05000416/LER-2024-002, Automatic Actuation of Reactor Protection System

Automatic Actuation of Reactor Protection System

ML24149A159
Person / Time
Site:	Grand Gulf
Issue date:	05/28/2024
From:	Hardy J Entergy Operations
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
GNRO2024-00020 LER 2024-002-00
Download: ML24149A159 (1)

LER-2024-002, Automatic Actuation of Reactor Protection System

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv)(A), System Actuation
4162024002R00 - NRC Website

text

) entergy GNRO2024-00020 May 28, 2024 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Entergy Operations, Inc.

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 SUBJECT:

Grand Gulf Nuclear Station, Unit 1 Licensee Event Report 2024-002-00, Automatic Actuation of Reactor Protection System Grand Gulf Nuclear Station, Unit 1 Docket No. 50-416 Renewed License No. NPF-29 Attached is Licensee Event Report (LER) 2024-002-00, Automatic Actuation of Reactor Protection System. This report is being submitted in accordance with 1 0 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).

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, JAH/saw Attachments: Licensee Event Report 2024-002-00

GNRO2024-00020 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

G N RO2024-00020 Page 3 of 3 Attachment Licensee Event Report 2024-002-00

Abstract

On March 26, 2024 at 1115 CDT, Grand Gulf Nuclear Station experienced an automatic actuation' of the reactor protection system (RPS) due to high reactor coolant system (RCS) pressure while performing in-service leak testing. The plant was in Mode 4 at zero percent power with all control rods inserted at the time of the RPS actuation.

The RPS actuation occurred due to a valid high RCS pressure signal and all plant systems responded as designed. The high pressure condition occurred due to inadvertent isolation of the blowdown discharge flow path.

There were no safety consequences impacting the plant or public as a result of this event. The reactor was shutdown and subcritical at the time of the actuation.

PLANT CONDITIONS I

2. DOCKET NUMBER

3. LER NUMBER 18 SEQUENTIAL REV NUMBER NO.

416

- I 1-0 002 At the time of the event, Grand Gulf Nuclear Station (GGNS) was in Mode 4 (Cold Shutdown) with all control rods inserted at 0% reactor power. The station was performing in-service leak testing with reactor coolant system (RCS) pressure at approximately 1025 psig.

DESCRIPTION OF EVENT During the performance of in-service leak testing, RCS pressure was being maintained with control rod drive (CRD) flow and reactor water cleanup (RWCU) blowdown to the main condenser. The Control Room was transferring RWCU blowdown to the radwaste system when RCS pressure began to rise. Reactor operators took action to reduce CRD flow, but RCS pressure did not reduce rapidly. The reactor protection system actuated as designed on high RCS pressure.

Operators responded per the off-normal event procedure and the RPS was reset.

REPORT ABILITY The automatic RPS actuation was initially reported to the NRC as a 4-hour report per 10 CFR 50.72(b)(2)(iv)(B) on March 26, 2024. This report is made in accordance with 10 CFR 50. 73(a)(2)(iv)(A) for any event or condition that resulted in manual or automatic actuation of any system listed in paragraph 1 O CFR 50. 73(a)(2)(iv)(B).

CAUSE The cause of the event was RWCU blowdown discharge flow path was isolated with the RCS at high pressure. Operators believed that the RWCU blowdown flow path to the main condenser could be isolated before aligning a discharge flow path to the radwaste system.

CORRECTIVE ACTIONS Completed actions:

• The RWCU discharge flow path was re-established.

• The RPS was reset.

Planned action:

• Revise integrated operating instruction procedure 03-1-01-6 "Reactor Vessel In-Service Leak Test" to add specific guidance for swapping RWCU discharge flow paths.

SAFETY SIGNIFICANCE There were no safety consequences, real or potential, resulting from the event. The reactor was sub-critical with all rods inserted at the time of the event and all systems responded as designed.

PREVIOUS SIMILAR EVENTS None Page 2

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