ML18153C835
| ML18153C835 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 11/29/1991 |
| From: | Buckley B Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9112100027 | |
| Download: ML18153C835 (47) | |
Text
{{#Wiki_filter:~ ' ) ( l_ Docket Nos. 50-280 a!'ld 50-281
- Novembe~9, 1991 LICENSEE: Virginia Electric and Power Company FACILITY: Surry Power Station, Units 1 and 2
SUBJECT:
MEETING
SUMMARY
OF OCTOBER 31, 1991 A meeting was held with the representatives of Virginia Electric and Power Company (VEPCO) and the NRC staff in Rockville, Maryland on October 31, 1991. The purposes of the meeting were to provide VEPCO the opportunity to discuss the core damage frequency (CDF) from internal flooding and the efforts underway to further reduce the CDF frequency. Meeting handouts and a list of attendees are enclosed. VEPCO representatives summarized the bases and methodology of their internal flooding analysis, described the affected systems and components and their interim flood control measures, as well as their future plans for further improvement. The NRC staff mentioned that further analysis would be required in the future with regards to external events, such as earthquakes and fire tornadoes *. More detailed information on the meeting is described in the enclosed handouts.
Enclosures:
- 1. List of Attendees
- 2. Meeting Handouts cc w/enclosure:
See next page Distribution See next page 9112100027 911129 PDR ADOCK 05000280 P PDR /s/ Bart Buckley, Sr. Project Manager Project Directorate II-2 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation
NAME Bart Buckley Paul Guymer Dave Bucheit George Hubbard Gus Lainas Luis Reyes James Tatum John Schiffgens Bill LeFave J. F. Wechselberger Jeffrey Shackelford Bruce Boger Lynn Connor George Wrobel Ann Ramey-Smith Erasmia Lois Bill Rasin Herb Fontecilla Jack Guttmann Sammy Diab Carl Baab Damalle Weaver Douglas Levy Michael T. Markley Ken Brockman Myron Karman Ron Hernan Ken Clark Frank Ingram D'Vera Cohn Kevin Connaughtom John H. Flack Paul Kirby Jocelyn Mitchell Bill Ruberry Gail Marcus Gary M. Holahan Ashok Thadani Ron Berryman Alan Price M. L. Bowling W. L. Stewart Attendance list for Surry IPE Meeting October 31, 1991 AFFILIATION NRC HNUS Virginia Power NRC/NRR NRC/NRR NRC NRC NRC DST/NRR OEDO NRC/RII NRC/NRR Southern Technical Services RG&E NRC/RES/PRAB NRC/RES/PRAB NUMARC Virginia Power NRC/OCM-FR NRC/NRR/PRAB Virginia Power The Energy Daily UPI NRC/NRR/LPEB OCM/IS OCM/KR NRR/PD I-4 NRC/PA/RII NRC/PA Washington Post OCM/JC NRC/RES/DSIR Daill Press OCM/ s Richmond Times - Dispatch OCM/KR NRC/NRR/DST NRC/NRR/DST Virginia Power - Eng Virginia Power - Surry Power Station Virginia Power - Manager 9 Nuclear Licensing Virginia Power - Sr. v.* P.- Nuclear
} L_ __ NAME F. K. Moore Frank Cange 1 T. Murley Conrad McCracken Herbert Berkow Wi 11 i am Beckner Albert Gibson S. AFFILIATION Virginia Power - V.P. Nuclear Energy Serv. NRC/NRR NRC/NRR NRR/SPLB NRC/NRR/PDII-2 NRC/NRR/RAB NRC/RII NRR/DRPE
