05000445/FIN-2015007-02
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Finding | |
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| Title | Failure to Validate Inverter Output Demand Factor and to use the Correct Value of Inverter Efficiency when Determining Inverter Input D-C Power Requirements |
| Description | The team identified a Green, non-cited violation of 10 CFR Part 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, for those structures, systems, and components to which this appendix applies are correctly translated into specifications, drawings, procedures, and instructions. Specifically, prior to June 30, 2015, the licensee did not correctly evaluate the inverter output loading by assuming an incorrectly low demand factor, and also did not correctly identify the inverter efficiency when determining the inverter input d-c power required from the Class 1E station battery. In response to this issue, the licensee performed an operability evaluation and reevaluated the battery inverter loads. The corrected inverter loads were compared with the inverter load performance test data. Based on Design Engineering bounding calculations, all of the safety-related battery inverters remained operable and capable of meeting the four hour mission time. This finding was entered into the licensees corrective action program as Condition Report CR-2015-005805. The team determined that the failure to correctly evaluate the inverter input d-c power requirement was a performance deficiency. The finding was more than minor because it was associated with the design control attribute of the Mitigating Systems Cornerstone and adversely affected the cornerstone objective of ensuring the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, the licensee failed to correctly evaluate the inverter input d-c power requirements that resulted in a condition where there was reasonable doubt on the operability of the system. In accordance with Inspection Manual Chapter 0609, Appendix A, The Significance Determination Process (SDP) for Findings At-Power, dated June 19, 2012, Exhibit 2, Mitigating Systems Screening Questions, the issue screened as having very low safety significance (Green) because it was a design or qualification deficiency that did not result in the loss of operability or functionality, did not represent an actual loss of safety function of the system or train; did not result in the loss of one or more trains of non-technical specification equipment; and did not screen as potentially risk significant due to seismic, flooding, or severe weather. The team determined that this finding did not have a cross-cutting aspect because the most significant contributor did not reflect current licensee performance. |
| Site: | Comanche Peak  |
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| Report | IR 05000445/2015007 Section 1R21 |
| Date counted | Sep 30, 2015 (2015Q3) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.21 |
| Inspectors (proximate) | C Baron C Smith J Watkins R Kopriva S Kobylarz T Farnholtz T Palmer |
| Violation of: | 10 CFR 50 Appendix B Criterion III, Design Control |
| INPO aspect | |
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Finding - Comanche Peak - IR 05000445/2015007 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Comanche Peak) @ 2015Q3
Self-Identified List (Comanche Peak)
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