The NRC made public today redacted versions of two reports prepared by Mitsubishi Heavy Industries concerning the steam generator replacement at the San Onofre Nuclear Generating Station (SONGS).
The Steam Generator Root Cause Analysis Report and a Supplemental Technical Evaluation Report were prepared by Mitsubishi Heavy Industries as part of its effort to determine what contributed to the unusual wear in the steam generators after they were installed in 2010 and 2011 at Units 2 and 3, respectively.
The NRC is using a variety of regulatory actions, such as inspections and investigations, to ensure that it is comprehensively addressing the issues that have arisen at the SONGS nuclear power plant.
On Sept. 28, 2012, the NRC began an expansive investigation on the completeness and accuracy of information that Edison provided to the NRC regarding the steam generator degradation under the NRC’s regulatory requirements.
These reports are included in an array of documents being reviewed by the NRC as we investigate whether Edison demonstrated sufficient due diligence in its oversight of the redesign of the steam generators; how design changes that were made or rejected may have affected the safety of the steam generators; and the truthfulness and accuracy of all the information Edison has provided to the NRC regarding the redesign and replacement of the steam generators.
Separately from the ongoing investigation, the NRC is evaluating Edison’s responses to questions the NRC has raised about their request to restart Unit 2 at the plant.
Additionally, the Atomic Safety and Licensing Board is reviewing issues related to the Confirmatory Action Letter issued by the NRC staff to Southern California Edison.