ML20169A584

Relief from the Requirements of the ASME Code

ML20169A584
Person / Time
Site:	Quad Cities
Issue date:	07/15/2020
From:	Nancy Salgado Plant Licensing Branch III
To:	Bryan Hanson Exelon Generation Co
Kuntz R
References
EPID L-2020-LLR-0000
Download: ML20169A584 (8)

Text

July 15, 2020 Mr. Bryan C. Hanson Senior Vice President Exelon Generation Company, LLC President and Chief Nuclear Officer (CNO)

Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2 - RELIEF FROM THE REQUIREMENTS OF THE ASME CODE (EPID L-2020-LLR-0000)

Dear Mr. Hanson:

By letter dated January 2, 2020, Exelon Generation Company, LLC, (the licensee) submitted an alternative request to the U.S. Nuclear Regulatory Commission (NRC) to the requirements of the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code), associated with valve inservice testing (IST) at Quad Cities Nuclear Power Station (QCNPS), Units 1 and 2.

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, Energy, of Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(z)(1), the licensee requested to use the proposed alternative in request RV-03, Revision 1, on the basis that the proposed alternatives will provide an acceptable level of quality and safety.

The NRC staff has reviewed the subject request and concludes, as set forth in the enclosed safety evaluation, that for alternative request RV-03, Revision 1, for QCNPS, Units 1 and 2, the proposed alternative provides an acceptable level of quality and safety for the valves listed in Table 1. Accordingly, the NRC staff concludes that the licensee has adequately addressed all the regulatory requirements set forth in 10 CFR 50.55a(z)(1) for request RV-03, Revision 1.

Therefore, the NRC staff authorizes the use of the alternative request RV-03, Revision 1, for QCNPS, Units 1 and 2, for the remainder of the fifth 10-year IST program interval, which began on February 18, 2013, and is scheduled to end on February 17, 2023.

All other ASME OM Code requirements for which relief was not specifically requested and approved in the subject requests remain applicable.

B. Hanson If you have any questions, please contact the Project Manager, Robert Kuntz at 301-415-3733 or via e-mail at Robert.Kuntz@nrc.gov.

Sincerely, Digitally signed by Nancy L. Nancy L. Salgado Date: 2020.07.15 Salgado 08:10:53 -04'00' Nancy L. Salgado, Chief Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-254 and 50-265

Enclosure:

Safety Evaluation cc: Listserv

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO RELIEF REQUEST RV-03, REVISION 1 EXELON GENERATION COMPANY, LLC AND MIDAMERICAN ENERGY COMPANY QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2 DOCKET NOS. 50-254 AND 50-265

1.0 INTRODUCTION

By letter dated January 2, 2020 (Agencywide Documents and Access Management System (ADAMS) Accession Number ML20003E481), Exelon Generation Company, LLC, (Exelon, the licensee), submitted an alternative to the requirements of the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code),

associated with valve inservice testing (IST) at Quad Cities Nuclear Power Station (QCNPS),

Units 1 and 2.

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, Energy, of Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(z)(1), the licensee requested to use the proposed alternative in request RV-03, Revision 1, on the basis that the proposed alternatives will provide an acceptable level of quality and safety.

2.0 REGULATORY EVALUATION

Regulation 10 CFR 50.55a(f), 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 10 CFR 50.55a(f)(2) and (3) 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.

Regulation 10 CFR 50.55a(z) states that alternatives to the requirements of paragraph (f) of 10 CFR 50.55a may be used, when authorized by the U. S. Nuclear Regulatory Commission Enclosure

(NRC), if the licensee demonstrates: (1) the proposed alternatives 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 Licensees Alternative Request RV-03 Revision 1 In the January 2, 2020, letter, the licensee requested an alternative to the valve testing requirements of the ASME OM Code. The licensee requested an alternative to the following provisions of the ASME OM Code:

ISTC-3522, Category C Check Valves, which states, in part, Category C check valves shall be exercised as follows: (a) During operation at power each check valve shall be exercised or examined in a manner that verifies obturator travel using the methods in para. ISTC-5221, (b) If exercising is not practicable during operation at power, it shall be performed during cold shutdowns, (c) If exercising is not practicable during operation at power and cold shutdowns, it shall be performed during refueling outages [RFOs].

