ML23101A043

April 6, 2023, Summary of Meeting with Vistra Operations Company LLC to Discuss Proposed Alternative Regarding Inservice Testing of Various Thermal Relief Valves for Comanche Peak Nuclear Power Plant, Unit Nos. 1 and 2

ML23101A043
Person / Time
Site:	Comanche Peak
Issue date:	04/12/2023
From:	Dennis Galvin Plant Licensing Branch IV
To:
Galvin D
References
EPID L-2023-LRM-0023
Download: ML23101A043 (5)

Text

April 12, 2023 LICENSEE: Vistra Operations Company LLC FACILITY: Comanche Peak Nuclear Power Plant, Units Nos. 1 and 2

SUMMARY

OF APRIL 6, 2023, PRESUBMITTAL MEETING WITH VISTRA OPERATIONS COMPANY LLC TO DISCUSS PROPOSED ALTERNATIVE REGARDING INSERVICE TESTING OF VARIOUS THERMAL RELIEF VALVES FOR COMANCHE PEAK NUCLEAR POWER PLANT, UNIT NOS. 1 AND 2 (EPID L-2023-LRM-0023)

On April 6, 2023, an Observation public meeting was held between the U.S. Nuclear Regulatory Commission (NRC) staff and representatives of Vistra Operations Company LLC (the licensee) via webinar. The purpose of the meeting was to discuss a proposed alternative request related to certain inservice testing (IST) requirements specified in the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code) as incorporated by reference in Title 10 of the Code of Federal Regulations Section 50.55a, Codes and standards, at the Comanche Peak Nuclear Power Plant, Unit Nos. 1 and 2 (Comanche Peak Units 1 and 2). The meeting notice and agenda, dated April 4, 2023, are available in the Agencywide Documents Access and Management System (ADAMS) at Accession No. ML23096A174. A list of attendees is enclosed.

The licensee presented informational slides at the meeting, which can be found in ADAMS at Accession No. ML23094A272. During the meeting, the licensee discussed its recent identification of the inadvertent omission of 10 thermal relief valves in the station service water (SSW) system and lube oil cooler system from the IST Program at Comanche Peak. In light of their inadvertent omission from the IST Program, the 10 thermal relief valves are required to be tested in accordance with the IST Program at the next available opportunity, which would be the refueling outages at Comanche Peak Unit 2 in the spring of 2023 and at Comanche Peak Unit 1 in the fall of 2023. Because of the unavailability of replacement parts for the thermal relief valves if needed when tested, the licensee plans to submit an alternative request in accordance with 10 CFR 50.55a(z), Alternatives to codes and standards requirements, to postpone the IST tests for these thermal relief valves until later refueling outages for both Comanche Peak units after replacement parts have been obtained.

During the meeting, the licensee stated that a misunderstanding of the ASME OM Code requirements for skid-mounted valves had caused the thermal relief valves to be inadvertently omitted from the IST Program at Comanche Peak many years ago. The licensee now recognizes that its original justification for excluding these valves from the IST Program was not adequate. The licensee is working to obtain replacement parts for these valves as soon as possible to support their testing.

The licensee summarized its planned alternative for the IST tests of the subject thermal relief valves required by the ASME OM Code as follows:

Overpressure protection is not needed during system operation to support a system safety function. The SSW is an open system that is only isolated to remove the system from service.

As an alternative that provides an acceptable level of quality and safety until replacement valves are installed, the licensee will ensure heat exchangers/coolers are vented to prevent overpressure when the system is isolated (shift manager clearance -

caution tag).

The licensee will request approval to extend the test/replacement interval until the first cold shutdown outage after acceptable replacement relief valves are available.

The NRC staff discussed several observations on the licensees presentation, including information needed or should be considered for inclusion in the proposed alternative as follows:

1. Since Comanche Peak has been out of compliance with the ASME OM Code because of the inadvertent omission of valves from the IST Program, the licensee needs to submit a request for an alternative to the ASME OM Code to justify the proposed postponement of the IST tests for the subject valves beyond the next refueling outage for each Comanche Peak unit.

2. The licensee should describe the operating status (open or closed) of both the SSW and lube oil cooler system to indicate when the applicable thermal relief valves might have an open safety function to relieve system overpressure.

