05000280/FIN-2009002-01
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Finding | |
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Title | Licensee-Identified Violation |
Description | 10 CFR 50, Appendix B, Criterion III, Design Control; requires, in part, that design changes be subject to design control measures commensurate with those applied to the original design. Contrary to the above, design control measures commensurate with the original design were not implemented for a design change implemented in the 1980s to the safety-related motor operated valve (MOV) control circuits for the condenser inlet isolation valves. The condenser inlet isolation valve closing circuits were modified to actuate on a turbine building flooding signal The circuit modification did not include electrical isolation via qualified isolation devices, per IEEE-279, Criteria for Protection Systems for Nuclear Power Generating Stations, between the safety-related closing circuit for the MOVs and the non-safety related circuit in the flood control panel. This was identified in the licensees CAP as CR 320789. A regional Senior Reactor Analyst performed a Phase 3 evaluation under the Significance Determination Process and concluded that the performance deficiency was of very low safety significance. The most credible accident sequence involved a seismic event which caused the loss of automatic isolation of the condenser inlet motor operated valves via the panel in question and caused a condenser pipe break. Manual closure of the valves which would terminate the turbine building flood, though possible, failed. Consequently, all electric power to critical mitigation equipment was lost and core damage ensued. Critical assumptions included the low initiating event frequency of such an event and that operator actions could terminate the flooding |
Site: | Surry ![]() |
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Report | IR 05000280/2009002 Section 4OA7 |
Date counted | Mar 31, 2009 (2009Q1) |
Type: | NCV: Green |
cornerstone | Mitigating Systems |
Identified by: | Licensee-identified |
Inspection Procedure: | |
Inspectors (proximate) | C Welch G Mccoy C Kontz E Stamm R Hamilton M Bates J Nadel |
INPO aspect | |
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Finding - Surry - IR 05000280/2009002 | |||||||||||||||||||||||||||||||||||||||
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Finding List (Surry) @ 2009Q1
Self-Identified List (Surry)
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