Peter the Great St. Petersburg Polytechnic University
Higher School of Technosphere Security
Natkha Sergey
Oroeva Arina
PROTECTION AND
DECONTAMINATION
OF PERSONNEL
TUTORIAL
Saint-Petersburg
2022
PROTECTION AND DECONTAMINATION OF PERSONNEL
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CONTENTS
ABBREVIATIONS .........................................................................................................................5
INTRODUCTION ...........................................................................................................................6
1.
Personnel exposure pathways ..................................................................................................7
1.1.
Harmful and dangerous industrial factors .................................................................... 7
1.2. Formation of harmful and dangerous factors at individual industries, facilities and
enterprises ............................................................................................................................. 11
1.2.1.
Mining and processing of uranium ores ..................................................................11
1.2.2.
Chemical processing of uranium and its enrichment...............................................11
1.2.3.
Production of fuel elements and fuel assemblies based on uranium .......................14
1.2.4. Production of power-grade uranium from highly enriched weapons-grade uranium
(HEU-LEU technology) ........................................................................................................14
1.2.5.
Nuclear reactors .......................................................................................................15
1.2.6.
Radiochemical production .......................................................................................15
1.2.7.
Plutonium production ..............................................................................................15
1.2.8.
Disposal of nuclear weapons ...................................................................................16
1.2.9. Dismantlement of nuclear submarines, surface ships with nuclear power plants and
rehabilitation of contaminated territories ..............................................................................16
1.2.10.
2.
Methods of protection against external and internal radiation exposure ...............................19
2.1.
Protection against external radiation exposure .......................................................... 19
2.2.
Protection against internal radiation exposure ........................................................... 22
2.3.
Protection public in emergency exposure situation ................................................... 22
2.3.1.
Iodine blocking of the thyroid gland (ITB) .............................................................24
2.3.2.
Evacuation ...............................................................................................................24
2.3.3.
Shelter ......................................................................................................................25
2.3.4.
Resettlement ............................................................................................................26
2.3.5.
Prevention of accidental ingestion of radionuclides into the body by ingestion .....26
2.3.6.
Decontamination people ..........................................................................................26
2.3.7.
Limiting the consumption of food, milk and drinking water ..................................27
2.4.
3.
Elimination of consequences of radiation accidents ............................................16
Identification and medical care of exposed persons .................................................. 27
2.4.1.
Serious medical consequences.................................................................................27
2.4.2.
Emergency medical examination, consultations and treatment ..............................29
2.4.3.
Medical supervision .................................................................................................29
2.5.
Protection of international trade and commercial interests........................................ 29
2.6.
Termination or relaxation of response measures ....................................................... 29
Personal protective equipment...............................................................................................31
3.1.
The history of the creation of personal protective equipment ................................... 31
3.2.
Purpose of personal protective equipment ................................................................. 32
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3.3.
Classification of personal protective equipment ........................................................ 33
3.4.
Concepts of use personal protective equipment ........................................................ 35
3.5.
Respiratory protective devices ................................................................................... 35
3.5.1.
Protective Concepts .................................................................................................35
3.5.2.
Components of a Respirator ....................................................................................36
3.5.3.
Self-Contained Breathable Gas Styles .....................................................................42
3.5.4.
Tethered Supplied Breathable Gas Systems ............................................................42
3.5.5.
Air-Purifying (Negative-Pressure) Respirators .......................................................43
3.5.6.
Powered Air-Purifying Respirators .........................................................................44
3.5.7.
Emerging Concepts and Issues ................................................................................46
3.6.
3.6.1.
Components .............................................................................................................47
3.6.2.
Ensembles of personal protective equipment ..........................................................48
3.6.3.
Emerging Concepts .................................................................................................53
3.7.
4.
Future Concepts to Improve Performance in Use ...................................................... 57
Decontamination Technic ......................................................................................................59
4.1.
Decontamination basis ............................................................................................... 60
4.1.1.
Sources of Radionuclide Contaminants...................................................................60
4.1.2.
Behavior Characteristics of Radionuclides..............................................................60
4.1.3.
Surface Contamination Mechanism ........................................................................61
4.2.
5.
Dermal Protective Equipment (Clothing) .................................................................. 47
Recent Decontamination Technologies ..................................................................... 62
4.2.1.
Physical-Mechanical Methods.................................................................................63
4.2.2.
Chemical Methods ...................................................................................................67
4.2.3.
Electrochemical Method ..........................................................................................70
Decontamination in the radiological accident case ...............................................................72
5.1.
Decontamination of settlements................................................................................. 72
5.1.1.
Recommended decontamination technologies ........................................................74
5.1.2.
Justification and Optimization .................................................................................75
5.2.
Decontamination of people and personnel ................................................................. 75
5.2.1.
Harmful effects of emergency radiation exposure skin ...........................................76
5.2.2.
General protective actions in case of radioactive contamination ............................77
5.3.
Contamination Control .............................................................................................. 81
5.3.1.
Contamination Control Practices .............................................................................81
5.3.2.
Contamination Control of Exposed People .............................................................81
5.3.3.
General Guidelines for Operation of a Controlled Contamination Area .................82
5.3.4.
Factors influencing decontamination efficiency......................................................83
5.4. Impact of Responder Management Strategies on Public Experiences and Behaviour
During Decontamination ...................................................................................................... 83
5.4.1.
Getting People to Agree to Undergo Decontamination ...........................................83
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5.4.2.
Helping People to Undergo Decontamination Quickly and Efficiently ..................84
5.4.3.
Encouraging People to Cooperate with Each Other During Decontamination .......85
5.4.4.
Making People Feel Less Anxious ..........................................................................86
5.4.5.
Understanding the Needs of Vulnerable Groups .....................................................86
5.4.6.
Recommendations for Optimising Management of Mass Decontamination...........87
CONCLUSION .............................................................................................................................88
References .....................................................................................................................................89
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ABBREVIATIONS
APE
APR
CBRN
CHTS
DF
DR
DRF
DPE
EPE
EPA
ICPD
ICRP
ITB
HVT
NFC
NPP
OIL
PAPR
PAZ
PPE
RO
RPE
REE
SCBA
SNF
TVT
TMI
UPZ
WHO
– Air-Purifying Element
– Air-Purifying Respirator
– Chemical, Biological, Radiological and Nuclear Agents
– Chemical Hazards and Toxic Substances
– Decontamination Factor
– Decontamination Reduction
– Decontamination Reduction Factor
– Dermal protective equipment
– Eyes Protective Equipment
– U.S. Environmental Protection Agency
– Ingestion and Commodities Planning Distance
– International Commission on Radiation Protection
– Iodine Thyroid Blocking
– half value thickness
– Nuclear Fuel Cycle
– Nuclear Power Plant
– Operational Intervention Level
– Powered Air Purifying Respirator
– Precautionary Action Zone
– Personal Protective Equipment
– Respiratory Organs
– Respiratory Protective Equipment
– Rare Earth Elements
– Self-Contained Breathing Apparatus
– Spent Nuclear Fuel
– Tenth Value Thickness
– Three Mile Island (USA)
– Urgent Protective Action Planning Zone
– World Health Organization
SYMBOLS
Bq
Ci
Gy
eV
PACpers
Sv
– Becquerel
– Curie
– Gray
– electron Voult
– Permissible Activity Concentration for Personnel
– Sievert
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INTRODUCTION
In the general set of measures aimed at preventing the radiation impact on the public and
emergency workers of harmful and hazardous accident factors, as well as objects using nuclear
energy and enterprises included in this field of activity, the most important place is given to the
organization and implementation of a system of individual human protection.
The effectiveness of the use of personal protective equipment (PPE) largely depends on
their correct selection and operation. When choosing PPE, it is necessary to take into account the
specific conditions of an emergency process, the type, intensity and duration of radiation exposure
of the public and worker to harmful and hazardous factors.
The relevance of the use of PPE is especially increasing during emergency rescue
operations.
Only the correct use of PPE can provide the maximum protective effect from their use. To
do this, employees of organizations and enterprises should have information about modern, highly
effective, physiologically acceptable personal protective equipment.
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1.
Personnel exposure pathways
1.1.
Harmful and dangerous industrial factors
The most important factor of harmful and dangerous impact on the personnel of the nuclear
industry, reflecting its specifics, is radiation . This factor almost always manifests itself in two
forms:

exposure to external ionizing radiation;

exposure to radioactive substances, which also form doses of external exposure and at the
same time can get inside the body and be a source of internal exposure.
Since many radioactive substances are both chemically toxic and aggressive, the chemical
impact factor is inextricably linked with the radiation factor, and they must be considered together.
Other influence factors (mechanical, temperature, electromagnetic, etc.) are also, of
course, present in the nuclear industry, but they are not specific to it.
Radioactive and chemically toxic substances can enter the body in three ways:

through the respiratory system (inhalation route of entry);

through the skin (percutaneous route of entry);

through the mouth, gastrointestinal tract (oral route of intake).
With inhalation intake, rapid absorption of toxic substances into the blood is possible and
manifestations of both acute poisoning and their chronic effects.
With percutaneous intake, certain substances slowly penetrate into the body (for example,
metals, their oxides), while other substances can be very quickly absorbed through intact skin and
cause skin damage (for example, uranium hexafluoride, hydrogen fluoride). Through the wound
and burn surfaces, the absorption of radioactive substances can go much faster.
Air pollution with radioactive substances. The oral route of entry of harmful and
hazardous substances into the body is quite rare and, as a rule, is the cause of violations of labor
protection and safety regulations, as well as simple hygiene standards. At the same time, smoking
can contribute to a sharp increase in the penetration of harmful substances into the body due to
contact contamination of the lips, as well as ingestion of saliva and changes in the pattern of
deposition of harmful substances in the lungs. The oral route of entry is also characteristic of
substances that are actively included in the food chain. For example, radioactive iodine along the
chain "grass - cow - milk" can enter the body in large quantities (see Fig. 1.1).
Figure 1.1. All relevant exposure pathways.
Radioactive and chemically toxic substances can be in a condensed state (solid or liquid)
or in gas or vapor, as well as in aerosol (particles smaller than 50 microns) and cluster (particles
smaller than 50 m).
Gas – at ordinary (room) temperature, it cannot be condensed by compression. For
protection against gases, insulating PPE, gas masks and chemisorption overalls are used. Tritium
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is one example of a gas that is very difficult to protect against with personal protective equipment
due to its high penetrating power.
Steam - form substances that can be simultaneously in liquid (or solid) and gaseous phases
at ordinary (room) temperature. At ordinary temperatures, steam can condense when compressed.
Vapor protection is provided by filtering PPE by sorption, chemisorption or insulating
PPE.
Aerosol - a particle in the air with a liquid or solid dispersed phase with a size of 0.002 to
50 microns. The lower limit of the range (0.002 μm = 2 nm ) is determined by the ability of
molecules to repel from the surface, and the upper limit of the range (50 μm) is determined by the
rate of particle settling on a horizontal surface - particles larger than 50 μm settle very quickly and
cannot stay for a long time without wind blowing in the air). Protection against aerosols can be
carried out both by filtering the air or gas polluted by them, and by isolating the respiratory organs
and skin from the polluted environment.
A cluster is a particle in which the number of molecules (atoms) on its surface is
commensurate with the number of molecules (atoms) inside the particle itself. These particles
ranging in size from 2 to 40 nm have properties that differ significantly from the properties of the
condensed phase of solid and liquid substances and the properties of more coarsely dispersed
aerosols.
Nanoparticles were previously defined as particles with one of the linear dimensions less
than 50 or less than 100 nm. Currently, in international and domestic practice, it is customary to
call nanoparticles particles that have one of the linear dimensions less than 100 nm . But it is cluster
particles smaller than 50 nm that are the most dangerous.
The ways of formation of radioactive nanoparticles with cluster sizes from 0.002 to 0.02
µm are as follows:
The phenomenon of aggregate returns. When an alpha particle is emitted towards the depth
of the material, the atoms adjacent to the decayed atom receive recoil energy and having formed a
single conglomerate, break away from the surface and form a cluster particle.
In the case of 235U, the particles formed have a diameter of about 0.005 µm and contain
about 104 atoms. In the same way, fine aerosols of other highly toxic alpha emitters can appear:
210
Po, 238, 239Pu, etc.
Decay of inert radioactive gases. This produces aerosols with an average size of about 0.05
µm.
In uranium mines, the daughter decay products of radon are associated with particles with
a size of 0.001-0.04 microns.
Hydrolysis of volatile fluorides, organometallic compounds and decomposition of iron
pentacarbonyl. The resulting aerodisperse system consists of particles with an average size of 0.02
μm.
The radiation hazard of radioactive substances that have entered the respiratory tract
depends on the type of radiation emitted, the dispersion and chemical nature of the particles
themselves, in particular, on their solubility.
The choice of PPE of the respiratory organs (RO) should be carried out taking into account
the peculiarities of the formation and filtration of various aerodisperse systems.
It should be noted the extremely high toxicity of radioactive aerosols of many
radionuclides, the permissible weight concentrations of which in the air of the working area are
thousands and millions of times less than for the most toxic non-radioactive substances. Single
aerosol particles of these substances with a size of about 1 micron, located in 1 m3 of air, can create
an excess of permissible concentrations of tens of times or more than permissible activity
concentration for personnel (PACpers) of polonium. Therefore, to protect against radioactive
aerosols, it is necessary to use only highly effective PPE of the highest degrees of protection.
Dispersion of radioactive and other toxic aerosols is very important when assessing their
danger, monitoring their content in the breathing zone and air of the working zone, and when
choosing PPE for RO.
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Coarse aerosols larger than 5 microns are retained in the upper respiratory tract
(nasopharynx, bronchi and trachea). Particles ranging in size from 0.1÷1.0 microns are deposited,
as a rule, in the bronchioles. In this case, particles smaller than 5 microns can enter the alveoli, but
mainly particles with a diameter of 0.1 microns are deposited there. Moreover, more than 50% of
insoluble aerosol particles that enter the alveoli remain there forever.
Molecules of gases and vapours, penetrating into the lungs, can enter the bloodstream due
to gas exchange and then to various depositing organs, or can be removed from the body with
exhaled air.
Thus, when harmful substances enter the human respiratory organs, the total delay and their
distribution in the body depend on the dispersion and physicochemical nature of the particles.
At a filtration rate of 1 cm/s, particles with a size of 0.15÷0.17 µm are most likely to
penetrate through the air-purifying materials. At peak filtration rates through PPE RO reaching 10
cm/s, the most penetrating nanoparticles have a size of 0.03÷0.04 µm.
When working on open technological equipment (replacing containers, repairing valves
and plugs, etc.), directly in the breathing zone of workers, nanoparticles of cluster sizes from 0.002
are formed that are most difficult to catch with the help of aerosol filters and PPE, as well as poorly
analyzed using air-purifying filters, up to 0.02 µm.
Micropores of activated carbon, which effectively absorb vapors of toxic substances, have
a size of 0.001 to 0.002 microns with an upper limit of 0.003 microns. In mesopores, sorption
proceeds much worse. Therefore, particles of cluster sizes are worse than vapors of toxic
substances, are retained by anti-gas and anti -gas and aerosol filters.
Considering the above, in order to ensure reliable respiratory protection of personnel
performing work on the opened process equipment, local exhausts should be equipped at the place
of such work, and the personnel should be provided with hose insulating PPE RO.
If, according to the results of special studies of working conditions, it is shown that when
performing the above or similar operations, the concentration of radioactive and other toxic
aerosols, clusters and vapours does not exceed 100 permissible values, then instead of insulating
PPE RO, high-performance filtering PPE RO of the 3rd protection class can be used in in
accordance with the new Russian standards introduced from 01.01.2003.
Numerous studies have found a direct relationship between air pollution levels, indoor
surfaces and equipment. The quantitative characteristic of this relationship depends on a number
of parameters: physical and chemical properties of surfaces and radioactive contamination, type
and intensity of impact on the surface, etc.
To protect the respiratory organs from harmful substances, filtering and insulating means
of personal respiratory protection (PPE RO) are used.
Contamination of surfaces of premises and equipment. Contamination of surfaces of
premises and equipment with radioactive substances is dangerous as a source of skin
contamination, as a source of external exposure and as a secondary source of air pollution.
Protection of the skin from radioactive contamination is achieved through the use of basic and
additional overalls, insulating suits, hand protection, safety shoes, dermatological products.
Welding work. At all enterprises of the State Corporation "Rosatom" a large number of
works on welding and cutting of metal are carried out. In this case, a large amount of welding
aerosols and gas-vapor products are formed. Welding aerosols and gas-vapor products are of
particular danger when welding and cutting metals contaminated with radioactive substances.
The composition of gas-vapor products formed during welding depends on many factors,
but it usually includes the following substances: HF, SiF4, NO2, HCl, O3, SO3, CO, various
chlorine-containing organic substances, and others that are effectively sorbed on fine (from 0.001
to 1.0 µm) welding aerosols, which significantly increases the toxicity of the latter.
External gamma radiation. When carrying out repair, dismantling and emergency recovery
work at the enterprises of the nuclear industry and energy, it becomes necessary for personnel to
stay in gamma radiation fields that create the radiation power of the human body above the
permissible value. The greatest contribution to the dose rate of gamma radiation is made by such
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fission products as 95Zr, 95Nb, 103Ru, 106Ru, 137Cs, 140Ba, 140La. Of the activation products, 22Na,
24
Na, 60Co, 59Fe should be noted. The energies of the main gamma lines of these radionuclides are
in the range of 0.31.6 MeV.
To protect personnel from external gamma radiation, some developers have attempted to
create personal protective equipment, however, the available data on the attenuation factor of
gamma radiation with an energy of more than 100 keV by various materials indicate the futility of
such developments.
Protection of personnel from external gamma radiation can be ensured by reducing the
duration of work (“time protection”), performing work using remote devices (“protection by
distance”), as well as using protective walls, screens, booths, mats, etc.
External neutron radiation. An analysis of the possibility of creating PPE from external
neutron radiation leads to a similar conclusion. The neutron shielding material must contain
hydrogen or another light substance – to slow down fast and intermediate neutrons in elastic
scattering, heavy elements – to slow down fast neutrons in the process of inelastic scattering and
attenuate captured gamma radiation, as well as elements with a high ability absorption of thermal
neutrons. One of the best is a composition based on polyethylene with the addition of about 20%
lead. This material has a density of 3 g/cm3 and provides three times protection against fission
neutron radiation with a protective layer thickness of about 10 cm. This means that a suit made of
this material, protecting only three times, will weigh more than 300 kg.
External beta radiation. PPE can provide effective protection against external beta
radiation. The totality of calculated and experimental data indicates that the dose absorbed by the
radiosensitive layer of the skin and caused by beta radiation, when measuring the thickness of the
protective material in units of density surfaces (for example, g/cm2), is practically independent of
the type of material. But it must be taken into account that the absorption of beta particles in the
protective material gives rise to hard bremsstrahlung, the output of which increases with the growth
of the atomic number of the material. Therefore, it is advisable to make PPE for protection against
beta radiation from materials based on elements with a small atomic number. These are the
majority of polymeric materials. The thickness of the protective material should be between 0.3
and 0.7 g/cm2, depending on the energy of the beta radiation, which corresponds to a protective
suit weight of approximately 718 kg.
External alpha radiation and irradiation with photons with energies less than 100 keV.
Since the range of alpha particles in tissue -equivalent materials does not exceed 50 microns, and
in air – 5 cm, external exposure to alpha particles does not pose a serious danger.
Irradiation with low-energy photons (gamma and X-ray radiation with energies below 100
keV) is a significant factor in radiation exposure, and in the absence of harder components of the
photon radiation spectrum, polymeric materials containing rare earth elements (REE), lead,
barium, tin, tungsten, etc. The use of REE-filled materials is very promising for the protection of
medical personnel and patients during X-ray examinations due to the high efficiency of REE and
lower toxicity compared to lead traditionally used for these purposes. However, the use of such
materials when working with fissile isotopes is limited due to the possible ingress of REE into
processed products, which is unacceptable, since they are "neutron poisons", i.e. substances that
actively absorb neutrons. The use of uranium for protection against soft photons is impractical due
to the significant gamma radiation of uranium decay products, which create doses of gamma
radiation that exceed the allowable.
PPE to protect the lens of the eye. Currently, in most production areas, there is no need to
protect the lens of the eye from beta and gamma radiation. According to the ICRP Publication 103,
“the dose limit for facial skin irradiation ensures that the lens dose limit from beta particles is not
exceeded.” Therefore, at present, during normal operation of the equipment, special protection of
the skin and the lens of the eye is not needed.
The situation will fundamentally change after the introduction in Russia of new radiation
safety standards that take into account the new limits of eye lens doses recommended in the IAEA
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Basic Safety Standard (2011): the equivalent dose in the lens of the eye is 20 mSv per year,
averaged over five consecutive years (100 mSv for 5 years), and 50 mSv for any single year.
In this case, the lens of the eye becomes a kind of "critical organ" that limits the exposure
of personnel. Therefore, you will have to use special PPE to protect the lens of the eye from
radiation (shields or glasses).
The calculation of the optimal thickness of the material for protection against beta radiation
showed that the optimal material thickness is 0.40.5 g/cm2. Such a material provides a protection
factor in the range of 10 to 40, depending on the composition of the beta-active nuclides present
in the radiation source.
At the same time, it is necessary to introduce additives that effectively attenuate photon
radiation in the specified energy range into the layer of transparent polymeric material of the shield
or goggles that protect against beta radiation, located closer to the eyes. In the photon energy range
from 0.01 to 0.06 MeV, the most effective are some rare earth elements, tin, tungsten, barium and
lead.
Create glasses or shields that protect the lens of the eye from gamma radiation with an
energy of more than 0.1 MeV is impossible due to the large mass of the required protective layer.
1.2. Formation of harmful and dangerous factors at individual industries,
facilities and enterprises
Enterprises of the nuclear fuel cycle and the nuclear weapons complex are inextricably
linked with the raw material base and, first of all, with the uranium industry: uranium mining and
its primary processing.
1.2.1. Mining and processing of uranium ores
Uranium is the eighth most abundant metal in the earth's crust and is found in varying
amounts in almost all natural objects. It belongs to bioelements and is a part of organs and tissues
of animals and humans.
In the exploration, mining and processing of uranium ores, along with unfavorable
microclimatic conditions, noise, vibration, rock dust and other factors inherent in mining
enterprises, harmful and dangerous specific factors due to the special nature of the extracted
radioactive minerals are important. The sources of radiation impact factors in uranium mines are:

radionuclides that are part of mine dust suspended in the air (uranium, radium, polonium
and other radionuclides of natural origin);

radioactive gas radon and its daughter decay products in the mine air in the form of cluster
compounds and aerosol particles;

external gamma and beta radiation;

contamination of surfaces and water with radioactive substances.
In this case, the main danger is determined by the impact of radon and its short-lived decay
products, and when the concentration of uranium in the rock is more than 0.3% - by external
radiation. However, freshly purified uranium compounds do not contain radium or its derivatives.
When mining and processing uranium ores, acids and other chemically toxic and
aggressive substances are also used in large volumes.
1.2.2. Chemical processing of uranium and its enrichment
Chemical processing of uranium and its enrichment in uranium-235 in terms of the
formation of occupational hazard factors are not only radiation hazardous. First of all, this is a
large large-scale chemical industry, where there is a combined effect on workers of chemical and
radiation factors, both during the daily professional activities of a person, and in the event of
emergencies, when chemical exposure is decisive in individual industries. These primarily include
the production of fluorine, hydrogen fluoride and uranium hexafluoride (UF6) - sublimation plants,
the production of uranium enriched in the uranium-235 isotope - separation plants, as well as the
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initial sites for the production of fuel assembly, the production of processing irradiated nuclear
fuel by gas fluoride and etc.
At the enterprises of the nuclear materials industry, large contingents of people come into
contact with chemical compounds that are in various states of aggregation:

gaseous (UF6, MoF6, WF6, F2, HF, ClF3, freons, metal carbonyls, diethylzinc, etc.);

