05000361/FIN-2012010-03
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Finding | |
|---|---|
| Title | Licensee-Identified Violation |
| Description | Title 10 CFR Part 50, Appendix B, Criterion III, Design Control, requires, in part, that design control measures shall be established to provide for verifying or checking the adequacy of design, such as by the performance of design reviews, by the use of alternate or simplified calculational methods, or by the performance of a suitable testing program. Contrary to the above, on December 11, 2007, and July 3, 2008, the licensee failed to establish design control measures during the review of Mitsubishis design Calculations SO23-617-1-C749 and SO23-617-1-C157, respectively, to verify or check the adequacy of the retainer bars design with respect to the susceptibility of the smaller diameter retainer bars to flow-induced vibration. Specifically, the licensee failed to ensure that there was sufficient analytical effort in the design methodology of the anti-vibration bar assembly to support the conclusion that tube wear would not occur as a result of contact with the retainer bars due to flow-induced vibration. Consequently, the smaller diameter retainer bars vibrated during normal operation causing wear on the adjacent tubes, that challenged the integrity of the reactor coolant system boundary. The inspectors determined that the licensees failure to verify the adequacy of the retainer bar design as required by Procedure SO123-XXIV-37.8.26 was of very low safety significance (Green) based on Inspection Manual Chapter 0609.04, Phase 1 Initial Screening and Characterization of Findings, and Inspection Manual Chapter 0609, Appendix A, The Significance Determination Process (SDP) for Findings At-Power, because the finding did not involve a degraded steam generator tube condition where one tube could not sustain 3 times the differential pressure across a tube during normal full power, steady state operation and none of the replacement steam generators violated the accident leakage performance criterion in plant Technical Specifications as a result of the retainer bar vibration. The licensee also implemented actions to inspect all affected tubes in Unit 2 and 3 and remove from service all those tubes surrounding the smaller retainer bars that could wear due to vibration of the retainer bar. Because this violation has been determined to be of very low safety significance (Green) and has been entered in the licensees corrective action program as Nuclear Notification NN 201843216, it will be dispositioned as a non-cited violation in accordance with Section 2.3.2 of the NRCs Enforcement Policy. |
| Site: | San Onofre  |
|---|---|
| Report | IR 05000361/2012010 Section 4OA7 |
| Date counted | Sep 30, 2012 (2012Q3) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | Licensee-identified |
| Inspection Procedure: | |
| Inspectors (proximate) | B Hagar G Werner J Reynoso J Rivera-Ortiz |
| INPO aspect | |
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Finding - San Onofre - IR 05000361/2012010 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (San Onofre) @ 2012Q3
Self-Identified List (San Onofre)
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