The inspectors reviewed a licensee-identified Green non-cited violation of Title
10 CFR Part 50, Appendix B, Criterion III, Design Control, for failure to correctly translate the design basis requirement for welded anchorage configurations into specifications and drawings for electrical load centers. Specifically, in 1977, seismic design qualification testing established the 125-volt
DC load center anchor design, but the licensee failed to update Drawing 050053, Sheet 11, Anchorage Requirements for Design Class I Electrical Equipment, Revision 12, to reflect the tested configuration. As a result, Load Center SD21 was reinstalled in the plant after the testing with an anchorage configuration that was less robust than the tested configuration, which degraded the load centers ability to withstand a seismic event. The performance deficiency was more than minor because it was associated with the design control attribute of the mitigating system cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to
initiating events to prevent undesirable consequences. Specifically, the missing
welds on the load center anchorage reduced the capability of the cabinet to withstand shaking from a seismic event compared to the seismic verification test configuration. This violation was of very low safety significance (Green) because, while the violation was a deficiency affecting design or qualification of a mitigating system, it did not result in the loss of operability or functionality of the system. The licensee entered the issue into the corrective action program as Notification 50540606 and has corrected the condition by adding additional
welds to the base of the load center consistent with the configuration used for design qualification testing.
