ML20198L565
| ML20198L565 | |
| Person / Time | |
|---|---|
| Issue date: | 10/30/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20198L563 | List: |
| References | |
| PROJECT-692 GL-96-05, GL-96-5, NUDOCS 9801160059 | |
| Download: ML20198L565 (15) | |
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SAFETY EVALUATION BY THE OFFICE OF UCL EAR REAC"0R REGUL ATION OF JOINT OWNERS GROLPPR03 RAM Oh MRlwlc VER) :lCATIONE MOTOR OPERAT ED VALVES
1.0 INTRODUCTION
NRC regulations require that components that are important to the safe operation of a nuclear power plant, including motor operated valves (HOVs), be treated in a manner that provides assurance of their performance. A
" General Design Criteria for Nuclear Power Plants," and AppendixQuality B, g>endix A.
Assurance Criteria for Nuclear Power Plants and fuel Reprocessing Plants " to Part 50 of Title 10 of the Code of federal Regulations (10 CFR Part 50) contain broad based requirements in this regard. In 10 CFR 50.55a(f), the NRC requires licensees to comply with Section XI of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code).
Nuclear power plant operating experience, valve oerformance problems, and HOV research have revealed that the focus of the ASME Code on stroke time and leak-rate testing for HOVs was not sufficient in light of the design of the valves and the conditions under which the valves must function. For this reason, on June 28. 1989, the NRC staff 1ssued Generic Letter (GL) 8910.
- Safety Related Motor Operated Valve Testing and Surveillance," asking licensees and permit holders to ensure the capability of MOVs in safety-related systems to perform their intended functions by (1) reviewing MOV design bases. (2) verifying MOV switch settings initially and periodically, (3) testing MOVs under design basis conditions where practicabie.
(4) improving evaluations of HOV failures and necessary corrective action, and (5) trending MOV problems. The NRC staff requested that licensees com)1ete the GL 8940 program within approximately three refueling outages, or 5 years, from the issuance of the generic letter. Permit holders were asked to complete the GL 89 10 program before plant startup or in accordance with the preceding schedule, whic.ever was later. The NRC staff issued seven supplements to GL 89-10 that presented additional guidance and information on the GL 8910 program scope, design basis reviews, switch settings, testing, periodic verification, trending, and schedule extensions.
Recommendation "d" of GL 8910 asked licensees and permit holders to prepare procedures to ensure that correct MOV switch settings are maint61ned throughout the life of the plant, GL 8910 stated that it may become necessary to adjust HOV switch settings because of wear or aging and that additional measures should be taken beyond ASME Ccde stroke time testing to adequately verif Recommendation "y that the switch settings ensure MOV operability.
h" of GL 89 10 asked licensees to evaluate trends in MOV serformance every 2 years or at each refueling outage. Recommendation"j"of GL 8910 stated that licensees should periodically verify MOV capability every 5 years or every 3 refueling outages.
ENCLOSURE W$U N1$k C PDR
I Licensees have completed (or are nearing completion of) their GL 8910 programs to verify the design basis capability of safety related MOVs by reviewing MOV design bases, verifying initial MOV switch settings, testing ,
MOVs under design basis conditions where practicable, and improving evaluations of MOV failures and necessary corrective action. The NRC staff has been closing its review of GL 8910 programs at individnl nuclear plants on the basis of resolution of issues associated with initial verification of MOV design basis capability. As indicated in applicable inspection reports and letters to licensees, the NRC staff has closed its review of the GL 8910 programs at a majority of nuclear plants, and the remaining reviews are nearing completion.
On September 18,1996, the NRC issued GL 96 05, " Periodic Verification of Design Basis Capability of Safety Related Motor 0perated Valves," to provide detailed guidance for the periodic verification of MOV design basis capability, In 61. 96 05, the NRC staff asked licensees to establish a program, or to ensure the effectiveness of the 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.
Licensees were requested to submit a written response within 60 days indicating whether or not the GL 96 05 requested actions would be implemented.
Within 180 days, or upon notification to NRC of completion of GL 89-10 *
(whichever is later). licensees were requested to submit a written summary descri) tion of the MOV periodic verification program established in accordance with G. 96 05 or the alternative indicated in the 60 day response. GL 96 05 supersedes GL 89 10 and its supplements with regard to MOV periodic
- verification.
2.0 JOINT OWNERS GROUP PROGRAM ON MOV EERIODIC VERIFICATION In response to GL 96 05, the Boilir.g Water Reactor Nners Group (BWROG). the Westinghouse Owners Group (WOG), and the Corrbustion Engineering Owners Group (CEOG) are jointly sponsoring an industry wide capability of MOVs established under the GL 89 10 program programs to help maintainatthe implemented individual nuclear Sower plants. This program is referred to as the Joint Owners Group (J0G) )rogram on MOV Periodic Verification. On March 3, 1997.
