05000255/FIN-2012012-03
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Finding | |
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| Title | Potential Failure to Prevent Recurrence of a Significant Condition Adverse to Quality |
| Description | On August 12, 2012, the licensee shutdown the reactor to investigate the source of elevated PCS unidentified leakage. During a containment walk down post shutdown it was discovered the source of the leakage was the housing on CRDM-24. The leak was classified as pressure boundary leakage. An event similar to this occurred in 2001 when the licensee discovered a steam leak in the housing of CRDM-21 which was also classified as pressure boundary leakage. Title 10 of the Code of Federal Regulations, Part 50, Appendix B, Criterion XVI, states, In the case of significant conditions adverse to quality, the measures shall assure that the cause of the condition is determined and corrective action taken to preclude repetition. This 2001 pressure boundary leakage event was classified by the licensee as a significant condition adverse to quality. Therefore, as part of the developed corrective action, the need to prevent recurrence was specified. The root cause of the 2001 event was determined to be TGSCC due to susceptible material, fabrication flaws and inherent stresses in the weld due to the design of the component. The corrective actions to prevent recurrence established by the licensee included making changes to the design, fabrication, and material of this component. Specific attention was paid to the pressure retaining welds. The location of the current leak was not in proximity to the pressure retaining welds; therefore, susceptibility in this area was not considered. The root cause evaluation for the current failure was ongoing at the end of the inspection; therefore, it cannot be definitively concluded that the failure mechanism for the current leak is the same as the cause identified in 2001 and the corrective actions to prevent recurrence were inadequate. Although the method of crack propagation was the same, TGSCC, the initiation mechanism for the crack is not yet known. There is no current safety issue as the housing was replaced and the current crack propagation assessments and extent of condition reviews performed provide reasonable assurance a through-wall crack will not occur. (URI 05000255/2012012-03, Potential Failure to Prevent Recurrence of a Significant Condition Adverse to Quality) |
| Site: | Palisades  |
|---|---|
| Report | IR 05000255/2012012 Section 4OA5 |
| Date counted | Sep 30, 2012 (2012Q3) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 93812 |
| Inspectors (proximate) | E Sanchez-Santiago C Phillips A Shaikhc Zoias Sheldon M Phalen J Lennartz K Walton M Jones T Taylor A Scarbeary E Sanchez-Santiago D Alley |
| INPO aspect | |
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Finding - Palisades - IR 05000255/2012012 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Palisades) @ 2012Q3
Self-Identified List (Palisades)
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