ML20044G344
| ML20044G344 | |
| Person / Time | |
|---|---|
| Issue date: | 02/25/1993 |
| From: | Thomas Scarbrough Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| GL-89-10, NUDOCS 9306020374 | |
| Download: ML20044G344 (29) | |
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i AGENDA PUBLIC WORKSHOP TO DISCUSS GENERIC LETTER 89-10,
" SAFETY-RELATED MOTOR-OPERATED VALVE TESTING AND SURVEILLANCE"
_L February 25, 1993 t
WELCOME AND OPENING REMARKS 8:00 am James E. Richardson, Director Division of Engineering Office of Nuclear Reactor Regulation i
GENERIC LETTER 89-10 AND NRC MOV ACTIVITIES 8:15 am Thomas G.
Scarbrough Mechanical Engineering Branch Division of Engineering Office of Nuclear R(actor Regulation GENERIC LETTER 89-10 INSPECTION RESULTS 9:00 am Representative from each NRC Region approximately 10 minutes each i
BREAK 9:45 - 10:00 am MOV NONCONFORMANCE AND OPERABILITY 10:00 am John N. Hannon, Director Project Directorate III-3 Division of Reactor Projects III/IV/V office of Nuclear Reactor Regulation i
REGULATORY BASIS FOR MOV CAPABT.LITY 10:30 am i
Anthony T. Gody, Jr.
Project Directorate III-3 Division of Reactor Projects III/IV/V office of Nuclear Reactor Regulation PRESSURE LOCKING AND THERMAL BINDING OF GATE VALVES 11:00 am i
Dr. Earl J.
Brown Reactor Operations Analysis Branch i
Division of Safety Programs J
Office for Analysis and Evaluation of Operational Data LUNCH 12:00 - 1:00 pm NRC STAFF RESPONSE TO WRITTEN QUESTIONS 1:00 pm ON GENERIC LETTER 89-10 BREAK 3:00 - 3:15 pm NRC STAFF RESPONSE TO QUESTIONS AND COMMENTS 3:15 pm FROM WORKSHOP PARTICIPANTS ON GENERIC LETTER 89-10 CLOSING REMARKS 4:45 pm James E. Richardson h
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9306020374 930225 PDR ORG NRRB bY
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GENERIC LETTER 89-10 AND NRC STAFF MOTOR-OPERATED VALVE ACTIVITIES February 25, 1993 Thomas G. Scarbrough Mechanical Engineering Branch Division of Engineering Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission l
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GENERIC LETTER 89-10 SAFETY-RELATED MOTOR-OPERATED VALVE TESTING AND SURVEILLANCE GL 89-10 REQUESTED LICENSEES TO ESTABLISH PROGRAMS TO ENSURE CAPABILITY OF ALL MOVs IN SAFETY-RELATED SYSTEMS TO PERFORM THEIR SAFETY FUNCTION.
INDIVIDUAL RECOMMENDED ACTIONS:
- a. REVIEW AND DOCUMENT THE DESIGN BASIS FOR THE OPERATION OF EACH MOV TO DETERMINE THE MAXIMUM DIFFERENTIAL PRESSURE AND FLOW EXPECTED FOR BOTH NORMAL OPERATIONS AND ABNORMAL CONDITIONS.
- c. TEST MOVs AT DESIGN-BASIS DIFFERENTIAL PRESSURE AND FLOW CONDITIONS WHERE PRACTICABLE AND JUSTIFY ALTERNATIVES WHERE DESIGN-BASIS TESTING NOT PRACTICABLE.
(IF DESIGN-BASIS TESTING NOT PRACTICABLE AND AN ALTERNATIVE CANNOT BE JUSTIFIED AT THIS TIME, LICENSEES MAY USE A TWO-STAGE APPROACH TO DETERMINE THE ADEQUACY OF MOV SIZING AND SWITCH SETTINGS USING THE BEST DATA AVAILABLE FOR THE FIRST STAGE AND THEN OBTAINING APPLICABLE DATA FOR THE SECOND STAGE. )
- d. PREPARE OR REVISE PROCEDURES TO ENSURE THAT ADEQUATE SWITCH SETTINGS ARE VERIFIED PERIODICALLY (EVERY 5 YEARS OR 3 REFUELING OUTAGES, AND FOLLOWING MAINTENANCE).
- e. ANALYZE EACH MOV FAILURE, JUSTIFY CORRECTIVE ACTION, AND TREND RESULTS (WITH REVIEW EVERY 2 YEARS).
SCHEDULE:
LICENSEES REQUESTED TO COMPLETE INITIAL TEST PROGRAM BY JUNE 1994 OR 3 REFUELING OUTAGES AFTER DECEMBER 28, 1989, WHICHEVER IS LATER.
