ML20094P415
| ML20094P415 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 11/09/1995 |
| From: | Elfstrom R, Higgins P, Hodge S NORTHEAST NUCLEAR ENERGY CO. |
| To: | |
| Shared Package | |
| ML20094P417 | List: |
| References | |
| NUDOCS 9511290137 | |
| Download: ML20094P415 (54) | |
Text
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l Generic Letter 89-10 Design-Basis Closure i
Northeast NuclearEnergy Company Millstone Unit 2 November 9,1995 Prepared:
S. T. Hodge
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MOV Tearn Su i r Reviewed:
AN R. C. Elfstrfdi MOV Team Consultant, Libeny hO o O Reviewed:
P.M HiggiE (
illstone Unit 2 MOV Project Engineer Approved:
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R. T. Harris MOV Team h ager Approved:
(A/
{j.. Riley /
Millstone Unit 2 Engineering Technical Suppon Manager 9511290137 951122
.PDR ADOCK 0 3j6
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Millstone Unit 2 MOV Program Nov:mber 9,1995 2
Table of Contents i
TABLE OF CONTENTS I
TABin lv 4
EXECUTIVE SUMMARV 5
- 1. PURPOSE 7
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- 2. INTRODUCTION 7
- 3. PROACTIVE FEATURES OF THE MOV PROGRAM S
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- 4. PROGRAM SCOPE 8
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- 6. SHERON MEMO CROSS REFERENCE 16 e
- 7. VALVE MISPOSITIONING 16
- 8. MOV PROGRAM SCOPE CRITERIA 16 l
- 9. DESIGN BASIS REVIEWS 17 i
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Millstone Unit 2 MOV Program November 9,1995 o
- 10. MOV SIZING AND SWITCH SETTINGS 20 10.1 VALVE WEAK LINK ANALYSIS 20 10.1.1 LOAD CASES AND COMBINATIONS 21 g
10.2 VALVE OPERATOR LIMITS 22 10.3 ELECTRICAL 22
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10.3.1 MOTOR PERFORMANCE FACTORS 23 10.3.2 EFFECTS OF DESIGN BASIS DEGRADED VOLTAGE ON MOV PERFORMANCE 23 10.4 DESIGN THRUST 24 10.5 VALVE FACTOR 24 10.6 STEM FACTOR / STEM FRICTION COEFFICIENT 27 10.7 MARGIN 2?
10.8 STEM LUBRICATION AND SPRGGPACK RELAXATION 30 10.9 SELECTION OF MOV SW!TCH SETTINGS 30 10.10 TORQUE SWITCH EY' ASS METHODOLOGY 32
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- 11. DESIGN-BASIS CAPABIIJTY 33 11.1 IN-SITU DESIGN BASIS VERIFICATION TESTING 33
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11.2 EXTRAPOLATION OF PARTIAL D/P THRUST MEASUREMENTS 33 11.3 LOAD SENSITIVE BEHAVIOR 33 11.4 POST-MAINTENANCE TESTING 35 j
- 12. DIAGNOSTIC TEST EOUIPMENT ACCURACY 36 12.1 GL 89-10 SUPPLEMENT 5 36 i
12.2 DIAGNOSTIC TEST EQUIPMENT REQUIREMENTS 37 i
12.2.1 DETERMINING ACCURACIES 38 12.2.2 APPLYING ACCURACIES 38 12.2.3 LIMIT SWITCH REPEATABILITY 39 i
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- 13. GROUPING 40 l
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- 14. PERIODIC VERIFICATION 41 14.1 PHILOSOPHY 41 14.2 DETERMINATION AND MAINTENANCE OF CORRECT SWITCH SETTINGS 41 14.3 POSITION ON PERIODIC TESTING (POST CLOSURE) 41
- 15. TREND AND ANALYZE MOV FAII.URES 42 15.1 TRACKING AND TRENDING REQUIREMENTS 42 15.2 DIAGNOSTIC PARAMETER TRENDING 43 15.3 MOV FAILURE TRENDING USING NPRDS 43 il
Millstone Unit 2 MOV Program November 9,1995
- 16. PRFRSURE LOCKING AND THERMAL BINDING 44 16.1 NRC POSITIDN 44 16.2 PLTB EVALUATION 44 16.2.1 EVALUATION CRITERIA 45 16.2.2 EVALUATION METHOD 45 16.3 EVALUATION RESULTS 46
- 17. INDUSTRY INFORMATION 48
- 18. PROGRAM SCHEDULE 48
- 19. OUAI ITY ASSURANCE 49
- 20. AUDITS / INSPECTIONS 49
- 21. TRAINING 50
- 22. MP2 CYCLE 13 TEST SCOPE (PRFLIMINARY) 50
- 23. STATUS OF GL 89-10 INSPECTION FINDINGS 51 REFERENCES 52 lii
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' W Millstone Unit 2 MOV Program November 9,1995 Tables
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Table 1: Summary ofMOV1ppes 9
Table 2: MOV-SystemNameandFunction 10 Table 3: Probabilistic-Risk-Assessment (PRA) Priority 11 Table 4: SafetyStrokes 11 Table 3: Information on Valve, Actuator andMotor 12 Table 6: ControlSwitch Thrust 13 Table 7: TestData 14 Table 8: Basis For Closure 13 Table 9: Sheron Memo items - Cross Reference 16 Table 10: Calculation Listing 19 Table i1: As Lep Load Combination (Design Basis) 21 Table 12: Non-As-Lep Load Combinations 21 Table 13:StallLoadCombination 22 Table 14: Gate Valve VfCriteria 23 Table 13: Valve Factors and Measured Rate ofLoading 26 T.dile 16: Gate Valve Measured Stem to Stem-Nut Coeficient ofFriction (p) 28 Table 17: Margin 29 Table 18: Post-Maintenance Retest Requirements 36 Table 19: Test Equipment Accuracy Matrix 38 Table 20: Pressure Locking (PL) / Thermal Binding (TB) Summary 47 Table 21: Cycle 13 Monitoring / Test Scope 30 l
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Millstone Unit 2 MOV Program NovGmber 9,1995 l
l CLOSURE OF MP2 GL 89-10 PROGRAM Executive Summary This document describes the bases for Millstone Unit 2's closure of the design-basis verification phase of NRC Generic Letter 89-10," Safety-Related Motor-Operated Valve Testing and Surveillance." This report was prepared to serve as a living document which controls the GL 89-10 design requirements, and provides in one place sufficient information to verify GL 89-10 closure.
This has been accomplished by defining the Northeast Utilities Motor-Operated Valve Program as implemented at the Millstone Unit 2 Plant. Included in the report are actions taken to date, as well as descriptions of the longer-term program being implemented for on-going testing and surveillance of safety-related motor-operated valves (MOV's). This program verified and ensures MOV operability under design-basis differential pressure and flow conditions.
In November of 1985, the NRC issued Bulletin 85-03 recommending licensees develop and implement a program to ensure the reliability of MOV's in several safety-related systems. In June of 1989, the NRC issued Generic Letter (GL) 89-10 recommending licensees develop a comprehensive l
program to ensure MOV's in safety-related systems will operate under design-bases conditions and mispositioned conditions.
Northeast Utilities (NU) committed to develop a detailed program for addressing GL 89-10 at Connecticut Yankee, Millstone Unit No.1, Millstone Unit No. 2, and Millstone Unit No. 3 nuclear power plants. All safety-related MOV's and position-changeable MOV's in safety-related piping systems are included in this program. 'lhis program includes demonstrating the operability of safety-related MOV's by analysis and in-situ flow tests at or near design basis conditions, where practicable. The objectives of our program are to:
Increase MOV operability assurance through a long-term preventive maintenance and trending program.
Identify problem valves early (i.e., experience no failures during plant operation).
1 Minimize extended outages due to MOV testing related activities.
The NU MOV Program Manual specifies criteria and requirements for NU's implementation of GL 89-10. The MOV Program Manual applies to the Connecticut Yankee, Millstone Unit No.1, Millstone Unit No. 2, and Millstone Unit No. 3 nuclear power plants. It is the controlling document for Northeast Utilities Service Company (NUSCO), Northeast Nuclear Energy Company (NNECO),
Connecticut Yankee Atomic Power Company (CYAPCO), and contractors performing MOV Program activities at Northeast Utilities. The MOV Program Manual consists of the following sections:
e Introduction Objectiver. ppose, scope and applicability.
Responsibilities Respon 4bilities of key individuals / groups.
Integration Interftces with other groups and individuals.
Technical Requirements Terinnical Requirements of the MOV Program.
Instructions Program Instructions (PIs) for implementation.
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Millstone Unit 2 MOV Program November 9,1995 Figures Organization and process flow charts.
- References Source / supporting documents, management commitments.
- Definitions Acronyms and terms.
- Attachments Attachments which ne significant.
Millstone Unit 2 completed the design-basis phase of GL 89-10 on August 4,1995, within the original NRC requested schedule, i.e., the third refueling outage after December 28,1989.
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9 Millstone Unit 2 MOV Program November 9,1995
- 1. Purpose The purpose of this document is to summarize, in one place, closure of the design-basis phase of GL 89-10, and future changes which impact design-basis considerations. It also provides the bases for MOV settings and configuration. Finally, this report serves as a living document which will be periodically revised as ont element in configuration control. This closure report will be maintained as a controlled document within the MOV Program Manual r.nd updated as necessary.
It is currently envisioned that this document will be reviewed after each refueling outage if changes are made which impact MOV functionality or GL 89-10 MOV design compliance. This document will not control control-switch setpoints, future test data, or calculation numbers. These and other parameters are controlled by NU procedures. Tables 6,7,10, and 17 will not be maintained as living. An example of an item which will result in a revision is a design change requiring revalidating design-basis capability.
- 2. Introduction On June 28,1989, the NRC staffissued Generic Letter 89-10," Safety-Related Motor-Operated Valve Testing and Surveillance,"' which provided recommendations to the licensees for the development of adequate programs to ensure operability of safety-related MOV's during design-basis conditions. The generic letter recommended that each licensee with an operating license complete all design-basis reviews, analyses, verifications, tests and inspections that have been instituted within five years or three refueling outages, whichever is later, of the date of the generic letter (June 28,1989).
The staff held public workshops to discuss the generic letter and to answer questions regarding its implementation. On June 13,1990, the staffissued Supplement 1 to Generic Letter 89-10 to provide the results of the public workshops. In Supplement 2' to Generic Letter 89-10, issued on August 3,1990, the staff stated that inspections of programs developed in response to the generic letter would not begin until January 1,1991.
In response to concerns raised by the results of NRC-sponsored MOV tests, the staffissued Supplement 3" to Generic Letter 89-10 on October 25,1990. This supplement requested that Boiling Water Reactor licensees evaluate the capability of MOV's used for containment isolation in the steam lines to the high pressure coolant injection system and reactor core isolation cooling system; in the supply line to the reactor water cleanup system; and in the lines to the isolation condenser, as j
applicable.
5 On February 12,1992, the staffissued Supplement 4 to Generic Letter 89-10 excluding considerations for inadvertent operation of MOV's from the scope of Generic Letter 89-10 for 6
Boiling Water Reactors. On June 28,1993, the staffissued Supplement 5 to Generic Letter 89-10 which requested that licensees review their MOV programs and to identify measures taken or planned to account for uncertainties in properly setting valve operating thrust due to increased inaccuracy of MOV diagnostic equipment.
7 Supplement 6 to Generic Letter 89-10, issued March 8,1994, further clarified NRC positions on the schedule for completing MOV testing to verify design-basis capability and grouping of MOV's to establish valve setup conditions. This supplement also provided staff responses to other general public questions.
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l Millstone Unit 2 MOV Program November 9,1995
- 3. Proactive Features of the MOV Program Used a 0.6 valve factor for non-testable gate valves based upon review of Electric Power Research Institute (EPRI) Performance Prediction Methodology (PPM) results.
Use of the Kalsi Engineering Inc., KEI Gate Program for non-testable valves to validate our 0.6 valve factor assumption. In cases where the KEI Gate yields a value
> than 0.6, the " bounding" KEI Gate value is used to define the thrust window. KEI Gate was performed for NNECO due to delayed issuance of the EPRI PPM.
Developed a comprehensive structural analysis procedure and replaced diverse vendor seismic weak link calculations with consistent calculations for all GL 89-10 valves.
Backfit ASME Code, stress-based requirements to Haddam Neck, Millstone Unit 1, and Millstone Unit 2.
Determined acceptable pressure boundary integrity at actuator stall in cases where actuators have been modified and stall thrust increased significantly.
Employ consistently determined results from three other nuclear units, thereby adding further validation to MOV program assumptions.
Performed laboratory design-basis dynamic tests for selected replacement valves.
This work was performed for Northeast Utilities by the broadly recognized Alden Research Laboratory in Massachusetts.
Provided special treatment of Westinghouse gate valves in high differential pressure applications. Not yet published EPRI research was used to define a more conservative set of acceptance criteria for two Westinghouse MOV's in high pressure applications.
Developed a more accurate model to evaluate stroke time for DC-powered actuators.
A specific linkage was drawn between higher assumed valve factors and stroke time.
Compiled digital photographs of MOV's for easy storage, retrieval and review.
- 4. Program Scope The objective of the Millstone Unit 2 MOV Program is to ensure MOV operability under design-basis differential pressure and flow conditions. This entails several program elements to:
(1) determine the design-basis conditions, (2) determine the physical limitations of the valve and actuator, (3) perform the requisite testing and evaluate the data to determine the appropriate limit and / or torque switch settings, and (4) ensure that operability is maintained throughout the life of the plant through on-going maintenance activities and design control measures.
Setup and testing of the valves is accomplished using the Liberty Technologies Valve Operation Test and Evaluation System (VOTES) or other equivalent (i.e., Motor Power Monitor - MPM).
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' Millstone Unit 2 MOV Program Nove,nber 9,1995 i
Millstone Unit 2's administrative program is defined by Nuclear Group Procedure (NGP) 2.32,
" Engineering Programs" with specific detailed procedural requirements contained in the Motor.
Operated Valve Program Manual. Other ancillary procedures govern more specific aspects of the program such as use and calibration of test equipment and adjustment of switches. Finally, procedural interfaces exist with other programs governing routine maintenance, plant design changes and modifications, corrective action programs, and identification of non-conforming muerials.
1 The Millstone Unit 2 MOV Program is based upon satisfying two key technical requirements. These are (1) the physical limitations of the valve and actuator based on allowable limits of subcomponents (e.g., torque limits on the actuator, thrust limits, valve component structural limits, etc.) and (2) the i
l required differential pressure and flow environment in which the valve must function. Other effects such as operation at reduced voltage and elevated temperatures, use of proper stem factors, pressure locking and thermal binding have also been considered.
l There are fifty two (52) motor-operated valves included in the Millstone Unit 2 MOV Program scope. A summary of valve types, disk type and valve manufacturer is defined in Table 1.
Table 1: Summary ofMOV1) pes Valve Type l Disk Type l
Manufacturer Gate Flex Wedge (28)
(4) Crane (37)
(1) Powell (23) Velan Parallel Disk (8)
(8) Anchor Darling Solid Wed (1) 1 Velan Globe (1) Gimpel (15)
(14) Velan All Millstone Unit 2 MOV's within the program scope utilize Limitorque operators.
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- 5. Status of GL 89-10 Program MOV's As of August 1995, all initial design reviews, valve set-up and static tests of the 52 valves in the Millstone Unit 2 GL 89-10 MOV Program were completed by the end of refueling outage RFO 12, the third refueling outage after the release of GL 89-10. All 52 valves were statically tested and 17 i
valves were dynamically tested during RFO 11 (1992). During RFO 12 (1994),32 valves were statically tested and eight valves were dynamically tested. Of the eight dynamically tested, three 1
were retests of valves previously tested during RFO 11. There were 15 valves which were not dynamically tested due to high calculated margin / capability.
4 Information about each MOV in the Millstone Unit 2 MOV Program is contained in numerous tables within this report. Table 2 contains the valve tag number and system label name along with the j
l functional description of each valve.
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E Millstone Unit 2 MOV Program November 9,1995 I
- I Table 2: MOV-SystemNameandFunction
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Valve System Name Function Number 2-CH-429 Chemical and Volume Control Charging Header Containment isolation Valve 2-CH-501 Chemical and Volume Control Volume Control Tank to Charging System Outlet Valve l
2-CH-504 Chemical and Volume Control i RWST to Charging Pump Suction Valve 2-CH-508 Chemical and Volume Cunuw.
