May Radiation Safety Overview for Environmental Professionals Student Manual

Transcription

1 May 2015 Radiation Safety Overview for Environmental Professionals Student Manual

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3 Radiation Safety Overview for Environmental Professionals Table of Contents Foreword & Course Description Unit 1 Unit 2 Unit 3 Unit 4 Unit 5 Unit 6 Orientation / Introduction Atomic Structure and Fundamental Principles of Radiation Types and Characteristics of Ionizing Radiation Radiation Dose Limits and Biological Effects Radiological Area Posting Requirements References Provided on Course CD

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5 Foreword This manual is for reference use of students enrolled in scheduled training courses of the U.S. Environmental Protection Agency (EPA). While it will be useful to anyone who needs information on the subjects covered, it will have its greatest value as an adjunct to classroom presentations involving discussions among the students and the instructional staff. This manual has been developed with a goal of providing the best available current information; however, individual instructors may provide additional material to cover special aspects of their presentation. Because of the limited availability of the manual, it should not be cited in bibliographies or other publications. References to products and manufacturers are for illustration only; they do not imply endorsement by EPA. Constructive suggestions for improvement of the content and format of the Radiation Safety Overview for Environmental Professionals manual are welcome.

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7 Radiation Safety Overview for Environmental Professionals 1 Day This one day introductory level course is designed to provide participants with an overview and basic understanding of the fundamental principles of radiation safety, provide guidance on EPA radiation exposure limits for site work involving radioactive materials, and provide information on radiological area posting requirements. This course is intended for environmental professionals who are not health physicists or other radiation safety specialists, but require a basic knowledge and understanding of radiation safety. Participants who are responsible for reviewing and discussing radiological issues will benefit from this course. Topics that are discussed include fundamental concepts of atomic structure, radiation, and radioactive decay; methods and characteristics of radiation interaction with matter; radiation dose limits and basic methods to control radiation exposures, biological effects of radiation, and posting requirements. Instructional methods include lectures, class discussions, and demonstrations. After completing the course, participants will be able to: Discuss basic terminology and fundamental principles of radiation. Identify the three primary types and characteristics of ionizing radiation. Identify radiation dose limits and explain basic methods to control exposures. Discuss biological effects of radiation. Identify radiological area postings. Continuing Education Units: 0.6

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9 Introduction RADIATION SAFETY OVERVIEW FOR ENVIRONMENTAL PROFESSIONALS presented by Tetra Tech, Inc. for the U.S. Environmental Protection Agency's Environmental Response Team ENVIRONMENTAL RESPONSE TRAINING PROGRAM (ERTP) U.S. EPA OSWER OSRTI ERT United States Environmental Protection Agency Office of Solid Waste and Emergency Response (Superfund) Office of Superfund Remediation and Technology Innovation Environmental Response Team ERTP TRAINING COURSES Are offered tuition-free for environmental and response personnel from federal, state, and local agencies Vary in length from one to five days Are conducted at EPA Training Centers, and at other locations throughout the United States 1

10 Introduction ERTP TRAINING COURSES Course Descriptions, Class Schedules, and Registration Information are available at: COURSE OBJECTIVES Discuss basic terminology and fundamental principles of radiation Identify the three primary types and characteristics of ionizing radiation Identify radiation dose limits and explain basic methods to control exposures Discuss biological effects of radiation Identify radiological area postings COURSE MATERIALS Student Registration Card Course Agenda Student Evaluation Form Student CD Course Exam 2

11 Introduction Please... In consideration of your fellow students and the instructors, please silence all cell phones and pagers VIBRATE MODE 3

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13 Atomic Structure And Fundamental Principles Of Radiation ATOMIC STRUCTURE AND FUNDAMENTAL PRINCIPLES OF RADIATION Student Performance Objectives Identify the three basic particles of an atom, and understand some of their characteristics Identify the components of chemical notation and their meanings Define radionuclide Student Performance Objectives Define radioactive decay, and half-life Identify the decay scheme of a radioactive element Calculate the activity of a radioactive isotope 5

