ML26009A095

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NRC Staff Presentation: Regulatory Topics on Motor-Operated Valves and Air-Operated Valves (January 2026)
ML26009A095
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Issue date: 01/09/2026
From: Nicholas Hansing, Thomas Scarbrough, Yuken Wong
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Regulatory Topics on Motor-Operated Valves and Air-Operated Valves Thomas G. Scarbrough Nicholas J. Hansing Yuken Wong Mechanical Engineering and Inservice Testing Branch Division of Engineering and External Hazards U.S. Nuclear Regulatory Commission MUG/AUG January 2026 Remote Presentation

Disclaimer This presentation was prepared by staff of the U.S. Nuclear Regulatory Commission (NRC). It may present information that does not currently represent an agreed upon NRC staff position. NRC has neither approved nor disapproved the technical content.

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Overview Remarks Jeremy Groom, Acting Director of the NRC Office of Nuclear Reactor Regulation, discussed the status of nuclear power in the United States in his keynote address during the 2025 ASME/NRC OM Symposium, including the following key messages:

  • We are at a pivotal moment for the renewed interest, urgency, and investment in nuclear energy.
  • New reactor applications are under review by the NRC.
  • Nuclear power plants are being restarted after planned permanent shutdowns.
  • Nuclear energy to support energy independence, to meet supply demands, and to combat climate change is not just relevant. It is essential.
  • To make this vision a reality, NRC is undergoing a significant transformation, and modernizing the licensing framework to accommodate new reactor designs.

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Overview Remarks (continued)

  • Inservice testing is a pillar of safety assurance at nuclear power plants.
  • Development of IST Programs must be ready for new and advanced reactors, such as implementation of the new ASME OM-2 Code.
  • Significant need for continued integration of component qualification and long-term reliability.
  • Digital technology is reshaping the approach for performance-based testing of nuclear power plant components.
  • NRC is working with ASME to fulfill our important mission to advance nuclear safety while enabling innovation.
  • Our challenge is to build a framework to support a modern, resilient, and safe nuclear infrastructure as a national imperative.

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10 CFR 50.55a, Codes and standards

  • 10 CFR 50.55a incorporates by reference specific editions and addenda of the ASME BPV Code,Section III (Design) and Section XI (Inservice Inspection), and ASME Operation and Maintenance of Nuclear Power Plants, Division 1, OM Code: Section IST (Inservice Testing).
  • 10 CFR 50.55a currently incorporates by reference the 2022 Edition (and earlier editions and addenda) of the ASME OM Code with conditions, and Revision 5 to Regulatory Guide (RG) 1.192 accepts specific OM Code Cases with or without conditions.

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OM Code of Record Interval Extension

  • In the current 10 CFR 50.55a, licensees are required to update OM Code of Record (COR) at least every two consecutive 10-Year IST intervals specified in Subsection ISTA, paragraph ISTA-3120, where implementing 2017 Edition (or later) of the OM Code, and each 10-year IST interval if earlier than 2017 Edition.

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Streamlining 10 CFR 50.55a Rulemaking

  • NRC has established a new approach to streamline the 10 CFR 50.55a rulemaking by the following processes:
  • Proposed/final rule process for the biennial incorporation by reference in 10 CFR 50.55a of specific ASME BPV and OM Code editions and revisions to RGs 1.84, 1.147, and 1.192 for ASME Code Cases with or without conditions.
  • Direct final rule (DFR) process to incorporate by reference in 10 CFR 50.55a revisions to RG 1.262, ASME Code Cases Approved for Use Without Conditions, accepting noncontroversial and unconditionally-approved Code Cases.
  • RG 1.262 was developed for the purpose of the DFR process, but otherwise has the same status as RGs 1.84, 1.147, and 1.192
  • RG 1.262 (Revision 0) is scheduled for issuance in 2026 7

Direct Final Rule for Noncontroversial and Unconditioned Code Cases

  • On September 26, 2025, the NRC issued Federal Register Notice 90 FR 46319 to incorporate by reference RG 1.262, Revision 0, in 10 CFR 50.55a under the direct final rule process.
  • 10 CFR 50.55a amendment will be effective on January 26, 2026, unless significant adverse comments were received by November 25, 2025.
  • NRC is evaluating the received comments to determine whether they meet the significant adverse threshold.

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Code Edition and Code Case Rulemaking Currently Under Development

  • NRC staff is drafting a proposed 10 CFR 50.55a rule for public comment for incorporation by reference of 2023 Edition of ASME BPV Code with conditions in 10 CFR 50.55a.
  • Draft rule includes proposed revisions to RGs 1.84, 1.147, and 1.192 specifying acceptable code cases with or without conditions.
  • Proposed rule should be issued for public comment in early 2026.

