ML22173A143
| ML22173A143 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 06/28/2022 |
| From: | Blake Purnell Plant Licensing Branch III |
| To: | Tony Brown Energy Harbor Nuclear Corp |
| Purnell B | |
| References | |
| Download: ML22173A143 (4) | |
Text
June 28, 2022 Mr. Terry J. Brown Site Vice President Energy Harbor Nuclear Corp.
Mail Stop P-DB-3080 5501 North State Route 2 Oak Harbor, OH 43449-9760
SUBJECT:
DAVIS-BESSE NUCLEAR POWER STATION, UNIT NO. 1 TRANSMITTAL OF FINAL ACCIDENT SEQUENCE PRECURSOR REPORT REGARDING THE EMERGENCY DIESEL GENERATOR FIELD FLASH SELECTOR SWITCH FAILURE ON MAY 27, 2021
Dear Mr. Brown:
On May 27, 2021, the division 1 emergency diesel generator at Davis-Besse Nuclear Power Station, Unit No. 1, failed to reach the required voltage and frequency during surveillance testing. This failure was attributed to the failure of the field flash selector switch. This event was discussed in Inspection Report 05000346/2021050 issued by the U.S. Nuclear Regulatory Commission (NRC) by letter dated November 19, 2021 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML21321A365). By letter dated April 19, 2022 (ML22109A157), the NRC staff informed the licensee that it had determined that there was no performance deficiency associated with the failure to develop a preventive maintenance schedule for the inspection of the field flash selector switch. The April 19, 2022, letter also discusses two unresolved items associated with the field flash selector switch failure and the modification of the field flash circuitry. As part of the accident sequence precursor program, the NRC staff reviewed the event to identify potential precursors and to determine the probability of the event leading to a core damage state. The results of the analysis are provided in the enclosure to this letter.
The mean conditional core damage probability for this event was calculated to be 9x10-6. In accordance with Regulatory Issue Summary 2006-24, Revised Review and Transmittal Process for Accident Sequence Precursor Analyses (ML060900007), the NRC staff is not requesting formal review comments because the analysis resulted in a conditional core damage probability of less than 10-4.
If you have any questions, please contact Blake Purnell at 301-415-1380 or via email at Blake.Purnell@nrc.gov.
Sincerely,
/RA/
Blake Purnell, Project Manager Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-346
Enclosure:
Final Accident Sequence Precursor Analysis cc: Listserv
ENCLOSURE Final Accident Sequence Precursor Analysis - Davis-Besse Nuclear Station, Field Flash Selector Switch Failure Results in Emergency Diesel Generator Unavailability (IR 05000346/2022050) - Precursor
ML22178A243 (Package)
ML22173A143 (Letter)
ML22164A812 (ASP Report - final)
OFFICE NRR/DORL/LPL3/PM NRR/DORL/LPL3/LA NAME BPurnell (SWall for)
SRohrer DATE 06/17/2022 06/22/2022 OFFICE NRR/DORL/LPL3/BC NRR/DORL/LPL3/PM NAME NSalgado BPurnell DATE 06/28/2022 06/28/2022