14 Atomic Structure And Fundamental Principles Of Radiation Atoms are the Fundamental Building Blocks of All Matter The Atom The smallest building block of matter Proton Neutron Electron Components of an Atom: Weight Charge Neutron 1 amu none Proton 1 amu +1 Electron.0005 amu -1 Proton Positively charged Number of protons determines the element Mass = 1 atomic mass unit (AMU) = (1.673 x gram) 6

15 Atomic Structure And Fundamental Principles Of Radiation Neutron No charge N Mass of 1 AMU Number of neutrons determines the isotope 1 1H 2 1H 3 1H Electrons Negatively charged particles that orbit the nucleus Mass of.0005 AMU Orbit in structured shells Shells are lettered K - Q Electron Shells KLMNO 7

16 Atomic Structure And Fundamental Principles Of Radiation Chemical Notation # Chemical Name Atomic Weight Boron Aluminum B Al Atomic Number (Proton #) Xx Carbon Silicon Chemical Symbol C Si Nitrogen N P Phosphorus Oxygen Sulfur O S Fluorine Chlorine F Cl 2 Helium Neon Argon He Ne Ar Convention A Z X A = Mass Number = Z + N (Note: N = neutron number) Z = Atomic number (number of protons) X = Element symbol (indicates element) Notation Example 12 C 12 6 = C = C-12 8

17 Atomic Structure And Fundamental Principles Of Radiation Nuclide A species of an atom characterized by the constitution of its nucleus, which is specified by its number of protons and neutrons, and its energy content. Radionuclide A radioactive (unstable) nuclide. Isotopes Atoms of the same element with a different number of neutrons (same Z, but different A). 9

18 Atomic Structure And Fundamental Principles Of Radiation Isotope Examples 12 6 C 13 6 C 1 1 H (C-12 and C-13 are stable) 2 1 H (H-1 and H-2 are stable) 14 6 C 3 1 H Radioactivity The process by which unstable atoms try to become stable, and as a result, emit radiation Ra-226 α Rn-222 Radiation Energy emitted as electromagnetic waves or energetic particles 10

19 Atomic Structure And Fundamental Principles Of Radiation Radioactive Decay Process by which atoms change (decay) to atoms of a different element or to a lower energy state of the same element by the spontaneous emission of charged particles or electromagnetic waves Causes - Radioactive Decay Unstable proton-to-neutron ratio Excess binding energy Line of Stability Line of stability 11

20 Atomic Structure And Fundamental Principles Of Radiation Radioactive Decay Natural Radioactivity naturally-occurring radionuclides Cosmic and solar Seawater: K-40 Soil: U and Th Artificial or Induced Radioactivity Radioactivity produced in a stable substance by particle bombardment or electromagnetic irradiation of elements Also called activation Co-59 Co-60 neutron bombardment 12

21 Atomic Structure And Fundamental Principles Of Radiation Activity The measurement of radioactive material Measured by counting the number of disintegrations per unit time Disintegrations per second (dps) Disintegrations per minute (dpm) Traditional Activity Units Note: International System (SI) 1 Becquerel (Bq) = 1 dps Activity Subunits 1 microcurie (µci) = 1 x 10-6 Ci 1 picocurie ( Ci) = 1 x Ci 13

22 Atomic Structure And Fundamental Principles Of Radiation Decay Schemes Radioactive Disintegration Series for Uranium 238 U Th Pa U y 90 25d 91 7 h y Uranium Thorium Protactinium Uranium Th Thorium Pb Lead Bi Bismuth y 27 min 5 d Ra Radium Bi Bismuth Po y 20 min d Polonium Rn Radon Po Po Pb y 82 Polonium Lead Pb Lead (a stable isotope) 4 d Polonium 3 min 22 y y = Years d = Days min = Minutes s = Seconds a = Alpha Particle = Beta Particle = Gamma Ray Decay Constant The fraction of atoms that disintegrate per unit time for a particular radionuclide ln 2 T ½ ln 2 = natural log of 2 (0.693) T ½ = half-life of the radionuclide Half-Life The time required for a radioactive substance to lose one-half of its activity due to radioactive decay. Each radionuclide has a specific half-life. 14

