ML24121A100
| ML24121A100 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 04/29/2024 |
| From: | James Holloway Dominion Energy South Carolina |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| 24-133 | |
| Download: ML24121A100 (1) | |
Text
Dominion Energy South Carolina, Inc.
5000 Dominion Boulevard, Glen Allen, VA 23060 Dominion Energy.com April 29, 2024 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 DOMINION ENERGY SOUTH CAROLINA VIRGIL C. SUMMER NUCLEAR STATION UNIT 1
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Serial No.
NRA/JH Docket No.
License No.24-133 R2 50-395 NPF-12 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING ALTERNATIVE REQUEST RR-5-V2 In reference, 1, Dominion Energy South Carolina (DESC) submitted relief and alternative requests for pumps and valves included in the Virgil C. Summer Nuclear Station (VCSNS)
Unit 1 Inservice Testing Program for the fifth interval.
The fifth interval begins on January 1, 2025 for VCSNS Unit 1. Pursuant to 10 CFR 50.55a(z)( 1 ), DESC requested an alternative providing an acceptable level of quality and safety.
In reference 2, the NRC issued a draft request for additional information (RAI) related to alternative request RR-5-V2, which was included in reference 1. DESC indicated that a clarification call was not necessary to respond to the information request and agreed to respond to the RAI by April 29, 2024. The attachment provides DESC's response to the RAI.
There are no new or revised commitments contained in this submittal.
In accordance with 10 CFR 50.91, a copy of this submittal along with the attachment is being provided to the designated South Carolina State Officials.
Should you have any questions regarding this submittal, please contact Julie Hough at (804) 273-3586.
Sincerely, James Holloway Vice President - Nuclear Engineering and Fleet Support
Serial No.24-133 Docket No. 50-395 Page 2 of 3
References:
- 1. Letter from J. Holloway (DESC) to U.S. Nuclear Regulatory Commission (NRG), "Dominion Energy South Carolina Virgil C.
Summer Nuclear Station Unit 1 In-Service Testing Program for Pumps and Valves Fifth Interval Update and Associated Relief and Alternative Requests," dated December 21, 2023. (ADAMS Accession No. ML23361A104)
Attachment:
- 2. Email from G. Miller (NRG) to Y. Gao (DESC), "Draft RAls for RR V2 (L-2023-LLR-0068)," dated March 15, 2024. (ADAMS Accession No. ML24075A187)
Response to Request for Additional Information Associated with VCSNS Unit 1 Alternative Request RR-5-V2 Commitments made in this letter: None cc:
U.S. Nuclear Regulatory Commission, Region II Marquis One Tower 245 Peachtree Center Avenue, NE Suite 1200 Atlanta, Georgia 30303-1257 Mr. G. Edward Miller NRG Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Rockville, Maryland 20852-2738 Mr. Zach M. Turner NRG Project Manager U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Rockville, Maryland 20852-2738 NRG Senior Resident Inspector V.C. Summer Nuclear Station Ms. Robin S. Mark Bureau of Environmental Health Services South Carolina Department of Health and Environmental Control 8500 Farrow Road - Building 17 Columbia, SC 29203
cc:
( continued)
Mr. G. J. Lindamood Santee Cooper - Nuclear Coordinator 1 Riverwood Drive Moncks Corner, SC 29461 Serial No.24-133 Docket No. 50-395 Page 3 of 3
Attachment Serial No.24-133 Docket Nos. 50-395 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ASSOCIATED WITH VCSNS UNIT 1 ALTERNATIVE REQUEST RR-5-V2 Virgil C. Summer Nuclear Station (VCSNS) Unit 1 Dominion Energy South Carolina, Inc. (DESC)
Serial No.24-133 Alternative Request RR-5-V2 RAI Response Attachment, Page 1 of 3 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION Alternative Request RR-5-V2
Background
In a letter dated December 21, 2023 (Agencywide Documents Access and Management System Accession No. ML23361A104), Dominion Energy South Carolina, Inc. (DESC, licensee) submitted requests related to the Fifth Interval lnservice Testing (1ST) Program at the Virgil C. Summer Nuclear Station (VCSNS) Unit 1. In Alternative Request RR V2, the licensee proposes to perform testing of specific valves at VCSNS Unit 1 at intervals ranging from every refueling outage to every fourth refueling outage. The licensee submitted Alternative Request RR-5-V2 pursuant to Title 10 of the Code of Federal Regulations (10 CFR), Part 50, Section 55a, Codes and standards, paragraph (z)(1), on the basis that the proposed alternative would provide an acceptable level of quality and safety.