3 *B" Boric Acid Storage Tank Outlet Gravity Feed Valve 2-CH-509 Chemical and Volume Control
%" Bonc Aciu Storage Tank Outlet Gravity Feed Valve 2-CH-514 Chemical and Volume Control Boric Acid Pumps Combined Discharge isolation Valve 2-CS-04.1 A Containment Spray "A" Containment Spray Header isolation Valve 2-CS-04.18 Containment Spray "B" Containment Spray Header isolation Valve 2-CS-13.1 A Containment Spray RWST Outlet Header "A" Isolation Valve 2-CS-13.1B Containment Spray RWST Outlet Header "B" Isolation Valve 2-CS-16.1 A Containment Spray Containment Sump Outlet Header "A" isolation Valve 2-CS-16.1 B Containment Spray Containment Sump Outlet Header "B" Isolation Valve i
2-FW-38A Feedwater "A" Steam Generator Feedwater Pump Discharge Valve 2-FW-38B Feedwater "B" Steam Generator Feedwater Pump Discharge Valve 2-FW-42A Feedwater
- 1 Steam Generator Feed Regulating Valve Blocking Valve 2-FW-42B Feedwater
- 2 Steam Generator Feed Regulating Valve Blocking Valve 2-FW-44 Feedwater Auxiliary Feedwater Pump Discharge Header Crosste Valve i
2-MS-65A Steam Generator
- 1 Steam Generator MSIV Bypass Vatve 2-MS-65B Steam Generator
- 2 Steam Generator MSIV Bypass Valve I
2-MS-201 Steam Generator
- 1 Steam Generator te Terry Turbine Steam Supply Valve 3
2-MS-202 Steam Generator
- 2 Steam Generator to Terry Turbine Steam Supply Valve 2-RB-30.1 A Reactor Plant Closed Cooling Water "A" RBCCW Header Containment Supply isolation Valve j
2-R B-30.1 B Reactor Plant Closed Cooling Water "B' RBCCW Header Containment Supply isolation Valve 2-RB-37.2A Reactor Plant Closed Cooling Water "A" RBCCW Header Containment Return isolation Valve 2-RB-37.20 Reactor Plant Closnd Cooling Water "B" RBCCW Header Containment Return isolation Valve 4
2-RC-403 Pressunzer Pressunzer Power-Operated Relief Valve isolation Valve i
2-RC-405 Pressunzer Pressunzer Power-Operated Relief Valve isolation Valve 2-SI-411 High Pressure Safety injection "A / B" HPSI Pumps Suction Crosste Valve l
2-SI-412 High Pressure Safety injection "B / C" HPSI Pumps Suction Crosstie Valve 2-SI-614 Low Pressure Safety injection
- 1 Safety injection Tank Outlet Valve 2-SI-615 Low Pressure Safety injection LPSI Header to Loop 1 A Injection Valve 2-SI-616 High Pressure Safety injection "B" HPSI Header to Loop 1A injection Valve 2-SI-617 High Pressure Safety injection "A" HPSI Header to Loop 1 A Injection Valve 2-SI-624 Low Pressure Safety injection
- 2 Safety injection Tank Outlet Valve 2-St-625 Low Pressure Safety injection LPSI Header to Loop 1B injection Valve 2-SI-626 High Pressure Safety injection "B" HPSI Header to Loop 10 injection Valve 2-SI-627 High Pressure Safety injection
2-SI-634 Low Pressure Safety injectir,n
- 3 Safety injection Tank Outlet Valve 2-SI-635 Low Pressure Safety injecgr[
LPSI Header to Loop 2A injection Valve 2-SI-636 High Pressure Safety injeg "B" HPSI Header to Loop 2A Injection Valve 2-SI-637 High Pressure Safety injefty "A" HPSI Header to Loop 2A Injection Valve 2-St-644 Low Pressure Safety injedn
- 4 Safety injection Tank Outlet Valve 2-SI-645 Low Pressure Safety injeMior.
LPSI Header to Loop 2B Injection Valve 2-SI-646 High Pressure Safety injk on "B" HPSI Header to Loop 2B Injection Valve 2-SI-647 High Pressure Safety injection "A" HPSI Header to Loop 2B Injection Valve 2-SI-651 Shutdown Cooling Shutdown Cooling Suction Header Containment isolation Valve 2-SI-652 Shutdown Cooling Shutdown Cooling Suction Header Containment isolation Valve 2-SI-653 High Pressure Safety injection "B" HPSI Pump Discharge to "B" HPSI Header Crosstie Valve 2-SI-654 High Pressure Safety injection
- B" HPSI Header Stop Valve 2-SI-655 H6gh Pressure Safety injection "B" HPSI Pump Discharge to "A" HPSI Header Crosstie Vatve 2-SI-656 High Pressure Safety injection "A" HPSI Header Stop Valve 2-SV-4188 Steam Generator Terry Turbine Tnp Throttle Valve 10 l
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l Millstone Unit 2 MOV Program November 9,1995 Provided in Table 3 is the quantitative-based Probabilistic Risk Assessment (PRA) priority for each valve. All MOV's were reclassified" in 1994 using component risk achievement worth (RAW) importance parameters. The new prioritization scheme is based upon superior insights and state of i
the art knowledge in comparison to the previous MOV prioritization schemes. The 52 valves in the Millstone Unit 2 MOV Program include 5 valves with a very high PRA rank,16 valves with high, and 24 valves with a medium PRA rank, and 7 valves with a low PRA rank.
l Tabis 3: Probabilistic-Risk-Assessment (PRA) Priority l
Valve Number PRA Rank Valve Number PRA Rank Valve Numtwr PRA Rank
)
2-CH-429 Medium 2-MS45A Medium 2-Sl425 Hgh
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2-MS45B Medium 2-Sl426 N Hgh 2-CH-501 Medium 2-CH-504 Low 2-MS-201 Medium 2-Sl427 i
High 2-CH-508 Medium 2-MS-202 Medium 2-Sl434 6ow i
2-CH-509 Medium 2-RB-30.1 A Medium 2-S14 35 Egh j
2-CH-514 Medium 2-RB-30.1 B Medium 2-St-636 High 2-CS-04.1 A High 2-RB-37.2A Medium 2-Sl437 High 2-CS-04.1 B High 2-RB-37.2B Medium 2-Sl444 Low 2-CS-13.1 A Medium 2-RC-403 Hgh 2-Sl445 Hgh 2-CS-13.1B Medium 2-RC-405 Hgh 2-Sl446 High 2-CS-16.1 A Very High 2-SI-411 Medium 2-Sl447 High 2-CS-16.1 B Very Hgn 2-SI-412 Medium 2-SI-651 Very High 1
2-FW-38A Medium 2-Sl414 Low 2-S14 52 Very Hgh 2-FW-38B Medium 2-Sl415 Hgh 2-SI-653 Medium 2-FW-42A Medium 2-SI-616 High 2-Sl454 Low 2-FW-42B Medium 2-SI-617 High 2-SI-655 Medium 2-FW-44 Medium 2-SI-624 Low 2-Sl456 Low 2-SV-4188 Very High 1
Table 4 lists the credited safety function strokes for each valve. The 52 valves in the Millstone Unit 2 MOV Program include 23 valves with an open safety function,16 valves with a close safety function, and 13 valves with both an open and close safety function.
l Table 4: SafetyStrokes Valve Number Safety Stroke Valve Number Safety Stroke Valve Number Safety Stroke 2-CH-429 open / close 2-MS-65A open / close 2-SI-625 open 2-CH-501 close 2-MS-65B open / close 2-SI-626 open 2-CH-504 open 2-MS-201 open / close 2-SI-627 open 2-CH-508 open 2-MS-202 open / close 2-Sl434 close 2-CH-509 open 2-R B-30.1 A close 2-SI-635 open 2-CH-514 open 2-RB-30.1 B close 2-Sl436 open 2-CS-04.1 A open / close 2-RB-37.2A close 2-SI-637 open 2-CS-04.1 B open / close 2-RB-37.2B close 2-St-644 close 2-CS-13.1 A close 2-RC-403 open / close 2-Sl445 open 2-CS-13.18 close 2-RC-405 open I close 2-Sl446 open 2-CS-16.1 A open 2-SI-411 open / ciose 2-S1447 open 2-CS-1rs.1 B open 2-St-412 open / close 2-SI-651 open 2-FW ',8A close 2-SI-614 close 2-SI-652 open 2-FW-38B close 2-SI-615 open 2-SI-653 open / close 2-FW-42A close 2-SI-616 open 2-S!-654 open 2-FW-42B close 2-SI-617 open 2-SI-655 open / close 2-FW-44 close 2-SI-624 close 2-SI-656 open 2-SV-4188 open i
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Millstone Unit 2 MOV Proy e Novsmber 9,1995 l
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- Table 5 lists the pertinent valve, actuator and motor information.
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Table 3: h{ormation on Yahe, Actuator andMotor
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Valve valve Actuator Motor l
Number Company Type Wedge Type Slee Company Type Company Size i
(in)
(ft-lb) i 2-CH-429 Volan Gate Solid 2
Limitorque SMB-000 Reliance 5
2-CH-501 Veien Gate Flex 4
Limnorgue SMB-00 Reliance 5
)
i 2-CH-504 Velan Gate Flex 3
Umitorque SMB-00 Relence 5
2-CH-508 Velan Gate Flex 3
umitorque SMB-00 Relence 5
l 2-CH-509 Volan Gate Flex 3
Limitorque SMB-00 Relence 5
i 2-CH-514 Velan Gate Flex.
3 Limitorque SMB-00 Reliance 5
g 2-CS-04.1 A Anchor-Darling Gate Parallel Dec 8
Umitorque SMB-0 Reliance 15 1
2-CS-04.1B Anchor-Darhng Gate Parallel Dec 8
Lirnnorque SMB-0 Relence 15 i
2-CS-13.1 A Anchor-Darhng Gate Parallel Dec 18 Umnorgue SMB-0 Poortesa 15 ll 2-CS-13.18 Anchor-Darling Gate Parallel Dec 18 Limitorque SMB-0 Peertees 15 2-CS-16.1 A Anchor-Darhng Gate Parallel Dec 24 Umitorque SMB-1 Peerless 25 l
2-CS-16.1B Anchor-Darhng Gate Parallel Disc 24 umitorque SMB-1 Peerless 25
(
l 2-FW-38A Crane Gate Flex 18 Umitorque SMB-4T Electric Apparatus 250 j
2-FW-38B Crane Gate Flex 18 umitorque SMB-4T Electric Apparatus 250 2-FW-42A Crane Gate Flex 18 Limitorque SMB-4T Electric Apparatus 250 l
2-FW-42B Crane Gate Flex 18 umitorque SMB-4T Electric Apparatus 250 2-FW-44 Powell Gate Flex 6
Limitorque SB-1 Relence 25 2-MS45A Velan Globe N/A 3
Limitorque SMB-000 Relence 5
1 2-MS45B Velan Globe N/A 3
umatorque SMB-000 Reliance 5
)
2-MS-201 Velan Gate Flex 4
Limitorque SMB-000 Relence 5
l 2-MS-202 Velan Gate Flex 4
Umstorque SMB-000 Relence 5
)
2-RB-30.1 A Velan Gate Flex 8
umitorque SMB-000 Rohance 5
l 1
2-RB-30.1B Velan Gate Flex 6
umnorque SMB-000 Reliance 5
l 2-RB-37.2A Velan Gate Flex 8
Umstorque SMB-000 Relence 5
2-RB-37.2B Velan Gate Flex 6
Limitorque SMB-000 Relence 5
L 2-RC-403 Velan Gate Flex 2.5 Limatorque SMB-00 Rotence 10 1
2-RC-405 Velan Gate Flex 2.5 Limitorque SMB-00 Rohana 10 i
2-St-411 Anchor Darling Gate Parallel Disc 8
Limitorque SMB-00 Peerless 10 2-St-412 Anchor-Darhng Gate Parallel Dec 8
Limitorque SMB-00 Relence 10 2-Sl414 Velan Gate Flex 12 Limitorque SMB-2 Relence 60
}
2-Sl415 Velan Globe N/A 6
Umitorque SMB-1 Relence 25 i
2-S1416 Velan Globe N/A 2
Limitorque SMB-00 Reliance 15 2-S1417 Velan Globe N/A 2
Limitorque SMB-00 Relence 15
}-
2-Sl424 Velan Gate Flex 12 Limitorque SMB-2 Relence 60 2-S1425 Velan Globe N/A 6
Limitorque SMB-1 Rehance 25 I
5:
2-Sl426 Velen Globe N/A 2
Limitorque SMB-00 Relence 15 2-S1427 Velan Globe N/A 2
Limitorque SMB-00 Relence 15 3
2-Sl434 Velan Gate Flex 12 Limitorque SMB-2 Rahance 60 2-Sl435 Velan Globe N/A 6
Limitorque SMB-1 Reliance 25 j
2-Sl436 Velan Globe N/A 2
Limitorque SMB-00 Relence 15 4,
2-St 637 Velan Globe N/A 2
Limitorque SMB-00 Reliance 15 i
2-Sl444 Velan Gate Flex 12 Limitorque SMB-2 Relence 60 2-Sl445 Velan Globe N/A 6
Limitorque SMB-1 Reliance 25 l
2-Sl446 Velen Globe N/A 2
Limitorque SMB-00 Relence 15
{
2-Sl447 Velan Globe N/A 2
Limnorque SMB-00 Reliance 15 2-S1451 Velan Gate Flex 12 Umitorque SMB-2 Rohance 60 4
l 2-S1452 Velan Gate Flex 12 Umstorque SMB-2 Rohance 60 2
241453 Velan Gate Flex 4
Limitorque SMB-00 Rehance 10 3
2-Sl454 Velan Gate Flex 6
Umnorque SMB-00 Relence 25 2-S1455 Velan Gate Flex 4
Limitorque SMB-00 Relence 10 j
2-Sl456 Velen Gate Flex 6
umitorque SMB-0 Relena 40 l
2-SV-4188 Gimpel Globe N/A 4
Umitorque SMB-000 Peerless (DC) 5 i
i 12 4
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l Millstone Unit 2 MOV Program November 9 1995 0
To demonstrate design-basis closure, control switch thrust versus calculated minimum and maximum thrust is tabulated in Table 6. Future changes will be controlled by existing NU procedures.
Table 6: ComrolSwitch Thrust Valve TSB or Minimum Calculated As-Left Numbe L
R Maximum CST 2-CH-429 1974 4303 3051 2-CH-501 2744 3284 2854 2-CH-504 1632 3830 2572 2-CH-508 759 4019 2465 2-CH-509 761 4019 2353 2-CH-514 1598 4305 7 368 2-CS-04.1 A 3284 10018 8628
~
2-CS-04.1 B 1608 8862 8766 2-CS-13.1 A 5912 9864 7098 2-CS-13.1 B 7071 9628 7576 2-CS-16.1 A 19011 22399 20372 2-CS-16.1 B 17694 25485 20802 2-FW-38A l
LS l
126031 159574 4570 2-FW-388 l
LS l
117520 164384 2756 2-FW-42A l
LS l
118592 164384 3170 2-FW-428 l
LS l
120571 164384 6053 2-FW-44 l TSB l 20844 22940 21231 m._
5172 8237 6615 2-MS-65A 2-MS-65B E!@j]
5963 8237 7035 2-MS-201 MW2tdI 4053 9340 8176 2-MS-202 EMj$$]
7108 9451 7971 2-R B-30.1 A gggj 4869 6882 6200 2-RB-30.18 msen a 2838 7073 5619 R]j; 3509 7073 6214 2-RB-37.2A 3056 6882 6270 2-RB-37.2B 2-RC-403
@l 9959 13923 10918 2-RC-405 K
10969 13923 12763
+
2-SI-411 2335 10526 6966 2-SI-412 W
_El 2653 9311 8882 2-SI-614 2:
20253 36049 27736 2-SI-615 m
2878 37190 15511 2-SI-616 4109 13307 8383 2-SI-617 3
2555 15433 10315 24308 36049 33089 r_"b"]
i 2-SI-624 1934 37160 17014 2-St-625 2 Sl-626 M
3670 10638 8713 2-Sl427 3
1088 9667 8452 20330 36964 30052 2-SI-634 R$g#,jpl 4590 40527 22503 2-SI-635 gg 3580 17544 11784 i
2-SI-636 2-SI-637 myggigld 967 16281 11273 2-SI-644 mediPJ 19005 36049 24546 2-SI-645
$I@
6392 40527 23947 2-SI-646 m@
3747 17544 7890 l
2-SI-647 6965 17544 10128 l
2-SI-651 15249 36964 32674 2-SI-652 13916 36964 23388 2-SI-653 1699 11395 10327 2-SI-654 2762 15834 7418 2-SI-655 965 14539 10443 2-SI-656 2672 30415 22661 TSB - Torque Switch Bypass rtch 13
l l.
l Millstone Unit 2 MOV Program November 9,1995 t
The type of test, either static or dynamic, and the date of the latest test is included in Table 7 to demonstrate design-basis closure. Future changes will be controlled by existing NU procedures.
Table 7: Test Data l
Valve As-Left Dynamic Open Close Open Close
% DB D/P:
% DB D/P:
Number Static Test Test Test DB DB Open Test Close Test Test Date Date Pressure Pressure D/P DfP g* p< ytsu$
^
83 83
-,,g;4;pjy+Cp WPM 2735 0
@pMkP ~ ~M N
2-CH-429 1/20/95 Non-Testable Ab P 4
fpygfl 2-CH-501 10/19/94 High Margin 6';g 2-CH-504 9/26/92 High Margin i$
121 121
- v Q 'p g; th,;
%,y@E$g p' 2-CH-508 6/25/95 High Margin L
69 15 n
2-CH-509 6/24/95 High Margin 69 15 t
k f /g,,
b;#:
2-CH-514 9/24/92 High Margin j
138 123 3
2-CS-04.1 A 10/7/94 Non-Testable.#L jngN 269 20
@ieMT'sfh 7 ~ d O A Q / i'{',, N, 2-CS-04.18 6/14/95 Non-Testable 3DW 4
269 20 yMo % y 19 4
J;W; *n r,s ' a ;, m, ". ;
v s
2-CS-13.1 A 11/5/92 High Margin p
.g n c q 7, C' 3@4
- C I'^ ;.
- ^
2-CS-13.18 5/19/95 High Margin 19 4
[ ), o' 'w? ' JW^g'g' J '
ww
~e g@g,p_ % [ hi[
A3GO 42 42 2-CS-16.1 A 5/16/95 Non-Testable
- $jfl P',O XY ih^
42 42 2-CS-16.1 B 2/1/95 Non-Testable W@ggQQh s f, f' p y I i
?.'. !
N/A 834 2-FW-38A 10/6/93 Non-Testable 3 d 7
- C.' O f "Rje:$IC5R N/A 834 Q)?' Q ' [ [ ";f^~
2-FW-38B 10/6/93 Non-Testable
- h g.gQ{[E[Mia l'
N/A 834 2-FW-42A 3/4/95 Non-Testable ww i ridp N/A 834
? - A e < > ', a t,
i 2-FW 428 10/7/93 Non-Testable 2-FW-44 3/17/95 3/17/95 1188 l 821 1229 1229 96 63% l 67.00 %
j F9pm wng a 885 1000 m W 7,',J,a N" 2-MS-65A 7/7/95 Non-Testable 2-MS-65B 7/13/95 Non-Testable hbY$ 5Ob NO 885 1000 t $ ' fi % I A M; 2-MS-201 12/29/94 9/30/94 735 735 1000 1000 73.50 %
73.50 %
2-MS-202 1/3/95 9/30/94 650 650 1000 1000 65.00 %
65.00 %
2-RB-30.1 A 11/4/92 12/17/92 80.3 80.3 96 96 83 65%
83.65 %
2-RB-30.1 B 1/11/95 High Margin FSKn V@
+sN 96 96 F M Ri&Y P M s V 2-RB-37.2A 12/4/92 12/17/92 78.4 l
78.4 96 96 81.70 % l 81.70 %
1 96 96
'^4 2-RB-37.2B 1/10/95 High Margin X 5'4 <,
+
d.
k@3png";: ). >
5 +am 4
2485 2250
,' l Nr
' ['i 2-RC-403 3/30/95 Non-Testable
@$d$NM 2485 2250
~/
i-2-RC-405 4/6/95 Non-Testable l' [;/,9 j l '
m 2-St 411 11/16/92 High Margin d
f [ d(..,,
40 55 2-SI-412 5/27/95 High Margin gjg'j $$
40 55
% 2
- f, : + ",'f 2-St-614 1/20/95 Non-Testable WW3fiCM + %
0 150 E."
