ML20210D145
| ML20210D145 | |
| Person / Time | |
|---|---|
| Issue date: | 07/08/1999 |
| From: | Wen P NRC (Affiliation Not Assigned) |
| To: | Carpenter C NRC (Affiliation Not Assigned) |
| References | |
| PROJECT-689, PROJECT-691, PROJECT-692, PROJECT-693, PROJECT-694 NUDOCS 9907270137 | |
| Download: ML20210D145 (66) | |
Text
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3 UNITED STATES
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NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20566-0001 90 July 8, 1999 MEMORANDUM TO: Cynthia A. Carpenter, Chief Generic Issues, Environmental, Financial and Rulemaking Branch Division of Regulatory Improvement Programs Office of Nuclear Reactor Regulation FROM: Peter C. Wen, Project Manager M C.
Generic Issues, Environmental, Financial and Rulemaking Branch Division of Regulatory improvement Programs Office of Nuclear Reactor Regulation
SUBJECT:
SUMMARY
OF JUNE 3,1999, MEETING WITH NUCLEAR ENERGY INSTITUTE REGARDING INDUSTRY AIR-OPERATED VALVE PROGRAM On June 3,1999, the NRC staff met with representatives from the Nuclear Energy Institute
'(NEI), the Joint Owners Group on Air-Operated Valves (JOG AOV), Institute of Nuclear Power Operations (INPO), Air-Operated Valve Users' Group (AUG), and the Electric Power Research Institute (EPRI) to discuss air-operated valve (AOV) design, performance, and maintenance issues. NRC offices represented at the public meeting included Nuclear Reactor Regulation (NRR), Nuclear Regulatory Research (RES), and a staff representative of the Advisory l Committee on Reactor Safeguards (ACRS). Members of the general public were also in {
attendance and all participated in question and answer sessions during each presentation. !
Attachment 1 is a list of the meeting participants.
JOG AOV representatives provided a discussion of the JOG AOV Program document which details the industry's effort to implement an AOV program at commercial light-water nuclear power plants in the United States. An AUG representative described the structure, function, and limitations of the users' group in addressing AOV issues. EPRI provided an update of its research efforts, including pilot AOV programs at several plants, issuance of its AOV Evaluation Guide, and coordination with the JOG AOV. INPO provided information on its evaluation and assistance activities with respect to AOVs. Finally, NEl addressed issues concerning nuclear industry implementation of the JOG AOV program document and any NRC generic {[
communications that may be issued by the staff. A copy of the slides from the presentations
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described above is included as Attachment 2. In addition, a copy of the JOG AOV program elements from the JOG AOV program document that was discussed during the meeting is i included as Attachment 3. 4 OJ i NRC NJ @MIB COPY 9 9907270137 990708 .
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C. Carpenter -2 July 8, 1999 Members of the NRC staff did not make any formal presentations. However, members of NRR did provide the following handouts: a list of questions for discussion at the public meeting (Attachment 4); a list of attributes for a successful AOV program based on the NRC Generic Letter 89-10 program for motor-operated valves (Attachment 5) and; a copy of the May 14,1999, letter from the Chairman of the ACRS to the NRC Executive Director of Operations discussing i the staff's proposed resolution of Generic Safety issue 158, " Performance of Safety-Related Power-Operated Valves Under Design Basis Conditions"(Attachment 6). In addition, a representative of NRC RES distributed a draft copy of the NRC AOV study: " Evaluation of Air-Operated Valves at U.S. Light-Water Reactors" (Attachment 7).
A NEl representative stated that the JOG AOV Program document is expected to be issued to the utilities sometime this summer. NEl is not planning to request that the NRC comment on the document prior to its issuance. NRC representatives stated that they may provide comments on the JOG AOV Program document after it is issued.
Attachments:
- 1. Meeting Participants
- 2. Meeting Agenda and Slides from the Industry Presentations
- 4. NRC Staff Handout: List of Questions for Meeting Discussion
- 5. NRC Staff Handout: List of Attributes for a Successful AOV Program
- 6. NRC Staff Handout: 5/14/99 Letter from the Chairman of the ACRS to the NRC EDO on the Proposed Resolution of GSI 158.
- 7. NRC Staff Handout: NRC AOV Study," Evaluation of Air-Operated Valves at U.S.
Light-Water Reactors" cc w/atts: see next page i
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C. Carpenter - -3 July 8,1999 Members of the NRC staff did not make any formal presentations. However, members of NRR did provide the following handouts: a list of questions for discussion at the public meeting s
(Attachment 4); a list of attributes for a successful ACV program based on the NRC Generic Letter 89-10 program for motor-operated valves (Attachment 5) and; a copy of the May 14,1999, letter from the Chairman of the ACRS to the NRC Executive Director of Operations discussing the staff's proposed resolution of Generic Safety issue 158, " Performance of Safety-Related Power-Operated Valves Under Design Basis Conditions"(Attachment 6). In addition, a representative of NRC RES distributed a draft copy of the NRC AOV study: " Evaluation of Air-Operated Valves at U.S. Light-Water Reactors"(Attachment 7).
A NEl representative stated that the JOG AOV Program document is expected to be issued to the utilities sometime this summer. NEl is not planning to request that the NRC comment on the document prior to its issuance. NRC representatives stated that they may provide comments on the JOG AOV Program document after it is issued.
' Attachments:
- 1. Meeting Participants
- 2. Meeting Agenda and Slides from the Industry Presentations
- 4. NRC Staff Handout: List of Questions for Meeting Discussion
- 5. NRC Staff Handout: List of Attributes for a Successful AOV Program
- 6. NRC Staff Handout: 5/14/99 Letter from the Chairman of the ACRS to the NRC EDO on the Proposed Resolution of GSI 158.
- 7. NRC Staff Handout: NRC AOV Study, " Evaluation of Air-Operated Valves at U.S.
Light-Water Reactors" cc w/atts: see next page DISTRIBUTION: See attached page ocument Name: g:\rgeb\pcw\msum_AOV.wpd OFFICE PM:RGEB: DRIP EMEB:DE SC:RGk V NAME PWen:sw gy JColaccino N FAkshfcz DATE 07/6 /99 07/ (,,/99 07/ h/99 OFFICIAL OFFICE COPY
i l
NRC/NEl MEETING ON INDUSTRY AOV PROGRAM l LIST OF ATTENDEES I
l June 3,1999 l
l NAME ORGANIZATION Dick Wessman NRR/DE Gene Imbro NRR/DE/EMEB David Terao NRR/DE/EMEB Tom Scarbrough NRR/DE/EMEB Joe Colaccino NRR/DE/EMEB l L. B. Marsh NRR/ DRIP /REXB Dave Skeen NRR/ DRIP /REXB Hal Ornstein RES/DET Frank Cherny RES/DET Al Serkiz RES/DET Mary Wegner RES/DET Amarjit Singh ACRS Doug Dempsay Reg l l Peter Wen NRR/ DRIP /RGEB Jim Riley NEl i Dave Modeen NEl John Hosler EPRI Kenneth Beasley Duke Power / B&WOG Philip Pieknik STPNOC/WOG :
ike Ezekoye Westinghouse /WOG Wendell Fiock GE/BWROG !
Jim Hallenbeck PECO/BWROG/AUG Mark Coleman PSE&G/ JOG /BWROG Kevin L. Cortis NNECO/ JOG /CEOG C. Wesley Rowley The Wesley Corp LJ. Victory Jr. Enurtech John Doiron INPO Robert Gambrill Consumers Energy l Stan Hale Crane Nuclear
! Glenn Warren BWROG
! Phillip Young DE&S
! Tom Walker MPR l
David Sibiga ABB-CE/CEOG Horace Beasley BGE Elaine Hiruo McGraw-Hill Jim White ~ Curtiss-Wright Flow Control Corp.
Owen Rothberg INEEL ATTACHMENT 1
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Industry AOV Program I
Industry / NRC Meeting i June 3,1999 ;
NEI, JOG, AUG,ITRI,INPO l mummmmmmmmmmmmmmmm Agenda
= Introduction Jim Riley
= AOV Program details Ken seasley Mark Coleman Kevin Cortis Philip Pieknik
= AUG support Jim naisenbeck
= EPRI support John noster
= INPO support John ooiron
= Implementation strategy Jim Riley
= NRC AOV Activities nRc
$I ATTACHMENT 2
1 1
Introduction i
= Meeting purpose l
. Present details of JOG AOV Program l Document
. Present associated industry support activities l
. Obtain update on NRC AOV activities
= Meeting groundrules
'f' Joint Owners' Group (JOG)
AOV Program Mark Coleman PhilPieknik Ken Beasley Kevin Cortis
i
Background
= IN 88-94, Undersized Actuators AUG created
= INPO letter on AOV Design Issues I
= JOG created pi Participating Owners' Groups aB&WOG
=BWROG
=CEOG
=WOG
't'
O Mission Statement
= To develop a common and cost-effective US nuclear utility AOV ,
Program which defines the elements necessary to enhance safe and reliable AOV performance and allow l timely address ofindustry and regulatory AOV issues.
Participation UIILITIES PLANTS UNITS B&WOG 5 5 7 BWROG 20 24 34 CEOG 8 9 14 WOG 23 29 47 TOTAL 56 67 102 V'
e organization l JOG AOV l 1 I i 1 B&WOG CORE GROUP BWROG CORE GROUP CE00 CORE GROUP WOG CORE GROUP l Ken Bessley Mat CcJaman Kevin Certa Ph5 Poknk l Charman Charman Darman Chaman I E [ t I I I 1 lPM l lUUNbesl lPM l lUl?ibesl l PM l lUtillbesl l PM l (UtEssl
)
Interfaces
= Primary Contractor:
Duke Engineering & Services
= Other Organizations
- ASME - AUG
- hTI - USA
n Program Development
= Majority of the 1998 JOG AOV efforts were devoted to the Program Document Development
= Document goal was to establish standard requirements for en industry AOV Program a Utility and NRC issues were reviewed a Core Group convened 7 times throughout the process a Four Utility review cycles e Industry reviews, including licensing
= Over 2500 Core Group man-hours expended a Revision 0 issued in March 1999 :
Program Elements a Scoping and Categorization a Design Basis Reviews Setpoint Control a Testing a Preventive Maintenance a Training
= Feedback
= Documentation & Data Management a Tracking & Trending g
AOV Program Scope 1
= AOV assembly includes valve, actuator, and '
accessories required to allow the AOV to perform it? afety significant function. l e All AOVs are considered for categorization.
= Isolation devices in duct work are excluded.
. Recognizes importance ofinstrument air systems as addressed by GL 88-14.
