05000387/FIN-2012005-04
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Finding | |
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| Title | Improper Stress Intensification Factor Results in RCS Pressure Boundary Leak |
| Description | A self-revealing Green NCV of 10 CFR 50 Appendix B, Criteria III, Design Control, was identified related to a leak on the Unit 1 A reactor recirculation pump suction line decontamination flange weld. Specifically, PPL personnel used an incorrect value for stress intensification factor in the vibration analysis in 2004 to support an extended power uprate (EPU). When the correct stress intensification factor was applied, American Society of Mechanical Engineers (ASME) OM-3 code limits for endurance and fatigue stress were exceeded. The weld failure resulted in pressure boundary leakage in excess of TS 3.4.4 limits from approximately June 16 through 19, 2012. PPL staff entered the problem in the PPL corrective action program (CAP) as CR 1589390, repaired and modified the flange line, and revised the calculation. The inspectors reviewed the performance deficiency using NRC IMC 0612, Appendix B, Issue Screening, and determined to be more than minor because it affected the Initiating Events cornerstone attribute of design control. The issue adversely affected the associated 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. The finding was evaluated using Section A of IMC 609, Appendix A, Exhibit 1, Initiating Events Screening Questions. Since the finding result could not have reasonably exceeded the leak rate for a small loss of coolant accident (LOCA) and did not likely affect other systems used to mitigate a LOCA resulting in a total loss of their function (e.g., inter-facing system LOCA), the finding screened to very low safety significance (Green). This finding was determined to not be indicative of current performance because the deficiency occurred in 2004 and procedures and training are in place that would have precluded the issue. Therefore, no cross-cutting aspect is assigned. |
| Site: | Susquehanna  |
|---|---|
| Report | IR 05000387/2012005 Section 4OA2 |
| Date counted | Dec 31, 2012 (2012Q4) |
| Type: | NCV: Green |
| cornerstone | Initiating Events |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71152 |
| Inspectors (proximate) | A Bolger A Rosebrook C Lally J Caruso J Furia J Greives J Richmond M Gray P Finney R Edwards R Rolph |
| INPO aspect | |
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Finding - Susquehanna - IR 05000387/2012005 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Susquehanna) @ 2012Q4
Self-Identified List (Susquehanna)
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