powdered (UF4, UO2F2, UO2(NO3)2 6H2O, U3O8), etc.
At sublimation and separation plants, the main occupational hazard factor is uranium
hexafluoride (UF6) and its hydrolysis products, primarily hydrogen fluoride.
The technological process of obtaining UF6 at the sublimation plant and enriched uranium
in the uranium-235 isotope at the separation plant is carried out in vacuum mode, except for the
areas of liquid UF6 overflow, where the devices are operated under pressure. Therefore, the
equipment used has a high degree of reliability and tightness. At the same time, the technological
process is not a closed continuous process and, under normal operation, is accompanied by the
opening of the internal volumes of equipment (cylinders, containers, etc.) and adjacent sections of
communications during the operations of disconnecting and connecting containers, accompanied
by the entry of highly volatile UF6 into the working area and other fluorine compounds. The
technological process is a source of formation of the radiation-chemical environment during
normal operation of the equipment and a source of increased chemical hazard in case of possible
accidents, accompanied by the release of UF6 into the air of the working area.
The features of the technological processes of sublimation and separation production
indicate a significant likelihood of leakage of gaseous uranium hexafluoride into the air of the
working zone (especially during its synthesis), as well as in the event of emergency
depressurization of containers.
There are also possible violations of the technological regime, safety regulations, as a result
of which gaseous fluoride compounds can enter the air of the working area, which can cause acute
intoxication of people. In this case, the severity of the lesion depends mainly on the concentration
of fluorine ion that has entered the body and the route of its intake (inhalation, percutaneous). The
absorption of fluorine ion through the skin is sufficient to cause a general systemic injury in an
emergency and lead to death if appropriate measures are not taken.
When in contact with air, uranium hexafluoride, as a rule, loses the properties of a solid or
liquid substance and passes into a vapor state with an evaporation rate that depends on the
conditions of its release into the air of the working zone.
Gaseous uranium hexafluoride has a high chemical activity. It is hydrolysed by air moisture
to form a fine aerosol of uranyl fluoride and gaseous hydrogen fluoride, which can be adsorbed on
aerosol particles.
UF6 + 2H2O = UO2F2 + 4HF
(1.1)
It has been proven that 90% of gaseous uranium hexafluoride is hydrolysed with a halflife of about 2 seconds. The remaining 10% of the total amount is characterized by several halflife components ranging from tens of seconds to several days.
The composition of air pollution by products of uranium hexafluoride hydrolysis depends
on the volume of the room, the amount of gas released into the air, its outflow rate, air temperature
and humidity. The long-lived fraction is a clustered state, i.e. uranium hexafluoride clusters are
formed in the air, each of which contains no more than 105 molecules, and the particle size does
not exceed 0.01 microns. These particles have a high penetrating power.
For the studied industries, it was found that the gas/aerosol ratio ranges from 1% to 90%,
with an average contribution of UF6 gas to the volumetric activity of air in the separation and
sublimation industries - 40% and 60%, respectively.
Due to its high mobility and chemical activity, the UF6 compound in molecular form is
sorbed in the human upper respiratory tract, and cluster and aerosol particles penetrate much
deeper into the lungs.
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All this leads to the deposition in the lungs proper of about 20% of the inhaled activity
during long-term exposure.
The amount of hydrogen fluoride formed at the initial moment of the UF6 release is zero,
but by 10-20 minutes it is about 5% by weight of the uranium concentration. Uranium and fluorine
ion can enter the body in three ways: inhalation, percutaneous and oral. A decisive influence on a
person, when the respiratory organs are protected by a gas mask, is exerted by the percutaneous
route of fluorine ion intake.
Far from the source of release, the inhalation intake of uranium is mainly due to aerosol
particles. When a person is near the source at the time of release, for example, when connecting
containers, replacing valves , etc. up to 100% of gaseous uranium hexafluoride, whose share in the
release can vary between 10-100%, is retained mainly in the upper respiratory tract, depending on
the time elapsed from the start of the release. With a purely inhalation intake of hexafluoride and
its hydrolysis products, uranium predominates in the body, and the amount of fluorine (by weight)
does not exceed 20% of the incorporated uranium, although it can also retain a value that
determines the biological effect.
With percutaneous intake, the resorption of uranium into the body does not exceed
hundredths of a percent, while fluorine, the source of which is UF6, UO2F2, UOF2, HF, is absorbed
at the level of tens of percent of what has entered the skin. Consequently, 20100 parts of fluorine
fall on one part of the absorbed uranium. The closer the worker is to the source, the greater the
importance of the percutaneous route of fluoride entry into the body, since the proportion of UF6
and UOF4 is large here. Far from the source, the supply of fluorine is due to its release from UOF4
and UO2F2. Effective protection of the respiratory organs, as well as the difference in resorption,
predetermines the leading significance of the intake of fluorine ion through the skin. Therefore, it
is necessary to take measures to prevent the deposition of UF6 on the skin and to protect it.
The use of regenerated raw materials in the technological process has led to the emergence
of mainly two new factors: 239Pu and 232U. The share of Pu in the alpha activity of aerosols can be
much higher than the corresponding value in raw materials and reach several percent. This is due
to the concentration of Pu in certain sections of the technological process. In addition, one more
circumstance should be taken into account. At a sublimation plant with high-temperature methods
for obtaining UF6 from regenerated raw materials, the critical compound in the air of working
rooms, along with uranium hexafluoride, is plutonium hexafluoride, the kinetics of which in air is
similar to UF6 with all the ensuing consequences. In the air of the working area of the sublimation
plant, PuF6 was found at a level of 8÷20% of the alpha activity of the gas fraction.
Considering that the PACpers for plutonium in air is set to be more stringent than for
uranium, the radiation hazard from Pu aerosols in some cases can be commensurate with the
radiation hazard from uranium aerosols and even exceed the latter.
The second professional factor due to the raw material is 232U. The content of 232U in the
raw material as a whole should increase with time. In addition, not only the 232U isotope itself is
dangerous due to its greater toxicity, but also its daughter products due to the formation of thoron
and hard penetrating radiation, including gamma rays with an energy of 2.62 MeV.
When working with highly enriched uranium, personnel may be exposed to neutrons due
to the (α, n) reaction on fluorine.
Thus, production facilities with fluoride technology are characterized by a combined effect
on working toxic substances (fluorine, hydrogen fluoride) and such radiation factors as alphaactive aerosols, gaseous UF6, PuF6, external beta, gamma and neutron radiation.
The main role in the air pollution of the working area belongs to uranium isotopes and its
decay products when using natural uranium and isotopes of uranium and 239Pu when using raw
materials of the different types.
Areas with UF6 are of paramount importance in terms of exposure to the gas. Since the
technological process is carried out in sealed equipment, the main sources of air and surface
contamination with radioactive substances are operations accompanied by the opening of internal
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cavities of communications and equipment, and current repair work. This determines the complex
of protective measures and the choice of PPE sets for personnel.
Currently, centrifuge separation technologies produce a large number of stable isotopes. In
this case, volatile fluorides and organoelement compounds are used.
1.2.3. Production of fuel elements and fuel assemblies based on uranium
In the manufacture of fuel elements based on uranium, personnel are exposed to external
gamma, beta, neutron irradiation, as well as internal irradiation due to the intake of alpha-active
aerosols of various nature, radioactive gases and vapors (UF6, 220Rn) through the respiratory
system. The presence, levels of exposure and dose implementation of radiation factors in the
production of fuel rods depend on the type of raw material, the chemical form of raw materials,
semi-products, waste and finished products, the degree of enrichment in 235U, technology and its
organization, the operation performed and the time it takes to complete, the level of the radiation
safety system and overall safety culture.
Gamma irradiation takes place in all operations to produce fuel elements. When working
in separate rooms with sheathed By fuel elements and assembly of fuel assemblies, gamma
radiation is the only factor of radiation exposure.
Exposure to beta particles should be taken into account when working with open materials
from uranium depleted in 235U, with a natural content of 235U and from uranium of low enrichment
in 235U (works with metallic uranium, visual control of fuel pellets, loading of fuel pellets in a
sintering furnace). Irradiation with beta particles is not ruled out when working with medium- and
highly enriched metallic uranium due to the effect of 234Th and 234Pa isotopes of the uranium family
234
Th and 234Pa floating to the surface of freshly smelted metal. The hands (skin of the palms) are
exposed to the greatest exposure. The dose of beta radiation to other parts of the body can be
ignored.
Neutron radiation occurs when working with enriched uranium. The highest values of
neutron radiation dose rates were noted during operations with enriched uranium hexafluoride due
to the (α, n) reaction on fluorine atoms.
Air pollution with radionuclides occurs when performing dusty operations. Alpha-emitting
isotopes with high specific activity represent the greatest danger of internal exposure. Due to the
increase in the total alpha activity per unit mass, the radiation hazard increases in the series U
depleted . < U nat < Un.rev < Us.rev < Uv.rev.
When connecting-disconnecting containers with uranium hexafluoride, one should take
into account the non-hydrolyzable fraction of uranium hexafluoride released into the air of the
working zone. This fraction has a unique penetrating ability – it completely passes through the
Air-Purifying Respirators (APRs). Therefore, under these conditions, the use of gas and aerosol
respirators of the Petal B type is required.
1.2.4. Production of power-grade uranium from highly enriched weapons-grade uranium
The instrumentation of the technological process of processing “High enriched uranium
(HEU)– Low enriched uranium (LEU)” limits the flow of radioactive substances into the air of the
working area. The processes of processing HEU metal, extraction purification of highly enriched
uranium nitrous oxide, its fluorination to highly enriched uranium hexafluoride, condensation,
evaporation and mixing of uranium fluoride compounds are carried out in boxes, process tanks
and collectors at subatmospheric pressure.
However, carrying out such operations as loading and unloading from boxes, a fluorinator
reactor , connecting - disconnecting tanks on evaporation and condensation collectors, training and
washing, replacing metal-ceramic filters and valves, as well as carrying out an inventory of tanks
and stripping equipment can lead to significant air pollution and, accordingly, to internal exposure
due to alpha radiation of 232,234,235,236,238U, 228Th, 239Pu, 237Np, located in the aerosol component
and gas component of radioactive contamination of air in the working area, as well as thoron and
its decay products.
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External exposure of personnel is determined by gamma radiation of 228,234Th, 235, 238U and
their decay products, neutron radiation resulting from -n - reactions on atoms of light elements,
mainly fluorine, and beta radiation beta-active decay products of uranium isotopes.
1.2.5. Nuclear reactors
The main factors of radiation impact on the personnel of nuclear reactors are gammaneutron radiation, radioactive gases and aerosols, contamination of the surface of equipment,
building structures, overalls and skin.
A nuclear reactor is a powerful source of gamma radiation, created mainly by radioactive
fission products of nuclear fuel, which, depending on the physical and chemical state, are divided
into the following groups:

radioactive isotopes of noble gases: xenon, krypton, argon;

volatile substances: iodine, partly caesium, ruthenium, etc. (in the event of an accident,
they account for more than half of the emissions and are primarily powerful sources of radiation);

non-volatile substances: strontium, zirconium, ruthenium, cerium, lanthanum, etc.
When the reactor is shut down and cooled down, neutron radiation is practically absent,
and the main source of gamma radiation is long-lived fission products and structural elements
activated by neutrons. During the period of scheduled preventive maintenance on the opened
reactor equipment, the volumetric activity of aerosols increases sharply, which requires reliable
protection of the respiratory organs and skin.
The average isotopic composition of alpha-emitters in air samples and smears from the
surface of equipment and the floor of industrial reactors is determined by isotopes 244Cm, 242Cm,
238
Pu, 241Am, 239-240Pu with their percentage by activity of 88.7; 6.9; 2.6; 0.5 and 1.3, respectively.
The annual inhalation intake of radionuclides into the body of personnel is formed mainly
during the periods of repair work and, as a rule, is significantly less than 50% of the maximum
permissible limit for α-active radionuclides.
If during the normal operation of reactors there is practically no need for individual
protection against iodine, then in case of accidents, the iodine problem becomes one of the main
ones, both due to inhalation intake and oral intake with milk through the food chain.
1.2.6. Radiochemical production
Taking into account the radiation properties of the raw materials being processed, the main
products obtained and radioactive waste, the radiation impact on personnel is due to gamma
radiation from fission fragments; gamma radiation accompanying the decay of transuranium
elements; gamma radiation accompanying the decay of isotopes of uranium and its daughter
products; beta radiation from fission fragments and daughter decay products of uranium; neutron
radiation due to spontaneous fission of plutonium and ( - n)-reaction on the nuclei of light
elements.
Internal exposure can occur due to inhalation of alpha-emitting isotopes of uranium and
plutonium, beta-emitting 241Pu; gamma and beta emitting fission fragments and alpha emitting
228
Th and its decay products.
Gamma radiation is most significant in areas for receiving irradiated standard uranium
blocks and in the machine rooms of production, especially near the head extractors.
Neutron radiation is the main dose -forming factor when working with the end product plutonium dioxide.
1.2.7. Plutonium production
Due to its high radiotoxicity, the production of plutonium in the nuclear fuel cycle (NFC)
is among the most radiation hazardous.
The main unfavorable factors of the production environment in the production of
plutonium and in the processing of products from it are:
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
alpha-active aerosols;

contamination with alpha -active substances of the surface of premises, equipment, overalls
and other personnel PPE;

the presence of external gamma-neutron radiation, including soft photon radiation emitted
241
by Am, which in many cases accompanies plutonium, being formed due to the beta decay of
241
Pu.
1.2.8. Disposal of nuclear weapons
At enterprises, depending on the nature of the work performed, there are three groups of
key personnel:

persons performing dismantling operations;

persons involved in the processing and processing of products;

persons serving the premises for the storage of fissile materials.
Personnel in the process of dismantling ammunition are exposed to the combined effects
of radiation and physical factors (non-radiation nature). The nature of the formation of dose loads
on the personnel involved in the disposal of nuclear weapons has pronounced specific features in
comparison with enterprises of the nuclear fuel cycle. Dismantling operations are predominantly
manual, ammunition has a different design, dimensions, changing radiation characteristics of
individual components and parts, which creates non-uniform radiation fields in the working areas.
Personnel are exposed to combined predominantly external and internal exposure.
Additional factors of radiation impact on personnel should be considered the possibility of
formation of a local cloud of radioactive aerosols from corrosive formations.
1.2.9. Dismantlement of nuclear submarines, surface ships with nuclear power plants and
rehabilitation of contaminated territories
When dismantling nuclear submarines, surface ships with nuclear power plants , nuclear
service vessels and remediation of contaminated areas, personnel are exposed to a complex of
radiation and chemical factors.
When carrying out these works, personnel are exposed to external gamma, beta and neutron
radiation.
When cutting various metal structures, a large amount of radioactive substances is released
into the air in the form of mainly fine aerosols, as well as toxic chemicals in the form of gases,
vapors and aerosols. The demolition of various construction sites, the collection of contaminated
soil lead to the formation of a large amount of dust containing radioactive and chemically toxic
substances.
The main feature of the working conditions of personnel is the performance of a large
amount of radiation - hazardous work in the open air under adverse climatic conditions and low
temperatures. Due to the lack of information about the specific parameters of objects being
disposed of and accumulated radioactive waste, there is an increased risk of emergency situations,
which must be taken into account when organizing individual and collective protection of
personnel involved in RW conditioning.
Currently, large-scale work is underway to eliminate the nuclear legacy. The problems with
the protection of personnel who carry out these works are only partly the same as in the
dismantlement of nuclear submarines, but they require the solution of special issues of ensuring
the safety and protection of personnel for various groups of enterprises and technologies.
1.2.10. Elimination of consequences of radiation accidents
To eliminate the consequences of radiation and chemical accidents, nuclear industry
organizations created, trained and certified professional emergency rescue teams, non-standard
emergency rescue teams, and special emergency teams.
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All emergency hazardous facilities of nuclear energy and industry in terms of the formation
of emergency PPE kits can be divided into four types:
I.
Radiochemical production, storage of radioactive waste, radionuclide sources
based on beta-gamma-active nuclides, nuclear weapons based on uranium.
The emergency at these facilities is characterized by the release of beta-gamma-active
nuclides and the corresponding surface and air pollution, high levels of external beta- and gammaradiation. It is necessary to use highly effective PPE that protects the respiratory organs from
radioactive aerosols and the skin from radioactive contamination. It is also necessary to use PPE
to protect the skin and especially the lens of the eye from external beta radiation. Protection from
external gamma radiation is ensured by regulating the time spent in fields of intense gamma
radiation, remote work, the use of protective screens, walls, boxes, etc.
II.
Operating nuclear reactors (nuclear power plants, transport power plants,
research reactors), initial sites of radiochemical production, preparations containing radioactive
iodine.
The emergency situation at these objects is characterized by the same parameters as for
objects of type I. The main feature is the presence of radioactive isotopes of iodine in the
composition of the release - this requires the use of gas and aerosol (sorption-filtering) PPE of the
respiratory organs (PPE RO), protecting against aerosols, vapours of radioactive iodine and its
compounds.
III.
Plutonium production, radionuclide source or other facility containing plutonium
isotopes, plutonium-based nuclear weapons.
The emergency situation is characterized by contamination of air and surfaces with highly
toxic isotopes of plutonium, which are dangerous primarily when entering the human body and
the absence of significant fields of beta, gamma, and neutron studies. In the early phase of an
accident, it is necessary to use highly effective PPE for the respiratory organs and skin (mainly
insulating PPE for the OD and skin).
IV.
Industries using or "producing" uranium hexafluoride and other fluorides.
The emergency situation is characterized by the release of uranium hexafluoride into the
air. When it decomposes and hydrolyses in air, fluorine, hydrogen fluoride and toxic aerosols are
formed that affect the respiratory system and skin. It is necessary to use insulating PPE, a gas mask
of the GF brand and PPE of the skin, preventing the entry of fluorine-containing compounds
through the skin.
The type of radiation hazardous production determines the specifics of the use of PPE.
Personnel performing work to eliminate the consequences of a radiation accident are
divided into two categories: the first category is rescuers; the second category is repair personnel
(liquidators). Depending on these categories, conditions of use, PPE sets are divided into two
types, differing in levels of protective properties:

a set of PPE of the first type for the protection of emergency rescue teams in an unknown
or insufficiently known radiation situation (the first category of workers is rescuers);

a set of PPE of the second type to protect repair teams and recovery units (the use of PPE
of the first type is also not excluded) - the second category of workers - repair personnel,
liquidators.
The personnel of the emergency response teams perform emergency work in the early
phase of a radiation accident, in the context of the ongoing release of radioactive substances and
significant exposure to chemical, thermal and other factors requiring the use of adequate personal
protective equipment. Insufficiency of information about the levels of radioactive and chemical
contamination of air and surfaces in the accident zone, the likelihood of deterioration of the
emergency situation requires choosing PPE with the necessary margin of efficiency. The following
types of personal protective equipment are recommended for emergency response personnel:

for respiratory protection - highly effective insulating PPE of the respiratory organs insulating open-type breathing apparatus for compressed air, insulating regenerative breathing
apparatus for compressed or chemically bound oxygen;
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
to protect the skin - in addition to the main set of overalls, additional overalls made of film
or laminated materials (at medium levels of contamination) and insulating suits should be used at high levels of radioactive or chemical contamination, and, if necessary, overalls made of
chemisorption materials that capture fluoride hydrogen, uranium hexafluoride and products of its
hydrolysis.
The personnel of the recovery units perform work at the intermediate phase of a radiation
accident, under the conditions of the termination of the release of radioactive substances, the
formed trace of radioactive contamination and sufficient knowledge of the radiation situation in
the areas of restoration work.
With sufficient knowledge of the emergency situation (the level of radiation and (or)
chemical contamination), it is allowed to protect the respiratory organs:

the use of filtering means of personal respiratory protection – high-performance light
respirators, respirators with a rubber half-mask, as well as filtering gas masks equipped with highly
effective gas and aerosol filters;

to protect the skin - in addition to the main set, it is recommended to use additional overalls
made of film or laminated materials.
If there is some time to prepare for recovery work, it is recommended to use hose PPE, as
well as PPE of the respiratory organs and skin with self-contained breathing apparatus (SCBA)
systems, which allow continuous (up to 6 hours or more) to carry out work to eliminate the
consequences of emergencies.
With a sufficiently high level of exposure to harmful and dangerous factors for the
personnel of the recovery units, the first (high) level of protection can also be used.
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2.
Methods of protection against external and internal radiation exposure
To receive radiation from radioactive materials is called radiation exposure. On the other
hand, radioactive contamination means that matter, including people and places, is contaminated
with radioactive materials. In other words, radioactive contamination suggests that some
radioactive materials exist in places where radioactive materials do not usually exist.
To receive radiation from radioactive materials outside the body is called external
exposure.
If a person breathes in radioactive materials in the air or takes contaminated food or drink
into their body, he/she will be exposed to radiation from inside their body. In addition, radioactive
materials can also enter the body from wounds. Receiving radiation in this way is called internal
exposure.
Figure 2.1. Types of radiation exposure.
In the event of a large nuclear accident, external and/or internal exposures result from
various pathways (see Fig.2.1). External exposure results from airborne radioactive material
present in the plume discharged by the damaged installation, and from radioactive material
deposited from the plume on to the ground, buildings, clothing, and skin. Internal exposure results
from the inhalation of radioactive material from the plume or resuspended from contaminated
surfaces, from the ingestion of contaminated food and water, and from inadvertent ingestion of
radionuclides on the ground or objects.
2.1.
Protection against external radiation exposure
External exposure occurs when all or part of the body is exposed to a penetrating radiation
field from an external source. During exposure this radiation can be absorbed by the body or it can
pass completely through, similar to a chest x-ray. Note that exposure to a radiation field does not
cause an individual to become radioactive; the radiation exposure ceases as soon as the individual
leaves the radiation field.
All ionizing radiation sources produce an external radiation field. However, some fields
are so small they pose no external radiation risk at all. Examples include these low and moderate
energy beta radiation emitters: 3H; 14C; 63Ni; 33P; 35S.
Other sources of ionizing radiation produce much higher energy external radiation fields,
and care must be taken to shield the source and to monitor exposure while working near these
sources. Examples include:
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 241Am/Be neutron sources;
 32P beta sources;
 137Cs gamma sources;
 60Co gamma sources;
 X-ray machines (only when the machine is energized).
Time, distance, and shielding measures minimize your exposure to radiation in much the
same way as they would to protect you against overexposure to the sun (as illustrated in the Fig.
2.2):
Time: For people who are exposed to radiation in addition to natural background radiation,
limiting or minimizing the exposure time reduces the dose from the radiation source.
Distance: Just as the heat from a fire is less intense the further away you are, so the intensity
and dose of radiation decreases dramatically as you increase your distance from the source.
Shielding: Barriers of lead, concrete, or water provide protection from penetrating
radiation such as gamma rays and neutrons. This is why certain radioactive materials are stored
under water or in concrete or lead-lined rooms, and why dentists place a lead blanket on patients
receiving x-rays of their teeth. Similarly, special plastic shields stop beta particles, and air stops
alpha particles. Therefore, inserting the proper shield between you and a radiation source will
greatly reduce or eliminate the dose you receive.
Figure 2.2. Protective measures against external radiation
In all applications of ionizing radiation, the radiation dose to the users, and to others in the
vicinity, must be kept as low as reasonably achievable and, in any case, below national dose limits.
This is also possible by using a source which is the most suitable for the particular application. As
radioactive sealed sources and machines involve only an external hazard they are, in general,
preferable to open sources. The hazard is further minimized by choosing a source of sufficient
activity, and the most appropriate radiation energies for the application.
Physical means exist to ensure that: exposure times are kept to a minimum; barriers remain
in place to keep people away from the hazardous areas; and shielding materials are in place before
a source can be exposed. These engineered controls are preferable to administrative controls which
rely on individuals obeying instructions not to remain longer than necessary near sources, not to
pass barriers, and to use shielding materials.
A shielded enclosure is an enclosed space engineered to contain ionizing radiation and to
provide adequate shielding for persons in the vicinity. They range in size from relatively small
cabinets, for example to contain the X ray (machines used to examine unopened mail and baggage;
through walled compounds in which radiography is carried out; to large chambers in which very
high doses are delivered for irradiation purposes such as disinfestation, sterilization and the
induction of changes in the matter being irradiated. An enclosure is essential for work with a
radiation source that has a high dose rate output. To rely on distance alone to reduce the dose rate
would require a prohibitively large exclusion zone. Similarly, other sources need to be suitably
enclosed to be used close to areas that are either occupied, or to which persons have a right of
access.
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The design principles are similar for all enclosures although different characteristics are
incorporated depending on whether the enclosure is to be suitable for X ray, gamma or neutron
radiation.
Sufficient shielding will be required to reduce the accessible, transmitted dose equivalent:
rates to an acceptable level, for example 7.5 µSv/h. There may be a need for a controlled area
outside an enclosure (see Fig. 2.3).
The amount of shielding needed, and consequently the cost, can be minimized by
restricting the number and area of internal surfaces that primary radiation is allowed to strike. This
higher energy radiation will need primary barriers, which are either comparatively thicker or made
using different materials. The restrictions can often be achieved by collimating the radiation
source, that is reducing and shaping the radiation to a useful beam which can then be directed only
towards suitable barriers.
Figure 2.3. The transmission factor as an indication of the effect of the primary barrier.
To estimate the necessary thickness of a primary barrier its transmission factor T must first
be calculated. If D1, is the maximum dose rate to be allowed (for example 7.5 µSv/h) at a position
close to the outside surface of the barrier and D2 is the dose rate at the same place when the barrier
is not there, then T is equal to D1, divided by D2. To calculate D2, the enclosure's designer will
need design parameters, which are basic assumptions about:

which radionuclides or machines are to be used;

the upper limit of activity of the radioactive source or the electrical parameters of the
machines that can be used;

the minimum distances between the radiation source and the barrier's internal surface.
An accurate estimate of the thickness of the shield needed requires transmission graphs
which are published for different radionuclides (and machine parameters) and different shielding
materials. However, a simplified estimation of the primary barrier's thickness which may tend to
overestimate the shielding is possible. If the calculated transmission factor, D1/D2, is one-tenth
then a primary barrier equivalent to a tenth value thickness (TVT) is used; to obtain a reduction of
one hundredth, two TVTs are used; for a reduction of one thousandth, three TVTs are used; and
so on. The HVTs (half value thicknesses) and TVTs are dependent on the primary radiation's
energy.
Table 2.1. Typical primary barrier thicknesses
Radiation source
Industrial X-ray (250 kV)
Iridium-192 (1 TBq)
Cobalt-60 (185 GBg)
Linear accelerator (8MV)
Typical primary barrier thicknesses
Lead (mm)
Concrete (cm)
10
50
70
60
180
80
300
200
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2.2.
Protection against internal radiation exposure
Internal exposure occurs due to radioactive materials being taken in the following routes:
ingestion together with food (ingestion); incorporation while breathing (inhalation); absorption
from the skin (percutaneous absorption); penetration from a wound (wound contamination), and
administration of radiopharmaceuticals through injection, etc.
Radioactive materials incorporated into the body (see Fig. 2.4) emit radiation within the
body. Accumulation in some specific organs may occur depending on the types of radioactive
materials.
This is largely due to the physicochemical properties of radioactive materials. For example,
strontium, having similar properties to calcium, tends to accumulate in calciumrich parts such as
bones once it enters the body; cesium, because of its properties similar to potassium, tends to
distribute throughout the body once it enters the body.
Iodine, being a constituent element of thyroid hormones, tends to accumulate in the thyroid,
whether it is radioactive iodine or stable iodine
Figure 2.4. Processes lead to internal exposure.
2.3.
Protection public in emergency exposure situation
When responding to an emergency situation at the facility, protective actions and other
response measures of two categories can be carried out:

Urgent protective actions and other responses must be taken quickly (usually within hours)
to be effective; in the event of a delay, their effectiveness will be significantly reduced. Urgent
protective actions and other responses include iodine thyroid blocking (ITB), evacuation, shortterm shelter, actions to reduce the likelihood of inadvertent ingestion of radionuclides (probability
of accidental ingestion), human decontamination, prevention of consumption of potentially
contaminated food, milk or water, identification of persons in need of a medical examination;
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
Early protective actions and other responses can be implemented within days to weeks and
still be effective. The most common early protective actions and other responses include
relocation, long-term restriction of consumption of contaminated food, and registration of
individuals in need of medical supervision.
These measures can be initiated in two ways. According to the first of them, the
implementation of measures within the boundaries of predetermined emergency zones and
distances begins after the announcement of a general emergency, and in accordance with the
second method, measures are taken after the release based on monitoring data.
Urgent protective actions and other response measures taken in relation to the population
in the event of a general emergency:

Instruct people in the PAZ to immediately take a thyroid iodine medication (if this does
not delay evacuation), reduce the chance of inadvertent ingestion of radionuclides (probability of
accidental ingestion), and conduct safe evacuation outside the UPZ. Conducting a safe evacuation
means that the lives of the evacuees are not endangered. Patients and persons in need of medical
assistance should be evacuated outside the RRS so that a second evacuation is not required.
Evacuation should not be delayed on the grounds that a release is ongoing. It is recommended that
you do not drink, eat or smoke, do not put your hands to your mouth unless they are washed, do
not play on the ground, and do not do other activities that can lead to the formation of dust that
can enter the body.

