05000416/LER-2021-003, High Pressure Core Spray Declared Inoperable
| ML21308A491 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 11/04/2021 |
| From: | Hardy J Entergy Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| GNRO2021/00036 LER 2021-003-00 | |
| Download: ML21308A491 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 4162021003R00 - NRC Website | |
text
GNRO2021/00036 November 04, 2021
. 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 2021-003-00, High Pressure Core Spray Declared Inoperable.
Grand Gulf Nuclear Station, Unit 1 Docket No. 50-416 Renewed License No. NPF-29 Attached is Licensee Event Report 2021-003-00, High Pressure Core Spray Declared Inoperable. This report is being submitted in accordance with 10 CFR 50.73(a)(2)(v)(D), any event or condition that could have prevented the fulfillment of the safety function needed to mitigate the consequences of an accident.
This letter contains no new Regulatory Commitments. Should you have any questions concerning the content of this letter, please contact Jeff Hardy, Regulatory Assurance Manager at 802-380-5124.
JAH/saw Attachments: Licensee Event Report 2021-003-00
GN RO2021 /00036 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
GNRO2021/00036 Page 3 of 3 Attachment Licensee Event Report 2021-003-00
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 08/31/2023 (08-2020)
()PR Rlct,<.,
- 1. Facility Name
~- Docket Number 3.Page Grand Gulf Nuclear Station, Unit 1 05000416 1 OF2
- 4. Title Hiah Pressure Core Sorav Declared lnooerable
- 5. Event Date
- 6. LER Number
- 7. Report Date
- 8. Other Facilities Involved Sequential Rev Facility Name Docket Number Month Day Year Year Month Day Year N/A Number No.
05000 N/A 09 09 2021 2021
- - 003 -
00 11 04 2021 Facility Name Docket Number N/A 05000 N/A
- 9. Operating Mode 110. Power LOO 1
70 N/A N/A N/A
~bstract (Limit to 1560 spaces, i.e., approximately 15 single-spaced typewritten lines)
On September 9, 2021, at 0033 CT, while Grand Gulf Nuclear Station was operating in MODE 1 at 70 percent power, the control room received the following alarms: High Pressure Core Spray System (HPCS) Out of Service, along with HPCS Motor Operated Valve/Overload Power loss status light. Additionally, the HPCS Min Flow to Suppression Pool light indication was lost.
An operator and electrician were dispatched to the HPCS Min Flow to Suppression Pool Breaker, reporting back that the breaker was in the closed position. Troubleshooting identified the following: HPCS MIN FLO TO SUPP POOL, control circuit alarm relay, shorted causing the control transformer fuse to fail.
The direct cause of equipment failure was the alarm relay, associated with breaker HPCS Min Flow to Suppression Pool Breaker, failed due to the coil shorting. This caused the control circuit fuse to blow resulting in the inability to open the High Pressure Core Spray min flow valve to the suppression pool.
Immediate action taken was to replace the damaged relay and associated control fuse.
There were no consequences to the general safety of the public, nuclear safety, industrial safety or radiological safety. No radiological releases occurred due to this event.
Plant Conditions
YEAR 2021 SEQUENTIAL NUMBER
- - 003 REV NO.
- - 00 Grand Gulf Nuclear Station (GGNS) Unit 1 was operating at 70 percent power in MODE 1. There were no Structures, Systems, or Components that were inoperable that contributed to this event.
Event Description
On September 9, 2021, at 0033 CT, the control room received the following alarms: High Pressure Core Spray System (HPCS) [BJ] Out of Service, 1H13-P601-16A-H5 along with HPCS Motor Operated Valve/Overload Power loss status light. Additionally, the HPCS Min Flow to Suppression Pool light indication was lost.
An operator and electrician were dispatched to the HPCS Min Flow to Suppression Pool Breaker [BKR] (52-170109) and reported back that breaker was in the closed position. Troubleshooting the cause of the event identified that the HPCS MIN FLO TO SUPP POOL, control circuit alarm relay [RL Y] device shorted causing the control transformer fuse to fail.
This caused the hand switch for the Min Flow Valve to be non-functional. Loss of the control fuse caused the Min Flow Valve to be inoperable and resulted in declaring HPCS inoperable. The inability to open the Min Flow Valve adversely affects overall system injection response time to inject and provide containment isolation by closing.
This event was reported under 10 CFR 50.72(b)(3)(v)(D), any event or condition which could have prevented the fulfillment of a safety function needed to mitigate the consequences of an accident. (EN 55451)
This report is made in accordance with 10 CFR 50.73(a)(2)(v)(D), any event or condition that could have prevented the fulfillment of the safety function needed to mitigate the consequences of an accident.
Safety Assessment
There were no actual consequences for this event. The event posed no threat to the health and safety of the general public or to nuclear safety as HPCS was inoperable but available. Industrial safety was not challenged, and there was no potential or actual radiological release during the event.
Event Cause(s):
The direct cause of equipment failure was the alarm relay, associated with breaker 52-170109, failed due to the coil shorting. This caused the control circuit fuse to blow resulting in the inability to open the High Pressure Core Spray min flow valve to the suppression pool.
Corrective Actions
Work Order 567580 replaced the shorted control circuit alarm relay and blown control circuit fuse. Completed.
Generate Preventive Maintenance to replace General Electric (GE) alarm relay on the same 10-year frequency as the associated circuit breakers. AR 21010831
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