Text

Analysis of Allowed Outage Times at Byron Generating Station
	ML20206F521
Person / Time
Site:	Byron
Issue date:	06/30/1986
From:	Bozoki G, Cho N, Chu T, Chu T, Xue D, Youngblood R; BROOKHAVEN NATIONAL LABORATORY
To:	; Office of Nuclear Reactor Regulation
References
	CON-FIN-A-3810 BNL-NUREG-51930, NUREG-CR-4404, NUDOCS 8606240502
	Download: ML20206F521 (118)
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---w NUREG/CR-4404 BNL-NUREG-51930 Analysis of Allowed Outage Times at the Byron Generating Station Prepared by N. Z. Cho, T-L. Chu, D. Xue, G. E. Bozoki, R. W. Youngblood Brookhaven National Laboratory l Prepared for i U.S. Nuclear Regulatory Commission l

?DR $000K05000454 2 860630 P

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NUREG/CR-4404 BNL-NUREG-51930 Analysis of Allowed Outage Times at the Byron Generating Station

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Manuscript Completed: December 1985 Date Published: June 1986 Prepared by N. Z. Cho, T-L. Chu, D. Xue, G. E. Bozoki, R. W. Youngblood i

Brookhaven National Laboratory Upton, NY 11973 1

Prrpured for Division of PWR Licensing-B Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission W:shington, D.C. 20555 l

NRC FIN A3810 1

l 1

ABSTRACT This report provides a critical review of the methods used in WCAP-10526 which proposed that allowed outage times (A0Ts) for a number of safety systems in the Byron Generating Station be increased from 3 to 7 days, and presents an independent estimate of the change in risk involved in the A0T extension. It also presents results of several sensitivity studies.

Alsc included are a survey of methods that can be used to evaluate nuclear power plant technical specifications and a description of pairwise importance measures.

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CONTENTS Page ABSTRACT.................................................................

iii LIST OF FIGURES..........................................................

vi LIST OF TABLES........................................................... vii ACKN0WLEDGEMENTS.........................................................

ix EXECUTIVE

SUMMARY

xi 1.

INTRODUCTION AND BACKGR0VND.........................................

1-1 1.1 Objectives and Scope...........................................

1-1 1.2 Organization of the Report.....................................

1-1 2.

BYRON SAFETY SYSTEMS................................................

2-1 2.1 Sy s t e m De s c r i p t i o n.............................................

2 - 1 2.2 Techni ca l Speci fi cat i ons....................................... 2-3 3.

REVIEW 0F BYRON LCO RELAXATION STUDY................................

3-1 3.1 Methods........................................................

3-1 3.2 Assumptions, Models, and Data Base.............................

3-2 3.3 Li mi tati ons a nd Is sue s.........................................

3-5 4.

REEVALUATION........................................................

4-1 4.1 Approaches.....................................................

4-1 4.1.1 Faul t Tree Li nki ng App roach............................. 4-1 4.1.2 Interpolation Between Two Bounding T

's.................

4-1 4.2 Mod i f i c a t i o n s.............................. [................... 4 - 2 4.2.1 Fau l t Tree Mod i fi cati on s................................ 4-2 4.2.2 Event Tree Modi fi cati on s................................ 4-5 4.3 Results........................................................

4-6 l

4.3.1 I n t ro d u c t i o n............................................ 4 - 6 4.3.2 Resul ts o f Fou r Model s..................................

4-7 4.3.3 Si ngl e-Event and Pai rwi se Importances................... 4-8 4.3.4 S u mm a ry................................................. 4 - 8 5.

SUMMARY

AND C0NCUSIONS..............................................

5-1 APPENDIX A:

SURVEY OF APPLICABLE METH0DS................................ A-1 APPENDIX B:

PAIR IMPORTANCE MEASURES IN SYSTEMS ANALYSIS................ A-2 APPENDIX C:

DOMINANT CUT SETS AND PAIRWISE IMPORTANCE OUTPUTS........... C-1 APPENDIX D:

EVENT DEF I NI TIONS AND N0TATIONS............................. D-1 REFERENCES...............................................................R-1 v

LIST OF FIGURES Figure #

Title Page 4.1 Event tree for loss of essential service water initiator......

4-9 4.2 Core Damage Frequency as a Function of T Model 0.................................r's for 9 Cases in 4-51 4.3 Core Damage Frequency as a Function of T Model 1.................................r's for 9 Cases in 4-52 4.4 Core Damage Frequency as a Function of T Model 2................................. r 's f o r 9 Ca s e 4-53 4.5 Core Damage Frequency as a Function of T Model 3................................. r 's fo r 7 Cases 4-54 A.1 Bl ock confi gu rati on of a sampl e probl em....................... A-6 A.2 Average unavailability and core damage fre o f A0T..................................... q u e n cy a s f u n c t i o n s A-9

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LIST OF TABLES i

Table #

Title Page 2.1 De s i g n C o mp a r i s o n.............................................

2-4 2.2 Byron Technical Specifications................................

2-5 4.1 Updated Basic Event Data......................................

4-10 4.2a Comparison of Initiator Frequencies (Events / Reactor Year).....

4-13 4.2b Sensitivity Study Results for Loss of Service Water Initiator Frequency (3-Day A0T)$........................................

4-14 4.3 Mean System Unavailabilities..................................

4-15 4.4 Definition of Cases...........................................

4-15 4.5 Plant Damage States and Core Damage Frequencies for Model O Case 1........................................................

4-16 4.6 Plant Damage States and Core Damage Frequencies for Model 0 Case 2........................................................

4-17 4.7 Plant Damage States and Core Damage Frequencies for Model 0 Case 3........................................................

4-18 4.8 Plant Damage States and Core Damage Frequencies for Model 0 Case 4........................................................

4-19 4.9 Plant Damage States and Core Damage Frequencies for Model 0 Case 5........................................................

4-20 4.10 Plant D+1 age States and Core Damage Frequencies for Model 0 Case 6........................................................

4-21 4.11 Plant Damage States and Core Damage Frequencies for Model 0 Case 7........................................................

4-22 4.12 Plant Damage States and Core Damage Frequencies for Model 0 Case 8........................................................

4-23 4.13 Plant Damage States and Core Damage Frequencies for Model 0 Case 9........................................................

4-24 4.14 Plant Damage States and Core Damage Frequencies for Model 1 Case 1........................................................

4-25 4.15 Plant Damage States and Core Damage Frequencies for Model 1 Case 2........................................................

4-26 l

4.16 Plant Damage States and Core Damage Frequencies for Model 1 Case 3........................................................

4-27 4.17 Plant Damage States and Core Damage Frequencies for Model 1 Case 4........................................................

4-28 4.18 Plant Damage States and Core Damage Frequencies for Model 1 Case 5........................................................

4-29 4.19 Plant Damage States and Core Damage Frequencies for Model 1 Case 6........................................................

4-30 4.20 Plant Damage States and Core Damage Frequencies for Model 1 i

Case 7........................................................

4-31 4.21 Plant Damage States and Core Damage Frequencies for Model 1 Case 8........................................................

4-32 4.22 Plant Damage States and Core Damage Frequencies for Model 1 Case 9........................................................

4-33 4.23 Plant Damage States and Core Damage Frequencies for Model 2 Case 1........................................................

4-34 4.24 Plant Damage States and Core Damage Frequencies for Model 2 Case 2........................................................

4-35 l

vii i

LIST OF TABLES (Continued)

Table #

Title Page 4.25 Plant Damage States and Core Damage Frequencies for Model 2 Case 3........................................................

4-36 4.26 Plant Damage States and Core Damage Frequencies for Model 2 Case 4........................................................

4-37 4.27 Plant Damage States and Core Damage Frequencies for Model 2 Case 5........................................................

4-38 4.28 Plant Damage States and Core Damage Frequencies for Model 2 Case 6........................................................

4-39 4.29 Plant Damage States and Core Damage Frequencies for Model 2 1

Case 7........................................................

4-40 4.30 Plant Damage States and Core Damage Frequencies for Model 2 Case 8........................................................

4-41 4.31 Plant Damage States and Core Damage Frequencies for Model 2 Case 9........................................................

4-42 4.32 Plant Damage States and Core Damage Fre Case 1.................................quenci es fo r Model 34-43 4.33 Plant Damage States and Core Damage Frequencies for Model 3 Case 2........................................................

4-44 4.34 Plant Damage States and Core Damage Fre Case 3.................................quencies for Model 3 4-45 4.35 Plant Damage States and Core Damage Fre Case 5.................................quencies for Model 3 4-46 4.36 Plant Damage States and Core Damage Fre Case 6.................................q uenci es for Model 34-47 4.37 Plant Damage States and Core Dama Case 7...........................ge Frequencies for Model 3 4-48 4.38 Plant Damage States and Core Dama Case 8...........................ge Frequencies for Model 3

............................. 4-49 4.39 Comparison of Mean Core Dama 0peration...................ge Frequencies from One Unit

.................................. 4-50 A.1 Failure Data Used in the Sample Problem.......................

A-7 A.2 Testing Schedules Assumed in the Sample Problem...............

A-7 A.3 Average Unavailability and Core Damage Probability at One Year Usi ng 3 Ini ti ators Per Yea r............................ A-8 C.1 Dominant Cut Sets of Loss of Service Water Initiator for Case 1 (Total = 9.47x10-4/ry)......................................

C-2 C.2 Dominant Cut Sets of Loss of Service Water Initiator for Case 2 (Total = 7.21x10-3/ry)......................................

C-3 C.3 Dominant Cut Sets of Core Damage for Model 1 - Case 1 (Total - 6.95x10-4/ry)........................................

C-4 C.4 Dominant Cut Sets of Core Damage for Model 1 - Case 2 (Total - 4.82x10 3/ry)........................................

C-6 C.5 Dominant Cut Sets of Core Damage for Model 2 - Case 1 (Total - 8.60x10 5/ry)........................................

C-8 C.6 Dominant Cut Sets of Core Damage for Model 2 - Case 2 (Total - 5.44x10-4/ry)........................................

C-10 C.7 Single-Event and Pairwise Importances for Model 1 - Case 1....

C-12 C.8 Single-Event and Pairwise Importances for Model 1 - Case 2....

C-16 viii l

ACKNOWLEDGEMENTS We benefited in several ways from discussions with N. Hanan of BNL.

We are grateful to A. Spano and A. Buslik of NRC for helpful discussions and for their encouragement throughout the work.

We also acknowledge J. Merz and D.

Sharp of Westinghouse and T. Tramm of Commonwealth Edison whose timely trans-fer of information helped to expedite this work.

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l EXECUTIVE

SUMMARY

This study presents a review of the Westinghouse report (WCAP-10526) which proposed that the allowed outage times (A0Ts) for a number of systems at the Byron Generating Station be increased from 3 to 7 days, with an estimate of the change in risk involved in the A0T extensions.

The methodology used in WCAP-10526 is the usual probabilistic risk assessment (PRA) technique, namely, the static fault tree method.

Appendix A of this study reviews and compares other methods also applicable to the A0T problem with the static fault tree method and concludes that the static fault tree method is generally conservative and can be used for many of the A0T problems. The A0T problem in technical specifications is fundamentally a de-cision problem. The WCAP-10526 approach to the A0T problem of using probabil-istic analyses is sound and logically correct.

In this respect, the approach in WCAP-10526 is a step in the right direction.

Although, in general, the effort in WCAP-10526 is commendable, the details of the approach can be sub-stantially improved.

The limitations and issues in WCAP-10526 arise mostly from the incomplete support state development in the support state decomposi-tion approach (also known as the large event tree /small fault tree approach or as the method of event trees with boundary conditions) which is a particular static fault tree method chosen and implemented in WCAP-10526, and from the use of the mean value (of the prior distribution) of the mean time to repair for repair duration in the component unavailability expression.

These are recapitulated as follows:

(1)

Incompleteness of initiators--loss of service water and loss of a dc bus.

(2)

Incomplete support state development in the support state decomposi-tion approach.

(3) No explicit treatment of A0Ts due to the use of mean time to repair (MTTR) for repair duration Tr-(4) Use of a single Tr for all systems.

(5) Simultaneous maintenance between systems.

(6) Asymmetric modeling of redundant trains.

(7) No considertion of battery depletion in station blackout sequences.

To obtain an independent estimate of the change in risk involved in the Byron proposal, this study modified the models in WCAP-10526 to reflect the issues and to improve the limitations above by employing the fault tree link-ing approach and interpolation between two bounding T 's.

The fault tree r

linking approach provides holistic information for the top event (e.g., core damage) and a basic mathematical model which facilitates sensitivity studies in a later phase, e.g., through importance analyses.

In particular, the use of pairwise importance measures (described in Appendix B) provides valuable insights in evaluation of the technical specifications.

The approach of interpolating between two bounding Tr's provides not only an upper bound on xi

core damage frequency allowed in the technical specifications, but also appro-priate core damage frequency which is only slightly conservative for a more definitive repair duration Tr-The reevaluation in this study focused on the core damage frequency from one unit operation only, since most of the shared systems between Unit 1 and Unit 2, in particular, the Essential Service Water System and the Component Cooling Water System, are not completely in place.

Among several risk measures, only core damage frequency was explicitly reevaluated, since it is affected directly by A0T changes for the Byron systems under consideration, and the available PRA results of several plants indicate, in general, that the core damage frequency is the limiting constraint to the proposed numerical guidelines of the NRC safety goals and that the health risks are below the safety goals.

The difference in core damage frequency estimates between WCAP-10526 and this study is considered significant (1.41 x 10 4 vs 6.95 x 10 4/ry in exist-ing A0Ts). This is primarily attributed to the loss of service water initia-tor identified and quantified in this study, coupled with the induced seal LOCA given loss of service water system.

Note that the Essential Service Water System at Byron consists of two trains with a single pump in each train and that the probability of a seal LOCA given loss of service water system was nominally assumed to be 0.5.

The results in this study on importance rankings of individual systems with regard to A0Ts, however, generally agree with the conclusion in WCAP-10526 that the largest impact on plant risk from changes in the A0Ts comes from the Essential Service Water System and the diesel genrators.

(Note,how-i ever, that individual system-level rankings are not provided in WCAP-10526.)

Similarly to the results of the basic model, the results of several sensitivi-ty models also indicate the same trends on the individual system rankings:

the Essential Service Water System and the diesel generators are the first two dominant contributors to the increments in core damage frequency due to the A0T extensions and next in importance is the Auxiliary Feedwater System.

The effects of the containment heat removal systems (Containment Spray System and Containment Fan Coolers) and the ECCS (Charging pumps, Safety Injection pumps, and RHR pumps) are considered to be small.

The results of pairwise importance analysis indicate that contributions of simultaneous maintenance of two components existing in the model are small. This reflects the fact that many of the potential simultaneous mainte-nances were already eliminated from the model because of the support system operability requirement in technical specifications. These simultaneous main-tenances were retained in the WCAP-10526 model, resulting in a conservative estimate.

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1-1 1

1.

INTRODUCTION AND BACKGROUND 1.1 Objectives and Scope This is a report on a program which was performed by Brookhaven National Laboratory (BNL) for the U.S. Nuclear Regulatory Commission (NRC).

The pro-gram is entitled " Review of WCAP-10526, Byron Limiting Conditions for Opera-tion (LCO) Relaxation Study." This program is part of the NRC's effort to re-spond to a recent request by the Commonwealth Edison Company who owns the Byron Generating Station.

Commonwealth Edison has proposed that the allowed outage times (A0Ts) for a number of systems in the Byron Generating Station be increased from 3 to 7 days.

The proposal (l) (WCAP-10526) uses the usual probabilistic risk assessment (PRA) methods, i.e., event tree / fault tree tech-niques, to conclude that the health and safety of the public would not be sig-nificantly affected by the proposed changes in A0Ts.

The overall objectives of this program are two-fold:

(1) To assess the methods in WCAP-10526 used in the context of the A0T problem, and- (2) To ob-j tain an independent estimate of the change in risk involved in the Byron pro-posal.

This review and reevaluation focus on the core damage frequency (among several risk measures) due to internal initiators at Byron Unit 1 in view of 1

the following considerations:

1.

It is the core damage frequency, not the health risks, that is af-fected directly by A0T changes for the Byron systems under considera-tion.

2.

The available PRA results for several nuclear power plants indicate that in most cases the core damage frequency rather than the health of the NRC safety goals. g raint to the proposed numerical guidelines risks is the limiting co While the Byron Generating Station will eventually operate two units, single-unit operation is analyzed because most of the shared systems between Unit 1 and Unit 2 at Byron are not completely in place.

It is noted that limiting conditions of operation (LCO) with specified A0Ts and surveillance testing intervals (STIs) constitute two primary aspects of technical specifications (TS) in a nuclear power plant.

The NRC is devel-oping methods and procedures for TS evaluation in a program called "Proce-dures for Evaluating Technical Specifications (PETS)."

The PETS program, which is currently performed by Brookhaven National Laboratory, considers) gen-eric as well as specific issues related to technical specifications.(5,30 1

1.2 Organization of the Report The report is organized as follows:

Section 2 briefly describes the safety systems and technical specifications at Byron for which the A0T exten-sions are requested.

Section 3 provides the review results of the Byron LC0 Relaxation Study and identifies limitations and issues.

Section 4 provides the basic approach taken in this study with specific modifications introduced in the reevaluation, as well as the reevaluation results for several models

,_,-m.

1-2 and cases.

Section 5 provides general conclusions of the study and implica-tions of the sensitivity analysis results presented in Section 4.

Appendix A and Appendix B include a survey of methods applicable to evaluation of nuclear power plant technical specifications and a description of pairwise importance measures, respectively. Appendix C provides the dominant minimal cut sets for the initiator event of loss of Essential Service Water System and for the core damage.

Appendix C also includes the outputs of pairwise importance calcula-tions.

Finally, Appendix D provides the event definitions and notations used in the event tree / fault tree models.

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2-1 2.

BYRON SAFETY SYSTEMS

2.1 System Description

The Byron Generating Station Units 1 and 2, located in Ogle County, Illi-nois, are Westinghouse PWRs of thermal output of 3425 MW per unit.

The fol-lowing is a brief description of important safety-related systems at Byron.

For convenience, Table 2.1 summarizes major design differences between the WCAP-10526 are largely from the Zion Probabilistic Safety Study.\\ pi Byron and Zion plants, since basic assumptions, models, and datg se used in 2

Electric Power Systems (EPS)

The plant consists of two main generating units, Units 1 and 2.

Two phy-sically independent 345-kV circuits are provided from the switchyard for each unit, one through the unit's assigned system auxiliary transformers (SATs) and the other through the SATs of the other unit.

Each unit has two SATs connect-ed to a single 345-kV circuit from the switchyard. Each SAT supplies power to a single redundant division. The SATs step the 345-kV system down to the sta-tion 4160-V and 6900-V power systems.

In the event of a failure of one system auxiliary transformer, removable links can be relocated to connect the other SAT to supply both divisions.

Each SAT is capable of simultaneously supplying the design basis accident (DBA) loads of both divisions of one unit and the safe shutdown loads of both divisions of the other unit.

Two unit auxiliary transformers (UATs) are connected to the main genera-tor buses of each unit by the isolated phase bus duct.

They are the normal power sources for the nonsafety-related buses.

The unit's four nonsafety-re-lated buses serve the reactor coolant pumps and other large auxiliary loads.

Each SAT provides offsite power to an ESF 4-kV bus of the unit.

In addition, each system auxiliary transformer serves as a reserve power source for the unit's nonsafety-related buses as well as a second source of offsite power for the corresponding ESF bus of the other unit.

Each unit has four 4160-V buses.

Two buses supply power to ESF loads as well as certain essential loads.

The other two buses supply power to larger, nonsafety-related auxiliary loads, as well as small, nonsafety-related loads.

A tie breaker between the 4160-V, ESF and nonsafety-related buses may be man-ually closed in the event of the loss of both the UAT and SAT power sources to these loads.

Onsite emergency power for each unit is supplied by two diesel generators which are each automatically started by either a safety injection signal or an emergency bus undervoltage signal on its respective ESF bus.

There is one diesel per ESF bus.

The ESF actuation will sequentially load the diesel gen-erator. The de systems for each unit consist of one 250-V and one 125-V non-class 1E battery systems and two independent and redundant Class IE 125-V bat-tery systems and static chargers.

Emergency Core Cooling Systems (ECCS)

ECCS design is based on the availability of a minimum of three out of four accumulators, one out of two charging pumps, one out of two safety J

i

2-2

" njection pumps, and one out of two residual heat removal (RHR) pumps and i

associated valves and piping.

Following a LOCA event, passive (accumulators) and active (injection pumps and associated valves) systems will operate. After the inventory of the refueling water storage tank (RWST) has been depleted, long term recirculation will be provided by taking suction from the containment sump and discharging to the reactor coolant system (RCS) cold and/or hot legs via high and inter-mediate head pumps.

The system automatically opens the RHR pump suction valves from the containment sump, with operator action required to isolate the RWST.

No operator action is required for the first 20 minutes following a large break LOCA.

The low-pressure passive accumulator system consists of four pressure vessels partially filled with borated water and pressurized with nitrogen gas to 640 psia.

The high head injection system consists of two centrifugal charging pumps which provide high pressure injection of boric acid solution into the RCS.

In addition, two intermediate head safety injection pumps deliver fluid to the RCS.

Both types of pumps are manually aligned to take suction from the RHRs discharge during the recirculation mode.

Low head injection is accomplished by two RHR pump subsystems.

Containment Heat Removal Systems (CHRS)

The active containment heat removal systems include the containment spray system (CSS), the reactor containment fan cooler (RCFC) system, and the resid-ual heat removal system (RHRS).

The containment spray system consists of two independent 100 percent capacity trains each containing a motor-driven pump. Containment spray injec-tion and caustic reduction continue until the low-low level of the RWST is reached. At that time, operator action is required to transfer the CSS to the recirculation mode.

The RCFC system is arranged in two trains of two RCFC units each with each unit capable of providing 50 percent of the required RCFC cooling capaci-ty.

During normal operation, only one RCFC train is operating with both fans at. high speed and the essential service water (ESW) cooling coils removing heat to control containment temperature.

The system automatically commences operation in the post-LOCA mode with both trains, fan motors on low speed and the ESW cooling coils carrying the entire RCFC cooling load.

The RHR serves as an active containment heat removal system during the recirculation phase following a LOCA.

Auxiliary Feedwater System (AFWS)

The system consists of two redundant, safety-related essential trains and one nonessential, manually-initiated (startup) train, all of which supply water to all four steam generators.

One essential train consists of a 100 percent capacity motor-driven pump.

The second train contains a 100 percent capacity di rect-dri ven diesel pump.

Both safety-related pumps start

{

2-3 automatically in transient or accident situations.

A third nonessential (startup) motor-driven pump, with considerably greater than minimum capacity, is nrovided for use during startup and normal shutdown.

This pump must be operated in series with a condensate / condensate booster pump and is manually started. Offsite power must be available to use the nonessential train. AFWS water supply to the essential trains is normally provided by the condensate water storage tank (CWST) with a backup supply available from the safety re-lated essential service water system.

Water supply for the nonessential startup train is provided by the condenser hotwell.

Service Water System (SWS)

Both essential and nonessential service water systems are provided for cooling various plant equipment.

Essential service water system (ESWS) sup-plies cooling water to safety-related equipment from the essential service water cooling towers.

Each unit's ESWS consists of two redundant, indepen-dent, full capacity closed cooling piping trains.

Each serves redundant essential components and is capable of providing 100 percent of the required cooling in all operating modes.

Each train contains one full-capacity pump which is powered from a separate emergency power source.

The two trains are connected to a common header which can be crosstied to the other unit's ser-vice water system.

Component Cooling Water System (CCWS)

The CCWS supplies cooling water to safety-related and nonsafety-related plant components during normal operation and to safety-related components during accident and emergency conditions.

The CCWS consists of five pumps, three heat exchangers, and two surge tanks serving two redundant cooling trains in both units. Each of the four pumps is powered from a separate emer-gency power source in its associated plant unit.

The fifth (maintenance spare) pump can be powered from any of the emergency power sources.

During normal operation, two pumps, two heat exchangers, and the two surge tanks serve both units. One pump and one heat exchanger are sufficient to carry the load in either unit during emergency conditions.

2.2 Technical Specifications Technical specifications (TS) in a nuclear power plant are specific re-quirements on its day-to-day operation designed to protect public health and safety.

Two primary aspects of the TS are (1) limiting conditions of opera-tion (LCO) with specified allowed outage times (A0Ts) and (2) surveillance testing intervals (STIs).

Table 2.2 summarizes the existing technical specifications (21) related to the Byron systems for which A0T extensions (from 3 to 7 days for all sys-l tems) are requested in WCAP-10526.

Note that WCAP-10526 does not request changes in STIs.

2-4 Table 2.1 Design Comparison!

BYRON ZION Owner Commonwealth Edison Commonwealth Edison Site Ogle County, Illinois Lake County, Illinois Capacity 3425 MWT 325D MWt Type 4 Loop Westinghouse PWR (2 Units) 4 Loop Westinghouse PWR (2 Units)

LPIS &

4 Accumulators 4 Accumulators LPRS 2 RHRS Pumps 2 RHRS Pumps CSIS &

2 CS Pumps 3 CS Pumps' CSRS HPIS &

2 SI Pumps 2 SI Pumps HPRS 2 Centrifugal Charging Pumps 2 Centrifugal Charging Pumps CHRS 4 RCFC Fan / Cooler Units 5 RCFC Fan / Cooler Units 1 Motor-driven Pump 2 Motor-driven Pumps AFWS 1 Direct-driven Diesel Pump 1 Turbine-driven Pump 1

1 Motor-driven Nonsafety Pump 2 Essential Power Divisions with 3 Essential Power Divisions with EPS 2 (Dedicated) Diesel Generators 2 (Dedicated) + 1 (Swing) Diesel Generators CCWS 5 Pumps & 3 HXs Shared by Both 5 Pumps & 3 HXs Shared by Both Units Units ESWS 4 Pumps Shared by Both Units 6 Pumps Shared by Both Units 1 Design parameters are for a unit unless otherwise noted.

2 The 3rd is a direct-driven diesel pump.

l

I 2-5 Table 2.2 Byron Technical Specifications

System STI A0T Comments DGs Monthly 3 days a

77WS Monthly 3 days b

13HEi Monthly 3 days EI5Ei Monthly 3 days EIIRT

- T3i Monthly 3 days CF Monthly 3 days c

ECCS Chg Monthly 3 days SI Monthly 3 days RHR Monthly 3 days

As a general rule, technical specifications require that when one train becomes inoperable due to test or maintenance, the other re-dundant train be operable including all necessary attendant equip-ment that are required for the train to perform its function.

a Staggered testing.

STI should be weekly if the number of failures in the last 20 valid tests is greater than 1.

b Staggered testing.

cBoth trains can be in outage for 3 days if the CS trains are oper-able.

3-1 3.

REVIEW 0F BYRON LC0 RELAXATION STUDY 3.1 Methods Basic methods that address the A0T problem in the Byron LC0 Relaxation Study (WCAP-10526) are the usual PRA techniques (6,12) that can be charac-terized as the methods of " static" fault trees.

The static fault tree method is a technique used to evaluate higher level performance measures of a plant, e.g., core damage frequency and health risks, by propagating, through a set of binary structure functions, time-averaged (over some baseline periods) perfor-mance measures of lower level basic components.

Appendix A of this report reviews and compares other methods which are also applicable to the A0T problem with the static fault tree method.

A con-clusion of Appendix A is that the static fault tree method is simple to use and generally conservative in comparison with other methods and can be used for many of the A0T decision problems.

In the static fault trees, a performance measure of a component, e.g.,

its time-averaged unavailability, is usually represented by (I)

Q = 1/2 A T + qd

A T, + r/T + m Tfr+9h s

o where A = standby failure rate, 3

A = operating failure rate, g

= maintenance frequency or a parameter which is a function of A '

m s

f T = surveillance testing interval, T, = mission time of an active component after an event, T = test duration, T = repair duration, p

qd = failure probability on demand of an active component, and gh = human error probability during test, repai r, or actuation of an active component.

T In Eq. (1) above, a most relevant term to the A0T problem is mf r j

which is a contribution of maintenance outage to the component unavailabil-corresponding to A0T = 3 days and A0T ity.

In WCAP-10526, two values for Tr

= 7 days, respectively, were used to determine core damage frequencies and health risks.

i

3-2 There are two static fault tree methods generally used in large-scale PRAs, which shall be called here:

(1) the support state decomposition proach also known as the method of event trees with hgundary conditions (ap-12) or as the large event tr fault tree approachp3) and (2) the fault linking approach.(12fe/small t ree The particular static fault tree method chosen and implemented in WCAP-10526 is the support state decomposition approach.

3.2 Assumptions, Models, and Data Base Basic assumptions, models, and a b employed in WCAP-10526 are daj;2 Zion Probabilistic Safety Study (ZPSS).(H )2) ase 1argely from the Byron Risk Study (BRS which is in turn based upon the 23 Accident initiators considered in WCAP-10526 are essentially the same as those in ZPSS.

Slightly different frequencies were used for somq of the ini-tiators in consideration of Byron-specific features.

A review (24) of ZPSS judged that the set of initiators is reasonably complete.

However, it also identified loss of component cooling water and loss of a dc bus as important initiators.

In Zion, the former initiator would lead to loss of seal cooling of the reactor coolant pumps.

Because of design differences between the two plants, the corresponding initiator for Byron would be loss of essential ser-vice water, which was not considered in WCAP-10526.

The latter initiator would lead, in Zion, to failure of feed and bleed operation in conjunction with failure of the Auxiliary Feedwater System, because dc power is required to operate P0RVs.

An initiator corresponding to this was not considered in WCAP-10526.

Event trees used in WCAP-10526 are slightly modified and expanded ver-sions of those for the Zion PSS.

In particular, operator actions during acci-dents were refined for most of the transient initiators.

For several tran-sient initiators, induced small LOCAs were also explicitly identified and transferred to the Event Tree 3, while for the loss of offsite power initiator they were developed within the same event tree.

ATWS events were always transferred to a separate event tree and devel-oped further there.

It is noteworthy that WCAP-10526 introduced an event tree node (S ) in the ATWS event tree which stands for ECCS operability after a 0

reactor vessel pressure spike in the event of failure of pressure relief through PORVs and safety valves.

In general, the event tree development in WCAP-10526 involves very de-tailed delineation and enumeration of accident scenarios leading to a large number of accident sequences.

However, it should be also recognized that, as PRA experience indicates, the high degree of detail and multitude of delinea-tions introduced in front-end systems analysis are not always supported by the adequate phenomenological modeling that follows.

(0f course, the detailed analysis is justified and desirable if it leads to better representation and more accurate quantification of accident sequences.)

This observation seems relevant also to the event tree modeling in WCAP-10526.

For example, consid-eration of the Sodium Hydroxide Addition System (NA) in almost all the event trees and questioning the Auxiliary Feedwater System (L-1) availability in sequences from #47 to #82 in the small LOCA event tree exemplify this point.

A particular sequence which questioned the NA availability was assumed to lead to core damage and to the same plant damage states, regardless of its

3-3 availability or unavailability.

Thus, NA is inconsequential in core damage and in health risks.

