ML20198L676
| ML20198L676 | |
| Person / Time | |
|---|---|
| Issue date: | 10/30/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20198L638 | List: |
| References | |
| PROJECT-691 FACA, GL-96-05, GL-96-5, NUDOCS 9801160091 | |
| Download: ML20198L676 (15) | |
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SAFETY EVAllATI N BY T4E F:fCF :: r di'l itA REANR R n I ATION OF JDINT ME is GROLP WP t
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1.0 INTRODUCTION
i NRC regulations require that cogonents that are imortant to the safe j
operat'on of a nuclear power plant, including motor-operated valves (MOVs), be tretted in a manner that provides assurance of their performance.
ix A;
" General Desi!)n Criteria for Nuclear Power Plants." and Appendix 8.
ality i.
Assurance Cr1Seria for Nuclear Power Plants and Fuel Reprocessing Plants " to-Part-50 of Title 10 of the Code of Fed 6,al Regulations (10 CFR Part 50) contain broad based requirements in this repard.
In 10 CFR 50.55a(f), the NRC j
requires licensets to cogly with Section X of the American Society of Nechanical Engineers Boiler and Pressure Vessel Code (ASME Code).
l Nuclear power plant operatin)he focus of the ASME Code on stroke time andexpeI research have revealed that c leak rate testing for MOVs was not sufficient in light of the design of the
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valves and the conditions under which the valves must' function.
For this reason, on June 28,1989, the NRC staff issued Generic Letter (GL) 89 10,
" Safety Related Motor Operated Valve Testing and Surveillance " askin) licensees and permit holders to ensure the capability of MOVs in safe;y.
j related systems to perform their intendeo functions Dy (1) reviewing MOV design bases,-(2) verifying MOV-switch settings initially and periodically, j
(3) testing MOVs under design basis conditions where practicable.
(4)' improving evaluations of MOV failures and necessary corrective action, and 4
(5) trendina MOV problems. The NRC staff requested that licensees complete the GL 891!) program within apprcximately three refueling outages, or 5 years, i
from the issuance of the generic letter.
Permit holders were asked to cog lete the GL 89 10 prograa before plan preceding schedule, whichevs.r was later. t startup or in accordance with the i
The NRC staff issued seven supplements to GL 8910 tr.et presented additional the GL.89 10 program serpe, design basis reviews, guidance and information on switch settings, testing, I
periodic verification, trending, and schedule extensions.
Recommendation "d" of-GL 89 10 asked licensees and permit holders to prepare procedures tc, ensure that correct MOV switch settinis are maintained tthroughout the life of the plant. GL 8910 stated Shat it may become necessary to adjust MOV switch settings because of wear or aging and that c
additional-measures should be taken beyond ASME Code stroke time testing to adequately verify that the switch settings ensure MOV operability.
. Recommendation "h" of GL 8910 asked licensees to evaluate trends in MOV i
$rformance every 2 years or at each refueling outage.
Recommendation"j"of 8910-stated 1 hat licensees should 5 years.or_ every 3 refueling outages, periodically verify MOV capability every e
{_Q ENCLOSURE b
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Licensees have cogleted (or are nearing completion of) their GL 8910 programs to verify the desn basis capability of safety related MOVs by reviewing MOV design bases, verifying initial MOV switch settings, testing MOVs under design basis conditions wwre practicable, and igrovin;RC staff evoluctions of MOV failures and necessary corrective action, The N has b;.en closing its review of GL 8910 programs at individual nuclear plants on the basis of resolution of issues associated with initial verification of MOV design basis capability. As indicated in applicable inspection re> orts i
and letters to licensees, the NRC staif has closed its review of the G. 8910 1
programs at a majority of nuclear plants, and the remaining re'.1ews are nearing completion.
On September 18, 1996, the NRC 1ssued GL 96 05, " Periodic Verification of Design Basis Capability of Safety Related Motor Operated Valves," to provide detailed guidance'for the periodic verification of MOV design basis capability, In GL' 96 05, the NRC staff asked licenstes to establish a program, or to er.sure the effectiveness of the current program, to verify on t.