( Meeting Summary Dated November 29 2 1991 D1 stribution Docket File NRC & Local PDRs PDII-2 RF T. Murley F. Miraglia S. Varga G. Lainas H. Berkow B. Buckley D. Miller OGC G. Hubbard, 8-D-1 J. Tatum, 8-D-l J. Schiffgens, 10-E-4 B. Boger, 13-E-4 A. Smith, NLN372 E. Lois, NLN372 J. Guttmann, 16-H-3 S. Diab, 10-E-4 M. Markley, 10-H-12 R. Hernan, 14-C-7 F. Ingram, 2-G-5 J. Flack, NLS324 G. Holahan, 8-E-2 A. Thadani, 8-E-2 F. Congel, 10-E-2 C. McCracken, 8-D-1 W. Beckner, 10-E-4 ACRS (10) E. Jordan, MNBB 3701 J. Wechselberger, 17-G-21 L. Reyes, RII A. Gibson, RII J. Shackelford, RII K. Clark, RII M
- S in ku 1 e, R II
INTERIM.UPDATE ON SUriRV IPE /-INTERNAL FLOODING . OCTOBER 31, 1991 VIRGINIA POWER
INTRODUCTION AND OVERVIEW .. e. . VIRGINIA POWER
- e W. L. STEWART SENIOR VICE PRESIDENT - NUCLEAR
AGENDA INTRODUCTION AND OVERVIEW ORIGINAL LICENSlt~G BAS1s* AND IPE / INTERNAL FLOODING. CHRONOLOGY ORIGINAL.IPE / INTERNAL FLOODING ANALYSIS. OVERVIEW AND SCOPE OF INTERNAL FLOODING REANALYSIS INTERIM FLOOD CONTR.OL MEASURES FUTURE PLANS AND CONCLUSIONS . W. L. STEWART M. L. BOWLING R.M.BERRYMAN J. A. PRICE M. L. BOWLING.
Transfonnera Dllch Turbine Building Main Condenser Condenser Pits. Service Bulldlng Auxllary Bulldlng Primary Water Storage Tank . I I I EL2.0't ___ -~ ____ _I Boron Recovery Tank SURRY NUCLEAR POWER PLANT CROSS SECTIONAL VIEW Pltwllh Vacuum Breaking YeniYalve Dllch EL 16.5' Dlschmge Seal Canal Weir
TO D ISCI\\ARG£ CAIW. <E---- & J41£S R II/ER ~CiJoull!N ll'l!AY IUT OOIWiRS H&r-1AtD lltlll'.llilllN ll'l!AY IUI OOWIIRS H!S-{-1 B tc UNIT 1 DISCHARGE TUNNEL LIil lllll!IIG Clll.llG 11\\TIR IDT oowaRS \\.l[-{-f ABtc LIil 1 (l)f(INSIR 1-0I-SC-1 A 1A 1 B I.NII 1 SCR£N1llS INTAKE CANAL . (CIMDI TD IIJTH IIIITS) LIii 1 COO:llll! Hll-SC-1 B 11m1 O,.il;IM;i'I.F -----~ ~itll'S(2) 1,1111 1 awtllC NI' ~Rl'lll IA!!R 9.8m1IJI I.Ill 2 OM:IIC PIJI' ~RVl_ll. IA!!R 9JJSYS1lll IUCllfflll.PIJJI{ BmlltY ~ IIOIL'R 1ml \\00 IL.Al KM S'fS1Ill OHlillS (l-l'Si-4 AB t C, aJAOj) FIDI LIii 2 mINnlS \\-g!-11 1C 10 Sl"'llFIED FLOW DIAGRAM CIRCllATING WATER SYSTEM AND SERVICE WATER SYSTEM 10 I.Ill 2 DISOWO: llHll. mmm .Im.lie 11\\l!R 1£.Al (IDMIJIS 1-W-£-lABCtO (<DIOI) ti.LOO. IIINIE Sll!ltlll( C lllllAT Ill: IITIR. Plll'S
- (B ft1! !>Ill lJIITS)
Dm.111MN OOUXl !IJNIII 11\\TIR l'lll'S (l, aMIM)
Turbine Building Basement Plan. Auxlllary Building.
~~~..;..._..~~~~-:--:-~--,
. ESGR MEAl3 ...................................................................... T"i.--~.....,-.~~...... -..~.....,-.~~----4-----------*r----~~~.. 0 0 0 Sump No.1' I AB Tunnel '-:*:::::::;~;;;;;i'.~:\\~., **<:;;~;;i~;;~:::~:k* m 1-CN-1-CN-z j I I SC-1A SC-1A I BC Heat Exchanger I 11 II Inlet " I I . I I I I r I I I I I I I I I I I I I I I RS & BC Valve Pit I I I 0 I I High Level Intake Canal 2'D1ke
- J CC Heat Exchangers D
cc Valve Pit J!! N t: z e
INTRODUCTION I SU*RRY IS WELL DESIGNE*D,MEETS LICENSING DESIGN BASIS,.
