ML24130A119
| ML24130A119 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 05/07/2024 |
| From: | James Holloway Virginia Electric & Power Co (VEPCO) |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| 24-153 | |
| Download: ML24130A119 (1) | |
Text
VrnGINIA E LECT RIC AND POWER COMPANY RI C H M OND, VIRGINIA 23261 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 May 7, 2024 VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNITS 1 AND 2 10 CFR 50.55a Serial No.24-153 NRA/GDM RO Docket Nos.
50-280/281 License Nos.
DPR-32/37 INSERVICE TESTING PROGRAM FOR PUMPS AND VALVES SIXTH INTERVAL UPDATE AND ASSOCIATED RELIEF AND ALTERNATIVE REQUESTS - RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING ALTERNATIVE REQUEST V-1 By letter dated October 12, 2023 (Agencywide Documents Access and Management System Accession No. ML23285A092), Virginia Electric and Power Company (Dominion Energy Virginia) submitted Alternative Request V-1 for Safety Injection pressure isolation valves to the U.S. Nuclear Regulatory Commission (NRC) in accordance with Title 10 of the Code of Federal Regulations (10 CFR) Section 50.55a, paragraph (z)(2), as part of the Surry Power Station (SPS) Units 1 and 2 Sixth Interval lnservice Testing (1ST)
Program.
By email dated April 10, 2024, the SPS NRC Project Manager provided a request for additional information (RAI) associated with Alternative Request V-1 to facilitate N RC staff review.
Dominion Energy Virginia's response to the NRC RAI is provided in the attachment.
If you have any questions or require additional information, please contact Mr. Gary D.
Miller at (804) 273-2771.
Respectfully,
~
James E. Holloway Vice President - Nuclear Engineering and Fleet Support Commitments contained in this letter: None
Attachment:
Response to NRC Request for Additional Information, Alternative Request V-1
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 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 Authorized Nuclear Inspector Surry Power Station Serial No.24-153 Docket Nos. 50-280/281 Page 2 of 2
Attachment Serial No.24-153 Docket Nos. 50-280/281 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION ALTER~ATIVE REQUEST V-1 SIXTH INTERVAL INSERVICE TESTING PROGRAM SURRY POWER STATION UNITS 1 AND 2 Virginia Electric and Power Company (Dominion Energy Virginia)
Serial No.24-153 Docket Nos. 50-280/281 Attachment RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION ALTERNATIVE REQUEST V-1 SIXTH INTERVAL INSERVICE TESTING PROGRAM SURRY POWER STATION UNITS 1 AND 2 NRC COMMENT:
Background
By letter dated October 12, 2023 (Agencywide Documents Access and Management System Accession No. ML23285A092), Virginia Electric and Power Company (Dominion Energy Virginia) submitted Alternative Request V-1 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 specific requirements of the American Society of Mechanical Engineers (ASME) Operation and Maintenance of Nuclear Power Plants, Division 1, OM Code: Section /ST (OM Code) associated with inservice testing (/ST) for certain check valves at Surry Power Station (SPS), Units 1 and 2.
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, states:
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 Page 1 of 5
Serial No.24-153 Docket Nos. 50-280/281 Attachment (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 (RA/s)
EMIB-RAl-1:
Section 6.A of Alternative Request V-1 refers to vendor guidance to rebuild 6" Ve/an swing check valves. Attachment 2, "Engineering Assessment of Mechanical Agitation Process for Six Inch Ve/an Pressure Isolation Valves," to the licensee's submittal is scoped for 6" Ve/an Pressure Isolation Valves. However, Section 1 of Alternative Request V-1 does not specify the type of check valve within the scope of this request.
The licensee is requested to confirm that the scope of the components in this request are only 6" Ve/an swing check valves or provide additional details regarding the components within the scope of this request.
Dominion Response The components to which this request applies are the twelve (six per unit) 6-inch Velan swing check valves installed in the Safety Injection System as noted in Section 1 of Alternative Request V-1.
EMIB-RAl-2:
The cited precedent (Sequoyah Unit 1 and 2, ML22263A375) for Alternative Request V-1 includes additional controls for mechanical agitation of check valves that do not appear present in this request. For example, the controls in the precedent require that the impact surface of the tool should be relatively large (greater than 1/2" diameter is preferred) and approximately flat or slightly rounded. If available, a rubber coated tool may be used. Those controls also specify that the tool will not impact the body with an edge or sharp point. Further, the controls specify that agitation should be applied incrementally starting with minimal force and may be applied to different locations on the body. In order to prevent damage to the valve or injury to personnel, the licensee is requested to provide additional guidance to this extent within Alternative Request V-1 and all guidance should be listed in sequence for better implementation.
Dominion Response The guidance below is either currently included or will be incorporated into the subject check valve test procedure to further define the use of mechanical agitation when needed to reseat the six-inch Velan check valves listed in Section 1 of Alternative Request V-1.
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Serial No.24-153 Docket Nos. 50-280/281 Attachment The valve body must be inspected prior to the use of mechanical agitation and any pre-existing markings, or defects recorded.
Mechanical agitation of the check valve is to be performed by tapping the valve body using a 15-pound (maximum), flat faced or rounded, rubber or dead blow hammer swung approximately 120 degrees about the elbow without excessive use of the body to accelerate the hammer head. The diameter of the hammer face shall be 1/2 inch or greater.
The surface to be mechanically agitated shall not include valve bolting or flanges.
