ML20248H378
| ML20248H378 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 12/02/2020 |
| From: | Markley M Plant Licensing Branch II |
| To: | Lippard G South Carolina Electric & Gas Co |
| References | |
| EPID L-2020-LLR-0077, EPID L-2020-LLR-0078 | |
| Download: ML20248H378 (10) | |
Text
December 2, 2020 Mr. George Lippard, III Vice President, Nuclear Operations South Carolina Electric & Gas Company Virgil C. Summer Nuclear Station P.O. Box 88, Mail Code 800 Jenkinsville, SC 29065
SUBJECT:
VIRGIL C. SUMMER NUCLEAR STATION, UNIT 1 - ALTERNATIVE REQUESTS RR 4-19 AND RR-4-21 RELATED TO THE INSERVICE TESTING PROGRAM (EPIDS L-2020-LLR-0077 AND L-2020-LLR-0078)
Dear Mr. Lippard:
By letter dated June 1, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20156A226), Dominion Energy South Carolina (DESC, the licensee) requested U.S. Nuclear Regulatory Commission (NRC) approval of alternatives, pursuant to Title 10, Energy, of the Code of Federal Regulations (10 CFR) 50.55a(z)(1), to the requirements of the American Society of Mechanical Engineers (ASME) Operation and Maintenance of Nuclear Power Plants, Division 1, OM Code: Section IST (OM Code) associated with the inservice testing (IST) frequency of certain valves at the Virgil C. Summer Nuclear Station (VCSNS) Unit 1.
Specifically, pursuant to subparagraph (1) in paragraph (z), Alternatives to codes and standards requirements, of Section 55a, Codes and standards, in Part 50, Domestic Licensing of Production and Utilization Facilities, in 10 CFR 50.55a(z)(1), the licensee requested to implement proposed alternatives RR-4-19 and RR-4-21 on the basis that the alternatives provide an acceptable level of quality and safety.
The NRC staff has reviewed requests RR-4-19 and RR-4-21 and concludes that the proposed alternatives provide an acceptable level of quality and safety for the components listed in Table 1 and Table 2 of this safety evaluation. Therefore, the NRC staff authorizes the use of alternative requests RR-4-19 and RR-4-21 for VCSNS until the end of the fourth IST Program interval, which is scheduled to end on December 31, 2023.
G. Lippard All other ASME OM Code requirements as incorporated by reference in 10 CFR 50.55a for which relief from, or an alternative to, was not specifically requested and approved in this subject request remain applicable.
If you have any questions, please contact the Project Manager, Karen Cotton-Gross at karen.cotton@nrc.gov.
Sincerely, Michael Markley, Chief Plant Licensing Branch 2-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-395
Enclosure:
Safety Evaluation cc: ListServ Michael T.
Markley Digitally signed by Michael T. Markley Date: 2020.12.02 14:42:31
-05'00'
- Concurred by SE OFFICE NRR/DORL/LPL2-1/PM NRR/DORL/LPL2-1/LA NRR/DEX/EMIB/BC NRR/DORL/LPL2-1/BC NAME KCotton KGoldstein ABuford*
MMarkley DATE 09/04/2020 09/08/2020 07/15/2020 12/2/2020
Enclosure SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION ALTERNATIVE REQUESTS RR-4-19 AND RR-4-21 RELATED TO THE INSERVICE TESTING PROGRAM DOMINION ENERGY SOUTH CAROLINA VIRGIL C. SUMMER NUCLEAR STATION UNIT 1 DOCKET NO. 50-395
1.0 INTRODUCTION
By letter dated June 1, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20156A226), Dominion Energy South Carolina (DESC, the licensee) requested U.S. Nuclear Regulatory Commission (NRC) approval of an alternative, pursuant to Title 10, Energy, of the Code of Federal Regulations (10 CFR) 50.55a(z)(1), to the requirements of the American Society of Mechanical Engineers (ASME) Operation and Maintenance of Nuclear Power Plants, Division 1, OM Code: Section IST (OM Code) associated with the inservice testing (IST) frequency of certain valves at the Virgil C. Summer Nuclear Station (VCSNS) Unit 1.
Specifically, pursuant to subparagraph (1) in paragraph (z), Alternatives to codes and standards requirements, of Section 55a, Codes and standards, in Part 50, Domestic Licensing of Production and Utilization Facilities, in Title 10, Energy, of the Code of Federal Regulations (10 CFR 50.55a(z)(1)), the licensee requested to implement proposed alternatives RR-4-19 and RR-4-21 on the basis that the alternatives provide an acceptable level of quality and safety.
