輻射安全常識(shí)課件

PrinciplesofRadiation

IndustrialStudies4020TopicsinIndustrialStudiesEnvironmentalSafetyManagementAtomicnumber

Atomicmass

NumberofProtonsONLYNumberofProtons&Neutrons (weight)

C1412ChemicalSymbolAtomicMassAtomicNumberReviewSo,whatisit?H3Hydrogen–3containsoneproton+twoneutrons.

It’saradioactiveisotopeofhydrogenalsoknown

astritiumIsotopesSamenumberofprotons;differentnumberofneutrons

SamechemicalpropertiesDifferentnuclearpropertiesHydrogen1ProtonDeuterium1Proton,1Neutron*Tritium1Proton,2NeutronsH11*Note:TritiumisRadioactiveHH2131RadioactivityAtomswithtoomanyneutronsorprotonsareunstableandemitenergytobecomemorestable.

Energyiscarriedawaybya-/b-particle

orx-/g-ray.

Theseatomsarecalledradioactive

andtheprocessiscalledradioactivedecayRadioactivityNaturalUraniumThoriumPotassium-40Carbon-14(C-14)Hydrogen-3(H-3)(tritium)ManmadePhosphorus-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)BackgroundRadiation

mrem/yrCosmic 27Terrestrial 28Inhaled 200Internal 39Man-made 63

Total:

357RadiationMicrowavelightbulbcellphoneUVlampradio/TVlaserheatlampx-raysEmission/propagationofenergythroughspaceormaterialmediumaswavesorparticlesIonizingRadiationAlphaParticles2Protons+2Neutrons

ShortRangeinAir

NotanExternalHazard

InternalHazard

BetaParticlesNegligibleMass

LongRangeinAir

Internal/ExternalHazardCharged

GammaRays/PhotonsGammaphotons&X-Raybothelectromagnetic

differonlybyplaceoforigin

Nomassorcharge

Highly-penetratingNeutronsVeryLongRange

VeryPenetrating

DifficulttodetectOthermodesofDecayPositronemissionElectroncaptureFissionElectronActivityDecayisastatisticalprocess.Cannotpredictwhenaparticularatomwilldecay.

Can

predictwhencertainamount(%)willhavedecayed.UnitsofActivity

Curie

(Ci)1Ci=37,000,000,000dps(3.7x1010dps)or

1Ci=2.22x1012dpm

Becquerel

(Bq)1Bq=1dps1Ci=37,000,000,000Bq=37GBq(GigaBecquerel)Quantities&UnitsBetaandgammaradiationaboutequallydamaging:1R=1rad=1remAlpharadiationcausesgreatercellulardamage1radofa=20remDecayRate

Half-life,

A=A0e0.693t/T?

A=A0(?)#ofhalf-livesNon-IonizingRadiationQuestions?Radiation

Safety

IndustrialStudies4020TopicsinIndustrialStudiesEnvironmentalSafetyManagementRadiationHazardsExternalHazard(exposurefromoutsidethebody)High-energybeta(i.e.,energy>300keVor>0.3MeV)GammaandX-raysNeutronsInternalHazardRadioactivematerialentersbodybyeating/drinkinginradiationarea,bybreathingvapors/aerosols,orskinabsorptionInbody,itistreatedlikenon-radioactiveelementsIfnotincorporatedintoorgan,rapidlyexcretedandmay

poseonlyslighthazardIfstoredinorgan,slowlyexcreted(effectivehalf-life)AcuteBiologicalEffectsWholebody,externalacute

exposureeffects25radsomechromosomeaberrations50radminorbloodchanges100rad2%radiationsickness400rad50%diein60days

(LD50/60)700radlethalsingleexposure6000radcancertherapy(local)

LowDoseBiologicalEffectsALARA

As

LowAsReasonablyAchievable

Benefitsoutweighrisks?

LowerDose=

LowerRiskWholebodybadge(TLD)CollarorRingTLDBioassay--thyroid(iodine)urinalysis(tritium)

MonitoringWorkersOccupationalExposureLimitsNottoExceedmrem/yr rem/yrmSv/yr5,000 550

15,000 15150

50,000 50500

50,000 50500AccumulatedDoseEquivalentto:WholeBody

LensoftheEye

SkinofWholeBody

ExtremitiesofWholeBody--Hands,Feet,etcGeneralSafetyMeasuresTIMEExposureincreaseswithtime

SHIELDINGPlasticforbetaLeadforgamma

DISTANCEExposuredecreases

withdistancevTimevsExposureIncreasedexposure(risk)

overtime

Linear

3mR/hr*4hr=???DistancevsExposure

I1d12=I2d22

Exposure&ShieldingThick,dense

(i.e.,lead)forgamma/x-rays

Plasticbeta

Hydrogeneous

(orboron+cadmium)forneutronsNoshieldingneededforalphaorlow-energybetaDetectors/MonitorsDetectors/Monitors1) CapableofDetecting

2) Efficiency

3) CalibrationIndustrialUsesofRadiation/rpdweb00/source-reduction-management/applications.htmlIndustrialUsesofRadiationLasersX-rays

GaugesWirelessexitsigns

X-rayFluorescence

(XRF)

IndustrialUsesofRadiation/rpdweb00/source-reduction-management/applications.htmlMoisture/densitygauges

RadiographyStaticcontrol

SmokedetectorsEmergencyResponse

LifesavingandseriousinjurytakeprecedenceoverradiationexposureandcontaminationControlAccesstoAreaCallforHelpRadioactive

Waste

IndustrialStudies4020TopicsinIndustrialStudiesEnvironmentalSafetyManagementTypesofRadioactiveWaste

SpentFuel-Withdrawnfromanuclearreactor

followingirradiation

High-levelwaste-Highlyradioactivematerialfrom

reprocessingspentnuclearfuel

Transuranic-Man-madeelementsabove

atomicnumber92

TypesofRadioactiveWaste

NORM

–

Natural