ML18152A149

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Rev 1 to Risk Assessment of Surry Auxiliary Feedwater Sys Tech Spec
ML18152A149
Person / Time
Site: Surry  Dominion icon.png
Issue date: 12/31/1987
From:
ABB IMPELL CORP. (FORMERLY IMPELL CORP.)
To:
Shared Package
ML18152A148 List:
References
03-1250-1143, 03-1250-1143-R01, 3-1250-1143, 3-1250-1143-R1, NUDOCS 8810180029
Download: ML18152A149 (46)
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Text

RISK ASSESSMENT OF THE SURRY,AFW SYSTEM

.:.. TECHNICAL SPECIFICATION

  • 1Y---:3:=:1;>1:=:<)029 8:31011-PfiR-

~DOC~ 05000280 P

PDC Prepared for:

VIRGINIA POWER 5000 Dominion Blvd Glen Allen, Virginia Prepared by:

IMPELL CORPORATION 333 Research Court Technology Park/Atlanta Norcross, Georgia 30092 Report Number 03-1250-1143 Revision 1 December, 1987

---~

APPENDIX 1

SUMMARY

REPORT IMPELL PROBABILISTIC RISK ANALYSIS 32

TABLE OF CONTENTS SECTION 1.0 Introduction 2.0 Analysis Methodology 3.0 AFW System Description 4.0 Analysis Assumptions 5.0 Analysis ResuHs 6.0 References

. Appendix A - AFW FauH Trees PAGE 1

2 4

6 7

Appendix B - AFW Major Cutsets And Failure Rates 10 A-1 B-1 Report Number 03-1250-1143, Revision 1, Page iii

1.0 INTRODUCTION

As part of a program to evaluate the operational readiness of plant systems, Vir-ginia Power performed a Safety System Functional Inspection (SSFI) to assess the Auxiliary Feedwater (AFW) system design. This review covered several areas in-cluding plant modifications, design control, maintenance, and testing.

As a result of the review, it was determined that an inconsistency existed between the plant Technical Specifications requirements that govern the AFW system unit cross-connect capability and the safety analysis assumptions for Surry Units 1 and

2. This inconsistency occurs as a result of a very low probability scenario for a high energy line break in the main steam valve house of an operating unit with the other unit in cold shutdown. During this scenario, the high energy line break in the main steam valve house may cause failure of all three AFW pumps due to environmen-tal qualification considerations. This, in combination with a single active failure in the shutdown unit, could result in a loss of all AFW capability since the current Tech-nical Specifications only require one AFW pump to be available on the shutdown unit.

To address this issue, Virginia Power determined that a revision to the current plant Technical Specifications would ensure that a single active failure in the shutdown unit would not result in loss of all AFW capability. Due to various plant considera-tions, however, the current Allowable Outage Time (AOT) for the action statements in the governing sections of the Technical Specifications is too restrictive for a unit in a cold or refueling shutdown.

As a result, Virginia Power contracted with. lmpell Corporation to perform a risk as-sessment to evaluate the contribution to core melt as a result of implementing a longer AOT for the action statements. This report presents the analysis and results of the risk assessment. The results of this conservative analysis show that an AOT of fourteen days results in a negligible impact upon core melt risk for the scenario mentioned above. In addition, the new requirement to maintain two additional AFW pumps operable enhances the level of safety for all other core damage sequences that challenge the AFW system. For these reasons, it is concluded that the AOT of fourteen days for the "cross-connect 11 AFW trains is acceptable.

Report Number 03-1250-1143, Revision 1 Page 1

2.0 ANALYSIS METHODOLOGY The analysis of the Surry AFW system used traditional fault tree analysis techni-ques. The basis for the analysis was the fault tree models and data from NU REG/CR 4550 Volume 3. Use of these fault tree models and data allow for a direct com-parison to core melt probability as calculated in the subject NUREG. The minimal cut set generation and quantification of the fault tree was performed using the micro-computer code IRRAS, Version 1.0.

The fault tree model developed for the cross connect capability of the AFW system was developed using the same methodology outlined in NUREG/CR 4550 and is presented in Appendix A of this report. Diesel generator dependencies were modeled per the Boolean expressions presented in Section IV.5.15.4 of NU REG/CR 4550 Volume 3.

To verify that the results obtained from this analysis were comparable with the above NUREG, a bench mark test case was analyzed. This analysis case (CASE 1) modeled the NUREG/CR 4550 AFW fault tree exactly and duplicated the NUREG results using the identical failure rate data.

The following scenario was analyzed from a reliability basis:

Unit 1 Is operating with Unit 2 in a cold shutdown mode. The as-sumption of Unit 2 being in the cold shutdown mode is conserva-tive for this analysis because it precludes utilization of the Unit 2 turbine driven pump to supply AFW flow to Unit 1.

LCO time periods of fourteen, twenty-one, and thirty days were evaluated. The event scenario included a HELB in the vicinity of the operating unit's AFW pumps (thus failing the pumps). In addition, loss of offsite power events (LOSP) were evaluated.

to a lesser extent. This is because a LOSP initiator by itself will not fail the AFW pumps in the operating unit, thus the initiator is not limiting.

A combined LOSP/HELB event would challenge the diesel generators and fail the operating unit AFW pumps; however, the event frequency is so small (about 2E-6), that this in-itiator with subsequent AFW failure is not the limiting risk associated with an in-creased AOT.

Specifically, the cases analyzed were:

  • Case 1 - AFW system without transient failures. This case wa~ used to com-pare the system reliability results with the NUREG/CR 4550 results as a bench mark test case.
  • Case 2 - AFW with LOSP, no credit for cross connect capability.

Report Number 03-1250-1143, Revision 1 Page 2

  • Case 3 - AFW with LOSP, credit for cross connect capability, no extended LCO requirements.
  • Case 4 - AFW with HELB, no extended LCO requirements on AFW cross connect train.
  • Case 5 -AFW with HELB, 14 day LCO requirements on AFW cross connect

'train.