It is noticed in the small LOCA event tree that the sequences from #65 to #82 are replicas of the sequences from #47 to #64 in terms of system success and failure combinations after L-1 and in terms of resulting plant damage states.

Thus, L-1 is also inconsequential in core damage and in health risks through these sequences.

Similar situations occur also in other event trees. Quantification of these unwarranted and replicated sequences is equivalent to calculating Pr(AF +AB) instead of Pr(A).

Calcula-tion of Pr(AF + AB) can be more difficult than that of Pr(A) if A and B are large fault trees and they share common components.

Because of the support state decomposition approach which will be mentioned later in this section, and the fact that the support states are not complete (note that the Component Cooling Water System is a support system but that it is modeled in the event trees), calculation of Pr(AB + AB) or incorporation of system success in event tree quantification will entail conservative approximations.

Detailed fault trees of the Byron safety systems for which A0T extensions are requested were developed in WCAP-10526.

In general, the fault tree models are considered to be appropriate.

One aspect of technical specifications, namely, prohibition of simultaneous maintenance of redundant trains within a system was incorporated by using NOT gates in system-level fault trees. How-ever, another aspect of technical specifications, namely, the requirement of operability of support systems when some other systems are under maintenance, was not modeled. This of course will result in conservative estimates of un-availabilities.

Fault trees for some of the event tree nodes, e.g., operator actions and induced LOCA events, were not developed.

Instead, conditional un-availabilities depending on support states in Zion PSS were applied directly to Byron.

There are " asymmetry" aspects introduced in some of the fault tree models in WCAP-10526.

In the fault trees of the Essential Service Water System (ESWS) and the Component Cooling Water System (CCWS), which are normally oper-ating systems, it was assumed a priori that train A is normally operating and thus not subject to maintenance and failure to start (it is noted, however, that it is modeled symmetrically for the loss of offsite power event).

It would be more realistic and there would be less bias and imbalance between the two trains if it is assumed that train A is normally operating while train B is in standby with a probability of 0.5 and vice versa.

Another " asymmetry" aspect occurs in the unavailability modeling between tests of the Auxiliary Feedwater System (AFWS) two trains; 1/4AsT was used for train A and 3/4AsT for train B instead of 1/2AsT for both trains as in Eq. (1) of Section 3.1.

As mentioned in Section 3.1, the particular static fault tree method used in WCAP-10526 is the large event tree /small support state decomposition approach.

For one unit operation, the following six support states were con-sidered from combinations of operating and failed states of Bus 141, Bus 142, and Essential Service Water System (ESWS):

(1) Bus 141, Bus 142, and ESWS all available, (2)

Bus 141 and Bus 142 available but ESWS unavailable, (3) Bus 141 unavailable, Bus 142 and ESWS available, (4) Bus 141 available, Bus 142 unavailable, ESWS available, (5) Bus 141 and Bus 142 unavailable but ESWS available,

(

(6) Bus 141, Bus 142, and ESWS all unavailable.

(

3-4 Two additional support states, which complete the total set of eight exhaus-tive and mutually exclusive support states, are:

(7) Bus 141 available, Bus 142 and ESWS unavailable, (8) Bus 141 unavailable, Bus 142 available, ESWS unavailable.

In WCAP-10526, these two states were merged with state (6), a more degraded state, to reduce the number of conditional evaluations of the event trees.

It is noted that probabilities of these two support states are zero for the loss of offsite power initiator.

Thus, the six support state modeling in WCAP-10526 will result in conservative evaluations for all initiators other than the loss of offsite power initiator.

As mentioned earlier, the support state development in WCAP-10526 is not complete because the CCWS is not included in the support states but modeled in the event trees, even though it is a support system.

This will render an accurate event tree quantification difficult or cumbersome.

In general, the complete development of support states for a plant of complicated structure results in a large number of support states which will defeat any efficacy of the large event tree /small support state decomposition approach.

For the 7-day A0T situation, the mean value of the prior distribution (assumed to be lognormal) for mean time to repair reported in the Zion PSS was l

used as the repair duration Tr in Eq. (1) of Section 3.1.

For the 3-day A0T situation, as in the existing Byron technical specifications, WCAP-10526 assumed subjective values for the two parameters of the lognormal distribution and derived the mean value.

Thus, the effect of A0Ts on mean times to repair was implicitly considered but not based on experience data.

It is also noted that a single T was used for all systems for a given A0T situation.

Spe-p cifically,19 hours2.199074e-4 days 0.00528 hours 3.141534e-5 weeks 7.2295e-6 months and 34 hours3.935185e-4 days 0.00944 hours 5.621693e-5 weeks 1.2937e-5 months were used for 3-day A0Ts and 7-day A0Ts re-spectively, for all systems for which A0T extensions were requested.

i Basic event data used in WCAP-10526 are from the open literature and, in general, considered appropriate except for several events to which the source data were not correctly applied.

(These are summarized in Section 4.3.)

Hardware failure data and maintenance frequencies are from Zion PSS and are Bayesian update specialized for the Zion plant, except for the diesel-driven pump in AFWS in which case the data in a Torrey Pines study (25) were used.

WCAP-10526 developed a set of 8-factor approach common cause failure formula in which common cause failure data of Ref 4 26 were used.

It was found that some of the coefficients in the common cause failure formulae are not cor-rect.

On pages 38-3 and 3B-5 in WCAP-10526, 3 should read 4 for 1/4 logic.

On page 38-5, 3 should read 4 for 2/4 and 3/4 logic, and 6 should read 12 for 2/4 logic. However, these corrections did not affect the results significant-ly. Operator failure probabilities are from Ref. 27.

It should be noted that the operator failure probabilities during an accident in Ref. 27 were for the control room crew, not for an individual.

It is noted that demand failure probabilities for active components, e.g., diesels, pumps, and fans, used in WCAP-10526 and the Zion PSS also in-clude standby failure rate contributions during test periods, in addition to

" intrinsic" demand failure probabilities.

In other words, the existing data represent the first two terms in Eq. (1) of Section 3.1 as a single composite (the raw data were processed in this way); qd value 1/2 AsT + qd.

It is

=

3-5 noted that 1/2AsT is a most relevant term in a surveillance testing interval (STI) problem.

3.3 Limitations and Issues Since the discussion in Section 3.2 also included limitations and issues in WCAP-10526, they are simply recapitulated here as the following:

(1)

Incompleteness of initiators--loss of service water and loss of a de bus.

(2)

Incomplete support state development in the support state decomposi-tion approach.

i (3) No explicit treatment of A0Ts due to the use of mean time to repair (MTTR) for repair duration Tr-(4) Use of a single Tr for all systems.

(5) Simultaneous maintenance between systems.

(6) Asymmetric modeling of redundant trains.

(7) No consideration of battery depletion in station blackout sequences, t

L j

lt

4-1 4.

REEVALUATION 4.1 Approaches The basic approaches of this study to most of the issues and limitations discussed in Section 3.2 and summarized in Section 3.3 are two-fold:

(1)

Fault tree linking approach and (2) Interpolation between two bonding A0Ts.

4.1.1 Fault Tree Linking Approach (6,12)

In the fault tree linking approach, which may be also called a minimal cut set approach, system-level fault trees of frontline and support systems are linked together to form larger composite fault trees.

The levels of com-posite fault trees can vary depending on the interests of the analysts. They can be for systems, accident sequences, plant damage states, core damage, and health risks.

Once composite fault trees are formed, minimal cut sets are generated and quantified for a top event probability.

(A more efficient and effective way to generate minimal cut sets for a composite fault tree is to

" link" minimal cut sets of system-level fault trees.) Since a minimal cut set is the smallest number of combinations of basic events (not conditiored on any other events in contrast to the support state decomposition approach) which j

leads to the top event, it provides simple and direct structural information l

for the top event. Furthermore, since the union of minimal cut sets is equiv-alent to the top event and can be represented in a Boolean function, it pro-vides holistic information and a mathematical model which facilitates sensi-tivity studies in a later phase, e.g., through importance analyses.

In addition to the traditional single-event importance measures,(28) the pairwise importance measures (29) (see also Appendix B) provide analysts and decision makers with valuable insights in evaluation of the technical spe-cifications.

The pairwise importance measures are defined for a pair of events, e.g., a maintenance act in conjunction with another maintenance act, a human error, or a hardware failure.

l 4.1.2 Interpolation Between Two Bounding Tr3 The third and fourth issues in Section 3.3 are related to the repair dur-in ation Tr in Eq. (1) of Section 3.1.

The question is how to specify Tr order to appropriately model the repair outage contribution to the component as an " average" re-unavailability.

A reasonable way may be to specify Tr pair time while the plant is online, i.e.,

A0T T = <t > =

J t g(t) dt + A0T [A0Tg(t)dt (1) r r

0 where g(t) is the repair time probability density function.

There are two difficulties in using the above equation.

Fi rst, g(t),

{

which is a function of components and of A0Ts, is not readily available from experience data base.

Second, it may also be a function of maintenance policy which in turn may be influenced by A0Ts unpredictably.

i i

1

i 4-2 Since this problem appears to be unresolved, this study takes a bounding analysis approach.

The approach is to evaluate, for example, two core damage frequencies using two bounding Tr's and to interpolate between them to pro-vide appropriate core damage frequency (with a slight conservatism) for a de-finitive Tr determined later when more information becomes available.

(This interpolation can be done not only for core damage frequency but also for other measures such as plant damage state frequencies and health risks.)

It is based on two observations.

First, in Eq. (1) above, Tr is bounded by the first term and by A0T.

Second, from Figure A.2 in Appendix A, it is observed that core damage frequencies obtained from all methods are monotonically in-creasing functi herent models,(on,g of A0Ts and that '. hey all exhibit weak convexity.

(For co-2W the monotonicity and convexity can be proved easily for the static fault tree and FRANTIC methods.)

These observations also suggest a natural way to perform sensitivity studies with regard to A0Ts.

The two bounding Tr's are 19 hours2.199074e-4 days 0.00528 hours 3.141534e-5 weeks 7.2295e-6 months and 168 hours0.00194 days 0.0467 hours 2.777778e-4 weeks 6.3924e-5 months which correspond to the first term in Eq. (1) for the 3-day A0T and the full A0T of 7 days, respectively.

Note that, in WCAP-10526, the two values for T corresponding to A0T = 3 days and r

A0T = 7 days are 19 hours2.199074e-4 days 0.00528 hours 3.141534e-5 weeks 7.2295e-6 months and 34 hours3.935185e-4 days 0.00944 hours 5.621693e-5 weeks 1.2937e-5 months , respectively.

4.2 Modifications This section provides a brief description of the modifications made to i

the models in WCAP-10526 during this study.

4.2.1 Fault Tree Modifications The orginal system-level fault trees provided to us by Commonwealth Edison and Westinghouse were modified as follows to reflect more accurately the technical specifications, reconfiguration of the system during mainte-nance, and symmetry of redundant trains.

EPS Maintenance overlaps of diesel generators with AFWS and ESWS were de-leted.

Diesel generator failure now includes a failure mode from loss of cooling provided by ESWS.

j A mission time of six hours for a diesel generator was used as a typi-cal " average" mission time, as in most of recent PRAs (WCAP-10526 spe-cified a mission time of 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months but the data actually used in calcu-lations corresponded to one hour).

The event of induced loss of offsite power (LOSP) and the events of nonrecovery for LOSP and for diesel generator failures were included in the system fault tree.

The 480-V ac bus unavailability now includes failures of a 4160-V--

480-V stepdown transformer and an associated breaker, i

4-3 ESWS

- The two trains are modeled as symmetric.

Train A is normally opera-ting and train B is in standby with a probability of 0.5 and vice versa.

The following valves are found from technical specifications to be tested monthly, not quarterly as in WCAP-10526:

OXVSX138AC/BC, IMVSX001AC/BC, 1XVSX143AC/BC.

AFWS Maintenance overlaps of AFWS trains with diesel generators were de-leted.

Symmetric test intervals were used for standby failures between tests (1/2 AsT in both trains).

The system fault tree now includes maintenance unavailability of the suction water source.

C_S, The CS pumps are tested monthly, not quarterly.

C_ F,

- The containnent fan coolers are tested monthly, not quarterly.

If the CS trains are operable, the two CF trains are allowed to be out for 3 days.

- Failures to restore cooling coil block valves after maintenance are conditioned on the maintenance events:

XVSXAHM/BHM/ CHM /DHM.

)

Failures of service water valves are included and conditioned on stroke-test failures:

ISX016A/B, ISX027A/B.

CCWS Asymmetry, due to the assumption that train A is normally operating and train B is on standby, was removed by assuming that 50% of the time a train is on standby and developing the fault tree conditional on the status of the train.

For pump failure to start, each pump is assigned half the probability of failure to start, and the cut set containing both pump fail to start is deleted.

For each component failure whose probability depends on the status of the train, e.g.,

check valve fails transfer closed, the failure event is represented by the Boolean sum F = FA

ASTANDBY + FB

ASTANDBY

\\

4-4 where FA is the event that the failure occurs given train A is on standby, FB is the event that the failure occurs given train B is on standby, and ASTANDBY has a probability of 0.5.

The pumps are tested monthly instead of quarterly.

- Maintenance overlaps of CCWS trains with diesel generators were deleted.

High Pressure Injection (HH1, HH2)

- If valve 8835 is left in a wrong position after test or maintenance, an audible alarm will sound in the control room.

- Maintenance activities that cause both SI pumps or both charging pumps to be unavailable were deleted.

For example, simultaneous maintenance of SI pump A and diesel generator B is not allowed by technical spe-cifications.

High Pressure Injection and Recirculation If valves 8924, 8716, 8835, 8812, 8809 are left in the wrong position after maintenance, alarms will sound in the control room.

I

- The crosstie on the discharge side of the RHR pumps is not available during the maintenance of either train, because one of the crosstie valves is closed to isolate the train being maintained.

- In order for the operators to establish recirculation, they need to close valves 8812, LCV112, 8806, and open valves 9412A,B. These oper-ator actions are assumed to be completely dependent with failure prob-ability equal to 10 4

- Valves 8716A,B are assumed to be closed in recirculation phase by operators.

MOVSI8804 failure to open is changed to input to gate CC.

Low Pressure Injection

- The crosstie on the discharge side of the RHR pumps is not available during the maintenance of either train because one of the crosstie valves needs to be closed to isolate the train being maintained.

If valves 8716, 8812, 8809 are left in the wrong position, an audible alarm will sound in the control room.

Maintenance overlaps of RHR pumps and diesel generators were deleted.

Low Pressure Injection and Recirculation In order to establish low pressure recirculation, the operators must close valves 8812A,B and open valves 9412A,B.

These operator actions

4-5 are assumed to be independent with failure probability equal to 1.5 x 10-3

- The crosstie on the discharge side of the RHR pumps is not available when either train is under maintenance.

If valves 8716, 8812, 8809 are left in the wrong position after main-tena'nce, an audible alarm will sound in the control room.

Simultaneous maintenance of RHR pumps, diesel generators, and CCWS pumps that causes both RHR trains unavailable was deleted.

4.2.2 Event Tree Modifications Specific modifications in the event trees which reflect the discussions in Section 3.2 are the following:

The inconsequential Sodium Hydroxide Addition System was removed from the event trees.

CCWS is treated as a support system and thus removed from the event trees.

Event tree node E60 in the loss of offsite power event tree (ET12A) was deleted because it was modeled in the Electric Power System fault tree.

Unwarranted sequences, e.g., the sequences from #65 to #84 in the small LOCA event tree as discussed in Section 3.2 were removed.

Event Tree 12 (loss of offsite power with onsite power available) was combined with Event Tree 12A (loss of offsite power with no onsite power available).

Sequences #29 and #56 in Event Tree 12A were further refined to con-sider feed and bleed operation.

An ATWS sequence #42 in Event Tree 14 (Reactor Trip) was deleted.

Event node So in the ATWS event tree was removed assuming no ECCS operability after an ATWS pressure soike.

Simple logic models were developed for the following event tree nodes (WCAP-10526 used Zion conditional unavailabilities) to reflect depen-dency on support systems (Event definitions and notations are provided in Appendix D):

I t

.~-

4-6

+

SA2=SA1+HH2.

~ OPl =oPF0Tr.PORVTECcf + (PoHv1Mw +Jes1N u) P0sv2Hw+JBS142W.

OP2=0P2-00+0P2-QA*OP2-QR+HH2+0P1.

-~"5P 3WPRD + ES WItJTJB STErDNB 51T20.

OP4=0P4-00+JBS141D+9BS1420.

OP5-1=OP5 TODTJBS1*lo*JBSr4zo.

OPS-2=0P5-200+JBS141D*JBS1420.

- UPa-1=0P3.

OP8-2=0P8-200+ESWAU+JBS1410*JBS1420 L K-1~=L@ DTJ8 514TD*JB STC20.

PR2=PR2-00*JRS141D*dBS1420.

S2= S2-Q A

E SW AU + S2D * ( JB5141D + JB S 147D) + 52-QC e

- An event tree was developed for the loss of service water initiator (Event Tree 17 in Figure 4.1).

The turbine trip event trea was modi-fied for this purpose by conditioning frontline systems on the loss of.

service water.

Since this initiator was not considered in WCAP-10526 and the data base for its frequency (for different A0T situations) is not available except for PWR generic data and plant-specific data for Zion in ZPSS (Note that in Table 2.1 four ESWS pumps are shared by both units at Byron and six ESWS pumps are shared by both units at Zion), this study estimated the initiator frequency for Byron by cal-culating the expected number of ESWS failures during one year interval for two different A0T situations. This was done by developing an ESWS fault tree, with renewal of an alternating system (th,qoretic considerations in modeling repairs 3'N such as ESWS.

In calculating unavaila-bility contribution due to maintenance events, the maintenance fre-quencies for the components in ESWS used in WCAP-10526 were multiplied by a factor of two.*

This factor of two comes from the fact that the maintenance frequency data for ESWS pumps in MCAP-10526 and ZPSS are the number of maintenance events averaged over total running times and standby times of all ESWS pumps, and that the relevant maintenance event, here is the event that one pump is put under maintenance given that the other pump is operating.

It was assumed that any one of the four fans in towers is sufficient to dissipate heat load expected in' var, cooling ious transient events and that no fans are necessary in three winter months.**

4.3 Results 4.3.1 Introduction The event trees and fault trees foi rae t 9 operation in WCAP-10526 in-corporating' specific modifications listed in Section 4.2 constitute the basic mathematical model of this study, which was then evaluated for various cases by employing the fault tree linking approach and interpolating between the twos bounding Tr's as described in Section 4.1.

'This was pointed out by A. Buslik.

~

- This new success criterion and related information were provided by the Byron engineers at a meeting on December 3,1985.

4-7 The two bounding Tr's considered are 19 hours2.199074e-4 days 0.00528 hours 3.141534e-5 weeks 7.2295e-6 months (referred to as A0T1) and 168 hours0.00194 days 0.0467 hours 2.777778e-4 weeks 6.3924e-5 months ( A0T2).

In the process of generating minimal cut sets, A0T2 and small cutoff (specifically, 10-8 in system-level minimal cut sets and 10-1grobabilitiesin sequence-level minimal cut sets) were used to minimize the poss ity of maintenance events being inappropriately truncated.

The SETS code was used for generation and quantification of the minimal cut sets.

In addition to the traditional single-event importance measures, the pairwise importance program described in Appendix B provided importance mea-sures for a pair of events of particular interest (e.g.,

two maintenance events or a maintenance event with a human error) in evaluating technical spe-cifications. In Appendix C are provided the dominant cut sets for the initia-tor event of loss of Essential Service Water System and for the core damage.

Appendix C also includes the results of pairwise importance calculations.

Table 4.1 shows the updated basic event data (the other data are the same with those in WCAP-10526) used to produce the results in this section and Table 4.2a provides a comparison of the initiator frequencies used in WCAP-10526 and in this study.

Table 4.2b shows the results of several sensitivity studies on the initi-ator frequency for the loss of Service Water System.

As discussed in Section 4.2.2, the initiator frequency was estimated by the expected number of ESWS failures during one year interval, using a fault tree model (the dominant cut sets are shown in Table C.1 and C.2 in Appendix C). The parameters subject to sensitivity studies were (1) failure rate for the ESWS pump to run, (2) fail-ure rate for the strainer by plugging, and (3) success criterion for the fans in cooling towers.

Table 4.3 shows the results of system-level mean unavailabilities for A0T1 and A0T2 in case of loss of offsite power initiator and of non-loss of offsite power initiators.

The column of slope /hr indicates the rate of in-crease of unavailability as a function of A0Ts.

Table 4.4 provides a key to various cases for which the results of evalu-ations are given in the following sections.

The nine cases, which classify the systems according to which A0Ts are assumed for them, were evaluated for each of the following four "models":

Model 0 - Model in WCAP-10526 with modifications in ' Section 4.2 except Event Tree 17 (loss of service water initiator) and with up-dated data in Tables 4.1 and 4.2, Model 1 - Model 0 plus Event Tree 17 (loss of service water initiator).

i I with Pr(S -QA) = 0 where S -QA is the seal LOCA event Model 2 - Model 2

2 given loss of service water (P (S -QA) = 0.5 in other models r 2 as in WCAP-10526).

Model 3 - Model I with no maintenance unavailability contributions from CCWS and ESWS.

Model 1 is the reference model in this study, of which the results are 9

considered best-estimates.

Model 0 is included for direct comparison with WCAP-10526.

Model 2 is a sensitivity study on an important parameter, that

4-8 is, the probability of the seal LOCA event given loss of service water. Model 3 assumes no maintenance outage for CCWS and ESWS to infer the effects of using linit 2 systems during maintenance.

4.3.2 Results of Four Models Tables 4.5 through 4.38 show the results of plant damage states and core damage frequencies for the four models and nine cases defined above.

It is mentioned that the blanks in the tables are due to either of the following reasons:

(1) There is no plant damage state resulting from an initiator under consideration, or (2) The frequencies are so small that the corresponding frequencies when all the systems are under A0T2 (Case 2) were less than 10-10, and thus they were truncated in the process of generating minimal cut sets.

Tables C.3 and C.4 in Appendix C show the dominant cut sets of core dam-age for Model 1 - Case 1 and Model 1 - Case 2, respectively.

Tables C.5 and C.6 show the dominant cut sets of core damage for Model 2 - Case 1 and Model 2 - Case 2, respectively.

4.3.3 Single-Event and Pairwise Importances Partial lists of sample outputs from the pairwise program are included in Tables C.7 and C.8 in Appendix C for Model 1 - Case 1 and Model 1 - Case 2.

These are the results for core damage frequency.

Several pairs involving maintenance events are noted.

For example, in the output for Model 1 - Case 2, the rows 70 and 71 show importance measures of AFWS pump A maintenance and operator failures during feed and bleed operation. The row 89 identifies ESWS pump A maintenance and AFWS pump B maintenance and indicates that contribution of these two maintenance events (which is permitted in the technical specifi-cations) to the core damage frequency is 0.09 per cent or 6.2 x 10 6 per reac-tor year.

4.3.4 Summary The results for core damage frequency are summarized in Tables 4.39 and Figures 4.2 through 4.5).

l l

E~

_oss

f Service Vater ET1.7

-S2 TR2 K-3 L-1 CS 1

1 SUCC 2

12 TEC 3

14 TE 4

15 ATVS 5

m TR E

6 17 S2 Figure 4.1 Event tree for loss of essential service water initiator.

4-10 Table 4.1 Updated Basic Event Data This Event Name Failure Mode System WCAP-10526 Study Comment

MVSI88120P OP fails to close R-1 1.4x10 4 1 suction from RWST MVCC94120P OP fails to open R-1 9.6x10 5 CC9412 valves

>1.5x10-3 1

MVS881280P OP fails to close R-2 1.4x10-4 suction from RWST MVC941280P OP fails to open R-2 9.6x10 5 CC9412 valves MVS8804A0P OP fails to close R-2 1.4x10-4 7 SI8804 valves MVS8804B0P OP fails to close R-2 1.4x10 4 SI8804 valves MVLCV1120P OP fails to close R-2 1.4x10-4 1x10 4 2

LCV112 valves MVSI88070P OP fails to close R-2 1.4x10 4 SI8807 valves MVSI88060P OP fails to close R-2 1.4x10-4 SI8806 valve AFWCCF Common cause failure AFWS 1.93x10 4 2.25x10 4 3

for AFW two pumps AF01BFR AFW pump B fails to AFWS 5.45x10-3 6.45x10 3 4

run (for 5 hours5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months ) 0XVSX138AC Valve 138A fails ESWS 1.27x10 6 9.50x10 6 5

closed 0XVSX138BC Valve 138B fails ESWS 5.78x10-5 9.50x10-6 5

closed 1MVSX001AC Valve 001A fails ESWS 1.27x10-6 9.50x10-6 5

closed 1MVSX001BC Valve 001B fails ESWS 5.78x10-6 9.50x10 6 5

closed lyVSX143AC Valve 143A fails ESWS 1.27x10 6 9.50x10-6 5

closed

4-11 Table 4.1 (Continued)

This Event Name Failure Mode System WCAP-10526 Study Comment

CCESWV1 Common cause failure ESWS 1.20x10-5 4.79x10-6 6

of service water trains (for transients) 1XVSX143BC Valve 143B fails ESWS 5.78x10-5 9.50x10-5 5

closed XVSXAHM OP fails to restore CF 8.00x10-4 1.33x10-4 7

block valve A XVSXBHM OP fails to restore CF 8.00x10-4 1.33x10-4 7

block valve B XVSXCHM OP fails to restore CF 8.00x10-4 1.33x10-4 7

block valve C XVSXDHM OP fails to restore CF 8.00x10-4 1.33x10-4 7

block valve D LOSP Induced loss of EPS 1.60x10-4 3.40x10 4 8

offsite power BUS 131ZD No power at bus EPS 7.64x10-8 5.57x10 s 9

131Z BUS 131Z1D No power at bus EPS 7.64x10-8 6.23x10-5 9

131Z1 BUX131XD No power at bus EPS 7.64x10-8 5.49x10-5 9

131X BUS 131X1D No power at bus EPS 7.64x10-8 6.20x10-5 9

131X1 DGAFR DGA fails to run EPS 5.97x10 3 3.58x10-2 10 (for 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months )

DGBFR DGB fails to run EPS 5.97x10-3 3.58x10-2 10 (for 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months )

LOSPNONREC Nonrecovery of loss EPS 0.38 0.26 11 of offsite power

]

DGANONREC Nonrecovery of DGA EPS 0.70 0.75 11 DGBNONREC Nonrecovery of DGB EPS 0.70 0.75 11 1

i

4-12 Table 4.1 (Continued)

This Event Name Failure Mode System WCAP-10526 Study Comment

PR2-QD OP fails to close PR2 1.20x10-2 6.30x10 2 12 PORVs OP1-0D OP fails to diagnose OP1 1.3x10 4 8.8x10-4 12 need of bleed OP2-0D OP fails to diagnose OP2 1.3x10-4 8.8x10 "

12 need of feed and bleed OP3-0A OP fails to control 0P3 4.5x10-4 3.0x10 3 12 feed and bleed OPS-10D OP fails to shut down OPS 7.8x10-4 4.2x10-3 12 for SGTR with SA2, MT l

success OPS-20D OP fails to shut down OPS 7.8x10-3 4.2x10-2 12 for SGTR with MT failure OP9 OP fails to shut down OP9 3.4x10-3 2.1x10 2 12 for core power excursion

1.

Operator errors in establishing recirculation after a large LOCA' are assumed completely dependent (see Section 4.2.1).

2.

Operator errors in establishing recirculation after a small LOCA are assumed completely dependent (see Section 4.2.1).

3.

Numerical errors in WCAP-10526 (p. 3.5-4).

4.

Numerical errors in WCAP-10526 (p. 3.5-4).

5.

Using symmetric testing intervals (see Section 4.2.1).

6.

Failure of both pumps to start is removed for transients other than loss of offsite power, because one pump is normally operating.

7.

Restoration failures are conditional on maintenance events.

8.

The value from the Zion PSS which represents the electric power network stability of the region.

j 9.

Including the Zion PSS data for the bus, circuit breaker, and i

transformer.

10. Multiplied by the mission of 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months .

11. From " Response to the BNL Peer Review of the Zion PSS."

12. From Ref. 27 for the operator (for the control room crew, not for an individual) failures during an accident.

l

4-13 Table 4.2a Comparison of Initiator Frequencies (Events / Reactor Year)

Initiator Group #

Initiator WCAP-10526 This Study 1

Large LOCA 9.40(-4) 9.40(-4) 2 Medium 0 0CA 9.40(-4) 9.40(-4) 3 Small LOCA 3.54(-2) 3.54(-2) 4 SG Tube Rupture 3.70(-2) 3.70(-2) 5 Steam Break Inside Containment 9.40(-4) 9.40(-4) 6 Steam Break Outside Containment 9.40(-4) 9.40(-4) 7 Loss of MFW 3.00 3.00 8

Closure of MSIV 2.52(-1) 6.00(-1)*

9 Loss of RCS Flow 3.58(-1) 3.58(-1) 10 Core Power Excursion 2.28(-2) 2.28(-2) 11 Turbine Trip 4.00 4.00 12A Loss of Offsite Power 5.76(-2) 9.10(-2)**

13 Spurious Safety Injection 8.00(-2) 1.60(-1)*

14 Reactor Trip 3.00 4.11*

15 Interfacing LOCA 2.10(-7) 7.80(-7)***

(16)

ATWS 1.36(-5)

{

17 Loss of Service Water

PWR generic data from Ref. 23.

- Ref. 31.

0**Ref. 32.

For 3-day A0T; See Section 4.2.2 and Table 4.2b.

1. For 7-day A0T; See Section 4.2.2.

)

\\

4-14 Table 4.2b Sensitivity Study Results for Lgss of Service Water Initiator Frequency (3-Day A0T))

Pump Strainer Failure Failure Initiator Success Criterion Rate Rate Frequency Case on Fans #

(/hr)

(/ry)

A Both fans in a tower 1.32(-6)+

6.67(-7)##

1.53(-3)

B Any 2 of 4 fans 9.00(-6)++

6.00(-6)%

1.80(-3)

C*

Any 1 of 4 fans 9.00(-6) 6.00(-7)%%

9,47( 4)

C'**

Any 1 of 4 fans 9.00(-6) 6.00(-7) 1.49(-4)

D No fans 9.00(-6) 6.00(-7) 8.87(-4)

E No fans 9.00(-6) 6.00(-6) 1.64(-3) 4 F

No fans 9.00(-6) 0.##

8.15(-4)

$ Common cause failures between the operating train and the standby train were not considered in this sensitivity study.

Case C is the reference case used throughout this study.

- Same with Case C except for an additional assumption of no maintenance 1

unavailability contribution.

+ Data used in WCAP-10526.

++ Data reported in LER.

1 I

% Data used in the Seabrook PSS.

%% Data in the Seabrook PSS is reduced by a factor of ten, giving considera-tions for the separate basin, 8-hour backwash cleaning, and automatic dif-ferential pressure indication and alarm.

Assumed that fans are not needed in three winter months.

