ML25352A146
| ML25352A146 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 12/17/2025 |
| From: | Kearney W Dominion Energy South Carolina |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| 25-297 | |
| Download: ML25352A146 (0) | |
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 ed DomInIon Energy December 17, 2025 Attn: Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555-0001 SN 25-297 VCS LIC/HK/Rev0 Docket No. 50-395 License No. NPF-12 DOMINION ENERGY SOUTH CAROLINA (DESC)
VIRGIL C. SUMMER NUCLEAR STATION (VCSNS) UNIT 1 TECHNICAL SPECIFICATION BASES CHANGES UPDATED THROUGH DECEMBER 2025 In accordance with Virgil C. Summer Nuclear Station (VCSNS) Unit 1 Technical Specifications (TS) 6.8.4.i.4, Dominion Energy South Carolina (DESC), acting for itself and as agent for South Carolina Public Service Authority, submits annual changes to the TS Bases.
This update includes changes to the TS Bases since the previous submittal in February 2025.
The enclosed changes revised by LBDCF:-23-VCSl-006 were implemented under the provision of 10 CFR 50.59. Changes are annotated by vertical revision bars and the LBDCR number at the bottom of the affected TS Bases pages.
Should you have any questions, please call Michael Moore at (803) 345-4752.
Will Kearney Director, Nuclear Plant Support V.C. Summer Nuclear Station Commitments contained in this letter: None : Summary of TS Bases Changes Through December 2025 : Technical Specification Bases Changes Updated Through December 2025 CC G. J. Lindamood - Santee Cooper J. Lara - NRC Region II G. Miller - NRC Project Manager NRC Resident Inspector
Serial No.25-297 : Page 1 of 1 Summary of TS Bases Changes Through December 2025 LBDCR-23-VCSI -006 Description of Change:
The Technical Specification (TS) Bases for Limiting Condition of Operation (LCO) 3.6.2.3 and its associated Surveillance Requirement (SR) 4.6.2.3 was revised to clarify the term group as used in both the LCO and SR. The change also more consistently uses RBCU to reinforce its association with the term unit.
Reason and Basis for Change:
CR-19-04103 identified that there is little documentation in the stations current licensing basis defining the term group in relation to LCO 3.6.2.3. To address this, License Basis Document Change Request (LBDCFq) 23-VCSl-006, approved on August 7, 2024, was developed to clarify the interpretation of the term group as it applies to the Reactor Building Cooling Units (RBCUs). Additionally, the use of RBCU was made more consistent to associate it with the term unit. CR Assignment CA13218175 documented incorporation of these changes into the TS Bases in accordance with LBDCR 23-VCSl-006.
Serial No.25-297 : Page 1 of 3 Technical Specification Bases Changes Updated Through December 2025 Amendment #
23-VCS 1 -006 23-VCS 1 -006 Pages Affected
[MW]
B 3/4 6-5
CONTAINMENT SYSTEMS BASES 3/4.6.2.2 SPRAY ADDITIVE SYSTEM The OPERABILITY of the spray additive system ensures that sufficient NaOH is added to the reactor building spray in the event of a LOCA. The limits on NaOH volume and concentration ensure a pH value of between 7.5 and 11.0 for the solution recirculated within containment after a LOCA. This pH band minimizes the evolution of iodine and minimizes the effect of chloride and caustic stress corrosion on mechanical systems and components. The contained solution volume limit includes an allowance for solution not usable because of tank discharge line location or other physical characteristics. These assumptions are consistent with the iodine removal efficiency assumed in the accident analyses.
3/4.6.2.3 REACTOR BUILDING COOLING SYSTEM The OPERABILITY of the reactor building cooling system ensures that 1) the reactor building air temperature will be maintained within limits during normal operation, and 2) adequate heat removal capacity is available when operated in conjunction with the reactor building spray systems during post-LOCA conditions.
The reactor building cooling system and the reactor building spray system provide post accident cooling of the reactor building atmosphere. These two independent systems incorporate different principles of heat removal, with RB Spray being more effective in the short term in limiting peak pressure and temperature conditions within the RB. Since RB Spray operation maximizes margin to the RB design limits for maximum pressure and temperature, the allowable out of service time requirements for the reactor building cooling system have been appropriately adjusted. However, the allowable out of service time requirements for the reactor building spray system have been maintained consistent with that assigned other inoperable ESF equipment since the reactor building spray system also provides a mechanism for removing iodine from the reactor building atmosphere.
