The Salem 2 nuclear plant in southern New Jersey is now offline after a leak of low-level radioactive water developed during routine testing of an emergency cooling system.
Plant operator PSEG Nuclear said the incident last Thursday posed no threat to plant workers or the public.
About 90 gallons of water leaked from a valve into the auxiliary building next to the reactor containment building, said company spokesman Joe Delmar. They collected the water through the floor drain system. Officials will process it through the radioactive waste system at the plant.
Workers were performing a routine monthly venting of the emergency core cooling system’s high head safety injection piping when they discovered a leak on an opened valve. A possible crack on a weld on the motorized valve was the cause of the leak, officials said.
Over a 6-minute period, before closing the valve, about 90 gallons of water leaked into the auxiliary building next to the reactor containment building at a rate of between 11 and 15 gallons per minute. Operating rules allow water leakage of up to 10 gallons per minute, but since this leak exceeded this amount, they declared an unusual event. The leak also caused the pressure in the system to drop.
Operators declared the system temporarily inoperable and began to power down the plant, eventually taking it offline.
Salem 2 has two high head safety injection pumps. They are part of the plant’s emergency core cooling system which they would use in the event of a loss of coolant from the reactor’s main coolant system.
During an accident, it would be one of the systems that would pump borated water into the reactor vessel to ensure the nuclear fuel inside remained covered with water and cooled. The system gets water initially by 8,000-gallon boric acid makeup tanks and there is a backup 400,000-gallon refueling water storage tank.
Routine tests of the emergency core cooling the systems occur monthly to ensure they are operational in the event other systems failed.
The incident prompted officials to declare an unusual event — the lowest level of alert — that lasted for about six hours.
An unusual event is the lowest of four emergency classifications as defined by the Nuclear Regulatory Commission (NRC), the federal agency which oversees operations of the nation’s nuclear power plants.
Delmar said operators were not sure when Salem 2 would return to service.
NRC resident inspectors assigned to the plant will follow up on the incident to ensure PSEG Nuclear fully understand the cause of the leak and its taking appropriate steps to prevent it from happening again, according to the agency.