ML23361A104

From kanterella
Jump to navigation Jump to search
Inservice Testing Program for Pumps and Valves Fifth Interval Update and Associated Relief and Alternative Requests
ML23361A104
Person / Time
Site: Summer South Carolina Electric & Gas Company icon.png
Issue date: 12/21/2023
From: James Holloway
Dominion Energy South Carolina
To:
Office of Nuclear Reactor Regulation, Document Control Desk
References
23-326
Download: ML23361A104 (1)


Text

Dominion Energy South Carolina, Inc.

5000 Dominion Boulevard, Glen Allen, VA 23060

_______ Dominion Dominion Energy.com ~ Energy Dec.ember 21, 2023 Attn: Document Control Desk Serial No.: 23-326 U. S. Nuclear Regulatory Commission NRANG: RO Washington, DC 20555-0001 Docket No.: 50-395 License No.: NPF-12 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 Pursuant to the provisions of 10 CFR 50.55a(f)(4)(ii), Dominion Energy South Carolina, Inc. (DESC), hereby submits the attached relief and alternative requests for pumps and valves included in the Virgil C. Summer Nuclear Station (VCSNS) Unit 1 lnservice Testing Program for the fifth (5th ) interval. 10 CFR 50.55a(a)(1 )(iv)(C)(3) refers to the American Society of Mechanical Engineers (ASME), Operation and Maintenance (OM) Code, Operation and Maintenance of Nuclear Plants, 2020 Edition. The ASME OM Code reference became effective on November 28, 2022, and applies to the fifth (5th ) interval for VCSNS Unit 1. The VCSNS Unit 1 1ST Program for the fifth (5th ) 1ST interval will be updated to comply with the appropriate edition of the ASME OM Code. The fifth interval starts on January 1, 2025, for VCSNS Unit 1.

VCSNS Unit 1 is currently in the fourth in-service testing (1ST) interval, from January 1, 2014, to December 31, 2024 (DESC previously submitted a letter to extend the fourth 10-year 1ST end date to December 31, 2024, from December 31, 2023 [ADAMS Accession No. ML22314A258].)

As part of this submittal, one (1) relief request (RR-5-V1) is submitted pursuant to 10 CFR 50.55a(f)(5)(iii) due to impracticality; two (2) alternative requests, one (1) for pressure isolation valves and one (1) for charging/safety injection pumps, are submitted pursuant to 10 CFR 50.55a(z)(1) as providing an acceptable level of quality and safety. A description of each of these three requests is provided in Attachment 1 , Attachment 2, and Attachment 3, respectively.

Pursuant to 10 CFR 50.55a(f)(6)(i) and 10 CFR 50.55a(z), the proposed requests require Nuclear Regulatory Commission (NRC) review and approval prior to implementation.

DESC requests NRC approval of the VCSNS Unit 1 fifth (5th ) interval 1ST program relief and alternative requests by December 19, 2024. The remaining portions of the 1ST Program are within the provisions of the Code and therefore do not require NRC approval for implementation.

In accordance with 10 CFR 50.91, a copy of this submittal, with Attachments, is being provided to the designated South Carolina State Officials.

Serial No.23-326 Docket No. 50-395 Page 2 of 3 Should you have any questions related to this submittal, please contact Yan Gao at (804) 273-2768.

Respectfully,

():~

James E. olloway Vice President - Nuclear Engineering and Fleet Support Commitments made in this letter: None.

Attachments:

1. Relief Request RR-5-V1
2. Alternative Request RR-5-V2
3. Alternative Request RR-5-P1

Serial No.23-326 Docket No. 50-395 Page 3 of 3 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 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 Mr. Zach M. Turner NRC Project Manager U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Rockville, Maryland 20852-2738 NRC 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 Mr. G. J. Lindamood Santee Cooper - Nuclear Coordinator 1 Riverwood Drive Moncks Corner, SC 29461

Serial No.23-326 Docket No. 50-395 Attachment 1 Relief Request RR-5-V1 Service Water Return Header Check Valves Virgil C. Summer Nuclear Station (VCSNS) Unit 1 Dominion Energy South Carolina, Inc. (DESC)

Serial No.23-326 Docket No. 50-395 Attachment 1 RR-5-V1: Page 2 of 4 Relief Request RR-5-V1 Service Water Return Header Check Valves Pursuant to 10 CFR 50.55a{f){5)(iii) and 10 CFR 50.55a{f){5){iv) 1.0 ASME CODE COMPONENT{S) AFFECTED Two (2) normally open, Service Water (SW) system discharge check valves, as shown in Table 1 below, are included in this relief request. These two valves perform no safety function in the closed position but perform an active safety function in the open position to allow SW return flow to the Service Water Pond. Unimpaired return flow is required for the SW system to provide maximum cooling of essential heat loads during accident conditions.

Table 1 - ASME Code Components

/t}t9R~f}

  • ,~~.i~g"q,w:?

SW Pond SW Return Header A Inlet 3 C Check Valve VC03130B-SW SW Pond SW Return Header B Inlet 3 C Check Valve 2.0 APPLICABLE CODE EDITION AND ADDENDA American Society of Mechanical Engineers (ASME), Operation and Maintenance (OM)

Code, Operation and Maintenance of Nuclear Plants, 2020 Edition [8.1 ].

3.0 APPLICABLE CODE REQUIREMENT ASME OM Code Subsection ISTC-3522, Category C Check Valves, specifies check valve exercising requirements and sub-paragraph (a) states in part that, "... each check valve shall be exercised or examined in a manner that verifies obturator travel by using the methods in ISTC-5221. Each check valve exercise test shall include open and close tests".

ASME OM Code Subsection ISTC-5221, Check Valve Obturator Movement, sub-paragraph (a) specifies that, 'The necessary valve obturator movement during exercise testing shall be demonstrated by performing both an open and a close test". Sub-paragraph (a)(2) also states, "Check valves that have a safety function in only the open direction shall be exercised by initiating flow and observing that the obturator has traveled

Serial No.23-326 Docket No. 50-395 Attachment 1 RR-5-V1: Page 3 of 4 either (to) the fully open position or to the position required to perform its intended function(s) (see ISTA-1100) and verify closure."

4.0 NOTIFICATION OF IMPRACTICAL CODE REQUIREMENT PURSUANT TO 10 CFR 50.55a{f)(5)(iii)

Most of the VCSNS SW return pIpmg is underground, including these SW system discharge check valves, buried without direct access. The system configuration does not provide a means to employ non-intrusive test methods or disassembly to confirm valve closure. To comply with the Code open and close testing requirements, either routine excavations or a system modification would be required. Since the valves are buried without direct access, excavation would be required every outage to allow access to the valves to facilitate valve disassembly and inspection or to employ non-intrusive test methods. Alternatively, a design modification would be required to allow routine access to the valves to allow testing of the valves in the closed direction using non-intrusive test methods or system operation.

5.0 PROPOSED RELIEF (SCHEDULE FOR COMPLETING IMPRACTICALITY DETERMINATION PURSUANT TO 10 CFR 50.55a(f)(5)(iv})

This Relief Request proposes to test by verifying these check valves in the open position instead of testing/verifying both open and close positions as stated in the Code requirement, i.e., VCSNS will exercise these check valves and verify the valves to be in the safety related fully open position during refueling outages without performing verification of the non-safety related closed position.

The design close function of these check valves is to prevent siphoning of the pond in the event of a postulated crack of a large diameter pipe in the SW system piping and to prevent inadvertent flooding during SW system maintenance from an incorrect valve lineup. The SW piping is moderate energy piping. Therefore, the design rules require that cracks, not breaks, must be postulated. Calculations for the postulated crack project a leak flow range less than the capacities of the sump pumps in the affected areas.

Due to the relatively small size of the resulting crack, the existing plant can easily handle a leak without requiring the valves to shut. Therefore, the back-seat function has been determined to not be required since the SW system and the Auxiliary and Intermediate buildings are designed to accommodate all postulated cracks. Also, due to the design of the valve (duo-disc), age related degradation of the valve would not affect the valve's ability to perform its safety related function. Using the provisions of this request, open testing/verification will provide reasonable assurance of the SW system discharge check valves' operational readiness.