WOG submitted Topical Report MPR 1807 (Revision 0, February 1997), " Joint BWR and Westinghouse Owners Group Program on Motor 0perated Valve (MOV) Periodic Veri fication. " On March 7. 1997. BWROG submitted Licensing Topical Report NEDC 32719 (March 1997), *BWR Owners' Group Program on Motor Operated valve (MOV) Periodic Verification." The topical reports on the J0G program submitted by the different owners groups are essentially identical and are referred to herein as the " topical report."
On July 23, 1997. CEOG submitted Revision 1 to Topical Report MPR-1807. " Joint BWR, Westinghouse and Combustion Engineerin Operated Valve (MOV) Periodic Verification.g The Owners' Groupbetween only change Program on Motor.
Revision 0 and Revision 1 of the topical report was indication of the participation of CEOG in the J0G program.
On July 30. August 6, and August 12, 1997, respectively. BWROG. CEOG, and WOG submitted Revision 2 to the topical report on the J0G P. rogram on MOV Periodic 2
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, Verification. The owners groups also submitted a written response to NRC staff coments on the J0G program.
As described in the topical report, J0G developed its program on MOV periodic ;
verification in response to GL 96 05 to obtain benefits from the sharing of information between licensees from GL 89 10 programs. Thestatedobjectives of the J0G Program on MOV Periodic Verification are to (1) provide an approach i for participating licensees to use imediately in their GL 96 05 programs, (2) develo) a basis for addressing the potential age related increase in required t1 rust or torque under dynamic conditions, and (3) use the developed basis to confirm, or if necessary to modify, the applied a Specific elements of the J0G program are (1) providing an " interim"pproach, periodic test program consisting of diagnostic testing of MOVs under stati: (nc flow) conditions for participating licensees to use in response to GL 96 05, (2) conducting a dynamic test program consisting of diagnostic testing of MOVs under differential pressure and flow conditions over the next 5 years to ;
identify potential a ;
operate gate, globe,ge andrelated butterflyincreases valves under in required dynamicthrust and torque conditions, and to ~
(3) evaluating the information from the d modify the interim program assumptions. ynamic testing program to confirm or ,
The stated benefits of the J0G program for participating licensees were conservation of resources, enhancement of pro experience among the aarticipating licensees, gram thoroughnessofand and establishment sharing of a solid technical basis for tie long term MOV Periodic Verification Program from the large sample of shared H0V test data. J0G suggested that benef1ts to the NRC included a generic ap> roach that conserves NRC resources, implementation of a uniform approach to G. 96 05, and assurance that the test findings are shared across the industry.
The topical report describes the objective of the interim MOV periodic test program as assuring that the setup of the MOVs remains consistent with GL 8910 criteria with additional margin for age related degradation during conduct of the J0G dynamic testing arogram. The elements of the interim program are (1) continuation of ASME Inservice Testing (IST) Program stroke-time testing and (2) performance of static diagnostic testing on a frequency based on functional capability (age related degradation margin over and above the margin for GL 8910 evaluated parameters) and safety significance.
The topical report describes the objectives of the J0G dynamic test program as determination of the degradation related trends in dynamic thrust and torque, and use of dynamic test results to adjust the interim prog: A if warranted.
The J0G dynamic test program will be implemented concurrent with the J0G interim static test program. The elements of the J0G dynamic testing program comprised the following: (1) identification of conditions and features that could potentially lead to MOV degradation. (2) definition and assignment of valves for dynamic testing. (3) testing valves three times with at least a 1 year interval between valve specific tests according to a standard test specification over a 5 year interval. (4) evaluttion of results of each test, and (5) evaluation of collective test results. J0G will establish a feedback l nechanism to ensure timely sharing of MOV interim and final test results i
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. between participating licensees, and prorr$t individual licensee actions to adjust their own HOV periodic verification programs, as appropriate.
In the last phase of the program, J0G will evoluate the test results to validate the assumptions in the interim program to establish a long4erm HOV Periodic Verificatior. Program to be implemented by the participating t licensees. J0G contracted with MPR Associates, Inc., to assist in the development of the periodic verification program, and in the management of the utility test database, and test data analysis and evaluation.
3.0 EVALUATION The HRC staff review of the J0G Program on MOV Periodic Verification was based on submittals from the owners groups and information obtained from public meetings. Staff from the NRC Office of Nuclear Reactor Regulation (NRR) and the NRC Office of Nuclear Re participated in the review. gulatory In letters Research (RES),
dated June and13.
