ML21242A330

Closeout of Bulletin 2012-01, Design Vulnerability in Electric Power System

ML21242A330
Person / Time
Site:	Summer
Issue date:	09/14/2021
From:	Vaughn Thomas Plant Licensing Branch II
To:	Stoddard D Dominion Energy South Carolina
Thomas, Vaughn
References
EPID L-2017-CRS-0063
Download: ML21242A330 (4)

Text

September 14, 2021 Mr. Daniel G. Stoddard Senior Vice President and Chief Nuclear Officer Dominion Energy South Carolina Innsbrook Technical Center 5000 Dominion Blvd., Floor: IN-2SW Glen Allen, VA 23060

SUBJECT:

VIRGIL C. SUMMER NUCLEAR STATION, UNIT 1 - CLOSEOUT OF BULLETIN 2012-01, DESIGN VULNERABILITY IN ELECTRIC POWER SYSTEM (EPID L-2017-CRS-0063)

Dear Mr. Stoddard:

The purpose of this letter is to inform you that the U.S. Nuclear Regulatory Commission (NRC) staff has completed its review of Dominion Energy South Carolina (the licensee) responses to NRCs Bulletin (BL) 2012-01, Design Vulnerability in Electric Power System, dated July 27, 2012 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12074A115), for Virgil C. Summer Nuclear Station, Unit 1 (Summer) and has closed out BL 2012-01 for Virgil C. Summer Nuclear Station, Unit 1.

The NRC issued BL 2012-01 on July 27, 2012, to all holders of operating licenses and combined licenses for nuclear power reactors, except those who have ceased operation permanently and have certified that fuel has been removed from the reactor vessel. The Bulletin requested information about each facilitys electric power system designs that would allow the NRC staff to verify the systems capability to address open phase conditions.

Specifically, the NRC requested licensees to:

describe how the protection scheme for engineered safety features buses (Class 1E for current operating plants or non-Class 1E for passive plants) is designed to detect and automatically respond to a single-phase open circuit condition or high impedance ground fault condition on a credited offsite power circuits or another power source; and describe the operating configuration of engineered safety features buses (Class 1E for current operating plants or non-Class 1E for passive plants) at power (i.e., normal operating condition).

The above information was requested to confirm that licensees comply with 10 CFR 50.55a(h)(2), 10 CFR 50.55a(h)(3), and Appendix A to 10 CFR Part 50, GDC 17, or principal design criteria specified in the updated final safety analysis report.

By letter dated October 24, 2012 (ADAMS Accession No. ML12299A470), the licensee provided its response to BL 2012-01 for Summer. By letter dated February 3, 2014 (ADAMS Accession No. ML14035A455), the licensee provided supplemental information for this facility in response

D. Stoddard to an NRC staff request for additional information issued on December 20, 2013 (ADAMS Accession No. ML13351A314).

By letters dated October 9, 2013, and March 16, 2015 (ADAMS Accession Nos. ML13333A147 and ML15075A454, respectively), the Nuclear Energy Institute (NEI) submitted a voluntary industry initiative to address open phase conditions at nuclear power plants. The NEI letter dated March 16, 2015, stated, in part: The initiative is a formal commitment by the companies that operate nuclear power plants to follow a specific policy or plan of action. The initiative calls for a proactive plan and schedule for addressing potential design vulnerabilities to the open phase condition.

To evaluate the adequacy of the open phase isolation systems designs, the NRC staff issued Temporary Instruction (TI) 2515/194, Inspection of the Licensees Implementation of Industry Initiative Associated with the Open Phase Condition Design Vulnerabilities in Electric Power Systems (NRC Bulletin 2012-01), dated October 31, 2017 (ADAMS Accession No. ML17137A416). The NRC staff piloted the use of TI 2515/194 by inspecting four nuclear power plants with four distinct open phase isolation system designs. A summary of the NRC staffs preliminary observations and issues needing additional clarity were discussed with industry representatives in two public meetings conducted on September 19, 2018, and October 17, 2018. The meeting summaries can be found in ADAMS under Package Accession Nos. ML18268A342 and ML18309A226, respectively.

By letter dated June 6, 2019 (ADAMS Accession No. ML19163A176), NEI submitted Revision 3 of the voluntary industry initiative to include an option for plants to perform a risk evaluation under certain boundary conditions to support manual response to an open phase condition.

NEI also submitted NEI 19-02, Guidance for Assessing Open Phase Condition Implementation Using Risk Insights on June 20, 2019 (ADAMS Accession No. ML19172A086). On August 18, 2020, the NRC staff issued Revision 2 of TI 2515/194 (ADAMS Accession No. ML20230A328),

which provided temporary inspection instructions for the purpose of verifying that licensees appropriately implemented Revision 3 of the NEI voluntary industry initiative. The revision accounted for changes reflected in Revision 3 of the NEI voluntary initiative.

In October 2019 and December 2020, the NRC staff performed inspections at Summer using TI 2515/194 dated October 31, 2017, and TI 2515/194 Revision 2 dated August 18, 2020 (ADAMS Accession No. ML20230A328), respectively. These inspections at Summer were performed to verify the licensees implementation of the voluntary industry initiative at this facility. To address the open phase condition design vulnerability issue at this facility, the licensee implemented open phase isolation system plant modifications, which provide detection and alarm in the control room, and necessary plant procedures that allow operators to diagnose and take manual action to mitigate an open phase condition. The NRC inspection reports listed below document the results of the TI 2515/194 inspections.

Virgil C. Summer Nuclear Station - Temporary Instruction 2515/194 Inspection Report 05000395/2019013, dated December 4, 2019 (ADAMS Accession No. ML19338C072)

Virgil C. Summer Nuclear Station - Integrated Inspection Report 05000395/2020004, dated February 9, 2021 (ADAMS Accession No. ML21040A504)

The NRC staff reviewed the information submitted by the licensee and the results of the TI 2515/194 inspections for Summer. No findings or exceptions were identified. Based on the

D. Stoddard above, the NRC staff concludes that the licensee provided the necessary information requested in BL 2012-01 and has completed implementation of its open phase isolation system.

Therefore, the NRC staff has closed BL 2012-01 for Summer.

If you have any questions, please contact me at 301-415-5897 or by e-mail to Vaughn.Thomas@nrc.gov Sincerely,

/RA/

Vaughn Thomas, Project Manager Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-395 cc: Listserv

ML21242A330 *by email OFFICE NRR/DORL/LPL2-1/PM NRR/DORL/LPL2-1/LA* NRR/DEX/EEEB/BC(A)*

NAME VThomas KGoldstein SRay DATE 08/30/2021 09/03/2021 08/04/2021 OFFICE NRR/DRA/APOB/BC* NRR/DRO/IOEB/BC* NRR/DORL/LPL2-1/BC*

NAME AZoulis LRegner MMarkley DATE 09/07/2021 09/08/2021 09/13/2021 OFFICE NRR/DORL/LPL2-1/PM NAME VThomas DATE 09/14/2021