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 i
indicating whether or not the GL 96 05 requested actions would be implemented, Within 180 days, or upon not:fication to NRC of completion of GL 8910 (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 8910 and its supplements with regard to MOV periodic verification.
2.0 @ INT OWNERS GROUP PROGRAM 01 MOV PERIODIC VERIFICATION In response to GL 96 05, the Boiling Hater Reactor Owners Group (BWROG), the Westinghouse %ners Group (WOG), and the Combustion Engineering Nners Group (CE0G) are jointly sponsoring an industry wide program to help maintain the capability of MOVs established under the GL 8910 programs implemented at individual nuclear >ower 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 Verification.
- On March 7. 1997 BWROG submitted Licensing Topical Report NEDC 32719 (March 1997), "BWR Owners' Group Program on Motor 0perated 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 Engineering Owners' Group Pr ram on Motor.
-Operated Valve (HOV) Periodic Verification.
The only change tween-Revision 0 and Revisinn 1 of the topical report was indication of the participation of CE0G 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 Program 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, J03 developed its program on HOV periodic verification in responte to GL 96 05 to obtain benefits from the sharing of information between licensees from GL 89 10 programs. The stated objectives of the J03 Program on HOV Periodic Verification are to (1) provide an approach for participating licensees to use immediately in their GL 96 05 programs.
(2) develop a basis for addressing the potential age related increase in required thrust 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 t program consisting of diagnostic testing of MOVs under static (no flow) conditions for participating licensees to use in response to GL 96 05, (2) conducting a dynamic test program consisting of diagnostic testing of HOVs under differential pressure and flow conditions over the next 5 years to operate gate, globe,ge related increases in required thrust and torque to identify potential a and butterfly valves under dynamic conditions, and (3) evaluating the information from the dynamic testing program to confirm or modify the interim program assumptions.
The stated benefits of the J0G program for participating licensees were conservation of resources, enhancement of program thoroughness and sharing of experience among the participating licensees, and establishment of a solid technical basis for the long term HOV Periodic Verification Program from the large sample of shared HOV test data, J0G suggested that benefits to the NRC included a generic a:oroach 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 top'. cal report describes the objective of the interim H0V periodic test program as assuring that the setup of the H0Vs remains consistent with GL 8910 criteria with additional margin for age related degradation during conduct of the J0G dynamic testing program. 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 frecuency based on functional capability (age related degradation margin over anc above the margin for GL 89 10 evaluated parameters) and safety significance.
The topical report describes the objectives of the JCG dynamic test program as determination of the degradation related trends in dyiiamic thrust and torque, and use of dynamic test results to adjust the interim program if warranted.
The J0G dynamic tdt program will be implemented concurrent with the J0G interim static test program. The elements of the J0G tiynamic testing program comprised the following:
(1) identification of condit ons and features that could potentially lead to MOV degradation, (2) definitun and assignment of valves for dynamic testing. (3) testing valves three tinies with at least a 1-year interval between valve-specific tests according to a standard test specification over a 5 year interval, (4) evaluation of *esults of each test, and (5) evaluation of collective test results.
J0G will establisn a feedback mechanism to ensure timely sharing of MOV interim and firal test results 3
between >articipating licensees, and prompt individual Itcensee actions to adjust t1eir own MOV periodic verification programs, as appropriate.
