05000250/FIN-2017007-02
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Finding | |
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Title | Failure to Perform Design Verification for Under Frequency Trip of the Main Generator Breakers |
Description | The NRC identified a non-cited violation of Title 10 Code of Federal Regulations Part 50, Appendix B, Criterion III, Design Control, for failure to verify or check the adequacy of design of the under frequency trip feature of the main generator circuit breakers with regard to the effect of its operation on plant stability and the maintenance of critical safety functions. The licensee entered this issue into their corrective action program as AR 2220874 and AR 2224998. The performance deficiency was determined to be more than minor because it was associated with the Design Control attribute of the Initiating Events Cornerstone and adversely affected the cornerstone objective of limiting the likelihood of events that upset plant stability and challenge critical safety functions. Specifically, opening of the main generator breakers due to an under frequency condition on the offsite power system would cause the generator load to suddenly drop from full power to the level of the plant loads, and there was no verification that plant stability and critical safety functions would be maintained. The team evaluated the finding with Inspection Manual Chapter 0609, Appendix A, and determined the finding met the Support System Initiators screening criteria for requiring a detailed risk evaluation. The team determined that this issue increased the likelihood of the support system initiator loss of offsite power (LOOP). The regional senior risk analyst conducted a detailed risk evaluation with a one year exposure and determined the change in core damage frequency was less than 1E-6, which was of very low safety significance (Green). The team did not assign a cross-cutting aspect because the issue did not reflect current licensee performance. |
Site: | Turkey Point ![]() |
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Report | IR 05000250/2017007 Section 1R21 |
Date counted | Sep 30, 2017 (2017Q3) |
Type: | NCV: Green |
cornerstone | Initiating Events |
Identified by: | NRC identified |
Inspection Procedure: | IP 71111.21M |
Inspectors (proximate) | T Fanelli S Bussey M Riley N Morgan M Jones H Leake R Bywater J Bartley |
Violation of: | 10 CFR 50 Appendix B 10 CFR 50 Appendix B Criterion III, Design Control |
INPO aspect | |
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Finding - Turkey Point - IR 05000250/2017007 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Turkey Point) @ 2017Q3
Self-Identified List (Turkey Point)
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