ML20138M415
| ML20138M415 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse, Oconee, Arkansas Nuclear, Three Mile Island, Rancho Seco, 05000000 |
| Issue date: | 10/17/1985 |
| From: | Vissing G Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20138M420 | List: |
| References | |
| NUDOCS 8511010225 | |
| Download: ML20138M415 (94) | |
Text
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OCT 171985 Dockets Nos. 50-269, 50-270, 50-287, 50-289, 50-300, 50-312, 50-313 and 50-346 l
l LICENSEE: B&WOG TRANSIENT ASSESSMENT AND AVAILABILITY COMMITTEES
SUBJECT:
SUMMARY
OF MEETING WITH THE B&WOG TRANSIENT ASSESSMENT AND AVAILABILITY COMMITTEES TO DISCUSS THESE COMMITTEES ACTIVITIES AND l
THEIR PLANS RELATIVE TO A PROPOSED RAISING 0F THE B&W REACTOR HIGH PRESSURE TRIP SET P0 INT, OCTOBER 4, 1985.
Introduction The staff met with the B&WOG Transient Assessment and Availability Committees in the B&W offices in Bethesda, Maryland, on October 4,1985, at the request of these comittees. The purpose of the meeting was to review with the staff the activities of these committees and to present the future plans of the comittees. In particular the committee came to discuss the operating experience of the B&W operating reactors and the plans of the B&WOG to improve that experience. Also, the committee came to discuss a proposal to raise the high pressure set point for reactor trip and the set point for arming the anticipatory turbine trip. Enclosure 1 is a list of the attendees. Enclosures 2, 3, 4, 5, 6, 7 and 8 are copies of the material presented at the meeting.
Discussion The B&WOG presented the agenda, described the make up and organization of the B&WOG, and discussed the objectives and goals of the Availability Committee and the Transient Assessment Committee. See Enclosure 2 and 3.
The Availability Committee has tracked and studied the availability, c6pacity factors, forced outages, planned outages and causes of forced outages of B&W operating plants since 1980. See Enclosure 4. This committee plans to issue a report on their findings to the members of the B&WOG by the end of October.
This report will be updated simi-annually. Other major programs of this committee include the following:
- 1. A Turbine Trip Reduction Program - A draft report to the B&W0G members is expected by the end of October. The report will identify and recommend programs to eliminate root causes of main turbine trip.
- 2. A Feedwater Pump Trip Reduction Program - Preliminary findings indicate trips due to human error are trending upwards.
- 3. A Planned Outage Reduction Improvement Program - This program identifies and undertakes projects aimed at reducing the duration of planned outages.
4 A Reactor Trip System Test Intervtl Expansion Proposal -
Implementation of this proposal is expected to reduce spurious reactor trips.
8511010225 051017 PDR ADOCK050g9 P
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The Transient Assessment Committee has produced and extensive data base from over 200 transient events which is shared with the B&WOG members and is analyzed to determine the effort aimed at reducing reactor trips. The report is available to the members but is not available to the staff excep as the B&WOG allows it to be available. See Enclosure 5. Trips caused by Main Feedwater trips and Main Turbine trips are major causes of reactor trips (approximately 10% of all trips). Large contributors of the reactor trips are associated with high pressure trips and anticipatory turbine trips. The committee believes that these trips could be reduced by raising the high pressure set point and raising the arming set point for anticipatory turbine tri p. The B&WOG intends to propose this in a topical report for staff review and approval. The propose set point change would raise the high pressure trip set point to 2355 psig. The current set point is 2300 psig. The PORV set point would remain the same at 2400 psig. See Enclosures 6, 7 and 8.
ctY".at dW af Guy S. Vissing, Project Manager Operating Reactors Branch E4 Division of Licensing ORly L GM ing;cr 10/ / /85
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ENCLOSURE 1 ATTENDANCE LIST FOR B&WOG MEETING 0F 10/4/85 NAME ORGANIZATION Walter A. Paulson Project Manager, DL/NRR Guy S. Vissing Project Manager, DL/NRR Dennis Crutchfield Ast. Director, DL/NRR Cecil 0. Thomas Branch Chief, DL/NRR Robert C. Jones RSB/DSI/NRR A. Thadani Branch Chief, DST /NRR N. Lauben RSB/DSI/NRR James Taylor Babcock and Wilcox R. Borsum Babcock and Wilcox R. P. Wichert B&WOG Availability Committee (SMUD)
L. Kolonay Babcock and Wilcox W. K. Baudhauer B&WOG Transient Assessment Program (TAP) Committee S. T. Rose B&WOG TAP Chairman
AGENDA FOR B&WOG/NRC MEETING ON INCREASING UNIT PRODUCTIVITY OCTOBER 4,1985 J. W. LANGENBACH ( GPU NUCLEAR )
- REVIEW OF B&WOG PRODUCTIVITY IMPROVEMENT GOALS R. P. WICHERT ( SMUD )
- AVAILABILITY COMMITTEE REVIEW
- REVIEW OF B&W PLANT PERFORMANCE 1980 - 1985
- STATUS OF B&WOG AVAILABILITY IMPROVEMENT PROJECTS
- PLANS FOR 1985 -1986 W. K. BANDHAUER ( FLORIDA POWER CORPORATION )
- TRANSIENT ASSESSMENT COMMITTEE OVERVIEW
- B&WOG REACTOR TRIP EXPERIENCE FOR 1984
- B&WOG REACTOR TRIP REDUCTION PROGRAM
- STATUS OF TRIP REDUCTION EFFORTS
- PLANS FOR 1985-86 S. T. ROSE ( DUKE POWER )
L. M. KOLONAY ( B&W )
- JUSTIFICATION FOR RAISING SETPOINTS FOR REACTOR TRIP ON HIGH PRESSURE AND TURBINE TRIP ARTS
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MR_ME_M_0.@.U.P.
