NRC Investigates Two Hiccups At Perry NPP

The Nuclear Regulatory Commission (NRC) said Monday it had launched a special investigation into two recent events at the Perry Nuclear Plant involving a manual shut down on Feb. 8 and a temporary loss of power on Feb. 11, while the reactor was shut down.

Perry NPP“On Feb. 8, operators manually shut own the reactor when they observed an increase of the temperature in the suppression pool,” the NRC said.

The suppression pool is designed to condense steam and is a source of water used in emergency cooling systems. The NRC said that the Feb. 11 loss of power involved “certain plant cooling equipment.”

Operators were able to use a redundant system and restore power to the cooling systems.

The Feb. 8 and Feb. 11 events are not related, said NRC Region III Administrator Cynthia Pederson. Still, “our team of specialists in reactor operations and electrical equipment will review the technical details to better understand what happened,” she said.

Perry, managed by FirstEnergy Nuclear Operating Company, is a 1,260-MW General Electric Type 6 boiling water reactor (BWR) 35 miles northeast of Cleveland that has been in operation since November 1986.

FirstEnergy reported a “spurious” set of signals from pressure and temperature monitors that prompted automated valves in high-pressure steam lines to open. This diverted high-temperature steam on route to the plant's turbines to a condenser, which allows the steam to cool down and convert back to water.

But the temperature of the condenser suppression pool water was predicted to rise, which prompted operators to shut down the reactor, reported

FirstEnergy spokeswoman Jennifer Young said the plant operators reacted “conservatively,” as they should have.

Engineers later said that air in the instrument line triggered the steam diversion by giving a false reading of high pressure in the line.

The second shut down came on Feb. 11, when there was a brief electrical shut down to electric pumps that feed coolant water to the reactor. A redundant system was activated and plant technicians were looking into the cause of that electrical hiccup.

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