Text

Evaluation of Potential Severe Accidents During LOW Power and Shutdown Operations at Surry,Unit 1.Analysis of Core Damage Frequency from Internal Floods During Mid-Loop Operations
	ML18151A168
Person / Time
Site:	Surry
Issue date:	07/31/1994
From:	Kohut P; BROOKHAVEN NATIONAL LABORATORY
To:	; NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES)
References
	CON-FIN-L-1922 BNL-NUREG-52399, NUREG-CR-6144, NUREG-CR-6144-V04, NUREG-CR-6144-V4, NUDOCS 9408180160
	Download: ML18151A168 (464)
	v • d • e

_... /

NUREG/CR-6144 ,

BNL-NUREG-52399 Vol. 4 Evaluation of Potential Severe Accidents During Low Power and Shutdown Operatipns at Surry, Unit 1 lalysis of Core Damage Frequency from Internal Floods During Mid-loop Operations Prepared by P. Kohut Brookhaven National Laboratory Prepared for U.S. Nuclear Regulatory Commission

,I' 9408180160 940731 PDR ADOCK 05000280 P PDR

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NUREG/CR-6144 BNL-NUREG-52399 Vol. 4 Evaluation of Potential Severe Accidents During Low Power and Shutdown Operations at Surry, Unit 1 Analysis of Core Damage Frequency from Internal Floods During Mid-loop Operations Manuscript Completed: January 1994 Date Published: July 1994 Prepared by P. Kohut Brookhaven National Laboratory Upton, NY 11973 Prepared for Division of Safety Issue Resolution Office of Nuclear Regulatory Research U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 NRC FIN L1922

ABSTRACT

T rnditionally, pmbabilistic dsk assessments (PRA) of severn accidents in nuclea, power plants have oonsidernd initiating events potentially occurring only during full power operation. Some previous screening analysis that were performed for other modes of operation suggested that risks during those modes were small relative to full power operation. However, more recent studies and operational experience have implied that accidents during low power and shutdown could be significant contributors to risk.

During 1989, the Nuclear Regulatory Commission (NRC) initiated an extensive program to carefully examine the potential risks during low power and shutdown operations. The program includes two parallel projects being performed by Brookhaven National Laboratory (BNL) and Sandia National Laboratories (SNL). Two plants, Surry (pressurized water reactor) and Grand Gulf (boiling water reactor), were selected as the plants to be studied.

The objectives of the program are to assess the risks of severe accidents initiated during plant operational states other than full power operation and to compare the estimated core damage frequencies, important accident sequences and other qualitative and quantitative results with those accidents initiated during full power operation as assessed in NUREG-1150. The scope of the program includes that of a Level-3 PRA.

A phased approach was used in the Level-1 program. In Phase 1 which was completed in Fall 1991, a coarse screening analysis including internal fire and flood was performed for all plant operational states (POSs). The objective of the Phase 1 study was to identify potential vulnerable plant configurations, to characterize (on a high, medium, or low basis) the potential core damage accident scenarios, and to provide a foundation for a detailed Phase 2 analysis.

In Phase 2, mid-loop operation was selected as the plant configuration to be analyzed based on the results of the Phase 1 study. The objective of the Phase 2 study is to perform a detailed analysis of the potential accident scenarios that may occur during mid-loop operation, and compare the results with those of NUREG-1150. The scope of the Level-1 study includes plant damage state analysis and uncertainty analysis. Volume 1 summarizes the results of the study. Internal events analysis is documented in Volume 2. Internal fire and internal flood analyses are documented in Volumes 3 and 4. A separate study on seismic analysis, documented in Volume 5, was performed for the NRC by Future Resources Associated, Inc.. Volume 6 documents the accident progression, source terms, and consequence analysis.

In the Phase 2 study, system models applicable for shutdown conditions were developed and supporting thermal hydraulic analyses were performed to determine the timing of the accidents and success criteria for systems. Initiating events that may occur during mid-loop operations were identified and accident sequence

~vent trees were developed and quantified. In the preliminary quantification of the mid-loop accident sequences, it was found that the decay heat at which the accident initiating event occurs is an important parameter that determines the success criteria for the mitigating functions, and time available for operator actions. In order to better account for the decay heat, a "time window" approach was developed. In this approach, time windows after shutdown were defined based on the success criteria established for the various methods that can be used to mitigate the accident. Within each time window, the decay heat and accident sequence timing are more accurately defined and new event trees developed and quantified accordingly.

Statistical analysis of the past outage data was performed to determine the time at which a mid-loop condition is reached, and the duration of the mid-loop operation. Past outage data are used to determine the probability that an accident initiating event occurs in each of the time windows. This probability is used in the quantification of the accident sequences .

iii NUREG/CR-6144

Abstract The major objective of the Surry internal flood analysis was to provide an improved understanding of the core damage scenarios arising from internal flood-related events. The mean core damage frequency of the Surry plant due to internal flood events during mid-loop operations is 4.8E-06 per year, and the 5th and 95th percentiles are 2.2E-07 and 1.8E-05 per year, respectively. Some limited sensitivity calculations were performed on three plant improvement options. The most significant result involves modifications of intake-level structure on the canal, which reduced core damage frequency contribution from floods in mid-loop by about 75%.

NUREG/CR-6144 iv

TABLE OF CONTENTS

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1u Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v List of Figures ................................................................... viii List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x Executive Sununary ................................................................ xi Foreword ....................................................................... xix

1. Introduction and Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 1.1 Scope of the Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 1.2 Phase la Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 1.3 Methodology Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 1.4 Internal Event Results ....... -. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 1.5 Organization of the Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 1.6 Plant Visits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 1.7 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

2. Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 2.2 Identification of Flood Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 2.3 Initiating Frequency Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 2.4 Location and Scenario Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 2.5 Plant Response, Accident Sequence Frequencies 2-3 Identification and Interconnection of Flood Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 3.2 Flood Sources, Protection Devices and Floor Drain Systems ........................... 3-1 3.2.1 Turbine Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 3.2.2 Emergency Switchgear Room and Relay Room . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 3.2.3 Auxiliary Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 3.2.4 Safeguard Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4 3.2.5 Containment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5 3.2.6 Mechanical Equipment Room No. #3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6 3.3 Building Layouts, Flood Propagation Pathways, Impact on Equipment . . . . . . . . . . . . . . . . . . . 3-6 3.3.1 Turbine Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6 3.3.2 Emergency Switchgear and Relay Room, Cable Vault and Tunnels . . . . . . . . . . . . . . . . . . 3-7 3.3.3 Auxiliary Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7 3.3.4 Safeguard Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8 3.3.5 Containment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8 3.3.6 Mechanical Equipment Room No. #3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9

4. Initiating Frequency Analysis . . . . . . . . . . . . .. .. . . ....... ... . ... . .. ..... .. ..... .. .. 4-1 4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . .. .. . . ....... ... . ... . .. ..... .. ..... .. .. 4-1 4.2 Turbine Building . . . . . . . . . . . . . . . . . . . . .. .. . . ....... ... . ... . .. ..... .. ..... .. .. 4-1 4.3 Emergency Switchgear and Relay Room . . . .. .. . . ....... ... . ... . .. ..... .. ..... .. .. 4-8 4.4 Auxiliary Building . . . . . . . . . . . . . . . . . . . .. .. . . ....... ... . ... . .. ..... .. ..... .. .. 4-8 V NUREG/CR-6144

Table of Contents (continued) 4.5 Safeguard Area ............................................................ 4-11 4.6 Containment .............................................................. 4-13 4.7 Mechanical Equipment Room No. #3 ........................................... 4-13 4.8 Flood Initiating Frequency - Summary ........................................... 4-14 4.9 References ................................................................ 4-15.

5. Scenario Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 5.2 Event Tree Approach and Assumptions, Time Window Approach ...................... 5-1 5.3 Human Interface Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6 5.3.1 Incorporation of Human Actions into the Plant Model . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7 5.3.2 Routine Actions before an Initiating Event . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8 5.3.3 Methodology for Evaluation of Dynamic Operator Actions and Recoveryctions . . . . . . . . . 5-8 5.3.3.1 Qualitative Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9 5.3.3.2 Quantitative Evaluation ............................................... 5-10 5.3.3.3 Quantification Process ................................................ 5-11 5.3.3.4 Summary .......................................................... 5-12 5.3.4 Actions while at Mid-Loop ................................................ 5-13 5.4 Turbine Building Flood Events - Flood Scenarios 1, 2 ............................... 5-13 5.5 Auxiliary Building Flood Events - Flood Scenarios 3, 4 ............................... 5-15 5.6 Safeguard Area Flood Events - Flood Scenario 5 ................................... 5-17 5.7 Containment Spray Events - Flood Scenario 6 ..................................... 5-18 5.8 Mechanical Equipment Room No. #3. - Flood Scenario 7 ............................ 5-18 5.9 References ................................................................ 5-18

6. Accident Sequence and Sensitivity Calculations . . . . . . . . . . . . . . . . . . . . . . . . ...... .. .... . 6-1 6.1 Accident Sequence Quantifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...... .. .... . 6-1 6.2 Sensitivity Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...... .. .... . 6-1 6.3 Uncertainty Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...... .. .... . 6-2 6.3.1 Sources and Treatment of Uncertainties . . . . . . . . . . . . . . . . . . . . . . . . . ...... .. .... . 6-2 6.3.2 Development of Parameter Distributions . . . . . . . . . . . . . . . . . . . . . . . . . ...... .. .... . 6-3 6.3.3 Quantification of Accident Sequence Uncertainty . . . . . . . . . . . . . . . . . . ...... .. .... . 6-3 6.4 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...... .. .... . 6-3

7. Plant Damage State Analysis. . . . . . . . . . . . . . . . . . . . ... .. .. ..... . . .. . . . ..... . . . . . . . . 7-1 7.1 Definition of Plant Damage State Indicators . . . . . . ... .. .. ..... . . .. . . . ..... . . . . . . . . 7-1 7.2 PDS Analysis, Rules . . . . . . . . . . . . . . . . . . . . . . . . ... .. .. ..... . . .. . . . ..... . . . . . . . . 7-1 7.3 PDS Uncertainty Analysis . . . . . . . . . . . . . . . . . . . . ... .. .. ..... . . .. . . . ..... . . . . . . . . 7-2

8. Conclusions and Summary . . . . . . . . . ............... ....... .. .. . . . . . .. ..... . . .... 8-1 8.1 Plant-Specific Conclusions . . . . . . . . ............... ....... .. .. . . . . . .. ..... . . .... 8-1 8.2 Accident Sequence Conclusions . . . . ............... ....... .. .. . . . . . .. ..... . . .... 8-1 8.3 Uncertainty Considerations . . . . . . . ............... ....... .. .. . . . . . .. ..... . . .... 8-2 8.4 Other Considerations . . . . . . . . . . . . ............... ....... .. .. . . . . . .. ..... . . .... 8-2 Appendix A Equipment Locations ................................................... A-1 NUREG/CR-6144 vi

Appendix B High Level System Fault Trees Table of Contents (continued)

B-1 Appendix C Flow Exceedance Frequency CuJVes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1 Appendix D Dominant Cutsets and Basic Event Importance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-1 Appendix D.1 Dominant Cutsets without Recovery Actions .......................... D-2 Appendix D.2 Basic Event Importances Based on Cutsets without Recovery Actions . . . . . . D-24 Appendix D.3 Dominant Cutsets with Recovery Actions ........................... D-29 Appendix D.4 Basic Event Importance Based on Cutsets with Recovery Actions . . . . . . . . . D-47 Appendix E Basic Event Data ...................................................... E-1

vii NUREG/CR-6144

LIST OF FIGURES 4-1 S~rry N~clear Powe~ :lant Cross Sec~ional View .................................... 4 - 1 6 .

4-2 Crrculatmg Water P1pmg at the Turbme Condenser Waterbox .......................... 4-17 4-3a Flood Dike Arrangements in Turbine Building, ESGR, MER No. #3 .................... 4-18 4-3b Flood Dike Arrangements in Turbine Building, ESGR, MER No. #3 .................... 4-19 5-1 Turbine Building Flood Scenario 1 FlB2WlD6 ..................................... 5-20 5-2 Turbine Building Flood Scenario 1 FlB2WlR6 ..................................... 5-21 5-3 Turbine Building Flood Scenario 1 F1B2W2D6 ..................................... 5-22 5-4 Turbine Building Flood Scenario 1 F1B2W2R6 ..................................... 5-23 5-5 Turbine Building Flood Scenario 1 F1B2W3D6 ..................................... 5-24 5-6 Turbine Building Flood Scenario 1 F1B2W3Rl0 .................................... 5-25 .

5-7 Turbine Building Flood Scenario 1 FlB2W3R6 ..................................... 5-26 5-8 Turbine Building Flood Scenario 1 F1B2W4D6 ..................................... 5-27 5-9 Turbine Building Flood Scenario 1 FlB2W4RlO .................................... 5-28 5-10 Turbine Building Flood Scenario 1 F1B2W4R6 ..................................... 5-29 5-11 Turbine Building Flood Scenario 2 F2B2W1D6 ..................................... 5-30 5-12 Turbine Building Flood Scenario 2 F2B2W1R6 ..................................... 5-31 5-13 Turbine Building Flood Scenario 2 F2B2W2D6 ..................................... 5-32 5-14 Turbine Building Flood Scenario 2 F2B2W2R6 ..................................... 5-33 5-15 Turbine Building Flood Scenario 2 F2B2W3D6 ..................................... 5-34 5-16 Turbine Building Flood Scenario 2 F2B2W3R10 .................................... 5-35 5-17 Turbine Building Flood Scenario 2 F2B2W3R6 ..................................... 5-36 5-18 Turbine Building Flood Scenario 2 F2B2W4D6 ..................................... 5-37 5-19 Turb~e Bu~d~ng Flood Scenar~o 2 F2B2W4R10 .................................... 5 - 3 8 .

5-20 Turbme Buildmg Flood Scenario 2 F2B2W4R6 ..................................... 5-39 5-21 Auxiliary Building Flood Scenario 3 F3R3W1D6 .................................... 5-40 5-22 Auxiliary Building Flood Scenario 3 F3R3W1R6 .................................... 5-41 5-23 Auxiliary Building Flood Scenario 3 F3R3W2D6 .................................... 5-42 5-24 Auxiliary Building Flood Scenario 3 F3R3W2R6 .................................... 5-43 5-25 Auxiliary Building Flood Scenario 3 F3R3W3D6 .................................... 5-44 5-26 Auxiliary Building Flood Scenario 3 F3R3W3Rl .................................... 5-45 5-27 Auxiliary Building Flood Scenario 3 F3R3W3R6 .................................... 5-46 5-28 Auxiliary Building Flood Scenario 3 F3R3W4D6 .................................... 5-47 5-29 Auxiliary Building Flood Scenario 3 F3R3W4Rl .................................... 5-48 5-30 Auxiliary Building Flood Scenario 3 F3R3W4R6 .................................... 5-49 5-31 Auxiliary Building Flood Scenario 4 F4R3W1D6 .................................... 5-50 5-32 Auxiliary Building Flood Scenario 4 F4R3W1R6 .................................... 5-51 5-33 Auxiliary Building Flood Scenario 4 F4R3W2D6 .................................... 5-52 5-34 Auxiliary Building Flood Scenario 4 F4R3W2R6 .................................... 5-53 5-35 Auxiliary Building Flood Scenario 4 F4R3W3D6 .................................... 5-54 5-36 Auxiliary Building Flood Scenario 4 F4R3W3Rl .................................... 5-55 5-37 Auxiliary Building Flood Scenario 4 F4R3W3R6 .................................... 5-56 5-38 Auxiliary Building Flood Scenario 4 F4R3W4D6 .................................... 5-57 5-39 Auxiliary Building Flood Scenario 4 F4R3W4Rl .................................... 5-58 5-40 Auxiliary Building Flood Scenario 4 F4R3W4R6 .................................... 5-59 5-41 Safeguard Building Flood Scenario 5 F5R3W1D6 ................................... 5-60 5-42 Safeguard Building Flood Scenario 5 F5R3W1R6 ................................... 5-61 NUREG/CR-6144 viii

List of Figures (continued) 5-43 Safeguard Building Flood Scenario 5 F5R3W2D6 ................................... 5-62 5.44 Safeguard Building Flood Scenario 5 F5R3W2R6 ................................... 5-63 5-45 Safeguard Building Flood Scenario 5 F5R3W3D6 ................................... 5-64 5-46 Safeguard Building Flood Scenario 5 F5R3W3R10 .................................. 5-65 5-47 Safeguard Building Flood Scenario 5 F5R3W3R6 ................................... 5-66 5-48 Safeguard Building Flood Scenario 5 F5R3W4D6 ................................... 5-67 5-49 Safeguard Building Flood Scenario 5 F5R3W4R10 .................................. 5-68 5-50 Safeguard Building Flood Scenario 5 F5R3W4R6 ................................... 5-69 5-51 Containment Spray Event Tree F6B2W1D6 .............. .512....................... 5-70 5-52 Containment Spray Event Tree F6R4W1R6 ....................................... 5-71 5-53 Containment Spray Event Tree F6R4W2D6 ....................................... 5-72 5-54 Containment Spray Event Tree F6R4W2R6 ....................................... 5-73 5-55 Containment Spray Event Tree F6R4W3D6 ....................................... 5-74 5-56 Containment Spray Event Tree F6R4W3R10 ...................................... 5- 75 5-57 Containment Spray Event Tree F6R4W3R6 ....................................... 5- 76 5-58 Containment Spray Event Tree F6R4W4D6 ....................................... 5-77 5-59 Containment Spray Event Tree F6R4W4R10 ...................................... 5-78 5-60 Containment Spray Event Tree F6R4W4R6 ....................................... 5-79 5-62 Mechanical Eq Rm 3 Flood Scenario 7 F7B2W1R6 .................................. 5-80 5-63 Mechanical Eq Rm 3 Flood Scenario 7 F7B2W2D6 ................................. 5-81 5-64 Mechanical Eq Rm 3 Flood Scenario 7 F7B2W2R6 .................................. 5-82 5-65 Mechanical Eq Rm 3 Flood Scenario 7 F7B2W3D6 ................................. 5-83 5-66 Mechanical Eq Rm 3 Flood Scenario 7 F7B2W3R10 ................................. 5-84 5-67 Mechanical Eq Rm 3 Flood Scenario 7 F7B2W3R6 .................................. 5-85 5-68 Mechanical Eq Rm 3 Flood Scenario 7 F7B2W4D6 ................................. 5-86 5-69 Mechanical Eq Rm 3 Flood Scenario 7 F7B2W4R10 ........... , ..................... 5-87 5-70 Mechanical Eq Rm 3 Flood Scenario 7 F7B2W4R6 .................................. 5-88 ix NUREG/CR-6144

LIST OF TABLES Table S-1 Summary of Point Estimate CDFs for Flood Events (/yr) .............................. xvi S-2 Results of the Flood Uncertainty Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii S-3 Core Damage Frequencies for Flood Events Sensitivity Analysis . . . . . . . . . . . . . . . . . . . . . . . xviii 1-1 Internal Flood Events, Summary of Coarse Screening Analysis ...................... *. . . 1-4 1-2 Internal Event Analysis Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5 3-1 Summary of Coarse Screening Analysis ........................................... 3-10 4-1 Turbine Building Flood Events, Circulating Water System ............................ 4-21 4-2 Fractional Distribution of CW Events and Recovery Characteristics . . . . . . . . . . . . . . . . . . . . 4-22 4-3 Service Water System Flood Events ............................................. 4-23 4-4 Auxiliary Building Flood Events ................................................ 4-25 4-5 Containment Building Spray Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-27 4-6 Flood Initiating Frequency, Mechanical Equipment Room #3 . . . . . . . . . . . . . . . . . . . . . . . . . 4-28 4-7 Flood Initiating Frequency, Summary ............................................ 4-29 5-1 Success Criteria for Mitigating Features .......................................... 5-89 5-2 Definition and Characterization of Time Windows .................................. 5-90 5-3 Definition of Dynamic Human Actions, Flood Initiating Events ......................... 5-92 5-4 Evaluation of Dynamic Human Actions, Flood Initiating Events ....................... 5-103 6-1 Evaluation of Recovery Human Actions, Flood Initiating Events . . . . . . . . . . . . . . . . . . . . . . . . 6-4 6-2 Core Damage Frequencies of Flood Event Trees Flood in Turbine Building, Two-Unit SBO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6 6-3 Core Damage Frequencies of Flood Event Trees Flood in Turbine Building, Two Unit SBO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-8 6-4

~::i:~::::;q;:~~:go~ -~l~~~ -~~e~~ -~r~~\ ...................................