  • Cac;e 6-AFWwith HELB, 21 day LCO requirements on AFW cross connect train.
  • Cac;e 7 - AFW with HELB, 30 day LCO requirements on AFW cross connect train.

Report Number 03-1250-1143, Revision 1 Page 3

3.0 AFW SYSTEM DESCRIPTION The following system description is quoted from NUREG/CR 4550 Volume 3 and is provided for information.

"The Surry AFW is a three train system, two electric motor driven pumps and one steam driven pump. Each pump draws suction through an independent line from the 110,000 gallon condensate storage tank (CST). In addition, a 300,000 gallon CST, a 100,000 gallon emergency makeup tank and the fire main can be used as water supplies for the AFW pumps. Each AFW pump discharges to parallel headers.

Each of these headers can provide auxiliary feedwater flow to any or all of the three steam generators. Flow from each header to any one Steam Generator is through a normally open MOV and a locked open valve in series, paralleled with a line from the other header. These lines feed one line containing a check valve which joins the main feedwater line to a steam generator."

"The motor driven AFW pumps automatically start on receipt of an SIAS signal, loss of main feedwater, low steam generator level in any steam generator, or loss of of-fsite power. The turbine driven AFW pump automatically starts on receipt of indica-tion of low steam generator level in two of the three steam generators or -under volt-age of any of the three main RCS pumps. These signals also ensure that the sys-tem MOV's are in the correct position."

The emergency electrical power system at Surry consists of three diesel generators, with one diesel generator aligned to each unit and the remaining diesel generator designated as a *swing" diesel. Upon receipt of a Safety Injection signal, the swing diesel will automatically align to the *affected" unit.

  • In addition, the AFW system has the ability to provide AFW flow to the opposite unit through a cross-tie header. The flow can be provided from the motor driven AFW pumps or the turbine driven AFW pump. For conservatism, the analysis assumed that the *un-affected* unit is in a cold shutdown condition and the turbine driven pump is not available. A simplified flow schematic is presented on the following page.

Report Number 03-1250-1143, Revision O Page 4

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4.0 ANALYSIS ASSUMPTIONS The following conservative assumptions and ground rules were used in this analysis:

  • The loss of offsite power event was assumed to affect both Unit 1 and Unit 2, although the analysis was performed for Unit 1. Should diesel generator #2

( dedicated to unit 2) fail to start or run, diesel generator #3 would align to-Unit 2, thereby making it unavailable for Unit 1. This assumption is extreme-ly conservative since the Unit 2 power requirements would be reduced while in a shutdown condition. For power supplies to Unit 2 AFW pumps a similar assumption is made. If Diesel Generator # 1 fails then Diesel Generator # 3 is assumed unavailable to supply power to Unit 2. It is assumed that for a simultaneous loss of off site power and HELB, the swing diesel would automatically align to Unit 1. This will necessitate the operat9r to manually align the diesel to Unit 2 to provide cross-tie flow capability. This operator action is viewed as an independent action from manually aligning the Unit 2 AFW flow path.

  • Failure of ~he Unit 2 cross-connect in the open position is assumed to fail the Unit i AFW due to flow diversion to the shut down unit. This is only true if*

the Unit 1 AFW pumps are operating. If the Unit 2 pumps are providing AFW to Unit 1 through the cross connect, flow diversion back to Unit 2 is not con-sidered credible since failure of two check valves in series would be required in addition to the cross connect valve failing in the open position while in-dicating closed. The use of the 300,000 gallon CST, the emergency makeup tank, or.the fire main as a backup to the CST were not considered as recovery actions for conservatism.

  • All failure rates and probabilities used in the analysis were obtained from

. NUREG/CR 4550 Volume 3 with the exception of the extended LCO un-availability. The extended LCO unavailability was derived for this analysis.

  • The shut down unit is assumed to enter into an extended LCO once every eighteen months for any given tr_ain of AFW on the "un-affected" unit. For this analysis, the fault tree model assumes that Train A is the AFW train that enters into the LCO condition. Since the AFW trains are identical, modeling AFW Train Bas the "LCO" train would give identical results.
  • The shut down unit is a~sumed to enter into an LCO once every three fuel.

cycles (approximately 4.5 years) that affects both trains of AFW on the shut-down unit. The AOT for this LCO is three days (72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />). The only situation that would require an outage of72 hours is major piping work on the cross tie header between the two units, therefore this is assumed to he an infrequent event.

Report Number 03-1250-1143, Revision 1 Page 6

5.0 ANALYSIS RES UL TS The following initiator frequencies from NUREG/CR 4550 Volume 3 were used for t~is analysis:

Loss of offsite power 7.0E-2/yr High Energy Pipe Rupture in AFW Room 3.0E-5/yr

SUMMARY

OF RESULTS ANALYSIS CASE FA1LURE INITIATOR RESULTANT CHANGE IN RISK PROBABILITY FREQUENCY FAILURE RATE CASE 1-Bench 2.34E-4 N/A

  • N)A N/A Mark Case CASE 2-lOSP, 2.58E-4 7.0E-2 1-8E-5 N/A no cross-connect CASE 3-LOSP, 2.38E-4 7.01:-2 1.7E-5 (1.0E-6) cross-connect, noAOT CASE 4-HELB, 4.45E-3 3.0E-5 1.3E-7 N/A noAOT CASE 5A-HELB, 6.56E-3 3.0E-5 2.0E-7 7.0E-8 14dayAOT CASE5B-8.07E-3 2.1E-6 1.7E-8 NIA LOSP/HELB, 14 dayAOT CASE 6-HELB, *
  • 6.71E~3 3.0E-5 2.0E-7 7_0E-8

.21 dayAOT.

CASE 7-HELB, 6.90E-3 3.0E-5 2.1E-7 8.0E-8 30dayAOT Case 1 results were compared to the results obtained in NUREG/CR 4550 Volume 3 to provide a bench mark test case. NUREG/CR 4550 Volume 3 failure rate for the AFW system is 2E-4 (the report only presents the first significant digit). The results of Case 1 are consistent with NUREG/CR 4550 Volume 3, therefore the analytical tools used for this analysis are valid and the results obtained in Cases 2 through 7 can be compared with the NUREG/CR 4550 Volume 3 core melt probabilities.

Report Number 03-1250-1143, Revision 1 Page 7

As a means of comparison, the values presented above are compared to the Surry dominant accident sequences identifier! in Table IV.9-2 (page IV-242) of NUREG/CR 4550 Volume 3. For Case SA (14 day LCO) above, if the assumption is made that the design basis event and subsequent failure of the AFW system resulted in core melt, then the Case SA result would be approximately 0.8% of the total core melt frequency (2.5E-5). This is conservative because no credit is being given to other actions the plant may take such as entering into "feed and bleed" operation.

NUREG/CR 4550 Volume 3 credits "feed and bleed" as a recovery path. This recovery action would improve the results by approximately an order of magnitude.

In addition, credit is not given for the availability of the main feedwater pumps, which may still be operable for a HELB event. This is also conservative by approximate-ly an order of magnitude.

As a comparison, the analysis also evaluated the LOSP initiating event. NU REG/CR 4550 showed that the LOSP/AFW failure events were significant contributors to core melt frequency.

The Technical Specification proposed does not impact the NUREG/CR 4550 analysis because credit for the cross connect capability is not given in the subject NUREG. As Case 3 results show, there is relatively little im-provement in the reliability of the AFW system when crediting the cross connect capability for the non-HELB sequences. This result demonstrates that for LOSP in-itiators, the failure probability of the AFW system is relatively insensitive to the AOT for the cross-connect capability, because the AFW failure probability will be between the Case 2 result and the Case 3 result for any given AOT.

A combined LOSP/HELB event was also evaluated and the results are presented as Case SB. This event is assumed to result in a loss of the operating unit AFW pumps and the requirement to rely on the diesel generators for emergency power.

As can be seen by the r:esult, the overall failure probability is less than Case SA due to the low probability of the combined LOSP/HELB event. In addition, the AFW failure probability is only slightly greater than when on-site power is available.

The results presented are based upon an analysis which contains a significant amount of conservatism. Specifically:

  • credit i'i not given for additional actions such a feed and bleecf' operations to prevent core melt (conservative by an order of magnitude),
  • credit L'i not given for the availability of the main feed water pumps for the I I ELB initiating event (consen.1ative by an order of magnitude),
  • the Unit I !Unit 2 operatingf.<;/iutdown configuration is assumed to be 100%

during any given year ( conservative by an approximate factor of two).

Report Number 03-1250-1143, Revision 1 Page 8

The results above show that an extended AOT time frame to 14 days results in a negligible (approximately 7.0E-8) increase in core melt risk with respect to the case with no AOT (Case 4). In addition, the new requirement to maintain two additional AFW pumps operable enhances the level of safety for all other core damage se-quences that challenge the AFW system, thus a net reduction in core melt risk is achieved.

Based on the above analysis, it is concluded that an allowed outage time of four-teen days does not present an increase in the probability for core melt.

Report Number 03-1250-1143, Revision 1 Page 9

6.0 REFERENCES

1. NUREG/CR-4550Nol. 3, ANALYSIS OF CORE DAMAGE FREQUENCY FROM IN-TERNAL EVENTS: SURRY, UNIT 1, printed November 1986.
2. Memorandum to Mr. E.S. Grecheck-Surry P/S, from Mr. R.W. Calder, dated July 7, 1987, DEV/A TION REPORT AUXILIARY FEEDWATER SYSTEM CROSS-CONNECT SURRY POWER STATION..
3. SURRY POWER STATION UFSAR, Revision 1, 6/83.
4. SURRY POWER STATION TECHNICAL SPECIFICATIONS, Section 3.6, 10-12-84.
5. Drawing Number 11448-FM-68A, Revision 20.
6. Drawing Number 11448-FM-688, Revision 14.
7. Drawing Number 11448-FM-188, Revision 8.

Report Number 03-1250-1143, Revision 1 Page 1 o

  • APPENDIX A AFW FAULT TREES

i---

NOTE 1:

Tl£SE FAULT GATES HAVE BEEN MODIFIED FROM Tl£ ORIGINAL FAll..T TREE MODEL TO EVALUATE Tl£ UNIT 2 CROSS TIE CAPABILITY.

SEE SHEET 6 FOR Tl£ ORIGINAL MODEL ANO SHEETS 17 ANO 18 FOR n£ MODIFIED FAll..T TREE.

r- -

INSUFFICIENT FLON THROUGH PIPE SEGMENT PS89

/

INSUFFICIENT FLOW THROUGH PIPE SEGMENT PSB3 I

MOTOR OPERATED VALVE FN151E PLUGGED I

I SEE NOTE l AFN2 AFN3 INSUFFICIENT FLOW TI-IUIUGH PIPE SEGMENT PSB9 ANO PS90 INSUFFICIENT FLOW TO ALL THREE STEAM GENERATORS FROM AU.

THREE AFW PLJM>S INSUFFICIENT FLON T.ml.lGH PIPE SEGIENT PS93 TO STEAM GENERATOR A CHECK VALVE CV27 FAILS TO OPEN INSUFFICIENT FLOW THROUGH PIPE SEGMENT PS90 r- -

INSUFFICIENT FLOW TtlUJGH PIPE SEGMENT PSB4 I

SEE NOTE 1 TITLE MOTOR OPERATED VALVE FN151F PLUGGED SURRY FAULT TREE AFW-L DRAWING NUMBER SHEET 1/19 Report Number 03-1250-1143, Revision 0 Page A-1 CALC NUMBER 1250-054..:.coo2 REV 0

INS\\FFICIENT FLON THROUGH PIPE SEGMENT PSB7 INSUFFICIENT FLOW TtflOUGH PIPE SEGMENT PSB3 MOTOR OPERATED VALVE FN151C PLUGGED AFN1 AFN3 INSUFFICIENT FLOM THROUGH PIPE SEGMENT PSB7 ANO PSBB INSUFFICIENT FLOW TO ALL THREE STEAM GENERATORS FROM ALL TfffE AFN PlM'S INSUFFICIENT FLOM THROUGH PIPE SEGloENT PS92 TO STEAM GENERATOR B

  • INSUFFICIENT FLOM THROUGH PIPE SEGMENT PSB'1 Report Number 03-1250-1143, Revision 0 Page A-2 CHECK VALVE cv~e FAILS TO OPEN INSUFFICIENT FLOW THROUGH PIPE SEGMENT PSBB TITLE MOTOR OPERATED VALVE FN1510 PLUGGED SURRY FAULT TREE AFW-L DRAWING NU"4BER SHEET 2/19 CALC NUMBER 1250-054-C002 REV 0

i*

INSlFFICIENT FLON T~UGH PIPE SEGMENT PSB5 INSI.FFICIENT FLOW THROUGH PIPE SEGMENT PSB3 MOTOR OPERATED VALVE FN151A PLUGGED AFN1 AFNi!

INSUFFICIENT FLON THROUGH PIPE SEGMENT PSm! ANO PS86 INSUFFICIENT FLOW TO ALL THREE STEAM GENERATORS FROM ALL THREE AFW PUloPS INSUFFICIENT FLON Tl*IOUGH PIPE SEGfoENT PS91 TO STEAM GENERATOR C INSI.FFICIENT FLOW THROUGH PIPE SEGMENT PSB4 Report Number 03-1250-1143, Revision O Page A-3 Cl£CK VALVE CVB9 FAILS TO OPEN INSUFFICIENT FLOW THROUGH PIPE SEGMENT PSB6 TITLE MOTOR OPERATED VALVE FN151B PLUGGED SURRY FAULT TREE AFW-L DRAWING NUMBER SHEET 3/19 CALC NUMBER 1250-054-C002 REV 0

NOTE 1: FOR THE LOSP INITIATOR. THESE EVENTS HAYE BEEN SEPARATELY MODELED DOWN TO THE DIESEL GENERATOR INTERFACE.

SEE SHEETS 13 AND 19 FOR THE DETAILED MODEL.

FOR NON-LOSP INITIATORSb THESE GATES HAYE BEEN REPLACE BY BASIC EVENTS FOR BUS FAILURES (CASE 1)

FAlA..TS IN PIPE SEGtENT PSB2 (PUMP TRAIN 38) 1 POWER NOT AVAILABLE FROM BUS IJ AFW13 AFW1<1 INSUFFICIENT FLOW THROUGH PIPE SEGMENTS PSBO, PSB1, AND PSB2 INSUFFICIENT FLOW THROUGH PIPE SEGliENT PS82 AFW16 AFW17 AFW18 POWER NOT AVAILABLE FROM DC BUS 18 NO ACTUATION SIGNAL TO AFW PUMP 38 SEE NOTE 1 Report Number OJ-125J-1143, Rcvis1on 0 Page A-4 INSUFFICIENT WATER AVAILABLE FROM 110,000 GALLON CST AFW-TNK-VF-CST UNDETECTED LEAKAGE THROUGH CHECK VALVES CV27, cv~e. OR cvag TITLE SURRY FAULT TREE AFW-L DRAWING NUMBER SHEET 4/19 CALC NUMBER 1250-054-C002 REV 0

NOTE 1: FOR LDSP INITIATOR, THESE EVENTS HAVE BEEN SEPARATELY MODELED DOWN TO THE DIESEL GENERATOR INTERFACE.

SEE SHEETS 11 ANO 19 FOR THE DETAILED MODEL.

FDR NON-LOSP INITIATORS, THESE GATES HAYE BEEN REPLACED BY BASIC EVENTS FOR BUS FAILURES (CASE 1)

INSUFFICIENT NATER AVAILABLE FORM 110,000 GALLON CST UNDETECTED LEAKAGE THROUGH CHECK VALVES CV27, CV!!B, OR CV89 AFN-CCF-LF-STMBD 3

AFW13 AFW14 AFW16 INSUFFICIENT FLOW THROUGH PIPE SEGMENTS PSBO, PSBI.

AND PSB2 INSUFFICIENT FLOW TtftOUGH PIPE SEGloENT PSB1 INSUFFICENT FLOW THROUGH PIPE SEGloENT PSBO r---- ---------

1 FAULTS IN PIPE SEGMENT PSB1 (PUMP TRAIN 3AI I

POWER NOT AVAILABLE POWER NOT AVAILABLE I

FROM BUS SH FROM DC BUS IA AFW-PSF-LF-PTR3A I

I L-------------------~

SEE NOTE 1 TITLE NO ACTUATION SIGNAL TD AFN PlMP 3A AFN-ACT-FA-PMP3A SURRY FAULT TREE AFW-L DRAWING NUMBER SHEET 5/19 Report NUi:il.Jer 03-1250-1143, P-evision 0 Page J\\-:-5 CALC NUMBER 1250-054-C002 REV 0

NOTE 1:

Tt£SE FAULT GATES HAVE BEEN MODIFIED FROM Tl£ ORIGINAL FAlA.T TREE MODEL TO EVALUATE Tl£ UNIT 2 CROSS TIE CAPABILITY.

SEE SHEETS 17 Atll 18 FOR Tl£ MODIFIED FAIJ..T TREE.