Instruct people in the UPZ:
 immediately before evacuation, stay indoors (in a shelter on the spot), take an iodine drug
for ITB, reduce the likelihood of accidental ingestion of radionuclides into the body by oral
route;
 if there is a possibility of a serious release to the atmosphere, instruct the public to safely
evacuate outside the UPZ as soon as possible without delaying the evacuation of the public
from the PAZ. If immediate evacuation is not possible (for example, due to snowfall,
flooding or lack of transport or from special facilities such as hospitals), the population
should remain sheltered in a large building, if possible, only for a short period until safe
evacuation is possible. Workers in special facilities (facilities whose occupants cannot be
evacuated immediately (e.g., hospitals, nursing homes, prisons), facilities necessary to
support a response (e.g. communications facilities), or facilities where protection is
required to prevent other hazards (e.g., chemical facilities)) should be counted and
protected as emergency workers as part of the emergency preparedness process.

Instruct people in the PAZ and UPZ who cannot be safely evacuated to immediately take
an iodine drug for the ITB, go inside the building (if possible, stay in the shelter of a large building),
close doors and windows, listen to radio or television to receive further instructions. It is necessary
to carry out preparatory actions in advance when introducing an emergency plan to control the
dose rate in special institutions (for example, in hospitals), for which the initial ̆ protective will be
the requirement to remain in shelter.

Instruct those responsible for transport systems (air, land, sea) to avoid the UPZ.

Instruct people in RRS to reduce the likelihood of inadvertent ingestion of radionuclides
by ingestion prior to assessing deposition levels.

Within the boundaries of the RPPT, give instructions:
 transfer animals to protected (for example, sheltered) feeds as necessary and possible;
 protect food and drinking water sources (for example, turn off rainwater collection pipes);
Food grown outdoors can be directly contaminated by release.
 cease consumption and distribution of locally produced non-essential products, wild plants
and game (e.g., mushrooms and bushmeat), grazing milk, rain water and animal feed until
concentration levels can be determined using the OIL criteria;
 stop distributing goods until the evaluation is carried out;
 put in place controls to ensure that all goods sold meet international standards and reassure
all interested parties (e.g., other states) that appropriate controls are in place.
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
Ensure registration and monitoring, decontamination and medical screening and dose
assessment of individuals in the PAZ and UPZ to determine the need for medical examination or
counselling and follow-up.
2.3.1. Iodine blocking of the thyroid gland
When a large amount of radioactive iodine is released, people can inhale enough
radioactive iodine to damage the thyroid gland and greatly increase the chance of developing
radiation-induced thyroid cancer. In addition, there may be serious consequences for the health of
the fetus associated with the dose of fetal exposure from the fetal thyroid gland at a concentration
of radioactive iodine in it (the thyroid gland of the fetus begins to function after the 10th week of
pregnancy). Severe health effects are severe deterministic effects and stochastic effects, i.e. cases
of radiation-induced cancers.
Thyroid uptake of inhaled radioactive iodine can be reduced by taking stable (nonradioactive) iodine. This is called the thyroid gland blocking with iodine preparations or iodine
prophylaxis, since non-radioactive iodine ensures saturation of the thyroid gland, which
significantly reduces the absorption of radioactive iodine. For iodine prophylaxis to be effective,
a non-radioactive iodine preparation must be taken before or shortly after the intake of radioactive
iodine (within 2 hours after inhalation of radioactive iodine or its intake through the
gastrointestinal tract). Doses from radioactive iodine inhalation in victims may be large enough to
cause severe deterministic effects in the thyroid gland and fetus, and sheltering or evacuation after
the release has begun may not provide sufficient protection to prevent these effects. Thus, in order
to reduce the likelihood of these effects, it is necessary to pre-distribute the drug for ITB with
instructions for use, so that people at home, at schools, at workplaces, in hospitals and other special
institutions, can take it immediately after the announcement of a general emergency situations
(detection of conditions at nuclear power plants indicating the possibility of a release). Predistribution is necessary because it may not be possible to distribute the ITB drug during an
emergency quickly enough for it to be effectively administered. The reason is that the time when
the radioactive - release, impossible to predict, release can occur at any time after damage to the
core.
WHO recommends that, in the absence of explicit instructions from the health authorities
for a different route of administration, only one dose of an iodine preparation for the thyroid gland
should be taken. A single dose of the drug is usually sufficient for adequate protection within 24
hours. In the event of prolonged or repeated exposure, health authorities may recommend more
than one dose of an iodine thyroid medication. At the same time, new-borns (up to 1 month old)
and pregnant and lactating women should not take repeated doses of an iodine drug for ITB.
Multiple use of an iodine preparation for ITB cannot be a substitute for evacuation in a
situation of prolonged exposure (more than 24 hours). Iodine drug is taken to provide protection
until a safe evacuation is organized and carried out.
ITB is safe and effective if stable iodine is used in the correct dosages. In this regard, it is
necessary to follow the recommendations of the World Health Organization (WHO).
2.3.2. Evacuation
Pre-release evacuation can prevent exposure through all possible human exposure
pathways. In addition, when people are evacuated, they leave the area of the accident, and in
relation to them, the persons managing the response actions will no longer need to take urgent
measures.
As stated earlier, timely evacuation, initiated prior to a release, in combination with iodine
BTC is the preferred protective measure in the event of an emergency. This is necessary to prevent
severe deterministic effects and exposures in excess of international general criteria that require
urgent protective action ̆ or other response actions.
It is stated that sheltering in a large building can prevent lethal exposure, and also provides
a significant reduction in all doses; therefore, if evacuation is delayed or immediate evacuation is
not possible (e.g. due to snowfall, flooding, lack of vehicles, or in the case of special institutions
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such as hospitals), people should remain sheltered in large buildings as long as possible until a
safe evacuation is possible.
There may be problems with possible traffic jams or "shadow evacuation" (informal,
unorganized evacuation undertaken on their own by people who are outside the area where
evacuation is officially recommended), leading to a delay in evacuation from the PAZ. For this
reason, it is recommended to carry out the evacuation in stages.
Evacuating faster than walking speed (approximately 5 km/h), even while in a cloud or
plume (i.e. at the time of release), is more efficient than shelter, and since a release can occur over
several days, evacuation should not be delayed on the grounds that a release is ongoing if it can be
carried out safely.
Evacuation is a safe measure and is often used in response to natural and man-made
emergencies. Experience has shown that local officials can quickly organize evacuations without
prior planning. However, it may pose a risk to special populations (e.g. hospital patients) if not
properly planned.
Evacuees should take a ITB iodine medication, if it can be done without delaying
evacuation, to provide protection against inhalation of radioactive iodine from the passing cloud.
2.3.3. Shelter
Consider two different types of shelter:
"in place" shelter, where people in a potentially unsafe area are instructed to " go inside
buildings, close doors and windows, listen to radio or television for further instructions".

shelter in a large building (also called "effective shelter") away from windows with
ventilation turned off using outside air.
Shelter is a short-term measure and can only be used for a few days. Shelter is usually used
as a temporary ̆ measure if immediate and safe evacuation is not possible (for example, this
concerns special facilities, the immediate evacuation of which may be dangerous (special facilities
include: telecommunications centers whose personnel must work in order to provide
telecommunications services; chemical plants that cannot be evacuated until certain actions to
prevent fire or explosion; hospitals that house patients who cannot be evacuated immediately, as
well as prisons), and circumstances where the prevailing conditions make immediate evacuation
impossible ̆ or dangerous ̆ (for example, in difficult weather conditions)). Shelter should not last
longer than one day unless preparations have been made in advance for:
a)
meeting the needs of persons in shelter (e.g., food, water, sanitation, energy, medical
care, etc.);
b)
providing information to people in hiding;
c)
measures should be taken to control doses to ensure the effectiveness of sheltering in
locations where sheltering is used as a protective measure.
Shelter, in itself, is not considered sufficient protection, it should be carried out, if possible,
in combination with iodine ITB. Thus, the use of shelter should be limited by the condition that
more than one- time intake of an iodine drug for ITB by the population is impractical.
The effectiveness of a shelter depends on the design of the building used as a shelter and
its ability to provide effective protection against all significant exposure pathways. Shelter "in
place" in a typical house or in a large building may not provide sufficient protection against a
blowout.
However, sheltering in a large building can prevent lethal exposure and provides a
significant reduction in all doses; therefore, if a safe evacuation cannot be carried out immediately,
large buildings should be used as shelter whenever possible.
In addition, for special facilities where shelter is planned in advance as an urgent protective
measure, during the emergency planning process, the personnel who will remain in shelter at the
facilities should be trained and equipped in the same way as emergency workers, or there should
be a possibility instruct them during an emergency. Personnel must be able to monitor the dose
rate to confirm the effectiveness of the protection of personnel and the public.

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2.3.4. Resettlement
Resettlement is a non-urgent human relocation exercise to avoid long-term exposure from
radioactive materials deposited on the ground. As a rule, areas requiring resettlement are
determined on the basis of monitoring. In addition, resettlement may be required if areas where
people live have become contaminated with basic food and water supplies and it is not possible to
provide replacement food or water.
Resettlement is not an urgent protective action, and therefore there is sufficient time (from
a week to a month) for the resettled persons to take the necessary measures in accordance with
personal needs, for example, create conditions for pets, collect important property, provide real
estate security or create conditions for farm animals. Officials outside the site will also have some
time to provide housing and care for the displaced persons; at the same time, relocation should be
carried out over a period of several days to a month in order to be effective in reducing the dose to
the population.
2.3.5. Prevention of accidental ingestion of radionuclides into the body by ingestion
Releases of radioactive material from damaged fuel located in the active zone or in the
spent fuel pool can be deposited on the soil or other surfaces (for example, on the surface of a car).
Accidental ingestion of this and precipitated radioactivity into the body by ingestion, for example,
when eating with contaminated hands, can become a significant source of exposure for people,
during the first few days and after the release, which requires the implementation of protective
actions ̆ outside the facility site. Therefore, people should be instructed to take the following
measures to prevent or reduce exposure associated with accidental ingestion:
a)
do not drink, eat or smoke, do not put your hands to your mouth unless they are washed,
b)
do not allow children to play on the ground,
c)
not perform other actions ̆ that can lead to the formation of dust that can enter the body.
2.3.6. Decontamination people
Deposition of radioactive substances on the skin in an amount that can lead to severe
deterministic effects (for example, burns) is possible only on the site of the facility. People can
receive significant exposure from the inadvertent ingestion of radioactive substances that have
come into contact with the skin from a passing radioactive cloud or through contact with
radioactivity, deposited on the soil or on other objects. Therefore, in all cases where people may
be exposed to radioactive contamination, they should be instructed to keep their hands away from
their mouths (to prevent accidental ingestion of radioactive materials), shower and change clothing
as soon as possible. If monitoring and decontamination facilities are not available, the public
should be reassured that there is little health risk from contamination. The presence of radioactive
substances on the skin can also have adverse psychological and economic consequences. It can be
expected that a large number of people from the contaminated area will require controls to ensure
that they have not been contaminated. A sufficiently large amount of radioactive substances can
enter the human body by accidental ingestion or inhalation, and medical supervision is required
for the resulting doses of radiation.
In several emergencies in the past, people with potential radioactive contamination were
obstructed and alienated, and medical personnel refused to treat them. It should be noted, however,
that persons involved in the transport and processing and treatment of contaminated people can
perform this work without danger to themselves if they apply general anti -infection precautions
that provide an adequate level of protection. Such measures, for example, include personal
protective equipment (gloves, masks, etc.), which we will study in the following sections.
The level of radioactive contamination can be significantly reduced by simply removing
outer clothing and washing the skin (face and hands). In case of emergencies affecting a large
number of people, initial decontamination measures should be limited to these basic measures,
with only limited actions (which can be easily and easily performed) to manage the waste
generated during decontamination.
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During the evacuation, it is likely that their pets will follow along with people being
evacuated from the accident area, so attention must be paid to the decontamination of animals. It
is recommended that this procedure be carried out by the owners themselves, who should be
advised to wash the animals (once).
2.3.7. Limiting the consumption of food, milk and drinking water
The accident at the Chernobyl NPP showed that after fuel damage and a release that
required protective actions outside the site of the facility, the largest contribution to dose formation
was made by the consumption of vegetables grown on open ground (locally produced products,
including wild plants and prey (e.g. mushrooms and bushmeat), milk from animals grazing on
contaminated pastures, and rainwater Consumption of rainwater and locally produced products
may be a problem for several hours after a release, and milk consumption for The accidents at both
the Chernobyl NPP and the Fukushima NPP have also shown that it is necessary to provide
information about the control measures in place in order to reassure the public and interested
parties (for example, other states).
In the event of a radioactive release in an emergency, the fallout pattern is very complex
and will constantly change as the release continues. Even with relatively small releases, expected
to last days or weeks, “hot spots” can occur, resulting in radioactive contamination of food, milk,
rainwater and animal feed that exceeds international common criteria for restrictions on
consumption or distribution are required. This complex and time-varying deposition pattern makes
it impossible to timely identify areas where consumption restrictions are required based on
monitoring and sampling alone. Therefore, after declaring a general emergency, it is necessary to
immediately ensure:

food and water protection by instructing the public to protect drinking water sources that
use rainwater (e.g., turn off rainwater collection pipes) and protect food supplies that may be
contaminated, for example by transferring grazing animals to protected areas (e.g. sheltered) feed,
if possible;

limiting the consumption and distribution of locally produced non-essential products, wild
plants and harvested items (e.g., mushrooms and bushmeat), milk, rainwater and animal feed after
a release, pending sampling and evaluation;

taking measures to prevent contaminated food intended for human consumption, as well as
animal feed, from entering the distribution system;

reassurance of the public and interested parties (for example, other states) that the above
measures have been taken.
Once a release has begun, in order to quickly identify new areas where restrictions on the
consumption of food, milk, rainwater, animal feed and locally produced goods are required, dose
rate comparison from ground deposition should be used, without waiting for the results of
laborious laboratory analysis.
Monitoring is used to identify places where restrictions should be immediately imposed on
locally produced products, pasture milk and rainwater. However, measures to protect against the
intake of radionuclides in food and water also include the implementation of a program for the
collection and analysis of samples of food, milk and water in order to:
a)
confirming the sufficiency of control measures;
b)
introduction of additional restrictions;
c)
providing alternative food supplies lifting restrictions.
Restrictions should not be applied if they could lead to malnutrition or other health
consequences.
2.4.
Identification and medical care of exposed persons
2.4.1. Serious medical consequences
Exposure-related effects of two different types are considered as serious health effects:
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

heavy deterministic effects;
stochastic effects (i.e., radiation-induced oncological diseases).
Severe deterministic effects are those deterministic effects that can lead to death or reduce
the quality of life. Deterministic effects occur after exposure to a dose that exceeds a certain
threshold, and the severity of the effect increases with increasing dose. These effects usually
appear within a few days or months after exposure. The dose at which an effect may appear in a
particular person may vary depending on age and health status, as well as on the duration of
exposure; the provision of medical care may affect the outcome of exposure.
The most probable severe deterministic effects in an emergency with a release due to fuel
damage in the reactor core or spent nuclear fuel (SNF) pool include:

severe forms of radiation burns of the skin or soft tissues by beta radiation from radioactive
substances (for example, iodine) on the surface of the skin or close to it (for example, on clothing
or in contaminated water). The occurrence of such burns can only be expected on persons present
at the facility. Beta-radiation burns have contributed to deaths from radiation diseases of
participants in the liquidation of the accident at the Chernobyl nuclear power plant;

deaths from high whole-body doses received are possible in individuals within a 35 km
radius of the facility site in the worst postulated release;

cases of non-fatal serious consequences for the fetus, thyroid gland and reproductive organs
are possible in persons located within a radius of 1030 km from the site of the facility. Serious
consequences for the fetus and thyroid gland are mainly due to the inhalation of radioactive iodine.
Stochastic effects (radiation-induced cancers) are not expected to have a dose threshold,
and their likelihood (but not severity) increases with radiation dose. However, there is a dose below
which excess radiation-induced oncological diseases cannot be detected. Radiation-induced
thyroid cancer is the most serious problem among other possible radiation -induced oncological
diseases that occur as a result of the release of radioactivity from the active zone of the reactor or
spent nuclear fuel pool. This is due to the release of large amounts of radioactive iodine. Iodine
can enter the body through inhalation, from contaminated drinking water, from rain water, from
the milk of animals that graze on polluted pastures, or from eating contaminated locally produced
products. After inhalation or ingestion, radioactive iodine is concentrated in the thyroid gland,
which leads to the formation of very high doses of radiation to this organ.
After the accident at the Chernobyl NPP, a clear increase in the number of cases of
radiation-related thyroid cancer was found among the population in the age group 018 years (in
1986), at distances exceeding 300 km from the accident site. These cancers were mainly due to
doses received from drinking milk from cows grazing on pastures contaminated with radioactive
iodine. Radiation-induced cases of thyroid cancer began to appear in 1990, four years after the
accident at the Chernobyl nuclear power plant. However, this type of cancer is usually not lifethreatening if detected early and treated. For this reason, all individuals who may have inhaled
iodine at the time of the release, or who may have consumed food, milk or rainwater contaminated
with radioactive iodine, should be registered, their doses assessed and whether medical supervision
is required.
Detectable increase in the incidence of any other radiation-induced oncological diseases
(for example, leukemia) in the population after a release from the damaged active zone of the
reactor or SNF pool, which requires the implementation of protective actions outside the site of
the facility, is very unlikely, and with such situations, many people should receive doses sufficient
to develop severe deterministic effects. To date, only the presence of adetectable increase in
radiation-induced cases of thyroid cancer in the population group aged 018 years (in 1986) living
in the regions of Belarus, Russia and Ukraine affected by the accident at the Chernobyl NPP has
been clearly established. There are no scientific data showing an increase in the incidence of other
radiation-induced cancers in the population or the incidence of non-malignant diseases that could
be associated with radiation exposure as a result of the Chernobyl accident.
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2.4.2. Emergency medical examination, consultations and treatment
Hospitals should be instructed on how to treat patients who may have been exposed to
radioactive contamination (i.e. that the application of general anti -infection precautions provides
sufficient protection). Immediate (priority) medical examination and hospitalization are required
only for people who have received a large enough dose of whole body radiation that exhibits the
symptoms described in; this is required for advice on treatment and care for severe deterministic
effects.
2.4.3. Medical supervision
In order to identify individuals who should continue to be under medical supervision and
provide a basis for informed counselling of pregnant women and others, their exposure doses need
to be assessed.
Within a few weeks, a program should begin to assess doses and health risks for all victims,
the purpose of which is to additionally determine the circle of all persons who may require longterm medical observation, based on the general criteria. The assessment of exposure doses to
pregnant women should be carried out first.
Advice and counselling by specialists should be provided to anyone who has been screened
or registered for medical supervision and who has concerns about exposure emergency situations
on their health or on the health of children or the fetus. There are only a limited number of
specialists in the field of diagnosis and treatment of radiation injuries in the world. Medical
examinations, treatment, and counselling should be carried out only after consultation with experts
(such assistance can be obtained through the IAEA or the WHO by following the recommendations
set out in).
All pregnant women who have had thyroid or skin radiation measurements taken or who
express concern should be registered and advised that:
d)
the risk to the fetus is small but can only be assessed by a radiation hygienist (not their
local doctor);
e)
individual risk will be assessed by experts and contacted to discuss the results and answer
any questions.
2.5.
Protection of international trade and commercial interests
Emergencies lead to adverse economic consequences. Consumers at home and abroad must
be assured that all products leaving the affected area are carefully monitored to ensure that they
are not contaminated with radioactivity (i.e., criteria set for international trade are not exceeded).
The economic consequences come when the possibility of radioactive contamination of export
products is only assumed, even if there was no serious release.
Therefore, appropriate measures must be taken to ensure that all goods meet international
standards and to reassure the public and interested parties (e.g., importing countries) of this.
Experience has shown that the establishment of a system of control and certification can mitigate
the economic impact on international trade. Measures are needed to limit the distribution of goods
within the boundaries of the ICPD until such time as certification can be used to confirm that
products from a contaminated area is safe and does not exceed internationally agreed criteria for
trade, and products from unaffected areas can be tested against a certificate of origin.
2.6.
Termination or relaxation of response measures
Protective actions and other responses should be discontinued or relaxed, as appropriate,
after consideration or confirmation of the following conditions:

further major releases are possible (e.g., the emergency is no longer classified as a site
emergency or a general emergency);

monitoring was carried out;

sampling and analysis of potentially contaminated food, milk and water samples;
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