Serial No.23-326 Docket No. 50-395 Attachment 1 RR-5-V1: Page 4 of 4 Based on the absence of a safety function in the closed position, elimination of bi-directional reverse flow closure testing has no safety impact. DESC requests approval of the relief request from the specific ISTC requirements identified in this request.

6.0 DURATION OF PROPOSED RELIEF This relief request, upon approval, will be utilized during the VCSNS fifth (5 th ) lnservice Testing (1ST) Interval, which begins on January 1, 2025.

7.0 PRECEDENTS The NRC has previously approved this relief request for the third and fourth 1ST intervals at VCSNS and concluded that the licensee's request for relief was granted pursuant to 10 CFR 50.55a(f)(6)(i) on the basis that compliance with the ASME OM Code requirements is impractical. The NRC further concluded that granting the relief did not endanger life or property or the common defense and security, and was otherwise in the public interest giving due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility [8.2] [8.3].

8.0 REFERENCES

8.1 American Society of Mechanical Engineers (ASME), Operation and Maintenance (OM) Code, Operation and Maintenance of Nuclear Plants, 2020 Edition 8.2 ADAMS Accession No. ML13301A767, NRC Letter, "Virgil C. Summer Nuclear Station, Unit 1 - Relief Request (RR-4-01, RR-4-02, RR-4-03) for Third and Fourth Ten-Year lnservice Inspection Interval (TAC Nos. MD1900, MF1901, MF1902),"

November 5, 2013 8.3 ADAMS Accession No. ML042110354, NRC Letter, "Safety Evaluation of Relief Request RR3-V-1 Related to the Third 10-Year lnservice Testing Interval for Virgil C. Summer Nuclear Station (TAC No. MC2623)," August 18, 2004

Serial No.23-326 Docket No. 50-395 Attachment 2 Alternative Request RR-5-V2 Pressure Isolation Valves Pursuant to 10CFR 50.55a(z)(1)

Virgil C. Summer Nuclear Station (VCSNS) Unit 1 Dominion Energy South Carolina, Inc. (DESC)

Serial No.23-326 Docket No. 50-395 Attachment 2 RR-5-V2: Page 2 of 20 Alternative Request RR-5-V2 Pressure Isolation Valves Pursuant to 10 CFR 50.55a(z)(1) 1.0 ASME CODE COMPONENT{S) AFFECTED Thirty-seven (37) valves, as shown in Table 1 below, are included in this alternative request (AR). With the exception of valves No. 5 and 6, thirty-five (35) of these valves are Reactor Coolant System (RCS) Pressure Isolation Valves (PIVs) with functions to provide reactor coolant pressure boundary isolation by separating the high-pressure RCS from an attached lower-pressure system, and prevent excessive PIV leakage which could lead to overpressure of the low-pressure piping or components, potentially resulting in a loss of coolant accident (LOCA) outside of containment.

Valves No. 5 and 6 (XVC08703A/B-RH) in Table 1, are not identified as PIVs in Technical Specifications (TS) Table 3.4-1. These valves are Residual Heat Removal (RHR) check valves located in bypass lines around the inner RHR Inlet Isolation motor operated valves (MOVs) (XVG08702A/B-RH, valves No. 3 and 4) and perform an active safety function in the open position to provide overpressure protection due to thermal buildup occurring in the interconnecting piping between the RHR Inlet Isolation MOVs (XVG08701A/B-RH, valves No. 1 and 2, and XVG08702A/B-RH, valves No. 3 and 4). These two valves (valves No. 5 and 6) perform an active safety function in the closed position by providing high to low pressure boundary isolation.

Table 1 -ASME Code Components Affected 2 VG08701 B-RH RH Header B Isolation Valve (IRC) 1 A 3 VG08702A-RH RH Inlet Header A Isolation Valve 1 A 4 VG08702B-RH RH Inlet Header B Isolation Valve 1 A 5 VC08703A-RH RH Header A Bypass Check Valve (IRC) 2 A/C 6 VC08703B-RH RH Header B Bypass Check Valve (IRC) 2 A/C 7 VC08948A-SI SI Loop A Outlet Header Check Valve 1 A/C 8 VC08948B-SI SI Loop B Outlet Header Check Valve 1 A/C 9 VC08948C-SI SI Loop C Outlet Header Check Valve 1 A/C 10 VC08956A-SI SI Accum A Disch Header Check Valve 1 A/C 11 VC089568-SI SI Accum B Disch Header Check Valve 1 A/C 12 VC08956C-SI SI Accum C Disch Header Check Valve 1 A/C

Serial No.23-326 Docket No. 50-395 Attachment 2 RR-5-V2: Page 3 of 20 Table 1 -ASME Code Components Affected - (continued)

tij~
\ l'trtt" 0irJ:::.{,JJL"fS;/J/.1,:,&ti\****d l*t>;;(:;c..,).r});'il'lf);f,, *.;*})}'},ic'}?Lf,,);:i/ic<t' £If!;.~ }f~t~g9ry),

13 D<VC08973A-SI RCS Loop A Cold Leg Inlet Hdr Check Valve 1 A/C 14 D<VC08973B-SI RCS Loop B Cold Leg Inlet Hdr Check Valve 1 A/C 15 D<VC08973C-SI RCS Loop C Cold Leg Inlet Hdr Check Valve 1 A/C 16 D<VC08974A-SI SI Header A Check Valve (IRC) 2 A/C 17 D<VC08974B-SI SI Header B Check Valve (IRC) 2 A/C 18 D<VC08988A-SI RHR Supply Header Check Valve 1 A/C 19 D<VC08988B-SI RHR Supply Header Check Valve 1 A/C 20 D<VC08990A-SI Loop A Low Head Hot Leg Check Valve 1 A/C 21 D<VC08990B-SI Loop B Low Head Hot Leg Check Valve 1 A/C 22 D<VC08990C-SI Loop C Low Head Hot Leg Check Valve 1 A/C 23 D<VC08992A-SI Loop A High Head Hot Leg Check Valve 1 A/C 24 D<VC08992B-SI Loop B High Head Hot Leg Check Valve 1 A/C 25 D<VC08992C-SI Loop C High Head Hot Leg Check Valve 1 A/C 26 D<VC08993A-SI Loop A High Head Hot Leg Hdr Check Valve 1 A/C 27 D<VC08993B-SI Loop B High Head Hot Leg Hdr Check Valve 1 A/C 28 D<VC08993C-SI Loop C High Head Hot Leg Hdr Check Valve 1 A/C 29 D<VC08995A-SI Loop A High Head Cold Leg Check Valve 1 A/C 30 D<VC089958-SI Loop B High Head Cold Leg Check Valve 1 A/C 31 D<VC08995C-SI Loop C High Head Cold Leg Check Valve 1 A/C 32 D<VC08997A-SI Loop A Low Head Cold Leg Check Valve 1 A/C 33 D<VC08997B-SI Loop B Low Head Cold Leg Check Valve 1 A/C 34 ~VC08997C-SI Loop C Low Head Cold Leg Check Valve 1 A/C 35 ~VC08998A-SI Loop A Low Head Cold Leg Check Valve 1 A/C 36 ~VC089988-SI Loop B Low Head Cold Leg Check Valve 1 A/C 37 ~VC08998C-SI Loop C Low Head Cold Leg Check Valve 1 A/C Note*: RH: Residual Heat, SI: Safety Injection 2.0 APPLICABLE CODE EDITION AND ADDENDA American Society of Mechanical Engineers (ASME), Operation and Maintenance (OM)

Code, Operation and Maintenance of Nuclear Plants, 2020 Edition [8.1 ].

Serial No.23-326 Docket No. 50-395 Attachment 2 RR-5-V2: Page 4 of 20 3.0 APPLICABLE CODE REQUIREMENT ASME OM Code Subsection ISTC-3630, Leakage Rate for Other Than Containment Isolation Valves, states, in part that, "Category A valves with a leakage requirement not based on an Owner's 10 CFR 50, Appendix J program, shall be tested to verify their seat leakages within acceptable limits. Valve closure before seat leakage testing shall be by using the valve operator with no additional closing force applied."

ASME OM Code Subsection ISTC-3630, paragraph (a) requires that leakage rate testing for Category A valves with a leakage requirement not based on an owner's 10 CFR 50, Appendix J program be performed at least once every two (2) years.