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Categorization a Categorization is based on risk-informed methods
= Several acceptable methods for risk ranking
. OMN-3
. Maintenance Rule
. NRC Regulatory Guides for Risk-Informed IST
= Expert panel required
I-Categorization (cont'd)
= 2 Categories:
. Category 1: Safety-related, active and high safety significant
. Category 2: Safety-related, active and not high safety significant or
)
Non safety-related, high safety significant and active N'
e Design Basis Reviews a Required for Category 1 AOVs
= Verifies and documents adequacy of sizing and setpoint
= Establishes acceptance criteria for verification testing
= Generic issues identified through Category 1 DBRs or industry feedback mechanisms that could affect Category 2 valves are considered ,
Design Basis Reviews (cont'd)
= System and component level reviews
= Allows exception from component level review for periodic cycling
= All known contributors to margin are considered in the margin calculation, including uncertainties and degradation
'd' Setpoint Control
= Required for Category 1 and 2 valves 1
= Setpoints to include are:
. actuator supply pressure
. preload/ bench set
. stroke length as applicable to safety significant function I
f Baseline Testing
= Performed for Category 1 AOVs to validate functional capability and DBR inputs, confirm setpoints, establish reference for periodic testing
= Test equipment in compliance with plant's Quality Assurance program a Method can range from stroke-time testing to '
dynamic testing N'
Periodic Testing a Performed for Category 1 AOVs to identify potential degradation m Identical or similar designs may be grouped
= A minimum of 30%, no less than 2, to be tested from each group
= AOVs tested consecutively to monitor for potential degradation
= Generic issues shall be reviewed for effect on similar assemblies fg
Post Maintenance Testing
= Performed for Category 1 AOVs to re-baseline following replacement, repair, or maintenance affecting performance
. Test methods established by plant; need not exceed initial baseline testing
= Category 2 - verification of affected setpoints required -
/M Preventive Maintenance 1
= Required for Category 1 and Category 2 l AOVs !
I
= Performed to provide high confidence of valve performance in meeting intended design functions
= PM requirements to be established by individual utilities [EPRI documents l offered as reference]
l
Training
= Recommended for any program
= Training elements left to individual utilities; JOG recommendations:
. Actuator, valve / accessory design & function
. Setpoint control
. Test equipment use & evaluation
. Calculation methods
. Maintenance practices
. Lessons learned Y'
Plant Specific Feedback
= To assure operating, design, maintenance and testing activities are continually considered for incorporation into plant AOV program a Communicate with other plant programs, such as Maintenance Rule or root cause evaluation of failures I
Industry Feedback
= To assure generic issues are evaluated for inclusion into all industry plant AOV programs a Forums and other communication mechanisms currently exist, such as INPO, EPRI, AUG, NRC, and Individual Owners' Groups Y'
Documentation / Data Management a Configuration control required for any utility AOV program a JOG recommendations for documents and information to be controlled include:
. Plant program document
. Scoping & categorization criteria, bases, results
. System design basis reviews
. Actuator / valve capability calculations
. Setpoints & test results
. Tracking & trending reports pg i
Tracking and Trending
= AOV failures shall be tracked / trended for all program
, AOVs
= Critical AOV performance parameters obtained during Category 1 testing shall be tracked / trended.
Examples:
. Packing /mnning loads
+ Setpoint pressure
+ Preload or bench setlange
+ Seating / unseating loads
+ Valve friction factors (if dynamically tested) El c
AUG Support ;
l AUG Air operated Valve Users' i Group l 1
Jim lh l l e n b e c k 1
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I AUG Charter
= Dedicated to the development and exchange of technical information for the design, testing and maintenance of Air-Operated Valves
= Provides a platform for training and .
exchange oflessons learned I
= Meetings attended by utilities, EPRI, INPO, OEMs, vendors, and NRC fg e
AUG Subcommittee Products
= AOV program scoping document
= AOV Program Document l
= Preventive maintenance recommendations
= Actuator sizing verification
AUG Limitations
= No formal mechanism exists to issue documents to the industry
= Little exposure to executive management for implementation
= No funding for research/ development I
l l
= AUG leadership participated in JOG AOV meetings
= AUG leadership prosided input into JOG AOV Program Docmnent development
= AUG Steering Conunittee includes members from JOG AOV Core Group
= AUG meetings used by JOG AOV as an additional forum to communicate and provide training y ;g
EPRI Support EPRI AOV Research Update John Ib si e r
't' overview
= Pilot AOV Programs e AOV Evaluation Guide a Ongoing Research Activities a Coordination with JOG AOV Program
't* '
= In 1996 EPRI began initiating pilot programs at several nuclear plants to apply lessons learned and tools developed under the EPRI MOV Performance Prediction Program in the development and implementation of technically sound Air-Operated Valve Programs
'd' MM EPRI AOV Pilot Programs
= Pilot Programs included definition of
- System conditions
- Valve required thrust / torque
- Actuator thrust / torque output capability
- AOV Margin
= EPRI MOV PPM utilized to define required thrust / torque when applicable
= New or refined methods utilized when PPM not applicable or appropriate
= First principles methods developed to define air-actuator output capability Y'
= Palisades pilot program to be complete, Over 150 AOVs evaluated
= Fermi pilot program to be complete,44 AOVs evaluated
= Duane Arnold AOV program 50% complete.
30 of 60 AOVs evaluated to date
= Comanche Peak AOV program initiated. Plan to complete 50 AOV evaluations in 99 I
J
. Refined balanced globe valve model developed and in use in pilot programs
- Neglects side loads
- Applies DP to actual unbalanced area
- Plans call for validation against test data in 99 m Refined unbalanced Y pattern globe valve modelin use for compressible flow (blowdown) conditions
- Applies 1.5 factor on DP tenn g
- Plans call for validation against data in 99 esp AOV Evaluation Guide
= Pilot AOV Programs led to development of a comprehensive AOV l Evaluation Guide
= Methods provided to assist utilities in !
conducting " design basis reviews" of I air-operated valves l
l
[
AOV Evaluation Guide
= Guideincludes:
- Methods for evaluating design basis system conditions
- Methods for evaluating valve required thrust / torque
- Methods for evaluating actuator thrust / torque output capability / margins
- Testing guidance -
= Guide to be published June 1999 N'
Ongoing Research Activities a Balanced globe valve required operating loads a Unbalanced globe valve required operating loads (compressible flow) e Simplified gate valve thermal binding ;
methodology l l
l
l I
l Coordination with JOG i AOV Program a EPRI participated in JOG AOV Meetings a EPRI provided earlyinput to JOG AOV Program Document development
= EPRI reviewed and provided comments on the JOG AOV Program Document j
= EPRI coordinated AOV Guide development with JOG AOV Program Document
= EPRI AOV Evaluation Guide reviewed by ,
JOG AOV Core Group members liti INPO Support !
INPO Air Operated Valve Activities Jo h n Da i r o n
OVERVIEW
= Evaluation activities
= Assistance activities
= Information exchange Evaluation Activities a Cross functional teams review plant :
management of air-operated valve <
reliability programs as part of ,
equipment performance and material l condition evaluation
= Increased focus on AOVs since 1997
't'
Assistance Activities
= Established single point of contact within INPO for Air-Operated Valve information and activity coordination
= 1999 pilot assistance objective to arrange specific AOV expertise to support plant assistance requests a Support and participate in August 1999 NMAC AOV workshop
'V' Information Exchange
= April 1997 letter to utilities recounting plant events and recurring AOV findings
= Maintaining INPO Web page listing INPO documents addressing AOVs a Developed Web page forjust-in-time operating experience briefing / training sheet
Information Exchange (Cont.)
= Reviewed and commented on the JOG AOV Program Document a Continue to support and participate in JOG AOV Core Group meetings
= Provide presentations for bi-annual AOV Users' Group conferences a Developed a Significant Event Report addressing AOV performance (SER l-99) 1 l
l NEl Summary Da y e Modeen
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Summary
= Risk informed, performance based, proactive program
= Single document for consistency
= Training at the January 2000 AUG Meeting
= JOG Core Group, NEI, INPO, and EPRI involvement continues, assembled as necessary to address any future AOV issues l
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JOG AOV % Revision 0 l March 9,1999 I
Table 3-1: AOV PROGRAM REQUIREMENTS
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Setpoint Comeroi 4.2 Yes Yes
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Design Basis Reviews 4.3 Yes No' l i
Baseline Testing 4.4.1 Yes No j Periodic Testing 4.4.2 Yes' No' i Post Maintenance Testing 4.4.3 Yes No' Preventive Maintenance 4.5 Yes Yes Training 4.6 Yes Yes Feedback 4.7 Yes Yes . l Documentation / Data Management 4.8 Yes Yes Tracking and Trending 4.9 Yes Yes Notes:
- 1. Although a DBR is not required for Category 2 valves, any generic issues identified through Category 1 DBRs or industry feedback mechanisms listed in Section 4.7 that could affect Category 2 valves shall be considered. For example, if a given vendor's effective diaphragm area is found to be less than stated in the original sizing, similar Category 2 AOV actuators shall be evaluated for impact.
- 2. Baseline testing is not required on Category 2 AOVs unless a DBR is required due to a generic issue identified through the Category 1 DBR process.
- 3. Testing may be required by existing plant programs such as inservice testing (ISI),
Maintenance Rule, ASME code, local leak rate testing (LLRT), licensing commitments, etc. For Category 2 AOVs, additional testing is not specifically required for the JOG AOV Program.
- 4. This program does not require additional post maintenance testing for Category 2 AOVs beyond verification of the affected setpoints established in Section 4.2.
- AOVs that are safety-related, active and have high safety-significance (see Section 4.1).
- Active AOVs that are safety related, active and do not have high safety-signifunce g AOVs that are non safety-related, have high safety-significance and are active (see Section 4.1).
ATTACHMENT 3 5
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List of initial NRC Public Meeting Questions for Joint Owners Group on Air-Operated Valves and Otherindustry Group Attendees
( Scone Of the plants that have categorized their air-operated valve assemblies (AOVs) into high and low l risk significant valvc assemblies, what was the typical number and percentage of high risk significant AOVs at t iese plants? Of the AOVs that were classified as high risk significant, on average, what was t .e number and percentage of safety-related valves?
Is there a potential for any active safety-related AOV to be excluded from the JOG AOV
. program? If so why?
What components are specified as part of the AOV assembly? Are any parts recommended for exclusion?
Design Basis Verification What methods are used to assure that AOVs will perform during the most limiting design conditions?
Is there a verification methodology that would provide some assurance that low safety significant AOVs would perform their design basis capability short of requiring a complete design basis verification review?
Probabilistic Risk Assessment Have you endorsed one specific methodology for risk ranking components? If you have not, is the JOG AOV concemed that this may lead to an unequal assessment of safety significance?
How does this compare with the JOG MOV actions in this area?
Was there any specific screening criteria guidelines included in the JOG AOV program? - if no, why not?
Testina How is AOV margin determined? How does this compare with the GL 89-10 program?
Is an acceptable capability margin defined in the JOG AOV program? How does this compare with the GL 89-10 program?
How are diagnostic uncertainties addressed in the JOG AO'/ program? How does this compare
- with the GL 8910 program?
Does the JOG consider it necessary to validate diagnostic methods? If not, why not?
I
! What is the appropriate mix of static and dynamic testing specified in the JOG AOV Program? If l
there is none, have any guidelines been provided which aid owners to determine the appropriate l mix? If not, why not?
ATTACHMENT 4
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t is credit taken for valves which are exercised during plant operation? How ooes this compare with the GL 89-10 program?-
What test frequencies are specified for all AOVs in the JOG AOV program? What is the justdication for each test frequency?
What testing is required for low risk significant safety-related AOVs? I l
w in what cases can stroke time testing provide verification of design basis capability?
