05000482/FIN-2013008-03
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Finding | |
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Title | Failure to Ensure that Degraded Voltage Relay Minimum Allowable Time Delay Value is Bounded by Analyzed Value |
Description | The team identified a Green, non-cited violation of 10 CFR 50, Appendix B, Criterion III, Design Control, which states, in part, Measures shall be established to assure that applicable regulatory requirements and the design basis are correctly translated into specifications, drawings, procedures, and instructions. The design control measures shall provide for verifying or checking the adequacy of design, such as by the performance of design reviews, by the use of alternate or simplified calculational methods, or by the performance of a suitable testing program. Specifically, on May 9, 2003, Calculation XX-E-009, System NB, NG, PG Undervoltage/Degraded Voltage Relay Setpoints, Revision 1, identified that the degraded voltage relays minimum time delay was 7.5 seconds, and the maximum time delay was 8.5 seconds. During testing of the degraded voltage relays, the calculation states, In all cases the steady state voltage on NB01 and NB02 recovered within the 7.5 seconds accident criteria. However in some cases the recovery time is marginal. This requirement was not correctly translated into Surveillance Test Procedures STS IC-805A and STS IC-805B which allow a minimum time delay of 7.0 seconds, and a maximum time delay of 9.0 seconds for the degraded voltage relays timeout period during accident conditions. The licensee has entered this issue into their corrective action program as Condition Report CR-72496. The team determined that the licensees failure to ensure that the analyzed minimum allowable degraded voltage relay time delay of 7.5 seconds and maximum allowable degraded voltage relay time delay of 8.5 seconds, was incorporated into acceptance criteria for surveillance testing procedures was a performance deficiency. This finding was more than minor because it was associated with the Procedure Quality attribute of the Reactor Safety Initiating Events Cornerstone and adversely affected the cornerstone objective to limit the likelihood of events that upset plant stability and challenge critical safety functions during shutdown as well as power operations. Specifically, it was indeterminate whether the design requirement to prevent spurious actuation of the degraded voltage relays and consequential loss of offsite power would have been met if the time delay had been set at less than 7.5 seconds or greater than 8.5 seconds. In accordance with NRC Inspection Manual Chapter 0609, Appendix A, Exhibit 1, Initiating Events Screening Questions, the finding was determined to have very low safety significance (Green), because it did not cause a reactor trip and loss of mitigation equipment. This finding did not have a cross-cutting aspect because the most significant contributor to the performance deficiency did not reflect current licensee performance. |
Site: | Wolf Creek |
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Report | IR 05000482/2013008 Section 1R21 |
Date counted | Sep 30, 2013 (2013Q3) |
Type: | NCV: Green |
cornerstone | Mitigating Systems |
Identified by: | NRC identified |
Inspection Procedure: | IP 71111.21 |
Inspectors (proximate) | S Garchow B Correll A Sengupta H Leake R Kopriva T Farnholtz |
Violation of: | 10 CFR 50 Appendix B Criterion III, Design Control |
INPO aspect | |
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Finding - Wolf Creek - IR 05000482/2013008 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Wolf Creek) @ 2013Q3
Self-Identified List (Wolf Creek)
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