2.0 REGULATORY EVALUATION
The regulations in 10 CFR 50.55a(f)(4), Inservice testing standards requirement for operating plants, states, 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 ASME OM Code must meet the IST 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 (f)(2) and (3) of 10 CFR 50.55a and that are incorporated by reference in 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 regulations in 10 CFR 50.55a(z) states, in part, that alternatives to the requirements of paragraphs (b) through (h) of 10 CFR 50.55a may be used, when authorized by the NRC, if the licensee demonstrates (1) the proposed alternative would provide an acceptable level of quality and safety; or (2) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
3.0 TECHNICAL EVALUATION
3.1 Applicable ASME OM Code Edition and Addenda The licensee proposes an alternative test plan in lieu of certain IST requirements of the 2004 Edition through the 2006 Addenda of the ASME OM Code for the IST Program at VCSNS, Unit 1.
Duration of the proposed alternative is for the fourth 10-year interval, which commenced on January 1, 2014, and is currently scheduled to end on December 31, 2023.
3.2 Licensees Alternative Request RR-4-19 ASME OM Code Requirements 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 Owners 10 CFR 50, Appendix J program, shall be tested to verify their seat leakages [are] 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(a), Frequency, states Tests shall be conducted at least once every 2 years.
Alternative testing is requested for the following valves:
Table 1 IST Program Valve ID IST Program Description Code Class OM Code Category XVC08703A-RH RH Header A Bypass Check Valve (IRC) 2 A/C XVC08703B-RH RH Header B Bypass Check Valve (IRC) 2 A/C The licensees request states, in part, that ASME OM Code, Subsection ISTC-3630(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.
The licensee previously submitted a request to use a performance-based testing frequency for certain pressure isolation valves (PIVs), with intervals ranging from every refueling outage (RFO) to every third RFO, not to exceed 60 months (ADAMS Accession No. ML18282A046).
This interval 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. The NRC approved this request (ADAMS Accession No. ML18345A060), which included valves XVG08701A/B-RH and XVG08702A/B-RH. These valves, the Residual Heat Removal (RHR) header isolation valves, are 12-inch, motor operated, active gate valves located in the RHR inlet line from the Reactor Coolant (RC) hot legs.
The licensees proposed alternative is to include two check valves, XVC08703A/B-RH, RHR Header Bypass Check Valves, in the previously approved performance-based testing frequency program discussed above. These valves are 3/4-inch check valves located in bypass lines around the inner RHR System Inlet Isolation valves, XVG08702A/B-RH. The purpose of these check valves is to open to relieve any pressure buildup in the piping between the XVG08701A/B-RH and XVG08702A/B-RH and to close to prevent pressure/flow from bypassing XVG08702A/B-RH. 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 test procedure as the PIVs (STP-215.008, "SI and RH 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.
By aligning the testing frequency of the two check valves with the performance-based testing of the PIVs, the licensee can effectively implement the previously approved performance-based testing program in order to:
Eliminate unnecessary thermal cycles on the reactor coolant system (RCS) cold leg safety injection piping.
Reduce radiological dose consistent with NRC and industry As Low As Reasonably Achievable (ALARA) radiation dose principles.
The licensee proposes that if these check valves have demonstrated acceptable performance for two consecutive cycles, they may have their test interval extended to every third RFO, not to exceed 60 months. A 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.
NRC Staff Evaluation
The licensee has proposed an alternative testing frequency in lieu of the requirements of the 2004 Edition through the 2006 Addenda of the ASME OM Code for the two check valves listed in Table 1 of this safety evaluation. The NRC staff reviewed the licensees proposed alternative testing frequency and concluded that the proposed alternative to functionally test and verify the leakage rate of these check valves will be conducted using a 10 CFR 50 Appendix J, Option B, performance-based schedule aligned with a previously NRC-approved request for certain PIVs (ADAMS Accession No. ML18282A046), including a specific set located on either side of the check valves listed in Table 1 of this safety evaluation.
The NRC staff confirmed that the licensee plans to initially test the valves as specified by ASME OM Code Section ISTC-3630(a), which is every RFO, or 2 years. The NRC staff also confirmed that when the licensee transitions to the 10 CFR 50 Appendix J, Option B, schedule, the licensee will perform valve testing at intervals (frequencies) ranging from every RFO up to every third RFO, not to exceed 60 months. Valves that have demonstrated good performance for two consecutive cycles may have their test interval extended to every third RFO. Any valve leakage test failure would require the component to return to the initial interval of every RFO or two years until good performance can again be established.