2-SI 615 2/23/95 11/18/92 141 187 178 0
79.21 %
N/A 2-SI-616 11/17/92 11/17/92 1179 1254 1280 0
92.11 %
> 100 %
2-SI-617 10/18/94 10/18/94 1267 1266 1280 24 98 99%
> 100 %
2-SI-624 1/30/95 Non-Testable rivm mm
""WV 0
150 P m?M e
~
2-St-625 3/10/95 3/10/95 175 115 178 0
85.96 %
N/A 2-SI-626 11/17/92 11/17/92 1181 1259 1280 0
92.30 %
> 100 %
2-SI-627 10/18/94 10/18/94 1256 1259 1280 24 98.11'4
> 100 %
0 150 FWWWW 2-SI-634 10/29/92 Non-Testable p e!M~r' 2-SI-635 11/18/94 11/18/92 144 169 178 0
81.00 %
N/A 2-SI-636 10/14/94 11/17/92 1251 1252 1280 0
97.73 %
> 100 %
2-SI-637 10/18/94 10/18/94 1264 1240 1280 24 97.87 %
> 100 %
2-SI-644 10/7/92 Non-Testable EU =le;w 4
0 150 D I V E W O: % ^
1 2-SI-645 11/18/92 11/18/92 148 175 17 ",
0 83.24 %
N/A 2-SI-646 11/17/92 11/17/92 1185 1263 1190 0
92.60 %
> 100 %
2-S1-647 12/1/92 Grouped ymewe e:;m 1 2'10 24 m vem mum ' +
2-SI-651 12/31/94 1/5/93 227.08 12.08 277 277 81.97 %
4.36 %
2-SI-652 1/24/95 7/3/95 204.12 0.12 271 277 73.68 %
0.04 %
2-SI-653 10/6/94 High Margin m %;
m1 42 42 wMg;q% 6g MMQQ 2-St-654 11/17/92 High Margin
@ $ %. y 42 f
16 2-SI-655 10/30/92 High Margin
@ g;G N % ng[d M 42 42 C 9sMM% <,M,,
2-St-656 11/12/92 High Margin MN5IbT I YN 1 42 16 MSkN Y 2-SV-4188 1/6/95 1/7/93 833 0
1000 N/A 83.30% j N/A 14
Millstone Unit 2 MOV Program NovGmber 9,1995 l
e The basis used for closure of each MOV is depicted in Table 8.
Table 8: Basis For Closure
~
Valve Number Full or Group With KEl Gate Large Non-Partial D/P D/P Tested Calculated Testable Test Valves Ma in lobe Valve X
2-CH-501 X
2-CH-504 X
2-CH-508 X
i 2 CH-509 X
2-CH-514 X
2-CS-04.1A X
2-CS-04.1B X
2-CS-13.1 A X
2-CS-13.1B X
i 2-CS-16.1 A X
2-CS-16.1B X
2-FW-38A X
2-FW-38B X
2-FW-42A X
2-FW-42B X
2-FW-44 Full 2-MS-65A X
2-MS45B X
2-MS-201 Full 2-MS-202 Full 2-RB-30.1 A Full 2-RB-30.18 X
j 2-RB-37.2A Full 2-RB-37.2B X
2-RC-403 X
2-RC-405 X
2-SI-411 X
4 2-SI-412 X
2-Sl414 X
2-S1415 Full 2-Sl416 Full 2-Sl417 Full 2-Sl424 X
2-St-625 Full 2-Sl426 Full 1
2-Sl427 Full 2-St-634 X
2-Sl435 Full 2-Sl436 Full 4
2-SI-637 Full 2-Sl444 X
2-SI-645 Full 2-S1446 Full il._
2-Sl447 Note 1
'/
2-Sl451 Partial 2-SI-652 Partial 7
2-SI-653 X
2-St-654 X
t 2-Sl455 4
X 2-St-656 X
2-SV-41 B8 Full 1:ote1: 7 S1 647 i; grouped with 2-SI-617, -627, -637, - il 6, -626, - 636, and -646 15
l Millstone Unit 2 MOV Program November 9,1995
- 6. Sheron Memo Cross Reference Provided below is a quick cross reference of the section and page number for each of the items in the
_ Sheron memo which required justification.
Table 9: Sheron Memo items - Cross Reference Section Page Sheron Memo item 10.5 24 Valve factor (including area assumption) 10.6 26 Stem fnction coefficient 11.3 33 Lead sensitive behavior 10.8 30 Margins for stem lubrication degradation and springpack relaxst:en 10.3.1 22 Motor performance factors 11.2 33 Basis for extrapolation method of partial d/p thrust measurements 12.2.3 39 Torque switch repeatabihty 10.2 22 Use of Umstorque, Kalsi, or other sources for increasing thrust / torque allowable limits 12 36 Equipment error 11.4 35 Post-maintenance testing, especially valve packing adjustments 13 39 Grouping of MOVs 15 42 Trending of MOV problems
- 7. Valve Mispositioning Millstone Unit 2 has deferred consideration of valve mispositioning in our GL 89 10 program in accordance with guidance provided in NRR memo of July 12,1994 (the "Sheron memo").' The NRC staffis evaluating the request by the Westinghouse Owners' Group that the recommendation in GL 89-10 to consider valve mispositioning be removed. The NRC Staffis preparing a Supplement 7 to GL 89-10 on the need to consider valve mispositioning as part of GL 89-10 programs at Pressurized Water Reactor (PWR) plants.' If ongoing staff analyses provide adequatejustification, the supplement will eliminate the recommendation for PWR licensees to consider valve mispositioning as part of their GL 89-10 programs.
During the time while the staffis preparing the proposed supplement to GL 89-10, the staff stated that a PWR licensee may defer consideration of valve mispositioning in its GL 89-10 program.'
Where a PWR licensee has completed its GL 89-10 program with the exception of the consideration of valve mispositioning, the staff may close its review of the licensee's design-basis capability verification of MOV's within the GL 89-10 program provided the licensee commits to consider valve mispositioning if the staff determines that this recommendation in GL 89-10 remains appropriate.
Millstone Unit 2 committed in a memo" to consider valve mispositioning if the NRC Staff determines that the recommendation, to consider mispositioning, in GL 89-10 remains appropriate.
However, no MOV's were included or removed from the program based upon mispositioning.
- 8. MOV Program Scope Criteria Program Instruction (PI)-1,"MOV Program Scope Determination," establishes the criteria for determining which MOV's are included in the MOV Program. PI-l provides the methodology for performing and documenting this process, and establishes the criteria to identify other MOV's in the balance of plant, commensurate with their'importance to safety, to be included in the MOV Program.
In addition, it provides methods for determining the position-changeability of MOV's. Millstone Unit 2 has deferred consideration of valve mispositioning pending the results of the final NRC 16
l l
Millstone Unit 2 MOV Program November 9,1995 l
position on mispositioning.'" The Millstone Unit 2 MOV Program scope is defined in the
" Millstone Unit 2 MOV Program Scope Determination," Calculation 89-078-857ES, Revision 2, September 28,1995.
- 9. Design Basis Reviews PI 2,"MOV System and Functional Design Basis Review," defines the methodology and requirements for performing system and design-basis reviews under the scope of GL 89-10. PI-2 requires that the following key elements be identified:
- 1. All active safety-related functions for each MOV by reviewing all normal operating and abnormal valve line-ups.
- 2. The maximum bounding system parameters corresponding to each ncrmal operating and abnormal condition valve line-up, to include:
Line Pressure (Upstream and Downstream)
Head differences due to elevation between the pump and the valve will, in general, be included in line pressure and differential pressure calculations (e.g. the pressure downstream of a pump during flowing conditions should be assumed to be equal to the pump discharge pressure plus any elevation difference). 'Ihis assumption does not preclude the incorporation of dynamic piping losses in future analyses as a means ofjustifying reduced line pressure or differential pressure.
D uation 1: P,,,,,,,,,, in,,,,, = P_, + H,,,,,, t H,1,,,,,,,
i Source Pressure (Psouu) can include any combination of the following:
reactor coolant system pressure inter-connecting fluid system pressure tank pressure atmospheric pressure containment pressure pressure contained in sections of pipe that could be pressurized; sources such as leakage past other valves or thermal expansion of the fluid.
safety valve set point; nominal set pressure should be used for consistency. Use of set pressure tolerance is not required.
Pump Head (He,mp) is the available head of any operating pump at the appropriate flow rate converted to psig by an appropriate conversion factor.
if the subject valve's close stroke reduces the source pump flow rate to zero under its design-basis conditions, then the Pump Head is the Shutoff Head at 17
.m_
m u
m
..m.
Millstone Unit 2 MOV Program November 9,1995 l
l the valve's full closed position. The nominal or design pump head curve should be used for the calculation of pump head.
Elevation Head (Hwion) results from elevation differences between the valve elevation and any higher or lower elevation of piping / components /
tank water levels, etc., converted to psig by an appropriate conversion factor.
Maaimum Line Pressure l
Maximum Line Pressure is the greater of the upstream and downstream line pressures.
Differential Pressure The maximum differential pressure (psid) exists when the vdve is in its fully closed position Throttling valves are assumed to fully close in order to obtain a bounding differential pressure.
Process Fluid Temperature and Flow Process fluid temperature and flow values shall be determined and correspond to the highest postulated temperature and flow for the line pressure / differential pressure case listed.
Flow Direction (forward and reverse)
The flow direction shall be determined for each MOV operation. In general, the normal flow direction for the valve will establish the upstream and downstream side of the valve.
Ambient Environment Temperature The ambient environment temperature shall be determined for each MOV (i.e. normal operation temperature, accident and post-accident conditions).
For post-accident conditions, the ambient teinperature based on the EEQ Profile should be used.
Degraded Voltage at Design Basis Conditions The effects of degraded voltage at design-basis conditions on MOV performance shall be determined in accordance with PI-4,"AC and DC Motor Terminal Voltage Evaluation."
Process Fluid and Phase 1
The process fluid conditions (water, steam or two-phase) shall be determined j
for each identified MOV operation.
- 3. The maximum cases for both open and close operations.
The Millstone Unit 2 MOV Program design-basis review is contained in the Design Basis Review Calculations which are listed in Table 10. Also provided in Table 10 is a listing of the Electrical i
Calculations, Weak Link Calculations, and Target Thrust Calculations for each MOV. The information in the table is presented to demonstrate design-basis closure. Future changes will be controlled by existing NU procedures.
i
)
18
~<
- e Millstone Unit 2 MOV Program November 9,1995 b.
Table 10: Calculation Listing Valve Number DSR Rev Electrical Rev Weak Link Rev Thrust Rev i.
2-CH-429 89478400ES 04 PA89-078-272E2 00 94102-C-10 00 80-078-888ES 00 2-CH-601 89-078490ES 04 PA89 078-272E2 00 94102-C-09 00 89-078-889ES 00
~~
2-CH-504 89078490ES 04 PA89-078-272E2 00 94102-C-08 02 89-078470ES 00 j
2-CH408 89 078400ES 04 PA89-078-272E2 00 94102-C-08 02 89 078-1073M2 01
]
2-CH-509 89-078490ES 04 PA89-078-272E2 00 94102-C-08 02 89-078-1073M2 01 4
2-CH-514 89-078490ES 04 PA89-078-272E2 00 94102-C-08 02 89-078470ES 00 j
2-CS-04.1A 89-078490ES 04 PA89-078-272E2 00 94102-C 07 01 89 078471ES 01 2-CS-04.18 89-078490ES 04-PA89-078-272E2 00 94102-C-07 01 89-078471ES 01 2-CS 13.1A 89-078490ES 04 PA89-078-272E2 00 94102-C-11 00 89-078-872ES -
00 2-CS-13.18 89-078490ES 04 PA89-078-272E2 00 94102-C-11 00 89-078472ES 00 j
2-CS-18.1 A 89-078-890ES 04 PA89 078-272E2 00 94102-C-03 02 89-078473ES 00 2-CS-18.1B 89-078490ES 04 PA89-078-272E2 00 94102-C-03 02 89-078473ES 00 l
2-FW-38A 89-078-890ES 04 PA89-078-272E2 00 94102 4 02 01 89-078452ES 05 2-FW-388 89-078490ES 04 PA89-078-272E2 00 94102-C-02 01 89-078452ES 05 1
2-FW-42A 89-078490ES 04 PA89-078-272E2 00 94102-C-02 01 89-078-852ES 05 2-FW-428 89-078-890ES 04 PA89-078-272E2 00 94102-C-02 01 89-078-852ES 05 2-FW-44 89-078490ES 04 PA89-078-272E2 00 94102 4 08 03 89-078-885ES 04-2-MS45A 89-078490ES 04 PA89-078-272E2 00 94102-C-12 01 92-RPS442ES 02 2-MS453 89-078-890ES 04 PA89-078-272E2 00 94102-C-12 01 92-RPS442ES 02 l
2-MS-201 89-078490ES 04 PA89-078-272E2 00 94102-C-05 02 89-078-855ES 03 2-MS-202 89-078490ES 04 PA89 078-272E2 00 94102-C-05 02 89-078-855ES 03 l
2-RB-30.1 A 89-078490ES 04 PA89-078-272E2 00 94102-C-14 01 89-078-875ES 02 2-RB-30.18 89-078-890ES 04 PA89-078-272E2 00 94102-C-14 01 89-078-921ES 01 f
2-RB-37.2A 89-078-890ES 04 PA89-078-272E2 00 94102-C 14 01 89-078-875ES 02 j
2-RB-37.2B 89-078-890ES 04 PA89-078-272E2 00 94102-C-14 01 89-078-921ES 01 g
2-RC-403 89-078-890ES 04 PA89-078-272E2 00 94102-C-01 03 89-078-860ES 02 1
2-RC-405 89-078-890ES 04 PA89-078-272E2 00 94102-C-01 03 89-078460ES 02 2-SI-411 89-078-890ES 04 PA89-078-272E2 00 94102-C-21 00 89-078478ES 01 2-SI-412 89-078-890ES 04 PA89-078-272E2 00 94102-C-21 00 89-078478ES 01
[
2-S1414 89-078490ES 04 PA89 078-272E2 00 94102-C-04 01 89-078-877ES 00 l
2-S1415 89-078490ES 04 PA89-078-272E2 00 94102-C-15 00 89-078-878ES 02 2-Sl416 89-078490ES 04 PA89-078-272E2 00 94102-C-16 01 89-078-879ES 02 1
2-Si417 89-078-890ES 04 PA89-078-272E2 00 94102-C-16 01 89-078-922ES 00 l
2-SI-624 89-078-890ES 04 PA89-078-272E2 00 94102-C-04 01 89-078477ES 00 2-SI-625 89-078490ES 04 PA89-078-272E2 00 94102-C-15 00 89-078-878ES 02 2-Sl426 89-078-890ES 04 PA89-078-272E2 00 94102-C-16 01 89-078-879ES 02 l
2-S1427 89-078-890ES 04 PA89-078-272E2 00 94102-C-16 01 89-078-922ES 00 l
2-S1434 89-078-890ES 04 PA89-078-272E2 00 94102-C-04 01 89-078-877ES 00 1
2 Sl435 89-078490ES 04 PA89-078-272E2 00 94102-C-15 00 89-078478ES 02 2-S1436 89-078490ES 04 PA89-078-272E2 00 94102-C-16 01 89-078-879ES 02 I
2-SI-637 89-078490ES 04 PA89-078-272E2 00 94102-C-16 01 89-078-922ES 00 l
2-Sl444 89-078-890ES 04 PA89-078-272E2 00 94102-C-04 01 89-078-877ES 00 I
2-S1445 89-078490ES 04 PA89-078-272E2 00 94102-C-15 00 89-078-878ES 02 2-Sl446 89-078-890ES 04 PA89-078-272E2 00 94102-C-16 01 89-078479ES 02 i
l 2-Sl447 89-078-890ES 04 PA89-078-272E2 00 94102-C-16 01 89-078-922ES 00 l
2-Sl451 89-078-890ES 04 PA89-078 272E2 00 94102-C-04 01 89-078-882ES 00 2-SI-652 89-078490ES 04 PA89-078-272E2 00 94102-C-04 01 89-078-882ES 00 3
1 2-Sl453 89-078-890ES 04 PA89-078-272E2 00 94102 & 17 02 89 078-880ES 00 1
2-Sl454 89-078-890ES 04 PA89-078-272E2 00 94102-C-18 01 89-078-854ES 02 2-SI-655 89-078-890ES 04 PA89-078-272E2 00 94102-C-17 02 89-078-880ES 00 l
2-Sl456 89-078-890ES 04 PA89-078-271E2 00 94102-C-19 00 89-078-881ES 00 2-SV 4188 E9-078-890ES 04 PA89-078-272E2 00 94102-C-20 01 89-078-883ES 01 i
i 4
i 19 i
Millstone Unit 2 MOV Program November 9,1995 l
l
- 10. MOV Sizing and Switch Settings
- 10.1 Valve Weak Link Analysis NU has performed weak link analyses for all MOV's in the GL 89-10 Program. He weak link analyses have determined the thrust or torque structural capacity of each component involved in supporting the MOV opening and closing strokes.
These analyses evaluated all structural components of each MOV which typically included the valve body, bonnet, yoke, stem, disk and appropriate flanges including bolted interfaces as a minimum.
The allowable thrust or torque capacity of each MOV was developed using the valve vendor's weak link analysis which have been independently reviewed and in most cases supplemented by Altran Corporation of Boston, MA. Completion of the weak link analysis results in identification of the weakest component of the MOV as well as the limiting thrust or torque load which could be accommodated by the valve for the given conditions.
