PredictionoftheperformanceofanionchamberamplifierunderγradiationOriginalResearchArticle

Theionchamberamplifier(ICA)playsamajorroleintheproperfunctioningofanuclearreactorasitmonitorstheradiationsfromthenuclearreactorbymeasuringtheionicactivityinsidetheionchamber.ThesignalconditioningcircuitryoftheICAdetectsandconditionstheweakioniccurrentscomingfromtheionchamberdome.DegradationintheperformanceofthesemiconductordevicesusedinthispartoftheICA,canleadtoinaccuratemonitoringofthereactoroperation,resultinginapossiblecatastropheduetomalfunction.Further,theresponseoftheICAunderirradiationalsodependsuponthestrengthoftheinputsignal(ionic)currentitisrequiredtohandle.TheactivedevicesusedintheICAunderstudyareoperationalamplifiers(Op-Amps)suchasDN8500AandOPA111,instrumentationamplifierINA101,transistor2N2920Aandavoltagereferencedevice,AD584.Sincethesedevicesmaybesensitivetoradiation,onemustknowtheirradiationbehavioursothattheperformanceoftheICAcanbepredicted.ThispaperexaminestheperformanceoftheICAbycharacterisingtheradiationprofilesofitsvitalcomponents,viz.theOp-Amps,instrumentationamplifiers,transistors,etc.bymonitoringtheirparametricchangeson-line,i.e.whenthesourceison,andthedevicesarebiased.ThesimulationrunsinvolvethesimulationoftheentireICAcircuitryusingthechangedvaluesofthevitalparameterssuchasinputbiascurrentandinputoffsetvoltage.ThemainadvantageofthismethodisthatitobviatesirradiatingthewholeICAcircuittostudyitsirradiationperformance,andsimulatesanenvironmentofradiationleakagearoundtheICA.Basedonthisstudy,resultsarepresentedtopredicttheperformanceoftheICA.