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Tuesday, July 17, 2012

San Onofre S/G tube wear - July 13 Press Release

Below is a press release from Southern California Edison.


Southern California Edison Releases Steam Generator Tube Wear Data

July 13, 2012

Media contact: Media Relations, (626) 302-2255
Investor relations contact: Scott Cunningham, (626) 302-2540

ROSEMEAD, Calif., July 13, 2012 — Southern California Edison (SCE) has released steam generator tube wear data associated with the San Onofre Nuclear Generating Station (SONGS) to the Nuclear Regulatory Commission. The data show that most of the wear, or tube wall thinning, was less than 20 percent. This is far below the 35 percent wall-thinning limit, which would require that the tube be plugged. The majority of this wear is related to support structures. The nature of the support structure wear is not unusual in new steam generators and is part of the equipment settling in.

“We’re using this information and additional detailed data collected through testing to develop our repair plans according to best practices and industry standards, particularly the data on the unexpected tube-to-tube wear,” said Senior Vice President and Chief Nuclear Officer Pete Dietrich. “Safety continues to be the guiding principle behind all the work we are doing.”

The data include the various types of wear on the tubes and the number of tubes affected.

There were three major categories of wear: anti-vibration bar wear, tube support plate wear and tube-to-tube wear. Two minor categories of wear were also included: retainer bar wear and wear due to a foreign object. The foreign object wear, also not unusual in new steam generators, was only found in Unit 2 and was caused by a piece of welding material about the size of a quarter rubbing against two tubes.

•In Unit 2, 1,595 tubes showed wear of some type and 510 tubes were ultimately plugged — six tubes for showing wear of more than 35 percent and the rest for preventative measures.
•In Unit 3, 1,806 tubes showed wear of some type and 807 tubes were ultimately plugged — 381 tubes for wear of more than 35 percent and the rest for preventative measures.

The complete data for both units is available on the commission website for SONGS information: www.nrc.gov/info-finder/reactor/songs/tube-degradation.html.

Both units of the plant are currently safely shut down for inspections, analysis and tests. Unit 2 was taken out of service Jan. 9 for a planned outage. Unit 3 was safely taken offline Jan. 31 after station operators detected a leak in a steam generator tube. The units will remain shut down until SCE and the commission are satisfied that the units are safe to operate.

About Southern California Edison
An Edison International (NYSE:EIX) company, Southern California Edison is one of the nation’s largest electric utilities, serving a population of nearly 14 million via 4.9 million customer accounts in a 50,000-square-mile service area within Central, Coastal and Southern California.


Additionally, SCE has released the statement on a pdf; click here.

Note also that the SCE release includes a direct link to the new NRC oversight page constructed to cover the SONGS steam generator issues.

12:42 PM Eastern 7/17/2012

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