- . AND IS CONSERVATIVELY OPERATED *.
IPE INTERNAL FLOODING.RESULTS WERE HIGHER THAN. EXPECTED BECAUSE OF THE CONSERVATISMS IN THE ORIGINAL ANALYSIS* I I I 9: A NUMBER OF PHYSICAL ENHANCEMENTS TO REDUCE.THE POTENTIAL FOR INTERNAL FLOODING EVENTS AT SURRY HAVE
- e.
BEEN MADE AND SEVERAL ADDiTIONAL *oNES ARE PLANNED
INTERNAL FLOODl'NG ORIGlNAL ANALYSIS OVERVIEW CDF 9URRENT (10/29/91)* CREDIT TAKEN FOR * . - EXPANSION JOINT REPLACEMENT AND MOV REPLACEMENT/BOLT INSPECTION - 7 OF 9 SUMP PUMPS OPERABLE PLANNED SHORT TERM MODIFICATIONS:(BY 11/22/91) CHARGING PUMP CUBICLE DRAIN LINE BACKFLOW
- . PREVENTION EXPANSION JOINT SHIELD INSTALLATION*.
1.7 E-4 9.9 E-5
- ORIGINAL LICENSING.BASIS AND IPE / INTERNAL FLOODING CHRONOLOGY I
e* VIRGINIA POWER
- M. L. BOWLING MANAGER - NUCLEAR LICENSING & PROGRAMS**
OPERATING LICENSE BASIS ORIGINAL LICENSING BASIS - LARGE UNISOLABLE CW FAILURE NOT CONSIDERED CREDIBLE CW PIPING ANALYZED FOR DBE MOVEMENT PIPE RESTRAINTS LIMIT BREAK SIZE HYPOTHETICAL PIPE LEAK ASSUMED 1/8" CRACKAND 180° SUMP PUMP CAPACITY GREATER THAN ASSUMED LEAKAGE. e
LICENSING BASIS FOLLOWING QUAD CITIES EVENT
- .* REVIEW ASSUMPTIONS FAILURES LIMITED TO NON-SE_ISMIC COMPONENTS.
CATEGORY I (SEISMIC) SYSTEMS REMAIN INTACT . LOSS OF OFFSITE POWER. NO CONCURRENT ACCIDENTS
- LICENSING BASIS FOLLOWING
. QUAD CITIES EVENT ( continued) PLANT MODIFICATIONS CW EXPANSION JOINT SHIELDS.. LEVEL SWITCHES/ALARMS AND AUTO CW ISOLATION DIKES, BARRIERS, AND-WATER TIGHT SEALS FOR
- OTHER SAFETY RELATED*AREAS AND VALVE PITS MODIFICATION OF EXISTING DIKES FLOW DIRECTING PIPE SLEEVE FOR FIRE MAIN IN TURBINE BUILDING NRC SER (12/18/80)
LAWRENCE LIVERMORE TECHNICAL EVALUATION. FINDING OF "DEGREE OF VULNERABILITY" MINIMIZED BY MODIFICATIONS AND PROCEDURES ~: '
IPE / INTERNAL FLOODING CHRONOLOGY AUGUST 30, 1991 SUBMITTED IPE OCTOBER 9~ 1991
- NRC BRIEFED ON IPE
- METHODOLOGY,.
