05000458/FIN-2009005-01
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Finding | |
|---|---|
| Title | Main Steam Line Plus Seal Failure Results in Loss of Reactor Cavity Inventory |
| Description | A self-revealing noncited violation of 10CFR50 Appendix B, Criterion V, Instructions, Procedures and Drawings, was identified for the failure to follow the procedure for making a permanent plant modification and provide adequate procedures for installation and use of the main steam line plugs following a main steam line plug design change. This failure resulted in draining approximately 5,000 gallons of water from the upper reactor cavity pool to the drywell and a manual actuation of low pressure coolant injection to restore cavity pool water level. The licensee entered this issue into their corrective action program as Condition Report CR-RBS-2009-4681. The finding was more than minor in accordance with Inspection Manual Chapter 0612, Appendix B, Issues Screening, because the finding affected the initiating events cornerstone attribute of configuration control and the cornerstone objective to limit the likelihood of those events that upset plant stability and challenge critical safety functions during shutdown operations. The inspectors evaluated the finding in accordance with Inspection Manual Chapter 0609, Appendix G, Shutdown Operations Significance Determination Process. The inspectors reviewed Section II.B.(1) of Checklist 7 and determined that the finding required a Phase 2 analysis because the finding involved procedures that affected steam line plug seal configuration and resulted in inventory loss from the upper reactor cavity pool. The senior reactor analyst determined that, because of the special circumstances of this event, the use of a qualitative assessment using Inspection Manual Chapter 0609, Appendix M, was more appropriate than the risk tools provided in Inspection Manual Chapter 0609, Appendix G. This is because the draindown event was self-limiting, such that the inventory excursion could not have drained reactor cavity level below the level of the main steam lines, and that even with the failure of operators to take actions, the core would have remained covered with no challenges to the shutdown cooling system. Therefore, the event in the worst case would have been transparent to the core. Also, the displaced inventory posed no threat to any of the plant\'s mitigating systems. The inspectors concluded that the finding was of very low safety significance (Green). There is no crosscutting aspect associated with this violation because the finding does not reflect current licensee performance (Section 1R22) |
| Site: | River Bend  |
|---|---|
| Report | IR 05000458/2009005 Section 1R22 |
| Date counted | Dec 31, 2009 (2009Q4) |
| Type: | NCV: Green |
| cornerstone | Initiating Events |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71111.22 |
| Inspectors (proximate) | D Stearns G Larkin V Gaddy S Makor C Norton G Vasquez |
| INPO aspect | |
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Finding - River Bend - IR 05000458/2009005 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (River Bend) @ 2009Q4
Self-Identified List (River Bend)
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