POTENTIAL BIOGENIC CORROSION OF ALLOY 22, A CANDIDATE NUCLEAR WASTE PACKAGING MATERIAL, UNDER SIMULATED REPOSITORY CONDITIONS

摘要

The U.S. Department of Energy has been charged with assessing the suitability of a geologic nuclear wasternrepository at Yucca Mountain (YM), NV. Microorganisms, both those endogenous to the repository site and thosernintroduced as a result of construction activities, may contribute to the corrosion of metal nuclear waste packagingrnand thereby decrease their useful lifetime as barrier materials. Evaluation of potential Microbiological InfluencedrnCorrosion (MIC) on candidate waste package materials was undertaken in reactor systems incorporating thernprimary elements of the repository: YM rock (either non-sterile or presterilized), material coupons, and a continualrnfeed of synthetic YM groundwater. Periodically, both aqueous reactor efflux and material coupons were analyzedrnfor chemical and surfacial characterization. Alloy 22 coupons exposed for a year in reactors containing non-sterilernYM rock demonstrated accretion of chrome oxide and silaceous scales, with what appear to be underlying areas ofrncorrosion.