The reactor building cooling system is composed of four dual-speed fan and coil Reactor Building Cooling Units (RBCUs) arranged in two Groups, with a pair of RBCUs constituting each Group associated with a train:
Train A RBCU XAAOOOI A:
XFN00064A (Fan) + XCE0008A (Coil)
RBCU XAAOO02A:
XFN00065A (Fan) + XCE0009A (Coil)
Train B RBCU XAAOOOI B:
XFN00064B (Fan) + XCE0008B (Coil)
RBCU XAAOO02B:
XFN00065B (Fan) + XCE0009B (Coil)
The LCO requirement for having two operable independent Groups satisfies single failure criteria because at least one RBCU will remain available in the event of a failure either of a train or of one RBCU in either Group. Accordingly, the Surveillance Requirement for a Group is met if one RBCU in a Group can be shown to start and operate at slow speed in each train.
SUMMER - UNIT 1 B 3/4 6-4 Amendment No. 61, 67, Corrected by letter dated 10/4/93, BRN-05-002, BRN-08-Oa4 23-VCS 1 -006
CONTAINMENT SYSTEMS BASES Under accident conditions, the low-speed motor in each RBCU fan is powered by a Class IE emergency bus, and its associated coil is cooled by a Service Water system train. The accident analysis credits only one RBCU in only one Group operating at slow speed Valves XVB-3107A(B)-SW and XVB-3106A(B)-SW have been designed and interlocked to other equipment controls to mitigate two scenarios in which a pipe water hammer could occur. The first water hammer scenario was postulated to occur when the RBCUs are operating in their normal lineup where they are being cooled by the non-safety Industrial Cooling Water System and the Service Water booster pumps (SWBP) are started during normal swap over to the SW system for or after a Loss Of Offsite Power (LOOP). The second water hammer scenario is postulated to occur when the SW system is aligned to provide cooling for the RBCUs and a LOOP occurs.
To minimize the affects of the first water hammer scenario vacuum relief valves XW-13143A(B)-SW downstream of valve XVB-3107A(B)-SW will replace, with air, any vacuum void downstream of closed valves XVB-3107A(B)-SW that may be formed due to gravity drain down of water to the SW pond. Upon the start of the SWBPs and opening of valves XVB-3107A(B)-SW, the air in the piping will act as a cushion to minimize any water hammer affects that could occur downstream of XVB-3107A(B)-SW. The opening logic of valves XVB-3107A(B)-SW has a delayed opening after valve 3106A(B)-SW begins to open. The delay allows fluid flow momentum to build to assure that additional void formation in the RBCU piping inside containment will not occur during swap over to the SW system.
To minimize the effects of the second water hammer scenario XVB-3107A(B)-SW, fast closing air operated butterfly valves, close in seven seconds upon de-energizing of the SWBPs. During times that the RBCUs are aligned with the SW system, if a LOOP were to occur, the fast valve closure will trap water in the high points above the valve and prevent void formation due to gravity drain down of the water to the SW pond. Interface logic is provided to equipment controls that tie the start of the respective SWBP to the closed position of the respective valve XVB-3107A(B)-SW.
The controls prevent a SWBP start if the respective valve XVB-3107A(B)-SW failed to fully close allowing drain down of the water to the SW Pond.
The accident analysis requires the service water booster pump to be passing 2,000 gpm to each selected RBCU within 86.5 seconds. This time encompasses the driving of all necessary service water valves to the correct positions, i.e., fully opened or fully closed. Reference Technical Specification Bases B 3/4.3.1 and B 3/4.3.2 for additional details.
3/4.6.3 PARTICULATE IODINE CLEANUP SYSTEM The OPERABILITY of the containment filter trains ensures that sufficient iodine removal capability will be available in the event of a LOCA. The reduction in containment iodine inventory reduces the resulting site boundary radiation doses associated with containment leakage. The operation of this system and resultant iodine removal capacity are consistent with the assumptions used in the LOCA analyses.
SUMMER - UNIT 1 B 3/4 6-5 Amendment No. 449, BRN 08 001, BRN 10 001 2+8, 23-VCSl-006