ML23025A353

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

ML23025A353
Person / Time
Site:	Comanche Peak
Issue date:	01/26/2023
From:	Dennis Galvin NRC/NRR/DORL/LPL4
To:	Peters K Vistra Operations Company
References
EPID L-2017-CRS-0063
Download: ML23025A353 (1)

Text

January 26, 2023 Mr. Ken J. Peters Senior Vice President and Chief Nuclear Officer Attention: Regulatory Affairs Vistra Operations Company LLC Comanche Peak Nuclear Power Plant 6322 N FM 56 P.O. Box 1002 Glen Rose, TX 76043

SUBJECT:

COMANCHE PEAK NUCLEAR POWER PLANT, UNIT NOS. 1 AND 2 - CLOSEOUT OF BULLETIN 2012-01, DESIGN VULNERABILITY IN ELECTRIC POWER SYSTEM (EPID L-2017-CRS-0063)

Dear Mr. Peters:

The purpose of this letter is to inform you that the U.S. Nuclear Regulatory Commission (NRC) staff has verified that Vistra Operations Company LLC (the licensee) has provided the necessary information requested in 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 Comanche Peak Nuclear Power Plant, Unit Nos. 1 and 2 (Comanche Peak). The NRC staff has completed its review of this information and has closed out BL 2012-01 for Comanche Peak.

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 permanently ceased operation 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 provide the following information:

A description of 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 offsite power circuits or another power source; and A description of 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).

By letter dated October 25, 2012 (ML12312A073), the licensee provided its response to BL 2012-01 for Comanche Peak. By letter dated January 30, 2014 (ML14043A106), the

K. Peters licensee provided supplemental information for this facility in response to an NRC staff request for additional information issued on December 20, 2013 (ML13351A314).

By letters dated October 9, 2013, and March 16, 2015 (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 (ML17137A416), which provided temporary inspection instructions for the purpose of verifying that licensees appropriately implemented the NEI voluntary industry initiative dated March 16, 2015. 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 ML18268A342 and ML18309A226, respectively.

In an e-mail dated June 6, 2019 (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 (ML19172A086). On August 18, 2020, the NRC staff issued Revision 2 of TI 2515/194 (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 September 2018, the NRC staff performed inspections at Comanche Peak using TI 2515/194 dated October 31, 2017. In December 2021, and November 2022, the NRC staff performed inspections at Comanche Peak using TI 2515/194 Revision 2. These inspections at Comanche Peak 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.

Comanche Peak Nuclear Power Plant - NRC Inspection of Temporary Instruction 2515/194 Inspection Report 05000445/2018012 and 05000446/2018012, dated December 12, 2018 (ML18285A725)

Comanche Peak Nuclear Power Plant - TI-194 Report 05000445/2021012 and 05000446/2021012, dated January 13, 2022 (ML22012A153)

Comanche Peak Nuclear Power Plant -TI-194 Report 05000445/2022010 and 05000446/2022010, dated January 23, 2023 (ML23023A058)

K. Peters The NRC staff reviewed the information submitted by the licensee and the results of the TI 2515/194 inspections for Comanche Peak. Based on this review, the NRC staff concludes that the licensee provided the necessary information requested in BL 2012-01 and has completed the implementation of its open phase isolation system. Therefore, the NRC staff closes BL 2012-01 for Comanche Peak.

If you have any questions, please contact me at 301-415-6256 or Dennis.Galvin@nrc.gov Sincerely,

/RA/

Dennis J. Galvin, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-445 and 50-446 cc: Listserv

ML23025A353 OFFICE NRR/DORL/LPL4/PM NRR/DORL/LPL4/LA* NRR/DEX/EEEB/BC*

NAME DGalvin PBlechman WMorton DATE 1/25/2023 1/25/2023 01/24/2023 OFFICE NRR/DRA/APOB/BC* NRR/DRO/IOEB/BC* NRR/DORL/LPL4/BC*

NAME AZoulis LRegner JDixon-Herrity DATE 1/24/2023 1/25/2023 1/26/2023 OFFICE NRR/DORL/LPL4/PM*

NAME DGalvin DATE 1/26/2023