The ISTC-3630, Leakage Rate for Other Than Containment Isolation Valves, states, 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 within acceptable limits.

Valve closure before seat leakage testing shall be by using valve operator with no additional closing force applied.

ISTC-3630(a), Frequency, states, Tests shall be conducted at least once every 2 yr[s].

In the January 2, 2020, letter, the licensee requested to use the proposed alternative described below for the valves listed in Table 1.

Table 1 Component Valve Containment System Code Category Number Type Isolation Valve Class (CIV), Pressure Isolation Valve (PIV),

Both 1(2)-1001-047-MO Gate Both Residual Heat 1 A Removal (RHR) 1(2)-1001-050-MO Gate Both RHR 1 A 1(2)-1001-029A-MO Gate Both RHR 1 A 1(2)-1001-029B-MO Gate Both RHR 1 A 1(2)-1001-068A Check PIV RHR 1 A/C 1(2)-1001-068B Check PIV RHR 1 A/C 1(2)-1001-009A Check PIV Core Spray (CS) 1 A/C 1(2)-1001-009B Check PIV CS 1 A/C 1(2)-1001-025A-MO Gate Both CS 1 A 1(2)-1001-025B-MO Gate Both CS 1 A

The QCNPS, Units 1 and 2, fifth 10-year IST program interval began on February 18, 2013 and is scheduled to end on February 17, 2023. The applicable ASME OM Code edition for the QCNPS, Units 1 and 2, fifth 10-year IST program interval is the 2004 Edition through the 2006 Addenda, which is incorporated by reference in 10 CFR 50.55a with conditions.

Reason for Request

ISTC-3630 requires that leakage rate testing for PIVs be performed at least once every 2 years. PIVs are not specifically included in the scope for performance-based testing as described in 10 CFR 50 Appendix J, "Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors," Option B, "Performance-Based Requirements" (Option B).

The QCNPS, Units 1 and 2, technical specification Section 5.5.12 includes a requirement to establish a leakage rate testing program in accordance with the guidelines contained in NEI 94-01, Revision 3-A, "Industry Guideline for Implementing Performance-Based Option of 10 CFR Part 50, Appendix J," dated July 2012, and conditions and limitations specified in NEI 94-01, Revision 2-A, dated October 2008.

NEI 94-01 describes the risk-informed basis for extended test intervals under Option B.

The valves identified in Table 1 are installed in water applications. The motor-operated valves (MOVs) are PIVs and CIVs, and they are exempt from air testing because their piping meets the requirements for closed water loops. The check valve PIVs are not CIVs and are not within the scope of Appendix J. The PIV testing is performed with water pressurized to pressures lower than function maximum pressure differential, and the observed leakage is adjusted to the function maximum pressure differential value in accordance with ISTC-3630(b)(4).

The performance of PIV leak rate testing provides assurance of acceptable seat leakage with the valve in a closed condition. PIV leak rate testing does not identify any issues with valve cycling. The MOVs are functionally tested in accordance with Section 3.6, "MOV Exercising Requirements, of OM Code Case OMN-1, and 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."

Proposed Alternative The request proposes to perform PIV testing at intervals ranging from every RFO to every third RFO. The specific interval for each valve would be a function of its performance and would be established in a manner consistent with the CIV process under Option B. If any valve fails its PIV test, the test interval will be reduced consistent with Option B requirements until good performance is reestablished.

The extension of test frequencies will be consistent with the guidance provided for Appendix J, Type C leak rate tests as detailed in paragraph 10.2.3.2, Extended Test Interval, of Nuclear Energy Institute (NEI) 94-01.

NRC Staff Evaluation

The request proposed an alternative test in lieu of the requirements in the ASME OM Code Section ISTC-3630(a) for all 20 of the PIVs listed in Table 1. Specifically, the request proposes to functionally test and verify the leakage rate of the PIVs using the Option B performance-based schedule. Valves would initially be tested at the required interval schedule which is currently every RFO or 2 years. Valves that have demonstrated good performance for two consecutive cycles may have their test interval extended from every RFO to every third RFO not to exceed 6 years. Any PIV leakage test failure would require the component to return to the initial interval of every RFO or 2 years until it can be reclassified as a good performer per the performance evaluation of Option B. The leakage test interval for these PIVs shall not exceed 60 months with a 15-month grace period based on the performance (i.e., a total of 75 months).