._________UULU.Y______________________ _____P_L ART.__________ __ _
ARKANSAS POWER & LIGHT COMPANY ANO-1 DUKE POWER COMPANY OCONEE 1, 2, 3 FLORIDA POWER CORPORATION CRYSTAL RIVER 3 GPU NUCLEAR TMI-i SACRAMENTO MUNICIPAL UTILITY DISTRICT RANCHO SECO TOLEDO EDISON COMPANY DAVIS BESSE TENNESSEE VALLEY AUTHORITY BELLEFONTE 1, 2 WASHINGTON PUBLIC POWER SUPPLY SYSTEM WNP 1 BABC0CK & WILC0X COMPANY
B & W OWNERS GROUP ORGANIZATION EXECUTIVE ,
COMMITTEE OWNERS CROUP STEERING COMMITTEE ,
1 TASK FORCES / ANALYSIS AVAILABILITY WORKING CROUPS TRANSIENT ASSESSMENT CORE TECH SPEC.
COMMITTEE COMMITTEE COMMITTEE COMMITTEE i COMMITTEE
--Life Extension
--Instrumentation
-Leak Before Break m
NDE MATERIALS OPERATOR SUPPORT ATWS COMMITTEE COMMITTEE STEAM COMMITTEE COMMITTEE CENERATOR COMMITTEE
E80AGUYLQBJEGUYLLG0AklLTlNG 0 B&WOG OBJECTIVEIG0ALS FOR 1985/86 PROACTIVELY ESTABLISHED IN 1984 0 OBJECTIVE FOR PRODUCTIVITY IMPROVEMENT INCREASE THE PRODUCTIVITY OF THE B&WOG UNITS SO AS TO PROVIDE A SAFE, RELIABLE AND ECONOMICAL SJPPLY 0F ENERGY o G0ALS ESTABLISHED TO SUPPORT OBJECTIVE i 0 WORKING PLANS FORMULATED TO ACCOMPLISH G0ALS I
- , . - - . . ,- - . - , , - , , , . - ~ . , . , - - - . . - - , . . . - - , - - - - - - . - - , - - - , - - - - - ,
B&W91_193Jil65.28QDilGIIYIILIttP8QdtiGL1Q6LS o EVALUATE AND RECOMMEND PROGRAMS AIMED AT REDUCING THE AVERAGE NUMBER OF TRIPS PER PLANT IN SUPPORT OF ESTABLISHED NUMARC SCRAM REDUCTION G0ALS.
0 EVALUATE AND RECOMMEND BY 1985 PROGRAMS AIMED AT INCREASING THE CAPACITY FACTOR OF B&W UNITS o EVALUATE B&W INTERFACE ASSOCIATED WITH OUTAGES AND MAKE RECOMMENDATIONS BY THE END OF 1985 TO MINIMIZE OUTAGE DURATIONS o EVALUATE PRESENT OPERATING MARGINS OF B&W UNITS FOR EXISTING PROBLEM AREAS AND RECOMMEND COST-EFFECTIVE SOLUTIONS THAT CAN BE IMPLEMENTED WITHIN THE NEXT TWO YEARS.
. . . _ . _ . _ - . ~_. __ _ - .. -- - .-. -_.. - . . _ . .
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- B&W OWNERS GROUP i
I AVAILABILITY COMMITTEE I
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ORGANIZATION i 1 a
I OBJECTIVES 4
J SUPPORT OF B&WO6 60ALS i i
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THE AVAILABILITY COMMtI it2.
WAS FORMED IN 1983 AS A STANDING COMMITTEE OF THE B&W OWNERS GROUP EXECtmVE COMMITTEE OWNERS GROUP STEERNG COWh5TTEE AVAILABILITY _
COMh5TTEE l
D
i MAJOR OBJECTIVES OF THE AVAILABILITY COMMITTEE INCLUDE:
1
- IDENTIFY AND PRIORITIZE AVAILABILITY ISSUES
- FOR SELECTED ISSUES, FORMULATE PROGRAMS TO ACHIEVE RESOLUTION i
- PROVIDE FOR TRACKING OF PROGRAM RESULTS i
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1
, l AVAILABILITY COMMITTEE ASSIGNED G0ALS
- EVALUATE AND RECOMMEND PROGRAMS AIMED AT INCREASING THE CAPACITY FACTOR OF B&W UNITS
- EVALUATE AND RECOMMEND PROGRAMS AIMED AT REDUCING THE AVERAGE NUMBER OF TRIPS PER PLANT (RESPONSIBILITY SHARED WITH TRANSIENT ASSESSMENT COMMITTEE)
- EVALUATE PROBLEM AREAS ASSOCIATED WITH PLANNED OUTAGES AND MAKE RECOMMENDATIONS TO MINIMIZE OUTAGE DURATION l
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3 I
REVIEW 0F B&W PLANT PERFORMANCE 1980 - 1985 l
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Unit Availability Fa cto rs For the B&W Units .
1980-1983 1
gg..
l ao- -
l 7o- -
67.57 60.45 1 oo "
57.5 so- -
.e
" so - -
so- - '
so- -
to-i 1980 1981 1982 1983 Yeor l
Unit A vailability Factors For the B&W Units -
1980-1984 es..
i 88*
- 77 47 7ea -
97,37 l
S3.22 N' "
57.5 ee. .
4e- -
30- -
se- -
l se- -
i 1980 1981 1982 1983 1984 .
Year
~
Unit Availability Fa cto rs For the B&W Units ~
1980-June 1985 se- -
77,47
"" '7 "7 au SO.45 80-20- -
10- -
isso isai iss2 inas ina4 inas l Year
Unit Availability and Outage Factors For the B&W Units, 1980-1983 -
Avail.
/ 62.2%
I 21.5% Forced Out.16.3%
Planned Out.
I OC"Or 1
Unit Availability and Outage Factors For the B&W Units in 1984 ~
f Avail.
77.5%
/ 14%
A Forced Out. 8.6%
// Planned Out.
f TOCtOr
AVERAGE PLANNED & FORCED OUTAGE FACTORS FOR THE B&W U NITS 1980 - JUNE 1985 50--
c5-- y FORCED q.-
5 M M PLANNED Y -
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~ 35--
- y a
P) 9 O 30--
6
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1980 1981 1982 1983 1984 1985 '
YEAR
I TABLE 1 CAUSES OF FORCED OUTAGES RANKED ACCORDING TO FORCED OUTAGE FACTOR (F0F)* FOR 1984 Bate # OF F0F CAUSE EVENTS (7d
- 1 SG TUBE LEAKS 4 4.31 2
EXCITER H2 EXPLOSION 3
1 1.25 INOPERABLE CONTAIN RECIRC. FAN 4
1 0.63 RCS SWAGELOK FITTING PROBLEM 1 0.55 5 BD XFRMR. CONNECTION FAILURE 6
1 0.34 MSSV FAILED OPEN
- 7 1 0.23 TURBINE BEARING VIBRATIONS 3 8 0.19 H2 SEAL OIL SYSTEM PROBLEM 1 0.17
- 11 1 0.10 FWP PROBLEMS / TRIPS 3 12 0.09 PZR MINI-SPRAY VALVE PACKING LEAK 1 0.08 13 DEMIN. VALVE AIR SUPPLY 14 1 0.08 RCP SEAL PRESS. SENSING LINE LEAK 1 0.08
- PROGRAM TO ADDRESS PROBLEM IS UNDERWAY BY B&WOG.