The formulae employed in the weak link analyses are those traditionally used for determining stress and consider the appropriate temperatures and pressures along with other plant specific design loads applied as required. The weak link evaluation and acceptance criteria are governed by a detailed and rigorous program instruction entitled, PI-3,"MOV Structural Evaluation". PI-3 criteria were based on the original valve design requirements as specified in the plant final safety analysis report, original construction valve specifications and subsequent plant licensing items, such as the SEP and GL 89-10.
With the exception of Millstone Unit 3, the original design code requirements were not stress (i.e.,
thrust) based criteria. The lack of thrust based limits would have precluded comparison with as-left and design-basis thrust values. With the exception of the valve actuator and stem nut, pressure and non-pressure boundary components of valves were evaluated to Section III of the ASME B&PV Code in accordance with PI-3 instructions. This in effect constituted a voluntary Backfit for Haddam Neck, Millstone Unit 1, and Millstone Unit 2.
Once the allowable stress was identified, the maximum thrust capacity of each structural element was solved for and tabulated in the weak link analysis. Additional thrust or torque limits were also developed which defined the threshold that, if exceeded during testing / set-up, would require engineering evaluation through more refined analysis techniques for potential corrective actions including inspection and / or replacement of weak link parts.
Included in the weak link analyses described above, NU has also evaluated the structural effects of motor actuator stall loads on the pressure boundary parts of MOV's for actuators which have been modified such that the resultant thrust output of the actuator at stall has been significantly increased.i2 Part of the structural limits developed in the weak link analyses have included allowable thrust or torque under motor actuator stall conditions.
The purpose of this additional evaluation was to ensure the resultant increase in stall thrust output of the modified actuator would not introduce a malfunction of the MOV different than any evaluated previously in the safety analysis report. The analysis compared the thrust or torque output at stall to the MOV's pressure boundary structural capacity and confirmed the valve's pressure boundary integrity was maintained. NU believes this analysis provided assurance that if a modified actuator developed stall thrust, the pressure boundary of the MOV would not be breached.
20
Millstone Unit 2 MOV Program November 9,1995 4
1 Conformance to the ASME B&PV Code allowable stress criteria and PI-3 requirements as well as i
meeting the analytical and testing acceptance criterion of all other applicable Project Instructions in i
NU's MOV Program Manual have confirmed both the integrity of the pressure boundary as well as the functionality of the MOV.
L 10.1.1 Load Cases and Combinations The valve components were evaluated for the following loading combinations for the valve opening j.
and closing directions. Loads due to pressure, deadweight, seismic, other occasional loads (such as water hammer, blowdown and other hydrodynamic loads, if applicable), and thrust / torque were j
included in the weak link analysis.
10.1.1.1 As-Left Load Combinations (Design Basis)
}
Table 11: As-Left Load Combination (Design Basis)
Condition Load Combinadon Normal Pa + DW + Thrust / Torque i
OBE Pa + OBE + DW + Thrust / Torque SSE Pa + SSE + DW + Thrust / Torque where:
l DW
= Loads due to dead weight of the valve components including the operator.
Pa
= Loads due to the maximum pressure of: design, operating, design accident or a valve mispositioning event (as applicable) per GL 89-10.
= Loads due to the operating basis earthquake.
= Loads due to the safe shutdown earthquake.
l Thrust /
= Operational loads due to simultaneous seating stem thrust and torque loads Torque acting on the valve components. For purposes of this evaluation the torque shall be taken as the stem thrust load times the stem factor.
l 10.1.1.2 Non-As-Left Load Combinations The valve components are also evaluated for the following MOV Program test (i.e., set-up) l conditions for the appropriate valve direction (opening, closing).
Table 12: Non-As-Left Load Combinations i
Condition Load Combination
~
Static Test:
Dynamic Test:
DW + P, + Thrust / Torque where:
l DW and Thrustfrorque as defined above i
P
= Loads due to actual operating line / dynamic pressure during valve test.
i 10.1.1.3 StallLoad Combination l
For MOV's which needed to be evaluated for stall in accordance with NU's position on stall evaluations discussed above or, when the valve had been stroked in a manner which resulted in a i
stall event, the valve components were evaluated for the following motor stall conditions for the appropriate valve direction.
21
1 Millstone Unit 2 MOV Program November 9,1995 l
Table 13:StallLoadCombination Condition Load Combination Stalt DW + P. + Thrust / Torque where:
DW and P. as defined above Thrustfrorque = Stall load as determined in accordance with Appendix E of PI-3.
10.2 Valve OperatorLimits Similar to the " weak link" analysis for the valve, the operator's manufacturer (i.e., Limitorque) established limiting operating parameters for the operator. Situations occurred across the industry where the operator's limits would not allow attainment of the forces required to ensure the associated valve's operation under design-basis conditions. Thus, several utilities combined resources to fund a study by Kalsi Engineering tojustify increasing the published limits.
Northeast Utilities became an active participant in the Limitorque Phase I and II Overload Testing Program being conducted by Kalsi Engineering,Inc. The Phase I portion of this program provided the necessary testing and analysis to substantially increase the published thrust rating for Limitorque operator sizes SMB-000 through 1. The thrust rating for each size operator was increased to 162%
of the published thrust rating for 2000 cycles or 200% of the published rating for 763 cycles. This report was reviewed and approved by the NU MOV Engineering group for use at Millstone Unit 3.
Applicable Target Thrust Calculations incorporate the Limitorque Technical Update 92-01 (use of 140% thrust rating). On a case basis, Kalsi reports are also utilized, as appropriate, in accordance with PI-9," Determination of Stem Thrust Requirements".
As an extension to the Phase I thrust overload test results, the Phase Il program was initiated in March 1992 to qualify the SMB-2 and the SB-000 through 2 operator design to larger thrust ratings.
In addition, the torque carrying capabilities of the H0BC and the SMB-000 through SMB-2 operators were chosen for funher study. The results provide additional margin and extend the results of the Phase I study to a broader population of motor operated valves at Millstone Unit 2. We also have the software for determining fatigue life for greater than rated torque.
We have extended the rating of SB operators based on Kalsi Engineering's Phase Il report," Thrust Rating Increase of Limitorque SB-00 Through SB-2 Spring Compensator Assemblies and SB-00 Through SB-1 Operators," Document No.1799C, Rev. O, October 7,1994. On January 30,1995, Limitorque issued a letter to Kalsi Engineering concurring with the conclusions of the Kalsi Phase II Report.
10.3 Electrical Calculations were performed to determine the motor-operated valve minimum terminal voltage using locked rotor current and to use the appropriate Limitorque operator factors and design thrust values in the Limitorque sizing equations to determine correct operator motor sizing.
For alternating current (AC) MOV's, a motor control center (MCC) voltage corresponding to the minimum degraded bus voltage was used to supply the motor-operated valve feeder cables. This degraded voitage was based on load flow calculations assuming a hypothetical minimum switchyard grid voltage and accident (LOCA) bus loadings in accordance with PI-4, "AC and DC Motor Terminal Voltage Evaluation."
22
a Millstone Unit 2 MOV Program -
November 9,1995 The cable voltage drop is developed using a constant impedance motor model for a given ambient temperature (90"C). The model was developed from the locked rotor current and the nameplate voltage. In response to Limitorque Part 21, Reliance actuator motors were derated due to ambient eperating temperature in accordance with PI-4. Additionally, Millstone Unit 2 calculations applied this derate to the nine actuators with non Reliance motors in accordance with recent non-Reliance motor studies." For valves located in areas where the maximum design-basis accident (DBA) temperature exceeded 40 C, the derating was applied to the starting current for that valve motor at the maximum DBA temperature. The derate accounts for the resistive rise in the motor at elevated
_ temperatures.
The cable size, cable lengths, and thermal overload and magnetic coil resistances were obtained for all of the listed 460V AC motor operated valves. Power factors for locked rotor torque conditions were obtained from Limitorque. The cables were derated to elevated temperatures, and the cable voltage drop / motor terminal voltage was calculated for each MOV. These motor terminal voltages were then used to determine appropriate motor sizing using the Limitorque sizing equation.
l 10.3.1 Motor Performance Factors j
Defined below are the values used for various motor performance factors:
Motor rating i
We use 100 percent of nameplate rating for the motor.
f Efficiencies used in open and close directions The source for open and close ciliciencies is the Limitorque Sizing and i
Selection Procedure dated November 9,1990. For AC motors we use pullout efficiency in the open direction, running efficiency in the closed direction, and stall efficiency for stall calculations. For DC motors we use 2
pullout efficiency in both the open and closed direction. Millstone Unit 2
'e does have one DC motor MOV's in the GL 89-10 program.
i Application factor We use an application factor of 1.0 to determine motor capability for target thrust / torque calculations.
Power factor used in degraded voltage calculations PI 4, "AC and DC. Motor Terminal Voltage Evaluation," requires the use of the power factor supplied by the motor operator manufacturers for the specific motor at Locked Rotor Current. If the value is not available from the manufacturer, we assume a 0.8 power factor.
j 10.3.2 Effects of Design-Basis Degraded Voltage on MOV Performance PI-4,"AC and DC Motor Terminal Voltage Evaluation," provides instructions for performing minimal terminal voltage evaluations for AC and DC powered MOV's. This evaluation provides direct input to the motor derate output torque evaluation which is then input to PI-9, " Determination of Stem Thrust Requirements," for evaluating the effects of degraded voltage at design-basis conditions.
23
i Millstone Unit 2 MOV Program November 9,1995 PI-4 uses locked rotor current at degraded voltage conditions to determine motor terminal voltage.
Because this is beyond the current licensing basis of the Millstone nuclear units and Connecticut Yankee, when operability issues arise,(e.g., when inadequate motor terminal voltage is predicted
__ during the course of a degraded voltage calculation), additional MOV specific calculations will be performed with less restrictive assumptions (e.g., use of starting current).
10.4 Design Thrust The following equation is used for design set-up with gate and globe valves.
Equation 2: Design Thrust = (DPx Asurx VF) + PL1PE DP
= Differential Pressure for the open or close stroke.
2 Asr2T
= valve seat area = (3.14159'D ) / 4, where D is the mean seat diamet.:r that most closely reflects the contact surface at the seat to dir.c interface. For plug-in-cage globe valves with piston / guide rings on the plug, the guide rings determine the D, area rather than the seating diameter.
= Refer to Table 14 for the valve factor selection criteria for gate valves.
= 1.1 for globe valves.
PL
= Packing Loads are assumed as follows:
Packing Load Valve Stem Diameter 1000 lb.
s 1.0 in.
1500 lb.
> 1.0 in. 5.1.5 in.
2500 lb.
> 1.5 in. 5 2.5 in.
4000 lb.
> 2.5 in. 5 4.0 in.
5000 lb.
> 4.0 in.
= Piston Effect (PE) is calculated as follows:
(1) Gate Valve: PE = Valve Stem Area x Line Pressure (LP)
(2) Globe Valve: PE = Valve Stem Area x (LP - DP)
Post set-up, static and dynamic testing valve factors, packing loads, and rate ofIcading (ROL) values are revised appropriately, if measured values exceed design set-up values.
10.5 Valve Factor NU's technical position on gate valve, valve factors (Vf's) reflects the "best available knowledge."
Actions taken by NU in response to the November 30,1993, NRC Information Notice," addressing valve factor data, are contained in a memo" in the MOV Program Manual. The MOV Program Manual provides the criteria used to choose Vf for gate valves in the GL 89-10 program for operability, design set-up and for GL 8910 closure.
"Best available data" was derived from quali,ty assurance (QA) reviewed EPRI Performance Prediction Program (PPP) valve test results,' other industry testing, and guidance contained in Reference 17. EPRI results confirm 1.1 is an appropriate value for globe valve design set-up.
However, evaluation of this information prompted the adoption ofincreased valve factors for gate 24
Millstone Unit 2 MOV Program November 9,1995 valves in many cases. Prior to this change NU had used vendor supplied valve factors or had assumed a 0.3 Vf for gate valves. A comparison of NU GL 89-10 MOV's was made to the valves tested in the EPRI program, ne results of this comparison revealed no matches between EPRI valves and NU non-dynamically testable MOV's.
varying plant conditions and for different phases of the MOV Program.'pate Table 14 summarizes the criteria used by NU for different categories of These values are used to achieve flow isolation in the close direction and are assumed to be applicable in the open direction.
I The " Design Set-up" values were used in conjunction with PI-9 during the preparation of target thrust calculations.
L Table 14: Gate Valve VfCriteria Category Operability Design Set-up GL 89-10 Closure Comment Dynamically Dynamic Test t0.4 Measured Vf or 0.3:
Adjust for Design Testable (Note 1)
Whichever is Basis Conditions Greater (Notes 2 and 3)
Non-Testable; intenm: 20.4 2 0.6 EPRI PPM or Intenm Operabikty Wedge Gate After 1" RFO:
(Notes 4 and 5)
Other (Note 6)
PPM or Other Other (Note 7)
Non-Testable:
Interim: 2 0.4 2 0.4 EPRI PPM or Note 8 ParalleIDisc After 1" RFO:
(Note 8)
Other PPM or Other Testable:
EPRI PPM, or 1 0.9 or EPRI PPM or VfE 0.9 NOTPlanned for Grouping. or Grouping Vf Grouping Vf or (Note 9) l Dynamic Test Other Other a
l I
Notes:" (1)This value includes margin for " preconditioning or aging" effects. NU will continue to monitor this effect during testing and through industry data, making adjustments as necessary.
(2) Dermitive determination of Vf and operability will be provided by dynamic testing properly adjusted to Design Basis conditions.
i (3) A Vflower than 0.3 may be used ifjustified by test results.
(4) EPRI data indicates a Vf of 0.4 is a bounding value for stellite surfaces under high contact stress, flat-on-flat disc-to-seat contact, at temperatures above 350"F. An allowance of 0.2 is provided to allow for " poor geometry" and the differences between mu and Vf.
(5) With the torque switch bypassed until flow isolation, the thrust at this Vf constitutes the design-basis thrust due to dynamic conditions to be used for structural evaluation.
(6) Use of a Vf 20.4 is an interim operability screening value for use at each unit until their first refueling after December 4,1993. This is a more realistic number than the 0.3 Vf previously used in NU's MOV Program Manual. A 0.4 Vf bounds about 50% of EPRI blowdown tests; is the minimum value stated in Reference"; and is a " good geometry" bounding value for high contact stress, flat-on-flat disc-to-seat contact, at temperatures above 350 F. It is not considered a conservative value.
(7) "Other" includes technicallyjustifiable approaches, e.g. special tests, analysis, a
ett..
25
_ ~. - -
7 Millstone Unit 2 MOV Program November 9,1995 i
i (8) A 0.4 Vf bounds the limited EPRI PPP test data for parallel-disc Anchor-l j
' Darling gate valves at temperatures > 350 F. 'Ihis is also consistent with the j
results of blowdown testing performed by Anchor-Darling. EPRI testing also
'I indicates 0.4 is a bounding value for hip contact stress, flat-on-flat disc-to-
. seat contact, at temperatures above 3507.
{
(9) A 0.9 Vf bounds virtually all empirical data for gate valves.
i Provided in Table 15 are valve factors (measured, programmatic,'8 or calculated by Kalsi j
Engineering) and measured rate ofloading values for each MOV. The shaded areas represent l
j MOV's set-up on limit switch or torque switch bypass control.
4 j
High margin valves were reviewed to ensure the as-left valve factor exceeded 0.9.'
Any future f
valve testing w'hich could impact the valve set-up cannot be done without a revision to the target thrust window. ' For high margin valves, the revised calculations use a 0.9 valve factor and an additional 25% margin in establishing the new thrust window.
Table H: Valve Factors andMeasuredRate ofLoading i
valve valve Factor l Rate of l Valve valve Factor Rate of j
Number Close Open l Loading l Number Close Open Loading
~
2-CH429 0.69 0.69 l l
2-RC-405 0.45 0.45 l
2-CH-501 0.4 "'
O.4 l
l 2-SI-411 0.4 "'
O.4 2-CH-504 0.4 "'
O4 l l
2-SI-412 0.4 "3 0.4 2-CH-508 0.6 "'
O.6 l l
2-S1414 0.71 0.71 2-CH 509 0.6 "'
O.6 l l
2-Sl415 1.1 1.1 l
2-CH-514 0.4 "'
O.4 l
l 2-Sl416 1.1 N/A 2-CS-04.1A 0.4 0.4 l
l 2-S1417 1.1 N/A 7.9%
i 2-CS-04.1B 0.4 0.4 l l
2-S1424 0.71 0.71 2-CS-13.1 A 0.4 "'
O.4 l
l 2-Sl425 1.1 1.1 7.2%
2-CS-13,1B 0.4 "'
O.4 l
l 2-Sl426 1.1 N/A i
2-CS-16.1 A 0.54 0.54 l l
2-S1427 1.1 N/A 1.6%
2-CS-16.1B 0.54 0.54 2-Sl434 0.71 0.71 2-FW-38A 0.6 0.6 2-Sl435 1.1 1.1 l
2-FW-38B 0.6 0.6 2-Sl436 1.1 h/A l
2-FW-42A 0.6 06 2-Sl437 1.1 N/A 3.5%
l 2-FW 42B 0.6 0.6 2-S1444 0.71 0.71 l
2-FW-44 0.506 0.506 2-Sl445 1.1 1.1 1
2-MS45A _
1.1 1.1 2-Sl446 1.1 N/A 2-MS45B 1.1 1.1 l
l 2-SI-647 1.1 N/A j
2-MS-201 0.4 0.4 l -8.4% l 2-Sl451 0.4 0.4 j
2-MS-202 0.4 0.1 l -14.0% l 2-Sl452 0.4 0.4 2-RB-30.1A 0.3 0.682 l -3.2% l 2-Sl453 0.4 "'
O.4 2-RB-30.1B 0.4 "'
O.4 l
l 2-Sl454 0.4 C.304 "'
2-RB-37.2A 0.3 0.496 l 1.8% l 2-Sl455 0.4 ")
0.4 2-RB-37.2B 0.4 "'
O.4 l
l 2-Sl456 0.4 "3 0.4 2-RC-403 0.453 0.526 l l
2-SV-4188 1.1 1.1 Note: (1) High margin valves with as left valve factors greater than 0.9.n.20 J
26
Millstone Unit 2 MOV Program November 9,1995 10.6 Stem Factor / Stem Friction Coefficient Millstone Unit 2 calculations use a stem factor based on a friction coefficient of = 0.15 or greater for all valves unlessjustification is provided. This assumption is based on information and
_ experience from the following sources:
Industry experience Testing performed by Northeast Utilities e
Limitorque sizing procedures e
Engineering Record Memo, ER-95-0124, Revision 1, Clarification of Assumptions Used in the Revision of Target Thrust Calculations"22 NMAC Application Guide for Motor Operated Valves in Nuclear Power Plants, e
NP-6660-D EPRI Stem / Stem-Nut Lubrication Test Report, TR-102135 e
The actuator of an MOV produces torque For rising stem valves, the torque produced is converted to thrust at the stem and stem-nut interface, or yoke-nut for rising rotating MOV's. The stem and stem-nut / yoke nut is a power screw which in most cases uses ACME threads. He efficiency of conversion of torque to thrust by the stem and stem nut / yoke-nut is called the " Stem Factor." He stem factor is determined by stem geometry and the coefficient of friction between the stem and the stem-nut / yoke-nut. Since the geometry of a given stem is fixed, any change in coefficient of friction will change the stem factor.
