ML25099A136
| ML25099A136 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 04/08/2025 |
| From: | James Holloway Virginia Electric & Power Co (VEPCO) |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| 24-257A | |
| Download: ML25099A136 (1) | |
Text
VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 April 8, 2025 Attn: Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555-0001 10 CFR 50.55a Serial No.:
24-257 A NRA/DPJ:
RO Docket Nos.: 50-280/281 License Nos.: DPR-32/37 VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION ENERGY VIRGINIA)
SURRY POWER STATION UNITS 1 AND 2 ALTERNATIVE REQUEST V USE OF MECHANICAL AGITATION FOR BACK LEAKAGE TESTING OF ACCUMULATOR DISCHARGE CHECK VALVES RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION By letter dated December 30, 2024 (ADAMS Accession No. ML24365A198), Virginia Electric and Power Company (Dominion Energy Virginia) submitted lnservice Testing (1ST) Alternative Request V-2 for Surry Power Station (SPS) Units 1 and 2. The proposed alternative would permit the use of mechanical agitation on accumulator discharge check valves to facilitate back leakage testing. By email dated March 13, 2025 (ADAMS Accession No. ML25072A273), the SPS NRC Project Manager provided a request for additional information (RAI) to assist the NRC staff in completing its review of the proposed alternative request. The Dominion Energy Virginia response to the NRC RAI is provided in the attachment.
Should you have any questions or require additional information, please contact Mr. Daniel P. Johnson at (804) 273-2381.
Respectfully, Ja:l::7 Vice President - Nuclear Engineering and Fleet Support Regulatory commitments contained in this correspondence: None
Attachment:
Response to NRC Request for Additional Information - 1ST Alternative Request V Proposed Alternative to Use Mechanical Agitation for Performing Back Leakage Testing of Accumulator Discharge Check Valves
cc:
U.S. Nuclear Regulatory Commission, Region II Marquis One Tower 245 Peachtree Center Avenue, NE Suite 1200 Atlanta, Georgia 30303-1257 Mr. L. John Klos - Surry NRC Project Manager U. S. Nuclear Regulatory Commission One White Flint North Mail Stop 09 E-3 11555 Rockville Pike Rockville, Maryland 20852 Mr. G. Edward Miller NRC Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North Mail Stop 09 E-3 11555 Rockville Pike Rockville, Maryland 20852-2738 NRC Senior Resident Inspector Surry Power Station Serial No.24-257 A Docket Nos. 50-280/281 Page 2 of 2
Attachment Serial No.24-257 A Docket Nos. 50-280/281 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION 1ST ALTERNATIVE REQUEST V-2 PROPOSED ALTERNATIVE TO USE MECHANICAL AGITATION FOR PERFORMING BACK LEAKAGE TESTING OF ACCUMULATOR DISCHARGE CHECK VALVES Virginia Electric and Power Company (Dominion Energy Virginia)
Surry Power Station Units 1 and 2
Serial No.24-257 A Docket Nos. 50-280/281 Attachment Page 1 of 5 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ALTERNATIVE REQUEST V-2
Background:
DOCKET NOS. 50-280 AND 50-281 EPID L-2024-LLR-0083 SURRY POWER STATION UNITS 1 AND 2 By letter dated December 30, 2024, Virginia Electric and Power Company (Dominion Energy Virginia) submitted Alternative Request V-2 for authorization by the U.S. Nuclear Regulatory Commission (NRG), pursuant to Title 10 of the Code of Federal Regulations (10 CFR} 50.55a(z)(2}, to implement an alternative to the inservice testing (1ST}
requirements of the 2020 Edition of the American Society of Mechanical Engineers (ASME) Operation and Maintenance of Nuclear Power Plants, Division 1, OM Code:
Sectlon 1ST (OM Code), as incorporated by reference in 10 CFR 50.55a, associated with certain accumulator discharge check valves at Surry Power Station (SPS), Units 1 and 2.
By email dated March 13, 2025 (ADAMS Accession No. ML25072A273), the SPS NRG Project Manager provided a request for additional information (RAI) to assist the NRG staff in completing its review of the proposed alternative request. The Dominion Energy Virginia response to the NRG RAI is provided in this attachment.
Regulatory Basis:
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 (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.
REQUESTS FOR ADDITIONAL INFORMATION (RAls):
EMIB-RAl-1 Serial No.24-257 A Docket Nos. 50-280/281 Attachment Page 2 of 5 In Alternative Request V-2, the licensee has requested a duration of the "Sixth and Seventh lnservice Testing Intervals," for this proposed alternative to the ASME OM Code
/ST requirements. The Federal Register notice (FRN) that describes the NRG rulemaking in 10 CFR 50.55a establishing the Code of Record (COR) interval (89 FR 58039) for /ST programs states:
Licensees may request future alternatives based upon the code of record interval. The reference to both the Sixth and Seventh /ST Program Intervals at SPS might be unclear in the future with the establishment of the new COR interval definition. Therefore, the licensee is requested to revise Alternative Request V-2 to specify that its proposed duration is for the Code of Record Interval at SPS, Units 1 and 2, that uses the 2020 Edition of the ASME OM Code, as incorporated by reference in 10 CFR 50. 55a.
Dominion Energy Virginia Response to EMIB-RAl-1 Dominion Energy is supplementing Alternative Request V-2 to state that the proposed duration for SPS Units 1 and 2 Alternative Request V-2 is for the Code of Record interval that uses the 2020 Edition of the ASME OM Code, as incorporated by reference in 10 CFR 50.55a.
