SONGS Steam Generator Tube Degradation
In response to an Event Notification Report, dated January 31, 2012, the U.S. Nuclear Regulatory Commission (NRC) modified its regulatory oversight of San Onofre Nuclear Generating Station (SONGS) Units 2 & 3, to address unexpected degradation of tubes in the newly installed steam generators after approximately 1.7 and 1 effective full power years of operation, respectively. The purpose of this special oversight was to assess the licensee's evaluation of the cause(s) of unexpected tube degradation, and verify that the licensee's corrective actions were appropriate to ensure the integrity of the steam generators and to protect the health and safety of the public and the environment.
On March 27, 2012, the NRC issued a Confirmatory Action Letter (CAL) to SCE, to confirm the actions the licensee committed to take prior to returning Units 2 and 3 to power operation. In its October 3, 2012, response to the CAL (addressing Unit 2 only), SCE indicated it would operate Unit 2 at no more than 70 percent power for no more than 150 days before conducting the next set of inspections of that unit's steam generator tubes.
SCE submitted a license amendment request for SONGS Unit 2 on April 5, 2013, as supplemented on April 9, 2013. SCE requested changes to support restart of SONGS Unit 2. The proposed license amendment would restrict Unit 2 operation to no more than 70 percent of the maximum authorized power level and would revise the Technical Specification requirements for steam generator tube integrity to reflect this change. SCE requested that these changes remain in effect for the duration of Unit 2, Cycle 17; a period of roughly 18 to 24 months of plant operation. This change would not relieve SCE of any of its obligations to demonstrate and maintain the integrity and operability of the SONGS steam generator tubes for the power level at which the reactor would operate.
Issuance of the license amendment would not authorize restart of SONGS Unit 2. The NRC will not permit SONGS Unit 2 to restart until SCE has met the terms of the CAL, the NRC has completed its thorough review of these actions, and the NRC has concluded that the licensee can operate the plant without undue risk to public health and safety and in compliance with NRC regulations. Before making a decision regarding restart of SONGS Unit 2, the NRC staff will complete all of the following actions:
- All inspection activities related to the licensee's corrective actions for Unit 2, as specified in the Confirmatory Action Letter (to be documented in an inspection report);
- Technical review of the safety bases for Unit 2 steam generator tube integrity provided in the licensee's October 3, 2012, CAL response and return to service report, as supplemented (to be documented in a Technical Evaluation Report); and
- Review of SCE's April 5, 2013, license amendment request for Unit 2, as supplemented (will be documented in a staff Safety Evaluation).
When the NRC is ready to make a decision regarding the restart of Unit 2, it will also make appropriate notifications to the Atomic Safety and Licensing Board (ASLB) presiding officer. In addition, a public meeting will be held in the vicinity of the plant to discuss the results/status of the staff's reviews and inspections prior to making a decision regarding restart.
Note that before these actions could be completed, SCE made the decision to permanently retire SONGS Units 2 & 3 and enter the decommissioning process.
For more information, see the following topics:
- Background Information
- Summary of Event and Plant Conditions
- Augmented Inspection Team
- Enhanced Oversight
- Unit 2 Steam Generators
- Unit 3 Steam Generators
- Steam Generator Tube Wear Data
- SONGS Unit 3 Failed In-situ Pressure Tests
- Decommissioning FAQs
- Decommissioning Fact Sheet
- San Onofre (NRC Blog)
- NRC SONGS Lessons Learned Report
- Confirmatory Action Letter
- License Amendment Request (04/05/2013)
- Past Milestones