6-5 Core Damage Frequencies of Flood Event Trees 6 _10

Flood in Auxiliary Building .................................................... 6-12 6-6 Core Damage Frequencies of Flood Event Trees Flood in Safeguard Area ...................................................... 6-13 6-7 Core Damage Frequencies of Flood Event Trees, Spray in Containment .................. 6-14 6-8 Core Damage Frequencies of Flood Event Trees, Flood in Mechanical Equipment Room No. #3, Two-Unit SBO ................................................................. 6-16 6-9 Core Damage Frequencies of Flood Event Trees, Sensitivity Cases ...................... 6-17 6-10 Core Damage Frequencies of Flood Event Trees, Uncertainty Results .................... 6-18 7-1 Plant Damage State Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3 7-2 Uncertainty Analysis, Flood Plant Damage States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4 8-1 Core Damage Frequencies for Flood Events, Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4 8-2 Core Damage Frequencies for Flood Events, Uncertainty Results . . . . . . . . . . . . . . . . . . . . . . . 8-5 8-3 Core Damage Frequencies for Flood Events, Sensitivity Cases, Summary . . . . . . . . . . . . . . . . . . 8-6 NUREG/CR-6144 X

EXECUTIVE

SUMMARY

'Ibis report presents the results of an internal flood event analysis of the Surry Power Station Unit 1 for accidents initiated during mid-loop operations. This program was performed by Brookhaven National Laboratory as part of a full-scope internal event study for the Low Power and Shutdown program of the U.S.

Nuclear Regulatory Commission Office of Nuclear Regulatory Research (RES). The first phase of the Low Power and Shutdown study included a Level 1 internal event probabilistic risk assessment and a fire and flood analysis. Preliminary results were obtained for accident initiated during low power and shutdown operations.

The first phase analysis also provided insights on potential accident scenarios and potentially vulnerable configurations during this particular operating mode. This portion of the program was completed in November 1991.

The second phase of the Low Power and Shutdown program has focused on a detailed analysis of mid-loop operation. 'Ibis operating mode was deemed to be the most important risk contributor, based on the Phase 1 analysis as well as the number of incidents which occurred in mid-loop operations. 'Ibis report documents the results and findings of the Phase 2 internal flood analysis. The results of the Level one internal event and fire analyses are reported separately in companion reports.

Surry Unit 1 was chosen as a representative pressurized water reactor (PWR) to be analyzed. The Surry plant was previously studied and analyzed in the Reactor Safety Studyl1l and NUREG-1150[2] for full power operation. The plant site contains two PWRs each rated at 788 MW (electrical) capacity located near Surry, Virginia.

Objectives The overall objective was to perform an analysis to support the Low Power and Shutdown program in developing a Level 1 internal flood event analysis for the shutdown operations of the Surry plant.

Corresponding Level 1 internal event, fire and seismic analyses have also been performed and documented in separate volumes of the reports. Specific objectives of the study were to identify pertinent flood events with respect to the mid-loop operating modes, develop and quantify potential risk-significant scenarios, and identify potential and significant system failures as applicable to the Surry Power Station.

'Ibis report presents the Level 1 internal flood event analysis including accident scenario development, determination of spatial interconnections and their effects, estimation of the frequencies of internal flood events during mid-loop operations, modeling of accident sequences and determination of the frequency of scenarios involving system failures leading to severe core damage. Core damage is defined as a significant core uncovery with fuel cladding failures. At the decay heat level during mid-loop operation, cladding failures are likely to occur when the water level in the core region is reduced to about 2.5 ft above the bottom of the reactor core. If reflooding of the core is not done immediately, fission product release from the fuel is expected to result.

Approach The plant configuration may constantly change during low power and shutdown operating modes. 'Ibis necessitated the definition of different outage types or plant operating states (POSs). In order to properly account for the time dependence of the decay heat, "time windows" were developed representing different decay heat levels combined with window-dependent success criteria. In each time window a probabilistic xi NUREG/CR-6144

Executive Summary model was developed that included identification of initiating events, development and quantification of system fault and accident event trees, and calculation of uncertainties.

Outage Types, Plant Operational States, Time Windows Similar to the internal analysis, the plant outages were grouped into the following different types: refueling, drained maintenance, and non-drained-maintenance. Mid-loop is the POS in which the reactor coolant level is lowered to the mid-plane of the hot leg. Three mid-loop POSs were selected for detailed analysis. Two of the POSs occur in refueling outage, POSs R6 and RlO, and one in drained maintenance outage, POS D6.

POS R6 represents a mid-loop operation starting early in the refueling outage, while POS RlO takes place at a relatively later time in a refueling outage due to additional maintenance actions. POS D6 is characterized by the highest decay heat level among the three mid-loop POSs since it could be required by unplanned maintenance activities when at full power.

The time dependence of the decay heat level and changes in success criteria during the shutdown operation was modeled using four time windows. For POSs R6 and D6, all four time windows were used; while for POS RlO, only time windows 3 and 4 were needed.

Initiating Event Analysis In order to develop and identify the root causes of various flood events, industry experience was reviewed. A plant-specific analysis was also performed to derive location-dependent initiating frequencies. The operating experience was reviewed with respect to its applicability to the Surry Power Station. This approach insured that any operating incident that has occurred or was studied in previous analyses was included and considered in the present study. The flood initiating frequencies were obtained based on the statistical analysis of actual operating events occurring at similar installations.

System Analysis, Flood Scenarios, Event Tree Development The fault tree models developed for the internal event low power and shutdown study were reviewed and used*

in the internal flood event analysis. The system models affected by specific flood scenarios were appropriately modified to take into account the potential damage to equipment located in flood areas.

Specific human errors associated with the diagnosis of specific flood scenarios and with the actions required by the plant operator were developed based on the approach used in the internal event study. Human error probabilities (HEPs) were developed in two steps. In the first step, each flood event scenario was qualitatively defined in terms of required action, important factors affecting operator performance, and the consequences of the action not being successful. The second step contained the quantification process.

The quantitative evaluation of HEPs was done using the success likelihood method with seven performance shaping factors. The numerical model was calibrated by HEPs obtained from probabilities developed for well-established human actions.

Flood accident scenarios were developed based on information collected during a plant visit and walk-down, discussions with operating personnel, and review of the plant drawings. The flood accident scenarios were compared and mapped with some modifications to the previously developed internal event accident event NUREG/CR-6144 xii

Executive Summary

trees. This enabled a probabilistic risk analysis of the various flood scenarios using the same methodology as used for the internal event analysis.

Quantification The accident sequence quantification was based on the flood event trees and the quantification of the core damage sequences was accomplished with the IRRAS[3l code. The truncation limits were set at l.OE-10 for the system and event tree analyses at the cutset level.

Results and Conclusions The major objective of the Surry internal flood analysis was to provide an improved understanding of the risk arising from internal flood-related events. The present analysis resulted in that the most dominant contributors to core damage due to internal floods are accident scenarios initiated in the Turbine Building leading to the draining of the intake canal. This potentially could result in a flood encompassing the plant Emergency Switchgear Rooms (ESGR) leading to a two unit loss of all emergency power (Fl and F2 scenarios).

The main results of the flood analysis are presented in Table S-1, listing the point estimate core damage frequencies of the analyzed operating states. The most dominant flood scenario, 85% of the total CDF, is the one occurring in the Turbine Building and overflowing the flood dikes at the unit ESGR causing the loss of all emergency power for the two *units (Fl and F2 scenarios).

The Turbine Building internal flood accident scenarios account for approximately 85% of the total core damage frequency (CDF) due to internal floods. This result is mainly due to the specific features of the Surry circulating water system and may not be applicable to other plants. The second most dominating flood scenario involves flooding of the Safeguard/Auxiliary Building in combination with the unavailability of the Refueling Water Storage Tank (RWST). The contribution of these scenarios ( F4 and F5) is approximately 13% of the total internal CDF. Again, these specific findings may not be generalized to other plants due to the plant specific nature of the actual evolvement of these accident scenarios.

Plant-Specific Conclusions The internal flood CDF is dominated by Turbine Building flood events. These events are primarily initiated by either valve or expansion joint failures in the main inlet lines of the circulating water system. These failures may lead to pipe ruptures upstream of the condenser water box and inlet valves. At Surry the circulating

water system is gravity fed from a very large capacity intake canal and its isolation may not be accomplished in a timely manner. This is in contrast with other common design arrangement where dedicated pumps provide the required cooling water flow through the system. In these designs, stopping the pumps would effectively isolate the system limiting potential water outflow.

The potential draining of the intake canal inventory in the Turbine Building is dominant due to a plant-specific spatial interdependence. For both units the Emergency Switchgear Rooms are located in the Service Building on the same elevation as the Turbine Building basement. These areas are separated by a fire door with 2 foot high flood dikes in front of them. A large scale flood could potentially overflow the dikes and enter into the two unit ESGR, leading to the potential loss of emergency power in both units, including the

xiii NUREG/CR-6144

Executive Summary loss of Residual Heat Removal (RHR) stub busses. The normal off-site power supply to the plant would not be affected since the normal SGR is located at higher elevation in the Service Building.

Another important contributor to the internal flood CDF is due to flood events originated or entering into the Auxiliary Building. These flood scenarios, mainly from supply pipe ruptures from the RWST, result in the loss of all Component Cooling Water (CCW) and consequently the RHR function at the plant. This coupled with the unavailability of the RWST inventory to be injected into the reactor core leads to core damage. Again, the plant-specific spatial arrangement of piping and equipment is the main reason for the development of the accident scenario and its risk significance.

Accident Sequence Conclusions The most dominant sequences, F1B2W4R10 - 4, F1B2W2R6 - 4 and F1B2W3R6 - 3, represent large scale flooding of the ESGR initiated in the Turbine Building coupled with the inability to recover. The flood in the ESGR disables all equipment required for feed and bleed operations and thus only reflux cooling and/or gravity feed options may be utilized. However, the primary coolant loops are isolated 70 % in time window 2 and 100% in time windows 3 and 4, respectively. In these sequences the pressurizer safety valves are not removed which prevents the use of the gravity feed options. Therefore, these sequences are effectively nonrecoverable except by some "ad hoc" means, for which no credit was given in these analyses.

The second group of accident sequences, F2B2W4R10 - 4, F2B2W2R6 - 4 and F2B2W3R6 - 3, are similar to the first group with the addition of the postulated difficulties in diagnosing accident conditions due to potential damage to the DC panels (instrumentation signals) in the ESGR.

The next most important group of sequences are associated with Auxiliary Building floods, F5R3W2R6 - 5 and F4R3W2R6 - 5. In both cases, the flood is initiated by a pipe rupture draining a large fraction of the RWST inventory into the Safeguard or Auxiliary Building. The flood would eventually collect in the Auxiliary Building basement leading to a loss of component cooling water and subsequently a loss of RHR event.

Forced feed and bleed is unavailable since the RWST must be isolated. In these sequences, either the reactor coolant system (RCS) loops are isolated or other malfunction prevents the utilization of the steam generators through the reflux cooling technique.

Uncertainty Considerations The probabilistic assessment and accident sequence modeling of the plant involves the combination of many individual events representing initiating frequencies, component and operator failures. The core damage frequency estimates are derived by using these individual events which, of themselves, frequently have significant uncertainties. The probabilistic accident sequence model may be used to develop importance measures and to calculate the appropriate uncertainty distributions of the individual and the sum of the accident sequence core damage frequencies.

The main results of the uncertainty analysis are shown in Table S-2, indicating the uncertainty bounds of the core damage frequency due to internal floods. The important measures of the uncertainty distribution are the 5%, mean and 95% values at 2.2E-07, 4.SE-06 and l.SE-05/yr, respectively.

NUREG/CR-6144 xiv

Executive Summary Other Considerations Important recovery options are related to the long term operation of the reflux cooling method by replenishing the steam generators and to the establishment of backup charging flow from Unit 2. The analysis also allowed credit for uncertainty in the success criterion used for the r~flux cooling.

Io general, the core damage frequency contribution from flood events during mid-loop operation is relatively significant and is dominated by potential flood events into the ESGR coupled with loop isolation during time windows 2, 3, and 4.

Sensitivity calculations were also completed for a number of proposed improvement options and the point estimate CDF results are summarized in Table S-3. The most effective analyzed options are the installation of watertight doors on the ESGR (Option 2) and modification of the intake str:ucture (Option 3), which are capable of reducing the CDF contribution in mid-loop by 57% and 75%, respectively i.e., 2.2E-06/yr and 1.3E-06/yr from the base case of 5.lE-06/yr.

References

1. Reactor Safety Study, An Assessment of Accident Risks in U.S. Commercial Nuclear Power Plants, U.S.

Nuclear Regulatory Commission, published as WASH-1400, 1975.

2. Reactor Risk Reference Document, NUREG-1150, U.S. Nuclear Regulatory Commision, 1987.

NUREG/CR-4550, Volume 3, Revision 1, Part 1, SAND86-2084, Analysis of Core Damage Frequency:

Suny Unit 1 Internal Events.

NUREG/CR-4550, Volume 3, Revision 1, Part 2, SAND86-2084, Analysis of Core Damage Frequency:

Suny Unit 1 Internal Events Appendices.

NUREG/CR-4550, Volume 3, Revision 1, Part 3, SAND86-2084, Analysis of Core Damage Frequency:

Suny Unit 1 External Events.

3. K. D. Russel, et. al., "Systems Analysis Programs for Hands-On Integrated Reliability Evaluations (SAPHIRE)" NUREG/CR-6116, EGG-2716, Volume 2, "Integrated Reliability and Risk Analysis System (IRRAS), Reference Manual", July 1994.

xv NUREG/CR-6144

Executive Summary Table S-1 Summary of Point Estimate CDFs for Flood Events (/yr)

Scenario Core Damage Frequency w/ Recovery POS6 POS 6 POS 10 Total Refueling Drained Refueling Turbine Building 1.9E-06 9.3E-08 1.SE-06 3.SE-06 Fl Turbine Building 4.SE-07 2.2E-08 3.6E-07 8.3E-07 F2 Auxiliary Building 4.7E-08 4.3E-08 1.ZE-08 1.0E-07 F3 Auxiliary Building 1.6E-07 5.7E-08 6.7E-08 2.8E-07 F4 Safeguard Area 2.0E-07 8.9E-08 9.4E-08 3.8E-07 F5 Spray in Containment - - - -

F6 Mechanical Equipment 1.0E-08 1.SE-08 7.SE-09 3.3E-08 Room No. #3 - F7 I Total-Flood I 2.SE-06 I 3.2E-07 I 2.0E-06 I 5.lE-06 I

Total-Internal Events 1.SE-06 3.lE-06 3.lE-07 4.9E-06 NUREG/CR-6144 xvi

Executive Summary Table S-2 Results of the Flood Uncertainty Analysis Flood Analysis Flood Analysis Internal Events Analysis Mid-Loop Operation Mid-Loop Operations (CDP/yr while at mid-loop) (CDP/yr while at mid-loop)

Mean

. 4.8E-06 4.9E-06 5th Percentile 2.2E-07 4.8E-07 50th Percentile 1.7E-06 2.lE-06 95th Percentile 1.8E-05 1.SE-05 Error Factor 9.0 5.7 Point Estimate 5.lE-06 5.lE-06

NUREG-1150 reported no flood sequences surving the cutoff criterion of 1.0E-08.

xvii NUREG/CR-6144

Executive Summary Table S-3 Core Damage Frequencies for Flood Events Sensitivity Analysis Core Damage Frequency Per Year Options (with recovery)

POS6 POS6 POS 10 Total Drained Refueling Refueling A CDF (Base-Total) 1 - Relocation of Sump Pump 2.8E-07 1.8E-06 1.3E-06

3.4E-06 1.8E-06 Power Supply 2 - Watertight Door on ESGR 2.5E-07 1.2E-06 7.lE-07 2.2E-06 2.9E-06 3 - Modification of Intake Level 2.3E-07 7.5E-07 3.lE-07 1.3E-06 3.SE-06 Structure Base Case-Internal Flood 3.2E-07 2.8E-06 2.0E-06 5.lE-06 -

Events NUREG/CR..:6144 xviii

Executive Summary FOREWORD (NUREG/CR-6143 and 6144)

Low Power and Shutdown Probabilistic Risk Assessment Program Traditionally, probabilistic risk assessments (PRA) of severe accidents in nuclear power plants have considered initiating events potentially occurring only during full power operation. Some previous screening analysis that were performed for other modes of operation suggested that risks during those modes were small relative to full power operation. However, more recent studies and operational experience have implied that accidents during low power and shutdown could be significant contributors to risk.

During 1989, the Nuclear Regulatory Commission (NRC) initiated an extensive program to carefully examine the potential risks during low power and shutdown operations. The program includes two parallel projects performed by Brookhaven National Laboratory(BNL) and Sandia National Laboratories(SNL), with the seismic analysis performed by Future Resources Associates. Two plants, Surry (pressurized water reactor) and Grand Gulf (boiling water reactor), were selected as the plants to be studied.

The objectives of the program are to assess the risks of severe accidents due to internal events, internal fires, internal floods, and seismic events initiated during plant operational states other than full power operation and to compare the estimated core damage frequencies, important accident sequences and other qualitative and quantitative results with those accidents initiated during full power operation as assessed in NUREG-1150.

The scope of the program includes that of a level-3 PRA.

The results of the program are documented in two reports, NUREG/CR-6143 and 6144. The reports are organized as follows:

For Grand Gulf:

NUREG/CR-6143 - Evaluation of Potential Severe Accidents during Low Power and Shutdown Operations at Grand Gulf, Unit 1 Volume 1: Summary of Results .

Volume 2: Analysis of Core Damage Frequency from Internal Events for Operational State 5 During a Refueling Outage Part 1: Main Report Part lA: Sections 1 - 9 Part lB: Section 10 Part lC: Sections 11 - 14 Part 2: Internal Events Appendices A to H Part 3: Internal Events Appendices I and J Part 4: Internal Events Appendices K to M Volume 3: Analysis of Core Damage Frequency from Internal Fire Events for Plant Operational State 5 During a Refueling Outage

xix NUREG/CR-6144

Volume 4: Analysis of Core Damage Frequency from Internal Flooding Events for Plant

Operational State 5 During a Refueling Outage Volume 5: Analysis of Core Damage Frequency from Seismic Events for Plant Operational State 5 During a Refueling Outage Volume 6: Evaluation of Severe Accident Risks for Plant Operational State 5 During a Refueling Outage Part 1: Main Report Part 2: Supporting MELCOR Calculations For Surry:

NUREG/CR-6144- Evaluation of Potential Severe Accidents during Low Power and Shutdown Operations at Surry Unit-1 Volume 1: Summary of Results Volume 2: Analysis of Core Damage Frequency from Internal Events during Mid-loop Operations Part 1: Main Report Part lA: Chapters 1 - 6 Part lB: Chapters 7 - 12 Part 2: Internal Events Appendices A to D Part 3: Internal Events Appendix E Part 3A: Sections E.1 - E.8 Part 3B: Sections E.9 - E.16 Part 4: Internal Events Appendices F to H Part 5: Internal Events Appendix I Volume 3: Analysis of Core Damage Frequency from Internal Fires during Mid-loop Operations Part 1: Main Report Part 2: Appendices Volume 4: Analysis of Core Damage Frequency from Internal Floods during Mid-loop Operations Volume 5: Analysis of Core Damage Frequency from Seismic Events during Mid-loop Operations Volume 6: Evaluation of Severe Accident Risks during Mid-loop Operations Part 1:

Main Report Part 2: Appendices NUREG/CR-6144 xx *

.1.1 Scope of the Study

1. INTRODUCTION AND OVERVIEW The study documented in this report is the continuation of the internal event Level 1 work of the low power and shutdown accident frequency analysis of the Surry Nuclear Power Plant. It contains the results of the internal flood analysis and excludes external flood events. The work was performed by Brookhaven National Laboratory for the Nuclear Regulatory Commission Office of Nuclear Regulatory Research. The main objective of the study is to determine the internal flood contribution to the core damage frequency estimates of a pressurized water reactor during low power and shutdown conditions. The study has concentrated on the various operational conditions during shutdown operation, determined the dominant flood accident sequences and important scenarios, and analyzed the contribution of the various accident scenarios in terms of their importance to the core damage frequency and risk.