4.0 BACKGROUND

AND REASON FOR ALTERNATIVE REQUEST A similar alternative request (AR) was submitted and approved for VCSNS for the fourth (4th) 1ST interval. VCSNS previously submitted requests to use a performance-based testing frequency for the same set of PIVs and the two (2) RHR Header Bypass Check Valves. In the previous requests, VCSNS proposed to perform testing of these PIVs at intervals ranging from every refueling outage (RFO) to every third RFO, not to exceed 60 months. Additionally, the requests proposed that the specific test interval for each valve would be a function of its performance and would be established in a manner consistent with the Containment Isolation Valve (CIV) extended test eligibility process guidance under 10 CFR 50, Appendix J, Option B. In this submittal, NEI 94-01 Revision 3-A, "Industry Guideline For Implementing Performance-Based Option of 10 CFR Part 50, Appendix J" [8.9] methodology is being applied for the VCSNS fifth (5 th ) 1ST interval as the basis for extending the test interval to every fourth (4th ) RFO, not to exceed 75-months, with a permissible extension (for non-routine emergent conditions) of nine months (84 months total).

ASME OM Code Subsection ISTC-3630, paragraph (a) requires that leakage rate testing for Category A valves with a leakage requirement not based on an owner's 10 CFR 50, Appendix J program be performed at least once every two years. Since PIVs may or may not be containment isolation valves (CIVs), they are not necessarily included in scope for performance-based testing as provided in 10 CFR 50, Appendix J, Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors, Option B, Performance Based-Requirements.

The concept behind the Option B alternative for CIVs is that licensees should be allowed to adopt cost effective methods for complying with regulatory requirements. Additionally, NEI 94-01, Revision 3-A [8.9] describes the risk-informed basis for the extended test intervals under Option B. The discussion concludes that CIVs which have demonstrated good performance by the successfu I completion of two consecutive leakage rate tests over two consecutive cycles, licensees may increase their frequencies. NEI 94-01, Revision 3-A [8.9] also presents the results of a comprehensive risk analysis, including the conclusion that "the risk impact associated with increasing [leak rate] test intervals is negligible (i.e., less than 0.1 percent of total risk)."

Serial No.23-326 Docket No. 50-395 Attachment 2 RR-5-V2: Page 5 of 20 The valves identified in this request are all in water applications. Testing is performed with water pressurized to slightly below or at the function maximum pressure differential; however, where necessary the observed leakage is adjusted to the function maximum pressure differential value in accordance with ASME OM Code Subsection ISTC-3630, paragraph (b) Differential Test Pressure, item (4). Testing of the PIVs is performed during plant startup following a refueling shutdown. The testing is performed by applying test pressure to the Reactor Coolant System (RCS) side of the disk by using the RCS as the pressure source or the Charging System via the Emergency Core Cooling System (ECCS) test header and the associated flow meters. The purpose of the test is to perform Category A, seat leakage testing of the PIVs. Although the testing of the PIVs includes a limit on allowable PIV leakage rate, the main purpose of this limit is to prevent overpressure failure of the low-pressure portions of connecting systems. The allowable leakage limit provides a standard against which the PIV leakage can be compared to determine if the component is degraded or degrading. Excessive PIV leakage (i.e.,

greater than the allowable leakage limit) could lead to over-pressurization of the low-pressure piping or components, potentially resulting in a loss of coolant accident (LOCA) outside of containment.

The RHR Header Bypass Check Valves (XVC08703A/B-RH) are 0.75-inch check valves located in the bypass lines around the inner RHR Inlet Isolation valves (XVG08702A/B-RH). The purpose of these check valves is to open and provide over-pressure relief due to thermal buildup in the piping between the RHR Inlet Isolation valves (XVG08701A/B-RH and XVG08702A/BRH) and to close to prevent pressure/flow from bypassing XVG08702A/B-RH. Check valves XVC08703A/B-RH are not identified in Technical Specifications (TS) Table 3.4-1 as PIVs; however, XVC08703A/B-RH are leak tested in parallel with XVG08702A/B-RH using the same VCSNS procedure, STP-215.008, SI and RHR System Valve Leakage Test, and under the same plant conditions. 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.

This proposed alternative is intended to provide for a performance-based scheduling of PIV tests at VCSNS and align the testing frequency of the two RHR Header Bypass Check Valves with the performance-based testing of the PIVs. The primary reason for requesting this alternative is to eliminate unnecessary thermal cycles in the RCS Cold Leg Safety Injection (SI) piping. A periodic thermal transient was identified in the RCS Cold Leg SI piping after post-refueling heat-up since approximately 1999. These transients coincide with the testing of the RCS PIVs, which causes the inlet check valves (XVC08998A-SI, XVC08998B-SI, and XVC08998C-SI) to open during this portion of testing, allowing cooler Volume Control Tank (VCT) temperature water into the SI piping.

These thermal transients, identified by the plant thermal cycle counting software, are counted against allowable fatigue usage totals for the affected piping system. For the RCS Cold Leg SI lines, the approximate fatigue usage is at 70% of the allowable. As a result of the high cumulative usage factor, additional ultrasonic inspections of the welds and elbows of the RCS Cold Leg SI lines A, B, and C in areas susceptible to thermal stratification were performed during refueling outage RF-21 in April 2014, with acceptable

Serial No.23-326 Docket No. 50-395 Attachment 2 RR-5-V2: Page 6 of 20 exam results. The proposed extended test intervals would reduce the frequency and, therefore, the impact of injecting ECCS water into the RCS during testing.

An additional reason for requesting this alternative is dose reduction to conform with Nuclear Regulatory Commission (NRC) and industry As Low As Reasonably Achievable (ALARA) radiation dose principles. A review of recent historical data identified that PIV testing results in a total personnel dose of approximately 0.3 Roentgen Equivalent Man (REM) each RFO.

NUREG-0933, Resolution of Generic Safety Issues, Section 3, Issue 105, Interfacing Systems LOCA at LWRs, discussed the need for PIV leak rate testing based primarily on three pre-1985 historical failures of applicable valves industry-wide. These failures all involved human errors in either operations or maintenance. None of these failures involved inservice equipment degradation. The performance of PIV leak rate testing provides assurance of acceptable seat leakage with the valve in a closed condition.

For check valves, functional testing is accomplished in accordance with ASME OM Code Mandatory Appendix 11, Check Valve Condition Monitoring Program. For power-operated valves, full stroke functional testing is accomplished in accordance with the ASME OM Code paragraph ISTC-3521, Category A and Category B Valves. The functional testing of the PIV check valves will be monitored through a Condition Monitoring Plan in accordance with ISTC-5222, Condition -Monitoring Program, and Mandatory Appendix II, Check Valve Condition Monitoring Program. Performance of the separate two-year PIV leak rate testing does not contribute any additional assurance of functional capability but rather provides added assurance of valve integrity, thereby reducing the probability of gross valve failure and consequent intersystem LOCA.

The use of a Condition Monitoring Plan is intended to align the frequency for the closure exercise testing with the pressure isolation valve test. By use of a Condition Monitoring Plan, the check valve closure test, based on performance, would be verified concurrently with the PIV seat leakage test. The frequency of the check valve closure test would then be the same as the PIV seat leakage test since closure performance and seat leakage performance are linked. The PIV seat leakage test would not pass if the valve failed to close. Pursuant to 10 CFR 50.55a, Codes and standards, paragraph 50.55a(z)(1 ), an alternative to the requirement of ASME OM Code Subsection ISTC-3630(a) is requested.

The basis of the request is that the proposed alternative would provide an acceptable level of quality and safety.

5.0 PROPOSED ALTERNATIVE AND ASSESSMENT Proposed Alternative VCSNS proposes to perform testing of the PIVs and check valves XVC08703A/B-RH at intervals ranging from every refueling outage (RFO) to every fourth refueling outage. The specific interval for each valve would be a function of its performance and would be established in a manner consistent with the CIV extended test eligibility process guidance under 10 CFR 50, Appendix J, Option B. Performance-based scheduling of PIVs and the

Serial No.23-326 Docket No. 50-395 Attachment 2 RR-5-V2: Page 7 of 20 check valves testing will be controlled in a manner similar to the methods described in NEI 94-01, Revision 3-A. PIV 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 consecutive cycles may have their test interval extended up to 75-months, with a permissible extension (for non-routine emergent conditions) of nine months (84 months total).

