Arnie Gundersen, Chief Engineer of Fairewinds, demonstrates what has happened inside the replacement steam generators at the site of the San Onofre nuclear generating station in San Diego, California. Arnie shows that steam generator tube vibrations have caused extensive damage due to design changes between the original and replacement generator tubes.
San Onofre’s Steam Generator Failures Could Have Been Prevented | Fairewinds Energy Education
Southern California Edison’s four replacement steam generators at their San Onofre Nuclear Generating Station failed in less than two years of operation, while the original equipment operated for 28 years. Fairewinds has been analyzing the data in order to determine how such an expensive investment could fail so quickly.
In June of 2006 Edison informed the NRC that the replacement steam generators to be manufactured by Mitsubishi would be fabricated to the same design specifications as the original San Onofre Combustion Engineering (CE) steam generators. According to Nuclear Engineering International, Edison has admitted that this was a strategic decision to avoid a more thorough license amendment and review process.
At SONGS, the major premise of the steam generator replacement project was that it would be implemented under the lOCFR50.59 rule, that is, without prior approval by the US Nuclear Regulatory Commission (USNRC). To achieve this goal, the RSGs were to be designed as 'in-kind' replacement for the OSGs in terms of form, fit and function.
Fairewinds finds that there are numerous changes to the San Onofre steam generators that are not like-for-like or “in-kind”.
Furthermore, the facts reviewed by Fairewinds makes it clear that if Edison had informed the NRC that the new steam generators were not like-for-like, the more thorough NRC licensing review process would have likely identified the design problems before the steam generators were manufactured.
Finally, Fairewinds finds that tube plugging is not the solution to the vibration problem and that the damaged steam generators will still require major modifications with repair and outage time that could last more than 18 months if Edison and Mitsubishi are even able to repair these faulty designed steam generators. However, Fairewinds finds that the safest long-term action is the replacement of the San Onofre steam generators.