The licensee stated that the two check valves are currently being leak tested every RFO or 2 years. The NRC staff reviewed the historical leak rate test data that the licensee provided, and the NRC staff concludes that the data demonstrates a good performance history for the subject check valves. The licensee also stated that no corrective maintenance was performed during the last four fuel cycles that would require a change to the analysis used to formulate the basis for extending the testing interval per the alternative request.
The two check valves in the licensees request are not PIVs, so the NRC staff reviewed the licensees justifications that the performance-based testing of the PIVs in the licensees Reference 1 are applicable to the two subject check valves. The NRC staff concludes the licensees proposed alternative is similar to the approach outlined in NEI 94-01, which is accepted for use in Regulatory Guide 1.163, Performance-Based Containment Leak-Test Program). In addition, the NRC staff reviewed that the licensee plans to conduct the separate functional testing of check valves per the ASME OM Code and use alarms provided to identify high pressure to low pressure leakage, which the staff finds acceptable. Furthermore, the NRC staff reviewed that the licensees leakage rate testing of these subject check valves, which utilizes the same plant conditions and test procedures as the adjacent PIVs discussed earlier, and the NRC staff concludes that by aligning the check valve leakage testing with the adjacent PIV leakage testing the licensee can eliminate unnecessary thermal cycles on the RCS cold leg safety injection piping and reduce radiological dose to workers. Finally, the NRC staff reviewed the historical performance data for the valves, which demonstrate a history of good performance, but should any valve fail a test, the licensee would be required to return to the initial interval of every RFO or two years until good performance can again be established.
Based on the NRC staffs review, the NRC staff concludes that the licensees alternative request to test two check valves under a performance-based testing program schedule provides an acceptable level of quality and safety for the components listed in Table 1 of this safety evaluation.
The licensee is authorized to implement a performance-based program for the two check valves listed in Table 1 of this safety evaluation at VCSNS Unit 1 until the end of the fourth IST Program interval, which is scheduled to end on December 31, 2023. The performance-based program interval shall not exceed three RFOs or 60 months.
3.3 Licensees Alternative Request RR-4-21 ASME OM Code Requirements:
ASME OM Code Mandatory Appendix II, 4000(b), Optimization of Condition-Monitoring Activities, (1)(e) states, in part, Identify the interval of each activity. Interval extensions shall be limited to one fuel cycle per extension.
Alternative testing is requested for the following valves:
Table 2 IST Program Valve ID IST Program Description Code Class OM Code Category XVC08703A-RH RH Header A Bypass Check Valve (IRC) 2 A/C IST Program Valve ID IST Program Description Code Class OM Code Category XVC08703B-RH RH Header B Bypass Check Valve (IRC) 2 A/C XVC08948A-SI SI Loop A Outlet Header Check Valve 1
A/C XVC08948B-SI SI Loop B Outlet Header Check Valve 1
A/C XVC08948C-SI SI Loop C Outlet Header Check Valve 1
A/C XVC08956A-SI SI Accum A Disch Header Check Valve 1
A/C XVC08956B-SI SI Accum B Disch Header Check Valve 1
A/C XVC08956C-SI SI Accum C Disch Header Check Valve 1
A/C XVC08973A-SI RCS Loop A Cold Leg Inlet Hdr Check Valve 1
A/C XVC08973B-SI RCS Loop B Cold Leg Inlet Hdr Check Valve 1
A/C XVC08973C-SI RCS Loop C Cold Leg Inlet Hdr Check Valve 1
A/C XVC08974A-SI SI Header A Check Valve (IRC) 2 A/C XVC08974B-SI SI Header B Check Valve (IRC) 2 A/C XVC08988A-SI RHR Supply Header Check Valve 1
A/C XVC08988B-SI RHR Supply Header Check Valve 1
A/C XVC08990A-SI Loop A High Head Hot Leg Check Valve 1
A/C XVC08990B-SI Loop B High Head Hot Leg Check Valve 1
A/C XVC08990C-SI Loop C High Head Hot Leg Check Valve 1
A/C XVC08992A-SI Loop A High Head Hot Leg Check Valve 1
A/C XVC08992B-SI Loop B High Head Hot Leg Check Valve 1
A/C XVC08992C-SI Loop C High Head Hot Leg Check Valve 1
A/C XVC08993A-SI Loop A High Head Hot Leg Hdr Check Valve 1
A/C XVC08993B-SI Loop B High Head Hot Leg Hdr Check Valve 1
A/C XVC08993C-SI Loop C High Head Hot Leg Hdr Check Valve 1
A/C XVC08995A-SI Loop A High Head Cold Leg Check Valve 1
A/C IST Program Valve ID IST Program Description Code Class OM Code Category XVC08995B-SI Loop B High Head Cold Leg Check Valve 1
A/C XVC08995C-SI Loop C High Head Cold Leg Check Valve 1
A/C XVC08997A-SI Loop A High Head Cold Leg Check Valve 1
A/C XVC08997B-SI Loop B High Head Cold Leg Check Valve 1
A/C XVC08997C-SI Loop C High Head Cold Leg Check Valve 1
