The Nuclear Regulatory Commission today released a document that opponents of the troubled San Onofre Nuclear Generating Station say proves Southern California Edison knowingly installed faulty steam generators without regard to the safety risks.
Why? Environmental groups and some lawmakers allege it was to avoid a costly and lengthy bureaucratic process the NRC would have required if they had fixed the problem. The controversy has prompted city officials from Los Angeles to San Diego to call for additional oversight of the plant because of the safety impact on millions of people. Sen. Barbara Boxer (D-Ca) and Rep. Ed Markey (D-Mass ) lead the charge release the documents today.
“These reports raise serious concerns about whether Southern California Edison and Mitsubishi Heavy Industries rejected safety modifications to avoid triggering the more rigorous license amendment and safety review process," Boxer stated in a joint press release with Markey.
"That is why it is essential that the NRC complete its expansive investigation into whether Southern California Edison fully complied with its legal obligations at the San Onofre nuclear facility," she said.
Regulators and Edison officials have said in the past that they complied with all regulations when installing the faulty $670 million in steam generators -- one of which sprang a radioactive leak last year.
"[Steam generator manufacturer Mitsubishi Heavy Industries] repeatedly reassured SCE of the efficacy of the design," Edison officials said in a statement Friday. They continued, saying Mitsubishi, "did not require additional design changes or measures, and that the replacement steam generators would perform as warranted."
But a coalition of local and national environmental groups is crying foul. The national group Friends of the Earth has lodged a legal complaint demanding that the NRC force Edison face a judge before a decision on whether to restart the plant can be made.
They argue that Edison made significant design changes that should have triggered a formal license amendment process before they installed the new generators, which use radioactive steam to boil fresh water through dense bundles of closed tubes. The process would have provided the additional scrutiny and oversight of the project.
Friends of the Earth point to a passage in the newly-released documents they say shows Edison knew the new design could cause intense vibration, but prevented engineers at Mitsubishi Heavy Industries from doing anything about it to avoid triggering the formal review process.
“Early in the project, [Southern California Edison] and [Mitsubishi Heavy Industries] formed an [anti-vibration bar] Design Team with the goal of minimizing U-bend tube vibration and wear..."
One of the causes of the leak -- which revealed damage to more than 1,300 tubes throughout the plant's four generators -- was caused by the vibration of the tubes at the point where they bend around in a "U" shape. The tubes rubbed up against the stabilizers called "anti-vibration bars," causing the tube walls to grow thinner.
The anti-vibration bar team "had considered making changes" to reduce the vibration but decided against them, according to the document.
"Each of the considered changes had unacceptable consequences and the AVB Design Team agreed not to implement them," the document states. "Among the difficulties associated with the potential changes was the possibility that making them could impede the ability to justify the [replacement steam generator] design under the provisions of the 10 C.F.R. §50.59 [NRC licensing rules].”
That section refers to the section of NRC code that requires a formal license amendment for significant design changes.
Chief Nuclear Officer Pete Dietrich said in Edison's statement that it is wrong to think the company would knowingly install unsafe equipment.
“SCE’s own oversight of MHI’s design review complied with industry standards and best practices,” Dietrich said. “SCE would never, and did not, install steam generators that it believed would impact public safety or impair reliability.”
See the redacted report as released by the NRC in the PDF attached to this article.