Industry testing has shown that the coefficient of friction can vary over a range of about 0.08 to 0.20.
This range of friction coefficient can change the output thrust for a given torque input by 250%,
thereby potentially effecting its ability to perform its intended function. Determining and 4
maintaining a stem to stem-nut coefficient of friction is dependent upon mechanical condition, lubricant used, lubricant co dition, and preventive maintenance practices.
i Measurement of torque and thrust under static conditions may not provide an accurate representation of coefficient of friction for the design-basis condition. Under static running load conditions, the load on the stem to stem-nut is not high enough to maintain even contact loads between the stem and stem-nut, causing the two to " float." This produces large swings in the measured coefficient of friction. Measurements taken at static torque switch trip can also be misleading, since at this point in the valve stroke there is little or no actual rotational movement. Under this condition, the measured coefficient of friction although consistent, will usually be lower than the actual value under design-basis conditions.
Northeast Utilities has validated the assumed = 0.15 by monitoring torque and thrust d tring selective dynamic tests for Haddam Neck, Millstone Unit 1, and Millstone Unit 2 for valves with similar lubrication practices. For Millstone Unit 3, p = 0.18 is assumed. Table 16 provides the results of all applicable valid stem coefficient data measured in NU's MOV Program to date. As can be seen, = 0.15 bounds 100 percent of the data for Haddam Neck and Millstone Unit 1. At Millstone Unit 2, for dynamically tested globe valves with an anti-rotation key, an additional 10% is added to the measured stem thrust to account for parasitic losses due to the anti-rotation key. This is applicable where torque is measured above and thrust is measured below the anti-rotation key.22 A p = 0.15 is used for all other valves. A review of EPRI PPP data at flow cutoff shows >> 99% of the data being below 0.15. This review covered in excess of 800 strokes. This adds significant credibility to NU's use of 0.15 as a bounding value.
27
9 Millstone Unit 2 MOV Program November 9,1995 0
Table 16: Gate Valve MeasuredStem to Stem-Nut Coepicient ofFriction (p)
Valve Dynamic COF l
Close Open BA-MOV-373 0.046 CH-MOV-257 0.103 0.119 CH-MOV-257B 0.103 l 0.119 l CH-MOV-2928 0.031 0.063 CH-MOV-292C 0.068 SI-MOV-861C 0.120 SI-MOV-871B 0.13 0.085 1-CS-218 0.106 1-CU-5 0.130 0.110 1-LP-7A 0.096 1-LP-13A 0.129 0.139 1-LP-13B 0.130 0.133 1-LP 14A 0.123 1-LP-148 0.129 1-LP-43A 0.1 0.146 1-LP-438 0.101 l 0.109 l 1-MW-96A 0.137 0.121 2-FW-44 0.152 2-MS-201 0.06 2-MS-202 0.091 0 -
I 3CHS*MVB106 0.179 3CHS*MV8116 0.153 WM g
g 3CHS*MV8438A 0.146 3FWA*MOV35A ('93) 0.100 3FWA*MOV35A ('93) 0.135 mie 3FWA*MOV35B 0.156 =. - _ _
4 3FWA*MOV35D 0.103 3RHS*MV8702B 0.093 l 3RHS*MV8702C 0.091 l 3RHS*MV8716A 0.109 hjfL 3RSS*MV8837A 0.155 3RSS*MV88378 0.125 Blf 3SlH'MV8801A 0.153 i
Where possible, NU's MOV's were tested using the VOTES Torque Cartridge / Quick Stem Sensor (VTC / QSS) to validate our selection of friction coefficient. Currently we have obtained 43 data points for coefficient of friction for the four Connecticut units. These data points were obtained under dynamic (i.e., flow and differential pressure) conditions, to best represent design-basis conditions. As noted, all data points are below 0.15 for Haddam Neck, Millstone Unit 1, and Millstone Unit 2, and below 0.18 for Millstone Unit 3; therefore validating our assumption. To add i
further rigor to NU's MOV Program, we are assessing the use of statistical analysis of our final data set (post Millstone Unit I completion) as a validation methodology. This will require additional data to permit meaningful statistical analysis.
28
Millstone Unit 2 MOV Program Nov:mber 9,1995 10.7 Margin The definition of margin varies from one licensee to another. Making simple comparisons of the numerical value is an unreliable indication. For example, NU's quoted margin is approximately
~
20 nercent greater than a licensee who uses 0.5 for a non-testable gate valve factor, if all other parameters are the same. The definition of margin is provided below:
' Thrustm, - Thrust,j Equation 3: Margm, =
x 100%
Thrust,w Listed in Table 17 is the margin for the safety stroke and the periodic testing priority for each MOV (see Section 14.3). The shaded areas indicate that there is not a safety stroke for that direction. Open margin was not calculated for globe valves which have flow under the seat, and is indicated in the table by FUS (flow under seat). The flow would assist in opening the valve and the resulting open margin values would be very large. The information in the table is presented to demonstrate design-basis closure. Future changes will be controlled by existing NU procedures.
Table 17: Margin Valve Periodic Close Opwn Valve Periodic Close Open Number Testing Margin Margin Number Testing Margin Margin Priority
(%)
(%)
Priority
(%)
(%)
2-CH429 2
62 31 2-RC-405 1
20 122 2-CH-501 2
4 mm 2-SI-411 2
69 182 2-CH-504 2
gp Note 1 2-SI-412 2
103 222 2-CH-508 2
FMgg 270 2-SI-614 2
46 hhg$g n ;
239 140 2-SI-615 1
2-CH-509 2
- r 1646 @
Note 1 2-SI-616 1
'?T?>
FUS 2-CH-514 2
2-CS-04.1 A 1
211 57 2-SI-617 1
G, ' ' 4 FUS y
2-CS-04.1 B 1
519 48 2-SI-624 2
50 prdaf aug$h q,,i 244 na 2-SI-625 1
2-CS-13.1 A 2
79 M
2-SI-626 1
4J j FUS 2-CS-13.1 B 2
43 2-CS-16.1 A 1
-- y 3
2-SI-627 1
@M FUS
.h 16 2-SI-634 2
58 PW 2-CS-16.18 1
a.lg0s 546 2 FW-38A 2
45 E
2-SI-635 1
m#
5 s' FUS 2-FW-38B 2
54 2-SI-636 1
m 2-FW-42A 2
53 j
2-SI-637 1
EliTd FUS 2-FW-42B 2
51
?
j 2-SI-644 2
37
- ce-m 2-FW-44 2
64 6
2-SI-645 1
171 2-MS-65A 2
30 FUS 2-SI-646 1
FUS 2-MS-65B 2
23 FUS 2-SI-647 1
g,q [ FUS 2-MS-201 2
160 327 2-SI-651 1
Qc, 88 2-MS-202 2
29 218 2-SI-652 1
i #A.. A 81 2-SI-653 2
515 85 2-R B-30.1 A 2
31 egrg 2-RB-30.1 B 2
41 7W4 2-SI-654 2
win 135 2-RB-37.2A 2
74 e
2-SI-655 2
863 FUS 2-SI-656 2
gg 13 2-RB-37.2B 2
54 2-RC-403 1
1 11 59 2-SV-4188 1
nxd 84 Note 1: Open thrust values are inflated due to calibration error.
FUS -- Flow Under Seat 29
Millstone Unit 2 MOV Program November 9,1995 10.8 Stem Lubrication and Springpack Relaxation The MOV Program assumes little or no degradation of stem lubricant will occur between maintenance intervals. This is based on a preventive maintenance program, and using the " reservoir method" of stem lubrication, which limits degredation of stem lubricant. To validate this assumption,"as-found" dynamic tests may need to be performed unless another means of monitoring stem lubrication effectiveness statically can be developed. Currently, use of motor power to provide this capability without further dynamic testing is being evaluated. The small number of as-found tests conducted to date indicate that there is no lubrication degradation using the reservoir method, therefore validating our assumption that additional margin is not required. However, for those
. MOV's with small overall margin, we will continue to closely monitor for changes.
L 10.9 Selection of MOV Switch Settings item b. of GL 89-10 requires that methods exist for selecting and setting MOV switches (i.e., switch settings) to ensure high reliability of safety-related MOV's. MOV sizing calculations and methods for determining switch setting are described in PI-9," Determination of Stem Thrust Requirements,"
memorandum MOV-RTH-93-034,"NU MOV Program: Acceptance Criteria for Gate Valve, Valve Factors (Vf),"" and target thrust calculations. PI-9 establishes the methodology for determining the i
target torque and thrust values for globe, gate, and Wt un valves, and the corresponding control l
switch settings. In addition, it provides instructions for determining a MOV's capability. The appropriate limit and torque switch settings are determined following the valve capability analysis.
MOV limiter plate sizing to prevent exceeding torque based limits is also included in PI-9. It is 4
conservative to use the motor pull-out efficiency to calculate valve thrust requirements for the open and closed cases, however it is also permissible to use the motor running efficiencies for closed I
cases, for AC actuators.
Design set-up calculations for determining thrust requirements and actuator capability assume the following: a valve factor of 0.4 for rising stem gate valves that will be dynamically tested; 0.6 for
- non-testable wedge gate valves; and 0.4 for non-testable parallel disc gate valves. For the non-testable valves or where representative dynamic conditions cannot be reasonably created, NU plans to use "best available data" in determining valve factors (e.g., the EPRI Performance Prediction Program, Kalsi Engineering evaluation, or from grouping of data from other dynamic tests). We reviewed preliminary information provided by EPRI's Performance Prediction Program and used this information as a basis for raising our valve factor assumptions from the previous standard assumption of 0.3 for wedge gate valves. For Millstone Unit 2 a stem friction coefficient of 0.15 for gate valves and 0.18 for globe valves is used for determination of actuator output thrust capability.
3 Thrust requirements for setting of actuator torque switches are adjusted to account for diagnostic equipment inaccuracy and torque switch repeatability.
The design-basis thrust calculations specify a 1.1 margin for non-testable gate / globe valves to account for load-sensitive behavior (also known as " rate ofloading"), unless the valve is on torque switch bypass (see Section 10.10). Load sensitive behavior data obtained from dynamic tests (i.e.,
testable gate / globe valves) is incorporated into target thrust calculations. Load sensitive behavior can reduce the thrust delivered by the motor operator under high differential pressure and flow conditions from the amount delivered under static conditions. The MOV Program allowance of 1.1 is based upon NU specific measurements statistically analyzed as a truncated normal distribution to exclude negative values (see Section i1.3). We will continue to monitor industry development of 4
23 increased understanding of this phenomenon and make changes to our analysis results to account for load sensitive behavior.
30
_ ~ _.. _ _. _ _.. _ _ _ _
Millstone Unit 2 MOV Proy ii November 9,1995 1
i Four-rotor limit switches are installed on all actuators in the Millstone Unit 2 GL 89-10 programi j
Actual limit switch settings are in the MOV schematic diagram. ne following limit switch settings j
,t apply to all MOV's, unlessjustified for a different setup, and are documented in accordance with PI-8," Control of MOV Settings"f
[
Open Limit - shall be set to 5% (nominally) from the full open valve position. De exact set point shall be determined on a case by case basis in order to ensure the valve does not torque into the backseat, coast into the backseat or adversely effect the stroke time of the MOV. The open limit shall be adjusted for the additional coast i
due to the piston effect ofline pressure. He setting shall also be selected such that i
the valve disc does not excessively protrude into the flow stream.
Close Limit - shall be set 0 to 10% from the valve full closed position (hard seat l
contact / flow isolation) on limit closed valves. His setting is only applicable if the l
original plant design-basis utilizes the close limit switch in its control circuit and the actuator speed requires closing on limit.
i Open-to-Close Bypass - shall be set greater than 5% from the full open valve j
position on MOV's designed to backseat only. Othenvise, there are no requirements.
The "97% nominal close torque switch bypass"(CTSB) may be used. In this application the close torque switch is bypassed until flow cut offis ensured. Once the port is covered the torque switch comes back in the circuit and controls closure.
A limit switch repeatability of I % shall be applied to CTSB setpoint to ensure the port is covered and the motor is cut off before hard seat contact. Use of a limit switch repeatability less than i 1% may bejustified by performing limit switch repeatability tests or via correlation to existing NU limit switch repeatability data.
All limit switch repeatability data must be statistically analyzed to ensure proper sample size and to confirm the actual limit switch repeatability is within a 95%
confidence range".
t Close-to-Open Bypass - shall be set greater than 45% from the full closed valve position. This setting is critical to ensure operability of the valve. (Note: Some valves have interlocks which required setting at 20% from full closed.)
Open position indicator (green light off) - shall be set to trip within *0% to -2%
(of full stroke) of open control switch trip, for MOV's which open on limit. For MOV's which intentionally backseat, the switch shall be set in accordance with Unit Engineering requirements.
Close position indicator (red light off)- when MOV is torque closed then light shall be set no greater than 3% (of full stroke) before hard seat contact and no greater than 15% (of the distance between hard seat contact and CST) after hard seat contact. Iflimit switch controlled, the switch is set in accordance with an approved set-up procedure.
l Intermediate Limits - Limits providing interlocks, status inputs, and special signals must be set so the limit switch at least changes state prior to the valve control switch.
i 31
f Millstone Unit 2 MOV Program November 9,1995 e
For gate valves, limit control in the closing direction may be used in lieu of torque switch control, as j
appropriate. The limit switches associated with Limitorque actuators are used for various functions including interlocks, position indication and controlling valve position. The limit switches are gear-driven directly off the drive sleeve for models SMB-000 and SMB-00 or the worm shaft for models SMB-0 through SMB-5. With this arrangement, it is possible to adjust a limit switch to control valve position within a few hundredths of an inch. For the normal uses the limit switch is put to, this fine control is not necessary, and therefore has not been evaluated.
Control of motor-cperated gate and globe valves in the closing direction is normally performed by i
the torque switch. In certain cases, control by use of the limit switch is desirable. These cases include high inertia, bypassing the close torque switch until flow isolation is achieved, and butterfly /
plug (quarter-turn) valves. In all cases the valve is being controlled by stem position rather than output torque. The allowable band of stem position in these situations is very small, sometimes as little a one quarter inch, so the ability to set the limit switch to control in these regions is critical.24 In addition to the ability to set the limit switch, some determination of the ability of the switch to trip at the same point each time must be made. The repeatability of the limit switches for Limitorque actuators is commonly reported at 2 to 3%. There has been no industry documentation of any testing or evaluation oflimit switch repeatability. The purpose for which we use limit switch control of valve closure on a gate valve requires better repeatability than 2 to 3%. NU has determined limit switch repeatability for particular applications based upon statistical analysis of multiple valve strokes 23 (see Section 12.2.3).
At Millstone Unit 2, only four gate valves (2-FW-38A/B and 2-FW-42A/B) are set-up on limit switch control. One valve is set-up on torque switch bypass (2-FW 44).
10.10 Torque Switch Bypass Methodology NU has implemented a methodology of bypassing the torque switch until flow cutoff. This control configuration is similar to limit-closed configuration because the full capability of the motor actuator is available to close the valve. However,NU's torque switch bypass configuration differs because the limit switch removes the torque switch bypass until flow cutoff and not the motor power. This allows the motor to ensure the disk covers the flow path then fully seat the disk based on torque switch trip. The torque switch setting is adjusted as high as possible to provide the greatest assurance of proper valve seating under a static condition.
Using this control configuration, a possibility exists during a close stroke under dynamic conditions for the motor torque to exceed the torque switch trip setpoint, which is bypassed. As a result, when the torque switch bypass is removed (after flow cutoff), motor power will be cut off after flow is stopped and, possibly, prior to hard seat contact. NU uses information contained in EPRI's NUMAC," Application Guide for Motor-Operated Valves in Nuclear Power Plants," as guidance on the sealing contact force required to obtain a leak-tight seal.
4 Torque switches are generally bypassed in the opening direction for approximately the first 45 - 65%
of the stroke. The open limit switch is used to control termination of the open stroke for rising stem and rising / rotating stem valves to prevent backseating of the valve. The torque switch is bypassed in the closing direction except for the last 5-20% of the stroke.
32
o Millstone Unit 2 MOV Program November 9,1995
- 11. Design-Basis Capability 11.1 In-situ Design Basis Verification Testing Item c. of GL 89-10 requires that each MOV be tested in-situ at design-basis conditions, if practicable, to demonstrate that it is capable of performing its intended function. In addition, Item c.
requires that each MOV be stroke tested at no-pressure or no-flow conditions (static testing) to verify that the MOV is operable even if testing with a differential pressure or flow cannot be performed.
PI-10," Static Testing," establishes guidelines for developing unit-specific test procedures for performing static condition testing of MOV's.
PI-l1," Determination ofIn-Situ Test Capability," establishes the methodology and requirements for determining in-situ testability of MOV's at design basis conditions. In addition, it establishes the requirements for documenting and justifying those cases where in-situ testing cannot be practicably performed at design-basis conditions (see Calculation 89-078-1694M2, Revision 0, July 12,1995,
" Determination ofIn-Situ Test Capability of Millstone Unit 2 MOV's."
Test procedures for in-situ design-basis verification testing are developed using established unit and station procedures and guidelines. PI-12," Requirements for Design Basis Verification Testing,"
lists parameters which must be measured during the performance ofin-situ tests.