23 Atomic Structure And Fundamental Principles Of Radiation Calculate the Activity A = A o e - t where: A = activity after time t A o = original activity e = base of natural logarithm (2.718) = decay constant (ln 2/half-life) t = elapsed time Example A 10.5 Ci Co-60 radiography source was prepared three years ago, having a halflife of years. What is the activity today? A o t T ½ = 10.5 Ci = 3 years = years Equation -ln 2 A = A o e ( ) T½ t A = 10.5e ( 5.271) A = 10.5e A = 10.5(0.677) A = 7.1 Ci Co-60 15

24 Atomic Structure And Fundamental Principles Of Radiation Half-Life Problem An air sample was collected from a thorium-contaminated building and was immediately counted, yielding 2500 Ci/l. The sample was recounted five minutes later, giving an activity of 59.4 Ci/l. What is the half-life and the most likely isotope of the sample? Half-Life Variables T ½ = ln 2(t) ln Half-Life Calculation A t A o T ½ = 0.693(5) ln T ½ = 3.74 = 0.92 min 60 sec. = 55.6 sec. Radon 220 (a.k.a. Thoron) 16

25 Atomic Structure And Fundamental Principles Of Radiation Conclusion Three basic particles of the atom Chemical notation Radionuclide Radioactive decay Decay scheme Activity and half-lives QUESTIONS? 17

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27 Types And Characteristics of Ionizing Radiation TYPES AND CHARACTERISTICS OF IONIZING RADIATION Student Performance Objectives Define ionization and excitation as they apply to the interaction of radiation with matter Distinguish between ionizing radiation and non-ionizing radiation State the four basic types of ionizing radiation and list their characteristics Define Bremsstrahlung Identify shielding for various types of radiation Four Basic Types of Ionizing Radiation Alpha particles Beta particles _ Gamma rays Neutrons 19

28 Types And Characteristics of Ionizing Radiation Common Interactions of Radiation With Matter Ionization Excitation Ionization Alpha particle Ionized electron The stripping of an orbital electron from an atom Secondary Ionization e - to another atom Ionization caused by a particle which is itself a result of ionization 20

29 Types And Characteristics of Ionizing Radiation Excitation The forced movement of an electron from an inner shell to some outer shell Linear Energy Transfer (LET) The amount of energy deposited by a specific radiation over a specific distance (ionizations per unit path length) 10,000s of ionizations/cm air 100s of ionizations/cm air 1 ionization/cm air Characteristics of Alpha Particles Emitted from nucleus Composition: 2 neutrons, 2 protons (identical to 4 He nucleus) High mass: 4 amu High charge: + 2 High energy: 4-8 MeV 21

30 Types And Characteristics of Ionizing Radiation Sources of Alpha Particles Radioactive decay of heavier radionuclides (predominantly Z > 82) Examples: U Pu U Ra Th + α MeV 2 4 α MeV 4 86Rn + α MeV 2 Alpha Particle Interactions Path length ~ 1 inch in air High ionization per unit path length (LET) Becomes helium atom by attracting two electrons Alpha Particle Interactions Alpha Particle Ionized Electron Nucleus 22

31 Types And Characteristics of Ionizing Radiation Characteristics of Beta Particles Emitted from nucleus Composition: identical to electron Two types: negatron with -1 charge (β-) positron with +1 charge (β+) Low mass: about.0005 amu Energies: most commonly 0.1 to 4 MeV Share decay energy with neutrino Sources of Beta Particles β- emitted from nucleus with too many neutrons β+ emitted from nucleus with too few neutrons Examples: 3 0 H He + β MeV K Ca + β MeV K Ar + β MeV (89%) (11%) Beta Particle Interactions Possible bremsstrahlung Medium ionization per unit path length (LET) Path length a few feet in air Positrons produce annihilation photons 23

32 Types And Characteristics of Ionizing Radiation Beta Particle Interactions Beta Particle Ionized Electron Nucleus Bremsstrahlung Braking Radiation is produced by the deceleration of a beta particle around the (+) charged nucleus of an atom, causing x-rays to be emitted. Bremsstrahlung X-ray Nucleus High energy beta particles interacting with high Z materials 24

