The NRC identified a finding for the licensees failure to verify the adequacy of design inputs used in protected
service water (PSW) testing and engineering evaluations to validate that the PSW system could perform its design function with respect to Milestone 4 of order
EA-13-010, in accordance with the Duke Energy Carolinas Topical Report, Quality Assurance Program. The licensee entered this issue into their corrective action program as problem investigation program reports (
PIPs) O-15-03630, O-15-03527, O-15-03529, O-15- 03631, O-15-03530, NCR 01930521, NCR 01929161, and
PIP 0-15-4544. The performance deficiency was more than minor because it was associated with the design control attribute and adversely affected the
mitigating systems cornerstone objective to ensure the availability, reliability, and capability of systems that respond to
initiating events to prevent undesirable consequences. Specifically, the errors identified in the hydraulic flow modeling software, Calculation OSC-9595, Protected
Service Water (PSW) Hydraulic Model, Rev. 6, and supporting documentation required significant revision and reanalysis in order to determine that the PSW system was capable of meeting its design flow requirements for short term secondary heat removal capability. The inspectors determined the finding to be of very low safety significance (Green) because the finding was a deficiency affecting the design or qualification of a mitigating structure, system, or component (
SSC), and the
SSC maintained its operability or functionality. The inspectors determined the finding was indicative of present licensee performance and was associated with the cross-cutting aspect of avoid complacency within the human performance area. Specifically, the licensee failed to utilize standard human error prevention tools to ensure critical reviews were performed for the PSW testing and engineering evaluations supporting the completion of Milestone 4 of order
EA-13-010 dated July 1, 2013.