Atomic Structure & Radiation
Community Environmental Monitoring
Program
CEMP
Gary M. Sandquist, PhD, CHP, PE
2011 Training Session
Slide 1
CEMP Training Outline
 Basic
Atomic Structure
 Introduction
Slide 2
to Radioactivity
 Radiation
Sources
 Biological
Effects
 Radiation
Risks
 Radiation
Limits
CEMP Training Outline
Slide 3

Personnel Monitoring

ALARA Program

Radiation Posting & Control

Radiation Work Permits

Radiological Emergencies
CEMP Training Outline
Slide 4

Radioactive Waste
Minimization

Radiation Contamination
Control

Practical Exercise
Isotopes

ISOTOPES:
Atoms with same number protons
(same atomic number) but different
number of neutrons in nucleus
(Mass number different but not atomic #)
-
238U
versus 235U – atomic # = 92
Chemistry of isotopes identical!
238U
Slide 5
same chemistry as 235U
Stable & Unstable Atoms

Only certain combinations of neutrons &
protons are stable nuclei.

Too many or too few neutrons for same
number of protons then nucleus has
excess energy & is unstable.
- Unstable atoms become more stable by
reducing excess energy through
release of radiation.
- Unstable nuclei known as radioactive
atoms.
Slide 6
Radiation Symbol - Radioactivity
Slide 7
Alpha Particles ( He4 )

PHYSICAL
CHARACTERISTICS
-

SHIELDING
-
Large mass
2 protons, 2 neutrons
no electrons
Stopped by
outer layer of skin,
few centimeters of air
or one sheet of paper.
Positive charge +2
-
-
Slide 8
Highly charged particle
emitted from nucleus of
atom.
Positive charge +2 causes
alpha particle (+) to strip
electrons (-) from nearby
atoms as it passes through
material, thus ionizing these
atoms.

BIOLOGICAL HAZARD
-
-
No external
radiation hazard.
Internally deposits large
amount of energy in
small volume of body
Beta Particles ( e-1 or e+1 )

Slide 9
PHYSICAL
CHARACTERISTICS
-
Small mass emitted from
nucleus of atom with
electrical charge of -1.
-
Cause ionization by
displacing electrons from
their orbits.
-
Same as electron.
-
Ionization caused by
repulsive force between
beta particle (-) &
electron (-);

RANGE
-

SHIELDING
-

Limited penetrating ability
(< 10 feet in air) because of
negative charge.
Most beta particles
shielded by plastic, glass,
metal foil, safety glasses
BIOLOGICAL HAZARD
-
An internal hazard due to
short range.
Hazardous to skin & eyes.
Gamma/X Rays ( g or x )

Slide 10
PHYSICAL
CHARACTERISTICS
-
Electromagnetic wave or
photon with no electrical
charge.
-
Gamma rays similar to x
rays, but from nucleus.
-
Gamma/x ray radiation
ionizes by direct reaction
with orbital electrons.
-
Energy of gamma/x ray
radiation transmitted
directly to target.

RANGE
-

SHIELDING
-

Gamma/x rays have no
charge or mass
Very penetrating
Range in air - few hundred
feet.
Best shielded by dense
materials
(concrete, lead or steel).
BIOLOGICAL HAZARD
-
Produces radiation
exposure to whole body.
Activity Units
Disintegrations Per Unit Time

Traditional (US) unit is Curie
- 1 Ci = 3.7 x 1010 dps (dis/sec)
- 1 Ci = 2.22 x 1012 dpm (dis/min)
- 1 Ci = 1 x 1012 pCi
- 1 Ci = 37 GBq

International unit is Becquerel
- 1 Bq = 1 dps = 2.70 x 10-11 Ci
Slide 11
- 1 GBq = 0.0270 Ci
Radiation Dose Units

rad = 100 ergs/gram of absorber -(Gray)

mrad = 1/1000th of rad

rem = rad x Quality Factor -(Sievert)

Quality Factors
- alpha = 20
- beta = 1
- gamma = 1
Slide 12
- neutron ~ 10(avg) varies 2 to 20
Radioactive Half-life

Time for 1/2 of radioactive atoms to decay
to something else

Example: 1 Ci X-365 has half life of 1 yr:
How much after 2 yrs, 10 yrs, 20 yrs?
X(1 yr) = X(0) x (1/2)n with n=2
So activity X(2 yr) = X(0) x (1/2)2 =1/4 X(0)
Slide 13
X(10 yr)
= X(0) x (1/2)10
~ 1/1000 X(0)
X(20 yr)
= X(0) x (1/2)20
~ 1/million X(0)
Natural Sources (2006 NCRP)
Slide 14