The test procedures contain the test methodology, controls, and specifications for initial system conditions, test limitations, necessary differential pressures and flows, and appropriate test acceptance criteria. MOV and system parameters such as motor voltage, upstream and downstream pressure, flow, and ambient temperature are documented in pre-and post test data sheets.
I
^
11.2 Extrapolation of Partial d/p Thrust Measurements Uncertainty in predicting thrust required at design-basis d/p increases as one departs from testing at 100% d/p. This is a generic issue for gate valves, and to a lesser degree globe valves. Virtually all licensees have used extrapolation, typically from 50% of design-basis d/p. The NRC has reviewed and found this practice acceptable for GL 89-10 closure." NU has also reviewed an evaluation of i
the extensive EPRI test results for gate and globe valves which validated linear extrapolation."
Published EPRI results demonstrate that the friction coefficient for stellite-on-stellite decreases with i
increasing disc-to-seat contact pressure, i.e., increasing d/p. Thus, extrapolation from low d/p should be conservative. It is possible that contact stresses become so low that data scatter becomes significant.
We are using extrapolation approaches identical to that reviewed and accepted by NRC for other licensees. The approach is incorporated in a dynamic test methodology in accordance with PI-13,
" Evaluation of Dynamic Test Results."
11.3 Load Sensitive Behavior Rate of Loading (ROL) or load-sensitive behavior, as it is also called, is the condition where torque switch trip occurs at a different thrust under dynamic conditions than during static conditions for the same torque switch setting. For example, an MOV that achieved 20,000 lbs. of thrust at torque switch trip during a static test delivers only 17,000 lbs. under dynamic conditions. This effect is normally considered as " positive" ROL, since a positive allowance is needed to ensure sufficient 33
i-Millstane Unit 2 MOV Program NovGmber 9,1995 o.
thrust under dynamic conditions. " Negative" ROL has also been observed, where mom thrust is
' delivered under dynamic conditions than static conditions. Some changes in torque as a function of loading profile may also occur. Equation 4 is used to determine ROL:
Thrustow, - Thrust,7m w
E,quation 4: ROL=
Thrust j
mu, i
l The mechanism that produces ROL is not well understood in the industry. It appears to be related to a change in stem factor brought about by changes in stem coefficient of friction as a result of stem lubrication. During gradual loading (dynamic conditions) stem lubrication is mostly in a boundary regime. During a rapid load increase (static test) some hydrodynamic lubrication appears to exist which decreases the coefficient of friction. During the past several years ROL has been the subject j
of numerous industry presentations, discussions, and experiments. ROL was examined during the i
EPRI Performance Prediction Program in an attempt to quantify it. EPRI concluded that ROL was not analytically predictable.
l ROL is accounted for by two methodologies, dependent upon control circuit logic. Testable MOV's j
are evaluated for ROL as a part of the PI-13 dynamic test evaluation. If present, the ROL will be incorporated in a revision to the thrust calculation. Both positive and negative ROL are considered.
j Positive ROL increases the minimum required thrust to close the valve while negative ROL i
decreases the maximum allowable control switch trip values.
More consideration must be given to those MOV's which are not dynamically testable. Millstone Unit 2 has 19 MOV's in this category. Of these,4 are controlled by limit switches and require no j
separate specific margin for ROL. The remaining 15 MOV's have as-left thrust values that meet a 10% margin for ROL added to their required thrust. Table 15 above (see page 26) provides the measured rate ofloading values.
For non-dynamically testable torque switch controlled valves, an additional margin (e.g., the 10%
noted above) is added to the calculated required thrust. Rather than use a representative but arbitrary
- margin allowance of 10%, we have validated this assumption by the use of ROL data obtained from 2s Millstone Unit 2 dynamic test results. We have not chosen to use multi-plant data because testing has shown that ROL is affected by the base oil viscosity of the grease used for stem lubrication and 23 lubrication practices. A statistical analysis was performed of this data. To provide a conservative evaluation of this data, a " truncated" normal distribution was used (see Figme 1, page 35). The method is well described in statistical literature.29 This method eliminates all negative ROL values.
]
His will result in a higher mean and a lower standard deviation than the use of a normal distribution.
The results of this evaluation provided a mean of 4.4% and a standard deviation of 2.7%, for a 95%
confidence level that the ROL is less than 9.0%. This ROL value is combined with other sources of uncertainty using the methods outlined in Reference 30. This method uses the mean as a margin in i
addition to all other margins, and two standard deviations are combined with the existing errors of diagnostic system accuracy and torque switch repeatability using the Square Root Sum of Squares (SRSS) method. The result is the equivalent of a " margin multiplier" slightly less than 10%,
I validating our previous 10% margin allowance.
i i-34
l i
l q,'
Millstone Unit 2 MOV Program November 9,1995
.i
[If) o Destetheates of Pastelve ROL Data Nennel Distributeen of All R L Data Figure h TruncatedNormalDistribution For MOV's that are controlled by ',imit switches, e.g., open direction, limit seating, and close torque switch bypass schemes, ROL is accounted for by the assumed stem-to-stem nut coefficient of friction. In this case, a separate margin is not added to the calculated minimum required, the margin is included in the assumption for coefficient of friction.' In this case, the validity of the assumption is verified along with the validation of coefficient of friction.
It is felt that current setup practices are sufficient to provide assurance of the ability of non-testable valves to perform their intended safety function. Conservatisms are already included in the calculation of minimum required thrusts. These include conservative valve factors, diagnostic system inaccuracy, torque switch repeatability, worst case differential pren,ure, derated motor torque, theoretical packing loads, actuator application factors, worst case undervoltage factors, and
~
stem-to-stem nut coefficient of friction.
l 11.4 Post-nfaintenance Testing Post maintenance testing and lubrication requirements are defined in PI-14," Post-Maintenance Testing and Lubrication Requirements," for MOV's which have completed a baseline set-up with diagnostic test equipment. Maintenance or modifications that affect the ability of an MOV to perform its design-basis function must be followed by a new baseline static test in accordance with GL 89-10 requirements. Listed in Table 18 are the retest requirements for various maintenance items. The Unit MOV Coordinator may modify these requirements when writtenjustification is provided to demonstrate the activity does not effect the ability of the MOV to perform it's design-basis function.
For testable valves, a dynamic test is performed at greater than or equal to 50% of design-basis differential pressure and 80% of design-basis flow conditions, following any modification which could affect the valve factor. Machining of the seat, disc or disc guiding surfaces, when not per the original design, is evaluated by engineering to determine if the baseline dynamic test is required. If plant or system conditions do not allow a dynamic test to be performed, an analyticaljustification is provided which verifies the ability of the MOV to continue to perform its required functions.
i 35
l Millston: Unit 2 MOV Program November 9,1995 i
1 b
Table 18: Post-Maintenance Ratest Requirements Maintenance Activity l Test l Comments i
Packin0 Replacement l X l A P3500 test, complete VOTES Test, calculatson, or other means.
)
Packing Adjustment l X l A P3500 test, complete VOTES Test, calculation, or other means.
l Valve Disassembly X
Dynamic test should be performed following maintenance or 4
modification of the disk, seats, or guides. If plant or system j
conditions do not allow a dynamic test to be performed, provide an analyticaljustification to verify the ability of the MOV to continue to 4
i perform its mquired functione.
Cleaning and Re-lubricating Valve Grease or other approved lubncant shall be applied so that all ste.Ti urfaces that come in contact with the stem nut are well coated.
Stem i
Replace Valve X
1 Tor Switch Removal X
j To e Switch Ad stment X
l 4
Motor rator Disassem
)
' Pack Removal i
Pack R lacement X
Pack A ustment X
Stem-Nut Removal X
i Motor Starter Contactor Replacement X
VOTES test is not required if contactor dropout time can be snown to be at or below that determined from the previous VOTES test.
l Motor Replacement (i.e. new motor)
X Venfy correct wirirn and motor rotation.
l i
i Umst Sivitch Removal '
Correct winng must be venfied and limit Limit Switch Re lacement switch settings adjusted in accordance with l
Limit Switch Adjustment approved procedures.
i Replace any Gears X
Baseline test for gear ratio changes or springpack removal. Static
{
retest not required if gear ratio unchanged and only motor pinion I j
worm shaft ars were removed and replaced with identical parts.
5 Re lace an Beann s X
l Replace Declutch Shaft X
Handwheel Assembly Removed X
SMB-00 and SMB-000 on! )
Motor Removal (gear box not removed)
Venfy correct winng and motor rotation.
l Replace actuator to-yoke or yoke-to-X Retest not required if replaced one at a time in accordance with bonnet bolts / studs published guidance."
l
- 12. Diagnostic Test Equipment Accuracy i
i l
12.1 GL 89-10 Supplement 5 l
On October 2,1992, Liberty Technologies, manufacturer of the VOTES system used at NU, issued a l
10 CFR Part 21 notification regarding potential inaccuracies in thrust measurements made with
{
VOTES. On June 28,1993, the NRC issued Supplement 5 to inform licensees of a generic concern regarding the accuracy of MOV diagnostic equipment. Liberty Technologies determined that two l
new factors can affect the thrust values obtained with its VOTES equipment. Those factors involve:
(1) the stem material constants, and (2) the failure to account for a torque effect when the equipment l
is calibrated by measuring strain of the threaded portion of a valve stem. The Supplement requested that the licensee evaluate this new information and any other information reasonably available to i
them and provide a written response to two requests for additional information. NU provided the j
additional information in a letter dated October 14,1993.32 36 n
. a,e e-n-
.,,,. ~,..
~_
Millstone Unit 2 MOV Program November 9,1995
)
NU uses Liberty Technologies VOTES diagnostic test equipment to confirm and maintain GL 89-10 MOV torque switch and / or limit switch settings. NU also uses VOTES 2.31 software, which automatically calculates the torque correction factor (TCF), which accounts for the VOTES Part 21
_ thrust under prediction measurement inaccuracy. The following is a summary of the actions taken to address the diagnostic test equipment accuracy concern:
(1) The Millstone Unit 2 performed VOTES thrust underprediction evaluations on July 16,1993. This effort corrected as-left measured thrust values. Intemal reportability evaluations were issued to address potential valve structural over-thrusts which were successfully resolved and the valves were deemed operable.
(2) NU's Engineering Department verified that all MOV measured thrust values were proper and valid.
(3) CYAPCO and NNECO's Engineering Department instituted VOTES Part 21 thrust under-prediction corrections for all MOV thrust window calculations completed after January 1,1993. Thrust windows incorporate the Liberty Technologies VOTES accuracy adjustment or TCF in their combined accuracy determinations. All VOTES diagnostic test systems now utilize Version 2.31 software, which automatically determines TCF. All VOTES test personnel are properly trained in the use of the 2.31 software.
(4) CYAPCO and NNECO revised the MOV Program Manual stem thrust procedure to incorporate Liberty Technologies VOTES system TCF accuracy corrections.
All program thrust calculations automatically address VOTES measurement and system accuracies.
(5) No Millstone Unit 2 valves exhibited an over-thrust condition, due to the application of the VOTES Part 21 correction.
(6) NNECO identified and evaluated historical VOTES tests to determine if previous operating thrust setups were higher and determine if cumulative fatigue is a concem. Our evaluation corrected as-left thrust values and resulted in further evaluations to address potential valve structural over-thrusts. If necessary, a detailed structural analysis was used to increase the valve's nominal thrust to greater than the over-thrust value and, subsequently, the valves were deemed operable. Detailed structural analysis for the over-thrusted valves revised the allowable design thrust. The revised thrust value for unlimited cycles exceeds the maximum thrust developed during past operation, when the thrust was under-predicted.
12.2 Diagnostic Test Equipment Requirements PI-15," Requirements for Test Equipment," establishes the requirements and optional parameters to be measured by MOV diagnostic test equipment. As a minimum, diagnostic test equipment will have the capability of measuring and recording the following parameters:
Stem Thrust - measured or calculated in both the opening and closing directions.
Stem Torque - measured in both the opening and closing directions (VTC is closed only).
Limit, Bypass, and Torque Switch Actuation 9
- Motor Current Voltage 37
i Millstone Unit 2 MOV Program November 9,1995 PI-15 specifies diagnostic test equipment calibration and system accuracy requirements. In addition, it provides general guidelines for test equipment associated with the NU MOV Program. Typically, systems and components are used from Teledyne Brown Engineering (QSS), Liberty Technologies (VOTES, STS - stem torque sensors), and calibrated strain gages. Millstone Unit 2 uses the VOTES diagnostic equipment to set the torque switches and perform diagnostic evaluations for MOV's in the GL 89-10 program.
12.2.1 Determining Accuracies Minimum and maximum thrust requirements include margin for MOV test equipment accuracies as summarized in Table 19, with additional discussion below. These margins are combined using the square root of the sum of the squares method.
J Table 19: Test Equipment Accuracy Matrix Parameter Accuracy VOTES Diagnostic Test Equipment Close: 29% x TCF Open:i10% x TCF Teledyne Quick Stem Sensor (Torque and Thrust) t9.8%
Limitorque Torque Switch Settings above #1 and 5 50 ft-lbs at TST t 1G%
Limitorque Torque Switch Settings above #1 and > 50 ft-lbs at TST 2 5%
Limitorque Torque Switch Settings at #1 and > 50 ft-lbs at TST 210%
Limitorque Torque Switch Settings at #1 and 5 50 ft-ibs at TST t 20%
A diagnostic test equipment (e.g., VOTES) closed accuracy of 9% x Torque Correction Factor (TCF) and open accuracy of 10% x TCF is assumed for the purpose of target thrust calculations based on Curve Fit Accuracy (CFA) calibration for the VOTES software, unless the testing is done outside the bounds of the Liberty assumptions. If outside the bounds, we contact Liberty to obtain the correct values. In cases where Best Fit Straight Line (BFSL) calibrations must be utilized, if the Regression Coefficient (RSQ) value is less than 0.997, the target thrust is recalculated to account for the difference in accuracy obtained via the CFA and BFSL methods.
The actual diagnostic test equipment accuracy used in post-diagnostic test analysis is taken from the calibration results obtained during perfonnance of station specific procedures or the test equipment vendor manual, as appropriate. The calibration process may require technical guidance from the test equipment manufacturer to account for local physical variations or particular valve installations.
Any pressure measuring devices, permanent or temporary, used for determining system differential or line pressure during diagnostic testing have a minimum accuracy of* 2% of the full scale reading.
The pre-diagnostic test analysis assumes a
- 2% pressure instrument accuracy.
Based upon Limitorque specifications, the actual torque output for a given torque switch setting is repeatable within the values specified in Table 19. This repeatability of actuator output is applied to the allowable thrust / torque at torque switch trip as well as to the total allowable torque / thrust value which includes inertial effects after contactor dropout and minimum available thrust. The measured test values are compared to these adjusted limits.
12.2.2 Applying Accuracies Diagnostic and test equipment accuracy factors are applied in a conservative manner to the calculated allowsbles and / or measured torque and thrust values, as appropriate. The overall accuracy which is applied to the MOV thrust and torque values will be the square root of the sum of the squares of the torque switch repeatability accuracy and diagnostic equipment accuracy.
38
l Millstone Unit 2 MOV Program November 9,1995 Pressure instrument (gages or transducers) accuracy factors are applied directly to the appropriate calibration range of the pressure instrument (e.g., percentage of full scale reading, percentage of reading, etc.) and added or subtracted to the measured test pressure in accordance with PI-13. It is important to note that pressure instrument accuracies are independent of the actual reading since they are a function of the full scale reading for a given instrument, unless the accuracy is expressed as a
~
percent of reading. If pressure transducers are used it is important to use the total loop accuracy to the point where the data is being used. Corrections for elevation-head differences between installed or temporary pressure instruments and the valve are applied in accordance with PI-13 for dynamic test evaluations.
Any other combination of independent accuracy factors will be compiled using the square root of the sum of the squares method.
12.2.3 Limit Switch Repeatability The objective of the analysis " Millstone Unit 2 Repeatability Statistical Evaluation,"25was to determine, at the 95 / 95 probability / confidence level, the repeatability of the limit switches for the Millstone Unit Two feedwater valve's closure from tests conducted at the site on October 6,1993.
The time from applying power to the motor on the MOV to the time when the limit switch was activated was measured on all four valves: 2-FW-38A,2-FW-38B,2-FW-42A and 2-FW-42B. In audition, valve closure tests were performed on 1-MS 5 at Millstone Unit One on March 16,1994.
Each of the four feedwater (FW) valves were subjected to five test runs of the valve motor until the limit switch was activated. The results of these tests consisted of times to closure and were recorded.
In addition, ten test runs of the valve motor were performed on 1-MS-5. The test results were recorded.
It is assumed that each measured valve closure time constitutes a random value from the population of all measurements. Sequential measurements on a valve are also assumed to be statistically independent and unbiased. The calculation method consisted of a sequence of steps:
- 1. The measurements for each valve were adjusted (transformed) by their respective mean values.
- 2. Basic statistics were determined for the adjusted data.
- 3. The W-test was applied to verify that the data can be characterized by a normal distribution (Millstone Unit 2 data only).
- 4. Two-sided 95/95 probability / confidence values for the adjusted valve closure times were determined.
- 5. The repeatability error for motor operated valve closure times was then established by transforming the 95/95 values for adjusted valve closure times back to the original (pre-adjusted) times.
The most adverse 95/95 closure time for the five valves was used to specify the repeatability error as a percent of average closure time. The calculation concluded that the Millstone Unit One valve was bounded by a limit switch repeatability 10.2% and the Millstone Unit Two valves were bounded by a10.5% limit switch repeatability.
39
Millstone Unit 2 MOV Program N:vember 9,1995
- ~
I I
- 13. Grouping In GL 89-10 and its supplements, the NRC staff requested that licensees test each MOV under design-basis differential pressure and flow conditions where practicable. However, the staff recognized that it is not practicable to test each MOV within the scope of GL 89-10 in-situ dynamic conditions. Therefore, if a licensee does not perform prototype testing at a test facility for each MOV that is not practicable to test in situ, the licensee will have to group MOV's that are not practicable to test in a manner that provides adequate confidence that the MOV's are capable of performing their design-basis function.
The staff continues to recommend testing MOV's under design-basis conditions where practicable.
i Paragraph I of GL 89-10 allows licensees to propose alternatives to the recommendations of the generic letter wherejustification is provided. Grouping data from design-basis differential pressure testing of similar MOV's at or near design-basis test conditions is an acceptable option to establish design-basis valve setup conditions.