1. For further sensitivity studies.

4-15 Table 4.3 Mean System Unavailabilities l

LOSP NON-LOSP A0T1*

A0T2**

Slope /Hr A0T1 A0T2 Slope /Hr ESWS 1.17(-3) 5.51(-3) 2.91(-5) 1.35(-5) 6.90(-5) 3.72(-7)

AFWS 1.05(-3) 3.37(-3) 1.56(-5) 5.41(-4) 1.57(-3) 6.91(-6)

CS 1.71(-3) 5.28(-3) 2.40(-5) 5.58(-4) 7.27(-4) 1.13(-6)

CF 1.44(-3) 7.54(-3) 4.09(-5) 1.72(-5) 3.11(-4) 1.97(-6)

CCW(A) 1.29(-3) 5.72(-3) 2.97(-5) 3.85(-5) 9.55(-5) 3.83(-7)

CCW(B) 1.27(-3) 5.72(-3) 2.99(-5) 1.81(-5) 7.52(-5) 3.83(-7)

SIM(HH1) 1.85(-5) 9.57(-5) 5.18(-7)

SIS (HH2) 1.17(-3) 5.52(-3) 2.92(-5) 1.35(-5) 6.90(-5) 3.72(-7) 2 LPI 2.43(-4) 2.78(-4) 2.35(-7)

R-1 1.66(-3) 1.80(-3) 9.40(-7)

R-2 8.83(-4) 1.88(-3) 6.69(-6) 5.02(-4) 6.43(-4) 9.46(-7)

A0T1: Tr = 19 hours2.199074e-4 days 0.00528 hours 3.141534e-5 weeks 7.2295e-6 months .

o*A0T2: Tr = 168 hours0.00194 days 0.0467 hours 2.777778e-4 weeks 6.3924e-5 months .

Table 4.4 Definition of Cases Case A0T1 A0T2 1

All systems None 2

None All systems 3

All others DGs 4

All others ESWS 5

All others CHRS (CF and CS) 6 All others Chg and SI 7

All others RHR 8

All others AFWS 9

All others CCWS l

_.. -. _ _ _ _ _ _ _ _ _. ~

Table 4.5 Plant Damage State and Core Dasage Frecuencies for Modde 0 CASE 10 MODEl. O CASE 1 ET!

ET2 ET3 ET4 ET5 ET6 ET7 ETB ET9 ETl!

ET124 ET13 ET14 ET15 ET!6 ET17 TOTAL

' AEFC 6.36E-07 2.30E-07 AEF 8.66E-07 EC 1.14E-08 AE 1.03E-10 1.03E-10 1.14E-08 ALFC 1.54E-06 1.54E-06 2.CfE-10 ALF 5.5EE-10 5.58E-10 3.08E-06 ALC 1.14E-08 1.12E-09 R.

1.14E48 SEFC 1.88E-08 4.8EE-08 9.53E-07 1.02E-06 SEF 3.32E49 3.32E-09 SEC 8.08E-05 3.86E-06 8.47E-05 SE 1.6SE-06 4.99E-05 5.16E-05 SLFC 1.84E-05 1.19E-091.19E-09 7.71E-071.54E-07 9.2!E-081.03E46 5.83E-07 2.74E-071.06E-06 4.55E-!C 2.24E-05 SLF 7.20E-09 2.94E-11 1.62E49 8.65E-09 i

SLC 3.30E-12 3.04E-09 3.25E-10 3.37E-09 g

SL 4.41E-11 4.41E-11 TEFC 1.61E-091.61E49 2.97E-06 5.94E-07 3.54E47 3.%E46 6.13E-08 2.59E-07 4.07E-06 2.81E-09 1.23E-05 TEF

!.73E-10 3.46E-!! 2.07E-11 9.60E-10 2.37E-10 1.43E-09 TEC 1.63E-101.63E-101.01E-06 2.02E-071.20E-071.35E-06 2.57E-07 5.36E-081.33E46 0.00E+00 4.3SE-06 TE 2.34E-08 4.68E-09 2.79E-09 3.14E-06 3.62E-061.05E-09 3.21E-08 0.00E+00 3.72E-06 V2E 5.29E-07 5.29E-07 V2L 9.40E49 9.40E-09 2.37E-06 9.40E-09 9.40E-09 V

2.41E-06 7.80E-07 7.80E-07 TOTR. 2.20E-061.79E-061.01E-04 2.90E-061.24E-061.24E-08 4.78E-06 9.55E-07 5.69E-07 6.3EE46 5.83E-05 5.88E-07 6.54E-06 7.80E4 cModel 0 - Model in WCAP-10526 with modifications in Section 4.2 (except Event Tree 17) and data i 4.1 and 4.2.

n Tables Case 1 - All systems under A0T1.

Tabla 4.6 Plant Damage Stat 2 and Core Dar. age Frequencies for Model 0 CASE 2

POCEL 0 CASE 2 ETI ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ET11 ET12R ET13 ET14 ET15 ET16 ET17 TOTAL 9.50E-07 AEFC 6.6EE-07 2.82E-07 AEF 6.13E48 AEC 6.13E-08 1.63E-09 AE 9.15E-10 9.15E-10 3.24E-06 ALFC 1.62E-061.62E-06 1.12E-09 ALF 5.5SE-10 5.5EE-10 6.13E-08 ALC 6.13E-08 AL SEFC 5.40E-08 5.33E-08 9.53E-07 1.CfE-06 9.18E-03 9.18E-09 SEF 2.4BE-05 4.41E-04 SEC 4.16E-04 SE 7.01E-06 2.2EE-04 2.35E-04 SLFC 2.35E-05 1.33E-091.33E-09 2.90E-06 5.75E-07 3.46E-07 3.86E46 2.71E-06 4.45E-07 3.97E-06 4.55E-10 3.83E-05 SLF 1.03E-08 2.20E-10 2.!EE-08 3.22E-08 A

SLC 2.2SE-09 8.04E-08 9.30E-10 8.36E-08 k

1.81E-09 1.81E-09 SL 4.44E-09 4.44E-09 8.5EE-061.72E-061.02E461.14E-05 2.08E-07 7.50E-071.1BE-05 2.81E-09 3.55E-05 TEFC 1.53E-09 3.06E-10 1.63E-10 4.16E-09 2.10E-09 8.2EE-09 TEF 6.17E-10 6.17E-10 8.01E-061.60E46 9.57E-071.0EE-05 2.56E-06 4.24E-071.10E-05 0.00E+00 3.53E-05 TEC 1.4CE-07 2.81E-08 1.6EE-08 1.66E 47 2.22E-05 7.03E-09 1.92E-07 0.00E+00 2.2EE-05 TE 2.64E-06 V2E 2.64E-06 6.52E-06 V2L 9.40E-09 9.40E-09 6.45E-06 9.40E-09 9.40E-09 7.50E-07 7.60E-07 y

TOTAL 2.36E-061.97E-06 4.47E-04 9.12E-061.58E-081.5aE-081.96E-05 3.93E-06 2.34E46 2.63E-05 2.81E-041.63E-06 2.69E-05 7.60E-Model 0 - Model in WCAP-10526 with modifications in Section 4.2 (except Event Tree 17) and data in Tables 4.1 and 4.2.

Case 2 - All systems under A0T2.

Table 4.7 Plant Damage State and Core Damage Frecuencies for Model 0 Case 3*

MODEL 0 CASE 3 ET!

ET2 ET3 ET4

'ET5 ET6 ET7 ET8 ET9 ET!!

ET!2A ET13 ET14 ET15 ET16 ET17 TOTAL AEFC 6.3EE-07 2.30E-07 lEF 8.66E-07 EC 1.14E48 1.14E-08 AE 9.15E-10 9.15E-10 ALFC 1.54E-06 1.54E-06 1.83E-03 3.08E-06 ALF 5.58E-10 5.58E-10 1.12E-09 ILC 1.14E-08 AL 1.14E-08 SEFC 2.05E-08 5.3BE-08 9.53E-07 1.03E46 SEF 3.32E-09 3.32E-D9 SEC 8.08E-05 6.56E-06 8.74E-05 SE 7.00E-06 1.75E-04 1.82E-04 SLFC 1.84E-05 1.19E-09 1.19E-09 7.77E-07 1.55E-07 9.27E-08 1.04E-06 1.78E-06 2.74E-07 1.06E-06 4.55E-10 2.3EE 05 A-SLF 7.20E-09 2.94E-11 1.14E-08

!.EEE-08 b

SLC 3.30E-12 9.46E-09 3.25E-10 9.79E-09 3

SL 2.04E-10 2.04E-10 TEFC 1.61E-09 1.61E-09 2.97E-06 5.94E-07 3.55E-07 3.96E-06 1.46E-07 2.59E-07 4.07E-06 2.81E-09 1.24E-05 TEF

!.73E-10 3.46E-11 2.07E-Il 9.60E-10 2.37E-10 1.43E-09 TEC 1.63E-10 1.63E-10 1.0!E-06 2.02E-07 1.20E-07 1.35E-06 4.38E-07 5.36E-08 1.39E-06 0.00E+00 4.f6E-06 TE 1.05E47 2.!CE-081.25E-061.40E-071.24E-05 5.182-091.44E-07 0.00E+00 1.25E-05 V2E 5.62E-07 5.62E-07 V2L 9.40E-09 9.40E-09 2.37E-06 9.40E-09 9.40E-09 2.41E-C6 V

7.80E-07 7.80E-07 TOTAL 2.20E461.79E-061.06E44 2.93E-061.24E-081.24E-08 4.87E-06 9.72E-07 5.8CE-07 6.4BE-061.%E-04 5.92E-07 6.67E-06 7.8DE-07 9.E0E-07 0.0C

Model 0 - Model in WCAP-10526 with modifications in Section 4.2 (except Event Tree 17) and data in Tables 4.1 and 4.2.

Case 3 - DGs under A0T2 and all others under A0T1.

Tab 12 428 Plant Damage Stata and Core Damage Frequereies for Model 0 Case 4*

MCDEL 0 CASE 4 ET!

ET2 ET3 ET4 ETS ET6 ET7 ET8 ET9 ET11 ET1,..

ET13 ET14 ET15 ET16 ET17 TOTAL AEFC 6.36E-07 2.30E-07 8.66E-07 AEF EC 6.13E-08 6.13E-08 AE 1.03E-10 1.03E-10 2.06E-10 ALFC 1.54E-M 1.54E-06 3.08E-06 ALF 5.58E-10 5.58E-10 1.12E-03 ALC 6.13E-08 6.13E-08 R.

SEFC 2.03E-08 4.8BE-08 9.53E-07 1,02E-06 SEF 3.32E-09 3.32E-09 SEC 4.16E-04 2.21E-05 4.39E-04 SE 1.68E-06 1.03E-04 1.05E-04 SLFC 1.84E-05 1.19E-09 1.19E-09 7.71E-07 1.54E-07 9.21E-08 1.03E-06 5.83E-07 2.74E-07 1.06E-06 4.55E-10 2.24E-05 SLF 7.20E-09 2.94E-11 1.62E-09 8 E E-03 i

SLC 3.30E-12 3.04E-09 9.30E-10 3.97E-09 G

SL 4.41E-11 4.41E-11 TEFC 1.61E-091.6!E-09 2.97E-06 5.94E-07 3.54E-07 3.%E-06 6.13E-08 2.59E-07 4.07E-06 2.81E-09 1.23E-05 TEF 1.73E-10 3.46E-11 2.07E-11 9.60E-10 2.37E-10 1.43E-09 TEC 5.33E-10 5.33E-10 4.95E-06 9.91E-07 5.91E-07 6.64E-06 1.51E-06 2.62E-07 6.78E-06 0.00E+00 2.17E-05 TE 2.34E48 4.68E-09 2.79E-09 3.14F-08 7.25E-061.05E-09 3.21E-08 0.00E+00 7.35E-06 V2E 2.61E-06 2.61E-06 V2L 9.40E-09 9.40E-09 2.37E-06 9.40E-09 9.40E-09 2.41E-06 V

7.80E-07 7.80E-07 TOTAL 2.25E-061.84E-% 4.37E-04 4.98E-061.27E-021.27E-08 8.71E-061.74E-061.04E-061.17E-051.35E-04 7.97E-071.19E-05 7.80E-07 9.60E-07 0.00E+00 6.16E-04

Model 0 - Model in WCAP-10526 with modifications in Section 4.2 (except Event Tree 17) and data in Tables 4.1 and 4.2.

Case 4 - ESWS under A0T2 and all others under A0T1.

O Table 4.9 Plant Dasage State and Core Damage Frecuercies for Model 0 Case 5 MODEL C CASE 5 ETI ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ET!!

ET12A ET13 ET14 ET15 ET16 ET17 TOTAL AEFC 6.3EE-07 2.30E-07 8.EEE-07 AEF AEC 1.14E-08 1.14E-08 AE 1.03E-10 1.03E-10 2.0EE-10 ALFC 1.54E-M 1.54E-M 3.08E-06 ALF 5.58E-10 5.5SE-10 1.12E-09 ALC 1.14E-08 1.14E-08 AL SEFC 1.88E-08 4.88E-08 9.53E-07 1.02E46 SEF 3.33E-09 3.32E-09 SEC 8.08E-05 3.86E s5 8.47E-05 SE 1.79E-06 4.99E-05 5.17E-05 SLFC 1.84E-05 1.19E-09 1.19E-09 7.71E-07 1.54E-07 9.21E-08 1.03E-06 5.83E-07 2.74E-07 1.06E-06 4.55E-10 2.24E-05 3

SLF 9.!ZE-09 2.94E-11 2.72E-09 1.19E-08 L

SLC 2.28E-09 2.08E-08 3.25E-10 2.34E-08 C

SL 4.41E-11 4.41E-11 TEFC 1.61E-09 1.61E-09 2.97E-06 5.94E-07 3.54E-07 3.96E-06 6.13E-08 2.59E-07 4.07E-06 2.81E-09 1.23E-05 TEF 1.73E-10 3.4EE-11 2.07E-11 1.02E-09 2.37E-10 1.49E-09 TEC 1.63E-10 1.63E-10 1.0!E-06 2.02E-07 1.20E-07 1.35E-06 2.58E-07 5.36E-08 1.39E-06 0.00E+004.38E-06 TE 2.34E-08 4.EBE-09 2.79E-03 3.14E-09 3.62E-061.05E-09 3.21E-08 0.00E+00 3.72E-06 V2E 5.29E-07 5.29E-07 V2L-9.40E-09 9.4CE-09 2.37E-06 9.40E-09 9.40E-09 2.41E-06

~

V 7.80E-07 7.80E-07 TOTAL 2.20E-061.79E-061.01E-04 2.90E-061.24E-081.24E-08 4.78E-06 9.55E-07 5.69E-07 6.36E-06 5.84E-05 5.88E-07 6.54E-06 7.80E-07 9.60E-07 0.00E+001. BEE-04

Model 0 - Model in WCAP-10526 with modifications in Section 4.2 (except Event Tree 17) and data in Tables 4.1 and 4.2.

Case 5 - CF and CS under A0T2 and all others under A0T1.

i

.. ~ - -

1 s

O Table 4.10 Plant Damage State and Core Dar. age Frequencies for Modde O CASE 6 MODEL 0 CASE 6 ETI ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ETil ET12A ET13 ET14 ET15 ET16 ET17 TOTAL AEFC 6.3EE-07 2.50E-07 8.85E-P AEF AEC 1.14E-08 1.14E-03 AE 1.03E-10 1.03E-10 2.0EE-10 ALFC 1.54E-(61.54E-06 3.08E-06 ALF 5.58E-10 5.55E-10 1.12E-09 ALC 1.14E-03 1.14E-08 AL SEFC 1.88E-08 4.88E-08 9.53E-07 1.302E-06 SEF 3.32E-09 3.32E-09 SEC 8.03E-05 3.8EE-06 8.47E-05 SE 1.6SE-06 4.99E-05 5.15E-05 SLFC 1.84E-05 1.19E-091.19E49 7.71E-071.54E-07 9.21E-081.03E-06 5.84E-07 2.74E-071.06E-06 4.55E-10 2.24E-05 4

SLF 7.20E-03 2.94E-11 1.62E-09 8.85E-09 SLC 3.30E-12 3.04E-09 3.25E-10 3.37E-09 SL 4.41E-11 4.41E-!!

TEFC 1.61E-09 1.61E-09 2.97E-06 5.94E-07 3.54E-07 3.9EE-06 6.25E-08 2.59E-07 4.07E-06 2.81E-09 1.23E-05 TEF 1.73E-10 3.4EE-Il 2.07E-11 9.6CE-10 2.37E-10 1.43E-09 TEC 1.63E-101.63E-101.0!E-06 2.02E-071.20E-071.35E46 2.57E-07 5.36E-081.39E-06 0.00E+00 4.38E-06 TE 2.34E-08 4.68E-09 2.79E-09 3.14E-08 3.62E-06 1.05E-09 3.21E-08 0.00E+00 3.72E-06 V2E 5.29E-07 5.29E-07 V2L 9.40E-09 9.40E-09 2.37E-06 9.40E-09 9.40E-09 2.41E-06 V

7.80E-07 7.8Cf-07 TOTAL 2.20E-061.81E-061.01E-04 2.90E-061.24E-081.24E-08 4.78E-06 9.55E-07 5.69E-07 6.36E-06 5.83E-05 5.86E-07 6.54E-06 7.80E47 9.60E-07 0.00E+001.85E-04 TModel 0 - Model in WCAP-10526 with modifications in Section 4.2 (except Event Tree 17) and data in Tables 4.1 and 4.2.

Case 6 - Chg and SI under A0T2 and all others under A0T1.

Table 4.11 Plant Damage State and Core Damage Frecuencies for Model 0 Case 7*

P.0 EEL 0 CASE 7 ETt ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ET!!

ET12A ET13 ET14 ET15 ET16 ET17 TOTAL TEFC 6.66E-07 2.63E-07 9.31E-07 AEF AEC 1.14E-08 1.14E48 AE 1.03E-10 1.03E-10 2.0EE-10 ALFC 1.62E-06 1.62E-06 3.24E-06 ALF 5.5EE-10 5.58E-10 1.12E-09 l

ALC 1.14E-08 1.14E-08 AL SEFC 1.88E-08 4.88E-08 9.53E-07 1.02E-06 SEF 3.32E-09 3.32E-09 SEC 8.08E-05 3.8EE-06 8.47E-05 SE 1.68E-06 4.99E-05 5.16E-05 SLFC 2.35E-05 1.19E-091.19E49 9.84E-071.97E-071.17E-071.31E-06 9.25E-07 3.49E-071.35E-06 4.55E-10 2.87E-05 3

SLF 8.39E-09 2.94E-11 3.80E-09 1.22E-08 L

SLC 3.30E-12 5.87E-09 3.25E-10 6.20E-09 N

SL 3.92E-10 3.92E-10 TEFC 1.61E-091.61E-09 2.97E-06 5.94E-07 3.54E-07 3.%E-06 6.13E-08 2.59E-07 4.07E-06 2.81E-09 1.23E-05 TEF 1.73E-10 3.4EE-!! 2.07E-11 9.60E-10 2.37E-10 1.43E-09 TEC 1.63E-101.63E-101.01E-06 2.02E-071.20E-071.35E46 2.57E-07 5.36E-081.39E-06 0.00E+00 4.38E-06 TE 2.34E-08 4.6BE-09 2.79E-09 3.14E-08 3.62E-% 1.05E-09 3.21E-08 0.00E+00 3.72E-%

V2E 5.29E-07 5.29E-07 V2L 9.40E-09 9.40E-09 2.44E-06 9.40E-09 9.40E-09 2.45E-06 7.80E-07 7.80E-07 V

TOTAL 2.31E-061.90E-061.0EE-04 2.97E-061.24E-081.24E-08 4.99E-06 9.98E-07 5.94E-07 6.65E-06 5.87E-05 6.63E-07 6.83E-06 7.80E-07 9.60E47 0.00E+001.9

Model 0 - Model in WCAP-10526 with modifications in Section 4.2 (except Event Tree 17) and data in Tables 4.1 and 4.2.

Case 7.- RHR under A0T2 and all others under A0T1.

Table 4.12 plant Damage Stat 2 and Core Damage Frequencies for Model 0 Case 8*

PIDEL 0 EASE 8 ETI ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ETil ET12A ET13 ET14 ET15 ET16 ET17 TOTAL CGC 6.36E-07 2.30E-07 8.66E-07 CE EC 1.14E-08 1.14E-08 E

1.03E-10 1.03E-10 2.06E-10 TLFC 1.54E-M 1.54E-M 3.08E-06 R.F 5.5SE-10 5.5SE-10 1.12E-09 ALC 1.14E-03 1.14E-08 AL SEFC 5.08E-08 4.88E-08 9.53E-07 1.05E-06 SEF 9.18E-09 9.18E-09 SEC 8.0BE-05 3.86E-06 8.47E-05 SE 1.6EE-06 4.99E-05 5.1EE-05 SLFC I.84E-05 1.33E-09 1.33E-09 2.26E-06 4.52E-07 2.70E-07 3.01E-06 8.55E-07 3.49E-07 3.09E-06 4.55E-10 2.87E-05 SLF 7.20E-09 2.60E-10 1.85E-09 9.31E-09 p

SLC 3.30E-12 4.48E-09 3.25E-10 4.81E-09 y

SL 4.41E-11 4.41E-11 TEFC 4.44E-09 4.44E-09 8.58E-06 1.72E-06 1.02E-06 1.14E-05 1.20E-07 7.50E-07 1.18E-05 2.81E-09 3.54E-05 TEF 1.53E-09 3.0EE-10 1.83E-10 3.57E-09 2.10E-09 7.6SE49 TEC 2.47E-10 2.47E-101.60E-06 3.19E-071.91E-07 2.14E46 3.92E-07 8.46E-08 2.19E-06 0.00E+00 6.91E-06 TE 3.48E-08 6.93E-09 4.14E-09 4.64E48 5.35E-061.61E-09 4.77E-08 0.00E+00 5.49E46 VEE 5.29E-07 5.29E-07 V2L 9.40E-09 9.40E-09 6.41E46 9.40E-09 9.40E-09 6.45E-06 V

7.80E-07 7.80E-07 TOTAL 2.20E-061.79E-061.01E-04 6.94E-061.54E-081.54E-081.25E-05 2.50E-061.49E-061.66E-05 6.05E-051.19E461.71E-05 7.80E-07 9.65E-07 0.00E+00 2.26E-04

Model 0 - Model in WCAP-10526 with modifications in Section 4.2 (except Event Tree 17) and data in Tables 4.1 and 4.2.

Case 8 - AFWS under A0T2 and all others under A0T1.

. ~ _..... _ - - - --..

Tabl2 4.13 Plant Damage State and Core Damage Frequencies for Model 0 Case 9

MODEL 0 CASE 9 ET1 ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ET!!

ET12A ET!3 ET!4 ET!5 ET16 ET17 TOTAL AEFC 6.36E-07 2.30E-07 8.6EE-07 AEF AEC 1.14E48 1.14E-08 AE 1.03E-10 1.03E-10 2.CfE-10 RFC 1.54E-M 1.54E-06 3.08E-%

RF 5.58E-10 5.58E-10 1.12E-09 1

RC 1.14E48 1.14E-08 l

R.

i SEFC 1.88E-08 4.88E-08 9.53E-07 1.02E-06 SEF 3.32E-09 3.32E-09 l

SEC 8.08E-05 3.86E-06 8.47E-05 SE 1.68E-06 4.99E-05 5.!EE-05 SLFC 1.84E-05 1.15E-09 1.19E-09 7.74E-07 1.55E-07 9.22E-08 1.03E-06 6.39E-07 2.74E-07 1.06E-06 4.55E-10 2.24E-05 SLF 7.20E-09 2.94E-11 1.65E-09 8.85E-09 4

SLC 3.30E-12 3.39E-09 3.25E-10 3.72E-09 SL 4.41E-11 4.41E-11 TEFC 1.61E-091.61E-09 2.97E-06 5.94E-07 3.54E-07 3.%E-06 6.13E-08 2.59E-07 4.07E-06 2.8tE-09 1.23E-05 I

TEF 1.73E-10 3.4EE-!! 2.07E-11 9.60E-10 2.37E-10 1.43E-03 TEC 1.63E-10 1.63E-10 1.01E-E 2.02E-07 1.20E-07 1.35E-06 2.57E-07 5.36E-08 1.39E-06 0.00E+00 4.38E-06 1

TE 2.34E-08 4.68E49 2.79E-09 3.14E-08 3.62E-061.05E-09 3.21E-08 0.00E+00 3.72E-06 i

V2E 5.29E-07 5.29E-C7 v2L 9.40E-09 9.40E-09 2.37E-06 9.40E-09 9.40E-09 2.41E-06 V

7.80E-07 7.8(E-07 TOTAL 2.20E-061.79E-M 1.01E-04 2.90E-M 1.24E-081.24E-08 4.78E-06 9.56E-07 5.69E47 6.37E-06 5.84E-05 5.88E-07 6.55E-06 7.8CE-07 9.60E-07 0.00E+001.85E-04

Model 0 - Model in WCAP-10526 with modifications in Section 4.2 (except Event Tree 17) and data in Tables 4.1 and 4.2.

Case 9 - CCWS under A0T2 and all others under A0T1.

i i

Table 4.14 Plant Damage State and Core Damage Frequencies for Mode! ! Case 1*

MODEL 1 EASE 1 ETI ET2 ET3 ET4 ETS ET6 ET7 ET8 ET9 ET!!

ET12A ET13 ET14 ET15 ET16 ET17 TOTAL AEFC 6.36E-07 2.30E-07 8.66E-07 REF AEC 1.14E-08 1.14E-08 AE 1.03E-10 1.03E-10 2.06E-10 ALFC 1.54E 4 1.54E-06 3.08E-06 ALF 5.58E-10 5.56E-10 1.12E-09 R.C 1.14E-08 1.14E-08 R.

SEFC 1.88E-08 4.88E-08 9.53E-07 1.02E-06 SEF 3.32E-09 3.32E-09 SEC 5.54E-04 3.86E-06 5.58E-04 SE 1.78E46 4.99E-05 5.17E-05 p

SLFC 1.84E-05 1.19E-09 1.19E-09 7.71E-07 1.54E-07 9.21E-08 1.03E-06 5.83E-07 2.74E-07 1.06E-06 4.55E-10 2.24E-05 N*

SLF 7.20E-09 2.94E-!! 1.62E49 8.85E-09 SLC 3.30E-12 3.04E-09 3.25E-10 3.37E-09 SL 4.41E-11 4.41E-11 TEFC 1.61E-091.61E-09 2.97E-06 5.94E-07 3.54E-07 3.96E-06 6.13E-08 2.59E-07 4.07E-06 2.81E-09 1.23E-05 TEF 1.73E-10 3.46E-11 2.07E-11 9.60E-10 2.37E-10 1.43E-09 TEC 1.63E-101.63E-101.01E-06 2.02E-071.20E-071.35E-06 2.57E-07 5.36E-081.39E-06 3.37E-05 3.81E-05 TE 2.34E48 4.68E49 2.79E-09 3.14E-08 3.62E461.05E-09 3.21E-08 2.00E-08 3.74E-06 V2E 5.29E-07 5.29E-07 V2L 9.40E-09 9.40E-09 2.37E-06 9.40E-09 9.40E-09 2.41E-06 V

7.80E-07 7.80E-07 TOG 8. 2.20E-061.79E-06 5.75E-04 2.90E-061.24E-081.24E-08 4.78E-06 9.55E47 5.69E-07 6.36E46 5.8K-05 5.88E47 6.54E46 7.80E-07 9.60E47 3.37E-05 6.95E44 TModel 1 - Model 0 plus Event Tree 17 (loss of service water).

Case ! - All systems under A0T1.

1 Table 4.15 Plant Damage State and Core Damage Frequencies for leode! ! Case 2

IGEL 1 EASE 2 ET!

ET2 ET3 ET4 ETS ET6 ET7 ET8 ET9 ET!!

ET12A ET13 ET14 ET15 ET16 ET17 TOTAL AEFC 6.68E-07 2.82E-07 9.50E-07 AEF AEC 6.13E-08 6.13E-08 AE 9.15E-10 9.15E-10 1.83E-09 ALFC 1.62E 4 1.62E-06 3.24E-06 RF 5.58E-10 5.58E-10 1.12E-09 RC 6.13E-08 6.13E-08 R.

SEFC 5.40E-08 5.38E-08 9.53E-07 1.06E-06 SEF 9.1E-09 9.1E-09 SEC 4.02E-03 2.48E-05 4.05E-03 SE 7.82E-06 2.2E-04 2.36E-04 i

SLFC 2.35E-05 1.33E-09 1.33E-09 2.90E-06 5.79E-07 3.46E-07 3.86E-06 2.71E-06 4.45E-07 3.97E-06 4.55E-10 3.83E-05 SLF 1.03E-08 2.20E-10 2.16E-08 3.21E-08 SLC 2.28E-09 8.04E-08 9.30E-10 8.36E-08 SL 1.81E-09 1.81E-09 TEFE 4.44E-09 4.44E-09 8.58E-06 1.72E-06 1.02E-06 1.14E-05 2.08E-07 7.50E-07 1.! E-05 2.81E-09 3.55E-05 TEF 1.53E-09 3.06E-101.83E-10 4.15E-09 2.10E-09 8.2BE-09 TEC 6.17E-10 6.17E-10 8.01E-06 1.60E-06 9.57E-07 1.08E-05 2.56E-05 4.24E-07 1.10E-05 3.92E-04 4.28E-04 TE 1.40E-07 2.81E-08 1.68E-08 1.88E-07 2.22E-05 7.03E-09 1.92E-07 2.94E-07 2.31E-05 V2E 2.64E-06 2.64E-06 V2L 9.40E-09 9.40E-09 6.48E-06 9.40E-09 9.40E-09 6.52E 4 V

7.80E-07 7.80E-07 TOTE. 2.36E-061.97E-06 4.05E-03 9.12E-061.58E-081.58E-081.96E-05 3.9E-06 2.34E-06 2.6K-05 2.81E-041.63E-06 2.69E-05 7.80E-07 9.65E-07 3.93E-04 4.82E-03

Model 1 - Model 0 plus Event Tree 17 (loss of service water).

Case 2 - All systems under A0T2.

Table 4.16 Plant Damage State and Core Damap Frequencies for Itodel 1 Case 3*

IGEL 1 CASE 3 ET!

ET2 ET3 ET4 ETS ET6 ET7 ET8 ET9 ET!!

ET12A ET13 ET14 ET15 ET16 ET17 TOTE EFC 6.36E-07 2.30E-07 8.66E-07 AEF AEC 1.14E-08 1.14E-08 AE 9.15E-10 9.15E-10 1.83E-09 EFC 1.54E-M 1.54E-06 3.08E-06 RF 5.58E-10 5.58E-10 1.12E-09 EC 1.14E-08 1.14E-08 65.

