Environmental group argues against restarting San Onofre plant

The environmental group Friends of the Earth made its case to federal regulators last week that Southern California Edison should be barred from restarting the San Onofre nuclear plant unless it goes through a trial-like hearing process.

The meeting between Friends of the Earth and a U.S. Nuclear Regulatory Commission review board on Wednesday was the latest step in a dispute that has lasted for more than six months.

San Onofre has been closed for nearly a year because of unusual wear on tubes at the plant, which resulted in a small leak of radioactive steam last January. The tubes are part of four giant steam generators that Edison replaced in 2010 and 2011.

An NRC investigation found that the issues arose because computer modeling by manufacturer Mitsubishi Heavy Industries failed to accurately predict the flow of steam and water in the generators, leading the tubes to vibrate excessively and rub against support structures and adjacent tubes.

Friends of the Earth alleges that the “root cause” of the issue was design changes ordered by Edison, and that the company should have requested a license amendment for the changes made between the old and new steam generators.

If the NRC petition review board agrees, the group argued, it should take enforcement action by suspending the plant’s license until Edison applies for a license amendment for all the design changes.

The new steam generators used a different alloy for the tubing, increased the number of tubes and have changes in the design of the support structures. Edison has said that the changes were made to improve the equipment’s performance and were in line with industry standards.

But Arnie Gundersen, a consultant for Friends of the Earth, contended that a more thorough review of the changes by the U.S. Nuclear Regulatory Commission might have prevented the defects.

In Wednesday’s presentation, Friends of the Earth argued that the problems were foreseeable and that “Edison should have notified the NRC that the significance of all the changes required” a license amendment.

“In the past 10 years, nobody has screwed up a piece of equipment more than the steam generators at San Onofre,” Gundersen told the board.

Edison did apply for and receive a license amendment in connection with the replacement steam generators, but not for the design changes.

Edison spokeswoman Maureen Brown said that since the early 1980s, most steam generator replacements have been done without license amendments — unless the replacement was done in connection with another change, such as increasing the power the plant is licensed to produce.

In its filing with the NRC, Edison argued that commission staff had already reviewed the process followed for the design changes — both when the generators were installed and as part of the more recent investigation — and that there was no way to foresee that Mitsubishi’s computer model would fail to predict a potential issue.

It is unclear when the review board will issue a decision.

A separate but related petition by Friends of the Earth is pending before another NRC board. Meanwhile, the commission is also reviewing Edison’s restart plan for San Onofre and may make a decision on that issue in March.

abby.sewell@latimes.com