Cosmic radiation ~ 5%

Terrestrial radiation ~ 3%

Internal radiation ~ 5%

Radon / Thoron ~ 37 %
Man-Made Sources
Slide 15

Medical radiation ~ 48%

Nuclear weapon tests < 0.1%

Consumer products ~ 2%

All energy production & research
< 0.1% or < 0.5 mrem

Industrial uses < 0.1%

Fukushima < 1 foot elevation
Medical Radiation
Slide 16

X-rays - medical (CT’s, etc) & dental

Radioactive material for diagnosis
131I, 99Tc, 32P, 3H, 14C

Radioactive material for therapy
60Co, 137Cs, 226Ra, neutrons

Annual dose ~298 mrem ~48% total
Average Total Annual Dose
620 mrem
Total average US
rad exposure
(NCRP report 160 - 2006)
Prior US level - 360mrem
Slide 17
Radiation Damage
Slide 18

Direct Effects:
- Ionization can break chemical bonds

Indirect Effects:
- Ionized water results in radicals
H+ or HO- or H2O2
- These radicals cause chemical damage

Location of damage important:
Cell Nucleus or Cytoplasm
Possible Effects on Cells

Slide 19
No damage evident

Damage repaired & cell normal

Damage not repaired & cell
functions abnormally

Cell dies
Cell Sensitivity
Slide 20

Cells have different rad sensitivity

Most sensitive: Cells actively
dividing (e.g., stem & blood cells)

Moderate sensitive: Less specialized
cells

Least sensitive: Specialized cells or
less actively dividing (nerve, brain,
bone, muscle cells, skin )
Dose Rate Effects

Acute: Large dose over short time
- 10-25 rem slight blood changes
- 300-500 rad hematopoetic
syndrome
- 500-1000 rad GI syndrome
- >1000 rad CNS syndrome

Slide 21
Chronic: Low dose rate over long
time e.g., Background radiation
Factors for Biological Damage

Total dose (how much)

Dose rate (how fast)

Type of radiation
(alpha, beta, gamma, neutron)

Area exposed
(total body, internal, hands, etc.)
Slide 22

Cell sensitivity

Individual person sensitivity
Risk From Exposure

No observed increase of risk at
occupational exposures

Risk factor: 4 x 10- 4 latent health
effects per rem (LNT model)

Cancer formation latency time > 10 yr

More solid tumor formation
at old age
Slide 23
Perspective of Risk
Estimated Loss of Life Expectancy during lifetime
Health Risks
20 cigarettes/day
6 years
15% overweight
2 years
Consuming alcohol 1 year
All Accidents
1 year
Motor vehicle
207 days
Home accident
74 days
Drowning
24 days
Natural hazards
7 days
Medical radiation
15 days
620 mrem/y for 47 y 31 days
(US Background dose)
1 rem/y for 47 y
50 days
Slide 24
Industrial Accidents
All industries 60 days
Agriculture
320 days
Construction 227 days
Mining
167 days
Transportation 160 days
Government
60 days
Manufacturing 40 days
Trade
27 days
Services
27 days
Nuclear Plant 27 days
DOE & USNRC
Occupational Dose Limits
Slide 25
Whole Body
5
rem per yr
Lens of Eyes
15
rem per yr
Extremities
50
rem per yr
Skin
50
rem per yr
Organ or Tissue
50
rem per yr
Unborn Child
0.5
rem pregnancy
(US Background
0.62 rem per yr)
Declared Pregnant Worker
(Embryo / Fetus)
Slide 26

Policy: Female radiation worker
encouraged to voluntarily notify
supervisor (written) if pregnant.

Employer must provide
agreeable work with limited
(~no rad) exposure @ no loss of
pay or promotional opportunity

Further occupational rad
exposure unlikely during
pregnancy.
Occupational Dose Equivalent
Limits



Slide 27
General Public
100 mrem/yr
Any Occupational Worker
(unmonitored)
100 mrem/yr
Radiation Worker (monitored)
5,000 mrem/yr = 5 rem/yr
External & Internal Radiation Dose
Reduction
Slide 28

Use shielding if possible

Minimize time in radiation field

Maximize distance to rad source

Dose ~ Source x time / (distance)2
ALARA

As Low As Reasonably Achievable
(called ALARA by regulators)
Radiation protection program manage
exposures (individual & collective to
workforce & public) as low as social,
technical, economic, practical, public
policy permit.
Slide 29
ALARA not dose limit but a process
“maintain dose levels “As Low
As Reasonably Achievable.”
ALARA Management Policy
Radiation exposure maintained
As Low As Reasonably
Achievable, considers social &
economic needs.
Radiation exposure to workers
controlled to ensure radiation
exposures well below regulatory
limits.
No occupational radiation
exposure allowed without
expected benefits (health,
economic, social, etc.).
Slide 30
Radiological Control
Responsibilities
Slide 31

Provide technical & programmatic control
over radiation & radioactive materials

Provide Health Physics (HP) personnel &
monitoring equipment

Issue Radiation Work Permits (RWPs)

Maintain dosimetry program

Maintain training program
Radiation Posting Requirements

Areas controlled for radiological
purposes designated with magenta
(or black) standard three-bladed
radiological warning symbol on
yellow background


Slide 32
Yellow & magenta ropes, tapes,
chains, or other barriers used to
denote & control boundaries.
Radiological Areas
Slide 33