EMIB-RAl-2 Section 4, "Reason for Request," of Alternative Request V-2 specifies back leakage testing requirements for the check valves within the scope of the request. However, both back leakage and closure tests are discussed on page 5 of 11 of the alternative request.
The licensee is requested to clarify (1) the testing requirements for the check valves within the scope of the alternative 'request, (2) when closure tests are required, and (3) the type of testing included in Tables V-2.1 and V-2.2 of the alternative request.
Dominion Energy Virginia Response to EMIB-RAl-2 The testing requirement for the Accumulator Discharge Check Valves (ADCVs) within the scope of this proposed alternative is limited to the back leakage test, which is a type of closure test. No other closure tests are required for the ADCVs. Should additional check valve closure tests applicable to these valves be introduced in the future, mechanical agitation would not be used without seeking prior NRG approval. The test history shown in Tables V-2.1 and V-2.2 is for historical back leakage testing. There are no other closure test results to provide within this review period.
EMIB-RAl-3 Serial No.24-257 A Docket Nos. 50-280/281 Attachment Page 3 of 5 Alternative Request V-2 describes the requirements for, and the evaluation of, the proposed mechanical agitation of check valves within the scope of the request at SPS, Units 1 and 2. On August 12, 2024 (ML24164A001), the NRG authorized Alternative Request V-1 for proposed mechanical agitation of other specific valves at SPS, Units 1 and 2. The NRG staff has reviewed the differences between these two alternative requests. For example, the staff identified the following questions based on its review:
- a. Is the hammer to be used when implementing Alternative Request V-2 restricted to a rounded or flat-faced hammer?
Dominion Energy Virginia Response to EMIB-RAl-3(a)
Consistent with Alternative Request V-1, the hammer to be used when implementing Alternative Request V-2 will be a flat faced, or rounded, rubber or dead blow hammer with a hammer face diameter 1/2 inch or greater.
- b. Is there a plan required under Alternative Request V-2 to verify that the mechanical agitation process does not cause adverse or detrimental effects to the valves?
Dominion Energy Virginia Response to EMIB-RAl-3(b)
Before and after mechanical agitation, the check valve will be visually inspected for any signs of external damage.
Specifically, visual inspection of the valve body will be performed prior to mechanical agitation, and any pre-existing damage, markings, or defects will be recorded.
Following mechanical agitation, the valve will be visibly inspected to ensure no physical external damage to the check valve has occurred.
Finally, the check valve will be opened and inspected during the next refueling outage to verify there is no internal damage to the valve due to mechanical agitation.
- c. Was Anchor Darling contacted as part of evaluating the process for Alternative Request V-2 similar to the licensee's outreach to Ve/an for Alternative Request V-1?
Dominion Energy Virginia Response to EMIB-RAl-3(c)
Anchor Darling (Flowserve) was contacted as part of the evaluation process for Alternative Request V-2, and confirmed mechanical agitation (using a reasonable amount of applied force) is an acceptable method to use for reseating valves of this type during back leakage testing.
Serial No.24-257 A Docket Nos. 50-280/281 Attachment Page 4 of 5
- d. Is the referenced evaluation in Alternative Request V-2 a common evaluation for both Anchor Darling and Ve/an valves, or is the evaluation specific to the valve vendor?
Dominion Energy Virginia Response to EMIB-RAl-3(d)
The referenced evaluation in Alternative Request V-2 is a common evaluation for both the Anchor Darling and Velan check valves and is based on the historical operating experience of both valves, as well as input from both vendors.
The licensee is requested to clarify these and any other differences between the requirements for, and the evaluation of, the proposed mechanical agitation of the applicable valves for Alternative Requests V-1 and V-2.
Dominion Energy Virginia Response to EMIB-RAl-3 Dominion Energy Virginia intends to implement the controls and processes of mechanical agitation of the ADCVs included in Alternative Request V-2 in the same manner as the check valves included in Alternative Request V-1, which was NRC approved by letter dated August 12, 2024 (ML24164A001 ).
EMIB-RAl-4 To ensure appropriate implementation of the mechanical agitation process, the NRG staff requests that the licensee confirm that all steps taken to apply mechanical agitation as described in Alternative Request V-2 for the subject check valves will be included in plant procedures at SPS, Units 1 and 2.
Dominion Energy Virginia Response to EMIB-RAl-4 To ensure appropriate implementation of the mechanical agitation process, Dominion Energy Virginia will incorporate the required steps discussed in Alternative Request V-2 regarding the use of mechanical agitation on the ADCVs into SPS Units 1 and 2 plant procedures prior to use.
EMIB-RAl-5 Serial No.24-257 A Docket Nos. 50-280/281 Attachment Page 5 of 5 The "Engineering Assessment of Mechanical Agitation Process for Accumulator Discharge Check Valves" for Alternative Request V-2 specifies that the derivation of valve length is conservative and consistent with TV A. The NRG staff notes that a 12-inch swing check valve resulted in a 29-inch valve length for Alternative Request V-2, while the method described in Alternative Request V-1 resulted in a 22-inch valve length for a 6-inch swing check valve. The licensee is requested to describe the derivation of the valve length as part of the method to be implemented under Alternative Request V-2 at SPS, Units 1 and 2.
Dominion Energy Virginia Response to EMIB-RAl-5 The valve length of 29-inches for the 12-inch Anchor Darling swing check valves was obtained from a vendor drawing of the valve and reflects the actual total valve length. It is conservative to use total valve length in calculating the moment applied by the mechanical agitation. The use of total valve length is consistent with the TV A and Dominion Energy Virginia V-1 Alternative Requests.