Part I

Radiation Safety Principles Overview George D. Mosho, CHMM, CHS-I Health Physicist

Personal Introduction
Health Physicist – Argonne National Laboratory
Operational Health Physics/Radiation Safety
Emergency Response
Decontamination & Decommissioning/Site Characterization
Hazmat Officer (Lt.) – Will County EMA
Assist. Safety Officer
Radiation Dosimetry Officer
Combat Engineer Officer – USMC
NBC Officer
Explosives/Mines/Boobytraps

Health Physics
Health physics is the development, dissemination, and application of both the scientific knowledge of, and the practical means for radiation protection .
The objective of health physics is the protection of people and the environment from unnecessary exposure to radiation.

Introduction
Radioactive material is a hazardous material .
Hazardous materials are managed safely every day. ( i.e. gasoline; chlorine)
Radioactive materials are also safely managed daily.

Radiation

Radiation
Ionizing [Health Physics]
Alpha
Beta
Gamma
X-Rays
Neutron
Non-Ionizing [Industrial Hygiene]
microwave, radio, laser, etc.

Ionizing Radiation
Ionizing radiation is radiation capable of imparting its energy to the body and causing chemical changes
Ionizing radiation is emitted by
- Radioactive material
Some devices such as x-ray machines

Alpha Radiation

Beta Radiation

Gamma-Rays

X-Rays

Types of Ionizing Radiation Alpha Particles Stopped by a sheet of paper Beta Particles Stopped by a layer of clothing or less than an inch of a substance Gamma Rays Stopped by inches to feet of concrete or less than an inch of lead Radiation Source

Misconceptions
Don’t get hung up on the fact that alpha & beta are “particles”; x-rays and gamma are energy!
Radioactive material that emits alpha, beta and/or gamma can be a…
Solid
Liquid
Gas

Radiation versus Contamination
Radiation is a type of energy; contamination is material
Exposure to radiation will not contaminate you
Radioactive contamination emits radiation

Radiation and Radioactive Material

Contamination

Irradiation

Activation/Induced Activity

Examples of Radioactive Materials Physical Radionuclide Half-Life Activity Where Found Cesium-137 30 y 1.5x10 6 Ci Food Irradiator Cobalt-60 5 y 15,000 Ci Cancer Therapy Plutonium-239 24,000 y 600 Ci Nuclear Weapon Iridium-192 74 d 100 Ci Ind. Radiography Hydrogen-3 12 y 12 Ci Exit Signs Strontium-90 29 y 0.1 Ci Ocular Therapy Iodine-131 8 d 0.015 Ci Nuclear Medicine Technetium-99m 6 h 0.025 Ci Diagnostic Imaging Americium-241 432 y 0.000005 Ci Smoke Detectors Radon-222 4 d 1 pCi/l Environment

Radiation Units Measure of Amount of radioactive material Ionization in air Absorbed energy per mass Absorbed dose weighted by type of radiation For most types of radiation 1 R  1 rad = 1 rem Quantity Activity Exposure Absorbed Dose Dose Equivalent Unit curie (Ci) roentgen (R) rad rem

Radiological Units
Radiation Exposure (rate) Measurement:
Roentgen or milliroentgen (R/h or mR/h)
rem or millirem (mrem/h)
Sievert (SI unit), 1 sievert = 100 rem

Radiological Units
Activity Measurement:
Curie or milli or microCurie
Becquerel (SI unit) or MBq
Disintegrations per minute (dpm)
Counts per minute (cpm)

Half-Life

Radioactive Decay Example A x = A 0 e -0.693 t/T½ where…. A x = Current activity (23 Oct 08) A 0 = 5 microCi (Initial activity: 23 Oct 04) t = 4 y elapsed T ½ = ~ 30 y ( 137 Cs) A x = (5 microCi) e -0.693 (4 y/30 y) A x = 4.6 microCi

Radioactive Decay
A x = A 0 e -0.693 t/T½
where…
A x = Activity of the source at t = x
A 0 = Activity of the source at t = 0
t = time elapsed from t = 0 to t = x
T ½ = Half-life of the specific radionuclide