protective actions and other responses consistent with OILs are no longer required;
weakening the response will do more good than harm;
stakeholder consultations;
the population is informed and understands the reason for the introduction of changes.
After the end of the announced emergency situation , further actions should be taken on
the basis of criteria developed after a careful assessment of local conditions, in consultation with
stakeholders, to ensure that, in terms of the impact of these actions on the population, any such
actions do more good than harm.
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3.
Personal protective equipment
3.1.
The history of the creation of personal protective equipment
In the first months of the war in Germany, there was a shortage of rubber, gasoline and
saltpetre, which were badly needed for the production of explosives and other military needs. In
such an environment, German scientists were mobilized to carry out military tasks.
At the end of 1914, a group of German chemists led by F. Gaber, director of the Berlin
Physico-Chemical Institute, contrary to the Hague Conventions of 1898 and 1907, suggested that
the German command use gaseous or volatile liquid poisonous substances in the form of a cloud
in combat conditions.
The first chemical attack was carried out in the northwest of Belgium. 180 tons of chlorine
were consumed in a section 6 km wide. The concentration of chlorine was 0.01 - 0.1%, which is a
lethal dose for humans. In addition to chlorine, phosgene, mustard gas, etc. were used as chemical
warfare agents.
The number of dead and injured as a result of such military actions stirred up the world
community. An active search began for a reliable means to neutralize the chemical weapons of the
enemy. Immediately after receiving news of the gas attack, Nikolai Dmitrievich Zelinskyi began
to look for ways to protect against gaseous poisons (chlorine was the first in his research) and to
create a gas mask. The main active reagents in gas masks were sodium hyposulfite (thiosulfate)
Na2S2O3 and (sodium carbonate) Na2CO3:
Na2S2O3 + 4Cl2 + 5H2O = Na2SO4 + H2SO4 + 8HCl
Na2CO3 + 2HCl = 2NaCl + H2O + CO2
(3.1)
Na2CO3 + H2SO4 = Na2SO4 + H2O + CO2
As a result of the proposed reaction, toxic products (chlorine) were absorbed, and non-toxic
(or moderately toxic - carbon dioxide) products were released.
But the proposed mixture was not universal - it can only neutralize chlorine. Other solutions
were needed.
Analysing the data received from the military activity area, as well as the symptoms of a
person’s defeat and the testimonies of survivors of gas attacks, Zelinsky noticed that those who
breathed through a damp rag (overcoat), through loose earth, tightly touching it with their mouth
and nose, survived. Those who covered their heads well with an overcoat and lay quietly during
the gas attack were also saved. These simple techniques, which saved from suffocation, showed
their effective protection in the conditions of the use of deadly poisonous gases. It became clear to
the scientist that the reason for the protection against poisonous gases must be sought in the
filtration of inhaled air by passing them through special filters. Such filters could be porous bodies
capable of adsorbing various substances on their surface. Therefore, it was decided to use a simple
agent as an absorber, the action of which would be similar to the action of the matter of a soldier
's overcoat or soil humus, would have more protective efficiency. At the same time, toxic
substances were not chemically bound, but absorbed or adsorbed by wool and soil. As studies have
shown, charcoal in relation to gases had a much higher adsorption coefficient than soil. The first
experiments were carried out in the Central Laboratory. In a hermetically sealed room, a large
piece of sulfur was lit. In this case, poisonous sulphur oxide (IV) was formed. When the
concentration of the gas became high enough and, N.D. Zelinsky and his collaborators V.S.
Sadikov and S.S. Stepanov. For half an hour, the testers were in a poisoned atmosphere without
any health consequences.
A systematic study of the properties of coal began. It turned out that ordinary coal has a
low absorption ability. You can increase its absorption properties by activating it. The meaning of
coal activation is that adsorbed heavy hydrocarbons and resinous substances are removed from the
inner surface of the pores. First, the coal was impregnated with alcohol and ether, and then
calcined. High-molecular organic substances were removed from the pores, and the coal acquired
greater porosity and, consequently, a highly developed surface. Further experiments showed that
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activation can also be carried out with water vapor. At high temperatures, the so-called water gas
is formed in the pores of coal.
In June 1915, Zelinsky made a report at a meeting of the sanitary-technical department of
the Russian Technical Society, and in August he delivered a report on the adsorption properties of
coal at an emergency meeting of the experimental commission at the medical commission of the
All-Russian Union of Cities in Moscow.
Based on the theoretical and experimental data of Professor Zelinsky, engineer Kummant
created a rubber mask that hermetically fits the face and ensures the flow of air for breathing only
through the filter element. It took four months to make a real gas mask.
However, the introduction of the invention was hampered. A specially created commission
at first gave preference to the gas mask design created at the Mining Institute, although it was
inferior to the Zelinsky-Kumant design in terms of power and convenience. Only in March 1916.
An order was placed for the manufacture of 200 000 Zelinsky gas masks. In August 1916 the army
was provided with such gas masks only 20%, although their popularity at the military activity area
was enormous.
To increase the effectiveness of chemical attacks, the Germans decided to use "mustard
gas", the use of which led to great casualties. This prompted the scientist to equip the recently
developed gas mask with additional boxes with a chemical "mustard gas" absorber.
At present, personal protective equipment is needed not only by military personnel in case
of the use of poisonous substances in the course of hostilities. They have found wide application
in peacetime, especially at enterprises that manufacture or use hazardous chemical substances in
production.
3.2.
Purpose of personal protective equipment
Personal protective equipment is understood as personal use equipment used to prevent or
reduce exposure of workers to harmful or hazardous production factors, as well as to protect
against pollution.
The use of personal protective equipment is the most effective way to protect the population
in real conditions of environmental contamination. They are designed to protect the respiratory
organs, eyes and skin from exposure to vapours, drops and aerosols of chemical hazards and toxic
substances (CHTS), as well as from the ingress of radioactive dust, pathogenic microbes and
toxins.
PPE should be used strictly for its intended purpose and in accordance with regulations that
classify them according to various criteria. Ensuring safe working conditions is the responsibility
of the employer. The rules and regulations for the issuance of PPE for a particular enterprise must
be approved by a local regulatory act - the Regulation on the issuance. With the list of protective
equipment necessary to ensure safe work at a particular workplace, the employee must be
familiarized with when hiring. By its internal order, the employer has the right to make changes to
this local list, provided that this does not worsen working conditions. When performing work in
hazardous or hazardous conditions, only certified protective equipment may be used, which are
marked with the name of the manufacturer, the name or type of product, the date of its manufacture
or certification test, as well as a seal confirming certification. Certification of all types of PPE is
carried out in accordance with the technical regulations of the Customs Union "On the safety of
personal protective equipment" TR CU 019/2011, which entered into force on June 1, 2012.
When choosing and ordering PPE, you must use the following terminology:

special protective clothing (sheep coats, coats, short coats, short fur coats, capes, raincoats,
half raincoats, dressing gowns, suits, jackets, shirts, trousers, shorts, overalls, semi-overalls, vests,
dresses, sundresses, blouses, skirts, aprons, shoulder pads);

hand protection equipment (mittens, gloves, half-gloves, fingertips, palms, wristlets,
armlets, elbow pads);
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
leg protection equipment (boots, boots with an elongated shaft, boots with a short shaft,
half boots, boots, low shoes, shoes, shoe covers, galoshes, boots, slippers, high boots, boots,
shields, boots, knee pads, footcloths);

eye and face protection (goggles, face shields);

head protection equipment (protective helmets, helmets, balaclavas, hats, berets, hats, caps,
scarves, mosquito nets);

respiratory protection equipment (gas masks, respirators, self-rescuers, air helmets,
pneumomasks, pneumosuit);

insulating suits (pneumatic suits, waterproofing suits, space suits);

hearing protection (anti-noise helmets, anti-noise inserts, anti-noise headphones);

fall protection equipment and other safety equipment (safety belts, ropes, hand grips,
manipulators, knee pads, elbow pads, shoulder pads);

dermatological protective agents (protective, skin cleaners, reparative agents that promote
skin regeneration);

comprehensive protective equipment.
General requirements for PPE:

PPE should not be a source of dangerous and harmful production factors;

PPE should not have a toxic or allergic effect on the worker's body; it is necessary to make
them from materials approved for use by the Ministry of Health and Social Development of the
Russian Federation;

PPE must meet the requirements of technical aesthetics and ergonomics.

PPE during washing, dry cleaning and disinfection should not change their properties;

assessment of PPE should be carried out according to protective, physiological and
hygienic and operational indicators.

PPE (each) must be supplied with instructions ̆ indicating the purpose, service life, rules of
operation and storage.
The classification of PPE depending on harmful and hazardous production factors is given
in the standards: GOST 12.4.013-97, GOST 12.4.023, GOST 12.4.034-2001, GOST 12.4.064,
GOST 12.4.068, GOST 12.4.218-99.
Purpose marking or general classification by protective properties is carried out in
accordance with the requirements of GOST 12.4.103-83. All types of overalls, footwear and hand
protection are divided into groups and subgroups, each of which has its own marking - a symbol.
The designation of the required properties depends on the materials used and the design of the
product. The required properties of a protective product are laid down at the creation stage in the
technical requirements. Labeling of a protective agent that simultaneously protects against several
harmful factors should include the designation of the most significant groups and subgroups (no
more than three).
3.3.
Classification of personal protective equipment
PPE differ depending on the purpose, design features ̆ and the principle of operation.
There are a huge number of different classifications of personal protective equipment. The
classification of PPE can be based on various features, for example, protected areas, purpose,
principle of protective action, etc.
1. Personal protective equipment is divided into protected areas:

Means of Individual Protection of the Respiratory Organs (RPE);

Means of Individual Eye Protection (EPE);

