05000440/FIN-2013008-03
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Finding | |
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| Title | Lack of Alternate Methods of Decay Heat Removal |
| Description | On May 21, 2004, the A ESW pump became inoperable due to a failure of the uppermost shaft coupling. Technical Specification Limiting Condition for Operation (LCO) 3.7.1, ESW System Divisions 1 and 2, required the licensee to restore operability within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. Because this action could not be met, TS required the licensee to be in Mode 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and Mode 4 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. While performing plant shutdown, LCO 3.4.10, Residual Heat Removal (RHR) Shutdown Cooling System Cold Shutdown, became applicable. It required, in part, two shutdown cooling subsystems operable in MODE 4 when heat losses to the ambient were not sufficient to maintain average reactor coolant temperature below 200oF. Because ESW is the heat sink of shutdown cooling, the A train of shutdown cooling was also inoperable. With one or two shutdown cooling subsystems inoperable, TS 3.4.10, Required Action A.1, required the licensee to verify an alternate method of decay heat removal was available for each inoperable shutdown cooling subsystem within one hour and once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> thereafter. The associated TS Basis described the alternate method as one that re-establishes backup decay heat removal capabilities similar to the requirements of the LCO. However, the licensee was unable to identify an alternate method of decay heat removal to satisfy TS 3.4.10, Required Action A.1. Moreover, during repairs on the ESW A pump, the licensee concluded that sufficient doubt existed regarding the ESW B pump; thus, they declared the pump inoperable. Consequently, the B train of shutdown cooling also became inoperable requiring two alternate methods of decay heat removal available. This incident resulted in an NCV which was documented in IR 05000440/2004011 and Licensee Event Report (LER) 05000440/2004-001. On October 19, 2009, the B ESW pump tripped off due to failure of the motor power supply cable. Again, the licensee was required to perform a plant shutdown by TS 3.7.1, declared the B shutdown cooling train inoperable when TS 3.4.10 became applicable, and was unable to verify an alternate method of decay heat removal within one hour to satisfy TS 3.4.10, Required Action A.1. This incident was captured in the CAP as CR 2009-66216 and resulted in LER 05000440/2009003. Following these two incidents, the licensee installed the Alternate Decay Heat Removal (ADHR) system. During this inspection period, the inspectors reviewed the associated 10 CFR 50.59 evaluation (i.e., Evaluation 05-04712, Installation of ADHR System ) which stated The intent of the ADHR system is to assure TS compliance in MODE 4 by providing an additional alternate decay heat removal option that does not rely upon RHR or ESW. However, the inspectors noted its design was limited to a heat removal rate which bounds the approximate decay heat production rate of the core 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after a scram from sustained 100 percent power. During normal shutdown conditions, the licensee transitions from 100 percent power to MODE 4 in a few hours. For instance, this transition occurred in about five hours during refueling outage 1R13. In addition, the licensee revised procedure ONI-E12-2, Loss of Decay Heat Removal, by adding Attachment 11, Cold Shutdown Decay Heat Removal by Steaming. This attachment contained instructions to establish an alternate method of decay heat removal independent of ESW. However, the attachment included a note stating, It will be necessary to validate the effectiveness of this attachment to maintain or reduce RPV temperature (by Engineering calculation or demonstration) if qualifying this as an alternate decay heat removal method per TS 3.4.9 and 3.4.10. As a result, the inspectors questioned the effectiveness of this approach given it had not been verified. The licensee consequently, performed a calculation that determined Attachment 11 was limited to a heat removal rate which bounds the approximate decay heat production rate of the core three days after a shutdown from sustained 100 percent power. The procedure contained other alternatives but these either relied on ESW or lacked enough capacity to serve as backup methods during periods of high decay heat loads. Based on this information, the inspectors were concerned the plant lacked two alternate methods of decay heat removal that have been verified to be effective should a loss of shutdown cooling result from ESW inoperability while in MODE 4 with high decay heat load. The inspectors were particularly concerned because this condition had occurred in the past at least twice. The licensee captured the inspectors concerns in their CAP as CR 2013-11480. This issue is unresolved pending further review and determination of NRC actions to resolve the issue. |
| Site: | Perry  |
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| Report | IR 05000440/2013008 Section 1R17 |
| Date counted | Sep 30, 2013 (2013Q3) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.17 |
| Inspectors (proximate) | J Cameron J Nance M Doyle M Jones N Feliz-Adorno R Elliott S Bell V Meghani V Meyersn Adornoi Hafeez R Daley J Gilliam |
| INPO aspect | |
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Finding - Perry - IR 05000440/2013008 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Perry) @ 2013Q3
Self-Identified List (Perry)
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