ChlorideinducedstresscorrosioncrackingofcandidatecanistermaterialsfordrystorageofspentfuelOriginalResearchArticle

Susceptibilitytochlorideinducedstresscorrosioncracking(ESCC)ofcandidatecanistermaterials,UNSS31260andUNSS31254stainlesssteels(SS),wasinvestigatedbyaconstantloadtestinairattemperaturesof343and353Kwithrelativehumidity(RH)of35%,andat373KwithoutcontrollingRH.UNSS31260andUNSS31254SSdidnotfailuntil37,700hat353KwithRH=35%,whereUNSS30403SSfailedwithin250–500h.Thesametendencyalsowasobtainedat343K,suggestingthesuperiorESCCresistanceofUNSS31260andUNSS31254SS.Evenrustwasnotobservedonthespecimenstestedatthetemperatureof373K.ToexplainthehigherESCCresistance,thepittingpotentialwasmeasuredinthesaturatedsyntheticseawaterattemperaturesfrom303to353K,sinceESCCisusuallyassociatedwithlocalizedcorrosionsuchaspittingandmaybecloselyrelatedtothecorrosionresistance.ThepittingpotentialsofUNSS31260andUNSS31254SSweremuchhigherthanthatofUNSS30403SS.Thus,itwasconcludedthatthesuperiorESCCresistanceisattributabletothehigherresistanceofUNSS31260andUNSS31254SStopittingcorrosion.ThecriticalrelativehumidityforESCC,underwhichnoESCCoccurs,isequaltoorhigherthan15%attemperatures<353KjudgingfromESCCbehaviorofUNSS30400SS.