05000285/FIN-2010006-04
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Finding | |
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| Title | Turbine-driven Auxiliary Feedwater Pump Trip Due to Inadequate Design Margin |
| Description | A self revealing noncited violation of 10 CFR, Part 50, Appendix B, Criterion III, Design Control, occurred when the licensee failed to ensure that the design basis of certain structures, systems and components were translated into specifications, drawings, procedures, and instructions when implementing Engineering Change 45105. Specifically, this design change reduced the turbine-driven auxiliary feedwater pumps margin between the pump discharge pressure and the pumps high discharge pressure trip set-point resulting in an April 6, 2009, high pump discharge pressure trip during a scheduled surveillance test start. The licensee entered this issue in their corrective action program as Condition Report CR-2009-1611. The inspectors determined the finding is more than minor because it is associated with the design control attribute of the Mitigating Systems Cornerstone, and adversely affected the cornerstone objective to ensure the availability, reliability and capability of systems that respond to initiating events to prevent undesirable consequences. Using Manual Chapter 0609.04, \"Phase 1 Initial Screening and Characterization of Findings,\" the issue screened as potentially risk significant since the finding represented a loss of system safety function of a single train for greater than the technical specification allowed outage time. The finding required a Phase 2 analysis. When evaluated per Manual Chapter 0609, Appendix A, \"Determining the Significance of Reactor Inspection Findings for At-Power Situations,\" and the Fort Calhoun Phase 2 presolved table item, Turbine-driven Auxiliary Feedwater Pump Fails to Start, the inspectors determined this finding to be potentially risk significant. The finding was forwarded to a senior reactor analyst for review. A Phase 3 analysis was performed and it was determined that the finding was of very low risk significance. The finding has a crosscutting aspect in the area of human performance because the licensee failed to use conservative assumptions in decision making when a nonconservative design margin was approved and implemented on the turbine-driven auxiliary feedwater pump. |
| Site: | Fort Calhoun  |
|---|---|
| Report | IR 05000285/2010006 Section 4OA5 |
| Date counted | Jun 30, 2010 (2010Q2) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 93812 |
| Inspectors (proximate) | J Kirkland D Loveless L Willoughby J Clark M Chambers J Wingebach M Williams |
| Violation of: | 10 CFR 50 Appendix B Criterion III, Design Control |
| CCA | H.14, Conservative Bias |
| INPO aspect | DM.2 |
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Finding - Fort Calhoun - IR 05000285/2010006 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Fort Calhoun) @ 2010Q2
Self-Identified List (Fort Calhoun)
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