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| Quarter | Site | Title | Description | |
|---|---|---|---|---|
| 05000346/FIN-2010008-01 | 2010Q3 | Davis Besse | Unqualified PT Procedure For CRDM Nozzle Repair Welds | The team identified a Non-Cited Violation (NCV) of 10 CFR Part 50 Appendix B, Criterion IX for the licensees failure to use a nondestructive examination procedure qualified in accordance with applicable Codes and Standards for detection of flaws in control rod drive nozzle repairs. Specifically, the licensee failed to ensure that Procedure 54-ISI-244-10 Liquid Penetrant Examination of Reactor Vessel Head Penetrations from the Inside Surface, contained a maximum time limit for application of water-wash. The licensee issued a procedure change to incorporate a maximum time limit of 10 minutes for the water-wash application time and demonstrated that this wash time was acceptable. This finding was more than minor because if left uncorrected, the failure to use a qualified procedure could become a more significant safety concern. Absent NRC identification, the licensee would not have controlled the maximum times used to wash the penetrant materials off repair weld surfaces. Excessive wash time could have resulted in failure to detect fabrication flaws such as voids and cracks. Undetected cracks returned to service in the repair welds would place the RVCH at increased risk for through-wall leakage and/or nozzle failure. Therefore, this finding adversely affected the Initiating Events Cornerstone objective to limit the likelihood of those events that upset plant stability and challenge critical safety functions. The issue was corrected promptly, no cracks were returned to service, and the team answered no to the Phase I screening question that asked assuming the worst case degradation would the finding result in exceeding the Technical Specification limit for any reactor coolant system leakage. Therefore, the finding screened as having very low safety significance (Green). This finding had a cross-cutting aspect in the area of Human Performance, Work Practices (IMC 0310 (Item H.4(c)) because the licensee did not provide adequate supervisory and management oversight of work activities including contractors such that nuclear safety was supported. Specifically, the licensee failed to provide an adequate oversight in the review and acceptance of the unqualified vendor Procedure 54-ISI-244-10. |
| 05000346/FIN-2010008-02 | 2010Q3 | Davis Besse | Unqualified Weld Repair Applied For CRDM Nozzle No. 4 | The team identified a NCV of 10 CFR Part 50 Appendix B, Criterion IX for the licensees failure to perform repair welding on control rod drive mechanism nozzle No. 4 using a qualified weld procedure. Specifically, the licensee failed to ensure that the weld procedure supplement PS0140-002 controlled heat input to less than that demonstrated in the supporting weld procedure qualification. To restore compliance, the licensee completed a new weld coupon, tested the coupon, and documented the results in a new procedure qualification record. The procedure qualification record recorded heat inputs for the weld coupon that bound the heat input used for the weld repairs completed on CRDM nozzle No. 4 and the weld coupon test results demonstrated the weld properties were acceptable. This finding was more than minor because if left uncorrected, the failure to use a qualified weld procedure could become a more significant safety concern. Absent NRC identification, the licensee would not have completed a Code qualified weld repair on Control Rod Drive Mechanism nozzle No. 4 prior to returning the reactor vessel closure head to service. The repair weld lacked qualification tests to demonstrate that the mechanical properties (toughness, ductility or strength) were adequate, which could have placed the RVCH at an increased risk for through-wall leakage and/or nozzle failure. Therefore, this finding adversely affected the Initiating Events Cornerstone objective to limit the likelihood of those events that upset plant stability and challenge critical safety functions. The issue was corrected promptly, the unqualified repair weld was not placed in service, and the team answered no to the Phase I screening question that asked assuming the worst case degradation would the finding result in exceeding the Technical Specification limit for any reactor coolant system leakage. Therefore, the finding screened as having very low safety significance (Green). This finding had a cross-cutting aspect in the area of Human Performance, Work Practices per IMC 0310 (Item H.4(c)) because the licensee did not provide adequate supervisory and management oversight of work activities including contractors such that nuclear safety was supported. Specifically, the licensee failed to provide an adequate oversight in the review and acceptance of the unqualified vendor weld procedure supplement. |