1 Maintenance <
I l
To what extent does compliance with the maintenance rule ensure the ability of AOVs to perform their design basis function?
MOV Lessons Learned What aspects of the programs described in NRC GL 89-10,95-07, and 96-05, have you specified in the JOG AOV program? If you have only included references, please justify this approach.
Industry Participation iI What level of participation do you expect from US Nuclear utilities and over what time frame?
Have there been any efforts to compile an industry database of safety-related AOVs, their .
I l functions, and (for those plants which have already ranked their AOVs) their safety significance?
8 Have there been any efforts by the Air-Operated Valve Users' Group (AUG) to perform any verification of diagnostic test equipment as was done in the GL 89-10 program?
What types of activities is the AUG involved in that directly support the JOG AOV Program?
L
e May 24,1999 ATTRIBUTES OF A SUCCESSFUL AOV PROGRAM !
(T. Scarbrough)
L The general guidance of GL 8g-10 for MOVs is useful in establishing an effective program to
- program should address scope, setup procedures, design-basis review, initial and periodic i testing, maintenance, corrective action, training, tracking and trending of AOV performance, and foedback of test results and trending information.
A few specific points to be considered in establishing the AOV program are:
- 2. Verify AOVs in nonsafety position are capable of retuming to their safety position if train is ;
assumed operable. '
- 3. Verify guidance in GL 88-14 on air systems has been successfully accomplished.
- 4. . Evaluate MOV risk ranking methodologies by BWROG and WOG for applicability to risk ranking of AOVs (such as revise example list of high risk valves). l
- 5. Focus initial efforts on safety-related, active, high-risk AOVs, but group these valves with i other safety-related AOVs to apply lessons leamed to verify and maintain design-basis i capability of all safety-related AOVs. 3
. specific AOV dynamic diagnostic testing. Use of the EPRI MOV PPM must include all aspects and not just individual EPRI valve test results.-
- 7. Justify method for predicting AOV output capability by test-based program of vendor, licensee, or industry.
~ 8. Address all applicable weak links including actuator, valve, and stem,
- g. Ensure QA program coverage.
- 10. Provide sufficient diagnostics when baseline testing to verify capability. Diagnostics might I not be needed if normal plant operation frequently demonstrates design-basis capability.
- 11. Specify when dynamic or static diagnostic periodic testing is needed.
- 12. Ensure post-mainter ance testing adequate to verify capability of all safety-related AOVs.
' 13. Ensure AOV maintenance procedures are reviewed to incorporate MOV lessons teamed.
- 14. Upgrade training to incorporate MOV lessons leamed.
i ATTACHMENT 5
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4
- 15. Apply feedback from plant-specific and industry information, including test data to all applicable safety-related AOVs.
- 16. Establish quantitative (test data) and qualitative (maintenance and condition reports) trending of AOV performance with detailed review following each refueling outage.
May 14,1999 Dr. William D. Travers Executive Director for Operations U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001.
Dear Dr. Travers:
SUBJECT:
PROPOSED RESOLUTION OF GENERIC SAFETY ISSUE-158,
" PERFORMANCE OF SAFETY-RELATED POWER-OPERATED VALVES UNDER DESIGN BASIS CONDITIONS" During the 462ad meeting of the Advisory Committee on Reactor Safeguards, May 5-8,1999, we reviewed the proposed resolution of Generic Safety issue-158 (GSI-158), " Performance of Safety-Related. Power-Operated Valves Under Design Basis Conditions." During our review,
. we had the benefit of discussions with representatives of the NRC staff. We also had the benefit of the document referenced.
Recommendation We recommend that GSI-158 not be considered resolved. Tne central issue, whether power- )
operated valves (POVs) are able to perform their intended functions under design basis dynamic. conditions, has not been adequately addressed.
Discussion -
The NRC staff recommended closure of GSI-158 based on the results of the analysis performed by the Idaho National Engineering and Environmental Laboratory (INEEL) that ,
revealed that the potential reduction in risk from an improvement in the reliability of POVs will '
neither result in a substantial safety improvement nor be cost effective. The failure probabilities used in the analysis, however, were based on data reported by licensees for normal operating conditions. The staff did not demonstrate that there are sufficient data or analytical models to
- establish POV failure probabilities under design basis conditions. Therefore, the results of the -
j INEEL analysis do not provide adequate justification for resolving GSI-158.
The central issue of whether POVs will perform their intended functions under design basis
- dynamic conditions has not been adequately addressed. Based on a review of POV testing at seven sites, the NRC staff concluded that most licensees were not performing dynamic testing ;
or evaluating whether the static testing performed was indicative of POV performance under l J
ATTACHMENT %
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l 2 dynamic conditions. This indicates that current programs and existing requirements are not sufficient to ensure a systematic evaluation and resolution of GSI-158.
l The NRC staff is relying on the Maintenance Rule to ensure that risk-significant valves are properly installed and maintained. The staff stated that there are industry initiatives to address issues associated with POVs. We are concemed that unless the staff undertakes a proactive effort to ensure resolution of this issue, the industry initiative will remain an optional, voluntary program that will not fully address the concems of GSI-158. We plan to continue our discussion with the staff regarding the resolution of our concems.
Sincerely, Dana A. Powers Chairman
Reference:
Memorandum dated April 5,1999, from John W. Craig, Office of Nuclear Regulatory Research to John T. Larkins, ACRS,
Subject:
Resolution of Generic Safety issue 158, " Performance of Safety-Related Power-Operated Valves Under Design Basis Conditions."
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1 ,-
c CONTENTS l AB B R EVIATION S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v .
EX EC U TIVE S U M M ARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi 1 I N TR O D U CTIO N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ......... 1 2 USE AND APPLICATION OF AlR OPERATED VALVES . . .
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3 OPERATING EXPERIENCE . . . . . . . . . . . . . . jr.'....... ..
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4 s. # s 4 S ITE VISITS . . . . . . . . . . . . . . . . . . . . . . . . . . 1..... ........
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,.. 'y 5 INDUSTRY INITIATIVES . . . . . . . . . . . . . . . . ,.....,.....................10 A
6 AIR-OPERATED 6.1 VALVE FAILURES AND RIK.%. :: u)
O ve rvie w . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . * : . ~. . '.' ,. . . . . . . . . . . . . . 12 6.2 Risk Achievement Worth . . . . . . . .a... . . . . . . 'it 6.3 Accident Sequence Precurso .. ., . .s
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7 FIN DIN G S . . . . . . . . . . . . . . . . . f. . . . . '; . . e . 4r.f. . . . . . . . . . . . . . . . . . . 13
- 7.1 Site Visits - AOV Progrpms - Anal sis an 7estipg of AOVs . . . . . . . . . . . . . 13 7.2 Operating Experience' .f. . . . . . . . . . . . .[: ~ . . . . . . . . . . . . . . . . . . . . . . . 14 7.3 ommon- use Failures . . . . . . . . . . . . . . . . 15 Risk Achievement)$orttis and 7.4 Risk- Accident Sequence Pfecursors ............................15 7.5 Dampers (" uartar-turn AOys"), , , f . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 8
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QONCLUSIONSgc . . . . .'. . . . . . . N.Y.".'. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5 8'1 Parallelisms qith Motor-Operated Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 8.2 AOV Prog ra msg. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 ,
8.3 upporting Pneumatic Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 l 8.4,Atan.d-Alone SysterY1 A. ir-Operated Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 8.5; Other'P wer-Operated Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
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9 REFERENCES '.y,. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
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TABLES l
+. ; . % - V 1 opulations of Air-operated Valves in Plants Visited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2 Pla nts Visite d . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3 Status of Alr-Operated Valve Programs at Time of Site Visits ...................... 9 4 Elements of an Effective Air-Operated Valve Program . . . . . . . . . . . . . . . . . . . . . . . . . . 17 ill
ABBREVIATIONS .
ADV atmospheric dump vaive -
AEOD Analysis and Evaluation of Operational Data (Office for)
AOV air-operated valve AOV-JOG Air-Operated Valve Joint Owners Group ASME American Society of Mechanical Engineers ASP Accident Sequence Procursor 7. f l AUG Air-Operated Valve Us ers Group ..:. O !
. .:?.'.Q l BWR boiling-water reactor jP' , ' :.;J ,r,5,4
.;; .A CCDP conditional core damage probability e 1,49
'[d 7 ;v.
EPRI Electric Power Research Institute / ^ I . h..
'd. '.*t**g i
GL Generic Letter . g . ,3.,. ,
p3#
IN information Notice p ~)) -
HOV hydraulic-operated valv .
/, j
[ ! '
INEEL Idaho National Engineering aryd Environ ental Laboratory INPO Institute of Nuclear Power O erations / .
IPE individual plant evaluation - ..- .f .j IPEEE individual lant e' valuation f extemal events '
LER licensee eve report _...
LWR light-water rea -' .
. : $lj
.MOV onotor-operated valve
- MUG .- Motor-Qperated Valve Users Group
\.4 NEl [ _
Nuclear EnergyInstitute P RV y
).
power-operated relief valve RV. pressure regulator valve A< babilistic safety assessment
+.<- ,
.. , :. t.,3 .- ..
V - .solenold-operated valve TEP top event prevention v
fi m-o .u . . . _ , _ . V a_. ... .
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EXECUTIVE
SUMMARY
This study was initiated by NRC's Office for Analysis and Evaluation of Operational Data' to help the Nuclear Regulatory Commission determine if additional attention needed to be focused -
i on air-operated valves (AOVs). This report and its companion document. Idaho National Engineering and Environmental Laboratory draft report (INEEL)/ EXT-98-00383, "A Study of Air-Operated Valves in Nuclear Power Plants," present the results of a comprehenpive review of AOV operating experience, and visits to 7 U.S. light water reactor sites at which ere are i 11 operating reactors. 3 y
)
Plant visits were conducted to obtain information about AO[operati experience and AOV activities. Discussions on operating experience focusedp'n the root ca ses of AOV failures agtr on the plants' corrective actions. The licensees provided detailed inform 5 tion about the playlF AOV programs. Features of the AOV programs that were discussed included,1dentification of risk-Important AOVs, design margins, design verificatidn, diagnostic testing, ma, intenance' practices, ageing, participation in industry AOV activities, parallelisms between AbV and MOV experience and activities. i, The study includes information on over 100 events which ir de common-cause failures or.
- degradations of AOVs in important systems suchjgs emergency' re cooling systems, residual heat removal systems, auxiliary feedwater systems, emergency ac ower systems, and boiling-water reactor scram systems. o h. "'
o Each plant visited had an AOV program j Those ;
methodologies from the plant probab.itistic riskand sessments as$0V programsrule the maintenance used to risk-informed ) ,
categorize the plant AOV populations. piany,put not all ,of the licensees' AOV programs were !
or were planning to perform analysis and diagnostic testing to confirm that important AOVs had - 4 the capability of performing in accordance pith their design. Similar to what was found with motor-operated valves, use 6f n,ewly developed diagnostic equipment has helped utilities ;
discover deficiencies anf weaknesses in he design, analysis, maintenance, and testing of AOVs. Tfiose AOV programs vary significantly from plant-to-plant. The plant AOV programs are volurita and there are explicit regulatory requirements goveming them.