A conservative control will be established such that if any valve fails the PIV test, the test interval will be reduced consistent with Appendix J, Option B, requirements. Leakage rates less than the leakage limits found in TS and VCSNS procedure STP-215.008, SI and RHR System Valve Leakage Test, shall be considered acceptable. Any PIV leakage test failure would require the associated component to return to the initial test interval of every RFO or two years until acceptable performance is re-established.

Assessment The primary justification for this proposed alternative is the historically good performance of the PIVs and the check valves.

Tables 2 and 3 below present historical test data that demonstrates acceptable PIV performance for the Residual Heat Removal (RHR) and Safety Injection (SI) systems.

Individual testing of PIVs is performed for the purposes of identifying leakage and when troubleshooting is required. Group testing of PIVs is performed where such capability exists. Group testing is more conservative, in that, the same limit is applied when testing a single valve or group consisting of multiple valves. The comments sections in the tables below delineate the manner of testing performed.

Table 4 presents historical data that demonstrates acceptable check valve performance for the RHR Header Bypass Check Valves XVC08703A/B-RH. These check valves are tested in parallel with the inner RHR Inlet Isolation valves 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.

The functional capability of the motor-operated valves (MOVs) included within this alternative request is demonstrated by the full exercise test and stroke time testing (both the open and close directions) performed at a cold shutdown frequency in accordance with ASME OM Code. Additionally, the MOVs are position indication tested at a biennial frequency in accordance with ASME OM Code, paragraph ISTC-3700, and satisfying the requirements of 10 CFR 50.55a(b)(3)(xi). These tests are separate and distinct from the leakage determining function, which PIV testing demonstrates.

For the check valves, the functional capability included within this alternative request is demonstrated by the open and close exercise performed in accordance with ASME OM Code, Appendix II, paragraph ll-4000(b), Optimization of Condition-Monitoring Frequencies. The Condition Monitoring Plans for the check valves currently include open verification testing performed at least every third RFO. Additionally, leak testing is

Serial No.23-326 Docket No. 50-395 Attachment 2 RR-5-V2: Page 8 of 20 currently performed at least every third RFO and credited with confirming closure of the check valves.

Note that NEI 94-01, Revision 3-A [8.9], is not the sole basis for this alternative request, given that NEI 94-01, Revision 3-A [8.9], does not address seat leakage testing with water. Instead, NEI 94-01 was cited as an approach similar to the requested alternative method and provides reasonable assurance of continued PIV operational readiness. If the proposed alternative is authorized and the valves exhibit good performance, the PIV test frequency will be controlled similar to the method described in NEI 94-01, Revision 3-A [8.9], so that testing of these PIVs and check valves would not be required each refueling outage.

The extension of test frequencies proposed is consistent with the guidance provided in 10 CFR 50, Appendix J, Type C leak rate tests as detailed in NEI 94-01, Revision 3-A

[8.9], Paragraph 10.2.3.2, Extended Test Interval, which states:

"Test intervals for Type C valves may be increased based upon completion of two consecutive periodic as-found Type C tests where the result of each test is within a licensee's allowable administrative limits. Elapsed time between the first and last tests in a series of consecutive passing tests used to determine performance shall be 24 months or the nominal test interval (e.g., refueling cycle) for the valve prior to implementing Option B to Appendix J. Intervals for Type C testing may be increased to a specific value in a range of frequencies from 30 months up to a maximum of 75 months. Test intervals for Type C valves should be determined by a licensee in accordance with Section 11.0."

Additional justifications for NRC approval of this proposed alternative are:

  • There is a low likelihood of valve mis-positioning during power operations (e.g.,

alignment and valve position verification procedures, interlocks).

  • Relief valves in the low pressure (LP) piping may not provide inter-system LOCA (ISLOCA) mitigation for inadvertent PIV mis-positioning, but their relief capacity can accommodate conservative PIV seat leakage rates.
  • Alarms are provided that identify high pressure (HP) to LP leakage. Operators are trained to recognize symptoms of a present ISLOCA and to take appropriate actions.

If this proposed alternative is authorized and the PIVs and the two check valves XVC08703A/B-RH continue to exhibit good performance, the test frequency for these valves could be extended such that testing would not be required each RFO. Instead, testing would be conducted at an interval not to exceed every 75-months, with a permissible extension (for non-routine emergent conditions) of nine months (84 months total).

Based on valve performance history, there is continued assurance of valve operational readiness, as required by ASME OM-2020 Code, paragraph ISTC-3630. Therefore, this proposed alternative to extend the testing frequency will continue to provide assurance

Serial No.23-326 Docket No. 50-395 Attachment 2 RR-5-V2: Page 9 of 20 of the valves' operational readiness and provides an acceptable level of quality and safety pursuant to 10 CFR 50.55a(z)(1 ).

Table 2- Historical Leak Rate Test Performance for RHR PIVs 12/5/2012 0.242 5/29/2014 0.23 XVG08701A-RH 11/30/2015 0.16 5 Individual Leak Rate 5/31/2017 0.16 11/21/2018 0.18 5/17/2023 2.64 12/5/2012 0.62 5/29/2014 0.29 XVG08701 B-RH 11/30/2015 0.77 5 Individual Leak Rate 5/31/2017 0.21 11/21/2018 0.18 5/17/2023 0.649 12/5/2012 0.72 5/29/2014 0.32 XVG08702A-RH 11/30/2015 0.0 5 Individual Leak Rate 5/31/2017 0.04 11/21/2018 0.0 5/17/2023 0.0 12/5/2012 1.14 5/29/2014 0.32 XVG08702B-RH 11/30/2015 0.93 5 Individual Leak Rate 5/31/2017 0.76 11/21/2018 0.96 5/17/2023 0.836 Note 1: For each of the valves listed in Table 2 with an Allowable Leakage Limit of 5 gallons per minute (gpm), a conservative, truncated limit of 3.8 gpm is used to determine PIV valve operability. The leakage value of 3.8 gpm is based on the mid-range flow meter maximum recordable value within the instrument's calibrated range.

Serial No.23-326 Docket No. 50-395 Attachment 2 RR-5-V2: Page 10 of 20 Table 3 - Historical Leak Rate Test Performance for SI PIVs 5/29/2014 0.5 XVC08948A-S I 11/30/2015 0.0 5 Individual Leak Rate 5/31/2017 0.3 11/21/2018 0.15 5/17/2023 0.0 12/5/2012 0.17 5/29/2014 3.3 XVC08948B-SI 11/30/2015 0.11 5 Individual Leak Rate 5/31/2017 0.35 11/21/2018 0.16 5/17/2023 2.6 12/5/2012 0.2 5/29/2014 2.4 XVC08948C-S I 11/30/2015 0.15 5 Individual Leak Rate 5/31/2017 0.15 11/21/2018 0.22 5/17/2023 0.35 12/5/2012 0.13 5/29/2014 0.1 XVC08956A-SI 11/30/2015 0.0 5 Individual Leak Rate 5/31/2017 0.13 11/21/2018 0.12 5/17/2023 0.12 12/5/2012 0.13 5/29/2014 0.1 XVC08956B-SI 11/30/2015 0.13 5 Individual Leak Rate 5/31/2017 0.1 11/21/2018 0.13 5/17/2023 0.12 12/5/2012 0.12 5/29/2014 0.5 XVC08956C-SI 11/30/2015 0.11 5 Individual Leak Rate 5/31/2017 0.12 11/21/2018 0.13 5/17/2023 0.12

Serial No.23-326 Docket No. 50-395 Attachment 2 RR-5-V2: Page 11 of 20 Table 3 - Historical Leak Rate Test Performance for SI PIVs - (continued 1 of 7) 5/29/2014 0.42 XVC08973A-S I 11/30/2015 0.34 3 Individual Leak Rate 5/31/2017 0.17 11/21/2018 1.01 5/17/2023 0.82 12/5/2012 0.82 5/29/2014 0.44 11/30/2015 0.38 XVC089738-SI 3 Individual Leak Rate 5/31/2017 0.3 11/21/2018 0.59 5/17/2023 1.1 12/5/2012 0.2 5/29/2014 0.37 11/30/2015 0.4 XVC08973C-S I 3 Individual Leak Rate 5/31/2017 0.23 11/21/2018 0.21 5/17/2023 0.62 12/5/2012 0.38 5/29/2014 0.24 11/30/2015 0.17 XVC08974A-SI 5 Individual Leak Rate 5/31/2017 0.0 11/21/2018 0.0 5/17/2023 0.52 12/5/2012 0.61 5/29/2014 0.23 11/30/2015 0.16 XVC089748-S I 5 Individual Leak Rate 5/31/2017 0.0 11/21/2018 0.0 5/17/2023 0.52