AFW20 AFW21 LOSS OF STEAM FLOW FROM STEAM GENERATOR A

INSUFFICIENT STEAM FLOII THROUGH PIPE SEGMENTS PS95, PS96, ANO PS97 AFW22 LOSS OF STEAM FLOW FROM STEAM GENERATOR B

LOSS OF STEAM FLOW FROM STEAM GENERATOR C

r-----------------------------, r-----------------------------,

AFW7 AFW9 AFWU FAll..TS IN PIPE SEGMENT PSBl (1£ADER Al INSUFFICIENT FLOW THROUGH PIPE SEGMENT PSB3 FLOW DIVERSION TD UNIT 2 THOUGH PIPE SEGMENT PS9'4 INSUFFICIENT FLON THROUGH PIPE SEGMENTS PSBO, PSBt, AND PS82 AFWB AFW10 AFW12 FLOW DIVERSION TO UNIT 2 THOUGH PIPE SEGMENT PS9<1 AFN-PSF-FC-XCONN 2

INSUFFICIENT FLON THROUGH PIPE SEGMENT PS8<1 INSIFFICIENT FLON THROUGH PIPE SEGMENTS PSBO, PSB1, AND PSB2 FAULTS IN PIPE SEG~NT PSB* (1£ADER Bl L-----------------------------J L-----------------------------J SEE NOTE 1 SEE NOTE 1 Report Number 03-1250-1143, Revision 0 Page A-6 TITLE SURRY FAULT TREE AFW-L ORANING NUMBER SHEET 6/19 CALC NUMBER 1250-054-C002 REV 0

LOSS OF FLOW THROUBH ADV-HS11!2A INSUFFICIENT WATER AVAILABLE FRO" 111.111 GALLON CST INSUFFICIENT STEA" FLOW TO TOPFW2 THROUGH PIPE SEGHENT P998 NO ACTUATION SIGNAL TD ADV-HS112A AFW-ACT-FA-VLVA INSUFFICIENT FLOW THROUBH PIPE SEGHENT PSBI!

AFWlS UNDETECTED LEAKAGE THROUGH Ct£CI< VALVES CV27. C~B. OR CVB9 INSUFFICIENT STEAM FLOW THROUGH PIPE SEBMENTS PS9S. PS96.

AND PS97 FAULTS IN PIPE SEGHENT PSBl!l CTUABINE DRIVEN PUHP TRAIN 21 INSUFFICIENT.STEAM FLOW THROUGH PIPE SEGMENTS PS95, PS96, AND PS97 Report Number OJ-1250-1143, Revision 0 Page A-7 INSUFF STEAH FLOW TO TOPFW2 THROUGH PIPE SEG PS98 AND PS99 INSUFFICIENT STEAH FLOW TO TOPFW2 THROUGH PIPE SEGHENT PS99 NO ACTUATION SIGNAL TD AOV-H911!28 LOSS OF FLOW THRDU8H ADV-HSU28 AFW-ACT-FA-VLVB TITLE SURRY FAULT TREE AFW-L ORAIIING NUHBER SHEET 7/19 CALC NUHBER 12~0-0~... -c002 REV 0

CHECK VALVE 1-FN-309 FAILS TO OPEN CHECK VALVE 1-FN-273 FAILS TO OPEN XCONN1 CHECK VALVE 1-FW-272 FAILS TO OPEN INSUFFICIENT FLOW FROM UNIT 2 CROSS TIE TO PSB3 XCONN2 TRAIN A AND B IN LCO LCD-AFW-TRAINAB CROSS CONNECT MOTOR OPERATED VALVES FAIL TO OPEN XCONN4 INSUFFICIENT FLOW FROM UNIT 2 PUMPS UNIT 2 AFW PUMPS FAIL TO OPERATE AFW PUMP 2-FW-P-3A FAILS TITLE AFN PUMP 2-FW-P-3B FAILS SURRY FAULT TREE AFW-L DRAWING NUMBER SHEET B/19 Report Number 03-1250-1143, Revision 1 Page A-8 CALC NUMBER 1250-054-C002 REV 1

CHECK VALVE 1-FW-310 FAILS TO OPEN XCONN15 INSUFFICIENT FLOW FROM UNIT 2 CROSS TIE TO PSB-4 TRAIN A AND B IN LCD Report tlu111ber 03-1250-1143, Revision 1 Page A-9 INSUFFICIENl FLOW FROM UNIT 2 PUMPS TITLE SURRY FAULT TREE AFW-L DRAWING NUMBER SHEET 9/19 flEV 1

CALC NUMBER 1250-054-C002 _____ __. _

LOSS OF POWER TO BUS 2H1 MOTOR OPERATED VALVE' FIU60A FAIL TO OPEN TRAIN A IN LCO XCONN3 MOTOR OPERATED VALVE FW160A FAIL TO OPEN AFW-MOV-CC-160A CROSS CONNECT MOTOR OPEflATED VALVES FAIL TO OPEN Report Number 03-1250-1143, Revision 1 LOSS OF POWER TO BUS 2J1 XCONNU Page A-10 MOTOR OPERATED VALVE FW160B FAIL TO OPEN TITLE MOTOR OPERATED VALVE FW160B FAIL TO OPEN SURRY FAULT TREE AFW-L DRAWING NUMBER SHEET 10/19 CALC NUMBER 1250-054-C002 HEY 1

DIESEL GENERATOR 1 FAILS TO START FAILURE TD RESTORE DFFSITE PDNER IN DtE HO~

PONER NOT AVAILABLE FROM BUS 1H1 DIESEL GENERATOR 1 IN MAINTENANCE DIESEL GENERATOR l FAILlR Report Number 03-1250-1143, Revision 0 Page A-ll e I DIESEL GENERATOR l FAILS TD RUN TITLE SURRY FAULT TREE AFW-L ORANJNG NUMBER SHEET 11/19 CALC NUMBER 125()-054-C002 REV 0

DIESEL GENERATOR 2 FAILS TO START XCONNB XCONN6 FAILURE TO RESTORE OFFSITE POWER IN ONE HOUR NR0SP-1HR POWER NOT AVAILABLE FROM BUS 2H1 DIESEL GENERATOR 2 IN MAINTENANCE Report Number 03-1250-1143, Revision 1 DIESEL GENERATOR FAILURE EDG2 XCONN12 Page A-12 DIESEL GENERATOR 2