The main objectives of the internal flood analysis are:

to assess the frequency of severe accidents initiated by internal flood events focusing on specific shutdown operational states

to compare the estimated core damage frequencies,important accident scenarios and dominant contributors and the main results to comparable accident events of the full power operations as assessed in the NUREG-1150 study for Surry Unit 1.

1.2 Phase la Results In the Phase la internal event study, a coarse internal flood screening analysis was completed. The study was limited only to a few plant operational states , involving mid-loop operation, i.e., POS 6 in refueling and drained maintenance and POS 10 in refueling mode of operation. The coarse screening analysis identified "I

the most vulnerable flood areas and screened out certain areas that do not have significant impact. Spatial interaction between connected areas and also the effect of flood on various equipment has been conservativel:y considered. Simplified flood event trees were developed and quantification was accomplished by assuming certain time evolution of the accident scenarios and the condition of the containment.

The main results of the coarse screening analysis are summarized in Table 1-1. The core damage frequency contribution was estimated to be significant for the Turbine Building, Safeguard Area, and for certain scenarios in the Auxiliary Building and the Emergency Switchgear and Relay Room. It was estimated that all of the internal flood events would lead to early cored damage with an open containment.

1.3 Methodology Overview The methodology of the internal flood event analysis is based on previously utilized approaches in probabilistic safety analysis works, especially the methodology used in the full power study of NUREG-1150 and the plant-specific Individual Plant Examination (IPE) study of the Surry Plant. The basic steps in the analysis involve the following:

identification of flood areas spatial interaction of flood areas 1-1 NUREG/CR-6144

Introduction and Overview

flood event frequency analysis flood damage states

location and scenario identification

plant response analysis accident scenarios, sequences, and frequencies The internal flood analysis utilized the system fault trees and event trees developed for the internal event study. The flood events were categorized as to their effect on the residual heat removal system and were mapped to the corresponding internal event tree. The event trees were modified to take into account the specific accident evolution of the flood event. In addition, the system fault trees were also modified according to the effects of the flood on equipment used to mitigate the accident. The relevant human error probabilities were also modified as timing and potential spatial interactions complicated the accident progression.

1.4 Internal Event Results The Phase 2 flood analysis documented in this report relied on the system fault and event trees developed for the internal event study. That portion of the work documented in Reference 1 was the basis of the numerical quantification of the *system and accident progression portion of the internal flood analysis. For further reference the main results of the Phase 2 internal event analysis are presented in Table 1-2. The most dominant operating state from the perspective of risk contribution is the POS 6 drained maintenance configuration, since the number of mitigating systems or alternate heat removal methods are most limited in this POS.

1.5 Organization of the Report The report is organized along the methodological steps of the internal flood analysis. In the next section, the methodology of the flood event analysis is discussed in more detail. In Section 3, the flood areas are identified and the effect of floods is investigated. In Section 4, the flood frequency is derived in each specific location for the respective POSs. Section 5 contains the scenario development, and discussion about the event trees used to analyze flood accident scenarios as well as discussion in the modification to the system fault trees and the internal event trees. Section 6 presents the quantification and the results. The final section discusses the insights and the conclusion of the internal flood study.

1.6 Plant Visits In order to become familiar with the specific plant locations as well as assess the potential for various flood damage scenarios and evaluate the design capabilities of the flood protection devices, a team of analysts undertook numerous site visits. These plant visits were extremely valuable in establishing the analytical work and relating the various assumptions used in the study. Special emphasis was put on investigating the potential spatial interconnections between various plant locations. The effectiveness of certain flood protection devices was also evaluated. Discussion with plant personnel about flood preventive measures, and potential procedural and hardware improvements was also helpful.

1-2 NUREG/CR-6144

1.7 References Introduction and Ovetview

l. Chu, T-L., et.al., "Evaluation of Potential Severe Accidents During Low Power and Shutdown Operations at Surry Unit-1: Analysis of Core Damage Frequency from Internal Events During Mid-Loop Operations." NUREG/CR-6144, Volume 2, June 1994.

2. Virginia Power, Surry Nuclear Power Plant, Individual Plant Examination Program, Appendix E:

Internal Flooding.

Internal Flooding Analysis for the Individual Plant Examinations, Supplemental Report, Surry Units 1 and 2, Virginia Electric and Power Company, November 1991.

1-3 NUREG/CR-6144

Table 1-1 Internal Flood Events Summary of Coarse Screening Analysis Areas or Building Lowest Frequency of Flood Seq.# CDF Timing Containment Elevation /yr POS 6 Refueling Emergency 9'-6" 3.00E-05 3 Low Early Open Switchgear and Relay Room 4 High Early Open Containment -27'-7" 6.18E-06 4 Low Early Open 7 Low Early Open Auxiliary Building 2' 1.88E-05 3 Low Early Open 5 High Early Open Safeguard Area -27'-7" l.SOE-05 High Early Open Turbine Building 9'-6" 7.52E-05 High Early Open

Table 1-2 Internal Event Analysis Summary I I Initiating Event I IE Frequency II Core-Damage Frequency (per year)

I

1. Loss of RHR R6 RlO D6 Total RHR2A-Over Draining 1.6E-02/Demand 1.BE-7 5.3E-8 2.6E-7 4.9E-7 RHR2B-Failure to Maintain Level 1.2E-05/hr 2.lE-08 2.0E-8 2.9E-8 7.0E-8 RHR3-Non-Recoverable Loss of RHR 4.lE-06/hr 1.5E-7 8.4E-9 3.0E-7 4.6E-7 RHR4-Non-Recoverable Loss or Operating Train of RHR 5.3E-06/hr 7.6E-9 t.2E-9 2.3E-8 3.2E-8 RHR5-Recoverable Loss of RHR 2.lE-05/hr 4.0E-8 4.lE-09 9.3E-8 1.4E-7

2. LOOP-Loss of Offsite Power - 7.0E-06/hr Ll-Both lH and 1J Energized 6.2E-06/hr 3.3E-7 7.0E-8 7.6E-7 1.2E-6 L2-1H and 2H energized, not 1J 7.4E-07/hr 1.0E-7 1.3E-8 1.7E-7 2.9E-7 L3-1H energized, not lJ, unit 2 blackout 3.BE-08/hr 4.2E-8 1.3E-8 9.9E-8 1.5E-7 Bl-Unit 1 Black Out 2.0E-08/hr 4.BE-8 1.lE-8 1.7E-7 2.3E-7 B2-2 Unit Blackout 3.2E-09/hr 3.BE-8 4.2E-8 1.lE-7 1.9E-7

3. 4KV-Loss or 4kv Bus 2.lE-05/hr 1.4E-7 1.9E-8 2.4E-7 4.0E-7

4. VITAL-Loss of Vital Bus 5.6E-06/hr 2.SE-8 5.lE-9 7.3E-8 1.lE-7

5. AIR-Loss or Outside Instrument Air 2.lE-6/hr 7.9E-10 - 3.2-9 4.0E-9

6. CCW-Loss of CCW 3.BE-06/hr 6.3E-8 1.lE-10 2.lE-7 2.7E-7

7. SWGR-Loss of Emergency Switchgear Room Cooling 1.SE-08/hr 3.6E-8 1.2E-8 7.4E-8 l.2E-7

8. ESFAS-lnadvertent Safety Feature Actuation 1.lE-04/hr 2.7E-7 2.7E-8 6.SE-7 9.SE-7

9. Dilute-Boron Dilution (estimated CDF) 2.0E-07/hr 6.SE-08 I TOTAL I I II l.5E-6 I 3.0E-7 I 3.3E-6 I 5.lE-6*

I

Not including boron dilution

2. METHODOLOGY 2.1 Introduction The coarse screening analysis of the potential internal flood events at the Surry Power Plant identified several scenarios with relatively high risk significant contributions. In the second phase of the flood analysis, a comprehensive detailed evaluation of the specific flood scenarios was undertaken based on the results of the coarse screening study. The analysis initially concentrated on mid-loop operations (POS 6 refueling and drained maintenance, POS 10 refueling) an~ the internal flood initiated contribution to the CDF has been quantified in these operating states only.

The mid-loop operational mode was selected, since the RCS inventory is at its lowest level with appreciable decay heat level. In the internal flood analysis specific attention has been paid to flood prevention devices which protect against or limit the consequences of any flood damage including floor plugs, dikes and reverse flow preventers.

The methodology is based on previously utilized approaches in previous probabilistic risk assessment work including the NUREG-1150 study and the recently completed IPE study of the Surry plant. Both of these studies provided large amounts of information required for the flood analysis. The information contained in these studies was confirmed and used whenever it was deemed appropriate.

Specific effort was made to identify potential flood propagation pathways between interconnected areas. The interconnection may be caused by doors or stairways, floor drains or other openings. It was assumed that immersion of equipment is the predominant failure mechanism due to flood and the effect of spraying or splashing is not considered presently except in the containment with respect to the operation of the RHR system.

The methodology of the flood analysis may be summarized as follows with the detailed description of each area given in subsequent sections:

identification of flood areas interconnection between flood areas

internal flood frequency analysis flood damage states

location and scenario identification

plant response analysis flood event trees, system fault tree modification accident sequence quantification 2.2 Identification of Flood Areas The areas defined in the coarse screening analysis were used as the basis for the second phase effort. The potential pathways for flood propagation were identified using the information obtained during a plant visit as well as information available from the NUREG-1150 and IPE studies. The spatial interactions and the 2-1 NUREG/CR-6144

Methodology various pathways between high risk areas i.e., Turbine Building and Emergency Switchgear Room and

Auxiliary Building were inspected and evaluated for potential flood damage.

2.3 Initiating Frequency Analysis The initiating frequency data was developed based on actual flooding events and updated to include plant-specific features and data. The data was gathered from various sources including the IPE Surry flood analysis, industry sources, licensing event reports {LERs).

In some cases, plant specific models were developed especially with regard to the most important circulating water (CW) and service water (SW) lines in the Turbine Building. These two sources of flood are estimated to dominate the risk, requiring special treatment. The most dominant failure mechanism for large pipes is pipe rupture due to water hammer events.

Generic pipe failure data and models were used when plant-specific data was unavailable with the exception of the CW and SW lines. The effects of flood barriers and other mitigating mechanisms were also considered in the development of damage states.

The equipment damage due to internal flood was determined as a function of flood level. Similar to the coarse screening analysis, the effect of spraying, splashing, and dripping is initially neglected. The flood level depends on various factors such as the rate of leaking, area of interconnections, drainage pathways, and potential mitigating actions.

In order to take these factors into account, simple flood damage categories or damage states were developed.

The damage states effectively incorporate the time dependency of the flood event and any potential mitigating or recovery actions. The damage states reflect a particular flood-exceeding frequency at a particular location with a predefined equipment damage level. This allows the incorporation of any partial failures due to flooding or differentiation between equipment damages at a particular location.

The flood initiating frequencies were developed to incorporate simple recovery actions as expected from the existingexperienceor data base. In addition, the data base is examined for its applicability for the Surry.plant and is modified to take into account certain plant-specific features.

2.4 Location and Scenario Identification The coarse screening analysis identified flood areas along the line of the fire analysis. This classification was further analyzed with regard to the risk importance of scenarios and the specific equipment locations. The flood areas may further be localized or subdivided depending on the specific sources, barriers, drain and sump systems, etc.

The flood sources in each location were identified and related to the corresponding frontline system so that the affected equipment and the potential damage could be identified. In the first stage of this analysis only the mid-loop operational mode (POS 6 refueling and drained maintenance, POS 10 refueling) is modeled, therefore potential flood damage to the RHR system/equipment and its support is the primary focus of the scenario identification. Thus the flood scenarios are limited to the extent of their effect on the RHR or any support system [including station black-out (SBO)].

NUREG/CR-6144 2-2

Methodology

The identification of the potential scenarios and flood locations was accomplished by initially using the general arrangement diagrams using the RHR system fault tree developed for the internal event analysis. The fault tree identifies all equipment and support components required for the RHR system operation. These were located and identified on the plant drawings and correlated with the flood areas as identified during the analysis.

The scenario development also included the identification of potential propagation pathways and their physical nature (doors, stairways, etc.) which may limit the flood rate. In addition, drainage potential and other mitigating features which could help in the recovery process were also identified.

Once the flood scenarios were identified, the effect on other frontline systems or their components was determined. This was limited to only those systems which were required to prevent core damage and are identified by examining the internal event trees for the loss of RHR function and/or station blackout. The appropriate equipment and/or its support were located and placed in the appropriate flood areas.

The quantification takes into account the rate of water flow into the area or height of the flood and establishes generally a critical flood level in each specific plant area. The time available for any recovery action is estimated by defining the critical volume and the applicable flow rate. This approach allows the incorporation of simple recovery effects in the quantification without greatly modifying the existing fault trees and internal event trees.

2.5 Plant Response, Accident Sequence Frequencies The quantification process utilizes the appropriately modified internal event tree models. The various flood events are connected to the appropriate event tree, which were modified to reflect the potential effects of the flood.

In this phase, only the mid-loop operational mode (POS 6 and POS 10) is modeled corresponding to the loss of the RHR system or station blackout event tree. The frontline systems required to prevent core damage were modified to reflect the actual flood scenario. The system fault trees were also modified, if required.

The event trees were quantified for the analyzed flood scenarios and flood damage state frequency. The effect of recovery and potential human actions may initially be considered in the derivation of the damage state frequency. The human reliability analysis (HRA) modeling was completed to include diagnostic and actuation human errors associated with the internal flood events and the corresponding mitigating systems. Potential recovery action was also considered after the dominant accident sequence scenarios and the prospective recovery actions were identified.

2-3 NUREG/CR-6144

3. IDENTIFICATION AND INTERCONNECTION OF FLOOD AREAS

*1 Introduction The coarse screening analysis has identified several areas, listed in Table 3-1, as potentially significant sources of internal flood risk. The analysis determined that the risk contribution from floods originating in these areas is not negligible and must be analyzed in more detail to identify the core damage frequency contributions.

The coarse screening analysis utilized relatively conservative quantification methodology without identifying the plant-specific features and details. Table 3-1 identifies the results of the coarse screening analysis indicating the flood initiating frequency and the consequent CDP contribution.

Other areas were also considered, but screened out due to little equipment damage by a flood in that area.

In the following two sections, these areas are further discussed with respect to the potential sources of flood and the interaction between areas or flood propagation pathways. The equipment located in the affected or interconnected area is identified in the following section. This serves as the basis for identifying the potential damage caused by a flood event.

The following areas are discussed further:

Turbine Building

Emergency Switchgear and Relay Room

Auxiliary Building

Safeguard Area

Containment

Mechanical Equipment Room No. #3 3.2 Flood Sources, Protection Devices and Floor Drain Systems The possible sources of internal floods and potential interactions between different areas were derived from various sources of information. The NUREG-1150, the IPE study, plant drawings, and walkdowns were extremely helpful in determining the potential flood sources as well as the propagation pathways including floor drain systems, pipe tunnels, stairwells, and ventilation openings.

3.2.1 Turbine Building The potential flooding sources in the Turbine Building have the largest potential for flood risk contribution due to their size and volume. The building has the largest floor area, the most extensive sump arrangements, and a large capacity of dewatering capability.

The single most important large source is connected with the intake canal through the CW and SW systems.

The CW system has four 96" diameter pipes at the inlet and outlet of the main condenser. The 36" SW system supply is taken from the CW inlet sections providing coolant to various heat exchangers.

The CW and SW systems are gravity feed from the intake canal that contains 29 million gallons of water.

Given an opening in the inlet or outlet piping of the CW or SW system, the intake canal may drain into the Turbine Building resulting in a flood scenario with potentially huge quantities of water.collecting inside the building.

3-1 NUREG/CR-6144

Identification and Interconnection of Flood Areas The four 96" diameter CW inlet lines (per unit) connect the intake canal with the main condenser. Each pipe enters the building from the condenser pit and rises 18" before connecting to the inlet motor-operated valve and an expansion joint. After the expansion joint, the pipe is connected to the condenser water box. The expansion joints are shielded by metal plates that would limit or reduce the leakage rate if a rupture were to develop.

The expansion joints are deemed to be the most vulnerable sections and potentially susceptible to pipe break due to water hammer or other mechanisms. The inlet and outlet isolation valves can be used to isolate a break in the system. The SW system also includes motor-operated valves (MOV-SWI01A,B, SWI02A,B, SWI03A,B,C,D) to stop and isolate the SW system, if required.

Two air-operated vacuum breaker valves are mounted on each condenser outlet waterbox at the highest point in the CW system. These valves are designed to interrupt the siphon action of CW flowing through the condenser and conserve canal inventory during fire events which may prevent the closing of the inlet and outlet valves.

The circulating water lines can be isolated at the high-level intake structure by inserting stop logs. The stop logs are used to isolate the inlet lines to allow maintenance to be performed. The time required to insert the stop logs varies depending on the availability of trained personnel and the conditions at the canal inlet. Due to the estimated time involved, it is not likely that the stop logs would be an effective means of isolating the circulating water lines in a short period of time. Long-term isolation may also be difficult, since the stop logs are not designed to be inserted against full flow which may prevent their movement in the track mechanism.

Other sources of water are related to the various systems located in the Turbine Building. However, their

capacity and flow rate is limited with comparison to the CW and SW system. The secondary side, that is the main feedwater (MFW), condensate and main steam system, is estimated to contain about 300,000 gallons of water and the maximum flow rate is about 20,000 gpm.

Additional sources of water are connected with the Fire Protection system and Condensate Storage Tank.

However, the flow rate through these piping connections is relatively limited and has isolation capability.

The plant has a number of flood protection devices installed that protect certain equipment and areas in case of flood events. The CW pipe expansion joints are surrounded by steel expansion plates which would restrict water flow given the failure of the expansion joints.

The Turbine Building ground floor is connected to a number of other adjoining plant areas. The entrance to the Emergency Switchgear and Relay Room of both units is located on this elevation through a double fire door. There is an open pipe tunnel connecting the Turbine Building ground floor (Elevation 9' -6") to the Auxiliary Building basement (Elevation 2'). There is also a connection to battery room 2B and the charging pump service water pump room through closed fire doors.

There are flood dikes at the entrance to the ESGR and the Auxiliary Building Tunnel. In addition, a splash guard is installed above the ESGR entrance door to prevent fire water from entering the ESGR. The ground floor connection to battery room 2B and charging pump service water pump room has no dike installed around them. Flood dikes surround the SW valve pits in the Turbine Building. The floor drains in the Electrical Tunnels, the ESGR, and the Mechanical Equipment Room are fitted with check valves that prevent backflow of water from the Turbine Building.

