【英文标准名称】:StandardPracticeforUseofaDichromateDosimetrySystem
【原文标准名称】:重铬酸盐剂量测定系统使用的标准规程
【标准号】:ASTMISO/ASTM51401-2003
【标准状态】:现行
【国别】:
【发布日期】:2003
【实施或试行日期】:
【发布单位】:美国材料与试验协会(US-ASTM)
【起草单位】:E10.01
【标准类型】:(ISO/ASTM)
【标准水平】:()
【中文主题词】:
【英文主题词】:ICS17.240;absorbeddose;absorbeddosemeasurements;dosimeter;dichromatedosimeter;dichromatedosimetrysystem;ionizingradiation
【摘要】:4.1Thedichromatesystemprovidesareliablemeansformeasuringabsorbeddoseinwater.Itisbasedonaprocessofreductionofdichromateionstochromicionsinacidicaqueoussolutionbyionizingradiation.4.2Thedosimeterisasolutioncontainingsilveranddichromateionsinperchloricacidinanappropriatecontainersuchasasealedglassampoule.Thesolutionindicatesabsorbeddosebyachange(decrease)inopticalabsorbanceataspecifiedwavelength(s)(3).Acalibratedspectrophotometerisusedtomeasuretheabsorbance.4.3EffectofIrradiationTemperature:4.3.1Thedosimeterresponsehasatemperaturedependenceduringirradiationthatisapproximatelyequalto-0.2%perdegreeCelsiusbetween25and50176;C.Attemperaturesbelow25176;C,thedependenceissmaller.Thedosimeterresponsebetween5and50176;CisshowninTable1,wheretheresponseatagiventemperatureistabulatedrelativetotheresponseat25176;C(4,5).4.3.2ThedatainTable1maybefittedwithanappropriateformulaforconvenienceofinterpolationasfollows:Rt5b01b1tb2(2)where:Rt=dosimeterresponseattemperaturetrelativetothatat25176;C.ThecurvegeneratedfromthefitteddataisshowninFig.1.4.4Noeffectofambientlight(evendirectsunlight)hasbeenobservedondichromatesolutionsinglassampoules(6).4.5Forcalibrationwithphotons,thedichromatedosimetershallbeirradiatedunderconditionsthatapproximateelectronequilibrium.4.6TheabsorbeddoseinmaterialsotherthanwaterirradiatedunderequivalentconditionsmaybecalculatedusingtheproceduresgiveninASTMPracticesE666,E668andISO/ASTMGuide51261.4.7Thedosimeterresponseisdependentonthetypeandenergyoftheradiationemployed.Forexample,theresponseinhighenergy(10MeV)electronbeamsisreportedtobeapproximately3%lowerthantheresponseincobalt-60radiation(2).Thedosimetershallbecalibratedinaradiationfieldofthesametypeandenergyasthatinwhichitistobeused.4.8Providedthedosimetersolutionispreparedasdescribedinthisdocument,andstepsaretakentoavoidcontamination,thedosimetersolutionstoredorsealedinglassvessels(forexample,ampoules)isstablebeforeandafterirradiation.1.1Thispracticecoversthepreparation,testing,andprocedureforusingtheacidicaqueoussilverdichromatedosimetrysystemtomeasureabsorbeddoseinwaterwhenexposedtoionizingradiation.Thesystemconsistsofadosimeterandappropriateanalyticalinstrumentation.Forsimplicity,thesystemwillbereferredtoasthedichromatesystem.Itisclassifiedasareferencestandarddosimetrysystem(seeISO/ASTMGuide51261).1.2Thispracticedescribesthespectrophotometricanalysisproceduresforthedichromatesystem.1.3Thispracticeappliesonlyto947;-rays,x-rays/bremsstrahlun,andhighenergyelectrons.1.4Thispracticeappliesprovidedthefollowingconditionsaresatisfied:1.4.1Theabsorbeddoserangeisfrom2X103to5X104Gy.1.4.2Theabsorbeddoseratedoesnotexceed600Gy/pulse(12.5pulsespersecond),ordoesnotexceedanequivalentdoserateof7.5kGy/sfromcontinuoussources(1).1.4.3Forradionuclidegamma-raysources,theinitialphotonenergyshallbegreaterthan0.6MeV.Forbremsstrahlungphotons,theinitialenergyoftheelectronsusedtoproducethebremsstrahlungphotonsshallbeequaltoorgreaterthan2MeV.Forelectronbeams,theinitialelectronenergyshallbegreaterthan8MeV.Note18212;Thelowerenergylimitsgivenareappropriateforacylindricaldosimeterampouleof12mmdiameter.Correctionsfordisplacementeffectsanddosegradientacrosstheampoulemayberequiredforelectronbeams(2).Thedichromatesystemmaybeusedatlowerenergiesbyemployingth......
【中国标准分类号】:
【国际标准分类号】:17_240
【页数】:6P.;A4
【正文语种】: