05000395/FIN-2011005-03
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Finding | |
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| Title | Licensee-Identified Violation |
| Description | 10 CFR 50, Appendix B, Criterion III, Design Control states, in part, that measures are established to ensure applicable regulatory requirements and design basis are correctly translated into procedures. Contrary to this, October 13, 2009, the licensee identified that they failed to have adequate measures in place to ensure that correct design bases were translated into procedures for RHR system operation. This issue is more than minor because it impacted the mitigating systems cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences and the attribute of procedure quality. The SDP screening determined that the PD affected both short term and long term core decay heat removal during shutdown and was evaluated with NRC Inspection Manual Chapter procedure 0609 Appendix G Shutdown Operations Significance Determination Process . Since the PD affected both trains of the Residual Heat Removal (RHR) System, the finding increased the likelihood that a loss of decay heat removal would occur during shutdown and a phase 3 SDP evaluation was performed by a regional SRA. A bounding analysis was performed assuming a conditional core damage probability of 1.0 for any loss of coolant (LOCA) or steam generator tube rupture (SGTR) initiators occurring during the exposure period. The analysis assumed a reduction in LOCA and SGTR pipe rupture frequencies of 10% of nominal for the exposure at shutdown conditions due to the reduced pressures. The exposure period was 4.8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> over a three year period. No recovery was assumed in the bounding analysis. The dominant sequence would be a LOCA or SGTR at Modes 3/4 with a loss of both RHR pumps due to flashing at the suction leading to core damage due to a loss of core heat removal. The risk was mitigated by the short exposure period. The result of the phase 3 SDP analysis was an increase in core damage frequency < 1E-6 a Green finding of very low safety significance. This issue is in the licensees CAP as CR-09-03980. |
| Site: | Summer  |
|---|---|
| Report | IR 05000395/2011005 Section 4OA7 |
| Date counted | Dec 31, 2011 (2011Q4) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | Licensee-identified |
| Inspection Procedure: | |
| Inspectors (proximate) | J Reece M Speck E Lea G Mccoy E Coffman |
| INPO aspect | |
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Finding - Summer - IR 05000395/2011005 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Summer) @ 2011Q4
Self-Identified List (Summer)
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