CONSERVATISMS, ANID FUTURE PLANS I
IPE / INTERNAL FLOODING CHRONOLOGY - ( continued)
- . IPE INTERNAL FLOODING RESULTS INDICATE VULNERABILITY TO UNISOLABL ~ INTERNAL FLOODS SHOULD THEY OCCUR e
PROBABILITY OF OCCURRENCE IS NOT DIRECTLY QUANTIFIABLE BASE_D ON ACTUAL OPERATING EXPERIENCE, RATHER IT IS THEORETICALLY DERIVED FROM LIMITED AVAILABLE COMPONENT FA~LURE DATA AND CONSERVATIVE MODELING ASSUMPTIONS ACTUAL PROBABILITY OF OCCURRENCE IS ACCEPTABLY LOW BECAUSE CRITICAL COMPONENTS, WHICH WILL PREVENT INTERNAL FLOODING, ARE BEING MAINTAINED THROUGH I I EXISTING MAINTENANCE PROGRAMS. ADDITIONALLY, SUMP _ PUMPS ARE RELIABLE PROCEDURE, PROGRAM, AND EQUIPMENT ENHANCEMENTS HAVE BEEN SCHEDULED TO REDUCE PROBABILITY OF AND ELIMINATE VULNERABILITY TO INTERNAL FLOODING ESTIMATED CDF TO BE< 8 E-4 TAKING CREDIT FOR FLOODING PROCEDURE REVISIONS AND 7 OF 9 SUMP PUMPS OPERABLE
IPE / INTERNAL FLOODING CHRONOLOGY (contunued) OCTOBER 23, 1991
- MET WITH NRC AT SURRY OCTOBER 28, 1991
- SUBMITTED REVISED MODIFICATION OCTOBER 29, 1991.
SCHEDULE, COMMITMENT TO INTERNAL * *
- . FLOODING REANALYSIS, AND COMMITMENT TO INTERIM MEASURES
- PURPOSE OF REANALYSIS IS TO BETTER *.
QUANTIFY CONSERVATISM IN ORIGINAL ANALYSIS.
- SUBMITTED REDUCED CDF FOR INTERNAL FLOODING OF 1.7 E-4 (CURRENT PLANT.
CONFIGURATION) *
- CREDIT TAKEN FOR REPLACEMENT OF EXPANSION JOINTS AND ASSOCIATED VALVES, VALVE BOLTING INSPECTIONS, AND 7 OF 9
. SUMP PUMPS OPERABLE e* e
IPE /INTERNAL FLOODING CHRONOLOGY. ( continued) NOVEMBER 21, 1991
- TENTATIVELY PLAN TO MEET WITH NRC TO.
DISCUSS INTERNAL FLOODING REANALYSIS RESULTS NOVEMBER 22, 19r1 *
- SCHEDULED TO SUBMIT INTERNAL FLOODING REANALYSIS RES~LTS
- SCHEDULED TO COMPLETE ADDITIONAL
- e MODIFICATIONS BY NOVEMBER 22, 1991 TO
- REDUCECO~SEQUENCES
ORIGINAL IPE / INTERNAL FLOODING ANALYSIS OVERVIEW VIRGINIA POWER . R. M. BERRYMAN MANAGER - NUCLEAR ANALYSIS & FUEL
INDIVIDUAL PLANT EXAMINATION SURRY UNITS 1 AND 2 SURRY IPE PERFORMED IN ACCORDANCE WITH NRC GENERIC a LEITER 88-20 METHOD OF EXAMINATION INCLUDED DEVELOPMENT.OF LEVEL 1 AND LEVEL 2 PRA MODELS FOR EACH SURRY UNIT. IPE PERFORMED BY A PROJECT TEAM CONSISTING OF VIRGINIA POWER AND NUS CORPORATION ANALYSTS EXAMINATION WAS COMPREHENSIVE AND PROVIDED SIGNIFICANT INSIGHT REGARDING POSSIBLE CORE DAMAGE SEQUENCES, POTENTIAL MITIGATIVE ACTION, AND ENHANCEMENTS TO REDUCE RISK. -* THE TOTAL CDF FROM INTERNAL EVENTS DERIVED FROM THE SURRY ~PE WAS COMPARABLE TO THAT DOCUMENTED IN NUREG/CR-4550 SINCE SURR,- ~PE REVEALED VULNERABILITY TO INTERNAL FLOODS, ADDITIONAL ANALYSIS AND REVIEW-HAVE BEEN INITIATED
ORIGINAL INTERNAL FLOODING ANAL VSIS BASIC ANALYTICAL STEPS..
