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| Entered date | Event description | |
|---|---|---|
| ENS 54234 | 22 August 2019 12:49:00 | This 60-day telephone notification is being made in accordance with 10 CFR 50.73(a)(1) and 10 CFR 50.73(a)(2)(iv)(A) regarding an invalid Engineered Safety Feature actuation signal. On June 27, 2019, at 0130 hours Pacific Daylight Time (PDT), with Unit 2 operating at 100 percent power, the U2 4-kV Vital Bus F was automatically transferred from its auxiliary power to its startup power due to an invalid loss of bus voltage signal. The cause of the invalid signal was due to a test jumper that was inadvertently left in place during surveillance testing. As a result, one auxiliary saltwater pump started and two containment fan cooler units started in slow speed. At 1245 PDT, Vital Bus F was transferred back from startup power to auxiliary power which is the normal plant operating configuration. This event was entered into the Diablo Canyon Power Plant corrective action program for resolution. This event did not result in any adverse impact on the health and safety of the public. The plant responded as expected. In accordance with 10 CFR 50.73(a)(1), a telephone notification is being made in lieu of submitting a written Licensee Event Report. The licensee has notified the NRC Senior Resident Inspector. |