NUREG/CR-6144 3-2

Identification and Interconnection of Flood Areas

The Turbine Building, shared by both units, has three separate floor drain systems. The Unit 1 part of the building is separated from that of Unit 2 by walls and fire doors, with the exception that they share one of the floor drain systems. Each floor drain system has three 1300 gpm sump pumps. Each unit has one dedicated floor drain system. The dedicated floor drain is connected to the Amertap pit. This pit is the lowest part of the turbine building. It has approximately 80,000 gallon capacity.

The third floor drain system is shared by both units. This shared system is also connected to the floor drain system for the Service Building as well as the condenser pits of both units. The drain lines from the sumps in the Service Building have anti-flow reversal devices that should prevent back flow into the Service Building.

The electrical motor control center of the drain sump pumps is also located on the ground elevation. It is expected that any water accumulation in excess of the various pits and dewatering capacity of the sump pumps would disable the electrical supply to the sump pumps itself.

The condenser pit is connected to the Amertap pit. The service water valve pits and manway pits are water-proofed/sealed and are equipped with a 2' metal dike separating them from the rest of the Turbine Building floor.

3.2.2 Emergency Switchgear Room and Relay Room This room has a 9" deep trench in the floor. It contains five 3" diameter lines of the charging pump service '.J

,I water system and four 2" lines containing water for the control room and relay room air conditioning system.

The Unit 1 ESGR is connected to the Unit 2 ESGR through a normally open heavy duty fire door, which may be closed by a pull-chain device to limit water ingress from the adjoining Turbine Building. The mechanical equipment room is connected to the Unit 2 ESGR by a fire door with a 2' dike. The Unit 1 ESGR is connected to the Unit 1 cable vault and tunnel area through a door with a 18" flood dike.

Elevation 9' -6" of the Service Building containing the ESGR has one floor drain system that is connected to the Turbine Building floor drain system. Higher elevations have drains to the Turbine Building floor drain system or sewer system. Mechanical Equipment Room No. #3 has three floor drains that are connected with the floor drain system of the Turbine Building. These drains have anti-reverse flow devices to prevent backflow. There are pipes that connect this room with the Emergency Relay Room and higher elevations of the Service Building. They are either Halon system pipes or soil waste or vent lines.

3.2.3 Auxiliary Building The Auxiliary Building houses normal and emergency equipment required for the operation of the units. The building is shared by both units and houses equipment primarily of the Chemical Volume and Control System (CVCS), Component Cooling Water System and the High Pressure Safety Injection System (HPI).

The primary sources of water are essentially related to the various systems located inside the Auxiliary Building. Most of these systems contain relatively small amounts of water or the maximum piping size is limited to 2"-4". The two major water sources are:

3-3 NUREG/CR-6144

Identification and Interconnection of Flood Areas Refueling Water Storage Tank Supplies The Refueling Water Storage Tank pipe connections and supply lines to the Charging Pumps are normally isolated, however, a random pipe rupture of the 10" and 8" lines may be a flood source with sufficient capacity to reach critical flood height. Any pipe break inside the building may be isolated at the RWST outlet by closing a manual valve. The maximum flood discharge rate was estimated in the IPE analysis at around 15,000 gpm based on the hydrostatic head involving the full rupture of a 10" supply line.

Fire Protection System The fire protection piping inside the Auxiliary Building supplies water to the hose reels through 4" pipes. One 6" diameter pipe runs to a ventilation unit at a higher elevation. The system is pressurized by a jockey pump and, given a reduction in pressure, the main fire water pumps would start automatically. Water discharged at higher elevations would find its way through gratings, floor opening and stairways down to the 2' elevation.

This elevation contains the major safety-related equipment such as the Charging Pumps and CCW Pumps.

Floods due to a pipe break in the Fire Protection System may be easily isolated by simply stopping the fire suppression pumps and/or isolating the piping headers by closing the appropriate manual valves.

The Auxiliary Building has one floor drain system that connects the charging pump cubicles with the rest of the building (all levels). High level in the building sump is alarmed in the control room. There are large openings in the floor at higher elevations. At the entrance of the Charging Pump cubicles, 2' flood dikes are installed to prevent the entering of any flood water accumulating at the 13' level. Anti-reverse flow devices are installed in the drain lines of the charging pump cubicles. The charging pump cubicles do not have any large openings such as doors, except for the floor drain, up to 11' 6" elevation. Between the charging pump cubicles, there are pipe route openings at approximately 4' from the floor connecting the cubicles to the rest of the Auxiliary Building. It was estimated that :::::::18" of water in the open floor of the Auxiliary Building will cause shorts in the CCW pump motors. The charging pumps would not be affected by this type of flood if the anti-reverse flow devices do not fail in the drain lines.

The piping from the RWST is primarily located in the charging pump cubicles and any rupture inside the cubicles would lead to the loss of two or three charging/high pressure injection pumps as well as flooding in the outside open areas with the consequent loss of the CCW system (at :::::::18").

3.2.4 Safeguard Area This area has a large number of sources of water for flooding. The main steam lines, f eedwater lines, and eight 24" SW lines to the recirculation spray heat exchangers inside the containment all pass through this area.

The containment spray pumps and low head injection pumps, located in this area, take suction from RWST, and the auxiliary feedwater pumps, also located in the safeguard area, take suction from the condensate storage tank.

The main steam and feedwater lines are automatically isolated after a pipe break, limiting the sources of flooding. The SW lines providing the heat removal function to the recirculation spray heat exchangers are normally isolated and cannot be a major source of flooding due to the limited water capacity of the pipe. The two major sources of flood that may provide a sufficient amount of water are the piping lines connected to the RWST or to the Emergency Condensate Storage Tank.

NUREG/CR-6144 3-4

Identification and Interconnection of Flood Areas

R.WST System Piping The Containment Spray Pumps are provided by 12" and 8" supply lines which are normally pressurized from the RWST. The Low Head Safety Injection System piping is also supplied from the RWST and pressurized by the static head in the tank. All these lines may be isolated at the RWST outlet, however, the precise determination of the actual break may be difficult, requiring the closure of all three RWST outlet valves.

Auxiliary Feedwater Piping The AFW pumps are normally supplied from the Emergency Condensate Storage Tank. This tank is capable of discharging about 110,000 gallons of water through the pump suction lines. The maximum discharge flow is estimated at 350 gpm based on the pipe sizes and the static head available in the tank.

The safeguard area consists of and may be divided into two sub-areas: main steam valve house and low head recirculation pump area. The main steam valve house has three levels at 26' -6', 12' and relative elevation -27' -

7". The containment spray pumps and auxiliary feed pumps are at elevation 26'-6". Above these pumps and below the roof at elevation 47' -4" are the main steam trip valves, associated bypass valves, and steam generator pressure operated relief valves (PO RVs). The SW supply lines and valves for the recirculation spray heat exchangers are at the 12' elevation.

The low head recirculation spray pump area contains valves, pumps and motors. The motors of the low head safety injection pumps, and outside containment recirculation spray pumps are at 12' elevation. The pumps of the low head injection pumps and containment recirculation spray pumps are at relative elevation -27' -7.

These pumps are connected to their motors through long shafts. The floors at different elevations in the safeguard area are connected by openings in the floor for ladders and pump shafts.

The area housing the low head injection piping and valves is connected to the area containing the AFW pumps through a pipe tunnel opening allowing a flood in one area to enter the other. The sub-area containing the AFW equipment is connected to the Auxiliary Building through a sealed pipe tunnel which leads to the 2' elevation of that building. Flood detection sensors are installed in the low head recirculation pump, area and in the tunnel connecting to the auxiliary building.

3.2.5 Containment The RHR pumps are located at the relative elevation -13"-0" elevation of the containment building 14' above the basemat of the containment which is at -27'-7". Only a very large flood in excess of a few thousand gallons can fill up the containment to 14' height causing the loss of the RHR pump motors. However, a leak and consequent spraying near the pump motors may result in an adverse impact on the motors. A leak or rupture of the reactor coolant system is considered and modeled as a large loss of coolant accident (LOCA).

Three scenarios are possible, a spurious actuation of the containment spray system, failure of the cavity seal during refueling, and failure in the SW lines to the recirculation spray heat exchangers. On May 17, 1988, a failure of cavity seal did occur at Unit 1. Such failure is modeled in the loss of off-site power event trees of the internal event analysis. In the plant's response to I.E. Bulletin 84-03, it was stated that the RHR system can still continue operating, given a seal failure. Therefore, such a scenario was not considered in the flood analysis. Inadvertent actuation of containment spray is considered as a loss of RHR event, and is analyzed 3-5 NUREG/CR-6144

Identification and Interconnection of Flood Areas in the loss of RHR event trees discussed again in the internal event analysis. Therefore, inadvertent actuation

of containment spray is not considered in the flood analysis.

The SW lines supplying the recirculation spray heat exchangers are the most likely cause of flood in the containment. However, these lines are normally kept isolated by MOV-SW103A-D. The water volume available in the SW pipes is estimated to be insufficient to cause large scale flooding inside the containment that would affect RHR equipment at the -13'-0" relative elevation.

The containment drainage system is designed to direct all leakages into the containment sump located on the bottom of the building. It is monitored in the control room for increasing level.

3.2.6 Mechanical Equipment Room No. #3 The Mechanical Equipment Room No. #3 is located on Elevation 9' -6" next to the plant ESGR and the Turbine Building. The room houses chillers, pumps, and valves associated with the control/relay room air conditioning system. The Charging Pump Service Water system pumps are also located here. Potential source of flooding is due to the SW supply lines to the chillers and pumps.

The entrance to the ESGR is protected by a flood dike and a connecting pipe tunnel is sealed to prevent water entering the electrical area. A flood sensor providing an alarm in the control room is also installed. The SW lines are connected to the inlet canal providing a potential source of flood water in this area.

3.3 Building Layouts, Flood Propagation Pathways, Impact on Equipment 3.3.1 Turbine Building The Turbine Building primarily houses equipment of the Power Conversion System which has no safety function. This building has the most sources of water. The equipment in the building that are needed for decay heat removal or mitigation of any initiating event are the instrument air compressors, SW valves and pipes, and cables for train A of safety injection, containment spray, RHR, and motor-driven auxiliary feed water pumps. A flood in this building can enter Battery Room 2B and charging pump SW pump room through the bottom of the doors. Failure of the anti-reverse flow device can cause a flood to propagate to the ESGR. A large flood can propagate from this building to the Auxiliary Building through the pipe tunnel used by the CCW system. A flood that exceeds 2' level in the building can propagate to the ESGRs, Mechanical Equipment Room No. #3 and cable vault and tunnel.

The building is shared between the two units, however, there is a dividing wall which extends up to the 58' -6" elevation. There are several nonwatertight interconnecting doorways, including three on the lowest level, and a common drain system.

The primary propagation pathways required to be analyzed are the overflow of a 2' flood dike protecting the ESGR. The door connecting the Turbine Building with the ESGR area is assumed to open under static pressure. The water would initially enter the Unit 2 ESGR and eventually would overflow a 3" curb at the entrance of the Unit 1 ESGR. The cable vaults and tunnels are protected at the back of the ESGR by 18" flood dikes.

NUREG/CR-6144 3-6

Identification and Interconnection of Flood Areas

The other important interconnection is through the pipe tunnel connecting the Turbine Building ground floor at the 9' -6" elevation with the Auxiliary Building at the 2' elevation. The entrance of the pipe tunnel in the Turbine Building is protected by a 2' flood dike. Given a flood event providing a sufficient amount of water, the 2' dike may be overflown and water may enter into the Auxiliary Building at the 2' elevation.

The most important impact of a limited flood in the Turbine Building is the potential loss of instrument air supply and the potential effects on the operation of the SW valves. However, a major flood event which would overflow into the ESGR and Auxiliary Building is expected to have a major impact. The effects of this type of flood propagation is discussed in the next sections.

The instrument air compressors are located 3' above the floor level and their function is to back up normal service air supply to the SG PORVs. The primary air supply to the PORVs is from the service air compressors located outside in the yard area.

The SW supply to the recirculation heat exchangers may also be affected after a flood event. However, the need for these heat exchangers is rather limited and required only for long-term sequences with RHR and AFW system failures.

3.3.2 Emergency Switchgear and Relay Room, Cable Vault and Tunnels The Unit 1 ESGR is connected to a number of other areas including the cable vault and tunnel through a door which has an 18" flood dike. There is a door opening to the Unit 2 ESGR that has a 3" curb. There is a direct connection to the Turbine Building through the floor drain system. The drain lines for this area are equipped with anti-reverse flow devices. The Unit 2 ESGR is connected to the Turbine Building through a fire door. A 2' dike is installed in front of the door inside the Turbine Building to prevent the propagation of any flood.

A flood propagating into the ESGR could affect all the safety related 4 kV and 125 VDC power supplies, 480 V buses, motor control center (MCCs) and DC switchboards. The cable vault contains a large number of cables for safety equipment and the following could be affected:

HHSI suction train A, B

HHSI discharge train C

CS discharge train A, B

PORV train A, B

RS-SW train A (1/2), B (1/2)

.3.3.3 Auxiliary Building The basement of the Auxiliary Building (Elevation 2' -0") houses the six charging pumps which also serve as high head safety injection (SI) pumps and CCW pumps for both units. The charging pumps are each in an enclosed compartment of its own. These compartments are connected with each other and the rest of the building with open pipe penetrations at approximately 4' above the floor. The compartments are separated from the rest of the building by walls which extend up to elevation 13' -0" where flood dikes are installed at the cubicle openings. The floor drain system*also connects the compartments with the rest of the Auxiliary Building where anti-reverse flow devices were recently installed .

3-7 NUREG/CR-6144

Identification and Interconnection of Flood Areas The charging pump cubicles are protected against flood by 2' dikes installed at the entrance at elevation 13'-0".

However, any flood at this elevation is expected to find its way to the 2' -0" elevation and collect on the basement floor.

The Auxiliary Building is connected to the Turbine Building through a pipe tunnel whose entrance at the Turbine Building is protected by a 2' dike. Therefore, a very large flood in the Turbine Building or a flood localized at the entrance to the pipe tunnel is needed for a flood to affect the Auxiliary Building.

The CCW pumps and their electrical motors are installed on a concrete pedestal about 18" height. A flood in the auxiliary building has to be of sufficient extent that the water level reaches this height causing the failure of the CCW system. The CCW system provides direct heat removal to the RHR heat exchangers, and thus its loss would lead to the loss of the RHR system. The RHR pump seals are cooled also by the CCW system, however, the loss of this cooling function will not directly lead to the heat removal capability and does not have to be further considered A major flood due to rupture of the RWST piping would most likely occur inside the charging pump cubicles leading to the loss of two or three charging pumps. The water would flow through the drain lines into the outside open area and eventually would short out the CCW pump motors when flood levels reach about 18".

3.3.4 Safeguard Area The Safeguard Area contains a number of safety-related pumps and valves located next to the containment.

The Safeguard Area has a sump at the 12' elevation. A flood at this elevation can potentially fail the low head safety injection pumps and outside containment recirculation spray pumps. A pipe tunnel at elevation 11'-6" exists between this area and the auxiliary building. It is sealed by foam for fire protection purposes. In the flood analysis, it was assumed that the seal is not a flood barrier.

The area may be divided between two sub-areas: one containing the low head safety injection pumps and the other mainly containing equipment and piping related to the main steam and AFW system. The two sub-areas communicates through a pipe trough opening at the 16'-9" elevation. The connection between the safeguard area and the pipe tunnel leading to the Auxiliary Building is at the 11'-6" elevation.

The flood may originate in the low head safety injection sub-area, in which case, the water has to rise to the 16'-9" elevation to overflow into the AFW equipment area and then through the pipe tunnel into the Auxiliary Building. Floods originating in the AFW equipment sub-area may flow directly into the Auxiliary Building once the fire barrier is penetrated by the water at the pipe tunnel entrance. A flood in these locations would eventually spill over onto the Auxiliary Building floor affecting the 6peration of the CCW pumps leading to the potential loss of the RHR system. The pipe tunnel discharges onto the 2' elevation of the Auxiliary Building where the water may collect.

3.3.5 Containment The RHR pumps are located on the -13'-0" relative elevation 14' above the bottom of the containment building. The volume in the SW or CCW system piping is not sufficient to fill up the containment to the RHR pump level. Indirect loss of the RHR system is considered through incidental spray on the RHR pump motor.

NUREG/CR-6144 3-8

Identification and Interconnection of Flood Areas 3.3.6 Mechanical Equipment Room No. #3 A potentially large flood in this location may overflow the flood dikes installed at the entrance to the ESGR and would cause first loss of AC power on Unit 2 and subsequently, given sufficient water volume, on Unit

2. The consequences of the event are similar to a large Turbine Building flood entering the ESGR. As the water enters into the ESGR, the MCCs and 480 V buses and finally the 4 kV buses are expected to be lost.

This leads to the loss of the RHR system combined with an electrical blackout of the units .

3-9 NUREG/CR-6144

Identification and Interconnection of Flood Areas Location Table 3-1 Summary of Coarse Screening Analysis Frequency of Flood Sequence No. Core Damage Frequency Emergency 3 Low Switchgear and 3.00 E-05 4 High Relay Room Containment 6.18-06 4 Low 7 Low Auxiliary 1.88E-05 3 Low Building 5 High Safeguard 1.SOE-05 High Area Turbine 7.52E-05 High Building NUREG/CR-6144 3-10

4. INITIATING FREQUENCY ANALYSIS 4.1 Introduction The initiating frequencies for the various buildings may be determined by using different approaches. The two most common approaches are 1) based on the statistical analysis of actual events occurring at similar installations orb) utilizing a fault tree method.

The first technique collects data from actual events and through statistical and engineering techniques tries to develop a data base specific for the plant. Through simple statistical arguments the frequency is then determined as the ratio of applicable events to some time base. The difficulty with this approach is that the physical arrangements and engineering design differences between the various installations may invalidate some of the actual events as not fully applicable to the specific plant.

The fault tree method relies on the simple assumption that potential failures of systems comprised of a number of components may be obtained by combining the various failure modes of the individual components.

The underlying assumption is that the component failure rates are better known than that of the system failure rate and the proper combination of the component failure modes and mechanisms may give an indication on the total system failure rate.

The difficulty of this approach lies in the quality of the component failure data and the actual analytical model of the system describing the potential failure modes. In general, it is difficult to determine whether the component or system failure rate data is the more reliable and whether all failure modes are represented by the data. Similarly, the analytical model has to take into account the most important failure modes that can seriously affect the operation or functioning of the system.

In this study, similar to the internal event initiating frequency analysis, the first method was selected whenever possible. The operating events related to flood scenarios were collected, reviewed, and applied to the Surry-specific conditions. This was especially important with respect to the Turbine Building flood scenarios that are deemed to be the most dominant flood sequences.

The most important sources of data were LER reports, previous PRA analyses, the recent IPE flood analysis of the Surry plant, and numerous NUREG reports.

There are a large number of flood scenarios initiated by random pipe rupture resulting in a break opening with a certain leak rate. Actual operating experiences in this area are not very reliable and consequently an analytical approach was used (Thomas-model). However, it must be recognized that the bases of the analytical model are actual plant operating experiences and the analytical formula is simply fit to represent available information.

4.2 Turbine Building The potential flood events emanating in the Turbine Building are related to the CW or SW piping. Both of these systems are constructed as large diameter low carbon steel piping and largely similar to other power plant installations. The actual physical arrangement at Surry is somewhat different in that gravity flow is used throughout the system which generally operates at a lower pressure as compared to pumped arrangements.

The main disadvantage of the gravity system is the potential for draining down the inlet canal for loss of circulating water pump function, and the potential for draining the intake canal volume into the building if a pipe or component break occurs. Figure 4-1 indicates the general cross section of the plant indicating the relative position of the Turbine Building, the intake canal, and the discharge section, and Figure 4-2 indicates the relative position of the CW inlet and outlet piping at the condenser. Figures 4-3a and 4-3b present the arrangement of the flood dikes inside the Turbine Building, the ESGR and the Mechanical Equipment Room No. #3, as well as at the entrance to the Cable Tunnel.

