Aging and life extension assessment of component cooling water systems

An aging assessment of component cooling water systems in pressurized water reactors was performed as part of the Nuclear Regulator Commission's Nuclear Plant Aging Research (NPAR) program. Failure data from national data bases were analyzed and predominant failure modes, causes and mechanisms were identified. Plant specific data were also obtained to supplement and validate the data base results. Time-dependent failure rates calculated from the data show a trend toward increasing with age. Using these failure rates in probabilistic risk assessment type analyses, changes in component relative importance and system unavilability with age were observed. These findings are discusses in relation to plant life extension