05000423/LER-2022-003, Re Gas Void in the Emergency Core Cooling System Resulted in a Condition Prohibited by Technical Specifications
| ML23301A009 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 10/28/2023 |
| From: | O'Connor M Dominion Energy Nuclear Connecticut |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| 23-281 LER 2022-003-00 | |
| Download: ML23301A009 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 4232022003R00 - NRC Website | |
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Dominion Energy NudNr c-.ctlcut, Inc.
MiH1ton* Poww Slltlon 314 Rope Ferry Rold, WaterlOfd, CT 063B6 DomlnlonEneror.com U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 OCl 28 l0t3 DOMINION ENERGY NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNIT 3 LICENSEE EVENT REPORT 2022-003-00 Dominion Energye Serial No.:
23-281 MPS Lie/JP RO Docket No.: 50-423 License No.: NPF-49 GAS VOID IN THE EMERGENCY CORE COOLING SYSTEM RESULTED IN A CONDITION PROHIBITED BY TECHNICAL SPECIFICATIONS This letter forwards Licensee Event Report (LER) 2022-003-00, documenting a condition that was discovered at Millstone Power Station Unit 3 (MPS3) on August 31, 2023. This LER is being submitted pursuant to 10 CFR 50.73 (a}(2}(i)(B) as a condition prohibited by technical specifications.
There are no regulatory commitments contained in this letter or its enclosure.
Should you have any questions, please contact Mr. Dean E. Rowe at (860} 444-5292.
Sincerely,
~~
Michael J. O'Connor Site Vice President - Millstone Enclosure: LER 423/2022-003-00
Serial No.23-281 Docket No. 50-423 Licensee Event Report 2022-003-00 Page 2 of 2 cc:
U.S. Nuclear Regulatory Commission Region I 475 Allendale Road, Suite 102, King of Prussia, PA 19406-1415.
R. V. Guzman NRC Project Manager Millstone Units 2 and 3 U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 08 C2 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station
Serial No.23-281 Docket No. 50-423 Licensee Event Report 2022-003-00 ATTACHMENT LICENSEE EVENT REPORT 2022-003-00 GAS VOID IN THE EMERGENCY CORE COOLING SYSTEM RESULTED IN A CONDITION PROHIBITED BY TECHNICAL SPECIFICATIONS MILLSTONE POWER STATION UNIT 3 DOMINION ENERGY NUCLEAR CONNECTICUT, INC.
Abstract
On October 6, 2022 at 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br />, with Millstone Power Station Unit 3 in Mode 1 at 100 percent reactor power, ultrasonic testing (UT) measurements on the A train residual heat removal (RHR) piping identified a gas void greater than acceptance criteria. The most likely source of gas voids in this section of pipe was determined to be inadequate guidance in the operating procedures used to perform filling and venting activities during system restorations following the refueling outage in May 2022. The entire length of piping was vented and UT measurements at multiple locations verified that the voids were reduced to within acceptable limits. This condition is being reported pursuant to 10 CFR 50.73(a)(2)(i)(B) as any operation or condition prohibited by the plant's Technical Specifications.Page of
- 3. LER NUMBER YEAR SEQUENTIAL NUMBER REV NO.
052 050 In the normal post LOCA cold leg recirculation configuration, the RSS pumps take suction from the containment sump to provide suction to the SIH pumps and CHS pumps. The high head CHS pumps and the intermediate head SIH pumps are aligned to provide injection into the reactor coolant system (RCS) cold legs.
Should the gas void interfere with the operation of a charging pump in establishing post LOCA cold leg recirculation, EOP 35 ES-1.3, Transfer to cold leg recirculation, has instructions to open a RHR cold leg injection valve. Cold leg recirculation flow would then be provided from the RSS pumps through the RHR injection lines as well as through the SIH pumps. This would allow for successful cold leg recirculation to be established.
The containment response to a LOCA is discussed in FSAR Section 6.2.1. The peak containment temperature and pressure also occur early in the Engineered Safety Features (ESF) injection phase of the accident. The post ESF injection containment spray recirculation is not impacted by the point 10 void location.
Therefore, it is concluded that the plant response to a LOCA will be unchanged from the results as presented in the FSAR.
CORRECTIVE ACTIONS
The entire length of pipe was vented to remove gas voids. UT measurements were performed at multiple locations along the piping to verify that voids were reduced to within acceptable limits. Operating procedures have been enhanced to include instructions for filling and venting this line and assuring that ECCS piping is verified sufficiently full of water.
Additional corrective actions will be taken in accordance with the stations corrective action program.
PREVIOUS OCCURANCES There have been no similar events or conditions related to Unit 3 ECCS train inoperable for a period longer than the technical specification action statement allows over the last 5 years.
ENERGY INDUSTRY IDENTIFICATION SYSTEM (EIIS) CODES None 4
4 Millstone Power Station - Unit 3 423 2022 003 00