ML21259A099

Proposed Alternatives to American Society of Mechanical Engineers Code for Operation and Maintenance of Nuclear Power Plants

ML21259A099
Person / Time
Site:	Robinson
Issue date:	11/04/2021
From:	David Wrona Plant Licensing Branch II
To:	Kapopoulos E Duke Energy Progress
Hood T
References
EPID L-2021-LLR-0024, RA-21-0095
Download: ML21259A099 (9)

Text

November 4, 2021 Mr. Ernest J. Kapopoulos, Jr.

Site Vice President H. B. Robinson Steam Electric Plant Duke Energy Progress, LLC 3581 West Entrance Road, RNPA01 Hartsville, SC 29550

SUBJECT:

H. B. ROBINSON STEAM ELECTRIC PLANT, UNIT 2 - PROPOSED ALTERNATIVES TO AMERICAN SOCIETY OF MECHANICAL ENGINEERS CODE FOR OPERATION AND MAINTENANCE OF NUCLEAR POWER PLANTS (EPID L-2021-LLR-0024)

Dear Mr. Kapopoulos:

By letter dated March 29, 2021 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML21088A139), Duke Energy Progress, LLC (Duke Energy, the licensee) submitted a request to the U.S. Nuclear Regulatory Commission (NRC) for the use of an alternative to specific Inservice Testing (IST) Program requirements in the 2017 Edition of the American Society of Mechanical Engineers (ASME) Operation and Maintenance of Nuclear Power Plants, Division 1, OM Code: Section IST (OM Code), as incorporated by reference in Title 10 of the Code of Federal Regulations (10 CFR) 50.55a, at the H. B. Robinson Steam Electric Plant, Unit 2 (Robinson) associated with the Sixth 10-Year IST Program interval.

Specifically, pursuant to 10 CFR 50.55a(z)(1), the licensee requested to use an alternative Request IST-RR-9 on the basis that the alternative provides 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 the proposed alternatives described in alternative request IST-RR-9 provide an acceptable level of quality and safety for the Sixth 10-year IST program interval, which begins on February 19, 2022. Accordingly, the NRC staff concludes that Duke Energy has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(z)(1).

Therefore, the NRC staff authorizes the use of proposed alternative request IST-RR-9 for the Sixth 10-year IST program interval at Robinson, which begins on February 19, 2022, and ends on February 18, 2032.

All other ASME OM Code requirements for which relief or an alternative was not specifically requested and approved remain applicable.

E. Kapopoulos If you have any questions, please contact Tanya Hood at (301) 415-1387 or by e-mail at Tanya.Hood@nrc.gov.

Sincerely, Digitally signed by David David J. J. Wrona Date: 2021.11.04 Wrona 13:23:32 -04'00' David J. Wrona, Chief Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-261

Enclosure:

Safety Evaluation cc: Listserv

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION PROPOSED ALTERNATIVE REQUEST IST-RR-9 REGARDING THE SIXTH 10-YEAR INTERVAL INSERVICE TESTING PROGRAM DUKE ENERGY PROGRESS, LLC H. B. ROBINSON STEAM ELECTRIC PLANT, UNIT NO. 2 DOCKET NO. 50-261 EPID-2021-LLR-0024

1.0 INTRODUCTION

By letter dated March 29, 2021 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML21088A139), Duke Energy Progress, LLC (Duke, the licensee) submitted Alternative Request IST-RR-9, as well as several additional requests, to the U.S. Nuclear Regulatory Commission (NRC) for the use of an alternative to specific Inservice Testing (IST) Program requirements in the 2017 Edition of the American Society of Mechanical Engineers (ASME) Operation and Maintenance of Nuclear Power Plants, Division 1, (OM Code): Section IST OM Code, as incorporated by reference in Title 10 of the Code of Federal Regulations (10 CFR) 50.55a, at the H. B. Robinson Steam Electric Plant (Robinson) associated with the Sixth 10-Year IST Program interval.

Specifically, pursuant to 10 CFR 50.55a(z)(1), the licensee proposed to implement Alternative Request IST-RR-9 on the basis that the alternative provides an acceptable level of quality and safety. The NRC describes its review of Alternative Request IST-RR-9 for Robinson in this safety evaluation (SE).

2.0 REGULATORY EVALUATION

The NRC regulations in 10 CFR 50.55a(f), Inservice Testing Requirements, require, in part, that inservice testing of certain ASME Code Class 1, 2, and 3 components must meet the requirements of the ASME OM Code and applicable addenda, except where alternatives have been authorized pursuant to paragraph 10 CFR 50.55a(z)(1) or 10 CFR 50.55a(z)(2).

