The trouble-plagued Rancho Seco nuclear power plant near Sacramento was shut down Tuesday after highly radioactive water was found leaking from the reactor’s primary cooling system at the rate of slightly more than 60 gallons an hour.
The shutdown was classified as an “unusual event,” the lowest emergency action level. There was no release of radioactive materials from the reactor containment building into the atmosphere, and no personnel were exposed to radiation, officials said.
They said it would take two to six days to correct the problem.
Rancho Seco, southeast of Sacramento, was restarted last March after a 27-month shutdown. The plant has one of the worst operating records in U.S. commercial nuclear reactor history.
The plant was operating at 92% of its capacity Tuesday and generating 870 megawatts of electricity when the leak was discovered.
Officials of the Sacramento Municipal Utility District, which operates the plant, said they believed that the leak was coming from two valves, one of which is located in the reactor’s cooling system. SMUD officals said the leaking 1-inch valve in the primary cooling system had been repaired last August after it was found leaking then.
The shutdown Tuesday was the second in less than two weeks. On Oct. 14, emergency equipmentautomatically turned the plant off after rain caused failures in Pacific Gas & Electric Co. transmission lines.
Last June, a ballot measure to keep the plant open on a trial basis for 18 months was narrowly approved by Sacramento-area voters.