Nuclear Energy

Published on April 4th, 2013 | by Guest Contributor


San Onofre: What Happened And What Must Not Happen Now

April 4th, 2013 by  

By Roy L Hales
Printed with the permission of San Diego Loves Green

Take a very close look at the diagram below. Notice the words “Tube Burst,” “Tube Burst Criterion” and “Tube fails 95% Burst probability 1.35 year.” These are calculations as to how long the tubes in unit #2, at San Onofre Nuclear facility would remain intact if the generator went online now. Generators are supposed to last 30 to 40 years, not 1.35 years. This is not a normal situation, in which there is “no significant hazard.” Yet, 14 months after having to shut down because of the unprecedented wear in their generator tubes, Southern California Edison is claiming they should be allowed to start the facility up again.


Image Credit: Declaration of John Large in Support of 2,206 Petition by Friends of the Earth

The diagram was drawn up by a consulting firm hired by Edison. Another firm told them the tubes could fail in six months. According to John Large, a London-based expert on nuclear reactors, this is the reason Edison would need to be shut down after five months “for steam generator tube inspections.” Then they could repair the damage and start another five month cycle.

One of the inherent problems with this “solution” is that it leaves no room for unexpected developments and, up to this point, San Onofre has been plagued by unanticipated events. Large believes that San Onofre’s reactor might be able to go through two or three such cycles. He did not say, and the rest of us neglected to ask, what would happen if there was a failure before the cycle completed.

Large did say, however, that he “would have expected the Nuclear Regulatory Commission (NRC) to be much more proactive” in these proceedings. They must have been aware that something out of the ordinary was happening, but were initially content with Edison’s reassurances. Now the NRC appears to be contemplating allowing Edison to proceed without carrying out a thorough examination of what happened, as well as what problems there may be ahead if Edison is allowed to restart San Onofre again.
Large and  Kendra Ulrich, Nuclear campaigner for Friends of the Earth, were the principal speakers at a phone in press conference this afternoon.

Contrary to what it has been claiming, Large says the documents show Edison not only knew about the potential flaws at San Onofre, but that it was “involved in the overall and detailed design of the replacement steam generators” from the beginning. “In September 2004  …  SCE issued the Certified Design Specification (CDS) spelling out the design strategy of the anti-vibration bar (AVB) support systems that were to prove crucial in the tube degradation performance” that led to San Onofre’s shutdown. After Mitsubishi’s computer analysis predicted a potential problem, a team composed of Edison and Mitsubishi (MHI) designers investigated this problem. That was in 2005.

Edison still claims that “at no time was SCE informed that the maximum void fraction or flow velocities estimated by MHI could contribute to the failure of steam generator tubes  … at the time, the design was considered sound.”

Yet on page 48 of Mitsubishi’s Root Cause Analysis it states the following:

“MHI and SCE recognized that the SONGS RSG steam quality (void fraction) was high and MHI performed feasibility studies of different methods to decrease it. Several design adjustments were made to reduce the steam quality (void fraction) but the effects were small. Design measures to reduce the steam quality (void fraction) by a greater amount were considered, but these changes had unacceptable consequences and MHI and SCE agreed not to implement them.”

And again, on page 22, it states:

“AVB Design Team recognized that the design for the SONGS RSGs resulted in higher steam quality (void fraction) than previous designs and had considered making changes to the design to reduce the void fraction (e.g. using a larger downcomer, using large flow slot design for the tube support plates and even removing a TSP). But each of the considered changes had unacceptable consequences and the AVB Design Team agreed not to implement them.”

The “unacceptable consequences” these refers to was the idea of putting Edison in a position where it would have to apply for a License Amendment. In order to evade the investigation applying for a License Amendment would have entailed, Edison reassured the Nuclear Regulatory Commission their new generators would “not not give rise to any detriment to the established SONGS nuclear safety case.” They were installing “like for like with limited exceptions, and were replaced under the 10CFR50.59 rule.” This meant there would be no need to apply for a License Amendment, but also created a situation that Large compares to trying to force a round peg into a square hole. The shape, size, and dimensions of San Onofre’s new generators were all set by Edison’s need to evade a thorough investigation.

The tube wear that caused San Onofre’s shutdown was a “direct result of the inappropriateness of the SCE-MHI jointly specified” design.

Ulrich put it much simpler: Edison was aware there could be a problem and took a gamble.

This pattern of evasion appears to be continuing. Edison is now seeking to fast track the licensing process by submitting a request to the NRC for a finding of no significant hazard.

How could the Nuclear Regulatory Commission even consider such a request? Haven’t there been enough irregularities at San Onofre? Has the NRC forgotten that their “mandate is to protect public health and safety and the environment?”

“A No Significant Hazards Consideration would effectively strip the public of their right to full independent critical safety review and public hearing rights,” Ulrich said.

“It is a regulatory loophole that would make any public hearing take place after an unassailable license amendment decision is made, rendering public input meaningless. The NRC must stand firm and demand a comprehensive license amendment process that includes all safety issues, and the opportunity for full public hearing. It must also reject Edison’s demand for a no hazard finding. This is not a footnote in a license as Edison claims but a severely damaged reactor that is unsafe to operate.”

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  • dynamo.joe

    Ya, I don’t really see the problem. There is a 5% chance of it breaking at the 15 month mark and they are proposing a inspection/repair/replace cycle of 5 months.

    Matthew, they are failing the 95% criteria at 1.3 years, not they have a 95% failure rate at 1.3 years. I’m guessing regulations say “no component can have a probability of failure greater than 0.05”.

    I’m no nuclear expert, but if this is a steam generator tube then it doesn’t ever enter the core, it’s a secondary water line. If that is true, even if it failed, there is no radiation and the only danger is to anyone who happens to be standing next to it. It’s an economic and worker safety issue, but not a public safety issue.

    • Bob_Wallace

      It’s an economic issue and one that could seemingly be solved with an aggressive PV installation program.

      It’s only during sunny, hot days that San Diego is pressed for supply. That’s when San Onofre’s absence is leaving them short. That’s also when solar panels produce electricity.

      Quit spending money on rebuilding San O’s steam generation system every few months. Offer a great big, short term rebate for new solar and fill up a bunch of rooftops. There’s plenty of panels available and the construction trade would love some job creation.

      And if there would be unmet late afternoon/evening demand then put some money into getting more wind turbines on line.

  • Just a minute, I not a fan of Nuclear; but the above graphic looks a bit faked. First the label on the left implies a 5% change of failure when you cross the red line not 95%. Second if the failure is vibration induced, the chance of failure wold not be zero for a year and then jump, you would expect the curve to grow some before going vertical. So while I agree that the US should be following Germany’s lead in turning away from nuclear, using what looks like faked data is not the way to go. The truth is bad enough.

  • The lack of transparency these energy monopolies generate is what makes nuclear power an obvious mistake. It is just too complicated to be anything but totally transparent and they will never make it transparent. The energy monopolies will instead buy the politicians and we won’t know what’s going on until it falls apart. Large companies can’t even manage to keep pipes from breaking and leaking oil. No way should they be trusted with potential dangers of this magnitude. They need to keep it simple and idiot proof. Use solar power and wind turbines instead.

    • Completely agree. People demand transparency today. And nuclear simply can’t offer it (safely/intelligently) — since everyone would see what a ripoff it is.

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