The NRC regulations in 10 CFR 50.55a(b)(3)(ii) require nuclear power plant licensees to comply with the provisions of the ASME OM Code as incorporated by reference in 10 CFR 50.55a, and Enclosure

to establish a program to ensure that motor-operated valves (MOVs) continue to be capable of performing their design-basis safety function.

In proposing alternatives, a licensee must demonstrate that the proposed alternatives provide an acceptable level of quality and safety (10 CFR 50.55a(z)(1)) or compliance would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety (10 CFR 50.55a(z)(2)).

3.0 TECHNICAL EVALUATION

The information provided by the licensee in support of Alternative IST-RR-9 has been evaluated and the bases for disposition are documented below.

Applicable Code Edition and Addenda

The applicable ASME OM Code edition for the Sixth 10-Year IST Program interval at Robinson is the 2017 Edition of ASME OM Code, as incorporated by reference in 10 CFR 50.55a.

Duration of the Alternative The licensee proposed Alternative Request IST-RR-9 for the duration of the Sixth 10-Year IST Program interval, which begins on February 19, 2022.

3.1 Licensees Alternative Request IST-RR-9 The IST requirements of the ASME OM Code as incorporated by reference in 10 CFR 50.55a related to this alternative request are as follows:

ASME OM Code, Mandatory Appendix III, Preservice and Inservice Testing of Active Electric Motor-Operated Valve Assemblies in Water-Cooled Reactor Nuclear Power Plants, paragraph III-3310, Inservice Test Interval, subparagraph (c),

states that:

The maximum inservice test interval shall not exceed 10 yr. MOV inservice tests conducted per para. III-3400 may be used to satisfy this requirement.

ASME OM Code, Mandatory Appendix III, paragraph III-3700, Risk-Informed MOV Inservice Testing, states that:

Risk-informed MOV inservice testing that incorporates risk insights in conjunction with performance margin to establish MOV grouping, acceptance criteria, exercising requirements and testing interval may be implemented.

ASME OM Code, Mandatory Appendix III, paragraph III-3721, HSSC [High Safety Significant Component] MOVs, states that:

HSSC MOVs shall be tested in accordance with para. III-3300 and exercised in accordance with para. III-3600. HSSC MOVs that can be operated during plant operation shall be exercised quarterly, unless the potential increase in core damage

frequency (CDF) and large early release (LER) associated with a longer exercise interval is small.

ASME OM Code, Mandatory Appendix III, paragraph III-3722, LSSC [Low Safety Significant Component] MOVs, subparagraph (d), states that:

MOVs shall be inservice tested at least every 10 yr in accordance with para. III-3310.

Reason for Request

The licensee states that ASME OM Code Case OMN-26, Alternate Risk-Informed and Margin Based Rules for Inservice Testing of Motor Operated Valves, better aligns ASME OM Code, Mandatory Appendix III, with the risk and margin based MOV programs developed in response to NRC Generic Letter (GL) 96-05, Periodic Verification of Design-Basis Capability of Safety-Related Motor-Operated Valves, that have been in effect since 1998. The licensee states that the Appendix III 10-year maximum IST interval was originally established to align with the maximum test interval allowed under the GL 96-05 MOV Programs that, for most licensees, were established by the Joint Owners Group (JOG) MOV Periodic Verification Program. The licensee notes that there is no formal technical basis for the current Appendix III 10-year maximum interval that applies to all MOVs regardless of risk and margin. ASME OM Code Case OMN-26 establishes a structured risk-informed approach for determining IST intervals that provides an acceptable level of quality and safety while providing Robinson additional IST schedule flexibility.

Licensees Proposed Alternative The licensee proposes to implement ASME OM Code Case OMN-26 in establishing alternative risk and margin informed rules for inservice testing of MOVs in its entirety. The licensee summarizes the provisions of ASME OM Code Case OMN-26 in its submittal.

3.2 NRC Staff Evaluation The NRC regulations in 10 CFR 50.55a(b)(3)(ii) require nuclear power plant licensees to comply with the provisions of the ASME OM Code as incorporated by reference in 10 CFR 50.55a, and to establish a program to ensure that MOVs continue to be capable of performing their design-basis safety function. The NRC staff considers ASME OM Code testing specified in Mandatory Appendix III, with the conditions in 10 CFR 50.55a(b)(3)(ii), to incorporate the MOV diagnostic test programs developed in response to NRC GL 89-10, Safety-Related Motor-Operated Valve Testing and Surveillance, and GL 96-05.