i in the last phase of the program, J0G will evaluate the test results to validate the assumptions in the interim program to establish a long term MOV l
Periodic Verification Program to be implemented by the participatini licensees. 00G contracted with HPR Associates. Inc., to assist in ;he development of the periodic verification program, and in the management of the i
utility test database, and test data analysis and evaluation, 3.0 CVALUATION The NRC staff review of the J0G Program on MOV Periodic Verification was based on submittals from the owners oroups and informatirm obtained from public meetin[s. Staff from the NRC dffice of Nuclear Reacter Regulation (NRR) and the NRL Office of Nuclear Regulatory Research (RES), W J an RES consultant, participated in the review, in letters dated June 12 and 13, 1997, respectively, the NRC staff provided comments to BWROG and WOG on the J0G pr ram. On June 24 and 25, 1997 NRC staff members from the NRR Hechanical l
En neerin Branch and the RES Electrical, Materials, and Mechanicel En ineeri Branch, and an RES consultant, met publicly with J0G represent 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 submitted Revision 2 to the topical report on the J0G Program on MOV Periodic Verification.
The owners groups also submitted a written response to NRC staff comments on the J0G program.
The NRC staff has prepared this safety evaluation (SE) on Revision 2 to.the r
topical report describing the J0G Program on MOV Priodic verification. J0G has comitted to maintain the program description as a controlled document so that it will be the same for all participants.
(See NRC Coment 5 on the J0G Program on MOV Periodic Verification provided in the NRC letter dated June 12, 1997, and the J0G response to that comment submitted in a letter from BWROG dated July 30. 1997, from CE0G dated August 6, 1997, or from WOG dated August 12, 1997.)
Many licensees have referenced the J0G Pr ram on MOV Periodic Verification in their individual responses to GL 96 05. J representatives have indicated that licensees of 93 reactor units are participating in the J0G program. This represents an increase in the number of licensee participants since the sumittal in early 1997 of licensee descriptions of MOV Periodic 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 oescribed 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 articipating licensees to (See goment 2 and J0G response.pstify any deviations from the J0G program.
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
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 MOVs to be operable when in their non safety positions will justify the capability of those MOVs to return to their safety position. The topical report states that the scope of the J0G program is intended to cover most types of gate, globe, and butterfly valves at participating plants at least with re degradation. gard to key valve features that are reltted to potential-Tne topical report states that each partici>ating licensee is responsible for identifying any valves that are outside tie scope of applicability of the J0G program and for addressing toose 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 verifica+ ion program for those valves or conditions outside the J0G program.
(See Comment 6 and J0G. response.)
Sufficient data will be necessary to justif/ the final test criteria for all valve types and materials (including their service conditions) within the scope of the J0G program. Some valves or materials intenued to be included in the J03 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 examp h, J0G will need to evaluate whether high temperature globe valve performance can remain in the scope of the J0G program.
(See Comments 7, 8, and 23, and J0G responses.)
RES is sponsoring tests to study age related degradation of Ste111te 6 materials used for most MOV sealing surfaces. RES is also sponsoring analytical studies of the potential increase in MOV failure probability basea on aging rates and margin uncertainty with longer test intervals. These or, going research efforts may provide information applicable to the J0G program.
NRC will make the results publicly available as soon as the research is completed and reviewed. J0G may neea 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 These phases ann applicable NRC review results are discussed below: program.
A, Interim Perio h Test Program In response to GL 8910, licensees have been verifying the design basis ca> ability of their safety related MOVs.
For the long term licensees are establishing programs in response to GL 8910 and, more rece,ntly, in response to GL 96 05, to maintain the design basis capability of these MOVs. To 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 MOV static testing with suitable diagnostic test equipment on a 5
- .y frequency that depends-'on,the safety si
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- the functional capability (margin) of thificanc- (risk) of the valve and on-valve,. Except where relief is
- requested and approved,' the NRC staff will= also expect licensees to contina
.l Ltesting MOVs in accordance with the acclicable-plant IST program as required
-by the NRC regulations in 10 CFR 50.55' and the ASME Boiler and Pressure -
a tVessel! Code.E u
The J0G Program on MOV Periodic Verification does not-include consideration of non mandatory ACME Code Case OMN 1. PAlternative Rules for Preservice and Inservice Testing of Certain Electric Motor Operated Valve Assemblies in LWR
[ Light Water ReactorlPower Plants
- whieb allows replacement of quarterly-stroke-time testing for HOVs within IST programs specified by the ASME Boiler
-and Pressure Vessel Code. J0G resresentatives have stated.their intent to evaluate the E,pplication of the JXI program to ASME Code Case OMN 1 over the 1
teru.-
Individual licensees are responsible for requesting any proposed i
ementation of ASME Code Case OMN 1 as relief from their. IST requirements.