33 Types And Characteristics of Ionizing Radiation Characteristics of Gamma Rays Electromagnetic energy Gamma rays from nucleus Zero mass, zero charge Energies: most commonly 0.5 to 2 MeV Sources of Gamma Rays Nucleus rearrangements following alpha or beta decay Nucleus moves from excited state to lower energy state Examples: 137 Cs Ba * 137 Ba * Ba β MeV gamma ray The Electromagnetic Energy Spectrum IONIZING RADIATION (potentially harmful or beneficial to humans) Low frequency/energy High frequency/energy 25

34 Types And Characteristics of Ionizing Radiation The Electromagnetic Energy Spectrum WAVELENGTH FREQUENCY ENERGY (meters) (hertz) (ev) x x x x10 8 GAMMA COSMIC x x10 4 ULTRAVIOLET X-RAYS x INFRARED VISIBLE x x10-4 MICROWAVES RADIO TV x x10-8 TV SHORTWAVE RADIO x x10-12 ELECTRIC POWER Gamma Ray Interactions Very long path length ~ 100s of meters in air Low ionization per unit path length (LET) Three principle interactions Photoelectric effect Compton scattering Pair production Photoelectric Effect Gamma Photon Ionized Electron N + + N N + 26

35 Types And Characteristics of Ionizing Radiation Compton Scattering Ionized Electron Gamma Photon N + + N N + Reduced Energy Photon Pair Production (all photon energy converted to mass) (-) Electron Gamma Photon N + + N N + + (+) Positron Characteristics of Neutrons Emitted from nucleus Mass: 1 amu Charge: 0 Energies Thermal neutrons ~ ev Fast neutrons ~ 0.1 to 10 MeV 27

36 Types And Characteristics of Ionizing Radiation Sources of Neutrons Spontaneous fission of uranium and transuranics Neutron-induced fission in Operating nuclear reactors Nuclear weapons explosions Neutron sources alpha bombardment alpha sources mixed with beryllium (americium, polonium, plutonium) 9 Be α C* 6C n Neutron Interactions Almost exclusively nuclei interactions Activation and excitation of nuclei Long path lengths in air ~ hundreds of feet, but much shorter path lengths in hydrogenous materials Shielding Alpha Radiation Most alpha particles are stopped by a few centimeters of air, a sheet of paper, or the dead layer of skin Alpha particles are considered an internal hazard only. If ingested or inhaled, they can cause great damage 28

37 Types And Characteristics of Ionizing Radiation Shielding Beta Radiation Shielded by plastic, aluminum, rubber, glass, or safety glasses Can penetrate skin and eyes Most dangerous if inhaled or ingested Shielding Gamma Radiation Shielded by very dense materials (high Z) such as iron, lead, or steel Very penetrating, thus whole-body hazard Shielding Neutron Radiation Has ability to penetrate the whole body Primarily an external hazard, but not normally found in the environment Shielded by hydrogenous materials such as water or paraffin 29

38 Types And Characteristics of Ionizing Radiation Shielding Materials PAPER ALUMINUM LEAD WATER ALPHA BETA GAMMA, X-RAYS NEUTRONS QUESTIONS? 30

39 Radiation Dose Limits and Biological Effects RADIATION DOSE LIMITS AND BIOLOGICAL EFFECTS Student Performance Objectives Discuss EPA s Radiation Safety Program Identify two EPA administrative exposure guidelines Identify three radiation exposure reduction methods List at least three possible biological effects of ionizing radiation on a cell Radiation Dose Limits 31

40 Radiation Dose Limits and Biological Effects Radiation Exposure Safe Guidance Principle ALARA (As Low As Reasonably Achievable) Adopted by: International Commission on Radiological Protection (ICRP) National Council on Radiation Protection and Measurements (NCRP) Units of Dose Measurement Roentgen (R): A measure of charge produced by "X" and "Gamma" rays. That amount of X or gamma radiation that will produce 1 electrostatic unit of charge per cubic centimeter of air (cm 3 ). Most radiation exposure instruments measure in R/hr, mr/hr, µr/hr (dose rate) Units of Dose Measurement RAD: Radiation Absorbed Dose. The amount of energy absorbed in material (tissue). 1 RAD = 100 ergs/g of energy 1 RAD =.01 Gray (Gy) 32

