ML22045A024

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

ML22045A024
Person / Time
Site:	Oconee
Issue date:	02/17/2022
From:	Shawn Williams Plant Licensing Branch II
To:	Snider S Duke Energy Carolinas
Williams S
References
Bulletin 2012 01
Download: ML22045A024 (5)

Text

February 17, 2022 Mr. Steven M. Snider Site Vice President Duke Energy Carolinas, LLC 7800 Rochester Highway Seneca, SC 29672-0752

SUBJECT:

OCONEE NUCLEAR STATION - CLOSEOUT OF BULLETIN 2012-01, DESIGN VULNERABILITY IN ELECTRIC POWER SYSTEM

Dear Mr. Snider:

The purpose of this letter is to inform you that the U.S. Nuclear Regulatory Commission (NRC) staff has verified that Duke Energy Carolinas, 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 Oconee Nuclear Station, Units 1, 2, and 3 (Oconee). The NRC staff has completed its review of this information and has closed out BL 2012-01 for Oconee.

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:

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 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).

By letter dated October 23, 2012 (ADAMS Accession No. ML12300A426), the licensee provided its response to BL 2012-01 for Oconee. By letter dated February 3, 2014 (ADAMS Accession No. ML14035A453), the licensee provided supplemental information for this facility in response 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

S. Snider 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), 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 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, the NRC staff performed inspections at Oconee using TI 2515/194 dated October 31, 2017. In September 2021, the NRC staff performed inspections at Oconee using TI 2515/194 Revision 2. These inspections at Oconee 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.

Oconee Nuclear Station - Temporary Instruction 2515/194 Inspection Report 05000269/2019013 and 05000270/2019013 and 05000287/2019013, dated November 14, 2019 (ADAMS Accession No. ML19318G943)

Oconee Nuclear Station - Integrated Inspection Report 05000269/2021003 and 05000270/2021003 and 05000287/2021003, dated October 28, 2021 (ADAMS Accession No. ML21301A125)

The NRC staff reviewed the information submitted by the licensee and the results of the TI 2515/194 inspections for Oconee. No findings nor exceptions were identified. Based on the above, 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 Oconee.

S. Snider If you have any questions, please contact me at 301-415-1009 or Shawn.Williams@nrc.gov .

Sincerely, Digitally signed by Shawn A. Shawn A. Williams Date: 2022.02.17 Williams 06:12:53 -05'00' Shawn A. Williams, Project Manager Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-269, 50-270, 50-287 cc: Listserv

ML22045A024 OFFICE NRR/DORL/LPL2-1/PM NRR/DORL/LPL2-1/LA NRR/DEX/EEEB/BC NAME SWilliams KGoldstein WMorton DATE 02/16/2022 02/16/2022 02/09/2022 OFFICE NRR/DRA/APOB/BC NRR/DRO/IOEB/BC NRR/DORL/LPL2-1/BC NAME AZoulis LRegner MMarkley DATE 02/15/2022 02/16/2022 02/16/2022 OFFICE NRR/DORL/LPL2-1/PM NAME SWilliams DATE 02/17/2022