05000263/FIN-2009007-03
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Finding | |
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Title | Failure to Adquately Evaluate Minimum Voltage Available at Safety-Related Electrical Components |
Description | The inspectors identified an NCV of 10 CFR Part 50, Appendix B, Criterion III, Design Control, having very low safety-significance for the failure to adequately evaluate circuit loads in determining design limits in electrical calculations. Specifically, three examples were identified where the licensee: (1) failed to perform a calculation for safety-related motor starters that included all control circuit loads in determining the minimum voltage available at 120Vac starter coils, which was used to establish the coil voltage test acceptance criteria; (2) failed to include thermal overload heater and starter contact resistance when calculating the minimum voltage at 480Vac motor terminals; and (3) failed to assure that the minimum voltage at the 120Vac solenoid operated control valves was in conformance with vendor requirements. These issues were entered into the licensees corrective action program to re-evaluate the voltage available, and to test coils, as required, to verify the pick-up voltage. The finding was more than minor because it was associated with the Mitigating Systems cornerstone attribute of design control and affected the cornerstone objective of ensuring the availability, reliability, and capability of safety-related equipment to respond to initiating events to prevent undesirable consequences. This finding is of very low safety-significance (Green) because the design deficiency was confirmed, with the exception of ESW pump P-111B, not to result in loss of operability or functionality. Specifically, the failure to assure adequate voltage was available at the solenoid valves coils; and to perform periodic testing to assure the minimum voltage remained acceptable as the components aged, did not result in an impact on current operability. With respect to the ESW pump, it was determined that the pump would not have started under degraded voltage condition as required such that the ESW pump was considered inoperable. Based on a Phase III analysis, the failure of the pump to start under degraded voltage conditions was determined to be very low safety-significance (Green). The inspectors did not identify a cross-cutting aspect associated with this finding because this was a legacy design issue, therefore was not reflective of current performance |
Site: | Monticello |
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Report | IR 05000263/2009007 Section 1R21 |
Date counted | Dec 31, 2009 (2009Q4) |
Type: | NCV: Green |
cornerstone | Mitigating Systems |
Identified by: | NRC identified |
Inspection Procedure: | IP 71111.21 |
Inspectors (proximate) | A Dunlop A Stone C Brown H Campbell J Bozga L Jones M Munir N Feliz Adomo S Kobylarz |
INPO aspect | |
Finding closed by | |
IR 05000263/2009007 (6 January 2010) | |
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Finding - Monticello - IR 05000263/2009007 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Monticello) @ 2009Q4
Self-Identified List (Monticello)
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