05000261/FIN-2011002-05
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Finding | |
|---|---|
| Title | None |
| Description | TS 3.5.3, ECCS Shutdown, required immediate actions to restore One ECCS RHR train to operable status when the required train was inoperable. Contrary to this on September 27, 2008, during the shutdown and on November 2, 2008, during the startup from a refueling outage RHR temperature was above the 250 degree Fahrenheit temperature limit for a combined total of approximately 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br />. The cause of the violation was an inadequate review of operating experience which had identified the potential for voiding in the RHR system when responding to a loss of coolant accident if RHR temperature is too high. The licensee entered the issue into the corrective action program as NCR 367186. The finding was evaluated in accordance with IMC 0609.04, Significance Determination Process (SDP) Phase 1 screening worksheets. Because it represented an actual loss of safety function of both trains of RHR, an SDP Phase 2 analysis was attempted. The inspectors determined that the finding could not be adequately modeled using the Phase 2 process. An SDP Phase 3 analysis was performed for the deficiency using an at power (vice a shutdown evaluation) because the performance deficiency would manifest itself immediately after shutting down the unit or immediately preceding returning to power. The NRC\'s risk model was modified to reflect the total loss of RHR pumping capability due to either voiding of the pump suctions or the associated water-hammer event. The resulting analysis, including the risk contribution due to external sources, was less than 1E-6/year and the finding is GREEN. The dominant cut sets were medium and small break loss of coolant accidents that proceed immediately to core damage due to the lack of low pressure injection |
| Site: | Robinson  |
|---|---|
| Report | IR 05000261/2011002 Section 4OA7 |
| Date counted | Mar 31, 2011 (2011Q1) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | Licensee-identified |
| Inspection Procedure: | |
| Inspectors (proximate) | J Hickey R Musser E Lea C Scott W Deschaine M Riches |
| INPO aspect | |
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Finding - Robinson - IR 05000261/2011002 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Robinson) @ 2011Q1
Self-Identified List (Robinson)
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