Means of Individual Dermal Protection (DPE).
PPE includes gas masks, respirators, various kinds of breathing apparatus, etc. The eyes
protective equipment includes protective goggles against the light pulse of a nuclear explosion,
and the SPE includes protective clothing.
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According to the most general classification, all PPE can be divided into three groups (see
Fig. 3.1):
1. Means of individual respiratory protective equipment;
2. Means for personal dermal protective equipment;
3. Medical protective means.
Personal
protective
equipment
Respiratory
protective
equipment
Dermal
protective
equipment
Medical
protective
means
Figure 3.1. Groups of personal protective equipment
The group of medical products includes medicines, tools and materials used in emergency
situations for disinfection, protection, and elimination of the consequences of exposure to
damaging factors on the human body.
To protect the skin, use overalls and safety shoes, means to protect the hands, head, eyes,
face. PPE skin are divided into insulating and filtering.
Insulating completely protect the skin and external organs from hazardous effects. For
example, insulating overalls are made from sealed or non-sealed air- and waterproof materials,
including frost-resistant ones. The means of filtering action include special breathable clothing, as
well as underwear made from fabrics that have been treated with a soap-oil emulsion or other
special composition.
Respiratory protective equipment can also be filtering and insulating. In filters, outside air
containing harmful substances undergoes preliminary filtration and purification, after which it
enters the respiratory organs. Insulating ones provide a supply of clean air from the outside or have
a closed pendulum breathing system based on the use of chemically bound oxygen.
Within each of the above groups of PPE, separate groups of PPE can be distinguished.
2. According to the principle of protective action RPE and DPE are divided into filtering
and insulating.
The action of filtering PPE is based on the principle of filtering and cleaning the working
atmosphere before it comes into contact with the human body. The action of insulating PPE is
based on the complete isolation of the human body from the environment.
3. 3. By appointment, PPE is divided into military, industrial and civilian.
The military are divided into combined-arms PPE, intended for use by personnel of the
internal affairs bodies and military personnel of the internal troops, and special PPE, which are
intended for use by military personnel and employees of certain specialties or for performing
special work.
Civil PPE is designed to protect the population on the ground, contaminated with CHTS
and radioactive substances.
Industrial PPE is designed to protect a person from specific toxic substances in the work
area at work. Such PPE cannot be considered as universal means of protection against hazardous
chemicals and radioactive substances.
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3.4.
Concepts of use personal protective equipment
There are a number of aspects of the concept of use of PPE that result in various different
subcategories within each type of item. In particular, these relate to the length of time and the
number of times that the equipment will be worn. Equipment may be intended as:
 Single-use (disposable)
 Multiple-use; dispose after contamination
 Reusable after contamination
These differences have a significant impact on the design, capabilities, and subsequent cost
of the item:
 Single-use equipment will often be less durable than multiple-use equipment, and if
maintaining the integrity of equipment is critical for user safety, the relevance of singleuse equipment in this application must be considered carefully.
 Designing for decontaminability is a particularly difficult challenge, and thus the user
should be clear on this particular component of their concept of operations when
designing or selecting PPE.
Hence, much equipment is intended to be multiple-use but not necessarily decontaminable
for the purposes of reuse.
A related consideration is the level of training the user requires:
 Escape or other forms of single-use equipment may be intended for relatively untrained
users, having a short intended use time, and offering the user limited operational
capability. Such equipment is often not sized but rather “one size fits all,” with perhaps
some fitting features, and may be single- or multiple-use.
 Users who expect to perform more operationally complex functions of longer duration
require training, and their PPE usually has more sophisticated features.
Such PPE may be single- or multiple-use and will almost always need fitting and sizing.
The areas that tend to be traded off when designing within these concepts of use are the following:
 Efficacy of protection vs. physiological burden;
 Durability and decontaminability vs. cost.
Particular design issues are addressed. In some cases, equipment has been designed around
particular standards, some of which are discussed in general in this chapter.
3.5.
Respiratory protective devices
3.5.1. Protective Concepts
To protect the respiratory tract, as well as associated routes of entry such as mouth and
eyes if within the respirator, there are two important requirements: First, the breathing air must be
free of hazards; and second, no hazards must be able to penetrate or permeate around or through
the protective item.
The breathing air can be rendered free of hazards either by the supplied air or by air
purification. Supplied air systems provide breathable gas from a supply that is:
 Worn by the wearer;
 Provided through a tether line from a tank or remote location with clean air; or
 Synthesized in situ by chemical reaction.
Air-purifying systems purify ambient air to remove and deactivate toxic materials by the
following means:
 Particulates and aerosols are removed by adhesion to the filtration layer.
 Vapours are removed by adsorption and chemisorption onto the adsorbent layer.
For either type of system, toxic materials can be prevented from entering the protective
item by providing a leak-free system; for some portions of the item, this may be relatively simple,
whereas for others it can be a significant design issue: for example, sealing to the face or preventing
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in-flow through the exhalation valve. Alternatively or additionally, leakage may be prevented by
using a positive-pressure concept, in which air flows out through all potential leak paths at a
sufficient pressure to prevent backflow. Materials must also be chosen to prevent permeation of
chemicals over the intended period of use.
Some particular challenges of applying traditional respiratory concepts for use in CBRN
protection lie in the following areas:
 The limited number of existing materials available that can satisfy the requirements for
soft components such as facepieces, valves, and hoses, and transparent components such
as eyepieces and visors
 The difficulty in maintaining protection and adequate clean air supply despite the high
airflows demanded when breathing at exhaustive work rates
 Fitting the population to minimize leakages while not restricting vision or causing
discomfort
It should be recognized here, as in all PPE use, that there are significant trade-offs involved
in selecting among the various concepts and that each has significant limitations that must be
managed.
3.5.2. Components of a Respirator
Regardless of which style of respiratory protective device is used, all consist of at least a
respiratory interface, which is the part of the respirator such as a facepiece or hood that connects
to the wearer, and either an air-purifying element or an air/oxygen source and associated delivery
components.
Air-Purifying Respirators (APRs). APRs contain, at a minimum, a respiratory interface
(such as a facepiece, hood, or helmet) and an air-purifying element (APE) that may be a removable
canister or filter element, or may be part of the facepiece, as in a filtering facepiece respirator. The
air is drawn through the APE either by the wearer’s inhalation action or with the assistance of a
blower unit. Powered air purifying respirators (PAPRs) use a blower to provide increased flow
and, potentially, overpressure.
Supplied Breathable Gas Devices. These contain, at a minimum, a respiratory interface
and a means for supplying uncontaminated breathable gas to the wearer. Self-contained devices
use pressurized breathable gas in valved cylinders, or generated by a chemical reaction during use,
as an integral part of the RPD worn by the user. Although oxygen-generating devices are
commonly used in escape applications for certain adverse environments (mines, submarines), they
are not commonly used for this application, weight of and heat generated by the oxygen-generating
system being concerns. Other supplied breathable gas devices use a gas source remote from the
wearer derived from pressurized cylinders or drawn by the breathing action of the wearer from an
uncontaminated area.
Typical Components of the Respiratory Interface. All respirators that cover at a minimum
the entire face (most relevant to CBRN protection) contain certain types of universal components
that assure functionality of the device. Various attachments and design features assure that the
respiratory interface fits to the wearer and integrates appropriately with other equipment. The
traditional full-face face sealing respirator has some form of adjustable head harness.
Alternatively, a seal to the neck or components to facilitate attachment to a helmet or hood system
may be present.
Normal functioning of the wearer is assisted by other components. Eyepieces or visors that
allow clear vision and integration with other equipment that may need to be brought up to the eyes
are essential, and they may have other functions, such as ballistic protection. Some form of
communication interface is necessary to permit clear speech, and in some cases to assist hearing.
In most cases, a drinking facility is provided (with an accompanying CBRN hardened reservoir
for drinking fluid).
Proper air management is critical to preserve the quality of the air within the respiratory
interface, maintaining a directional path for incoming and outgoing air. One-way valves open only
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during either the inhalation portion of the respiratory cycle (inlet valves), allowing clean air to
flowinto the lungs, or during the exhalation portion (outlet valves), exhausting the exhaled air out
of the RPD. The nose cup is present to minimize the “dead space” of exhaled air that is not
exchanged completely on each breath, and to keep moist exhaled air from fogging up eyepieces,
which have a clean air sweep across them as well. Inhalation and exhalation valves have some
cracking pressure (i.e., they will not open if there is insufficient positive pressure against them).
This cracking pressure will potentially be different in overpressure devices compared with
negative-pressure devices. Finally, a leak-free means of attaching to the air supply or APE
(canister) is required.
Styles of Respiratory Interface. There are two styles of respiratory interface to the wearer’s
head: tight fitting and loose fitting. Tight-fitting respiratory interfaces rely on providing an intact
physical barrier between the device and the wearer. Nose cups, facepieces, and hoods that seal to
the neck are examples of this style of respiratory interface (see Fig 3.2) for an example of a
facepiece style of respirator). Such systems need to form a tight seal to the wearer’s skin, usually
on the face or occasionally on the neck. The seal itself protects against ingress of contaminated
air. Typical APRs fall into this category; they are referred to as negative-pressure devices, as the
air pressure within the device will become negative during the inhalation cycle. However, motion,
speaking, or dislodging by other equipment can break the seal, in which case leakage may occur.
This potential leakage can be reduced by using overpressure concepts such as self-contained
breathing apparatus (SCBA) or tightfitting powered air-purifying respirators (PAPRs).
Figure 3.2. Tight-fitting military-style APR.
Loose-fitting respiratory interfaces have no or a minimal seal anywhere to the skin and
therefore rely on adequate breathable gas being provided at all times to accomplish an
overpressure. This overpressure is intended to prevent hazardous substances from leaking into the
area covering the important routes of entry: eyes, face, and/or mouth. Certain styles of hoods and
helmets fall within this category (see Fig. 3.3).
Nonencapsulating loose-fitting respiratory interfaces such as that illustrated in Fig.3.3 do
not seal to the wearer’s skin, and therefore they can only be used with devices that actively supply
breathable gas to the respiratory interface; otherwise, there is nothing to prevent ingress of
contaminated air and protection exists only in the presence of substantial overpressure. The amount
of air supply required to maintain this overpressure depends on two factors: the breathing rate of
the wearer and the resistance to flow out of the interface. As the breathing rate increases, an
adequate air supply must be present on the inhalation portion of the breathing cycle so that there
is still more air supplied than is being inhaled, maintaining positive pressure. With regard to design
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of the respiratory interface, the size of the “gap” between the interface, such as a hood, and the
wearer’s skin – the air exits through this gap – determines whether any overpressure can be
maintained. If movement causes this gap to increase or causes a bellows effect with the interface
material, exterior air may be drawn into the breathing region. In either case, for protection to be
effective, the system must include a pressure demand valve that increases the flow to maintain the
overpressure. For the relatively high protection levels required for CBRN protection, extremely
high flow rates may be necessary as a result, and these may be difficult or impossible to provide.
Figure 3.3. Loose-fitting powered air-purifying respirator: hood style with powered air supply
worn on the waist.
Additionally, encapsulating (or nearly encapsulating) systems exist that may have no
specific seal to the wearer but have few leakage routes either [i.e., the wearer is inside a giant
plastic bag with a route for breathing air to enter (if necessary) and exit]. When worn with selfcontained breathing apparatus (SCBA) inside the system, only an exhalation valve is needed, and
overpressure is maintained within the entire system. An example of the general design of a loosefitting nearly encapsulating system is shown in Fig. 3.4. A blower is worn within the suit, with the
canisters outside; air is supplied from the blower to the head area. The breathing area may or may
not be enclosed in a nose cup; alternatively a neck dam may separate the breathing area from the
body of the suit. Typically, the exhaled air exhausts down into the body of the suit and then through
a valve into the atmosphere. Encapsulating concepts are not particularly affected by the wearer’s
anthropometry, and therefore in principle are to be preferred when trying to fit to the entire
population to a very high degree of protection.
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Figure 3.4. Nearly encapsulating suit worn with a PAPR: front view, and back view showing the
APEs outside the suit. (Reproduced by permission of, and © Respirex International, date
unknown.)
Air-Purifying Element Components. The air-purifying element or elements may be part
of the facepiece, or a canister attached to the facepiece or a blower unit in the case of a powered
air system. Canisters will have a housing consisting of an appropriately impermeable material, an
inlet (designed to protect the contents from splash contamination or wetting by water during use,
and decontamination), and an outlet that contains the attachment to the respiratory interface.
Figure 3.5. Schematic of the layout of a canister.
For general-purpose CBRN applications, the APE (Fig. 3.5) will first contain a particulate
filtration component to remove aerosols, followed by an adsorptive or reactive component to
remove vapours. The aerosol-removal component will be in front of the vapor-removal component
to minimize degradation of the adsorptive or reactive bed by encounter with aerosols and dusts.
An APE containing only the particulate removal element has potential application for B and R
events, where no hazardous vapor is known to be present. The use of APE-containing devices is
appropriate only when it is known that the APE has the capacity to remove all the hazards from
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the air and that the remaining air is suitable to breathe (i.e., has sufficient oxygen content). The
hazard-removal capability of an APE is difficult to ascertain thoroughly, particularly for vapours.
Its dynamic capacity (the speed with which it can remove the hazard) and theoretically, total
capacity must be determined for each vapor hazard of interest, under a variety of realistic
conditions of use (airflow rates, temperatures, and relative humidities in particular). This means
that vapor-removing APEs have limited duration of use, which will differ for each hazard and
condition of use.
Particulate removal components have fewer limitations; their capabilities vary most
importantly as a function of the challenge particle size, surface tension (wet/dry), and charge, and
not as a function of the specific agent. Thus, the performance can be more easily characterized
generically for worst-case conditions. In most cases, capacity is limited by clogging of the filter,
which is detected by the user as an increased breathing resistance, meaning that filter change is
required. Attachment of the filter to the headpiece or hose is usually via a standardized connector
[398,399].
Breathable Gas Supply Components. A breathable gas is supplied from a pressurized
source. Possible gas sources include:
 Gas cylinders: designed to contain pressurized breathing gases at the highest practical
pressures for efficient storage. The breathing gas may be purified air or various oxygengas mixtures.
 Chemical oxygen: provides breathable gas to the wearer by mean of a chemical reaction
and includes a scrubber to remove undesired exhaust gases.
 Compressor: provides a continuous source of purified breathable air to the supply chain.
The gas source may be remote from the wearer and connected via an air-line or mounted
on the body in the case of gas cylinders or chemical oxygen supply. The supply chain for the device
may contain the following components:
 Shutoff valve: to allow or prevent the gas from entering the supply chain.
 Pressure reducer: reduces the high pressure to lower pressure levels that the wearer can
breathe directly or that are used by a demand valve.
 Demand valve: there are two types, negative and positive pressure. In a negative pressure
demand valve, inhalation triggers the valve to open and exhalation stops the flow; during
inhalation, the pressure may go negative. Positive-pressure demand valves are designed
to maintain a pressure slightly above ambient inside the respiratory interface even during
inhalation.
 Continuous flow valve: provides flow at a comfortable rate and pressure for the user in a
continuous flow (rather than demand) mode.
 Relief valves: used to prevent over pressurization within the supply chain.
 Transportation elements (e.g., hoses and breathing bags): direct the gas along the supply
chain.
Table 3.1 summarizes most of the relevant possible styles of respiratory protection for a
CBRN application. More detailed discussion of the more common styles of RPD follows.
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Table 3.1. Some styles of RPD that are relevant for CBRN protection.
Design Feature
or Capability
Type
Seal style to face Half face
or head
Full face
Hood
Nearly totally
encapsulating
suit
Totally
encapsulating
suit
Manner in which Self-contained
air is supplied
air
Variants
Tight-fitting
single-use Particulate only could have
APR with built-in APE or relevance when worn with eye
replaceable canister
protection
(e.g.,
filtering
facepiece);
particularly for
particulate-only events (B, R)
Tight-fitting reusable APR Particulate only, vapor only, or
with replaceable canister
both
Tight-fitting with supplied SCBA
air
Tight-fitting
single-use Often used for escape concepts
APR, with mouthpiece
Tight-fitting APR with PAPR likely
replaceable canister
Loose-fitting APR with PAPR only
replaceable canister
Loose- or tight-fitting with PAPR only
replaceable canister
Loose- or tight-fitting
SCBA only
Demand
Uses less air and balances
demand, therefore extending the
air supply and optimizing
protection
Maintains
overpressure,
theoretically
improving
protection
Air is exhausted to the outside
Air is recirculated by scrubbing
undesirable
exhaled
gases,
cooling, and supplementing
oxygen
Air is supplied under pressure
from a remote source (e.g., tank,
filtered compressor)
Conserves life of canisters
More
common;
maintains
overpressure,
theoretically
improving protection
Called N100 per NIOSH
Called N99 per NIOSH
Called N95 per NIOSH; also R95
(somewhat resistant to oil)
Called ULPA in Europe per EN
1882 (generally for collective
protection/clean rooms)
Called HEPA in Europe per EN
1882
Constant flow
Open circuit
Closed circuit
Air-line
Closed circuit
Demand
Constant flow
Particulate
removal
capability of
APE
Nonoily
particulate (e.g.,
biological
aerosol)
Any particulate
Examples and Comments
99.97%
99%
95%
>99.995%
80–99.995%
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3.5.3. Self-Contained Breathable Gas Styles
Existing supplied breathable gas systems intended for CBRN use are essentially all selfcontained breathing apparatus (SCBA) systems (see Fig. 3.6) with a compressed air tank worn by
the user using a harness, and connected to pressure regulators and supply lines, which are
connected to a facepiece. This is an open-circuit apparatus, as the exhaled air is not recirculated.
The significant advantages of this concept are that:
 Breathing air is guaranteed in environments containing any concentration or type of
hazard agent, or low oxygen.
 The supplied air generates an overpressure (at a minimum pressure guaranteed by the
pressure-demand valve) that assists in preventing inward leakage.
 Breathing is assisted on inhalation.
 Defogging is facilitated if flow is directed properly within the facepiece.
 The person is not tethered to an air-line and therefore is free to move.
 Air supplies require warning systems to alert the wearer if air is low, and such systems
are an additional expense and, when audible, restrict stealth operations.
 Requirements for air resupply, maintenance, and training are significant compared with
simple air-purifying respirators.
Figure 3.6. SCBA worn over a protective coverall.
3.5.4. Tethered Supplied Breathable Gas Systems
Breathable gas may be supplied via a tethered line from a plumbed-in air supply (within a
building, for example), from a larger purified supply not worn by the user, or from a clean ambient
air source remote from the source of contamination. The latter strategy would often be a poor one
in a CBRN incident, as no such source may exist within a reasonable distance of the user, and
some form of air purification would still be required to ensure that clean air is used. The use of a
tethered line in general has limited applicability for roles where freedom of motion is required,
although certain user groups might find applicability; for example, medical personnel, coroners,
or pathologists who work in a fixed area might find this concept of use appropriate. An SCBA
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system may also be supplemented by a portable tank system with an air-line to extend the air
supply.
3.5.5. Air-Purifying (Negative-Pressure) Respirators
The simplest forms of air-purifying respirators are those that have no form of assisted air
supply; in other words, the force to drive the air through the purifying element is provided by the
wearer’s lungs. They are referred to as negative-pressure respirators because inhalation causes the
interior of the respirator to be at lower pressure than the surrounding air, which will tend to force
leakage in through any place where seals are not tight. Despite this disadvantage compared with
overpressure respirators, they are simpler, with less logistical burden, and therefore remain a good
choice where their use is permitted.
Commercially, a variety of styles of such respirators are available. They may be half-face,
covering the mouth and nose only (Fig. 3.7), or full face, covering the entire face, including the
eyes. In terms of purification styles, they may be designed to remove only a particular subset of
hazards. Particulate respirators may be rated to remove oily aerosols and/or dry aerosols, and are
often constructed as filtering facepiece respirators (Fig. 3.8). Gas and vapor respirators may
remove only particular chemicals or classes of chemicals, such as organic vapor or acid vapor.
From the point of view of CBRN protection, as noted previously, most appropriate styles
will cover the entire face at a minimum, although it is noteworthy that the use of particulate
filtering facepiece devices for protection against contagious outbreak events is considered to be
the norm, despite their demonstrably low protection capabilities against submicrometer particles
and generally poor fitting characteristics. It is noteworthy, of course, that surgical masks are also
used routinely despite not being respiratory protective devices at all.
Figure 3.7. Half-face respirator.
There are various types of air purification capability in routine use:
 For particulate filtering only;
 For vapor air purifying only;
 A combination of air purifying and filtering.
For CBRN purposes, vapor air purifying could only have applicability far from a chemical
release event. Particulate filtering alone would have applicability to all biological and almost all
radiological agents, while a combination of air purifying and filtering is appropriate for most
chemical or unknown events where some combination of aerosol and vapor might be present. It
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should be reiterated here that there are CBRN environments in which no APR concept is suitable
for use, and only an air or breathable gas supply is appropriate. These environments where APR
use is inappropriate include:
 Oxygen-deficient environments;
 Extremely high concentration environments (e.g., a release within a confined space or a
large release outdoors);
 Vapor environments where the canister does not, or is not known to, remove the
chemical;
 Unknown environments (where the agent released is sufficiently uncharacterized in either
nature or concentration that the capability of the system to protect against it cannot be
assessed).
Figure 3.8. Filtering facepiece respirator with an exhalation valve.
3.5.6. Powered Air-Purifying Respirators
Positive-pressure powered air-purifying respirators are generally supposed to be a
significant improvement over negative-pressure APRs because of the following features:
 A blower, combined with an appropriate exhalation/exhaust valve combination in the
facepiece, ensures that positive pressure is supplied to the facepiece, nominally forcing
face seal leakage in an outward direction.
 The exhalation/exhaust valve must have enough resistance to flow that it maintains
overpressure within the facepiece.
 The exhalation resistance can be reduced through the use of a pressurecompensating
valve.
 Continual airflow provides cooling (via convection if there is a temperature gradient and
via evaporation if there is a water concentration gradient) and also provides defogging.
 Air is not limited as it is in an SCBA tank.
 The positive pressure reduces the work of breathing by assisting in inhalation.
An example of a PAPR with a tight-fitting interface is shown in Fig. 3.9. PAPRs that do
not seal to the face (including loose-fitting PAPRs) also confer the advantagethat:
 Facial hair, eyeglasses, and unusual facial features that might compromise a seal can, in
theory, be accommodated.
 Fit testing and sizing are usually not required.
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Figure 3.9. Powered air-purifying respirator with tight-fitting facepiece worn with a disposable
suit; a blower with canisters is worn on the waist, with the air supply hose leading to the
facepiece.
It must be stated that, in general, not all of these features necessarily result in overall
improvements for the user. Some of the potential disadvantages or limitations of the PAPR system
include:
 Continuous high flow through the canisters means that their lifetime is necessarily
limited; the desired longer potential duration of use of the RPD due to physiological
benefits thus requires a stock of canisters at the point of use.
 Canisters must be larger, more efficient, or doubled up to maintain required protection
levels and durations, which leads to greater weight and bulk, particularly when including
the blower.
 Battery life is often a limiting feature, and few systems have any end-of-service life
indicator; when batteries begin to die, blower power and protection fall off dramatically.
 Rechargeable batteries cannot guarantee a sufficient output after several rechargings;
therefore, nonrechargeable batteries must be kept stocked and fresh at the point of use.
 A requirement may exist for resistance to flow on exhalation that may be higher than that
in an APR, to maintain overpressure within the facepiece.
 Blower and hose construction are often less durable because these parts are not required
to withstand high-pressure use, unlike SCBAs.
 The fact that PAPR blowers deliver high volumes at low pressures means that their
capability to maintain overpressure within the facepiece is potentially not as robust as for
an SCBA, which can provide substantial flow at a higher minimum overpressure.
 Loose-fitting PAPRs are particularly prone to overbreathing.
The latter two issues may be mitigated by wearing the PAPR within a nearly encapsulating
suit, as described previously.
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3.5.7. Emerging Concepts and Issues
Combined SCBA/PAPR respirators are now available (which generally can also be worn
as an APR). The main advantage of this style is the extended wear times of the PAPR combined
with an available clean air supply if agent concentrations become high, the canister cannot remove
the hazard, or oxygen is depleted. Although this approach is attractive for organizations that have
all three types of respirators on hand and would like to minimize the associated cost and logistics,
the possible disadvantages of this concept should not be overlooked, as there is always a price to
be paid:
 Increased weight and bulk will result from carrying both a blower and an air tank.
 Design compromises may result from combining both functionalities; for example:
 If both hoses are attached separately to either side of the facepiece, the field of view will
be affected and snagging or interference with the hoses is more likely, the facepiece is
less likely to fit well beneath a visor, and the weight of the two sets of hoses may be more
likely to cause dislodging of the facepiece.
 If the two devices are placed in series (blower attached to the facepiece and compressed
air tank feeding through the blower), the demand valve configuration may not function
reliably.
 It may not be possible for the wearer to switch back and forth freely between modes, for
example, turning on and off an air tank worn on the back may be difficult for wearers by
themselves, and for safety reasons the self-contained air is designed to override the PAPR
so that in this configuration the PAPR would be usable only after the air tank was
exhausted.
 It may not be possible to know when to switch safely between modes, so the PAPR
functionality has limited applicability. Note that self-switching devices based on the
detection of contaminants or oxygen depletion have been proposed; it is, however, as
difficult to imagine such a device assessing all possible situations successfully as it is to
imagine that the user will be able to assess them successfully using other available
devices.
It is possible for respirators to be closed-circuit (i.e., the supplied air is rebreathed) by
using a chemically reactive system that resupplies oxygen and scrubs out excess carbon dioxide.
Their particular advantage is that they can provide breathable air for a significantly longer duration
(several hours). Although such devices have merit and are used for mine rescue, for example, no
such devices yet exist that have been demonstrated as appropriate for CBRN use. Additional
disadvantages include associated weight and bulk as well as heat production from the chemical
reactions.
Combined soldier headwear systems such as concepts proposed in the Soldier Integrated
Headwear System technology demonstration project may better integrate the many additional
functionalities required in the head region. The various NATO target capabilities that were
combined as foci in the concepts included lethality; mobility; survivability (CBRN and ballistic);
sustainability; and command, control, communications, and intelligence. Two next-generation
general design types that integrated functionalities differently were considered: a modular system
that included an integrated removable respirator and a permanently encapsulated helmet with
respiratory protection. An add-on system that used a conventional helmet and respirator was also
considered.
Bioreactive particulate filtering devices that include a biocidal layer releasing iodine
have been marketed.
Face-forming or adhesive respirators are under consideration that will remove much of
the requirement for individual fitting and sizing; superadhesive and shape memory materials may
have applications here.
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3.6.
Dermal Protective Equipment (Clothing)
3.6.1. Components of personal protective equipment
The types of items that can comprise dermal protective equipment (DPE) include jackets,
pants, hoods, socks, undergarments, overgarments and coveralls, encapsulating suits, gloves, glove
liners, and boots. How these components fit and work together with each other and with a
respirator is as important in determining the effectiveness of the system as are their individual
properties. Material choices range from inexpensive disposable options to highly chemical
impermeable laminates or polymers to air-permeable active carbon material systems.
Gloves are worn to protect the hands and wrists and, in general, can be expected to be
exposed to higher levels of surface contamination than much of the remainder of the body, as well
as requiring higher durability characteristics. Resistance to chemical permeation should be
particularly high on the fingertips and palms for those persons who could come into contact with
liquid chemicals. Increased chemical resistance is often provided by polymeric laminates and is
counter to the requirements for tactility. Grip can be improved by adding texture; this is