)
SUPPLEMENT 1 TO GENERIC LETTER 89-10 (JUNE 13, 1990)
PROVIDES THE RESULTS OF THE PUBLIC WORKSHOPS TO DISCUSS THE GENERIC LETTER AND TO ANSWER QUESTIONS REGARDING ITS IMPLEMENTATION.
LIMITS SCOPE OF GENERIC LETTER TO MOVs IN SAFETY-RELATED EPll{G SYSTEMS.
LIM'ITS CONSIDERATION OF VALVE MISPOSITIONING TO INADVERTENT OPERATION FROM THE CONTROL ROOM.
DISCUSSES THE FACTORS TO BE CONSIDERED, AND LIMITATIONS,.IN JUSTIFYING THE ACCEPTABILITY OF ALTERNATIVES TO IN SITU DESIGN-BASIS TESTING.
EMPHASIZES THE RECOMMENDATION TO FOLLOW THE TWO STAGE APPROACH WHERE DESIGN-BASIS TESTING IS NOT PRACTICABLE AND AN ALTERNATIVE CANNOT BE JUSTIFIED AT THIS TIME.
SUPPLEMENT 2 TO GENERIC LETTER 89-10 (AUGUST 3, 1990)
TO ALLOW ADDITIONAL TIME FOR LICENSEES TO INCORPORATE THE INFORMATION IN SUPPLEMENT 1 Ilr1'O THEIR GENERIC LETTER PROGRAMS, THE NRC STAFF STATED THAT PROGRAM DESCRIPTIONS DID NOT NEED TO BE AVAILABLE ON SITE UNTIL JANUARY 1, 1991.
THE SCHEDULE REQUESTED FOR COMPLETING THE RECOMMENDED ACTIONS OF GL 89-10 BY JUNE 28, 1994 OR THREE REFUELING OUTAGES AFTER DECEMBER 28, 1989 (OR OPERATING LICENSE ISSUANCE FOR CONSTRUCTION PERMIT HOLDERS) REMAINS UNCHANGED.
i SUPPLEMENT 3 TO GENERIC LETTER 89-10 (OCTOBER 25, 1990)
BASED ON (1) THE RESULTS OF NRC-SPONSORED MOV TESTS OF 6-INCH AND 10-INCH FLEXIBLE WEDGE GATE VALVES TYPICALLY USED FOR CONTAINMENT ISOLATION IN THE HIGH PRESSURE COOLANT INJECTION (HPCI) AND REACTOR CORE ISOLATION COOLING (RCIC) SYSTEMS AND IN THE SUPPLY LINE FOR THE REACTOR WATER CLEANUP (RWCU) SYSTEM IN BWR PLANTS, AND (2) THE NRC STAFF'S BRIEF REVIEW OF THE CAPAEILITY OF MOVs USED FOR THOSE PURPOSES AT BWR PLANTS, THE STAFF DETERMINED THAT ACTION SHOULD BE TAKEN BY BWR LICENSEES TO PROVIDE ASSURANCE OF THE CAPABILITY OF THOSE MOVs IN ADVANCE OF THE OVERALL GENERIC LETTER SCHEDULE.
IN RESPONSE TO SUPPLEMENT 3, BWR LICENSEES ESTABLISHED CRITERIA TO DETERMINE WHETHER DEFICIENCIES EXISTED IN THE APPLICABLE MOVs IN THE HPCI, RCIC, AND RWCU SYSTEMS, AS WELL AS IN THE ISOLAT10N CONDENSER LINES, AS APPLICABLE; IDENTIFIED ANY MOVs FOUND TO HAVE DEFICIENCIES; AND ESTABLISHED A SCHEDULE FOR ANY NECESSARY CORRECTIVE ACTION.
BWR LICENSEES HAVE COMPLETED THEIR EVALUATIONS IN RESPONSE TO SUPPLEMENT 3 TO GL 89-10.
LICENSEES HAVE REPORTED THAT APPROXIMATELY ONE-HALF OF THE 200 MOVs WITHIN THE SCOPE OF SUPPLEMENT 3 TO GL 89-10 HAVE BEEN, OR WILL BE, MODIFIED OR ADJUSTED IN RESPONSE TO THE EVALUATION PERFORMED IN RESPONSE TO SUPPLEMENT 3.
SUPPLEMENT 4 TO GENERIC LETTER 89-10 (FEBRUARY 12, 1992)
BWR OWNERS GROUP APPEALED THE RECOMMENDATION IN GL 89-10 TO ADDRESS INADVERTENT MOV OPERATION FROM THE CONTROL ROOM.