. FAILS TO RUN TITLE SURRY FAULT TREE AFW-L DRAWING NUMBER SHEET 12/19 CALC NUMBER 1250-054-C002 REV 1

DIESEL GENERATOR 3 FAILS TO START OEP-DGN-FS-DG03 POWER NOT AVAILABLE FROH BUS lJl FAILURE TO RESTORE OFFSITE POWER IN ONE HOUR DIESEL GENERATOR 3 IN HAINTENANCE DIESEL GENERATOR 3 FAILS TD RUN DIESEL GENERATORS EDG2, EDG3 FAILURE DIESEL GENERATOR 2 FAILS TD START Report Number 03-1250-1143, Revision 0 Page A-13 DIESEL GENERATOR 2 IN HAINTENANCE DIESEL GENERATOR 2 FAILS TO RUN TITLE SURRY FAULT TREE AF\\1-L ORAIIING NUHBER SHEET 13/19 CALC NUHBER 1250-05"4-C002 REV 0

DIESEL GENERATOR 3 FAILS TO START XCONN9 XCONN7 FAILURE TO RESTORE OFFSITE POWER IN ONE HOUR POWER NOT AVAILABLE FROM BUS 2J1 DIESEL GENERATOR FAILURE DIESEL GENERATOR 3 IN MAINTENANCE DIESEL GENERATOR 3 FAILS TO RUN DIESEL GENERATOR 1 FAILS TO START OPERATOR FAILS TO ALIGN 0603 TO BUS 2J AFW-XHE-F0-0603 Report Number 03-1250-1143, Revision 1 Page A-14 DIESEL GENERATOR 1 IN MAINTENANCE DIESEL GENERATOR 1 FAILS TO RUN TITLE SURRY FAULT TREE AFW-L DRAWING NUMBER SHEET 14/19 CALC NUMBER 1250-054-C002 REV 1

PUMP 2-FW-P-3A FAILS LOSS OF POWER TO BUS 2H1 LOSS OF POWER TO BUS 2H1 AFW PUMP 2-FW-P-3A FAILS LOSS OF POWER TO DC BUS 2A OPERATOR FAILS TD CROSS CONNECT UNIT 2 POWER NOT AVAILABLE FROM DC BATTERY 2-1A Report Number 03-1250-1143, Revision 1 Page /\\-15 INSUFFICIENT WATER AVAILABLE FROM 110,000 GALLON CST UNDETECTED LEAKAGE THROUGH CHECK VALVES CV27, CV58, CVB9 AFW-CCF-LF-STMBD TRAIN A IN LCD TITLE SURRY FAULT TREE AFW-L DRAWING NUMBER SHEET 15/19 CALC NUMBER 1250-054-C002 REV 1

PUMP 2-FW-P-3B FAILS LOSS OF POWER TO BUS 2...11 LOSS OF POWER TO BUS 2...11 AFW PUMP 2-FW-P-3B FAILS LOSS OF POWER TO DC BUS 28 OPERATOR FAILS TO CROSS CONNECT UNIT 2 POWER NOT AVAILABLE FROM DC BATTERY 2-1B Report Number 03-1250-1143, Revision 1 Page A-16 INSUFFICIENT WATER AVAILABLE FROM 110,000 GALLON CST UNDETECTED LEAKAGE THROUGH CHECK VALVES CV27, CV5B, CVB9 AFW-CCF-LF-STMBD TITLE SURRY FAULT TREE AFW-L DRAWING NUMBER SHEET 16/19 CALC NUMBER 1250-054-C002 REV 1

NOTE: THIS IS THE HOOIFIED FAULT TREE TO ACCOUNT FOR THE CROSS TIE CAPABILITY BETWEEN SUVIY UNITS INSUFFICIENT FLOW FROH UNIT 2 CROSS TIE TO PSB3 XCDNN2 INSUFFICIENT SUPPLY TO PIPE SESHENT PS83 PIPE FAULTS IN PIPE SE6HENT PS83 (t£ADER Al AF117 INSUFFICIENT FLOW THROUGH PIPE SEGHENT PSB3 INSUFFICIENT FLOW FROH UNIT l FLOW DIVERSION TO UNIT 2 THROUGH PIPE SEGMENT PS91 AFW-PSF-FC-XCONN INSUFFICIENT FLOW THROUGH PIPE SEGHENTS PSBB. 81.

AND PS82 Report Number 03-1250-1143, Revision O Page A-17 TITLE SURRY FAULT TREE AF\\J-L DRAWING NUHBER SHEET 17/19 CALC NUHBER 1250-05-1-C002 REV

  • 0

NOTE: THIS IS Tl£ MODIFIED FAULT TREE TO ACCOUNT FDA Tl£ CROSS TIE CAPABILITY BETWEEN SURRY UNITS INSUFFICIENT FLOW FROM UNIT 2 CROSS TIE TD PSB<4 INSUFFICIENT SUPPLY TO PIPE SEGIENT PSB4 PIPE FAULTS IN PIPE SEGMENT PSB4 (1£ADER Bl AFW-PSF-LF-HDRB AFWB INSUFFICIENT FLOW THROUGH PIPE SEGMENT PSB4 INSUFFICIENT FLOW FROM UNIT 1 XCDNN19 INSUFFICIENT FLOW THROUGH PIPE SEGMENTS PSBO, 81, AND PS82 Report Number 03-1250-1143, Revision 0 FLOW DIVERSION TO UNIT 2 THROUGH PS9<4 AFW-PSF-FC-XCONN Page A-18 e

TITLE SURRY FAULT TREE AFW-L DRAWING NUMBER SHEET 18/19 CALC NUMBER 1250-054-C002 REV 0

POWER NOT AVAILABLE FROM DC BUS 1A POWER NOT AVAILABLE FROM BUS 1H1 AFN23 POWER NOT AVAILABLE FROM DC BATTERY 1A DCP-BAT-LP-BATA POWER NOT AVAILABLE FROM DC BUS 18 POWER NOT AVAILABLE FROM BUS 1J1 POWER NOT AVAILABLE FROM DC BATTERY 1B DCP-BAT-LP-BATB TITLE SURRY FAULT TREE AFW-L DRAWING NUMBER SHEET 19/19 Report Number 03-1250-1143, r-evision 0 Page A-19 CALC NUMBER 1250-054-C002 REV 0