Serial No.23-326 Docket No. 50-395 Attachment 2 RR-5-V2: Page 12 of 20 Table 3 - Historical Leak Rate Test Performance for SI PIVs - (continued 2 of 7)

Group Leak Rate (8 valves:

12/5/2012 0.21 XVC08988A/B-SI; XVC08990A/B/C-SI; XVC08992A/B/C-S I)

Group Leak Rate (5 valves:

5/29/2014 0.93 XVC08988A/B-SI; XVC08990A/B/C-SI) 1113012015 0.96 Group Leak Rate (2 valves:

XVC08988A-SI 3 XVC08988A/B-SI)

Group Leak Rate (8 valves:

5/31/2017 0.0 XVC08988A/B-S1; XVC08990A/B/C-SI; XVC08992A/B/C-SI) 11/21/2018 0.84 Group Leak Rate (5 valves:

5/17/2023 0.39 XVC08988A/B-SI; XVC08990A/B/C-SI)

Group Leak Rate (8 valves:

12/5/2012 0.21 XVC08988A/B-SI; XVC08990A/8/C-SI; XVC08992A/8/C-S I)

Group Leak Rate (5 valves:

5/29/2014 0.93 XVC08988A/B-S I; XVC08990A/B/C-S I) 1113012015 0.96 Group Leak Rate (2 valves:

XVC089888-SI 3 XVC08988A/B-S I)

Group Leak Rate (8 valves:

5/31/2017 0.0 XVC08988A/B-SI; XVC08990A/B/C-SI; XVC08992A/B/C-SI) 11/21/2018 0.84 Group Leak Rate (5 valves:

5/17/2023 0.39 XVC08988A/B-SI; XVC08990A/B/C-SI)

Serial No.23-326 Docket No. 50-395 Attachment 2 RR-5-V2: Page 13 of 20 Table 3 - Historical Leak Rate Test Performance for SI PIVs - (continued 3 of 7)

Group Leak Rate (8 valves:

12/5/2012 0.21 XVC08988A/B-SI; XVC08990A/B/C-SI; XVC08992A/B/C-S I)

Group Leak Rate (5 valves:

5/29/2014 0.93 XVC08988A/B-S I; XVC08990A/B/C-SI) 1113012015 0.1 Group Leak Rate (3 valves:

XVC08990A-SI 1 XVC08990A/B/C-SI)

Group Leak Rate (8 valves:

5/31/2017 0.0 XVC08988A/B-SI; XVC08990A/B/C-SI; XVC08992A/B/C-SI) 11/21/2018 0.84 Group Leak Rate (5 valves:

5/17/2023 0.39 XVC08988A/B-SI; XVC08990A/B/C-SI)

Group Leak Rate (8 valves:

12/5/2012 0.21 XVC08988A/B-SI; XVC08990A/B/C-SI; XVC08992A/B/C-SI)

Group Leak Rate (5 valves:

5/29/2014 0.93 XVC08988A/B-S1; XVC08990A/8/C-SI)

Group Leak Rate (3 valves:

XVC089908-SI 11/30/2015 0.1 1 XVC08990A/B/C-S I)

Group Leak Rate (8 valves:

5/31/2017 0.0 XVC08988A/B-SI; XVC08990A/B/C-SI; XVC08992A/B/C-SI) 11/21/2018 0.84 Group Leak Rate (5 valves:

XVC08988A/B-SI; 5/17/2023 0.39 XVC08990A/B/C-S I)

Serial No.23-326 Docket No. 50-395 Attachment 2 RR-5-V2: Page 14 of 20 Table 3 - Historical Leak Rate Test Performance for SI PIVs - (continued 4 of 7)

Group Leak Rate (8 valves:

12/5/2012 0.21 XVC08988A/B-SI; XVC08990A/B/C-S I; XVC08992A/B/C-SI)

Group Leak Rate (5 valves:

5/29/2014 0.93 XVC08988A/B-SI; XVC08990A/B/C-S I) 0.1 Group Leak Rate (3 valves:

XVC08990C-SI 11/30/2015 1 XVC08990A/B/C-S I)

Group Leak Rate (8 valves:

5/31/2017 0.0 XVC08988A/B-SI; XVC08990A/B/C-SI; XVC08992A/B/C-SI) 11/21/2018 0.84 Group Leak Rate (5 valves:

5/17/2023 0.39 XVC08988A/B-SI; XVC08990A/B/C-SI)

Group Leak Rate (8 valves:

12/5/2012 0.21 XVC08988A/B-SI; XVC08990A/B/C-SI; XVC08992A/B/C-SI) 5/29/2014 0.86 Group Leak Rate (2 valves:

XVC08992A/C-S I) 11/30/2015 0.38 Group Leak Rate (3 valves:

XVC08992A-SI 1 XVC08992A/B/C-S I)

Group Leak Rate (8 valves:

5/31/2017 0.0 XVC08988A/B-SI; XVC08990A/B/C-SI; XVC08992A/B/C-SI) 11/21/2018 0.71 Group Leak Rate (3 valves:

5/17/2023 0.66 XVC08992A/B/C-SI)

Serial No.23-326 Docket No. 50-395 Attachment 2 RR-5-V2: Page 15 of 20 Table 3 - Historical Leak Rate Test Performance for SI PIVs - (continued 5 of 7)

}I:, /
  • :: £\* ...

~~*

'*c""

I

}

ii.:

./'

'>(}

if::

,;,rtr .;

/'*
*.:; < :*J/i' J;
{**
.:*:'.; ::,;.f'),:. .., .. :.+.*

I i: t: . /:;.

11.1~~'l.* .., ..

'\

,} **;.r/~:. :}:

... .*;,:)

'.d:..._:
    • 7:

oJ'i; tt::

.c::;:

.}l

*)

      • 11*I

.**i~li\il:* *::l~\/

    • .i. .'.'";
.*:c::.*:,.'.
  • .**; c.

,, . . .:r j:? ,c;/:l@st

:* *.*. ***.::. .{.,;',:*ii .\f  ;., ** .: ,>~ JI I
    • *"*. ** * *"*IO;-*,,,,._.,,, _

_'.. >-> ~"<-:>

  • ~*'"
/;'.t\? .;: :;-; ;  :<. :.  ;. *';*.:". .-,::; .. ;;<< *:.  ; ;><'. :* J. h:  : ;c
  • J\;: (( ./;;;;;: .*'::: s?f,;. .,.. ,*,: ,.,-_ ..,_.,\ .** ,;,, _:,:; )*-?*'*":.,: 'Ct>, ','i **?~ C/\ ,. : ::: .0/::

Group Leak Rate (8 valves:

12/5/2012 0.21 XVC08988A/B-SI; XVC08990A/B/C-S I; XVC08992A/B/C-SI) 5/29/2014 0.41 Individual Leak Rate 11/30/2015 0.38 Group Leak Rate (3 valves:

XVC08992B-SI 1 XVC08992A/B/C-SI)

Group Leak Rate (8 valves:

5/31/2017 0.0 XVC08988A/B-SI; XVC08990A/B/C-S I; XVC08992A/B/C-S I) 11/21/2018 0.71 Group Leak Rate (3 valves:

5/17/2023 0.66 XVC08992A/B/C-SI)

Group Leak Rate (8 valves:

12/5/2012 0.21 XVC08988A/B-SI; XVC08990A/B/C-SI; XVC08992A/B/C-SI) 5/29/2014 0.86 Group Leak Rate (2 valves:

XVC08992A/C-S I)

Group Leak Rate (3 valves:

XVC08992C-SI 11/30/2015 0.38 1 XVC08992A/B/C-SI)

Group Leak Rate (8 valves:

5/31/2017 0.0 XVC08988A/B-SI; XVC08990A/B/C-SI; XVC08992A/B/C-S I) 11/21/2018 0.71 Group Leak Rate (3 valves:

5/17/2023 0.66 XVC08992A/B/C-SI)

. ' .. -c*v ,,-_-, *- ,*,v --** . .. . .. .. ....

