W3F1-2024-0013, Manual Reactor Trip Due to Engineered Safety Features Actuation System Relay Failure

Manual Reactor Trip Due to Engineered Safety Features Actuation System Relay Failure

ML24136A170
Person / Time
Site:	Waterford
Issue date:	05/15/2024
From:	Twarog J Entergy Operations
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
W3F1-2024-0013 LER 2024-001-00
Download: ML24136A170 (1)

Text

E) entergy John Twarog Manager Regulatory Assurance 504-739-67 4 7

W3F1-2024-0013 10 CFR 50.73

May 15, 2024

ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001

Subject:

Licensee Event Report 50-382/2024-001-00, Manual Reactor Trip Due to Engineered Safety Features Actuation System Relay Failure Waterford Steam Electric Station, Unit 3 NRC Docket No. 50-382 Renewed Facility Operating License No. NPF-38

Entergy Operations, Inc. (Entergy) submits the enclosed Licensee Event Report (LER) 50-382/2024-001-00 for Waterford Steam Electric Station, Unit 3 (Waterford 3). The events reported herein are reportable in accordance with 10 CFR 50.73(a)(2)(iv)(A}, Any event or condition that resulted in manual or automatic actuation of any of the systems listed in paragraph (a)(2)(iv)(B); Reactor protection system (RPS) including: reactor scram or reactor trip and PWR auxiliary or emergency feedwater system actuation.

The LER describes the Engineered Safety Features Actuation System relay failure and subsequent reactor trip and emergency feedwater actuation.

This letter contains no new commitments.

Should you have any questions concerning this issue, please contact me at 504-739-6747.

Respectfully,

John Twarog /1/

JRT/ahv

Entergy Operations, Inc., 17265 River Road, Killona, LA 70057 W3F1-2024-0013 Page 2 of 2

Enclosure:

Licensee Event Report 50-382/2024-001-00

cc : NRC Region IV Regional Administrator NRC Senior Resident Inspector - Waterford Steam Electric Station, Unit 3 NRC Project Manager - Waterford Steam Electric Station, Unit 3 Louisiana Department of Environmental Quality Enclosure

W3F1-2024-0013

Licensee Event Report 50-382/2024-001-00 NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 04/30/2027 (04-02-2024 ) Estimated burden per response to comply with this mandatory collection request 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />. Reported lessons lecrned a-e incorporated into the licensing process and fed back to industry. Send comments rega-ding burden

(~*~*""***:**1 LICENSEE EVENT REPORT (LER) estimate to the FOIA, Library, and Information Collections Branch (T-6 A10M), U. S. Nuclear Regulatory (See Page 2 for required number of digits/characters for each block) Commission, Washington, DC 20555-0001, or by email to lnfocol1ects.Resource@nrc.gov, and the 0MB reviewer

'::.,._, +O, at 0MB Office..... (See NUREG-1022, R.3 for instruction and guidance for completing this of Information and Regulatory Affairs, (3150-0104), Attn: Desk Officer for the Nuclear Regulatory form Commission, 72517th Street NW, Washingk>n, DC 20503. The NRC may not conductor sponsor, and a person is httg://www.nrc.gov / reading-rm /doc-collections /nuregs /staff/ sr1022/r3/) not required to respond to, a collection of information unless the document requesting or requiring the collection displays a currently vafid 0MB control number.

1. Facility Name ~ 050 2. Docket Number 3. Page Waterford Steam Electric Station, Unit 3 052 00382 1 OF 3 4. Title Manual Reactor Trip Due to Engineered Safety Features Actuation System Relay Failure

5. Event Date 6. LER Number 7. Report Date 8. Other Facilities Involved

Month Day Year Year Sequential Revision Month Day Year Facility Name Docket Number Number No. 050