4-1 NUREG/CR-6144

Initiating Frequency Analysis Table 4-1 lists the events which were considered in the analysis. The data was collected from a number of sources such as the LER data base, the IPE analysisl4-tJ, a time period covering essentially 1980 to present with the addition of significant events from earlier time periods. A number of events effectively represents spraying incidents (1st, 2nd, 4th) and is not considered in the data representing large flood events. The feedwater line break incident on 12/09/86 at Unit 2, Surry (Event # 2) was one of the minor events in the Turbine Building.

For the other events the flow rate and the total accumulation are listed along with a short description of the underlying cause leading to the flood release.

In some cases, the values are engineering estimates, since the event descriptions were not detailed enough.

An important attribute of each event is the recovery characteristics, which is also estimated and noted in the last column.

The compilation of the data did not include a number of flood events which were judged to be not applicable to the Surry plant. These generally involved different valve operator types ( 06n2, Quad Cities - hydraulic operator; 10/10n6, Oconee 3 - air operator), pump start transients (04n7, Three Mile Island 1), or foreign plants which are excluded from the U.S. data bases.

In general the data base is not as extensive as for specific component types which is expected, since large scale flood events are relatively rare. This type of system failure involves the combination or gross failure of one or several components and additionally, possible human errors. However, it is sufficiently robust and diverse that certain conclusions may be drawn even from this limited experience.

The data were further categorized to estimate the relative frequency of the different flood rates. Table 4-2 lists the respective flood rate intervals, the number of events (N), and their relative fractions (FRJ. The other columns deal with the recovery characteristics of the events which are discussed further below. Three events from Table 4-1 were treated somewhat differently from the others due to their component and plant-specific nature. These events are not fully applicable to the Surry plant, however, using engineering judgement one may be able to extrapolate to the Surry-specific data base from these occurrences.

Event # 6, LaSalle: In this case, the valve operator mounting bolts were not properly torqued. When these bolts became loose and failed due to fatigue, the valve disk was permitted to rotate freely shut resulting in a water hammer that ruptured the rubber expansion joint. At Surry, the valve operators and their mountings are properly sized and there is a high degree of assurance that the bolts are torqued. This allows us to utilize a correction factor of CF= .1. In addition, the valves are positioned fully open and the disks do not experience significant turbulence resulting in balanced forces. A correction factor may also be applied to take this effect into account, CF=.2. The combination of these correction factors CF=.lx.2=.02was applied to Event #6.

Event # 7, South Texas: The 96" discharge valve operator cap screws failed due to fatigue caused by a drive sleeve periodically hitting a mechanical stop and the combinat~on of vibrations caused by turbulent flow. The valve disk became separated from the operator, allowing it to swing closed causing a water hammer. At Surry, the operator is of a different design (Limitorque) with a lock pin preventing a stop. There is a reduced likelihood of separation which is accounted for by applying a reduction factor of CF=.l.

Event# 8, Palo Verde: One of the four cap screws backed out and the others sheared causing the butterfly valve to swing shut resulting in a water hammer event. This is similar to the previous event and the differences are also similar. The operator is different with six instead of four bolts and the stopping mechanism is also different, reducing the likelihood of fatigue failure resulting in an engineering reduction factor of CF=.1.

A pathway for gravity draining of the canal to the Turbine Building can occur in several ways:

a. Failure of the expansion joints or other components in the circulating water lines and SW lines, or NUREG/CR-6144 4-2

Initiating Frequency Analysis

b. Maintenance activities causing inadvertent opening of an open pathway to or inside the Turbine Building.

The primary damage mechanism due to a large scale flood in the Turbine Building is the flooding of the ESGR leading to the potential loss of all 4 kV, 480 V and 125 VDC electrical safety power supplies. The flood events listed in Table 4-1 indicate that the leak rate in a flood event or the total volume of water discharged encompasses a relatively wide spectrum. There were events with relatively large flow rate, but for a short duration of time, and there were events with small leak rates for short and long periods of recovery times.

This indicates that flood events and the expected flood frequency must be characterized by these attributes.

In the Turbine Building two separate categories of flood frequency are derived:

Category 1 - Large flood - > 3600 gpm These flood events result in the flooding of the Turbine Building up to and beyond the 11'-6" elevation.

The 2' dikes to the Auxiliary Building Tunnel and the ESGR are overflown resulting in equipment damage at those locations.

Category 2 - Medium flood - 3600 gpm These events result in the flooding of the SW valve pit and damage to the SW valves supplying the recirculation spray heat exchangers.

The critical water volume corresponding to these categories may be estimated by taking into account the potential drainage pathways, sump pump capacities, and the volume of the building. The progress of flooding originated from CW/SW lines initially is assumed to collect and fill up the valve pits in the Unit 1 portion of the Turbine Building. In the next stage the water would collect on the building floor and spill over to the other units through the interconnecting doorways. Operable floor sump pumps would remove water at the rate of 1300 gpm per pumps. The increasing water height eventually would trip the sump pumps when it reached the sump pump power supply cabinet (estimated at ===8"). With further leakage, the water level would reach the height of the flood dikes and overflow into the ESGR and Auxiliary Building.

The unit volumes were estimated by utilizing information from plant drawings and are as follows: .

Volume of Unit 1 & 2 buildings 2 X 460,000 gal Volume of Unit 1 & 2 pits 2 X 200,000 gal Volume of ESGR up to 18" 20,000 gal Total Volume Unit 1 +ESGR 680,000 gal Unit 2 660,000 gal The IPE estimated these volumes at 712,582 gal for Unit 1 and 696,832 gal for Unit 2, which is relatively close.

This is the critical flood volume which will cause damage in the ESGR. The Auxiliary Building requires additional water volume due to the large open floor arrangement. The effect of drain and sump pump dewatering rate is not taken into account at this point. The critical volume simply indicates that given a flood event, what amount of water has to collect in the Turbine Building to overflow the flood dikes and damage equipment located in the ESGR.

An additional consideration for very large flood categories is the question of isolation capability. The Turbine Building is at a lower elevation (9' -6") than the intake canal( ===29' -25') and a postulated break at or upstream

of the inlet isolation valve body is not easily isolable. Stop logs may be inserted at the intake canal entrance, 4-3 NUREG/CR-6144

Initiating Frequency Analysis however, this cannot be quickly accomplished. In this scenario, the potential for recovery in the first few hours of the accident is relatively small. This contrasts with other events, where the inlet valve may remain intact and its closure may terminate any flood event in a relatively short period of time.

The essential difference is in the recovery model and usually this is taken into account by separating the large flood scenarios into two distinct group, namely nonisolable and isolable, and assigning different recovery probabilities to the two groups. Normally, the nonrecoverable category would have P(failure to recover)= 1.

This approach is consistent with static fault tree modeling and does not take into account the time dependent behavior of the events as represented by the statistical data.

In this study, the recovery behavior was derived from the operating experience by noting the nonrecovery fractions as a function of time. The norecovery fraction, NR, represents the fraction of the total events which did not recover for a certain time. This is similar to the approach taken in quantifying the loss of off-site power recovery behavior. Table 4-3 lists the values which were derived from the recovery data of the flood events listed in Table 4-1.

The initiating frequency for Category 1 events is determined by considering the fraction of flood events discharging at least the critical volume in the Turbine Building. In this formulation, the recovery potential for each category of events is incorporated in the initiating frequency. For example, small leak rate flood events have a longer time to recover, thus its nonrecovery probability is relatively small. However, large or nonisolable flood events will have nonrecovery probabilities close to unity (fail to recover).

The formulation may be expressed as:

{(Category 1) = 2: f(flood)

FRi

NRi = f(flood)

CP(flood/damage) i where f(Category 1) = Frequency of floods which discharge the critical volume into the Turbine Building irrespective of the discharge rate f(flood) = Frequency of all flood events in the Turbine Building

~ = Relative fraction of all flood events in the i-th leak rate range N~ = Nonrecovery probability of the i-th leak rate range CP(flood/damage) = Conditional probability of flood damage given a flood event Table 4-2 lists the corresponding values for the above variables in each flood range. The critical ti~es associated with each flood range are based on the total volummetric estimate and was set at =700,000 gal for Unit 1 and an additional 680,000 gal for the Unit 2 areas, reflecting a compromise between the estimated values of this and the IPE study.

The critical time estimates comprise of a number of factors related to the building volumes. The estimate for the Turbine Building volume and the ESGR together with the flow rate in a given category was used to determine the approximate timing of the flood scenario. The Surry plant recently instituted an improved reliability program for the Turbine Building sump pumps. It is claimed that the reliability of these sump pumps is improved to such a degree that 7 of the 9 pumps would be operable in a flood event. Presently, this study has taken credit for 7 operating sump pumps of the 9. This increases the dewateringcapacity, but only for a period of time, since the power supply for the sump pumps is located on the same elevation shorting out for increasing water level. The mitigating effects of the sump pump dewatering capabilities are not expected to be large since a) the sump pumps are decapacitatedwhen the water level reaches the power supply cabinet.

NUREG/CR-6144 4-4

Initiating Frequency Analysis (8") and shorts out the pumps, and b) flood events with damage potential are dominated by rare, but large leak rates where the dewatering capacity is not sufficiently large to cope with the large scale inleakage.

As it will be seen, the most dominant contribution to the conditional probability to flood damage given a flood event arises from the very large flow rate type of flood scenarios, 25,000 gpm or larger. In these.cases, the dewatering capability is significant.

The nonrecovery probabilities for small leak rates are relatively small which reflect the statistical experience.

In this event isolation capability is rarely lost and ample time is available to discover and isolate the events before the critical discharge volume is reached.

The very large flooding category is more problematic, since there are few data points in this range and these were adjusted to reflect Surry-specific features. The general recovery characteristics are not totally applicable for the events, especially in the last two flood rate categories, 25-50,000 and 50,000-200,000 gal. Here the recovery curve was adjusted upward to reflect the nonisolable potential for these events.

In the range of 25-50,000 gpm, the nonrecovery probability value was set at .9 and the available time before the critical volume is about 40-50 min. If the motor-operated valves are operable then the operator may attempt to close them from the control room. Local operation of the valve is possible, but may take about one hr and with the condition in the Turbine Building this action is rather unlikely.

In the last category, 50-200,000 gpm, the flow rate is so large that the critical time is about 15 min and these events are beyond any isolation capability in the short run. However, even these events may be isolated by installation of the stop logs, but not in time to prevent the overflowing of the 2' dikes at the entrance of the ESGR and Auxiliary Building Tunnel.

The total conditional probability of damage due to flood events is CP(flood/damage) =2.3E-02, listed in Table 4-2. The flood frequency is obtained by noting that the total accumulated time of operating nuclear power plants (turbine buildings/CW systems) is 1463 yr (derived by noting the number of operating power plants),

thus f(flood)= Flood Events/Plant years= 7.22/1463 = 4.9x10"3/yr and the Category 1 frequency due to CW floods are fcw(Category l)=f(flood)

CP(flood/damage) fcw(Category 1) = 1.2x10*4tyr The other group of flood events with dominant contribution in the Turbine Building is due to events related to the SW system. SW is supplied to a number of heat exchangers through 42" and 48" diameter pipes which take off from the CW inlet pipes in the Turbine Building. The sections of the SW piping vulnerable to flood incidents are mostly located in the valve pits (inlet of CCW heat exchangers) which contain isolation valves and expansion joints.

The events serving as the data base for SW flood/leak incidents are listed in Table 4-3. The majority of cases are relatively benign small leak events without serious consequences to plant operation. The events may be classified according to the discharge rate as follows:

4-5 NUREG/CR-6144

Initiating Frequency Analysis Discharge Range gpm SW Flood Events N

Relative Fractions FR 0-100 15 .75 100-1000 4 .20

>1000 1 .05 Total 20 1.

The yearly frequency of flood events may be determined as fsw(small, 0-1000 gpm) = N(total)

FR(0-1000)/1463 = 1.3x10*021yr fswOarge, > 1000 gpm) = N(total)

FR(> 1000)/1463 = 6.8x10*041yr where the value 1463 represents the total operating time for the nuclear power plants.

The recovery characteristics of these events fall into two distinct groups. The relatively small flow rate events are discovered generally at a later period, but their isolation is easily accomplished. However, events with larger flow rates tend to be recognized sooner and their isolation seems to be accomplished at a much earlier time period. The corresponding time periods for average recovery times are 1-2 hr for smaller flow rates (0-1000 gpm) and =30 min for events larger than 1000 gpm.

The data represents essentially those events where isolation capability was not affected and the operator was able to act once the nature of the flood event was recognized. At Surry, there is a possibility of nonisolable failures of the SW system, such as the failure of expansion joints upstream of the main isolation valves. In such case no isolation capability exists besides the installation of the stop logs at the inlet of the intake canal However, this may take a relatively long time period of 10-24 hr.

There were two events related to expansion joints failures, which is about 10 % of the total (2/20), which would result in a frequency of expansion joint failures for larger than 1000 gpm leak rate as f=6.8x10* 05!yr.

However, failures which may be classified as nonisolable must involve a large scale rupture of the expansion joints.

The conditional probability that the expansion joint will experience a large rupture given a flood event with leak rate > 1000 gpm is estimated at P(full rupture)= .5. This is based on previous work done for interfacing LOCA studies (NUREG/CR-5102) and considering the type of material and expected stresses. The nonrecovery factor for this type of event is relatively high and estimated based on the available time and critical volume (=700,000 gallons) at P(nonrecovery)=.7 The estimated frequency of expansion joint failures which result in reaching the critical flood volume is fsw(Category 1/exp. joint-SW) = fsw(large, > 1000 gpm)*P(exp joint)*P(rupture)*P(nonrecovery) fsw(Category 1/exp joint-SW) = 2.4x10*05!yr NUREG/CR-6144 4-6

Initiating Frequency Analysis There are other causes of failures which could lead to large scale flood events and these may be estimated

from the data by extrapolating a flow exceedance plot based on the events listed in Table 4-3. The frequency of the events exceeding a certain flow rate may be plotted on a logarithmic scale and fitted with a curve. By extrapolating this curve to higher flow rates, an estimate may be obtained for larger flow rates. This method assumes a log-log relationship between flow rates and occurrence rate which is found to be fairly representative of this type of event.

The following table indicates the results from this process which are the frequency of flood events for the different exceedance flow group rates:

Exceedance Frequency Nonrecovery Flow Rate /yr Probability gpm NR

> 1000-10,000 2.0E-04 .001 10,000-20,000 9.0E-05 .05 20,000-40,000 5.0E-05 .4

> 40,000 2.0E-05 .75 The nonrecovery probability values indicated in the last column were derived from the same relationships as established for the CW events assuming that the critical flood volume is also the same as previously estimated.

The total frequency of SW-related flood events other than expansion joint failures is obtained as the sum of the individual flood group frequencies weighed with the nonrecovery factor:

fsw(Category 1/other-SW) =I f(SW/flood)i

NRi fsw(Category 1/other-SW) = 4.0E-05/yr The total SW-related flood event frequency is the sum of the failure frequency for expansion joints and from all other causes:

fsw(Category 1) = fsw(Category 1/exp joint-SW) + fsw(Category 1/other-SW) fsw(Category 1) = 6.4E-05/yr.

The Turbine Building Category 1 flood event frequency is the sum of the CW and SW flood event frequencies:

f(TB - Category 1) = fcw(Category 1) + f5w(Category 1) f(TB - Category 1) = 1.9E-04/yr which was used as the mean value of a prior distribution (assuming an error factor of 10) based on generic data.

4-7 NUREG/CR-6144

Initiating Frequency Analysis A Bayesian updating was performed using the above obtained prior distribution, and no events in 35.5 years

as the plant-specific evidence. The posterior distribution has a mean frequency of l.8E-04 per year (error factor of 7.4). Assuming that this frequency applies to any plant condition (or POS), it converts to a frequency of f(TB - Category 1)=2.lE-08/hr.

The duration of the mid-loop POSs may be used to calculate the expected Category 1 failure probability in the respective operating states:

POS 6 Refueling - f(TB - Category 1) = 5.0E-06, POS 6 Drained Maintenance - f(TB - Category 1) = 5.3E-06, POS 10 Refueling - f(TB - Category 1) = 9.6E-06.

An other class of flood events is the one which affects only the SW isolation valves supplying the Recirculation Heat Exchangers. The amount of flood required is around 3600 gpm and its frequency may be estimated from the SW exceedance curve. The estimated frequency of flood events which appear with 3600 gpm is f(Category 2 )=1.0E-05/yr .

The nonrecovery rate for this type of flood event is estimated at NR= .1. Combining the estimated Category 2 flood frequency with the nonrecovery probability and performing a Bayesian updating, one finally obtains the flood frequency for Category 2 as f(TB - Category 2) = 1.lE-10/hr.

The consequences of this type of flood event is the potential loss of the inside recirculation beat exchangers.

From the perspective of loss of RHR accident, this is relatively insignificant, since those beat exchangers are required only for long-lasting accidents to delay containment failure.

4.3 Emergency Switchgear and Relay Room Due to limited sources of water in this area, flood damage is expected to be due to propagation of flood from the adjacent Turbine Building. Category 1 flood events in the Turbine Building are such that the protecting 2' dikes are overflown and water enters into the ESGR area.

The amount of flood was also estimated in the previous section at =700,000 gallons. At this level the flood would enter the ESGR and reach a height of about 4". At that level the 480 V buses and MCCs would short out and most likely cause the tripping of the 4 kV safety buses. DC power would fail when the flood reaches 12". Given a flood in this area, it was conservatively assumed that every piece of equipment in the area and the cable vault and tunnels would fail. As a result, a two-unit station blackout would occur- and the only means to mitigate the flood is gravity feed from the RWST.

4.4 Auxiliary Building Due to the large size of the building as well as the separation of the charging pumps from the rest of the building by compartments, a large flood would be needed to cause simultaneous damage of all the charging and CCW pumps in the building. Based on a limited review of the plant experience, no significant flooding in the building was identified.

NUREG/CR-6144 4-8

Initiating Frequency Analysis

The data in Table 4-4 indicates a limited number of flood events which occurred in Auxiliary Buildings of nuclear power plants. The data seems to indicate that large scale flooding is not a common occurrence.

However, a leak rate dependent exceedance curve may still be constructed from the data and the curve can be extrapolated linearly (log-frequency vs. log-leak rate/gpm) to estimate the expected frequency of floods with higher leak rate.

The results of this process are summarized in the following:

f(> 1000 gpm) = 1.5xto-04/yr f(>3000 gpm) = 8.0xto*05!yr f(> 10,000 gpm) = 4.0x10-051yr Three categories of flood levels were established to deal with the different time scale and potential recovery actions. The critical flood height is estimated based on the location of the critical equipment in the Auxiliary Building, such as the charging and CCW pumps. The critical volume is estimated at 135,000 gal and the corresponding flood height would be 18.5". At that level the CCW pump motors, which are installed on a concrete pedestal, would most likely be shorted out. For a large scale flood in the Auxiliary Building basement due to a supply line rupture to the RWST, the charging pump cubicles would be overflown causing the subsequent failure of all charging pumps. The flood would enter the open area and could short out the CCW pump motors once the flood height reaches 18.5".

The data in Table 4-5 do not represent flood events due to pipe rupture which may be a significant contributor to the total flood frequency. The most vulnerable piping systems in the Auxiliary Building are predominantly low pressure pipes pressurized by static head from the RWST or by the fire protection system pumps. The pipe rupture frequency may be estimated by utilizing the semi-analytical Thomas model. In this respect, the present analysis relies on the results of the IPE study which used the same approach to estimate the frequency of large scale rupture of piping in the Auxiliary Building.