AS RESULT OF AN NRC-SPONSORED STUDY OF CORE MELT PROBABILITY, NRC STAFF ISSUED SUPPLEMENT 4 TO GL 89-10 STATING THAT BWR LICENSEES NEED NOT ADDRESS INADVERTENT MOV OPERATION AS PART OF THEIR GL i
89-10 PROGRAMS ALTHOUGH THE STAFF BELIEVES THAT SUCH CONSIDERATION BENEFITS SAFETY.
i SUPPLEMENT 4 EMPHASIZES THAT LICENSEES MAY NEED TO ADDRESS VALVE MISPOSITIONING IN RESPONSE TO NRC REGULATIONS (SUCH AS FIRE PROTECTION).
j NRC STAFF WILL BE EVALUATING THE Il
'ASE IN CORE MELT PROBABILITY AS A CONSEQUENCE OF INAL'ZRTENT MOV OPERATION IN PWR PLANTS.
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PROPOSED SUPPLEMENT 5 TO GENERIC LETTER 89-10 ON FEBRUARY 4, 1992, MOV USERS GROUP (MUG) ISSUED REPORT ON ACCURACY OF MOV DIAGNOSTIC EQUIPMENT.
MUG FOUND EQUIPMENT FROM IMPELL AND ITI-MOVATS RELYING ON SPRING PACK DISPLACEMENT TO ESTIMATE STEM THRUST DID NOT MEET THEIR ACCURACY CLAIMS.
IMPELL STATED AT THE FEB. 1992 MUG MEETING THAT IT WOULD BE MEETING WITH ITS TWO LICENSEE CUSTOMERS.
ON MARCH 2, 1992, NRC STAFF MET WITH ITI-MOVATS TO DISCUSS-MUG PROGRAM AND ITI-MOVATS VALIDATION PROGRAM.
ITI-MOVATS FOUND INCREASED UNCERTAINTY IN ACCURACY OF THRUST MEASURING DEVICE (TMD) FROM CALIBRATION IN OPEN DIRECTION WHILE RELYING ON TMD TO ESTIMATE THRUST IN CLOSE DIRECTION.
ON MARCH 13, 1992, ITI-MOVATS RELEASED ENGINEERING REPORT $.2 TO 1
PROVIDE GUIDANCE FOR LICENSEES.
NUMARC PREPARED GUIDELINES ON ITI-MOVATS GUIDANCE.
ON JULY 8, 1992, NRC STAFF PUBLISHED PROPOSED SUPPLEMENT 5 TO GL 89-10 IN FEDERAL REGISTER FOR PUBLIC COMMENT ON VALVE STEM 4
DIRECTIONAL EFFECTS FOR ALL MOV DIAGNOSTIC EQUIPMENT AND REFERENCING THE NUMARC GUIDELINES FOR ITI-MOVATS TMD.
PUBLIC COMMENTS RECEIVED FROM NUMARC, OHIO CITIZENS FOR RESPONSIBLE ENERGY, CAROLINA POWER & LIGHT COMPANY, AND ENTERGY OPERATIONS-GRAND GULF.
NRC STAFF PREPARED PACKAGE FOR NRC'S COMMITTEE TO REVIEW GENERIC REQUIREMENTS (CRGR) ON INACCURACY OF MOV DIAGNOSTIC EQUIPMENT RESULTING FROM VALVE STEM DIRECTIONAL EFFECTS.
ON OCTOBER 2, 1992, LIBERTY TECHNOLOGIES SUBMITTED A PART 21 i
NOTICE ON THE POTENTIAL INCREASED INACCURACY OF ITS VOTES EQUIPMENT CAUSED BY (1) THE POSSIBLE USE OF IMPROPER STEM MATERIAL CONSTANTS AND (2) THE FAILURE TO ACOOUNT FOR A TORQUE EFFECT WHEN THE EQUIPMENT IS CALIBRATED BY MEASURING STRAIN OF THE THREADED PORTION OF A VALVE STEM.
INFORMATION NOTICE 93-01 DISCUSSES THE INCREASED INACCURACY OF THE VOTES EQUIPMENT.
NRC STAFF WILL BE DISCUSSING THESE ISSUES WITH CRGR IN THE NEAR FUTURE.
CVERALL FINDINGS OF GL 89-10 INSPECTIONS TEMPORARY INSTRUCTION 2515/109 PART 1 INVOLVES INSPECTION TO REVIEW THE PROGRAM DEVELOPED i
IN RESPONSE TO GL 89-10.
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PART 2 INVOLVES INSPECTION OF THE IMPLEMENTATION OF THE GL i
89-10 PROGRAM.
i INFORMATION NOTICE 92-17 SUMMARIZES GL 89-10 INSPECTION FINDINGS UP TO THE DATE OF ITS PREPARATION.
ALL BUT TWO SITES (MILLSTONE AND WATTS BAR) INSPECTED UNDER PART 1 OF TI 2515/109.
FIRST INSPECTION UNDER PART 2 OF TI 2515/109 CONDUCTED AT FERMI-2 FROM FEBRUARY 8 TO 18, 1993.
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INSPECTIONS UNDER PART 1 OF TEMPORARY INSTRUCTION 2515/109 TO REVIEW GENERIC LETTER 89-10 PROGRAMS SCOPE:
SCOPE OF LICENSEE MOV PROGRAMS GENERALLY CONSISTENT WITH GL 89-10.
