The San Onofre nuclear power plant came under renewed scrutiny last week after a small radiation leak and the discovery of extensive tube damage. the incidents raised concern among environmental groups, which for years have kept a close eye on the plant near San Clemente following other safety problems.
Trouble began at San Onofre on Tuesday when a leak from a tube at one unit released a small amount of radiation, prompting operators to shut down the reactor.
On Thursday, at a second unit that was shut down for maintenance, nuclear regulation officials found extensive wear on tubes that carry radioactive water in a steam generator. The tubes were installed less than two years ago after they were delivered by the Japanese manufacturer of the generators, Mitsubishi Heavy Industries.
Two of the tubes showed more than 30% wall thinning, 69 had 20% thinning and more than 800 had 10% thinning, said Victor Dricks, spokesman for the Nuclear Regulatory Commission.
Manfre said the extent of the tube damage was not yet clear to Edison.
Both units were shut down Friday as officials conducted inspections. Manfre said it was too soon to know when the units would be working again or how much of the tubing needs to be replaced or repaired.
On Friday, a local newspaper reported a third incident involving a veteran worker at the plant who lost his balance while trying to retrieve a flashlight and tumbled into a reactor pool. The man reportedly did not suffer significant radiation exposure. Edison may review its procedures for working around the reactor pool, officials said.
Some critics saw the incidents as a sign of greater problems.
In 2008, the plant received a string of citations over such issues as failed emergency generators, improperly wired batteries and falsified fire safety data, records show.
Early last year, the NRC issued its annual review of San Onofre, identifying improvements but noting that in the area of human performance, “corrective actions to date have not resulted in sustained and measurable improvement.”
– from latimes.com