The data and the modeling approach in the IPE study were reviewed and confirmatory calculations were completed to check its validity and application. It was found to be a reasonable approach predicting realistic pipe rupture frequencies. The following values were used for the different pipe and valve sizes:

Size Pipe Rupture Valve Rupture Frequency/yr Frequency/yr 10" 7.5x10*05 8" 1.3x10-04 2.0x10*04 6" 1.9x10-04 1.9xto*OS 4" 7.0x10-04 3.2x10-05 The Thomas model predicts the frequency of pipe break, but this still has to be further distributed between different break sizes which result in different leak rates. The following relative values [P(x gpm)=conditional 4-9 NUREG/CR-6144

Initiating Frequency Analysis probability that a pipe break results in x gpm] were used, P( 1000 gpm)=.6, P(3000 gpm)=.3 and P( 10,000.

gpm)=.1 and the final pipe break frequencies are as follows:

f( 1000 gpm - pipe) = 2.4x10*04tyr f( 3000 gpm - pipe) = 3.0x10-041yr f( 10,000 gpm - pipe) = 7.5x10*061yr The nonrecovery factors or the effect of potential recovery actions by the operators may be taken into account at this level. The numerical values are based on the available time which is derived from the flood rate and the critical flood volume and also considers the potential drainage pathways, Category Time Nonrecovery Probability f (1000) 1.5 hr .1 f(3000) .75 hr .2 f (10,000) 13 min .9 NUREG/CR-6144 4-10

Initiating Frequency Analysis

The total flood frequency in the Auxiliary Building is obtained for each category by combining the flood frequency components (pipe break frequency and operating experience) and the nonrecovery probabilities to arrive the final estimates as:

Flow rate Frequency POS6 POS6 POS 10 (gpm) /hr Refueling Drained Refueling Maintenance f( 1,000) 4.45E-09 1.06E-06 1.14E-06 l.98E-06 f( 3,000) 8.68E-09 2.07E-06 2.21E-06 3.85E-06 f(l0,000) 4.91E-09 1.15E-06 l.24E-06 2.15E-06 Total 4.28E-06 4.59E-06 7.98E-06 Total w/ RWST 2.48E-06 2.65E-06 4.62E-06 Total w/o l.82E-06 l.95E-06 3.4E-06 RWST The above rates can be further divided according to the additional criterion of RWST availability (listed as with or without RWS1). The question of RWST availability is important from the accident progression point of view, since the low pressure injection system as well as the gravity feed method of heat removal is dependent on the water source available through the RWST.

4.5 Safeguard Area The Safeguard Area has two separated compartments with a number of piping systems pressurized by the RWST static head. The main contribution to the frequency of flood with a potential for damage is expected to arise from scenarios involving large pipe ruptures.

The pipe break frequencies of the low pressure pipes are developed again using the Thomas-model approach utilizing some of the results of the IPE analysis. The information developed and used in the IPE study was again checked and confirmatory calculations were performed.

4-11 NUREG/CR-6144

Initiating Frequency Analysis Three different flood categories were established, f(lOOO gpm), f(3000 gpm), and f(l0,000 gpm). The Safeguard Area communicates with the Auxiliary Building through a pipe tunnel and this serves as the main propagation pathway.

The dominant failure scenario is a flood of sufficient size and duration to flood the Auxiliary Building through the pipe tunnel up to the 18.5" level. At that point the CCW and charging pumps are assumed to fail.

The pipe break frequencies for the different pipe sizes are the following:

Category Pipe break Nonrecovery Frequency Probability f(lOOO gpm) 6.6x10*041yr .001 f(3000 gpm) .1 f(l0,000 gpm) 5.5xlQ*OS/yr .9 The nonrecovery probabilities were derived by considering the critical water volume, available time, and the isolation capability of the supply pipes existing at the RWST outlet.

The final flood frequencies for the different categories are obtained by combining the pipe break frequency with the nonrecovery probability to arrive at the frequency of flood with damage in the respective category:

Flow rate Frequency POS6 POS6 POS 10 (gpm) /hr Refueling Drained Refueling Maintenance f( 1,000) 7.53E-10 1.79E-07 1.92E-07 3.35E-07 f( 3,000) 4.34E-09 1.03E-06 1.llE-06 1.93E-06 f(l0,000) 5.59E-09 1.33E-06 1.43E-06 2.48E-06 Total 2.54E-06 2.73E-06 4.75E-06 NUREG/CR-6144 4-12

Initiating Frequency Analysis 4.6 Containment As discussed previously, the failure of the SW lines to the recirculation spray heat exchangers is the most significant cause of flood in the containment. However, these lines are normally isolated by the SW isolation motor-operated valves (MOVs) located in the Turbine Building SW valve pits. It is estimated that the water volume contained in the SW piping is not sufficient to cause large-scale flooding in the containment which would affect the operation of the RHR pumps.

However, a potential break near the RHR pump motors may affect their operation, if the leak sprays on the electrical parts. Table 4-5 lists a number of spray events inside the containment and these were utilized to estimate the frequency of loss of RHR pumps due to this specific failure mechanism.

The following formulation was used:

f(spray at RHR pumps)=f(spray in containment)*Ppipe *P1ocation where f(spray in containment)= frequency of spray events in containment Ppipe = fraction of pipe length around the RHR pump motors relative to the total pipe length in containment Piocation = conditional probability that the spray, once it occurred near the RHR, affects the RHR pump motor The value of f(spray in containment) is estimated based on the data in Table 4-5, f(spray in containment) =2.0E-03/yr. Ppipe= .1 is selected based on the review of piping drawings and Piocation is estimated also at .1. The spray frequency is obtained as the combination of these factors:

f(spray at RHR motor) = 2.0E-05/yr=2.3E-09/hr or the failure probability in the operating states:

POS 6 Refueling - f(spray at RHR motor) = 5.43E-07 POS 6 Drained Maintenance - f(spray at RHR motor) = 5.82E-07 POS 10 Refueling - f(spray at RHR motor) = l.OlE-06 4.7 Mechanical Equipment Room No. #3 The Mechanical Equipment Room (MER) is a relatively small area where the primary mechanism for any flood event is expected to be due to pipe ruptures in the SW supply lines. The SW lines may be isolated outside the MER in the Turbine Building. There are a number of 6" and 4" pipe segments and supply headers 4-13 NUREG/CR-6144

Initiating Frequency Analysis which would dominate the flood risk. Operation Response Procedures exist (O-AP-13.00) which give

instructions to the operator upon receiving HI level flood alarms.

The critical elements in the flood frequency analysis are the frequency of expected rupture or leak, the size of the rupture, and the available time before damage occurs. The damage time may be established by estimating the critical water volume required to flood the Unit 1 ESGR. The water volume inside the MER up to 2' height (flood dike) is about 10,000 gal which was derived by reviewing engineering drawings and documents. An additional 20,000 gal is required to flood the Unit 1 ESGRwhich was estimated at the Turbine Building flood scenarios. Thus, the total of about 30,000 gal is necessary to disrupt the operation of the RHR system and cause further damage by effectively disabling the station safety power supplies.

The pipe rupture probability analysis of the IPE study (Ref. 1) has been reviewed and utilized to derive the pipe rupture frequency data as indicated in Table 4-6. The SW lines may be isolated outside the MER and any flood would be alarmed in the control room. The nonrecovery factors are also listed in Table 4-6 and reflect the probability of operator error to correctly diagnose and act upon a flood event in the MER. The last column in Table 4-6 is the initiating frequency of flood events which result in damage to the electrical components in the ESGR. The total initiating frequency of f(flood in MER)=7.3E-07/hr may be CQnverted to the appropriate values in the respective operating states to obtain POS 6 Refueling - f(flood in MER) = 2.lE-08 POS 6 Drained Maintenance - f(flood in MER) = l.9E-08 POS 10 Refueling - f(flood in MER) = 3.7E-08 4.8 Flood Initiating Frequency - Summary Table 4-7 summarizes the flood initiating frequencies for the different locations and categories. In general, these frequencies were calculated to represent a wide spectrum of flow rates and also include actual recovery processes which were established using operating experience. The resulting flood frequencies, in effect, represent expected flood occurrences which could cause damage to safety areas and equipment housed in those locations. Flood events in the Turbine Building are expected to have the most significant consequences due to the potential for overflowing the ESGR causing plant blackout and the loss of all safety-related electrical supplies. This category of flood events seems to be the most likely one as compared to the other potential flood locations due primarily to the isolation difficulty of these type of events.

NUREG/CR-6144 4-14

Initiating Frequency Analysis References

1. Virginia Power, Surry Nuclear Power Plant, Individual Plant Examination Program, Appendix E:

Internal Flooding.

Internal Flooding Analysis for the Individual Plant Examination, Supplemental Report, Surry Units 1 and 2, Virginia Electric and Power Company, November 1991.

2. "NUREG-1150, External Event Risk Analyses, Surry Power Station," NUREG/CR-4550, Revision lNolume 3.

3. USNRC, "Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants,"

NUREG-0800, LWR Edition, July 1981.

4. Nuclear Power Experience, NPE, published by the S.M. Stoller Corp.

4-5 "Oconee PRA, A Probabilistic Risk Assessment of Oconee Unit 3," NSAC-60, June 1984.

4-6 DOE/RECON, Nuclear Safety Information Center, 1963 to present.

Licensing Event Reports Data Base, 1980 to present.

Licensed Operating Reactors, NUREG-0020.

4-15 NUREG/CR-6144

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Table 4-1 Turbine Building nooct Events Circulating Water System

Date Plant Leaking Description Flow Total lsol.

Component Rate Disch. Time gpm gals.

1 10/27/87 Surry 1 Reheater leaks Leak drains to flood control panel, small small main CW valves close 2 12,09/86 Surry 2 Pipe 18' suction of MFWP ruptured large engulfing equipment 3 11/22/89 Surry 2 Flood protection dike for SW MOV none has been removed, maintenance problem 4 03,09/85 Trojan Pipe Pipe rupture releasing steam/water, actuating fire deluge system, damage to secondary equipment 5 08,08/86 Catawba 1 Condenser Condenser outlet valve leaked, manual severe -15 operator failed, valve opened fully, min water overflowed through open manway door. Condenser cooling pumps secured to control flooding 6 05/31/85 LaSalle Rubber Water hammer due to sudden closure 2,000 600,000 5 hrs expansion joint of a butterfly valve. Valve operator mounting bolts not properly torqued 7 03/17/87 South Pump casing Sudden closure of discharge valve, severe small Texas 1 discharge elbow water hammer, pump casing failed (300,000) 8 06/28/87 Palo Piping/water box Sudden closure of butterfly valve, water severe 15 Verde 1 hammer. Failure of bolts (500,000) min

Table 4-1 Turbine Building Flood Events Circulating Water System (continued)

Initiating Frequency Analysis *

Date Plant Leaking Description Flow Total Isol.

Component Rate Disch. Time gpm gals.

9 04,117/88 Fort St. Expansion joint Long tear in expansion joint due to 15,000 300,000 20 Vrain aging min 10 01/14/84 Peach Valve Improper valve line up during 3,000 200,000 1.1 hr Bottom 3 maintenance 11 09/17/86 Brunswick Sight glass Rupture of sight glass, flooding pit severe .5 hr 1 (150,000) 12 12/23/87 Su5<J1uehann Gasket Leaking gasket on condenser manway severe 12 a1 (60,000) min 13 06/74 Duane Valve Backwash valve failure during 12,000 -12 Arnold backwash process min 14 10/78 Surry 2 Valve Valve malfunction during maintenance small

Initiating Frequency Analysis Table 4-2 Fractional Distribution of CW Events and Recovery Characteristics Flow Flood Relative Critical" Nonrecovery Range Events Fraction Time Probability gpm N FRi t, NRi NRjXFRi 0-2000 1.02# .14 >24 hr negligible negligil>le 2-5000 3 .42 10 hr negligible negligil>le 5-10,000 2 .28 3 hr .001 2.8E-04 10-25,000 1 .14 105 min .03 4.2E-03 25-50,000 .1- .01 40 min .9 9.0E-03 50-200,000 .1- .01 15 min 1. 1.0E-02 TOTAL 7.22 2.3E-02 Critical Flood Volume =700,000 (Unit l+ESGR) + 680,000 (Unit 2) gal

- The Number of Events were Modified by Appropriate Correction Factors, CF, Ranging .1-.2, (See Text)

NUREG/CR-6144 4-22

Table 4-3 Service Water System Flood Events

Date Plant Leaking Description Flow Total Component Rate (gpm) Disch.

(gals.)

1 06n5 Surry 2 Pump seal Pump developed seal leak small small 2 04/19/89 River Bend Free:re seal Loss* of cooling to freeze seal during 1250 15000 maintenance 3 05/08/90 Clinton 1 Expansion joint Expansion joint develops a leak, pipe small supports damaged 4 06/16/86 Surry Expansion joint Corrosion of metal weld small 5 07/28/88 Susquehanna Pipe cap 1/2" drain cap ejected small 2

6 06/17/85 Quad Cities Vent line Vent line breaks, pump room partially small 1 filled 7 02/91 Palisades Pipe Pinhole leak through pipe small 8 Pilgrim Pipe Corrosion, pinhole leaks small 9 09/08/87 Susquehanna Pipe Flexible pipes had pinhole leaks, spraying small 1 water 10 05/26/82 Salem 2 Seam weld Failed motor cooler seam weld 100 5,000 11 06/23/81 Salem 2 Pipe cap 1/2" pipe cap broken off 25 12,000 12 10/17/80 Indian Point Cooling coil Containment Fan coolers leak, sump small 100,000 2 pump continuously running 13 02/27/90 ANO 1 Cooling coil Cooling coils leaks small 14 11/19/87 Robinson 2 Cooling coil Cooling coil .leaks small

Table 4-3 Service Water System Flood Events (continued)

Date Plant Leaking Description Flow Total Component Rate (gpm) Disch.

(gals.)

15 12,06/87 Salem 1 Cooling coil Cooling coil leaks small 16 05/14/87 Salem 1 Cooling coil Cooling coil leaks small

Table 4-4 Auxiliary Building Flood Events

DATE PLANT LEAKING DESCRIPTION FLOW TOTA COMPONENT RATE L gpm DISCH gals.

1 10/28/85 Waterford Pipe flange Steam leak near MFWP actuated the small small 3 deluge system, spraying on control cabinet causing pump trip 2 01/23/88 Palo Verde Fire suppression water discharge into 1 protected area 3 02/20/90 Turkey pump seal Pump failure in SF pool area created 18 18 3"small Point 3 gpm leak. Drain system partially in clogged, water collects in HX room room 4 09ft)5/89 McGuire 1 heat exchanger Heat exchanger leaks into building 10,000 5 03/14/89 Sheron Fire suppression system sprays on small Harris 1 MFWP causing internal shorts 6 01/29/87 Braidwood* Floor drain clogged, water backs up into small 1 upper cable spreading room. Water leaks through seals into control room.

7 13ft)8/84 Indian valve SW valve partially removed, developing large Point 2 a leak filling the pump room. Floor drain has insufficient capacity. Two CCW pump failed, SW pumps tripped to stop flooding.

8 04/19/89 River Bend freeze plug Failure of freeze plug 1250 15,000 9 04/78 Browns Weld fatigue causing joint failure. 80,000 Ferry 3 Condensate spill onto core spray pump room floor.

Table 4-4 Auxiliary Building Flood Events

DATE PLANT LEAKING DESCRIPTION FLOW TOTA COMPONENT RATE L gpm DISCH gals.

10 07n7 Brunswick Flange rupture Flange gasket rupture in the SW system. large 1 Pump and valve damage 11 11n1 Brunswick Drain Water accumulates due to backflow small 1 through drain system, oil pump shorts out 12 11n1 Dresden 2 River water spilled from HX outlet valve 3.5' in during test room 13 osn1 Trojan SF pool demineralizer head gasket fails, large Arnold large spill 14 10n4 Oconee Operator failed to isolate LPCI header, 3' in water accumulates in pump room room

Table 4-S Containment Building Spray Events Date Plant Description Total I I I I Release I

03/24/87 Calvert Cliffs Coolant was spraying from small 2 two pinholes 07/19/86 Lacross Water splashed off pipe, small solenoid malfunction 04/10/90 Cook 1 Steam and water from SG small blowdown permeated a fire detection control panel 09/03/89 Catawba2 Radiation monitor being small sprayed

4-27 NUREG/CR-6144

Table 4-6 Flood Initiating Frequency Mechanical Equipment Room #3 Flood Category Pipe Rupture Critical Nonrecovery Flood Initiating gpm Frequency (/yr) Time (min) Factor Frequency w/

Recovery (/yr)

~

I N

00 2600 2.2E-5 16 .01 2.2E-07

-1300 7.SE-05 30 .006 4.SE-07

- 650 1.lE-04 60 .0005 5.SE-08

325 2.4E-4 126 Negl. Negl.

< 150 2.9E-3 > 200 Negl. Negl.

I Total I I I I 7.3E-07 I

Table 4-7 Flood Initiating Frequency Summary Location Flood Frequency I I per yr I

Turbine Building Category 1 1.8E-04 Category2 1.0E-05 Auxiliary Building w/RWST 9.lE-05 w/o RWST 6.7E-05 Safeguard Area 9.3E-05 Containment 2.0E-05 RHR motor spray Mechanical Equipment 7.3E-07 Room No. #3 4-29 NUREG/CR-6144

5. Scenario Development 5.1 Introduction Accident scenarios due to flood events were developed by considering the internal event accident scenarios and their corresponding event trees. The flood events were examined with respect to the operating state and configuration and the actual effect on the decay heat removal function as represented by the RHR system.

The flood events and the corresponding scenarios were mapped to those event trees which represented similar accident progression characteristics. Modifications were made to remove or add additional events as required.

The system fault trees were also modified to take into account the effect of the actual flood event on the equipment located in the area.

The equipment flood fragility values were selected based on simple criteria. Electrical equipment is assumed to fail if the flood height reaches the location of any electrical component. Pumps, valves, or any other mechanical device without electrical connection or supply is assumed to operate even in flooded conditions.

This primarily involves manually operated valves or inline check valves. Centrifugal pumps are normally mounted with their electrical motors on the same pedestal and assumed to fail. However, vertically mounted pumps with extended shafts may have their motors located at higher elevation and are not as susceptible to flooding which occurs at lower elevations.

The flood scenario development also included some time estimates regarding operator actions and estimation of potential recovery options available to the operator. This enabled the proper determination of the corresponding human error rates. The flood scenarios at the different locations were not subdivided to smaller locations inside the specific buildings due to the open floor arrangements in both the Turbine and Auxiliary Buildings. The Safeguard Area was also handled as one unit, since only the overflow into the Auxiliary Building represents potential risk significant contribution. Based on these considerations, the following flood scenarios were developed for detailed analysis:

1. Turbine Building Flood - Large Category 1 flood and the dikes at the ESGR and Auxiliary Pipe Tunnel are overflown.

2. Auxiliary Building Flood - Flood in the Auxiliary Building collects in the basement and leads to equipment loss.

3. Safeguard Area Flood - Large flood in the Safeguard Area overflows into the Auxiliary Building leading to equipment loss.

4. Spray in Containment - One train of the RHR is lost due to direct spray on the RHR motors.

5. Mechanical Equipment Room No. #3 - Flood in the MER, overflowing into the unit ESGR leading to a two-unit station blackout.

5.2 Event Tree Approach and Assumptions, Time Window Approach The event trees developed for the internal event analysis were reviewed for their applicability to the flood events. The Surry plant developed and modified certain procedures to account for the possibility of flood events. These were also reviewed and incorporated into the system logic. The conditions at shutdown were

also reviewed for their applicability and w~re found that the flood events as determined in this study are not 5-1 NUREG/CR-6144

Scenario Development specifically shutdown-related. However, the event trees in the internal event study were specifically developed

for the shutdown conditions. The expected responses to adverse conditions due to flood events were discussed with plant personnel during the site visit and possible operator actions were analyzed in detail. The flood event tree structures are essentially the same as for the internal events to maintain consistency and compatibility.

