辐射安全常识

Industrial Studies 4020Topics in Industrial StudiesEnvironmental Safety Management Atomic number Atomic massNumber of Protons ONLY Number of Protons&Neutrons (weight)C1412Chemical SymbolAtomic MassAtomic NumberReviewSo,what is it?H3Hydrogen 3 contains one proton+two neutrons.Its a radioactive isotope of hydrogen also known as tritiumIsotopes Same number of protons;different number of neutrons Same chemical properties Different nuclear propertiesHydrogen1 ProtonDeuterium1 Proton,1 Neutron*Tritium1 Proton,2 NeutronsH11*Note:Tritium is RadioactiveHH2131Radioactivity Atoms with too many neutrons or protons are unstable and emit energy to become more stable.Energy is carried away by a a-/b b-particle or x-/g g-ray.These atoms are called radioactive and the process is called radioactive decayRadioactivity Natural Uranium Thorium Potassium-40 Carbon-14(C-14)Hydrogen-3(H-3)(tritium)Man madePhosphorus-32(P-32)Sulfur-35(S-35)Calcium-45(Ca-45)Chromium-51(Cr-51)Zinc-65(Zn-65)Rubidium-86(Rb-86)Iodine-125(I-125)RadiationMicrowave light bulbcell phone UV lampradio/TV laserheat lamp x-raysEmission/propagation of energy through space or material medium as waves or particlesIonizing RadiationAlpha Particles2 Protons+2 NeutronsShort Range in AirNot an External Hazard Internal HazardBeta ParticlesNegligible MassLong Range in AirInternal/External HazardChargedGamma Rays/PhotonsGamma photons&X-Ray both electromagnetic differ only by place of origin No mass or chargeHighly-penetratingNeutronsVery Long RangeVery PenetratingDifficult to detectOther modes of DecayPositron emissionElectron captureFissionElectron Decay is a statistical process.Cannot predict when a particular atom will decay.Can predict when certain amount(%)will have decayed.Units of ActivityCurie(Ci)1 Ci=37,000,000,000 dps(3.7 x 1010 dps)or1 Ci=2.22 x 1012 dpm Becquerel(Bq)1 Bq=1 dps 1 Ci=37,000,000,000 Bq=37 GBq(Giga Becquerel)Beta and gamma radiation about equally damaging:1 R=1 rad=1 rem Alpha radiation causes greater cellular damage 1 rad of a a=20 rem Half-life,A=A0 e 0.693t/TA=A0()#of half-livesNon-Ionizing RadiationQuestions?Industrial Studies 4020Topics in Industrial StudiesEnvironmental Safety Management External Hazard(exposure from outside the body)High-energy beta(i.e.,energy 300 keV or 0.3 MeV)Gamma and X-rays Neutrons Internal Hazard Radioactive material enters body by eating/drinking in radiation area,by breathing vapors/aerosols,or skin absorption In body,it is treated like non-radioactive elements If not incorporated into organ,rapidly excreted and maypose only slight hazard If stored in organ,slowly excreted(effective half-life)Whole body,external acute exposure effects25 rad some chromosome aberrations50 rad minor blood changes100 rad 2%radiation sickness400 rad 50%die in 60 days(LD50/60)700 rad lethal single exposure6000 rad cancer therapy(local)As Low As Reasonably Achievable Benefits outweigh risks?Lower Dose=Lower Risk Whole body badge (TLD)Collar or Ring TLD Bioassay-thyroid(iodine)urinalysis(tritium)Occupational Exposure LimitsNot to Exceedmrem/yr rem/yr mSv/yr5,000 5 5015,000 15 15050,000 50 50050,000 50 500Accumulated DoseEquivalent to:Whole BodyLens of the EyeSkin of Whole BodyExtremities of WholeBody-Hands,Feet,etc TIMEExposure increases with time SHIELDINGPlastic for betaLead for gamma DISTANCEExposure decreases with distancevIncreased exposure(risk)over time Linear3 mR/hr*4 hr=?I1d12=I2d22 Thick,dense (i.e.,lead)for gamma/x-raysPlastic betaHydrogeneous(or boron+cadmium)for neutronsNo shielding needed for alpha or low-energy beta1)Capable of Detecting 2)Efficiency3)Calibration Industrial Uses of Radiationhttp:/www.epa.gov/rpdweb00/source-reduction-management/applications.htmlIndustrial Uses of RadiationLasersX-raysGaugesWireless exit signs X-ray Fluorescence(XRF)Industrial Uses of Radiationhttp:/www.epa.gov/rpdweb00/source-reduction-management/applications.htmlMoisture/density gaugesRadiographyStatic controlSmoke detectorsEmergency Response Lifesaving and serious injury take precedence over radiation exposure and contamination Control Access to Area Call for HelpIndustrial Studies 4020Topics in Industrial StudiesEnvironmental Safety ManagementTypes of Radioactive Waste Spent Fuel-Withdrawn from a nuclear reactor following irradiationHigh-level waste-Highly radioactive material from reprocessing spent nuclear fuelTransuranic-Man-made elements above atomic number 92 Types of Radioactive Waste NORM Naturally-occurring radioactive material (primarily uranium&thoriumSpecial Nuclear-Pu,U-233,or uranium enriched in the Material isotopes U-233 or U-235Low-level waste-not high-level radioactive waste,spent nuclear fuel,transuranic waste,or certain by-product material Landfill Decay Incinerate Supercompaction Hold for decay Sanitary sewerTable IIPOTW Mixed Waste RCRA/AEA Dual regulation EPA/State Conditional exemption Department ofEnergyQuestions?