12 and an 1997, RES consultant, respectively, the NRC staff provided coments to BWROG and WOG on the J0G 3rogram. On June 24 and 25. 1997, NRC staff members from the NRR Hechanical Engineerin Branch and the RES Electrical, Materials, and Mechanical ingineerin Branch, and an RES consultant, met publicly with J0G r representa ives at NRC headquarters in Rockville, Maryland, to discuss the NRC staff comments. On July 30, August 6, and August 12. 1997, respectively. the BWROG. CEOG and WOG submitter Revision 2 to the topical report on the J0G Pregram on HOV Periodic Verification. The owners groups also submitted a written response to NRC staff comments on the J0G program.
The NRC staff has pre >ared this-safety evaluation (SE) on Revision 2 to the topical report descri)ing the J0G Program on HOV Periodic Verification. J03 has committed to maintain the program description as a controlled document so that it will be the same for all p6,ticipants. (See NRC Coment S on the Jr.ki Program en MOV Periodic Verification provided in the NRC letter dated Junc 12, 1997, and the J0G response to that comment submitted in a letter from BWROG dated July 30. 1997, from CEOG dated August 6, 1997, or from WOG dated August 12. 1997.)
Many licensees have referenced the J0G Pr ram on HOV Periodic Verification in their individual responses to GL 96 05. J representatives havo indicated that licensees of 93 reactor units are participating in the J0G program. This re) resents an increase in the number of licensee partici) ants since the su)mittal in early 1997 of licensee descriptions of HOV seriodie Verification Programs in response to GL 96 05. J0G indicated that participating licensees will be requested, following issuance of this SE, to individually notify the NRC of their plans to implement the J0G program described in Revision 2 of the topical reports. The NRC staff's review of the J0G program involved the entire program and not individual portions. The NRC staff will expect aarticipating licensees to justify any deviations from the J0G program. (See Comment 2 and J0G response.)
The topical report states that the J0G program is based on each participating licensee defining and justifying its scope of valves to be considered for GL 96 05. The topical report notes that participating licensees will need to 4
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. document and justify any changes in the scope of the GL 96 05 program in accordance with plant procedures, for example, the NRC staff will expect that licensees assuming HOVs to be operable when in their non safety positions will justify the capability of those HOVs to return to their safety position, The topical report states that the scope of the J0G pro] ram is intended to cover most types of gate, globe, and butterfly valves at participating plants at least with regard to key valve features that are related to potential degradation. The topical report states that each participating licensee is responsible for identifying any valves that are outside the scope of applicability of the J0G program and for addressing those valves on a separate basis, The NRC staff notes that participating licensees will be responsible for determining that their valves (and materials) and service conditions are covered by the J0G program and for justifying a separate periodic verification arogram for those valves or conditions outside the J0G program. (See Comment 6 and J0G. response.)
Sufficient data will be necessary to justify the final test criteria for all valve types and materials (including (neir service conditions) within the scope of the J0G program. Some valves or materials intended to be included in the J0G program may not have sufficient data to justify the final test criteria and may need to be deleted from the program scope after evaluating their test data. If any valve types, materials, or service conditions are deleted from the J0G program scope, participating licensees will be responsible for justifying a separate periodic verification program for those valves, materials and service conditions. For example, J0G will need to evaluate whether high temperature globe valve performance can remain in the scope of the J0G program. (See Coments 7, 8, and 23 and J0G responses.)
RES is sponsoring tests to study age related degradation of Ste111te 6 materials used for most HOV sealing surfaces. RES is also sponsoring analytical studies of the potential increase in MOV failure probability based on aging rates and margin uncertainty with longer test intervals. These l
ongoing research efforts may provide information applicable to the J0G program. NRC Cll make the results publicly available as soon as the research is completed and reviewed. J03 may need to consider some redirection of its activities based on the results of the research.
The J0G program comprises three distinct phases: (1) interim periodic test program. (2) dynamic test program, and (3) long term periodic test program.
These phases and applicabic NRC review results are discussed below:
A. Interim Periodic Test Program In response to GL 89 10, licensees have been verifying the design basis capability of their safety related HOVs, For the long term, licensees are establishing to GL 96 05, to programs maintaininthe response design to GL 89 basis 10 and,of capability more recently, these HOVs. inToresponse assist licensees in these efforts, the first phase of the J0G Program on MOV Periodic Verification establishes an interim periodic test program for each participating licensee to implement during performance of the J0G dynamic test program. The topical report describes the interim periodic test program as initiation of HOV static testing with suitable diagnostic test equipment on a 5
. frequency that depends on the safety significance (risk) of the valve and on the functional capability (margin) of the valve. Except where relief is requested and approved, the NRC staff will diso expect licensees to continue -
testing HOVs in accordance with the applicable plant IST program as required by the NRC regulations in 10 CFR 50.55a and the ASME Boiler and Pressure Vessel Code.