In this PRA study, a mission time of 24 hr is used. That is, it is assumed that if the operators are able to prevent core damage from taking place during the first 24 hr subsequent to an initiating event, then core damage can be avoided due to the additional help that would become available. Thermal hydraulic calculations are used to determine the success criteria of the various systems or mitigation functions based on the 24-hr mission time. In addition, the calculations determine the timing of the accident scenarios and the time available for the operators to perform the needed actions.

Table 5-1 summarizes the success criteria as a functions of the decay heat. Table 5-2 summarizes the success criteria for the time windows and the timing of the important events that determine the time available for operator actions. Table 5-2 differs from Table 5-1 in the success criteria for feed and bleed. Table 5-1 shows the success criteria based on Virginia Power technical report 865 which is intended to maintain subcooling in the RCS to allow restoration of RHR, and is conservative regarding preventing core damage. Table 5-1 is more realistic and is used in the PRA analysis.

Gravity feed from RWST Gravity feed from RWST is established by opening the low head injection flow path from RWST to the RCS cold legs or hot legs. The RCS must be vented by removing the safety valves (SVs) on the pressurizer such that the gravity flow can be established. Depending on the decay heat level and the number of SVs removed, gravity feed may or may not provide 24 hr of cooling subsequent to the initiating event. The analysis documented in Section 5.1 of Reference 1 found that with 1 SV removed approximately 32 days after shutdown (5 MW decay heat), core damage takes place after 24 hr. Therefore, 32 days was chosen to be a boundary of the time windows. In the PRA model, for an accident initiating event that takes place after 32 days after shutdown, gravity feed from RWST is sufficient to terminate the accident. For accidents that start before 32 days after shutdown, gravity feed from RWST would provide some additional time for operators to restore failed mitigation systems. The additional amount of time for each of the time windows is listed in Table 5-2. These times are the estimated delays in core damage based on modeling of gravity feed with the MELCOR computer code, and the amount of time that subcooling is maintained as estimated in Attachment 9 of AP 27.00. Operator recovery using these times is modeled as recovery actions in the event tree analysis. The time available for the operators to establish gravity feed is assumed to be the same as time to core uncovery.

Feed and Spill Section 5.2 of Reference 1 documents the determination of success criteria of the feed-and-spill operation. There, both the Virginia Power Technical Report 865 and BNL analysis are discussed. Table 5-2 summarizes the success criteria. It is based on the Virginia Power Technical Report 865 which is the basis*

of AP 27.00. In AP 27.00, LHSI to hot legs is the preferred method for feed and spill. If hot leg injection is not available, then cold leg injection is used. If low pressure injection system (LHSI) is not available, then the high pressure injection system (HHSI) is used. Similar to LHSI, HHSI prefers hot leg injection to cold leg injection. The necessary number of PORVs is specified as a function of the time after shutdown. The operators are expected to throttle the injection flow to maintain 200 F° at the core exit thermal couple.

It should be mentioned that the success criteria in the Virginia Power technical report is intended to maintain subcooling in the RCS. In reality, more relaxed success criteria is sufficient for preventing core damage. For example, the Virginia Power technical report requires that two charging pumps and two PORVs would be NUREG/CR-6144 5-2

Scenario Development

needed for feed and spill during the first 129 hours0.00149 days 0.0358 hours 2.132936e-4 weeks 4.90845e-5 months . If only one charging pump and 1 PORV are available, feed and bleed should be sufficient to keep the core covered as long as water is available in the RWST. The success criteria of Table 5-2 is used in this study.

In order to account for the low shutoff head of the LHSI pumps, the time at which RCS pressure reaches 165 psia was determined and used as the time available for an operator to use LHSI. For HHSI, it is assumed that the time to core damage is the time available. In the high level fault trees, two separate human error events are used.

Recirculation Table 5-2 lists the time to RWST depletion for each of the time windows. As the level in the RWST becomes low, the operators are instructed to establish either RWST cross connect or high head recirculation. Section 5.2 of Reference 1 estimated that approximately 10 days after shutdown, recirculation is not needed. The calculation shows that with successful feed and spill, core damage will not occur within 24 hr after the loss of an RHR initiating event. Therefore, high pressure recirculation is needed only during the first 10 days after shutdown. This 10 days is used to define the boundary of Time Windows 2 and 3. In Window 1, two RWSTs are not enough to support 24 hr of feed-and-spill operation. Therefore, recirculation is needed. In Window 2, a cross connect of RWST provides 24 hr of feed-and-spill operation. In the fault trees for recirculation in Window 2, cross connection of RWSTs is taken into account.

AP27.00 provides instructions on how high pressure recirculation can be established, and states the possible need for the spray recirculation heat exchangers. High pressure recirculation is done by using the low pressure injection pump to take suction from the containment sump, and discharge to the suction of the high pressure injection system. In the fault tree analysis, two alternative methods o! recirculation are also modeled. They are low pressure feed and steam taking suction from the containment sump, and low pressure feed and spill taking suction from the sump. In these modes of operation, only low head injection is needed. The feed and steam mode requires that the safety valves be removed to provide sufficient vent path, and does not require cooling of the sump water. The feed-and-spill operation requires operation of the spray recirculation systems to cool the water in the sump, such that subcooling in the reactor vessel can be established.

Spray Recirculation In Section 5.2 of Reference 1, it is estimated that during the first 10 days after shutdown, the RWST inventory is not sufficient for feed and spill and recirculation is needed. Recirculation would introduce steam into the containment, and the potential of containment failure exists. In the Level 1 PRA, it is assumed that if spray recirculation is not available, then containment would fail. The impact of containment failure on recirculation is that a small probability, 0.02, exists that the low head pumps would lose their needed net positive suction head. This failure cause is similar to the failure mode considered in NUREG-1150: . Failure of recirculation is modeled as a potential failure mode of the low head injection pumps.

Another function of the spray recirculation systems is to support the low pressure recirculation operation by taking suction from the containment sump. It cools the containment sump water to make it possible to maintain subcooling in the reactor vessel.

Reflux Cooling The success criteria for reflux cooling was based on the Virginia Power Technical Report 865.

It is also specified in AP 27.00. There, the number of steam generators (SGs) needed is specified as a function of decay heat. It is known that the success criteria is conservative. Because it is specified in the procedure, it is assumed that the operators would follow the procedure. As part of the procedure for

establishing reflux cooling, the operators are supposed to close the vessel head vent and PORVs to ensure that 5-3 NUREG/CR-6144

Scenario Development there is no inventory loss through these openings. In Section 5.3 of Reference 1, it was estimated that the

leakage through the tygon tube connected to the vessel head is insignificant. If the Pressure Relief Tank (PR1) rupture disks are ruptured, the leakage through an open PORV is large enough to lead to core damage in a few hours. If reflux cooling is established before the PRT is ruptured, the PRT becomes a part of the RCS boundary, and no significant inventory loss is expected. Therefore, if the operators can establish reflux cooling by venting the secondary side of the SGs before PRT rupture disks rupture, then there is no need to close the PORVs. If reflux cooling is established after the PRT ruptures, then it is necessary to close the PORVs to prevent inventory loss. It is assumed that reflux cooling is sufficient to remove decay heat if it is established before core uncovery occurs. Given that reflux cooling is established, the SG inventory is sufficient for approximately 10 hours1.157407e-4 days 0.00278 hours 1.653439e-5 weeks 3.805e-6 months . (See Table 5-2.) Feeding the SG after the inventory becomes low is modeled as a long-term operator actions.

Event Tree Nomenclature (1) The name of an event tree consists of four parts: the flood scenario, the initiating event, window number and POS. For example, "F1R3WIR6" represents the event tree for nonrecoverable loss of RHR (R3) in Window 1 (Wl) in POS 6 of a refueling outage (R6) in Flood Scenario Fl.

Flood Scenario Fl-Turbine Building Flood Scenario 1 F2-Turbine Building Flood Scenario 2 F3-Auxiliary Building Flood Scenario 3 F4-Auxiliary Building Flood Scenario 4 PS-Safeguard Area Flood Scenario 5 F6-Containment Flood Scenario 6 F7-Mechanica1Equipment Room 3, Flood Scenario 7 Initiating Event R3-Nonrecoverable loss of RHR R4-nonrecoverable loss of operating train of RHR B2-2 Unit blackout POS and Outage Type R6-POS 6 of a refueling outage RlO-POS 10 of a refueling outage D6-POS 6 of a drained maintenance outage Window Number Wl-Window 1 W2-Window2 W3-Window3 W4-Window4 NUREG/CR-6144 5-4

Scenario Development (2) The names of event tree top events are chosen by adding a prefix to the event tree name (without the POS and flood scenario POS designator) to represent the generic type of the top event. For example, "SR3Wl" has a prefix of "S" to indicate the reflux cooling method. The high level fault trees were built in such a way that they depend on the initiating event and time window, but independent of the POSs.

Therefore, the POS designators are not needed in naming the top events. The following is a list of the prefixes for the generic top events.

I-Initiating Event Frequency Calculation H-Recovery of Support System Failures M-RCS Makeup R-Restore RHR V-RCS Vented F-RCS Feed and Bleed S-Steam Generator Feed and Bleed G-Gravity Feed from RWST N-Recovery of Off-Site Power C-High Pressure Recirculation P-Spray Recirculation-both ISR and OSR (3) The names of human error events modeled in the system fault trees follow the convention of NUREG/CR-4550. The name of high level human error events consists of the following fields separated by hyphens:

(a) The first letter in the name is either "D" representing failure to Diagnose, or a letter representing failure to take action in a top event, "F', "G", etc.

(b) Name of event tree (c) A one-letter prefix representing the specific failure of the generic top event type For example, SF5W1S2 represents a sequence in the event tree "F5Wl," where the operator fails to establish reflux cooling in Window 1. In this example, "S2" represents bleeding the SGs prior to rupture of the PRT rupture disk. DF5Wl represents failure to diagnose a event F5 (flood in the Safeguard Area overflowing into the Auxiliary Building) in Window 1, such that core damage results. The human error probabilities (HEPs) are dependent on the specific flood scenario, which is incorporated into the numerical model through "change sets." In this case, the numerical values of the HEPs are always set for each separate flood scenario before each run without changing the designators.

_ Basic event failures representing the flood-related failure of certain components were also introduced in the system fault trees. The names were derived from the basic event names already established by adding an FL designator upfront and removing the failure-specific designator from the basic event. For example, the basic event representing the failure of charging pump 1B to start is HPI-MDP-FS-CHlB. The flood basic event disabling this pump for a flood becomes FL-HPI-MDP-CHlB. All other conventions used in the internal event analysis were adhered to. The human error designator was not specifically changed for the flood, however, its value was appropriately adjusted to reflect the flood-specific situation, timing, and prospective recovery options. The success criterion used in the internal event study was also utilized for the flood analysis with special emphasis on the unavailability of certain systems in flood events which limit the options available to the operator for alternate heat removal.

5-5 NUREG/CR-6144

Scenario Development Following the IPE analysis, the plant has initiated and completed a number of modifications in order to reduce the risk impact of expected flood events. The present analysis has also incorporated some of these modifications as follows:

Procedural modifications to identify the location of specific CW/SW flood sources and perform necessary mitigating actions such as closing isolation valves, opening/closing doors, etc.

Inspection program was designed and placed to determine the status of the CW/SW expansion joints and simultaneously a replacement program for the expansion joints material was also established.

Program for periodic verification of proper-strength bolts on CW isolation valve operators, positive locking devices, periodic visual inspection of operator-to-body bolted connections.

Inspection program for the Limitorque operator.

Installation of anti-reverse backflow devices in drain lines from the ESG R, MER, Electrical Tunnels to the Turbine Building, from the charging pump cubicles to the Auxiliary Building sump.

Two pipe penetrations between the charging pump cubicles and the rest of the Auxiliary Building were sealed.

In addition, the plant has proposed other design modifications and changes which are presently going through various design evaluations. Some of these were selected for further sensitivity studies and documented in Section 6.

5.3 Human Interface Analysis The approach used for the evaluation of operator actions in response to the flood initiating events is the same as that used for the internal event analysis[ 5* 1l. The dynamic operator actions analyzed in this study are listed in Table 5-1 (i.e., fault tree high level human action events). All of the human actions with unique numerical values are quantified, according to the descriptions in Table 5-1. A number of human error actions defined in Table 5-1 have similar numerical values and they are used with the appropriate values derived for the similar human error event in the event sequence quantification.

Human errors and human solutions are a vital part of nuclear power plant operation and accident response.

In fact, the causes for nearly all plant problems can ultimately be traced to some form of human fallibility, and nearly all plant problems can be solved by humans if they are provided with the appropriate information, guidance, and tools. Within the context of this study, however, the evaluation of human errors encompasses only those actions accomplished within the plant that directly

impact the availability of support or safety systems at the time of the initiating event

mitigate against core damage during the sequence of events following the initiating event With this in mind, the following types of human actions are evaluated:

Routine Actions before an Initiating Event. Routine actions considered in the PRA involve restoring a component or flow path to normal after completing the testing, inspection, or maintenance and ensuring that the sensing equipment is correctly aligned and calibrated for automatic response to emergency actuation conditions. Errors that are important to plant risk leave safety-related equipment disabled or in an undetected, misaligned state, causing it to be unavailable to accomplish its function on demand during an event sequence.

NUREG/CR-6144 5-6

Scenario Development

Actions that Can Cause Initiating Events. Actions that can initiate plant transients are implicitly accounted for in the quantification of initiating event frequencies to the extent that these human actions are the cause of such events. Generic plant data are used to assign total initiating event frequencies of which human errors are only one cause. Therefore, these types of human actions are accounted for in the initiating event analysis and are not discussed here further.

Dynamic Operator Actions Accomplished during the Plant Response to an Initiator. Guided by the plant abnormal and emergency response procedures, the operators make active decisions and take appropriate actions in response to a complex series of stimuli during the sequence of events following an initiator.

They are scenario specific and include well-defined tasks for manual initiation, control, and alignment of plant emergency equipment or selected backup systems. Usually, the operators must complete a particular activity within a specified period of time to avoid an unfavorable change in the state of the plant. These actions are an integral part of the plant response to the initiating event.

Recovery Actions. Recovery actions generally involve recovery from failures that completely or partially disable the standard system response during a plant transient. They generally involve alignment of alternate systems or repair and restoration of the failed system. They may be well defined in procedures or based on general guidance and the training and knowledge of the operators and plant staff. For the purposes of this study, recovery actions are those identified through the first quantification, after the dominant scenarios have been identified.

5.3.1 Incorporation of Human Actions into the Plant Model e approach to human interaction modeling provides a systematic and consistent framework for identifying, evaluating, and documenting human responses at all levels of the study. The approach emph~sizes a detailed interview with plant operators and a thorough review of their procedures.

Quantified (HEP) can be incorporated into the plant model in a number of ways, depending on the influence of the action on other events in the sequence and, in particular, how they impact the quantification of other events. The potential dependencies of HEPs on other elements of the plant model can strongly affect how the action and subsequent events are quantified. There are three general types, as follows: '

Plant-human dependency accounts for the impact of the plant instrumentation and other performance indications on the ability of the operators to accomplish the action. They are scenario dependent and influence the degree of difficulty that the operators face when responding to the scenario.

" Human-plant dependency accounts for those actions that can cause more than one system to fail. The event trees that are used to. express the plant response to an initiating event can serve as a vehicle to represent these dependencies.

Human-human dependency involves the increased potential for making a series of errors once the first error is made.

5-7 NUREG/CR-6144

Scenario Development

Depending on the type of dependency involved, any one of the following approaches can be used to incorporate human actions into the overall risk model:

An action may be included within the system fault trees if the human error affects subsequent events in the sequence in the same way as hardware causes of system failure. Errors that occur before the initiating event, and some dynamic operator actions, fall into this category.

If failure of an operator action that fails a system has a different effect on the subsequent response of the plant than a hardware failure, a separate top event may be used to represent the human action. Dynamic operator actions may, but not always, fall into this category.

Recovery actions are often appended to accident sequence cutsets as separate basic events. In this way, they can be made very cutset-specific and not alter the remainder of the model.

S.3.2 Routine Actions before an Initiating Event Routine human actions considered in the PRA are system-specific activities performed by one or more operations staff members as part of their normal workday duties to align a safety function properly before leaving it in its ready condition. These include:

realignment of a component or flow path to normal after completing the testing, inspection, or maintenance

removal of jumpers or other temporary system alterations to restore it back to service

calibration and alignment of sensing equipment to ensure proper automatic response to emergency actuation conditions Errors that are important to plant risk cause the system to be unavailable to accomplish its function properly following an initiating event. Failure modes that could produce this condition involve, primarily, leaving safety-related equipment disabled or in an undetected misaligned state, causing it to fail to operate upon demand The system analyst is responsible for evaluating routine actions that cause equipment unavailability. This approach is used because the system analyst is most familiar with the equipment, its location, control room alarms and indications, and details of all procedures and other guidance impacting the maintenance and

~urveillance testing of the system.

Normally, only surveillance procedures are evaluated to identify specific causes of equipment unavailability.

Maintenance procedures are evaluated only if the operability of the system is not verified by a surveillance procedure at the conclusion of the maintenance or repair activity.

S.3.3 Methodology for Evaluation of Dynamic Operator Actions and Recovery Actions Dynamic operator actions and recovery actions that take place following an initiator are identified and qualitatively described during the construction of the plant model event trees and quantification of the accident sequence, respectively. The licensed plant operators were consulted for evaluation and feedback on the NUREG/CR-6144 5-8

Scenario Development process for restoring RHR cooling and establishing alternate decay heat removal. The qualitative descriptions for the operator actions are expanded to account for all factors significant to quantification. The methodology laid out in this section is an abbreviated approach to adapt to project schedule and scope. Rather than evaluation by teams of operators, quantification is based on the judgment of the analysts. Because of similarity in assigned weights, only one calibration group was used.

The following describes the qualitative process by which the actions are identified and the procedure used for evaluations within the context of the success failure likelihood (SLIM-MAUDE) index methodology.

S.3.3.1 Qualitative Evaluation The purposes of the qualitative evaluation are to,

Identify dynamic operator actions to include in the event tree sequence evaluation

Identify recovery actions to realistically model the accident sequence

Ensure that the impact of the success or failure of those actions is properly modeled

Develop descriptions of those actions in a form that will facilitate evaluation During event tree construction and accident sequence evaluation, a variety of operator tasks are considered for inclusion in the model. These include

Manual actions required in abnormal and emergency procedures to prevent core damage following an initiating event

Control of preferred cooling systems

Backup of automatically controlled systems

Immediate response to failures of active systems Once individual actions are identified for evaluation, the action boundary conditions, success criteria, and event scenario timing are identified and recorded on the Operator Response Forms. The purpose of this form is to provide a consistent format to convey the context of the action to the evaluation team who will analyze its degree of difficulty, and to provide a short summary of what is required to accomplish it. The available thermodynamic calculations supporting the timing considerations and arguments supporting engineering judgments regarding timing are contained in Chapter 5 of Reference 1.

The first two sections of the form set up the situation facing the operators. They describe where in the event tree model this action will take place and what indications the operators are expected to respond to in the control room. The next three sections describe what is involved in accomplishing the action, the relevant training and experiences, and those factors that compete for the operators' attention or divert them from the task. Two sections are then provided to describe what happens in the event sequence model if the action succeeds or fails. Finally, the time frame over which the action can be expected to be accomplished is

addressed 5-9 NUREG/CR-6144

Scenario Development Plant-human dependencies are described explicitly on the Operator Response Form, both in the section that relates the action to the plant model and in the discussion of required actions and competing factors. This permits the assessment team to understand the context of the action during the quantification of the action so that the dependencies can be reflected properly in the final error frequency.