- DIVIDE PLANT INTO INDEPENDENT FLOOD *AREAS
.IDENTIFY MAJOR FLOOD SOURCES -. IDENTIFY POTENTIAL INTER-AREA PROPAGATION PATHWAYS SCREEN FLOOD AREAS AND POTENTIAL FLOOD PATHWAYS.* . USING CONSERVATIVE ANAL;YSES PERFORM DETAILED ANALYSIS OF POTENTIAL SIGNIFICANT FLOOD AREAS, SOURCES, AND SCENARIOS ei
ORIGINAL INTERNAL FLO*ODING ANALYSIS* ( continued) FLOOD ANALYSIS ACCOUNTS FOR* -FREQUENCY/SIZE OF FLOOD EVENT* FLOOD MITIGATION MEASURES (AUTO ISOLATION, DRAINS, SUMP.. PUMPS, FLOOD ALARMS, AND PROCEDURES) RESULTING NATURE OF FLOOD INITIATED TRANSIENT AND EQUIPMENT DAMAGE - -COINCIDENT RANDOM EQUIPMENT FAILURES AND HUMAN ERRORS RECOVERY ACTIONS \\ e
I---------------------------- R*Esu*L TS OF ORIGINAL INTERNAL FLOODING ANAL YS1S 18*FL00D AREAS IDENTIFIED AND SCREENED AT SURRY POWER STATION 6 OF THE 18 FLOOD AREAS EVALUATED IN DETAIL .* BASE CASE RESULTS FLOOD AREA FLOOD SOURCE CDF/YR (BASE CASE) UNIT 1 TURBINE BUILDING (CW + SW) 5.9 E-4 . UNIT 2 TURBINE BUILDING (CW + SW) 4.5 E~4 UNIT 1 SAFEGUARDS BUILDING (RWST SUPPLY) 3.1 E~5 MECHANICAL EQUIPMENT (SW). *
- 3.0 E-5 ROOM NO. 3 AUXILIARY BUILDING (RWST SUPPLY) 2.3 E-5
- UNIT 2 SAFEGUARDS BUILDING (RWST SUPPLY)
- 1.5 E-5
-1.1 E-3.
) ORIGINAL INTERNAL FLOODING ANAL VSIS - EVALUATION OF TURBINE BUILDING. MOST SIGNIFICANT FLOOD INITIATORS CIRCULATING WATER AND SERVICE WATER.FAILURES VALVE BODIES EXPANSION JOINTS PIPE/CONDEN,SER SOURCES GRAVITY FED FROM INTAKE CANAL TWO FLOOD TYPES DEFINED . LONG TERM ISOLABLE*- CAN ONLY BE 15.0LATED BY STOP LOGS (ASSUMED TO TAKE UP TO 24 HOURS) -
- SHORT TERM ISOLABLE - CAN B*E ISOLATED BY CLOSING.
VALVES '1 e
ORIGINAL INTERNAL FLOODING_ ANALYSIS - - EVALUATION OF FLOOD HAZARD FOR CW AND SW SYSTEMS EXTENSIVE SEARCH OF HISTORICAL INDUSTRY FLOODING DATA ASSOCIATED WITH CW.AND SW SYSTEMS-LOG-LINEAR RELATIONSHIP BETWEEN FLOOD FREQUENCY AND RATES UTILIZED FOR ALL CW AND SW FLOODING SOURCES
- . ENGINEERING JUDGEMENT USED TO QUANTIFY THIS LOG-LINEAR RELATIONSHIP USE OF LOG-LINEAR RELATIONSHIP TO DETERMINE PROBABILITY _OF COMPONENT FAILURES RESULTING IN
- MAX!M:UM FLOOD RATES.IS CONSERVATIVE*
e*
E
- a.
a C -* -* a, IC !I 0 ii: - a 0... SERVICE WATIER SYSTEM FLOODING RATES FROM ACTUAL EVENTS J.5 J 2.5 2 1.5 I I 3 5 7 9 II* ll EVENT NUMBER e
CW [xpansion Joint. Log Linear Curve
- 1 0 0 0 0 0 0 --************--*---*-*--*.. ---*--*----*--*----**-*--* --==
1 0 0 0 0 0 :::i:::::::::::::::::::::::::::::::i:: ::::::~~:::::::::::: :::::: ::::::=:::::::::::::::.. :::::::::::~~::::::::::;:::::? :::::::::::::::::::::::: *::::::= ::::::::::::-===*. (D - - c* -~- ~ .0 G:.. "'C o* 0 LL 10000 ~.................. - *---.. *-**-****--*-****-***--************,*****------*-**-**---****----. *----******-**************-....... ---*-*** 1000.
