NUREG-1352, Informs Commission of Status of Activities That NRC Performing & Has Planned to Resolve Concerns W/Performance of MOVs & Check Valves in Nuclear Power Plants

Informs Commission of Status of Activities That NRC Performing & Has Planned to Resolve Concerns W/Performance of MOVs & Check Valves in Nuclear Power Plants

ML20045A729
Person / Time
Issue date:	06/04/1993
From:	Taylor J NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO)
To:
References
RTR-NUREG-1352 GL-89-10, SECY-93-159, NUDOCS 9306110295
Download: ML20045A729 (9)

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POLICY ISSUE SECY-93-159 June 4, 1993 (Information)

FOR:

The Commissioners FROM:

James M. Taylor Executive Director for Operations

SUBJECT:

STATUS OF THE STAFF'S ACTIVITIES REGARDING MOTOR-0PERATED VALVES AND CHECK VALVES PURPOSE:

To inform the Commission of the status of activities that the staff is performing, and has planned, to resolve concerns with the performance of motor-operated valves (MOVs) and check valves in nuclear power plants.

BACKGROUND:

In SECY-90-ll2 (March 22, 1990), " Staff Activities Regarding Motor-Operated Valves and Check Valves," the NRC staff described the status of its activities regarding the performance of MOVs and check valves in nuclear power plants.

In June 1990, the staf f issued NUREG-1352, " Action Plans for Motor-Operated Valves and Check Valves," which includes activities associated with Generic Letter (GL) 89-10, " Safety-Related Motor-0perated Valve Testing and Surveillance," of June 28, 1989.

In SECY-91-143 (May 16, 1991) and SECV-92-205 (June 3, 1992) with the same title as this paper, the staff discussed the status of its activities to help improve the performance of MOVs and check valves.

DISCUSSION:

In NUREG-1352, the staff described activities to help resolve the concerns about the performance of MOVs and check valves. These activities include evaluating the adequacy of current regulatory requirements and guidance, developing inspection guidance, coordinating NRC inspections, conducting regular meetings between the headquarters and regional staff, completing NRC research programs, cooperating with industry groups, evaluating the efforts of the NRC staff and the industry, and participating in organizations to prepare national codes and standards.

In the enclosure, the staff discusses the status of these activities.

CONTACT:

Francis T. Grubelich, NRR NOTE:

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2 In 1992, the staff continued implementing the action plans in l4UREC-1352 for MOVs and check valves.

For example, the staff performed inspections of licensee activities to improve the performance of MOVs and check valves under Temporary Instruction (TI) 2515/109, " Inspection Requirements for Generic Letter 89-10, Safety-Related Motor-Operated Valve Testing and Surveillance,"

and Tl 2515/110, " Effectiveness of Licensee Activities Regarding the Performance of Safety-Related Check Valves," respectively.

The staff found that some licensees had not made sufficient progress in resolving concerns with MOV performance. The staff also found that licensees were in various stages of developing check valve programs and lacked specific guidance for preventative maintenance programs for check valves.

The staff met with industry groups and individual licensees to encourage them to develop programs to improve MOV and check valve performance.

The staff also participates in preparing national codes and standards to improve the performance, testing, and maintenance of MOVs and check valves.

SUMMARY

The staff is continuing to monitor industry activities to improve the reliability and performance of MOVs and check valves by conducting inspections, holding discussions with the industry, and disseminating information on operational experience.

The staff is interacting with industry groups, national standard-writing committees, and individual licensees to identify and resolve problems with MOVs and check valves.

The staff will inform the Commission periodically of the status of MOV and check valve activities.

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Enclosure:

MOV Status Report DISTRIBUTION:

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4 ENCLOSURE STATUS OF NRC STAFF AC11VITIES TO IMPROVE THE PERFORMANCE OF MOTOR-0PERATED VALVES AND CHECK VALVES l

Motor-Operated Valve Activities The NRC regulations require that components that are important to the safe operation of a nuclear power plant, including motor-operated valves (MOVs), be treated.in a manner that provides assurance of their performance. Appendices-i A, " General Design Criteria for Nuclear Power Plants," and B, " Quality j

Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants," to 10 CFR Part 50 include broad-based requirements in this regard.

In 10 CFR 50.55a(g), the NRC requires the licensees to comply. with Section' XI,.

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" Rules for Inservice Inspection of huclear Power Plant Components." of the American Society of Mechanical Er.gineers (ASME) Boiler and Pressure Vessel Code. Nuclear power plant operating experience and MOV research have revealed that the focus of the ASME Code on stroke time and leak rate testing is not sufficient in light of the design of the valves and the conditions under which they must function.

