05000395/LER-2022-002-01, Condition Prohibited by Technical Specifications: Inoperable B Emergency Diesel Generator
| ML22342B247 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 12/08/2022 |
| From: | Lippard G Dominion Energy South Carolina |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| 22-370 LER 2022-002-01 | |
| Download: ML22342B247 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3952022002R01 - NRC Website | |
text
V.C. Summer Nuclear Station Bradham Blvd & Hwy 215, Jenkinsville, SC 29065 Mailing Address:
P.O. Box 88, Jenkinsville, SC 29065 Dominion Energy.com December 8, 2022 Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555 DOMINION ENERGY SOUTH CAROLINA (DESC) i; Dominion
- iiiiii" Energy Serial No.22-370 VCS-LIC/JB RO Docket No. 50-395 License No. NPF-12 VIRGIL C. SUMMER NUCLEAR STATION (VCSNS) UNIT 1 UPDATED LICENSEE EVENT REPORT 2022-002-01 CONDITION PROHIBITED BY TECHNICAL SPECIFICATION 3.8.1.1 Dominion Energy South Carolina hereby submits Licensee Event Report (LER) 2022-002-01, forVCSNS. LER 2022-002-00 (ML22101A284) described a potential condition prohibited by VCSNS Technical Specification 3.8.1.1 related to its 'B' Emergency Diesel Generator and was submitted in accordance with 10 CFR 50.73(a)(2)(i)(B). The enclosed LER 2022-002-01 provides updated information for this event.
Should you have any questions, please call Mr. Justin Bouknight at (803) 941-9828.
Sincerely,
~L~
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 February 9, 2022, VCSNS identified kilowatt oscillations in the load of the 'B' Emergency Diesel Generator (EDG) during the performance of surveillance test procedure STP-125.002B. The 'B' EDG satisfied STP-125.002B acceptance criteria; however, since the kilowatt oscillations were not immediately explainable and based on engineering qualitative review for prompt operability, the 'B' EDG was declared inoperable. The unexpected condition of the 'B' EDG resulted in inoperability of the 'B' EDG, contrary to VCSNS Technical Specifications (TS) Limiting Condition of Operation (LCO) 3.8.1.1.b, from January 16 to February 9, 2022.
1.0 DESCRIPTION OF THE EVENT On February 9, 2022, VCSNS identified kilowatt oscillations in the load of the 'B' Emergency Diesel Generator (EOG) during the performance of surveillance test procedure STP-125.002B. The 'B' EOG satisfied STP-125.002B acceptance criteria. Since the kilowatt oscillations were not immediately explainable, the 'B' EOG was declared inoperable. This prompt operability review was based on qualitative engineering analysis.
During troubleshooting on February 9, an intermittently connecting pin was discovered in a governor Amphenol connector, which was causing the kilowatt oscillations. The Amphenol connector was replaced to correct the connection issue.
VCSNS TS 3.8.1.1.b requires two separate and independent EDGs and appurtenances during Mode 1 through 4 operations. The broken Amphenol connector pin on the 'B' EOG governor wire resulted in inoperability of the 'B' EOG, contrary to VCSNS TS 3.8.1.1.b, from January 16 to February 9, 2022.
2.0 SIGNIFICANT SAFETY CONSEQUENCES AND IMPLICATIONS
The 'B' EOG is one of two safety-related (SR) power supplies on-site and provides the emergency on-site power supply to Engineered Safety Feature (ESF) loads on bus 1 DB, in the event of off-site power interruption. Bus 1 DB powers one of the two sets of redundant ESF equipment needed in the postulated design basis accident (OBA) scenario. In the event neither EOG is available to power its respective loads, a non-safety related alternate AC power (AAC) source can provide power. The AAC is designed to provide back-up power to either ESF bus whenever one of the EDGs is out of service, particularly in Modes 1 through 4 operation. The design of the AAC is capable of providing the required safety and non-safety related loads in the event of a total loss of offsite power and if both EDGs fail to start and load. Although the AAC is not designed for OBA loads, it is capable of supplying sufficient power to mitigate the effects of an accident. The AAC is not credited in the safety analysis.
3.0 CAUSE OF THE EVENT
Troubleshooting was performed following the February 9 performance of STP-125.002B and identified an intermittently connecting pin on the governor Amphenol connection. Replacement of the affected Amphenol connector corrected the 'B' EDG kilowatt oscillation condition.
4.0 IMMEDIATE CORRECTIVE ACTIONS
The 'B' EDG was declared inoperable following qualitative engineering review of the kilowatt oscillations during the February 9, 2022, STP-125.002B run.
Troubleshooting was performed and the governor Amphenol connector was replaced.
5.0 ADDITIONAL CORRECTIVE ACTIONS
None 6.0 ACTIONS TO PREVENT RECURRENCE Corrective actions have been generated to implement design changes for both EDGs that provides strain relief on the governor control signal wires. Routine maintenance and surveillance of the EDGs will continue to ensure operability of both EDGs and identify adverse conditions requiring correction.
7.0 SIMILAR EVENTS
None 8.0 MANUFACTURER Colt Industries, Fairbanks-Morse Engine Division Page 3
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