Westinghouse fuel performance experience

Nuclear fuel reliability is among the highest priority items in the nuclear industry today. Despite having fuel reliability unsurpassed in the PWR industry, Westinghouse has an aggressive program to identify the efforts needed to achieve defect-free operation. This program consists of monitoring fuel performance, detailed on-site examinations to identify leakage causes, and implementation of corrective actions. These efforts have identified debris-induced fretting as the dominant leakage mechanism, accounting for approximately 70% of observed leaking rods. Corrective actions, consisting of training of site personnel and fuel assembly design changes, have been implemented to minimize the impact that debris can have on fuel integrity. Evaluations of data obtained from site examinations show several interesting trends. The size of debris wear scars has become smaller over the past several years, implying that debris in the system is becoming smaller. Also the majority of debris-induced fretting defects have been found to occur early in the fuel's operating life. This suggests that fuel rods have properties which make them more resistant to debris damage as burnup increases. The corrective actions implemented have been shown to be successful in reducing the occurrence of debris-related damage. Additional improvements are being developed to provide even further resistance to debris. (author). 8 figs 1 tab