Basics of Radiation
Terry Romanko
Technical Director
TestAmerica St. Louis
Proprietary and Confidential
Aug 5, 2015
What is Radioactive Material?
• Any material containing unstable
atoms that emit radiation.
• Radioactivity is the process of
unstable atoms becoming stable.
This is done by emitting radiation,
or giving off energy. This process
is referred to as radioactive
decay.
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“Is it Radioactive?”
• Many consumer products
contain radioactivity (In fact the
question is not “Is it
radioactive?”, but “How much
does it contain?”
~ Fiesta Ware (and other glazed
items)
~ Bathroom tile
~ Granite countertops
~ Cigarettes/tobacco
~ Brazil nuts
~ Potassium salt (table and
water softener
~ Incandescent gas lantern
mantles
~ Many more:
(http://www.orau.org/ptp/collection/consumer%20p
roducts/consumer.htm)
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Common terms
• Radioactive Half-life: the time it takes for
one half of the unstable atoms present to
decay. Example ~ Ni-65 = 2.52 hours
~ K-40 = 1.28x109 years
• Radioactive contamination: radioactive
material that is uncontained and in an
unwanted place.
~ It is important to note that exposure to radiation does
not necessarily result in contamination of the worker.
Radiation is energy; contamination is a material. When
properly contained, radiation may still be an external
dose hazard but not a contamination hazard.
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Common terms (cont.)
• Ionizing radiation: is energy emitted from
radioactive atoms, and some devices, that cause
ionization.
• Non-ionizing radiation: Electromagnetic radiation
that doesn’t have enough energy to ionize an
atom.
~ Examples are radar waves, microwaves, and
even visible light.
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Common terms (cont.)
•
•
•
•
•
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Source Material: The NRC’s definition of source material means Uranium
(U) or Thorium (Th), or any combination thereof, in any physical or
chemical form or ores which contain by weight 1/20th of 1% (0.05%) or
more of U, Th, or any combination thereof.
Unimportant Quantities of Source Material: Any person is exempt from
licensing regulations and requirements to the extent that such person
receives, possesses, uses, transfers, or delivers source material in any
chemical mixture in which the source material is by weight less than 1/20th
of 1%, and that said person does not refine or process such material.
Byproduct Material: The tailings or wastes produced by the extraction or
concentration of U or Th from any ore processed primarily for its source
material content.
NORM: or Naturally Occurring Radioactive Materials, consist of materials
that are found in the environment, such as uranium, thorium, and
potassium, and any of their decay products, such as radium and radon.
These natural radioactive elements are present in very low concentrations
in earth’s crust and are brought to the surface through activities such as
mining and oil & gas exploration.
TENORM: or Technologically Enhanced Naturally Occurring Materials,
means NORM whose radionuclide concentrations are increased by or as
a result of human practices. A good example of TENORM is coal ash
produced from coal firing in power plants.
The Four Basic Types of
Ionizing Radiation
•
•
•
•
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Alpha radiation
Beta radiation
Gamma radiation
Neutron radiation
Alpha radiation
• Range~ Very short, about 1 to 2 inches in air
~ Deposits large amount of energy in a short
distance of travel
~ This large energy deposit is what limits the
penetrating ability to a very short distance
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Alpha radiation (cont.)
• Shielding~ Most alpha particles are stopped by:
◦ only a few centimeters of air,
◦ a sheet of paper,
◦ the dead layer of skin on a human body.
• Biological Hazards~ No external hazard.
~ Internally, the source is in close contact with body
tissue and can deposit large amounts of energy to
a small body of living tissue.
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Alpha radiation (cont.)
• Common sources~
~
~
~
~
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Uranium
Thorium
Plutonium
Radium
Radon
Beta radiation
• Range~ Short distance, depending on the energy of
the particle, about 1 inch to 20 feet
~ In the case of tritium (H3), the range is only
one inch
~ In the case of phosphorous-32 (P-32) or
strontium-90 (Sr-90), the range is 20 feet
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Beta radiation (cont.)
•
Shielding~ Beta particles are typically shielded by plastic or glass
◦ The sample containers generally shield the outside
environment from a beta emitter
◦ Your safety glasses will shield your eyes (note - very
important!)
Important note for licensed facilities using hand held
friskers! – When frisking samples for radioactivity, you may
receive a false negative with closed containers!
•
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Biological Hazards~ Internal hazard due to short range and lower penetrating
power.
~ Externally, a beta emitter may be hazardous to the skins and
eyes.
Beta radiation (cont.)
• Common sources~
~
~
~
~
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Potassium 40 (K-40)
Strontium 90 (Sr-90)
Cesium 137 (Cs-137)
Cobalt 60 (Co-60)
Tritium (H3)
Gamma radiation
• Range~ Very high range, easily can go several hundred
feet or more.