DESIGN-BASIS REVIEWS:
MOST LICENSEES REVIEWING APPROPRIATE PLANT DOCUMENTATION TO DETERMINE WORST CASE CONDITIONS FOR ALL DESIGN-BASIS SCENARIOS.
SOME LICENSEES HAD NOT REVIEWED PLANT PROCEDURES TO ENSURE THAT WORST CASE CONDITIONS IDENTIFIED FOR VARIOUS DESIGN-BASIS SCENARIOS.
LACK OF CONSIDERATION OF DESIGN-BASIS FACTORS OTHER THAN DIFFERENTIAL PRESSURE.
DEGRADED VOLTAGE STUDIES AT MANY PLANTS NEED UPDATING.
MOV SIZING AND SWITCH SETTING CALCULATIONS:
SOME LICENSEES USE VALVE FACTORS THAT REFLECT RECENT INDUSTRY AND RESEARCH EXPERIENCE.
SOME LICENSEES USE OLD VALVE FACTORS THAT MAY BE INADEQUATE FOR SOME MOVs.
FOR EXAMPLE, WEAKNESSES FOUND IN (1)
JUSTIFICATION FOR ASSUMPTIONS FOR STEM FRICTION COEFFICIENT OVER THE ENTIRE STEM LUBRICATION INTERVAL, (2)
CONSIDERATION OF MARGIN FOR LOAD SENSITIVE BEHAVIOR, (3)
JUSTIFICATION FOR REMOVAL OF ANY STANDARD CONSERVATISM (SUCH AS APPLICATION FACTOR), AND (4)
USE OF LIMITORQUE SIZING EQUATION WITH STALL MOTOR TORQUE AND STALL EFFICIENCY CONTRARY TO EPRI AND LIMITORQUE GUIDANCE.
SOME LICENSEES NOT EVALUATING MOV SIZING AND SWITCH SETTING CALCULATIONS FOR MARGINAL AND POTENTIALLY UNDERSIZED MOVs FOR APPROPRIATE ACTION.
1 DESIGN-BASIS TESTING:
MANY LICENSEES HAVE COMMITTED TO TEST MOVs UNDER DESIGN-BASIS CONDITIONS, WHERE PRACTICABLE, AS REQUESTED BY GL 89-10.
TEST RESULTS INDICATE THAT APPARENTLY IDENTICAL MOVs DO NOT ALWAYS PERFORM SIMILARLY.
IN SUCH CASES, LICENSEE SHOULD PERFORM ROOT CAUSE ANALYSIS TO UNDERSTAND WHY BEHAVIOR DIFFERS.
BASED ON TEST RESULTS AND ROOT CAUSE ANALYSIS, LICENSEE MAY FIND GROUPING OF MOVs DIFFICULT.
DIFFERENTIAL PRESSURE AND FLOW TESTING REVEALS MANY GATE MOVs TO REQUIRE MORE THRUST TO OPERATE THAN PREDICTED BY THE STANDARD EQUATION WITH 0.3 VALVE FACTOR AND MEAN DISC AREA.
WEAKNESSES FOUND IN PROCEDURES FOR MOV TESTING, ACCEPTANCE CRITERIA, AND FEEDBACK OF TEST RESULTS INTO MOV CA*,CULATIONS.
SOME LICENSEES ARE NOT THOROUGHLY EVALUATING STATIC AND DYNAMIC TEST RESULTS TO ENSURE OPERABILITY BEFORE THE MOVs ARE RETURNED TO SERVICE.
SOME LICENSEES ARE NOT INCORPORATING THEIR VALVE SPECIFIC AND PLANT-WIDE MOV TEST RESULTS INTO SIZING AND SWITCH SETTING CALCULATIONS IN A TIMELY MANNER.
LICENSEES NEED TO ADDRESS REGULATORY REQUIREMENTS AND TECH SPECS FOR REPORTING AND ACTION BASED ON TEST RESULTS.
SOME LICENSEES NOT FOLLOWING THEIR COMMITMENTS TO TWO-STAGE APPROACH FOR MOVs THAT CANNOT BE TESTED IN-SITU UNDER DESIGN-BASIS CONDITIONS.
AS DISCUSSED IN SUPPLEMENT 1 TO GL 89-10, FIRST STAGE OF TWO-STAGE APPROACH INVOLVES TESTING MOV AT MAXIMUM ACHIEVABLE CONDITIONS.
SUCH TESTING HELPS VERIFY VALVE FACTOR AND STEM FRICTION COEFFICIENT ASSUMPTIONS.
TEST RESULTS MIGHT REQUIRE TECH SPEC ACTIONS OR REPORTING.
LICENSEES HAVE FOUND SOME MOVs NOT CAPABLE OF OPERATING IN
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NONSAFETY DIRECTION UNDER THEIR ORIGINAL DESIGN-BASIS CONDITIONS WHIC.i! MAY AFFECT PRAs AND SEVERE ACCIDENT STUDIES.
