05000321/LER-2024-002, Manual Reactor Trip Due to Loss of Feedwater

Manual Reactor Trip Due to Loss of Feedwater

ML24130A268
Person / Time
Site:	Hatch
Issue date:	05/09/2024
From:	Busch M Southern Nuclear Operating Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
NL-24-0166 LER 2024-002-00
Download: ML24130A268 (1)

LER-2024-002, Manual Reactor Trip Due to Loss of Feedwater

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv)(A), System Actuation
3212024002R00 - NRC Website

text

-~ Southern Nuclear Matt Busch Hatch Nuclear Plant Vice President - Plant Hatch 11028 Hatch Parkway N011h Baxley,GA 31513 9125375859 tel 9 I 2 366 2077 fax

May 9, 2024

Docket Nos.: 50-321 NL-24-0166

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

Edwin I. Hatch Nuclear Plant LER 2024-002-00 Unit 1 Manual Reactor Trip Due to Loss of Feedwater

Ladies and Gentlemen:

In accordance with the requirements of 10 CFR 50.73 (a)(2)(iv)(A), Southern Nuclear Operating Company hereby submits the enclosed Licensee Event Report.

This letter contains no NRC commitments. If you have any questions, please contact the Hatch Licensing Manager, Jimmy Collins, at 912.453.2342.

Respectfully submitted,

Matt Busch Vice President - Hatch

MSB / JMH

Enclosure : LER 2024-002-00

Cc: Regional Administrator, Region II NRR Project Manager - Hatch Senior Resident Inspector - Hatch RTYPE: CHA02.004 Enclosure to NL-24-0166 LER 2024-002-00

Edwin I. Hatch Nuclear Plant Unit 1 Licensee Event Report 2024-002-00

Manual Trip Due to Loss of Feedwater

Enclosure

LER 2024-002-00

Abstract

At 1338 EDT on 3/11/2024, while Unit 1 was in MODE 1 at 35% power and performing power ascension activities, the reactor was manually tripped due to reactor water level decreasing following the trip of the 'A' Reactor Feed Pump (RFP) on low suction pressure. Due to the power level at the time, the 'B' RFP had not been placed in service. Closure of Containment Isolation Valves (CIV's) in multiple systems and actuation of High Pressure Coolant Injection (HPCI) and Reactor Core Isolation Cooling (RCIC) pumps occurred as a result of reaching the respective actuation setpoints on reactor water level as designed. The 'B' RFP was placed in service to control water level at 1340 EDT on 3/11/2024.

The cause of the 'A' RFP trip was the use of the incorrect procedure section for isolation of a condensate pump while the main condenser was under vacuum. This allowed air leakage into the system which resulted in the low suction pressure trip of the 'A' RFP. The Condensate & Feedwater System procedure has been revised to clearly direct the performer to the appropriate section.

EVENT DESCRIPTION

At 1338 EDT on 3/11/2024, while Unit 1 was in MODE 1 at 35% power and performing power ascension activities, the reactor was manually tripped due to reactor water level decreasing following the trip of the 'A' Reactor Feed Pump (RFP)(EIIS Code: P) on low suction pressure. Due to the power level at the time, the 'B' RFP had not been placed in service. Closure of Containment Isolation Valves (CIVs)(EIIS Code: ISV) in multiple systems and actuation of High Pressure Coolant Injection (HPCl)(EIIS Code: BJ) and Reactor Core Isolation Cooling (RCIC)(EIIS Code: BN) pumps occurred as a result of reaching the respective actuation setpoints on reactor water level as designed. The 'B' RFP was placed in service to control water level at 1340 EDT on 3/11/2024. Once the 'B' RFP was placed in service, HPCI and RCIC were secured at 1340 EDT and 1342 EDT respectively.

EVENT CAUSE ANALYSIS

Based on causal analysis, the cause of the 'A' RFP trip was the use of the incorrect procedure section for isolation of a condensate pump while the main condenser was under vacuum. This allowed air leakage into the system which resulted in the low suction pressure trip of the 'A' RFP.

SAFETY ASSESSMENT AND REPORTABILITY

There were no actual safety consequences as a result of this event. All safety related systems functioned as designed during this event. The operating crew responded correctly to the event. The applicable abnormal/emergency operating procedures were entered. The event was within the analysis of the Updated Final Safety Analysis Report (UFSAR) Chapter 15.

This event is reportable per 10 CFR 50. 73(a)(2)(iv)(A), as any event or condition that resulted in manual or automatic actuation of any of the systems listed in paragraph (a)(2)(iv)(B) of this section. Systems that actuated during this event that are listed in (a)(2)(iv)(B) include; the Reactor Protection System (RPS)(EIIS Code: IG), general Containment Isolation Valves (CIV) in more than one system, ECCS including the HPCI system, and the RCIC system.

CORRECTIVE ACTIONS

The Condensate & Feedwater System procedure has been revised to clearly direct the performer to the appropriate section for isolating a condensate pump when the main condenser is under vacuum.

PREVIOUS SIMILAR EVENTS

On 09/29/2000 at 1357 EDT, Unit 1 was in the Run mode at a power level of approximately 1520 CMWT (55 percent rated thermal power). At that time, the reactor was scrammed manually following a trip of the operating Reactor Feedwater Pump (RFP) and a decrease in water level. Personnel inserted the scram in anticipation of an automatic scram on low water level.

A RFP was placed into service to maintain level. This event was caused by component failure. During the implementation of a clearance to isolate a condensate pump, air was introduced into the condensate pump suction header through a leaking pump suction isolation valve. The presence of air led to the trip of the operating RFP on low suction pressure. LER 2000-011-00.