05000338/FIN-2015003-01
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Finding | |
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| Title | Licensee-Identified Violation |
| Description | The following violation of very low safety significance (Green) was identified by the licensee and is a violation of NRC requirements which meets the criteria of the NRC Enforcement Policy, being for dispositioned as a NCV: Technical Specification (TS) 3.7.5 for Auxiliary Feedwater System requires that three AFW trains be operable in Modes 1, 2, and 3. TS Action C.1 also requires that if two AFW trains are inoperable in Modes 1, 2, or 3, a required action places both units in Mode 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. Contrary to the above, on May 8, 2015, the licensee discovered that two motor-driven AFW (MDAFW) trains were inoperable for more than 12.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> and TS Action C.1 was not completed. Using Manual Chapter 0609, Attachment 4, Initial Characterizations of Findings, Table 2, dated July 1, 2012 and Manual Chapter 0609, Appendix A, Significance Determination Process (SDP) for Findings at-Power, Exhibit 2, dated July 1, 2012, the inspectors determined a detailed risk evaluation was required because the finding represented both MDAFW out of service exceeding its allowed outage. A Detailed SDP risk evaluation was performed by a regional SRA in accordance with the guidance of NRC IMC 0609, Appendix A, using the latest NRC North Anna SPAR risk model. The major analysis assumptions included: a one day exposure period, both MDAFW pumps assumed to fail to run with no ventilation available, and no recovery credit applied, for a twenty four hour mission time. A sensitivity analysis was run with a seven day mission time and recovery credit allowed. Both analyses determined the increase in CDF due to the performance deficiency was < 1.0E-6/year a GREEN finding of very low safety significance. The dominant sequence for both analyses was a Reactor Trip Initiator with a Loss of the Condenser Heat Sink (IE-LOCHS), failure of Main Feedwater (MFW), failure of AFW, and failure of the operator to implement Feed and Bleed cooling leading to core damage. MFW was failed due to loss of condensate. MDAFW was failed due to the PD and the Turbine Driven AFW (TDAFW) was a random failure to run. The risk was mitigated by the availability of TDAFW and the short exposure period. This issue was entered into the licensees CAP as CR579372, and resulted in Apparent Cause Evaluation, ACE19928, that determined additional training was required for licensee personnel to develop sensitivity to auxiliary equipment required to maintain operability of safety related systems that is not specifically mentioned in the Technical Specifications. |
| Site: | North Anna  |
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| Report | IR 05000338/2015003 Section 4OA7 |
| Date counted | Sep 30, 2015 (2015Q3) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | Licensee-identified |
| Inspection Procedure: | |
| Inspectors (proximate) | A Masters G Kolcum J Parent L Mckown T Skaggs-Ryan |
| Violation of: | Technical Specification |
| INPO aspect | |
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Finding - North Anna - IR 05000338/2015003 | ||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (North Anna) @ 2015Q3
Self-Identified List (North Anna)
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