Inverse Square Law
I 2 = I 1 (d 1 2 /d 2 2 )
where…
I 1 = Intensity † of radiation at position #1
I 2 = Intensity of radiation at position #2
d 1 = Distance position #1 is from source
d 2 = Distance position #2 is from source
† : Exposure rate (i.e. mR/h)

Inverse Square Law Example
I 2 = I 1 (d 1 2 /d 2 2 )
where…
I 1 = 120 mR/h
d 1 = 2 m from the source
d 2 = 4 m from the source
I 2 = (120 mR/h)((2 m) 2 /(4 m) 2 )
I 2 = 30 mR/h

Types of Radiation Hazards
External Exposure:
whole-body
partial-body
Contamination :
External: radioactive material on the skin
Internal: radioactive material inhaled, swallowed, absorbed through skin or wounds
External Exposure Internal Contamination External Contamination

Causes of Exposure/Contamination
Accidents
Nuclear reactor
Medical radiation therapy
Industrial irradiator
Lost/stolen medical or industrial radioactive sources
Transportation
Terrorist Event
Radiological dispersal device (dirty bomb)
Low-yield nuclear weapon

ALARA
A - As
L - Low
A - As
R - Reasonably
A - Achievable

ALARA
Basic Question:
“ Does the benefit outweigh the risk?”
If not, then back to the drawing board.
If so, then review the operation for further potential improvements (i.e. reduction in exposure)

Standard Radiation Protection Principles
▪ Time
▪ Distance
▪ Shielding

Radiation Protection Principles
Time
Distance
Source Barrier
Personal Barrier
Dispersal
Source Reduction
Effect Mitigation
Decorporation (Internal and surface irradiation only)
Optimal Technology
Limitation of Other Exposures

Natural Background Radiation
U.S. average: 100 - 400 mrem/y
[200 - 300 mrem/y due to radon]
Parameters:
mineral deposits (Brazil ~ 7 rem/y - 232 Th)
elevation above sea level (Denver ~ 600 mrem/y - cosmic rays)
other- foodstuffs, lifestyle, construction techniques for dwellings, etc.

Background Radiation

Radiation Doses and Dose Limits
Flight from Los Angeles to London 5 mrem
Annual public dose limit 100 mrem
Annual natural background 300 mrem
Annual radiation worker dose limit 5,000 mrem
“ Mild” acute radiation syndrome 200,000 mrem
LD 50/60 for humans (bone marrow dose) 350,000 mrem

Biological Effects
Potential effects on the human body from ionizing radiation:
No damage
Cells repair damage and operate normally
Cells are damaged and operate abnormally
Cells die as a result of the damage

Laws and Regulations
The Atomic Energy Act of 1954 is the basis of all laws and regulations controlling the use of radioactive materials in the US.
Several federal agencies, including the NRC , DOE , EPA , OSHA , and DOT have developed and promulgated radiation protection standards.
Organizations such as the NCRP , IAEA , ICRP and CRCPD provide recommendations for radiation exposure and the implementation of standards.

Personnel Dose Limits *
Occupational Workers:
TEDE ** 5 rem/yr
Lens of eye 15 rem/yr
Extremities 50 rem/yr
Other organs 50 rem/yr
Skin 50 rem/yr
Members of Public:
TEDE 0.1 rem/yr
* 10 CFR 20 and 10 CFR 835
** Total Effective Dose Equivalent (TEDE) means the sum of the deep-dose equivalent (for external exposures) and the committed effective dose equivalent (for internal exposures).

Personnel Dose Limits (cont'd)
Minors:
10% of occupational (10 CFR 20)
0.1 rem/yr TEDE (10 CFR 835)
Embryo/Fetus:
0.5 rem TEDE for the entire gestation period

Detecting and Measuring Radiation
Detectors or Survey Instruments:
contamination
exposure rate
Personal Dosimeters – Film, TLD, Self-reading
measure doses to responders

Questions? Thank you. If you have any questions at a later date, please contact me at Argonne National Lab George D. Mosho, CHMM 630-252-6172 [email_address]

Part I

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Part I

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