03 16 2024 2024 - 001 - 00 05 15 2024 Facility Name 052 Docket Number

9. Operating Mode 110. Power Level 1 100

11. This Report is Submitted Pursuant to the Requirements of 1 0 CFR §: (Check all that apply) 10 CFR Part 20 20.2203( a)(2)(vi) 10 CFR Part 50 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A) 73.1200(a) 20.2201(b) 20.2203(a)(3)(i) 50.36(c)(1 )(i)(A) 50.73(a)(2)(ii)(B) 50. 73(a)(2)(viii)(B) 73.1200(b) 20.2201(d) 20.2203(a)(3)(ii) 50.36(c)(1 )(ii)(A) 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A) 73.1200(c) 20.2203(a)(1) 20.2203(a)(4) 50.36(c)(2) [Z] 50. 73(a)(2)(iv)(A) 50.73(a)(2)(x) 73.1200(d) 20.2203(a)(2)(i) 10 CFR Part 21 50.46(a)(3)(ii) 50.73(a)(2)(v)(A) 10 CFR Part 73 73.1200(e) 20.2203(a)(2)(ii) 21.2(c) 50.69(g) 50. 73(a)(2)(v)(B) 73. 77(a)(1) 73.1200(f) 20.2203(a)(2)(iii) 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(C) 73. 77(a)(2)(i) 73.1200(9) 20.2203(a)(2)(iv) 50. 73(a)(2)(i)(B) 50. 73(a)(2)(v)(D) 73.77(a)(2)(ii) 73.1200(h) 20.2203(a)(2)(v) 50. 73(a)(2)(i)(C) 50.73(a)(2)(vii)

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

12. Licensee Contact for this LER

Licensee Contact Phone Number (Include area code)

John Twarog (504) 739-6747

13. Complete One Line for each Component Failure Described in this Report

Cause System Component Manufacturer Reportable to IRIS Cause System Component Manufacturer Reportable to IRIS B JE RLY T351 y

14. Supplemental Report Expected Month Day Year

15. Expected Submission Date 0 No Yes (If yes, complete 15. Expected Submission Date)

16. Abstract (Limit to 1326 spaces, i.e., approximately 13 single-spaced typewritten lines)

At 1449 CDT on March 16, 2024, with Waterford Steam Electric Station, Unit 3 (WF3), operating in Mode 1 at approximately 100% power, Main Feedwater Isolation Valve #2, FW-184B, and Main Steam Isolation Valve #2, MS-124B, began closing resulting in steam generator levels lowering. As a result of these indications, control room operators initiated a manual reactor trip. All control element assemblies properly inserted in response to the reactor trip. All safety systems, including the Emergency Feedwater System, performed as designed and there were no complications with the trip.

The cause of the event was a failure of the Steam Generator #2 and Main Steam Line #2 Valves Main Steam Isolation Signal Actuation Relay, K313-A, resulting in the unexpected closing of MS-124B and FW-184B. The relay has been sent to the vendor for analysis. The failed relay was replaced, and the remaining Engineered Safeguard Features Actuation System relays were verified to be from a different batch.

This event is being reported in accordance with 10 CFR 50. 73(a)(2)(iv)(A), as an actuation of the Reactor Protection System and Emergency Feedwater System.

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 04/30/2027 (04-02-2024 ) Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />. Reported lessons learned are incorporated into the licensing process and fed back to industry. Send commenls LICENSEE EVENT REPORT (LER) regarding burden estimate to the FOIA, Library, and Information Collections Branch (T-6 A10M), U. S.

Nuclear Regulatory Commission, Washington, DC 20555-0001, or by email to CONTINUATION SHEET lnfocollects.Resource@nrc.gov, and the 0MB reviewer at: 0MB Office of lnfonnation and Regulatory Affairs, (3150-0104), Attn: Desk Officer for the Nuclear Regulatory Commission, 725 17th Street NW,

(See NUREG-1022, R.3 for instruction and guidance for completing this form Washington, DC 20503. The NRC may not conduct or sponsor, and a person is not required to http:/lwww.nrc.gov/reading - rm/doc -collections/nuregs/staff/sr1022/r3Q respond to, a collection of infonnation unless the document requesting or requiring the collection displays a currently valid 0MB control number.