Regulatory Requirements The NRG regulations in 10 CFR 50.55a(f)(4), lnservice testing standards requirement for operating plants, state, in part, that throughout the service life of a boiling or pressurized water-cooled nuclear power facility, pumps and valves that are within the scope of the American Society of Mechanical Engineers (ASME) Operation and Maintenance of Nuclear Power Plants, Division 1, OM Code: Section /ST (OM Code) must meet the inservice test requirements (except design and access provisions) set forth in the ASME OM Code and addenda that become effective subsequent to editions and addenda specified in paragraphs 10 CFR 50.55a(f)(2) and (3) and that are incorporated by reference in paragraph 10 CFR 50.55a(a)(1)(iv), to the extent practical within the limitations of design, geometry, and materials of construction of the components.
The NRG regulations in 10 CFR 50.55a(z), Alternatives to codes and standards requirements, state:
Alternatives to the requirements of paragraphs (b) through (h) of this section or portions thereof may be used when authorized by the Director, Office of Nuclear Reactor Regulation. A proposed alternative must be submitted and authorized prior to implementation. The applicant or licensee must demonstrate that:
(1) Acceptable level of quality and safety. The proposed alternative would provide an acceptable level of quality and safety; or
Serial No.24-133 Alternative Request RR-5-V2 RAI Response Attachment, Page 2 of 3 (2) Hardship without a compensating increase in quality and safety. Compliance with the specified requirements of this section would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
Request for Additional Information VCSNS Unit 1 Alternative Request RR-5-V2 specifies that the specified interval for each valve would be a function of its performance and would be established in a manner consistent with the containment isolation valve extended test eligibility process guidance under 10 CFR Part 50, Appendix J, "Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors," Option B. The leakage data provided in Alternative Request RR-5-V2 for the applicable valves show a wide variation in the measured leakage rates over many years. The NRG staff requests the licensee to describe the representative sampling of the subject valves (e.g., plans to obtain test data during outages to support an extended test interval program) within the scope of the request during each refueling outage for leakage testing when implementing Alternative Request RR-5-V2. Please clarify how the historical data of the leakage rates will be used to determine an initial and successive sampling program to ensure that valves with increasing trends do not exceed their leakage limits before their next scheduled test.
DESC Response As discussed in RR-5-V2, Section 5, VCSNS is requesting perm1ss1on to use performance-based testing intervals for seat leakage testing of the PIVs and closure testing of check valves XVC08703A/B-RH that would be comparable to the performance-based Option Bin Appendix J for Local Leak Rate Testing.
Following NRC approval of Alternative Request RR-5-V2, the impacts to the 1ST Program due to this alternative will be implemented, including the Check Valve Condition Monitoring (CVCM) plans. Leakage testing of these PIVs will be specified in the CVCM plans.
Test frequencies shall be sufficient to maintain leakage rates within permissible leakage rates. Trending and evaluation of existing data shall be used as the bases to justify the time interval between tests. To support the leakage rate testing intervals, the applicable preventive maintenance activities and associated intervals required to maintain continued acceptable performance of the valves shall be identified.
Test performances would occur at a nominal frequency ranging from every refueling outage to every fourth refueling outage, subject to acceptable valve performance. Valves that have demonstrated good performance for two prior consecutive surveillance tests not exceeding the acceptance criteria may have their test interval extended. If a valve
Serial No.24-133 Alternative Request RR-5-V2 RAI Response Attachment, Page 3 of 3 exceeds the acceptance criteria, the test interval will be reduced to the initial interval of every refueling outage (RFO), or two years, until good performance is re-established.
Adequate margin shall exist and be trended such that leakage shall not be expected to exceed the acceptance criteria prior to the next scheduled test.
Valve testing will be scheduled and performed such that all of the valves are tested throughout the interval. No maximum limit is specified for the number of valves to be tested during any single 24-month interval; however, a minimum of 20% of the PIVs shall be tested within any 24-month interval. This 20% shall consist of valves that have not been tested during the 75-month interval (with a permissible 9-month extension for non-routine emergent conditions for a total of 84 months), if they exist.
Group testing of PIVs will continue to be performed where such capability exists. Group testing is more conservative, because the most limiting acceptance criteria is applied when testing a single valve or group consisting of multiple valves. Individual testing of PIVs will be performed for the purpose of identifying leakage and troubleshooting when required. Check valves XVC08703A/B-RH will continue to be tested in parallel with PIVs XVG08702A/B-RH. If leakage through both valves is unacceptable, XVC08703A/B-RH can be isolated so that XVG08702A/B-RH can be tested independently to determine the source of the leakage. XVC08703A/B-RH cannot be tested independently.
Separate functional testing of the PIVs and check valves XVC08703A/B-RH will continue to be conducted per the ASME OM Code.