05000482/FIN-2012002-01
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Finding | |
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| Title | Inadequate Procedure Causes Lift of Relief Valve and Reactor Coolant Leak During Shutdown |
| Description | The inspectors reviewed a self-revealing non-cited violation of 10 CFR 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, for a procedure that failed to restore the reactor coolant pump seal return flow path prior to raising reactor coolant system pressure, which caused the seal return relief valve to lift. During shutdown, reactor coolant pump seal return valve BGHV8100 was shut. On February 12, 2012, Wolf Creek was in Mode 5 with a water-filled (solid) pressurizer at 94 psig. After pressurizer power operated relief valve maintenance, Wolf Creek raised reactor coolant system pressure to 250 psig. With no return path, the relief valve lifted at 150 psig for 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> before operators noted an unexplained steady increase in pressurizer relief tank level and re-established the return flow path. Wolf Creek procedures were written to transition straight to refueling, and did not include consideration for maneuvering the plant in Mode 5. This led to shutting valve BGHV8100 without instructions to reopen it before exceeding 150 psig. Wolf Creek subsequently added procedure steps and precautions to reopen the seal return path in Mode 5. The inspectors calculated that approximately 760 gallons of reactor coolant were lost to the relief tank. This issue was placed in the corrective action program as condition report 49021. Failure to align the reactor coolant pump seal return flow path prior to raising reactor coolant system pressure above the relief valve setpoint, creating a leak path, was a performance deficiency. The inspectors determined that this finding impacted the Initiating Events Cornerstone and its objective to limit the likelihood of events that upset plant stability and challenge safety functions during shutdown. Specifically, it impacted the configuration control attribute of shutdown equipment lineup which created an unmonitored intersystem leak. The inspectors used Inspection Manual Chapter 0609, Appendix G, Attachment 1, checklist 4 (cold shutdown, level in the pressurizer, time to boil >2 hours) to evaluate the significance of this finding. A Phase 2 analysis was not needed because the level of inventory was terminated when the normal path was opened and the relief valve reseated. The leak would have terminated itself if the reactor coolant system drained itself to below the pump seal. The finding did not affect reactor coolant system level indication, affect the ability to terminate the leak path, affect the ability to add inventory, or affect the ability to recover residual heat removal if it was lost. Therefore, the finding was determined to be of very low safety significance. The inspectors identified the cause of the finding had a human performance cross-cutting aspect in the area of resources. Specifically, complete and accurate procedures were not provided because Procedure GEN 00-006 did not contain guidance to establish the seal return flow path prior to raising reactor coolant system pressure above 150 psig |
| Site: | Wolf Creek  |
|---|---|
| Report | IR 05000482/2012002 Section 1R20 |
| Date counted | Mar 31, 2012 (2012Q1) |
| Type: | NCV: Green |
| cornerstone | Initiating Events |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71111.2 |
| Inspectors (proximate) | C Peabody Z Hollcraft G Callaway J Melfi N O'Keefe C Long |
| CCA | H.7, Documentation |
| INPO aspect | WP.3 |
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Finding - Wolf Creek - IR 05000482/2012002 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Wolf Creek) @ 2012Q1
Self-Identified List (Wolf Creek)
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