STATUS OF B&WOG AVAILABILITY IMPROVEMENT PROJECTS O
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m B&WOG AVAILABILITY IMPROVEMENT PROJECTS
- AVAILABILITY EXPERIENCE REPORT
- TURBINE TRIP REDUCTION
- FEEDWATER PUMP TRIP REDUCTION
- RCP MOTOR OIL PROBLEMS
- REACTOR BUILDI,NG ENTRY LIMITS
- PLANNED OUTAGE IMPROVEMENT
- REACTOR TRIP SYSTEM TEST INTERVAL EXTENSION
B&WO6 AVAILABILITY EXPERIENCE REPORT OBJECTIVE:
- MONITOR AND TREND AVAILABILITY FOR B&W UNITS AS A GROUP
- IDENTIFY POSSIBLE AVAILABILITY IMPROVEMENTS
- TRACK THE EFFECTIVENESS OF IMPLEMENTED CHANGES- -
EXPECTED BENEFITS:
THIS PROGRAM WILL PROVIDE GUIDANCE FOR SELECTION OF GENERIC PROJECTS WITH GOOD POTENTIAL FOR AVAILABILITY IMPROVEMENT APPROACH:
- SELECT DATA SOURCE COPEC-II VIA INP0)
- MONITOR AND TREND AVAILABILITi
- ANALYZE DATA AND DEVELOP RECOMME'4DATIONS FOR IMPROVEMENT PROJECTS
- ISSUE REPORTS SEMI-ANNUALLY STATUS:
- FIRST REPORT TO BE ISSUED END OF OCTOBER I
TURBINE TRIP REDUCTION 4
OBJECTIVE:
IDENTIFY AND RECOMMEND PROGRAMS TO ELIMINATE ROOT CAUSES FOR MAIN TURBINE iRIPS EXPECTED BENEF'TS:
REDUCTION IN REACTOR TRIPS AND IMPROVEMENT IN AVAILABILITY APPROACH:
- COMPILE ENGINEERING AND OPERATING EXPERIENCE DATA
- ANALYZE DATA FOR TRENDS AND PATTERNS
- IDENTIFY ROOT CAUSES FOR TRIPS
- DEVELOP REC 0hMENDATIONS FOR ROOT CAUSE ELIMINATION STATUS:
- DRAFT REPORT EXPECTED FROM PICKARD, LOWE & GARRICK END OF OCTOBER l
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FEEDWATER PUMP TRIP REDUCTION OBJECTIVE:
IDENTIFY AND RECOMMEND PROGRAMS TO ELIMINATE ROOT CAUSES FOR MAIN FEEDWATER PUMP TRIPS APPROACH:
- COMPILE ENGINEERING AND OPERATING EXPERIENCE DATA
- IDENTIFY ROOT CAUSES FOR TRIPS
- DEVELOP RECOMMENDATIONS FOR I.00T CAUSE ELIMINATION EXPECTED BENEFITS: .
- REDUCTION IN FEEDPUMP TRIPS AND RESULTING FEEDWATER UPSETS
- REDUCTION IN REACTOR TRIPS DUE TO FEEDWATER UPSETS
- AVAILABILITY IMPROVEMENT ,
STATUS:
- PRELIMINARY FINDINGS e TRIPS DUE TO HUMAN ERROR ARE TRENDING UPWARD e TRIPS DUE TO EQUIPMENT PROBLEMS NOT INCREASING e MAJOR TRIP CAUSES ARE LOW OIL PRESSURE AND LOW SUCTION PRESSURE e APPLICATION OF PRESSURE SWITCHES NEEDS FURTHER INVESTIGATION
l-
- PLANNED OUTAGE IMPROVEMENT OBJECTIVE:
IDENTIFY AND UNDERTAKE PROJECTS AIMED AT REDUCING THE DURATION OF PLANNED OUTAGEt LXPECTED BENEFITS:
IMPROVED AVAILABILITY APPROACH:
- ASSEMBLE UTILITY EXPERTS (0UTAGE MANAGERS AND PLANNERS) FOR OUTAGE EXPERIENCE CONFERENCE
- PRIORITIZE OUTAGE IMPROVEMENT IDEAS
- DEVELOP PROJECTS BASED ON HIGHEST PRIORITY ITEMS STATUS:
- B&WOS OUTAGE MANAGEMENT EXPERIENCE CONFERENCE WAS HELD SEPTEMBER 23-25, 1985
- AVAILABILITY COMMITTEE IDENTIFIED ITEMS FOR COMMITTEE ACTION
- ACTION PLANS UNDER DEVELOPMENT FOR TOP TEN ITEMS l
RCP MOTOR OIL PR03 LENS OBJECTIVE:
IDENTIFY ROOT CAUSES FOR PROBLEMS ASSOCIATED WITH REACTOR COOLANT PUMP MOTOR OIL LEAKAGE AND DEVELOP RECOMMENDATIONS FOR ELIMINATION EXPECTED BENEFITS:
AVAILABILITY IMPROVEMENT BY ELIMINATION OF NEED TO SHUTDOWN OR REDUCE POWER FOR 011. ADDITION APPROACH:
- COLLECT ENGINEERING AND OPERATING EXPERIENCE DATA
- DEVELOP RECOMMENDATIONS FOR ROOT CAUSE ELIMINATION STATUS:
- PRELIMINARY FINDINGS FROM B&W INDICATE INSTRUMENTATION AND MAINTENANCE COULD BE PROBLEM AREAS l
I REACTOR BUILDING ENTRY LIMITS REVIEW OBJECTIVE:
DETERMINE THE CAUSE AND EXTENT OF LIMITATIONS WHICH DELAY ENTRY INTO THE REACTOR BUILDING FOR SCHEDULED OUTAGES AND DEVELOP RECOMMENDATIONS FOR REDUCING THE DELAYS EXPECTED BENEFill:
AVAILABILITY IMPROVEMENT BY REDUCTION IN PLANNED OUTAGE DURATION APPROACH:
- COLLECT UTILITY DATA ON CAUSES AND EXTENT OF BUILDING ENTRY DELAYS
- DEVELOP RECOMMENDATIONS FOR REDUCING DELAYS STATUS:
- DRAFT REPORT EXPECTED FROM STONE AND WEBSTER DECEMBER '85 l
- O REACTOR TRIP SYSTEM TEST INTERVAL EXTENSION OBJECTIVE:
DEVELOP JUSTIFICATION FOR EXTENDING SURVEILLANCE TEST INTERVAL FOR THE REACTOR TRIP SYSTEM (RTS) BEYOND THE CURRENT ONE MONTH EXPECTEI BENEFITS:
REDUCTION IN SPURIOUS REACTOR TRIPS AND REDUCTION IN RESOURCE REQUIREMENTS FOR TESTING APPROACH:
DEMONSTRATE BY ANALYSIS THAT RTS RELIABILITY AND IMPACT ON CORE MELT FREQUENCY ARE ACCEPTABLE AT TEST INTERVALS GREATER THAN ONE MONTH STATUS:
- RTS RELIABILITY STUDIES AT LONGER INTERVALS IS COMPLETE ;
- ANALYSIS OF IMPACT ON CORE MELT FREQUENCY IS IN PROGRESS I
