05000445/LER-2023-001, Automatic Reactor Trip Due to Lo-Lo Steam Generator Level
| ML23227A145 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 08/15/2023 |
| From: | John Lloyd Luminant Generation Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| CP-202300404, TXX-23065 LER 2023-001-00 | |
| Download: ML23227A145 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 4452023001R00 - NRC Website | |
text
m Luminant CP-202300404 TXX-23065 August 15, 2023 Jay J. Lloyd Senior Director, Engineering & Regulatory Affairs U. S. Nuclear Regulatory Commission A TIN: Document Control Desk Washington, DC 20555-0001
Subject:
Comanche Peak Nuclear Power Plant (CPNPP)
Docket Nos. 50-445 Automatic Reactor Trip Due to Lo-Lo Steam Generator Level Licensee Event Report 445/23-001-00
Dear Sir or Madam:
Ref Comanche Peak Nuclear Power Plant (Vistra Operations Company LLC)
P.O. Box 1002 6322 North FM 56 Glen Rose, TX 76043 T 254.897.6067 10 CFR50.73 Enclosed is Licensee Event Report (LER) 1-23-001-00, "Automatic Reactor Trip Due to Lo-Lo Steam Generator Level" for Comanche Peak Nuclear Power Plant (CPNPP) Unit 1.
This communication contains no new commitments regarding CPNPP Units 1 and 2.
Should you have any questions, please contact Kassie Mandrell at (254) 897-6987 or Kassie.Mandrell@luminant.com.
Attachment: LER 23-001-00 (4 pages) c (email) -
John Monninger, Region IV Uohn.Monninger@nrc.gov]
Dennis Galvin, NRR [Dennis.Galvin@nrc.gov]
John Ellegood, Senior Resident Inspector, CPNPP Uohn.Ellegood@nrc.gov]
Dominic Antonangeli, Resident Inspector, CPNPP [Dominic.Antonangeli@nrc.gov]
Abstract
Comanche Peak Nuclear Power Plant
445 4
Automatic Reactor Trip Due to Lo-Lo Steam Generator Level 06 16 2023 2023 001 00 08 15 2023 Mode 1 100
Kassie Mandrell 254-897-6987 J.
369 Y
1
2023 On June 16, 2023, nit 1 was operating at 100% power. At 18:22, the 1B Main Feedwater Pump (MFP) began indicating
oscillating speed. The Žscillations increased in severity and became unresponsive to manual control input. Due to the loss
of control, the 1B MFP was manually tripped as it approached the overspeed setpoints. Following the manual trip of the 1B
MFP the Unit responded with an automatic runback to 700MW. Following the runback, the combined effects of the entire
transient resulted in an automatic reactor trip due to Steam Generator #4 Lo-Lo water level.
The direct cause of this event was a degraded servo on the 1B MFP. Vendor troubleshooting of the component is ongoing
and the failure has not yet been determined. Results of the failure analysiswill be provided in a supplemental report.
Corrective action included replacement of the servo.
All times are in Central Daylight Time (CDT).
- (Page of
- 3. LER NUMBER YEAR SEQUENTIAL NUMBER REV NO.
052 050 C. SAFETY CONSEQUENCES AND IMPLICATIONS OF THE EVENT A turbine trip is an ANS Condition II event (Faults of Moderate Frequency). When the reactor was automatically tripped the Auxiliary Feedwater System started to provide feedwater to the steam generators. The reactor trip on lo-lo water level in any steam generator provides the necessary protection against a loss of normal feedwater.
An automatic reactor trip was exercised and the Auxiliary Feedwater System started automatically as expected and all plant safety systems responded as designed during the resultant transient. This event had no impact on nuclear safety, reactor safety, radiological safety, environmental safety or the safety of the public. This event has been evaluated as not meeting the definition of a safety system functional failure per 10 CFR 50.73(a)(2)(v).
IV. CAUSE OF THE EVENT
The direct cause of this event was a degraded servo on the 1B MFP. Vendor troubleshooting of the component is ongoing and the failure has not yet been determined. Results of the failure analysiswill be provided in a supplemental report.
V. CORRECTIVE ACTIONS
Corrective actions include replacement of the 1B MFP servo and increaseG monitoring of speed oscillations. Additional corrective actions resulting from the equipment analysLs will be included in the supplemental report.
VI. PREVIOUS SIMILAR EVENTS
There have been no previous similar reportable events at CPNPP in the past three years.
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Comanche Peak Nuclear Power Plant 445 23 001 00