05000424/LER-2023-002, Manual Reactor Trip Due to Failure of a Heater Drain Pump and Standby Condensate Pump
| ML23284A427 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 10/11/2023 |
| From: | Dean E Southern Nuclear Operating Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| NL-23-0769 LER 2023-002-00 | |
| Download: ML23284A427 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 4242023002R00 - NRC Website | |
text
A Southern Nuclear October 11, 2023 Docket Nos.: 50-424 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin D. Dean Ill Site Vice President Vogtle Units 1-2 Vogtle Electric Generating Plant Unit 1 licensee Event Report 2023-002-00 7821 River RO Waynesboro GA, 30830 706-848-0001 tel 706-848-3321 fax NL-23-0769 Manual Reactor Trip Due to Failure of a Heater Drain Pump and Standby Condensate Pump Ladies and Gentlemen:
In accordance with the requirements of 10 CFR 50.73(a)(2)(iv)(A), Southern Nuclear Operating Company is submitting the enclosed Licensee Event Report, 2023-002-00 for Vogtle Electric Generating Plant Unit 1.
This letter contains no NRC commitments. If you have any questions, please contact Jeff Deal at (706) 848-3792.
Respectfully submitted, Site Vice President Vogtle 1&2 EDD/KCW Enclosure: Units 1 Licensee Event Report 2023*002-00 cc:
Regional Administrator NRR Project Manager - Vogtle 1 & 2 Senior Resident Inspector - Vogtle 1 & 2 RType: CVC7000
U. S. Nuclear Regulatory Commission NL-23-0769 Page 2 Vogtle Electric Generating Plant Unit 1 Licensee Event Report 2023-002-00 Manual Reactor Trip Due to Failure of a Heater Drain Pump and Standby Condensate Pump Enclosure Units 1 Licensee Event Report 2023-002-00
Abstract
On August 22, 2023 at 1724 EDT, with Unit 1 in Mode 1 and 100 percent power, the Control Room Operators manually tripped the reactor due to lowering Main Feed pump suction pressure and Steam Generator water levels. The initiating event was Heater Drain pump 'B' motor tripping on overcurrent. The cause of the reactor trip was the failure of Condensate pump 'A' to start automatically or manually. The trip was not complex, and all other systems responded normally post trip. At 1735, the Control Room was notified of the Heater Drain pump 'B' motor being on fire, and the fire was extinguished by the onsite fire brigade at 1807. Units 2, 3, and 4 were not affected. The operating crew performed as expected. The unit was stabilized in Mode 3 with decay heat removed through the Steam Dumps to the Condenser.
The Heater Drain Pump 'B' motor was replaced and the Condensate Pump 'A' differential and lockout relays were replaced.
Due to the actuation of the Reactor Protection System and the Auxiliary Feedwater System, this is being reported under 10 CFR 50.73 (a)(2)(iv)(A).
IA. Event Description
- 2. DOCKET NUMBER
- 3. LER NUMBER I
00424 NUMBER NO.
I YEAR SEQUENTIAL REV t5-I 002 1-G On August 22, 2023 at 1724 EDT, with Unit 1 in Mode 1 and 100 percent power, the Control Room Operators manually tripped the reactor due to lowering Main Feed pump (SJ) suction pressure and Steam Generator water levels. The initiating event was Heater Drain pump 'B' (SN) tripping on overcurrent. The cause of the reactor trip was the failure of Condensate pump 'A' (SD) to start automatically or manually. The trip was not complex, and all other systems responded normally post trip. At 1735, the Control Room was notified of the Heater Drain pump 'B' motor being on fire, and the fire was extinguished by the onsite fire brigade at 1807. Units 2, 3, and 4 were not affected. The operating crew performed as expected. The unit was stabilized in Mode 3 with decay heat removed through the Steam Dumps (JI) to the Condenser (SG). The components that failed were the General Electric 5KV84473466501 Heater Drain pump 'B' motor and Basler Electric G2F-A 1 P-H 1 N6F differential relay.
There were no Structures, Systems, or Components (SSCs) that were inoperable at the beginning of the event that contributed to the event.
Due to the actuation of the Reactor Protection System (JC) and Auxiliary Feedwater System (BA) from the reactor trip, this issue is reported under 10 CFR 50. 73 (a)(2)(iv)(A).
B. Cause of Event
The initiating event was Heater Drain pump 'B' tripping on overcurrent. The cause of the reactor trip was the failure of Condensate pump 'A' to start automatically or manually. A failure analysis was performed on Heater Drain pump 'B'.
Results revealed that the failure was due to a surge experienced by the motor, causing a phase-to-phase fault.
Condensate pump 'A' failed to start due to the differential relay being in the tripped position, causing the lockout relay to trip and preventing breaker closure. Subsequent troubleshooting could not determine the cause of the differential relay being tripped prior to the pump start demand.
C. Safety Assessment
Heater Drain pump 'B' and Condensate pump 'A' serve no safety-related function for the unit. When the reactor was manually tripped, all the appropriate safety systems operated as designed, and the operating crew responded as expected.
The Auxiliary Feedwater System actuated as designed and all Control Rods [AA] fully inserted into the core. The event was
~ithin the analysis of the Updated Final Safety Analysis Report, Chapter 15, and there was no release of radioactivity.
Hence, the safety significance of this issue is very low.
D. Corrective Actions
The corrective actions were replacement of the Heater Drain pump 'B' motor and the differential relay for the Condensate pump 'A' breaker. Additionally, the lockout relay for Condensate pump 'A' was conservatively replaced.
E. Previous Similar Events
None. Page 2
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