~ Very high penetrating power since it has no mass
and no charge.
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Gamma radiation (cont.)
• Shielding~ Very dense material
◦ Concrete
◦ Water
◦ Lead
• Biological hazards~ Can result in whole body exposure
~ Hazard may be internal or external depending on
location of source.
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What about protection from
radiation?
•
Source reduction~ Put the larger volume of samples away, remove and only work with
aliquot needed.
~ Decontaminate the area around you.
•
Practice the three principles of radiation protection:
~ Time – Time spent away from radioactive emitters,
~ Distance – Distance yourself from the emitters,
~ Shielding – Shield yourself from high emitters.
•
Practice ALARA!
~ As Low As Reasonably Achievable.
~ Always reduce your exposure as much as possible, simply reducing
to a licensed limit is never enough. This means that if the NRC
states that you can safely handle 5 REM in a year, but you have the
means to reduce your exposure even further , you must reduce it.
•
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Remember, these same safe practices help to protect against known and
unknown chemical hazards as well.
Permissible Exposure Limits
• Nuclear Regulatory Commission = 5 REM
(50mSv) per year for a radiation worker,100
mrem (1 mSv) per year for a member of the
general public.
• Test America = action level is 500 mrem (5 mSv)
per year, 1/10th of the NRC limit (same as NRC
“Pregnant Worker”).
• What is “REM”?
~ The acronym for Roentgen Equivalent Man is a
standard unit that measures the effects of ionizing
radiation on humans.
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Risk in Perspective (cont.)
• Estimated Average Whole Body Dose from Natural & Manmade Sources:
• Naturally Occurring~ Cosmic Radiation = 39 mrem/yr.
~ Internal, principally K-40 = 26 mrem/yr.
~ External Terrestrial = 235 mrem/yr.
– Earth’s crust~35mrem, Radon gas~200mrem
• Man-made~ Fallout = 1mrem/yr.
~ Medical uses (x-rays, internal sources) = 90mrem/yr., avg.
chest x-ray~10mrem ea.
~ Tobacco products = 1300 mrem/yr.
~ Building materials = 7mrem/yr.
~ Domestic water supply = 5mrem/yr.
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Risk in Perspective (cont.)
•
•
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Reduction of Life Span from Various Causes=
~ Smoking (one pack/day) ~
9 yrs.
~ Living in city vs. country ~
5 yrs.
~ Being single vs. married ~
5 yrs.
~ Desk job vs. field job ~
5 yrs.
~ Being male vs. female ~
3 yrs.
~ Obesity ~
2 yrs.
~ Alcohol consumption ~
1 yr.
Radiation=
~ Cosmic ~
20 – 30 days
~ Terrestrial ~
50 – 100 days
~ Medical ~
30 days
~ Luminous watch ~
<26 days
~ World fallout ~
1 day
~ Occupational dosage of 1rem/yr. ~ 51 days
◦ Note – this is twice TestAmerica’s internal limit!
Basic Analytical Instrumentation
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•
•
•
•
•
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Gamma Spectrometry
Gas Flow Proportional Counting
Liquid Scintillation Counting
Alpha Spectrometry
Lucas Cell (Scintillation Detector)
ICP-MS
Gamma Spectrometry
• Detector (High Purity Germanium)
• aka HPGe
• Semiconductor Detector (cryo temp)
• High Resolution (Low FWHM)
• Electronics
• Collect and Process Signal from
Detector
• MCA is key component
• Software
• Store and analyze the spectrum
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Gas Flow Proportional Counting
• Detector
• Gas-filled (P-10; 90% Argon, 10% methane)
chamber with thin window (e.g. mylar film,
80μg/cm2)
• Electronics
• Collect and Process Signal from Detector
• Pulse shape discrimination key function
• Software
• Store and analyze the
spectrum
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Liquid Scintillation Counting
• Detector
• Photomultiplier tube (PMT) collects light
• Electronics
• Collect and Process Signal from
Detector
• Utilizes MCA for spectral output
• Software
• Store and analyze the
spectrum
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Alpha Spectrometry
• Detector
• Ion-implanted-Si Charged particle detector
• Low Resolution (High FWHM) compared to γ
• Electronics
• Collect and Process Signal from Detector
• MCA is key component
• Software
• Store and analyze the spectrum
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Lucas Cell Counting
• Used specifically for Ra-226 by radon
emanation (Richland)
• Silver-activated zinc sulfate coating
scintillates when struck by alpha particle
• Photomultiplier tube measures scintillation
• Each event recorded on counter/scalar
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ICP-MS
• Inductively Coupled Plasma – Mass
Spectrometry
• Direct Mass Measurement
• Can convert results to activity
• Useful for long-lived isotopes
• Uranium
• Tc-99
• Th-232
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What is NORM?