3. The licensee should describe its controls to provide reasonable assurance that the subject thermal relief valves will not be called upon to open during the time period of the requested alternative, except under specific circumstances.

4. The licensee needs to specify the requested duration of the proposed alternative for each Comanche Peak unit, such as until the refueling outage in the spring or fall of a specific year for each reactor unit.

5. The licensee needs to justify its request in accordance with either 10 CFR 50.55a(z)(1) as providing an acceptable level of quality and safety by implementing the proposed alternative, or 10 CFR 50.55a(z)(2) that the required OM Code testing represents a hardship without a compensating increase in quality and safety considering the proposed alternative. For example, the licensee might discuss the unavailability of replacement parts if needed following testing of the subject thermal relief valves that might cause safety systems at Comanche Peak to be out of service for extended periods of time.

6. The licensee needs to submit the alternative request as soon as possible for the NRC staff to complete its evaluation prior to the Comanche Peak Unit 2 refueling outage in the spring of 2023. The NRC staff will evaluate the alternative request using the verbal authorization process if adequately justified by the licensee.

7. The licensee needs to identify the applicable thermal relief valves in the alternative request. The licensee should include the information normally provided in the IST Program plan for each valve within the scope of the alternative request.

8. The NRC staff is not able to evaluate alternative requests related to previously missed IST tests for ASME OM Code components. In other words, alternative requests can only be forward looking. Therefore, the NRC region staff will evaluate the omission of the thermal relief valves from the IST Program at Comanche Peak, and the missed IST tests for those valves, under the reactor oversight program.

9. The NRC staff recommended that the licensee reconsider the proposed commitment to repair valves at the next cold shutdown outage if parts are available, at least for the SSW relief valves. A commitment to repair or replace the affected components at the next opportunity will normally result in a safety improvement, but in this case may lead to a reduction in safety. This is because (1) the overpressure function of the relief valves in question is not needed except when the heat exchangers are isolated, (2) while unlikely, this commitment could result in numerous evolutions where one train of ultimate heat sink is taken out of service while fuel is in the core, potentially for extended periods, and (3) the licensee stated that their normal refueling practice is to conduct a full core offload into the spent fuel pool, which can be cooled from the other unit.

During the meeting, the licensee stated that the planned alternative request for Comanche Peak will be submitted on or about April 13, 2023. The NRC staff will review the alternative request upon receipt, including the need for any requests for additional information.

No members of the public called into the meeting. No public meeting feedback forms were received. No regulatory decisions were made at the meeting.

Please direct any inquiries to me at 301-415-6256 or by e-mail to Dennis.Galvin@nrc.gov.

/RA/

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

Enclosure:

List of Attendees cc: Listserv

LIST OF ATTENDEES APRIL 6, 2023, PRESUBMITTAL WEBINAR REGARDING PROPOSED ALTERNATIVE FOR INSERVICE TESTING OF VARIOUS THERMAL RELIEF VALVES VISTRA OPERATIONS COMPANY LLC COMANCHE PEAK NUCLEAR POWER PLANT, UNITS NO. 1 AND 2 U.S. Nuclear Regulatory Commission Stewart Bailey Gurjendra Bedi Nachiketh Chandran Jennifer Dixon-Herrity James Drake John Ellegood Nicholas Hansing Shiattin Makor David Nani David Proulx Thomas Scarbrough Vistra Operations Company LLC James Barnette Thomas Crippes Jack Hicks Evan Jones Neil Jones Andrea Lemons Ben Martin Barney Pool Josh Porter Brian Turnipseed Enclosure

ML23101A045 (Package)

ML23096A174 (Meeting Notice)

ML23094A272 (Public Meeting Slides)

ML23101A043 (Meeting Summary)

OFFICE NRR/DORL/LPL4/PM NRR/DORL/LPL4/LA NRR/DEX/EMIB/BC NAME DGalvin PBlechman SBailey DATE 4/11/2023 4/11/2023 4/11/2023 OFFICE NRR/DORL/LPL4/BC NRR/DORL/LPL4/PM NAME JDixon-Herrity DGalvin DATE 4/12/2023 4/12/2023