The Perry nuclear power plant outside Cleveland is leaking tritium, a radioactive form of water with a half-life of more than 12 years.
The radioactive water was in groundwater at concentrations more than twice the federal drinking water limit outside of a building where workers found the leak Monday. Workers found no other, more dangerous radioactive isotopes.
Plant owner FirstEnergy said the tritium has not made its way into the plant’s larger under-drain system designed to collect groundwater from under the entire site. Nor is the isotope in other groundwater test sites on the property or in nearby Lake Erie.
“It was found in one sample area next to the building. I know of at least five other areas that have been sampled and there have been no indications of tritium beyond that one,” said Jennifer Young, FirstEnergy nuclear spokeswoman.
“We are doing additional sampling today. Any groundwater flows into the plant’s under-drain system,” she said. “It has not left the plant boundaries.”
Perry engineers reported the problem to the Nuclear Regulatory Commission (NRC) and its on-site inspectors, as well as to county and state emergency agencies about 1:40 a.m. Tuesday.
“Actions are in progress to stop the leak,” the NRC report said. Engineers were still working late Tuesday afternoon to seal it.
Workers discovered the leak Monday in a valve on a water line that carries reactor water back to the reactor after it has run through the plant’s steam turbine and then been condensed back into water.
The leaky valve was in a pipe contained in a hallway-sized steam tunnel running from the turbine and generator building through a second, auxiliary equipment building and then back into the reactor containment building, said Young.
She could not say when the leak began. She described it as a small spray of water and steam, which cameras monitoring the tunnel picked up.
The NRC on Tuesday said the leak, as described by the company, does not pose a serious risk to the public.