05000458/FIN-2011008-02
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Finding | |
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| Title | Failure to Use Conservative Design Assumptions in the Ultimate Heat Sink Inventory Calculation |
| Description | The team identified a Green, noncited violation of 10 CFR Part 50, Appendix B, Criterion III, Design Control, which states, in part, Measures shall be established to assure that applicable regulatory requirements and the design basis are correctly translated into specifications, drawings, procedures, and instructions. Specifically, prior to October 27,2011, the licensee failed to assure that the design basis information for expected heat loads to the ultimate heat sink was correctly translated into the ultimate heat sink 30-day inventory analysis. The analysis used a less conservative, frictionless form of the conservation of energy equation to determine heat load in the standby service water system during a 30-day design basis event. This finding was entered into the licensee\'s corrective action program as Condition Reports CR-RBS-2011-07430 and CR-RBS-2011-07654. The team determined that the failure to correctly translate expected heat loads into the ultimate heat sink inventory analysis was a performance deficiency. The finding was more than minor because it was associated with the design control attribute of the Mitigating Systems Cornerstone and adversely affected the cornerstone objective of ensuring availability, reliability, and capability of systems needed to respond to undesired consequences. Specifically, the neglect of friction heat load in the ultimate heat sink analysis system resulted in a condition where there was reasonable doubt on the operability of a system to meet its 30-day mission time without a makeup water source. In accordance with NRC Inspection Manual Chapter 0609, Attachment 4, Phase 1 - Initial Screening and Characterization of Findings, the finding was determined to have very low safety significance (Green) because it was a design or qualification deficiency confirmed not to result in a loss of operability or functionality, loss of a system safety function, loss of a single train for greater than technical specification allowed outage time, loss of one or more non-technical specification risk significant equipment for greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, and did not screen as potentially risk significant due to seismic, flooding, or severe weather. Specifically, the licensee\'s revised analysis to determine operability removed overly conservative assumptions for operating the low pressure core spray pump for 30 days to account for the friction heat load added to the system. The finding has a crosscutting aspect in the area of problem identification and resolution, corrective action program component, because the licensee failed to thoroughly evaluate problems such that the resolutions address cause and extent of condition |
| Site: | River Bend  |
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| Report | IR 05000458/2011008 Section 1R21 |
| Date counted | Dec 31, 2011 (2011Q4) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.21 |
| Inspectors (proximate) | K Clayton G George T Farnholtz S Makor N Greca C Edwards J Braisted B Latta |
| CCA | P.2, Evaluation |
| INPO aspect | PI.2 |
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Finding - River Bend - IR 05000458/2011008 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (River Bend) @ 2011Q4
Self-Identified List (River Bend)
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