05000327/FIN-2010005-03
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Finding | |
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Title | Failure to Use Worst Case 6900 VAC Bus Voltage in Design Calculations |
Description | The inspectors identified a Green non-cited violation of 10 CFR 50, Appendix B, Criterion III, Design Control, for the licensees failure to assure that applicable regulatory requirements and the design basis for structures, systems, and components are correctly translated into specifications, drawings, procedures, and instructions. Specifically, the licensee failed to assure that applicable regulatory requirements for undervoltage (degraded) voltage protection, including those prescribed in TS section 3.3.14, table 3.3.14-2, were correctly translated into design calculation, SQNETAPAC, AC Auxiliary Power System Analysis, Rev. 36, which evaluated transient motor starting voltages at the beginning of a design basis loss of coolant accident (LOCA). The licensee has entered this into their corrective action program as PER 297671 This finding is more than minor because it affects the Design Control attribute of the Mitigating Systems Cornerstone. It impacts the cornerstone objective of ensuring the availability, reliability, and operability of the 6900 VAC safety buses to perform its intended safety function during a design basis event. The potential availability, reliability, and operability of the 6900 VAC safety buses during a potential degraded voltage condition was impacted as the licensee calculation used a non conservative degraded voltage input, with respect to the values specified in TS, into their safetyrelated motor starting and running calculations. The inspectors assessed the finding using the SDP and determined that the finding was of very low safety significance (Green) because the finding represented a design deficiency confirmed not to result in the loss of functionality of safety-related loads due to the availability of load tap changers (LTCs) that are installed to improve a degraded voltage condition. The inspectors reviewed the performance deficiency for cross-cutting aspects and determined that none were applicable since this performance deficiency was not indicative of current licensee performance as the design calculation discussed above was not recently performed |
Site: | Sequoyah ![]() |
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Report | IR 05000327/2010005 Section 4OA5 |
Date counted | Dec 31, 2010 (2010Q4) |
Type: | NCV: Green |
cornerstone | Mitigating Systems |
Identified by: | NRC identified |
Inspection Procedure: | |
Inspectors (proximate) | R Patterson R Williams S Sandal W Deschaine W Loo C Young E Guthrie L Lake L Mahlahla M Riches M Speck P Higgins R Aiello R Baldwin R Hamilton |
INPO aspect | |
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Finding - Sequoyah - IR 05000327/2010005 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Sequoyah) @ 2010Q4
Self-Identified List (Sequoyah)
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