PERIODIC VERIFICATION AND POST-MAINTENANCE TESTING:
MOST LICENSEES HOPE TO PERIODICALLY VERIFY DESIGN-BASIS CAPABILITY FROM STATIC TESTING, BUT HAVE NOT JUSTIFIED THE EXTRAPOLATION OF STATIC TEST RESULTS TO DESIGN-BASIS CONDITIONS.
l OVER THE IONG TERM, LICENSEES WILL NEED TO JUSTIFY THEIR PERIODIC VERIFICATION METHOD.
MOST LICENSEES ARE IMPROVING POST-MAINTENANCE TESTING (PMT)
METHODS.
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CORRECTIVE ACTION AND TRENDING:
SOME LICENSEES HAVE BEEN WEAK IN RESPONDING TO MOV FAILURES AND DEFICIENCIES.
I SOME LICENSEES HAVE NOT BEEN THOROUGH IN ROOT CAUSE ANALYSES.
l TRENDING BY SOME LICENSEES HAS NOT BEEN CONSISTENT WITH GL 89-10.
TRENDING EFFORTS BY MOST LICENSEES IMPROVING.
SCHEDULE:
SOME LICENSEES HAD NOT MADE SUFFICIENT PROGRESS TOWARD RESOLVING THE MOV ISSUE WITHIN THE RECOMMENDED SCHEDULE OF GL 89-10.
LESS THAN TWO YEARS REMAIN IN THE GL 89-10 SCHEDULE AND MANY LICENSEES ARE JUST BEGINNING DYNAMIC TESTING OF MOVs.
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NRC STAFF HAS ACCEPTED LIMITED EXTENSIONS FOR GL 89-10 SCHEDULE WHERE JUSTIFICATION PROVIDED.
EXAMPLE FINDINGS IN RELATED MOV AREAS 1.
SOME LICENSEES HAVE NOT PROVIDED ADEQUATE MANAGEMENT OVERSIGHT AND DIRECTION FOR MOV PROGRAM.
2.
LICENSEES IMPROVING DOCUMENTATION OF CURRENT AND REQUIRED MOV SWITCH SETTINGS BUT SOME WEAKNESSES REMAIN.
3.
SOME LICENSEES HAVE RAISED TORQUE SWITCH SETTINGS ABOVE MANUFACTURER *S MAXIMUM VALUE WITHOUT SAFETY EVALUATION.
4.
SOME LICENSEES RELYING ON PREVENTIVE MAINTENANCE OR DIAGNOSTIC TEST RESULTS FOR DETERMINING MOV REFURBISHMENT DESPITE WEAKNESSES IN IDENTIFYING DEGRADATION.
5.
SOME LICENSEES HAVE STRONG TRAINING PROGRAMS, BUT SOME WLAKNESS IN REFRESHER TRAINING, TRAINING OF CONTRACTOR PERSONNEL, AND VERIFICATION OF INSTRUCTOR CAPABILITY.
6.
SOME LICENSEES HAVE STRONG HOUSEKEEPING, BUT AT OTHER PLANTS GREASE LEAKS, DIRTY STEMS, AND OUT-OF-DATE CALIBRATION STICKERS FOUND.
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INSPECTIONS UNDER PART 2 OF TEMPORARY INSTRUCTION 2515/109 TO EVALUATE IMPLEMENTATION OF GENERIC LETTER 89-10 PROGRAMS I
NRC STAFF EXPECTATIONS REGARDING GL 89-10 PROGRAMS USE BEST AVAILABLE DATA TEST ALL MOVs IN GL 89-10 PRO 3 RAM UNDER MAXIMUM ACHIEVABLE CONDITIONS WHERE PRACTICABLE BE AWARE OF INDUSTRY TEST DATA JUSTIFY EACH PARAMETER IN MOV CALCULATIONS FOR EXAMPLE, JUSTIFY VALVE FACTOR AND STEM FRICTION COEFFICIENT BASED ON PLANT SPECIFIC DATA DETERMINE APPROPRIATE AMOUNT OF MARGIN TO ACCOUNT FOR LOAD SENSITIVE BEHAVIOR ASSUME CONSERVATIVE VALUE FOR A PARAMETER WHERE NO PLAlfr SPECIFIC JUSTIFICATION CURRENTLY AVAILABLE LICENSEE MAY CONSIDER ANY CONSERVATISM IN PARAMETERS WHERE CALCULATION PREDICTS CAPABILITY