RadiationTrainingCourse核輻射基礎(chǔ)知識

（優(yōu)選）RadiationTrainingCourse核(He)輻射基礎(chǔ)知識第一頁，共五十四頁。天(Tian)然輻射RadiationistheemissionofenergyfromanatomintheformofeitheranelectromagneticwaveoraparticletravellingathighspeedTheatomemitsthisenergytoreachamorestable(i.e.lowerenergy)state輻射是原子通過發(fā)射電磁波或粒子而釋放能量的過程。原子通過釋放能量從而達(dá)到穩(wěn)定的狀態(tài)。

第二頁，共五十四頁。原(Yuan)子AnAtomhasanucleusaroundwhichelectronsorbit原子由原子核與核外電子構(gòu)成NucleusElectron第三頁，共五十四頁。原(Yuan)子(2)Thenucleuscontainsneutronsandprotons原子核包含中子與質(zhì)子NeutronProtonElectron第四頁，共五十四頁。原(Yuan)子(3)Theprotonseachcarryapositive(+)chargeTheneutronsareneutral(nocharge)質(zhì)子帶一個單位正電荷，中子不帶電，而電子帶一個單位負(fù)電荷。NeutronProtonElectron++Theelectronseachcarryanegative(-)charge,sotheatomisneutraloverallsincethenumbersofneutronsandelectronsareequal第五頁，共五十四頁。原(Yuan)子(4)Thenumberofprotonsistermedtheatomicnumber,ZThenumberofneutronsandprotonsistermedthemassnumber,A質(zhì)子數(shù)決定原子序數(shù)Z，中子和質(zhì)子數(shù)之和決定質(zhì)量數(shù)AInthisexample,thereare2protons,sotheatomicnumberis2Therearealso2neutrons,sothemassnumber,A

is4第六頁，共五十四頁。原(Yuan)子(5)Theatomicnumber,Zdependsonthechemicalelement原子序數(shù)Z決定元素的化學(xué)性質(zhì)Z=1Z=3Z=2HydrogenHeliumLithiumHHeLi第七頁，共五十四頁。同位(Wei)素(1)Isotopesareatomsofthesamechemicalelement(sameatomicnumber,Z),butwithdifferentnumbersofneutrons(differentmassnumber,A),forexample,isotopesofhydrogen,HZ=1Z=1Z=1HydrogenDeuteriumTritium1H2HA=1A=3A=23H第八頁，共五十四頁。同位(Wei)素(2)Isotopesarewritten:Asthenameofthechemicalelement,followedbytheMassNumber(A),e.g.Uranium-235Or

U23592Symbolforchemicalelement

AtomicNumber,ZMassNumber,A第九頁，共五十四頁。TypesofAtomicRadiationAlphaparticle(α)Betaparticle(β)Gammaradiation(γ)NeutronsThereareothertypesofradiationbuttheyarebeyondthescopeofthistrainingcourse第十頁，共五十四頁。AlphaParticlesAnα-particleisanucleusofaheliumatom,ejectedathighspeedbydisintegrationofthenucleusofalarger(heavier)atomItconsistsof2neutronsand2protonsItcarriesadoublepositivechargeα粒子是由重核衰變產(chǎn)生的，由2個中子與2個質(zhì)(Zhi)子組成，帶2個單位正電荷。++He42α第十一頁，共五十四頁。BetaParticlesAβ-particleisanelectronejectedathighspeedfromadisintegratingatomItcarriesasinglenegativechargeβ粒子是(Shi)由原子核產(chǎn)生的高速電子，帶1個單位負(fù)電荷-β0-1第十二頁，共五十四頁。GammaRadiationAγ

-rayisapulseofhighfrequencyelectromagneticradiationejectedfromthenucleusofadisintegratingatomItcarriesnoelectricalcharge

