Short-termrupturestudiesofZircaloy-4andNb-modifiedZircaloy-4tubingusingclosed-endinternalpressurizationOriginalResearchArticle

BurstrupturepropertiesofZircaloy-4andNb-ModifiedZircaloy-4areinvestigatedattemperaturesrangingfrom638to843Kbyinternalpressurizationofclosed-endtubingsamples.Variouspressurizationlevelswereimposedandrupturetimeswerenoted.ThedataenabledanevaluationofLarson–MillerparameterandthepresentexperimentalresultsonZircaloy-4wereinexcellentagreementwiththosereportedintheliterature.Theeffectof1%NbadditiontoZircaloy-4wasstudiedsincethesematerialsarenowknowntoresistlong-timecorrosioninwaterreactorsandarethusconsideredforhighburn-upapplications.NegligibledifferenceswerenotedintherupturecharacteristicsbetweenthestandardZircaloy-4andNb-addedZircaloy-4.Inaddition,alimitedamountoftestingwasperformedtocharacterizethehoopcreepbehaviorofthesematerialsusingacreeptesterwithhoopstrainmonitoredinsitubyaLasertelemetricextensometer.Boththealloysfollowedanexponentialstressvariationofthecreep-rateathigh(>10−3E,Eistheelasticmodulus)stresses.Atverylowstresses,viscouscreepwasnotedidentifiablewithCoblecreepcorrespondingtosmallgrainsizedmaterials.