41 Radiation Dose Limits and Biological Effects Units of Dose Measurement REM: Roentgen Equivalent Man. A unit of Dose Equivalent for any type of radiation calculated as the product of the number of rads times the radiation weighting factor. It is designed to indicate potential effectiveness for damaging tissue. 1 REM =.01 Sievert (Sv) Radiation Weighting Factor A numerical value multiplied by the absorbed dose (RAD) to determine the dose equivalent (REM). Formally known as the quality factor. Note: The term quality factor (QF) was changed to radiation weighting factor (W r ) in the 1990 recommendations of ICRP CFR20 does not yet use the newer term. Radiation Weighting Factor (RAD x W r = REM) GAMMA: W r = 1; 1 RAD x 1 = 1 REM BETA: W r = 1; 1 RAD x 1 = 1 REM NEUTRON: W r = 10 (unknown energy); 1 RAD x 10 = 10 REM ALPHA: W r = 20; 1 RAD x 20 = 20 REM 33

42 Radiation Dose Limits and Biological Effects Radiation Subunits 1 rem = 1,000 mrem (millirem) 1 mrem = 1,000 µrem (microrem) 1 R = 1,000 mr = 1,000,000 µr EPA s Radiation Safety Program U.S. EPA Safety, Health and Environmental Management Program (SHEMP) Guide 38 Guide 38 Radiation Safety and Health Protection Program EPA s Radiation Safety Program Defines EPA s program for minimizing occupational radiation exposure of its workers. Provides requirements for Radiation Safety Training. Provides Radiation Exposure Guidelines. Provides Guidelines for Monitoring and recording Radiation Exposures. 34

43 Radiation Dose Limits and Biological Effects Administrative Control Level (ACL) for U.S. EPA Employees Enrolled in program ACL of 500 mrem/year Any 12 consecutive months At 500 mrem restrict radiation exposure (do not exceed 500 mrem for any 12-month period) Action Reference Level (ARL) for U.S. EPA Employees ARL of 50 mrem/quarter Monitor the employee dose every quarter year Measured over three months (one quarter) Emergency Exposure Guidance for U.S. EPA Employees Instructions on dose limitation for designated EPA workers performing emergency response services are provided in the Manual of Protective Action Guides and Protective Actions for Nuclear Incidents (EPA 400-R ). These dose limits supersede the ACL during radiological emergencies. Always, dose management should begin at 1 mr/hr. Source: U.S. EPA SHEMP 38 35

44 Radiation Dose Limits and Biological Effects U.S. EPA Dose Limits for Workers Performing Emergency Services 5 rem All activities 10 rem To protect valuable property, when lower dose not practicable 25 rem Life saving or protection of large population when lower dose not practicable >25 rem Life saving or protection of large populations only on a voluntary basis to persons fully aware of the risks involved Source: U.S. EPA 400-R , Manual of Protective Action Guides and Protective Actions for Nuclear Incidents, 1991, Table 2-2, page Emergency Exposure Guidance for U.S. EPA Employees In addition to the Protective Action Guides, workers in radiological emergency responses may be confronted with high radiation exposure rates. Turnback level guidelines for EPA workers performing emergency response under the EPARERP are provided in Guidance for U.S. EPA Personnel Responding to Radiological Emergencies. Emergency Exposure Guidance "Turnback Levels" Time Period Stop-and-Check Condition Early Phase 10 R/h Voluntary, with supervisor review, for lifesaving or critical actions ONLY evaluate anticipated doses against dose limits above Intermediate Phase 1.5 R/hr Dose management imperative Late or Recovery Phase Site-specific according to site health and safety plan EPA Action Reference Level: 50 mrem/quarter and Administrative Control Level: 500 mrem/year Source: U.S. EPA SHEMP 38 36

45 Radiation Dose Limits and Biological Effects Declared Pregnant Worker NRC Regulatory Guide 8.13 entitled Instruction Concerning Prenatal Radiation Exposure, recommends the Federal dose limitation value for an unborn child during pregnancy (conception through birth), and emphasize the importance of female workers declaring pregnancy as soon as known. Declared Pregnant Worker The ACL, established for EPA workers is also deemed by EPA to provide an acceptable level of reproductive protection both for parents and their embryo/fetus during the gestation period, and is consistent with the limits of NRC Regulatory Guide Declared Pregnant Worker NRC Regulatory Guide 8.13, and SHEMP Guide 38 recommendations for declared pregnant worker (voluntary) Worker may notify employer in writing that she is pregnant The declaration may be revoked in writing at any time by the declared worker 500 mrem limit/gestation period 37