In GL 89-10, the NRC staff requested that each nuclear power plant licensee establish a program to demonstrate that safety-related MOVs are capable of performing their design basis functions. During the implementation of GL 89-10, the NRC staff provided four acceptable methods that a licensee could use to demonstrate the design basis capability of its safety-related MOVs. The four methods for demonstrating capability in descending order of acceptability are:

1) Dynamic testing at or near design basis conditions with diagnostics of each MOV where practicable. Valves dynamically tested at less than design basis conditions may be extrapolated with proper justification.

2) Electric Power Research Institute (EPRI) MOV Performance Prediction Methodology (PPM). This method was developed for those valves that could not be dynamically tested. The PPM required internal valve measurements to provide assurance that the valve performance was predictable. The NRC staff began accepting the use of the PPM even where dynamic testing for an MOV was practicable.

3) MOV valve grouping. Where valve-specific dynamic testing was not performed and the PPM was not used, the staff accepted grouping of MOVs that were dynamic tested at the plant to apply the plant-specific test information to an MOV in the group.

4) The use of valve test data from other plants or research programs. The NRC ranks this as the least-preferred approach (with the most margin required) because the licensee would have minimal information regarding the tested valve and its history.

In superseding GL 89-10, GL 96-05 requested that each licensee establish a program, or ensure the effectiveness of its current program, to verify on a periodic basis that safety-related MOVs continue to be capable of performing their safety functions within the current licensing basis of the facility. The GL 96-05 program was intended to ensure that changes in required MOV performance resulting from degradation (such as those caused by age) can be properly identified and addressed.

In response to GL 96-05, the nuclear industry joined together to form the JOG MOV Periodic Verification Program. The JOG program consisted of three elements: 1) an interim MOV periodic verification program for licensees to use in response to GL 96-05 during development of a long-term program; 2) a 5-year MOV dynamic diagnostic test program; and 3) a long-term MOV periodic diagnostic test program to be based on the information from the dynamic testing program. The JOG effort was intended to address the potential for valve degradation as it pertained to valve configuration, design, and system application. The JOG test program was not intended to provide data to the industry for the purpose of justifying valve performance.

The final JOG program plan consisted of periodic diagnostic test program that is based on risk and margin. The NRC staff approved the JOG final program plan, with conditions, in an SE dated September 25, 2006 (ADAMS Accession No. ML061280315).

The ASME OM Code establishes the requirements for preservice and inservice testing and examination of certain components to assess their operational readiness in light-water reactor nuclear power plants. These requirements apply to pumps and valves that are required to perform a specific function in shutting down a reactor to the safe shutdown condition, in maintaining the safe shutdown condition, or in mitigating the consequences of an accident.

The ASME OM Code also applies to pressure relief devices and dynamic restraints.

Prior to the development of Mandatory Appendix III, the ASME OM Code testing for MOVs consisted of:

1) Valve exercising to include quarterly stroke time testing

2) Valve obturator movement verification during the exercise test

3) Valve leakage testing (only if the valve has a leakage limit requirement)

4) Remote position indication verification In the past, these required tests were considered to be adequate to assess MOV operational readiness. However, over the course of several years of MOV operating experience and

testing, it was determined that quarterly stroke-time testing of MOVs was not an adequate indicator of MOV degradation. As an alternative to MOV stroke-time testing, ASME developed Code Case OMN-1, Alternative Rules for Preservice and Inservice Testing of Active Electric Motor Operated Valve Assemblies in Light-Water Reactor Power Plants, to allow periodic exercising and diagnostic testing in assessing operational readiness of active MOVs in lieu of quarterly stroke-time testing. ASME provided additional guidance by developing Code Case OMN-11, Risk-Informed Testing for Motor-Operated Valves, for MOVs in the IST program that are determined to have a high safety significance. The NRC staff has reviewed and accepted these Code Cases with certain conditions as noted in Regulatory Guide (RG) 1.192, Operation and Maintenance Code Case Acceptability ASME OM Code, which is incorporated by reference in 10 CFR 50.55a. ASME merged these two Code Cases into an updated version of Code Case OMN-1 published in the 2006 Addenda of the ASME OM Code. This updated Code Case OMN-1 was later adopted into the 2009 Edition of ASME OM Code as Mandatory Appendix III. The NRC conditions for use of Mandatory Appendix III are specified in 10 CFR 50.55a(b)(3)(ii).