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B&WOG AVAILABILITY COMMITTEE PLANS FOR '85 '86 l
e CONTINUE TO IDENTIFY OPPORTUNITIES FOR AVAILABILITY IMPROVEMENT IN THE FORCED OUTAGE AREA e ACTIVELY PURSUE PROJECTS AIMED AT SHORTENING PLANNED OUTAGES
- ESTABLISH SYSTEM FOR TIMELY SHARING 0F CURRENT PLANNED OUTAGE EXPERIENCE
- DEVELOP CONTINGENCY PLANS FOR POTENTIAL PROBLEMS WHICH COULD HAVE MAJOR IMPACT ON FUTURE OUTAGES
- DEVELOP MEANS TO CAPTURE AND COMMUNICATE OUTAGE EXPERIENCE HISTORY
- IDENTIFY COMMON ACTIVITIES ASSOCIATED WITH OUTAGES AND ANALYZE UTILITY EXPERIENCE TO IDENTIFY OPPORTUNITIES FOR IMPROVEMENT ,
- IDENTIFY AND SHARE EXPERIENCE ON MAINTENANCE AND MODIFICATION WORK CURRENTLY DONE ON-LINE
- IDENTIFY ACTIVITIES BEING HANDLED BY ACTIVITY C0ORDINATORS AND BUILDING C0ORDINATORS AT VARIOUS UTILITIES l
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i B&WOG AVAILABILITY COMMITTEE PLANS FOR '85 '86 (CONTINUED) l
- EVALUATE STATUS AND FUTURE DIRECTION OF POOLED INVENTORY MANAGEMENT SYSTEM (PIMS) RELATIVE TO OUTAGE SUPPORT
- DEVELOP AN EFFECTIVE MEANS TO IDENTIFY AND COMMUNICATE LESSONS LEARNED COMMUNICATE TO OTHER OWNERS GROUP ORGANIZATIONS THE NEED TO INTEGRATE LICENSING COMMITMENTS WITH OUTAGE IMPROVEMENT EFFORTS IDENTIFY GOOD PREVENTIVE MAINTENANCE PRACTICES FOR KEY EQUIPMENT REQUIRED FOR OUTAGES
T. 6 4ro-c f TRANSIENT ASSESSME.iT PROGRAM OVERVIEW t
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o e TRANSIENT ASSESSMENT PROGRAM PURPOSE TAP WAS ESTABLISHED BY THE B&W OWNERS GROUP TO SHARE OPERATING EXPERIENCE AND PLANT TRANSIENT INFORMATION AMONG PROGRAM MEMBERS.
. IN ITS SIX YEAR EXISTENCE, THE TAP HAS PRODUCED AN EXTENSIVE DATA BASE, INCLUDING INFORMATION FROM REPORTS FOR MORE THAN 200 TRANSIENT EVENTS.
THIS INFORMATION, WHICH INDICATES WHAT HAS AND WHAT IS CAUSING TRIPS AT B&W PLANTS, IS THE BASIS FOR EFFORTS AIMED AT REDUCING REACTOR TRIPS.
e
6 TRANSIENT ASSESSMENT PROGRAM PLANT TRANSIENT if (TAP REPRESENTATIVE)
B&W ASSISTANCE i DESIRED -
- NO YES
~
8&W SITE VIS T TEAM ASSISTS UTILITYCONDUCTSEVALUATIOk,
- UTILITY IN TIANS! EAT EVALUATION DRAFTS REPORT AND FORWARDS AND REPORT PI(EPARATION TO BsW FOR DISTRIBUTION UTILITY RELEASES REPORT TO B&W FOR DISTRIBUTION lf B&W OISTRIBUTES TRANSIENT ASSESSMENT I
REPORT TO ALL PARTICIPATING 177 FA OWNERS
~~
lf EACH UTILITY REVIEWS REPORT FOR APPLICABILITY if .
B&W PROVIDE OPEPATINt. UTILITIES AND 8&W CONDUCT EXPERIENCE
SUMMARY
PERIODIC OPERATING REPORTS TO PROGRAM EXPERIENCE SEMINARS PARTICIPANTS p _ _ _ __ _ _ __ _ _ _ _
y l TAF COMMITTEE DEVELOPS RECONMENDATIONS l FOR GENERIC IMPROVEMENTS l_ __ _ __ _J
. o PROGRAM BENEFITS TAP IS THE BEST SOURCE AVAILABLE FOR EXCHANGE OF DETAILED 0PERATING EXPERIENCE INFORMATION PROVIDES A MEANS TO INCORPORATE OPERATING EXPERIENCE INTO PLANT DESIGN AND OPERATION PROVIDES OPERATING FEEDBACK FROM THE PLANTS INT 0 OTHER B&WOG PROGRAMS PROVIDES INPUT TO THE EVALUATION PROCESS FROM THE DESIGNERS VIEWP0 INT PROVIDES DIRECTION FOR FUTURE OWNERS GROUP PROGRAMS TO IMPROVE PLANT PERFORMANCE, INCLUDING TRIP REDUCTION
O e B8WOG REACTOR TRIP EXPERIENCE FOR 198L1 I
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TRIP AVERAGES FOR B&W PLANTS l 6.8 6.3 l
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g.. ...
.. = =
l TRIPS PER RX-YR FOR B&W PLANTS 1 ..-
18.5-1 l 13.0- .
i so.s - -
10.2 10.2 j go. .
I 7.9 v.s- -
! d 4.s - -
E 3.6 s.e - -
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80 81 82 83 84
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MAJOR FACTORS CONTRIBUTING TO 1984 RECORD:
REDUCTION IN TURBINE TRIPS AT OCONEE UNITS it REDUCTION IN HIGH PRESSURE TRIPS AT CR-3 REDUCTION IN POWER / FLOW / IMBALANCE TRIPS AT DAVIS-BESSE FEWER PLANTS STARTING UP AFTER REFUELING AND MODIFICATION OUTABES l
l
REDUCTION IN TURBINE TRIPS AT OCONEE UNITS REDUCTION ACHIEVED 1980-83 2 8 TRIPS / UNIT /YR.
1984 7 TRIPS / UNIT /YR.
FACTORS CONTRIBUTING TO REDUCTION
- MODIFICATIONS TO AVOID TURBINE TRIP ON M0MENTARY LOSS OF POWER TO EHC
- CHANGED FREQUENCY OF SWAPPING MOISTURE SEPARATOR DRAIN TANK (MSDT) PUMPS TO REDUCE PROBABILITY OF MSDT HIGH LEVEL TRIPS
- INCREASED FREQUENCY OF STR0KE TESTING MSDT DUMP YALVES l
l 1
i
REDUCTION IN HIGH PRESSURE TRIPS AT CRYSTAL RIVER-3 REDUCTION ACHIEVED 1980-83 5 3 TRIPS /YR.
