FirstEnergy (NYSE: FE), owner and operator of the facility, said two mechanics were working on a valve of an air system when liquid refrigerant began leaking from the valve and then turned into gas.
The control room was contacted. After tests, the air showed high levels of trichloroethylene.
Jennifer Young, spokeswoman for FirstEnergy said the leak was contained and the valve was repaired. She added that the cooling system contained no radioactive material and the leak did not affect the operation of the plant.