. APPENDIX B MAJOR CUTSETS AND FAILURE RATES This appendix presents the major minimal cutsets for the following analysis cases:

  • Ca"e 1 - AFW system without transient failures. This case was used to com-pare the system reliability results with the NUREG/CR 4550 results as a bench mark test case.
  • Case 2 - AFW with LOSP, no credit for cross connect capability.
  • Case 3 - AFW with LOSP, credit for cross connect capability, no extended LCO requirements.
  • Case_ 4 - AFW with HELB, no extended LCO requirements on AFW cross connect train.
  • Ca"e 5 -AFW with HELB, 14 day LCO requirements on AFW cross connect train.
  • Case 6 - AFW with HELB, 21 day LCO requirements on AFW cross connect train.
  • Case 7 - AFW with HELB, 30 day LCO requirements on AFW cross connect train.

Report Number 03-1250-1143, Revision 1, Page B-1

MAJOR MINIMAL CUT SETS FOR CASE 1 AFW SYSTEM WITHOUT TRANSIENT FAILURES

  • AFW-PSF-LF-PTR3A AFW-PSF-LF-PTR3B AFW-PSF-LF-PTRN2 AFW-TNK-VF-CST FAILURE RATE DESCRIPTION 6.30E-004 Auto Initiation of Pump 3A faHs 6.30E-004 Auto Initiation of Pump 38 fans 1.00E-004 Leakage thru check vtvs 27, 58, 89 1.30E-004 Flow diversion to Unit 2 8.SOE-003 Faults In Pump Train 3A 8.SOE-003 Faults In Pump Train 38 3.10E-002 Faults In Turbine Pump Unit 1 1.30E-006 lnsuff. water In CST Report Number 03-1250-1143, Revision O, Page B-2

MINIMAL CUT SETS FOR CASE 2 AFW WITH LOSP, NO CROSS-CONNECT

      • Min Cut Upper Bound = = = 2.58E-004 FAIL PROB CUTSET 1.30E-004 AFW-PSF-FC-XCONN 1.00E-004 AFW-CCF-LF-STMBD 2.24E-006 AFW-PSF-LF-PTR3A AFW-PSF-LF-PTR3B AFW-PSF-LF-PTRN2 1.30E-006 AFW-TNK-VF-CST FAILURE RATES COMPONENT ID AFW-CCF-LF-STMBD AFW-PSF-FC-XCONN AFW-PSF-LF-PTR3A AFW-PSF-LF-PTR38 AFW-PSF-LF-PTRN2 AFW-TNK-VF-CST FAILURE RATE DESCRIPTION 1.00E-004 Leakage thru check vlvs 27, 58, 89 1.30E-004 Flow diversion to Unit 2 8.SOE-003 Faults in Pump Train 3A 8.SOE-003 Faults In Pump Train 38 3.10E-002 Faults In Turbine Pump Unit 1 1.30E-006 lnsuff. water In CST Report Number 03-1250-1143, Revision O, Page B-3

r MINIMAL CUT SETS FOR CASE 3 AFW WITH LOSP, CROSS-CONNECT

      • Min Cut Upper Bound = = = 2.38E-004 FAIL PROB CUTSET 1.30E-004 AFW-PSF-FC-XCONN 1.00E-004 AFW-CCF-LF-STMBD 1.16E-006 AFW-PSF-LF-PTRN2 NROSP-1 HR OEP-DGN-FS-DG01 OEP-DGN-FS-DG02 1.16E-006 AFW-PSF-LF-PTRN2 NR0SP-1HR OEP-DGN-FS-DG01 OEP-DGN-MA-OG02 1.16E-006 AFW-PSF-LF-PTRN2 NROSP-1 HR OEP-DGN-FS-DG02 OEP-DGN-MA-DG01 1.16E-006 AFW-PSF-LF-PTRN2 NROSP-1 HR OEP-DGN-MA-DG01 OEP-DGN-MA-DG02**

8.03E-007 AFW-PSF-LF-PTRN2 NROSP-1 HR OEP-DGN-FR-DG01 OEP-DGN-FS-DG02 8.03E-007 AFW-PSF-LF-PTRN2 NR0SP-1HR OEP-DGN-FR-DG01 OEP-DGN-MA-DG02 8.03E-007 AFW-PSF-LF-PTRN2 NROSP-1 HR OEP-DGN-FR-DG02 OEP-DGN-FS-DG01 8.03E-007 AFW-PSF-LF-PTRN2 NROSP-1 HR OEP-DGN-FR-DG02 OEP-DGN-MA-DG01 5.SSE-007 AFW-PSF-LF-PTRN2 NROSP-1 HR OEP-DGN-FR-DG01 OEP-DGN-FR-OG02

    • This cutset places the unit In a more restrictive LCO action statement.

Report Number 03-1250-1143, Revision O, Page 8-4

FAILURE RATES COMPONENT ID FAILURE RATE DESCRIPTION AFW-CCF-LF-STMBD 1.00E-004 Leakage thru check vlvs 27, 58, 89 AFW-PSF-FC-XCONN 1.30E-004 Row diversion to Unit 2 AFW-PSF-LF-PTRN2 3.10E-002 Faults In Turbine Pump Unit 1 NR0SP-1HR 3.10E-001 Failure to restore offslte power OEP-DGN-FR-DG01 7.60E-003 DG 01 faffs to run OEP-DGN-FR-DG02 7.60E-003 DG 02 faffs to run OEP-DGN-FS-DG01 1.10E-002 DG 01 fails to start OEP-DGN-FS-DG02 1.10E-002 DG 02 falls to start OEP-DGN-MA-DG01 1.10E-002 DG 01 In maintenance OEP-DGN-MA-DG02 1.10E-002 DG 02 In maintenance Report Number 03-1250-1143, Revision 0, Page B-5