EFC 2.05E-08 5.38E-08 9.53E-07 1.03E-06 SEF 3.32E-09 3.32E-09 SEC 5.54E-04 6.56E-06 5.61E-04 SE 7.10E-06 1.75E-04 1.82E-04 k

SLFC 1.84E-05 1.19E-09 1.19E-09 7.77E-07 1.55E-07 9.27E-08 1.04E-06 1.78E-06 2.74E-07 1.06E-05 4.55E-10 2.36E-05 N

SLF 7.20E-09 2.94E-11 1.14E-08 1.86E-06 SLC 3.30E-12 9.46E-09 3.25E-10 9.79E-09 SL 2.04E-10 2.04E-10 TEFC 1.61E-09 1.61E-09 2.97E-06 5.94E-07 3.55E-07 3.96E-06 1.46E-07 2.59E-07 4.07E-06 2.81E-09 1.24E-05 TEF 1.73E-10 3.46E-11 2.07E-11 9.60E-10 2.37E-10 1.43E-09 TEC 1.63E-10 1.63E-10 1.01E-06 2.02E-07 1.20E-07 1.35E-06 4.38E-07 5.36E-08 1.39E-06 3.3?E-05 3.83E-05 TE 1.05E-07 2.10E-08 1.25E-08 1.40E-07 1.24E-05 5.18E-09 1.44E-07 2.00E-08 1.28E-05 V2E 5.62E-07 5.62E-07 V2L 9.40E-09 9.40E-09 2.37E-06 9.40E-09 9.40E-09 2.41E46 V

7.80E-07 7.80E-07 TOTit. 2.20E-061.79E-06 5.80E44 2.9I-061.24E-081.24E-08 4.87E-06 9.72E-07 5.80E-07 6.48E-061.96E-04 5.92E-07 6.67E-06 7.80E-07 9.60E-07 3.37E-05 8.39E-04 W odel 1 - Model 0 plus Event Tree 17 (loss of service water).

Case 3 - DGs under A0T2 and all others under A0T1.

Table 4.17 Plant Damage State and Core Damage Frequencies for Mode! ! Case 4*

IGEL 1 CASE 4 ET!

ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ET!!

ET12A ET13 ET14 ET15 ET16 ET17 TOTAL EFC 6.36E-07 2.30E-07 8.66E-07 AEF AEC 6.13E-08 6.13E-08 AE 1.0 E-10 1.03E-10 2.06E-10 E FC 1.54E-06 1.54E-06 3.08E-06 ALF 5.58E-10 5.58E-10 1.12E-09 RC 6.13E-06 6.13E-08 R.

SEFC 2.03E-08 4.88E-08 9.53E-07 1.02E-06 SEF 3.32E-09 3.32E-09 SEC 4.02E-03 2.21E-05 4.04E-03 SE 2.48E-06 1.03E-04 1.05E-04 a

SLFC 1.84E-05 1.19E-091.19E-09 7.71E-071.54E-07 9.21E-081.03E-06 5.83E-07 2.74E-071.06E-06 4.55E-10 2.24E-05 b

SLF 7.20E-09 2.94E-11 1.62E-09 8.85E-09 SLC 3.30E-12 3.04E-09 9.30E-10 3.97E-03 SL 4.41E-11 4.41E-11 TEFC 1.61E-091.61E-09 2.97E-06 5.94E-07 3.54E-07 3.96E-06 6.13E-08 2.59E-07 4.07E-06 2.81E-09 1.23E-05 TEF 1.73E-10 3.46E-!! 2.07E-11 9.60E-10 2.37E-10 1.43E-09 TEC 5.33E-10 5.3 I-10 4.95E-06 9.91E-07 5.91E-07 6.64E-06 1.51E-06 2.62E-07 6.78E-06 2.57E-04 2.78E-04 l

TE 2.34E-08 4.68E49 2.79E-09 3.14E-08 7.25E-061.05E-09 3.21E-08 1.52E-07 7.50E-06 V2E 2.6!E-06 2.61E-06 V2L 9.40E-09 9.40E-09 2.37E-06 9.40E-09 9.40E-09 2.41E-06 V

7.80E-07 7.80E-07 TOTE. 2.25E-061.84E-06 4.04E-03 4.98E461.27E-081.27E-08 8.71E-061.74E-061.04E-061.17E-051.35E-04 7.97E-071.19E-05 7.80E-07 9.60E-07 2.57E-04 4.48E-03

Model 1 - Model 0 plus Event Tree 17 (loss of service water).

Case 4 - ESWS under A0T2 and all others under A0T1.

i i

i 1

I 1

Table 4.18 plant Damage State and Corv 8ammy Frequencies for Model 1 Case 5*

18 M I. 1 EREE 5 f

ET1 ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ETil ET128 ET13 ET14 ET15 ET16 ET17 TOTE 4

IEFC L36E47 2.30E-07 8.66E-07 3

{

8EF EC 1.14E-08 1.14E-06

[

E

1. E -10 1.0 E-10 2.06E-10

[

SLFC 1.54E-06 1.54E-06 3.08E-M RF 15E-10 5.5E-10 1.12E-09 EC 1.14E-08 1.14E-06 E

I j

!EFC 1.8BE-08 4.88E-08 9.53E-07 1.02E-06 i

SEF 3.32E-09 3.32E-09 l

SEC 5.54E-04 3.86E 4 5.58E-04 SE 1.79E-06 4.9!E-05 5.!E-05 L EFC 1.84E-05 1.19E-091.1E49 7.71E471.54E-07 9.21E-081.03E-06 5.8E-07 2.74E-071.06E-06 4.55E-10 2.24E-05

E.F 9.12E-09 2.94E-11 2.72E-09 1.1E-08 1

1C 2.28E-09 2.00E-08 3.2E-10 2.34E-08 SL 4.41E-11 4.41E-11 i

TEFC 1.61E-091.61E-09 2.9E4 5.94E-07 3.54E-07 3.96E-06 L1E-08 2.5E-07 4.07E-06 2.81E-09 1.2E-05 I

l TEF 1.7 E-10 3.46E-11 2.0 E-11 1.02E-09 2.37E-10 1.49E-09 TEC 1.6E-101.E-101.01E-06 2.0EE-071.2GE-071.35E-06 2.5IE-07 5.3EE-081.39E-06 3.3 E-05 3.81E-05 f

TE 2.34E-08 4.6E49 2.79E49 3.14E-08 3.62E-061.05E49 3.21E-08 2.48E-06 3.74E-06

[

V2E 5.29E-0F 5.29E47 l

V2L 9.40E-05 9.40E-05

. 2.37E-06 9.40E-09 9.40E-05 2.41E-06 l

V 7.80E-07 7.80E-07 IDTE 2.20E-061.7E-06175E-04 2.90E-061.24E-081.24E-08 4.7EE-06 9.55E47 5.69E47 6.3sE-06 5.84E-05 5.88E47 L54E-06 7.00E47 9.60E47 3.3E-05 L95E-04

Model 1 - Model O plus Event Tree 17 (loss of service water).

Case 5 - CF and CS under A0T2 and all others under A0T1.

I J

4 4

e-- - - - ~ -

Table 4.19 Plant Damage State and Core Damage Frequercies for Model 1 Case 6*

IGEL 1 CASE 6 ETI ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ET11 ET124 ET13 ET14 ET15 ET16 ET17 TOTAL E FC 6.36E-07 2.50E-07 8.86E-07 AEF AEC 1.14E-08 1.14E-08 AE 1.0I-10 1.0 I-10 2.06E-10 ALFC 1.54E-06 1.54E-06 3.08E-06 ALF 5.58E-10 5.58E-10 1.12E-09 R.C 1.14E-08 1.14E-08 R.

SEFC 1.88E-08 4.88E-08 9.53E-07 1.02E-06 SEF 3.32E-09 3.32E-09 SEC 5.54E-04 3.86E-06 5.58E-04 SE 1.78E-06 4.99E-05 5.17E-05

?

SLFC 1.84E-05 1.19E-09 1.19E-09 7.71E-07 1.54E-07 9.21E-08 1.03E-06 5.84E-07 2.74E-07 1.06E-06 4.55E-10 2.24E-05 8

SLF 7.20E-09 2.94E-11 1.62E-09 8.85E-09 SLC 3.30E-12 3.04E-09 3.25E-10 3.37E-09 SL 4.41E-11 4.41E-11 TEFC 1.61E-09 1.61E-09 2.97E-06 5.94E-07 3.54E-07 3.96E-06 6.25E-08 2.59E-07 4.07E-06 2.81E-09 1.23E TEF 1.73E-10 3.46E-11 2.07E-11 9.60E-10 2.37E-10 1.43E-09 TEC 1.63E-10 1.63E-10 1.0!E-06 2.02E-07 1.20E-07 1.35E-06 2.57E-07 5.36E-08 1.39E-06 3.37E-05 3.81E-05 TE 2.34E-08 4.68E-09 2.79E-09 3.14E-06 3.62E-061.05E-09 3.21E-08 2.00E-08 3.74E-06 V2E 5.29E-07 5.29E-07 V2L 9.40E-09 9.4E-09 2.37E-06 3.40E-09 9.40E-09 2.41E-06 Y

7.80E-07 7.80E-07 TOT 4. 2.20E-061.81E-06 5.75E-04 2.90E-061.24E-081.24E-08 4.78E-06 9.55E-07 5.69E-07 6.36E-06 5.83E-05 5.88E-07 6.54E-06 7.80E-07 9.60E-07 3.J7E-05 6.95E-04

~*Model 1 - Model 0 plus Event Tree 17 (loss of service water).

Case 6 - Chg and SI under A0T2 and all others under A0T1.

Table 4.20 Plant Damage State and Core Damage Frequencies for Model 1 Case 7 *

't MODEL 1 EASE 7 ET1 ET2 ET3 ET4 ETS ET6 ET7 ET8 ET9 ET11 ET12A ET13 ET14 ET15 ET16 ET17 TOTAL 9.31E-07 AEFC 6.68E-07 2.63E-07 AEF AEC 1.14E-08 1.14E-06 2.06E-10 AE 1.03E-10 1.03E-10 3.24E-06 ALFC 1.62E-06 1.62E-06 1.12E-09 ALF 5.58E-10 5.58E-10 1.14E-08 ALC 1.14E-08 A.

SEFC 1.88E-08 4.88E-08 9.53E-07 1.02E-06 3.32E-09 3.32E-09 SEF SEC 5.54E-04 3.86E-06 5.5BE-04 SE 1.78E-06 4.99E-05 5.17E-05 ?

SLFC 2.35E-05 1.19E-09 1.19E-09 9.84E-07 1.97E-07 1.17E-07 1.31E-06 9.25E-07 3.49E-07 1.35E-06 4.55E-10 2.87E-05 $

SLF 8.39E-09 2.94E-11 3.80E49 1.22E-06 SLC 3.30E-12 5.87E-09 3.25E-10 6.20E-09 3.92E-10 3.92E-10 SL TEFC 1.61E-09 1.61E-09 2.97E-06 5.94E-07 3.54E-07 3.96E-06 6.13E-08 2.59E-07 4.07E-06 2.81E-09 1.23E-05 TEF 1.73E-10 3.46E-11 2.07E-11 9.60E-10 2.37E-10 1.43E-09 TEC 1.63E-10 1.63E-10 1.01E-06 2.02E-07 1.20E-07 1.35E-06 2.57E-07 5.36E-08 1.39E-06 3.37E-05 3.81E-05 TE 2.34E-08 4.69E-09 2.79E-09 3.14E-06 3.62E-061.05E-09 3.21E-08 2.00E-08 3.74E-06 V2E 5.29E-07 5.29E-07 V2L 9.40E-09 9.40E-09 2.44E-06 9.40E-09 9.40E-09 2.48E-06 7.80E-07 7.80E-07 V

TOT 4. 2.31E-061.90E-06 5.80E-04 2.97E-061.24E-081.24E-08 4.99E-06 9.98E-07 5.94E-07 6.65E-06 5.87E-05 6.63E-07 6.83E-06 7.80E-07 9.60E-07 3.37E-95 7.

Model 1 - Model 0 plus Event Tree 17 (loss of service water).

Case 7 - RHR under A0T2 and all others under A0T1.

Table 4.21 Plant Dasay State and Core Damage Frequencies for Mode! ! Case 8

MODEL 1 CAE 8 ET!

ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ET!!

ET12A ET13 ET14 ET15 ET16 ET17 TOTAL AEFC 6.36E-07 2.30E-07 8.66E-07 AEF AEC 1.14E-08 1.14E-08 AE 1.0 I-10 1.03E-10 2.06E-10 ALFC 1.54E-06 1.54E-06 3.08E-06 ALF 5.58E-10 5.58E-10 1.12E-09 ALC 1.14E-08 1.14E-08 AL SEFC 5.08E-08 4.88E-08 9.53E-07 1.05E-06 SEF 9.18E-09 9.18E-09 SEC 5.54E-04 3.86E-06 5.58E-04 SE 1.78E-06 4.99E-05 5.17E-05

?

SLFC 1.84E-05 1.33E-091.33E-09 2.26E-06 4.52E-07 2.70E-07 3.01E-06 8.55E-07 3.49E-07 3.09E-06 4.55E-10 2.87E-05 M

SLF 7.20E-09 2.60E-10 1.85E-09 9.31E-09 SLC 3.30E-12 4.48E-09 3.25E-10 4.81E-09 SL 4.41E-11 4.41E-11 TEFC 4.44E-09 4.44E-09 8.58E-061.72E-061.02E-061.14E-051.20E-07 7.50E-071.18E-05 2.81E-09 3.54E-05 TEF 1.53E-09 3.06E-10 1.83E-10 3.57E-09 2.10E-09 7.68E-09 TEC 2.47E-10 2.47E-10 1.60E-06 3.19E-07 1.91E-07 2.14E-06 3.92E-07 8.46E-08 2.19E-06 5.15E-05 5.84E-05 TE 3.48E-08 6.93E-09 4.14E-09 4.64E-08 5.35E-06 1.61E-09 4.77E-08 3.11E-08 5.52E-06 V2E 5.29E-07 5.29E-07 V2L 9.40E-09 9.40E-09 6.41E-06 9.40E-09 9.40E-09 6.45E-06 V

7.80E-07 7.80E-07 TOT 4. 2.20E-061.7E-06 5.75E-04 6.94E-061.54E-081.54E-081.25E-05 2.50E-061.49E-061.66E-05 6.05E-051.19E-061.71E-05 7.80E-07 9.65E-07 5.MiE-05 7.51E-

Model 1 - Model 0 plus Event Tree 17 (loss of service water).

Case 8 - AFWS under A0T2 and all others under A0T1.

_s Table 4.22 Plant Damage State and Core Damage Frequencies for Model 1 Case 9*

NEEL 1 CASE 9 ET1 ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ET!!

ET12A ET13 ET14 ET15 ET16 ET17 TOTAL AEFC 6.36E-07 2.30E-07 8.66E-07 AEF AEC 1.14E-08 1.14E-08 AE 1.0 E-10 1.03E-10 2.06E-10 ALFC 1.54E-06 1.54E-06 3.08E-06 ALF 5.58E-10 5.58E-10 1.12E-09 4

ALC 1.14E-08 1.14E-08 AL SEFC 1.88E-08 4.88E-08 9.53E-07 1.02E-06 l

SEF 3.32E-09 3.32E-09 SEC 5.54E-04 3.86E-06 5.58E44 SE 1.78E-06 4.99E-05 5.17E-05 i

SLFC 1.84E-05 1.19E-091.19E-09 7.74E471.55E-07 9.22E-081.03E-06 6.39E-07 2.74E-071.06E-06 4.55E-10 2.24E-05 d SLF 7.20E-09 2.94E-11 1.65E-09 8.88E-09 SLC 3.30E-12 3.39E-09 3.25E-10 3.72E-09 SL 4.41E-11 4.41E-II i

TEFC 1.61E-09 1.6tE-09 2.97E-06 5.94E-07 3.54E-07 3.96E-06 6.13E-48 2.59E-07 4.07E-M 2.81E-09 1.23E-05 TEF 1.73E-10 3.46E-11 2.07E-11 9.60E-10 2.37E-10 1.43E-09 TEC 1.63E-10 1.63E-10 1.01E-06 2.02E-07 1.20E-07 1.35E-06 2.57E-07 5.36E-08 1.39E-06 3.37E-05 3.'81E-05 I

2.34E-08 4.68E-09 2.79E-09 3.14E-06 3.62E-061.05E-09 3.21E-08 2.00E48 3.74E-06 TE V2E 5.29E-07 5.29E-07 V2L 9.40E-09 9.40E-09 2.37E-06 9.40E-09 9.40E49 2.41E-06 V

7.80E-07 7.80E-07 TOTAL 2.20E-061.79E-06 5.75E-04 2.90E-061.24E-081.24E-08 4.78E-06 9.56E-07 5.69E-07 6.37E-06 5.84E-05 5.88E47 6.55E-06 7.80E47 9.60E47 3.37E-05 6.95E-04

Model 1 - Model 0 plus Event Tree 17 (loss of service water).

Case 9 - CCWS under A0T2 and all others under A0T1.

i Table 4.23 Plant Damage State ar.d Core Damage Frequencies for Model 2 Case 1*

MODEL 2 CASE 1 ET!

ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ET!!

ET12A ET13 ET14 ET15 ET16 ET17 TOTAL AEFC 6.36E-07 2.30E-07 8.66E-07 AEF AEC 1.14E-08 1.14E-08 AE 1.03E-10 1.03E-10 2.06E-10 ALFC 1.54E-06 1.54E-06 3.08E46 ALF 5.58E-10 5.58E-10 1.12E-09 ALC 1.14E-08 1.14E48 AL SEFC 1.88E-08 4.88E-08 9.53E-07 1.02E-06 4

SEF 3.32E-09 3.32E-09 SEC 5.87E-07 5.26E-09 5.93E47 SE 1.16E-08 2.42E-07 2.54E47 SLFC 1.84E-05 1.19E-09 1.19E-09 7.71E-07 1.54E-07 9.21E-08 1.03E-06 5.83E-07 2.74E-07 1.06E-06 4.55E-10 2.24E-05 i

SLF 7.20E-09 2.94E-!! 1.62E-09 8.85E-09 y

SLC 3.3t'E-12 3.04E-09 3.25E-10 3.37E-09 SL 4.41E-11 4.41E-11 TEFC 1.61E-091.61E-09 2.97E-06 5.94E-07 3.54E-07 3.%E-06 6.13E-08 2.59E-07 4.07E-06

2. 61E-09 1.23E-05 TEF 1.73E-10 3.46E-11 2.07E-11 9.60E-10 e.37E-10 1.43E-09 TEC 1.63E-101.63E-101.01E-06 2.02E-071.20E471.35E-06 2.57E-07 5.36E481.39E-06 3.37E-05 3.81E-05 TE 2.34E-08 4.68E-09 2.'79E-09 3.14E-06 3.62E-06 1.05E-09 3.21E-08 2.00E-08 3.74E-06 V2E 5.29E-07 5.29E-07 V2L 9.40E-09 9.40E-09 2;37E-06 9.40E-09 9.40E-09 2.41E-06 V

7.80E-07 7.80E-07 TOT 4. 2.20E-061.79E-061.90E-05 2.90E-061.24E-061.24E-08 4.78E46 9.55E-07 3.69E-07 6.36E-06 4.82E-06 5.8BE-07 6.54E-06 7.80E47 9.60E-07 3.37E-05 8.60E-05

Model 2 - Model I with P (S -QA) = 0 where S -QA is the seal LOCA event given loss of service water.

r 2 2

Case 1

- All systems under N)T1.

i T. ole 4.24 Plant Damage State and Core Damage Frequencies for Model 2 Case 2*

MODEL 2 CE E 2 ET!

ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ET11 ET12A ET13 ET14 ET15 ET16 ET17 TOTE 9.50E-07 EFC 6.68E-07 2.82E-07 AEF 6.13E-08 AEC 6.13E-06 1.83E-09 AE 9.15E-10 9.15E-10 3.24E-06 ALFC 1.62E-06 1.62E-06 1.12E-09 ALF 5.58E-10 5.58E-10 6.13E-06 l

ALC 6.13E-08 AL SEFC 5.40E-08 5.38E-08 9.53E-07 1.06E-06 9.18E-09 9.18E-09 SEF SEC 3.20E-06 3.86E-08 3.24E-06 SE 5.28E-08 6.16E-07 6.69E-07 SLFC 2.35E-05 1.33E-091.33E-09 2.90E-06 5.79E-07 3.46E-07 3.86E-06 2.71E-06 4.45E-07 3.97E-06 4.55E-10 3.83E-05 i

SLF 1.03E-08 2.20E-10 2.16E-06 3.21E-06 M

SLC 2.28E-09 8.04E-08 9.30E-10 8.36E-08 1.81E-09 1.81E-09 l

SL TEFC 4.44E-09 4.44E-09 8.58E-061.72E-061.02E-061.14E-05 2.08E-07 7.50E-071.18E-05 2.81E-09 3.55E-05 TEF 1.53E-09 3.06E-10 1.83E-10 4.16E-09 2.10E-09 8.28E-09 TEC 6.17E-10 6.17E-10 8.01E-06 1.60E-06 9.57E-07 1.00E-05 2.56E-06 4.24E-07 1.10E-05 3.92E-04 4.28E-04 TE 1.40E-07 2.81E-08 1.68E-08 1.88E-07 2.22E-05 7.03E-09 1.92E-07 2.94E-07 2.312-05 V2E 2.64E-06 2.64E 4 V2L 9.40E-09 9.40E-09 6.48E-06 9.40E-09 9.40E-09 6.52E-06 t

7.80E-07 7.80E-07 V

TOTAL 2.36E-061.97E-06 2.68E-05 9.12E-061.58E-081.58E-081.96E-05 3.93E-06 2.34E-06 2.63E-05 2.85E-051.63E-06 2.69E-05 7.80E-07 9.65E-07 3.93E-0 o

ModeT 2 Model l sith Pr(S -QA) = 0 where S -QA is the seal LOCA event given loss of service water.

j

~

2 2

Case 2 - All systems under A0T2.

i

Table 4.25 Plant Damage State and Core Damage Frequencies for Model 2 Case 3*

MODEL 2 CASE 3 ETI ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ET11 ET12A ET13 ET14 ET15 ET16 ET17 TOTAL AEFC 6.36E-07 2.30E-07 8.66E-07 rF AEC 1.14E-08 1.14E48 E

9.15E-10 9.15E-10 1.83E-09 ALFC 1.54E-06 1.54E-06 3.08E-06 ALF 5.58E-10 5.58E-10 1.12E-09 ALC 1.14E-08 1.14E-08 AL SEFC 2.05E-08 5.38E-08 9.53E-07 1.03E-06 SEF 3.32E-09 3.32E-09 SEC 5.87E-07 1.02E-08 5.98E-07 SE 5.26E-08 5.30E-07 5.83E-07 SLFC 1.84E-05 1.19E-09 1.19E-09 7.77E-07 1.55E-07 9.27E-08 1.04E-06 1.78E-06 2.74E-07 1.06E-06 4.55E-10 2.36E-05 i

SLF 7.20E-09 2.94E-11 1.14E-08 1.8EE-08 SLC 3.30E-12 9.46E-09 3.25E-10 9.79E-09 SL 2.04E-10 2.04E-10 TEFC 1.61E-09 1.61E-09 2.97E-06 5.94E-07 3.55E-07 3.96E-06 1.46E-07 2.59E-07 4.07E-06 2.81E-09 1.24E45 TEF 1.73E-10 3.4EE-11 2.07E-11 9.60E-10 2.37E-10 1.43E-09 TEC 1.63E-10 1.63E-10 1.01E-06 2.02E-07 1.20E-07 1.35E-06 4.38E-07 5.3EE-08 1.39E-06 3.37E-05 3.83E-05 TE 1.05E-07 2.10E-08 1.25E-08 1.40E-07 1.24E-05 5.18E-09 1.44E-07 2.00E-081.28E-05 V2E 5.62E-07 5.62E-07 V2L 9.40E-09 9.40E-09 2.37E-06 9.40E-09 9.40E-09 2.41E-06 V

7.80E-07 7.80E-07 TOTAL 2.20E-061.79E-061.91E-05 2.93E-061.24E-081.24E-08 4.87E-06 9.72E-07 5.80E-07 6.48E-061.54E-05 5.92E-07 6.67E-06 7.80E-07 9.60E-07 3.37E-05 9.70E-05

Model 2 - Model I with Pr(S -QA) = 0 where S -QA is the seal LOCA event given loss of service water.

2 2

Case 3 - DGs under A0T2 and all others under A0T1.

Table 4.26 Plant Damage State and Core Damage Frequercies for Model 2 Case 4*

MODEL 2 CASE 4 ET!

ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ET11 ET12A ET13 ET14 ET15 ET16 ET17 TOTAL EFC 6.36E-07 2.30E-07 8.66E-07 EF EC 5.13E-08 6.13E-08 E

1.03E-10 1.03E-10 2.06E-10 ALFC 1.54E-06 1.54E-06 3.CBE-06 ALF 5.58E-10 5.58E-10 1.12E-09 ALC 6.13E-08 6.13E-08 AL SEFC 2.03E-08 4.8BE-08 9.53E-07 1.02E-06 SEF 3.32E-09 3.32E-09 SEC 3.20E-06 3.37E-08 3.23E-06 SE 1.17E-08 3.28E-07 3.40E-07 SLFC 1.84E-05 1.19E-09 1.19E-09 7.71E-07 1.54E-07 9.21E-08 1.03E-06 5.83E-07 2.74E-07 1.06E-06 4.55F 10 2.24E-05 ?

i SLF 7.20E-09 2.94E-11 1.62E-09 8.85E-09 d SLC 3.30E-12 3.04E-09 9.30E-10 3.97E-09 SL -

4.41E-11 4.41E-11 TEFC 1.61E-09 1.61E-09 2.97E-06 5.94E-07 3.54E-07 3.96E-06 6.13E-08 2.59E-07 4.07E-06 2.81E-09 1.23E-05 TEF 1.73E-10 3.46E-11 2.07E-11 9.60E-10 2.37E-10 1.43E-09 TEC 5.33E-10 5.33E-10 4.95E-06 9.91E-07 5.91E-07 6.64E-06 1.51E-06 2.62E-07 6.78E-06 2.57E-04 2.78E-04 TE 2.34E-08 4.68E-09 2.79E-09 3.14E-08 7.25E-06 1.05E-09 3.21E-08 1.52E-07 7.50E-06 i'

V2E 2.61E-06 2.61E-06 V2L 9.40E-09 9.40E-09 2.37E-06 9.40E-09 9.40E-09 2.41E-06 V

7.80E-07 7.80E-07 TOTAL 2.25E-06 1.84E-06 2.16E-05 4.98E-06 1.27E-08 1.27E-08 8.71E-06 1.74E-06 1.04E-06 1.17E-05 9.82E-06 7.97E-07 1.19E-05 7.80E-07 9.60E-07 2.57E-04 3.35E-04

Model 2 - Model 1 with Pr(S -QA) = 0 where S -QA is the seal LOCA event given loss of service water.

2 2

Case 4 - ESWS under A0T2 and all others under A0T1.

Table 4.27 Plant Damage State and Core Damage Frequencies for Model 2 Case 5*

MODEL 2 CASE 5 ET1 ET2 ET3 ET4 ETS ET6 ET7 ET8 ET9 ET11 ET12A ET13 ET14 ET15 ET16 ET17 TOTAL AEFC 6.36E-07 2.30E-07 8.66E-07 AEF AEC 1.14E-08 1.14E-08 AE 1.03E-10 1.03E-10 2.06E-10 ALFC 1.54E-06 1.54E-06 3.08E-06 ALF 5.58E-10 5.58E-10 1.12E-09 ALC 1.14E-08 1.14E-08 AL SEFC 1.38E-08 4.88E-08 9.53E-07 1.02E-06 SEF 3.32E-09 3.32E-09 SEC 5.87E-07 5.26E-09 5.93E-07 SE 1.!EE-08 2.42E-07 2.54E-07 SLFC 1.84E-05 1.19E-09 1.19E-09 7.71E-07 1.54E-07 9.21E-08 1.03E-06 5.83E-07 2.74E-07 1.06E-06 4.55E-10 2.24E-05 i

SLF 9.12E-09 2.94E-11 2.72E 4 1.19E-08 SLC 2.28E-09 2.08E-08 3.25E-10 2.34E-08 SL 4.41E-11 4.41E-11 TEFC 1.61E-091.61E-09 2.97E-06 5.94E-07 3.54E-07 3.%E-06 6.13E-08 2.59E-07 4.07E-06 2.81E-09 1.23E-05 TEF 1.73E-10 3.46E-!! 2.07E-11 1.02E-09 2.37E-10 1.49E-09 TEC 1.63E-10 1.63E-10 1.01E-06 2.02E-07 1.20E-07 1.35E-06 2.58E-07 5.36E-08 1.39E-06 3.37E-05 3.81E-05 TE 2.34E-08 4.68E-09 2.79E49 3.14E48 3.62E-061.05E-09 3.21E-08 2.48E-08 3.74E-06 V2E 5.29E-07 5.29E-07 V2L 9.40E-09 9.40E-09 2.37E-06 9.40E-09 9.40E-09 2.41E-06 V

7.80E-07 7.80E-07 TOTAL 2.20E-061.79E-061.9CE-05 2.90E-061.24E-081.24E-08 4.78E-06 9.55E-07 5.69E-07 6.36E-06 4.84E-06 5.8BE-07 6.54E-06 7.80E47 9.60E-07 3.37E-05 8.61E-05 1 with Pr(S -QA) = 0 where S -QA is the seal LOCA event given loss of service water.

Model 2 - Model 2

2 Case 5 - CF and CS under A0T2 and all others under A0T1.

t

Table 4.28 Plant Damage State and Core Damage Frequencies for Model 2 Case 6 MODEL 2 CASE 6 ET1 ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ET!!

ET12A ET13 ET14 ET15 ET16 ET17 TOTAL AEFC 6.36E-07 2.50E-07 8.86E-07 MF AEC 1.14E-08 1.14E-06 AE 1.03E-10 1.03E-10 2.06E-10 ALFC 1.54E-06 1.54E-06 3.08E-06 ALF 5.58E-10 5.58E-10 1.12E-09 ALC 1.14E-08 1.14E-08 AL SEFC 1.88E-08 4.88E-08 9.53E-07 1.02E-06 SEF 3.32E-09 3.32E-09 SEC 5.87E-07 5.26E-09 5.93E-07 SE 1.16E-08 2.42E-07 2.54E-07 SLFC 1.84E-05 1.19E-09 1.19E-09 7.71E-07 1.54E-07 9.21E-08 1.03E-06 5.84E-07 2.74E-07 1.06E-06 4.55E-10 2.24E-05 L

SLF 7.20E-09 2.94E-11 1.62E-09 8.85E-09 e

SLC 3.30E-12 3.04E-09 3.25E-10 3.37E-09 SL 4.41E-11 4.41E-11 TEFC 1.61E-091.61E-09 2.97E-06 5.94E-07 3.54E-07 3.%E-06 6.25E-08 2.59E-07 4.07E-06 2.81E-09 1.23E-05 TEF' 1.73E-10 3.46E-11 2.07E-11 9.60E-10 2.37E-10 1.43E-09 TEC 1.63E-101.63E-101.01E-06 2.02E-071.20E-071.35E-06 2.57E-07 5.36E-081.39E-06 3.37E-05 3.81E-05 TE 2.34E-08 4.68E-09 2.79E-09 3.14E-08 3.62E-06 1.05E-09 3.21E-08 2.00E-08 3.74E-06 V2E 5.29E-07 5.23E-07 V2L 9.40E-09 9.40E-09 2.37E-06 9.40E-09 9.40E-09 2.41E-06 V

7.80E-07 7.80E-07 TOTAL 2.20E-061.81E-061.90E-05 2.90E-061.24E-081.24E-08 4.78E-06 9.55E-07 5.69E-07 6.36E-06 4.82E-06 5.88E-07 6.54E-06 7.80E-07 9.60E-07 3.37E-05 8.61E-05

Model 2 - Model I with Pr(S -0A) = 0 where S -QA is the seal LOCA event given loss of service water.

