Nuclear, O&M, Reactors

Limerick nuclear unit offline

Caption: Exelon’s Limerick nuclear power plant, located in Pennsylvania.

Unit 1 of the Limerick nuclear power plant in Pennsylvania was shut down Monday night after a high-pressure signal went off.
According to a report filed with the U.S. Nuclear Regulatory Commission, the reactor high-pressure signal was caused by the closure of a valve on one of the plant’s main steam lines. The valve closing caused the reactor pressure to rise, exceeding the reactor protection system. The closure of the valve seems to have been caused by a loss of primary containment instrument gas pneumatic supply to the valve, but workers are investigating the cause.
Safety equipment and workers with plant operator Exelon (NYSE: EXC) responded. Unit 2 was not affected.
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