PROBLEMS EVALUATE TEST RESULTS BEFORE RETURNING MOV TO SERVICE JUSTIFY ACCURACY OF MOV DIAGNOSTIC SYSTEM PERFORMANCE OF GL 89-10 INSPECTIONS A PRINCIPAL GOAL OF THE STAFF WILL BE TO ENSURE CONSISTENCY REGARDING OPERABILITY AND ENFORCEMENT DETERMINATIONS DURING PART 2 INSPECTIONS FOCUS OF PART 2 INSPECTIONS WILL BE THE DESIGN BASIS CAPABILITY OF SPECIFIC SAMPLED MOVs STAFF WILL EVALUATE GROUPING BASED ON FINDINGS FOR SAMPLED MOVs MOV OPERABILITY TECHNICAL GUIDANCE ON OPERABILITY AND NONCONFORMING COMPONENTS FOUND IN GENERIC LETTER 91-18
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NONCONFORMING AND INOPERABLE MOVs DURING PART 2 INSPECTIONS l
LICENSEES FINDING MANY MOVs CANNOT SATISFY LIMITORQUE TYPICAL SIZING EQUATION STAFF HAS BEEN FACED WITH CASES WHERE LICENSEES HAVE NOT ADEQUATELY JUSTIFIED PARAMETERS FOR MOV CALCULATIONS DURING PART 2 INSPECTIONS, STAFF WILL EVALUATE JUSTIFICATION FOR OPERABILITY OF SAMPLED MOVs STAFF WILL CONSIDER PARAMETERS IN COMBINATION REGULATORY BASIS FOR MOV CAPABILITY OFFICE OF ENFORCEMENT AND NRR HAVE DISCUSSED REGULATORY BASIS FOR MOV CAPABILITY WITH REGIONS TO HELP ENSURE CONSISTENCY MOV TESTING GL 89-10 RECOMMENDS THAT MOVs BE TESTED AT MAXIMUM ACHIEVABLE I
CONDITIONS WHERE PRACTICABLE TESTING AT MAXIMUM ACHIEVABLE CONDITIONS MAY PROVIDE INFORMATION TO SUPPORT GROUPING IF TESTED AT OR NEAR DESIGN BASIS CONDITIONS, LICENSEE WILL BE ABLE TO BETTER JUSTIFY DESIGN BASIS CAPABILITY DATA FROM ALL MOV TESTS UNDER STATIC AND DIFFERENTIAL PRESSURE CONDITIONS NEED TO BE EVALUATED BECAUSE OF UNCERTAINTIES IN " N POLATING TEST DATA, LICENSEE MIGHT HAVE TO USE EXTRAPOLATED DATA AS FIRST STAGE OF TWO-STAGE APPROACH EPRI PROGRAM MIGHT PROVIDE ADDITIONAL SUPPORT FOR EXTRAPOLATING 4
TEST DATA I
ACCEPTANCE CRITERIA FOR RETURNING MOV TO SERVICE:
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STATIC TEST 1.
AVAILABLE THRUST AND TORQUE WITHIN WINDOW 2.
DIAGNOSTIC TRACES DO NOT INDICATE ABNORMALITIES OR ANOMALIES 3.
VALVF, STROKE TIME MEETS ASME SECTION XI AND TECH SPECS
DIFFERENTIAL PRESSURE TEST 1.
VALVE FULLY OPENS WITH APPROPRIATE TOR'QUE SWITCH BYFASS AND FULLY CLOSES WITH SEATING AND CONTROL ROOM INDICATION 2.
CONTROL SWITCH SETTINGS PROVIDE ADEQUATE THRUST MARGIN TO OVERCOME DESIGN BASIS REQUIREMENTS (INCLUDING DIAGNOSTIC EQUIPMENT INACCURACY, CONTROL SWITCH REPEATABILITY, LOAD SENSITIVE BEHAVIOR, AND MARGIN FOR DEGRADATION) 3.
MOTOR OUTPUT CAPABILITY AT DEGRADED VOLTAGE EXCEEDS CONTROL SWITCH SETTING (INCLUDING FACTORS IN ITEM 2) 4.
MAXIMUM THRUST AND TORQUE (INCLUDING DIAGNOSTIC EQUIPMENT INACCURACY AND CONTROL SWITCH REPEATABILITY) DO NOT EXCEED STRUCTURAL LIMITS 5.
DIACNOSTIC TRACES DO NOT INDICATE SIGNIFICANT ABNORMALITIES OR ANOMALIES.