2 2

Case 6 - Chg and SI under A0T2 and all others under A0T1.

Table 4.29 Plant Damage State and Core Damage Frequencies for Model 2 Case 7*

l MODEL 2 CASE 7 ET!

ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ET!!

ET12A ET13 ET14 ET15 ET16 ET17 TOTAL AEFC 6.68E-07 2.63E-07 9.31E-07 AEF AEC 1.14E-08 1.14E-08 AE 1.03E-10 1.03E-10 2.06E-10 ALFC 1.62E-06 1.62E-06 3.24E-06 ALF 5.58E-10 5.58E-10 1.12E-09 ALC 1.14E-08 1.14E-08 R.

SEFC 1.88E-08 4.88E-08 9.53E-07 1.02E-06 SEF 3.32E49 3.32E-09 SEC 5.87E-07 5.26E-09 5.93E-07 SE 1.16E-08 2.42E-07 2.54E-07 SLFC 2.35E-05 1.19E-091.19E49 9.84E-071.97E-071.17E-071.31E-06 9.25E-07 3.49E-071.35E-06 4.55E-10 2.87E-05 p

SLF 8.39E-09 2.94E-11 3.80E-09 1.22E-08 g

SLC 3.30E-12 5.87E-09 3.25E-10 6.20E-09 SL 3.92E-10 3.92E-10 TEFC 1.61E-09 1.61E-09 2.97E-06 5.94E-07 3.54E-07 3.96E-06 6.13E-08 2.59E-07 4.07E-06 2.81E-09 1.23E-05 TEF 1.73E-10 3.46E-11 2.07E-11 9.60E-10 2.37E-10 1.43E-09 TEC 1.63E-10 1.63E-10 1.0!E-06 2.02E-07 1.20E-07 1.35E-06 2.57E-07 5.36E-08 1.39E-06 3.37E-05 3.81E-05 TE 2.34E-08 4.68E-09 2.79E-09 3.14E-06 3.62E-061.05E-09 3.21E-08 2.00E-08 3.74E-06 V2E 5.29E-07 5.29E-07 V2L 9.40E-09 9.40E-09 2.44E-06 9.40E-09 9.40E-09 2.48E-06 V

7.80E-07 7.80E-07 TOTAL 2.31E-061.90E-06 2.41E-05 2.97E-061.24E-081.24E-08 4.99E-06 9.98E-07 5.94E-07 6.65E-06 5.17E-06 6.63E-07 6.83E-06 7.80E-07 9.60E-07 3.37E-05 9.27E-05 2

CModel 2 - Model I with Pr(S -QA) = 0 where S -QA is the seal LOCA event given loss of service water.

2 2

Case 7 - RHR under A0T2 and all others under A0T1.

I

i l

Table 4.30 Plant Damage State and Core Damage Frequencies for Model 2 Case 8*

MODEL 2 CASE 8 ET1 ET2 ET3 ET4 ETS ET6 ET7 ET8 ET9 ET11 ET12A ET13 ET14 ET15 ET16 ET17 TOTAL AEFC 5.36E-07 2.30E-07 8.66E-07 AEF AEC 1.14E48 1.14E-08 AE 1.03E-10 1.03E-10 2.06E-10 ALFC 1.54E-06 1.54E-06 3.08E46 ALF 5.58E-10 5.58E-10 1.12E-09 ALC 1.14E-08 1.14E-08 AL SEFC 5.08E-08 4.88E-08 9.53E-07 1.05E-06 SEF 9.18E49 9.18E-09 SEC 5.87E-07 5.26E-09 5.93E-07 SE 1.16E-08 2.42E-07 2.54E-07 a

SLFC 1.84E-05 1.33E-09 1.33E-09 2.26E-06 4.52E-07 2.70E-07 3.01E-06 8.55E-07 3.49E-07 3.09E-06 4.55E-10 2.87E-05 1.

SLF 7.20E-09 2.50E-10 1.85E-09 9.31E-09 SLC 3.30E-12 4.48E-09 3.25E-10 4.81E-09 SL 4.41E-11 4.41E-11 TEFC 4.44E49 4.44E-09 8.58E-061.72E-061.02E-061.14E-051.20E-07 7.50E-071.18E45 2.81E-09 3.54E-05 TEF 1.53E-09 3.06E-10 1.83E-10 3.57E-09 2.10E-09 7.68E-09 TEC 2.47E-10 2.47E-101.60E-06 3.19E-071.91E47 2.14E46 3.92E-07 8.46E-08 2.19E46 5.15E-05 5.84E-05 TE 3.48E-08 6.93E-09 4.14E-09 4.64E-08 5.35E-06 1.61E-09 4.77E-08 3.11E-08 5.52E-06 V2E 5.29E-07 5.29E-07 U2L 9.40E-09 9.40E-09 6.41E-06 9.40E-09 9.40E-09 6.45E-06 V

7.80E-07 7.80E-07 TOTAL 2.20E-06 1.79E-06 1.91E-05 6.94E-06 1.54E-08 1.54E-08 1.25E-05 2.50E-06 1.49E-Oo 1.66E-05 7.02E-06 1.19E-06 1.71E-05 7.80E-07 9.65E-07 5.15E-05 1.42E-04 OModel 2 - Model I with Pr(S -QA) = 0 where S -QA is the seal LOCA event given loss of service water.

2 2

Case 8 - AFWS under A0T2 and all others under A0T1.

i l

Table 4.31 Plant Damage State and Core Damage Frequencies for Model 2 Case 9 MODEL 2 CASE 9 ET!

ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ET11 ET12A ET13 ET14 ET15 ET16 ET17 TOTAL AEFC 6.36E-07 2.30E-07 8.66E-07 AEF AEC 1.14E-08 1.14E-08 AE 1.03E-10 1.03E-10 2.06E-10 ALFC 1.54E-06 1.54E-06 3.06E-06 ALF 5.58E-10 5.58E-10 1.12E-09 ALC 1.14E-08 1.14E-08 AL SEFC 1.88E-08 4.88E-08 9.53E-07 1.C2E-06 SEF 3.32E-09 3.32E-09 SEC 5.87E-07 5.26E-09 5.93E-07 SE 1.16E-08 2.42E-07 2.54E-07 SLFC 1.84E-05 1.19E-091.19E-09 7.74E-071.55E-07 9.22E-081.03E-06 6.39E-07 2.74E-071.06E-06 4.55E-10 2.24E-05

?

SLF 7.20E-09 2.94E-11 1.65E-09 8.88E-09 g

SLC 3.30E-12 3.39E-09 3.2" -10 3.72E-03 E

SL 4.41E-11 4.41E-11 TEFC 1.61E-09 1.61E-09 2.97E-06 5.94E-07 3.54E-07 3.96E-06 6.13E-08 2.59E-07 4.07E-06 2.81E-09 1.23E-05 TEF 1.73E-10 3.46E-11 2.07E-11 9.60E-10 2.37E-10 1.43E-09 TEC 1.63E-10 1.63E-10 1.01E-06 2.02E-07 1.20E-07 1.35E-06 2.57E-07 5.36E-08 1.39E-06 3.37E-05 3.81E-05 TE 2.34E-08 4.6BE-03 2.79E-09 3.14E-08 3.62E-06 1.05E-09 3.21E-08 2.00E-08 3.74E-06 V2E 5.29E-07 5.29E-07 V2L. 9.40E-09 9.40E-09 2.37E-06 9.40E-09 9.40E-09 2.41E-06 V

7.80E-07 7.80E-07 TOTAL 2.20E-061.79E-061.90E-05 2.90E-061.24E-081.24E-08 4.78E-06 9.56E-07 5.69E-07 6.37E-06 4.88E-06 5.88E-07 6.55E-06 7.E0E-07 9.60E-07 3.37E-05 8.61E-05 OModel 2 - Model I with Pr(S -0A) = 0 where S -QA is the seal LOCA event given loss of service water.'

2 2

Case 9 - CCWS under A0T2 and all others under A0T1.

4

Table 4.32 Plant Damage State and Core Damage Frequencies for Model 3 Case 1

MODEL 3 CASE 1 ETI ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ET11 ET12A ET13 ET14 ET15 ET16 ET17 TOTAL EFC 6.36E-07 2.30E-07 8.66E-07 AEF AEC 5.03E-09 5.03E-09 AE 1.03E-10 1.03E-10 2.06E-10 ALFC 1.54E-06 1.54E-06 3.08E-06 ALF 5.58E-10 5.58E-10 1.12E-09 ALC 5.03E-09 5.03E-09 AL SEFC 1.86E-08 4.88E-08 9.53E-07 1.02E-06 SEF 3.32E-09 3.32E-09 SEC 1.13E-04 1.53E-06 1.14E-04 SE 1.69E-06 4.32E-05 4.49E-05 SLFC 1.84E-05 1.19E-09 1.19E-09 7.71E-07 1.54E-07 9.21E-08 1.03E-06 5.83E-07 2.74E-07 1.06E-06 4.55E-10 2.24E-05

?

SLF 7.20E-09 2.94E-11 1.62E-09 8.8 2 -09 O

SLC 3.30E-12 3.03E-09 2.4BE-10 3.28E-09 SL 4.41E-11 4.41E-11 TEFC 1.61E-09 1.61E-09 2.97E-06 5.94E-07 3.54E-07 3.96E-06 6.13E-08 2.59E-07 4.07E-06 2.81E-09 1.23E-05 TEF 1.73E-10 3.46E-11 2.07E-11 9.60E-10 2.37E-10 1.43E-09 TEC 1.16E-10 1.16E-10 5.07E-07 1.01E-07 6.05E-08 6.76E-07 9.69E-08 2.70E-08 6.95E-07 5.30E-06 7.47E-06 TE 2.34E-08 4.68E-09 2.79E-09 3.14E48 3.15E-061.05E-09 3.21E-08 3.14E-09 3.2EE-06 V2E 2.63E-07 2.63E-07 V2L 9.40E-09 9.40E-09 2.37E-06 9.40E-09 9.40E-09 2.41E-06 7.80E-07 7.80E-07 V

TOTAL 2.19E-06 1.79E-06 1.33E-04 2.63E-06 1.23E-08 1.23E-08 4.27E-06 8.54E-07 5.09E-07 5.69E-06 4.87E-05 5.61E-07 5.85E-06 7.80E-07 9.60E-07 5.31E-06 2.13E-04

Model 3 - Model 1 with no maintenance unavailability contributions from CCWS and ESWS.

Case 1 - All systems under A0T1.

Table 4.33 Plant Damage Stata and Core Damage Frequencies for Model 3 Case 2

MODEL 3 CASE 2 ET!

ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ET!!

ET12A ET13 ET14 ET15 ET16 ET17 TOTAL-AEFC 6.68E-07 2.82E-07 9.50E-07 AEF AEC 5.03E-09 5.03E-09 i

AE 9.15E-10 9.15E-10 1.83E-09 ALrt 1.62E-061.62E-06 3.24E-06 ALF 5.5dE-10 5.58E-10 1.12E-09 ALC 5.03E-09 5.03E-09 R.

SEFC 5.23E-08 5.38E-08 9.53E-07 1.06E-06 SEF 9.18E-09 9.18E-09

.SEC 1.13E-04 4.23E-06 1.17E-04 SE 7.02E-06 1.68E-04 1.75E-04 SLFC 2.35E-05 1.33E-09 1.33E-09 2.89E-06 5.79E-07 3.45E-07 3.86E-06 2.62E-06 4.44E-07 3.96E-06 4.55E-10 3.82E-05 i

SLF 1.03E-08 2.20E-10 2.12E-08 3.17E-08 SLC 2.2SE-09 7.52E-08 2.48E 7.77E-08 SL 1.81E-09 1.81E-09 TEFC 4.44E-09 4.44E-09 8.5BE-06 1.72E-06 1.02E-06 1.14E-05 2.08E-07 7.50E-07 1.18E-05 2.81E-09 3.55E-05 TEF 1.53E-69 3.06E-10 1.83E-10 4.16E-09 2.10E-09 8.28E-09 TEC 2.00E-10 2.00E-10 7.77E-07 1.56E-07 9.28E-08 1.04E-06 3.78E-07 4.14E-08 1.06E-06 8.11E-06 1.17E-05 TE 1.40E-07 2.81E-08 1.68E-08 1.88E-07 1.58E-05 7.03E-09 1.92E-07 6.08E-091.64E-05 V2E 2.96E-07 2.96E-07 V2L 9.40E-09 9.40E-09 6.48E-06 9.40E-09 9.40E-09 6.52E-06 V

7.80E-07 7.80E-07 TOTAL 2.30E-061.92E-061.43E-04 6.78E-061.54E-081.54E-081.24E-05 2.48E-061.47E-061.65E-051.91E-041.24E-061.70E-05 7.80E-07 9.65E-07 8.11E-06 4.06E-04

Model 3 - Modef 1 with no maintenance unavailability contributions from CCWS and ESWS.

Case 2 - All systems under A0T2.

<g-

Table 4.34 Plant Damage State and Core Dasage Frequencies for Model 3 Case 3 MODE 1. 3 CASE 3 ET1 ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ET!!

ET12A ET13 ET14 ET15 ET16 ET17 TOTAL AEFC 6.36E-07 2.30E-07 8.66E-07 AEF AEC 5.03E-09 5.03E-09 AE 9.15E-10 9.15E-10 1.83E-09 ALFC 1.54E-06 1.54E-06 3.08E-06 ALF 5.58E-10 5.58E-10 1.12E-09 ALC 5.03E-09 5.03E-09 AL SEFC 2.03E-08 5.38E-08 9.53E-07 1.03E-06 SEF 3.32E-09 3.32E-09 SEC 1.13E-04 4.23E-06 1.17E-04 SE 7.02E-06 1.68E-04 1.75E-04 SLFC 1.84E-05 1.19E-091.19E49 7.77E-071.55E-07 9.27E-081.04E-061.78E-06 2.74E-071.06E-06 4.55E-10 2.36E-05

?

SLF 7.20E-09 2.94E-11 1.14E-08 1.86E-08 SLC 3.30E-12 9.46E-09 2.48E-10 9.71E-09 SL 2.04E-10 2.04E-10 TEFC 1.61E-09 1.61E-09 2.97E-06 5.94E-07 3.55E-07 3.96E-06 1.46E-07 2.59E-07 4.07E-06 2.81E-09.

1.24E-05 TEF 1.73E-10 3.46E-11 2.07E-11 9.60E-10 2.37E-10 1.43E-09 TEC 1.16E-101.16E-10 5.07E-071.01E-07 6.05E-08 6.76E-07 2.78E-07 2.70E-08 6.95E-07 5.30E-06 7.65E-06 TE 1.05E-07 2.10E-081.25E-081.40E-071.20E45 5.18E-091.44E-07 3.14E-09 1.24E-05 V2E 2.96E-07 2.96E-07 V2L 9.40E-09 9.40E-09 2.37E-06 9.40E-09 9.40E-09 2.41E-06 7.80E-07 7.80E-07 V

TOTAL 2.19E-061.79E-061.38E-04 2.67E-061.23E-081.23E-08 4.36E-06 8.71E-07 5.21E47 5.81E-061.87E-04 5.66E-07 5.98E-06 7.80E47 9.60E-07 5.31E-06 3.56E-04

Model 3 - Model I with no maintenance unavailability contributions from CCWS and ESWS.

Case 3 - DGs under A0T2 and all others under A0T1.

Table 4.35 Plant Damage State and Core Damage Frequencies for Model 3 Case 5*

MODEl. 3 CASE 5 ET!

ET2 ET3 ET4 ETS ET6 ET7 ET8 ET9 ET11 ET12A ET13 ET14 ET15 ET16 ET17 TOTAL AEFC 6.36E-07 2.30E-07 8.66E-07 AEF AEC 5.03E-09 5.03E-09 AE 1.03E-10 1.03E-10 2.06E-10 ALFC 1.54E-06 1.54E-06 3.08E-06 i

ALF 5.58E-10 5.58E-10 1.12E-09 ALC 5.03E-09 5.03E-09 AL SEFC 1.86E-08 4.88E-08 9.53E-07 1.02E-06 SEF 3.32E-49 3.32E-09 SEC 1.13E-04 3.86E-06 1.16E-04 SE 1.79E-06 4.32E-05 4.50E-05 SLFC 1.84E-05 1.19E-09 1.19E-09 7.71E-07 1.54E-07 9.21E-08 1.03E-06 5.83E-07 2.74E-07 1.06E-06 4.55E-10 2.24E-05 L

SLF 9.12E-03 2.94E-11 2.72E-09 1.19E-08 cn SLC 2.2BE-09 2.07E-08 2.48E-10 2.32E-08 SL 4.41E-11 4.41E-11 TEFC 1.61E-09 1.61E-09 2.97E-06 5.94E-07 3.54E-07 3.96E-06 6.13E-08 2.59E-07 4.07E-06 2.81E-09 1.23E-05 TEF 1.73E-10 3.46E-11 2.07E-11 1.02E-09 2.37E-10 1.49E-09 TEC 1.16E-10 1.16E-10 5.07E-07 1.0!E-07 6.05E-08 6.76E-07 9.79E-08 2.70E-08 6.95E-07 5.30E-06 7.47E-06 TE 2.34E-08 4.68E-09 2.79E-09 3.14E-08 3.16E-06 1.05E-09 3.21E-08 3.90E-09 3.26E-06 V2E 2.63E-07 2.63E-07 V2L 9.40E-09 9.40E-09 2.37E-06 9.40E-09 9.40E-09 2.41E-06 V

7.80E-07 7.80E-07 TOTAL 2.19E-061.79E-061.33E-04 2.63E-061.23E-081.23E-08 4.27E-06 8.54E-07 5.09E-07 5.69E-06 5.10E-05 5.61E-07 5.85E-06 7.80E-07 9.60E-07 5.31E-06 2.15E-04 l

Model 3 - Model 1 with no maintenance unavailability contributions from CCWS and ESWS.

Case 5 - CF and CS under A0T2 and all others under A0T1.

l l

Ta51e 4-36 Plant Damage State and Core Damage Frequencies for Model 3 Case 6*

i MODEL 3 CASE 6 ETt ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ET11 ET12A ET13 ET14 ETIS ET16 ET17 TOTAL 8.86E-07 E FC 6.3EE-07 2.50E-07 EF 5.03E-09 EC 5.03E-09 2.06E-10 E

1.03E-10 1.03E-10 3.08E-06 ALFC 1.54E-06 1.54E-06 1.12E-09 ALF 5.56E-10 5.5BE-10 5.03E49 ALC 5.03E-09 QL 4.88E-08 9.53E-07 1.02E-06 SEFC 1.86E-08 3.32E-09 3.32E-09 SEF i

1.53E-06 1.14E-04 SEC 1.13E-04 4.32E-05 4.49E-05 SE 1.69E-06 SLFC 1.84E-05 1.19E-09 1.19E-09 7.71E-07 1.54E-07 9.21E-08 1.03E-06 5.83E-07 2.74E-07 1.06E-06 4.55E-10 2.24E-05 g

SLF 7.20E-09 2.94E-II 1.62E-09 8.85E-09 N

3.03E-09 2.48E-10 3.28E49 SLC 3.30E-12 4.41E-11 4.41E-11 SL 1.61E-091.61E-09 2.97E-06 5.94E-07 3.54E-07 3.%E-05 6.25E-08 2.59E-07 4.07E-06 2.81E-09 1.23E-05 TEFC 1.73E-10 3.46E-11 2.07E-!! 9.60E-10 2.37E-10 1.43E-09 TEF 1.15E-10 1.16E-10 5.07E-07 1.01E-07 6.05E-08 6.76E-07 9.69E-08 2.70E-08 6.95E-07 5.30E-06 7.47E-06 TEC 2.34E-08 4.68E-09 2.79E-09 3.14E-08 3.16E461.05E-09 3.21E-08 3.14E-09 3.26E-06 TE 2.63E-07 V2E 2.63E-07 2.41E-06 V2L 9.40E-09 9.40E-09 2.37E-06 9.40E-09 9.40E-09 7.80E-07 7.80E-07 V

TOTAL 2.19E-061.81E-061.33E-04 2.63E-061.23E-081.23E-08 4.27E-06 8.54E-07 5.09E-07 5.69E-06 4.87E-05 5.61E47 5.85E-06 7.80E-07

Model 3 - Model I with no maintenance unavailability contributions from CCWS and ESWS.

Case 6 - Chg and SI under A0T2 and all others under A0T1.

Table 4-37 Plant Damage State and Core Damage Frequencies for Model 3 Case 7 MODEL 3 CASE 7 ETI ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ET11 ET12A ET13 ET14 ET15 ET16 ET17 TOTAL AEFC 5.68E-07 2.63E-07 9.31E-07 AEF AEC 5.03E-09 5.03E-09 AE 1.03E-10 1.03E-10 2.06E-10 R FC 1.62E-06 1.62E-06 3.24E-06 ALF 5.58E-10 5.58E-10 1.12E-09 RC 5.03E-09 5.03E-09 K

SEFC 1.86E-08 4.88E-08 9.53E-07 1.02E-06 SEF 3.32E-09 3.32E-09 SEC 1.13E-04 1.53E-06 1.14E44 SE 1.69E-06 4.32E-05 4.49E-05 SLFC 2.35E-05 1.19E-091.19E-09 9.84E-071.97E-071.17E471.31E-06 9.24E-07 3.49E-071.35E-06 4.55E-10 2.87E-05 p

SLF 8.39E-09 2.94E-11 3.80E-09 1.22E-08

.g SLC 3.30E-12 5.86E-09 2.48E-10 6.!!E-09 SL 3.92E-10 3.92E-10 TEFC 1.61E-09 1.61E-09 2.97E-06 5.94E-07 3.54E-07 3.96E-06 6.13E-08 2.59E-07 4.07E-06 2.81E-09 1.23E-05 TEF 1.73E-10 3.46E-11 2.07E-11 9.60E-10 2.37E-10 1.43E-09 TEC 1.16E-10 1.16E-10 5.07E-07 1.01E-07 6.05E-08 6.76E-07 9.69E-08 2.70E-08 6.95E-07 5.30E-06 7.47E-06 TE 2.34E-08 4.68E-09 2.79E-09 3.14E-08 3.16E-06 1.05E-09 3.21E-08 3.14E-09 3.26E-06 V2E 2.63E-07 2.63E-07 V2L 9.40E-09 9.40E-09 2.44E-06 9.40E-09 9.40E-09 2.48E-06 V

7.80E-07 7.8C(-07 TOTE 2.30E-061.90E-061.38E-04 2.70E-061.23E-081.23E-08 4.48E-06 8.97E-07 5.34E-07 5.98E-06 4.90E-05 6.37E-07 6.14E-06 7.80E-07 9.60E-07 5.31E-06

Model 3 - Model I with no maintenance unavailability contributions from CCWS and ESWS.

Case 7 - RHR under A0T2 and all others under A0T1.

Tahlo d-3R Plant Damage State ard Core Damage Frequencies for Model 3 Case 8 MODEL 3 CASE 8 ET1 ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ET11 ET12A ET13 ETi4 ET15 ET16 ET17 TOTAL 8.66E-07 EFC 6.36E-07 2.30E-07 EF 5.03E-09 EC 5.03E-09 2.06E-10 E

1.03E-10 1.03E-10 3.08E-06 ALFC 1.54E-06 1.54E-06 1.12E-09 ALF 5.58E-10 5.58E-10 5.03E-09 ALC 5.03E-09 AL SEFC 5.06E-08 4.88E-08 9.53E-07 1.05E-06 9.18E-09 9.18E-09 SEF SEC 1.13E-04 1.53E-06 1.14E-04 SE

!.69E-06 4.32E-05 4.45E-05 SLFC 1.84E-05 1.33E-09 1.33E-09 2.26E-06 4.52E-07 2.70E-07 3.01E-06 8.54E-07 3.49E-07 3.09E-06 4.55E-10 2.87E-05 Sif 7.20E-09 2.60E-10 1.85E-09 9.31E-09 E

SLC 3.30E-12 4.47E-09 2.4BE-10 4.72E-09 4.41E-11 4.41E-11 SL TEFC 4.44E-09 4.44E-09 8.58E-06 1.72E-06 1.02E-06 1.14E-05 1.20E-07 7.50E-07 1.18E-05 2.81E-09 3.54E-05 IEF 1.53E-09 3.06E-10 1.83E-10 3.57E-03 2.10E-09 7.68E-09 TEC 2.00E-10 2.00E-10 7.77E-07 1.56E-07 9.28E-08 1.04E-06 1.45E-07 4.14E-08 1.06E-06 8.11E-06 1.14E-05 TE 3.48E-08 6.93E-09 4.14E-09 4.64E-08 4.63E-06 1.61E-09 4.77E-08 4.89E-09 4.78E-06 V2E 2.63E-07 2.63E-07 V2L 9.40E-09 9.40E-09 6.41E-06 9.40E-09 9.40E-09 6.45E-06 7.80E-07 7.80E-07 V

TOTAL 2.19E-06 1.79E-06 1.33E-04 6.67E-06 1.54E-08 1.54E-08 1.17E-05 2.34E-06 1.39E- % 1.55E-05 5.05E-05 1.14E-06 1.60E-05 7.80E-07 9.65E-07 8.11E-0

Model 3 - Model I with no maintenance unavailability contributions from CCWS and ESWS.

Case 8 - AFWS under A0T2 and all others under A0T1.

l

4-50 Table 4.39 Comparison of Mean Core Damage Frequencies from One Unit Operation This Study ***

Case WCAP-10526 Model 0 Model 1 Model 2 Model 3 1

1.41(-4) 1.88(-4) 6.95(-4) 8.60(-5) 2.13(-4) 2 8.24(-4) 4.82(-3) 5.44(-4) 4.06(-4) 3 3.32(-4) 8.39(-4) 9.70(-5) 3.56(-4) 4 6.18(-4) 4.48(-3) 3.35(-4)

NA**

5 1.88(-4) 6.95(-4) 8.61(-5) 2.15(-4) 6 1.88(-4) 6.95(-4) 8.61(-5) 2.13(-4) 7 1.94(-4) 7.02(-4) 9.27(-5) 2.19(-4) 8 2.26(-4) 7.51(-4) 1.42(-4) 2.52(-4) 9 1.88(-4) 6.95(-4) 8.61(-5)

NA**

10*

1.67(-4) 2.52(-4) 1.11(-3) 1.32(-4) 2.32(-4)

Tr = 34 hours3.935185e-4 days 0.00944 hours 5.621693e-5 weeks 1.2937e-5 months for all systems.

- Not Applicable.

- - Model 0 - Model in WCAP-10526 with modifications in Section 4.2 except Event Tree 17 (loss of service water initiator) and with updated data in Tables 4.1 and 4.2.

Model 1 - Model 0 plus Event Tree 17 (loss of service water initiator).

Reference model in this study.

Model 2 - Model 1 with Pr(S -QA) = 0 where S -QA is the seal LOCA event 2

2 given loss of service water (Pr(S -QA) = 0.5 in other models as 2

in WCAP-10526).

Model 3 - Model I with no maintenance unavailability contributions from CCWS and ESWS.

l i

-~~

4-51 1

I I

I

-4 x10 Model 0 9.0 -

Case A0TI A072 1

All systems None 2

None AM systems

,I 8*0 3

All others DGs 4

All others ESWS 4

j 5

All others CHRS (CF and CS) l 6

All others Chg and $1 7

All others RHR 8

All others AFWS 7.0 9

All others CCWS i

.4 i

6.0 5.0 l

E w

4.0 ti 3

g m

D 3.0 o

f g

--. 8 7

mx 5,6,9 20 u

1 1.0 j

i e

i i

1 0

25 50 75 100 125 150 175 T (Hours) r f

Figure 4.2 Core Damage Frequency as a Function of T 's for 9 Cases r

in Model 0.

4-52 I

I I

I x10-9.0 I

Model 1 8.0 Case A0T1 A0T2

~

1 All systems None 2

None All systems

~

3 All others DGs 4

All others ESWS 7.0 5

All others CHRS (CF and CS) 6 All others Chg and $1 7

All others RHR 8

All others AFWS 9

All others CCWS 6.0 y

6

?

o3 5.0 e) 2 e

5 4-R 4

4,0 U

8 1

3.0 I

-2.0 -

8 1.0 -

/7 1-

~

5,6,9 I

I I

l l

l 0

25 50 75 100 125 150 175 i

T (H urs) r Figure 4.3 Core Damage Frequency as a Function of T 's for 9 Cases in Model 1.

r

l 4-53 I

i i

i

-4 x10 9.0 Model 2 Case A0T1.

A0T2 8.0 1

All systems None 2

None All systems 3

All others OGs 4

All others ESWS 5

All others CHRS (CF and CS) 7.0 6

All others Chg and SI 7

All others RHR 8

All others AFWS 9

All others CCWS g

6.0 w>-

ce

'2 -

S o$

5.0 E

Us a?

c2 4.0 w8 o

,4_

3.0 L

2.0

.8. 3

,[5,

'7 1.0

'1' 5,9 1

1 I

I i

l 0

25 50 75 100 125 150 175 T (H urs) r Figure 4.4 Core Damage Frequency as a Function of T 's for 9 Cases r

in Model 2.

4-54 i

i i

i I

I i

x10-4 9.0 flodel 3 Case A0T1 A0T2 8.0 1

All systems None 2

None All systems 3

All others OGs 4

All others ESWS 5

All others CHR$ (CF and CS) 7*0 6

All others Chg and $[

7 All others RHR 8

All others AFWS 9

All others CCWS 6.0 ce5 3

5

!3 5.0 5

J E

u 4

56 4.0

.L Q

g

.3_

3.0 J

-.8_

,7

/

I*

2.0

' fi.6

. u '

1.0 I

I i

1 1

1 0

25 50 75 100 125 150 175 i

T (H urs) r Figure 4.5 Core Damage Frequency as a Function of T 's for 7 cases in

-l r

Model 3.

i

5-1 5.

SUMMARY

AND CONCLUSIONS This study has reviewed the Westinghouse report WCAP-10526 which provided a methodology to be used in A0T problems, and specifically requested A0T ex-tensions for a number of systems in the Byron Generating Station, with an es-timate of the change in risk involved.

The methodology used in WCAP-10526 is the usual probabilistic risk assessment (PRA) technique characterized as the method of static fault trees.

Appendix A of this study reviews and compares other methods also applicable to the A0T problem with the static fault tree method and concludes that the stat-ic fault tree method is simple to use and generally conservative and thus can be used for many of the A0T problems.

The WCAP-10526 approach to the A0T problem (which is fundamentally a decision problem) of using probabilistic analyses is sound and logically correct.

In this respect, the approach in WCAP-10526 is a step in the right direction and in general, the effort in WCAP-10526 is commendable.

As pointed out, however, the details of the approach can be substantially improved.

The limitations and issues in WCAP-10526 arise mostly from the support state decomposition approach which is a particular static fault tree method

chosen and implemented in WCAP-10526, and from the use of mean value (of the prior distribution) of mean time to repair for repair duration in the component unavailability expression.