The J03 Program on MOV Periodic Verification does not include consideration of non mandatory ASME Code Case OMN 1, " Alternative Rules for Preservice and Inservice Testing of Certain Electric Motor Operated Valve Assemblies in LWR
[ Light Water Reactor) Power Plants,' which allows replacement of quarterly stroke time testing for HOVs within IST programs specified by the ASME Boiler and Pressure Vessel Code. J0G representatives have stated their intent to evaluate the application of the J0G program to ASME Code Case OMN 1 over the long term. Individual licensees are responsible for requesting any proposed implementation of ASME Code Case OMN 1 as relief from their IST requirements.
(See Comment 4 and J0G response.)
The topical report specifies that static diagnostic testing will be conducted under the interim periodic test program on the following refueling cycle frequency:
Risk and Margin Low Hargin Medium Margin High Margin Categories MOVs MOVs MOVs High Risk 1 cycle 2 cycles 3 cycles Medium Risk 2 cycles 4 cycles 6 cycles
- Low Risk 3 cycles 6 cycles
- 6 cycles *
- Not to exceed 10 years.
The topical report defines low margin as less than 5 percent, medium margin as equal to or greater than 5 but less than 10 percent, and high margin as equal to or greater than 10 percent. The topical report allows the risk categories to be based on owners grou) or utility specific criteria. The topical re) ort allows plants with '2 monti fuel cycles to double the frequency criteria Jut not to exceed 10 y .,s.
The topical report states that the interim seriodic testing program is intended to provide confirmation that each 10V is set up in a manner that ensures positive margin for operability. J0G has stated that the frequency and margin provisions of the interim static test criteria are based on engineering judgment, and operational and test experience. The risk and margin criteria are preliminary and will be confirmed by the J0G dynamic test program.
The topical re) ort states that the interim testing program provides confirmation tlat setup is consistent with operability and that all evaluated HOVs are expected to be operable. The topical report indicates that it is not 6
, intended that the risk criteria be used to avoid addressing operability. The NRC staff considers the topical report to indicate that licensees must ensure '
that each MOV in the J0G program will have adequate margin (including contideration of aging related degradation) to remain operable until the next scheduled test, regardless of its risk categorization or safety significance. .
(See Coment 10 and J0G response.)
The topical report states that the methoduvogy and discrimination criteria for l placing valves in specific risk categories are the responsibility of each '
participating licensee. For determining the risk significance of individual 40Vs. the topical r? port refers members of the BWROG Inte Regulation Comittee to BWROG Topical Report NEDC 32264. grated Application of Risk Based Probabilistic Safety Assessment to Generic Letter 89 10 Implementation " where i the report is applied in accordance with an NRC SE dated February 27. 1996.
In that SE. the NRC staff approved with certain conditions the use of BWROG related MOVs for Topical testing in Report responseNEDC-32264 to GL 89 10. The forNRC the prioritization staff considers tof safety he application o NEDC 322N also appropriate for programs developed in response to GL 96 05 for licensees that participated in the development of NEDC-32264. Applicable .
licensees will need to review their plant specific pro to verify proper application of the BWROG methodology. grams (including scope)
As stated in the NRC SE on NEDC 32264. the NRC staff review of the BWROG methodology is only applicable to the licensees participating in the development of that methodology. J0G states in its topical report that other licensees participating in the J0G specific or other generic criteria, programwhich need will betoexpected be justified, to use plant-for ranking MOVs. The NRC staff will expect licensees that did not participate in the development of NEDC-32264 to justify their MOV risk categorization methodology as part of their implementation of the J0G program. By letter dated June 2, 1997, WOG submitted for NRC review Revision 0 of WOG Engineering Report V EC-1658, " Risk Ranking Approach for H' tor 0perated Valves in Response to Generic Letter 96 05," which presents a methodology to rank MOVs according to their risk importance. The NRC staff is reviewing the WOG methodology for possible endorsement. Other owners groups have not submitted an MOV risk ranking methodology for NRC review. (See Coment 12 and J0G response.)
The Electric Power Research Institute (EPRI) develo>ed the MOV Performance Prediction Methodology (PPM) to define a bounding t1 rust (or torque) required to o PPM.perate a gate, globe, or butterfly valve within the scope of the EPRI MOV The NRC staff conewded that the EPRI M0V PPM constituted an acceptable methodology to predict thrust and torque requirements following the conditions and limitations in an SE dated March 15, 1996, and an SE supplement dated February 20. 1997. J0G acknowledges the use of the EPRI MOV PPM b licensees in predicting thrust and torque requirements for sizing and settin MOVs. In Section 4. the topical report states that an MOV is considered to ave "high margin" within the J0G interim test program provided that (1) default coefficients are used in the EPRI MOV PPM, (2) the guidance in the EPRI documentation and NRC SE are met, (3) the valve is predictable as defined in the EPRI M0V PPM. (4) the margin as defined in the J0G program is greater than zero, and (5) the need for maintenance is considered by the plant and maintenance is performed where required to keep the MOV in good working order.