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Operating Reactor IST Upgrades

  • ASME has improved the IST requirements for the operational readiness of motor-operated valves (MOVs) and air-operated valves (AOVs) to perform their design-basis safety functions in nuclear power plants.
  • In the 2009 Edition of the OM Code, ASME included Appendix III to replace quarterly stroke-time testing requirements with periodic exercising and diagnostic testing of MOVs in the IST Program.
  • In the 2017 Edition of the OM Code, ASME included Appendix IV to require periodic diagnostic testing of high safety significant AOVs in addition to quarterly stroke-time testing of all AOVs in the IST Program.
  • Some licensees have begun implementing these new MOV and AOV testing requirements as part of the periodic updates of their IST Programs.
  • Licensees are encouraged to contact their NRC Project Manager during the update process if challenges occur with the improved IST requirements in the ASME OM Code.

10

Restart of Shutdown Reactors

  • Several licensees are considering restart of nuclear power plants that had been shut down for planned decommissioning.
  • NRC staff have been working with those licensees to ensure that the IST Programs will provide reasonable assurance that the AOVs and MOVs (and other components) are operationally ready to perform their design-basis safety functions upon plant restart.
  • These interactions have been successful with the licensees demonstrating a strong emphasis on ensuring the design-basis capability of the components to perform their safety functions in preparing for plant restart.
  • Licensees considering restart of shutdown reactors are encouraged to contact their NRC Project Manager to set-up discussions with the NRC staff responsible for the review of IST Programs.

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Development of IST Programs for New and Advanced Reactors

  • Mechanical equipment within the scope of the IST Program must be qualified for seismic, environmental, and functional capability to support the development of the IST Program for new and advanced reactors.
  • ASME QME-1 Standard specifies provisions for the qualification of active mechanical equipment used in nuclear power plants.
  • Reactors with non-water-cooled designs are outside the scope of 10 CFR 50.55a.
  • ASME OM-2-2024 Code specifies provisions for IST programs for new and advanced reactors with water-cooled or non-water-cooled designs.

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Qualification of Mechanical Equipment

  • ASME QME-1-2017, Qualification of Active Mechanical Equipment Used in Nuclear Facilities, is accepted in Revision 4 to RG 1.100, Seismic Qualification of Electrical and Active Mechanical Equipment and Functional Qualification of Active Mechanical Equipment for Nuclear Power Plants, with regulatory positions.
  • ASME QME-1-2023 includes improvements for the qualification of active mechanical equipment in nuclear facilities with its focus on water-cooled reactors.
  • In November 2025, ASME issued QME-1-2025, Qualification of Mechanical Equipment Used in Nuclear Facilities, which reformats the standard for more effective application for qualification of mechanical equipment in either water-cooled and non-water-cooled nuclear facilities.
  • NRC staff are drafting proposed Revision 5 to RG 1.100 to accept ASME QME-1-2023 and QME-1-2025 with applicable regulatory positions.
  • Proposed Revision 5 to RG 1.100 should be issued for public comment in early 2026.

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ASME OM-2-2024 Code

  • In October 2024, ASME issued OM-2-2024 to specify provisions for IST programs in new and advanced reactors with water-cooled or non-water-cooled designs.
  • Scope includes components that control the movement of fluid (e.g., pumps and valves), and dynamic restraints.
  • Risk insights may be applied at the outset in developing the IST Program.
  • Specifies use of QME-1 (or equivalent) for initial qualification of IST components.
  • Allows flexibility for advanced condition monitoring methods.
  • New and advanced reactor designers are interested in applying the OM-2 Code in developing IST Programs for their nuclear facilities.

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Regulatory Guide 1.220

  • NRC staff are drafting new RG 1.220 (DG-1424) to accept ASME OM 2024 Code for IST Programs in new and advanced reactors with water-cooled or non-water-cooled designs.
  • Regulatory control of implementation of ASME OM-2-2024 as accepted in RG 1.220 would be accomplished by a license condition (similar to RG 1.246 for inservice inspection programs in new and advanced reactors).
  • NRC staff will review the proposed IST Program for new and advanced reactors as part of the licensing process.
  • NRC staff plans to issue RG 1.220 in spring 2026.

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16 ASME OM-1 Code Project

  • The ASME OM Code committees are working to develop a streamlined and improved version of the OM Code referred to as OM-1.
  • The NRC staff has been participating on the OM-1 task groups (including Sections MOV and AOV) to minimize any regulatory conditions when accepted. For example, Section MOV might be able to justify removal of the 10 CFR 50.55a(b)(3)(ii)(A) through (D) conditions.
  • The OM-1 format will be similar to the ASME OM-2-2024 Code format that is more straightforward for application by industry personnel.
  • The OM-1 Code will include improvements in the IST requirements based on lessons learned for the implementation of the OM Code and operating experience.
  • ASME is working to complete the OM-1 Code for issuance in 2026.
  • The NRC staff will review the OM-1 Code for acceptance when published.

