San Onofre: Why it happened & What MUST not happen now

By Roy L Hales

Screen-shot-2014-03-18-at-3.43.47-PM1Take a very close look at the diagram above. 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 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 (SCE) is claiming they should be allowed to start the facility up again.

The diagram was allegedly 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, “I 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 appear to have been satisfied with Edison’s reassurances. After all that has transpired, the NRC may actually allow Edison to proceed without carrying out a thorough examination of what happened and what problems there may be ahead if Edison is allowed to start San Onofre up 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 they have been claiming, Large says the documents show Edison not only knew about the potential flaws at San Onofre, 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 of composed 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, “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 the, “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 putting Edison in a position where it would have to apply for a License Amendment. In order to evade the investigation this 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 “direct result on 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? Does the NRC need to be reminded that their “mandate is to protect public health and safety and the environment?” (These are my questions, not Large’s or Ulrich’s.)

“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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