particularly relevant when using decontaminating solutions, which are often quite slippery.
Allowing for good finger motion may require building in some extra features that ease motions; it
is possible that the backs of the gloves could be constructed of different lighter or more permeable
materials. An example of a military CBRN polymeric glove that has finger grips, accordion-like
folds at the joints, and a cotton liner to absorb sweat is illustrated in Figure 3.10. The glove is also
ambidextrous, which has a number of advantages in the areas of cost, logistics, and ease of use for
the wearer. In a different approach, W. L. Gore has designed the Chempak Ultra Barrier Glove
System, which includes a protective, permeation-resistant fluoropolymer liner worn inside a more
fabric-like functional outer glove.
Figure 3.10. Canadian CBRN protective glove and liner.
Figure 3.11. Hazmat-style overboots (left) and military overboots (right).
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Similarly, boots worn alone or as or overboots protect the feet; the soles should be
particularly resistant to permeation, and durability is an equally important issue. The traditional
polymer boot or overboot is the most common approach (Fig. 3.11); however, the standard-wear
boot (e.g., work boot or combat boot) can also be designed with a protective membrane barrier
included, or the protection provided in, or enhanced by, an interior layer such as a separate sock
or integrated bootie.
Items of equipment not sold as CBRN DPE may also have a protective role to play; for
example, ballistic vests, helmets, and visors can provide substantial CBRN protection by acting as
an additional barrier layer.
3.6.2. Ensembles of personal protective equipment
For many years, the most prevalent protective ensembles used for CBRN protection fell
into three general categories that are still available:
 U.S. Environmental Protection Agency (EPA) categories;
 Single-use coveralls;
 Military-style active carbon systems.
These are described first, with more modern configurations following.
EPA Categories. The first category of system is the industrial spill response type, typically
described using U.S. EPA designations of level A, B, or C; see Table 3.2. These reusable and
decontaminable systems are intended to protect response crews from contact with chemicals such
as toxic and corrosive liquids (in the case of levels B and C) or to protect from all airborne
substances when concentrations reach very high levels (level A). They have no associated
performance standards.
Table 3.2. EPA Ensemble-Level Descriptions.
EPA Level
RPD
DPE
Intent of Use
A
SCBA
Fully encapsulating
Most hazardous environments
B
SCBA
Full-body
protective
C
APR
Full-body
splash
protective, or head,
hands, and feet only,
depending on hazard
analysis
D
None
Appropriate for general Minimal hazard
work environment
splash Significant respiratory hazard; dermal
hazard only from liquid contact
Respiratory hazard that can be
removed by APR (e.g., below IDLH);
dermal hazard only from liquid
contact
The level A style of totally encapsulating protection, which can be used at even the high
concentrations that can be obtained in confined spaces, is still the gold standard for CBR
protection, provided that it is well designed from highly liquidimpermeable materials (as specified
in NFPA). Levels B and C have the respirator worn at least partly outside the DPE (Fig.3.12).
There are no particular descriptors that ensure performance against airborne substances; the
materials must be impermeable to liquids, and some degree of splash protection must be provided.
Levels B and C suits are not necessarily well integrated with the peripheral items, as they are not
evaluated as a system. In summary, these systems were developed primarily for open-air response
to an accidental release of large volumes of liquid or gaseous chemicals, and because they have no
performance specifications and need not have particularly effective closures, they are not
necessarily appropriate for CBR protection unless they have demonstrated their performance as a
system.
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Any design that depends on an impermeable material combined with good closures to
provide vapor and aerosol protection is completely dependent on the total integrity of the system.
A single material or closure failure results in drastically reduced protection. Helping to compensate
for this issue, extra dermal protection is provided in all level A systems, due to the fact that the
clean exhaust air from the SCBA (contained entirely within the suit) fills the suit, and an
overpressure valve keeps the suit under positive pressure. This same type of protection can be
designed into level B and C systems by using overpressure and/or airflow through the suit to
protect against ingress or flush it of agents; this approach may also assist in evaporative cooling.
A separate positive-pressure air supply can also be used for the suit only, although this adds bulk
and complexity.
Single-use (disposable) protective coveralls are used with whatever peripheral items and
respirator are deemed expedient. This style is relevant when the dermal hazards are minimal (as in
the case of biological materials) or skin decontamination is relatively efficacious even after hours
of exposure (as in the case of radiological materials). Hence, a disposable coverall worn over
normal clothing is often felt to provide sufficient protection and is there primarily to reduce the
decontamination burden on the clothing as well as the skin. Durability is quite limited, with the
majority of the protection provided by the peripheral items.
Figure 3.12. EPA level B ensemble.
Both of the categories of equipment above imply a very high thermal burden because of
the largely air-impermeable polymeric materials used. Working time within these systems is
comfortably perhaps an hour at moderate activity levels, although it can be extended when
necessary or in cooler environments. Duration of use may be limited by durability and/or working
time.
Cold-War Military Systems. Many very early military systems were similar to the EPAstyle level C systems. However, during the cold war, the military felt that they would operate
around the clock in a contaminated environment. Therefore, the level of physiological burden that
these systems providedwas unacceptable, and an alternative approach was developed. The active-
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carbon-containing overgarments of the cold-war era were air permeable and worn with an airpurifying respirator, polymeric gloves, and overboots. They were meant to be worn over combat
clothing in cold climates, and more recently have often been worn as stand-alone systems
(replacing the uniform) in warm climates. These ensembles were designed first and foremost for
protection against militarized CW agents. This means that dermal protection was focused primarily
on keeping highly dermally toxic liquid and vapor chemicals of moderate to low volatility away
from the skin, which could be achieved through the use of adsorbent active carbon combined with
a liquid repellent outer layer. The DPE provides some protection against aerosolized materials in
general because all cloths are reasonably good filters of particles 3 m and above. Active carbon
adsorbents provide much less protection against high-volatility chemicals (many TICs), although
these are rarely dermally active, and there are a few such compounds that have been identified as
being of significant concern.
The air-permeable nature of an active carbon material, which yields considerable thermal
burden advantage, means that certain types of vapors and aerosols can penetrate freely at
sufficiently high wind speeds. Reducing the air permeability of the material system, or the size of
the air gap between the layers, reduces penetration under these conditions. Materials that filter
aerosols can provide extra protection if incorporated into the material system; active carbon fibers
afford some increased aerosol protection relative to other forms of carbon, and extra fibrous
filtration layers are also possible. Electrospun fibrous layers may offer a particular advantage here,
as they are claimed to provide better filtration capability at higher air permeability.
Protection against nuclear events (N) in such systems was focused on ensuring that the
materials were resistant to nuclear flash.
In some cases, these systems were adapted for first-responder use by making the materials
more air permeable and less liquid protective. This was not based on any effective analysis of
requirements but, rather, was primarily a drive toward comfort. Some of the more recently
designed systems that can provide improved protection or functionality over those used historically
are described below.
Protective Undergarments. As discussed previously, moving the barrier or adsorbent layer
closer to the skin affords improved protection, keeping penetration low, with the small air gap
effectively scavenged by the adsorbent. Protective undergarments or next-to-skin designs (Figure
5-12) are meant to be worn under other equipment. Outer clothing could consist of turnout gear,
street clothing, or uniforms; undergarments are also a good choice beneath specialized equipment
such as bomb disposal gear.
Undergarment components can include hoods, jerseys and pants, socks, and glove liners.
Typically, such garments contain active carbon and are stretchy for comfort and snug fit. The
active carbon provides protection against the most dermally active chemical agents, while the outer
layer can provide additional protection by acting as a barrier, reducing air permeability, or having
a liquid-repellent treatment. Overlap between components (e.g., ankle to sock) can be substantial
without needing special closures; there is little movement and no significant gaps that would cause
leakage; thus, protection can be excellent. However, thermal burden can be significant because of
the multiple layers when the overgarments are included.
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Figure 3.13. Protective undergarment system, including gloves, socks, and hood.
Recently, the first standards specifically designed for domestic response to terrorism
involving CBR agents were published in the United States. NFPA 1994 class 2 and class 3 systems
have been designed and approved for use in CBR response.
It is intended that class 2 ensembles are for incidents involving vapor or liquid hazards
where the concentrations require the use of SCBA (above IDLH), while Class 3 ensembles are for
equivalent but below-IDLH conditions. NFPA class 2 and 3 ensembles are illustrated in Fig. 3.14.
Construction of a class 2 suit requires reasonably vapor-tight closures and impermeable materials
to pass the requirements; this implies a certain degree of aerosol protection as well. A class 3
system has somewhat lower protection requirements, so the closures can be less tight. The
materials must display a certain amount of evaporative heat loss through using moisture vapor–
permeable materials, so the systems should yield a lower physiological burden. Each system is
approved in its entirety for dermal protection, including the respirator. Numerous approved class
2 and 3 systems are now available.
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Figure 3.14. NFPA 1994 class 2 ensemble (left) and class 3 ensemble (right). (Photographed by
Rick Bloomingdale, reproduced by permission of, and © Starfield-Lion, 2011.)
Other types of DPE have been investigated for their use as expedient protection for
emergency escape. For example, firefighter turnout gear worn alone can act as a barrier to an agent;
the materials are water repellent, bulky, and contain selectively moisture vapor–permeable
membrane barrier layers. Gloves are usually durable with a synthetic or leather outer, and boots
are chemically resistant. The systems are designed to be reasonably splash-proof overall, with
closures to prevent water ingress.
Therefore, there is protection intrinsic to such a system when worn with self-contained
breathing apparatus in the standard response configuration. That level of protection appropriate
for escape and rescue in a CWA release was demonstrated for these systems by the U.S. Domestic
Preparedness Program in the late 1990s. It was deemed that incorporation of protection directly
into turnout gear could lead to improved response capability in the case of a known terrorism event,
leading to the
NFPA 1971 turnout gear (CBRN option) style of equipment. The equipment is truly dualfunctional; it is meant to be worn as turnout gear for structural response, but with an additional
demonstrated capability to keep out CBR agents through a combination of an appropriately
protective barrier layer in the material system and protective features designed to be deployed to
keep out airborne substances.
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Figure 3.15. Summary explanation for EPA/OSHA protective levels
3.6.3. Emerging Concepts
Several areas are of particular interest in improving the performance of dermal protective
systems.
Military Systems. Improving human performance by reducing the physiological burden is
a major goal. The notion of lighter-weight protective uniforms for the military, designed to be
worn in place of more burdensome overgarments or stand-alone DPE when the perceived threat
or hazard is lower, is an attractive one. A protective uniform concept would provide protection
somewhere between that of a nonprotective uniform and that of a full-up ensemble that could
provide protection for days against a wide variety of hazards. It has the properties of a uniform
when worn in the open state, but can be closed up for more complete protection. A lower burden
can be achieved, for example, by reducing the weight of the materials, improving their hand and
comfort properties, or increasing the air permeability; it is important that this lower burden be
achieved in both the open (daily wear) and closed (protective) states.
The concept of use for such a uniform would be more limited, meaning that some hazards
might need to be avoided, or protection could be of shorter duration, with the intent to use the
uniform as an escape option. Nevertheless, the built-in “just in time” protection concept means
that decisions about when to don the more burdensome overgarment or stand-alone concepts do
not need to be made too early – a person has some protection all the time and remains in a relatively
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positive physiological state throughout (both prior to, and after closing up for protection). Some
of the challenges with this type of design include the durability required for it to be worn as a
uniform while maintaining protective capabilities, and retaining the correct hand properties of the
materials, to keep them as uniform-like as possible. A number of militaries are updating their
protective clothing systems to modernize and achieve a lower burden, including those of Canada,
the UK, the United States, and Germany (Fig. 3.15).
It was noted previously that class 3 NFPA 1994 systems use moisture vapor–permeable
materials, and some military concepts also include them. If total heat loss values can be made
sufficiently high, these concepts have the potential to be competitive for comfort with more highly
protective air-permeable systems while providing broader-spectrum protection. An example of a
military-style protective system incorporating MVP materials is shown in Fig. 3.16.
NFPA 1951 includes the CBRN technical rescue protective ensemble concept for use by
emergency services personnel assigned to or involved in search, rescue, treatment, recovery,
decontamination, site stabilization, extrication, and similar operations at CBRN incidents; at the
time of publication, no certified ensembles yet exist to meet this standard. Similarly, ensembles
specifically certified for use in particulate CBRN hazard incidents do not yet exist. Both NFPA
and Canadian first-responder PPE standards suggest the appropriateness of such an ensemble for
response to a biological or radiological event. ISO also specifies requirements for particulate
protective clothing; however, the testing is not based on a fully integrated system (i.e., respirator,
gloves, and boots can be substituted) and is also based on inward leakage and not deposition, and
therefore this set of requirements provides undefined particulate protection levels.
Figure 3.16. Two examples of military systems designed to be worn as stand-alone uniforms.
Left: The IdZ system, under development for the German Federal Armed Forces. (Reproduced
by permission of, and © Bl¨ucher Gmbh, 2011). Right: The CBplus uniform concept (worn in
the closed state), developed by Defence Research and Development Canada.
The Canadian standard additionally includes a wide variety of possible ensemble
configurations designed for specific capabilities within a CBRN response incident. Various
potential respirator styles are matched with suitable dermal protection capabilities as entire
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systems, suitable for the possible roles and locations within an incident. Approval of systems
against the standard is under way.
Figure 3.17. Protective system using an MVP barrier. (Photographed by Rick Bloomingdale,
reproduced by permission of, and © Starfield-Lion, 2011.)
Similarly, the U.S. National Institute of Justice has published a standard for law
enforcement ensembles. Respiratory protection is not covered, nor is protection from ballistic
threats, explosives, or ionizing radiation. The combination of respiratory protection style and
clothing yields various configurations. As of this date, no systems are approved under this
standard.
PPE for radiation protection useful for generic CBRN applications is still in its infancy.
One system approved under the NFPA 1994 class 2 category (Fig. 3.18) includes the partially
radiopaque material Demron. Demron is the only impermeable CBRN fabric that permits heat
exchange, enabling the wearer to be cooled externally without having to penetrate the suit. The
same materials have been incorporated into bomb suits and personal protective armour.
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Figure 3.18. Radiation shielding suit and shield. (Reproduced by permission of, and © Radiation
Shield Technologies, date unknown.)
By combining different functionalities, the burden can potentially be lowered, particularly
for those who must have multiple types of protection. The advanced NBC protection system for
aircrew combines protection against whole-body immersion and CBRN agents, as well as active
cooling and CBRN protection.
Figure 3.19. Radiation shielding suit (The Russian Federation Research Institute of Steel).
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Figure 3.20. Makeshift radiation shielding on Chernobyl NPP emergency.
3.7.
Future Concepts to Improve Performance in Use
There are some generic ways in which performance in use can be improved in the future,
both through design of the PPE itself and by developing better concepts of use or indicators.
Fitting. Equipment that does not fit properly will neither protect properly nor will it be
suitably functional. Therefore, designing equipment that is one size fits all with some adjustability,
that is easy to fit, or that can be preadjusted and then fixed will reduce the logistics associated with
this problem. Custom-fitted and custom-produced PPE is also a possibility with current scanning
and rapid three-dimensional printing capabilities. Real-time sensors that detect failures in fit are a
possible solution, for example, integral pressure sensors in closures that detect when a seal pressure
falls below a certain value. Approaches to rapid determination of air-purifying respirator fit in the
field are under development.
Monitoring Protective Capacity. When equipment is worn or stored too long, it may fail
to protect, due to either exceeding its normal capacity or to reduced capacity due to environmental
exposures. Hence end-of-service-life indicators or residual-life indicators for protective
performance would be of significant benefit. Since most protective materials have different
protective capacities for different agents, a one-size-fits-all approach is conceptually and
technically quite challenging.
Donning and doffing. Equipment may protect well when it is worn, but take too long to
put on properly, be put on too late, removed before completely decontaminated, or difficult to
remove without contamination transfer. Smart protective equipment that is worn all the time and
closed up automatically based on a remote sensor or environmental trigger would have benefits in
dealing with the donning issues. Ease of removal through the use of quick releases and reduction
of the likelihood of contact with contamination during removal through peelable outer layers
should be considered.
Localized exposure/contamination indicators on the exterior of the PPE would make the
decontamination and removal procedure more fool proof: for example, a colour-change material
that indicated chemical agent contamination of surfaces. Self decontaminating materials would
also reduce the likelihood of contamination during and after removal.
Multiple Hazards and Functions and System Integration. CBRN equipment is
expensive and annoying to implement and wear. It is also highly dependent on having system
integrity in order to perform adequately. Combining protection against other hazards with CBRN
protection has the advantage that the user is more likely to wear the equipment if its primary
function is something other than CBRN protection; in addition, when protection against other
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hazards, such as ballistics, moisture, or fire lies outside the CBRN layer, its integrity is more likely
to be preserved in use.
Integrating CBRN protection into the next-generation soldier system by integrating with
the helmet and other protective layers as well as planning for reduced burden on the wearer by
dual-use items such as CBRN protective footwear, or clothing requiring no extra outer layer, will
increase the likelihood that the PPE will be used when it is needed and that it will function as
desired. Increasing the breadth of the CBR hazards protected against by the PPE – for example by
using an “all-hazards” air purifying system that allows only selected gases such as oxygen and
nitrogen through or by using long-life lightweight closed-circuit breathing apparatus – would be
of huge benefit.
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4.
Decontamination Technic
As a result of accidents, when the protective barriers are destroyed, gaseous and
sublimating radioactive elements can be released from the reactors into the external environment
with steam streams: radioactive noble gases, radionuclides of iodine and caesium.
In the early phase of the accident, the actual release of radioactive substances into the
environment occurs. The duration of this period can be from several minutes to several hours in
the case of a single release and up to several days in the case of a prolonged release.
The intermediate phase of an accident is a period during which there is no additional intake
of radioactivity from the source of the release into the environment. This phase begins with the
first few hours from the moment of release and lasts up to several days, weeks or more. For onetime emissions, the length of the intermediate phase is predicted, as a rule, within 7 to 10 days.
The late phase (recovery phase) is characterized by a period of return to the conditions of
normal life of the population and can last from several weeks to several decades, depending on the
power and radionuclide composition of the release, the characteristics and size of the contaminated
area, the effectiveness of radiation protection measures. The most severe radiation accidents at
nuclear power plants, accompanied by the release of uranium and its fission products outside the
sanitary protection zone and radioactive pollution of the environment, include the so-called outof-design accidents caused by depressurization of the reactor's primary circuit. A typical example
of this type of accident is the accident at the Chernobyl NPP in April 1986.
The main source of radioactive pollution of the environment and human exposure during
nuclear reactor accidents is gas-aerosol mixtures emitted from the reactor. Radioactive aerosols
after hitting the surface of objects are fixed on it. The processes of surface and deep pollution, as
a rule, occur simultaneously.
In dry weather, radioactive contamination is mostly superficial. At the same time,
individual particles will penetrate into the recesses of the rough surface, causing deep
contamination.
When the surface is contaminated with droplets containing radioactive substances, another
mechanism is triggered: initially, the droplets will adhere to a solid surface, which in the future
will lead to an increase in the concentration of radionuclides on the surface, ion exchange and
diffusion.
In addition to primary radioactive contamination, subsequent contamination cycles, the socalled “secondary” contamination, are possible. In case of secondary contamination, radioactive
substances are transferred from a previously contaminated object or territory to a clean or less
contaminated object. Thus, radioactive contamination of terrain, structures and roads can pass into
the air or groundwater, and then precipitate, causing radioactive contamination of previously
"clean" objects, transported by transport, people or animals.
In case of accidents at nuclear power plants, there are two main periods: “iodine hazard”,
lasting up to 2 months, and “caesium hazard”, which lasts for many years.
In the "iodine period", in addition to external irradiation (up to 45% of the dose for the first
year), the main problems are associated with milk and leafy vegetables - the main "suppliers" of
iodine radionuclide inside the body. At the first stage, radiation exposure to people consists of
external and internal exposures caused, respectively, by radioactive exposures from radionuclidecontaminated environmental objects and inhalation of radionuclides with polluted air, at the
second stage - by irradiation from radionuclide-contaminated environmental objects and their
introduction into the human body with consumed food and water, and in the future - mainly due
to the consumption of contaminated food by the population.
It is generally assumed that 85% of the total predicted radiation dose for the next 50 years
after the accident is the dose of internal radiation caused by the consumption of food grown in the
contaminated area, and only 15% falls on the dose of external radiation.
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4.1.
Decontamination basis
4.1.1. Sources of Radionuclide Contaminants
During the radiological accidents, the basic recovery strategy for contaminated areas is to
identify, relocate, isolate, decontaminate and rapidly release them for unrestricted use. Areas that
cannot be decontaminated to levels allowing unrestricted are converted to uses controlled by
authorities, such as paved public squares. These strategies are effective in reducing public
disruption and stress.
The various stages of the nuclear fuel cycle and the operation and decommissioning of
nuclear reactors all have the potential to create contaminated sites. The contamination may include
mill tailings; spillage of ore end product at the mine and in transport; waste from enrichment and
fuel fabrication operations; fission product and actinide waste streams from reprocessing of fuel
elements; radioactive effluents from normal operations of nuclear power plants; wastes produced
during decommissioning of reactors; and major releases under accident conditions
Radioactive materials have been used widely since their discovery for a variety of
scientific, medical and industrial uses. In some cases, either through ignorance, carelessness, or
accident, sites have been left contaminated with residues of the operations. Such sites include
factories where radium was used in luminescent paint and thorium was used in thorium coated gas
mantles. Other locations where radionuclides have been handled have the potential for leaving
contamination.
In the course of nuclear weapons production and transport, there have been several severe
accidents resulting in considerable contamination. These include: Windscale Pile 1 (1957),
Kyshtym (1957), Palomares (1966) and Thule (1968). The spread of contamination by accident or
by human ignorance are illustrated by the cases of the TMI NPP (1979), Chernobyl NPP (1986)
and Fukushima NPP (2011).
Various types of facilities, especially reactors, produce various radionuclides due to
different moderators, coolants, structural materials, nuclear fuels, and auxiliary processes used.
Radioactive nuclear fission products such as 131I, 137Ce, and 90Sr are created in the nuclear reactor
core. There are a limited number of radioactive sources that are large enough to cause widespread
contamination. The radionuclide contaminants mainly include 60Co, 134, 137Cs, 90Sr, 238U, 129Te,
110
Ag, 232Th, 238,239,240Pu, 192Ir, 241Am, 129,131I, 97,98,99Tc, 93,95Zr, 55Fe, 94Nb, etc.
4.1.2. Behavior Characteristics of Radionuclides
During the surface decontamination of nuclear facilities, the focus is not only on the surface
deposition layer but also taking into account the radionuclide migration.
The penetrating depth varied depending on the physicochemical properties of base
materials, nature of radionuclides, etc. (Fig. 4.1). Cs had similar contamination behaviours to Sr,
but it was more inclined to surface than Sr (see Tab. 4.1). The majority of Sr remained near the
base material surface and did not penetrate beneath the surface. Therefore, the penetration depth
of Sr was smaller than that of Cs.
The permeation depth of U in rubber ranged from ten to one hundred micrometres. The
radioactivity of the deposition layer is just a proportion of radioactivity in the pipe and some
radionuclides had penetrated into the sub-surface of the base material. Stainless steel is a common
structural material used in a nuclear power plant due to their better mechanical properties and
corrosion resistance.
Tritium is considered as an important fuel for fusion reaction and stainless steel is
commonly used as a candidate structural material to make tritium containers, the facility, and the
pipe. During long-term application, the tritium penetrates the stainless steel through adsorption
and diffusion, resulting in the structure performance degradation and threatening the safety of the
stainless steel for use. Many pieces of research have been conducted to study the distribution and
speciation of tritium in stainless steel. The tritium is mainly in the form of tritiated water vapor
(HTO) and tritiated hydrogen (HT). The distribution of tritium varies based on the tritium storing
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condition and place. The tritium was released as HTO with a fraction of HT during gradual surface
etching. The HTO mostly originated from the tritium present on the outermost surface and about
90% of it could be easily released. The rest was sorbet tightly and remained in the surface layer.
Figure 4.1. Factors on the penetration of radionuclides in base materials.
Table 4.1. Characteristic of radionuclides in base material
Radionuclides
U
Sr
Bulk
Materials
Species on the Bulk
Surfaces
Rubber, cable
Stainless
steel
Stainless
steel
SrCrO4 in the oxide layer
SrCo3 in the matrix
Cs2Cr2O7 in the oxide
layer
Cs
Concrete
Sr
Cs
Y
Concrete
Cs doesn’t interact with
cement hydrates. Sr
interacts with cement
hydrates through ion
exchange with Ca. High
pH of the cement hydrate
forming a hydroxide of
low Y solubility
Depth Distributions
Rubber tube: 6.5 – 35.0 m
Rubber floor: 2.1 – 220 m
Cable insulation material:
3.5 – 38.3 m
Penetrating depth of 150nm
Penetrating depth of 15nm
Degraded concreate: several
millimetres
Cracked concrete: >10 cm
Cs: 15mm with concentration
of
approximately
110-8
mol/kg.
Sr: 3mm with concentration of
approximately 110-8 mol/kg.
Y: on the surface of the mortar
4.1.3. Surface Contamination Mechanism
Decontamination is defined as the removal of contaminants from surfaces by washing,
heating, or chemical, electrochemical, or mechanical action. It is mainly applied in nuclear facility
equipment and components, including building exteriors and interiors, equipment, pavement, and
vehicles. Sometimes, it can also concern the removal of radioactivity situated deep in the material.
During the decontaminating processes, two points need to be better understood. The first is to
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clarify the parts that need be decontaminated, and the second is to know the source of the
contaminants. The radioactive contamination is caused by radionuclide contaminants on surfaces
through mechanical adsorption, physical adsorption, or chemical reactions with different base
materials, such as stainless steel, rubber, plastic, etc. The mechanical adsorption is resulted from
the imbedding and adhesion of radionuclides in the defect of the material surface. The physical
adsorption is generated because some materials’ surfaces have charges and the radionuclides with
opposite charge are adhered on their surfaces. The chemical reaction is caused by various
reactions, such as ion exchange and isotopic exchange between radionuclides with ionic form and
materials. The type of contamination is determined by the radionuclides and base material, as well
as the system.
The main forms of radionuclides binding to the surface include:
1.
Nonfixed contaminants attached to the surface by intermolecular forces. There is no
reaction between radionuclides and base materials. The combination between them is weak
and this contaminant is easy to be removed.
2.
Weakly fixed contaminants formed through chemical adsorption or ion exchange. The
combination is strong, and the radionuclides penetrate the base material with a considerable
depth resulting the difficulty of radionuclides to be removed.
3.
Deep surface contamination formed by radionuclides diffusing to the base or neutron
irradiation activation of trace elements in the base. This contamination is difficult to be
dealt with as well.
Contamination can also be classified as being “fixed” and “loose (or free)”. Fixed
contamination is that which is not transferred from a contaminated surface to an uncontaminated
surface when two surfaces accidently touch. The radioactive material cannot be spread, since it is
chemically or mechanically bound to structures. It cannot be removed by common cleaning
methods. As a comparison, loose contamination is that which may be readily transferred under
these circumstances. The radioactive material can be spread, and this contamination can easily be
removed with simple decontamination methods. Therefore, in response to different levels of
surface contamination and the requirements for decontamination effects, it is necessary to choose
a reasonable and economic decontamination technique.
4.2.
Recent Decontamination Technologies
The decontamination process, which is the reverse of the process of radioactive