The specific interval for each valve will be a function of its performance and will be established in a manner consistent with the CIV process under Option B.

The PIVs are defined as two valves in a series within the reactor coolant pressure boundary which separate the high-pressure reactor coolant system from an attached low-pressure system. Failure of a PIV could result in an over-pressurization event which could lead to a system rupture and possible release of fission products to the environment. This type of failure event was analyzed under NUREG/CR-5928, "Interfacing System LOCA (ISLOCA) Research Program," (ADAMS Accession No. ML072430731). The purpose of NUREG/CR-5928 was to quantify the risk associated with an ISLOCA event. NUREG/CR-5928 analyzed boiling-water reactor (BWR) and pressurized-water reactor (PWR) designs.

Option B is a performance-based leakage test program. Guidance for implementation of acceptable leakage rate test methods, procedures, and analyses is provided in Regulatory Guide (RG) 1.163, Performance Based Containment Leak Test Program (ADAMS Accession No. ML003740058). RG 1.163 endorses NEI Topical Report (TR) 94-01, Revision 0, Industry Guideline for Implementing Performance Based Option of 10 CFR 50, Appendix J dated July 26, 1995, with the limitation that Type C components test interval cannot extend greater than 60 months. The current version of NEI 94-01 is Revision 3-A which allows Type C containment isolation valves test intervals to be extended to 75 months with a permissible extension for non-routine emergent conditions of nine months (84 months total). The NRC staff finds the guidance in NEI 94-01, Revision 3-A, is acceptable (ADAMS Accession Nos.

ML121030286 and ML12226A546) with the following conditions:

1) Extended interval for Type C local leak-rate tests (LLRTs) may be increased to 75 months with the requirement that the post outage report include the margin between Type B and Type C leakage rate summation and its regulatory limit. In addition, a corrective action plan shall be developed to restore the margin to an acceptable level.

Extensions of up to 9 months (total maximum interval of 84 months for Type C tests) are permissible only for non-routine emergent conditions. This provision (9-month extension) does not apply to valves that are restricted and/or limited to 30-month intervals in Section 10.2 (such as BWR MSIVs (main steam isolation valves)) or to valves held to the base interval (30 months) due to unsatisfactory LLRT performance.

2) When routinely scheduling any LLRT valve interval beyond 60-months and up to 75-months, the primary containment leakage rate testing program trending or monitoring must include an estimate of the amount of understatement in the Type B and C total and must be included in the post-outage report. The report must include the reasoning and

determination of the acceptability of the extension, demonstrating that the LLRT totals calculated represent the actual leakage potential of the penetrations.

Currently, all 20 PIVs in this request are being leak tested every RFO or 2 years and the licensee presented data that shows the PIVs have maintained a history of good performance.

In addition, functional tests and/or performance indicator test are routinely performed on each of the PIV check valves and full stroke tests of other PIVs are completed in accordance with ASME OM Code requirements, to ensure their functional capabilities. Based on good valve performance and maintenance history, coupled with stroking each valve every RFO and the low risk factor, as noted in NUREG/CR-5928, the proposed alternative provides an acceptable level of quality and safety.

4.0 CONCLUSION

As set forth above, the NRC staff determined that for RV-03, Revision 1, for QCNPS, Units 1 and 2, the proposed alternative provides an acceptable level of quality and safety for the valves listed in Table 1. Accordingly, the NRC staff concludes that the request has adequately addressed all the regulatory requirements set forth in 10 CFR 50.55a(z)(1) for request RV-03, Revision 1. Therefore, the NRC staff authorizes the use of the alternative request RV-03, Revision 1, for QCNPS, Units 1 and 2, for the remainder of the fifth 10-year IST program interval, which began on February 18, 2013, and is scheduled to end on February 17, 2023.

All other ASME OM Code requirements for which relief was not specifically requested and approved in the subject requests remain applicable.

Principal Contributor: R. Wolfgang, NRR Date: July 15, 2020

ML20169A584 *Via e-mail OFFICE NRR/DORL/LPL3/PM* NRR/DORL/LPL3/LA* NRR/DEX/EMIB/BC* NRR/DORL/LPL3/BC*

NAME RKuntz SRohrer ABuford NSalgado DATE 06/18/2020 6/18/2020 06/11/2020 07/15/2020