The staff is preparing a request for permission to begin a proposed rulemaking that would resolve weaknesses in the current regulatory requirements and referenced standards.

Upon considering operating experience, the staff issued NUREG-1352, " Action Plans for Motor-0perated Valves and Check Valves," in June 1990 describing actions to organize the activities aimed at resolving the concerns about the performance of MOVs and check valves. These actions include evaluating' the current regulatory requirements and guidance for MOVs, preparing guidance for NRC inspections and coordinating them, completing NRC MOV research programs and implementing the research results, and providing the nuclear industry information on MOVs.

A significant task of the MOV action plan is the staff's review of'the implementation of Generic Letter (GL) 89-10 (June 28,1989), " Safety-Related Motor-Operated Valve Testing and Surveillance," and.its supplements, by -

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In GL 89-10, the staff requested.that licensees help ensure the capability of MOVs in safety-related systems by.

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reviewing MOV design bases, verifying MOV switch settings initially and periodically, testing MOVs under design basis conditions where practicable, l

improving evaluations of MOV failures and necessary corrective action,-and trending MOV problems. The staff requested that licensees complete the testing l

program _under GL 89-10 by June 28, 1994, or within three refueling outages after December 28, 1989, whichever is.later.

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On June 13, 1990, the staff issued Supplement 1'to GL 89-10 to provide detailed information on the results of public workshops held on the GL.

On August 3,1990, the staff issued Supplement. 2 to GL 89-10 to allow l

licensees more time to review and to incorporate the information in l

Supplement 1 into their programs in response to the GL.

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4 In 1988 and 1989, the results of NRC-sponsored MOV tests revealed that more

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thrust was required to operate the tested valves under high-flow conditions I

than had been predicted using industry's standard calculations.

These test results applied directly to the safety function of MOVs used for containment isolation in the high-pressure coolant injection (HPCI), reactor core r

isolation cooling (RCIC), and reactor water cleanup (RWCU) systems of boiling-t water reactor (BWR) plants. On October 25, 1990, the staff issued l

Supplement 3 to GL 89-10, in which it requested each BWR licensee to perform a

'l plant-specific safety analysis and to evaluate the capability of MOVs used for

-l isolation in the HPCI, RCIC, and RWCU systems, and in isolation condenser lines, as applicable, in advance of the GL 89-10 recommended schedule.

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licensees have completed their evaluations of the MOVs within the scope of i

Supplement 3 to GL 89-10, and have modified or adjusted many MOVs to ensure i

they are capable of performing their design-basis function.

l On Fabruary 12, 1992, the staff issued Supplement 4 to GL 89-10 in which it stated that, based on a study of core melt probability, BWR licensees need not I

address inadvertent MOV operation in their GL 89-10 programs. Nevertheless, l

the staff stated its belief that the licensee could obtain a safety benefit by considering the inadvertent operation of MOVs. The staff has contracted Brookhaven National Laboratory to perform a similar core-melt probability study to address valve mispositioning in pressurized-water reactor nuclear power plants.

In performing their GL 89-10 programs, most licensees rely on MOV diagnostic equipment for information on the thrust required to open or close the valve

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and the thrust delivered by the motor actuator. The various types of MOV t

diagnostic equipment estimate stem thrust using different parameters, such as l

spring pack displacement, or strain in the stem, mounting bolts, or yoke.

How the MOV diagnostic equipment is used can significantly affect the safe operation of a nuclear power plant because some licensees determine the j

operability of safety-related MOVs based on the thrust indicated by diagnostic equipment.

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The staff recently obtained new information on the accuracy of MOV diagnostic i

equipment. This new information raises a generic concern regarding the j

reliability of the data provided by MOV diagnostic equipment.

For example, on i

February 3,1992, the MOV Users Group (MUG) of nuclear power plant licensees released Volume 1 of " Final Report - MUG Validation Testing as Performed at 1

Idaho National Engineering Laboratories," in which it indicated that the MOV j

diagnostic equipment that relied on spring pack displacement to' estimate stem thrust did not meet the accuracy claimed.by its vendors. -0n July 8,-1992,-the

-staff issued for public comment proposed Supplement 5 to GL 89-10, in which it requested nuclear power plant licensees to address the recent information on' the inaccuracy of certain MOV diagnostic equipment. More recently, the staff i

learned of increased inaccuracy of.particular MOV diagnostic equipment that relies on valve yoke strain to estimate stem thrust. On March 9,.1993,-the;

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staff met with'the Committee to Review Generic Requirements (CRGR) and is incorporating its comments before issuing Supplement 5 to GL 89-10.

