ML21201A105

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

ML21201A105
Person / Time
Site:	Callaway
Issue date:	07/27/2021
From:	Mahesh Chawla Plant Licensing Branch IV
To:	Diya F Union Electric Co
Chawla M
References
BL-12-001, EPID L-2017-CRS-0063
Download: ML21201A105 (3)

Text

July 27, 2021 Mr. Fadi Diya Senior Vice President and Chief Nuclear Officer Ameren Missouri Callaway Energy Center 8315 County Road 459 Steedman, MO 65077

SUBJECT:

CALLAWAY PLANT, UNIT 1 - CLOSEOUT OF BULLETIN 2012-01, DESIGN VULNERABILITY IN ELECTRIC POWER SYSTEM (EPID L-2017-CRS-0063)

Dear Mr. Diya,

The purpose of this letter is to inform you that the U.S. Nuclear Regulatory Commission (NRC) staff has verified that Union Electric Company, dba Ameren Missouri (the licensee) has provided the necessary information requested in 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 Callaway Plant, Unit No. 1 (Callaway).

The NRC staff has completed its review of this information and has closed out BL 2012-01 for Callaway.

The NRC issued BL 2012-01 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 24, 2012 (ADAMS Accession No. ML12298A514), the licensee provided its response to BL 2012-01 for Callaway. By letter dated January 30, 2014 (ADAMS Accession No. ML14030A423), the license 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

F. Diya 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 the potential design vulnerabilities to the open phase condition.

To evaluate the adequacy of the open phase isolation systems designs, the NRC staff inspected four nuclear power plants with four distinct open phase isolation system designs using the NRCs 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). 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 Accession Nos. ML18268A342 and ML18309A226, respectively.

In September 2018, the NRC staff performed an inspection using TI 2515/194 at Callaway to verify the licensees implementation of Revision 1 of the voluntary industry initiative at this facility. To address the open phase condition design vulnerability issue at Callaway, the licensee implemented open phase isolation system plant modifications, which provide detection, alarm, and automatic protective features. The NRC inspection report, as identified below, documents the results of this TI 2515/194 inspection. No findings or violations of more than minor significance were identified. The licensee completed the implementation of its open phase isolation system in April 2020.

NRC Inspection Report 05000483/2018011, Callaway Plant, Unit 1 - NRC Inspection of Temporary Instruction 2515/194, Inspection Report 05000483/2018011, dated October 16, 2018 (ADAMS Accession No. ML18289A652).

The NRC staff reviewed the information submitted by the licensee and the results of the TI 2515/194 inspection for Callaway. Based on this review, the NRC staff concludes that the licensee provided the necessary information requested in BL 2012-01. Therefore, the NRC staff has closed BL 2012-01 for Callaway.

If you have any questions, please contact me at 301-415-8371 or by e-mail to Mahesh.Chawla@nrc.gov.

Sincerely,

/RA/

Mahesh L. Chawla, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-483 cc: Listserv

ML21201A105 *by email OFFICE NRR/DORL/LPL4/PM NRR/DORL/LPL4/LA NRR/DEX/EEEB/BC (A)

NAME MChawla PBlechman SRay DATE 07/23/2021 07/20/2021 07/19/2021 OFFICE NRR/DRO/IOEB/BC NRR/DORL/LPL4/BC NRR/DORL/LPL4/PM NAME LRegner JDixon-Herrity MChawla DATE 07/26/2021 07/27/2021 07/27/2021