1984 1 TRIP FACTORS CONTRIBUTING TO REDUCTION
- INCREASED EMPHASIS ON INSURING FEEDWATER SYSTEM IS READY FOR OPERATION FOLLOWING AN OUTAGE
- ESTABLISHMENT OF SIX OPERATING SHIFTS INSTEAD OF FIVE
- INITIATION OF A RELIABILITY-CENTERED MAINTENANCE PROGRAM l - INCREASED EMPHASIS ON USE OF AN IN-HOUSE INDUSTRY EXPERIENCE REVIEW GROUP
- INSTALLATION OF IMPROVED DATA COLLECTION EQUIPMENT TO AID IN ROOT CAUSE DETERMINATION
i REDUCTION IN POWER / FLOW / IMBALANCE TRIPS AT DAVIS-BESSE REDUCTION ACHIEVED 1983 4 TRIPS 1984 1 TRIP FACTORS CONTRIBUTING TO REDUCTION
- CHANGED AUTOMATIC RUNBACK RATE ON ASYMMETRIC R0D CONDITION TO 3%/ MINUTE (FROM ORIGINAL 30%/ MIN.)
- IMPLEMENTED CONTROL R0D DRIVE (CRD) FUSE' INSPECTION PROGRAM TO REDUCE DROPPED R0D EVENTS CAUSED BY FUSE FAILURES
- PERFORMED COMPLETE CLEANING OF CRDCS CABINETS r
s a t
FEWER PLANTS STARTING UP AFTER REFUELING OUTAGES e
START-UPS AFTER REFUELING OUTAGES 1980-83 AVERAGE 5 PLANTS /YR.
1984 2 PLANTS ANALYSIS OF TAP DATA SHOWS THAT 4-5 TIMES AS MANY TRIPS OCCUR IN FIRST WEEK AFTER OUTAGE THAN ANY SUCCEEDING WEEK D
TRIPS AFTER REFUELING OUTAGES as -
E e.. .
so- -
, no- -
9 p p -
p p p -
p o .
, <=1 2 3 4 5 6 .7 8 9 10 11 12 WEEKS AFTER OUTAGE
e B8WOG REACTOR TR..P REDUCTION PROGRAM 4
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TRIP REDUCTION APPROACH PROGRAM CONSISTS OF GENERIC EFFORTS WHICH ARE IN ADDITION TO INDIVIDUAL UTILITY ACTIVITIES GENERIC ITEMS WERE SELECTED BASED ON COLLECTIVE OPERATING EXPERIENCE DOCUMENTED BY TAP PROGRAM ITEMS INCLUDE BOTH TRIP AY01 DANCE AND ROOT CAUSE ELIMINATION EFFORTS __
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TRIP AVOIDANCE EFFORTS
- RAISE HIGH PRESSURE TRIP SETP0 INT TO ORIGINAL SAFETY ANALYSIS VALUE
- RAISE ARMING THRESH 0LD FOR ANTICIPATORY REACTOR TRIP ON TURBINE TRIP
- IMPROVE ICS RESPONSE TO PLANT UPSET CONDITIONS
- IMPROVE ICS RESPONSE TO INPUT FAILURES
O e i
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ROOT CAUSE ELIMINATION EFFORTS
- MAIN FEEDWATER PUMP TRIP REDUCTION I
MAIN TURBINE TRIP REDUCTION 4
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, , , . , - - - _ , , _ . . - . . .-.._.--.y.,__,_ _ _ ~ ___, , _. . - _.. ,
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STATUS OF TRIP REDUCTION EFFORTS
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RAISE HIGH PRESSURE TRIP SETPOINT OBJECTIVE: DEVELOP JUSTIFICATION FOR RAISING THE SETP0 INT FOR R.EACTOR TRIP ON HIGH PRESSURE FROM CURRENT NOMINAL 2300 PSIG TO ORIGINAL 2355 PSIG.
EXPECTED BENEFITS: A REDUCTION IN HIGH PRESSURE TRIPS NOW CAUSED BY MINOR FEEDWATER UPSETS AND OTHER SLOW MOVING TRANSIENTS.
APPROACH: DEMONSTRATE BY ANALYSIS AND EVALUATION OF PLANT DATA THAT THE PROBABILITY OF OPENING THE PORY DURING AN OVERPRESSURE TRANSIENT WILL REMAIN ACCEPTABLY LOW WITH A REACTOR TRIP SETPOINT OF 2355 PSIG.
STATUS: ANALYSIS HAS BEEN COMPLETED. RESULTS SHOW THAT RAISING THE HIGH PRESSURE TRIP SETPOINT TO 2355 PSIG WILL HAVE NEGLIGIBLE IMPACT ON OVERALL PORY OPENING FREQUENCY.
i e
l RAISE ARMING THRESH 0LD FOR ANTICIPATORY REACTOR TRIP (ART) ON TURBINE TRIP OBJECTIVE: DEVELOP JUSTIFICATION FOR RAISING THE ARMING THRESHOLD FOR THE TURBINE TRIP ART HIGHER THAN THE CURRENT 20%
POWER LEVEL.
EXPECTED BENEFITS: A REDUCTION IN REACTOR TRIPS NOW CAUSED BY TURBINE TRIPS AT LOWER POWER LEVELS.
APPROACH: PERFORM AN ENGINEERING EVALUATION TO DETERMINE THE MAXIMUM POWER LEVEL FROM WHICH A SUCCESSFUL RUNBACK ON TURBINE TRIP COULD BE ACHIEVED.
STATUS: ENGINEERING EVALUATION HAS BEEN COMPLETED. RESULTS SHOW .
THAT B&W PLANTS COULD SURVIVE TURBINE TRIPS FROM 25 TO 30% POWER WITH THE CURRENT HIGH PRESSURE TRIP SETPOINT. HIGHER POWER LEVELS COULD BE ACCOMMODATED,WITH A 2355 PSIG SETPOINT.
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,, e ,- - - - - . , - - . ,
IMPROVE ICS RESPONSE TO PLANT UPSET CONDITIONS OBJECTIVE: IDENTIFY MODIFICATIONS TO ICS DESIGN FEATURES WHICH WILL IMPROVE THE PROBABILITY OF SUCCESSFUL RUNBACK ACTIONS AND REDUCE THE PROBABILITY OF INAPPROPRIATE CONTROL ACTIONS.
EXPECTED BENEFITS: A REDUCTION IN REACTOR TRIPS NOW CAUSED BY UNS'JCCESSFUL RUNBACK ACTIONS OR INAPPROPRIATE CONTROL ACTIONS.