• Naturally Occurring Radioactive Material
• Terrestrial – primordial radionuclides present
in rocks and minerals
• Cosmogenic - interaction of cosmic nucleons
with atmosphere (varies with altitude)
• Dose
~ 31 mR/yr in St. Louis
~ 55 mR/yr in Denver
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NORM
(Naturally Occurring Radioactive Materials)
• Terrestrial
~ K-40
~ Nuclides in Primordial Series
◦ Uranium-238 (Uranium Series)
◦ Thorium-232 (Thorium Series)
◦ Uranium-235 (Actinium Series)
• Cosmogenic (H-3, C-14, Be-7)
• Principal Nuclides of concern (typically)
~ Ra-226, K-40, Th-232
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TENORM
(Technology Enhanced NORM)
• Produced when NORM are exposed to
the environment or concentrated;
extraction/treatment/purification (EPA)
~ Minerals Mining & Production/Processing
(e.g. phosphogypsum)
~ Coal Ash Generation
~ Oil & Gas Production
~ Sewage or Drinking Water Treatment
~ Consumer Items
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Key Methods/Isotopes
(SDWA-related)
•
•
•
•
•
•
Gross Alpha/Beta (3/4 pCi/L)
Ra-226/Ra-228 (1 pCi/L)/(1 pCi/g)
Sr-90 (1 pCi/L)/(1 pCi/g)
H-3 (300 pCi/L)/(2 pCi/g)
Uranium (Total/Iso)
K-40 (Beta minus K-40)
“If it is good enough to drink, it is good enough to pour down the drain.”
This idea is not appropriate for all situations, and is overused.
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Beta/Photon Emitters
“Most systems will never need to monitor for beta
particle and photon radioactivity”*
*Radionuclides in Drinking Water: A Small Entity
Compliance Guide, EPA (2002)
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Key Methods
(Other)
• Alpha emitters
• Iso-U, Iso-Th, Am-241, Iso-Pu, Np-237, Po-210
• 1 pCi/L / 1 pCi/g to lower than 0.1 pCi/L / 0.1 pCi/g
• Beta emitters
• C-14, Tc-99, Pb-210, Ni-63, Pu-241, Cl-36
• Gamma emitters
• Co-60, Cs-137, Fe-55, I-129 (I-125)
• 20 pCi/L / 0.2 pCi/g based upon Cs-137
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Trash/Treasure
• One man’s trash is another man’s treasure:
Fly ash – concrete, cement, concrete block
Bottom ash – snow/ice control
Boiler slag – blasting grit, roof granules
Sludges – wallboard, roadbases
Phosphogypsum – used in agriculture as a source
of calcium and sulfur, for pH adjustment, and for
erosion control.
~ Phosphate slag – used in roadbase (crushed) and
as aggregate for asphalt; Portland cement and
concrete; railroad ballast and construction
~
~
~
~
~
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Regulations
• Regulations:
~ TENORM not directly regulated by Atomic
Energy Act (AEA)
◦
◦
except mill tailings (Thorium/Uranium)
source material (high grade ores)
~ Clean Air Act (NESHAPS): regulates release
of TENORM to air from phosphate industry
and uranium mining
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Phosphate Industry Regs
• NESHAPS standard for airborne Po-210 also
effectively controls Pb-210.
• Slag contains ~15x background gamma rays.
Radon is mostly encapsulated by the slag. A
NESHAPS standard does exist for radon
emissions from phosphogypsum stacks.
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Uranium Mining Regs
• Open Pit mines:
~ Not many active. Large area of overburden
topsoil and open pit area, exposing Radium
(Radon). EPA study – low health risk. Already
regulated by state and federal mining laws. No
NESHAPS put into place.
• Underground mines:
~ 1989 NESHAPS regulates Radon emissions from
underground mines (vents – potentially high
emissions).
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Other Regulations
• Clean Water Act (CWA) – through NPDES, EPA
has authority to regulate discharges into surface
waters that don’t fall under AEA Permits issued
will include criteria for TENORM for uranium,
thorium, etc mines/mills.
• Safe Drinking Water Act (SDWA) – National
Primary Drinking Water Regulations includes
limits for radionuclides. Most recently revised in
2000.
• CERCLA (Superfund) – establishes preliminary
remediation goals (PRGs) for soils contaminated
with uranium, thorium, radium, et al.
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Questions/Contact Info
Questions?
• Terry Romanko – Radiochemistry Technical Director
• St. Louis Laboratory
• terry.romanko@testamericainc.com
• 314-298-8566
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