Southern California Edison (SCE) owns and operates the San Onofre Nuclear Generating Station one the Pacific Coast between Los Angeles and San Diego. The station is located next to the Cristianitos fault which is listed as inactive. Around 7.4 million people live within 50 miles of the plant.
The Unit 1 reactor was a first generation pressurized water reactor that came online in 1967. It was decommissioned in 1992 and dismantled. It is now used to store spent fuel rods.
The Unit 2 and Unit 3 reactors are also pressurized water reactors. They were commissioned in 1982 and their licenses are set to expire in 2022 giving them 40 year life spans.
There have been technical problems at the plant over the years of operation. In 2008, the plant received multiple citations for such issues as failed emergency generators, improperly wired battery systems, and falsified fire safety records. A review in 2011 suggested that there had not been sufficient improvement in the area of human performance. Many anti-nuclear protests have been held at the station.
In January 2012, a break in a pipe that carries radioactive water for the Unit 3 reactor resulted in the release of a small amount of radioactive steam. SCE stated at the time that the radiation that escaped posed no threat to the workers at the plant of people who lived nearby.
When the steam pipes for the Unit 3 reactor were examined, it was found that they had sustained unexpected damage and the Unit 3 reactor was then shut down.
The Unit 2 reactor was shut down for maintenance in January and it was found that many of the tubes were also worn but not as seriously as the piping of the Unit 3 reactor. that service were found to have unusual wear.
It was eventually determined that a faulty computer analysis program had resulted in a bad design for the steam pipes that service the four steam turbines. There will need to be a lot of work on the piping system before the reactors can be restarted but no plan has been presented for how to accomplish this work.
The initial focus is on repairing the steam pipes for Unit 2 which have less damage than the Unit 3 pipes. No schedule has been announced for the repairs to Unit 2 and there has been no estimate of when it may be started again.
SCE has just announced its intention to remove the fuel rods from the Unit 3 reactor and move them into storage in September. This will make repair of the piping system easier but it will also mean that the Unit 3 reactor will be off line for a longer time. Removing the fuel from the reactor will incidentally reduce the number of inspections and tests that must be performed as required by the Nuclear Regulatory Commission.
SCE had previously announced that it is laying off part of its workforce. In view of the fact that this will leave fewer personnel to carry out necessary work, it makes sense to remove the fuel and reduce the work load at the plant.
