05000443/LER-2023-001, Automatic Actuation of B Emergency Diesel Generator Emergency Power Sequencer

Automatic Actuation of B Emergency Diesel Generator Emergency Power Sequencer

ML23163A217
Person / Time
Site:	Seabrook
Issue date:	06/12/2023
From:	Strand D NextEra Energy Seabrook
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
L-2023-081 LER 2023-001-00
Download: ML23163A217 (1)

LER-2023-001, Automatic Actuation of B Emergency Diesel Generator Emergency Power Sequencer

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A)
4432023001R00 - NRC Website

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NEXTera ENERGY~

SEABROOK U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 Re:

Seabrook Station Docket No. 50-443 Reportable Event: 2023-001-00 Date of Event: April 12, 2023 June 12, 2023 L-2023-081 10 CFR 50.73 Automatic Actuation of 'B' Emergency Diesel Generator Emergency Power Sequencer The attached Licensee Event Report 2023-001 is being submitted pursuant to the requirements of 10 CFR 50. 73 to provide notification of the subject event.

Respectfully, Dianne Strand General Manager, Regulatory Affairs Attachment cc:

Seabrook Station NRC Senior Resident Inspector Seabrook Station NRC Program Manager NextEra Energy Seabrook, LLC, P.O. Box 300, Lafayette Road, Seabrook, NH 03874

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (08-2020)

APPROVED BY OMB: NO. 3150-0104 EXPIRES: 08/31/2023 LICENSEE EVENT REPORT (LER)

(See Page 3 for required number of digits/characters for each block)

(See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)

1. Facility Name Seabrook Station

2. Docket Number 05000443

3. Page 1 of 3

4. Title Automatic Actuation of B Emergency Diesel Generator Emergency Power Sequencer

5. Event Date

6. LER Number

7. Report Date

8. Other Facilities Involved Month Day Year Year Sequential Number Revision Number Month Day Year Facility Name n/a Docket Number 05000 4

12 2023 2023 -

001 -

00 6

12 2023 Facility Name n/a Docket Number 05000

9. Operating Mode 6

10. Power Level 0%

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) 10 CFR Part 20 20.2203(a)(2)(vi) 50.36(c)(2) 50.73(a)(2)(iv)(A) 50.73(a)(2)(x) 20.2201(b) 20.2203(a)(3)(i) 50.46(a)(3)(ii) 50.73(a)(2)(v)(A) 10 CFR Part 73 20.2201(d) 20.2203(a)(3)(ii) 50.69(g) 50.73(a)(2)(v)(B) 73.71(a)(4) 20.2203(a)(1) 20.2203(a)(4) 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(C) 73.71(a)(5) 20.2203(a)(2)(i) 10 CFR Part 21 50.73(a)(2)(i)(B) 50.73(a)(2)(v)(D) 73.77(a)(1) 20.2203(a)(2)(ii) 21.2(c) 50.73(a)(2)(i)(C) 50.73(a)(2)(vii) 73.77(a)(2)(i) 20.2203(a)(2)(iii) 10 CFR Part 50 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A) 73.77(a)(2)(ii) 20.2203(a)(2)(iv) 50.36(c)(1)(i)(A) 50.73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B) 20.2203(a)(2)(v) 50.36(c)(1)(ii)(A) 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A)

OTHER (Specify here, in abstract or in NRC 366A)

12. Licensee Contact for this LER Licensee Contact Bob Murrell, Licensing Engineer Telephone Number (Include area code) 319-651-9496 Cause System Component Manufacturer Reportable To IRIS Cause System Component Manufacturer Reportable To IRIS X

JE PR W120 Y

14. Supplemental Report Expected YES (If yes, complete 15. Expected Submission Date)

NO

15. Expected Submission Date Month Day Year Abstract (Limit to 1560 spaces, i.e., approximately 15 single-spaced typewritten lines)

On April 12, 2023, at 11:07, while in Mode 6 at 0% power, a valid actuation of the B Emergency Diesel Generator (EDG) Emergency Power Sequencer (EPS) occurred due to a loss of power to the B train Emergency Bus E6. Troubleshooting determined that the loss of power resulted from spurious operation of EPS Remote Manual Override (RMO) relays that opened the Unit Auxiliary Transformer (UAT) feeder breaker to Bus E6. Subsequently, the loss of power to Bus E6 resulted in a valid actuation of an EPS starting signal to the B EDG. On April 15, 2023, Emergency Bus E6 Remote Manual Override relays were tested and all functions were found to operate as designed. At the time of this event, the B EDG was removed from service for scheduled maintenance and therefore, did not start. There was minimal impact to the station due the unplanned actuation. However, based on the fact that the B EDG did not actually start, this event had no impact on to the health and safety of the public. In addition, there were no other Structure Systems or Components (SSCs) that contributed to this event.

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Page 3 of 3 Corrective Actions On April 15, 2023, testing of the EPS RMO relays was performed, and all components were found to operate as designed. In addition, the EPS power supplies were replaced on April 17, 2023.

Similar Events A review of reportable events dating back 10 years, did not identify any previous events or conditions that involved the same underlying cause as this event.

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