MINIMAL CUT SETS FOR CASE 4 AFW WITH HELB, CROSS-CONNECT

FAILURE RATES COMPONENT ID FAILURE RATE DESCRIPTION AFW-CCF-LF-STMBD 1.00E-004 Leakage thru check vlvs 27, 58, 89 AFW-CKV-FT-272 1.30E-004 Check valve fails AFW-CKV-FT-273 1.30E-004 Check valve fails AFW-MDP:FS-2P3A 8.SOE-003 Unit 2 pump 3A fails AFW-MDP-FS-2P38 8.SOE-003 Unit 2 pump 38 fails AFW-PSF-LF-PTR3A 1.00E+OOO Faults in Pump Train 3A AFW-PSF-LF-PTR38 1.00E+OOO Faults in Pump Train 38 AFW-PSF-LF-PTRN2 1.00E+OOO Faults in Turbine Pump Unit 1 AFW-XHE-FO-UNIT2 4.00E-003 Operator fails to cross connect Report Nw nber 03-1250- 1 *, 43, Revision 1, Page B-7

MINIMAL CUT SETS FOR CASE 5 AFW WITH HELB, 14 DAY AOT

FAIL PROB CUTSET 1.44E-005 AFW-MOV-CC-160A AFW-MOV-CC-160B AFW-PSF-LF-PTR3A AFW-PSF-LF-PTR3B AFW-PSF-LF-PTRN2 FAILURE RATES COMPONENT ID AFW-CCF-LF-STMBO AFW-CKV-FT-272 AFW-CKV-FT-273 AFW-MDP-FS-2P3A AFW-MDP-FS-2P3B AFW-MOV-CC-160A AFW-MOV-CC-1608 AFW-PSF-LF-PTR3A AFW-PSF-LF-PTR3B AFW-PSF-LF-PTRN2 AFW-XHE-FO-UNIT2 LCO-AFW-TRAIN-A LCO-AFW-TRAINAB FAILURE RATE DESCRIPTION 1.00E-004 Leakage thru check vtvs 27, 58, 89 1.30E-004 Check valve fails 1.30E-004 Check valve fails 8.50E-003 Unit 2 pump 3A fails 8.50E-003 Unit 2 pump 3B fails 3.BOE-003 MOV fails closed 3.BOE-003 MOY fails closed 1.00E+OOO Faults in Pump Train 3A 1.00E+OOO Faults in Pump Train 3B 1.00E+OOO Faults in Turbine Pump Unit 1 4.00E-003 Operator fails to cross connect 2.60E-002 Train A in LCO 1.BOE-003 Train A and B in LCO

-Report Number 03-1250-1143, Revision 1, Page B-9

MINIMAL CUT SETS FOR CASE 6 AFW WITH HELB, 21 DAY AOT

FAIL PROB CUTSET 1.44E--005 AFW-MOV-CC-160A AFW-MOV-CC-160B AFW-PSF-LF-PTR3A AFW-PSF-LF-PTR3B AFW-PSF-LF-PTRN2 FAILURE RATES COMPONENT ID FAILURE RATE DESCRIPTION AFW-CCF-LF-STM80 1.00E-004 Leakage thru check vlvs 27, 58, 89 AFW-CKV-FT-272 1.JOE-004 Check valve fails AFW-CKV-FT-273 1.30E-004 Check valve fails AFW-MDP-FS-2P3A 8.SOE--003 Unit 2 pump 3A fails AFW-MDP-FS-2P38 8.SOE--003 Unit 2 pump 38 fails AFW-MOV-CC-160A 3.BOE--003 MOV fails closed AFW-MOV-CC-160B 3.BOE--003 MOV fails closed AFW-PSF-LF-PTR3A 1.00E +000 Faults in Pump Train 3A AFW-PSF-LF-PTR38 1.00E+OOO Faults in Pump Train 38 AFW-PSF-LF-PTRN2 1.00E+OOO Faults in Turbine Pump Unit 1 AFW-XHE-FO-UNIT2.

4.00E--003 Operator fails to cross connect LCO-AFW-TRAIN-A 3.BOE--002 Train A In LCO LCO-AFW-TRAINAB 1.BOE--003 Train A and 8 in LCO Report Number 03-1250-1143, Revision 1, Page B-11

MINIMAL CUT SETS FOR CASE 7 AFW WITH HELB, 30 DAY AOT

FAIL PROB CUTSET 1.44E-005 AFW-MOV-CC-160A AFW-MOV-CC-1606 AFW-PSF-LF-PTR3A AFW-PSF-LF-PTR3B AFW-PSF-LF-PTRN2 FAILURE RATES COMPONENT ID AFW-CCF-LF-STMBD AFW-CKV-FT-272 AFW-CKV-FT-273 AFW-MDP-FS-2P3A AFW-MDP-FS-2P3B AFW-MOV-CC-160A AFW-MOV-CC-160B AFW-PSF-LF-PTR3A AFW-PSF-LF-PTR3B AFW-PSF-LF-PTRN2 AFW-XHE-FO-UNIT2 LCO-AFW-TRAIN-A LCO-AFW-TRAINAB FAILURE RATE DESCRIPTION 1.00E-004 Leakage thru check vtvs 27, 58, 89 1.30E-004 Check valve fails 1.30E-004 Check valve falls 8.SOE-003 Unit 2 pump 3A faffs 8.SOE-003 Unit 2 pump 38 fails 3.BOE-003 MOV tans closed 3.BOE-003 MOV tans closed 1.00E+OOO Faults In Pump Train 3A 1.00E+OOO Faults in Pump Train 38 1.00E+OOO Faults in Turbine Pump Unit 1 4.00E-003 Operator faHs to cross connect 5.40E-002 Train A In LCO 1.BOE-003 Train A and B In LCO Report Number 03-1250-1143, Revision 1, Page B-13

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