(S Comment 4 and J0G response.)'.
The topical report spe'ifies that static diagnostic testing will be conducted
- under the interim periodic test program on the following refueling cycle frequency:
! Risk and Margin:
Low Margin 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 Rist 3 cycles 6 cycles
- 6 cycles
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- 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 group or utility-specific criteria.
The topical re> ort
. allows plants with 12-menth fuel cycles to double the frequency criteria Jut not to exceed 10 years.
T?.e topical report states that the interim pcriodic testing program is.
intended to provide confirmation that each MOV is set up in a manner-that ensures positive margin for operability. J0G has sta'.ed 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 11at setup is consistent with operability and that-all evaluated
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" MOVE tre expected to be operable. The topical report indicates that it is not 6
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i intended that the risk criteria be used to avoid addressing operability. :Tht.
NRC staff contiders the topical-report to indicate:that licensees must ensure 7that each @V in.the J0G program will have adequate margin-(including consideration of aging related degradation) to remain opereble until thelnext
-scheduled test. regardless of its risk categorization or safety significance.1 (See Comment 10 and J0G response.)
c The topical report states that the methodology and discrimination criteria for
= placing valves in specific ~ risk categories are the responsibility of each participating licensee, For determining the risk significance of individual
-MOVs. the tJpical-report refers members of the BWROFIntegrated Risk Based
- Regulation Committee to BWROG Topical Report NEDC-32264, lication of Probabilistic Safety Assessment to Generic Letter 8910 I ementation." where the report is ap)RC staff approved with certain conditions the use of BWROG 1ied in accordance with an NRC SE dated F bruary 27. 1996.
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.In that SE.;the 1 Topical Report NEDC-32264 for the prioritization of safety-related MOVs for 4
testing in response to GL 89-10. The NRC staff considers the application of-NEDC-32264 also appropriate for >rograms developed in response to GL 96-05 for licensees that participated in t1e development of NEDC-32264. Applicable licensees will need to review their >1 ant-specific pro to verify proper application of the SWROG 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 c'evelopment of that methodology. J0G states in its topical report that other L..
. licensees participating in the J0G program will be expected to use plant-specific or other generic criteria, which need to be justified. for ranking 4
MOVs. The NRC staff will expect licensees that did not participate in the development of NEDC-32264 to justify.their MOV risk cate9orization 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 Mctor-Operated Valves in Response to Generic Letter %-05," which presents a methodology to rank MOVs according to their L
risk importance. The NRC staff is reviewing the WOG methodology for possible endorsement. Other owners gr have not submitted an MOV risk ranking rc R
h Institut PR e
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Prediction Methodology (PPM) to define a bounding t1 rust (or torque) required to operate a gate, globe, or butterfly valve within the scope of the EPRI.MOV PPM.. The NRC staff concluded that the EPRI MOV PPM constituted an acceptable L
methodology to predict thrust-and torque requirements following the conditions and limitations in an SE dated March 15,19%, and an SE supplement dated i
February 20. 1997. J0G acknowledges the use of the EPRI MOV PPM by licensees in predicting thrust and torque requirements:for sizing and setting MOVs.
In Section 4, tne topical report states that an MOV is considered to have "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 Ldocumentation and NRC SE are met,-'(3). the valve is. predictable as defined in the EPRI MOV 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 MOV PPM contains some margin.for increases l
In recuired thrat or torque, the NRC staff will-expect licensees to-address m-:
degracation in actuator output thrust in determinino whether an MOV should be
" considered to have high margin, (See Coments 13,14,: and 15.. and J0G responses.)
