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 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 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

13 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

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 Physical Radionuclide Half-Life Activity Where Found Cesium y 1.5x10 6 Ci Food Irradiator Cobalt-60 5 y 15,000 Ci Cancer Therapy Plutonium-23924,000 y600 CiNuclear Weapon Iridium d 100 Ci Ind. Radiography Hydrogen-3 12 y 12 Ci Exit Signs Strontium-9029 y 0.1 CiOcular Therapy Iodine d Ci Nuclear Medicine Technetium-99m 6 h Ci Diagnostic Imaging Americium y Ci Smoke Detectors Radon d 1 pCi/l Environment Examples of Radioactive Materials

20 Measure of Amount of radioactive material Ionization in air Absorbed energy per mass Absorbed dose weighted by type of radiation Radiation Units 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

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 A x = A 0 e 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 (4 y/30 y) A x = 4.6 microCi

25 Radioactive Decay A x = A 0 e 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

26 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)

27 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

28 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

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 Standard Radiation 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: mrem/y [ mrem/y due to radon] Parameters: – mineral deposits (Brazil ~ 7 rem/y Th) – 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 LD 50/60 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 organs50 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