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| Entered date | Event description | |
|---|---|---|
| ENS 56769 | 1 October 2023 03:02:00 | The following information was provided by the licensee via email: At 2014 (PDT) on 09/30/2023, with (Diablo Canyon) Unit 1 in Mode 1 at 11 percent reactor power in preparation for a pre-planned manual reactor trip into a scheduled refueling outage, the reactor was manually tripped due to a failed secondary system dump valve. Auxiliary feedwater was manually started in accordance with plant procedures. This event is being reported in accordance with the reporting criteria of 10 CFR 50.72(b)(2)(iv)(B) and 10 CFR 50.72(b)(3)(iv)(A). There was no plant or public safety impact. The NRC Senior Resident Inspector has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: Diablo Canyon Unit 2 was unaffected. |
| ENS 56176 | 23 October 2022 19:05:00 | The following information was provided by the licensee via email: At 0830 PDT on 10/23/2022, during routine outage inspections on Unit 2, it was determined that the RCS Pressure Boundary did not meet ASME Section XI acceptance criteria on a 2-inch vacuum refill connection line. This event is being reported pursuant to 10 CFR 50.72(b)(3)(ii)(A). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. |
| ENS 54789 | 17 July 2020 19:59:00 | On July 17, 2020, at 1346 PDT with Diablo Canyon Power Plant Unit 2 operating at 100 percent power, the reactor was manually tripped in accordance with plant procedures due to increasing hydrogen usage in the Unit 2 main generator. The reactor trip was uncomplicated and the Auxiliary Feedwater system started as expected. The plant is stable in Mode 3. This notification is being made in accordance the requirements of 10 CFR 50.72(b)(2)(iv)(B) as a manual actuation of the reactor protection system and 10 CFR 50.72(b)(3)(iv)(A) as an automatic actuation of a specified safety system. The cause of the increased hydrogen usage is under investigation. There was no impact to the health and safety of the public or plant personnel. The Senior Resident Inspector has been notified. |