05000282/LER-2023-001, Reactor Trip, Auxiliary Feedwater and Emergency Service Water System Actuation Due to Electrical Transient in DC Control Power Cables
| ML23338A277 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 12/04/2023 |
| From: | Borgen T Northern States Power Company, Minnesota, Xcel Energy |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| L-PI-23-032 LER 2023-001-00 | |
| Download: ML23338A277 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 2822023001R00 - NRC Website | |
text
1717 Wakonade Drive Welch, MN 55089 L-PI-23-032 10 CFR 50.73 December 04, 2023 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Prairie Island Nuclear Generating Plant, Units 1 and 2 Docket Nos. 50-282 and 50-306 Renewed Facility Operating License Nos. DPR-42 and DPR-60 Prairie Island Nuclear Generating Plant Unit 1 Licensee Event Report 2023-001-00 Northern States Power Company, a Minnesota corporation, doing business as Xcel Energy (hereafter NSPM), hereby submits Licensee Event Report (LER) 50-282/2023-001-00 per 10 CFR 50.73(a)(2)(iv)(A).
Summary of Commitments This letter makes no new commitments and no revisions to existing commitments.
Timothy P. Borgen Plant Manager, Prairie Island Nuclear Generating Plant Northern States Power Company - Minnesota Enclosure cc:
Administrator, Region III, USNRC Project Manager, Prairie Island, USNRC Resident Inspector, Prairie Island, USNRC State of Minnesota
ENCLOSURE PRAIRIE ISLAND NUCLEAR GENERATING PLANT LICENSEE EVENT REPORT 50-282/2023-001-00 3 pages follow
Abstract
At 11:10 on October 19, 2023, with Prairie Island Nuclear Generating Plant Unit 1 operating at 100 percent power in Mode 1, power operations, grounds on DC control power cabling from the plant to the substation control house. This caused multiple substation breakers to spuriously open leading to a Unit 1 turbine and reactor trip with a loss of all non-safety related busses and the actuation of Auxiliary Feedwater and Cooling Water. Operators responded to the event in accordance with approved procedures and safely placed the plant in Mode 3.
The cause of the event is currently under evaluation and will be provided later as a supplement to this LER.
There were no radiological, environmental, or industrial impacts associated with this event. The health and safety of the public and site personnel were not impacted during this event.
This event is reportable under 10 CFR 50.73(a)(2)(iv)(A) due to a Reactor Trip, a valid Pressurized Water Reactor Auxiliary Feedwater actuation, and actuation of Emergency Service Water system.Page of
- 3. LER NUMBER YEAR SEQUENTIAL NUMBER REV NO.
052 050 There were no radiological, environmental, or industrial impacts associated with this event. The health and safety of the public and site personnel were not impacted during this event.
CAUSE OF THE EVENT
Initial troubleshooting has determined the most likely cause of the event to be a result of directional boring for 2R cable replacement that disturbed DC control power cabling from the plant to the substation control house. This caused multiple substation breakers to spuriously open leading to a Unit 1 turbine and reactor trip with a loss of all NSR busses, and the actuation of AFW and CL. The direct cause of this event is being investigated and will be provided in the supplement to this LER.
CORRECTIVE ACTIONS
The station is currently investigating the cause(s) behind the event. Unit 1 is currently in Mode 5, cold shutdown and Unit 2 is defueled. Additional corrective actions will be provided in the supplement to this LER.
PREVIOUS SIMILAR EVENTS
The review of the similar past events will be provided in the supplement to this LER.
ADDITIONAL INFORMATION
All times are in Central Daylight Time.
Energy Industry Identification System (EIIS) codes are identified in the text as [XX].
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Prairie Island Nuclear Generating Plant, Unit 1
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