- '**********-******-*****----**-******-H******Hee***-*****H*oo-**HOeo*H***********H
- ******-***********.o***********************--**
- .-*-*...::::=::::::=::::.-.::::_ :: -*:::::::::::::::::::::.-==::::::..-::.::::::::::... **:::.::::::::::::::,::::::::::::::::::::::::.:::::
1 0 0 ~-----.,-------,-.--___.;.-------.----------4 5.0E-_05 1.0E-04. 1.SE-04 2.0E.;...04 2.SE-04 Probability Per
- Component Year
CONSERV ATISM*s IN ORIGINAL INTERNAL FLOODING ANALYSIS ESTIMATION OF FLOOD HAZARD NO MAJOR FLOODING EVENTS FOR SW VAL YES/EXPANSION . JOINTS AND CW INLET VALV*ES APPLICABLE TO SURRY FLOOD FREQUENCY AT LOWER END OF RANGE CONSERVATIVELY ASSIGNED (E.G., HISTORICAL LEAKAGE FROM EXPANSION JOINTS APP'ROXIMATELY 1 GPM; ANALYSIS.
- . CONSERVATIVELY ASSIGNED ONE EVENT AT 100 GPM}
WORST CASE FLOW RATES FOR INDIVIDUAL FLOOD SEQUENCES I.. WERE USED TO DETERMINE OPERATOR RESPONSE TIME FOR* e. HUMAN-ERROR PROBABILITIES
- . WATER HAMMER EVENT ASSUMED TO RESULT IN COMPONENT FAILURE
CONSERVATISMS IN ORIGINAL INTERNAL FLOODING ANAL VSIS (continued). ASSUMPTIONS -
- ENTRANCE FROM TURBINE BUILDING TO ESG ROOM ASSUMED TOBE OPENED LOWEST ELEVATION USED FOR ALL MCCs* IN SAME AREA TO
- DETERIMINE CRITICAL FLOOD HEIGHT.
CONSERVATIVE MINIMUM NUMBER OF SUMP PUMPS AVAILABLE (2 OUT OF 9 PUMPS) e
INTERNAL FLOODING REANALYSIS PURPOSE TO QUANTIFY THE CONSERVATISMS IN THE CORE DAMAGE FREQUENCY DUE TO INTERNAL FLOODING FOR THE ORIGINAL ANALYSIS BY DEMONSTRATING ANALYTICALLY THAT WATER HAMMER INDUCED ~TRESS IS INSUFFICIENT TO CAUSE FAILURE OF RISK - SIGNiFICANT* COMPONENTS IN THE CW AND SW SYSTEMS ANALYZING REMAINING COMPONENTS WHICH MAY STILL e PRESENT A FLOOD HAZARD- - -e
INTERNAL FLOODING REANAL VSIS APPROACH. PERFORM DETERMINISTIC WATER HAMMER ANALYSIS OF CW AND SW SYSTEMS TO DETERMINE MAGNITUDE OF STRESS _FOR CRITICAL COMPONENTS DETERMINE YIELD AND ULTIMATE STRESSES FOR - CRITICAL COMPONENTS DEVELOP STRESS INDUCED FAILURE.PROBABILITY MO.DEL REFINE DATAANALYSIS TO. DETERMINE-FREQUENCY OF WA"l"ER HAMMER EVENTS, COMPONENT FAILURE
- 9 PROBABILITY, AND MAXIMUM CREDIBLE FLOOD RATES REQUANTIFY CDF.