Radiological Buffer Area

Radiation Area

High Radiation Area

Very High Radiation Area

Contamination Area

High Contamination Area

Fixed Contamination Area

Soil Contamination Area

Airborne Radioactivity Area
Radiation Area
Area with radiation dose rates
> 5 mrem/hr but < 100 mrem/hr
Entry requirements:
Rad Worker I or II Training
Worker signature on RWP
Required Dosimetry
Requirements in work area
Slide 34

Don’t loiter

Practice ALARA
High Radiation Area
Radiation dose rate > 100 mrem/hr & < 500 rad/hr.
Entry requirements
Radiological Worker II Training
Worker’s signature on job-specific RWP
Requirements for work in area
Personnel & supplemental dosimeters
Survey meters or dose rate indicating device
Access points secured by control devices, locks, etc.
Slide 35
Very High Radiation Area
Area where radiation dose rates
> 500 rad/hr
Entry requirements:
Radiological Worker II Training
Worker signs job-specific RWP
Requirements for work in area:
Personnel & supplemental
dosimeters
Survey meters or dose rate
indicating device
Access points secured by control
devices, locks, etc.
Slide 36
Contamination Area
Area where surface has removable
contamination > given limits
Entry Requirements:
Radiological Training II
Worker signs RWP
Requirements for work in area:
Personnel dosimeter if necessary
Minimize dust generation
Respiratory protection if necessary
Slide 37
High Contamination Area
Area where surface has removable
contamination >10 times limits.
Entry Requirements:
Radiological Training II
Worker signs RWP
Requirements for work in area:
Personnel dosimeter if necessary
Minimize dust generation
Respiratory protection if necessary
Slide 38
Soil Contamination Area
Area where surface soil
contaminated above limits
Entry Requirements:
Radiological Training II
Worker signs RWP
Requirements for work in area:
Personnel dosimeter if necessary
Minimize dust generation
Minimize earth disturbance
Respiratory protection if necessary
Slide 39
Airborne Contamination Area
Area where surface soil
contaminated above limits.
Entry Requirements:
Radiological Training II
Worker signs RWP
Requirements for work in area:
Personnel dosimeter if needed
Minimize dust generation
Minimize earth disturbance
Respiratory protection
Slide 40
Requirements for Exiting
Slide 41

Exit at step-off pad provides
“barrier” between contaminated &
clean areas to prevent spread of
contamination.
Remove protective clothing

Perform whole body survey.
If contaminated: stay in area, notify
Radiological Control personnel,
minimize cross-contamination.

After exiting & monitoring self,
wash hands before eating, drinking,
chewing, applying make-up, etc.
Radioactive Material Area
Entry requirements into Rad
Materials Area if whole body
dose rate > 5 mrem/hour or
contamination > specified
limits
Same for entry into Radiation
Area or Contamination Area
Depends on radiological
hazard present.
Slide 42
Hot Spot Identification



Slide 43
Hot spots - Source of
radiation or rad
material in area,
equipment or piping
Rad levels at such
spots typically
higher than
surrounding area
Avoid hot spots if
possible
Control of Radioactive Spills

Stop or secure spill source

Warn others in area

Isolate spill if possible

Minimize exposure &
contamination


Secure unfiltered ventilation
Requirements for exiting
- Site specific monitoring
- Monitor per posted
instructions before entry to
clean area
Slide 44

Notify Rad Control
personnel

Changing rad conditions.

Actions don’t create rad
problems for others.

Be alert for activities that
change rad conditions
Radiation Work Permits

Rad Work Permit used to control routine
or repetitive activities such as
inspections in areas with stable
radiological conditions.
Valid for up to one calendar year.

Job-Specific Radiation Work Permit
control non-routine operations in areas
with changing radiological conditions.
Valid only for duration of job.
Slide 45
Emergency Dose Limits

Protecting property if 5 rem not practical


Lifesaving or protection of small population
if dose limit not practical:


25 rem
Lifesaving or protection of large population
(volunteer basis for person aware of risk)

Slide 46
10 rem
> 25 rem
Segregation Rad Materials


Slide 47
Place rad waste only
in Rad Waste
receptacles
Don’t put non-rad
waste or reusable rad
material in Rad Waste
containers

Segregate compactable
material from noncompactable material

Minimize mixed waste
generation

Use good housekeeping
techniques
Personnel Protective Clothing

Protective Clothing used to enter
areas with rad levels above specified
limits to prevent skin contamination

Clothing depends on work area, rad
conditions, job, etc.

Full protective clothing includes
coveralls
cotton glove liners & gloves
hood
shoe covers & rubber overshoes.
Slide 48
Decontamination

Decontamination - removal
of rad materials from
locations not wanted
- Personnel decon usually
done using mild soap &
lukewarm water.
- Material decon- removal
of radioactive material
from tools, equipment,
floors & other surfaces
Slide 49
- Thank you for your participation -
Community Environmental
Monitoring Program
CEMP
END of Training
ANY QUESTIONS?
Slide 50