The study conc udes that implementation of an effective AOV program can minimize the likelihood for effmmon-cause AOVla,ilures.
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i Effective March 28,1999. The Office for Anafysis and Evaluation of Operational Data was disbanded. The work described in this report which was initiated by AEOD is being completed by the Regulatory Effectiveness Assessment and Human Factors Branch of the NRC's Office of Nuclear Regulatory Research.
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1 INTRODUCTION To assess the status of air operated valves (AOVs) at U.S. light-water reactors (LWRs), the Office for Analysis and Evaluation of Operational Data (AEOD) and the Idaho National .
Engineering and Environmental Laboratory (INEEL) engineers visited 7 reactor sites which house 11 operating U.S. LWRs representing about 10 percent of the currently operating
. U.S. LWRs.. The site visits provided an important sampling of the AOV activities a d programs at U.S. LWR plants. In addition,' AEOD staff had discussions with engineers at ny other U.S. LWR facilities and with members of nuclear industry groups such r-Operated Valve Users Group (AUG), Motor-Operated Valve Users Group (MUG)/s the Operati ' (INPO),
, Air-Operated Nuclear Valve Joint Owners Energy Institute Group (NEl), American(AOV-JOG), institute Society of Mechanical png of Nuclear Powp[ineers
) Operating and g (A
- Maintenance Working Groups on AOVs and hydraulic rated val Vs)[ASME O&ffG),
and motor operated valves (MOVs) [ASME O&M 8].
i g , g r' To better understand plant AOV activities, AEOD visit slid n plant sites to disc ssYeh licensee's AOV programs. The information gathered fron) those visits is an important part of this study. The focus of this study is on important AOVsivhlph could affect plant safety systems and as such are within the purview of NRC's(egulati . ;, h l 2
gg -
AOVs are used in all used U.S.a.wid g; LWRs. *~.
They re/USE AND A variety of applications. Some AOVs i
perform important functions in safety a .d nonsafety-relat systems which could affect initiating .
event frequencies, accident mitigation, pnd radiological re ases.
An AOV is a complex system pi of e ma mponents: the actuator, the valve .
(body), and the controller. fach of the major components includes numerous " place-parts' I such as djaphragms, spJ i ngs, limit switchds, solenoid operators, positioners, current / pressure (1/p) conyerters, voltage 7 pressure (e/p) converters, accumulators, o-rings, lubricants, filters, j regulators;gokes, bonnets, d seals. Electricity is required for control and air systems are 1 required to pro e motive po .
Table 1 contains a listing of the AO , populations at the 7 sites (11 plants) visited during this study. T) licensees v sited stated that their plants had between 400 and 2800 AOVs. Each of the plan)ts visited has c{ategorized between 50 and 500 3 AOVs as " safety-re sig ificance,""important'toapfety," or a combination thereof. The remaining AOVs (the -
m ty of AOVs at eacfi plant) were determined to have little or no safety-significance, m /
me AOV applicatio}ns appear to be common to many plants. For exam se AOVs for contninment isolation functions and for main steam systems. U.S. boiling-water actors (BWR's) use AOVs in their scram systems. U.S. pressurized-water reactors use AOVs forycontrolling auxiliary and main feedwater and for condensate systems. The majority of AOVs at U.S. LWRs are nonsafety-related and are generally associated with the non-nuclear balance of plant. Nonetheless many plants visited identified a number of *important" or " risk important" AOVs which had been classified as nonsafety-mlated.
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Table 1 Populations of Air-operated Valves in Plants Visited Plant Safety Related Category 1 Category 2 Category 3 GL 89-10' Name AOVs AOVs ADVs AOVs MOVs Palo Verde 41 + 131 = 172 AOVs 41 AOVs per plant 131 AOVs per plant are Approximately 2628 There are 831 123 per plant are dassmed are dassified by the dassified by the licensee AOVs per plant are MOVs on site by the licensee as licensee as as Category 2. The dassmed by the (3 plants)of safety-related. See Category 1. The licensee refers to licens,ee as Ca 3. which 336 are in Category 1 and 2. licensee refers to nonachve safety related The, licensee , rs to the GL 8910 active safety-related AOVs as Category 3, noyfety-related AOVs program.
AOVs as Category 1, f. as, Category 3 Fermi 2 22 AOVs in Category 1 403 AOVs are 147 MO are in and 34 AOVs in dassified by the 82 AOVs are hlfiedCa,tahr43 AOVs are by the heensee as I
,those
- hap Uttle or no theyL'h9-10 Category 2 (56 total) licensee as Category 2 ihuding safety-signtn nce or program, are safety-related Category 1. The 24 safety-related AOVs ' economic ./
according to the licensee refers to consequences? "'
program plan draft AOVs having *high The hcensekdesignates as Category 2 those less (Note: The original 3
j safety-signmcance" safety-significa'nt AOVs 1995 rough outline for (There are also 2482 as Category 1. development of the solenoid-operated included are 370 that related support funp6ons or safety ke Fermi 2 AOV program valves (SOVs) of which SCRAM inlet and relatively high econom68 lists a total of 2058 1442 are classified by outlet valves, cons quencesif they gAOVs of which 598 the licensee as QA1.) 22 safety related fall. 4 ogre considered safety-valves, and 11 risk- ,c g related valves or signmcant valves #ampers, and 1460 were considered
. - . . nonsafety-related u .: valves or dampers.)
safety-related AOVs this category are by the licensee as AOVs which are not MOVs in the was not provided. See safetypelsted with Category 2.These AOVs Category 1 or 2 are plant of which 30 Categones 1 and 2. jetive, safety are safety-related but of dassified by the are covered by funcbons, importan low risk-signmcance or licensee as Category 3 GL 89-10.
to-safety based on nonsafety-related but AOVs.
^
y their probabilistic used in *critica!"
safety assessment applications (PSA), risk '
signlficance,or 28
, includedhood on
.5 Expert Pan'el.
, determinations.
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LaSalie 12/ 84 for both $ nits. AOVs having high AOVs having low safety AOVs having high There are 200 safety signifcance, signmcance. Number not economic signmcance. MOVs in the in addition,370 con , Number not provided. Number not provided. GL 89-10 rod drive hydraulic s provu$ed (LaSalle categorizes progmm for both valves in each unitere AOVs with no or limited units.
l classified by the '(, safety / economic
[ ' licensee asJdety- significanoe as b-related.T / '
Category 4.) (There are
. 1575 nonsafety-related
.',,I'" AOVs for both units.)
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Table 1 Populations of Alr operated Valves in Plants Visited (Cont.)
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- Plant Safety Related . Category 1 Category 2 Category 3 GL 391o* *
.Name AOVs AOVs 'AOVs . AOVs MOVs I TMI1 98 AOVs are desemed 98 AOVs are 328 AOVs are 484 AOVs are There are 81 as safety-related categortred as Class categorized as Class 2 categortred as Class 3 MOVs in the (A C N *G eless" 1 by the licensee by the licensee. These by the leensee . GL 8s 10 or Class 1') by tie These are AOVs with are AOVs with an EOP program for this are A9Vs not liconese, an active esfoty function or operstonal categortzed 1 plant.
fundion. econorme sigq are a total of 910 f- s at TMI-1.
Indien 263 AOVs are - The licensee did not The licensee hno'f Theb(tees did no(
- 89 MOV[are Point 3 classmed as safety- classify AOVs as dessify AOVp as deselfy AQVs as within the scope related by the licensee Category 1,2, or 3. Category 1, . or 3. . Category 1%.or 3c - g.GL'A9-10.
(215 AOVs were g', .There are 5789Vs in ' y
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e,e nonsafe,-
within the scope of . , , . .
the Maintenance ---
N i Rule.10 CFR 50.65 } d.1% I (Ref.1)) A Turkey The licensee dassified 174 AoVs (98 oclive, 3[actNo.19 pesolve, Khere are 836 AOVs in 111 MOVs (total -
Point 3 4 191 AOVs(totalfor 76 passive, total for i for both units) are both units it is not for both units) both units) es safety- both units) are ssified, by the licensee knownif thelicensee are within the related. classified by the as Ca . ., specifically designated scope of J licensee as /
- Category 1. - "
Category 3. {
- Safe - e,ated Mot -Operat alve Testing and Surveillance - 10 CFR 50.54(f)," June 28,1989 (Ref. iy' :/
y s 8 "
NOTE: r
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The category designations in
' table vary from p (nt-to-plant
~ " The use of the categories for each plant is cxplained wt the entry. '
. . , , ,1 There may be S Vgin the plants tha re classified as part of the AOV. Figures for SOVs were included if separate data was pro ided. q,
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,#N . s, 3 OPERATING EXPERIENCE 4
. INE L draft repoft,"A Shudy cIf Air-Operated Valves at U.S. Nuclear Power Plants,"
ItfEEUEXT-98-00383, April 26,1999 (Ref 3), contains summaries of 109 AOV events that were reported in LERs,, and 24 additional events that were not reported in LERs. Selected OV events are list $d below. Plant name, licensee event report (LER) number, and a short scription of e(ch event is presented. The conditional core damage probability (CCDP) culated in,NRC's Accident Sequence Precursor (ASP) Program is also shown when av labler
s 3
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Palisades (LER 255/78-003 and 255/81-030)
On two occasions, water in the instrument air system prevented an AOV in the residual heat removal heat exchanger outlet line from opening (going to its " fall-safe" position). The two -
failures of the same AOV resulted in rapid core heat-up from cold shutdown to near boiling (215
- F and 197 'F in 45 minutes and about 1-3/4 hours respectively). Although these events occurred in 1970 and 1981, they are included because the poor quality air conditio s that led to these events existed at the plant at the time of our site visit.
Turkey Point 3 (LERs 250/85-019 and 250/85-021) ASP CCDP = 0.0E-04 4 2.1, . - N While in hot standby recovering from a prior reactor trip, OVs in the pux(liary feedwater and/
main feedwater systems failed on demand complicating the recove,r)f Multip,le failures off0Vs and other pneumatic equipment were attributed to moisture and . rrosion products in thef instrument air system. g. g Palo Verde 3 (LER 530/89-001) hN F..,:.4 ASP CCDP = 4.9E-05 Palo Verde 1,2,3 (LER 528/89-005) ' M h.g' Failure of all four atmospheric dump valves (ADVs)1AOVs] to fun 'on on demand at Palo Verde Unit 3 subsequent to reactor trip contributed to a complicate rgcovery. The manufacturer found design deficiencies in alfthreelinits' 12 ADVs ,bxcessive intemal leakage which could result in inability to operate pie ADVs fronige control' rooms or the remote shutdown panels at all three Palo Verde units. TJIe licensge also found that incorrect valve set
- up and poor quality air contributed o'tli,e unit three ADV failures.
