A coolant leak shut down an Ohio reactor last weekend, one month after an earlier refueling outage.

Perry nuclear plant. Source: NRCWorkers at Perry unit 1 found a leak in the base of a recirculation flow control valve vent line at about 11 p.m., Saturday, according to a report filed with the Nuclear Regulatory Commission. After drywell leakage indications, a worker inspecting the drywell observed steam coming from a weld on the valve, the NRC reported. While FirstEnergy described the leak as small and could not provide a leak rate, federal regulations required that the reactor shut down.

A plant spokeswoman told the Cleveland Plain Dealer the steam did not make its way into other areas of the plant or the environment. Repairs are underway.

Perry's reactor is a General Electric Type 6 boiling water reactor, first licensed in 1986, according to the NRC. It is located northeast of Cleveland.