辐射安全常识ppt课件.ppt

Principles of Radiation Industrial Studies 4020Topics in Industrial StudiesEnvironmental Safety Management•Atomic number Atomic massNumber of Protons ONLY Number of Protons & Neutrons (weight)• C1412Chemical SymbolAtomic MassAtomic NumberReviewSo, what is it ? H3Hydrogen – 3 contains one proton + two neutrons. It’s a radioactive isotope of hydrogen also known as tritiumIsotopes•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 RadioactiveHH2131Radioactivity•Atoms with too many neutrons or protons are unstable and emit energy to become more stable.•Energy is carried away by a- / b-particle or x- / g-ray.•These atoms are called radioactive and the process is called radioactive decayRadioactivity•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)Background Radiationmrem/yrCosmic 27Terrestrial 28Inhaled 200Internal 39Man-made63Total: 357RadiationMicrowave light bulbcell phone UV lampradio / TV laserheat lamp x-raysEmission / propagation of energy through space or material medium as waves or particlesIonizing RadiationAlpha Particles2 Protons + 2 NeutronsShort Range in AirNot an External Hazard Internal HazardBeta ParticlesNegligible MassLong Range in AirInternal/External HazardChargedGamma Rays/PhotonsGamma photons & X-Ray both electromagnetic differ only by place of origin No mass or chargeHighly-penetratingNeutronsVery Long RangeVery PenetratingDifficult to detectOther modes of Decay•Positron emission•Electron capture•Fission•ElectronActivity•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 dps1 Ci = 37,000,000,000 Bq = 37 GBq (Giga Becquerel)Quantities & Units•Beta and gamma radiation about equally damaging:• 1 R = 1 rad = 1 rem•Alpha radiation causes greater cellular damage• 1 rad of a = 20 remDecay Rate Half-life, A= A0 e 0.693t/T½A = A0 (½)# of half-livesNon-Ionizing RadiationQuestions?RadiationSafety Industrial Studies 4020Topics in Industrial StudiesEnvironmental Safety ManagementRadiation Hazards•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)Acute Biological EffectsWhole 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) Low Dose Biological EffectsALARAAs Low As Reasonably Achievable Benefits outweigh risks? Lower Dose = Lower Risk•Whole body badge (TLD)•Collar or Ring TLD•Bioassay -- thyroid (iodine)•urinalysis (tritium)• Monitoring Workers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General Safety Measures•TIME•Exposure increases with time•SHIELDING•Plastic for beta•Lead for gamma• • DISTANCE•Exposure decreases with distance•vTime vs ExposureIncreased exposure (risk)over time Linear3 mR/hr * 4 hr = ???Distance vs Exposure I1d12 = I2d22 Exposure & ShieldingThick, dense (i.e., lead) for gamma / x-raysPlastic betaHydrogeneous (or boron + cadmium) for neutronsNo shielding needed for alpha or low-energy betaDetectors/ MonitorsDetectors/ Monitors1)Capable of Detecting 2)Efficiency3)Calibration Industrial Uses of Radiationepa.gov/rpdweb00/source-reduction-management/applications.htmlIndustrial Uses of RadiationLasersX-raysGaugesWireless exit signs X-ray Fluorescence(XRF) Industrial Uses of Radiationepa.gov/rpdweb00/source-reduction-management/applications.htmlMoisture/density gaugesRadiographyStatic controlSmoke detectorsEmergency Response•Lifesaving and serious injury take precedence over radiation exposure and contamination•Control Access to Area•Call for HelpRadioactiveWaste Industrial Studies 4020Topics in Industrial StudiesEnvironmental Safety ManagementTypes 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 Solid Waste LandfillDecay IncinerateSupercompactionLSC Vial Waste• Aqueous Waste•Hold for decay•Sanitary sewerTable IIPOTW• Mixed Waste•RCRA/AEA – Dual regulation•EPA/State Conditional exemption•Department ofEnergyQuestions?。