, u) _. i Hope Creek (LERs 354/93-006 d 354/ 1,7)
, f % s RepetitivefDV failures,Jnc,luding two set of concurrent failures of AOVs in the Safe Cooling' System. A licengee initiated desig,n change (modification of valve packing without taking inlo. account the effec of the new lower friction) compromised room cooling for all plant emergency' diesel generators 8 AOVs) and emergency core cooling systems (24 AOVs).
pf Oyster Creek t.ER {y '219/85-012)Y ASP CCDP = 2.3E-04 Two 40 in series scha ischarge volume drain line failed to close on demand subpequent to a reactorperg,m, resulting in an uncontrolled leak of hot pressurized reactor coplant outside primarypontainment. The failures were caused by inadequate AOV set-up and d,esign (improper stro e adjustment and an improperiy sized spring).
erm$nt Yankee.(l'E 271/98-025, EN 35150) '.
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' mdn-cause failures (CCFs) of scram discharge drain lines (four AOVs). The AOVs had ina equate design margin. Surveillance testing revealed multiple AOV malfunctions shortly after their installation.
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I Millstone 2 (LER 336/97-011, EN 32070) i l
Nineteen of 23 AOVs serving in containment isolation functions failed to isolate under full system pressure. The failures were attributed to improper set up. Full pressure testing had .
never been done. Failure of the three AOVs which isolate letdown would result in offsite radiation doses higher than stated in the plant's final safety analysis report. Two of three AOVs in the letdown line had malfunctioned 4-years earfier but the problem was not corr eted - see LER 336/93-023 below. l Millstone 2 (LER 336/93423)
'Ng While at full reactor coolant system pressure with valve closed, two AOVs in the letdown line were leaking between 20 and 40 gpmg The licensee /
attributed the leakage to improper bench setting of the failure to test the AOVs at full reactor coolant system p%OVs. Tfe licensee ; '
licensee acknowledged the need to verify isolation Qse valvesof th[ essure against was full reactor a contributing,cau coolant system pressure however verification was not done until 4,- ears later (see LER 336/97-011 l above). w. 4.3 r.2 g.g 1 LaSalle (LER 374/96-011), NRC Information Notied]IN) 96-68 (Ref,4)1f LaSalle station's review of AOV diagnosticle/st h,. \fbI5.and load calculations rev!
AOV manufacturers published data on effective diaphragm areas.' Use of the manufacturers erroneous effective diaphragm areas cpuld resul (n incorr et se.t-up values and consequent fa!!ure during design-basis events. ' M' '
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- San Onofre 2 and 3 (LER 361/9 11)
While pursulhg an AOV tesdng rogram s.rnila 13 theif MOV program, the licensee found severalyontainment isolation valves [AOVs] which would not have been capable to closing under d~esign-basis conditions. The licensee attributed the deficiencies to errors in the manufactulefs analysis and' setup errors that emanated from using the manufacturers outdated andlncorrect setup in'structions.*
Haddam eck(LER
) s 94-00
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NRC IN 95 34 (Ref. 5) ASP CCDP = 1.4E-04 Both of the pressurizer power-operated relief valves (PORVs)[AOVs] failed to open on demand dupn,g a trst while the plant was in cold shutdown. The failures were attributed to air leaks c9used by improper AOV diaphragm installation by the licensee, improper use of lubricant on i e diaphragms causell them to extrude enabling the air leakage.
ladda'm NeckfL 93-007) ASP CCDP = 6.5E-05
.;. .a W A test of the ernergency air accumulator, used for PORV operation during feed and bleed cooling, revealed execssive leakage through a PORV's diaphragm and pressure regulator. The diaphragm had been instailed improperly. The pressure regulator leaked because of corrosion products which resulted from moisture in the air system which was caused by a malfunctioning air dryer SOV.
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Salem 1 (LER 272/91-030-01)
Recurring PORV [AOV) failures at Units 1 and 2 and the failure of both Unit 1 PORVs to open on demand during testing. The apparent cause was air leakage around the diaphragms. -
Contributing factors for many of the failuras were: failure to use manufacturer's installation procedures, valve temperatures in excess of their design temperatures, and pipeline induced vibration. The LER noted similar experience with AOVs which are used as pressurizer spray valves at Salem units 1 and 2.
Fermi 2 (DER 97-1202-plant intemal deficiency report) ,,
n x ;.h Eighteen SOVs controlling safety related AOVs failed du ng an 18-month period. The root cause was excessive use of thread locking compound on threaded jofntsyigration of va from the thread locking compound deposited on surfa s of the SOVs causi them to sti :
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NRC IN 88-24 (Ref. 6) -
Kewaunee (LER 305/87-12) -
Calvert Cliffs (10 CFR 50.72 Reports 12013 and 1201 p 4,1988) ,
],e s'. A NRC IN 88-24 notified all U.S. LWR licensees ofynditinns at ewaunee'and Calvert Cliffs where common-cause AOV failures did/could result from overpressurizing SOVs (which are piece-parts of AOVs). The IN Indicated thalflilures could result in failure of safety-related quentAOVs. Subse,of to the issuance of the IN,noncafety-relahed several p
. licensees found similar situations at thejr' plants. piowever,,in recerit years severallicensees '
found similar vulnerabilities that their original reyfew of IN 88-24 did not find, for example:
'r ; -
Clinton (LER 461/90-004) ;,P ,
indian Millstone Point 3 (LER 286/93-p)50 3 (LER 423/96-031
-y5. G7 I Cooper (Inspection Repprt 50-298/97-201 _ -;F Waterfordl(LER 382/98-010)D.C. .
A Cook LERs 315/97-tq6-01 and 315/98-052/01)
\ .. 2 . #.".h Relevant Non U5. Events '
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Darlingto/n U it 2 (DEven Notification Report D-1998-01497 and Detailed Event R D-1998-01497): {y?
S'eptember 20,199[ while restoring the instrument air system during an outage,18 of 0 " pressure regulator valves (PRVs)" failed, exposing downstream AOVs to full-system ressure. The PRVj failures were attributed to embrittled diaphragms coupled with the large l
, ad that was placed on the PRV diaphragms when the air system pressure was being restored. i
'ye licensee noted that the occurrence of such an event could cause safety-related AOVs to be !
forced.to a position opposite from their " loss of air position," and that they could be damaged and remain in that "non-safe position." An analagous situation could occur at a U.S. plant during a recovery from a loss of offsite power or a loss of instrument air.
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Pbkering Unit 2 [ Canada) (SER A-94 plant root cause failure report):
On December 10,1994, a " thermally aged" diaphragm in a pressure relief valve [AOVJ in the primary heat transport system cracked initiating a small break loss-of-coolant accident. As a .
result of that event, Canadian plants have implemented programs to replace existing diaphragms and implement programs for ensuring appropriate diaphragm replacement frequencies in safety-related systems.
Bruce "A" [ Canada) (Technical Paper by Ferguson and Fitzgerald at th/Drgan n for l
Economic Cooperation and Development /intemal Atomic E ergy Ag ncy Joint Specialist Meeting on Motor Operated Valve issues, April 1994): ..)
. 4% ,
/ 4lt, tg in 1991 diagnostic testing was incorporated into an AO preventive alnte ance program ,
Initial diagnostic testing (322 tests) found that: 65 pere'ent of the.1/ps and pos tgriers requirid calibration,15 percent of the bench sets needed adjus nt,affd only 12 percent the AOVs required no maintenance or adjustment. In subseque iagnostic testing (88 test ,45 percent of the 1/ps and positioners required calibration,5 perce ithe s bench sets needed adjustment, and 22 percent of the AOVs required no maintenance 4r adju tment.g a h. Y.
4 y SITE VISITS a C .'.Q y 7. A,ofX ,
Seven site visits were conducted betwee October 9' nd Ma 1998. Each visitlasted .
the reactor manufacturer, the j 2 days.engineer, architect Tableand 2 lists thetheplant the year name, plant be
^' tJe dates of ti fhe vis I t '
The site visit team ~..
included p one, fromngineer INEEL, and one fp;gan co m AEO Awo engineers j engineer from either NRR or RES. Durin most of visits, the NRC resident inspectors ,
attended the' entrance d[or exit intervie s that.vyere held on site.
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The visilts gsually include ' plant walk-throughs, discussions with licensing personnel and engineers, plant operators and plant maintenance peisonnel affiliated with AOV activities. Discussion's gere hel'dregarding plant AOV operating experience and plant programs assonated with AOVs. In addition comprehensive discussions were held with personnelissocLied ylth plant PSA's (individual plant evaluations [lPE's) and Individual plant evaluation of extemal events [lPEEEs]) and " maintenance rule" (10 CFR 50.65 [Ref.1]) ,
act ities. Detailed trip rspop from the site visits appear in Appendix C of Reference 3.
I a T e plants visited we hosen in a manner to get a representative cross-section of the
.S. LWR populati n accordance with the following criteria:
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- plant a AEOD project schedule availabliity
- 3. plant participation in AOV users group activities
- 4. plant type and age.
7 1
I
rm _
^
Participation by the licensees was voluntary and participants were assured that the visits were
' independent fact finding / lessons loamed activities," not inspection or regulatory compliance activities.
Table 2 Plants Visited Plant Dates Plant Description / f Year' Commercial Name of Visits Architect Engineer / Operation Began 1
Palo Verde 10/28-29/97 Combustion Engineering, loop, ; ;Q l 1-2-3 System 80 (no PORVs) R/Bechtel %, 1986 [
Fermi 2 11/03-04/97 General Electric BWR 4fDetroit Epison h.1988d i Palisades 11/18-19/97 Combustion Engineering,~ two Idip M7(
V PWR/Bechtel LaSalle12 12/17-18/97 General Electric BWR([Sarg'e &, h 1984 Lundy ,
- ~M p
TMI 1' 02/12-13/98 Babcock and yil5x, lowered loop 1974 i
PWR/Gilber) Associales A
.. Indian 03/10-11/98 Westing,hdu'se, fourIoopMVR/ United 1976 Point 3 Engineers and C,c'nstructorM ;
Turkey . 03/24-25/98 tinghouse;'three MWR/Bechtel 1972 Point 3-4 /
, h, ,
I.
AOV Procrams at Sites isited All of the p nts visited had rograms in place. All of the programs were aimed at '
improving AO[ performance. However, there were many differences in the status and the depth of the programs at each station (see Table 3). Reference 3 provides details of the progra s at the statio visited.y
,. p2 .
Th9 OV programs at a'l olthe stations visited had been or were in the process of surveying, c9tegorizing, and rankl their AOV populations.- Table 1 contains a summary of the ytegorizations and rp king efforts at each of the seven stations visited. The methodologies 1 sed to categorizeAnd rank the AOVs at the plants visited included: review of plant operating ;
lxperience, consl'deration of the results of plant PSAs, the use of expert panels, consideration (Frequently these activities were part of licensee implementh*lon of the main licensees' evaluations utilized IPE and IPEEE methodologies and results. Many licensees' categorizations considered risk achievement worths, Fussell-Vesley or other risk importance measures.
8 l
d l
Table 3 Status of Air Operated Valve Programs at Time of Site Visits
' ~
Categorization Diagnostic Testing
- Plant Status Being Done Findings (
l Palo Verde Complete Static and Dynamic Low margins- '
replaced /modifi AOVs Fermi Nearing Completion To be determined p Calcu{ations# planned Palisades Complete Static. Dynamic betr[ Low r3argins A 3 planned. g repla5ed/rpodified'AOVs /
LaSalle Complete Static j dImarginke.4%*
.. .s_./ replaced /modifie(AOVacFound
(~ generic effective diaphragm area problem described in T
N5 IN 96-68.