17 NUREG-1482 Guidelines for Inservice Testing at Nuclear Power Plants

  • Describes regulatory basis for IST programs for nuclear power plants.
  • Provides guidance for development of IST programs:

o Scope o IST program documentation o Preconditioning o Specific valve guidance o Specific pump guidance o Specific dynamic restraint/snubber guidance o New reactor IST guidance

  • In September 2025, NRC staff issued Revision 4 to NUREG-1482 to provide updated IST guidance based on regulatory requirements, OM Code editions, and operating experience. It is available in ADAMS at ML25267A104.

18 Revision 4 to NUREG-1482

  • Draft released February 2025.
  • 46 Public Comments received.
  • Highlighted guidance updates include:

o Use of 2022 ASME OM Code, specific OM Code Cases, and associated regulatory requirements.

o Active/Passive classification of valves in IST Program.

o Category A or B valve categorization with respect to leakage.

o Valve position indication requirements in ASME OM Code and 10 CFR 50.55a(b)(3)(xi), including use of Code Case OMN-28 in evaluating potential stem-disk separation.

19 Revision 4 to NUREG-1482

  • Highlighted guidance updates include (continued):

o Skid-mounted component testing.

o Verification of check valve position.

o Implementation of ASME OM Code, Appendix III, for MOVs including 50.55a regulatory conditions.

o MOV backseating requirements in ASME OM Code.

20 Revision 4 to NUREG-1482

  • Highlighted guidance updates include (continued):

o Pump Periodic Verification Test requirements in recent ASME OM Code editions.

o Safety relief valve testing requirements with respect to installed operating conditions.

o Relocation of IST Plan submittal requirement from ASME OM Code to 50.55a(f)(7).

o New Appendix on the topic of Code of Record Intervals.

21 MOV Backseating Operating Experience

  • Operating experience indicates that MOV backseating can cause significant damage to the MOV stem and backseat if not carefully controlled.
  • Additional information can be found in:
  • NRC authorizations (e.g., 1-17-2017 SE McGuire).

22 MOV Backseating Code Case

  • ASME OM Code, Subsection ISTC, ISTC-3310 (and III-3400 for MOVs and IV-3520 for AOVs) requires that when a valve has been replaced or repaired, or has undergone maintenance that could affect the valves performance, a new reference value shall be determined or the previous values reconfirmed by an inservice test before it is returned to service or immediately if not removed from service.
  • Per December 2025 meeting of ASME OM Code Subgroup on MOVs (SG-MOV), a task group is drafting a code case on MOV backseating as an acceptable Code alternative to avoid the need for a hardship alternative request under 10 CFR 50.55a(z)(2).
  • SG-MOV members emphasized that MOV backseating should only be used when the MOV is not accessible during plant operation.
  • When drafted, the task group will submit the code case for ballot by the SG-MOV.

MOV Anomalous Behavior

  • OM Code, Appendix III, and Code Case OMN-1 specify that anomalous behavior observed during testing must be evaluated.
  • Anomalous behavior could involve such aspects of MOV performance as stroke time, stroke smoothness, or change in MOV parameters (such as seat coefficient of friction (COF), stem COF, or motor current).
  • For example, if the stem COF increases above the assumed value in MOV calculations during the valve stroke (such as at flow cutoff), this anomalous behavior must be evaluated to determine if stem lubrication activities need to be adjusted to ensure that the MOV can perform its safety function to close the valve.
  • Licensees should be aware of OM Code requirements in response to MOV anomalous behavior for appropriate action.

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decaBDE Wiring Insulation

  • In response to an initial EPA rule on decabromodiphenyl ether (decaBDE), NRC staff alerted EPA to safety information regarding electrical equipment (such as MOV actuators) that use decaBDE wiring insulation (see NRC Vendor Presentation at ML23158A084 public).
  • EPA revised its rule to avoid safety issues from the unavailability of safety-related electrical equipment, or potential shutdown of nuclear power plants.
  • EPA received public comments on extension of compliance date to allow time for qualification of new cable/wire insulation, allowable use of currently available cable and wire, and broad definition of nuclear power reactors.
  • Safety concerns with EPA rule appear to be on track for resolution.

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Valve Stem Packing Leakage

  • Some valves have developed pin hole leaks in the stem packing area.
  • From operating experience review, licensees have used sealant to address these leaks.
  • Licensees need to evaluate the following:
  • Possible impact on the pressure boundary
  • Potential impact on valve operational capability
  • Consequences of foreign material in fluid system
  • Compliance with ASME BPV Code and OM Code requirements
  • Potential need for relief or alternative from Code requirements
  • Industry guidance for these activities would be helpful.

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2025 ASME/NRC OM Symposium NUREG

  • NRC staff preparing a Proceedings NUREG for the 2025 OM Symposium.
  • The staff has drafted the NUREG and reviewed the papers (with minor edits) submitted at the time of the symposium.
  • The papers provide excellent guidance on IST topics.
  • The staff will include the original abstracts provided by presenters who did not submit a paper.
  • The staff plans to send the draft NUREG to the NRC editors by the end of January to meet a planned June 2026 issuance date.

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QUESTIONS?

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