Grouping of MOV's is performed in accordance with the requirements of GL 89-10 Supplement 6 as summarized below: identical valve design ( the valves must either be ofidentical design orjustified identical in design by performing a detailed analysis including consideration ofinternal dimensions and clearances), representative (but not similar) operating conditions, the MOV's have similar installation conditions and orientation, the adequacy of the valve design has been verified through review ofindustry and plant specific data, and number of times the valve is stroked during an operating cycle.
Dynamic testing shall be performed on at least two MOV's from a group or 30% of the group (round up to the next high number of valves when taking percentages), whichever is greater. Dynamic testing need not be performed on the remaining MOV's in the group for GL 89-10 closure.
Grouping analysis methodology is contained in PI-11. The valves exempted from dynamic testing meet the requirements of PI-11, Section 3.4; GL 89-10, Supplement 6 for excluding testable valves from dynamic testing; and the following guidelines for grouped valves:
Industry or plant specific data shows that valves in this group can perform their intended e
function.
At least two (2) and no less than 30% of the number of valves in the group will be tested at or near DB conditions.
All valves in the group have been statically tested.
Valves in same group with higher priority, least margin, or greatest safety e
significance have been dynamically tested.
The MOV's have similar installation conditions and orientations.
Vale designs are the same or similar.
e Adverce performance results were reviewed for applicability to all MOV's in the group.
Valve maintenance histories were reviewed to determine if valve internals are in the e
same condition.
Millstone Unit 2 MOV's which were grouped are indicated in Table 8.
i-40
Millstone Unit 2 MOV Program November 9,1995 o o
- 14. Periodic Verification i
14.1 Philosophy
\\
The purpose of GL 89-10 was to ensure that safety related MOV's are operable, and to the extent practical this has been verified by testing the MOV's at conditions representative of their design-basis function. The unit's licensing basis requires that these valves are operable and be maintained as operable after the closure of the design-basis verification phase of GL 89-10. There needs to bc high confidence that degradation will not occur so as to erode margin or in some way render the MOV inoperable.
Item j. of GL 89-10 speaks of the need to verify "MOV switch settings because of the effects of wear or aging" (Item d.). In Item j., the licensee is requested to perform periodic testing with surveillance intervals " based upon the licensee's evaluation of the safety importance of each MOV as well as its maintenance and performance history. The surveillance interval should not exceed five years or three outages, whichever is longer, unless a longer interval can bejustified for my particular MOV."
Millstone Unit 2, through implementation of the NU MOV Program, is comnutted to maintaining these safety-related MOV's operable in accordance with our MOV Program 'equirements as specified in our MOV Program Manual. Periodic testing can include static, dynamic, and motor current tests, or other acceptable diagnostic test methods. NU believes that static tests are fully effective in detecting degradation, except where valve internals have been modified or somehow degraded. We are aware that issues still exist as to the need to periodically dynamically test GL 89-10 MOV's. This was responsively considered in our approach to periodic testing (see Section 14.3).
14.2 Determination and Maintenance of Correct Switch Settings item d. of GL 89-10 requires licensees to prepare or revise procedures to ensure that correct switch settings are determined and maintained throughout the life of the plant. PI-8," Control of MOV Settings," establishes the methodology for controlling changes to maximum and minimum thrust and torque settings, limiter plate sizes, limit switch setpoints, and thermal overload heater settings.
NGP 6.10,"Use of the PMMS Data Base to Indicate Quality Assurance or Special Program Applicability," provides methods for identifying which nuclear plant components have special program requirements. All MOV's within the scope of the Millstone Unit 2 MOV Program are included in a "special programs" PMMS screen. This action will provide a mechanism for identifying components which have special MOV Program requirements during the generation of Automated Work Orders or system reviews. This effort integrates the MOV Program as an element of the NU Configuration Management Program to help maintain the configuration management of MOV switch settings.
PEP Action Plan 2.3.2," Design Control Manual," has been established to redesign the design control process at Northeast Utilities. 'Ihis effort is integrated with PEP Action Plans 2.3.1," Configuration Management," and 2.3.3," Engineering Programs." The Design Control Manual will provide a mechanism for ensunng that MOV design requirements are maintained.
14.3 Position on Periodic Testing (Post Closure)
The MOV Program approach to periodic testing of GL 89-10 MOV's is as follows:
41
Millstone Unit 2 MOV Program November 9,1995
- 1. Post-Maintenance Testing His will be performed as required by PI-14," Post-Maintenance Testing Requirements," which addresses the need for both static and dynamic testing.
- 2. Trending This is described in PI-16,"MOV Tracking and Trending Program." His PI will be enhanced by a revision to specify trending requirements in even greater detail. We consider the use of static diagnostic testing to be the core of an effective periodic testing program. It allows detection of anomalies and / or early indication of degradation. Periodic static testing will be performed on all GL 89-10 MOV's.
Frequency of periodic static testing will be based on the PRA ranking, with the MOV's being divided into two groups. Priority I will consist of MOV's with a "very high" or "high" PRA ranking. Priority 2 will consist of MOV's with a " medium" or " low" PRA ranking. The definition of"very high","high", etc. is as defined by NU's Safety Analysis Branch.
The frequency of testing will be:
Priority 1: Every three outages or five years, whichever is greater.
Priority 2: Every six outages or ten years, whichever is greater.
Grouping will also be employed to optimize the tested population.
- 3. Periodic Dynamic Testing Plans for periodic dynamic testing of Millstone Unit 2 MOV's will be developed following issuance of the recently announced NRC generic letter on periodic testing.
Millstone Unit 2 will be reviewing valves with low (but acceptable) margin as potential candidates for either reclassification from periodic testing category Priority 2 to 1, or to have their torque switch settings increased at the next convenient opportunity, as appropriate.
- 15. Trend and Analyze MOV Failures 15.1 Tracking and Trending Requirements Item h. of GL 89-10 requires that each MOV failure and corrective action taken, including repair, alteration, analysis, test, and surveillance, should be analyzed orjustified and documented. The documentation should include the results and history of each as-found deteriorated condition, malfunction, test, inspection, analysis, repair, or alteration. PI-16,"MOV Tracking and Trending Program," establishes the tracking and trending requirements for the NU MOV Program. PI-16 requires that each MOV failure and corrective action taren, including any repair or alteration, shall be entered into the NPRDS data for their units to identify any trends.
42
Millstoro Unit 2 MOV Program Nov:mber 9,1995 All corrective work on MOV's is performed through the work request process. Procedures describe the method for documenting failures or nonconforming conditions that occur during operation, testing, or maintenance. Depending on the particular failure or deteriorated condition, follow-up
_ action may include:
- Generation of a Adverse Condition Report (ACR), which replaced Plant Incident Report (PIR).
Performance of a Root Cause Determination (RCD).
Notification under the Nuclear Plant Reliability Data System (NPRDS).
e Generation of an additional work package (s) for follow-up or corrective e
maintenance.
15.2 Diagnostic Parameter Trending MOV performance is trended to ensure that switch settings remain adequate for a given MOV throughout the life of the unit. PI-16 provides guidance on the collection of as-found testing and the collection of diagnostic test data for trending. The following performance parameters shall be trended:
Motor running current and supply voltage at the MCC or at the motor.
Measured maximum thrust or torque (whichever parameter is used for " baseline") at close torque switch trip and running average.
Power factor (if found to be a quantitative parameter, otherwise motor power should be trended).
Torque switch settings.
Valve stroke time is monitored and trended by existing nuclear unit In-Service Test (IST) Programs and will not be trended by the NU MOV Program. Our program should provide sufficient data to identify degraded MOV performance. During RFO 11 (1992) all 52 valves had baseline static tests performed and, effectively,17 valves had baseline dynamic tests performed, including grouped valves. As-found static tests were performed on seven valves during RFO 12 (1994 - 1995).
15.3 MOVFailure Trending Using NPRDS The NPRDS system will be used to assist in root cause investigations of MOV failures. At least once every refueling cycle (i.e., every two years or after each refueling outage), a Component Failure Analysis Report (CFAR) will be generated from the NPRDS data on record for Millstone Unit 2 to identify trends related to MOV operability as a function of the failures reported in the nuclear industry. This effort will assist in determining areas for programmatic improvement.
43
1 l
Millstone Unit 2 MOV Program November 9,1995 j
- 16. Pressure Locking and Thermal Binding 16.1 NRC Position
~
ne NRC Office for Analysis and Evaluation of Operational Data (AEOD) completed AEOD Special Study AEOD/S92-07 (December 1992)," Pressure Locking and Rennal Binding of Gate Valves."
l The stafrissued the AEOD report in NUREG-1275, Volume 9 (March 1993)," Operating Experience Feedback Report Pressure Locking and Thermal Binding of Gate Valves." In its report, AEOD concluded that licensees had not taken sufficient action to provide assurance that pressure locking and thermal binding will not prevent a gate valve from performing its safety function.
{
A memorandum dated December 20,1993, from James T. Wiggins, Acting Director, Division of Engineering, NRR, to the Regions provided guidance on the evaluation oflicensee activities to address pressure locking and thermal binding of gate valves. Supplement 6 to GL 89-10, dated March 4,1994, provided information on the consideration of pressure locking and thermal binding of gate valves. Finally, on August 17,1995, NRR issued GL 95-07," Pressure Locking and Thermal Binding of Safety-Related Power-Operated Gate Valves."
The NRC regulations require that licensees design safety-related systems to provide assurance that those systems can perform their safety functions. In GL 89-10, the staff requested licensees to j
review the design bases of their safety-related MOV's. In complying with the NRC regulations,"...
licensees are expected to have evaluated the potential for pressure locking and thermal binding of gate valves and taken action to ensure that these phenomena do not affect the capability of MOV's to
)
perform their safety-related functions. If a licensee identifies a potential for pressure locking and i
thermal binding of gate valves, the NRC regulations require that the licensee take action to resolve l
that problem."
16.2 PLTB Evaluation
\\
l The initial review of the potential for pressure locking and thermal binding of gate valves at Millstone Unit 2 was performed by Stone and Webster Engineering Corporation (SWEC) in 1990.3'
)
Stone and Webster performed similar evaluations for the other Millstone Units and Haddam Neck.
During an NRC evaluation of the GL 89-10 Program at Millstone Unit 1, the NRC reviewed the 35 SWEC report, and identified potential deficiencies with the evaluation and questioned the following assumptions:
Excluding steam system valves from the evaluation for pressure locking, Excluding valves below 200 F for thermal binding and below 150 psi for pressure e
locking.
Since the same assumptions were used in the Millstone Unit 2 evaluation, the SWEC evaluation was revisited. During the re-evaluation, the following Adverse Condition Reports (ACR's) were initiated when there were indications of PLTB concerns with GL 89-10 MOVs: ACR's 00535 (3/28/95),
00934 (3/17/95),02058 (6/7/95),03071 (6/13/95),03072 (6/13/95),03441 (6/28/95), and 03458 (6/28/95).
44
e Millstone Unit 2 MOV Program November 9,1995 i
All ACRs were dispositioned with all of the subject valves found to be operable. Final evaluations were performed in accordance with PI-20,"MOV Program Pressure Locking and nermal Binding j
Evaluation", and documented in calculation 89-078-1192M2, Revision 0,"MP2 - MOV Pressure Locking and nermal Binding - PI-20 Evaluations", Rev. O with Calculation Change Notices 1,2, and 3, June 27,1995.
16.2.1 Evaluation Criteria 2
ne following criteria were used to determine if a GL 89-10 valve is susceptible to either pressure locking or thermal binding:36 Pressure locking and thermal binding is only applicable to gate valves. Any valve that is not a gate valve is excluded from any further evaluation for susceptibility to pressure locking or thermal binding.
Pressure locking and / or thermal binding of a gate valve is only a safety concern i
when the valve is closed and the valve is required to open to perform its safety i
function. Valves that are normally open and must only be closed to perform their safety function are not required to be evaluated for pressure locking or thermal binding.
Double-disc parallel-seat gate valves are not subject to thermal binding due to their disc design. The wedging mechanism between the double discs collapses as the stem rises. This permits the parallel discs to move inward and be raised regardless of the change in system temperature.
Solid wedge gate valves are not subject to pressure locking since the disc does not e
contain a cavity at the seating surfaces that can be pressurized, and simultaneous leak tightness of both disc sealing surfaces cannot be reliably achieved.
Gate valves that perform non-design-basis event opening for recovery from mispositioning only are excluded from this evaluation.
16.2.2 Evaluation Method Utilizing the above criteria, each of the valves in the GL 89-10 program have been screened for susceptibility to pressure locking and thermal binding. No further evaluation was required for valves eliminated based on one of the above screening criteria. For each valve that was not eliminated as a result of the screening, the following evaluation method was used:
The expected range of upstream and downstream operating conditions was established.
Each stroke in the Design Basis Review (DBR) calculation where the valve is required to open from the full closed position was reviewed to determine if the conditions necessary to cause pressure locking or thermal binding of the disc exist during that stroke. Recovery from mispositioning strokes were not included in this review.
The surveillance procedures that affect these valves were reviewed to determine if the surveillance procedure established the conditions that could result in pressure locking or thermal binding of the valve.
45
Millstone Unit 2 MOV Program November 9,1995 l
'a De following are the conditions that must occur before the valve is required to open for pressure locking or thermal binding to potentially exist:
Hermal binding of a valve could occur if a valve is closed when hot and then cools e
down appreciably before it is required to open. PI-20,"MOV Program Pressure f
Locking and Hermal Binding Evaluation," provided the temperature changes for evaluation. De valve body and seats contract a greater amount than the disc causing the seats to bind the disc more tightly, increasing the force required to open the valve, possibly exceeding the capabilities of the motor operator, Pressure locking could occur if a valve is closed in a system that operates at pressure e
or is pressurized. He bonnet cavity and the area between the valve discs fill with
.i pressurized water, equalizing with system pressure over time. Subsequently, before the valve is required to open, the system pressure drops and the higher pressure fluid is trapped in the bonnet area and the area between the valve discs. The pressurized fluid forces the discs closed even tighter, trapping the pressurized fluid and preventing it from leaking by the discs. When the valve is required to open, the extra force required to open the valve due to the discs being pressed against the valve seats could potentially exceed the capability of the motor operator.
Pressure locking could occur if a valve is closed in a system that is normally filled and slightly pressurized. The bonnet cavity and the area between the valve discs fill with water, equalizing with line pressure over time. (Note that the head of water from a filled tank can provide enough pressure to fill the valve internals.)
Subsequently, before opening, the valve is heated by hotter fluid on either side of the valve disc or by an external heat source. Heating of the water in the bonnet and disc J
cavity results in the thermal expansion of the trapped fluid, increasing the pressure seating the valve discs against the seats. When the valve is required to open, the extra force required to open the valve due to the discs being pressed against the valve seats could potentially exceed the capability of the motor operator.
16.3 Evaluation Results For each valve opening stroke or surveillance procedure where the potential for either pressure locking or thermal binding exists, the corrective actions taken to preclude it from occurring are identified. The results / conclusions and corrective actions are summarized in Table 20.
46
Millston) Unit 2 MOV Program November 9,1995 l
l
(
i j
Table 20: Pressure Locking (PL) / Thermal Binding (TB) Summary Valve Valve Wedge susceptiene l Accon l
Number Type Design PL TB l l
l
~
2-CH-429 Gate Solid No No l l
I 2-CH-501 Gate Flex No No l No open safety functe, normally open l
l 2-CH-504 Gate Flex No No l l
il' 2-CH-508 Gate Flex No No l l
2-CH-509 Gate Flex No No l l
2 2-CH-514 Gate Flex No No l l
1 2-CS-04.1 A Gate Parallel Disc No No l l
)
2-CS-04.1 B Gate Parallel Disc No No l l
l 2-CS-13.1 A Gate Parallei Dec No No l No open safety funchon, normally open l
t 2-CS-13.1B Gate Parallel Disc No No l No open safety function, normally open l
j 2-CS-16.1 A Gate Parallel Osc Yes No l Analysis Performed to Justify Design Resolution l 2-CS-16.18 Gate Parallel Dec Yes No l and Procedure initiated to Address PL l
l 2-FW-38A Gate Flex No No l No open safety function, normally open l
l 2-FW-38B Gate Flex No No l No open safety funchon, normally open l
2-FW-42A Gate Flex No No l No open safety funchon, normally open l
4 2-FW428 Gate Flex No No l No open safety function, normally open l
I 2-FW-44 Gate Flex No No No s
function, norma n
2-MS45A Globe N/A No No 2-MS45B Globe N/A No No l
2-MS-201 Gate -
Flex No Yes Procedural Change 2-MS-202 Gate Flex No Yes lProceduralChange l
2-RB-30.1 A Gate Flex No No l No open safety funchon, normally open l
1 2-RB-30.1B Gate Flex No No l No open safety function, normally open l
I 2-RB-37.2A Gate Flex No No l No open safety function, normally open l
l 2-RB-37.2B Gate Flex No No l No open safety function, normally open l
l-2-RC-403 Gate Flex No Yes l Procedural Change l
i 2-RC-405 Gate Flex No Yes l Procedural Change l
}
2-SI-411 Gate Parallel Disc No No l l
2-SI-412 Gate Parallel Disc No No l 2-S1414 Gate Flex No No N n safe function, norm n
2-Sl415 Globe N/A No No
{
WWYT No i
i
~2-SI-624 Gate Flex No N
afe funchon, norm n
2-Sl425 Globe N/A No No
[
2-St-626 Globe N/A No No i
l' 2-SI-627 Globe N/A No No l
2-SI-634 Gate Flex No No n safe ion, normal n
i 2-Sl435 Globe N/A No No j
2-St-636 Globe N/A No No 2-Sl444 Gate Flex No N
safe nction, normal n
2-Sl445 Globe N/A No No i
2-Sl446 Globe N/A No No 2-Sl451 Gate Flex Yes Yes Procedural Change for TB and 1
2-Sl452 Gate Flex No Yes l Design Modification for PL 2-Sl453 Gate Flex No No l l
2-Si454 Gate Flex No No l No open safety funchon, normally open l
2-Sl455 Gate Flex No No l l
2-Sl456 Gate Flex No No No n safet funcbon, normall n
2-SV-4188 Globe N/A No No f
4 i
i 47 men-
,~ -.
