BWR Water Chemistry Transients and Crud-Induced Corrosion Fuel Failure Risk Assessment

摘要

BWR fuel has a long history of successful operationwith no crud and corrosion related fuel failures in theU.S. BWR fleet more than a decade. Although plant waterchemistry control has improved significantly, someunexpected transients still occur and impact plantoperation. This paper summarizes water chemistrytransient cases at FitzPatrick Nuclear Power Plant (JAF)due to severe condenser leaks and high feedwater (FW)metals input, at Columbia Generating Station (CGS) dueto Fe intrusion following on-line Residual Heat Removal(RHR) decontamination, and at Laguna Verde due toincreased feedwater (FW) Ni from erosion of nickelchromium alloy 75E and Inconel? coatings applied tohigh pressure turbine/moisture separator/reheater (MSR)cross-under piping to minimize flow acceleratedcorrosion (FAC). In these plant experiences, crudinducedfuel cladding corrosion was one of the concerns.EPRI’s CORAL software tool, which models the effects offuel duty and water chemistry variables on fuel cruddeposition and fuel integrity risk in BWRs, was utilized toassess crud-induced corrosion failure risk anddemonstrated adequate performance margin in thesecases, which is consistent with actual operation (i.e. noneof these cases had fuel failures).