| 05000346/FIN-2010008-03 | 2010Q3 | Davis Besse | Inadequate Procedure For Viewing of Remote PT on Nozzle No. 61 Repair Welds | The team identified a NCV of 10 CFR Part 50 Appendix B, Criterion V for the licensees failure to provide documented instructions appropriate to the circumstances for the remote visual examination of the final dye penetrant examination completed on repaired nozzle No. 61. Specifically, OI 03-1240857-006 BWOG CRDM Nozzle Top Down Inspection Tooling Operating Instructions, did not include guidance for control of spacer sizes or camera field of view necessary to ensure that the entire examination surface area was viewed. To correct this issue, the procedure was revised to include additional instructions to ensure complete examination coverage with the remote camera system. Additionally, the licensee repeated the examinations on nozzle No. 61 and nine additional nozzles with incomplete examination coverage is finding was more than minor because if left uncorrected, the failure to use an adequate procedure for detecting flaws could become a more significant safety concern. Absent NRC identification, the licensee would not have examined the entire surface of the repaired nozzle No. 61 and nine other nozzles, which could have allowed cracks to go undetected. Undetected cracks returned to service in the repair welds would place the RVCH at increased risk for through-wall leakage and/or nozzle failure. Therefore, this finding adversely affected the Initiating Events Cornerstone objective to limit the likelihood of those events that upset plant stability and challenge critical safety functions. The issue was corrected promptly, weld cracks were not returned to service, and the team answered no to the Phase I screening question that asked assuming the worst case degradation would the finding result in exceeding the Technical Specification limit for any reactor coolant system leakage. Therefore, the finding screened as having very low safety significance (Green). This finding had a cross-cutting aspect in the area of Human Performance, Work Practices per IMC 0310 (Item H.4(c)) because the licensee did not provide adequate supervisory and management oversight of work activities including contractors such that nuclear safety was supported. Specifically, the licensee failed to provide an adequate oversight in that no licensee review was completed for the inadequate vendor Procedure OI 03-1240857-006. |
| 05000346/FIN-2010008-04 | 2010Q3 | Davis Besse | Control Rod Drive Nozzle PWSCC and Pressure Boundary Leakage | On March 12, 2010, during UT of CRDM nozzles, the licensee identified nozzles, which did not meet acceptance criteria. Additionally, during BMV examination of the outer surface of the RVCH, the licensee identified boric acid deposits indicative of RCS leakage. The direct cause of this event was PWSCC of the CRDM nozzles and J-groove welds and the license identified and repaired a total of 24 CRDM nozzles with PWSCC in the nozzle or J-groove welds. Because the PWSCCs identified were well below crack sizes required for nozzle ejection and there was no discernable head wastage, the licensee concluded that this issue was of very low safety significance. The team evaluated the safety significance of this cracking (Section 4OA3.4) and concluded that the cracking was identified early such that plant safety was not challenged. This event was reviewed in-depth by the team as discussed within each section of this report. The NRC determined that past operation with CRDM nozzle leakage was a violation of TS 3.4.13 RCS Operational Leakage and applied enforcement discretion to not issue a violation for this issue as discussed in the following report section. Documents reviewed as part of this inspection are listed in Attachment 1. LER 05000346/2010-002-00 is closed. |
| 05000346/FIN-2010008-05 | 2010Q3 | Davis Besse | Technical Specification (TS) Leakage Requirements | The team reviewed the root cause analysis of the event and RCS leakage data from previous operating cycles, and concluded that the equipment failure (cracked CRDM nozzles) could not have been avoided or detected by the licensees quality assurance program or other related control measures. Therefore, the team concluded that a licensee performance deficiency did not exist for this violation and did not apply to the Significance Determination Process as described in IMC 0609. Although, a quantitative risk-evaluation was not completed, the licensee performed a deterministic evaluation of the safety significance for the PWSCC identified in the CRDM nozzles (Reference LER 05000346/2010-002-00). Because the PWSCC sizes identified in the CRDM nozzles were well below the crack size that would challenge structural integrity and there was no discernable head wastage, the licensee concluded that this issue was of very low safety significance. The team agreed with the licensees assessment that this issue was of very low safety significance. |