U.S.NRC UNITED STATES NUCLEAR REGULATORY COMMISSION Protecting People and the Environment HR D Human ResourcesT Training & Development HealthHealth PhysicsPhysics FundamentalsFundamentals RodRod Reed,Reed, Ph.D.,Ph.D., CHPCHP Senior Health Physicist US Nuclear Regulatory Commission Technical Training Center Chattanooga, Tennessee (423) 855-6513 [email protected] September 6, 2007 Briefing for Media 9/6/07 - slide 0 of 26 AtomicAtomic StructureStructure ¾ Atomic Structure ¾ Protons (p) ¾ Neutrons (η) ¾ Electrons (e) Briefing for Media 9/6/07 - slide 2 of 26 IsotopesIsotopes ofof thethe ElementElement HydrogenHydrogen Briefing for Media 9/6/07 - slide 3 of 26 RadioactivityRadioactivity andand RadiationRadiation ¾ Types of Radiation ¾ Particle emission (α, β-, β+) ¾ Photon emission (γ, x-ray) Briefing for Media 9/6/07 - slide 4 of 26 Radiation Penetration Briefing for Media 9/6/07 - slide 5 of 26 Activity Briefing for Media 9/6/07 - slide 6 of 26 MassMass vsvs ActivityActivity 0.001 gm 1 gm 635,600 gm 60 27Co 226Ra 88 Amount in grams of each isotope equaling 238U one curie of activity 92 210PoPo · 0.000220.00022 gmgm Briefing for Media 9/6/07 - slide 7 of 26 IonizingIonizing RadiationRadiation HalfHalf LifeLife ¾¾ amountamount ofof timetime forfor halfhalf ofof thethe activityactivity toto decaydecay ¾¾ halfhalf lifelife isis uniqueunique toto eacheach radionuclideradionuclide ¾¾ NN--1616 isis 77 secondsseconds (BWRs)(BWRs) ¾¾ CoCo--6060 isis 5.35.3 yearsyears ¾¾ CsCs--137137 isis 30.1730.17 yearsyears ¾¾ PoPo--210210 isis 138138 daysdays Briefing for Media 9/6/07 - slide 8 of 26 Radiation Units Briefing for Media 9/6/07 - slide 9 of 26 SISI vsvs SpecialSpecial UnitsUnits SI Unit Special Conversion Unit Gray Rad 1 Gy = 100 rad Sievert Rem 1 Sv = 100 rem Becquerel Curie 1 Ci = 3.7 x 1010 Bq 11 remrem == 1,0001,000 milliremmillirem (mrem)(mrem) 11 CurieCurie == 1,0001,000 millicuriesmillicuries (mCi)(mCi) Briefing for Media 9/6/07 - slide 10 of 26 Region III Region I Yucca Mtn HQ Region IV ** TTC Region II * 1 µR = 1/1,000,000 R 1 milliroentgen (mR)= 1,000 µR MedicalMedical ProceduresProcedures Procedure Dose (mrem) X-Rays Abdomen 40 Chest 6 Pelvis 60 Dental 3 Mammography 40 CT (full body) 130 Nuclear Medicine 400 Briefing for Media 9/6/07 - slide 12 of 26 AnnualAnnual BackgroundBackground RadiationRadiation DoseDose toto AverageAverage USUS CitizenCitizen ~360 mrem Natural Background total vs Artificial Background ~39 mrem ~200 mrem – rem ~28 m radon Briefing for Media 9/6/07 - slide 13 of 26 ExternalExternal RadiationRadiation DoseDose Gamma, beta or neutron radiation emitted by radioactive material outside the body exposing the skin, lens of the eye, extremities & the whole body (i.e. internal organs) Briefing for Media 9/6/07 - slide 14 of 26 InternalInternal RadiationRadiation DoseDose thyroid RAM is inhaled RAM is inhaled lung oror swallowedswallowed bone GI System Alpha, beta or gamma radiation emitted by radioactive material inside the body exposing internal organs such as: Briefing for Media 9/6/07 - slide 15 of 26 KIKI EffectivenessEffectiveness vsvs TimeTime ofof AdministrationAdministration KI can reduce thyroid dose in an emergency involving radio- active iodine Briefing for Media 9/6/07 - slide 16 of 26 TheThe CellCell DNADNA Briefing for Media 9/6/07 - slide 17 of 26 LowLow--levellevel RadiationRadiation EffectsEffects (most(most exposures)exposures) ¾¾ CancerCancer –– provenproven atat higherhigher dosesdoses (e.g.(e.g. >> 1010 radrad acute);acute); assumedassumed toto occuroccur atat lowerlower doses,doses, withwith nono thresholdthreshold ¾¾ GeneticGenetic effectseffects -- occuroccur inin micemice andand fruitfruit flies;flies; assumedassumed toto occuroccur inin humanshumans butbut nevernever provenproven Briefing for Media 9/6/07 - slide 18 of 26 CanCan RadiationRadiation ExposureExposure CauseCause This?This? Briefing for Media 9/6/07 - slide 19 of 26 LowLow--LevelLevel EffectsEffects -- CancerCancer ¾¾ NaturalNatural cancercancer raterate == 20%20% oror 11 inin 55 (or(or 2,0002,000 outout ofof everyevery 10,00010,000 people)people) ¾¾ RadiationRadiation riskrisk ofof cancercancer (hypothetical)(hypothetical) == 0.04%0.04% oror 44 inin 10,00010,000 perper remrem ¾¾ Thus,Thus, 11 remrem mightmight increaseincrease totaltotal cancercancer riskrisk toto anan exposedexposed personperson toto 20.04%20.04% Briefing for Media 9/6/07 - slide 20 of 26 HighHigh LevelsLevels ofof RadiationRadiation (occur(occur rarely)rarely) Acute Radiation Syndromes: ¾ 100 rad - hematopoietic (blood) ¾ 500 rad – gastrointestinal (GI) ¾ 2,000 rad - central nervous system (CNS) ¾ LD50/60 - lethal dose to 50% of people within 60 days, approximately 400 rad (whole body exposure) Briefing for Media 9/6/07 - slide 21 of 26 NRCNRC OccupationalOccupational DoseDose LimitsLimits Whole Body (TEDE) 5,000 mrem/yr Any Organ (TODE) 50,000 mrem/yr Skin (SDE) 50,000 mrem/yr Extremity (SDE) 50,000 mrem/yr Lens of Eye (LDE) 15,000 mrem/yr Embryo/Fetus of DPW 500 mrem/yr Member of the Public 100 mrem/yr Note: 1,000 mrem = 1 rem Briefing for Media 9/6/07 - slide 25 of 26 THETHE ENDEND Briefing for Media 9/6/07 - slide 26 of 26.