ML23110A712
| ML23110A712 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 04/20/2023 |
| From: | Dennis Galvin NRC/NRR/DORL/LPL4 |
| To: | Hicks J TEX Operations Company |
| References | |
| L-2023-LLR-0019 | |
| Download: ML23110A712 (8) | |
Text
From: Dennis Galvin Sent: Thursday, April 20, 2023 3:31 PM To: Jack Hicks (Jack.Hicks@luminant.com)
Cc: Barnette, James; Jennifer Dixon-Herrity; Stewart Bailey; Thomas Scarbrough
Subject:
Comanche Peak - Verbal Authorization of Proposed Alternative RV-1 (L-2023-LLR-0019)
Attachments: L-2023-LLR-0019 Comanche Peak RV-1 Regarding Thermal Relief Valves Verbal Authorization 2023-04-20.pdf
Dear Mr. Hicks,
Please find the attached the written documentation of the verbal authorization of Comanche Peak Proposed Alternative RV-1, submitted April 13, 2023 (ML23108A246).
If you have any questions, please contact me at (301) 415-6256 or Dennis.Galvin@nrc.gov.
Respectfully, Dennis Galvin Project Manager U.S Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Division of Operating Reactor Licensing Licensing Project Branch 4 301-415-6256 Docket Nos. 50-445 and 50-446
Hearing Identifier: NRR_DRMA Email Number: 2045 Mail Envelope Properties (SA1PR09MB811123ABE04D5A93AFD11704FB639)
Subject:
Comanche Peak - Verbal Authorization of Proposed Alternative RV-1 (L-2023-LLR-0019)
Sent Date: 4/20/2023 3:31:27 PM Received Date: 4/20/2023 3:31:00 PM From: Dennis Galvin Created By: Dennis.Galvin@nrc.gov Recipients:
"Barnette, James" <James.Barnette@luminant.com>
Tracking Status: None "Jennifer Dixon-Herrity" <Jennifer.Dixon-Herrity@nrc.gov>
Tracking Status: None "Stewart Bailey" <Stewart.Bailey@nrc.gov>
Tracking Status: None "Thomas Scarbrough" <Thomas.Scarbrough@nrc.gov>
Tracking Status: None "Jack Hicks (Jack.Hicks@luminant.com)" <Jack.Hicks@luminant.com>
Tracking Status: None Post Office: SA1PR09MB8111.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 559 4/20/2023 3:31:00 PM L-2023-LLR-0019 Comanche Peak RV-1 Regarding Thermal Relief Valves Verbal Authorization 2023-04-20.pdf 471644 Options Priority: Normal Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:
VERBAL AUTHORIZATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION FOR ALTERNATIVE REQUEST RV-1 EXTENSION REQUEST FOR THERMAL RELIEF VALVES COMANCHE PEAK NUCLEAR POWER PLANT, UNITS 1 AND 2 VISTRA OPERATIONS COMPANY LLC DOCKET NUMBERS 50-445 AND 50-446 EPID: L-2023-LLR-0019 APRIL 20, 2023 Technical Evaluation read by Stewart Bailey, Chief, Mechanical Engineering and Inservice Testing Branch, Division of Engineering and External Hazards, NRC Office of Nuclear Reactor Regulation This call is for the NRC to verbally authorize a request by Vistra Operations Company LLC (Vista, or the licensee) for an alternative to certain inservice testing (IST) requirements specified in the American Society of Mechanical Engineers (ASME) Operation and Maintenance Code (OM) as incorporated by reference in Title 10 of the Code of Federal Regulations, Section 50.55a, for the Comanche Peak Nuclear Power Plant, Units 1 and 2. This verbal authorization is in response to Comanche Peak Alternative Request RV-1, which was submitted electronically on April 13, 2023, in accordance with the provisions in 10 CFR 50.55a(z)(2). Specifically, RV-1 states that following the provisions of the ASME OM Code would result in a hardship or unusual difficulty without a compensating increase in the level of quality and safety in the case of performing specific tests for 19 small thermal relief valves during the spring 2023 refueling outage at Comanche Peak Unit 2, and during the fall 2023 refueling outage at Comanche Peak Unit 1.