APPROACH: IDENTIFY CANDIDATE MODIFICATIONS AND DEMONSTRATE THEIR EFFECTIVENESS BY ANALYSIS AND SIMULATION.
STATUS: ENGINEERING EVALUATION IS ONG0ING. PRELIMINARY RESULTS SHOW:
- BTU LIMITS FUNCTION CAN BE REMOVED
- CHANCES FOR SUCCESSFUL RUNBACK ON LOSS OF ONE FEED PUMP CAN BE IMPROVED BY CHANGES IN RUNBACK RATE AND TARGET LEVEL
- FEED PUMP SPEED CONTROL CAN BE IMPROVED BY ADJUSTMENTS TO CONTROLLER CONSTANTS i
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IMPROVE ICS RESPONSE TO FAILED INPUTS OBJECTIVE: IDENTIFY MODIFICATIONS TO REDUCE FREQUENCY OF INAPPROPRIATE CONTROL ACTIONS DUE TO FAILED INPUT SIGNALS.
EXPECTED BENEFITS: REDUCTION IN REACTOR TRIPS N0W CAUSED BY FAILURES OF SINGLE INPUTS TO THE ICS.
APPROACH: IDENTIFY TROUBLES 0ME SIGNALS AND DEVELOP MODIFICATIONS TO IMPROVE RELIABILITY SUCH AS:
- ELIMINATION OF SIGNALS PROVIDING MARGINAL BENEFIT
- REPLACEMENT OF UNRELIABLE INPUTS WITH EXISTING MORE RELIABLE SIGNALS
- IMPROVE UTILIZATION OF EXISTING REDUNDANT INFORMATION STATUS: ENGINEERING EVALUATION IS ONG0ING. PRELIMINARY RESULTS ARE: '
- RC FLOW SIGNAL CAN BE REPLACED WITH EXISTING PUMP STATUS INPUTS
- START UP FW FLOW CAN:BE ELIMINATED AS CONTROL INPUT FOR SOME PLANTS
- FEEDWATER TEMPERATURE INPUT HAS MINOR INCREMENTAL BENEFIT 1
TRANSIENT ASSESSMENT COMMITTEE PLANS FOR 1985-86 COMPLETE CURRENT STUDIES AND IMPLEMENT RECOMMENDATIONS
- CONTINUE EFFORTS TO IDENTIFY FURTHER TRIP REDUCTION OPPORTUNITIES
- INITIATE EFFORTS TO IDENTIFY CAUSES OF TRIPS DURING OUTAGE STARTUPS 4
DEVELOP GENERIC TRANSIENT LOGGING GUIDELINES FOR USE IN PLANT LIFE EXTENSION PROGRAM i - CONTINUE TRANSIENT ASSESSMENT PROGRAM AND STRENGTHEN IN AREAS OF:
ROOT CAUSE DETERMINATION IDENTIFICATION OF GENERIC RECOMMENDATIONS l
TRACKING OF RECOMMENDATIONS
fn e A rv,c c l
B&W OWNERS GROUP TRIP REDUCTION PROGRAM OVERVIEW OF JUSTIFICATION FOR RAISING SETPOINT FOR 1 REACTOR TRIP ON HIGH PRESSURE AND l
INCREASING ART THRESHOLD t
i _ _ . . -. _ _. _ -- _.
i MOTIVATION FOR SEEKING CHANGE:
REDUCE REACTOR TRIPS 1
REDUCE CHALLENGES TO SAFETY SYSTEMS IMPROVE TRANSIENT PERFORMANCE l
BACKGROUND e BtW NSSS DESIGNED WITH RUNBACK CAPABILITY TO ALLOW PLANT UPSETS WITHOUT REACTOR TRIP
- ICS
- 0TSG e POST-TMI CHANGES TO REDUCE PORY CHALLENGES DRASTICALLY REDUCED RUNBACK CAPABILITY
- PORY SETPOINT RAISED TO 2450 PSIG
- HIGH PRESSURE TRIP LOWERED TO 2300 PSIG
- TURBINE TRIP ART e OPERATING EXPERIENCE INDICATES THAT POST-TMI CHANGES WERE OVERLY CONSERVATIVE
- NO AUTOMATIC PORY OPENING IN 35 REACTOR-YEARS OPERATION e PARTIAL RESTORATION OF RUNBACK CAPABILITY IS POSSIBLE THROUGH ELIMINATION 0F EXCESS CONSERVATISM IN HIGH PRESSURE AND ART SETPOINTS WITHOUT CHANGING PORV SETPOINT
- 9 IMPACT OF POST-TMI CHANGES i
_ + Z,, m O 4 SUCCESSFUL RUNBACK ACTIONS (PRE-1979)
INITIAL POWER FINAL POWER EVENT HD. RANGE RANGE %
TURBINE TRIP / LOAD REJECTION 14 15-100 2-22 FEED PUMP TRIPS (1 0F 2) 14 100 55-75 R0D DROPS 4 100 50-60 10% STEP LOAD INCREASES 4 17-90 27-100 10% STEP LOAD DECREASES 11 37-100 15-90 TOTAL 47 DATA FOR ONE STATION J
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I l AVERAGE NUMDER OF HIGH PRESS. TRIPS PER YEAR i .--
! LEGEND 4.e - -
b
- PRE '79 POST '79 s.s- -
e.
=
a s.s - -
N. .
m a g
am aa 1.s - -
q
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- PRE '79 INCLUDES YEARS OF COMM. OPERATION '73 D4RU '78 i __ ___.____ ____________ _ _ - . _ _ - - _ _ _ _ _ _ _ _ . - ____ ____ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
l AVERAGE NUMBER OF HIGH PRESSURE AND ARTS TRIPS PER YEAR
- " 5 LEGEND -
- PRE '79 1 gost ,9 l
1 ~ ,
- g. .
l I l R .- -
- UNIT ~
!
- PRE '79 INCLUDES YEARS OF COMM. OPERATION '73 THRU '78
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I POTENTIAL FOR TRIP REDUCTION I
INCREASING MARGIN TO HIGH PRESSURE TRIP WOULD :
1 REDUCE CHALLENGES TO SAFETY SYSTEMS ALLOW MORE TIME FOR RECOVERY BY OPERATOR INCREASE PROBABILITY FOR SUCCESSFUL AUTOMATIC RUNBACKS (e.g., MFWP TRIPS) 1 INCREASE BENEFITS OF RAISING TURBINE TRIP ART SETPOINT j
l 4
.,,--._,_.,,.-,..,_,..._-__,,_,_,-.,-._._,m-_
4
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l ANTICIPATORY REACTOR TRIPS
- ON TURBINE TRIP FOR B&W PLANTS I
{ 1980-1984 i se l
as. .