On February 25, 1993, the staff held.a public workshop to discuss GL 89-10 and to answer questions on the inspections of GL 89-10 programs.

Licensees asked 2

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the most significant questions about (1) the scope of GL 89-10 programs, (2) the grouping of MOVs to. share test data, (3) the prioritization of MOVs based on probabilistic risk assessments, and (4) *.he schedule for completing-i the MOV tests to verify design-basis capability as recommended in GL 89-10.

i' The staff prepared a proposed Supplement 6 to GL 89-10 to provide information i

to the lice 15ees ',n these areas. The staff also intends to enclose with Supplement 6 M GL 89-10 general responses to other questions raised during the February 25 public workshop.

The staff issued Temporary Instruction (TI) 2515/109 (January 14, 1991),

" Inspection Requirements for Generic. Letter 89-10, Safety-Related Motor-Operated Valve Testing and Surveillance," to provide guidance for regional l

inspections of the programs being developed by nuclear power plant licensees in response to GL 89-10.

In Part 1 of the temporary instruction, the Office.

of Huclear Reactor Regulation (llRR) provided guidance for performing inspections to evaluate programs developed in response to GL 89-10.

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Part 2, NRR provided guidance for performing inspections to determine the adequacy of the implementation of generic letter programs.

In January 1991, the staff began conducting inspections of the programs being.

developed by licensees in response to GL 89-10. The staff has completed inspections to review the development of MOV programs in response to GL 89-10 f

at each nuclear power plant except Millstone, which was audited in late 1990.

In Information Notice 92-17 (February 26, 1992), the staff summarized the findings of the GL 89-10 inspections conducted up to that time.

i From the inspections of GL 89-10 programs, the staff has found some licensees to be making significant progress toward completing the testing program recommended by the staff.

During the inspection at Comanche Peak in March 1993, the staff found that the licensee had completed most of its dynamic testing under GL 89-10 and planned to complete the. testing by the end of 1993.

At some other facilities, however, the staff found the licensees to have made insufficient progress.

For example, during an inspection in January 1992 at the Vogtle nuclear power plant, the staff found the licensee to have no plans for testing its safety-related MOVs under design-basis conditions as recommended in GL 89-10. After the staff audited the licensee's corporate office in 1992, the licensee established a test plan to validate its methodology for sizing and setting MOVs by the end of 1994.

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Although licensees are making progress in resolving the MOV issue, operating experience continues to reveal problems with the performance of MOVs in nuclear power plants.

For example, in ' January-1992, a residual heat removal i

(RHR) MOV at the Grand Gulf nuclear power plant failed to open'as _a result of pressure locking of the valve bonnet.

In February, April, and May 1992, the licensee for the FitzPatrick nuclear power plant reported the' identification and correction of several MOV deficiencies.

In March-1992, the licensee for the San Onofre nuclear power plant found that two out of four MOVs for containment spray in the emergency core cooling system failed differential l

pressure tests-in Unit 3.

The licensee' shut down San Onofre Unit 2 and found 1

that the applicable MOVs in that unit would not-have been able to perform.

their design-basis functions.

In April 1992, the licensee for the Crystal.

River nuclear power plant reported that a test _ failure of an emergency 3

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i feedwr.ter (EFW) MOV in October 1991 under differential pressure conditions indicated that the MOV and other applicable EFW MOVs would not have been able to perform their design-basis functions.

In May 1992, the Crystal River i

licensee reported that these four EFW MOVs failed to close during differential pressure testing.

In May 1992, the licensee for the Zion nuclear power plant i

determined that the torque switch settings in 15 service water butterfly MOVs in Unit I were inadequate for design-basis conditions, in June 1992, the licensee of Unit 3 for the Indian Point nuclear power plant discovered that the spring packs in two containment isolation MOVs for component cooling water i

return from the reactor coolant pump thermal barrier heat exchanger were inadequate to close the MOVs during a heat exchanger rupture event.

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October 1992, the licensee for the Peach Bottom nuclear power plant determined that cracks in the valve yokes of two MOVs in the RHR system in Unit 2 might 1

have caused both loops of the torus cooling mode of RHR to have been unable to provide containment cooling under certain design-basis events. Also in l

October 1992, the licensee for the Peach Bottom nuclear power plant determined that the redundant MOVs in the HPCI steam supply line of Unit 3 might not have been capable of isolating a high energy pipe break.

The Peach Bottom licensee i

declared the MOVs inoperable and took corrective action.

