05000416/FIN-2012005-07
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Finding | |
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| Title | |
| Description | The inspectors identified a non-cited violation of 10 CFR 50, Appendix B, Criterion III, Design Control, for the licensees failure to establish the gain settings used on the power range neutron monitoring system in accordance with design requirements. The licensee entered this issue into their corrective action program as Condition Report CR-GGN-2013-00177. The immediate corrective actions included adjusting gain settings for their average power range monitor (APRM) instruments to indicate actual core thermal power as determined by the heat balance. In additioin, the licensee revised their neutron monitoring procedure to set the initial gains for the average power range monitor to the maximum value to maintain conservative power indication during future startups. They also changed their local power range monitor replacement procedure to use the vendor specified initial gain setting of 3.692 prior to startup. The finding was more than minor because it affected the design control attribute of the Mitigating Systems Cornerstone and impacted the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, the incorrect gain settings caused a violation of technical specification 3.0.4 by rendering the APRM Neutron Flux High Setdown scram function and the Neutron Flux Upscale, Startup control rod block function inoperable prior to entry into Mode 2. In accordance with NRC Inspection Manual Chapter 0609, Attachment 4, Initial Characterization of Findings, the inspectors determined that the issue affected the Mitigating Systems Cornerstone. In accordance with NRC Inspection Manual Chapter 0609, Appendix A, The Significance Determination Process (SDP) for Findings at Power , the inspectors determined that the issue had very low safety significance (Green) because although the finding affected a single reactor protection system trip signal to initiate a reactor scram, it did not affect the function of other redundant trips or diverse methods of reactor shutdown, did not involve control manipulations that unintentionally added positive reactivity, and did not result in a mismanagement of reactivity by operators. Because the performance deficiency occurred in the past and is not reflective of current licensee performance, this finding was not assigned a cross-cutting aspect. |
| Site: | Grand Gulf  |
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| Report | IR 05000416/2012005 Section 4OA3 |
| Date counted | Dec 31, 2012 (2012Q4) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71153 |
| Inspectors (proximate) | B Rice D Proulx G George J Laughlin L Carson N Okonkwo R Kumana R Smith S Achen S Makord Proulx G George J Laughlin L Carson N Okonkwo R Kumana R Smith S Achen S Makor B Ric |
| INPO aspect | |
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Finding - Grand Gulf - IR 05000416/2012005 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Grand Gulf) @ 2012Q4
Self-Identified List (Grand Gulf)
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