γ射線是由原子核衰變產(chǎn)生的高能電(Dian)磁波，不帶電(Dian)γ第十三頁，共五十四頁。X-RadiationAnX-rayisapulseofhighfrequencyelectromagneticradiationejectedfromanatomwhenanorbitalelectrondropsfromahigh-energy(‘excited’)statetoalower-energystateItcarriesnoelectricalchargeX射線是核外電子由高能態(tài)躍遷到低能態(tài)時產(chǎn)生的電磁(Ci)波，不帶電第十四頁，共五十四頁。NeutronsNeutronsareemittedfromthenucleusasaresultofradioactivedecayofsomeunstableatoms:‘Fissionproducts’formedjustafteraheavyatom,suchasUranium,hasbeensplit(‘fissioned’)ThisoccursmainlyinnuclearreactorsandatomicweaponexplosionsSomeveryheavyisotopesshowaprocessknown‘spontaneousfission’;theyemitneutrons(examplesareplutonium-240,andcalifornium-252)Certainradioisotopesourcesaredesignedtoemitneutrons,forexampleamericium-241mixedwithberylliumNeutronscarrynoelectricalcharge中子是不穩(wěn)定的原(Yuan)子核衰變時產(chǎn)生的，不帶電第十五頁，共五十四頁。輻射的穿(Chuan)透性(1)Alphaparticlesarenotverypenetrating.Theyarestoppedby:Afewcm/2–3inchesofairAsheetofpaperorathinfoilofaluminiumThedeadlayerofhumanskinHOWEVERAlphaparticlesinsidethebodydepositalloftheirenergyinaverysmallvolumeofhumantissueInthissituation,theyareabout20timesmoredamagingthanγ-radiationAlpha粒子的穿透能力很弱，一張紙或人的皮膚就可以阻止Alpha粒子，空氣中的射程也只有幾個cm.但是，Alpha粒子在人體組織中的內(nèi)照射危害約是Gamma射線的20倍。第十六頁，共五十四頁。輻射的穿透(Tou)性(2)Beta(β)particlesaremorepenetratingthanα-particlesTheyarestoppedby:Severalfeetofair(range~12feet/MeVβ-particleenergy)Afewcm(~2”)ofaluminiumorafewmm(~?”ofsteel)β-particlescanirradiatethegrowinglayersofhumanskinPlasticandaluminiumareusefulshieldingmaterialsBeta粒子的穿透性比Alpha粒子強(qiáng)。Beta粒子可以穿透人的皮膚，其在空氣中的射程約幾十cm,在鋁中的射程為幾個cm。通常我們用塑料或鋁來屏蔽Beta粒子。第十七頁，共五十四頁。輻射的穿(Chuan)透性(3)Gamma(γ)andX-raysareverypenetratingTheycantravellongdistances(miles)inairandothermaterialsTheyarenotabsorbedcompletely,buttheirintensitycanbegreatlyreducedby:20feet(6metres)ofwaterSeveralfeet(2-3m)ofconcrete4”(10cm)ofleadγ-radiationpassesthroughthehumanbodyGamma射線和X射線的穿透能力很強(qiáng)，其在空氣中的射程可達(dá)幾公里，在鉛中的射程達(dá)幾個cm，可以穿過人體。通常用鉛來屏蔽Gamma射線。第十八頁，共五十四頁。輻(Fu)射的穿透性(4)Neutronscantravelhundredsofyards(~km)inairTheyrequirespecialshieldingusingmaterialscontaininglightelements,suchashydrogen,orcertainelementsthatabsorborscatterneutrons.Examples:Water,HeavyWater,Polyethylene,cadmium,concrete中子在空氣中的射程可達(dá)數(shù)公里，通常用輕核素來屏蔽中子，例如水，塑料，水泥等。第十九頁，共五十四頁。輻射的(De)穿透性(5)PaperPlasticorAluminiumSteel,leadorconcreteαβγ第二十頁，共五十四頁。輻射與放(Fang)射性RadiationisthestreamofparticlesorraysbeingemittedbyasourceofradioactivityRadioactivityistheprocessofgivingoffradiation輻射是放射源發(fā)射出粒子或射線束，放射性是發(fā)出輻射的過程SourceRadiation第二十一頁，共五十四頁。放(Fang)射性衰變(1)RecallthattheatomicnucleuscontainsneutronsandprotonsNeutronProtonElectron第二十二頁，共五十四頁。放射性(Xing)衰變(2)Byemittinganα-particleNucleusloses2protons+2neutronsByemittingaβ-particleNucleusgainsaprotonByemittingaseriesofα-particlesand