POST-MAINTENANCE TESTING SOME LICENSEES CONTINUE TO USE MOTOR CURRENT SIGNATURES FOR POST-MAINTENANCE TESTING FOLLOWING PACKING REPLACEMENT OR ADJUSTMENTS MOTOR CURRENT HAS NOT BEEN SHOWN RELIABLE FOR PREDICTING PACKING LOAD CHANGES STAFF WILL ADDRESS THIS CONCERN DURING PART 2 INSPECTIONS PRESSURE LOCKING AND THERMAL BINDING STAFF HAS COMPLETED A STUDY OF PRESSURE LOCKING AND THERMAL BINDING OF GATE VALVES STAFF IS PREPARING AN INFORMATION NOTICE ON THE STUDY STAFF WILL REVIEW LICENSEE EVALUATION OF POTENTIAL FOR PRESSURE LOCKING AND THERMAL BINDING OF GATE VALVES AND CORRECTIVE ACTION DURING PART 2 INSPECTIONS SCHEDigg STAFF BELIEVES THE MOV ISSUE NEEDS TO BE RESOLVED PROMPTLY LICENSEES SHOULD HAVE CONDUCTED SUFFICIENT TESTING BY JUNE 1994 TO ADEQUATELY SIZE AND SET ALL MOVs IN GL 89-10 PROGRAM USING THE BEST AVAILABLE DATA SUCH AS VALVE SPECIFIC, PLANT SPECIFIC, EPRI, OR INDUSTRY TESTS.
PLANNED AND RECOMMENDED INDUSTRY AND NRC STAFF ACTIONS INDUSTRY 1.
TEST MOVs AT MAXIMUM ACHIEVABLE CONDITIONS WHERE i
PRACTICABLE.
2.
COLLECT ALL RELEVAh"r PARAMETERS DURING TESTING (SUCH AS DESCRIBED IN EPRI IN-SITU TEST GUIDE FOR ENHANCED TESTING).
3.
ENSURE THE CAPABILITY OF MOVs TO PERFORM THEIR SAFETY FUNCTION BEFORE RETURN TO SERVICE FOLLOWING TESTING.
4.
SELECT AN INDUSTRY LEADER TO DEVELOP (1) AN ACCEPTABLE TECHNICAL BASIS FOR GROUPING MOVS THAT ARE NOT PRACTICABLE TO TEST UNDER DIFFERENTIAL PRESSURE AND FLOW CONDITIONS, (2)
A METHOD TO EXTRAPOLATE MOV CAPABILITY AT DEGRADED VOLTAGE FROM TEST OF THE MOV UNDER DIFFERENTIAL PRESSURE AND FLOW i
CONDITIONS AND FULL VOLTAGE, (3) SPECIFIC APPROACHES TO ANALYZE AND REMEDY PRESSURE LOCKING AND THERMAL BINDING, AND (4) A HIGH-QUALITY, USEABLE INDUSTRY MOV TEST DATABASE.
5.
BY JUNE 1994, SIZE AND SET ALL GL 89-10 MOVs USING BEST AVAILABLE DATA FROM PLANT SPECIFIC TESTS, EPRI TESTS, OR INDUSTRY TESTS.
6.
EPRI INFORMATION IS EXPECTED TO BE A KEY SOURCE FOR COMPLETING STAGE 2 OF THE TWO-STAGE APPROACH.
LICENSEES SHOULD THINK OF THE EPRI INFORMATION AS BEING CONFIRMATION OF THE WAY THE VALVES HAD ALREADY BEEN SET UP.
THEREFORE, LICENSEES SHOULD NOT WAIT OR POSTPONE ACTIONS EXPECTING THE EPRI PROGRAM TO REPLACE YOUR COMMITTED STAGE 1 RESPONSIBILITIES.
7.
PRIORITIZE MOVs SUCH THAT HIGHEST SAFETY SIGNIFICANT MOVs ARE TESTED AT MAXIMUM ACHIEVABLE CONDITIONS BY JUNE 1994 OUTAGES.
8.
COMPLETE TESTING IN ACCORDANCE WITH ORIGINAL GL 89-10 SCHEDULE COMMITMENT OR, WHERE JUSTIFIED, MAY REQUEST EXTENSION.
9.
RESTORE MARGIN TO MOV CAPABILITY AS LONG-TERM ENDPOINT.
10.
DEVELOP A HIGH-QUALITY, USEABLE INDUSTRY MOV TEST DATABASE SO THAT ALL LICENSEES WILL BE ABLE TO ADEQUATELY SIZE AND SET MOVs BY JUNE 1994.
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NRC STAFP 1.
DEVELOPING DEFINITIVE ACCEPTANCE CRITERIA FOR NRC INSPECTIONS.
2.
MAY REQUIRE EACH LICENSEE TO SUBMIT A REPORT ON THE METHODOLOGY USED TO SIZE AND SET EACH MOV (INCLUDING DESIGN BASIS PARAMETERS, SAFETY FUNCTION, BASIS FOR ESTIMATING THRUST / TORQUE REQUIREMENTS, AND JUSTIFICATION FOR APPLYING j
DATA FROM OTHER MOVs WHERE APPLICABLE) BY JUNE 1994.
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3.
WILL LIKELY TAKE ENFORCEMENT ACTION IN CASES WHERE MOVs ARE FOUND TO BE INOPERABLE BECAUSE OF INADEQUATE TORQUE OR THRUST CAPABILITY AFTER JUNE 1994.
i 4.
