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Monday, June 18, 2012

Augmented Inspection Team Meeting at San Onofre (Press Release)

Southern California Edison has provided the following press release, direct to Atomic Power Review, concerning this evening's public NRC meeting at 6 PM Pacific.


Southern California Edison to Participate in Nuclear Regulatory Commission Public Meeting

ROSEMEAD, Calif., June 18, 2012 — Southern California Edison (SCE) will be participating in the Nuclear Regulatory Commission (NRC) public meeting today, Monday, June 18, in San Juan Capistrano. The NRC will present findings from its Augmented Inspection Team (AIT) that visited the San Onofre Nuclear Generating Station (SONGS) earlier this year. SCE has not received the NRC’s report from the AIT and cannot comment on its content at this time.

The utility will be presenting information to the NRC and the public on the ongoing steam generator tube wear analysis and responding to questions from the NRC at the public meeting.

“We know that the outage and the tube wear issue have generated concern in our community,” said SCE president Ron Litzinger. “This meeting is a further opportunity to talk with the NRC and the public about the rigorous process of inspection, testing and analysis that we continue to do at the plant and our ongoing commitment to safety.”

SCE’s number one priority is, and has been, the health and safety of the public and its employees. SCE will not restart the SONGS units until the utility and the NRC are satisfied that it is safe to do so.

SCE will not be discussing restart at the June 18 meeting as that is not within the scope of the AIT report. Currently, SCE estimates that SONGS Unit 2 likely will remain off line through August. A plan for Unit 3 is expected to take longer to develop.

Unit 2 was taken out of service Jan. 9 for a planned outage. Unit 3 was safely taken off line Jan. 31 after station operators detected a leak in a steam generator tube.

More information is available at www.edison.com/songsupdate.

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.


Jennifer Manfrè
Senior Manager, Media Relations
Southern California Edison


Southern California Edison has also provided us with a copy of a special fact sheet which has been distributed to interested parties; this fact sheet gives some quick background on steam generator replacement. Click here to access this fact sheet on the SONGS update page.

Jennifer Manfre has also provided a copy of the relevant pages of the Federal Register in which are covered the NRC findings on the San Onofre steam generator replacement. It is clear that the NRC staff found "no significant hazards."

Given the history of steam generator replacements prior to those performed at San Onofre, data this author has read on Inconel 690, the SoCal Ed referenced material and professional opinions, there is no specific or pointed reason known or given at this time to think that anyone - SoCal Ed, Mitsubishi, the NRC or anyone else - should have suspected problems due to vibration in these steam generators such that tube damage would occur. Reports today in the general press are indeed focusing on design issues with the steam generators, apparently in an advance release of NRC investigation findings. Much more work remains to determine the root cause of this problem.

It is unknown to this author why NRC AIT findings would be released and / or discussed in an Associated Press wire story prior to the findings being supplied to Southern California Edison.

SoCal Ed will be taping the meeting and may post some of the video; if this happens, I'll note that on this site.

6:25 PM Eastern 6/18/2012


UPDATE 11:00 AM Eastern 6/19/2012

The news on the wires this morning is that the NRC feels that computer modeling performed by Mitsubishi in determining flow and heat transfer characteristics internal to the generators was flawed. This seems to drop the problem squarely in Mitsubishi's lap, but there is by no means a certain outcome for this yet - in fact, whether or not Mitsubishi is finally found at fault, Southern California Edison could well still be fined. The situation is still highly unclear, although we're a step along in determining the real cause. As Meredith Angwin pointed out in her very popular guest post on steam generators, it would appear (in my opinion as well) that operation at reduced power should be possible with greatly reduced likelihood of damage. This will probably shake out as the operational testing period plan.


  1. Seems there were some sizeable errors made by Mitsubishi in modeling the fluid flows in the tubes, according to the LA Times.
    Not sure this is the root cause, but a surprising discovery, as a factor of 3 difference in flow really should be pretty apparent.

  2. We have the update on this now and I'm awaiting some comment from SoCal Ed on the matter. Some of us have been waiting a long time to see just who would get "pinned" for this.. and it is not certain yet by a long shot.

  3. Who decided to make the changes to the steam generator from the original, that is, adding the 400 extra tubes? Was it Mitsubishi's idea or Edison? I would not think that Mitsubishi would be culpable if their customer told them how to manufacture the unit. Do these units have a warranty? If so, the most Mitsubishi would be out it to manufacture new steam generators the way they were originally. Which brings up - is there such a thing as a "universal" steam generator, like they have with some appliance and car parts?

  4. @Robert: I am not entirely certain at this moment where the alterations began. It is my notion that the beginning of the changes likely started with the use of Inconel 690 tubes, which have a number of superior characteristics to the older material (Inconel 600) but have worse heat transfer characteristics. So then you might want to add more tubes, perhaps with thinner diameters (some older replacement steam generators with Inconel 690 tubes that were virtual copies of originals with Inconel 600 were found to generate lower steam pressures due to slightly less efficient heat transfer.) From there, other alterations to support and align the increased number of tubes were likely made. Who started this process is not known.

    There is no "universal" replacement, per se, since there are a number of different original steam generator designs of widely various sizes, weights, power ratings and with different locations for the various connections. Unfortunately, the "First Nuclear Era" ended just as truly standardized nuclear plants were just beginning to appear (like the Westinghouse SNUPPS, the "Babcock-205" and the Combustion Engineering CE-80.)

    There absolutely is warranty coverage, and recent reports from the last few days say that Mitsubishi is now very actively involved in finding out the root cause of the problem.