PSEG Nuclear’s 1,232-MW Salem-2 in Hancocks Bridge, New Jersey, connected to the grid at 6:35 a.m. Monday after shutting down July 4.
The incident occurred when the control room received an intermittent alarm indicating a possible electrical fault or short, company spokesman Joseph Delmar said.
The unit was operating at 18 percent capacity Monday after operating at 12 percent capacity Sunday, the Nuclear Regulatory Commission (NRC) said in daily reactor status reports.
The unit had shut at 4:23 a.m. when an electrical short caused the main generator protection signal to activate and automatically trip the main turbine. The short occurred because water entered a duct system that runs between the generator and main power transformer.
The reactor connected to the grid at 2:04 p.m. July 3 and reached 82 percent capacity early in the afternoon of July 4. But a power reduction began following the control room receiving the intermittent alarm, and the turbine and generator went offline at 11:22 p.m. July 4.
Delmar said the cause of the intermittent alarm could “not be fully determined. We entered our operational decision-making process and have put additional monitoring in place to observe for additional faults.”
The 1,254-MW Salem-1 has been shut since April 14. The unit shut for a refueling and maintenance outage, and a visual inspection of a number of baffle-former bolts found some boltheads were missing and others were protruding. Delmar said June 29 ultrasonic testing to assess the condition of more bolts and repairs were underway and that PSEG is “not commenting further on the status until the plant safely returns to service.”
The nearby 1,240-MW Hope Creek-1 was operating at 100 percent capacity Monday morning, according to the NRC.