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Although a prediction from the EPRI HOV PPM contains some margin for increases in required thrust or torque, the NRC staff will expect licensees to address degradation in actuator output thrust in determining whether an HOV should be considered to have high margin. (See Coments 13,14 and 15 and J0G responses.)
The topical report defines margin as the difference between available thrust (or tor torque)que) capable demanded of being by the valve delivered by the under design actuator basis andThe conditions. required topicalthrust (or report states that the margin for gate and globe valves is calculated from the adjusted actuator output thrust minus the adjusted required thrust, and the margin for butterfly valves is calculated from the adjusted actuator output torque minus the adjusted required torc,ue. The topical report lists the following as example adjustments: test equipment inaccuracy, torque switch repeatability, rate of-loading, spring degradation, and'. seat degradation, hardening).
(e.g. pack relaxation, stem lubricantLicense differ pproaches in applying uncertainties in thrust and torque setup calcult as in their MOV programs. These differing approaches can result in differei, amounts of margin when a) plied to the same MOV. The topical report states that each plant is responsi)lc for appropriately applying the adjustments to actuator output torque or thrust in calculating margin in the J0G program. Thi.s is particularly important because of the small margins allowed by the J03 interim periodic test program. For example, the uncertainties torque switch of test equipment repeatability, inaccuracyspring late of-loading, at static packtorque switchan relaxation, trip,d stem lubricant degradation are to be used to adjust the actuator output thrust.
Licensees may retain their approach for MOV setup if it is justified that H0Vs are properly evaluated for operability. However, when establishing test frequencies under the J0G program, the NRC staff will expect licensees to apply uncertainties as appropriate to the output or required thrust (or torque). (See Comment 9 and J0G response.)
The J0G interim program establishes a general test frecuency of 1 to 6 cycles (with a maximum of 10 years) on the basis of margin anc safety significance for the specific HOV. These test frequencies are generic and might not be applicable to every MOV within a licensee's HOV Periodic Verification Program.
In addition to the general test frequency established in the J0G program, the -
NRC staff will also expect licensees to consider the operating history of the specific valve, and its application and environment, to determine if the test frequenc If an HOV has a planned test schedule beyond 5 years,ytheis a)propriate.
NRC staff will expect the licensee to group that HOV with other HOVs that will be tested within 5 years in order to confirm the assumptions supporting the longer test interval. (See Comment 11 and J0G response.)
The topical report states that the J0G program is based on the premise that each licensee is responsible for determining the margins that need to be included for actuator capability degradation, and for justifying and implementing these margins. Degradation of actuator output thrust and torque is not within the scope of the J0G program. J0G representatives have stated that actuator output capability was not included in the J0G program because of significant differences between the individual licensee programs in maintaining the output of their actuators. As a result, J0G is relying on each participating licensee to provide reliable predictions of actuator 8
j output. With the focus of the J0G program on the potential age related increase in the thrust and torque required to operate the valves, the NRC staff will expect licensees to address apart from the J0G program the thrust and torque delivered by the motor ectuator, including consideration of NRC Information Notice 96 48. ' Motor Operated Valve Performance Issues," and followup industry and NRC information, further, the NRC st6ff will expect licensees to address the effects of aging on rate of-loading and stem friction coetficient under dynamic conditions. Therofore. licensees are responsible for justifying their actuator out>ut predictions, includina stem friction coefficient and load sensitive beiavior, as part of their MOV programs. On the basis of GL 89 10 inspections, some licensees are planning to resolve weaknesses in their assumptio 4 for stem friction coefficient or load sensitive behavior as part of Joeir long term MOV 3rograms. The limited J0G dynamic testing at specific plant sites might not >e sufficient to justify the
, actuator output. capability assumptions for some licensees. Consequently, licensees will be responsible for supplementing the J0G testing program as necessary to resolve any identified weaknesses in actuator capability assumptions. (See Coment 21 and J0G response.)
B. J0G Dynamic Test Program In parallel with the first phase of interim static diagnostic testing, the topical report states that the second phase of the overall J0G program is a dynamic testing program that involves performance of d MOVs at participating plants over a period of 5 years.ynamic The J0G tests of selected dynamic test program will involve diagnostic testing of a few MOVs at each participating plant under carefully controlled conditions. J0G intends these dynamic tests to provide the technical basis to verify, or if necessary to modify, the criteria in the interim test program. J0G has develo ed a test specification to ensure consistency in the data obtained from multi le sites. In developing the test matrix for the second phase of its program. OG has identified various mechanisms that could potentially cause an increase in thrust requirements as a result of age related degradation. J0G has stated that the MOVs to be tested cover the range of valve design factors (e.g., materials) and application factors (e.g., stroking history or water quality) that can potentially affect degradation. The NRC staff notes that participating licensees are responsible for identifying any valves that are outside the scope of the J0G dynamic test program, such as in terms of valve manufacturer, size, type, or service conditions and for justifying a separate MOV Periodic Verification Frogram for valves or, conditions outside the J0G program.