TMI1 Complete Static planned, . 4ow margins- modified AOVs Indian Point 3 Complete Static . . . .
Lowsmargins -
IN O replaced / modified AOVs
, Turkey Point Complete S tic .
Focusing on maintenance /
/ L operations. Limited testing of
/ , problem AOVs. '
a
- f.
Dynamic testing: testingfcohddcted with systemyre)ssure and/or flow.
Static testing: testing cond'ucted at aroblent conditions without system pressure or flow.
- >m ey y ,
The Palisa(es and Fermi p ants are lead plants in a program funded by EPRI to develop /
confirm analytipal techniques fo(predicting AOV performance and design margins. At the time of our visits to t.bose plants, both plants had categorized and prioritized or ranked their AOVs.
A contractor h'ad pe(ormed analyses on the Palisades plant's AOVs. The Palisades plant staff had perfor'rned static testing of their AOVs, and was in the process of planning to perform dyna,mic diagnostic testhg. In contrast, the Fermi plant had hired a contractor to conduct analyses of the most important (Category 1) AOVs, but had not established any specific plans
' diagnostic testing ofA. OVs. -
f ato Verde's AOVyrogram was initiated many years ago. Having experienced common-cause OV failures as early as 1989, the Palo Verde plant initiated an aggressive program to prevent Fs. The Palo Verde staff performed static and dynamic test of AOVs which appeared to havalow operating margins. As a result of analyses which indicaied less than desired design margins, coupled with the results of static and in some cases, dynamic testing, Palo Verde made modifications to certain AOVs to assure satisfactory operation during design basis events.
9
.. n - . ~ . x ,
In order to analyze their AOVs, many of the utilities canvassed' have had to purchase design information and analyses from the AOV manufacturers since that information was not provided with the valves, it appears that some of the original AOV design information may have been ;
provided to the architect engineers but the utilities were not privy to many of the details of the -
AOVs' design analyses or avaliable margins. Recently, there have been several cases in which
' utihties evaluated their AOVs and found errors in the AOV manufacturers' design calculations l ss well as errors in the valve designs (e.g., Crane-Aloyco, Fisher, Anchor-Darling / CF/WKM/
BS&B [ described in Reference 3]). In addition, many AO'/ manufacturefs have .t provided sufficient guidance or instructions for AOV maintenance or changeout./"Simila y, regarding SOVs which are important piece-parts of AOVs, NUREG-1 5, Vol p, Operating Experience l Feedbao. Report-Solenold-Operated Valve Problems," . Nuclearyegulatory Commission ;
Office for Analysis and Evaluation of Operational Data, F bruary 199h noted many cases / ;
where SOV manufacturers did not provide utilities with ufficient idanceN rmaintenanje dnd change-out of SOVs which control the AOVs.
- 8" i *cyg./
p1 'V AOV programs at the stations visited either were using qr were planning to use AOV diagnostic testing equipment. In addition to the plants visited, feedback from industry meetings indicates that plants have had favorable results using AOV diagnostic tqsting equipment to diagnose and fix specific AOV problems. In many cases, as a result of using agnostic testing equipment, the utilities have made modifications to AOVs to, improve their o(peration. So that they use AOV diagnostic testing equipmept routinely to confimithat AOVs have been set up correctly, in a presentation at a recent AUG mee, ting, a valve engineer stated that at his plant, AOV diagnostic testing equipment)s the too of olce"to assure that the AOVs have .
. been set up correctly. P h ~
Some plants have performed AOVIagnostic testing under prototypic dynamic conditions.
However, most plants' AOV diagrfostic testi prototypic design loading copditions. In som,ng e cases, successful has bee,n'done static diagnostic testing may statically, I be able to perform its safety function under design not provideJhe loading r'iditions. assurance 3g that An AOV w(Qv A ' ? ,7 b., i 5 INDUS Y INIT!ATIVE I Operating experience has shown that many of the problems associated with MOVs such as ction or actuator sizing, verification of valve capability, design loading, valve sizirig, lack of vendor packing,] tion, nonprototypic survelliance testing, informa verificatio operating capability also'eidst with AOVs. Industry organizations (INPO, EPRI, AUG) have ,
encouraged licensees to take the initiative to translate the lessons leamed from the MOV l operating experiencejlnd the diagnostic testing associated with MOVs to AOVs. As noted in 1 4ection 4 of this report, licensees at the seven sites visited have initiated AOV programs to iddress those and other similar problems. Those AOV programs vary in age, resources, and i Qfectiveness! They are voluntary, they use risk-informeo techniques drawing from operating expgce, the maintenance rule, plant IPE and IPEEEs, plant operating and emergency 8
Plants canvassed includes the seven stations visited plus others that had representatives at AOV industry meetings.
10
F .- -. - -. _
l
,, procedures, plant technical specifications, etc., to identify important AOVs, the design capability of which need to be verified. Some licensees have performed analyses and diagnostic tests to * ,
verify the capability of certain AOVs. Some utilities use diagnostic testing equipment to improve )
the set-up and maintenance of their AOVs. However, some licensees are not addressing the AOV issues discussed in this report. From a nuclear industry organization's presentation at a .
. recent AOV users group meeting (Ref. 7), it appears that some plants' AOV programs are understaffed and underfunded.
In 1997, a nuclear industry organization notified all U.S. LWRs of concems that op'erating experience was showing that many of the problems associated with MOVs we,re also present with AOVs, and that AOVs warranted further attention. At about the same time, EPRI implemented AOV pilot programs at the Palisades and Feyril plants 4nd recently expanded to the Duane important AOVs,Amold and Comanche the development Peakchniques, of AOV calculationa plants.an_EPRl's rogram p suppo,d verific design capabilities. //
7 Qag
' 'a y in 1998, similar to what was done with MOVs, U.S. L licensees formed an Al k)perated Valve Joint Owners' Group (AOV-JOG). AOV-JOG's s ted mission is "to develop a common and cost-effective U.S. nuclear utility AOV program whfl i dqfines the minimum elements ,
necessary to enhance safe and reliable AOV performs,nce and, allow timely address of industry and regdatory AOV issues"(Ref. 6). The AOV-JOG initiatives argvoluntary industry activities.
At the present time, details of what AOV-JOG is pfoposing for resol tion of AOV issues at their ,
plants have not been presented to the NRC. ." ' Si
- e~- R5 e !
- in December 1998 at the AUG Number j meeting, a nuqlear indusiry organization representative stated that it was plannjrig to incrpsse its attivities in the area of AOVs including
" assistance visits" and holding AOV workshops 1n 1999. In addition, the nuclear industry organization indicated that it will piake AOv ' formation jresumably operating experience, readily available on its WEB horne page. -
g f/ .
O f The nuclearindustry org,anization representative provided a summary of the AOV findings from 14 site gisits. One strength that was common to many plants was their use of diagnostic testing equipmen 3 s, .i
~
Weaknesses are observed in following areas:
/-..
Some plants'have not done a'dequate reviews of other plants' AOV events.
t some plantshesting and sizing verifications of AOVs were not implemented.
. At some plants OVs have not been set up properly in some systems.
, For many AOVs the're were inadequate thrust assumptions.
_ , Plants changed,/. OV packing without considering the effect of the changed friction values.
Plants have n/ on information leamed from industry groups on inaccurate thrust ot acted calculations.
- D% y:. f Areas ofconcem at some plants are:
AOVs have low station priority.
Some stations have a high tolerance for AOV problems.
Lessons leamed from MOVs are not applied to AOVs.
Lack of budget to support AOV programs - don't do much until something is required.
11
- ~ - ...u.._ ... 3 . .s s.
Too Event Prevention Analysis Review of the technical paper,"Use of Top Event Presentation Analysis to Select a Safety-Significant Subset of Alr-Operated Valves for Testing" (Ref. 9), provided insight to the .
Monticello plant's AOV program. In a discussion with the Monticello plant staff and their contractor, we leamed about the Monticello plant's AOV program. The Monticello plant's AOV program is currently under development and expected to be finalized later this yea . The Monticello AOV program will be similar to the AOV programs at other plants (not earlierin this report). One difference is that Monticello plant's AOV program will/ise thy . op Event Prevention" (TEP) methodology to identify ' safety-significan r design basis review and periodic testing. The technical paper describes f some thework
~
resultryo,t" that the AOVs Monticello plant and its contractors have done to select safety-signifi nt AOVs us,ing the TEP methodology.
/
f -
.n .
The TEP methodology is commonly referred to as a
- nimump th set meth ology." ~1,t utilizes PSA techniques (the Monticello plant's IPE in t s case) to determine which equ,ipment must work in order to prevent the undesired event (top It tree event) from occurring. The Monticello plant's TEP analysis identified 24 "important*MO s. The technical paper indicated that if those 24 AOVs receive design-basis reviews an,d peri (odig testing, they c to be " reliable," and they would then be expected tp.have the reliagility and failure rates that 4 were used for AOVs in the Monticello IPE, Th technica1 paper reported that when the !
Monticello plant IPE's AOV failure rates were sed r those 24 AOVs and a failure rate of"one" i was assigned to all other active AOVs, thpre was a mall (8 percentj increase in the plant's l base case core damage frequency (CDf). 'In co st,he technical paper reported that failures l
of those AOVs would result in significaritincreases in CDF above the base case. ;
/ %, ~ ; \
ing the F ssell-Vesley importance and Risk The technical Achievement paper oalso Worth threshold reportef screening va thatwhen, lues ofp. percent and 2 0 res l
recommendations of NUMpRC 3-01,"inpustry Guldeline for Monitoring the Effectiveness of Maintenanc'e at Nuclea ower lants," M y 1993), the Monticello plant does not have any "potentialIy risk signifi OVs." In cont st, the technical paper stated that "while no AOVs exceed thr sholds for risk ig,nificance, in combination with one another, they can have a significant(enect if allowed to dqprade in reliability." On the other hand, TEP ana the combinatio'ns of AOVs which re important to safety."
/
f
- u .3 6 IR OPERATED VALVE FAILURES AND RISK 6/ j Overview
'y e hrimary concern r AOVs is that risk-significant AOVs satisfactorily perform their functions is assumed or apalyzed. Nuclear plant safety in the U.S. is predicated on the single-fallure jriterion; therefore, the failure of any single component should not result in unacceptable consequences. 'Therefore, one would expect that single AOV failures would not result in
~
unacceptable consequences. However, common-cause AOV failures can result in conditions more severe than those analyzed in the plant safety analyses.
12
l l
v.