25 M" "
!I I
e >
11 so- -
I i
, S*
- i 3 3 tV /A
. Q
- o-so 31-4o 4t-so st-so ex-vo vi-so ex-se ex-too l p INITIAL POWER LEVEL -
i _
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l 24 OF THE 186 TRIPS WHICH OCCURRED DURING '80 '84 MAY HAVE BEEN AVOIDED WITH THE HIGHER SETPOINTS.
ASSUMING FUTURE MIX OF TRANSIENTS SIMILAR TO
'80 '84, A 10% REDUCTION IN TRIPS / YEAR IS PROJECTED
IMPACT ON PORY OPENING FREQUENCY o PORY OPENING FREQUENCY CONTRIBUTION FROM OVERPRESSURE TRANSIENTS IS RELATIVELY SMALL i
e CHANGE IN HIGH PRESSURE TRIP SETPOINT DOES NOT AFFECT OPENING FREQUENCY FOR OTHER EVENTS e OVERALL PORY OPENING FREQUENCY IS ESSENTIALLY THE SAME WHETHER THE TRIP SETPOINT IS 2300 OR 2355 PSIG I
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TABLE 3-1. PORV OPENING FREQUENCY -
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OPENING PER REACTOR YEAR TER CURRENT STUDY OVERPRESSURE TRANSIENTS 2.2x10-3 2x10-5 TRANSIENTS WITH DELAYED AUXILIARY FEEDWATER 7.6x10-4 NO CHANGE OPERATOR ACTIONS UNDER ATOG 7.7x10-2 NO CHANGE l& C FAULTS 1.7x10-3 NO CHANGE OVERCOOLING TRANSIENTS
- THAT INITIATE H P I 8.28x10-4 NO CHANGE TOTAL 8.28x10-2 8.06x10-2 FRANKLIN LAB STUDY TER-C5506-410 l
1
SUMMARY
- RAISING THE HIGH PRESSURE TRIP SETPOINT TO 2355 PSIG CAN RESULT IN A SUBSTANTIAL REDUCTION IN REACTOR TRIPS
- THE BENEFIT CAN BE ACHIEVED WITH A NEGLIGIBLE IMPACT ON PORV OPENING FREQUENCY (MAINTAINING CURRENT
- OPENING SETPOINT) 1
4-%c /aso n 7 4
ANALY' SIS TO SUPPORT RAISING llLGLERESSURE TRlf_SETPOINT e OBJECTIVE o KEY INPUTS I
e SEQUENCE e POWERTRAIN SIMULATION e MONTE CARL 0 SIMULATION e COMPARIS0N WITH NRC GUIDELINES AND PREVIOUS ANALYSIS 1
I
t J
ANALYSIS OBJECTIVE s s ,
\
\
's s
4 d
1 DETERMINE WHETHER THE HIGH PRESSURE REACTOR TRIP SETPOINT CAN BE RAISED TO A VALUE AB0VE THE CURRENT 2300 PSI 6 SETTING WITHOUT EXCEEDING NRC GUIDELINES FOR ,
- PORY OPENING FREQUENCY.
1
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-_y, 7 .y.~- --, ___._. - , ., ,_,y .-, .- _---- ._ _ .
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KEY ANALYSIS INPUTS I
DISTRIBUTIONS FOR:
- PEAK RC PRESSURE
- RPS ERRORS
- PORY CIRCUIT ERRORS 1
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TYPICAL OVERPRESSURE TRANSIENTS seso - - - - - - - - - - - - - - - - - - - ~ ~ - - - - - - - - -
i
, ,, , TURB VLV CLS
_ MFWP TRIP saso- -
l smoo- - ----------------------- = . ----- ......-- --------------------------- .
x
- N N
\ '
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amoo- -
g IIE sino- -
- \
\
i stoo- - \
\
\s sono : : : : : : : : : : : : : : :
- 4 2 -1 0 1 2 3 4 5 6 7 8 SECONDS (RELATIVE TO REACTOR TRIP)
ANALYSIS SEQUENCE 1 DEVELOP PEAK RC PRESSURE (0VERSHOOT) DISTRIBUTION FROM PLANT DATA.
2 PERFORM POWERTRAIN SIMULATION TO DETERMINE RELATIONSHIP BETWEEN OVERSHOOT AND TRIP SETP0 INT.
3 STATISTICALLY COMBINE OVERSHOOT, RPS ERRORS, AND PORY ERRORS TO PREDICT PORY OPENING PROBABILITIES.
4 COMPARE RESULTS WITH NRC GUIDELINES AND PREVIOUS ANALYSIS.
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RC PRESSURE OVERSHOOT PLANT DATA DISTRIBUTION -
s.- -
ao. .
as- -
8 so- -
b
- g ... .
to- .
7
' 3 2
i o . .
vss m
/b .
vss m O-10 11-20 21 - 30 31 - 40 41 - 50 51 - 60 l OVERSHOOT RANGE (PSI)
f 9 a
0VERSHOOT DISTRIBUTION REVIEWED TAP DATA FOR HIGH PRESSURE TRIPS 1980-84 CARE TAKEN TO ASSURE PEAK PRESSURE WAS CAPTURED ONLY BEST DATA USED (47 0F 65 TRIPS)
INLET SKEWED DISTRIBUTION OBSERVED
9 9 POWERTRAIN SIMULATION
- METHOD
- RESULTS
- CONCLUSIONS l
1 1
SIMULATION METHOD
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e REPRESENTATIVE TRANSIENT SELECTED (TURBINE TRIP WITHOUT REACTOR TRIP) e PLANT MODEL DEVELOPED (SIMILAR TO RANCHO SECO) e MODEL PREDICTIONS COMPARED WITH PLANT DATA AT 2300 PSIG SETPOINT e MODEL PREDICTIONS AT 2300 PSIG AND 2355 PSIG COMPARED
, - - - .- -.-- __ _ . y _ .--.. ,
POWERTRAIN VS PLANT DATA t
TURBINE TRIP WITHOUT ARTS -
2300 PSIG SETPOINT s4So.-
i 2400- - RC PR PT
....... RC PR Pl.NT
.......... 2300 TRIP m
.3 . .
y SSGo*
- g
. . ./
/
2180* -
w w O . 5 11.522.533.544.555.566.577.588.59 SECONDS (REL.ATIVE TO TU.RBINE TRIP)
Pt. ANT DATA FOR OCONE-1.1/22/85
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SIMULATION RESULTS I
o 0VERSH00T AT 2?00 PSIG SETPOINT 50 PSI o OVERSHOOT AT 2355 PSIG SETPOINT 30 PSI 1
4
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POWERTRAIN RESU LTS TURBINE TRIP WITHOUT ARTS -
2450 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2300 CASE seco- -
1
__ 2355 CASE
............................................................................. eM. ......................... .D --**-**
- - .......... 2355 TRIP m
.__ PORV
,,oo. . ............................... ..........................
