05000305/FIN-2012005-08
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Finding | |
|---|---|
| Title | Licensee-Identified Violation |
| Description | Technical Specification 3.5.2, Emergency Core Cooling System (ECCS), Action, Limiting Condition for Operation, requires, in part, that two ECCS trains shall be Operable while in Mode 1. Contrary to the above, from December 7, 2011, through February 29, 2012, the B SI pump was not operable, because the associated SI pump breaker 1-606 installed on December 7, 2011, did not function properly due to a bent main charging shaft, while the reactor was in Mode 1. Upon discovery of the condition during the scheduled Technical Specification SR test, the licensee restored the system to an operable status through replacement of the SI pump B breaker. The inspectors determined the violation could be evaluated using the SDP in accordance with IMC 0609, Significance Determination Process, Attachment 0609.04, Initial Characterization of Findings, and Appendix A, The Significance Determination Process (SDP) for Findings At-Power Exhibit 2, Mitigating Systems Screening Questions, effective July 1, 2012. The inspectors answered Yes to the screening question 3 that stated the finding represented an actual loss of function of at least a single train for greater than its allowed Technical Specification allowed outage time, in this case 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. Therefore, the finding required a detailed risk evaluation by the Region III Senior Reactor Analyst (SRA). The SRA determined that the failure would result in failure of the high pressure recirculation mode for SI pump B. The SRA performed the detailed risk evaluation using the Kewaunee SPAR Model Version 8.20, SAPHIRE Version 8.0.8.0. The exposure time was 84 days. The model was run by setting the basic event representing failure of motor-operated valve RHR-299B to True. Setting failure of this valve to True represents failure of the flowpath from the discharge of residual heat removal (RHR) pump B to the suction of SI pump B, thus failing the B train of the high pressure recirculation mode of SI with common cause potential for the A train as well. The resultant delta CDF was 4.13E-7/yr. This represents internal events risk with the dominant sequence involving a loss of offsite power initiating event, failure of secondary cooling, and failure of high pressure recirculation. Regarding external events risk, the SRA used the external event features of the Kewaunee SPAR model to determine the additional risk for the finding due to initiating events such as fires, floods, and seismic events. The SRA performed a similar analysis as that above for external events only. The resultant delta CDF was 1.4E-7 predominantly due to fire. The total delta CDF was the sum of the internal and external event risk, or 5.6E-7. Regarding the potential risk contribution due to Large Early Release Frequency (LERF), The SRA used IMC 0609 Appendix H, Containment Integrity Significance Determination Process. Kewaunee Station is a 2-loop Westinghouse PWR with a large dry containment. Sequences important to LERF include steam generator tube rupture events and inter-system LOCA events. These were not the dominant core damage sequences for this finding. The SRA determined that the risk due to internal and external events, and LERF to be of very low safety significance (GREEN). The licensee documented this violation in CR 0190063 and conducted an apparent cause determination. The licensee took immediate corrective actions upon discovery to restore the B SI train. At the end of the inspection period, the license continued to implement long term corrective actions from the causal evaluation. |
| Site: | Kewaunee  |
|---|---|
| Report | IR 05000305/2012005 Section 4OA7 |
| Date counted | Dec 31, 2012 (2012Q4) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | Licensee-identified |
| Inspection Procedure: | |
| Inspectors (proximate) | J Beavers V Myers K Carrington D Mcneil R Winter K Riemer J Jandovitz C Moore J Laughlin R Krsek K Barclay |
| INPO aspect | |
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Finding - Kewaunee - IR 05000305/2012005 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Kewaunee) @ 2012Q4
Self-Identified List (Kewaunee)
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