These are recapitulated as the following:

(1)

Incompleteness of initiators--loss of service water and loss of a dc bus.

(2)

Incomplete support state development in the support state decomposi-tion approach.

(3) No explicit treatment of A0Ts due to the use of mean time to repair (MTTR) for repair duration Tr in Eq. (1) of Section 3.1.

(4) Use of a single Tr for all systems.

(5) Simultaneous maintenance between systems.

(6) Asymmetric modeling of redundant trains.

(7) No consideration of battery depletion in station blackout sequences.

To obtain an independent estimate of the change in risk involved in the Byron proposal, this study modified the models in WCAP-10526 incorporating the issues and improving the limitations above by employing the fault tree linking approach and interpolation between two bounding A0Ts.

The fault tree linking approach provides holistic information for the top event (e.g., core damage) and a basic mathematical model which facilitates sensitivity studies in a later phase, e.g., through importance analyses.

In particular, the use of pairwise importance measures (described in Appendix B) provides valuable in-sights in evaluation of the technical specifications.

The approach of inter-polating between two bounding Tr's is useful in providing not only an upper bound on core damage frequency allowed in the technical specifications, but also appropriate core damage frequency which is only slightly conservative for

i 5-2 t

a more definitive repair duration Tr to be determined later when more infor-mation becomes available or a policy decision is made.

The reevaluation in this study focused on the core damage frequency from f

one unit operation only, since most of the shared systems between Unit 1 and t

Unit 2, in particular, the Essential Service Water System and the Component j

Cooling Water System, are not completely in place.

As summarized in Table 4.39 and Figures 4.2 through 4.5, the difference between WCAP-10526 and Model 1 (basic model of this study) is considered significant.

This is attributed to the loss of service water initiator included in Model 1, coupled with the 1

induced seal LOCA given loss of service water system. Note that the Essential 1

Service Water System at Byron consists of two trains with a single pump in each train and that the probability of a seal LOCA given loss of service water system was nominally assumed to be 0.5.

It is observed in Model 2 where the probability of a seal.LOCA given loss of service water system is assumed to be zero instead of nominal 0.5, the core damage frequencies become substantially i

l smaller in comparison with those of Model 1.

There have been discussions that normal leak rate from heated seals (even without the seal 0-ring being failed) i would be -20 gpm per pump which would correspond to -20 hours of core uncovery time.

Thus, it may be argued that the nominal value of 0.5 for the probability of a seal LOCA given loss of service water may be nonconservative since the recovery time of the last service water system could be longer than

{

the core uncovery time.

4 The results in this study on importance rankings of individual systems j

with regard to A0Ts, however, generally agree with the conclusion in WCAP-10526 that the largest impact on plant risk from changes in the A0Ts comes l

from the Essential Service Water System and the diesel generators.

(Note, I

however, that individual system-level rankings are not given in WCAP-10526.)

l Similarly to the results of the basic model, the results of several sensitiv-ity models also indicate the same trends on the individual system rankings:

l the Essential Service Water System and the diesel generators are the first two i

dominant contributors to the increments in core damage frequency due to the t

i A0T extensions and next in importance is the Auxiliary Feedwater System. The I

effects of the containment heat removal systems (Containment Spray System and j

Containment Fan Coolers) and the ECCS (Charging pumps, Safety Injection pumps, and RHR pumps) are considered to be small.

However, in Model 2 which assumes that there is no induced seal LOCA from loss of service water, the effect of j

the diesel generators is also considered to be small (see Figure 4.4).

This i

is because the station blackout scenarios become less important for the induced seal LOCA in this model.

The results of pairwise importance analysis indicate that contributions of simultaneous maintenance of two components existing in the model are j

small. This reflects the fact that many of the potential simultaneous mainte-i nances were already eliminated from. the model because of the support system l

operability requirement in technical specifications.

l Although the effect of extended A0Ts of the containment heat removal sys-i j

tems on core damage frequency is negligible, their effect on health risks j

could be significant, since the states of the containment heat removal systems affect release categories directy.

It is observed from Tables 4.14 and 4.18 i

that extended A0Ts of the containment heat removal systems increase..slightly l

the plant damage states SLF (from 8.85.x 10 9 to 1.19 x 10 8 events / reactor

,-,.-e--.

.--,--~,-,-.w-sa-ie,-,,-....v.,c-y eva,-s-,-.w-e-.-.--e.m e w.4

.e,m-

,,-,w.-,m.--.m

_-.,.._4

.,,,w--,--o-gr-yevs-

'g*v-~--**"-"

5-3 year) and SLC (from 3.37 x 10-9 to 2.34 x 10-8 events / reactor year).

SLF affects the latent cancer fatalities primarily through release categories 2R and 2 (see Tables 4A-4 and 48-6 in WCAP-10526).

SLC affects the latent cancer fatalities primarily through release categories SR, Z-5, and Z-3, and also the early fatalities through release categories Z-3 and Z-5 (see Tables 4A-4, 4B-3, and 4B-6 in WCAP-10526).

Therefore, it is ascertained that practically no increase in core damage frequency with, nonetheless, slight increases in plant damage states SLF and SLC will result in nonnegligible increases in health risks.

However, the available PRA results of several plants, e.g.,

Zion and Limerick which are sited in more populated areas than Byron, indicate that the core damage frequency is the limiting constraint to the proposed numerical guidelines of the NRC safety goals and that the health risks are well below the safety goals.

Thus, health risks from Byron Unit 1 are expected to be within the safety goals in spite of the results that indicate the core damage frequency is above the proposed numerical guideline.

l A-1 APPENDIX A SURVEY OF APPLICABLE METHODS Technical specifications (TS) in a nuclear power plant are specific re-quirements on its day-to-day operation, designed to protect public health and safety.

Two primary aspects of the TS are (1) limiting conditions of opera-tion (LC0) with allowed outage times (A0T's) and (2) surveillance testing in-tervals (STI's). The promulgation of TS is an important element of the exist-ing regulatory framework which governs licensing and operation of nuclear power plants.

In recent years, there has been growing interest in the nuclear community in reexamining the TS.

One of the reasons is that a sign 1ficant portion of reactor downtime (plant unavailability) is attributable to the strict TS.

Existing TS were derived from engineering judgement based on deterministic re-view; they were not directly risk-based, and their efficacy in enhancing pub-lic safety is difficult to establish.

In the debate regarding the merits of relaxing the TS, the burden is however, primarily on the owners and operators of the plants to prove that the existing TS are "too strict." A difficulty in doing this arises from the fact that the decision makers (owners of the plants or regulators as appropriate) and the public are not cognizant of the lower level measures, e.g., unavailability of certain components or systems, which are affected by the TS directly.

In other words, the lower level measures do not convey direct meaning to them.

In contrast, higher level measures, e.g.,

fatalities from the accidents, property damage, cost, and core damage frequen-cy, would have more direct meaning to them.

Thus, decisions based on higher level measures would be understood and accepted more easily than those based on lower level measures.

Another difficulty comes from lack of a decision

" standard (criteria) setting" or regulatiop:) either framework in nuclear 2

Standard-setting categorizes options decision-making.t

" case-by-case" (e.g., two testing procedures, existing and proposed) as " acceptable or not acceptable" whereas decision-making procedures attempt to order the available options according to their " attractiveness" and choose the mqs attractive The NRC's proposed safety goals and numerical guidelinest provide an one.

example of standard-setting at a higher level.

Ref. 4 develops a method for setting reliability criteria at a lower level which are derived consistently from higher level criteria.

The higher level measures which should be the attributes in risk-based decisions, however, are not directly " measurable."

Thus, they must be evalu-ated by mathematical (deterministic and/or probabilistic) methods using var-ious models.

Here arises the importance of the chosen methods and models since the final decision would depend on them.

The outcome of a decision based on a particular method could be different from that of a decision which was based on another method.

This is particularly relevant to the TS problem since various complex characteristics are inherent in the TS problem. Some of the characteristics and issues that should be addressed in the TS problem are outlined in Ref. 5.

In brief, allowed outage times (A0T's) and surveillance testing intervals (STI's) introduce into the TS problem a high degree of sto-chastic dependency among components and systems including the following:

+

A-2 l

t (1) At test and repair times, the component exhibits discontinuities in its unavailability.

(2) The TS require that when one train becomes inoperable due to test or repair, the other redundant train including all support equiment be operable.

This requirement is usually satisfied by staggered c

schedules for test and repair.

(3) The TS require the reactor be shut down if test or repair is not completed within a given A0T.

(4) During test and repairs in most of the systems, the logic (success criterion) of the system changes.

(5) For some systems, when a particular component or train is tested or repaired, the system is reconfigured involving a set of other compo-4 j

nents in the same system and/or in other systems in order to accom-plish the test and repair or to improve unavailability of the system during the test and repair.

(6) Frequent test and challenge of the component may degrade the compo-nent.

i (7) Test and repair may introduce human errors into the state of the j

component affecting the component unavailability.

i (8) Human errors during test and repair may affect the state of the sys-i tem resulting in shutdown of the plant.

(9) A0T of a particular component may depend: on states of other compo-l nents.

(10) The TS problem increases desirability of modeling multiple states for components and system.

l (11) Challenge rate is an integral element in evaluating effectiveness of one or a set of standby systems.

?

The available methods applicable to the TS problem dealing with the as-pects listed above invariably employ some kind of approximations.

The degree 1

of approximation varies according to the methods. Some approximations.are in--

l trinsic to particular methods because of fundamental assumptions in the meth-ods while some approximations are made for numerical and computational effi-l ciency.

The methods reviewed and tested in this study (using a sample problem) j are limited to those whose computer code (i plementations are available.

f These (1) "stp$jc" fault tree approach, 01 (2

unav analysis.t8)) " time-dependent"(9-ll)ailabil--

i are:

1 ity analysis,l') and (3) Markov Other methods poten-tially applicable to the TS problem are not reviewed here since they are still under development and computer codes implementing the methods are not availa-l ble to the authors of this report.

i

l A-3 l

A.1 METHODS The three methods tested by using a sample problem are the following (Detailed descriptions are available in the references):

Static Fault Tree Approach (6,12)

Time-Dependent Unavailability Analysis (7,13,14)

Markov Analysis (8,15,16,17,18)

A.2 SAMPLE PROBLEM The sample problem devised in this study is to calculate core damage fre-quency from an accident sequence using the three methods in Section A.I.

The accident sequence consists of an initiator and failures of two frontline sys-tems and a support system.

The systems and failure data are abstracted from the Byron plant. However, the sequence is constructed only for the purpose of comparing the methods and thus does not necessarily represent any accident sequence appropriate to the Byron plant per se.

Figure A.1 represents the sample problem configuration in a reliability block diagram.

Each block is a "supercomponent" consisting of several compo-nents in series.

For example, Block 1 is composed of a pump and several valves associated with the pump.

Frontline system 1 consists of Blocks 1, 2 and 3.

Similarly, frontline system 2 consists of Blocks 4, 5 and 6.

The suc-cess criterion is 1-out-of-2 for both frontline systems.

Blocks 7 and 8 con-stitute a support system.

The problem is characterized by the following:

1.

The accident sequence is defined as TF Ft 2 where T is the initiating are the failure events of the frontline system 1 event, and Fi and F2 and the frontline system 2, respectively.

2.

The two trains (blocks) in each system follow staggered testing schedules.

3.

The testing schedules are consistent between the frontlina systems and the support system.

For example, test of Block 1 is also stag-gered with test of Block 8.

4.

The suction source (Block 3) for frontline system 1 is reconfigured during test and repair.

That is, when Block 3 is under test or re-pair, the support system whose primary function is cooling of pumps in Blocks 1, 2, 4 and 5, is also used, if it is available, as the suction source in lieu of Block 3.

5.

Test time of the suction source (Block 6) for frontline system 2 is negligibly short.

If test finds Block 6 is unavailable, the reactor is shut down immediately.

6.

If repair of each block is not completed within an A0T, the reactor is shut down.

A-4 7.

Each block is not available during its test.

8.

Test and repair introduce human errors into the state of the block affecting its unavailability.

A.3 RESULTS AND DISCUSSIONS Tables A.1 and A.2 summarize the failure data and parameters associated with testing schedules used SETS code.l19)he calculations.

ip t The static fault tree was quantified by th For time-dependent unavailability analy-III(14) sis, FRANTIC was used.

For Markov analysis, the version of STAGEN and MARELA developed in Ref. 17 was modified for the sample problem.

Table A.3 and Figure A.2 show the results of sensitivity calculations ob-tained by varying A0Ts.

In the case of unavailability of the combined systems in the sequence, only time-averaged values (for 360 days) are included.

FRANTIC III and STAGEN/MARELA calculate unavailabilities as functions of time in detail.

In addition, STAGEN/MARELA also calculates core damage probabili-ties and reactor shutdown probabilities as functions of time directly.

In the case of Markov analysis, each block was modeled to be in three states, i.e.,

(1) operating, (2) failed, and (3) in repair, and it was assumed that, once the reactor makes a transition to the reactor shutdown. state (without core i

damage), it is completely renewed and transferred to a system state in which every block is operable following an exponential distribution with mean time of 48 hours5.555556e-4 days 0.0133 hours 7.936508e-5 weeks 1.8264e-5 months .

The results for static fault tree approach and the Markov analysis in-clude reconfiguration of Block 3 during test and repair.

The FRANTIC results obtained here, however, do not represent the reconfiguration exactly.

Two sets of results tre instead provided for FRANTIC III calculations: one for no reconfiguation of Block 3 during test and repair, and another for zero test and repair duration (equivalent to no unavailability during test and repair) of Block 3.

Incorporating reconfiguration correctly in the FRANTIC calcula-tion will entail generating new minimal cut sets by taking into account the resulting new system structure and related human failures.

The new minimal cut sets should then be used only during test and repair by FRANTIC.

There may be situations, depending upon the problem and data, in which the rare-event approximation usually employed in current PRAs will not be accurate enough (on the conservative side) if it is used also in the FRANTIC calcula-tion, especially for the test and repair phase.

Therefore, in the FRANTIC calcu]ations for the sample problem in this study, the min cut upper boundt20i was used to reduce over-estimation in the unavailability.

It is observed from Table A.3. and Figure A.2 that for the range of A0T's considered, Markov analysis gives smaller unavailabilities and core damage probabilities than the other two methods.

If reconfiguration is not consid-ered in the FRANTIC calculation, FRANTIC results are the most conservative.

However, if zero test and repair duration is assumed in the FRANTIC calcula-tion, static fault tree results become the most conservative.

The static fault tree results are always conservative compared to the Markov analysis re-sults.

The differences in core damage frequency and in unavailability (as far as time-averaged unavailability is concerned) between the static fault tree and

I i

A-5 I

FRANTIC results are not considered significant while the corresponding differ-ences fetween the static fault tree and Markov results are considered substan-tial. This is because the Markov analysis models stochastic' dependency better than the other two methods and multiple states in the Markov analysis allow more realistic modeling of cenponent and system dynam.ic behavior, including renewal aspects of system challenges and inter-system state transitions.

FRANTIC (and Markov analysis) of course provides noi only time-averaged unavailabilities but also detailed unavailabilities as %nctions of time which cannot be obtained by the static fault tree approach.

It is also noted from Figure A.2 that all curves exhibit convexity as ex-pected (only degrees of the convexity are different among the curves).

A.4 CONCLUSIONS Although the sample problem used is not a detailed model, it 'contains most of the important and essential characteristics that should be addressed in the TS problem.

Thus, the trends observed in the results are expected to be indicative of the real situation.

The results obtained in this section using three methods give useful in-sights and lend confidence to the conclusion that the static fault tree method is simple to use and generally conservative in comparison with the other two methods and thus can be used for the A0T problem when the quantified higher level measures, e.g., core damage frequency and health risks, turn out to be clearly less than the criteria (e.g., the safety goals or other agreed-upon safety criteria).

However, when the higher level measures corresponding to the proposed A0Ts are in the range of the criteria, the Markov analysis or the time-dependent unavailability analysis would be attractive to owners of the plants who bear the burden of proof in A0T relaxation.

The weak convexity of the results suggests a way to perform sensitivity studies with regard to A0Ts.

They can be done simply by linearly interpolat-ing two results obtained from small and large A0Ts, e.g.,

19 hours2.199074e-4 days 0.00528 hours 3.141534e-5 weeks 7.2295e-6 months and 168 hours0.00194 days 0.0467 hours 2.777778e-4 weeks 6.3924e-5 months .

These two A0Ts are taken as the bounding A0Ts described in Section 4.1.2.

f b

4

A-6 1

7. _ _ _

- - _ _ _.n. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _,

e t

3 l

8 8

2 i

7

' t t

'r- '

i l

I I

8

-- 2 4

1 6

1 5

Figure A.1 Block configuration of a sample problem.

l i

l A-7 Table A.1 Failure Data Used in the Sample Problem Independent Common Cause Test Human Error Failure Rate Failure Rate

Test Human Error Not Detecting Block (per hour)

(per hour)

Causing Failure Failure s

1 1.66(-5) 5.29(-7) 1.00(-3) 1.00(-3) l 2

7.31(-5) 1.00(-3) 1.00(-3) l 3

3.87(-7) 1.00(-3) 1.00(-3) 4 1.03(-6) 3.50(-7)

_1.00(-3) 1.00(-3) 5 1.03(-6) 1.00(-3) 1.00(-3) l 6

1.85(-7) 1.00(-3) 1.00(-3) 7 2.40(-5) 3.29(-8) 1.00(-3) 1.00(-3) 8 2.40(-5) 1.00(-3) 1.00(-3)

CCoanon cause failure rates between blocks 1 and 2, blocks 4 and 5, and blocks 7 and 8, respectively.

i Table A.2 Testing Schedules Assumed in the Sample Problem Mean time Mean Time Starting Test to Test To Repair Test Time Interval Block (hours)

(hours)

(days)

(days) 1 2

19 15-30 2

2 19 30 30 3

2 19 15 15 4

2

-19 15 90 5

2 19 60 90 6

0 0

15 45 7

2 19 15 30 8

2 19 30 30 i

s 93

A-8 Table A.3 Average Unavailability and Core Damage Probability

)

at One Year Using 3 Initiators Per Year Average Unavailability Core Damage Probability Static Static A0T (Hrs) Fault Tree FRANTIC Markov Fault Tree FRANTIC Markov 19 1.64(-4) 1.68(-4)* 1.12(-4) 4.92(-4) 5.04(-4)* 3.31(-4) 1.43(-4)#

4.29(-4)#

34 1.70(-4) 1.74(-4) 1.18(-4) 5.10(-4) 5.22(-4) 3.47(-4) 1.50(-4) 4.50(-4) 72 1.86(-4) 1.92(-4) 1.33(-4) 5.58(-4) 5.76(-4) 3.94(-4) 1.67(-4) 5.01(-4) 168 2.26(-4) 2.42(-4) 1.79(-4) 6.78(-4) 7.26(-4) 5.30(-4) 2.18(-4) 6.54(-4)

No reconfiguration of Block 3 during test and repair.

Zero test and repair time (duration) for Block 3.

f l

x 10-4 A

Static Fault Tree FRANTIC *#

8 8

FRANTIC C

D Narkov 7

+

Core Damage Frequency 6

5

8. 7.'7+

A' N

c e/.

>6 4

/'

l i

0~.

ta

.3

,. /

J Average 2

s Unavailability CD 8 I

A' so --

EO c-5#

o.

y 0

20 40 60 80 100 120 140 160 A0T (flours)

Figure A.2 Average Unavailability and Core Damage Frequency as functions of A0T.

B-1 APPENDIX B PAIR IMPORTANCE MEASURES IN SYSTEMS ANALYSIS Importance measures in systems unreliability (or unavailability) analysis provide useful information that can be used to identify components that are critical with regard to the availability or reliability of a system.

Various importance measures known in the reliability literature (28) are defined for a single component.

This appendix extends earlier work to define importance measures for a pair of components of the system (accident sequence, core dam-age frequency, or health risks as appropriate), and illustrates the usefulness of these pairwise importarce measures in nuclear power plants. These measures are immediately applicable to risk-based evaluation of the technical specifi-cations; in addition, pairwise importances could play a significant role in systems interaction studies by highlighting pairs of events between which a coupling would be significant if it existed.

Traditional single-event importance measures reflect time-averaged prop-erties of the system which have been modeled by fault trees; for example, a particular component will have a certain importance based on time-averaged un-availabilities for other components.

However, the ranking of components by such a measure may shift considerably if it is known that another component is unavailable.

The importance of the pair becomes relevant if one is trying to assess the advisability of permitting simultaneous maintenance on particular pairs of components, or in adjusting surveillance requirements for one compo-nent given that another is down for maintenance, or generally in knowing whether the top event probability is sensitive to a potential statistical coupling between a particular pair of events.

Let us assume that the top event is given in terms of minimal cut sets.

Let P(X

,...,X ) represent the probability of the top event, expressed as a i

n probabilities X,X

,...,X

, where Xi is the function of the n basic event i 2 n

probability of the basic event i.

Then we can write, for any pair of events (1,j),

P(X,X

,...,X ) = Ajj + XjB j + XjCjj + XjXjDjj (1) 1 2 n

i where Ajj is the sum of terms independent of Xj and Xj, B j is the sum of coefficients of Xj, over terms which do not i

contain Xj, i

over terms which do not C j is the sum of coefficients of Xj, contain Xj, over terms containing Djj is the sum of coefficients of Xj Xj Xj Xj.

B-2 It is obvious from Eq. (1) that aP/a(XjXj) = D j.

i Thus, Djj is analogous to the single-event Birnbaum importance, but defined for a pair of events.

Similarly, one can consider the quantity XjXjDjj/P which may be called a pairwise Fussell-Vesely importance, but reflects only the overlap contribution from the pair; it is the importance of terms contain-ing both. The corresponding importance of terms containing either or both is (XjBjj + XjCjj + XjXjDjj)/P.

All these quantities are potentially valuable in examining the issues mention-ed above.

For even moderately large models, there are many possible combinations of pairs to consider and a large Boolean expression to quantify.

Reasonably efficient means for generating and ranking these quantities have been comput-erized. The current version of the code developed for the pairwise importance measures requires, as an input, whichcanbegeneratedbytheSETScode.\\g9a fact rgd form of the Boolean expression 1

Recent work (30) developing methodology for evaluation of technical spe-cifications has reaffirmed the need to examine combinations of events which contribute to risk when a selected component is unavailable.

The goal is to minimize the risk associated with maintenance unavailability by identifying human errors and additional component failures that could combine with the maintenance act to contribute to risk, and then ensuring that the probability of these is minimized. The present method is an efficient way to identify the most important combinations.

i C-1 APPENDIX C DOMINANT CUT SETS AND PAIRWISE IMPORTANCE OUTPUTS j

C-2 Table C.1 Dominant Cut Sets of Loss of Service Water Initiator for Case 1 (Total = 9.47 x 10 '+/ry)

TERM PROB.