Millstone Unit 2 MOV Program November 9,1995 The NRC regulations require an analysis under 10 CFR 50.59 for any valve modifications and establishment of adequate post-modification and in-service testing of any valves installed as part of the modification. For example, the licensee would have to evaluate the effects of drilling the hole in the disk if used to resolve a pressure locking concern. One consideration in this evaluation is the fact that the MOV will be leaktight in only one direction.
If an MOV is found to be susceptible to pressure locking or thermal binding and the licensee relies on the capability of the MOV to overcome pressure locking or thermal binding, the staff will review the licensee justification during inspections in consideration of the uncertainties surrounding the prediction of the required thrust to overcome these phenomena. If the staff finds that a licensee has not adequately addressed the potential for pressure locking and thermal binding of gate valves, enforcement actions and schedules for response will depend on the safety significance of the issue at the plant. At Millstone Unit 2 initial modifications were made to two valves: 2-CS-16.l A and 2-CS-16.lB. Subsequent leakage concerns required reversal of this modification and an evaluation was performed which demonstrated the MOV's capability to overcome pressure locking."
- 17. Industry Information NRC information notices, industry technical and reaintenance updates, and 10 CFR Part 21 notices are entered into our mainframe-based Action Item Tracking and Trending System (AITTS) computer database. The assignments, due dates, required response, and resultant action can be reviewed by any individual with access to a computer.
- 18. Program Schedule In a letter dated June 28,1989,' the NRC Staffissued Generic Letter 89-10," Safety-Related Motor-Operated Valve Testing and Surveillance." The letter required each licensee with an operating license to complete all design-basis reviews, analyses, verifications, tests, and inspections instituted to comply with GL 89-10 within five years or three refueling outages of the date of the letter, whichever was later. The required documentation had to be available within one year or one refueling outage of the date of the letter, whichever was later. The documents should include the description and schedule for the design-basis review recommended in item a. (including guidance from item e.) for all safety-related MOV's and position-changeable MOV's as described, and the program description and schedule for items b. through h. for all safety-related MOV's and position-changeable MOV's.
j Northeast Utilities certified in a letter dated December 15,1989,38 that they were "... developing detailed programs for addressing Generic Letter 89-10 at the Millstone Unit 2 Plant...", and that the
"... programs will encompass the guidance as detailed in the Generic Letter." The proposed schedule for Millstone Unit 2, with the program defined by January 1991 and the program completed within three refueling outages (1994).
In a letter dated August 3,1990', the NRC Staffissued Supplement 2 to GL 89-10. In thh letter, the NRC staff stated that licensees were not required to have their respective program descriptions in place until at least January 1,1991. Northeast Utilities informed the NRC in a letter dated May 4, 1992", that they did not fully comply with their commitments to develop program descriptions by April 1991. This conclusion was based upon an audit, part of a routine in-house Quality Services self-assessment, which determined that in-place program descriptions for addressing GL 89-10 did 48
Millstone Unit 2 MOV Program Nov:mber 9,1995 not contain all of the necessary technical elements specified in GL 89-10. Northeast Utilities then stated that they "... plan to have the program descriptions completed by the end of 1992." This commitment was met with the release of the Motor Operated Valve Program Manual on December 18,1992.
In a letter dated December 13,1993," Northeast Utilities provided the NRC with an updated schedule for completion of testing at the third refueling outage. This change represented a change in the Millstone Unit 2 date for the third refueling. The GL 89-10 MOV Program was completed at Millstone Unit 2 within three refueling outages after the date of the GL 89-10 letter. Additionally, documentation was provided to the NRC Staff within 30 days following the completion of the third refueling outage. Therefore, Millstone Unit 2 has met all schedule commitments with respect to GL 89-10 requirements.
- 19. Quality Assurance Item f. of GL 89 10 requires that documentation of explanations and a description of the actual test methods used for accomplishing design-basis verification testing be retained. Calculations associated with design-basis reviews and development ofin-situ testing are performed in accordance with Nuclear Group Procedures (NGP) 5.05," Design Inputs, Design Verification, and Design Interface Reviews," and NGP 5.06," Design Analyses and Calculations." All MOV Program records and test procedures are retained in accordance with NGP 2.13," Nuclear Plant Records Program."
NU developed Motor-Operated Valve Engineering Program Plan, Revision 1, dated July 16,1992, to address the recommended actions of GL 89-10. The documents that implement this plan are the Motor-Operated Valve Program Manual and its Program Instructions. Based on the results of an i
intemal audit, NU recognized that they were behind schedule in meeting their prior commitment to develop a GL 89-10 MOV Program Description for Millstone Unit 2 by April 1991. Management j
took action to correct this problem by assigning lead responsibility for MOV program development to the systems engineering group. To complete this effort, NU used contractor assistance to prepare the MOV Program Instructions, differential pressure test procedures and other related documents.
Northeast Utilities committed to have the Motor-Operated Valve Program Manual in place by December 31,1992, and they completed this effort on December 18,1992.
- 20. Audits / Inspections We performed a self-assessment of our MOV Program from June 14-25,1993, following a meeting with Region I and NRR staff on May 20,1993, where we proposed our plan to do a self-assessment at the Millstone Nuclear Power Station and documented by letter, dated June 4,1993. Region I authorized our self-assessment in lieu of the NRC inspection mandated by NRC Temporary Instruction 2515/109. NRC inspectors monitored the self assessment and found that the findings were equivalent to those that would have been identified by an NRC team. He self-assessment was conducted for the three Millstone units. The findings were significant, proper emphasis was placed on the importance of the items, and disposition of each finding was adequately addressed.
49
- ..ae*
Millstone Unit 2 MOV Program Novtmber 9,1995
- 21. Training PI-17," Qualification of Personnel," establishes MOV Program training and personnel qualification requirements based on position and functional assignments. Departmental training requirements for Nuclear Group personnel are governed by NGP 2.26," Departmental Training." All personnel performing maintenance and / or testing on MOV's are required to attend and satisfactorily complete the necessary training courses. Supervisors evaluate each individual's competence and previous MOV experience to determine an individual's qualification to perform work. De Nuclear Training Department provides VOTES and MOV technical training for nuclear unit department personnel.
Millstone Unit 2's MOV training program has been accredited by the Institute of Nuclear Power Operations. It outlines the specific requirements as well as continuing and refresher training for various technicians and engineers. His program includes both classroom knowledge and hands-on laboratory skill development. Numerous types of MOV hardware are used as training aids at the NU training facility. VOTES equipment is borrowed from Generation Test Services for training and returned for actual work at the unit.
Each instructor has an individual training folder which contains qualifying documentation covering the background and qualifications of the instructor. NRC discussions with the training staff regarding MOV issues verified that they were knowledgeable and experienced. The Nuclear Training Department staff check and validate contractor training by examination requiring an 80%
on a written test and a display of proficiency in the laboratory before being allowed to assist qualified personnel from Millstone Unit 2 or Generation Test Services.
j The Nuclear Training Depart ent maintains a matrix of all qualified personnel in each department and distributus this information to department heads periodically. After completion of the reqaired MOV training the department head qualifies the trainee with applicablejob related training. The completed m ming information is sent to the Nuclear Training Department to update the matrix with a qualificatica status and a date for requalification. Required training updates are designated on the matrix te signify when new elements of training are required.
The Training Program Control Committee reviews regulatory and industry documents to determine f
their applicability to the licensee's MOV program. Representatives from training and maintenance j
meet periodically to discuss training modifications based on any new industry or vendor information.
- 22. MP2 Cycle 13 Test Scope (Preliminary) 1 Provided in Table 21 is a preliminary summary of future MOV monitoring activities and retests in addition to periodic testing.
Table 21: Cycle 13 Monitoring / Test Scope Valve Static Test Dynamic Test Comments 2-CH-504 X
Current As-Left Open Stroke Out of Cakbration 2-CH-514 X
Current As-Left Open Stroke Out of Cahbration 2-FW-38A X
Current As-Left Open Stroke Out of Cakbration 2-FW-38t3 X
Current As-Left Open Stroke Out of Cahbration 2-FW-42B X
Current As-Left Open Stroke Out of Cahbration 2-R B-30.1 A X
Current As-Left Open Stroke Out of Cahbration 2-RB-37.2A X
Current As-Left Open Stroke Out of Cahbration 2-SI-655 X
Current As-Left Open Stroke Out of Cahbration 50
- g"**
Millstone Unit 2 MOV Program November 9,1995
- 23. Status of GL 89-10 Inspection Findings NU extensively modified its position on gate valve factors in December,1993 in response to the release of the EPRI PPM test data and the issuance of NRC Information Notice 93-88." His position which was documented in January 1994 has remained unchanged." The memo provided requirements for operability and design setup for both testable and non-testable gate valves.
Validation of these valve factor criteria is required as part of design basis closure of GL 89-10. The need tojustify these values was reaffinned in the July 12,1994,"Sheron memo".
The approach for dynamically testable valves has been to validate Vf's used for design setup by dynamic testing with appropriate allowances for uncertainties and extrapolation. For non-testable valves, validation is provided using the EPRI developed Performance Prediction Methodology (PPM).'" Due to the extensive delay in the release of PPM to the industry, NU took the pro-active step to hire Kalsi Engineering Inc. to provide validation using their KEI Gate program under their QA Program. KEI Gate is the functional equivalent of the gate valve model in the EPRI PPM program. Kalsi Engineering Inc. was the developer of the gate valve model under contract to EPRI.
NU recognizes that the NRC Staffintends to formally review PPM and issue a Safety Evaluation Report (SER). NU will examine the NRC SER when issued and reconcile any differences with KEI Gate. The schedule for resolution is dependent upon the significance of the change, and in no case j
would it be later than RFO 13. This recognizes that control switch settings may have to be adjusted if significant changes were made which would involve static diagnostic testing. Subsequent calculations for new valves, new conditions, or for those previous KEI Gate calculations which require revision will all be analyzed using the NRC reviewed version of EPRI PPM.
Results of a NRC inspection of the Millstone Unit 2 MOV program from January 30 - February 10, 1995, were issued in a report dated April 14,1995. The inspection report identified seven previously unresolved items needed for closure of the Millstone Unit 2 MOV Program. These items covered the same MOV Programmatic issues which were reviewed and accepted by the NRC during their closure of the Haddam Neck MOV Program".
l 51
Millstone Unit 2 MOV Program November 9,1995 q,,,,,
References
~~ ' James G. Partlow letter to All Licensees of Operating Nuclear Power Plants and Holders of Construction Permits for Nuclear Power Plants," Safety-Related Motor Operated Valve Testing and Surveillance (Generic Letter 89-10)- 10CFR50.54(f)," June 28,1989.
' James G. Partlow letter to All Licensees of Operating Nuclear Power Plants and Holders of Construction Permits for Nuclear Power Plants, and Individuals on the Attached Distribution List," Supplement I to Generic Letter 89-10: Results of the Public Workshops," June 13,1990.
' James G. Partlow letter to All Licensees of Operating Nuclear Power Plants and Holders of Construction Permits for Nuclear Power Plants," Supplement 2 to Generic Letter 89-10: ' Availability of Program Descriptions'," August 3,1990.
- James G. Partlow letter to All Licensees of Operating Nuclear Power Plants and Holders of Construction Permits for Nuclear Power Plants," Generic Letter 89-10, Supplement 3, ' Consideration of the Results of NRC-Sponsored Tests of Motor Operated Valves'," October 25,1990.
8 James G. Partlow letter to All Licensees of Operating Nuclear Power Plants and Holders of Construction Permits for Nuclear Power Plants," Generic Letter 89-10, Supplement 4, ' Consideration of Valve Mispositioning in Boiling Water Reactors'," February 12,1992.
' James G. Partlow letter to All Licensees of Operating Nuclear Power Plants and Holders of Construction Permits for Nuclear Power Plants," Generic Letter 89-10, Supplement 5, ' Inaccuracy of Motor-Operated j
Valve Diagnostic Equipment'," June 28,1993.
' James G. Partlow letter to All Licensees of Operating Nuclear Power Plants and Holders of Construction Permits for Nuclear Power Plants," Generic Letter 89-10, Supplement 6, 'Information on Schedule and Grouping, and Staff Responses to Additional Public Questions'," March 8,1994.
' S. D. Weerakody to R. T. Harris memo, NE-94-SAB-375," Quantitative importance Measures of Millstone Unit 2 MOVs," October 7,1994.
' S. D. Weerakody to R. T. Harris memo, NE-94-SAB-356," Revised Prioritization of Millstone Unit 2 MOVs,"
September 29,1994.
" Brian W. Sheron to NRC Regional Directors memo," Guidance on Closure of Staff Review of Generic Letter 89-10 Programs," July 12,1994.
" R. T. Harris to MOV File (MOV Program Manual, Notes / Memo Tab) memo, MOV-RTH-95-026, Rev. 3, "GL 89-10 Closure items," October 31,1995.
" R. T. Harris to MOV File (MOV Program Manual, Notes / Memo Tab) memo, MOV-RTH-94-037,"NU MOV Program Position on Structural Calculations at Stall (Locked Rotor) Condition," April 8,1994.
" J. H. Mutchler / R. J. Bumstead to S. T. Hodge memo, MOV-95-399, " Ambient Temperature Torque Derate of Non-Reliance AC Motors," August 25,1995.
" NRC Infonnation Notice 93-88," Status of Motor-Operated Valve Performance Prediction Program by the Electric Power Research Institute," November 30,1993.
" R. T. Harris to MOV File memo, MOV-RTH-93-034,"NU MOV Program: Acceptance Criteria for Gate Valve, Valve Factors (Vf) (Re: PI-9 and PI l 1)," January 25,1994.
" EPRI Letter,"EPRI MOV PPP Update of Results and Specifications and Drawings for Flow Loop Test Valves," December 14,1993.
" J. E. Richardson to NRC Regional Directors memo," Guidance for Inspections of Programs in Response to Generic Letter 89-10," April 30,1993.
" R. Eisner to R. T. Harris memo, MOV 94-021," Comparison of EPRI Perfonnance Prediction Program Valves to NU's GL 89-10 Program Motor Operated Valves," January 25,1994.
" R. T. Harris to J. W. Riley memo, MOV RTH 94-048,"MP-2 Exempting Testable Valves from Dynamic Testing," June 29,1994.
52
4 e,,en, o
)
Millstone Unit 2 MOV Program November 9,1995 i
l
P. S. Higgins to R. T. Blanchard Memo, MOV-94-300,"MP-2 Exempting and Adding Valves for Dynamic j
Testing," September 29,1994.
~
i
P. S. Higgins to H. E. Beeman Memo, MOV-95-020,"MP-2 MOV's Requiring CCN Issuance Prior to Next
[
Diagnostic Testing," July 25,1995.
- ' Engineering Record Memo, ER-95-0124, Revision 1. " Clarification of Assumptions Used in the Revision of Target nrust Calculations," October 12,1995.
l
NU Calculation,89-078-1319M2,"MP-2 Analysis of MOV Rate of Loading," November 3,1995.
]
. 24 J. H. Mutchler to R. C. Elfstrom memo, MOV-94-206," Limit Switch Repeatability for Limitorque j
Actuators," March 26,1994.
?
" NU Calculation W2-517-1075-RE, Revision 3," Millstone 2 MOV Repeatability Statistical Evaluation,"
May 4,1994.
John M. Jacobson (NRC) to E. Watzl (Northern States Power Co.) letter, "Close-Out Inspection of GL 89-10 (Monticello)," May 11,1995.
f
" Private Communication to NU, November 22,1994.
f
EPRI MOV Performance Prediction Program," Motor-Operated Separate Effects Testing," April 1995.
'I
" Onedenko, B. and Ushakov, I., Probabilistic Reliability Engineering, John Wiley & Sons, Inc.,1995, Page 19.
EPRI MOV Performance Prediction Program," Performance Prediction Methodology implementation Guide," November 1994.
" R. T. Harris to MOV File memo, MOV RTH-95 19,"NU MOV Program Position on Replacement of j
Operator or Yoke Bolts / Studs of GL 89-10 MOV's Without Diagnostic Retesting," April 6,1995.
l
J. F. Opeka letter to U. S. Nuclear Regulatory Commission,"Haddam Neck Plant, Millstone Nuclear Power f
i Station, Unit Nos.1,2, and 3, Response to Generic Letter 89-10, Supplement ', ' Inaccuracy of Motor-i Operated Valve Diagnostic Program'," October 14,1993.
f
" Liberty Technology Center Inc., " VOTES 2.0 Users Manual" Software, Version 2.3.1.
i
" Final Report Dennal Binding and Hydraulic Lock of Gate Valves for Millstone Unit 2 Nuclear Power Station", Stone and Webster Engineering Corporation, J.O. No. 1727409, September 27,1990.
" R. T. Harris to Distribution memo, MOV-RTH-94-034," Pressure Locking / Thermal Binding of Power I
Operated Valves," March 21,1994.
f 8' PI 20,"MOV Program Pressure Locking and Hermal Binding Evaluation," Revision 2.
" Calculation Change Notice 2 to "MP2 Pressure Locking and nermal Binding of Gate Valves", NU Calculation 89-078-1192 M2, Revision 0, July 27,1995.
8' E. J. Mroczka letter to U. S. Nuclear Regulatory Commission,"Haddam Neck Plant, Millstone Nuclear Power Station, Unit Nos.1,2, and 3, Generic Letter 89-10, ' Safety-Related Motor-Operated Valve Testing and Surveillance'," December 15,1989.
" J. F. Opeka letter to U. S. Nuclear Regulatory Commission, "Haddam Neck Plant, Millstone Nuclear Power Station, Unit Nos.1,2, and 3, ' Safety-Related Motor-Operated Valve Testing and Surveillance',"
May 4,1992.
I
- J. F. Opeks letter to U. S. Nuclear Regulatory Commission,"Haddam Neck, Millstone Nuclear Power 3
Station, Unit Nos.1,2, and 3, Generic Letter 89-10, ' Motor-Operated Valve Testing Program',"
1 December 13,1993.
E. M. Kelly, USNRC to J. F. Opeka, inspection Report #50-213/95-12,"Haddam Neck Motor-Operated 1-Valve inspection 95-12," September 29,1995.
i l
53
.