12/5/2012 0.97 5/29/2014 0.41 11/30/2015 0.9 Group Leak Rate (3 valves:

XVC08993A-SI 3 5/31/2017 0.86 XVC08993A/B/C-SI) 11/21/2018 1.5 5/17/2023 1.4

Serial No.23-326 Docket No. 50-395 Attachment 2 RR-5-V2: Page 16 of 20 Table 3 - Historical Leak Rate Test Performance for SI PIVs - (continued 6 of 7) 5/29/2014 0.41 1113012015 Group Leak Rate (3 valves:

XVC08993B-SI 1--------+------1

o. 9 3 XVC08993A/B/C-SI) 5/31/2017 0.86 11/21/2018 1.5

--- J' --v -- -, ,-- .,* ,,.. -,

5/17/2023 1.4

,. ,,. -~*- ,... ___,.,

12/5/2012 0.97 5/29/2014 0.41 11130120 15 09 Group Leak Rate (3 valves:

XVC08993C-S I 1--- - - - - - - + - - --*- - - - 1 3 5/31/2017 0.86 XVC08993A/B/C-SI) 11/21/2018 1.5 5/17/2023 1.4 12/5/2012 0.72 5/29/2014 0.45 Group Leak Rate (6 valves:

XVC08995A-S I 1--1_1_/3_0/_2_01_5_ _ _0_._16_----1 XVC08995A/B/C-SI; 1

5/31/2017 0.42 XVC08997 A/B/C-SI) 11/21/2018 0.41 5/17/2023 0.02 12/5/2012 0.72 5/29/2014 0.45 Group Leak Rate (6 valves:

XVC08995B-SI 1--1_1_/3_0_/2_0_15_ _ _0_._16_---1 1 XVC08995A/B/C-SI; 5/31/2017 0.42 XVC08997 A/B/C-S I) 11/21/2018 0.41 5/17/2023 0.02 12/5/2012 0. 72 5/29/2014 0.45 Group Leak Rate (6 valves:

XVC08995C-S I 1--1_1_/3_0_/2_0_15_ _ _0_._16_---1 1 XVC08995A/B/C-SI; 5/31/2017 0.42 XVC08997 A/B/C-SI) 11/21/2018 0.41 5/17/2023 .,

0.02 12/5/2012 0.72 5/29/2014 0.45 Group Leak Rate (6 valves:

XVC08997 A-SI _1_1_/3_0_/2_0_15_ _ _0_._16_---; 1 XVC08995A/B/C-SI; 5/31/2017 0.42 XVC08997 A/B/C-SI) 11 /21/2018 0 .41 5/17/2023 0.02

Serial No.23-326 Docket No. 50-395 Attachment 2 RR-5-V2: Page 17 of 20 Table 3 - Historical Leak Rate Test Performance for SI PIVs - (continued 7 of 7) 5/29/2014 0.45 Group Leak Rate (6 valves:

11/30/2015 0.16 XVC089978-SI 1 XVC08995A/B/C-S I; 5/31/2017 0.42 XVC08997 A/B/C-SI) 11/21/2018 0.41 5/17/2023 0.02 12/5/2012 0.72 5/29/2014 0.45 Group Leak Rate (6 valves:

11/30/2015 0.16 XVC08997C-SI 1 XVC08995A/B/C-SI; 5/31/2017 0.42 XVC08997A/8/C-SI) 11/21/2018 0.41 5/17/2023 0.02 12/5/2012 1.0 5/29/2014 0.29 11/30/2015 0.88 XVC08998A-SI 3 Individual Leak Rate 5/31/2017 0.96 11/21/2018 1.07 5/17/2023 1.34 12/5/2012 0.34 5/29/2014 0.9 11/30/2015 0.91 XVC08998B-SI 3 Individual Leak Rate 5/31/2017 0.2 11/21/2018 0.77 5/17/2023 1.1 12/5/2012 0.58 5/29/2014 0.32 11/30/2015 0.41 XVC08998C-S I 3 Individual Leak Rate 5/31/2017 0.41 11/21/2018 0.29 5/17/2023 0.63 Note 2: For each of the valves listed in Table 3 with an Allowable Leakage Limit of 5 gallons per minute (gpm), a conservative, truncated limit of 3.8 gpm is used to determine PIV valve operability. The leakage value of 3.8 gpm is based on the mid-range flow meter maximum recordable value within the instrument's calibrated range.

Serial No.23-326 Docket No. 50-395 Attachment 2 RR-5-V2: Page 18 of 20 Table 4: Historical Leak Rate Test Performance for RHR Header Bypass Check Valves 12/5/2012 -0.30*

5/29/2014 0.00 Combined Leak Rate 11/30/2015 0.11 XVC08703A-RH 3.8 (XVC08703A-RH and 5/31/2017 0.18 XVG08702A-RH) 11/21/2018 -0.13*

5/17/2023 -0.374*

12/5/2012 0.43 5/29/2014 0.93 11/30/2015 1.18 Combined Leak Rate XVC08703B-RH 3.8 (XVC08703B-RH and 5/31/2017 0.62 XVG08702B-RH) 11/21/2018 0.86 5/17/2023 1.32 Note 3: For each of the valves listed in Table 4, the Allowable Leakage Limit of 3.8 gpm is based on the mid-range flow meter maximum recordable value within the instrument's calibrated range.

Note *: The baseline leakage was more than the leakage measured through XVC08703A-RH and XVG08702A-RH in parallel. Baseline leakage is measured from the test header while XVC08703A-RH and XVG08702A-RH are isolated from the test header.

This value is later subtracted from the leakage measured when XVC08703A-RH and XVG08702A-RH are aligned to the test header. This gives the "combined leak rate." For the test performed on 12/5/2012, the baseline leakage was 1.10 gpm and leakage through XVC08703A-RH and XVG08702A-RH in parallel was 0.80 gpm. For the test performed on 11/21/2018, the baseline leakage was 0.81 gpm and leakage through XVC08703A-RH and XVG08702A-RH in parallel was 0.68 gpm. For the test performed on 5/17/2023, the baseline leakage was 1.2 and the leakage through XVC08703A-RH and XVG08702A-RH in parallel was 0.86 gpm. All are below the allowable leakage limit of 3.8 gpm.

6.0 DURATION OF PROPOSED ALTERNATIVE This relief request, upon approval, will be utilized during the VCSNS fifth (5 th ) lnservice Testing (1ST) Interval, which begins on January 1, 2025.

Serial No.23-326 Docket No. 50-395 Attachment 2 RR-5-V2: Page 19 of 20 7.0 PRECEDENTS The NRC has previously approved similar alternative requests for the fourth (4 th ) interval at VCSNS on the basis that the good performance and low risk factor supports the logical progression to a performance-based program. [8.2], [8.3] The NRC further concluded that the proposed alternative provided an acceptable level of quality and safety. The NRC has also previously approved similar alternative requests for other plants ([8.4], [8.5],

[8.6], [8.7], and [8.8]) to allow PIV testing under a performance-based testing approach similar to that established under 10 CFR 50, Appendix J, Option B.

8.0 REFERENCES

8.1 American Society of Mechanical Engineers (ASME), Operation and Maintenance (OM) Code, Operation and Maintenance of Nuclear Plants, 2020 Edition 8.2 ADAMS Accession No. ML18345A060, NRC Letter, "Virgil C. Summer Nuclear Station, Unit 1 - Relief Request Regarding Use of a Performance-Based Testing Frequency for Pressure Isolation Valves (RR-4-14) (EPID No. L-2018-LLR-0129)," December 17, 2018 8.3 ADAMS Accession No. ML20248H378, NRC Letter, "Virgil C. Summer Nuclear Station, Unit 1 -Alternative Request (RR-4-19, RR-4-21) Related to the lnservice Testing Program (EPIDS L-2020-LLR-0077 and L-2020-LLR-0078)," December 2, 2020 8.4 ADAMS Accession No. ML22265A180, NRC Letter, "River Bend Station, Unit 1 -

Proposed Alternative to the Requirements of ASME Code of Operation and Maintenance of Nuclear Power Plants for Pressure Isolation Valve Testing Frequency (EPID L-2021-LLR-0090)," September 27, 2022.

