05000373/FIN-2010002-01
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Finding | |
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| Title | Failure to Maintain Design Control of SBLC system |
| Description | The inspectors identified a finding of very low safety significance for the licensees failure to ensure the standby liquid control (SBLC) system could mitigate the consequences of all design basis anticipated transient without scram (ATWS) events. Specifically, the licensee lowered SBLC pump discharge relief valve set pressure to a value where a successful relief valve surveillance test result could be achieved, but SBLC system pressure attained during certain ATWS events would result in lifting the relief valve, which redirects the required sodium pentaborate solution away from the reactor. A NCV of 10 CFR 50, Appendix B, Criterion III, Design Control, was also identified for failure to maintain the design basis of the SBLC system to bring the reactor from rated power to a cold shutdown condition at any time in core life as described in the Updated Final Safety Analysis Report (UFSAR).The inspectors determined that the finding was more than minor because it affected the Mitigating Systems Cornerstone objective of ensuring the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. In addition, the finding affected the attribute of design control in the area of plant modifications. Specifically, by changing the set pressures of the SBLC relief valves, the licensee created the possibility that an SBLC train would not be capable of injecting neutron absorber solution into the reactor to accomplish the above stated design specification under certain accident conditions. The finding was determined to be of very low safety significance using the SDP Phase 3. As part of their corrective actions, the licensee adjusted the relief valve setpoints and is performing a detailed root cause on the set pressure drift phenomenon and the maintenance and testing practices performed by licensee personnel on the relief valves in question |
| Site: | LaSalle  |
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| Report | IR 05000373/2010002 Section 1R12 |
| Date counted | Mar 31, 2010 (2010Q1) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.12 |
| Inspectors (proximate) | M Holmberg F Ramirez K Riemer M Mitchell B Metrow J Yesinowski C Scott A Scarbeary P Smagacz J Corujo-Sandin |
| INPO aspect | |
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Finding - LaSalle - IR 05000373/2010002 | |||||||||||||||||||||||||||||||||||||||||||
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Finding List (LaSalle) @ 2010Q1
Self-Identified List (LaSalle)
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