SCE's Calif. San Onofre restart plan didn't rely on Mitsubishi

Wed Dec 19, 2012 9:15am EST

* NRC says Mitsubishi Heavy failed certain requirements

* SCE wants to restart Unit 2 at San Onofre

* NRC may approve of San Onofre 2 restart in March

* San Onofre reactors shut in January

Dec 19 (Reuters) - California power company Southern California Edison (SCE) said it did not rely on testing by Japanese engineering firm Mitsubishi Heavy Industries Ltd to develop its restart plan for Unit 2 at the San Onofre nuclear plant in California.

Both reactors at the 2,150-megawatt (MW) San Onofre plant shut in January due to tube wear problems in the units' new steam generators. Mitsubishi Heavy built those steam generators and installed them in 2010 and 2011.

The U.S. Nuclear Regulatory Commission (NRC) said in a letter posted on its website that Mitsubishi Heavy failed to meet certain requirements related to the mock-up and testing of re-designed components for the steam generators that may be used to repair the San Onofre steam generators.

But in a statement Tuesday night, SCE, a unit of California power company Edison International, said it did not consult or rely upon the Mitsubishi testing under review by the NRC to create the utility's plan to restart Unit 2.

The NRC is also reviewing SCE's plan to restart Unit 2 and may issue a decision on that plan in March. The reactor cannot restart without the NRC's approval.

SCE's plan to restart Unit 2 includes preventive plugging of tubes in the steam generators and operating the 1,070-MW unit at 70 percent power for a five-month period.

San Onofre is one of the biggest power plants in California and its shutdown since January has caused reliability challenges for the Southern California power grid.

INDEPENDENT EXPERTS

SCE said its team of experts conducted three independent operational assessments of tube wear. The assessments were done by units of nuclear engineering firm Areva SA of France, the Westinghouse Electric unit of Japan's Toshiba Corp , and international testers at Intertek/Aptech.

SCE said none of its experts based their review and recommendations on testing by Mitsubishi. SCE said this was confirmed Tuesday at an NRC public meeting in Rockville, Maryland.

SCE submitted technical information to the NRC in October in support of its proposed restart plan for Unit 2. That plan did not include a restart for Unit 3 in part because the steam generators in Unit 3 suffered more tube wear.

The company shut Unit 2 on Jan. 9 for a planned outage. Unit 3 shut on Jan. 31 after station operators detected a leak in a steam generator tube.

SCE operates San Onofre for its owners: SCE (78.21 percent), Sempra Energy's San Diego Gas & Electric (20 percent) and the city of Riverside (1.79 percent).

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