8.5 ADAMS Accession No. ML21294A067, NRC Letter, "Grand Gulf Nuclear Station, Unit 1 - lnservice Testing Program Relief Request VRR-GGNS-2021-1, Alternative Request for Pressure Isolation Valve Testing Frequency (EPID L-2021-LLR-0040)," October 28, 2021 8.6 ADAMS Accession No. ML20174A545, NRC Letter, "Monticello Nuclear Generating Plant - Request for Alternative for Pressure Isolation Valve Testing (EPID L-2020-LLR-0006)," July 15, 2020 8.7 ADAMS Accession No. ML19228A195, NRC Letter, "Limerick Generating Station, Units 1 and 2- Safety Evaluation of Relief Requests GVRR-8, 11-PRR-1, 90-PRR-1 and 47-VRR-2 Regarding the Fourth 10-Yer Interval of the lnservice Testing Program (EPID L-2018-LLR-0384, EPID L- 2018-LLR-0384, EPID L-2018-LLR-0386, and EPID L-2018-LLR-0387)," October 28, 2019

Serial No.23-326 Docket No. 50-395 Attachment 2 RR-5-V2: Page 20 of 20 8.8 ADAMS Accession No. ML19217A306, NRC Letter, "LaSalle County Station, Units 1 and 2 - Request from the Requirements of the ASME Code Related to Pressure Isolation Valve Testing Frequency (EPID L-2019-LLR-0062)," September 10, 2019 8.9 ADAMS Accession No. ML12221A202, NEI 94-01, Revision 3-A, "Industry Guideline For Implementing Performance-Based Option of 10 CFR Part 50, Appendix J", July 2012

Serial No.23-326 Docket No. 50-395 Attachment 3 Alternative Request RR-5-P1 Charging/Safety Injection Pumps Virgil C. Summer Nuclear Station (VCSNS) Unit 1 Dominion Energy South Carolina, Inc. {DESC)

Serial No.23-326 Docket Nos. 50-395 Attachment 3 RR-5-P1: Page 2 of 7 Alternative Request RR-5-P1 Charging/Safety Injection Pumps Pursuant to 10 CFR 50.55a(z)(1) 1.0 ASME CODE COMPONENTS AFFECTED Three (3) Charging/Safety Injection (SI) centrifugal Group A pumps, XPP0043A, XPP0043B, and XPP0043C, shown in Table 1 below, are included in this alternative request (AR). These pumps are routinely used for normal plant operation, providing charging and seal injection flow.

Table 1 - ASME Code Components XPP0043A Charging/SI Pump A 2 A XPP0043B Charging/SI Pump B 2 A XPP0043C Charging/SI Pump C 2 A 2.0 APPLICABLE CODE EDITION AND ADDENDA American Society of Mechanical Engineers (ASME), Operation and Maintenance (OM)

Code, Operation and Maintenance of Nuclear Plants, 2020 Edition [8.1].

3.0 APPLICABLE CODE REQUIREMENT ASME OM Code Subsection ISTB-3000, General Testing Requirements, states in part, that, The parameters to be measured during preservice and inservice testing are specified in Table ISTB-3000-1."

ASME OM Code Table ISTB-3000-1, lnservice Test Parameters, specifies in part that, Flow Rate (Q) is required to be measured during Group A pump tests.

ASME OM Code Subsection ISTB-3300(e)(2), Reference Values, states that "Reference values shall be established at the comprehensive pump test flow rate for the Group A and Group B tests, if practicable. If not practicable, the reference point flow rate shall be established at the highest practical flow rate."

ASME OM Code Subsection ISTB-3400, Frequency of lnservice Tests, states in part that, "An inservice test shall be run on each pump as specified in Table ISTB-3400-1."

Serial No.23-326 Docket No. 50-395 Attachment 3 RR-5-P 1: Page 3 of 7 ASME OM Code Table ISTB-3400-1, lnservice Test Frequency, specifies in part that Group A pumps are to be tested quarterly.

ASME OM Code Subsection ISTB-351 0(a), Accuracy, states in part that, "Instrument accuracy shall be within the limits of Table ISTB-3510-1. If a parameter is determined by analytical methods instead of measurement, then the determination shall meet the parameter accuracy requirement of Table ISTB-3510-1 (e.g., flow rate determination shall be accurate to within +/-2% of actual)."

ASME OM Code Table ISTB-3510-1, Required Instrument Accuracy, specifies in part that when measuring Flow Rate, the required instrument accuracy is +/-2% for Group A Tests.

ASME OM Code Subsection ISTB-3550, Flow Rate, states in part, "When measuring flow rate, a rate or quantity meter shall be installed in the pump test circuit. If a meter does not indicate the flow rate directly, the record shall include the method used to reduce the data. Internal recirculated flow is not required to be measured."

ASME OM Code Subsection ISTB-51 00(a)(1 ), Duration of Tests, states that, "For the Group A test and the comprehensive test, after pump conditions are as stable as the system permits, each pump shall be run at least 2 min. At the end of this time at least one measurement or determination of each of the quantities required by Table ISTB-3000-1 shall be made and recorded."

ASME OM Code Subsection ISTB-51 00(b)(1 ), Bypass Loops, states that "A bypass test loop may be used for a Group A test or comprehensive test, provided the flow rate through the loop meets the requirements as specified in ISTB-3300."

ASME OM Code Subsection ISTB-5121, Group A Test Procedure, details requirements for the conduct of pump inservice testing and evaluation/analysis of test results. ISTB-5121 (c) states that, "Where it is not practical to vary system resistance, flow rate and pressure shall be determined and compared to their respective reference values." ISTB-5121 (e) states in part that, "All deviations from the reference values shall be compared with the ranges of Table ISTB-5121-1 and corrective action taken as specified in ISTB-6200."

4.0 BACKGROUND

AND REASON FOR ALTERNATIVE REQUEST The test circuit used during the quarterly Group A Charging/SI Pump inservice test is described in VCSNS Updated Final Safety Analysis Report (UFSAR) [8.8] Section 6.3.2.2.4.2, Centrifugal Charging Pumps, and states, in part that, "A minimum flow bypass line is provided on each pump discharge to recirculate flow to the volume control tank after cooling via the seal water heat exchanger during normal plant operation," and, "during normal plant operation, at least one charging pump is continuously in service.

The second pump is a non-running pump on the inactive loop and the third, if available, is designated as a spare and its breaker(s) are racked out. The other charging pumps may be tested during power operation via the minimum flow bypass lines."

Serial No.23-326 Docket No. 50-395 Attachment 3 RR-5-P1: Page 4 of 7 The VCSNS Charging/SI system was constructed without installed flow measurement instrumentation in the Charging/SI minimum flow recirculation lines. During the second and third intervals, Charging/SI pump inservice testing was conducted in accordance with Generic Letter (GL) 89-04, Guidance on Developing Acceptable lnservice Testing Programs, Position 9 [8.2].

Prior to the start of the fourth interval, efforts were made to measure flow through the recirculation lines using ultrasonic flow meters. During the first 12-months of the fourth interval, strap-on ultrasonic flow meters were used to measure recirculation flow during Charging/SI Pump quarterly Group A testing. The required instrument repeatability established in ASME OM Code Table ISTB-3510-1 could not be achieved. During field use, flow rate variations of up to 6 percent and higher from average were noted.

Inaccuracies associated with clamp-on ultrasonic flow measurement devices were the subject of NRC Information Notice (IN) 95-08, "Inaccurate Data Obtained with Clamp-on Ultrasonic Flow Measurement Instruments" [8.3]

As such, based on the lack of consistency in data measurement using the ultrasonic meters and lack of installed instrumentation to measure recirculation line flow during Charging/SI Pump Group A testing, pursuant to 10 CFR 50.55a, Codes and standards, paragraph (z)(1 ), an alternative to the surveillance testing methodology of the ASME OM Code is requested.

5.0 PROPOSED ALTERNATIVE AND ASSESSMENT Proposed Alternative VCSNS proposes to continue use of the method identified in GL 89-04 [8.2] that was approved for the fourth (4 th ) interval as an alternative method for meeting the surveillance requirement for the fifth (5 th ) VCSNS 1ST interval, thereby maintaining an acceptable level of quality and safety. Performing inservice testing using a non-instrumented recirculation line was also previously found acceptable by NRC in GL 89-04, Position 9, Pump Testing using Minimum-flow Return Line With or Without Flow Measuring Devices [8.2].