STRESS INDUCED FAILURE PROBABILITY MODEL MODEL FOR FAILURE PROBABILITY VS. STRESS WILL BE BASED ON NUREG/CR-5102, "INTERFACING SYSTEMS LOCA STUDY" USES MAXIMUM UNCERTAINTY (EXTREME VALUE) DISTRIBUTION AS MOST DEFENSIBLE ASSUMES MEAN FAILURE PROBABILITY AT 90% OF ULTIMATE STRESS, BASED.ON BURST TEST DATA ASSUMES 99th PERCENTILE AT ULTIMATE STRESS APPLICATION WILL ACCOUNT FOR PLANT SPECIFIC DESIGN AND OPERATING CONDITIONs**
. REFINED DATA ANALYSIS FOR INTERNAL FLOODING REAN,AL YSIS 3 VALVE FAILURES WHICH RESULTED IN WATER HAMMER HAVE BEEN RECORDED IN U. S. NUCLEAR PLANT OPERATING HISTORY~. THESE FAILURES HAVE THE FOLLOWINGCHARACTERISTICS
- PUMPED SYSTEM VIBRATION/PRESSURE PUI..SE LEADING TO FATIGUE.
- . SURRY DESIGN CONDITIONS DIFFER FROM HISTORICAL FAILURE EVENTS.
GRAVITY FED NO PULSED VIBRATION
- APPLICABLE DESIGN CONDITIONS WILL BE UTILIZED TO DEVELOP REVISED FREQUENCY OF VALVE FAILURES LEADING TO WATER.
HAMMER EVENTS
R-EFINED DATA ANALYSIS. FOR INTERNAL FLOOD~NG REANALYSIS * (continued) DETERMINE PROB.ABILITY OF COMPONENT FAILURES GIVEN THE STRESS THAT IS INDUCED DUE. TO A POSTULATED WATER HAMMER SCREEN OUT COMPONENT FAILURES SHOWN TO BE. NOT CREDIBLE OR VERY LOW FREQUENCY ( < 1 E-6/YR). CALCULATE MAXIMUM FLOW.RATE FOR REMAINING COMPONENTS WHICH MAY FAIL BASED ON 9
- CREDIBLE BREAK SIZE DETERMINE PROBABILITY OF FAILURE OF REMAINING COMPONENTS FOR *A RANGE OF FLOW.
RATES
i I I RE.QUANTIFICATION OF CDF
- .CALCULATE FLOOD DAMAGE STATE FREQUENCIES
. BASED ON REVISED FLOOD-HAZARD QUANTIFY EVENT TREES TO DETERMINE REVISED CDF DUE TO INTERNAL-FLOODS REVISED BASE CASE TO REFLECT CURRENT PLANT -CONFIGURATION AND OPERATING PRACTICES *, ADDITIONAL CASE TO REFILECT PLANNED FUTURE** MODIFICATIONS
- e.
INTERIM FLOOD CONTROL MEASURES -1 VIRGINIA POWER J. A. PRICE ASSISTANT STATION MANAGER -. NUCLEAR SAFETY & LICENSING
- I
-INTERIM FLOOD CONTROL MEASURES -- NO CREDIT TAKEN FOR INTERIM MEASURES IN CDF REDUCTION INTERIM FLOOD WATCH PROGRAM -VT2 QUALIFIED* PERSONNEL TURBINE BUILDING SUMP PUMP MEASURES STOP LOG INSTALLATION ADMINISTRATIVE CONTROLS
INTERIM FLOOD CONTROL MEASURES (continued) FLOOD WATCH PROGRAM * - NO OTHER ASSIGNED.DUTIES * - TRAINED ON POTENTIAL FLOOD SOURCES .. l f . I I . I - COMM-UNICATIONS ESTABLISHED WITH SHIFT SUPERVISOR e*
-INTERIM FLOOD CONTROL MEASURES
- ( continued)
TURBINE BUILDING SUMP PUMP MEASURES. ** - TWO DIESEL DRIVEN PUMPS (-1,200 GPM EACH) ONSITE . - BY PROCEDURE, TURBINE BUILDING OPERATOR CHECKS ALL THE 9 PUMPS EACH SHIFT - ADMINISTRATIVELY REQUIRE 90F 9 PUMPS OPERABLE - ENTER 7 DAY ADMINISTRATIVE ACTION STATEMENT FOR e