The topical report states that dynamic testing of MOVs can provide additional information for evaluating margin beyond that provided by static testing. The topical report provides as examples the following information that can be obtained from dynamic testing: (1) required dynamic thrust for gace and globe valves (expressed as valve factor) or required d valves (sum of bearing and hydrodynamic torque),ynamic torque in butterfly (2) eff pressure on unwedging thrust (gate valves), (3) rate of-loading for gate and globe valves, and (4) stem friction coefficient under dynamic conditions for gcte and globe valves. Dynamic test results will be used to understand potential degradations in required dynamic thrust or torque. The transfer of information on unwedgirg thrust from one valve to another might be unreliable 9
4 because of valve specific characteristics. (See Comment IB and J0G response.)
The topical report states that changes in rate of loading cre not considered in the dynamic testing program, J0G considers the potential time related degradation of thrust at torque switch trip under dynamic conditions to be se>arately addressed by considering stem lubricant degradation. Stem lu)ricant degrad tion under dynamic conditions is outside the scope of the J03 program, The ..RC staff will expect licensees to address the potential for age related changes in rate of loading and stem lubricant degradation (and other potential age related effects such as spring pack relaxation, and actuator and switch lubrication degradation) as part of their long term HOV programs.
The topical report states that the dynamic test program consists of a series of in plant MOV tests performed under dynamic conditions. The d program is said to include 100 gate valves 30 butterfly valves,ynamic test 10 unbalance disk globe valves, and 10 bala,aed disk globe valves. The topical report states that each valve is to bc tested a minimum of three times under nominally identical dynamic conditions. The tests are to be separated by at least 1 year with all three tests completed by 5 years after the start of the J0G program, The topical report allows tests conducted under previous programs (such as GL 89 10) to be used as the initial test for the J0G dynamic test program. The test interval will be as long as possible within the parameters of the program to provide a better opportunity to observe age related degradation. Stroke information for the previous 2 years or to the previous J0G test, whichever is longer, will be collected for evaluation.
The 4RC staff believes that more extensive historical information on the test valves might be helpful in evaluating the test results W their implication.
The J0G representatives stated that more detailed information may be requested for specific valves on the basis of the results from the testing program.
(See Comments 19 and 20, and J0G responses.)
J0G developed a test matrix on the basis of the valve types and service conditions in use at muclear plants, and on the basis of the availability of valves that can be n,.amically tested in situ at participating plants, The topical report states that the intent of the test matrix is to provide data covering a range of each key factor influencing potential degradation. These potent 1al factors include cumulative dynamic strokes, fluid environment and temperature, disk and seat material pair, guide material sair, valve factor, stem orientation for gate valves: cumulative d environment and temperature for globe valves;and ynamic stroces, bearing fluid mater 1L1, particulate level in fluid medium, and stem orientation for butterfly valves.
Manufacturers covered in the J0G program are Aloyc,>, Anchor / Darling, Borg Warner, Copes Vulcan, Crane, Pacific. Powell, Velan, Walworth, and Westinghouse for gate valves: CCI, Copes Vulcan, fisher, Hamel Dahl, Valtek, and Yarway for balanced disk globe valves: Anchor / Darling Borg Warner, Edward, Velan, Walworth, and Yarway for unbalanced disk globe valves: and Allis Chalmers, Blf, Contromatics, Fisher, Jamesbury, and Pratt for butterfly valves. In response to NRC staff coments, J0G provided an up to date list of valves to be dynamically tested as part of the J0G program, including unbalanced disk globe valves, (See Coments 22 and 24. and J0G responses.)
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The dynamic test seguence in the J0G program includes a static test preceding the dynamic test. The NRC staff has questioned the potential effect of this static test on thc results of the dynamic test. J03 stated that static testing is typically performed imediately preceding dynamic testing to calibrate the diagnostic equipment. However, J0G stated that some dynamic tests may be conducted without an immediately preceding static test. J0G will evaluate this information, to the extent possible, to determine whether the receding a dynamic test might affect the conclusions of the J0G program. The i performance of a static test imediately this issue on the basis of J0G data and NRC research results.
The topical report indicates that test results will be periodically assessed and evaluated to ensure that findings are addressed in the J0G program and transmitted to participating licensees. If adjustments are warranted to the program or to tie interim criteria, the to)ical report states that these changes will be made and comunicated to tie participsnts. The topical report states that, for information supplied by J0G. it is the responsibility of the individual plants to evaluate t1e applicability and impact of that information for their valves. The NRC staff notes that this includes responsibility for satisfaction of the reovirements to notify the NRC under the provisions of 10 CFR Part 21, evaluation of experience for applicability, and consideration of effects on component operability, as appropriate. (See Coment 3 and J0G response.)