-Nt_JMBER OF' TERM

~~~"-'

~ " -

_ ___...IF-ET17 =

1 3.5336E-04 --- IPSX01PBFR

IP@X01PAM + ~ " - ' ' ~ -

2 3iS336E-04--

IPSX01PAFR

1P@X01PBM'+

.5 2'.'8422E-05 IPSx01PBFR'

1P!X01P AFS + ~ -'~-'-

4 2sB422E-05 1PSX01PAFR *-1P@X01P8FS i- -

5 2.'3557E-05 ISSX01FRQ *-1PSX01PAM"+

1 6

2.3557E-085~

ISSX01F AQ

1PSX01P8M +~ ~~-

7 1g4980E-05 1PSX01PBFR-*-1SSX01FAM-+--

'8-1~44980E-05 I PSX 01P AFR * ' 1SSX01F8M ~*~'-~~~

9 1;16 0 0E-05 -- FSXO 3 CEFR *- FSX 0.3 SWHE ~+ --~~ ---

10---1.16 0 0 E- 0 5 FSX03CBFR *- FSX0.3SWHE + -- -

11 li1600E-05--

FSXO3CFFR's FSXO3SWHE +

~

~ ~ 1.~16 0 0 E-05 ----- FSX O 3 C AFR

FSx 0.3 SWHE +

' - ~

1-3 8.5147E-06 1PSX01PBFR * -1SSX01FAOD i----

14 8s5147E-06 2 PSX 01 P A FR~ *

15@X 01 FBQD' '+~~~-

15 6.5380E-06..

BUS 131ZD *"FSX035WHE i

- 6.538 0E RUS132ZD"*-FSX03SWHE-5 17-~ 2.0734E-06 1 MVS X 0 01 BC" * "1 P!X 01P A M ' *'

~18

2. 0734E-0C --"1 XVSX 143BC-

IP@X01 P AM + -----

19-2.0734E-06 -- -0XySX13BBC e - 1P@X01PAM + --

-~~'~~ 20-2.0734E 1MySX001AC

1P@X01PBM +

C-3 Table C.2 Dominant Cut Sets of Loss of Service Water Initiator for Case 2 (Total = 7.21 x 10-3/ry) f TERM PROB.

NUMBER OF TERM

____ - rF-ET17 = ----

1 -3.1244E-0 3 ---1 PSX01PBFR ~ * ' 1P!X 01P AM 2

371244 E-03~~

1 PSX 01 P AFR-'s" 1P!X 01 PBM * ~~~"-

3 2.0830E-04 ISSX01FBQ

IPSXojpAu + - -

4 2.0830E-04 ISSX01FAQ-*-1PSX01 P B M "+ ' ----

5 1".3245E-04 1PSX01PBFR"*-1SSX01FAM~* -

6 IT3245E IPSX01PAFR *~1SSX01FSM

7 248422E-05 I PSXO1PBFR **- 1P!X01P AFS-~I-

-" 8 2.8422E-05

- 1 PS X 01 P A F R "* "1 P @X 01 P B F S"'+'--

9 1.8333E-05 ---1*VSX001BC T-1P@X01PAM

10---1.8333E-05

-1XVSX143BC-* 1Ppxolp AM +-

11 1.8333E-05 D X VSX 13 8 B C' * - IP@ X 01 P A M - *---

i 12 ----1~.8333E -~ 1MVSX 0 01 AC

1P@X 01PBM * - -~

13 1sB333E-05 IXVSX143AC

IP!X01PBM *---

14' i.8333E'05

-0XVSX138AC-*-1P!X01PBM"*'--

15"-

171600E-05 FSXO3CBFR *-FSX0,35WHE +

1 16 171600E-05 FSX03CAFR * -FSX03SWHE ~+

17

-171600E-05

- F S X O 3 CFFR * * '*F S X 0.3 SWHE--i 18 - l41600E-05

- FSX O3 CEFR

FSX 0,3 SWHE +-- "' 8. 83 01E-06--- 1 SSX01FBQ

1SSX01FAM +

20 8;8301E ISSX01FAQ *-'1SSX01 F B M "+

l

C-4 Table C.3 Dominant Cut Sets of Core Damage for Model 1 - Case 1 (Total - 6.95 x 10-4/ry)

TERM PROB.

NUNBER OF TERM CORED =

1 4.7350E-04 S2-04

IF-ET17 +

2 2.2065E-05 AF01PBFS

IF-ET17 +

3 9.8434E-06 CCESW1

S2-0A

IF-ET14 +

4 9.5800E-06 CCESW1

IF-ET!!

S2-GA +

5 7.9296E-06 IF-ET3

PRH0!PACFS +

6 7.1850E-06 CCESW1

IF-ET7

S2-CA +

7 6.3182E-06 LOSPNONREC

DGANONREC

DGAFR

DGBNONREC

DGBFR

IF-ET12A 8 6.1081E-06 AFO!PBFR

IF-ET17 +

9 3.6147E-06 LDSPNONREC

DGAM e DGbNONREC

DGBFR

IF-ET12A

S2-04

E120-2 +

10 3.6147E-06 LOSPNONREC

D6ANONREC

DGAFR

DGBM e IF-ET12A

S2-04

E120-2 11 3.5400E-06' IF-ET3

HpRECIRCDP +

12 3.2102E-06 LOSPNONREC

D6ANONREC

DGAFR

D6BNONREC

DGBFS

I 13 3.2102E-06 LOSPNONREC

D6ANONREC

DGAFS

DGBNONEC

DGBFR

IF-E 14 3.1023E-06 LDSPNONREC

D6ANONREC

D6BNONREC

CCAC

IF-ET12A

S2-t 15 2.2671E-06 PAF0!PBM

IF-ET17 +

16 2.2199E-06 LDSPNONREC

D6ANONREC

D6AFR

D6BNONREC

DGBFR

I 17 2.2105E-06 1PSX0!PAM e ISSIO!FBQ

S2-04

IF-ET14 +

18 2.2105E-06 ISSX01FAQ

IPSIO!PBM e S2-QA

IF-ET14 +

19 2.1514E-06 1PSX0lPAM e ISSX01FBQ

IF-ET11

S2-0A +

20 2.1514E-06 ISSX0!FAQ

IPCI0IPBM e IF-ETil

S2-0A +

21 1.8366E-06 LOSPNONREC

DGAM e DGBh0NREC e DGBFS

IF-ET!2A

S2-DA

E120-2

l C-5 Table C.3 (Continued) 22 1.8366E-06 LOSPNONREC

DBAh0NREC

D6AFS

D6BM e IF-ET12A

S2-04

E120-2 +

23 1.6461E-06 IF-ET3

MVCC9412CC +

24 1.6461E-06 IF-ET3

MVSIB811CC +

25 1.6311E-06 LDSPNONREC

DGANONREC

DBAFS

D6BNONREC

D6BFS

IF-ET12A

S2-04

E120-2 +

4 26 1.6135E-06 1PSX01PAM

ISSX01FBQ

IF-ET7

S2-GA +

27 1.6135E-06 ISSX01FAQ

iPSIO!PBM

IF-ET7

S2 @ +

28 1.4370E-06 CCESWU1

IF-ET8

S2-GA +

29 1.4100E-06 IF-ETI

LPRECIRCOP +

30 1.4100E-06 LPRECIRCOP

IF-ET2 +

31 1.3637E-06 A0VSX178D e IF-ET17 +

32 1.3637E-06 ADVSX173D

IF-ET17 +

33 1.2700E-06 LOSPNONREC

DGAM e DGENONREC e D6BFR

IF-ET12A

E120-1

S2-04 +

34 1.2700E-06 LCSPNONREC

DGANONREC

DGAFR

DGEM

IF-ETIEA

E120-1

S2-OR +

35 1.1279E-06 LOSPNONREC e D6m 0NREC

D6AFR

DGBNONREC

D6BFS

IF-ET12A

E120-1

S2-GA +

36 1.1279E-06 LDSPNONREC

DGMONREC e DC#S

DGENONREC e DGBFR

IF-ET12A

E120-1

S2-GA +

i 37 1.0900E-06 LOSPNONREC

D6ANONREC

D6BNONREC

CCAC

IF-ET12A

E120-1

S2-GA +

38 1.0541E-06 LOSPNONREC

DGBNONREC e D6BFR

1PSX01PAM e IF-ET12A

S2-DA

E120-2 +

39 1.0541E-06 LOSPNONREC

D6ANONREC e D6AFR

1PSIO1PEM e IF-ET12A

S2-GA

E120-2 +

40 9.5200E-07 IF-ET16

PL-1

TT2-2 +

41 8.5741E-07 CCESW1

IF-ET9

S2-GA +

42 8.3287E-07 AFWSCCFAIL

IF-ET4

OP8-20D +

43 8.1414E-07 AFWSCCFAIL

DP2-0D e IF-ET14 +

44 8.1414E-07 AFWSCCFAIL

OPI-0D

IF-ET14 +

45 7.9235E-07 AFWSCCFAIL

OP2-0D

IF-ET11 +

C-6 Table C.4 Dominant Cut Sets of Core Damage for Model 1 - Case 2 (Total - 4.82 x 10-3/ry)

TERM PROB.

NUf6ER OF TERM CORED =

1 3.6050E-03 S2-04 e IF-ET17 +

2 1.6799E-04 AF0!PSFS e IF-ET17 +

3 1.5264E-04 PAF0!PBM e IF-ET17 +

4 4.6504E-05 AFO!PBFR e IF-ET17 +

5 3.1%1E-05 LOSPNONREC e DGAM e D6BNONREC e DGBFR e IF-ET12A

S2-GA e E120-6 3.1961E-05 LOSPNONREC

DGANONREC e D6AFR

D6BM e IF-ET12A e S2-04 e E12 7 1.9555E-05 IPSIO!PAM e ISSIO!FBQ

S2-04 e IF-ET14 +

8 1.9555E-05 ISSX01FAQ e IPSIO!PBM e S2-GA e IF-ET14 +

9 1.9032E-05 IPSIO!PAM e ISSX01FBQ s IF-ETl! e S2-CA +

10 1.9032E-05 ISSIO!FAQ e IPSX0!PBM e IF-ET!! e S2-GA +

11 1.6239E-05 LOSPNONREC e DGAM e DGBNONREC e DGBFS

IF-ET12A e S2-0A e 12 1.6239E-05 LOSPNONREC e D6ANONREC

D6AFS

D6BM e IF-ET!!A e S2-GA e 13 1.4274E-05 1PSX0!PAM e ISSX01FB0

IF-ET7

S2-0A +

14 1.4274E-05 ISSIO!FAQ e IPSIO!PBM e IF-Ei.

S2-GA +

15 1.1230E-05 LOSPNONREC e DGAM e DGBNONREC 5 D6BFR

IF-ET12A e E120 16 1.1230E-05 LOSPNONREC e D6ANONREC e D6AFR e D6BN e IF-ET124

E120-1 17 1.0382E-05 ADVSX1780 e IF-ET17 +

18 1.0382E-05 A0VSX173D e IF-ET17 +

19 9.8434E-06 CCESW1 e S2-0A e IF-ET14 +

20 9.5800E-06 CCESW1 e IF-ETl! e S2-QA +

21 9.3249E-06 LOSPNONREC e DGBNONREC e DGBFR e 1PSX01PAM e IF-ET

l l

C-7

\\

I Table C.4 (Continued) 22 9.3249E-06 LOSPNONREC

D6ANONREC

DGAFR

1PSX01PBM e IF-ET!2A

S2-DA

E120-2 +

23 7.9296E-06 IF-ET3

PRH01PACFS +

24 7.1850E-06 CCESi4J1

IF-ET7

S2-GA +

25 6.9030E-06 1PSX0!PAM e FSX03CFFR

S2-GA

IF-ET14 +

26 6.9030E-06 1PSX01PAM e FSX03CEFR

S2-DA

IF-ET14 +

27 6.9030E-06 FSXO3CBFR

1PSX01PBM e S2-DA

IF-ET14 +

28 6.9030E-06 FSIO3CAFR

1PSX0!PBM e S2-DA

IF-ET14 +

29 6.7183E-06 1PSIO1PAM

FSX03CFFR

IF-ET11

S2-0A +

30 6.7183E-06 1PSX01PAM e FSX03CEFR

IF-ET11

S2-QA +

31 6.7183E-06 FSX03CBFR

1PSX01PBM e IF-ET11

S2-0A +

32 6.7183E-06 FSX03CAFR * !PSIO!PBM

IF-ET!!

S2-DA +

33 6.3182E-06 LOSPNONREC

D6ANONREC

DGAFR

D6BNONREC

D6BFR

IF-ET12A

S2-0A

E120-2 +

34 5.7057E-06 LOSPNONREC

D6AM e D6BNONREC

D6BFS

IF-ET12A

E120-1

S2-04 +

35 5.7057EH)6 LOSPNONREC

D6ANONREC

DGAFS

CGBM

IF-ET12A

E120-1

S2-04 +

36 5.0387E-06 1PSX0!PAM

FSX03CFFR

IF-ET7

S2-GA +

37 5.0387E-06 IPSX01PAM e FSX03CEFR

IF-ET7

S2-GA +

38 5.0387E-06 FSIO3CBFR

1PSX0!PBM e IF-ET7

S2-DA +

i 39 5.0387E-06 FSX03CAFR

IPSX01PBM

IF-ET7

S2-0A +

40 4.8472E-06 ISSX01FAQ

FSX03CFM

S2-0A

IF-ET14 +

41 4.8472E-06 ISSX01FAQ

FSX03CEM e S2-0A

IF-ET14 +

42 4.8472E-06 FSX03CBM e ISSIO!FB0

S2-GA

IF-ET14 +

43 4.8472E-06 FSX03 CAM e 1SSX01FBQ

S2-04

IF-ET14 +

44, 4.7380E-06 LOSPNONREC

DGBNONREC e DSBFS

1PSX01PAM e IF-ET!2A

S2-0A

E120-2 +

45 4.7380E-06 LDSPNONREC

DGANONREC

DGAFS

iPSX01PBY

IF-ET12A

S2-0A

E120-2 +

C-8 Table C.5 Dominant Cut Sets of Core Damage for Model 2 - Case 1 (Total - 8.60 x 10-5 fry)

TERM PROB.

MJMBER OF TERM CORED =

1 2.2065E-05 AF01PBFS

IF-ET17 +

2 7.9296E-06 IF-ET3 e PRH01PACFS +

3 6.1081E-06 AF01PBFR e IF-ET17 +

4 3.5400E-06 IF-ET3 e HPRECIRCOP +

5 2.2671E-06 PAF01PEM e IF-ET17 +

6 1.6461E-06 IF-ET3 e MVCC9412CC +

2 7 1.6461E-06 IF-ET3 e MVS!8811CC +

8 1.4100E-06 LPRECIRCOP

IF-ET2 +

9 1.4100E-06 IF-ET!

LPRECIRCOP +

10 1.3637E-06 ADVSX178D e IF-ET17 +

11 1.3637E-06 A0VSX173D e IF-ET17 +

12 9.5200E-07 IF-ET16 e PL-1

TT2-2 +

13 8.3287E-07 AFWSCCFAIL

IF-ET4 e DP8-200 +

14 8.1414E-07 EWSCCFAll

DP2-CD e IF-ET!4 +

15 8.1414E-07 AFWSCCFAIL

OP1-0D e IF-ET14 +

i 16 7.9235E-07 AFWSCCFAIL

OP2-QD e IF-ET11 +

17 7.9235E-07 AFWSCCFAIL

OP1-0D e IF-ET11 +

18 7.8000E-07 ET15V +

19 5.9426E-07 AFWSCCFAIL e OPI-0D e IF-ET7 +

20 5.9426E-07 FWSE. FAIL e IF-ET7 e OP2-0D +

I 21 4.5870E-07 CCESMJ1 e AF01PBFS e IF-ET14 +

l l

l C-9 Table C.5 (Continued) 22 4.4643E-07 CCESW1 e F0!PFS

IF-ET!! +

23 4.3277E-07 E 01PFS

F 01PBFS e IF-ET4

OP8-200 +

24 4.2304E-07 AFO!PFS e WO!PBFS e OP2-CD e IF-ET14 +

25 4.2304E-07 M01PFS e AF01PBFS e 091-0D e IF-ET!4 +

26 4.1172E-07 AF01PFS e WO1PBFS

OP2-CD e IF-ET!! +

27 4.1172E-07 E 01PFS e F 01PBFS

091-0D e IF-ET11 +

28 3.3482E-07 CCESW1 e WO1PBFS

IF-ET7 +

29 3.0879E-07 F0!MS

AF0!PBFS

IF-ET7 e OP2-0D +

30 3.0879E-07 F01PFS

WO!PBFS

0P1-0D e IF-ET7 +

31 3.0630E-07 PAF0!PAM e F01PBFS

IF-ET4 e OP8-20D +

32 2.9942E-07 PAF01PAM e M0!PFS e OP2-00 e IF-ET!4 +

33 2.9942E-07 PAF01PAM e AF01PBFS

0P1-00 e IF-ET!4 +

34 2.9443E-07 LDSPNONREC e DGANONREC e DGAFR e DSIMONREC e DGBFR e M01PBF 35 2.9140E-07 PAF0!PAM e 701PBFS

OP2-0D e IF-ET11 +

36 2.9140E-07 PAF0lPAM e M0!PFS e OP!-0D e IF-ET11 +

37 2.9067E-07 IF-ET3

PRH01PACFR +

38 2.1855E-07 PAF0!PAM e WO!PFS

IF ~T7 e OP2-QD +

39 2.1855E-07 PAF01PAM e F01PBFS e 0P1-00 e IF-ET7 +

40 2.1317E-07 AFWS TFAIL e IF-ET17 +

41 2.1056E-07 CCRHRPMPFS

IF-ET2 +

42 2.1056E-07 IF-ETI e CCRtiRPMDFS +

43 2.0724E-07 PRH01PACFS e AFWSCCFAIL e IF-ET14 +

44 2.0169E-07 PRH01PACFS

M WSCCFAIL e IF-ET11 +

45 1.7723E-07 CCESW1

IF-ET4 +

C-10 Table C.6 Dominant Cut Sets of Core Damage for Model 2 - Case 2 (Total - 5.44 x 10-4/ry)

TERM PROB.

IUlBER OF TERM CORED =

1 1.6799E-04 50lPBFS e IF-ET17 +

2 1.5264E-04 PAF0!PBM e IF-ET17 +

3 4.6504E-05 F01PBFR

IF-ET17 +

4 1.0382E-05 A0VSX178D e IF-ET17 +

5 1.0382E-05 A0VSX1730 e IF-ET17 +

6 7.9296E-06 IF-ET3 e PAH0lPACFS +

7 3.5400E-06 IF-ET3 e HPRECIRCOP +

8 2.7087E-06 PAF0!PAM e F0lPFS e IF-ET4 e OP8-200 +

9 2.6478E-06 PAF0lPAM e F0!PBFS e OP2-CD e IF-ET14 +

10 2.6478E-06 PAF0!PAM e AF0!PFS e 091-0D e IF-ET14 +

11 2.5769E-06 P F0!PAM e F0!PBFS e OP2-CD e IF-ET11 +

12 2.5769E-06 PAF0!PAM e AF0!PFS e Opi-0D e IF-EI!! +

13 1.9327E-06 PAF0!PAM e F0lPBFS e IF-ET7 e OP2-DD +

14 1.9327E-06 PAF0lPAM e FO!PFS e Opl-0D e IF-ET7 +

15 1.6461E-06 IF-ET3

MVS!8811CC +

16 1.6461E-06 IF-ET3 e MVCC9412CC +

17 1.6230E-06 AFWSCCFAIL e IF-ET17 +

18 1.4894E-06 LDSPNONREC e DSAM e DGBNONREC e D3BFR e FOIPEFS e IF 19 1.4894E-06 LOSPNONREC e DGAh0NREC e D6F R e DGEM e F 0!PDFS e IF 20 1.4100E-06 IF-ETl e LPRECIRCOP +

21 1.4100E-06 LPRECIRCCP e IF-ET2 +

C-11 Table C.6 (Continued) 22 1.3532E-06 LOSPNONREC e DGANONREC e D6AFR

D6BM e PAF01PBM e IF-ET12A e E120-2 +

23 9.5200E-07 IF-ET16

PL-1

TT2-2 +

24 9.1128E-07 1SSX01FAQ

1PSX0!PBM e AFO!PFS e IF-ET14 +

25 9.1128E-07 1PSX01PAM e 1SSX01FB0 e F 01PBFS

IF-ET14 +

26 8.8689E-07 ISSX01FAQ e IPSX01PBM e AF01PFS e IF-ET11 +

27 8.8689E-07 1PSX01PAM e 1SSX01FBQ e AF01PBFS

IF-ET11 +

28 8.3287E-07 AFWIKX: FAIL e IF-ET4 e OPS-20D +

29 8.2797E-07 1PSX0!PAM e ISSIO!FBQ e PAF01PBM e IF-ET14 +

30 8.2797E-07 ISSX01FAQ

1PSX01PBM e PAF01PBM e IF-ET14 +

31 8.1414E-07 AFWSCCFAIL e OP2-QD e IF-ET14 +

32 8.1414E-07 FWSCCFAIL e Opl-CD e IF-ET14 +

33 8.0581E-07 IPSX01PAM e ISSX01FB0 e PAF01PBM e IF-ET11 +

34 8.0581E-07 1SS101FAQ

iPSX01PBM e PAF01PBM e IF-ET11 +

35 7.9235E-07 AFWSCCFAIL e OP2-0D e IF-ET11 +

36 7.9235E-07 F WSCCFAIL

0P1-00

IF-ET11 +

37 7.8000E-07 ET15V +

38 7.5675E-07 LDSPNONREC e D6AM e D6BNONREC

DGBFS

W O1PBFS

IF-ET12A

E120-2 +

39 7.5675E-07 LOSPO NREC e DGANONREC e D6AFS e D6BM e F01PBFS e IF-ET12A e E120-2 +

40 7.4984E-07 PAF01PAM e M0!PFR e IF-ET4

OP8-20D +

41 7.3298E-07 PAF01PAM e F01PBFR e OP2-0D e IF-ET14 +

42 7.3298E-07 PAF01pAM e F01PFR e 0P1-0D e IF-ET14 +

43 7.2100E-07 S2-0C e IF-ET17 +

44 7.1336E-07 PAF01PAM e M01PFR

092-00

IF-ET11 +

45 7.1336E-07 PAF01Pfet

E01PDFR e Opt-QD e IF-ET11 +

C-12 Table C.7 Single-Event and Pairwise Importances for Model 1 - Case 1 s

BASIC EVENT SINBLE EVENT CONTRIBUTI(N TO PR(BASILITY F-V IMPORTANCE TOP EVENT 1

( 185) S2-GA 5.0000F01 8.78430-01 6.0877D-04 2 ( 195) IF-ET17 9.47000 4 4 7.3203D-01 5.0731D-04 3 ( 178) IF-ET12A 9.10000-02 8.3322D-02 5.7743D-05 4 ( 27) LOSPNONREC 2.6000D41 8.0622 H 2 5.5872D-05 5 ( 186) E120-2 7.40000 41 6.17790-02 4.2814 H 5 6 ( 28) D8MOSEC 7.50000-01 5.8456F02 4.0511 H 5 7 ( 33) DSIN0NIEC 7.5000 H I 5.7847D-02 4.0089045 8 ( 143) M01PBFS 2.3300 H 2 4.9891D-02 3.4575 H 5 9 ( 194) IF-ET14 4.1100D+00 4.8967D-02 3.3935F05 10 ( 177) IF-ET!!

4.0000D+00 4.7656D42 3.3026D-05 11

( 71) CCES68J1 4.79000-06 4.5823D-02 3.1756D-05 12 ( 169) IF-ET7 3.00000+00 3.5742D-02 2.47700-05 13 ( 30) DBE R 3.5820D-02 3.42890-02 2.37630-05 l

14 ( 35) DGBFR 3.5820 H 2 3.3855D-02 2.3462D-05 15 ( 97) IPSX01PBM 4.4820 H 3 2.7038D-02 1.8738D-05 16 ( 43) IPSX0lPAM 4.44200 4 3 2.7034D-02 1.8735D-05 17 ( 113) IF-ET3 3.5400 H 2 2.61190 4 2 1.8101D-05 18 ( 179) E120-1 2.6000D41 2.1543D-02 1.49300-05 19 ( 80) 1SSX01FAQ 2.40000-04 2.0214D-02 1.40080 4 5 20 ( 94) IS6X01FB0 2.40000 4 4 2.0213 H 2 1.40080-05 21

( 29) DGES 1.82000-02 1.7198 H 2 1.1918F05 22 ( 34) DGIFS 1.82000-02 1.7023D-02 1.1797F05 23 ( 126) PRH01PA(TS 2.2400D44 1.4197D-02 9.8387D-06 24 ( 144) M 01PDFR 6.4500D-03 1.3372D42 9.26700-06 25 ( 31) D6AM 1.5370D-02 1.3245D-02 9.17900-06 26 ( 32) DEIN 1.5370 H 2 1.3078F02 9.0635D-06 27 ( 139) FWGCCFAIL 2.2510 H 4 1.0699 H 2 7.41440-06 28 ( 147) OPl@

8.8000 H 4 8.29360-03 5.7476D-06 29 ( 172) OP2 4 8.8000F04 8.2729D-03 5.7333D-06 30 ( 140) F01PFS 5.0200D43 7.7854D43 5.3954F06 31

( 118) CCAC 6.30000-04 7.1770D-03 4.9738D-06 32 ( 175) IF-(T8 6.0000 H 1 7.1325 H 3 4.94290-06 33 ( 76) FSX03CBFR 8.47200-05 6.8963D-03 4.7792D-06 34 ( 73) FSX03CAFR 8.4720 H 5 6.8963D-03 4.7792D-06 35 ( 89) FSX03CFFR 8.4720F05 6.8962 H 3 4.7792D-06 36 ( 86) FSX03CEFR 8.47200-05 6.89620 4 3 4.77920-06 37 ( 120) HPIECIRCOP 1.00000 4 4 6.3023D-03 4.36760-06 38 ( 75) FSX03CIM 1.1120D43 5.80500 4 3 4.02290-06 39 ( 72) FSX03 CAM 1.!!200-03 5.8050F03 4.0229D-06 40 ( 88) FSX03CFM 1.!!20043 5.61520-03 3.89140 4 6 41

( 85) FSX03CEM 1.11200-03 5.61520-03 3.8914D-06 42 ( 141) PAF0lPAM 3.55300 4 3 5.3703D-03 3.72170-06

C-15 Table C.7 (Continued) 43 ( 142) PAF01PBM 2.3940D-03 4.65370-03 3.2251D-06 44 ( 176) IF-ET9 3.58000-01 4.2421D-03 2.93990-06 45 ( 77) FSIO3CBFS 1.1700D-03 4.1531D-03 2.8782D-06

% ( 74) FSX03CAFS 1.1700D-03 4.1531D-03 2.8782D-06 47 ( 90) FSX03CFFS 1.1700D-03 4.1516D-03 2.8771D-06 48 ( 87) FSIO3CEFS 1.1700D-03 4.1516D-03 2.8771D-06 49 ( 69) LPREC1RCOP 1.5000D-03 4.0692D-03 2.8200D-06 50 ( 150) 1F-ET4 3.8200D-02 4.0691D-03 2.8200D-06 51

( 7) IF-ETI 9.4000D-04 3.1260D-03 2.1664D-06 52 ( 163) OP8-20D 1.0000D-01 2.9666D-03 2.0559D-06 53 ( 122) MVCC9412CC 4.6500D-05 2.8976D-03 2.0081 H 6 54

( 121) MVS18811CC 4.65000-05 2.8976D-03 2.0081D-06 55 ( 14) A0VSX178D 1.44000-03 2.7883D-03 1.9323D-06 56 ( 145) A0VSX173D 1.4400D-03 2.7883D43 1.9323D-06 57

( 26) LOSP 3.4000D-04 2.7457D-03 1.9028D-06 58 ( 109) 1PSX01PAFS 7.21000 4 4 2.5526D-03 1.76900-06 59 ( 110) 1PSX01PBFS 7.2100D-04 2.5517D-03 1.76840-06 60 ( 105) IF-ET2 9.4000D-04 2.54080-03 1.7608D-06 61

( 98) BUS 131ZD 5.5720D-05 2.3800D-03 1.6494D-06 62 ( 101) BUS 132ZD 5.5720D-05 2.37990-03 1.6493D-06 63 ( 189) IF-ET!3 1.60000-01 2.3225D-03 1.6096D-06 64 ( 103) FLA6ESFANF 5.0000D41 2.1281D-03 1.4748D-06 65 ( 102) FLAGESFANE 5.0000D-01 2.1281D-03 1.4748D-06 66 ( 100) FLAGESFANB 5.00000-01 2.1281D-03 1.47480-06 67 ( 99) FLAGESFANA 5.00000-01 2.1281D-03 1.47480-06 68 ( 95) 1PSX01PBFR 3.1680D-05 2.0604D-03 1.42790-06 69 ( 84) IPSX01PAFA 3.1680D-05 2.0604D-03 1.4279D-06 70 ( 191) PL-1 5.0000D-01 1.37440-03 9.5248D-07 71

( 190) IF-ET16 1.3600D-05 1.3744D-03 9.5248D47 72 ( 193) TT2-2 1.40000-01 1.3737D-03 9.5200D-07 73 ( 112) FLAGESPBFS 5.0000D-01 1.3114D-03 9.0881D-07 74 ( 111) FLAGESPAFS 5.00000-01 1.3114D-03 9.0881D-07 75 ( 199) ET15V 7.8000D-07 1.1255D-03 7.8000D-07 76 ( %) 1SSX01FBM 1.90000-04 9.33%D-04 6.47250-07 77 ( 82) ISSX01FAM 1.9000D-04 9.33%D-04 6.47250-07 78 ( 181) S2-0C 1.0000D-04 8.9016D-04 6.16900-07 79 ( 198) CCESWUILOSP 1.20000-05 8.3587D-04 5.79270-07 80 ( 55) MVCC9412BQ l.55000-03 7.6051D-04 5.27040-07 81

( 51) MVS18811B0 1.5500D-03 7.6051D-04 5.2704D-07 82 ( 155) OP34D 3.00000-03 7.5803D-04 5.2532D-07 83 ( 45) MVCC9412AQ l.55000-03 6.7456D-04 4.6748D-07 84 ( 41) MVS!8811A0 1.5500D-03 6.7456D-04 4.6748D-07 85 ( 149) AF01PFR 4.93500-04 6.2802D-04 4.3523D-07 86 ( 23) CCRHAPPPFS 2.2400D-04 6.07660-04 4.2112 H 7 87 ( 93) IXVSX143BC 9.50400-06 5.7929D-04 4.014D-07 88

( 92) 1MVSX00!BC 9.50400-06 5.7929D-04 4.0146D-07 89 ( 4) PRH01PBM 1.1600D-03 5.6373D-04 3.9067D-07 90 ( 2) pRH01PAM 1.1600 H 3 5.1390D-04 3.5614 H 7

C-14 Table C.7 (Continued)

PAIRWISE CONTRIBUTION TO F-V INPORTANCE TOP EVENT 1

( 185) S2-GA

( 195) IF-ET17 6.8325D-01 4.7350D-04 2 ( 27) LDSPNONREC

( 178) IF-ET12A 7.7876D-02 5.3970D-05 3 ( 185) S2-GA

( 178) IF-ET12A 7.6879D-02 5.3279D-05 4 ( 185) S2-04

( 27) LOSPNONREC 7.4737D-02 5.1794D-05 5 ( 178) IF-ET12A

( 186) E120-2 6.1779D-02 4.2814tH)5 6 ( 27) LOSPNONREC

( 28) DGAN(NEC 5.8456D-02 4.0511D-05 7 ( 27) LOSPNONREC

( 33) D6BNONREC 5.7847D42 4.0089D-05 8 ( 27) LDSPNONREC

( 1E) E120-2 5.77190-02 4.00000-05 9 ( 185) S2-04

( 12) E120-2 5.6923D-02 3.9449D-05 10 ( 28) D6ANONREC

( 178) IF-ET12A 5.6371D-02 3.9066D-05

( 33) D6BNONREC

( 178) IF-ET12A 5.57680-02 3.8648D-05 12 ( 185) S2-04

( 28) D6AN(NEC 5.4160D-02 3.7534D-05 13 ( 185) S2-0A

( 33) D6BNONREC 5.4153D-02 3.7529D-05 14 ( 28) D6ANONREC

( 1E) E120-2 4.1775D-02 2.8951D-05 15 ( 33) D6BNONREC

( IE) E120-2 4.1292D-02 2.E16D-05 16 ( 28) 06ANONREC

( 33) 06BN(NREC 3.7940D-02 2.6293D-05 17 ( 28) DGANONREC

( 30) D6AFR 3.4289D-02 2.3763D-05 18 ( 27) LOSPNONREC

( 30) D6F R 3.4289D-02 2.3763D-05 19 ( 33) DGBNONREC

( 35) D6BFR 3.3855D-02 2.3462D-05 20 ( 27) LOSPNONREC

( 35) D6FR 3.3855D-02 2.3462D-05 21

( 30) DGF R

( 178) IF-ET12A 3.2988D-02 2.2861D-05 22 ( 35) DGFR

( 178) IF-ET12A 3.2559D-02 2.2564D-05 23 ( 185) S2-QA

( 30) D6AFR 3.1689D-02 2.1%1D-05 24 ( 185) S2-QA

( 35) D6FR 3.1682D-02 2.1956D-05 25 ( 185) S2-04

( 97) IPSIO1PBM 2.52590-02 1.7505D-05 26 ( 185) S2-GA

( 83) IPSX0!PAM 2.5259D-02 1.7505D-05 27 ( 30) D6AFR

( 186) E120-2 2.4439D-02 1.69360-05 28 ( 35) D6FR

( 186) E120-2 2.4101D-02 1.6702D-05 29 ( 30) D6AFR

( 33) D6BNONREC 2.0778D-02 1.4400D-05 30 ( 28) DGANONREC

( 35) D6FR 2.0778D-02 1.4400D-05 31

( 28) D6ANONREC

( 29) D6AFS 1.7198D-02 1.19180-05 32 ( 27) LOSPNONREC

( 29) D6 F S 1.71980-02 1.1918D-05 33 ( 33) DGBNONREC

( 34) DGF S 1.7023D-02 1.1797D-05 34 ( 27) LOSPNONREC

( 34) D6FS 1.7023D-02 1.1797D-05 35 ( 29) DGAFS

( 178) IF-ET12A 1.6690D-02 1.1567D-05 36 ( 34) D6FS

( 178) IF-ET12A 1.6517D-02 1.1446D-05 37 ( 185) S2-04

( 34) DG FS 1.5948D-02 1.1052D-05 38 ( 185) S2-QA

( 29) D6F S 1.5948D-02 1.1052D-05 39 ( 30) D6AFR

( 35) D6FR I.3782D-02 9.55080-06 40 ( 27) LDSPNONREC

( 31) D6AM 1.3245D-02 9.17900-06 41

( 27) LOSPNONREC

( 32) DGBM 1.30780-02

9. % 350-06 42 ( 31) D6AM

( 178) IF-ET12A 1.2727D-02 8.8200D-06 1

l C-15 Table C.7 (Continued) 43 ( 32) D6BM

( 178) IF-ET12A 1.2558D-02 8.7029D-06 44 ( 29) DGAFS

( 186) E120-2 1.2379D-02 8.5788D-06 45 ( 34) D6FS

( 186) E120-2 1.22340-02 8.4780D-06 46 ( 185) S2-0A

( 32) DSBN 1.2193D-02 8.44%D-06 47 ( 185) S2-04

( 31) D6AM 1.2193D-02 8.44%D-06 48 ( 28) DGANONREC

( 32) 06BM 1.2058D-02 8.3564D-06 49 ( 31) DGAM

( 33) D6BNONREC 1.2005D-02 8.3193D-06 50 ( 29) D6AFS

( 33) D6BN(NREC 1.04000-02 7.2074D-06 51

( 28) DGANONREC

( 34) D6BFS 1.0400D-02 7.2074D-06 52 ( 31) D6AM

( 186) E120-2 9.4287D-03 6.5342D-06 53 ( 32) DGBM

( 186) E120-2 9.29700 ^3 6.44300-06 54 ( 30) D6AFR

( 32) 06BM 7.9105D-03 5.4821D-06 55 ( 31) DGAM

( 35) D6BFR 7.8754D-03 5.45780-06 56 ( 118) CCAC

( 27) LOSpl0NREC 7.17700-03 4.9738D-06 57 ( 30) DGAFR

( 34) D6BFS 6.9968D-03 4.8489D-06 58 ( 29) DGAFS

( 35) D6FR 6.9968D-03 4.8489D-06 59 ( 118) CCAC

( 28) DGANONREC 6.%95D-03 4.8300D-06 60 ( 118) CCAC

( 33) D6BNONREC 6.%%D-03 4.8296D-06 61

( 118) CCAC

( 178) IF-ET12A 6.9006D-03 4.7822D-06 62 ( 118) CCAC

( 185) S2-DA 6.7214D-03 4.65800-06 63 ( 185) S2-04

( 75) FSIO3CBM 5.56000-03 3.8532D-06 64 ( 185) S2-GA

( 72) FSX03 CAM 5.5600D-03 3.8532D-06 65 ( 185) S2-GA

( 88) FSX03CFM 5.3725D-03 3.7232D-06 66 ( 185) S2-GA

( 85) FSX03CEM 5.3725D-03 3.7232D-06 67 ( 118) CCAC

( 186) E120-2 5.1161D-03 3.54560-06 68 ( 97) IPSX0!PBM

( 178) IF-ET12A 4.4996D-03 3.1183D-06 69 ( 83) IPSX01PAM

( 178) IF-ET12A 4.4996D-03 3.1183D-06 70 ( 29) 06 F S

( 32) D6BM 4.0155D-03 2.7828D-06 71

(.31) D6AM

( 34) D6BFS 3.9977D-03 2.7705D-06 72 ( 28) DGANONREC

( 97) IPSX0!PBM 3.5092D-03 2.4319D-06 73 ( 27) LOSPNONREC

( 97) 1PSX01PBM 3.5092D-03 2.43190-06 74 ( 33) DGBNONREC

( 83) 1PSX01PAM 3.5052D-03 2.4292D-06 75 ( 27) LOSPNONREC

( 83) IPSX01PAM 3.5052D-03 2.4292D-06 76 ( 29) DG FS

( 34) D6FS 3.4033D-03 2.3586D-06 77 ( 97) 1PSX01PBM

( 186) E120-2 3.3320D-03 2.3091D-06 78 ( 83) IPSX01PAM

( 186) E120-2 3.3320D-03 2.3091D-06 79 ( 142) PAF01PBM

( 195) IF-ET17 3.2714D-03 2.2671D-06 80 ( 26) LOSP

( 27) LOSPNONREC 2.7457D-03 1.9028D-06 81

( 185) S2-04

( 26) LOSP 2.66700-03 1.8483D-06 82 ( 30) D6F R

( 97) 1PSX0!PBM 2.3032D-03 1.5%2D-06 83 ( 35) D6FR

( 83) IPSX01PAM 2.2992D-03 1.59340-06 84 ( 26) LOSP

