05000482/FIN-2011005-02
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Finding | |
|---|---|
| Title | Failure to Account for RCP Seal Injection in Safety Analysis for Inadvertent Safety Injection |
| Description | On June 13, 2011, the inspectors identified a non-cited violation of 10 CFR, Part 50, Appendix B, Criterion XVI, for an inadequate safety analysis of inadvertent operation of the emergency core cooling system. The inspectors identified that Updated Safety Analysis Report, Chapter 15.5.1, Inadvertent Operation of the ECCS, was inadequate because it did not account for the effects of reactor coolant pump seal injection flow. Since the pressurizer would be nearly full when operators terminate safety injection flow, the added volume would eventually overfill the pressurizer. Relief of liquid by the pressurizer safety valves is not permissible by the Updated Safety Analysis Report and the Standard Review Plan because the event could then propagate to a loss of coolant accident. The inspectors also identified that Wolf Creek needed an additional time critical operator action to re-establish letdown to reduce pressurizer level. The inspectors identified that operators were not tested on these actions in the simulator. Wolf Creek evaluations in 2011 did not find the error in the safety analysis or operator training. Wolf Creek planned to re-perform this safety analysis and has changed its simulator training to include timing of safety injection termination and establishing letdown. This issue was entered in the corrective action program as condition report 40410. Failure to identify an inadequate safety analysis for inadvertent safety injection while comparing the plant response during an actual inadvertent safety injection to the safety analysis was a performance deficiency. This finding was more than minor because it impacted the design control attribute of the Initiating Events Cornerstone and affected the cornerstone objective to limit the likelihood of those events that upset plant stability and challenge critical safety functions during shutdown as well as power operations. The inspectors used Inspection Manual Chapter 0609.04, \\\"Phase 1 - Initial Screening and Characterization of Findings,\\\" and determined that the issue required a Phase 3 analysis because it involved a primary system loss of coolant accident initiator that could exceed the technical specification limit for allowable leakage. The senior reactor analyst calculated a bounding incremental core damage probability of 9.0E-7 per year or very low safety significance. This finding had a cross-cutting aspect in the area of problem identification and resolution associated with problem evaluation. Specifically, condition reports 34964 and 35700 did not identify the issue although they were tasked with evaluating the March 19 event against the safety analysis. |
| Site: | Wolf Creek  |
|---|---|
| Report | IR 05000482/2011005 Section 1R18 |
| Date counted | Dec 31, 2011 (2011Q4) |
| Type: | NCV: Green |
| cornerstone | Initiating Events |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71111.18 |
| Inspectors (proximate) | R Deese G Guerra P Elkmann L Willoughby N O'Keefe C Long C Peabody C Steely D Strickland N Makris |
| CCA | P.2, Evaluation |
| INPO aspect | PI.2 |
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Finding - Wolf Creek - IR 05000482/2011005 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Wolf Creek) @ 2011Q4
Self-Identified List (Wolf Creek)
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