Appendix D to the topical report contains a standard approach for analysis of dynamic test data by participating licensees to calculate valve factor (gate end globe valves) and bearing friction coefficient (butterfly valves) in a consistent manner. For example, maintenance performed on HOVs in the testing program may affect the ability to identify age related degradation. In response to this issue, J0G emphasized that it will evaluate all test data for reliability. (See Coments 26 to 34, and J0G responses.)
Each participating licensee will submit a test documentation package to J0G.
The approach to be applied in the J0G program for analyzing and evaluating dynamic test data ansists of (1) plant evaluation. (2) J0G receipt evaluation, and (3) J0G formal periodic evaluation.
(1) Plant Evaluation After testing each MOV in the J0G program, the participating licensee will analyze the data using plant procedures and the J0G analysis method specified in the topical report. The licensee will compare the performance of the tested valve with previous test results on the basis of both plant and J0G methods. The topical report states that increases in required thrust will be evaluated at each plant as part of the normal trending and data evaluation program. Participating licensees are.
responsible for this trending and evaluation of valve test data. The topical report requires participating licensees to submit the test documentation package to the J0G program within 3 months of test completion.
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l (2) J0G Receipt Evaluation i V)on receipt of the test documentation packages, the J03 program reviews ;
tie packages for completeness, accuracy, and consistency. The J0G j receipt evaluation involves comparing the test results with 3revioas tests, with any observed trends with similar valves, and wit 1 the J0G program criteria. J0G's annual review will include assessment of the :
threshold criteria for imediate evaluation of test data. (See Coment 16 and J0G response.)
1 (3) J0G Formal Periodic Evaluation when a potentially lar The topical rate has beenreport states observed for a that,lve va or class of valves,gethe J0Gdegradation program will determine if further evaluation, or potential modification of the program or interim criteria. is required. If action is needed, the J03 pro;lram will prepare and comunicate the information to the participating licensees. An industry group overseeing the J0G program will meet once a year to review test data and to determine if there are any necessary corrective actions to the program or to the interim criteria. The J0G program will notify participating licensees of the results of the annual meeting and any necessary corrective actions.
The J0G intenm test program allows small margins to be available to accommodate potential age related degradation. As a result, the NRC staff will expect the J0G program to provide prompt feedback of test results to participating licensees to ensure that the dynamic test information continues te support the established testing frequency in the interim program. For example, the interim program allows a margin below 5 percent for some valves:
but the J0G dynamic test program does not promatly address changes in thrust or torque requirenents less then 10 3ercent. 41th the periodic information to be provided by the J0G p.ogram, the iRC staff will expect participating licensees to address these program updates.
Some HOVs have tentative test schedules beyond 5 years in the interim test program. The NRC staff will expect J0G to evaluate dynamic test data within the 5 year program so that applicable MOVs will be tested w4 thin 5 years if test 1sults do not support longer test intervals. (See Comment 17 and J0G respv..se. )
J0G and the NRC staff have agreed to meet periodically to discuss the progress and findings of dynamic testing within the J0G program.
C. Long Term Periodic Test Program For the third >hase of its program, J0G will evaluate the dynamic test results to determine tie specific mechanisms that affect thrust requirements. On the basis of the dynamic test results. J0G will establish the final test criteria for MOV periodic verification. - J0G will prepare a revision to (or a replacement report for) the topical report on the J0G Program for MOV Periodic Verification s
-justification.pecifying the final MOV periodic verification criteria and their The NRL staff will review the final test criteria for the 12
long term HOV Periodic Verification Program, and their justification, when these are incorporated into the topical report. The NRC staff will update this SE at that time. (See Comment 1 and J0G response.)
4.0 RELATIONSHIP TO GL 96-05 For licensees participating in the J0G Program on MOV Periodic Verification, the NRC staff intends to rely to a significant extent on the comitment of those licensees to implement the guidelines in the J0G topical report and this SE in evaluating the adequacy of their response to Gl. 96-05. In discussions with the NRC staff, J0G has indicated that participating licensees will update their commitments to the J0G orogram followiag issuance of this SE. In ,
updating its comitments to the J0G program, it would be helpful if licensees '
described their implementation of the jog program (such as their MOV risk ranking a>proach), consideration of as outside tie scope of the J0G program,and pects im of MOV periodic verification during completion of their GL 89-10 program.plementation After receiving aoflicensee's commitments made updated comitments regarding the J0G program, the NRC staff plans to prepare c an SE for each licensee with respect to its response to GL 96 05. Prior to or following issuance of plant specific SEs, the NRC staff may perform inspections at nuclear power plants to evaluate the development and implementation of the J0G program. These inspections might also evaluate licensee consideration of aspects of MOV periodic verification outside the scope of the J0G program and implementation of comitments made by licensees during completion of their GL 89-10 programs.