( 28) 06ANONREC 2.0850D-03 1.4449 H 6 85 ( 26) LOSP

( 33) 06BNONREC 2.0787D-03 1.4406D-06 86 ( 141) PAF01PAM

( 147) 0P1-0D 1.7944D-03 1.2436D-06 87

( 141) PAF01PAM

( 172) OP2-00 1.7897D-03 1.2403&-06 88

( 26) LOSP

( 30) D6AFR 1.3013D-03 9.0179D-07 89 ( 26) LOSP

( 35) D6BFR 1.2958D-03 8.97990-07 90 ( 34) 06BFS

( 83) IPSX0!PAM 1.1677D-03 8.09200-07 l

C-16 Table C.8 Single-Event and Pairwise Importances for Model 1 - Case 2 BASIC EVENT SIN 6LE EVENT CONTR!iUT!(N TO PROBABILITY F-V IMPORTANCE TDP EVENT 1

( 185) S2-04 5.00000-01 8.8830D-01 4.2762D-03 2 ( 195) IF-ET17 7.2100D43 8.3047D-01 3.99780-03 3 ( 178) IF-ET12A 9.1000D-02 5.7717D-02 2.7785D-04 4 ( 27) LOSPNONREC 2.60000 4 1 5.4757D-02 2.6360D-04 5 ( 143) AF0!PBFS 2.3300D-02 4.6839D-02 2.25480-04 6 ( 186) E120-2 7.40000-01 4.2770D-02 2.05890-04 7 ( 142) PAF01PBM 2.!!70D-02 3.7029D-02 1.7826D44 8 ( 97) IPSX0!PBM 3.9650D-02 3.5573D-02 1.7125D-04 9 ( 83) IPSX0lPAM

3. % 500-02 3.5568D-02 1.7122D-04 10 ( 194) IF-ET14 4.11000+00 3.4712D-02 1.6710D44 11

( 177) IF-ETil 4.0000D+00 3.3783D-02 1.6263D-04 12 ( 28) D6ANONREC 7.5000D-01 2.9155D-02 1.4035D-04 13 ( 33) D6BNONREC 7.5000D-01 2.8308D-02 1.3627D44 14 ( 169) IF-ET7 3.00000+00 2.5337D-02 1.2197D-04 15 ( 80) ISSX01FAQ 2.40000-04 2.1491D-02 1.0346D-04 16 ( 94) ISSX01FB0 2.40000 4 4 2.14880-02 1.03440-04 17 ( 30) D6AFR 3.58200-02 1.8528D-02 8.9192D-05 18 ( 35) D60FR 3.58200-02 1.7962D-02 8.64690 4 5 19 ( 32) 06BM 1.3590 N 1 1.72490-02 8.3036D45 20 ( 31) DGA1 1.35900-01 1.6881D-02 8.1265D-05 21

( 179) E120-1 2.6000D-01 1.4947D-02 7.1955D-05 22 ( 144) AF0lPBFR 6.4500D-03 1.2607D-02 6.0688D-05 23 ( 29) 06AFS 1.8200D-02 9.3695D-03 4.5104D-05 24 ( 34) D6BFS 1.8200D-02 9.09400 4 3 4.3778D-05 25 ( 75) FSX03CBM 9.8280D-03 7.5465D43 3.6328D-05 26 ( 72) FSX03 CAM 9.82800-03 7.5465D-03 3.6328D-05 27 ( 76) FSXO3CBFR 8.47200-05 7.3699D43 3.5478D-05 28 ( 73) FSX03CAFR 8.47200-05 7.3699D-03 3.5478D-05 29 ( 89) FSX03CFFR 8.4720D-05 7.3690D-03 3.5474D-05 30 ( 86) FSIO3CEFR 8.47200-05 7.36900-03 3.5474D-05 31

( 88) FSX03CFM 9.82800-03 7.30500-03 3.5166D-05 32 ( 85) FSX03CEM 9.82800-03 7.30500-03 3.5166D-05 33

( 141) PAFOIPAM 3.14200-02 7.1041D-03 3.41980-05 34 ( 71)CCESWU!

4.7900D-06 6.8251D-03 3.2856D-05 35 ( !!3) IF-ET3 3.54000-02 5.20150-03 2.50400-05 36 ( 175) IF-ET8 6.0000D-01 5.0582D-03 2.4350D-05 37 ( 147) DP1-CD 8.8000D-04 3.47100-03 1.67090-05 38 ( 172) 092-0D 8.80000 4 4 3.4621D-03 1.6666D-05 39 ( 98) BUS 131ZD 5.5720D-05 3.1375D-03 1.51040-05 40 ( 101) BUS 132ZD 5.5720D45 3.13690-03 1.5101D-05 41

( 176) IF-ET9 3.5800D41 3.0108D-03 1.4494D-05 42 ( 95) IPSX0lPBFR 3.16800-05 2.6605D-03 1.2808D-05

1 C-17 Table C.8 (Continued) 43 ( 84) IPSX0!PAFR 3.1680D-05 2.6605D-03 1.28080-05 44 ( 1 %) A0VSX178D 1.44000-03 2.6524D-03 1.2768D-05 45 ( 145) A0VSX173D 1.4400D-03 2.6524D-03 1.2768D-05

% ( 126) PRH01PACFS 2.2400D-04 2.6276D-03 1.2649D-05 47 ( 26) LOSP 3.4000D-04 1.9170D-03 9.2285D-06 48 ( 139) AFWSCCFAIL 2.2510C 04 1.9015D-03 9.1538D-06 49 ( 150) IF-ET4 3.8200D-02 1.8672D-03 8.9884D-06 50 ( 140) AF0!PFS 5.0200D43 1.7415D-03 8.3834D-M 51

( 77) FSX03CBFS 1.1700D-03 1.6501D-03 7.9434D-06 52 ( 74) FSX03CAFS 1.17000-03 1.6501D-03 7.9434D-06 53 ( %) FSIO3CFFS 1.1700D-03 1.6335D-03 7.8637D-06 54 ( 87) FSX03CEFS 1.1700D-03 1.6335D-03 7.8637D-06 55 ( 118) CCAC 6.3000D-04 1.5031D-03 7.2359D-06 56

( 189) IF-ET13 1.60000-01 1.4532D-03 6.9958D-M 57 ( 163) OP8-20D 1.00000-01 1.2377D-03 5.9582D-06 58 ( %) 1SSX01FBM 1.6800D-03 1.1962D-03 5.7583D-06 59 ( 82) 1SSX01FAM 1.68000-03 1.1962D-03 5.7583D-06 60 ( 120) HPRECIRCOP 1.00000-04 1.1635D-03 5.6008D-06 61

( 109) IPSX01PAFS 7.2100D-04 1.01%D-03 4.8844D-06 62 ( 110) IPSX01PBFS 7.2100D-04 1.0044D-03 4.8353D-06 63 ( 4) PRH01PBM 1.0300D-02 8.9135D-04 4.2909D-06 64 ( 2) PRH01PAM 1.0300D42 7.8979D-04 3.80200-06 65 ( 93) 1XVSX143BC 9.50400-06 7.33880-04 3.53290-06 66 ( 92) 1MVSX001BC 9.50400-06 7.33880-04 3.53290-06 67 ( 69) LPRECIRCOP 1.5000D-03 5.8580D-04 2.8200D-06 68 ( 122) MVCC9412CC 4.65000-05 5.34%D-04 2.5753D-06 69 ( 121) MVS!8811CC 4.6500D-05 5.34%D-04 2.5753D-06 70 ( 91) OXVSX138BC 9.50400-06 4.91990-04 2.3684D-06 71 f, 81) 1XVSX143AC 9.5040D-06 4.9199D-04 2.36840-06 72 ( 79) IMVSX001AC 9.50400-06 4.9199D44 2.3684D-06 i

73 ( 78) 0XVSX138AC 9.5040D-06 4.9199D-04 2.3684D46 74 ( 7) IF-ETt 9.4000D44 4.7678D-04 2.2952D-06 75 ( 105) IF-ET2 9.4000D-04 3.9443D-04 1.8988D-06 76 ( 103) FLA6ESFA W 5.0000D-01 3.%36D-04 1.4748D-06 77 ( 102) FLAGESFANE 5.0000D-01 3.0636D44 1.4748D-06 78 ( 100) FLAGESFANB 5.0000D-01 3.06360-04 1.4748D-06 79 ( 99) FLABESFANA 5.0000D-01 3.0636D44 1.47480-06 80 ( 55) MVCC9412B0 1.55000-03 3.0186D-04 1.45310- %

81

( 51) MVS!881tE0 1.5500D-03 3.01860-04 1.45310-06 82 ( 181) S2-0C 1.00000-04 2.6263D-04 1.2643D-%

83

( 45) MVCC9412AQ l.55000-03 2.5887D44 1.2462D-06 84

( 41) MVS18811AQ l.5500D-03 2.5887D-04 1.2%2D-06 85 ( 155) DP3-00 3.00000-03 2.4590D-04 1.1837D-06 86 ( 132) MVS!8804E0 1.5500D-03 2.44510 4 4 1.1771D-06 87

( 174) OP2-OR 3.00000-03 2.1078D-04 1.0147D-06 88 ( 173) OP2-GA 1.90000-02 2.1078D-04 1.0147D-06 89 ( 131) MVS!680400 1.55000-03 2.0148D44 9.6990D-07 90 ( 191) pt-1 5.0000D-01 1.9865D-04 9.5628D-07

C-18 Table C.8 (Continued)

PAIRWISE CONTRIBUTION TO F-V INPDRTANCE TOP EVENT 1

( 185) S2-04

( 195) IF-ET17 7.9863D-01 5.7000D-03 2 ( 27) LOSPNONREC

( 178) IF-ET12A 3.5640D-02 2.5437D-04 3 ( 185) S2-GA

( 178) IF-ET12A 3.51240-02 2.50690-M 4 ( 142) PAF01PIM

( 195) IF-ET17 3.3814D-0R 2.4134D-04 5 ( 185) S2-04

( 27) LOSPNONREC 3.3390D-02 2.3831D-04 6 ( 178) IF-ET!2A

( 1E) E120-2 2.8848D-02 2.0589D-04 7 ( 27) LOSPNONREC

( 186) E120-2 2.6401D-02 1.8843D-04 8 ( 185) S2-0A

( IM) E120-2 2.5996D-02 1.8554D-M 9 ( 185) S2-04

( 97) 1PSX01PBM 2.1697D-02 1.5486D-04 10 ( 185) S2-GA

( 83) 1PSX01PAM 2.1697D-02 1.5486D-M 11

( 27) LOSPNONREC

( 28) DGANONREC 1.96650-02 1.40350-04 12 ( 27) LOSPNONEC

( 33) 06BNMEC 1.9093D-02 1.3627D-04 13 ( 28) DGMONEC

( 178) IF-ET12A 1.89390-02 1.3517D-04 14 ( 33) D6BNONREC

( 178) IF-ET12A 1.8388D-02 1.3124D-04 15 ( 185) S2-GA

( 28) DGANONREC 1.76000-02 1.2562D-04 16 ( 185) S2-GA

( 33) 06BNMEC 1.7600D-02 1.2561D-04 17 ( 28) D6ANONEC

( 186) E120-2 1.4025D-02 1.00100-M 18 ( 33) 06BNWEC

( IE) E120-2 1.3612D-02 9.7153D-05 19 ( 28) DGANONREC

( 30) DGAFR 1.2497D-02 8.9192D-05 20 ( 27) LDSPNONREC

( 30) D6AFR 1.2497D-02 8.9192D-05 21 ( 33) 068NONREC

( 35) 06BFR 1.21150-02 8.64680-05 22 ( 27) LDSPNONREC

( 35) D6BFR 1.2115D-02 8.6468D-05 23 ( 30) DGAFA

( 178) IF-ET12A 1.2021D-02 8.5795D-05 24 ( 35) 06BFR

( 178) IF-ET12A 1.1654D-02 8.3178D-05 25 ( 27) LOSPNONREC

( 32) D6BM 1.1634D-02 8.3036D-05 26 ( 27) LOSPNONEC

( 31) DBAM 1.1386D-02 8.1265D-05 27 ( 32) D6IN

( 178) IF-ET12A 1.1172D-02 7.97400-05 28 ( 185) S2-GA

( 30) D6F R 1.1170D-02 7.9721D-05 29 ( 185) S2-04

( 35) D6BFR 1.11690-02 7.97170-05 30 ( 31) D6AM

( 178) IF-ET12A 1.0941D-02 7.8091D-05 31

( 28) D6ANONEC

( 32) D6BM 1.0714D-02 7.6470D-05 32 ( 185) S2-GA

( 32) 06BM

!.04680-02 7.4710D-05 33 ( 185) S2-0A

( 31) D6AM 1.M68D-02 7.47100-05 34 ( 31) D6AM

( 33) 06BNWEC 1.03CSD-02 7.35690-05 35 ( 30) DGAFR

( 186) E120-2 8.90000-03 6.3521D-05 36 ( 35) 06BFR

( 186) E120-2 8.6264D-03 6.1568D-05 37 ( 32) D6BM

( 186) E!20-2 8.27290-03 5.90450-05 38 ( 31) D6AM

( 186) E120-2 8.10700-03 5.7 eld-05 39 ( 30) D6AFR

( 32) D6BM 7.0290D-03 5.0167D-05 40 ( 31) DGM

( 35) D6BFR 6.7625D-03 4.8265D-05 41

( 28) DGANONREC

( 29) DGAFS 6.31960-03 4.51040-05 42 ( 27) LOSPNONEC

( 29) D6AFS 6.31960-03 4.51040-05

C-19 Table C.8 (Continued) 43 ( 33) D6BN(NREC

( 34) D6BFS 6.1338D-03 4.3778D-05 44 ( 27) LDSPNONEC

( 34) D6BFS 6.1338D-03 4.3778D-05 45 ( 29) D6M S

( 178) IF-ET12A 6.0967D-03 4.3513D-05 46 ( 34) D6BFS

( 178) IF-ET12A 5.9166D-03 4.2228D-05 47 ( 185) S2-GA

( 34) D6BFS 5.6602D-03 4.0398D-05 48 ( 185) S2-GA

( 29) D6AFS 5.6602D-03 4.0398D-05 49 ( 185) S2-GA

( 75) FSIO3CBM 4.7715D-03 3.4055D-05 50 ( 185) S2-QR

( 72) FSIO3 CAM 4.7715D43 3.4055D-05 51

( 185) S2-GA

( 88) FSIO3CFM 4.6106D43 3.29060-05 52 ( 185) S2-QR

( 85) FSIO3CEM 4.6106D-03 3.2906D-05 53 ( 29) DGAFS

( 186) E120-2 4.5166 H 3 3.2236D-05 54

( 34) 06BFS

( 186) E120-2 4.3806D-03 3.1265D-05 55 ( 97) IPSI 0lPBM

( 178) IF-ET12A 3.9995D-03 2.8545D-05 56 ( 83) IPSI 0lPAM

( 178) IF-ET12A 3.9995D-03 2.8545D-05 57 ( 28) D6ANONREC

( 33) D6BNONREC 3.8082D43 2.7180D-05 58 ( 29) D6AFS

( 32) D6BM 3.5680D-03 2.5466D-05 59 ( 31) D6AM

( 34) D6BFS 3.4326D-03 2.4499D-05 60 ( 28) DGAM)NREC

( 97) IPSI 0lPBM 3.1155D-03 2.2236D-05 61

( 27) LDSPM]NREC

( 97) 1 PSI 0lPBM 3.1155D-03 2.2236D-06 62 ( 33) DGBNONREC

( 83) IPSIO!PAM 3.1121D-03 2.2212D-05 63 ( 27) LOSPNONREC

( 83) 1 PSI 0lPAM 3.ll21D43 2.2212D-05 64 ( 97) 1 PSI 0lPBM

( 186) E120-2 2.9621D-03 2.ll41D-05 65 ( 83) IPSIO1PAM

( 186) E120-2 2.9621 H 3 2.11410-05 C6 ( 30) D6AFR

( 33) DGBN(NEC 2.0853D-03 1.4883D-05 67 ( 28) D6ANONREC

( 35) DGBFR 2.0853D-03 1.4883D-05 68 ( 30) DGAFR

( 97) IPS10lPBM 2.0447D-03 1.4594D-05 69 ( 35) D6BFR

( 83) IPSI 0lPAM 2.0413D-03 1.4569D-05 70 ( 141) PAF0lPAM

( 147) OP1-0D 1.5408D-03 1.0997D-05 71

( 141) PAF01PAM

( 172) OP2-00 1.5367D-03 1.0968D-05 72 ( 30) D6F R

( 35) D6BFR 1.3831D43 9.8714D-06 73 ( 26) LDSP

( 27) LDSPNONREC 1.2930D-03 9.2285D-06 74 ( 185) S2-GA

( 26) LDSP 1.2153D-03 8.6735D-06 75 ( 142) PAF0lPBM

( 178) IF-ET12A 1.ll73D43 7.9747D-06 76 ( 29) DGAFS

( 33) D6BN(NEC 1.0443D-03 7.4532D-06 77 ( 28) DGANONREF

( 34) D6BFS 1.0443D43 7.4532D46 78 ( 34) D6BFS

( 83) IPS10lPAM 1.0367D-03 7.3991D-06 79 ( 29) DGAFS

( 97) IPSIO1PBM 1.0367D-03 7.3991D-06 80 ( 27) LDSPNONREC

( 142) PAF0!PBM 1.0181D-03 7.2665D-06 81

( 118) CCAC

( 27) LOSPNONREC 1.0138D-03 7.23580-06 82 ( !!8) CCAC

( 178) IF-ET12A 9.8699D-04 7.0443D-06 83 ( 75) FSI0 IBM

( 178) IF-ET12A 9.8224D-04 7.0104D-06 84 ( 72) FSIO3 CAM

( 178) IF-ET12A 9.82240-04 7.0104D-06 2 ( 88) FSIO3CFM

( 178) IF-ET12A 9.8135D-04 7.00410-06 86 ( 85) FSID3CEM

( 178) IF-ET12A 9.8135D-04 7.004tD-06 87 ( 118) CCAC

( 185) S2-04 9.2616D-04 6.6102D-06 88 ( 142) PAF0lPBM

( 97) IPSIO!PBM 8.6602D-04 6.1809D-06 89 ( 83) IPSI 0lPAM

( 142) PAF0lPBM 8.6602D44 6.1809D46 90 ( 118) CCAC

( 28) DGAN(NREC 8.4846D-04 6.0556D-06 1

D-1 l

APPENDIX D EVENT DEFINITIONS AND NOTATIONS

Event Name Event Description System or Function IF-ET1 Large LOCA Initiator IF-ET2 Mediam LOCA Initiator IF-ET3 Small LOCA Initiator IF-ET4 Steam generator tube rupture Initiator IF-ET5 Steambreak inside containment Initiator IF-ET6 Steambreak outside containment Initiator IF-ET7 Loss of main feedwater Initiator IF-ET8 Closure of MSIV Initiator IF-ET9 Loss of RCS flow Initiator IF-ET10 Core power excursion Initiator IF-ET11 Turbine trip Initiator IF-ET12A Loss of offsite power Initiator IF-ET13 Spurious safety injection Initiator IF-ET14 Reactor trip Initiator IF-ET15 Interfacing systems LOCA Initiator IF-ET16 ATWS Initiator IF-ET17 Loss service water Initiator AF01PBFS AFW pump B fails to start AFWS AF01PBFR AFW pump B fails to run AFWS AFWS PAF01PBM AFW pump B in maintenance PRH01PACFS Common cause failure of RHR pumps to start HPRECIRCOP Failure of operators to establish high R-2 pressure recirculation LPRECIRCOP Failure of operators to establish low R-1 pressure recirculation i

PRH01PAM RHR pump A in maintenance R-1 CCESWU1 Common cause f ailure of service water ESWS system S2-QA Induced seal LOCA given loss of service Induced LOCA water MVCC9412CC Common cause failure of valves 9412A and R-1, R-2 9412B

0ther events not listed here are defined in WCAP-10526.

D-2 4

Event Name Event Description System or Function MVSI8811CC Common cause failure of valves 8811A and R-1, R-2 8811B A0VSX178D SWS return valve ISX178 fails to operate AFWS A0VSX173D SWS inlet valve 1SX173 fails to operate AFWS LOSP Induced loss of offsite power EPS LOSPNONREC Nonrecovery of loss of offsite power in EPS 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months DGAFS Diesel generator A fails to start EPS DGAFR Diesel generator A fails to run EPS DGAM Diesel generator A in maintenance EPS CCAC Common cause failure of diesel generators EPS A and B BUS 131ZD 480-V bus 131 fails EPS DGANONREC Nonrecovery of diesel generator A in 1 EPS hour DGBN0NREC Nonrecovery of diesel generator B in 1 EPS hour E120-1 Recovery of loss of offsite power in EPS 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months E120-2 Nonrecovery of loss of offsite power in 2 EPS hours PR2-QD OP fails to close PORVs PR2 OP1-QD OP fails to diagnose need of bleed OP1 OP2-QD OP fails to diagnose need of feed and bleed OP2 OP3-QA OP fails to control feed and bleed OP3 OPS-1QD OP fails to shutdown for SGTR with SA2, OPS NT success 0P5-20D OP fails to shutdown for SGTR with MT OPS failure OP9 OP fails to shutdown for core power OP9 excursion 1PSX01PAFS Service water pump A fails to start ESWS 1PSX01PAFR Service water pump A fails to run ESWS 1PSX01PAM Service water pump A in maintenance ESWS 1SSX01FAQ Service water strainer A fails plugged ESWS ISSX01FAM Service water strainer A in maintenance ESWS FSX03CAFR Cooling tower fan A falls to run ESWS FSX03SWHE OP fails to switch cooling tower fans ESWS l

~ - -

s D-3 Event Name Event Description System or Function 1MVSX001BC Motor-operated valve 0018 fails closed ESWS 1XVSX143BC Manual valve 1438 fails closed ESWS OXVSX138BC Manual valve 1383 fails closed ESWS o

e a

N f

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}

t

)

R-1 REFERENCES 1.

Butler, J. C. et al., " Byron Generating Station Limiting Conditions for Operation Relaxation Program," Westinghouse Electric Corporation, WCAP-10526, Volumes 1 and 2, April 1984.

2.

Fischhoff, B.,

" Standard Setting Standards: A Systematic Approach to Managing Public Health and Safety Risks," Decision Research, NUREG/CR-3508, February 1984.

3.

U.S. Nuclear Regulatory Commission, " Safety Goals for Nuclear Power Plant Operation," NUREG-0880, Revision 1, May 1983.

4.

Cho, N.

Z.,

Papazoglou, I. A., Bari, R.

A.,

and El-Bassioni,

A.,

"A Decision-Theoretic Methodology for Reliability and Risk A11acation in Nuclear Power Plants," Paper No. 14, Proceedings of the International ANS/ ENS To)ical Meeting on Probabilistic Safety Methods and Applications, Volume 1, ;ebruary 1985, San Francisco, CA.

5.

Boccio, J.

L., Fragola, J.

R.,

Hall, R.

E., Lofgren, E.

V.,

Samanta, P.

K., and Vesely, W.

E., " Program Plan for a Procedure for Evaluating Technical Specifications (PETS)," Brookhaven National Laboratory, October 1984.

6.

Reactor Safety Study: An Assessment of Accident Risks in U.S. Comercial Nuclear Power Plants, U.S. Nuclear Regulatory Commission, NUREG-75/014 (WASH-1400), October 1975.

7.

Vesely, W. E. and Goldberg, F.

F.,

" FRANTIC - A Computer Code for Time Dependent Unavailability Analysis," NUREG-0193, October 1977.

8.

Howard, R., Dynamic Probabilistic Systems, Volumes I and II, John Wiley and Sons, Inc., New York, 1971.

9.

Lewis, E. E. and Olvey, L. A. "Markov Monte Carlo Unavailability Analy-sis,Trans. Am. Nucl. Soc., 47, 329 (1984).

10.

Busiik, A.

J.,

"Mor.te Carlo Methods for the Reliability Analysis of Markov Systems," Paper No.178, Proceedings of the International ANS/ ENS Topical Meeting on Probabilistic Safety Methods and Applications, Volume 3, February 1985, San Francisco, CA.

11. Vesely, W.

E., Gaertner, J.

P., and Wagner, D.

P., " Methodology for Risk-Based Analysis of Technical Specifications," Paper No. 32, ibid., Volume 1.

12. American Nuclear Society, and Institute of Electrical and Electronics Engineers, "A PRA Procedures Guide," NUREG/CR-2300, January 1983.

13. Vesely, W.

E.,

Goldberg, F.

F.,

Powers, J.

T.,

Dickey, J.

M.,

Smith, J. M.,

and Hall, R.

E., " FRANTIC II - A Computer Code for Time Dependent Unavailability Analysis," Brookhaven National Laboratory, NUREG/CR-1924, BNL-NUREG-51355, April 1981.

R-2

14. Ginzburg, T. and Powers, J.

T., " FRANTIC III - A Computer Code for Time-Dependent Reliability Analysis (User's Manual)," Brookhaven National Laboratory, Draft, April 1984.

15. Papazoglou, I. A. and Gyftopoulos, E.

P.,

"Markov Processes for Relia-bility Analyses of Large Systems," IEEE Trans. Reliability, R-26, 232, (1977).

16. Papazoglou, I.

A.

and Sun, Y.

H.,

" Risk Evaluation of Generic Fluid Systems," Brookhaven National Laboratory, NUREG/CR-3528, Review Draft, July 1982.

17. Papazoglou, I. A. and Cho, N.

Z., " Review and Assessment of Evaluation of Surveillance Frequencies and Out of Service Times for the Reactor Protec-tion Instrumentation System," Brookhaven National Laboratory, BNL-NUREG-51780, April 1984.

I 18.

Papazoglou, I. A., Bozoki, G., and Sun, Y.-H., "Probabilistic Evaluation of Limiting Conditions of Operations Outage Times for Diesel Generators,"

Brookhaven National Laboratory, BNL-NUREG-51781, May 1984.

19. Worrell, R. B. and Stack, D.

W., "A SETS User's Manual for the Fault Tree Analyst,"

Sandia National Laboratories, NUREG/CR-0465, SAND 77-2051, November 1978,

20. Barlow, R. E. and Proschan, F., Statistical Theory of Reliability and i

Life Testing, Holt, Rinehart and Winston, Inc., New York,1975.

21. Technical Specifications for Byron Station Units No. I and No. 2, Docket Nos. STN 50-454 and 50-455.

)

22. Westinghouse Electric Corporation and Commonwealth Edison Company, " Byron Risk Study:

A Probabilistic Risk Evaluation Based on the Zion Probabil-istic Safety Study," February 1983.

23. Commonwealth Edison Company, " Zion Probabilistic Safety Study," NRC Docket Nos. 50-295 and 50-304.

24. Berry, D. L. et al., " Review and Evaluation of the Zion Probabilistic Safety Study," Sandia National Laboratories, NUREG/CR-3300, SAND 83-1118, Vol.1, May 1984.

25. Torrey Pines Technology, " Byron Units 1 & 2 Braidwood Units 1 & 2 Auxil-iary Feedwater System Reliability Analysis," August 1981.

26. Atwood, C.

L., " Common Cause Failure Rates for Pumps," EG8G Idaho, Inc.,

NUREG/CR-2098, EGG-EA-5289, February 1983.

27. Swain, A. D. and Guttman, H.

E., " Handbook of Human Reliability Analysis with Emphasis on Nuclear Power Plant Applications," Sandia National Laboratories, NUREG/CR-1278, SAND 80-0200, August 1983.

28. Lambert, H.

E., " Measures of Importance of Events and Cut Sets in Fault Trees," in Reliability and Fault Tree Analysis, SIAM, Philadelphia, 1975.

R-3

29. Youngblood, R.,

Xue, D.,

and Cho, N.,

" Pair Importance Measures in Systems Analysis," Proceedings of the International ANS/ ENS Topical Meeting on Thermal Reactor Safety. February 1986, San Diego, CA.

30. Vesely, W. and Boccio, J.

L., "The Use of Risk Analysis for Determining Tech Specs:

Issues and Review Considerations," (BNL Internal Draft Report, December 1984).

31. Papazoglou, I.

A., Anavim, E., and Lederman, L., " Bayesian Analysis Under Population Variability with an Application to the Frequency of Loss of Offsite Power and Anticipated Transients in Nuclear Power Plants," Brook-haven National Laboratory, BNL-NUREG-31794, Informal Report, February 1983.

32. Lederman, L. and Cho, N.,

" Byron Accident Sequence Review," Brookhaven National Laboratory, Letter Report, February 1983.

33. Bari, R. A. et al., "Probabilistic Safety Analysis Procedures Guide,"

Brookhaven National Laboratory, NUREG/CR-2815, BNL-NUREG-51559, Vol. 1, Rev. 1, August 1985.

34. Gnedenko, B.

V.,

Belyayev, Yu.

K.,

and Solovyev, A.

D.,

Mathematical Methods of Reliability Theory, Academic Press, New York,1969.

u s huCLE AR EEGULATOXY COMwesseO:4 i utron7 %vwsta easspea e, reoc. saa vee he..e sars hnC POAM 335 NUREG/CR-4404 h 3d7 BIBLIOGRAPHIC DATA SHEET BNL-NUREG-51930 Sg t N$TRUCTsONfdp% f ag mEVER$4 J LE AVE SLA%ut 2 Yafit AND SutterLE Analysis of Al wed Outage Times at the Byron Generati 4oATi **oafcow"<o Station l

, A,s

.O~T.

December 1985

. Au Y,. Oms, N.Z. Cho, T-L. Chu, D. Xue, G.E. Bozoki, and

,,A,,

R.W. Youngblood June 1986 a PROJECT.Y A54 WOHK uNif NuMStR 7 s tRFO*W4NG Om3ANIZAfiON NAWE AND W iNG ADDRE55 Heweele Cadet

"*o"6"'**""

Brookhaven Natianal Lab atory Upton, NY 11973 A3810 a to MPE OF R E*0MT 10 Sv0N54m'NG OmGANil ATtON N AUt AND MasteNG ADD

$ nacsues le Co,,,

Division of PWR Licensing-B Office of Nuclear Reactor Regu tion

' " " ' ' ' ' " ' " ~ ~ ' ~ ~ ~ " ~

U.S. Nuclear Regulatory Commiss n Washington, DC 20555 12 SuePLEwt%T ARv NOTES

13. A.5T R ACT #200 weree er ' esso This report provides a critic review of the methods used in WCAP-10526 which proposed that allowed outage es (A0Ts) for a number of safety systems in the Byron Generating Station b i reased from 3 to 7 days, and presents an independent estimate of the chan in isk involved in the A0T extension.

It also presents results of several ensi vity studies. Also included are a survey of methods that can be us d to e luate nuclear power plant technical specifications and a descriptio of pair 'se importance measures.

,. oOCu. T A~ AL.s., - e u..O os oESC, tom

;;,an'A';"

Evaluation of Nuclear Power P ant Technical Specifications Allowed Outage Times Unlimited Probabilistic Risk Assessmen s

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(tag eaget Unclassified

,,,oesT,,,... O,im iso.o Y t.-s ilne reeerto Unclassified i f ~uo.. O., Aces 18 PRICE

UNITED STATES l-NUCLEAR RE 2ULATORY CSMMISSION sucm eovate. ctAss nave mstm eriesruo l

WASHINGTON, D.C. 20666 wfEic.

MaterT ese G47 OFFICIAL BUSINESS PENALTY FOR PRIVATE USE. 6300 120555078877 1 1 A NIRGIGFIGP US NRC ADM-DIV 0F TIDC PCLICY & PUP MGT BR-PDR NUR EG W-501 t

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