9 6.2 Risk Achievement Worth From the plant visits, it became inherently obdeus that there are major differences in use, type, and number of AOVs at each plant. Table 1 shows the results of each of the plants AOV .
classifications. The bottom line of which is that each plant has identified a number of AOVs that are "important" and which may also have high " risk significance." The quantity and the distribution of AOVs vary widely from plant to plant. Recognizing that plant IPEs h ve shown l variations in which systems are most risk important, it is not surprising that the I lon of the risk important AOVs vary from plant to plant. Several plants provided th*e stu ' m with a
values of AOV risk achievement worth which indicated that failures o rtain OVs could significantly effect the risk from the plants in some casesge plant ound high AOV risk achievement worth values which Indicated that failures of those AOV uld lead to CDFs ma times greater than the CDFs which were estimated by t e plants' PSAs s's uming nominal generic AOV failure rates. '
4, 6.3 Accident Sequence Precursors '
- . h, A review of NRC's ASP program results found that forJhe years 1984.to 1995, there were 288 events that were classified as precursors (CCDPgreaterhequal to 10E-06). Twenty-six of those events were AOV related (i.e., AOV malfunctions were Igvolved as either initiators or contributors to the events). Twelve of those AOV related precursorgvents'had CCDP of 10E-04 or greater. The highest CCDP wasjhd 1985 loss of all auxiliary feedwater at Turkey ;
Point in which water contamination of theJnstrumenf air system resulted in common-cause AOV I
l 40 events that were found to be precursors that/ ear. No ,OV events after January 1,1995, j were classified as precursors by NRC's, ASP program.
. 07' i I
~7 a !
7 FINDINGS
.. . . A '
Visits to 7 U. (plant sites pro ided an overview of the status of AOVs at about 10 percent of the U.S. commercial LWR popuIat(on. Each plant visited was implementing an AOV program. '
However, there were widespread variations in the scope, focus, resources, status and future '
plans for7 each of thbrograms. All plants visited were integrating the knowledge gained from :
their maintenance rule,qctivities and their PSAs [lPE's) to categorize and prioritize AOV 4
,i activljes. py l 4 V each plant visited, tpe' licensee identified a number of important or risk-significant valves. In ,,
ome cases, AOVsjhat had been classified as "nonsafety-related" were found to be risk ignificant. . Conversely, some AOVs that were classified as " safety-related" were found not to risk signifiedrit-
'l
' ?. p.;; W
,- \
3 Risk achievement worth is the ratio of the. plant's core damage frequency calculated when j the component of interest has a failure rate of one divided by the plant's base case overall !
core damage frequency.
13 l
j
- - ~ .
\
There have been instances where licensees' AOV programs found that risk significant safety- '
related AOVs were not capable of performing their intended safety function during design basis events due to inadequate valve design or inadequate valve set up. Previous AOV testing under nonprototypic conditions was incapable of detecting some of these deficiencies. .
l Licensees found that AOV surveillance testing per technical specifications or ASME in-service-testing requirements dF ut always provide assurance that AOVs would perform tisfactorily i during design basis c3 ats.
f There was a wide variation in the status and plans for diagnostic test g o'f AOVs. Some plants j have done extensive static and dynamic testing of AOVs gn'd were I ng to upgrade their diagnostic testing equipment, whereas some other plan 'have, as y ot performed any AO diagnostic testing. v .# -
N, p ,
,t. , , , .
A significant problem facing the AOV engineers trying to determine the AOVs' perating'.#
margins is lack of AOV manufacturer design data. ' " ,( D' Validation and verification of the accuracy and efficacy , A V diagnostic testing equipment does not appear to be available at the present time. .1 .~cg 7.2 Operating Experience Q,., j A review of operating experience and visits to s UgS. plant sitesiound that many plants >
, have experienced or discovered AOV maIfunctions'or vulgerabilities which affected plant ,
operational safety or reduced plant operating margins. A n, umber of those malfunctions or vulnerabilities were due to a common cpuse which affected several valves.
l Licensees are more aware importancelof of the/ AOV,,s than ever before through the Electric Povyer Research Irystitule (EPRI), Nonethe19ss, recent operating ughsvents thro that 1998 indicate /NPO, plantsAOV-JOG, NEl and are finding conditions in the AEOD which AOVs are vulnerable to CCF from d'esign, installation and maintenance deficiencies as well as aire stem deficiencie Almost all plan s visited had observed s multiple CCF failures or degradations of AOVs and/or the SOVs contrpflir(g them. Those events were reported in plant intemal reports (condition reports, deviatior) r6 ports, et'c'(but many were not reported to the NRC or to INPO's Nuclear Plant Rellat]iiity Data Systemf Such omissions can lead to nonconservative beta factors and result in nonponservative PSA. Examples which are described in Reference 2 include: Fermi Unit 2
)aiisades pressure regulator failures; Turkey Point pilot-operated IPyT-580 thread kup valve failures /stic locker,) king; Three Mile Island Unit 1 Crane-Aloyco gate v (lmost all of theptants visited had experienced AOV failures that were caused by air-system E ntamination or moisture intrusion many years ago. Many of the licensees indicated that they observed significant improvements in the operation of AOVs, other pneumatic equipment, an overall plant operation as a result of substantive improvements that were made to the instrument air system and instrument air quality. The instrument air system and instrument air quality improvements were made as a result of NRC's GL 88-14," Instrument Air Supply System Problems Affecting Safety-Related Equipment," August 8,1988.
14
l l i 7.3 Risk Achievement Worths and Common-Cause Failures 1 From the visits, it was leamed that most of the plants calculated risk importance of their AOVs ! using their own probabilistic risk assessment models. Many of the licensees found AOVs - - I having high risk achievement worths and failure of these AOVs would affect important systems. I Failure of the high-risk achievement worth AOVs to perform their functions would translate to corresponding increases in CDF estimates. Another major concem for AOVs is r susceptibility to CCFs, which may not have been analyzed. i 1 These findings highlight the importance of verifying that important AO s will be capable of operating satisfactorily and for preventing common-cause OV.failu s.g a 7.4 Risk- Accident Sequence Precursors N n p w. ' y , Review of the results from NRC's ASP Program for the, years 1984 to 1995 found that AOV utors to about 10 percent'of the' events that were designated as precursors. AOVs were involv(ed in about two-dozen even CCDPs of greater than 10E-06, with about half of those fveqts having CCDPs of 10E-04 or greater. However, there were no AOV events after Jakiary f, 995, that had CCDPs greater than 10E-06. s NE?
^
J ,% 7.5 Dampers (* quarter-tum AOVs") .j'
~ ' e-s 4;,:x j . Licensees at most of the plants' visited and license s thht a have indicated that they are not inclu. ding air-oper'ated da,were mpers in their AOV programs.canvassed This at indust appears to be a carryover from their MpV progr'ams (responses to GL 89-10 and its supplements), it is interesting tof otel that at one dual unit station visited (LaSalle), the containment purge valves which are air-op,erated da,mpers have been evaluated by the plant (IPE results) to have a higt) Ask'importan . However, because the containment purge valves are categ AUG mee,orized as1998 tings in June
- dampers,"
and Decemb they are nspokesmen r 1998, covered forby AOV-JOG the licensee's AOV and EPRI program. both Also at discounted the need to cons (der alr-operated dampers in plant AOV programs. Further inquiry into this pos'ltion revealed that this position is simply an extension of the original position that the NRC had a'd, opted regardingigotor-operated dampers under the GL 89-10 program. The omission of the' motor-operated dampers from the GL 89-10 programs was based solely on their firepr$tection TUnption. Their performance during other design-basis events were not considered. 17W ' g' 8 CONCLUSION ' f e plants visiteprepresented a reasonable cross-section of the U.S. LWR population. The llowing conclusions are based on information obtained from those visits, discussions with AqV personnel at industry meetings, operating data, INEEL's AOV sensitivity study,
" Transmittal of Sensitivity Analysis for AOV Study, Job Code Number (JCN) E8238, Task Order 15-00R-03-98," December 1998, plant PSAs and ASP analyses.
5, 15
_ . . n. - . l 1 l 8.1 Paralleilsms With Motor-Operated Valves Operating experience has shown that common-cause AOV design deficiencies have resulted in situations where multiple AOVs could not perform their intended functions under design-basis . conditions as stipulated in plant safety analyses. The operating experience reported in LERs, inspection reports, and presentations made at AOV users group meetings indicates that there is a heightened awareness of the similarity between AOV and MOV issues. Similar tp the industry's formation of a joint owners group to help address the MOV issues [MpV-JOG) after the issuance of GL 89-10 and its supplements, an industry joint owners' group)6r AOVs has been formco [AOV-JOG). The AOV-JOG has not providedypecific plans and schedules or information regarding its members commitments to participatio,n and acceptance of the AOV-JOG's technical positions. Licensee participation in the e programs is oluntary.. AOV operability is subject to many of the same facto s MOVs puch s igh f ction or' valve] factors than those used or assumed in manufac urers' design calculationsg - , underestimation of loads during design basis operation, extrapolation of valve operabilit'y based on nonprototypic testing such as in-service testing, and, problems with valve setup and maintenance practices. The analytical and testing methods for verifying AOV operating capabilities are not yet proven and agreed upon. Continued discussions amo,ng'bRC, EPRI, nucle,ar plant owners, AOV manufacturers, and diagnostic testing equip ent manufacturers is needed to develop consensus.
, p4 ,
8.2 AOV Programs
- f. . -
During plant visits, we noted that/ork$ad ?t een done tp satisfy the requirements of GL 88-20,
" Individual Plant Examination fo[ Severe Apcident Vulnerabilities - 10 CFR 50.54(f)," .
November 23,1988, (and 1,ts supplements) and thetaintenance Rule (10 CFR 50.65 [Ref.1]) regarding ADVs and their supporting systgms formed the foundations of many of the licensees' AOV prog, rams. The objectives of those programs are to focus on AOVs and assure that they operate satisfactorily to achieve safe reliable economical plant operation. Ali of the pla visited had in ed AOV programs. Many, but not all of the programs focus on activities to con 7irm the capability and operability of important AOVs. There are large plant-to-plant variations in the types, numbers, applications, and risk importance of AOVs, and there are significant pro rammatic and schedular differences between the plants' AOV p rams. y Tpe U.S. NRC is parti pating with industry groups to communicate the lessons of operating experience.
,1 f
ffective AOVyrograms would include the following elements:
. g. . /
- 1) dentify risk significant AOVs, including those which are considered piece-parts in stand alone systems such as the emergency diesel generators.
16
I
- 2) Verify the operating capability of risk-significant AOVs under design-basis conditions, and periodically verify that the risk-significant AOVs' operating margins remain satisfactory.
- 3) Follow manufacturers' recommendations for SOV installation and maintenance regarding the use of thread sealants and lubricants. -
I I
- 4) Maintain instrument air quality in accordance with current industry stand s and guideline 3 [ISA-S7.0.01-1996, and ASME OM-17]. 7
. ,/.
, effectivepOV programs can Utilizing provide risk-informed assurance and that risk-significant AOVsmaintenance are capab o rule methodologie[f an'd will b satisfactorily in accordance with plant safety analyses. e elements'of hffective AOV programs are outlir,ed in Table 4. '
]: gg.. . : y,
.p . . y
- 1 Table 4 Elements of an Effective Air-Operated Valve Program'
/m ..
