05000395/LER-2024-002-01, (Vcsns), Unit 1, Loss of Control Room Emergency Filtration System
| ML25028A244 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 01/28/2025 |
| From: | Jenkins B Dominion Energy, Dominion Energy South Carolina |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| 24-310B LER 2024-002-01 | |
| Download: ML25028A244 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| 3952024002R01 - NRC Website | |
text
Dominion Energy South Carolina, Inc Virgil C. Summer Nuclear Station Bradham Boulevard & Highway 215, Jenkinsville, SC 29065 Mailing Address:
P.O. Box 88, Jenkinsville, SC 29065 DominionEnergy.com January 28, 2025 Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555 Dominion Energy!D Serial No.: 24-31 OB VCS-LIC/JB RO Docket No. 50-395 License No. NPF-12 DOMINION ENERGY SOUTH CAROLINA, INC. (DESC)
VIRGIL C. SUMMER NUCLEAR STATION (VCSNS) UNIT 1 LICENSEE EVENT REPORT 2024-002-01 LOSS OF CONTROL ROOM EMERGENCY FILTRATION SYSTEM Dominion Energy South Carolina, Inc. hereby submits Licensee Event Report (LER) 2024-002-01, for VCSNS. This report provides updated information regarding the inoperability of Control Room Ventilation on August 20, 2024.
Should you have any questions, please call Mr. Justin Bouknight at (803) 941-9828.
Sincerely,
'd>~
Beth Jenkins Site Vice President V.C. Summer Nuclear Station Enclosure Commitments contained in this letter: None cc:
G. J. Lindamood - Santee Cooper L. Dudes - NRC Region II G. Miller-NRC Project Mgr.
NRC Resident Inspector J. N. Bassett-INPO Marsh USA, Inc.
Abstract
On August 20, 2024, at 2001 EDT, V.C. Summer Nuclear Station (VCSNS) identified that both trains of Control Room Emergency Filtration System (CREFS) were inoperable. The CREFS consists of the 'A' and
- B' trains of the Control Room Ventilation System (CRVS). The ' B' Train of CREFS had been removed from service earlier in the day for planned maintenance and testing activities. At 1015 EDT, 'A' CRVS Control Damper failed to close under its own power, when required to do so to support retest of the
- B' CRVS. As a result, both trains of CREFS were determined to be unable to perform the emergency filtration function during a postulated accident for a period longer than allowed by Technical Specifications.
At 2107 EDT, the 'A' CREFS was restored to OPERABLE status and available to perform its safety function. Reactor power remained at 100% throughout the event.
This event is being reported in accordance with 10 CFR 50. 73(a)(2)(i)(B) and 10 CFR 50. 73(a)(2)(v).
1.0 DESCRIPTION OF THE EVENT
- 2. DOCKET NUMBER
- 3. LER NUMBER I
395 D
NUMBER NO.
I YEAR SEQUENTIAL REV
~-I 002 1-0 On August 20, 2024, V.C. Summer Nuclear Station (VCSNS) removed 'B' train of its Control Room Emergency Filtration System (CREFS) from service for planned maintenance activities. Following maintenance, the 'B' CREFS was to be retested per STP-454.002, "Control Room Emergency Air Cleanup System Performance Test."
To support performance of STP-454.002, the Control Room Air Handling Unit A Control Damper (XDP0022A) had to be closed. At 1015 EDT, XDP0022A failed to close upon demand. With the Unit A Control Damper unable to close on demand, the 'A' CREFS was no longer OPERABLE, while the 'B' CREFS was removed from service for maintenance. As a result, the control room did not have emergency filtration capability, which is a safety function needed to mitigate the consequences of an accident.
At 2107 EDT, the crew placed 'A' train of CREFS in emergency mode and failed XDP0022A closed, which made the train OPERABLE.
Reactor power remained at 100% throughout the event. This event is being reported in accordance with 10 CFR 50. 73(a)
(2)(i)(B) and 10 CFR 50. 73(a)(2)(v).
2.0 SIGNIFICANT SAFETY CONSEQUENCES AND IMPLICATIONS
With both trains of CRVS inoperable, the CREFS would have been unable to perform its safety function needed to mitigate the consequences of a postulated accident.
3.0 CAUSE OF THE EVENT
The following causes were identified by the LEE:
(1) Knowledge gap by the shift manager in understanding what made A train of CREFS inoperable and that both trains being inoperable led to entry into TS 3.0.3 (2) Shift management failed to engage additional resources when questioned on operability of the CREFS with the 'A' CRVS Damper (XDP0022A) stuck open.
(3) Inaccurate risk perception when performing STP-454.002, "Control Room Emergency Air Cleanup System Performance Test."
4.0 INITIAL ACTIONS At 2107 EDT, the crew placed A train of CREFS in emergency mode and failed XDP0022A closed, which made the train OPERABLE.
On August 23, 2024 at 0849 EDT, the 'B' CRVS returned to OPERABLE status following completion of its planned maintenance activities.
5.0 INTERIM & COMPENSATORY ACTIONS A. Coached relief SM on knowledge gap of the effect of stuck damper on CREFS operability B. Distributed information from the event to the site via department clock reset.
C. Reinforced use of mass notification system to alert station management to new conditions.
6.0 CORRECTIVE ACTIONS
(1) Screen STP-454.002, "Control Room Emergency Air Cleanup System Performance Test," for operational risk using WM-AA-301 (per management discretion due to possible TS 3.0.3 entry).
(2) Identify other surveillances associated with CREFS that are not screened appropriately for operational risk (per management discretion due to possible TS 3.0.3 entry).
(3) Perform a performance gap analysis to identify and correct the extent of condition (knowledge gaps/proficiency pertaining to CREFS operability/reportability and timeliness of assessment).
(4) Re-institute the emergent items checklist from OAP-100.2, "Communication."
(5) Submit procedure feedback to WM-AA-301 to evaluate operational risk of surveillances that require cross train operations.
(6) Review control room ventilation procedures for similar vulnerabilities where loss of safety function may occur.
7.0 SIMILAR EVENTS
No similar events were identified within the last three years.
8.0 COMPONENT Bahnsen Heavy Duty Damper Page 3
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