The NRC regulations in 10 CFR 50.55a(z) allow licensees to request alternatives to the IST requirements where either (1) the proposed alternative would provide an acceptable level of quality and safety, or (2) compliance with the specified requirements would result in hardship or 1
unusual difficulty without a compensating increase in the level of quality and safety. NRC procedures permit the NRC staff to verbally authorize an alternative to the IST requirements in circumstances where the licensee has docketed all pertinent information, the NRC staff has completed its review, and there is not enough time for the NRC to issue its written safety evaluation before the alternative is needed. That is the case here.
As background, the NRC regulations in 10 CFR 50.55a(f) require licensees to implement IST Programs for pumps, valves, and dynamic restraints that meet the requirements of the ASME OM Code as incorporated by reference in 10 CFR 50.55a. The current ASME OM Code of Record for the Third 10-Year Interval IST Program at Comanche Peak until August 2, 2023, is the 2004 Edition through the 2006 Addenda as incorporated by reference in 10 CFR 50.55a.
On November 4, 2020, the NRC approved a request by the licensee in accordance with 10 CFR 50.55a(f)(4)(iv) to use a portion of the 2017 Edition of the ASME OM Code related to the documentation of IST results for the remainder of the Third 10-Year Interval IST Program at Comanche Peak. Beginning on August 3, 2023, the licensee will be required by 10 CFR 50.55a to implement the Fourth 10-Year Interval IST Program at Comanche Peak with the ASME OM Code of Record being the 2017 Edition as incorporated by reference in 10 CFR 50.55a.
Back to Alternative Request RV-1. In accordance with 10 CFR 50.55a(z)(2), the licensee requested a postponement of testing that the OM Code would require for 19 small thermal relief valves during the upcoming refueling outages at Comanche Peak. The OM Code requirement is in Mandatory Appendix I, paragraph I-1390, Test Frequency, Classes 2 and 3 Pressure Relief Devices That Are Used for Thermal Relief Application. The request is for 10 thermal relief valves in Unit 1 and 9 thermal relief valves in Unit 2. They are all in the Station Service Water (SSW) system. They provide overpressure protection for the SSW side of the Component Cooling Water Heat Exchangers and the SSW side of various emergency core cooling system pump lube oil coolers. In its submittal, the licensee included the information 2
normally provided in the IST Program for these 19 thermal relief valves. The licensee requested that the alternative be authorized until the spring 2025 refueling outage for Unit 1 and the fall 2024 refueling outage for Unit 2 at Comanche Peak when the 19 thermal relief valves will be reworked or replaced with suitable replacement valves or parts. The licensee notes that the duration of Alternative Request RV-1 spans the remainder of the Third 10-Year Interval IST Program and up to the first refueling outage of the Fourth 10-Year Interval IST Program at each unit. With respect to paragraph I-1390, there are no technical differences between the Code editions used for the Third and Fourth 10-year intervals.
In performing their closed safety function, the thermal relief valves within the scope of Alternative Request RV-1 remain closed to maintain the SSW system pressure boundary when the SSW system is in service at Comanche Peak. The open safety function of these thermal relief valves is only required for overpressure protection when the heat exchangers or coolers are isolated for maintenance, or in response to a condition requiring the heat exchanger or cooler to be taken out of service. Regarding operating history, the licensee stated that there has been only one instance of leakage from the relief valves within the scope of Alternative Request RV-1. Further, the licensee indicated that the full open relief rate for one of these 1-inch thermal relief valves would be insignificant compared to the available margin in the safe shutdown impoundment inventory of the SSW system, and less than half the capacity of the applicable sump pumps at Comanche Peak.
In Alternative Request RV-1, the licensee described the controls that will be established to provide assurance that the applicable thermal relief valves will remain closed throughout the duration of the alternative request. The licensee stated that Shift Manager Clearances in the form of Caution Tags will be attached to the applicable heat exchanger and cooler isolation valves and vent valves. These will require the heat exchangers to be vented upon isolation and to remain vented until the heat exchanger is no longer isolated from the safe shutdown impoundment. The Caution Tags will provide directions to open the respective vent valve upon 3
isolation of its heat exchanger. Opening the vent valve will eliminate the potential for an overpressure condition due to thermal expansion that might lead to opening of the applicable thermal relief valve.
