05000275/LER-2023-001, Unit 1 Manual Reactor Trip at Low Power
| ML23331A967 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 11/27/2023 |
| From: | Petersen D Pacific Gas & Electric Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| DCL-23-123 LER 2023-01-00 | |
| Download: ML23331A967 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 2752023001R00 - NRC Website | |
text
Pacific Gas and Electric Company"'
PG&E Letter DCL-23-123 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Docket No. 50-275, OL-DPR-80 Diablo Canyon Power Plant, Unit 1 Dennis B. Petersen Station Director Diablo Canyon Power Plant Mail code 104/51502
. P.O. Box 56 Avila Beach, CA 93424 805,545,4022 Dennis. Petersen@pge.com 10 CFR 50.73 Unit 1 Licensee Event Report 2023-01 -00, Unit 1 Manual Reactor Trip at Low Power
Dear Commissioners and Staff,
In accordance with the requirements of 10 CFR 50.73(a)(2)(iv)(A), Pacific Gas and Electric Company (PG&E) hereby submits the enclosed Diablo Canyon Power Plant (DCPP) Unit 1 Licensee Event Report.
PG&E makes no new or revised regulatory commitments (as defined by NEI 99-04) in this report. All corrective actions identified in this letter will be implemented in accordance with the DCPP Corrective Action Program.
This event did not adversely affect the health and safety of the public.
If you have any questions or require additional information, please contact Mr. James Morris, Regulatory Services Manager, at (805) 545-4609.
Sincerely, Dennis B. Petersen Date dqmg/51206375 Enclosure cc/enc:
Diablo Distribution Mahdi 0. Hayes, NRC Senior Resident Inspector INPO Samson S. Lee, NRR Senior Project Manager John D. Monninger, NRC Region IV Administrator A
membe r of t he STARS Allia nce Ca l laway
- Diablo Ca nyo n
- Pa lo Ver de
- Wol f Creek
Abstract
At 20:14 Pacific Daylight Time on September 30,2023, with Diablo Canyon Power Plant (DCPP) Unit 1 in Mode 1 at approximately 11 percent reactor power in preparation for a pre-planned manual reactor trip into a scheduled refueling outage, the reactor was manually tripped due to increasing water level in Feedwater Heater (FWH) 1-5A caused by a secondary system dump valve which remained in the closed position. Auxiliary feedwater was manually started in accordance with plant procedures.
This event is being reported per 10 CFR 50.73(a)(2)(iv)(A).
The cause of the increased feedwater level was due to Level Control Valve LCV-9 remaining in the closed position.
The valve has been repaired and corrective actions will be managed in accordance with the DCPP Corrective Action Program.
There was no plant or public safety impact.
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I. Reporting Requirements
This event is being reported in accordance with 10 CFR 50.73(a)(2)(iv)(A) and the associated guidance of NUREG-1022, Revision 3, due to a manual reactor trip and the subsequent manual actuation of the auxiliary feedwater (AFW) system in accordance with plant procedures.
This event was initially reported in Event Notification 56769 in accordance with the requirements of 10 CFR 50.72(b)(2)(iv)(B) and 10 CFR 50.72(b)(3)(iv)(A).
II. Plant Conditions
At the time of the event, Diablo Canyon Power Plant (DCPP) Unit 1 was in Mode 1 at approximately 11 percent power in preparation for pre-planned manual reactor trip for entry into a scheduled refueling outage.
III. Problem Description A. Background The condensate system and main feedwater system (MFWS) are non-safety-related systems whose function is to supply preheated feedwater to the steam generators (SGs). These systems improve overall plant efficiency by regeneratively heating feedwater as it is pumped through low and high-pressure feedwater heaters (FWHs) prior to the entering the SGs. The condensate and MFWS are not required to ensure safe shutdown of the nuclear steam supply system.
B. Event Description
At 20:14 Pacific Daylight Time on September 30,2023, with DCPP Unit 1 in Mode 1 at approximately 11 percent reactor power in preparation for a pre-planned manual reactor trip into a scheduled refueling outage, the reactor was manually tripped due to increasing water level in FWH 1-5A. Following the trip, AFW was manually started in accordance with station procedures. The cause of the increasing water level in the FWH was determined to be due to dump valve LCV-9 remaining in the closed position. The valve was subsequently repaired and associated corrective actions will be managed in accordance with the DCPP Corrective Action Program.
C. Status of Inoperable Structures, Systems, or Components that Contributed to the Event There were no inoperable Technical Specification structures, systems, or components that contributed to the event.
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D. Method of Discovery
Increased water level in FWH 1-5A was validated by Operations personnel following the receipt of the associated control room annunciator.
E. Operator Actions
The Operations crews responded to this event in accordance with plant operating procedures.
F. Safety System Responses Plant systems responded as expected following the manual reactor trip.
IV. Cause of the Problem The cause of the water level increase in FWH 1-5A was a result of dump valve LCV-9 remaining in the closed position.
V. Assessment of Safety Consequences
There was no plant or public safety impact.
VI. Corrective Actions
Dump valve LCV-9 was repaired. Additional follow-up corrective actions will be managed in accordance with the DCPP Corrective Action Program.
VII. Additional Information
None.