Licensees of operating nuclear power plants must meet the requirements of 10 CFR 50.55a(b)(3)(ii) in implementing the ASME OM Code requirements, and establish an MOV program that periodically verifies that MOVs will continue to perform their safety function. The NRC staff considers that the JOG MOV Periodic Verification Program can be used to help satisfy the requirements in ASME OM Code, Mandatory Appendix III, with the conditions in 10 CFR 50.55a(b)(3)(ii). Some aspects of the JOG MOV Periodic Verification Program that need to be addressed when used to help meet the NRC regulations are as follows:

1) The JOG program incorporates risk into its MOV diagnostic testing schedule, but Mandatory Appendix III does not require the implementation of a risk-informed program. Applying risk in Mandatory Appendix III relaxes MOV grouping requirements, which allows for more flexible testing.

2) The JOG program has specific test intervals based on risk and margin. Under the JOG program, high risk MOVs have shorter test intervals dependent on margin with a maximum test interval of 6 years for high margin and 2 years for low margin.

Mandatory Appendix III relies on the plant MOV engineer to set the correct test interval not to exceed 10 years based on specific MOV diagnostic test data.

3) The licensees implementation of the JOG program is a commitment in response to GL 96-05, whereas the implementation of Mandatory Appendix III is a regulatory requirement.

4) The JOG program applies to valve performance, and the licensee is responsible for justifying the periodic verification of the actuator performance.

ASME developed Code Case OMN-26 to reduce the amount of programmatic changes for licensees incorporating Mandatory Appendix III for the first time when the licensees update their IST Programs. Code Case OMN-26 aligns those portions of Mandatory Appendix III to follow the JOG approach of the test interval being based on both margin and risk that has been successfully implemented for 20 years. In some instances, Code Case OMN-26 is more restrictive in that certain MOVs (without periodic design-basis testing) are not allowed to have test intervals up to the 10-year interval that is allowed in Mandatory Appendix III. On the other hand, Code Case OMN-26 will allow certain MOVs to have test intervals based on their risk and margin that are beyond the 10-year interval in Appendix III. The NRC staff considers the

extensions of the test intervals in Code Case OMN-26 to be reasonable based on many years of successful test data in implementing the JOG program by nuclear power plant licensees.

Another aspect of Code Case OMN-26 is that for high-risk MOVs with very high margins that are successfully stroked at least once per operating cycle under full design pressure and flow, the test interval may be extended to 12 years. Similarly, the diagnostic test interval for low-risk MOVs with very high margins and that are successfully stroked at least once per operating cycle under full design pressure and flow, the test interval may be extended to 16 years.

Essentially, each successful stroke under full design pressure and flow is a reasonable demonstration of an MOV being operationally ready to perform its safety function without diagnostic test equipment.

The NRC staff is reviewing Code Case OMN-26 for acceptance in RG 1.192. In its letter dated March 29, 2021, the licensee states that the provisions of Code Case OMN-26 will be implemented in their entirety, including all tables and associated notes. The NRC staff has determined that the licensees proposed alternative to implement Code Case OMN-26, in its entirety, at Robinson provides an acceptable level quality and safety for the Sixth 10-Year IST Program interval.

4.0 CONCLUSION

As set forth above, the NRC staff finds that the proposed alternatives described in alternative request IST-RR-9 provide an acceptable level of quality and safety for the Sixth 10-year IST program interval, which begins on February 19, 2022. Accordingly, the NRC staff concludes that the licensee has adequately addressed all the regulatory requirements set forth in 10 CFR 50.55a(z)(1). Therefore, the NRC staff authorizes the use of proposed alternative request IST-RR-9 for the Sixth 10-year IST program interval at Robinson, which begins on February 19, 2022, and ends on February 18, 2032.

All other ASME Code requirements for which relief or an alternative was not specifically requested, and granted or authorized (as appropriate), in the subject request remain applicable.

Principal Contributor: Y. Wong, NRR T. Scarbrough, NRR Date: November 4, 2021

ML21259A099 *by e-mail OFFICE NRR/DORL/LPL2-1/PM NRR/DORL/LPL2-2/LA NRR/DEX/EMIB/BC* NRR/DORL/LPL2-2/BC NAME JKlos RButler ITseng DWrona DATE 9/13/2021 9/23/2021 9/7/2021 11/4/2021