EPRI perspective: nuclear plant life extension

In 1978-1979, the Electric Power Research Institute (EPRI) undertook a series of studies that suggested that extending the operation of current nuclear generating units beyond their nominal 40-yr licensing term was both technically feasible and economically attractive. In 1985 more detailed evaluations were initiated as part of a joint EPRI/US Department of Energy program plan to culminate in the licensing of a generating unit(s) for extended life. One focus of this effort is two intensive pilot evaluations, by and with utilities, to provide guidelines for such achievement. One pilot study is by Virginia Power (Surry Unit 1, a pressurized water reactor); the second is by Northern States Power (Monticello, a boiling water reactor). The pilot studies were initiated by identification of components potentially critical to life extension; e.g. major components, such as the reactor pressure vessel, whose costs and outage time for replacement might severely inhibit life extension. The programs are currently performing life assessments of these components using fitness for service approaches deriving from the ASME Boiler and Pressure Vessel Code Section XI