v 2250- -
N 3150- ,
3100 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 .5 1 1.522.533.544.555.566.577.588.59 SECONDS (RELATIVE TO TURBINE TRIP) 1
CONCLUSIONS FROM POWERTRAIN SIMULATION e OVERSHOOT IS A WEAK FUNCTION OF TRIP SETP0 INT e OVERSHOOT DISTRIBUTION FOR MONTE CARLD ANALYSIS CONSERVATIVELY ASSUMED SAME AS PLANT DATA l
e e-- ._ _ _ _
1
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l MONTE CARLO SIMULATION e MAJOR INPUTS e METHOD e RESULTS
MAJOR INPUTS TO MONTE CARL 0 SJMULATION e REACTOR PROTECTION SYSTEM (RTS) ERROR DISTRIBUTION e PORY CIRCUIT ERROR DISTRIBUTION e RC PRESSURE OVERSHOOT DISTRIBUTION
Table 4-3. Summary of Major Inputs to Monte Carlo Simulation Procram RANDOM ERRORS Probability Distribution Distribution Source (Model) Parameters Reactor Normal Average 4.83 Protection psi System Standard Deviation 6.2175 psi Non-Nuclear Instrumentation
-Buffer Amplifier Normal Average 0.0 Psi j Standard Deviation 1.4 psi
-Bistable Normal Average 0.0 psi Standard Deviation 1.3 psi Setpoints RPS ,
Uniform Range O to
+ 5 psi NNI (PORV) Uniform Range -5 to ;
! O psi 1
PHYSICAL PHENOMENA Pressure Exponential 16.4 psi Ov;ershoot (Truncaced
< 60 psi 2 10 psi) 4 4
.-.-m
- - - - - - . - - - - - - . , . .- - , _ . - - . . , , . , , ,_, , , - , - , - - - - , . - _ , . - - -. 9-
Figure 4.4-2. Overshoot Distribution for Monte Carlo Input
.60 Observed (Plant Data) 5 h .50 -
^
yE -_--
3 3 -
g8 '8 .40 -
g e I Used E
3c a g'f l (Result of applied model)*
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c 5 .30 3
- *{$ -
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4 ,'
E% __I * $
gu .20 - z$ 3 -.
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&E 7
.10 -
p g
L E g u _ _ _ _ s,. ., _ _ , y
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l i I I 1
, 10 20 30 40 50 60 Overshoot, psi
- Approximated l
a
I MONTE CARL 0 SIMULATION METHOD e SINGLE TRUE PRESSURE INPUT TO ALL FOUR RPS TRANSMITTERS e ADD RPS ERRORS e CHECK FOR TRIP 0F AT LEAST TWO CHANNELS e INCREMENT TRUE PRESSURE BY OVERSHOOT VALUE FROM DISTRIBUTION e ADD'PORY CIRCUIT ERRORS e CHECK FOR PORY OPENING e REPEAT FOR 100,000 TRIALS l
)
l l
l f __ _
1 Figure 4.4-3. Model for Monte Carlo Analysis i
l RPS "A" String (Buffer Amplifier -
Bistable High Press S.P. yy,
_ String PORY l # (Setpoint)
-e i
g;- go l . l I
RPS Errors True
@+"",
N (4.83String 6.2175)
_ RC High Press U (0,5)
Pressure Setpoint NNI Errors String gp3 ..C.. B/A N(0,1.4)
N(0,1.3)
,_ Setpoint U(-5.0)
.i RPS D" Note: N (a,b)=p Nomal distribution with mean a, standard deviation bs U (a,b)=> Unifom distribution on interval (a,b) -
. c 1
MONTE CARLO SIMULATION RESULTS e ONE TRIAL IN 100,000 RESULTED IN OPENING THE PORY WIT'.i TRIP SETPOINT 1 AT 2355 PSIG AND FORY AT 2450 PSIG s
l 9
4 Fiqure 4.4-1. Monte Carlo Results i
3000 -
0 (2893)
X (2365) 3 2000
.2 h
8 8
f S e(1485) l .5
- c
- D (1077) w 1000 -
o- PORY opens x- Within5ps!
O- Within 10 psi (44)
(296) ( )- Count Q e(55) 2355 2365 2375 .
Setpoint, psig
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COMPARISON WITH NRC GUIDELINES AND PREVIOUS ANALYSIS i
, s f
e APPLICABLE NRC GUIDELINES e CURRENT STUDY RESULTS 9
i l
1 l
l APPLICABLE NRC GUIDELINES e PROBABILITY OF A SMALL BREAK LOCA DUE TO A STUCK-0 PEN PORY OR SAFETY YALVE SHOULD BE LESS THAN 10-3/ REACTOR YEAR (NUREG-0737 ITEM II.K.3 2) e FREQUENCY OF PORY OPENINGS FOR OVERPRESSURE TRANSIENTS SHOULD BE LESS THAN 5% OF THE TOTAL NUMBER OF OVERPRESSURE TRANSIENTS (NUREG-0737 ITEM II.K.3 7) i
CURRENT STUDY RESULTS e PORY OPENING PROBABILITY FOR OVERPRESSURE TRANSIENTS 1 x 10-5 OPENINGS PER EVENT e OVERPRESSURE TRANSIENT FREQUENCY 1 86 EVENTS PER REACTOR YEAR (BASED ON 65 HIGH PRESSURE TRIPS FOR 7 PLANTS OVER 5 YEARS) e PORY OPENING FREQUENCY FOR OVERPRESSURE TRANSIENTS 1 86 x 10-5 OPENINGS PER REACTOR YEAR
COMPARIS0N WITH PREVIOUS ANALYSIS l
e RAISING HIGH PRESSURE TRIP SETPOINT DOES NOT IMPACT PORY OPENING FREQUENCY FOR OTHER EVENTS e OVERALL PORY OPENING FREQUENCY IS ESSENTIALLY THE SAME WHETHER SETPOINT IS 2300 PSIG OR 2355 PSIG e PREVIOUS STUDY CONCLUDED THAT PROBABILITY OF SBLOCA DUE TO STUCK OPEN PORY WAS ACCEPTABLE (<10-3) WITH OVERPRESSURE TRANSIENT CONTRIBUTION TO PORY OPENING FREQUENCY OF 2 2 X 10-3 e CURRENT STUDY ESTIMATE OF 2 x 10-5 WILL ALSO RESULT IN ACCEPTABLE SBLOCA PROBABILITY ,
l e DIFFERENCE IN CURRENT vs. PREVIOUS STUDY RESULTS DUE MAINLY TO:
- BETTER DATA FOR OVERSHOOT DISTRIBUTION 1
(
l