β-particles,thenucleuscanachievethemoststableconfigurationParentNucleus‘Daughter’Nucleusα-particle第二十三頁，共五十四頁。RadioactiveDecayofUranium-238第二十四頁，共五十四頁。半衰(Shuai)期Thehalf-lifeofaradioisotopeisthetimetakenforhalfoftheatomsinasampletohavedecayedThehalf-lifecanvaryoverahugerange;itisfixedforaparticularradioisotope.Theshorterthehalf-life,themore‘a(chǎn)ctive’thesamplewillbe半衰期是指樣品中放射原子數(shù)量從開始衰變到一半時所用的時間。TypicalRadioactiveHalf-LivesUranium-2384.5billionyearsCarbon-145730yearsRadium-2261600yearsCaesium-13730yearsCobalt-605.3yearsPolonium-210138daysPhosphorous-302.55minutesHelium-60.82seconds第二十五頁，共五十四頁。放射性衰(Shuai)變圖第二十六頁，共五十四頁。放射(She)性單位1Becquerel(Bq)=1disintegrationpersecondAVERYSMALLQUANTITYSIUnits1Curie(Ci)=37billiondisintegrationspersecond=37billionBecquerels(37GBq)ANENORMOUSQUANTITY!USUnits第二十七頁，共五十四頁。RelativeMagnitudesofNumbersNUMBERSGREATERTHAN1NUMBERSLESSTHAN110121,000,000,000,000teraT10-10.1decid1091,000,000,000gigaG10-20.01centic1061,000,000megaM10-30.001millim1031,000kilok10-60.000001microμ102100hectoh10-90.000000001nanon10011110-120.000000000001picop第二十八頁，共五十四頁。輻射(She)能量αandβparticles,andγ-andX-radiationcanbeemittedwithdifferentenergies,dependingonthenucleustheyoriginatedinTheseenergiesarecharacteristicoftheisotopeoforiginα

或β

粒子,γ或X射線的能量是由放射性核素決定的。Withspecialinstrumentation,thisfeaturecanbeusedtoidentifytheisotopespresentinanunknownradioactivesampleTheenergyofaparticleorradiationismeasuredinelectronvolts(eV),withprefixesofkilo(x1000)ormega(x1,000,000)

hencekeV,MeV,etc.Thehighertheenergy,thefastertheparticleistravellingandthemorepenetratingtheradiation第二十九頁，共五十四頁。UnitsofRadiation:Radiation‘Dose’As,ittravelsthroughair,oranyothermedium,abeamofradiation,oraradiationparticle,losessomeorallofitsenergybytransferringittothemediumJustas,forexample,amicrowaveovenradiatesmicrowaveswhichareabsorbedbysomethingyouwanttocook,raisingthetemperature第三十頁，共五十四頁。UnitsofRadiation:Radiation‘Dose’(2)Theenergytransferredtotheair,orothermaterialthattheradiationtravelsthrough,causesariseintemperaturewhichcanbemeasured,althoughitisverysmallThisENERGYABSORBEDbythematerialistermedtheABSORBEDDOSEUnits (USA): Rad RadiationAbsorbedDose (SI): Gray (Gy) 1Gy=100rads=100cGy第三十一頁，共五十四頁。UnitsofRadiation:Radiation‘Dose’(3)TheintensityofaradiationbeamistherateatwhichenergyisdeliveredThisistheabsorbeddoseperunitoftime,orDOSERATEUsually,thisisexpressedasdoseperhour,butBEWARE!insomeaccident,medicalormilitarysituations,weusedoseperSECONDABSORBEDDOSERATE:DOSE/TIME

1Gy/h=100rads/h=100cGy/h第三十二頁，共五十四頁。UnitsofRadiation:Radiation‘Dose’(4)Thusfar,wehavebeenconsideringabsorbedradiationdoseinAIR,oranotherMEDIUMHowever,wearemoreinterestedinmeasuringthesignificanceofradiationtohumansTheabsorbeddoseismultipliedbyaweightingfactor

whichtakestheestimatedbiologicaleffectoftheabsorbedradiationintoaccountThisnewquantityisknownasWhataboutremsandSieverts?DOSEEQUIVALENT第三十三頁，共五十四頁。UnitsofRadiation:DoseEquivalentDOSEEQUIVALENTHABSORBEDDOSE,DxQUALITYFACTOR,Q第三十四頁，共五十四頁。UnitsofRadiation:DoseEquivalent(2)DxQ