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The topical report defines mar in as the difference between available thrust
.(or. torque) capable of being d!11vered by the actuator ind required thrust (or -
torque) demanded by the valve under design basis conditions, The topical ' -
a report states that the margin for gate and globe valves is calculated-from the tadjusted actuator output tarust minus the adjusted required thrust. and the i
margin for butterfly valves is calculated from tha adjusted actuator output i
torque minus the adjusted required torque. The topical report 11stsLthe
-following as example adjustments:- test equipment inaccuracy,lubricanttorque switc repeatability, rate-of-loading, spring degradation, and seat 00grada;1on (e.g. pack relaxation, stemLicensees have
,> hardening).
different-approaches in applying uncertainties in thrust and torque setup calculations in their MOV pr rams. These differing approaches can result in different amounts of margin applied to the same r.0V. The topical report
-states that each plant is responsible for appropriately applying the 4
adjustments to actuatur output torque or thrust in calculating margin in the J0G program. This is particularly important because of the small margins R
allowed by the J0G interim periodic test program. For example, the t
uncertainties of test equipment inaccuracy at static torque switen trip, torque switch repeatability, rate-of-loading, spring pack relaxation, and stem 1
lubricant degradition are to be used to adjust the actuator output thrust.
Licensees may retain their approach for MOV setup if it is justified that MOVs 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 M0V. These test frequencies-are generic and might not be applicable to every MOV within a licensee's MOV 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 Joecific valve, and its application and environment, to determine if the tect 5 years,y is appropriate.the NRC staff will expect the licensee to group that M
?quenc If an MOV has a planned test schedule beyoci
'H0Vs that will be tested within 5 { ears-in order to confirm the assumptions supporting the longer test intervai.
(See Coment 11 and J0G response.)
The topical report states that _the J0G program is based on the premise that L
Leach' licensee is responsible for determining the margins that need to.be
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included for actuator capability; degradation. and for justifying and implementing these margins.. Degradation of actuator output thrust and torcue-r is not within the scope of the J0G program. J0G representatives have stated 4
.thattactuator output capability was not included in the J0G program because of significant differences between the individual licensee programs in maintaining the outputLof their actuators. As a result, J0G 1s relying on each participating ~ licensee to provide reliable predictions of actuator 8
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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 actuator. including consideration of NRC Information Notice 96-48, " Motor-0perated Va've Performance Issues " and followup-industry and NRC information, further, the NRC staff will expect licensees to 6ddress the effects of aging on rate-of-loading and stem friction coefficient under dynamic conditions. Therefore, licensees are responsible for justifying their actuator output predictions, including stem friction coefficient and load sensitive behavior, as part of their MOV programs. On the basis of GL 8910 inspections, some licensees are planning to resolve weaknesses in their assumption; for stem friction coefficient or load sensitive behavior as part of their long term HOV 3rograms. The limited J0G dynamic. testing at s>ecific plant sites might not >e sufficient to justify the actuator output capa)111ty assumptions for Nme licensees. Consequently, licensees will be responsible for supplementing the J0G testing program as necessary to resolve any identified weaknesses in actuator capebility assumptions.
(See Comment 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.ynenic tests of selected The J0G dynamic test program will involve diagnostic testing of a few H0Vs 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 d 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.
0G 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 fL.: tors (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 Program 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 gate and globe valves (expressed as valve factor) or required dynansic torque in butterfly valves (sum of bearing and hydrodynamic torque), (2) effect of differential pressure on unwedging thrust (gate valves). (3) rate-of-loading for gate and globe valves, and (4) stem friction coefficient under dynamic conditions for gate and globe valves. Dynamic test results will be used to understand potential-degradations in required dynamic thrust or torque. The transfer of information on unwedging thrust from one valve to another might be unreliable 9
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,because of valve specific characteristics. -(See Coment 18 and J0G response.).
