After a maintenance outage that ended up extended after workers found damaged reactor coolant pump bolts, unit 2 at PSEG’s Salem nuclear plant in New Jersey came back on line Monday.
Offline since April 12, the unit had reached 18 percent power as of Monday morning, according to the Nuclear Regulatory Commission (NRC).
Eight turning vane bolt heads ended up removed from RCP piping and the reactor pressure vessel. PSEG said it believes intergranular stress corrosion cracking weakened the bolts. Areva and Westinghouse inspected all four RCPs and made repairs using bolts with a different type of stainless steel.
The bolts were part of the original equipment at the Westinghouse reactor first licensed in 1981.
An NRC spokesman said the specific model of RCP affected only installed at the Salem and at the Surry plant in Virginia.
Earlier, NRC officials said PSEG discovered a smaller number of bolt heads at unit 2 during previous outages. In the most recent case, most damaged bolt heads ended up held in place even after they failed by mechanical restraints and tack welds.