contamination, is associated with the removal of radioactive contamination from the treated
objects. In the case of surface contamination, decontamination is limited to the removal from the
surface of objects of radioactive substances that have been fixed on it as a result of adhesion and
adsorption of molecules or ions of radionuclides. For decontamination with deep contamination,
this is not enough - it becomes necessary to extract radioactive contamination that has penetrated
deep into the surface, and only after that the removal of radioactive contamination that has passed
from the depth to the surface of the object occurs. It is possible to remove radioactive contaminants
located deep in the material together with this material.
Decontamination is carried out using various methods. A decontamination method is a set
of operations using decontamination means to remove radioactive contamination from objects or
to isolate the surfaces of these objects. Decontamination methods are implemented as a result of
the impact of decontaminating solutions or media on the treated surface, taking into account the
characteristics of the object and the technical means used.
Existing decontamination methods can be classified according to various criteria, which,
on the one hand, are determined by the conditions of radioactive contamination, and, on the other
hand, by the conditions for conducting the decontamination itself. The choice of decontamination
method is dictated by the characteristics of radioactive contamination and the object itself. The
classification of all methods of decontamination can be based on two basic principles that
determine the state of aggregation of the decontaminating medium and the features of the actual
decontamination.
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Depending on the state of aggregation of the decontamination medium, all methods of
decontamination can be divided into liquid and non-liquid, as well as combined ones.
Liquid methods can be based on the use of mechanical action (water jet, ultrasound, etc.)
of solutions using physicochemical processes (adsorption, ion-exchange, membrane, etc.), as well
as on a combination of various types of action. The desire to improve the efficiency of
decontamination has led to the implementation of decontamination by a combination of different
methods. A similar combination of liquid and non-liquid processing methods is realized in the
combined processing methods, which, in particular, were used in Chernobyl. Decontamination by
superheated steam can be classified as a liquid-free method, but after steam condensation on the
surface of an object, treatment proceeds according to the liquid decontamination mechanism.
Complex decontamination should be understood as the processing of the same object in
different ways.
For example, in Chernobyl, equipment and facilities were decontaminated first using
vacuum cleaners and then using decontaminating solutions. In conditions of mass radioactive
contamination, it may be necessary to repeatedly decontaminate. In Chernobyl, multiple
decontamination was carried out involuntarily due to repeated radioactive contamination of the
same objects and insufficient efficiency of one-time treatment.
Not all decontamination methods are used equally often. For this reason, they can be
divided into two groups - main and auxiliary. Relatively rarely, decontamination is carried out
with foams and using membrane technology. In addition, auxiliary methods should include those
methods of decontamination that are carried out without the use of technical means; for example,
wiping a contaminated surface by hand with brushes or rags.
Sometimes decontamination methods are divided into physical-mechanical, chemical and
physical-chemical. Physical-mechanical methods are carried out using mechanical or physical
processes; for example, the mechanical action of a brush, the aerodynamic action of a liquid or gas
flow, etc. In chemical methods, the chemical interaction of radionuclides with the components of
the decontaminating solution occurs; it can be intensified under the action of external factors, in
particular, an electric field. Physical-chemical methods of decontamination combine the features
of the two previous ones. All non-liquid methods can be attributed to physical-mechanical
methods, and liquid and combined methods can be attributed to physical-chemical methods with
a predominance of either chemical or physical processes.
Removal of radioactive contamination in the implementation of any method of
decontamination occurs in two stages. The first stage of the decontamination process 1 is to
overcome the connection between the carriers of radioactive contamination (radioactive particles,
radionuclides in the form of molecules or ions) and the surface of the treated object. In the case of
deep contamination, decontamination consists not only in overcoming the connection between the
carriers of radioactive contamination and the surface, but also in the transfer of these
contaminations from the depth of the material to the surface. The radioactive contaminants
extracted from the material fall on the surface of the product, turn from deep into surface, and then
are removed, like surface contaminants.
No less important is the second stage of the decontamination process, which consists in the
movement of radioactive contamination from the treated object. If the second stage of the process
does not occur in full, and even more so completely absent, then the radioactive contamination in
the spent environment is deposited, and the secondary contamination of the object is already in the
process of decontamination itself.
Such a distinction between the decontamination process into two stages is somewhat
arbitrary. This conditionality is due to the fact that both stages of the process can occur either
simultaneously, or with the advantage of any one of them.
4.2.1. Physical-Mechanical Methods
Physical-mechanical decontamination techniques are physical methods that are based on
different mechanical forces, such as scraping, brushing, wiping, and scrubbing to release
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radionuclides through mechanical agitation or physical removal. They mainly include highpressure liquid jetting (high pressure and ultra-high pressure), mechanical cleaning, and airblast cleaning.
4.2.1.1.
Decontamination by gas (air) jet
During decontamination by a jet of gas (air), contamination in the form of radioactive
particles, liquid droplets, as well as structured masses are removed from the surface. The gas
stream is able to overcome only surface radioactive contamination of adhesive nature.
Practically, a gas jet is used to decontaminate objects, which escapes from the jet engine
nozzle. The velocity of the gas jet at the exit of an aircraft engine is usually 150-200 m/s, and at
the treated surface it decreases to 90110 m/s. This speed allows you to remove fairly large
radioactive particles with a diameter of more than 15 microns. The deactivation coefficient of this
method reaches only 5. When used at the Chernobyl nuclear power plant, this method was not
effective in relation to vehicles.
4.2.1.2.
Decontamination by abrasive blowing
One of the ways to increase the efficiency of processing is based on the use of an air jet
after the introduction of a powder into it that has an abrasive effect and is able to remove the top
contaminated layer. Decontamination occurs as a result of abrasive blowing, while removing both
surface and deep radioactive contamination. The decontamination coefficient can reach 200-300,
which guarantees excellent processing quality.
The abrasive powder is fed into the air environment and under its influence acquires the
necessary speed due to aerodynamic and inertial forces. Then the powder, together with the air
flow, is fed to the treated surface. Sand, carborundum, metal and other powders can be used as
abrasive material.
Decontamination is mainly carried out due to the impact of abrasive powder, and the air
jet, in this case, performs auxiliary functions: spraying powder, sending abrasive particles a certain
speed, directing them to the treated surface and removing spent particles together with radioactive
contamination from the surface of the object.
Figure 4.2. Decontamination by abrasive blowing.
In all cases of using an abrasive preparation and removing the contaminated layer, an
abrasive (sand, shot, metal and other particles) is introduced into the treated surface, chipping or
cutting off part of this surface. The performance of abrasive treatment is relatively small, it can
reach about 5 m2/h for alloy steel structures, and 25 m2/h for painted products by removing a layer
of paint.
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4.2.1.3.
Decontamination by High-Pressure Liquid Jetting
Among these mechanical methods, the high-pressure liquid jetting is a process employing
water pumped through a rotary nozzle at pressures of 10–100 MPa. These techniques have been
proved effective to clean substrate surfaces. The decontamination efficiency of water jetting for
stainless steel surfaces and the potential implications for steel recontamination. After
decontamination, water jetting at 45 more efficiently removed the passive layer than that at 90;
thus, it was more suitable for Sr decontamination treatment. The mechanism of this method for
material removal is considered to be a complex process including plastic deformations and crack
initiation, pit development, granular erosion, and water permeation into cracks and pores.
Figure 4.3. Decontamination by high-pressure liquid jetting.
The HPWJ is an effective, customizable, reliable process and uses environmentally friendly
water as a cleaning medium. However, the main problem arises from the resulting contamination
of the water, which can lead to deep cross-contamination, especially in cracks and joints. There is
a linear correlation between decontamination and water pressure at a 90 incident angle. It has the
potential to create larger volumes of liquid waste that would require effective management.
4.2.1.4.
Decontamination by vacuum cleaner
Unlike the method of decontamination with an air jet, the air flow is directed not towards
the treated surface, but away from it. This happens under the action of the vacuum created in the
air path of the device. Vacuum and a certain air flow are characteristic parameters for
decontamination by dust extraction.
In the first stage of decontamination, the removal of adhesion-bound RA contaminants is
facilitated, in addition to vacuum, by the mechanical action of the brush. The air flow picks up
radioactive contaminants, removes them from the contaminated surface and thus carries out the
second stage of the decontamination process.
During the implementation of the second stage, the air flow enclosed in the air duct is
deprived of the possibility of spreading RA pollution into the environment. Filtration of the
polluted stream makes it possible to capture the removed radioactive contamination and carry out
decontamination on the basis of a closed cycle.
Thus, in industrial and domestic vacuum cleaners that implement decontamination based
on dust extraction, in contrast to airflow, decontamination is carried out on the basis of a closed
cycle; this is the advantage of dust extraction against air jet decontamination. In addition, vacuum
cleaners require lower airflow velocities and, consequently, less powerful generators to create such
flows.
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Figure 4.4. Industrial vacuum cleaner for decontamination.
Industrial vacuum cleaners are capable of processing about 300 m2 of contaminated
surfaces in 1 hour. The capacity of these vacuum cleaners in relation to the cubic capacity of the
premises – is 150250 m3/h, and when using household vacuum cleaners, it is reduced to
6070 m3/h.
4.2.1.5.
Removing the contaminated layer and isolating the contaminated surface
In the process of removing the contaminated layer, two stages of the decontamination
process are combined in one. This method of decontamination can be implemented in relation to
the terrain, roads, painted products, building structures, as well as for any other objects, especially
after accidental radioactive contamination.
The efficiency of decontamination is determined by the depth of the removed upper
contaminated layer, which in turn depends on the depth of penetration of radionuclides into various
materials. If the depth of penetration into the soil is 5 cm, then the thickness of the removed soil
layer, which ensures effective decontamination, is 10 cm; for concrete, respectively, 0.5 and 1 cm.
The implementation of the method depends on the characteristics of the object being
processed. The top layer of soil is cut off. This is done manually in relation to limited areas and in
the case when it is impossible to use engineering equipment – bulldozers, scrapers, graders.
Despite the apparent simplicity of this method, the practical implementation is associated
with the cost of large material resources and is laborious. When the contaminated layer is removed,
along with radioactive contamination, a part of the soil itself or material is removed, the mass of
which is 1000 times or more greater than the mass of the contamination itself. To decontaminate,
for example, a 100 m2 area, approximately 20 tons of contaminated soil will need to be transferred.
This soil is a source of radioactive contamination during transportation, as well as along the route
of transport. All those surfaces with which this soil is in contact are also polluted. Burial grounds
are required for the disposal of contaminated soil; at the same time, it is necessary to exclude the
possibility of the spread of radioactive contamination from these burial grounds due to
groundwater and soil processes.
The process of soil removal itself is carried out sequentially from site to site. When using
a bulldozer, for example, the width of the processing area is limited by the width of the bulldozer
blade. During the operation of the bulldozer, dumps of radioactive contamination are formed and
there is a danger of spilling part of the soil from the dumps onto already treated areas. Therefore,
careful organization of work on soil decontamination is required, which excludes the possibility
of transfer of contaminated soil to the treated areas.
Equally problematic are the decontamination of equipment, buildings and steel structures.
Due to the fact that the depth of the removed layer is relatively small in relation to the contaminated
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layer, the mass of the removed contaminated layer is less than when the soil is decontaminated.
However, the top layer of soil is removed with less effort than the top layer from various materials
and equipment. In addition, the elastic properties of the removed material contribute to a greater
distribution of this material into the environment and create a greater likelihood of secondary
contamination.
Figure 4.5. Mechanical decontamination.
Mechanical methods are carried out by grinding, the impact of brushes and scrapers, using
jackhammers and drills.
4.2.2. Chemical Methods
Chemical methods are mainly based on reactions such as dissolution, oxidation/reduction,
complexation, and sequestration to remove contaminants from the surface. This method mainly
includes reagent washing, foam decontamination, chemical gel, strippable coating,
electrochemical gel decontamination, etc. Reagents used for chemical decontamination approach
include water alone or with soap, surfactants, acids, bases, chelating agents, or redox changing
agents. Foams, gels, or pastes are used to provide a longer contact time and thereby enhance
removal.
4.2.2.1.
Reagent Washing
Reagent washing is a simple decontamination method, which is more effective for smooth
nonporous surfaces. Many decontamination solutions have been applied, the use of which depends
on the contaminant and surface chemistry, as well as the secondary waste generated.
Typical reagents used in decontamination solutions include water, detergents and
surfactants, acids, chelators, redox agents, foams and gels, and hybrid and proprietary solutions.
Among them, water is available for most ionic compounds and mainly applied to smearable
contamination. Its decontamination efficiency can be improved by increasing temperature or
adding wetting agents and detergents. Most commercial detergents have a detergent acting as a
wetting agent or surfactant. While detergents have limited effectiveness by themselves, they are
effective at enhancing other decontamination solutions.
Surfactants can decrease the surface tension and increase liquid contact with the
contaminated surface. The role of acids is to react with and dissolve metal oxide films containing
contaminations or to etch the base metal and release the contaminant. Compared with inorganic
acids, the organic acids offer advantages of safer handling and the ability to sequester
contaminants. The concrete was first washed with hydrochloric acid to decompose CaCO3 and
thus decrease the pH of concrete. The 60Co and 137Cs removal efficiency were 85% and 76.3% at
this stage. Then, the electrokinetic method was applied with acetic acid with 60Co and 137Cs
removal of 99.7% and 99.6%, respectively.
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Figure 4.6. Reagent washing of contaminated surfaces.
Chelation techniques are best used on nonporous surfaces and generally applied to fixed
contamination that is not readily removed by simpler methods. Complexing agents are often used
in combination with detergents, acids, and oxidizing agents. Reduction and oxidation agents are
used to change the oxidation state of a metal and make it more soluble or more conducive to other
decontamination methods. Foams and gels are used as carrier media for other decontamination
agents. They have little decontamination ability by themselves but can enhance other agents’
efficiency by sticking to a surface and providing longer contact times. Hybrid and proprietary
solutions can increase the decontamination factor over conventional washes. These systems
combine several solution types and use gels, foams, pastes, and combinations of each for delivery
and enhanced efficiency.
4.2.2.2.
Foam Decontamination
Foam decontamination, also known as decontamination foam, is achieved by spraying the
detergents and wetting agents with hydrophilic groups or hydrophobic groups with a high pressure.
The foam, as a carrier for chemical decontamination agents, is formed on the facility surface,
which collapses after decontamination and drains away.
The composition of foams may include other substances that accelerate decontamination.
Thus, oxalic acid and a mixture of silica gel with dolomite as a sorbent were introduced into one
of the compositions.
When using foams, the effectiveness of the method is determined by a thin layer of liquid
in contact with the contaminated surface. The remaining liquid of the solution turns out to be
useless. The foam uses most of the liquid for decontamination, which allows at least 5 times to
reduce the consumption of the solution. The use of colloidal properties of foam bubbles also makes
it possible to increase the processing efficiency.
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Figure 4.7. Foam decontamination.
Foams make it possible to deactivate such objects for which other methods are
unacceptable; for example, airplanes and helicopters; surfaces of complex configuration, the
recesses of which are available for foam; some types of optical, electronic and other equipment.
Decontamination foams can be used in various ways. The first of them is based on the
application of foam, exposure (exposure) for a certain time on the treated surface. In addition, it is
possible to treat surfaces based on the second option – by circulating foam, as well as cleaning the
aqueous medium with foam.
The most common foam method is implemented in the first variant, when after application
and exposure, which is calculated in tens of minutes, the foam is removed in various ways: by
water jet, by vacuum, by mechanical means.
The effectiveness of decontamination in conditions of severe radioactive contamination is
high with sufficient time of foam exposure to the contaminated surface.
The disadvantages of this decontamination method are associated with the implementation
of the second stage of the decontamination process. The transporting capacity of the foam is
insignificant. Over time, the foam goes out, which makes it possible for radioactive contamination
to settle again on the already treated surface. This circumstance determines the two-stage
treatment, while the water consumption for flushing the foam is up to ten times higher than the
consumption of the foaming solution.
As compared to the use of chemical decontamination solution, the decontamination foam
decreased the secondary waste by 80%. With the temperature dropping from -10 to +10C, the
viscosity of the foam solution significantly increased, and the half-life of the foam increased from
181.5 to 2758 min. It is worth noting that decontamination efficiency may be decreased if foams
are unstable. Therefore, it is the key issue for a successful decontamination process to stabilize the
decontamination foam. Improving foam stability can lead to the increase in decontamination time,
which is conducive to improving the decontamination efficiency.
4.2.2.3.
Chemical Gels
The use of chemical gels aims to overcome problems associated with chemical-based
decontamination techniques, such as reagent baths, foaming solutions, or solvents. The gels are
commonly prepared by dispersing thickening agents, such as silica or alumina particles in solution,
forming a gel-like suspension. The excellent rheological properties for decontamination gels allow
them to be sprayed and remain attached to surface. This allows the implementation of this
technique over large surfaces at large scale. The gels crack after drying, forming non-dust flakes
where the contaminants are trapped and are easily removed by brushing or vacuum cleaning
(Fig. 4.4). It offers advantages of safe handling, high penetration, and small volumes of secondary
waste. The decontamination process is more efficient for nonporous materials and the
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decontamination factors could reach more than 90%. Was developed a polyvinyl alcohol–borax
complex-based spray coating containing adsorbents (Prussian blue, bentonite, and sulfur-zeolite)
for the decontamination of 137Cs-contaminated surfaces. The gel-like coating adheres to vertical
surfaces with a 137Cs removal efficiency of 56.9%, as compared with 27.2% for DeconGel.
Figure 4.8. Applying of gels for decontamination.
In addition, the coating could be easily removed by rinsing with water leaving no residue.
4.2.2.4.
Strippable Coating
Some methods are a combination of chemical and mechanical or a hybrid of the two.
Strippable coatings use chemical and adhesive methods to remove the contamination from the
surface and again require mechanical peeling of the coating. Was prepared a strippable coating
using acrylate emulsion as the main film-forming agent and lauryl sodium sulphate as surfactant.
The decontamination rate reached 92.26% for uranium dust on the concrete surface with a dosage
of 2.5 kg m2. Also was employed a biodegradable strippable coating to surfaces contaminated with
60
Co, 133Ba, 137Cs, and 241Am. Up to 95% of decontamination factors were obtained for these
radioactive isotopes.
Figure 4.9. Applying of strippable coatings for decontamination.
Was explored the feasibility of applying chitosan gels with or without Fe3O4 nanoparticles
to deal with radioactive contamination. A removal efficiency of 85% was achieved for
noncompatible waste contaminated with uranium. For the strippable coating method, it has no
airborne contamination and secondary liquid waste. However, it is best suited for smaller
decontamination activities and only worked for easily removed contaminants.
4.2.3. Electrochemical Method
Electrochemical decontamination includes electrolysis, electrophoresis, and electro
osmosis, in which processing the contaminated surface is immersed in a certain electrolyte as the
anode. The electrolysis corrodes the anode, so that the nuclide pollutants in the metal surface layer
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are dissolved into the electrolyte solution achieving the purpose of removing nuclides. Compared
to other chemical decontamination technology, the solution can be reused by filtering and adding
an electrolyte. It is suitable for deep decontamination of carbon steel, stainless steel, aluminum,
and other metal surfaces produced during the decommissioning of nuclear facilities. Was
investigated the electrochemical decontamination of irradiated nuclear graphite in an acid medium.
The reduction in 60Co activity by a factor of 210 and Cs activity by a factor of 7100 was
achieved. Was coupled electrochemical decontamination with ultrasonic technology, and the
decontamination effect was compared with that for individual electrochemical decontamination.
The results indicated that the ultrasonic-assisted electrochemical decontamination had
advantages such as good decontamination efficiency, simple equipment, fewer chemical reagents,
etc. Was used the electro-coagulation technique to remove uranium from stainless steel. The
removal efficiencies of 90% uranium were obtained in using a molar solution of H2SO4 as a
support electrolyte and a potential of 2.4 V. The electrochemical method has a high efficiency with
a small volume of secondary waste. However, the saturated solutions require appropriate processes
for final treatment.
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5.
Decontamination in the radiological accident case
The most dangerous source of radioactive contamination of surfaces, equipment and
buildings is the release of radioactive substances into the atmosphere and the spread of these
emissions in the form of an aerosol cloud. During the movement of this cloud, radioactive particles
settle and fix them on objects that are on the surface along the path of movement of this cloud.
Exposure to radioactive substances after an emergency release is manifested in the
exposure of people as a result of external and internal exposure, measured by the radiation dose.
In total, the dose of external radiation after mass pollution, including after the Chernobyl disaster,
is caused by -radiation from clouds, volatile radioactive products and gases when radionuclides
are in the air; -radiation from contaminated terrain and objects on it; -radiation of particles that
have fallen on human skin; -radiation from all contaminated objects.
The dose of internal radiation is determined by the effect of absorbed radioactive iodine on
the thyroid gland; radiation in the lungs of inhaled radioactive substances; radiation in the
gastrointestinal tract as a result of ingestion of radionuclides orally with contaminated water and
food.
The particle sizes during aerosol release determine the nature of the fallout of radioactive
particles and the features of the formation of pollution zones during the movement of the aerosol
cloud. Radioactive contamination can be divided depending on their level and distinguish shortrange, regional and long-range precipitation, as well as the transboundary spread of radioactive
particles.
Each of these precipitations is caused mainly by particles of a certain group. The most
severe pollution is observed directly near the emergency facility due to group 1 particles and pieces
of various origin (in case of an accident at a nuclear power plant, these may be fragments of fuel
rods, graphite, structures and communications). It is this part of the nearest zone that is
decontaminated in the first place.
As a conditional boundary of regional pollution caused by the deposition of radioactive
particles of groups 2 and mainly 3, it is possible to take the territory limited by isolines with a dose
rate of 0.5 mSv/h. The boundary between the zones is conditional due to the possibility of transfer
of radioactive substances.
Long-range precipitation occurred due to particles of group 3 and mainly group 4. Longrange radioactive contamination is usually slightly higher than background. In some cases,
especially during rain and descending air flows, pollution may exceed permissible standards,
which requires decontamination.
Decontamination of buildings and surfaces and fixation of remaining radioactivity may be
necessary. The magnitude of the radiological consequences will determine the degree of action
necessary. Depending upon the type of area affected, the responsible authorities should take the
necessary steps to measure the radioactivity in the areas affected and to calculate the resulting
potential doses to persons. Depending on the level of decontamination, the types of surfaces and
size of the area affected, continuous monitoring of radiation dose rates at certain locations may be
necessary for some time. The cumulative doses to persons present in areas to which access is
controlled can be measured by integrating dosimeters.
5.1.
Decontamination of settlements
Decontamination of settlements was one of the main countermeasures during the initial
stage of accidental response. The purpose of settlement decontamination after the Chernobyl
accident was the removal of radiation source distributed in the urban environment inhabited by
humans to isolated or at least remote places. The decontamination efficiency may be determined
by means of the following parameters:
 Decontamination Factor (DF) The efficiency of techniques in removing radioactivity from
a surface. For example, a DF of 2 means that a reduction in contamination (alpha or
beta/gamma activity) on the surface by a factor of 2 is seen following decontamination.
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 Decontamination Reduction Factor (DRF) The reduction in gamma dose rate above a
surface following decontamination. For example, a DRF of 5 means that, following
decontamination, the dose rate 1 m above the surface is reduced by a factor of 5.
 Decontamination Reduction (DR) The reduction in overall external exposure from
deposited gamma-emitting material from all surfaces in the environment where an
individual is located, taking into account any decontamination that has taken place. For
example, a DF of 2 on roofs may result in a DR of 10% in the first year following
deposition.
The information upon the effectiveness of different decontamination technologies
accumulated by the present time could be chronologically and by subjects structured in the
following way:
1.
Results of laboratory and field investigations both before and after the Chernobyl accident,
during which there have been determined the values of the DF and DRF factors for separate
decontamination technologies conformably to different surfaces and objects in the
anthropogenic environment.
2.
Results of the carrying out large-scale measures upon the decontamination of settlements
on the territories of Russia, Ukraine and Byelorussia radioactively contaminated after the
accident at the Chernobyl NPP. After doing these actions, there were received for the first
time the values of the DR factor based not on calculations, but on measurements of the
dose reduction effect for the external exposure among different groups of population.
3.
Results of a number of local field experiments (in 1989, 1990, 1995 and 1997) upon
decontaminating small areas and buildings situated on them in the countryside of the
Russia and Belarus.
The most interesting results appurtenant to the first group has been published as Riso
report. It constitutes a catalogue of achievable “local” dose reduction factors or decontamination
factors and other important parameters for different clean-up procedures in various types of
environmental scenarios. The estimates were based on experimental work to assess the effect of
dose reducing countermeasures in areas contaminated about 9 years ago by radioactive material
released during the Chernobyl accident. However, it is very difficult on this background to get a
clear view of the total dose-reducing effect (in terms of DR) in the anthropogenic areas of carrying
out a whole series of countermeasures on different surfaces, as it would be done in practice.
Large-scaled decontamination was performed in 1986-1989 in cities and villages of FSU
most contaminated after the Chernobyl accident. This activity was performed usually by military
personnel and included washing of building with water or special solutions, cleaning of residential
areas, removal of contaminated soil, cleaning and washing of roads, and decontamination of open
water supplies. Special attention was paid to kindergartens, schools, hospitals, and other buildings
frequently visited by large numbers of persons. During large-scaled decontamination campaign in
1986-1989 about one thousand of settlements were treated, tens of thousand inhabited and social
buildings, more than thousand of agricultural farms. Depending on decontamination technologies
the dose rate over different visited plots was decreased by a factor from 1.5 to 15. But high cost of
this activity hindered to clean totally the whole settlement territory and especially its vicinity,
fields, meadows, forests where significant part of population spends a lot of time. Due to these
conditions actual effectiveness of the annual external dose decrease after upper soil layer removal
around houses, social and production buildings usually was 10 to 20% for average population
ranging from about 30% for children visiting kindergarten and schools to less than 10% for outdoor
workers (herders, foresters, etc.). These data were confirmed by individual external dose
measurements. The averted collective external dose in 90 thousand of inhabitants of 93 most
contaminated settlements of the Brynsk region in Russia due to large-scaled decontamination in
1989 was estimated to be about 1 thousand man-Sv.
In the early period of the accident inhalation of resuspended radioactive particles of soil
and nuclear fuel could significantly contribute to the internal dose. To suppress dust formation the
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method of dispersion of organic solution over contaminated plots was chosen which created
invisible polymer film after natural drying. This method was implemented on the Chernobyl NPP
and in 30-km zone during Spring - Summer 1986. Streets in cities were watered to prevent dust
formation and to remove radionuclides in the sewerage system. The effectiveness of early
decontamination efforts in 1986 still remains to be quantified. However, daily washing of streets
in Kiev decreased collective external dose to its 3 million inhabitants by 3000 man-Sv and
decontamination of schools and school areas saved 600 man-Sv.
The most interesting from the point of planning the decontamination strategy in a remote
period after radioactive fall-outs is the third data group. These data are received in the course of
carrying out a local decontamination of 35 houses and the surrounding territory in a rural areas
of the Bryansk region (Russia) and Belarus 3 14 years after the radioactive fall-outs. The analysis
of the results of this work permits to come to the following conclusions that have practical
importance for choosing decontamination strategy and methods:

10 years after the radioactive fall-outs, the main sources that define the external radiation
dose rate outdoors are the contaminated areas of soil. The dose rate contribution from roads
and trees practically disappear within the first five years.

the main contributor to the dose rate inside the one-story houses was the contaminated soil
around houses but roofs also made a significant contribution, whereas radiation from the
walls was comparatively insignificant.

more than 90% of the activity in soil is accumulated in the upper 10 cm layer.
5.1.1. Recommended decontamination technologies
Planning the decontamination activity it is important to take into account contribution of
the external dose in the total dose. In the areas with dominating soil type reach with clay, low
transfer of caesium radionuclides along the food chain and consequently low internal dose relative
decrease of total dose is close to decontamination effectiveness. In contrary, in the peaty soil areas
where long-term internal exposure dominates relative decrease of the total dose due to village
decontamination is expected to be insignificant.
Following dry deposition, street cleaning, removal of trees and shrubs and digging the
garden are efficient and inexpensive means of achieving very significant reductions in dose and
would rate highly in a list of priorities. Roofs are important contributors to dose but the cost of
cleaning roofs is high and this would not rank highly in a list of priorities.
Walls contribute little to dose, are expensive and difficult to decontaminate and would
therefore carry a very low rating in a list of priorities.
In the case of wet deposition the garden will be given first priority since a considerable
reduction in dose (60%) can be achieved at relatively low cost. Street cleaning would also be
useful.
The priorities that different procedures would be given in a decontamination strategy would
be greatly environment-specific. Nevertheless, basing on the accumulated experience of the study
upon this problem, the following set of the major decontamination procedures could be
recommended:
1.
Removal of the upper 5÷10 cm layer of soil (it depends on the activity distribution in
depth) in courtyards in front of residential buildings, around public buildings, schools and
kindergartens, from roadsides inside a settlement. The removed most contaminated layer
of soil gets placed into the holes specially dug on the territory of a private homestead land
or on the territory of a settlement when decontaminating the settlement as a whole. At
that the clean soil (sand) from the dug holes gets used for covering decontaminated areas.
Such technology excludes the formation of special burials of radioactive waste.
2.
Deep ploughing of private fruit gardens’ territories (if they hadn’t been ploughed up by
this time), or removal of the upper 5÷10 cm layer of the soil. By this time vegetable
gardens have been ploughed up many times, and in this case the activity distribution in
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soil will be uniform in the layer 20÷30 cm deep (it might be different in the abandoned
area).
3.
Covering the decontaminated parts with a layer of «clean sand», or, where possible, with
a layer of gravel to attenuate residual radiation.
4.
Cleaning the roofs or their replacement (the roof decontamination should be done before
decontaminating the under spread surface).
The list of these procedures can be applied both for decontaminating single private
homestead lands and houses, and also for decontaminating settlements as a whole. It is evident
that in the latter case the influence of the decontamination upon the further external radiation dose
reduction will be greater. Achievable decontamination factors for various urban surfaces are
presented in the Table 5.1. Detailed data on the efficiency, realisation technology, necessary
equipment, cost and time expenses, quantity of radioactive waste, and other parameters of separate
decontamination procedures are contained in the report.
Table 5.1. Achievable Decontamination Factors for Various Urban Surfaces.
5.1.2. Justification and Optimization
In accordance with the present methodology of radiation protection, a decision on
decontamination and selection of an optimal decontamination technology should be taken with
calculating costs of all the actions and social factors.
Calculated cost of actions relates to various decontamination technologies for which the
assessment of the averted dose has been made. Benefit (averted collective effective dose) and
detriment (expenses, collective dose of decontamination workers) are also compared for each
decontamination technology with the accepted cost of one Man-Sv or by means of multi-factorial
analysis. If prognostic value of net effects of decontamination for all the considered technologies
is positive, the application of these protection measures should be considered founded.
5.2.
Decontamination of people and personnel
Humans are constantly exposed to substances of varying toxicities, ranging from chemical
agents and pesticides to radioactive substances. Thus, the ability to prevent or slow absorption of
these toxicants is vital.
Decontamination is a crucial step in the care to victims exposed to radioactive substances.
To be beneficial to victims, it must be performed as quickly as possible following exposure, and
as thoroughly as possible on the body surface which not only includes skin but also wounds, hair,
eyes, and other mucous membranes.
Decontamination is defined as the process of making any person, object, or area safe by
absorbing, destroying, neutralizing, making harmless, or removing chemical or biological agents,
or by removing radioactive material clinging to or around it. Human decontamination has two
main objectives: firstly, to improve the prognosis, functional and vital, of contaminated victims,
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and secondly, to reduce the transfer of contamination from the body surface to media, including
noncontaminated skin, with which it interacts.
From a practical point of view, decontamination is usually performed in two consecutive
steps: the first one, “emergency decontamination” consists in partial disrobing and use of
emergency decontamination kit on the unprotected body surfaces, and the second one, “thorough
decontamination” consists in total disrobing followed with showering.
Emergency decontamination kits include absorbents, for example, handkerchief, paper,
towel, clean fabric, and adsorbent powders such as Fuller’s earth, talcum, flour, clean sand, and
cat litter. Adsorbent powders are poured on the contaminated area, then either left until a shower
can be performed or, after a short contact time, removed with a towel or more effectively with
water.
Showering can be performed with different systems, for example, fixed shower, mobile
decontamination unit, ladder pipes from the Fire Services, and by implementing different protocols
varying according to the duration, water temperature, additive to water, water flow rate, and
pressure.
When choosing a decontamination kit, one has to consider not only effectiveness but also
skin, wound and eye biocompatibility, ease and restrictions of use, cost, stability and storage
conditions, and elimination after usage.
5.2.1. Harmful effects of emergency radiation exposure skin
Incidents occurring in laboratories, hospitals, nuclear power plants, etc., involving small
amounts of radionuclides with the potential contamination of one or a few individuals are small
scale. Radiation-safety and medical professionals are likely to be on the premises or nearby as
employees or contract personnel. In nearly all cases, initial responding individuals will be coworkers and supervisors who are responsible for notifying radiation-safety staff/ officers (health
physicists) and upper management.
The radiological control staff is responsible for initial assessment and, in consultation with
management, for determining the course of action for management of the contaminated person or
persons, and the steps required to confine the contaminating radionuclides to the location of the
incident. Appropriate local, state, or federal regulators may require notification, depending on the
nature of the incident (e.g., the theft of radioactive material or the innocent finding of radioactive
material).
Incidents involving relatively-large quantities of radionuclides and the potential
contamination of large numbers of people are large scale. Examples of large-scale incidents
include terrorist attacks with radiological weapons, nuclear-weapons detonations, and nuclear
power plant accidents. Initial responders may be law enforcement, firefighters, and local disaster
response teams.
Incidents may require designation of several areas, based on levels of contamination and
the needs for successfully mediating the incident. The latter includes ensuring the confinement of
the radionuclides to the contaminated area while effectively managing contaminated people.
Some of the personnel noted below may be involved in a small-scale incident, and even
large-scale incidents may not call for all of these personnel (or they may not all be available). The
person(s) in charge of the incident response will be responsible for determining which roles are
required and to make the best use of the available personnel and resources.
Contamination of skin surfaces suggest possible intakes through absorption, but only in
cases of very heavy contamination would absorption result in significant internal contamination,
even if the radionuclide is in a soluble form. Injuries with contaminated debris and shrapnel are
clear evidence of internal contamination. Contamination of the mouth and other oral surfaces
suggest possible intakes by ingestion, not necessarily in contaminated food, but by touching the
face and mouth with contaminated hands. Wounds in areas of skin contamination are strong
indicators of possible radionuclide intakes.
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The effects in the skin of greatest importance in radiation protection are those from
exposures to beta-particle radiation of various energies and low-energy gamma rays, because
damage that may be caused by more penetrating x and gamma rays will generally be restricted by
the limit on the effective dose. Exposure to very high doses over a very small area from moderate
to high-energy beta rays, such as can occur with radioactive particles, in particular, the so-called
‘hot particle’, pose a special problem. Because of the very low penetration of alpha particles,
radiation doses from alpha particles could be high in the superficial layers of the skin without
appreciable dose to the cells of the basal layer. There have not been any reports of deterministic
effects resulting from alpha-particle exposure.
The major acute deterministic effects are:
1)
moist desquamation which results from damage to skin after high-dose acute exposure of
the skin to moderate to high-energy β radiations or low-energy X rays;
2)
acute ulceration which results from interphase death of fibroblasts and vascular endothelial
cells may be seen with irradiation from “hot particles”;
3)
acute epithelial necrosis which is caused by interphase death of post mitotic suprabasal
cells in the epidermis after exposure to low-energy beta particles of energies about 0.2 MeV
maximum energy.
The threshold for acute exposures of large areas is about 20 Gy. Protraction of the
irradiation decreases the effect and at a dose rate of 0.4 Gy/h no acute tissue breakdown was found
with total doses of about 100 Gy.
Dermal atrophy and damage to the vasculature (including telangiectasia) are the main late
effects of acute exposures and also chronic exposures from moderate to high-energy radiations.
Dermal atrophy, detected as induration of the skin, a minor detriment, can occur at doses below
the threshold for acute breakdown of the skin and thus could be considered the limiting effect.
The characteristic of ‘hot particle’ exposure is that very high doses can occur over a very
small area and the measurement of the dose over small areas is a difficult problem. The number of
cells at risk is so small that the risk of cancer induction is considered minor. The lesion of concern
is acute ulceration which with subsequent infection can lead to a more severe lesion.
5.2.2. General protective actions in case of radioactive contamination
Medical and radiation-safety personnel who are first responders to an incident in which
persons may have been exposed to radionuclides have six major objectives:
 provide medical aid to exposed individuals;
 identify irradiated and contaminated individuals;
 detect and identify radioactive material;
 identify sources of external radiation;
 control the radionuclide contamination, preventing the spread of radionuclides beyond
the incident site; and
 initiate decontamination of individuals and the site.
The highest priority should be to provide medical care to all injured, exposed and
unexposed. However, in principle, all of these objectives should be pursued simultaneously by all
first responders. It is important that these major objectives be achieved with the utmost attention
to protection of exposed persons as well as the professionals attending them.
An effective response to an incident in which persons may be contaminated with
radionuclides, whether the incident is small involving one or a few individuals or very large
involving large numbers of individuals, requires that qualified experts, medical personnel
(physicians, nurses, and medical technicians) and radiation safety personnel (radiation safety
officers, health physicists, and radiation protection technicians) work as a team.
In an ideal situation, a radionuclide contamination incident will occur in a location where
both medical and radiation-safety staff are available. Fortunately, that is almost always the case
since nearly all incidents are accidents occurring in facilities routinely handling radioactive
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materials, such as hospitals, research laboratories, universities, government nuclear sites, nuclear
power stations, and industries using radionuclides. These institutions generally employ radiationsafety officers and have trained medical staff available.
When contamination incidents occur, extensive prehospital care is generally possible,
depending upon the training of the personnel and the availability of instrumentation. Ideally, the
personnel at the onsite facility will have removed all transferable radioactive material from the
patient, estimated the severity of internal contamination, and provided emergency first aid for
wounds before the patient is moved to the hospital. In general, the hospital is used only for
definitive medical care.
Obviously, when large incidents occur and many people are exposed, considerable
ingenuity is required to manage contaminated individuals efficiently and effectively.
The radiological nature of an incident may not be immediately obvious, especially in the
event of a large explosion that causes confusion, ignites fires, damages structures, and injures and
kills bystanders. Until the radiological nature of an incident is recognized (and, to some extent,
even afterwards), the highest priority should be devoted to rescue and lifesaving operations,
performing triage on injured persons, evacuating the most seriously injured, and other immediately
necessary actions (e.g., firefighting). Once the radiological nature of the incident is recognized, it
will also be important to determine the nature and extent of the contamination, after which the
entire contaminated area should be cordoned off and radiation warning signs posted and radiation
control zones established.
The potential offsite transport of radioactive materials through air or water contamination
and by people and vehicles passing through contaminated areas will be the concern of those
responsible for public health and environmental safety.
The presence of radioactive contamination will determine the need for PPE such as gloves,
respiratory protection, and shoe covers for those entering the area. Persons leaving a contaminated
area must remove their PPE and (if necessary) decontaminate themselves prior to exit.
The presence of elevated radiation levels will determine the radiological stay-times for
persons working in the area. Radiologically-controlled areas will be established to recognize both
contamination and radiation levels.
Personnel responding to a radiological incident will use radiation detectors to determine
the location of perimeter boundaries. Contamination limits are typically provided in units of
becquerel or disintegrations per minute in a reference area [e.g., becquerel per square centimeter
(Bq cm–2), or disintegrations per minute per 100 square centimeter (disintegrations per minute
100 cm–2)]. Radiation detectors do not read directly in units of becquerel or disintegrations per
minute; they read in counts per minute. Each meter has a counting efficiency for each energy and
type of radiation it is measuring; the meter reading is equal to the amount of contamination
multiplied by the counting efficiency, which is calculated when a meter is calibrated. To convert
from the meter reading of counts per minute to the required units of disintegrations per minute, the
user must divide the displayed count by the counting efficiency.
For example, if a reading of 1,000 cpm is displayed on the meter face, and the meter is
known to have a counting efficiency of 10 %, then the amount of contamination present is equal
to 1,000 cpm divided by 0.10 = 10,000 dpm.
The area in which the release of radionuclides occurs should be isolated to prevent the
spread of contamination to unaffected areas.
Any emergency-response personnel entering the area should be prepared to work in a
contaminated environment, and those leaving the area should be monitored and decontaminated
as necessary.
To prevent the spread of radionuclides beyond the area of the incident, control areas should
be established. Figure 5.1 provides a generic example of how control areas might be established.
Three defined areas are shown:
 inner contaminated area where the radionuclide release occurred;
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 outer contaminated area where released activity may be transported such as by
explosions, air currents or inadvertently by people walking and vehicles driving from the
release area; and
 secured (clean) area, where entry and egress are controlled to minimize further
contamination of people, facilities and the environment.
This radionuclide control concept can apply to a broad spectrum of accidental and
deliberate contamination incidents such as explosions, fires, ruptures of sources, and spills of
radioactive materials in industrial settings, laboratories and hospitals.
The particular situation will determine the configuration of control zones and the criteria
for establishing contamination levels. In situations where the released radionuclides are totally
contained at the site of release, the outer contaminated area would not be needed. Control areas or
zones could be defined quite differently, depending upon the nature and the magnitude of the
radionuclide source. For example, to attain the same objective, control of the released activity, an
incident in a building would require an approach different from those in rural or urban sites.
Applying the example in Figure 5.1 to a spill in a laboratory, the inner contaminated area is the
location of a radionuclide release or spill (e.g., on a bench or laboratory floor). A radiation control
point would be immediately established (perhaps only a step-off pad) to minimize the spread of
the contamination. The laboratory or the corridor leading to the laboratory might be established as
the outer contaminated area where activity may have, or is likely to, spread as a result of movement
of people, equipment or ambient air. The whole building might be defined as the third, secured
(clean) area, where entry and exit of persons and equipment would be controlled. The controlling
radiation dose rates and contamination levels established by the radiation-safety personnel would
depend upon the nature of the incident. These control areas should be cordoned off with barriers
in place or locked doors and identified appropriately.
Figure 5.1. A generic example of areas designated for specific activities in management of
exposed persons after an incident involving the release of radionuclides.
In the generic example, Fig. 5.1, triage, medical-response, and decontamination activities
are located outside the perimeter of the outer contaminated area but within the perimeter of the
secured area. This concept of control zones is used in general response procedures for hazardous
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materials. Control areas at hazardous materials incident sites are designated based upon safety and
the degree of hazard. In radionuclide contamination incidents control zones help to limit the
absorbed doses received by individual emergency responders as well as to facilitate effective
management of exposed individuals.
First responders may be required to perform various surveys to detect external radiation
sources and radioactive contamination. A major objective of onsite medical assessment or triage
is an early identification of persons exposed to external radiation and those externally and
internally contaminated with radionuclides.
Other stages in the management of contaminated individuals onsite and at treatment
facilities, require further and more thorough surveys for radionuclide contamination.
Table 5.2. Types of surveys and appropriate instruments.
Survey
Hands and feet
(exiting room)
Survey type
Contamination
Meter and Probe
Hand and foot monitor
(GM)
Count wipes in well
counter, or with meter
Energy compensated GM,
ion chamber or micro-R
meter
Smear wipe
Removable
contamination
Area survey
Radiation
Spills, personnel
surveys
Contamination
GM and/or alpha detector
Radionuclide
identification
Contamination
Portable spectroscopy
survey meter
Personnel
Contamination
Portal monitor
Figure 5.2. Surveys and appropriate instruments.
80
Record result in
Becquerel (dmp)
Becquerel (dmp)
mGy or mSv h-1 or
µGy or µSv h-1
Becquerel (dmp)
Output varies,
radionuclide and
activity determination
Becquerel (dmp)
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5.3.
Contamination Control
5.3.1. Contamination Control Practices
Appropriate contamination control measures should be taken, when such measures do not
interfere with necessary emergency medical attention.
Factors influencing the need for contamination control measures:
 injuries or other medical concerns (e.g., lacerations, smoke inhalation, embedded
materials, burns, respiratory or cardiac distress, broken limbs, shock);
 contamination of the individual (e.g., skin contamination, inhaled or ingested activity,
contaminated clothing or hair);
 contamination at the scene (e.g., spilled liquids, radioactive powder, and fallout);
 other dangers at the scene (e.g., fire, unstable structures, spilled chemicals, broken glass,
dangerously high radiation levels, explosives).
Contamination control will be a primary concern only if the contaminated person is lightly
injured or uninjured and there are no other hazards at the scene. However, the presence of other
significant hazards or serious injuries should take priority over contamination control.
5.3.2. Contamination Control of Exposed People
Contamination control (see Fig.5.3) should not interfere with caring for severely-injured
people. Contamination control may include:
 removing the person’s contaminated clothing;
 wrapping the individual to control the spread of contamination;
 decontaminating the contaminated person.
Figure 5.3. Surveys and appropriate instruments.
Figure 5.4. illustrates important concepts of radiologically-controlled areas and their
use. These apply to the sites of radionuclide releases (contamination incidents) and hospitals
or other locations where contaminated patients are being examined, decontaminated or
treated.
 established boundaries should be at least waist high with clearly defined paths via stepoff pads (e.g., rope, tape, or other device that can be controlled);
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 if possible locate a table with a barrier line separating clean and possibly contaminated
surfaces at exit point for tools and equipment;
 the markings on the floor at the designated exit points delineating the inner contaminated,
outer contaminated, and secured areas should be low to permit crossing without tripping
or losing balance. (To control contamination, persons should not cross boundaries
anywhere except at designated points, the gates at the step-off pads.);
 plastic sheeting (preferably textured to minimize slipping) should be used to cover the
ground in the exit area;
 “sticky mats” may be used as step-off pads to minimize transporting radioactive
contamination from one area to the next;
 “hot” waste containers should be clearly marked “radioactive waste” and should be lined
with plastic bags.
Figure 5.4. Schematic drawing of radiologically-controlled areas and exit points at the scene of
an incident.
5.3.3. General Guidelines for Operation of a Controlled Contamination Area
Operation of a Controlled Contamination Area should count next features:
 seriously injured patients and necessary medical personnel should use the contamination
control corridor for evacuations to ambulances;
 the inner and outer contaminated, and secured areas of the exit point should be used in
the following manner:
o the inner contaminated area and objects within are assumed to be
contaminated at all times;
o persons wishing to exit the inner contaminated area should do so only at an
exit location such as that shown in Figure 5.1 unless their medical condition
dictates otherwise;
o the outer contaminated area is established for the removal of contamination
control PPE, performing whole-body surveys, and necessary
decontamination. This area should be surveyed and decontaminated
frequently, if possible;
o exit to the “clean” secured area should be restricted to those who are
confirmed to be uncontaminated via whole-body survey and (if necessary)
decontamination;
o step-off pads (preferably consisting of “sticky mats” when available) should
be used when stepping into the next area through the control points;
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o step-off pads should be surveyed periodically for contamination and should
be replaced, decontaminated or renewed if found to be contaminated;
o contaminated clothing, tools, and other objects should be placed in
radioactive-waste containers, in individual bags if possible.
5.3.4. Factors influencing decontamination efficiency
The condition of the skin. Any conditions that contribute to an increase in the strength of
the bond of radionuclides with the surface of the skin cause deterioration of skin deactivation. Dry
skin of the hands, covered with cracks and burrs, is cleaned of radioactive substances worse than
smooth and elastic skin. Areas of the skin devoid of hair are deactivated more easily than areas
covered with hair. The skin, previously skimmed and then contaminated with radioactive
substances, is decontaminated worse than the skin, covered by the time of radioactive application
with a water-fat film. Therefore, in the practice of working with radioactive materials, hygienic
skin care should be given special attention.
In case of damage to the integrity of the skin and violation of their properties (wounds,
thermal and chemical burns, etc.), the rate of penetration of radioactive substances into
subcutaneous tissues and organs increases many times, and decontamination of damaged skin
becomes extremely ineffective.
The temperature of the decontamination solution. It is usually suggested to use
solutions with a temperature of no more than 30°C. It is believed that the use of hot or cold water
during the cleaning process worsens the decontamination of the skin. Obviously, the treatment of
hands with warm water is preferable for reasons of comfort.
Duration of cleaning. The results of studies devoted to the study of the kinetics of the
removal of radioactive substances with highly effective decontaminating agents allow us to
conclude that when decontaminating the skin, it is impractical to continue the process for more
than 9-12 minutes, because longer treatment of contaminated skin areas, as a rule, does not allow
achieving the desired result.
The nature of radioactive contamination. Under the influence of a decontaminating
agent, dry contact contamination is cleaned more easily than dried drip contamination. It has also
been proven that radioactive substances that get on the skin as part of organic liquids are removed
worse than radionuclides in aqueous solutions.
The effect of decontaminating agents on the penetration of radionuclides. Any
decontaminating agent for obtaining permission for practical use should be carefully studied from
the standpoint of harmlessness in conditions of repeated use. The intake of radioactive substances
into the body under the influence of decontaminating solutions occurs in two stages: during
purification and during the post-decontamination period.
Some deactivating agents, effective in terms of reducing the level of radioactive
contamination of the skin, do not lead to a decrease and even increase the content of uranium
fission products in the body, and, consequently, the process of skin deactivation leads to an
increase in the dose of internal radiation.
5.4. Impact of Responder Management Strategies on Public Experiences and
Behaviour During Decontamination
5.4.1. Getting People to Agree to Undergo Decontamination
Getting people to agree to undergo decontamination will be crucial to the success of the
decontamination process. For decontamination to be successful, people will need to agree to
undertake any actions recommended by emergency responders.
These actions may include disrobing, undergoing improvised and/or interim
decontamination, and undergoing a decontamination shower in a specialist mass decontamination
unit. As mentioned above, decontamination may be frightening and embarrassing for members of
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the public, and this may make them reluctant to agree to undergo decontamination. A review of
small-scale decontamination incidents showed that refusal to undergo decontamination was
common. This was especially the case during incidents in which people felt that they had not
received sufficient information from emergency responders about the decontamination process,
and when they felt that their needs for privacy and modesty had not been respected. Any reluctance
of people to undergo decontamination will delay decontamination, and could potentially cost lives.
It is therefore essential that people agree to undergo decontamination, and that they do so in a
quick and efficient way.
Emergency responders can encourage people to agree to undergo decontamination by
doing two key things. First, emergency responders should explain to members of the public why
it is necessary for them to undergo decontamination. If people don’t understand why
decontamination is important they are unlikely to agree to do it. Explanations should be healthfocused where possible, should explain how undergoing decontamination will reduce the risk of
further harm from the contaminant and will also potentially prevent secondary contamination of
other people and places. Second, by showing respect for public needs for privacy. If people don’t
feel that their needs for privacy and modesty have been met, they are unlikely to agree to undergo
decontamination. While it may not always be possible to provide people with the level of privacy
they would like, it is important to communicate why this is the case, and therefore demonstrate an
understanding of and respect for public needs.
Doing these two things will demonstrate that responders are managing the incident in a
legitimate way and will promote trust in emergency responders and the information that they
provide. A key finding from our research into public behaviour during mass decontamination is
that a perception that responders are managing an incident in a legitimate way is crucial for getting
people to agree to undergo decontamination. When people feel that they have received effective
communication, and that their needs for privacy have been met, this results in increased perceived
legitimacy of emergency responders and the actions that they are taking. This is crucial, because
this perception of responder legitimacy facilitates the formation of shared identity between
members of the public and emergency responders which, as noted above, enhances cooperation
with other group members and encourages people to act in accordance with group norms.
Shared identity between members of the public and emergency responders therefore
encourages people to agree to undergo decontamination.
5.4.2. Helping People to Undergo Decontamination Quickly and Efficiently
Getting people to agree to undergo decontamination is a crucial first step in ensuring that
decontamination is successful. The next step is to make sure that people know what they need to
do, to help them to undergo decontamination quickly and efficiently. The key to quick and efficient
decontamination is to provide people with sufficient practical information about the actions that
they need to take. Findings from decontamination field exercises show that people consistently
report that they have not received practical information about what to do during the
decontamination process, and consequently, that they are confused and don’t know what actions
to take.
To understand more about the effect of different levels of information on public behaviour
during mass decontamination, we carried out a mass decontamination field experiment. During
this experiment, three different groups of participants were provided with different levels of
information before they underwent decontamination. Information included explanations about the
importance of decontamination, updates about actions responders were taking, and practical
information about the actions that participants needed to take during the decontamination process.
Participants were timed going through decontamination to enable a comparison of
decontamination efficiency between groups. The optimum time for participants to complete the
entire decontamination process was 9 minutes and 30 seconds. Findings showed that those who
were provided with the most detailed information went through the decontamination process more
quickly and efficiently than those who were provided with less detailed information, and in closest
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to the optimum time. In fact, of those who received the less detailed information, the slowest
participants took 19 minutes and 48 seconds to undergo the full decontamination process; this is
almost twice as long as the process should have taken.
This therefore illustrates how important it is for emergency responders to provide people
with detailed information about the actions people need to take during decontamination, and not
to assume that people will know what actions they need to take. It has sometimes been suggested
by emergency responders and policy makers that during decontamination there will not be time to
provide people with information, and that doing so will delay the decontamination process. The
findings presented here show that the opposite is true: the more information that people can be
provided with about what to do during decontamination, the more quick and efficient the process
is likely to be.
5.4.3. Encouraging People to Cooperate with Each Other During Decontamination
As well as being willing and able to undergo decontamination quickly and efficiently, those
involved will also need to cooperate with each other to make sure that the decontamination process
runs smoothly. Cooperating with each other in the context of decontamination involves two
different aspects:
1. Behaving in an orderly and cooperative way during decontamination (e.g. forming an
orderly queue to go through the decontamination process).
2. Actively helping others (e.g. helping to assist someone who has difficulty walking to go
through the decontamination process). This type of active helping has also been shown to be
common during mass emergencies and disasters, particularly where people experience a sense of
shared social identity with each other. Given the low number of responders to members of the
public during incidents requiring decontamination, the more that members of the public are willing
to cooperate with and assist each other during decontamination, the more smoothly the
decontamination process is likely to run. It is therefore important to understand what makes people
more or less likely to behave helpfully and cooperatively during decontamination, so that such
behaviour can be encouraged. The social identity approach suggests that people are more likely to
cooperate with each other if they identify with each other. In mass emergencies, people often
experience a sense of shared fate (in relation to the emergency) that leads them to identify with
others ‘in the same boat’.
When there is a shared identity amongst a group of people, this results in:
1. The internalisation of shared goals and motivation to contribute to the achievement of
such goals (in this case, the goal of undergoing decontamination).
2. A sense of collective efficacy, which is a belief that those involved in the incident can
work together to achieve shared goals, and to overcome any challenges that they face.
3. Motivation to help and cooperate with other group members.
A sense of shared identity will therefore be crucial for encouraging those affected to
cooperate with each other when undergoing decontamination. As described above, those involved
in a mass emergency are likely to experience a sense of shared identity, as a result of the sense of
shared fate that they all face. In the case of incidents involving mass decontamination, it is
important that people also identify with the emergency responders managing the incident. If
members of the public experience shared identity with each other, and not with emergency
responders, they may work together to challenge responder authority, rather than to go through
decontamination.
To ensure that identification is also shared between members of the public and emergency
responders, it is again crucial that emergency responders communicate effectively with members
of the public. Effective communication results in perceptions that responders are managing the
incident in a legitimate way. Perceptions of responder legitimacy have been shown to be key in
promoting shared identity between members of the public and emergency responders during mass
decontamination. Effective communication therefore encourages people to cooperate with each
other in two ways:
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1. It promotes willingness to cooperate with each other, by establishing trust, which in turn
enhances identification with emergency responders and ensures that undergoing decontamination
is accepted as a shared goal.
2. It promotes ability to cooperate with each other – by providing people with the
information that they need in order to know what to do during decontamination, and therefore to
be able to work together. Ensuring that people know what to do during decontamination promotes
a sense of collective agency, enabling people to work together to achieve shared goals (i.e.
decontamination).
5.4.4. Making People Feel Less Anxious
CBRN incidents have the potential to be very frightening for those involved, because they
are unfamiliar and ambiguous. The decontamination process is also likely to be unfamiliar and
frightening for those involved. Decontamination involves the need to remove clothes and undergo
a shower in front of others. It is therefore likely to be embarrassing, which may result in high levels
of public anxiety.
It is important that emergency responders understand that while panic will be rare, and
people are likely to behave rationally, they are still likely to be anxious. While a certain level of
anxiety is to be expected during incidents involving CBRN agents, it is important that this concern
is in proportion to the potential effects of any contaminant, rather than in relation to the
decontamination process itself. Understanding what factors may increase public anxiety about the
decontamination process will help emergency responders to manage this when carrying out
decontamination.
Our review of findings from small-scale incidents involving decontamination revealed the
potential for high levels of anxiety amongst members of the public about the decontamination
process. This was especially the case during incidents in which those affected felt they had not
received adequate information about the decontamination process, and when they felt that their
concerns about dignity and modesty had not been addressed.
To reduce public anxiety about the decontamination process, it is therefore important that
emergency responders communicate with those affected about why it is important for them to
undergo decontamination, and how decontamination will help to protect them (and others) from
the effects of any contaminant. It is also important that those affected feel that their needs for
privacy and modesty are being considered during the decontamination process. Failure to respect
public needs for privacy has been shown to be a key factor in increasing public anxiety, and
reducing public compliance, during decontamination.
5.4.5. Understanding the Needs of Vulnerable Groups
There are a large number of different factors that may make someone vulnerable during
decontamination, and there is often considerable overlap between the needs of different vulnerable
groups. Because of this, it is helpful to take a ‘functional needs’ approach. This type of approach
involves considering the greater needs that some people may have during decontamination. There
are four main functional needs that should be considered when planning for mass decontamination:
1)
impaired ability to physically undergo decontamination (e.g. anyone who may struggle to
undergo decontamination unassisted);
2)
impaired ability to communicate during the decontamination process (e.g. difficulty in
seeing, hearing, or understanding instructions);
3)
different social or cultural needs (e.g. cultural or religious norms);
4)
pre-existing health factors or medical conditions (e.g. any factors that may make someone
more susceptible to the effects of contamination or may make it more difficult for them to
successfully undergo the decontamination process).
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5.4.6. Recommendations for Optimising Management of Mass Decontamination
1. Responders should communicate openly and honestly with members of the public, and
should provide regular updates about any actions that they are taking. This will help to establish
trust and a perception that responders are managing the incident in a legitimate way, which will
promote compliance with responder instructions.
2. Emergency responders should communicate in a health-focused way about the
importance of decontamination. Specifically, responders should communicate:
1)
why decontamination is necessary, in terms of removing any potential contaminant from
the skin and preventing any further risks to health;
2)
how decontamination will protect someone, and their loved ones. Failure to remove
contaminant from someone’s skin could result in secondary contamination of other people and
places, including potentially a person’s home and family;
3)
what the process will involve. It is important that members of the public understand exactly
what the decontamination process will involve before they undergo it, since this is likely to
reduce public anxiety, and increase public compliance.
3. Emergency responders should provide members of the public with sufficient practical
information during the decontamination process. Provision of sufficient practical information
during the decontamination process improves the speed and efficiency of decontamination,
reduces confusion, and could therefore save lives during a real incident involving mass
decontamination.
4. Emergency responders should respect public needs for privacy and modesty. Failure to
respect public needs for privacy can reduce public compliance, and therefore result in delays to
decontamination.
5. Emergency responders should treat everyone as an expert in his or her own needs during
decontamination. Treating each person as an individual will demonstrate respect for their needs,
which should result in increased perceptions of legitimacy, and increased compliance. Training
and exercising should be carried out with those with different functional needs, to ensure that plans
are in place should a real incident occur.
If an incident involving mass decontamination is managed effectively (in line with the
recommendations presented), this will increase the perceived legitimacy of responders and the
actions they are taking, and will therefore promote compliance with responder instructions. The
five recommendations presented here could therefore improve behavioural and psychological
outcomes during mass decontamination, which could result in lives being saved during a real
incident.
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CONCLUSION
The use of personal protective equipment is an important protective measure used in the
case of a radiological emergency. This measure makes it possible to significantly reduce the
collective effective dose for the public, primarily in the event of a large release of radioactive
substances into the atmosphere during an accident. On the other hand, to reduce the radiation doses
of emergency workers, an adequate choice of a set of personal protective equipment to prevent
internal exposure and the use of methods to reduce the doses of external exposure is required.
Modern industry produces a large number of personal protective equipment. At the stage
of emergency preparedness, it is necessary to justify the volume of stocks of protective equipment
and their nomenclature on the basis of a hazard assessment, this can significantly increase the
effectiveness of this protective measure.
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