A/C XVC08998A-SI Loop A Low Head Cold Leg Check Valve 1
A/C XVC08998B-SI Loop B Low Head Cold Leg Check Valve 1
A/C XVC08998C-SI Loop C Low Head Cold Leg Check Valve 1
A/C The licensees request states, in part, that ASME OM Code, Mandatory Appendix II, 4000(b)(1)(e) requires that extensions of testing intervals be limited to one fuel cycle per extension. The licensee had previously requested, and was authorized by the NRC, an alternative to ISTC-3630(a) to allow a performance-based testing frequency for all valves listed in Table 2 of this safety evaluation, except for check valves XVC08703A/B-RH, which are the subject of alternative request RR-4-19. Alternative request RR-4-19 is evaluated earlier in this safety evaluation and requests to include these valves into a similar performance-based testing frequency. The licensee is requesting immediate extension of the testing frequency to every third RFO, as opposed to being limited to a one fuel cycle extension. In doing so, the licensee states that this will eliminate unnecessary thermal cycles in the RCS cold leg safety injection piping and reduce radiological dose to personnel.
NRC Staff Evaluation
The NRC staff reviewed the licensees proposed alternative test frequency, which is in lieu of the requirements found in 2004 Edition through the 2006 Addenda of the ASME OM Code, Mandatory Appendix II, 4000(b)(1)(e), for the 33 valves listed in Table 2 of this safety evaluation. Specifically, the licensee proposes to immediately implement a leakage testing frequency of every third RFO and perform the next testing in RFO-27 instead of limiting extensions to one fuel cycle per extension.
The NRC previously authorized the licensees alternative for all but two of the valves subject to this alternative request (ADAMS Accession No. ML18345A060). This previous alternative request allowed for implementation of a performance-based testing program, allowing valves demonstrating good performance for two consecutive cycles to extend their test interval to every third RFO, not to exceed 60 months. Any valve leakage test failure would require the component to return to the initial interval of every RFO or two years until good performance can again be established. The licensee did not include the Mandatory Appendix II, 4000(b)(1)(e) limitation on interval extensions for check valves in their previous request but is now requesting authorization at this time.
The limitation on interval extensions for check valve testing in Mandatory Appendix II considers that performance history may not be available to support a longer extension than one RFO.
Overextending a test interval increases the risk of not detecting failures introduced by the increased duration between tests, so the basis for this limitation is sound. The NRC staff reviewed the historical performance data provided by the licensee for the last four RFOs for the valves listed in Table 2 of this safety evaluation. The NRC staff confirmed that all the valves in this request have successfully met the TS allowable leakage limits for the past four fuel cycles and, therefore, the NRC staff concludes the valves have a documented history of good performance.
Based the NRC staffs review, the NRC staff concludes that the alternative request to immediately implement a leakage testing frequency of every third RFO and perform the next testing in RFO-27 instead of limiting extensions to one fuel cycle per extension provides an acceptable level of quality and safety for the components listed in Table 2 of this safety evaluation.
The licensee is authorized to implement a leakage testing frequency of every third RFO and perform the next testing in RFO-27 for the valves in Table 2 of this safety evaluation at VCSNS Unit 1 until the end of the fourth IST Program interval, which is scheduled to end on December 31, 2023. The performance-based program interval shall not exceed three RFOs or 60 months.
Any valve leakage test failure would require the component to return to the initial interval of every RFO or two years until good performance can again be established, as described in the licensees previous alternative request.
4.0 CONCLUSION
Based on the above evaluation, the NRC staff concludes that the proposed alternatives described in requests RR-4-19 and RR-4-21 provides an acceptable level of quality and safety for the components listed in Table 1 and Table 2 of this safety evaluation. Therefore, the staff authorizes the use of alternative requests RR-4-19 and RR-4-21 until the end of the fourth IST Program interval, which is scheduled to end on December 31, 2023.
All other ASME OM Code requirements as incorporated by reference in 10 CFR 50.55a for which relief from, or an alternative to, was not specifically requested and approved in this subject request remain applicable.
Principal Contributor: Nicholas Hansing, NRR/DEX/EMIB Date: December 2, 2020