DEVELOPING A SUPPLEMENT TO GL 89-10 TO DISCUSS JUNE 1994 MOV
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STATUS, REPORTING MOV STATUS, SCHEDULE EXTENSIONS, f
ENFORCEMENT, PRIORITIZATION OF EFFORTS, AND ENDPOINT OBJECTIVE OF RESTORING MARGINS.
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5.
CONTINUE TO CONDUCP INSPECTIONS TO ENSURE LICENSEES IMPLEMENT PROGRAMS CONSISTENT WITH THE INTENT OF GL 89-10.
6.
UPDATING THE INSPECTION GUIDANCE TO REFLECT THE RESULTS OF THE PART 1 INSPECTIONS.
1 7.
COMPLETE EVALUATION OF INADVERTENT MOV OPERATION IN PWR PLANTS.
8.
CONTINUE TO REVIEW EPRI MOV PERFORMANCE PREDICTION PROGRAM.
I 9.
EXPLORING THE APPLICATION OF PROBABILISTIC RISK ASSESSMENT TO MOVs TO DEVELOP GUIDELINES ON THE USE OF THIS APPROACH FOR LICENSEE PRIORITIZATION OF MOV ACTIVITIES.
10.
DEVELOPING CONTACTS WITH REGULATORY AND INDUSTRY REPRESENTATIVES FROM OTHER COUNTRIES TO SHARE INFORMATION ON RESOLUTION OF MOV ISSUES.
11.
PREPARE INFORMATION NOTICE ON PHOENIX WORKSHOP.
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PRESSURE LOCKING PHENOMENON AND CAUSES.
(SAFETY-SIGNIFICANT CAUSES)
Leakage past downstream check valve High-pressure causes disc to flex I
Downstream line subsequently depressurizes rapidly (LOCA)
Ifigh-pressure fluid trapped in bonnet while upstre'am and downstream lines are at lower pressures 6
e 4
s & 9
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3
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PRESSURE LOCKING PHENOMENON AND CAUSES (SAFETY SIGNIFICANT CAUSES)
Bonnet liquid heatup during mode transition l
RHR pump suction valve from suppression pool during realignment from the SDC mode to the standby LPCI mode during reactor heatup.
l heatup is through thermal conduction from suction junction pressure locking at 175 *F RCS temperature,74 F suppression pool temperature RCS temperature reduced to 135 F. AT across the valve was 43 *F. Still cannot be opened.
AT across the valve reduced to 20 *F then opened l
l r
i 4
c SAFETY SIGNIFICANCE
[
t i
Flexible-wedge and double disc gate valves widely used in e
BWRs and PWRs. Required to open to perform safety-function.
e Safety system function lost.
Potential common-cause failure mechanism.
i Conditions develop during normal plant evolution e
e ASP analysis For the FitzPatrick 1991 event d
Conditional core damage probability: 4 x 10 1
6
AEOD SURVEY ON LICENSEE' CORRECTIVE ACTIONS Site Survey:
Six plants May 1992. Two plants Febraary 1993.
BWR and PWR Operating plants Results of AEOD Survey:
Most licensees do not consider pressure locking a credible problem Lack of plant-specific failure exnerience Generic communications not specific Review based on engineering judgement Engineering analyses not comprehensive or conservative Some licensees made modifications on LPCI and LPCS valves -
otba licensees have not i
s D
6
v LESSONS LEARNED FROM SURVEY AND OPERATING EVENTS Several valve suppliers are involved ECCS valves susceptible: LPCI, LPCS, LHSI, RHR suction isolation, Emergency feedwater system, LPCI turbine steam Motor operator damage or degradation due to valve operation at locked rotor current The potential for valve locking has not been fully evaluated or corrected for all system operating modes, transients, or infrequent plant alignments Surveillance testing does not identify problem Lack of training program for engineering staff c
Two types of valve modification are involved Weep hole Vent line t
b 7
LESSONS LEARNED FROM SURVEY AND OPERATING EVENTS Noncont ervative aspects of pressure locking analyses were observed:
Leakage past check valve assumed to be zero 1
l Bonnet out-leakage rate assumed worn disks rather than l
new/rebnitt discs l
1 i
I l
Bonnet out-leakage rate based on low differential press.ure rather than high differential pressure 4
All valve internal forces not included or assumed to act simultaneously Motor-operator thrust capability was not conservative Bonnet heatup from nearby pipe breaks or equipment was not considered 8
CONCLUSION BWR and PWR safety-related valves affected e
Common-mode failure mechanism Industry /NRC feedback not effective in achieving adequate licensee assessments and/or corrective actions Surveillance test does not detect problem l
Thorough system analysis to identify valve susceptibility Physical modification is the most effective corrective action b _ ___ _ _ _ _ _ __ _ ___ _ _ _ _ - _ _ _ -_ __ _ _
NRC ACTIONS Considered a GL89-10 issue NRC/NUAIARC joint efTort Technical workshop NUREG report I
?
i 10
Pressure Locking Flexible-Wedge Gate Valve t
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