46 Radiation Dose Limits and Biological Effects Monitoring and Dosimetry of U.S. EPA Employees Dosimeter required for U.S. EPA work activities where radiation exposure is above background Thermoluminescent dosimeter (TLD): Monitors external exposure Wear for one calendar quarter, then read for dose Exchanged more frequently under special circumstances Whole Body TLD Worn between the shoulders and the waist, and worn underneath protective clothing, on the front of the body. The active element of the dosimeter should be facing outward. Monitoring and Dosimetry of U.S. EPA Employees Additional dosimeters: Extremity TLD dosimeters: finger ring, wrist, ankle Neutron Electronic Personal Dosimeter (EPD) 38

47 Radiation Dose Limits and Biological Effects Extremity dosimeter: Worn on the hand/finger of the hand most exposed to the radiation source. The active element of the dosimeter should face the source of radiation. Electronic Personal Dosimeter (EPD) Dose/dose rate level alarms Worn on the front of the body. The active element of the dosimeter should be facing outward. Emergency Contractor Monitoring If contractor personnel who do not normally qualify for enrollment in the EPA Program must participate in critical, emergency or imminent danger response at an EPA facility or EPA controlled site, EPA shall, whenever possible, provide temporary dosimeter(s) for all personnel at risk for exposure. 39

48 Radiation Dose Limits and Biological Effects Protective Action Guides (PAGs) During a radiological emergency, public health officials must act quickly to protect public health. EPA has developed a system (PAGs) to help officials make critical decisions. Source: U.S. EPA 400-R Protective Action Guides (PAGs) PAGs identify three phases of an emergency: Early Intermediate Late Protective Action Guides (PAGs) Early phase Several hours to several days, evacuation and sheltering are the principal actions to protect the public from exposure to direct radiation and inhalation of airborne radioactive material 40

49 Radiation Dose Limits and Biological Effects Protective Action Guides (PAGs) Intermediate phase From weeks to months, protective actions may include limiting food and water consumption to decrease ingestion of radioactive material and relocating people to protect them from radiation exposure Protective Action Guides (PAGs) Late phase From months to years, the PAGs address the decontamination of property OSHA Dose Limits 29 CFR Quarterly Whole-body: head and trunk, active blood-forming organs, lens of eyes, or gonads: 1.25 rem per quarter (5 rem/year) Hands and forearms, feet and ankles: rem per quarter (75 rem/year) Skin of whole body: 7.5 rem/quarter (30 rem/year) 41

50 Radiation Dose Limits and Biological Effects DOE Dose Equivalent Limits and Controls Whole-body Extremity Skin & other organs Lens of eye Members of the public Declared pregnant worker Source: 10 CFR 835 DOE Dose Equivalent Limit rem/year Facility Administrative Controls rem/year Facility-specific Facility-specific Facility-specific Facility-specific Facility-specific Facility-specific NRC Dose Equivalent Limits NRC standard 10 CFR 20 5 rem/year NRC standard 10 CFR 20, Appendix B Provides annual limits on intake (ALI) Limits on intake of given radionuclide by a "reference man" ALARA ALARA (As Low As Reasonably Achievable) Principle for minimizing radiation doses and release of radioactive materials by all reasonable methods 42

51 Radiation Dose Limits and Biological Effects Exposure Reduction Methods Time Minimize the time of exposure Distance Maximize the distance to reduce exposure rate Shielding Use appropriate absorber materials to reduce exposure Biological Effects Biological Effects of Radiation More is known about the biological effects of radiation than about most other environmental factors Four major groups of people who have been exposed to radiation: Radiological workers Atomic bomb survivors (250,000) People involved in radiation accidents Radiation therapy patients 43