L The topical-report statis that' changes in rate of-loadin!1 are not consideredj in the dynamic testing programa J0G considers the poten;1al' time related--
2 degradation of thrust at torque-switch trip under dynamic conditions to be
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- separately-addressed by considering-stem lubricant degradation.1 Stem-i ilubricant. degradation under dynamic conditions 1s outside the scope of the J0G
~ program. The NRC staff will expect licensees to address the potential:for age related changes in rate of loading and stem lubricant'd6 gradation (and.
other potential age related effects such as spring-pack relexation,-and.
actuator and switch lubrication degradation) as part of their long tem MOV-
- programs, The topical re> ort states that the dynamic test program consists of a series of in plant M0/ tests performed under dynamic conditions.
The d program-is said to include 100 gate valves. 30 butterfl valves,ynamic test 10 unbalanced disk globe valves and 10 balanced disk globe valves. y"he topical' report-states that each valve is to be 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 observo 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 NRC staff believes that more-extensive historical information on the test valves might be helpful in evaluating the test results and their implication.
The J0G representatives stated that more detailed infortr.ation may bt requested for s>ecific 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 nuclear plants, and on the basis of the availability of valves that can be dynamically 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 potential factors include cumulative dynamic strokes, fluid environment and temperature, disk and seat material pair, guide material ) air, valve factor, stem orientation for gate valves: cumulative dynamic stroces, fluid environment and temperature for globe valves: and bearing material.
particulate level in fluid medium. and stem orientation for butterfly valves.
- Manufacturers covered in the J0G program are Aloyco. Anchor / Darling, 4
Borg Warner Copes-Vulcan Crane. Pacific. Powell Velan. Walworth, and Westinghouse for gate valves: CCI. Copes-Vulcan, Fisher. Hammel-Dahl, Valtek.
4 and:Yarway for balanced disk globe valves: Anchor / Darling. Borg-Warner.
Edward. Velen. Walworth, and Yarway for unbalanced disk-globe valves: and Allis Chalmers.:BIF. Contramatics. Fisher. Jamesbury, and Pratt-for butterfly
=
valves.. 'In response to NRC staff comments.LJ0G provided an up-to-date list of L
valves to be dynamically tested as part of-the J0G program. including
_ unbalanced disk globe valves.- (See Comments 22 and 24. and J0G responses.)
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The dynamic test sequence in the J0G program includes a static test preceding the dynamic test. The NRC staff has questioned th2 potential effect of this static test on the results of the dynamic test. J0G stated that static-testing is typically performed immediately preceding dynamic testing to calibrate the diagnostic e@ipment, liowever J0G stated that some dynamic tests may be conducted withot,t an imediately preceding static test. J0G will evaluate this information, t', the extent possible, to determine whether the performance of a static test immediately 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.
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 the'. interim criteria, the to)1 cal report states that these changes will be made and comunicated to tie participants. The topical report states that, for information supplied by J0G, it is the responsibility of the individual plants to evaluate the applicability and impact of that information for their valves. The NRC staff notes that this includes responsibility for satisfaction of the requirements to notify the NRC under the provisions of 10 CFR Part 21, evaluation of experience foi' applicability, and consideration of effects on component operability, as appropriate.
(See Coment 3 and J0G response.)
Appendix 0 to the topical report conteins a standard approach for analysis of dynamic test data by participating licensees to calculete valve factor (gate and globe valves) and bearing friction coefficient (butterfly valves) in a consistent manner. For example, maintenance performed on MOVs 1' the testing program may affect the ability to id#ify age-related degradation.
In response to this issue. J0G emphasizeo 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 consists 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.
11
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.I (2) [J0GReceiptEvaluation.
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U)on receipt of the test. documentation packages,.the J0G tie packages for. completeness, accuracy, and consistency. program reviews-1 c The J0G
. receipt evaluation involves comparing the test results with previous =
tests, with any observed trends with similar valves, and with the J0G-i
. program criteria. J0G's annual review will include assessment of the
-threshold criteria for immediate evaluation of test data.