In its justification for the alternative request, the licensee stated that the thermal relief valves in question have not been tested for several years because they were inadvertently omitted from the IST Program. The licensee has determined that replacement valves or parts are not currently available. As a result, implementing the ASME OM Code requirement to test the thermal relief valves during the upcoming refueling outages has the potential to cause an extended unavailability of the service water system or emergency core cooling systems. The licensee has initiated several actions to obtain either replacement valves or parts to support testing of the thermal relief valves during the spring 2025 refueling outage for Unit 1 and the fall 2024 refueling outage for Unit 2.
NRC staff review: In its review of Alternative Request RV-1, the NRC staff evaluated (1) the licensees description of the specific inservice tests proposed to be deferred for the 19 thermal relief valves; (2) the open and closed functions of these small thermal relief valves; (3) the overall successful leaktight history of the thermal relief valves; (4) the capability of plant systems to respond to a stuck-open thermal relief valve; (5) the current unavailability of replacement valves or parts for the thermal relief valves; (6) the extensive efforts by the licensee to obtain replacement valves or parts as soon as possible; and (7) the re-initiation of the required testing during the spring 2025 refueling outage for Unit 1 and the fall 2024 refueling outage for Unit 2.
The NRC staff understands that Alternative Request RV-1 spans the remainder of the Third 10-Year Interval IST Program and lasts until the first refueling outage of the Fourth 10-year interval for each unit.
Based on the information provided by the licensee in Alternative Request RV-1, the NRC staff finds that a hardship exists without a compensating increase in the level of quality and safety, in accordance with 10 CFR 50.55a(z)(2), for the performance of the specified IST 4
requirements for the 19 thermal relief valves within the scope of the request during the spring 2023 refueling outage at Comanche Peak Unit 2, and during the fall 2023 refueling outage at Comanche Peak Unit 1. The NRC staff also finds that the licensees proposed alternative to postpone the inservice tests of the applicable 19 thermal relief valves until the spring 2025 refueling outage for Unit 1 and the fall 2024 refueling outage for Unit 2 at Comanche Peak will not adversely impact the reasonable assurance that those valves will be operationally ready to perform their safety functions. Therefore, the NRC staff authorizes Alternative Request RV-1 to defer the specified inservice tests of the applicable 19 thermal relief valves for the remainder of the Third 10-Year Interval IST Program, and until the spring 2025 refueling outage for Unit 1 and the fall 2024 refueling outage for Unit 2 during the Fourth 10-Year Interval IST Program at Comanche Peak. The NRC staff does not authorize Alternative Request RV-1 beyond the spring 2025 refueling outage for Unit 1 or the fall 2024 refueling outage for Unit 2 at Comanche Peak.
All other ASME OM Code requirements for which relief or an alternative was not specifically requested and granted or authorized as part of Alternative Request RV-1 remain applicable. If the licensee identifies a performance issue with any of the thermal relief valves within the scope of the request, the licensee will be expected to take action to implement the requirements of its Technical Specifications. The NRC staffs review of Alternative Request RV-1 for Comanche Peak will be described in detail in a separate safety evaluation.
NRC Staff Conclusion read by Jennifer Dixon Herrity, Chief, Plant Licensing Branch 4, Division of Operating Reactor Licensing, Office of Nuclear Reactor Regulation As Chief of Plant Licensing Branch 4, I concur with the conclusions of the NRR Mechanical Engineering and Inservice Testing Branch.
The NRC staff concludes that Alternative Request RV-1 submitted by the Comanche Peak licensee addresses the hardship or unusual difficulty without a compensating increase in the 5
level of quality and safety for the performance of certain inservice tests required by the ASME OM Code for the specified thermal relief valves.
Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(z)(2) to justify the requested alternative to defer the ASME OM Code IST requirements for the specified thermal relief valves for the remainder of the Third 10-Year Interval IST Program, and until the spring 2025 refueling outage for Unit 1 and the fall 2024 refueling outage for Unit 2 during the Fourth 10-Year Interval IST Program at Comanche Peak.
Therefore, on April 20, 2023, the NRC authorizes Alternative Request RV-1 for the remainder of the Third 10-Year Interval IST Program, and until the spring 2025 refueling outage for Unit 1 and the fall 2024 refueling outage for Unit 2 during the Fourth 10-Year Interval IST Program at Comanche Peak.
All other requirements of the ASME OM Code, for which relief or an alternative was not specifically requested and authorized by the NRC staff, remain applicable.
This verbal authorization does not preclude the NRC staff from asking additional questions and clarifications regarding the licensees proposed alternative while preparing the subsequent written safety evaluation.
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