In February 1993, the licensee for the LaSalle nuclear power plant reported that pressure locking of the valve caused the inboard containment isolation MOV in the RCIC~

7 steam line in Unit 1 to fail to open on February 10 and again on. February 26, 1993, after it was closed for routine maintenance testing.

In February 1993, i

the licensee for the Catawba nuclear power plant reported that a butterfly MOV in the service water system failed to close under flow conditions and that the problem also applied to other butterfly MOVs in the system.

Through a series of meetings between NRR and the regions, the staff revised l

Tl 2515/109 to reflect the results of GL 89-10 inspections and to include r

updated guidance for inspecting the implementation of GL 89-10 programs.

The staff also prepared information on various aspects of GL 89-10 to assist the i

regions in inspecting the implementation of the generic letter.

This information was enclosed in a memorandum on April 30, 1993, from NRR to the regions.

With the updated guidance, the staff is beginning inspections to evaluate the implementation of GL 89-10 programs.

l In Dccember 1992, the NRC Office for Analysis and Evaluation of Operational l

Data (AEOD) completed Special Study AEOD/592-07, " Pressure Locking and Thermal Binding of Gate Valves," in which it concluded that licensees have not taKen i

sufficient action to ensure that pressure locking and thermal binding will not prevent a gate valve from performing its safety function.

In March 1993, the staff issued the AE0D report as Volume 9 of NUREG-1275, " Operating Experience Feedback Report - Pressure Locking and Thermal Binding of Gate Valves." The-NRC regulations require that licensees design safety-related systems to ensure that those systems can perform their safety functions.

In GL 89-10, the staff l

i requested licensees to review the design bases' of their safety-related MOVs.

The staff is revising the inspection guidance for GL 89-10 to request that the inspector verify that the licensee has evaluated the potential for pressure locking and thermal binding of gate valves and has taken action to prevent these phenomena.

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NRR and the Office of Nuclear Regulatory Research (RES) have identified the

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areas requiring further research and analysis to assist the staff in l

evaluating GL 89-10 programs at nuclear power plants. For example, NUREG/CR-5720, " Motor-0perated Valve Research Update," includes important I

information on several areas of MOV behavior under high-load conditions.

RES is funding other research to improve the understanding of MOV performance in j

support of regulatory activities.

t The staff continues to meet with the industry and issue information notices to assist licensees in resolving the MOV issues at their particular facilities.

For example, the staff discussed MOV issues at the 1992 and 1993 Regulatory Information Conferences. The staff also presents the status of NRC activities and concerns at meetings of the MOV Users' Group (MUG) of nuclear power plant licensees.

In July 1992, the staff and the ASME jointly sponsored a symposium to address MOVs and other components.

The staff issues information notices to I

alert nuclear power plant licensees to important information on MOV performance.

l The staff meets regularly with representatives of the Nuclear Management and Resources Council (NUMARC) and the Electric Power Research Institute (EPRI) to discuss an EPRI program to develop a methodology for predicting MOV performance.

EPRI is testing many MOVs in developing the methodology.

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staff will continue to discuss this program with NUMARC and EPRI and will evaluate the results of tests on selected MOVs. NUMARC and EPRI have stated that they will submit the results of the EPRI program as a topical report for 1

the staff to review.

l The staff participates on the national committees responsible for improving codes and standards for MOV performance.

For example, the staff is i

participating on the committee to revise American Society of Mechanical Engineers (ASME) Standard QME, " Qualification of Mechanical Equipment Used in Nuclear Power Plants," to improve the functional qualification requirements for valve assemblies and to revise ASME Operations and Maintenance Standard OM-8, "Startup and Periodic Performance Testing of Electric Motor-Operated Valve Assemblies Used in Nuclear Power Plants."

Check Valve Activities NRC regulations for check valves are specified in 10 CFR 50.55a, and Appendices A and B to 10 CFR Part 50.

Check valve failures and the results of NRC inspections raised concerns over licensees' check valve programs and activities.

In NUREG-1352, the staff issued an NRC action plan for monitoring l

activities and programs for improving check valve performance and operational readiness.

During 1992, the staff continued to implement the action plan.

l In 1991, the staff issued TI 2515/110. " Effectiveness of Licensee Activities Regarding the Performance of Safety-Related Check Valves," to provide inspection guidance for evaluating the check valve activities at nuclear power plants.

NRR prepared a check valve training and inspection manual, and provided training and inspection support-as requested by the regions.

During 1992, the regions inspected 18 operating nuclear plants using the temporary 5

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4 instruction and manual. The inspectors found that licensees were in various stages of developing check valve programs.

