Federal regulators on Friday released parts of a once-confidential report at the center of a dispute between California Sen. Barbara Boxer and the company that runs the troubled San Onofre nuclear power plant.
However, sections of the 64-page report released by the Nuclear Regulatory Commission were redacted, and it wasn't immediately clear if the issues highlighted by Boxer were included.
The Democratic senator said last month that the study suggests operator Southern California Edison took shortcuts that compromised safety at the seaside plant, which was shut down more than a year ago after a tube break released a trace of radiation.
Edison has said the senator is off the mark.
The report was authored by Mitsubishi Heavy Industries - the Japan-based company that built the plant's troubled steam generators.
The problems at the twin-domed plant between Los Angeles and San Diego center on the huge generators, which were installed in a $670 million overhaul in 2009 and 2010.
After the plant was shut down, investigators found unusual damage on hundreds of tubes that carry radioactive water inside the equipment. NRC investigators later blamed the problem on a flawed computer analysis that resulted in design flaws.
Edison has asked the NRC for permission to restart one of the reactors, Unit 2, and run it as reduced power in hopes of slowing or stopping tube damage.
The generators, which resemble massive steel fire hydrants, control heat in the reactors and operate something like a car radiator. At San Onofre, each one stands 65 feet high, weighs 1.3 million pounds, with 9,727 U-shaped tubes inside, each three-quarters of an inch in diameter.
Overall, NRC records show investigators found wear from friction and vibration in 15,000 places, in varying degrees, in 3,401 tubes inside the plant's four generators, two in each reactor.
The plant is owned by SCE, San Diego Gas & Electric and the city of Riverside.