- UNITS IF PUMPS OUT OF SERVICE OR IMPLEMENT COMPENSATORY MEASURES
- - PRIORITY GIVEN TO ANY REQUIRED MAINTENANCE
INTERIM FLOOD CONTROL.MEASURES (continued)
- . STOP LOG INSTALLATION CONTROLS
- DEDICATED CRANE OPERATOR AND RIGGERS-ONSITE 24 HOURS PER DAV - DEDICATED CRANE AND STOP LOGS AT HIGH LEVEL INTAKE STRUCTURE AT ALL TiMES
~ FUTURE PLANS AND CONCLUSIONS VIRGINIA POWER M. L. BOWLING -MANAGER - NUCLEAR LICENSING & PROGRAMS
ADDITIONAL PHYSICAL MODIFICATIONS_ CHARGING PUMP CUBICLE DRAIN LINE MODIFICATION TO PREVIENT BACKFLOW EITHER BY PLANNED INSTALLATION - OF BACKFLOW DEVICES OR BY TEMPORARY INSTALLATION OF BLANK FLANGES BY NOVEMIBER 22, 1991 FLOW SHIELD INSTALLATION ON SIX EXPANSION JOINTS IN SERVICE \\'VATER SUPPLY LINES FOR BEARING COOLING AND COMPONENT COOLING BY NOVEMBER 22, 1991 . :.(. INSTALLATION OF SUBMERSIBLE OPERATORS FOR BC/CC MOVs (REQUIRES RISK REDUCTION/BENEFIT ANAL VSIS IN e VIEW OF FLOW SHIELD INSTALLATION) RELOCATION OF POWER SOURCE FOR EXISTING TB SUMP PUMPS
ONGOING ACTIVITIES . e
- . IMPROVED SUMP PUMP RELIABILITY - MAINTAIN AT LEAST 7 PUMPS OPERABLE - AS AN INTERIM MEASURE,..
MAINTAINING 9 PUMPS OPERABLE INSPECTION PROGRAM AND SERVICE LIFE REPLACEMENT PROGRAM FOR** EXPANSION JOINTS. INSPECTl'lN PROGRAM FOR VALVE BOLTING .. e PROCEDURE REVISIONS FOR' ISOLATION*OF CW AND SW PIPING FOR MAINTENANCE DURING OUTAGES
-CONCLUSIONS IPE IS A USEFUL TOOL FOR IDENTIFYING POTENTIAL AREAS OF CONCERN SURRY MEETS -LICENSING BASIS CDF FOR INTERNAL FLOODING IN THE IPE SUBMITTAL IS OVERSTATED BASED ON - RECOGNITION OF ONGOING INSPECTION, REPLACEMENT, AND MAINTENANCE PROGRAMS FOR KEY VALVES AND EXPANSION JOINTS . GREATER NUMBER OF SUMP PUMPS ACTUALL V AVAILABLE CURRENT CDF DUE TO INTERNAL FLOODING IS 1.7E~4 PER REACTO l YEAR USING ORIGINAL ANAL VSIS METHODOLOGY e*
CONCLUSIONS
- (continued)
CDF DUE TO INTERNAL FLOODING WILL BE* FURTHER REDUCED BY NOVEMBER 22, 1991TO AT
- LEAST 9.9 E-5 PER REACTOR YEAR USING ORIGINAL ANALYSIS METHODOLOGY INTERNAL FLOODING REANALYSIS WILL QUANTIFY THE CONSERVATISMS INTHE ORIGINAL ANALYSIS*
AND IS EXPECTED TO RESULT IN A MORE REALISTIC, BUT STILL CONSERVATIVE, ESTIMATE OF CDF DUE TO INTERNALFLOODING IN THE INTERIM, ADMINISTRATIVE CONTROLS AND. ADDITIONAL SUMP PUMP CAPABILITY HAVE BEE.N IMPLEMENTED TO FURTHER RE.DUCE ANY POTENTIAL CONSEQUENCES SHOULD A FLOODING -- EVENT OCCUR I}}