05000382/FIN-2014007-07
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Finding | |
|---|---|
| Title | Failure to Properly Evaluate Main Steam Isolation Valve Weak Link |
| Description | The team reviewed a self-revealing Green non-cited violation of 10 CFR Part 50, Appendix B, Criterion III, Design Control, which states, in part, that design control measures shall 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. Specifically, prior to the failure of main steam isolation valve MS-124A on January 5, 2013, the licensee failed to have an adequate weak-link evaluation for the main steam isolation valves. In response to this event, the licensee performed a seismic weak-link evaluation of the main steam isolation valves that supported a determination that the valves were operable. This finding was entered into the licensees corrective action program as CR-WF3-2014-05708. The team determined that the failure to evaluate the main steam isolation valve maximum allowed thrust, assuming appropriate values for the structural limitations of the valve and actuator, was a performance deficiency. This performance deficiency was more than minor because it was associated with the design control attribute of the Barrier Integrity cornerstone and adversely affected the cornerstone objective to provide reasonable assurance that physical design barriers (containment) protect the public from radionuclide releases caused by accidents or events. Specifically, the licensee used a non-conservative value for the maximum allowed thrust, and the error resulted in a failure of main steam isolation valve MS-124A, because the allowable nitrogen pressure for the valve actuator was inappropriate. In accordance with Inspection Manual Chapter 0609, Appendix A, The Significance Determination Process (SDP) for Findings At-Power, issued June 19, 2012, Exhibit 3, Barrier Integrity Screening Questions, this finding screened as having very low safety significance (Green) because the finding did not represent an actual open pathway in the physical integrity of reactor containment and did not involve an actual reduction in function of the hydrogen igniters in reactor containment. The team determined that this finding did not have a cross-cutting aspect because the most significant contributor did not reflect current licensee performance. |
| Site: | Waterford  |
|---|---|
| Report | IR 05000382/2014007 Section 1R21 |
| Date counted | Mar 31, 2015 (2015Q1) |
| Type: | NCV: Green |
| cornerstone | Barrier Integrity |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71111.21 |
| Inspectors (proximate) | B Larson E Ruesch G Gardner G Ottenberg P Wagner S Makor |
| Violation of: | 10 CFR 50 Appendix B Criterion III, Design Control |
| INPO aspect | |
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Finding - Waterford - IR 05000382/2014007 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Waterford) @ 2015Q1
Self-Identified List (Waterford)
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