.-----------------, 00 050 1. FACILITY NAME 2. DOCKET NUMBER 3. LER NUMBER YEAR SEQUENTIAL REV Waterford Steam Electric Station, Unit 3 052 I 00382 D NUMBER NO. I

~-, 001 1-0 NARRATIVE

Event Description

At 1449 CDT on March 16, 2024, with Waterford Steam Electric Station, Unit 3 (WF3), operating Mode 1 at 100% power,

Main Feedwater Isolation Valve #2 [SJ:ISV], FW-184B, and Main Steam Isolation Valve #2 [SB:ISV], MS-124B, began closing resulting in steam generator levels lowering. As a result of these indications, control room operators initiated a manual reactor trip. All control element assemblies properly inserted in response to the reactor trip. All safety systems, including the Emergency Feedwater System (EFW) [BAJ, performed as designed and there were no complications with the trip. The condition was reported on March 16, 2024, at 1836 EDT (Event Number 57032) in accordance with 10 CFR 50. 72 (b)(2)(iv)(B) and 10 CFR 50. 72(b)(3)(iv)(A) for a valid Reactor Protection System (RPS) actuation and EFW system actuation.

Following the reactor trip, an acrid odor was detected in the rear of relay cabinet, 3AS Bay 3. The investigation identified that the Tyco, MDR-7034, K313-A relay had failed.

Event Cause

The cause of FW-184B and MS-124B failing closed was due to a degraded relay coil. The K313-A relay, Steam Generator

1. 2 and Main Steam Line #2 Valves Main Steam Isolation Signal Actuation Relay, is part of the Engineered Safeguard Features Actuation System (ESFAS). The relay has been sent for vendor failure analysis. If the results from the vendor analysis indicate a different cause for the failure, then a supplement will be provided.

ESFAS relays were previously identified as Single Point Vulnerabilities (SPV). Elimination of this SPV was scheduled to be completed in WF3's most recent outage (Refuel Outage [RF] 25) however due to a design discrepancy with the Engineering Change the modification was removed from the RF-25 scope.

Safety Assessment

The actual consequence for the relay failure was a reactor trip. The relay failure challenged the ESFAS and Reactor Protection System. Following the manual reactor trip, plant equipment performed as designed. There were no other structures, systems, or components out of service that contributed to this event. EFW responded and provided normal post trip heat removal via the Steam Generators [SG] such that there were no actual consequences to general safety of the public, nuclear safety, industrial safety, or radiological safety for this event.

Corrective Actions

(1) K313-A relay was replaced, and post maintenance testing was completed.

(2) Validated the remaining ESFAS relays are not from the same batch as the failed K313-A relay.

(3) Determine if any ESFAS spare relays in stock are from the same batch as the failed K313-A relay. This action is scheduled for completion by May 31, 2024.

(4) Ensure the Engineering Modification to eliminate the ESFAS relays as SPVs is planned to be scoped for either RF-26 or RF-27. This action is scheduled for completion by September 30, 2024.

NRC FORM 366A (04-02-2024) Page 2 of 3 NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 04/30/2027 (04-02-2024 ) Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />. Repcrted lessons learned are incorpo rated in to the licensing process and fed back to industry. Send comments LICENSEE EVENT REPORT (LER) regarding burden estimate to the FOIA, Library, and Information Collections Branch (T-6 A10M), U. S.

Nuclear Regulatory Commission, Washington, DC 20555-0001, or by email to CONTINUATION SHEET lnfocollects.Resource@nrc.gov, and the 0M B reviewer at: 0MB Office of lnfonnation and Regulatory Affairs, (3150-0104), Attn: Desk Officer for the Nuclear Regulatory Commission, 725 17th Street NW,

(See NUREG-1022, R.3 for instruction and guidance for completing this form Washington, DC 20503. The NRC may not conduct or sponsor, and a person is not requ ired to http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3Q respond to, a collection of information unless the document requesting or requiring the collection displays a currently valid 0MB control number.

1. FACILITY NAME 00 050 2. DOCKET NUMBER 3. LER NUMBER YEAR SEQUENTIAL REV NUMBER NO.

Waterford Steam Electric Station, Unit 3 052 I 00382 I B -I 001 1-0

NARRATIVE

Previous Similar Events

LER-2022-005-00, documents of the opposite train failure ESFAS relay, K313-B that resulted in a reactor trip on June 24,2022. The direct cause of the relay failure was a short in the relay coil. After the failure of the relay on June 24, 2022, the site replaced all six Main Steam Isolation Valve and Main Feed Isolation Valve ESFAS relays. Vendor analysis determined the relay coil failed due to a manufacturing defect.

NRC FORM 366A (04-02-2024) Page 3 of 3