U.S. NRC Blog

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An Update on San Onofre

Three months to the day after being dispatched under a charter to investigate the circumstances surrounding a steam generator tube leak at the San Onofre Nuclear Generating Station, an NRC Augmented Inspection Team issued their findings in a report just under 100 pages long.

Most of their findings had been previously reported by the news media following a June 18 public meeting in San Juan Capistrano. The team found that faulty computer modeling that inadequately predicted conditions in steam generators at the plant and manufacturing issues contributed to excessive wear of the components.

But the team also addressed an issue that had been the focus of much public attention – whether Southern California Edison provided the NRC all the information required about the proposed design changes to the steam generators before replacing them. The team reported that the licensee had done this.

The team also identified 10 issues requiring follow-up by the NRC. And another inspection will be conducted to assess the licensee’s regulatory compliance and identify potential violations of NRC requirements.

What lies ahead?We are now looking at dates and a location for another public meeting to be held in the vicinity of the plant. We will schedule this meeting in the near future to receive and respond to public comments and questions on the now-finalized AIT report and other issues of public concern.

The plant will not be permitted to restart until the licensee has developed a plan to prevent further steam generator tube degradation and the NRC independently verifies that it can be operated safely.

Victor Dricks
Region IV Public Affairs

35 responses to “An Update on San Onofre

  1. fresh December 4, 2012 at 10:20 am

    When will the NRC stop being disrespected by those that are supposed to listen to them!

    NRC need more power to regulate and IMPOSE fines!

  2. HelpAllHurtNeverBaba November 30, 2012 at 3:12 am

    Westinghouse calculates a void fraction of 99.6% in both Units, but claims, no fluid elastic instability occurred in Unit 2. DAB Safety Team agrees with Westinghouse based on review of plant operational data that no fluid elastic instability occurred in Unit 2. NRC and SCE both claim that Operational Conditions were same in both units, but fluid elastic instability occurred in Unit 3 due to high steam flows, velocities (MHI Computer model under-predicted TH conditions) and manufacturing defects, which created insufficient contact forces between tube-to-AVB Gaps. However, based on a review of AREVA and Westinghouse OAs, DAB Safety Team has concluded that fluid elastic instability and MHI Flowering Effect, and may be manufacturing defects contributed to bigger gaps in Unit 3, but the gaps were redistributed. Therefore, NRC Headquarter Qualified Steam Generator and Thermal-Hydraulic Experts needs to determine the real Root Cause of SONGS SG Degradation. NRC Region IV should not even be holding any discussions with SCE for Restart Of Unit 2, because Southern Californians do not trust their technical ability to make public safety decisions.

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