05000416/LER-2024-003, Feedwater Inlet Check Valve Incorrectly Determined Operable

Feedwater Inlet Check Valve Incorrectly Determined Operable

ML24239A788
Person / Time
Site:	Grand Gulf
Issue date:	08/26/2024
From:	Hardy J Entergy Operations
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
GNRO2024-00029 LER 2024-003-00
Download: ML24239A788 (1)

LER-2024-003, Feedwater Inlet Check Valve Incorrectly Determined Operable

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
4162024003R00 - NRC Website

text

Entergy Operations, Inc.

~ entergy P.O. Box 756 Port Gibson, Mississippi 39150

Jeffery A. Hardy Manager Regulatory Assurance Grand Gulf Nuclear Station Tel: 802-380-5124

10 CFR 50.73

GNRO2024-00029

August26,2024

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

SUBJECT: Grand Gulf Nuclear Station, Unit 1 Licensee Event Report 2024-003-00, Feedwater Inlet Check Valve Incorrectly Determined Operable

Grand Gulf Nuclear Station, Unit 1 Docket No. 50-416 Renewed License No. NPF-29

Attached is Licensee Event Report (LER) 2024-003-00, Feedwater Inlet Check Valve Incorrectly Determined Operable. This report is being submitted in accordance with 1 O CFR 50.73(a)(2)(i)(B), as an operation of condition which was prohibited by the plant's Technical Specifications.

This letter contains no new Regulatory Commitments. Should you have any questions concerning the content of this letter, please contact me at 802-380-5124.

Sincerely, 9A~\\?2 JAH/saw

Attachments: Licensee Event Report 2024-003-00 GNRO2024-00029 Page 2 of 3

cc: NRC Senior Resident Inspector Grand Gulf Nuclear Station Port Gibson, MS 39150

U.S Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 GNRO2024-00029 Page 3 of 3

Attachment Licensee Event Report 2024-003-00

Abstract

On April 2, 2022, at 0301 CT, while the plant was in MODE 4 with all control rods inserted during a refuel outage, Grand Gulf Nuclear Station identified a failed post work leakage rate test of Feedwater Inlet Check Valve, 1 B21 F032B. An operability evaluation of the valve was performed, an d the valve was inappropriately determined to be operable. The valve was returned to service, and the plant returne d to MODE 1 at the end of the refuel outage.

On June 27, 2024, NRC inspectors identified a Green finding and as sociated Non-Cited Viol at ion of Technic al Specification 3.6.1.3, " Primary Containment Isolation Valves" (PCIV) for failure to ensure each PCIV was op erable.

Valve 1 B21 F032B failed the leakage rate test due to degradation and wear of the valve seat. The operator failed to properly evaluate the operability due to a lack of understanding of the Primary Containment Leakage Rate T esting (Appendix J) program requirements.

There was no impact on the health and safety of the public or reactor safety. The feedwater isolation shutoff valve 1 B21 F065B would have maintained leakage rates for the containment penetration; therefore, there was no significant risk to containment integrity.

Plant Conditions

At the time of the event, Grand Gulf Nuclear Station was in MODE 4 (Cold Shutdown) with all control rods inserted at zero percent reactor power. The station was performing a post-work leakage rate test on Feedwater Inlet Check Valve 1821F032B.

Description of Event

On April 2, 2022, during the performance of the post work leakage rate test of the Feedwater Inlet Check Valve 1821 F032B, a failing leakage rate of 7650 milliliters per minute was observed. A Condition Report was issued per procedure, and an operability evaluation was performed using the past operability, the technical specification surveillance requirement, and the Primary Containment Leakage Rate Testing (Appendix J) program requirements. An incorrect assumption about the Appendix J requirements was made, and it was determined that the identified leakage was within the allowable leakage rate based on the surveillance requirements. The operability evaluation incorrectly determined that Feedwater Inlet Check Valve 1821 F032B, was operable, and the valve remained in service for the 24-month fuel cycle.

On June 27, 2024, as part of the Biennial Problem Identification and Resolution Inspection Report 05000416/2024010, the NRC inspectors identified a Green finding and associated Non-Cited Violation of Technical Specification (TS) 3.6.1.3, "Primary Containment Isolation Valves" (PCIV) for failure to ensure each PCIV was operable following a failed leakage rate test of 1821 F032B during a refueling outage. A violation of TS 3.0.4 was also identified for making a mode change without meeting the requirements to do so as a result of not meeting TS 3.6.1.3.

Reportability

This report is made in accordance with 10 CFR 50.73(a)(2)(i)(B) for an operation of condition which was prohibited by the plant's Technical Specifications. TS LCO 3.6.1.3 requires each PCIV to be OPERABLE. Due to incorrect operability evaluation, Required Actions C and E were not taken.

Cause(s)

The direct cause of the event was degradation and wear of the valve's seat which resulted in the failed leakage rate test.

An additional cause of insufficient knowledge of the Appendix J program requirements by the Senior Reactor Operators (SROs) was also identified as the cause of the incorrectly performed operability evaluation.

Corrective Actions

Completed Actions: Repairs to the valve seat were made during 2024 refuel outage. Post-work leak rate testing was completed satisfactorily and indicated a leak rate of zero millimeters per minute.

Planned Actions: Update Operability Training for SROs with a focus on Code testing requirements.

Safety Significance

There was no impact on the health and safety of the public or reactor safety. The feedwater isolation shutoff valve 1821 F065B would have maintained leakage rates for the containment penetration; therefore, there was no significant risk to containment integrity.

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