A. Catalogue the plant AOV population. Y NA B. Categorize the AOVs'importance based [" N, k Safety analyses final safety analysis repo icensing requirpments/ technical l l specifications i 4
, Plant PSA (IPEs and IPEEEs) .7p/9' '
CDF,large early release frequency ' Fussell-Vesley impo nee, risk achievement worth, TEP/ minimum path set, etc. Plant operating experie, luations ce Expert panel / maintenance rule eva/ y Transientinitiatorf f 7 8-
% . p" . '
fmergency op A.. (Abnormal oper,erating ati,ng proceduresprocedure C. Verify'that AOV installalion, operating conditions, interface conditions and environmental condition's are within the AOy's design. . D. Confirm' operating margins o$important" valves (and accumulators if applicable) for , d silgn basis ever(ts throug#4
~
. Analytical techniques Diagnostic testing *(static and/or dynamic testing as appropriate)
- f. Verify pneumatic $uid quality periodically (on a frequency in accordance with indus standards / guidelines [ISA-S7.0.001-1996/ASME OM-17]).
Including ' stand-alone systems'such as emergency diesel generators, BWR scram system, main steam relief and isolation systems, heat and ventilation systems, and air-operated dampers. 17
_ . - _ . _ - . . _u _ . _ . l i Table 4 Elements of an Effective Air Operated Valve Program (Cont.) F. Verify the adequacy and operability of safety-grade backup air accumulators Baseline: Verify accumulator sizing Periodic: Testing of check valves for leakage, monitoring / alarming accumulator pressure, verifying accumulator sizing, checking for the, presence of water accumulation A G. Perform preventive maintenance periodically on AOVs and their s0ppor}dstems AOV subcomponents (diaphragms, positioners, o-pngs, springs, etc.) AOV supporting components (SOVs, pressure regulators, filters, s etc.). Supporting pneumatic systems (dryers, filter, rryoisture separato.rs, compressors, f ' pressure regulators, extemal compressed gas / systems, a,ccumula(ors) ff H. Perform periodic surveillance testing to verify /cor(firm thato'perating makiqs of risk
- significant AOVs remain satisfactory for the duratipn of plant life. V>
- l. Train and sensitize plant operations and rr.aintenap'ce staff o t' the susceptibility of AOVs to CCFs emanating from their subcomponents, gppohiqg components, and their N
supporting pneumatic systems. - l
,, e M '\,
8.3 Supporting Pneumatic Systems ,-
, j Many plants' AOV programs are addre s ! '
AOVs; however, it appears that plantsmany are not,ssing focusingtheflesign, on the AOVs' o era, tion' , and testing asp supporting pneumatic systems. At many plants, additional attentior)inay be needed to focus more . attention on AOV supporting pnpumatic syyt' ems to minimize the likelihood for unanalyzed common-cause AOV failures. Of paramotlnt importance is the need to monitor the instrument I air quality.(moisture in particulai) in accordiance with current industry standards and guidelines ' (ISA-S7 .01-1996, and ASME OM-17). V-8.4 Stand- lone System Air- erated Valves N .* .:) At many plants,1mportant AOVs i t,tand-alone systems (emergency diesel generators, main steam relief and ' isolation systems, h'est and ventilation systems) have not been included in the plants'/OV programs)phese omissions were based on historical precedent, not on the risk-infor,m'ed methodology th,at is being used for developing plant AOV programs. Inclusion of these valves in plant AOV programs may identify some as risk significant. j..; y K.5 Other Power-Operated Valves tho gh they are not the subject of this report, considerations similar to those for AOVs may OV,s. Consideration of these valves may identify some as risk significant. 18
V * - 0 9 REFERENCES
- 1. U.S. Nuclear Regulatory Commission,10 CFR 50.65,
- Requirements for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants." .
- 2. U.S. Nuclear Regulatory Commission, Generic Letter 89-10, " Safety Related Motor-Operated Valve Testing and Surveillance - 10 CFR 50.54(f)," June 28,198 .
- 3. Idaho National Engineering and Environmental Laboratory draf(teport/A Study of Air-Operated Valves at U.S. Nuclear Power Plants," i EEUE 98-00383, April 26, 1999' WA, 4.
U.S. Nuclear Regulatory Commission, Information Notice 96
.A
. i ',.2..
*lqcorrect Effective Diaphragm Area Values in Vendor Manual Re It in Pot tialFailure f Pneumati -
Diaphragm Actuators," December 19,1996. ..
- 5. U.S. Nuclear Regulatory Commission, Informati rt Notice 95-34, " Air Actuator and Supply Air Regulator Problems in Copes-VulcarpPre surizer Power-Operated Relief Valves," August 25,1995, W v4.qq
- 6. U.S. Nuclear Regulatory Commission, fonIa' tion Notice '8-24,'"$ilures of Air-Operated Valves Affecting Safety R d stems," May 1 988.
- 7. .... Industry Perspective Air-Operated Va eskresented at 2nd Joint Meeting of the .
Air-Operated Valve and Motorpperated alve User's_ Group Meeting (AUG Meetmg 1 Number 16), December 1998 f / ,
- 8. Coleman, M.," JOG AOV
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Valve and Motor Operate d Valve / Program, resented er's Group Meeting (AUG>iMeeting 2nd Joint Number Meeting 16), of the Air-Op, Dece'mber 1998. b r 9.
/ . ,
.i i-7 Proceedings of the (th Intemational Conference on Probabilistic Safety Assessment and Ma'nagement. NierodegC.F., Wellumson, T.P., Worrell, R.B., Blanchard, D.P., "Use of Top Event Prevention Analysis to Select a Safety-Significant Subset of Air-Operated Valves for Testing," Septe'myr 1998.
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L , Boiling ' Water Reactor Owners Group Project No. 691 cc: Thomas J. Rausch, Chairman W. Glenn Warren Boiling Water Reactor Owners' Group Southern Nuclear / Georgia Power
. Commonwealth Edison Company E.I. Hatch Nuclear Plant Nuclear Fuel Services PO Box 1295 M/C B052 1400 Opus Place 4th Floor ETWill Birmingham, AL 35201 Downers Grove, IL 60515 Carl D. Teny Dennis B. Townsend Vice President, Nuclear Engineering GE Nuclear Energy Niagara Mohawk Power Corporation M/C 182 Nine Mile Point 2 175 Curtner Avenue PO Box 63 San Jose, CA 95125 Lycoming, NY 13093 Drew B. Fetters Thomas A. Green PECO Energy .
GE Nuclear Energy Nuclear Group Headquarters Mail Code 182 MC 62C-3 175 Curtner Avenue
. 965 Chesterbrook Blvd. San Jose, CA 95125 Wayne, PA 19087 l
John Hosmer l Commonwealth Edison Executive Towers,4th Floor 1400 Opus Place , Downers Grove, IL 60515 l George T. Jones i Pennsylvania Power & Light MC A6-1 Two North Ninth Street - Allentown, PA 18101 Lewis H. Sumner Southern Nuclear / Georgia Power E. I. Hatch Nuclear Power Plant 40 Inverness Parkway PO Box 1295
. Birmingham,GA 35201 John Kelly New York Power Authority 14th Floor Mail Stop 14K Centroplex Building 123 Main Street White Plains, NY 10601 s
r-3 3, a I' B&W Owners Group Project No. 693 cc: Randy Hutchinson, Chairman B&WOG Executive Committee Vice President Operations Arkansas Nuclear One Entergy Operations, Inc 1448 S.R. 333 Russellville, Arkansas 72801-0967 1 l Mr. W. W. Foster, Chairman. B&WOG Steering Committee { Director of Safety Assurance Duke Power Company
.Oconee Nuclear Station PO Box 1439
- Seneca, SC ' 29679 s
Mr. Michael Schoppman. Licensing Manager Framatome Technologies, Inc. 1700 Rockville Pike, Suite 525 I Rockville, MD 20852-1631 l Mr. J. J. Kelly, Manager B&W Owners Group Services ' Framatome Technologies, Inc. P.O.' Box 10935
- Lynchburg, VA 24506-0935 Mr. F. McPhatter, Manager Framatome Cogema Fuels 3315 Old Forest Road P.O. Box 10935 Lynchburg, VA 24506-0935 l
l~ I r
b'*- CE OWNERS GROUP Project No. 692 cc: Mr. Gordon C. Bischoff - CEOG Project Manager ABB Combustion Engineering M.S. 9615-1932 2000 Day Hill Road Windsor, CT 06095 Mr Ralph Phelps, Chairman CE Owners Group Omaha Public Power District P.O. Box 399 Ft. Calhoun, NE 68023-0399 Mr. lan C. Rickard, Director ' 4 Nuclear Licensing ABB-Combustion Engineering, Inc. Post Office Box 500 ' 2000 Day Hill Road Windsor, CT 06095 Mr. Charles B. Brinkman, Manager Washington Operations ABB-Combustion Engineering, Inc. j
.12300 Twinbrook Parkway, Suite 330 4 Rockville, MD 20852- >
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Westinghouse Owners Group Project No. 694 l cc: l Mrl Nicholas Liparulo, Manager
/ Regulatory and Engineering Networks
/ - Westinghouse Electric Corporation
. Mail Stop ECE 4-15 P.O. Box 355 Pittsburgh, PA 15230-0355 Mr. Andrew Drake, Project Manager -
Westinghouse Owners Group Westinghouse Electric Corporation Mail Stop ECE 516 P.O. Box 355 Pittsburgh, PA 15230-0355 Jack Bastin, Director Westinghouse Electric Corporation 11921 Rockville Pike, Suite 107 Rockville, MD 20852 Mr. John Galernbush, Acting Manager Regulatory and Licensing Engineering Westinghouse Electric Corporatior, PO Box 355 Pittsburgh, PA 15230-0355 l l 1 l l l l w
7 . Nuclear Energy' Institute Project No. 689 cc: Mr. Ralph Beedle Ms. Lynnette Hendricks, Director Senior Vice President Plant Support and Chief Nuclear Officer
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Nuclear Energy Institute Nuclear Energy Institute Suite 400 Suite 400 1776 i Street, NW 1776 i Street, NW Washington, DC 20006-3708 Washington, DC 20006-3708 Mr. Alex Marion, Director Mr. Charles B. Brinkman, Director Programs Washington Operations Nuclear Energy Institute ABB-Combustion Engineering, Inc. Suite 400 12300 Twinbrook Parkway, Suite 330 1776 l Street, NW Rockville, Maryland 20852 Washington, DC 20006-3708 Mr. David Modeen, Director , Engineering Nuclear Energy Institute ; Suite 400 ' 1776 I Street, NW I Washington, DC 20006-3708 Mr. Anthony Pietrangelo, Director Licensing Nuclear Energy Institute Suite 400 1776 i Street, NW Washington, DC 20006-3708 Mr. Nicholas J. Liparulo, Manager Nuclear Safety and Regulatory Activities Nuclear and Advanced Technology Division , Westinghouse Electric Corporation P.O. Box 355 Pittsburgh, Pennsylvania 15230 Mr. Jim Davis, Director Operations Nuclear Energy Institute Suite 400 1776 i Street, NW Washington, DC 20006-3708 J
4 o o Distribution: Mtg. Summary w/ NEl Re AOV lssues Dated July 8,1999 Hard Copy / Docket File PUBLIC PGEB R/F OGC ACRS PWen JColaccino H Ornstein (RES) J Donohew EMail SCollins/RZimmerman BSheron WKa..e JStrosnider/RWessman ; Elmbro DTerao DMatthews/SNewberry : CCarpenter { FAkstulewicz l I GTracy, EDO l
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