San Onofre Nuke Plant: "Mitsubishi Heavy failed certain requirements", Says NRC

Friday, December 21, 2012

San Onofre Nuke Plant: "Mitsubishi Heavy failed certain requirements", Says NRCSan Onofre Nuke Plant: "Mitsubishi Heavy failed certain requirements", Says NRC

NRC says Mitsubishi Heavy Industries failed to meet requirements related to the mock-up and testing of re-designed components for the steam generators.

So-Cal Edison wants to restart Reactor 2 in March. It says independent experts from Areva, Westingshouse/Toshiba, and Intertek/Aptech conducted the operational assessment.

SCE insists the company didn't rely on Mitsubishi (as if it is a good thing; maybe it is...).

For more on the Mitsubishi-made steam generator problems at San Onofre, see my posts (here and here).

From Reuters (12/19/2012; emphasis is mine):

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

* 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).

I think NRC's letter mentioned in the article is this. It's more a report than a letter, dated November 30, 2012. So NRC staff made a trip to Kobe, Japan to inspect Mitsubishi Heavy Industries' noncompliance. Interesting.

Addressed to the Quality Assurance Manager Mr. Otake, NRC says:

From October 9-17, 2012, the U.S. Nuclear Regulatory Commission (NRC) staff conducted an inspection at the Mitsubishi Heavy Industries, Ltd (MHI) facility in Kobe, Japan. The purpose of this reactive inspection was to assess MHI’s compliance with the provisions of Title 10 of the Code of Federal Regulations (10 CFR) Part 21, “Reporting of Defects and Noncompliance,” and selected portions of Appendix B, “Quality Assurance Program Criteria for Nuclear Power Plants and Fuel Reprocessing Plants,” to 10 CFR Part 50, “Domestic Licensing of Production and Utilization Facilities.”

This reactive inspection evaluated MHI’s quality assurance activities associated with the mock-up and testing of re-designed anti-vibration bars that may be used as a long-term repair of both Unit 2 and Unit 3 San Onofre Nuclear Generating Station (SONGS) steam generators. The inspection will assist the Nuclear Regulatory Commission (NRC) when and if modifications are installed at SONGS. The design and installation of the modification will require that the NRC conduct an independent review of the modification and possibly approval of the design change. The inspection evaluated if MHI’s design, manufacturing, preparation, and testing of the mock-up and testing of re-designed anti-vibration bars meet the applicable requirements of Appendix B to 10 CFR Part 50, 10 CFR Part 21, and American Society of Mechanical Engineers Code Section III, “Rules for Construction of Nuclear Facility Components”. The enclosed report presents the results of this inspection. This NRC inspection report does not constitute NRC endorsement of MHI’s overall quality assurance (QA) or 10 CFR Part 21 programs.

During this inspection, the NRC inspection team found that the implementation of your quality assurance program failed to meet certain NRC requirements imposed on MHI by its customers or NRC licensees. Specifically, MHI: 1) failed to verify the tube outside diameter straightness, tube bending radius, and total tube length conformed to the requirements identified in the purchase order and purchase specifications to Sumitomo Metal Corporation for the alloy 690 seamless tubes used to construct the steam generator u-tube bundle mock-up; and
2) failed to perform dedication of the commercial calibration services provided by Tokyo Sokki Kenkyujo Co., Ltd. The enclosed Notice of Nonconformance (NON) cites these nonconformances, and the circumstances surrounding them are described in detail in the enclosed inspection report. Even though the NRC inspection team did not identify issues in all areas reviewed, in the response to the enclosed NON, MHI should document the results of the extent of condition and determine if there are any effects on other associated QA activities.

Please provide a written statement or explanation within 30 days from the date of this letter in accordance with the instructions specified in the enclosed NON. We will consider extending the response time if you show good cause for us to do so.

The letter is followed by the notice of nonconformance and the detailed inspection report.

Quick check on MHI's website, and there is still no mention of the accident.