05000416/LER-2025-001, Manual Scram Due to Degraded Condenser Vacuum
| ML25106A148 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 04/16/2025 |
| From: | Hardy J Entergy Operations |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| GNRO2025-00014 LER 2025-001-00 | |
| Download: ML25106A148 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 4162025001R00 - NRC Website | |
text
S) entergy G N RO2025-00014 April 16, 2025 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Entergy Operations, Inc.
P.O. Box 756 Port Gibson, Mississippi 39150 Jeffery A. Hardy Manager Regulatory Assurance Grand Gulf Nuclear Station Tel: 802-380-5124 10 CFR 50.73
SUBJECT:
Grand Gulf Nuclear Station, Unit 1 Licensee Event Report 2025-001-00, Manual Scram Due to Degraded Condenser Vacuum Grand Gulf Nuclear Station, Unit 1 Docket No. 50-416 Renewed License No. NPF-29 Attached is Licensee Event Report (LER) 2025-001-00, Manual Scram Due to Degraded Condenser Vacuum. This report is being submitted in accordance with 10 CFR 50.73(a)(2)(iv)(A), for events or conditions that resulted in the manual or automatic actuation of the reactor protection system.
This letter contains no new Regulatory Commitments. Should you have any questions concerning the content of this letter, please contact me at 802-380-5124.
Sincerely, Digitally signed by Jeff Hardy DN: cn=Jeff Hardy, o=Grand Gulf Jeff Hardy Nuclear Station, ou=Manager, Regulatory Assurance,
email:::jhardy@entergy.com Date: 2025.04.16 09:52:49 -05'00' JAH/saw Attachments: Licensee Event Report 2025-001-00
GNRO2025-00014 Page 2 of 3 cc:
NRC Senior Resident Inspector Grand Gulf Nuclear Station Port Gibson, MS 39150 U.S Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
GNRO2025-00014 Page 3 of 3 Attachment Licensee Event Report 2025-001-00
Abstract
On February 15, 2025, at 2240 CT, Grand Gulf Nuclear Station, Unit 1 operators initiated a manual Reactor Protection System (RPS) actuation due to degrading condenser vacuum which resulted from a loss of seal steam. Rainwater intrusion had entered the enclosure building due to degraded roofing. The water entered a load control center which caused an overcurrent and loss of power in a static inverter. The loss of the static inverter resulted in a loss of seal steam that led to a degraded condenser vacuum. All control rods were fully inserted with no complications.
The cause of the event was determined to be water intrusion due to degraded roofing of the enclosure building.
This report is being made in accordance with 10 CFR 50.73(a)(2)(iv)(A) for any event that resulted in manual actuation of the RPS system.
Plant Conditions
Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />. Reported lessons learned are incorporated into the licensing process and fed back to industry. Send comments regarding burden estimate to the FOIA, Library, and Information Collection Branch (T-6 A10M), U.S.
Nuclear Regulatory Commission, Washington, DC 20555-0001,
or by e-mail to lnfocollects.Resource@nrc.gov, and the 0MB reviewer at: 0MB Office of Information and Regulatory Affairs, (3150-0104), Attn: Desk Oflicer for the Nuclear Regulatory Commission, 725 17th Street NW, Washington, DC 20503. The NRC may not conduct or sponsor, and a person is not required to respond to, a collection of information unless the document requesting or requiring the collection displays a currently valid 0 MB control number.
- 2. DOCKET NUMBER YEAR 00416 2025
- 3. LER NUMBER SEQUENTIAL NUMBER 001 REV NO.
00 At the time of the event Grand Gulf Nuclear Station (GGNS), Unit 1 was in MODE 1 at 84 percent power. The Division 2 Emergency Diesel Generator was inoperable due to scheduled maintenance, and all other safety systems were operable.
Description of Event
On February 15, 2025, rainwater intrusion entered the enclosure building due to degraded roofing. The water entered a load control center which caused an overcurrent and loss of power in a static inverter.
At 2237 CT, the loss of power to the static inverter caused a loss of seal steam and degrading condenser vacuum. At 2240 CT, a manual Reactor Protection System (RPS) actuation was initiated due to degrading condenser vacuum. All control rods fully inserted, and there were no complications.
Reportability
This report is being made in accordance with 1 O CFR 50.73(a)(2)(iv)(A) for any event that resulted in manual actuation of the RPS system.
Cause(s)
The direct cause of the event was water intrusion due to degraded enclosure building roofing which entered the load control center and caused an overcurrent condition and loss of power to the static inverter.
Corrective Actions
Completed Actions:
- - Restored the function of the enclosure building roof drains.
- - Replaced damaged Load Center Bus components Planned Actions:
- - Replace enclosure building roof.
- - Update preventative maintenance instructions for roof inspections to ensure that degradation is identified.
- - Review all single power source inverters to identify and correct any single point vulnerabilities.
Safety Significance
There were no actual safety consequences associated with this condition. Plant systems responded as designed and the unit was brought to Mode 3 by Control Room Operators.
Previous Similar Events
None identified. Page 2 of 2