For licensees not participating in the J0G program, the NRC staff will evaluate the MOV periodic verification prograrr.s at those facilities through NRC staff review of licensee submittais and the performance of on site NRC inspections, as necessary. Based on the results of the review and inspection activities, the NRC staff will prepare an SE on the MOV periodic program developed and implemented by those licensees to evaluate the adequacy of their response to GL 96 05.
5.0 CONCLUSION
S The NRC staff has reviewed the J0G Program on MOV Periodic Verification s)onsored by BWROG, WOG and CEOG which provides an industry wide approach for tie periodic verification of the design basis capability of safety related HOVs in response to GL 96-05. This program is described in a single report submitted separately by BWROG as Licensing Topical Report NEDC 32719 (Revision 2), "BWR Owners' Group Program on Motor-Operated Valve (MOV)
Periodic Verification " on July 30, 1997: by CE0G as Topical Report MPR-1807 (Revision 2), " Joint BWR Westinghouse and Combustion Engineering Owners Group Program on Motor-Operated Vaive (MOV) Periodic Verification," on August 6,
Westinghouse Valve (MOV) Periodic andVerificat Combustion on." on En ineering August 12.1 Owners Groug97 Program on Motor 13
- d. . . _ _ .
The conditions and limitations described in this SE enable the NRC staff to conclude that the J0G Program on MOV. Periodic Verification provifies an acceptable industry wide response to GL 96 05 for valve age related degradation. Among the more significant conditions and limitations for NRC staff acceptance are the following:
A. J0G must submit for NRC review and approval a re ision to (or replacement re> ort for) the to)ical report following the J0G dynamic test program w11ch describes tie final test criteria for the long term
- MOV Periodic Verification Program, and the justification for those criteria.
B. Licensees that did not justify their MOV risk participate in themethodology rategor12ation developmentas ofpart NEDC of their-32264 must implementation of the J0G program. The NRC staff is reviewing an MOV risk ranking methodology submitted by WOG for possible endorsement.
C. Licensees implementing the J0G program must address the NRC evaluation and conclusions on the J0G program provided in this SE (and in the supplement to be prepared after the results of the J0G dynamic test-3rogram are evaluated). J0G indicated that
>e requested, following issuance of this SE to participating licensees individually will notify the NRC of their plans to im31ement the J0G program described in Revision 2 of the topical resort. 3articipatinglicenseesmustjustifyany deviat1ons from tie J03 program.
D. Licensees implementing the J0G program must determine any valves that are outside the scope of applicability of the J0G overall program or the J0G dynamic test program (or deleted from the J0G program scope), such as in terms of valve manufacturer, size, type, materials, or service conditions, and must justify a separate program for MOV periodic verification for those valves, materials, and service conditions not encompassed by the J0G program.
E. Licensees implementing the J0G program must address the information provided as a result of the J0G program during and following the J0G dynamic test arogram. This responsibility includes notification of the NRC under 10 CFR Part 21 evaluation of experience for applicability, and' consideration of effects on component operability, as appropriate.
F. Licensees must ensure that each MOV in the J0G program will have adequate margin (including consideration for aging-related degradation) to remain operable until the next scheduled test regardless of its risk categorization or safety significance, 14
s G. Licensees may retain their approach for M0V setup where it is justified that MOVs cre properly evaluated for operability. However, when establishing test frequencies under the J0G program, licensees must ap ly uncertainties as appropriate in calculating actuator output or
-va ve required thrust (or torque).
H. With the focus of the J0G program on the potential age related increase in the thrust and torque required to operate the valves, licensees must address apart from the J0G program the thrust and torque-delivered by the motor actuator. Licensees must address the effects of aging on-rate of-loading and stem friction coefficient under dynamic conditions, and other potential age related effects such as s and actuator and' switch lubrication degradation. pring-pack relaxation, I. The dynamic test sequence in the J0G program includes a static test preceding the dynamic test. J0G will evaluate available test information, to the extent possible. to determine whether the performance of a static test imediately preceding a dynamic test might affect the conclusions of the J0G program. The NRC staff will continue to monitor this issue on the basis of J0G data and NRC research results.
J. MOVs with scheduled test frequencies beyond 5 years will need to be .
grouped with other MOVs that will be tested on frequencies less than 5 years in order to validate assumptions for the longer test intervals.
This review must include both valve thrust (or torque) requirements and actuator output capability.
Principal Contributors:
Thomas G. Scarbrough, NRR Dr. Gerald H. Weidenhamer RES Robert Steele. RES consultant s
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