The inspectors also found discrepancies in inservice testing, backflow testing omissions, and little evidence of trending activities. Responding to the inspections, licensees 4

began to develop, to improve, and to assess their cneck valve programs and activities. The regions are continuing their inspections. The staff will recommend extending the TI te cover all plants based on the inspection findings.

The staff recognized the need for an accurate and comprehensive industry historical failure review to assess the status of improvement in check valve performance and reliability.

The staff reviewed the published industry's data base of check valve failures. The staff found one major conclusion of the document flawed and considered the document inadequate.

With the assistance of the Oak Ridge National Laboratory (ORNL), RES evaluated check valve failure rates and the factors and conditions affecting failure rates.

The staff is compiling historical check valve information and failure reports from the nuclear plant reliability data system (NPRDS).

For example, the staff is correlating valve failure rates with such characteristics as valve age, valve size, systems of service, valve usage, manufacturer, failure niode, discovery process and detection method, failure area, and extent of degradation. The staff and ORNL presented a summary of the research results during the 1992 NRC/ASME Symposium on Pump and Valve Testing and during the wintar 1992 Nuclear Industry Check Valve (known as NIC) meeting. The staff and ORNL also presented this summary to the ASME work group on check valves.

The staff is issuing the complete failure data base and characteristics in NUREG/CR-5944, "A Characterization of Check Valve Degradation and Failure Experience in the Nuclear Power Industry." The staff and ORNL met with the NIC group to discuss the research. One area of weakness noted in the staff's review was the difficulty in identifying the failure area of the check valve based on information submitted in the NPRDS reports. The ORNL added a cautionary note in the report section dealing with the failure area.

The NIC group will explore changes to the NPRDS data base or to the reporting practices. RES plans to annually update the data base which will be a valuable tool in efforts to assess and improve the reliability and performance of check valves.

The staff encouraged the technical and academic communities, national l

laboratories, industry groups, and individual licensees to present papers on check valve problems and issues at the 1992-NRC/ASME Symposium on Pump and Valve Testing. At the symposium, NRR presented a paper.on NRC Check Valve Action Plans and Inspection Results. A representative _of the ORNL presented a r

summary of the research on the check valve failure data base. The NIC group-presented a paper on the use of non-intrusive test methods.

Industry representatives presented several papers on check valve problems, resolutions, and issues. The staff regularly attends the NIC meetings, and often.is t

invited to attend the NIC steering committee meetings to discuss or present check valve issues of concern to the staff.

In 1992, the NIC group issued a report on a program conducted at the Utah State University Water Research laboratory involving check valves in air t

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5-systems. The NIC group also began a program to test the use of non-intrusive.

methods on check valves in steam systems. Upon reviewing the test results, the NIC group recommended updating the EPRI manual, " Application Guidelines for Check Valves in Nuclear Power Plants," to reflect new knowledge and operational testing experience with check valves.

EPRI's Nuclear Maintenance Applications Center (NMAC) and the NIC group are jointly developing a check valve maintenance manual which will contain guidance on structuring-i preventative or. reliability-centered. maintenance programs While conducting the check valve audits and region inspections, the. staff

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repeatedly found that licensees lacked specific guidance for developing their preventive maintenance or reliability programs.

The staff also found that; these programs were not consistent. Therefore, the staff encouraged EPRI to update the application manual and to develop an NMAC maintenance manual for i

check valves.

The EPRI application guide is a basic reference document used in most plants. The industry will benefit from the updated applications guide and the new check valve maintenance manual.

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The EPRI Monitoring and Diagnostic Center conducted four workshops on check valve maintenance and diagnostics.

EPRI also helped sponsor a Valve Technology Symposium which included sessions on check. valves.

EPRI's Nuclear Maintenance Applications Center (NMAC) conducted its annual review to determine the maintenance issues affecting nuclear utilities based on experience and information from the industry. Check valves were prominent on the list of maintenance issues prioritized by plant maintenance managers and supervisors.

The staff is represented on ASME OM-22, " Working Group on Check Valves," which is responsible for preparing national codes' and standards to improve the performance, testing, and maintenance of check valves. lDuring 1992, the work group proposed two important changes to the check valve testing portions of the ASME Operations and Maintenance (OM) Code. One change allowed the use-of non-intrusive diagnostic testing and the other change involved the disassembly and inspection of samples of check valves. The ASME work group changed the

" disassembly and inspection" provision from a Code alternative to a conditional option only when other positive methods, such as flow ~and non-intrusive testing are not practical. The changes were accepted by the OM Main a

Committee and Board of National Codes and Standards for inclusion in the next Code revision. The work group also completed a draft of a check valve l

standard. The staff will continue to work with the industry in completing the i

OM-22 Standard.

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