Southern California Edison (SCE) participated in the first of a series of public meetings hosted by the Nuclear Regulatory Commission (NRC) on the evening of June 18 in San Juan Capistrano.
After completing more than 60,000 tests on the steam generator tubes at the San Onofre Nuclear Generating Station (SONGS) Units 2 and 3, and performing significant analysis of the test results, SCE executives confirmed that the cause of the unexpected tube-to-tube wear is “fluid elastic instability” or excessive tube vibration.
“Our overriding and paramount interest is the health and safety of the public and our employees,” said Senior Vice President and Chief Nuclear Officer Pete Dietrich for SONGS. “We have focused on making safe decisions since the onset of the tube leak and we will continue to do so. There is no timeline on safety.”
The purpose of the NRC meetings is to update the public and surrounding communities on the progress of the SONGS outage, and answer questions and concerns from the audience. SCE provided comprehensive details on the status of the plant investigations and testing results. This included receiving both input and challenges to the plant engineers’ conclusions from a team of thermal hydraulics and steam generator design experts from around the world, which is still ongoing.
The NRC clarified several outstanding issues from the public, including that the agency was aware of all design modifications made by SCE during the steam generator replacement process.
The utility has the following outstanding items to address:
- Following up on any remaining information requests from the NRC’s Augmented Inspection Team for completion of its inspection activities;
- Developing the additional information needed to respond to the NRC’s Confirmatory Action Letter; and
- Working with Mitsubishi Heavy Industries, the steam generator manufacturer, and other steam generator vendors to determine appropriate intermediate and long-term solutions to the problem.
SCE remains committed to keeping the public informed and Monday night’s interaction was yet another important step in that process. Both units will remain shut down until SCE and the NRC are satisfied that they are safe to operate.
Unit 2 was taken out of service Jan. 9 for a planned outage. Unit 3 was safely taken off line Jan. 31 after station operators detected a leak in a steam generator tube.