=HGyxQ=SvradxQ=rem第三十五頁，共五十四頁。UnitsofRadiation:DoseEquivalent(3)DxQ=HGyxQ=SvradxQ=remQUALITYFACTORS:X-RAYS,BETA,GAMMA 1Alpha 20ForX-RAYS,BETA,GAMMA:1Gy=1Sv=100rem第三十六頁，共五十四頁。Whyareweconcernedaboutradiation?Whyareweconcernedaboutradiation?第三十七頁，共五十四頁。放射性(Xing)對人的影響Photo:USDoD/DoEPublicDomainCANCERSTERILITYMUTATIONSRADIATIONSICKNESS第三十八頁，共五十四頁。輻射的生(Sheng)物效應(yīng)(1)RADIATIONCAUSESIONIZATIONCellNucleusγ-ray+-+-OH.H.輻射引起細(xì)胞的DNA鏈斷裂，產(chǎn)生自由基第三十九頁，共五十四頁。輻射(She)的生物效應(yīng)(2)DamagedCellDamagedcelldiesCellrepairsitselfDamagedcellreplicatesMUTATION第四十頁，共五十四頁。輻射的(De)生物效應(yīng)(3)EARLYEFFECTSTemporarychangeinbloodcount臨時改變血球計(jì)數(shù)Sterility不育癥Nausea&Vomiting惡心和嘔吐Radiationburns輻射灼傷AcuteRadiationSyndrome急性輻射綜合癥Death死亡DELAYEDEFFECTSCataracts白內(nèi)障Leukaemia,othercancers白血病，其他癌癥Lifeshortening壽命縮短Geneticeffects遺傳效應(yīng)Hormesis(improvedhealth)興奮效應(yīng)（改善健康）Nothingatall無影響第四十一頁，共五十四頁。輻射的生物(Wu)效應(yīng)(4)Radiationhasthegreatesteffectonthosepartsofthebodywherecellsaredividingquickly:SexorgansStomachliningSkin輻射對性器官，胃，皮膚等影響較大Radiationhaslesseffectonthoseorganswherecellsarerenewedmoreslowly:MuscleBoneNerve輻射對肌肉，骨骼，神經(jīng)等影響較小第四十二頁，共五十四頁。Whathappenswithveryhighradiationdoses?Dose(Sv)SurvivalTimeModeofDemise550%chanceofsurvival5to10Weeks-monthsInfection感染10to100Days-weeksGastrointestinalcollapse胃腸道塌陷>100Hours-daysCentralNervousSystemFailure中樞系統(tǒng)衰竭第四十三頁，共五十四頁?！璦ndatslightlylowerdoses?Dose(Sv)Effect0.15Temporarysterility暫時不育0.5Cataractformation白內(nèi)障的形成3Erythema(skinreddening)，Hairloss紅斑（皮膚發(fā)紅），脫發(fā)5Drydesquamation干性脫皮10to20Moistdesquamation濕性脫皮第四十四頁，共五十四頁。HealthEffectsversusRadiationDose0.11101001,00010,000mSv101001,00010,000100,0001,000,000mremNote:thisscaleisinmilliSieverts(mSv);toconvertthistomicroSieverts(μSv),multiplyby1,000(add3zero’s)ormultiplymilliremscaleby10(add1zero)AnnualdoselimitforamemberofthePublicinEUAverageannualdosefromnaturalbackgroundradiationAnnualdoselimitforaradiationworkerinEU5-yeardoselimitforaradiationworkerinEUChangesinbloodcountvisibleafterasingledoseClinicalsymptomsofearlypathologyLethaldosebeyondtherapy*Typicaldosefromatrans-Atlanticcommercialflight第四十五頁，共五十四頁。RadiationDosesfromVariousSourcesTypicaldistributionofaverageindividualexposureTotal2to3mSv/person/yearSource:AREVA第四十六頁，共五十四頁。ExamplesofNaturalRadioactivityRain