(See i
Comment 16 and J0G response.)-
(3)
LJ0G Formal Periodic Evaluation The topical report states that, when a potentially large degradation rate has been observed for a valve or class of valves, the J0G program
-will determine if further evaluation, or L;
- program or interim criteria, is required. potential modification of the If action is needed, the J0G program will p pare and comunicate the information to the
- participating censees. An industry group overseeing the J0G~ arogram will-meet once a year to review test data and to determine if tiere are
- any necessary corrective actions to the program or to the interim criteria. The J0G progr6m will notify participating licensees of the results of the annual meeting and any necessary corrective actions.
The J0G interim 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 p feedback of test results to participating licensees to ensure that t amic test information continues to 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 promptly address changes in thrust F
or torque r uirements less than 10 >ercant.
With the periodic information to be provided the J0G program, the (RC staff will expect participating licensees to address these program updates, Some MOVs have tentative test schedules beyond 5 years in the interim test p gram. The NRC staff will ex t J0G to evaluate dynamic test data within t
5 year program so that a pl cable MOVs will be tested within 5 years if test results do not support onger test intervals.
(See Comment 17 and J0G
-response.)
9 I
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 i
for MOV periodic verificationw:J0C will prepare a revision to (or a replacement report for) the t ical report on the J0G Program for MOV Periodic Verificatbn specif the fi al-MOV periodic verification criteria and their i
- justifiestion.
staff will review the final test criteria for the-12 J
5
long term H0V 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 96 051 For licensees participating-in the J0G Program on P.0V 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 eveluating 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 program following issuance of this SE.
In updating its comitments to the J0G progr_am. It woeld be helpful if licensees described their implementation of the J0G pr ram (such er their MOV risk ranking a >proach).. consideration of as outside tie scope:of the J0G program, pects c. HOV periodh. verification during completion of their GL 89-10 program.plementation of commitments made and im After receiving a licensee's updated commitments regarding the J0G program, the NRC staff plans to prepcre 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 Juu program. These inspections might also evaluate licensee consideration of aspects of MOV periodic verification outside the scope of the J0G program and implemer tation of commitments made by licensees during completion of their GL 8910 programs.
For licensees not participating in the J0G program, the NRC staff will evaluate the M0V periodic verification programs at those fsc111 ties through NP.C staff review of licensee submittals 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 oy 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
- s3onsored by BWROG, WOG and CE0G 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 Nners' 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 Nners Group Program on Motor-0perated Valve (MOV) Periodic Verification." on August 6.
1997: and by WOG as Topical Report MPR-1807 (Revision 2) " Joint BWR, Westinghouse and Combustion Engineering Nners Group Progrt.m on Motor-0perated Valve-(MOV) Periodic Verification." on August 12. 1997.
13 w
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The conditions and limitations described in this SE enable the NRC staff to conclude that the J0G Program on MOV Periodic Verification provides 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 revision to (or replacement re> ort for) the to)1 cal 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 criterla.
B.
Licensees that did not participate in the development of NEDC-32264 must justify their MOV risk categorization methodology as part of their implementat' ion of the J0G program.
The NRC staff is reviewing an MOV risk ranking methodology submitted by WOG for possible endorsement.
C.
License c 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 J03 dynamic test program are evaluated). J0G indicated that be requested, following issuance of this SE, participating licensees will to individually notify the NRC of their plans to imalement the J0G program described in Revision 2 of the topical resort.
Participating lic.ensees must justify any deviations from tie J0G 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 3rogram. 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 I
/
G.
Licensees may.etain their approach for H0V setup where it is justified that MOVs are properly evaluated for operability. However.-when establishing test frequencies under the J0G program, licensees must apply uncertainties as appropriate in calculating actuator output _or valve required thrust (or torque).
H.. With the focus of the J0G program on the pbtential 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 n;otor 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 spring pack relaxation, and actuator and switch lubrication degradation.
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 HOVs that will be tested on frequencies less th3n 5 years in order to valicate 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 15 1