05000361/FIN-2012009-02
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Finding | |
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| Title | Failure to Verify Adequacy of Thermal-Hydraulic and Flow-Induced Vibration Design for the Unit 3 Replacement Steam Generators |
| Description | The inspectors identified an apparent violation of 10 CFR Part 50, Appendix B, Criterion III, Design Control, for the failure to verify the adequacy of the thermal-hydraulic and flow-induced vibration design of the Unit 3 replacement steam generators, which resulted in significant and unexpected steam generator tube wear after 11 months of operation and an associated apparent violation of Technical Specification 5.5.2.11, Steam Generator Program, loss of tube integrity on Unit 3 Steam Generator 3E0- 88. The licensee initiated Nuclear Notification NN 202447265 to address this issue in the corrective action program. Southern California Edison revised the thermal-hydraulic code of record and ensured that the code was in accordance with ASME guidance. Subsequently, on June 7, 2013, Southern California Edison announced that Units 2 and 3 would be permanently shut down. This finding is more than minor because it is associated with the equipment performance attribute of the Initiating Events Cornerstone and adversely affected the cornerstone objective of limiting the likelihood of those events that upset plant stability and challenge critical safety functions during shutdown as well as power operations. Specifically, the failure to verify the adequacy of the thermal-hydraulic and flow-induced vibration design resulted in excessive and rapid tube wear due to fluid elastic instability, which challenged the structural integrity of the tubes to perform their pressure boundary function. The inspectors used NRC Inspection Manual Chapter 0609, Attachment 4 and Appendix A, to evaluate the significance of this finding. In accordance with Exhibit 1 of Inspection Manual Chapter 0609, Appendix A, the inspectors determined that this finding required evaluation in accordance with Inspection Manual Chapter 0609, Appendix J, because the finding involved a degraded steam generator tube condition where one tube could not sustain three times the differential pressure across a tube during normal full power, steady-state operation. In accordance with Inspection Manual Chapter 0609, Appendix J, this finding required a detailed risk analysis, since it involved two or more tubes that could not sustain three times the normal differential pressure and one or more steam generators that violated accident-induced leakage performance criterion. A Phase 3 analysis was completed using the San Onofre SPAR model, Revision 8.22, assuming average test and maintenance, and a truncation limit of 1.0E-11. Based on the best available information, the performance deficiency was preliminarily characterized as a finding of low to moderate safety significance (White). The final significance of this finding is to be determined. No cross-cutting aspect was assigned because this performance deficiency occurred in the 2005 to 2008 timeframe. Substantial management and personnel changes have occurred, including taking actions to address a chilled work environment and other safety culture issues. The NRC determined that the performance behavior that existed at that time is not indicative of current performance |
| Site: | San Onofre  |
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| Report | IR 05000361/2012009 Section 4OA5 |
| Date counted | Jun 30, 2013 (2013Q2) |
| Type: | Violation: White |
| cornerstone | Initiating Events |
| Identified by: | NRC identified |
| Inspection Procedure: | |
| Inspectors (proximate) | A Howell C Thurston E Murphy G Warrier G Werner J Billoue J Reynoso M Bloodgood R Lantz V Dhirg Warnickr Evans R Kellar |
| Violation of: | 10 CFR 50 Appendix B Criterion III, Design Control Technical Specification |
| INPO aspect | |
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Finding - San Onofre - IR 05000361/2012009 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (San Onofre) @ 2013Q2
Self-Identified List (San Onofre)
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