NRC asks Mitsubishi for report on San Onofre equipment issues

The U.S. Nuclear Regulatory Commission has asked Mitsubishi Heavy Industries to hand over a redacted version of a report on equipment issues at the now-shuttered San Onofre nuclear plant.

The commission, which has already reviewed the full report, said it intends to make the redacted version public.

Sen. Barbara Boxer (D-Calif.) and U.S. Rep. Ed Markey (D-Mass.) obtained a leaked copy of the report and alleged in a letter to the head of the NRC last week that it indicated the utility and manufacturer were aware of “serious problems” with their design of the nuclear plant’s replacement steam generator and failed to fix the flaw before the equipment was installed.

The lawmakers said Edison and Mitsubishi wanted to avoid triggering a lengthy license amendment process. Edison is the plant’s operator, and Mitsubishi manufactured the steam generators.

San Onofre was shuttered a little more than a year ago because of unusual degradation of the plant’s steam generator tubes. One of the tubes leaked in January 2012, releasing a small amount of radioactive steam.

A source familiar with the report said a team formed early in the design process to look at the design of anti-vibration bars recognized that the steam in the new equipment could be drier than in previous designs. Dry steam was one of the factors later identified as contributing to the excessive tube vibration and wear at the plant.

Edison and Mitsubishi have denied that they knowingly installed faulty equipment, and accused the lawmakers of taking brief excerpts of a lengthy report out of context.

Victor Dricks, an NRC spokesman, said the agency requested Thursday that Mitsubishi provide a redacted version of the report by Friday. A Mitsubishi spokesman said the company had received the request and was in the process of responding to it.

In response to Boxer and Markey’s letter, NRC Chairwoman Allison Macfarlane disclosed that NRC’s investigative arm had launched an “expansive investigation” in September into the “completeness and accuracy” of information provided by Edison. Greg Werner, who headed an NRC special inspection team charged with finding the cause of the steam generator issues, said the investigation was related to information Edison gave the team.

Pete Dietrich, Edison’s chief nuclear officer, said at a public meeting Tuesday that the company would cooperate with the probe.

The NRC is still reviewing a proposal by Edison to restart one of the plant’s two reactor units and run it at 70% power, which the company said would prevent the excessive tube vibration. A decision could come in late April.

As part of a series of follow-up questions, NRC staff asked Edison to show that the tubes could maintain structural integrity at 100% of its licensed operating power. The company has yet to respond.

On Thursday, investment banking firm Jefferies & Co. downgraded Edison stock from “hold” to “underperform,” saying: “We believe there is a growing likelihood that the NRC will require an amendment to the operating license ... before permitting the plant to restart. This would delay the restart for 6-12 months depending on whether the NRC decides to hold public hearings.”

Jefferies analyst Paul B. Fremont said he reached that conclusion based on conversations with NRC contacts — although he said they had not told him definitively that they would require a license amendment if Edison could not show it could operate the plant safely at its full licensed power.

Edison and San Diego Gas & Electric — which owns a 20% share in the plant — spent a combined $774 million replacing the steam generators, which utility customers are now paying for.

The California Public Utilities Commission is investigating the costs of the outage to determine whether money should be refunded to ratepayers. A decision could be reached on the first phase of the investigation, which involves looking at the plant’s 2012 expenses, in July.

abby.sewell@latimes.com