52 Radiation Dose Limits and Biological Effects Effects of Acute Radiation Dose Dose received in a short time period, usually less than one day 700 RAD = LD 100 Within days 600 RAD = LD 99 Within days 450 RAD = LD 50 Within 30 days 200 RAD = LD LO Within several weeks 100 RAD = TD LO Immunosuppressive reaction 25 RAD = ED LO Blood serum changes Effects of Chronic Radiation Dose Small amount of radiation over a long time period Body has time to repair damage Effects of Chronic Radiation Dose Any member of the U.S. population has about a 33% chance of contracting cancer and about a 25% chance of dying of cancer Cancer risk is approximately.02%/rem 50 rem = 1% increased risk of cancer 44

53 Radiation Dose Limits and Biological Effects Damage Mechanisms Living tissue damage can result when ionizing radiation causes atoms and molecules to become ionized or excited Ionizations and excitations can: Produce free radicals Break chemical bonds Damage molecules that control essential cell functions (e.g., DNA) Possible Effects of Radiation On Cells Cells may not be damaged Cells may be damaged, but can fully repair at lower levels and operate normally Cells may be damaged and operate abnormally Cell death may result at higher doses Most Radiosensitive Cell Sensitivity Actively dividing and non-specialized cells Blood-forming cells Cells that line the intestinal tract Hair follicles Cells that form sperm These cells are more susceptible to damage from ionizing radiation 45

54 Radiation Dose Limits and Biological Effects Least Radiosensitive Cell Sensitivity Less actively dividing and more specialized cells Cells that divide more slowly Specialized cells Brain cells Muscle cells These cells are not as susceptible to damage from ionizing radiation Somatic Effects Damage to cells other than reproductive cells Seen in the exposed individual Not passed on to offspring Delayed Somatic Effects Delayed effects may result from acute or chronic exposure Cancer Cataracts Shorter life expectancy 46

55 Radiation Dose Limits and Biological Effects Genetic Effects of Radiation Exposure Mutations due to radiation damage to the DNA of a cell Genetic damage passed on to offspring Atomic bomb survivors: No heritable effects found in children born to the survivors; 77,000 children Sources of Radiation Exposure Naturally occurring in the environment Man-made radionuclides in the environment See: and Average Annual Dose The average annual dose to the general population is about 625 mrem. This estimate is for non-smokers. SOURCE: 2009 NCRP Report No. 160 Ionizing Radiation Exposure of the Population of the United States 47

56 Radiation Dose Limits and Biological Effects Sources of Radiation Exposure of the U.S. Population SOURCE NATURAL (ubiquitous background) SOURCE (mrem/year) % of TOTAL Internal, inhalation (radon and thoron) % External, space. 33 5% Internal, ingestion. 29 5% External, terrestrial 21 3% TOTAL NATURAL % SOURCE: 2009 NCRP Report No. 160 Ionizing Radiation Exposure of the Population of the United States Sources of Radiation Exposure of the U.S. Population SOURCE SOURCE (mrem/year) % of TOTAL MANMADE Medical % CT 147, 24% Nuclear Medicine 77, 12% Interventional Fluoroscopy 43, 7% Conventional Radiography and Fluoroscopy 33, 5% Consumer. 13 2% Industrial....3 <0.1% Occupational..5 <0.1% TOTAL MANMADE (Non-smokers) % SOURCE: 2009 NCRP Report No. 160 Ionizing Radiation Exposure of the Population of the United States Sources of Radiation Exposure of the U.S. Population SOURCE SOURCE (mrem/year) % of TOTAL TOTAL NATURAL % TOTAL MANMADE (Non-smokers) % TOTAL OF MANMADE AND NATURAL % (Non-smokers) SOURCE: 2009 NCRP Report No. 160 Ionizing Radiation Exposure of the Population of the United States 48