Only the lower two-thirds of the valve body shall be struck.
The valve shall be visibly inspected after the application of mechanical agitation to ensure no physical external damage to the check valve has occurred.
The valve shall only be struck one time with leakage reassessed prior to striking again.
Should mechanical agitation need to be reapplied, the hammer can be applied to different areas of the valve body above minimum force within the noted limitations above.
The above controls will ensure that mechanical agitation will only be applied to the valve body, and no edges or sharp points will be impacted. These controls will prevent damage to the valve and injury to personnel.
EMIB-RA/-3:
Section 6.A of Alternative Request V-1 is entitled "Review of Maintenance History for Valves in Section 1," but the discussion focuses on leakage testing results for the subject check valves.
The licensee is requested to provide information regarding the maintenance history of the check valves in addition to the leakage testing results, to support the assertion that these check valves have a history of good performance. For example, the cited precedent discussed visual inspection results and freedom of movement checks of the applicable check valves. In addition, the licensee should discuss any significant maintenance activities for the check valves within the scope of Alternative Request V-1, such as lessons learned described in NRG Inspection Report 05000281/2020040 dated December 30, 2020 (ML20365A007).
Dominion Response The subject pressure isolation valves (PIVs) have an open safety function during accident conditions and a closed safety function during power operation.
The PIVs have historically proved to be reliable in performing these functions and have only experienced seating issues during leakage testing, which takes place at a much lower pressure than Page 3 of 5
Serial No.24-153 Docket Nos. 50-280/281 Attachment when the PIVs are performing their reactor coolant pressure boundary function.
Furthermore, no issues have been identified with the PIVs performing their open safety function.
Contingency work orders are in place to open and inspect any PIV that fails an inservice leak test to determine if corrective maintenance is needed. There are currently no active preventative maintenance tasks in place for these valves because they have proven to be reliable in performing their safety functions and are not subject to inservice conditions that would cause degradation or wear of the valve internals. However, consistent with the lessons learned from NRG Inspection Report 05000281/2020040, if a degradation mechanism were to be identified for these valves, the Fleet ASME 1ST Program - Check Valve Condition Monitoring Program procedure would require an assessment of the performance adequacy of the check valves and a determination of whether applicable preventative maintenance activities should be established on a periodic frequency to replace any internal components that exhibited excessive wear.
Mechanical corrective maintenance procedures are currently in place for the inspection and overhaul of the six-inch Velan swing check valves.
The procedures require verification of freedom of movement of the valve internals whenever a PIV is opened for inspection and/or repair to verify there is no binding. The most recent example of this is PIV 1-SI-241. This valve could not pass the prescribed leakage test without mechanical agitation during the spring 2021 refueling outage (RFO), and, as a result, was scheduled to be opened for internal inspection during the fall 2022 RFO. However, due to the inability to establish a tagout boundary during the 2022 RFO, an emergency alternative request was verbally approved by the NRG on December 22, 2022, to permit mechanical agitation of the check valve to effect seating of the valve disc and to defer internal inspection of the valve until the following spring 2024 Unit 1 RFO. The valve was opened and inspected during the ongoing SPS Unit 1 spring RFO and confirmed to have freedom of movement with no binding. In addition, the current condition of the valve body, seat, and disc were determined to be satisfactory.
This inspection provides reasonable assurance the disc is contacting the seat. Even though this valve could not pass the prescribed leakage test without mechanical agitation during the spring 2021 RFO, when the valve was opened and inspected during the current spring 2024 RFO, it was determined to be in an acceptable condition and fully capable of performing its safety functions.
A review of PIV major maintenance history noted that PIVs 1-SI-82, 1-SI-85, 1-SI-241, and 1-SI-243 had been mechanically agitated in 2007 after the valves could not pass their respective seat leakage tests. Since the valves would not seat after several attempts using mechanical agitation, the valves were opened and inspected during that RFO. The disc and seat on the valves were found to be unsatisfactory and replaced. In the 2007 and 2009 time frames, several of these valves underwent major maintenance due to the use of improper maintenance techniques. As a result, a Velan valve specialist was brought in to recommend improved maintenance practices. In addition, the valve discs Page 4 of 5
Serial No.24-153 Docket Nos. 50-280/281 Attachment and seats were replaced, and maintenance procedures were updated to provide better lapping techniques which resolved the ongoing maintenance issues at that time.
Additionally, 1-SI-82 was mechanically agitated in 2009 due to the inability of the valve to pass its seat leakage test, and, following agitation, seat leakage returned to zero. 1-SI-82 was opened and inspected during the next refueling outage and an indication was found on the valve seat. The valve seat was lapped and has not had any additional seat leakage issues since that time.
Additional maintenance history associated with the subject PIVs is described below:
No major maintenance was identified for 1-SI-242 going back to 1995.
2-SI-79 was replaced in May 1999.
2-SI-82 was disassembled in November of 2009. Internals replaced.
2-SI-85 was disassembled in November 2009. Internals and seat replaced.
2-SI-241 was disassembled May 2008. New disc installed.
2-SI-242 was disassembled May 2008. New disc installed.
2-SI-243 was disassembled in May 2008. Valve seat was lapped.
Valve testing and inspection results since 2009 support the conclusion that the subject PIVs are: 1) not experiencing internal degradation issues, 2) maintaining freedom of movement, and 3) favorably responding to mechanical agitation to facilitate seating of the valve.
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