Under the alternative approach, pump flow is measured during a comprehensive test each refueling outage with the minimum-flow line isolated. Pump performance is then compared to Design Basis Accident (OBA) analysis requirements.

The Group A pump quarterly test of the Charging/SI Pumps will be performed in accordance with GL 89-04 [8.2], Position 9, by measuring pump differential pressure and vibration. The Charging/SI Pump orifices are large differential pressure orifices, with backpressure having minimal effect on orifice performance.

Assessment Based on recirculation flow measurement data repeatability issues, an alternative to the requirement of the ASME OM Code to measure Charging/SI Pump recirculation line flow during quarterly Group A testing is requested. This test alternate is endorsed in Position

Serial No.23-326 Docket No. 50-395 Attachment 3 RR-5-P1: Page 5 of 7 9 of GL 89-04 [8.2]. The test methodology using Position 9 was used during previous test intervals at VCSNS. The Alternative was not requested prior to the 4th interval, as NUREG-1482, Revision Owas used during the third (3 rd ) ten-year interval update and did not require licensees to submit relief requests prior to utilizing GL 89-04, Position 9 [8.2].

GL 89-04 [8.2], Position 9 acknowledged that earlier (and current) inservice test Codes required pump differential pressure and flow rate to be measured and then evaluated together to determine pump hydraulic performance during testing. The GL states that "Certain safety-related systems are designed such that the minimum-flow return lines are the only flow paths that can be utilized for quarterly pump testing. Furthermore, some of these systems do not have a flow path that can be utilized for pump testing during any plant operating mode except the minimum-flow return lines. In these cases, pumping through the path designed for fulfilling the intended system safety function could result in damage to plant equipment. Minimum-flow lines are not designed for pump testing purposes, and few have installed flow measuring devices."

The GL goes on to state that, "In cases where flow can only be established through a non-instrumented minimum-flow path during quarterly pump testing and a path exists at cold shutdowns or refueling outages to perform a test of the pump under full or substantial flow conditions, the staff has determined that the increased interval is an acceptable alternative to the Code requirements provided that pump differential pressure, flow rate, and bearing measurements are taken during this testing and that quarterly testing also measuring at least pump differential pressure and vibration is continued. Data from both testing frequencies should be trended as required by (the Code)."

GL 89-04 [8.2] also references NRC Bulletin 88-04 [8.5] which advised licensees of the potential for pump damage while running pumps in the minimum-flow condition. The GL states that, "Licensees should ensure that if pumps are tested in the low flow condition, the flow is sufficient to prevent damage to the pump."

The acceptability of operation of VCSNS Charging/SI Pumps in the minimum-flow configuration has been evaluated [8.4]. While on minimum-flow, each pump will run at greater than 60 gallons per minute, regardless of which combination of pumps are operating. This is because the individual pump minimum-flow orifices govern the operating point for each pump. A stronger pump will have negligible impact on the operating point of the weaker pump since a slight increase in orifice backpressure will have minimal effect on orifice performance. This is true for the charging pump minimum-flow orifices which are large differential pressure orifices. The required minimum-flow of 60 gallons per minute is sufficient to prevent pump damage.

The large differential pressure orifices establish a fixed operating point for each Charging/SI Pump which allows testing under repeatable conditions, without the need to measure flow, as endorsed in GL 89-04, Position 9 [8.2]. Pump condition will be evaluated by trending pump differential pressure and vibration. Flow rate will be assumed to be fixed and at its reference value similar to the previous inservice testing interval. The Charging/SI Pumps also undergo comprehensive inservice testing during refueling outages. The minimum-flow lines are isolated and total flow is measured at substantial flow conditions as required by the ASME OM Code.

Serial No.23-326 Docket No. 50-395 Attachment 3 RR-5-P1: Page 6 of 7 NUREG-1482, Revision 3, Guidelines for lnservice Testing at Nuclear Power Plants, [8.7]

Section 3.1, NRG Recommendations and Guidance, states, in part that, "The recommendations herein replace the guidance and technical positions in GL 89-04. Note that specific relief is required to implement the guidance derived from GL 89-04.

However, relief justification may refer to the positions in GL 89-04 with clarifying information to clearly show how it would apply to a licensee's situation."

The proposed alternative is consistent with the guidelines provided in NUREG-1482, Section 5.9 and GL 89-04, Position 9. [8.7], [8.2] Using the provisions of this request provides a reasonable alternative to the Code requirements based on the determination that the proposed alternative will provide adequate indication of pump performance, permit detection of component degradation, and continue to provide an acceptable level of quality and safety. Therefore, pursuant to 10 CFR 50.55a(z)(1 ), VCSNS requests approval of this alternative to the specific ISTB requirements identified in this request.

6.0 DURATION OF PROPOSED RELIEF This alternative request, upon approval, will be utilized during the VCSNS fifth (5 th )

lnservice Testing (1ST) Interval, which begins on January 1, 2025.

7.0 PRECEDENTS NRC has previously approved a similar alternative request for the fourth (4 th ) interval at VCSNS on the basis that the application was consistent with the guidance in NUREG-1482, Section 5.9, Pump Testing Using Minimum Flow Return Lines With or Without Flow Measuring Devices, and GL 89-04, Guidance On Developing Acceptable lnservice Testing Program, Position 9, and concluded the proposed alternative provided an acceptable level of quality and safety. [8.6], [8.2] NRC also has previously approved similar alternatives for other plants, such as for the fourth (4 th ) and fifth (5 th ) intervals at Beaver Valley Power Station, Unit 1. [8.9], [8.1 O], [8.11]

8.0 REFERENCES

8.1 American Society of Mechanical Engineers (ASME), Operation and Maintenance (OM) Code, Operation and Maintenance of Nuclear Plants, 2020 Edition 8.2 ADAMS Accession No. ML031150259, NRC Generic Letter 89-04, "Guidance On Developing Acceptable lnservice Testing Program, April 3, 1989 8.3 ADAMS Accession No. ML031060366, Information Notice 1995-008, "Inaccurate Data Obtained with Clamp-On Ultrasonic Flow Measurement Instruments,"

January 30, 1995

Serial No.23-326 Docket No. 50-395 Attachment 3 RR-5-P1: Page 7 of 7 8.4 Westinghouse Letter CGE-87-776, from J. C. Snelson (Westinghouse) to R. B.

Clary (SCE&G), "South Carolina Electric & Gas Company Virgil C. Summer Nuclear Station Charging Pump Miniflow Assessment," November 16, 1987 8.5 NRC Bulletin 88-04, Potential Safety-Related Pump Loss, May 5, 1988 8.6 ADAMS Accession No. ML13295A020, NUREG 1482, Revision 2, "Guidelines for lnservice Testing at Nuclear Power Plants," October 31, 2013 8.7 ADAMS Accession No. ML20202A473, NUREG 1482, Revision 3, "Guidelines for lnservice Testing and Nuclear Power Plants," July 2020 8.8 VCSNS Updated Final Safety Analysis Report (UFSAR), Docket Number 50-395, Revision 23.02, updated on line November 2, 2023 8.9 ADAMS Accession No. ML070890491, Beaver Valley Unit 1, Requests Approval of Proposed Alternatives and Relief for lnservice Testing Program Ten-Year Update, March 28, 2007 8.10 ADAMS Accession No. ML17159A442, NRC Letter, "Beaver Valley Power Station, Unit 1 - Requests for Alternatives and Requests for Relief Re: Fifth 10-Year lnservice Testing Program Interval (CAC Nos. MF8332, MF8334, MF8336, MF8337, MF8340, MF8340, MF8342, MF8344, MF8346, MF8648, MF8350, MF8351, MF8353, MF8354, MF8355, and MF8357)," June 26, 2017 8.11 ADAMS Accession No. ML17255A508, NRC Letter, "Correction to the Safety Evaluation to Beaver Valley Power Station, Unit No. 1 - Requests for Alternatives and Requests for Relief Re: Fifth 10-Year lnservice Testing Program Interval (CAC Nos. MD8332 through MF8357)," September 19, 2017.