57 Radiation Dose Limits and Biological Effects Sources of Radiation Exposure of the U.S. Population Terrestrial (background) 3% Internal (background) 5% Space (background) 5% Radon and Thoron (background) 37% Computed Tomography (medical) 24% Nuclear Medicine (medical) 12% Interventional Fluoroscopy (medical) 7% Consumer 2% Conventional Radiography & Fluoroscopy (medical) 5% Occupational <0.1% Industrial <0.1% SOURCE: 2009 NCRP Report No. 160 Ionizing Radiation Exposure of the Population of the United States HEALTH RISK Smoking 20 cigarettes a day Overweight by 15% Alcohol (U.S. average) All accidents Occupational dose of 1 rem/year from age (47 yrs total) Occupational dose of 300 mrem/year from age (47 yrs total) All natural hazards Medical radiation ESTIMATED LIFE EXPECTENCY LOST 6 years 2 years 1 year 207 days 51 days 15 days 7 days 6 days SOURCE: these estimates are taken from NRC Draft Guide DG-8012 and were adapted from B.L. Cohen and L.S. Lee, "Catalogue of Risks Extended and Updates," Health Physics, Vol. 61, September QUESTIONS? 49

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59 Radiological Area Posting Requirements RADIOLOGICAL AREA POSTING REQUIREMENTS Student Performance Objectives Identify the common NRC, DOE, and OSHA regulations for proper posting requirements Identify "radiation area," "high radiation area," "very high radiation area," "airborne radioactivity," and "radioactive material" Posting Overview Postings alert workers and members of the public to the presence of radiological hazards. Uniform posting across agencies avoids misunderstanding. Postings provide valuable information to emergency responders. 51

60 Radiological Area Posting Requirements Radiological Area Posting Requirements NRC: 10 CFR OSHA: 29 CFR (in revision) DOE: 10 CFR Conventions: Colors: magenta or black on yellow Three-blade design called a trefoil Radiation Symbol Design-standard geometry Radiation symbol CAUTION RADIATION AREA Dose equivalent of >0.005 rem in 1 hour at 30 centimeters from the radiation source or any surface that radiation penetrates Perimeter barriers: rope, chain, fence, or wall 52

61 Radiological Area Posting Requirements CAUTION HIGH RADIATION AREA Dose equivalent of >0.1 rem in 1 hour at 30 centimeters from the radiation source or any surface that radiation penetrates Perimeter barriers: fence, wall, with locked or guarded entry GRAVE DANGER VERY HIGH RADIATION AREA Absorbed dose of >500 rads in 1 hour at 1 meter from the radiation source or any surface that radiation penetrates Perimeter barriers: fence, wall, with locked or guarded entry CAUTION AIRBORNE RADIOACTIVITY AREA Concentrations >derived air concentrations (DAC) specified in Appendix B to 10 CFR 20, or weekly intake of 0.6% of the annual limit on intake (ALI), or 12 DAC-hours Perimeter barriers: rope, chain, fence, or wall 53

62 Radiological Area Posting Requirements CAUTION RADIOACTIVE MATERIAL Amount of radioactive material >10 times the quantity specified in Appendix C to 10 CFR 20 or greater than the quantity specified in Appendix E of 10 CFR 835. Perimeter barriers: rope, chain, fence, or wall CAUTION SURFACE CONTAMINATION Posted where radioactive surface contamination (loose or fixed) exceeds the limits for an uncontrolled area Perimeter barriers: rope, chain, fence, or wall Container Labels Must have label with radiation symbol and the words Caution or Danger Radioactive Material, with sufficient information for handlers of containers to minimize exposure, such as: Radionuclide(s) present Activity Date Radiation level Kind of material 54

63 Radiological Area Posting Requirements Posting Configurations (NRC) Site Boundary Protected Area* (GET Required) RCA Radiation Area RMA High Radiation Area Locked High Radiation Area Contamination Area Airborne Radioactivity Area * Optional Posting Configurations (DOE) Site Boundary Controlled Area (GERT Recommended) Radiological Buffer Area (RW-I*) Radiation Area (RW-I) High Radiation Area (RW-II) Very High Radiation Area (RW-II) RMA (RW-I) Radiological Buffer Area (RW-I*) Contamination Area (RW-II) High Contamination Area (RW-II) Airborne Radioactivity Area (RW-II) * Minimum Training Requirement Radiation Safety Signs and Labels 55

64 Radiological Area Posting Requirements Argonne National Laboratory Argonne National Laboratory Fernald 56

65 Radiological Area Posting Requirements Fernald Fernald Fernald 57

66 Radiological Area Posting Requirements Some Variations Hazard Recognition Be aware of your surroundings 58

67 Radiological Area Posting Requirements QUESTIONS? 59