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Radiation Safety Principles

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Title: Radiation Safety Principles


1
Radiation Safety Principles
  • Overview

George D. Mosho, CHMM, CHS-I Health Physicist
2
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

3
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.

4
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.

5
Radiation
6
Radiation
  • Ionizing Health Physics
  • Alpha
  • Beta
  • Gamma
  • X-Rays
  • Neutron
  • Non-Ionizing Industrial Hygiene
  • microwave, radio, laser, etc.

7
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

8
Alpha Radiation
9
Beta Radiation
10
Gamma-Rays
11
X-Rays
12
Types of Ionizing Radiation
Alpha Particles Stopped by a sheet of paper
Radiation Source
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
13
Misconceptions
  • Dont 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

14
Radiation versus Contamination
  • Radiation is a type of energy contamination is
    material
  • Exposure to radiation will not contaminate you
  • Radioactive contamination emits radiation

15
Radiation and Radioactive Material
16
Contamination
17
Irradiation
18
Activation/Induced Activity
19
Examples of Radioactive Materials
Physical Radionuclide Half-Life
Activity Where
Found Cesium-137 30 y
1.5x106 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
20
Radiation Units
Measure of Amount of radioactive material
Ionization in air Absorbed energy per
mass Absorbed dose weighted by type of
radiation
Quantity Activity Exposure Absorbed
Dose Dose Equivalent
Unit curie (Ci) roentgen (R) rad rem
For most types of radiation 1 R ? 1 rad 1 rem
21
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

22
Radiological Units
  • Activity Measurement
  • Curie or milli or microCurie
  • Becquerel (SI unit) or MBq
  • Disintegrations per minute (dpm)
  • Counts per minute (cpm)

23
Half-Life
24
Radioactive Decay Example
Ax A0e-0.693 t/T½ where. Ax Current
activity (23 Oct 08) A0 5 microCi
(Initial activity 23 Oct 04) t 4 y
elapsed T½ 30 y (137Cs) Ax (5 microCi)
e-0.693 (4 y/30 y) Ax 4.6 microCi
25
Radioactive Decay
  • Ax A0e-0.693 t/T½
  • where
  • Ax Activity of the source at t x
  • A0 Activity of the source at t 0
  • t time elapsed from t 0 to t x
  • T½ Half-life of the specific radionuclide

26
Inverse Square Law
  • I2 I1 (d12/d22)
  • where
  • I1 Intensity of radiation at position 1
  • I2 Intensity of radiation at position 2
  • d1 Distance position 1 is from source
  • d2 Distance position 2 is from source

Exposure rate (i.e. mR/h)
27
Inverse Square Law Example
  • I2 I1 (d12/d22)
  • where
  • I1 120 mR/h
  • d1 2 m from the source
  • d2 4 m from the source
  • I2 (120 mR/h)((2 m)2/(4 m)2)
  • I2 30 mR/h

28
Types of Radiation Hazards
Internal Contamination
  • External Exposure
  • whole-body
  • partial-body
  • Contamination
  • External radioactive material on the skin
  • Internal radioactive material inhaled,
    swallowed, absorbed through skin or wounds

External Contamination
External Exposure
29
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

30
ALARA
  • A - As
  • L - Low
  • A - As
  • R - Reasonably
  • A - Achievable

31
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)

32
StandardRadiation Protection Principles
  • ? Time
  • ? Distance
  • ? Shielding

33
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

34
Natural Background Radiation
  • U.S. average 100 - 400 mrem/y
  • 200 - 300 mrem/y due to radon
  • Parameters
  • mineral deposits (Brazil 7 rem/y - 232Th)
  • elevation above sea level
    (Denver 600 mrem/y - cosmic rays)
  • other- foodstuffs, lifestyle, construction
    techniques for dwellings, etc.

35
Background Radiation
36
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
  • LD50/60 for humans (bone marrow dose)
    350,000 mrem

37
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

38
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.

39
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).

40
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

41
Detecting and Measuring Radiation
  • Detectors or Survey Instruments
  • contamination
  • exposure rate
  • Personal Dosimeters Film, TLD, Self-reading
  • measure doses to responders

42
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 mosho_at_anl.gov
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