Nuclear consultants Fairewinds Associates and anti-nuclear activists Friends of the Earth are at it again with a new “report” that seeks to create concern, with little to no substance, over steam generator tube leaks at San Onofre Nuclear Generating Station (SONGS). The report, “Steam Generator Failures at San Onofre,” claims that without a thorough root cause analysis of why the plant’s recently installed steam generator tubes have become worn, that:
“…radioactive releases might be significantly larger than those that occurred after the January 2012 tube leak. Such an accident would cause implementation of the California emergency evacuation plan and closing of the San Clemente beach and Interstate I-5, potentially for an extended period of time.”
Fairewinds’ opinion misleads the general public to believe that the plant already released a large amount of radiation, which in fact, it has not. In a February 17 press release, Southern California Edison (SCE) clarified:
The radioactivity released to the atmosphere during the steam generator tube leak was barely measurable – 4E-5 millirems or 0.00004 millirems -- which is 200 times less than you would receive by having a smoke detector in your home for a year.
The steam generator tube wear leads to very minor leakage within the steam generator, which is something that can easily be detected by sophisticated monitors (as proven in this case) before any significant release of radiation would occur.
Given the fact that some news articles have already referenced the misleading Fairewinds report and other activist organizations are using it to push their anti-nuclear campaigns, I decided to get further analysis on this report with NEI’s Alex Marion, an electrical engineer who sits on the American Society of Mechanical Engineers Board on Nuclear Codes & Standards. In a nutshell, here’s what he had to say:
The issue at SONGS demonstrates the stringent safety practices in the U.S. nuclear energy industry. SONGS detected there was an issue with the steam generator tubes while implementing its rigorous inspection program, which has been accepted by the Nuclear Regulatory Commission. This involves examining the steam generator tubes and if degradation is found, then a more comprehensive examination is conducted that may include pressure testing of the tubes or sending samples of tubing to a metallurgical laboratory for independent evaluations. Once a root cause for the problem is discovered, the plant can fix the problem and restart. However, the plant will not continue operations until this analysis has been completed.
Why is a “root cause analysis” important?
Marion:
Basically, what you have is a large heat exchanger that uses heat from the primary reactor cooling water that flows within the thousands of tubes to transfer heat to a separate flow of water that surrounds the tubes. The water that flows outside of the tubes is converted to steam, which is used to drive turbine generators and make electricity. Because of vibrations that result from the water flow during plant operations, the tubes may rub against supporting structures resulting in “wear,” or thinning of the tube wall. This is a known form of wear that occasionally occurs, however, it was not expected to have occurred on as many tubes as had been found at San Onofre. A root cause analysis will determine what caused this unanticipated wear and how it can be minimized.
The Gundersen report suggests that the tube degradation is an anomaly and that the plant should continue to be shut down indefinitely. Is there a technical basis for this?
Marion:
We agree that the extent of wear in recently installed steam generator tubes is unusual. This is why we believe that you cannot effectively address the issue until a root cause analysis is completed, which is exactly what SCE is doing now, in close coordination with Mitsubishi and the Nuclear Regulatory Commission.
The report also calls into question SCE’s “like-for-like replacement” of its steam generators recently, suggesting that had the replacements been duplicates, “the problems that San Onofre is currently experiencing would have been dramatically reduced or entirely eliminated.” What does he mean by this?
Marion:
Utilities are allowed to replace equipment without prior NRC review and approval if certain criteria are satisfied. The criteria ensures that the replacement equipment still fulfills all safety requirements and does not deviate from the original plant design in a way that could compromise safe operation. Key features of the replacement steam generators at SONGS were modeled or tested to confirm their performance capability and structural integrity to demonstrate that they satisfied the design requirements.
In terms of “like-for-like” replacement, SONGS focused on the principle of form, fit and function. The new steam generator included a new, improved tube alloy versus the one which was previously used. They were able to demonstrate that with improved materials and enhanced design features, the steam generators could be installed and operate within the plant design limits with minimal modifications to the plant systems, instrumentation and controls.
Besides the fact that this report includes misleading claims for the general public, what is your overall conclusion about it?
Marion:
The report calls for Southern California Edison to keep SONGS shutdown until a thorough and systematic root cause analysis has been completed. That is precisely what is occurring now. The plant will remain shut down until the root cause is established and addressed and the NRC deems it can safely restart.
Once again, Fairewinds and its counterparts at Friends of the Earth have created a report that does little other than advance their anti-nuclear agenda. Their tactics, which unfortunately are picked up in news media and further disseminated by flights of television advertisements, do a disservice to the public by mischaracterizing the strong safety record of the U.S. nuclear industry.
The Nuclear Regulatory Commission has documented actions that must be taken before SCE is permitted to restart the San Onofre reactors. The company must demonstrate to the NRC that 1) the cause of the tube wear in both steam generators is well understood and 2) it will appropriately address the issue in order to ensure safe operation. Elmo Collins, the head of the NRC’s West region office, said:
Until we are satisfied that has been done, the plant will not be permitted to restart.
San Onofre is a safe nuclear plant and is a vital contributor to California’s electricity supply. Learn more about how Southern California Edison is working diligently to identify and fix the problem with its steam generator tubes in a new video with the company’s president Ron Litzinger.
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