The Operator Response Form presents human-human dependencies by asking the assessment team to identify with the situation at hand and to consider how an operating team may have made previous errors from which they must recover. They are then asked to identify ways to recognize and recover from previous errors when quantifying the dependent action.

5.3.3.2 Quantitative Evaluation This study uses an adaptation of the success likelihood index methodology (SLIM) to elicit judgment and to convert the operator evaluations into quantitative error frequencies. SLIM is based on the following assumptions:

The likelihood of operator error in a particular situation depends on the combined effects of a relatively small set of performance-shapingfactors (PSF) that influence the operator's ability to accomplish the action successfully.

Evaluators can address each of these PSFs independently so that the overall evaluation can be expressed as the sum of the results of each PSF to form a numerical likelihood index.

The actual quantitative error rate is related to the numerical likelihood index by a logarithmic relationship.

The logarithmic relationship can be calibrated on a situational basis by use of appropriately selected calibration tasks having generally accepted error rates.

The SLIM procedure was adapted by defining a small set of generic PSFs that are judged to encompass the major focuses of cognitive activity. Seven PSFs have been chosen to relate the impact of the following

Conditions of the work setting under which the action must be accomplished. The PSFs are as follows:

significant preceding and concurrent actions plant interface and indications adequacy of time to accomplish the action

Requirements of the task itself. The PSFs are as follows:

procedural guidance complexity of the task relative to resources, coordination, and location NUREG/CR-6144 5-10

Scenario Development

.*

Psychological and cognitive condition of the operators. The PSFs are as follows:

training and experience relative to the action stress due to the situation and environmental conditions Performance-shaping factors are rated against two criteria:

A score relates the degree to which the conditions of PSF help or hinder the operator to perform the action.

A weight relates the relative influence of each PSF on the likelihood of the success of the action.

The evaluation of dynamic human errors with SLIM is made consistent by the development of a set of forms and instructions to explain and expand on the rating procedures for the PSFs.

The SLIM methodology has been modified so that the evaluators scale the degree of difficulty, rather than the potential for success, when they score the action. This change in orientation produces a failure likelihood index (FLI) rather than a success likelihood index. This approach has the advantage of quantitatively highlighting the causes of operator difficulty. A high score combined with a high weight produces a large FU compared to other ratings. This permits efficient analysis of the potential problem areas and trends.

The independence of the PSFs is addressed by the definition at the top of each evaluation form that emphasizes the different aspects of the cognitive process that each PSF is intended to address. Another major premise of the SLIM methodology is that the evaluation team can rate the weight and score independently.

During evaluation of the operator actions, the evaluation team is also requested to consider a number of possible errors. These include:

Nonresponse Errors, Also Called Errors of Omission. This would include problems generated by both the plant interface and the competition of other actions.

Time and Resource Limitations. For certain actions, the operators are requested to identify the number of people and the coordination required to get the job done. The degree of difficulty will then be impacted by the personnel and communications they have available.

Nonviable Errors. Under some conditions, the operators may correctly diagnose the accident scenario but select the wrong response. These errors are believed to be gc)Verned by operator slips, e.g., selecting the wrong controls for the tasks. The control room feedback problems that could keep such errors from being detected are also considered.

S.3.3.3 Quantification Process The quantification process is done in a series of stages.

First, a normalized weight for each PSF is obtained by dividing the weight assigned by the evaluation team by the total of all the weights for that particular action .

5-11 NUREG/CR-6144

Scenario Development The FLI is calculated by multiplying the normalized weight of the PSF by its score and adding that result to similar results for the other PSFS, or where i = PSF that has an influence on the error rate of the action.

wi = weight of PSFi, normalized so that E w; = 1.

Si = degree of difficulty score for PSF;, from O to 10.

The error rate of each action is estimated by comparing the overall FLI to a correlation that follows the relationship:

Logarithm (human error rate)= A+ B(FLI)

The coefficients of the correlation are obtained from a least squares fit of the FLI of calibration actions that have reasonable or generally accepted error rates in the industry.

To provide error rates that are consistent with other studies, the calibration of the human error rate model uses well-defined actions obtained from evaluations for other PRAs and other statistical or analytical evidence of failure frequencies for these actions. The calibration procedure should ensure that the numerical error

rate estimates are realistic and consistent with available data, observed human behavior, and the results from comparable expert evaluations of similar activities.

The use of some combinations of calibration actions may produce human error rates of 1.0 per demand for FLI values of less than 10. When this occurs, all actions with an FLI above that value are quantified as being guaranteed to fail.

5.3.3.4 Summary The error rates resulting from the evaluation and the quantification are displayed in tabular format. This permits easy review, comparison, and identificationof the most important factors influencing each assessment.

It is important to recognize that the quantification of human error rates is only a small portion of the information obtained from the SLIM approach. The trends of weights and scores provide much valuable information regarding the evaluator's judgment with respect to the focus of safety-related actions and the difficulties involved in accomplishing them.

Table 5.3 gives the definition of the various dynamic human actions for the flood initiating events. The quantification process and the weights and scoring for the PFSs are listed in Table 5.4.

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Scenario Development

5.3.4 Actions while at Mid-Loop Several hundred specific actions are considered in this analysis, and over 150 are quantified directly. Others are assigned HEPs equal to one of those actually quantified directly because of similarities in required response, cues, timing, and all other factors.

The large number of specific action scenarios are actually special cases of a small number of functional responses defined by plant procedures and colored by special conditions of the sequence of events that leads to the need for action. To aid in understanding the many special cases, we organize their presentation under the following topics:

Human Responses global actions primary cognitive response specific activities recovery actions

Factors Affecting Response initiating event previous/concurrent hardware failures and human actions other performance shaping factors 5.4 Turbine Building Flood Events - Flood Scenarios 1, 2 Flood events in the Turbine Building have been classed into two categories:

Category 1 events are large scale flood occurrences, where the dewatering capacity of the building sump pumps is insufficient. The events are initiated by the rupture of one of the expansion joints in the CW or SW system. The resulting leak may not be isolated in sufficient time to prevent the overflow of the flood dikes in front of the unit ESGR. The Amertap, SW valve pits, and the building sump pits are filled and as the water level rises, the sump pump motor control center is shorted, stopping the building sump pumps. The flood in the Turbine Building itself has no significant safety impact as most of the equipment is non-safety-related or would not compromise the operation of the RHR system.

Category 2 flood events flood the SW valve pit compromising the operation of the recirculation heat exchangers. The use of these heat exchangers is required only in long-term accident sequences to mitigate containment failure. It does not directly affect the operation of the RHR system and as such does not lead to loss of decay heat removal. For this reason, this type of flood event is not analyzed further .

5-13 NUREG/CR-6144

Scenario Development The Category 1 flood events eventually overflow the flood dikes and water enters into the unit ESGR and the Auxiliary Building Pipe Tunnel. The most significant damage arises from water entering into the ESGR before any appreciable water can collect in the Auxiliary Building basement. The amount of water required to cause damage in the Auxiliary Building is larger than that required for the ESGR. Therefore, the flood scenario may neglect the damage caused in the Auxiliary Bui~ding.

As the water enters into the unit ESGR, it is expected that a number of electrical equipment housed in cabinets will short out rendering the associated equipment unavailable. Based on the field inspection, it is estimated that all 480 V buses and numerous MCCs will short out as the water level reaches about 4". This will most likely cause the loss of all 4 kV buses leading to a unit station blackout. The unit DC power is expected to be lost as the water level further increases to about 12".

Therefore, two sub-scenarios are discussed:

Scenario 1: Event Trees, FlB2WlR6, FlB2WlD6, F1B2W2R6, F1B2W2D6, F1B2W3R6, F1B2W3D6, F1B2W3R10, F1B1W4R6, F1B2W4D6, F1B2W4R10 Two-unit station blackout with instrumentation power available providing power to certain safety related instrumentation and indication. The unit non-safety-related power supplies may be used to provide power to certain non-safety-related equipment, however, the actual extent of remaining power supplies is uncertain. Therefore, a two-unit complete station blackout is conservatively assumed and the corresponding internal event tree B2R6, B2D6, and B2Rl0 was used to describe Scenario la. The relative probability of this scenario is estimated at P(Scenario la)= .8 given that the flood enters the ESGR.

Scenario 2: Event Trees, FlB2WlR6, F2B2W1D6, F2B2W2R6, F2B2W2D6, F2B2W3R6, F2B2W3D6, F2B2W3Rl0, F2B2W4R6, F2B2W4D6, F2B2W4R10 Two-unit station blackout with instrumentation unavailable or unreliable. In this case the flood height inside the ESGR reaches the DC fuse panel causing the partial or total loss of the DC power which eventually leads to the loss of instrumentation. The scenario is again described by the properly modified station blackout event trees with the human errors describing the difficulties related to the instrumentation control and indications. The relative probability of this scenario is estimated at P(Scenario lb)=.2.

Figures 5-1-10 and 5-11-20 represent the flood events trees for flood Scenarios Fl and F2, respectively. The top events for the_ flood event trees for these scenarios are briefly summarized in the following. The event tree structure for the flood events is such that systems which are failed by the initial conditions are not included. However, these may be utilized in the recovery phase and thus, will also be summarized at the end of each event tree top event description.

NUREG/CR-6144 5-14

Scenario Development IB2Wl, IB2W2, IB2W3 , IB2W4

Flood Initiator These top events represent the flood occurrence probability in the respective POSs (R6 - POS 6 Refueling, D6 - POS 6 Drained Maintenance, RIO - POS 10 Refueling). The flood frequency was derived based on the operating experience and is discussed in Section 3. The combination of this top event with the event tree initiator gives the flood frequency in the corresponding POS.

VWl, VW2, VW3, VW4

RCS Initially Vented This top event represents the probability that the RCS is initially vented through the removal of the pressurizer safety valves. The probability was estimated at 0.01 in Window 1, 0.05 in Window 2, .9 in Window 3, and .3 in Window 4, which is the same as used in the internal event analysis. Gravity feed may only be accomplished if the RCS is vented, however, reflux cooling is not possible in this plant configuration.

GB2Wl, GB2W2, GB2W3, GB2W4

Gravity Feed from RWST The low pressure injection pathway may be utilized to gravity feed the RCS from the RWST by opening a normally closed valve. The success of this top event requires that the RCS be vented. In most cases it provides additional time to provide alternate means of heat removal.

SB2Wl, SB2W2, SB2W3, SB2W4

Steam Generator Feed and Bleed This top event, representing the possibility of using reflux cooling method to remove decay heat is not included in the event trees, since initially it failed (depends on the semi-vital bus located in the ESGR). However, the system may be used in the recovery phase, if instrument air can be reestablished. It requires the operation of the secondary side relief through the SG PO RVs or steam dump to the main condenser or to the turbine deck. The operation of the steam dump valves requires instrument air and DC power, which may be lost during a station blackout situation due to a flood event in the Turbine Building. The instrument air compressors have alternate diesel-driven compressors installed in the yard area, which may be started to provide instrument air.

5.5 Auxiliary Building Flood Events - Flood Scenarios 3, 4 Large scale flood events in the Auxiliary Building are primarily due to pipe ruptures in the building connected to either the fire water system or to the water source from the RWST. The RWST is the main source of supply for various safety systems which serve as alternate or backup heat removal systems to the RHR system.

Therefore, the availability of the RWST is an important characteristic of each accident scenario. Accordingly, the flood events in the Auxiliary Building are separated into two categories with and without RWST supply availability.

The open structure of the building assures that any flood originating even at higher elevations eventually will drain to the basement at Elevation 2'. Flood levels reaching the CCW pumps would disable the CCW system on both units and consequently the operating RHR system would also be disabled by losing heat rejection capability in the RHR heat exchangers.

5-15 NUREG/CR-6144

Scenario Development A large flood inside the charging pump cubicles would disable the charging pumps and in addition, a number of motor operated valves in the HPI system would also become disabled assuming that the operators would not operate under a wet environment. A potential alternate heat removal technique is to utilize the SG recirculation system to transfer heat to the CCW system from the SGs. However, this system also becomes unavailable, since the CCW system itself is disabled by the flood and also the recirculation pumps are located in the same 2' elevation losing their function.

The flood scenarios in the Auxiliary Building have been modeled by utilizing the nonrecoverable loss of RHR internal event trees RHR3. The flood event trees corresponding to these two scenarios are presented in Figure 5-21-40 for the three operating configuration, POS 6 Refueling, Drained maintenance and POS 10 Refueling. The top events on these event trees are essentially the same as for the internal events with the exception of the high level HEPs and that the system fault trees are modified to take into account equipment damaged by the flood event.

Scenario 3: Event Trees, F3R3W1D6, F3R3W1R6, F3R3W2D6, F3R3W2R6, F3R3W3D6, F3R3W3R6, F3R3W3Rl, F3R3W4D6, F3R3W4R6, F3R3W4Rl Large scale flood in the Auxiliary Building basement with the RWST available. A number of CCW, SG recirculation pumps, and a few motor operated valves become unavailable. The event trees are presented in Figures 5-21-30.

Scenario 4: Event Trees, F4R3W1D6, F4R3W1R6, F4R3W2D6, F4R3W2R6, F4R3W3D6, F4R3W3R6, F4R3W3Rl, F4R3W4D6, F4R3W4R6, F4R3WR1 Large scale flood in the Auxiliary Building basement inside the charging pump cubicles with the RWST unavailable. The overflowing flood from the cubicles cause the failure of the charging, CCW.

and SG recirculation pumps, and motor operated valves in the HPI system also become unavailable.

Isolation of the flood still causes the loss of charging and low pressure injection function due to the unavailability of the RWST. The event trees are presented in Figures 5-31-40.

IR3Wl, IR3W2, IR3W3, IR3W4 - Initiating Event IR4Wl, IR4W2, IR4W3, IR4W4 This event in combination of the initiating event represents the flood frequency in the respective POS and time window which is expected to occur in the Auxiliary Building.

VWl, VW2, VW3, VW4 - RCS Initially Vented This event represents the conditions that the RCS is vented through the removal of the pressurizer safety valves. The resulting opening is required for successful operation of the gravity feed method. However, if the RCS is open, the reflux cooling mode of heat removal through the SG cannot be accomplished. The event is estimated to have the probability value of 0.01 (Wl), .05 (W2), .9 (W3), and .3 (W4).

NUREG/CR-6144 5-16

Scenario Development R3Wl, SR3W2, SR3W3, SR3W4 - Steam Generator Feed and Bleed SR4Wl, SR4W2, SR3W3, SR4W4 This event represents the successful use of the reflux cooling method which is possible when the RCS loops are not isolated and the secondary side of the SGs is filled. The steam generated in the secondary side has to be relieved through either the secondary side PORVs or the steam dump valves.

FR3Wl, FR3W2, FR3W3, FR3W4 - Primary Feed and Bleed This top event represents the primary feed and bleed function using the charging or the low pressure injection pumps. In this mode, water is injected into the system from the RWST and is allowed to bleed through the PORVs. The PORVs are open with the block valves deenergized. The charging pump cubicles have an opening about 4' from the basement floor and the charging pumps may be disabled when the water level reaches that elevation. This top event is present only in Scenario 3, since it is failed in Scenario 4 due to the unavailability of the RWST. The Unit 2 charging pumps and RWST may be available and is considered in the recovery phase of the analysis.

GR3Wl, GR3W2, GR3W3, GR3W4 - Gravity Feed from RWST If the pressurizer safety valves are removed, gravity feed is a viable option for delaying boiling in the core.

This may be accomplished by opening a normally closed valve in the low pressure injection line and allowing the RWST water to gravity drain "into the RCS. This will delay core heatup by hours after that period ltemate heat removal method has to be found or reestablished. Timing was established by system thermal-ydraulic calculations taking into account decay heat generation and the static head in the RWST. Cross connection to the Unit 2 RWST is also considered. The top event is failed in Scenario 4, since the RWST is unavailable for feed and bleed. It is still present in the event tree for calculational reasons in order to correctly calculate the total CDF due to the initiating event.

5.6 Safeguard Area Flood Events

Flood Scenario S The potentially risk significant flood events originating in this are those which spill over into the Auxiliary Building through a pipe tunnel connecting the two areas. In particular, flood events in the sub-area containing the valves and piping of the low pressure injection system are of interest due to the potential loss of the low pressure injection path. These floods have to first spill over to the other sub-area in the Safeguard Area through a pipe opening and then could overflow into the Auxiliary Building.

The scenario is similar to the Auxiliary Building flood scenarios, except for the additional equipment damage in the Safeguard Area itself. From the safety point of view, only the low pressure injection and the AFW system must be considered. The AFW system located in the other sub-area is required for secondary side heat removal and is modeled in the event trees (reflux cooling top event, function "S").

The event trees used for this scenario are the nonrecoverable Loss of RHR or RHR3 trees used in the Auxiliary Building analysis. The effect of flood in the Safeguard Area is treated through changes in the system fault trees by setting the components affected by flood to a definite failed state.

Scenario 5: Event Trees, F5R3W1D6, FSR3W1R6, F5R3W2D6, FSR3W2R6, 5-17 NUREG/CR-6144

Scenario Development F5R3W3D6, F5R3W3R6, F5R3W3Rl0, F5R3W4D6, F5R3W4R6, F5R3W4Rl0 Large scale flood in the Safeguard Area due to rupture in the RWST supply line. The flood source RWST is unavailable for supplying water to the RCS, the closed discharge valves LPI-1890B/C are flooded and may not be remotely or manually operated. The flood overflows into the Auxiliary Building, flooding the basement and disabling the CCW system and a number of motor operated valves and other secondary systems. In this scenario, forced feed and bleed and/or gravity feed is unavailable in this scenario due to the unavailability of the RWST. The event trees are presented in Figures 5-41-50.

5. 7 Containment Spray Events - Flood Scenario 6 The spray event is postulated to occur in the containment disabling the operating RHR train. This event has no other effect and can be analyzed with the Loss of Operating Train of RHR (RHR4) event tree of the internal event analysis. It effectively represents failures that may not be recovered within the time frame of accident scenarios that may result.

Scenario 6: Event Trees, F6R4W1D6, F6R4W1R6, F6R4W2D6, F6R4W2R6, F6R4W3D6, F6R4W3R6, F6R4W3R10, F6R4W4D6, F6R4W4R6, F6R4W4R10 All the top events in these event trees are identical to the previously discussed event trees with the exception of RR4Wl, RR4W2, RR4W3, RR4W4. The event trees are presented in Figures 5-51-60.

RR4Wl, RR4W2, RR4W3, RR4W4 - Restoration of RHR This top event represents the restoration of the RHR after a spray event. This involves the local venting of the RHR pumps, verifying the heat sink and the restart of an RHR pump.

5.8 Mechanical Equipment Room No. #3. - Flood Scenario 7 Flood events occurring in this area would overflow the flood dikes at the entrance to the plant ESGR area and eventually cause the loss of all AC power. The consequences of this flood scenario is identical to the Turbine Building flood events (Flood Scenario 1) and are analyzed in a similar manner. In order to simplify the analysis, the same event trees were utilized to determine the CDF contribution from this flood scenario with appropriate changes in the data (Fig. 5-61-70).

5.9 References

1. Ch.u, T-L., et.al., "Evaluation of Potential Severe Accidents During Low Power and Shutdown Operations at Surry Unit-1: Analysis of Core Damage Frequency from Internal Events During Mid-Loop Operations." NUREG/CR-6144, Volume 2, June 1994.

NUREG/CR-6144 5-18

Scenario Development Virginia Power, Surry Nuclear Power Plant, Individual Plant Examination Program, Appendix E:

Internal Flooding.

Internal Flooding Analysis for the Individual Plant Examination, Supplemental Report, Surry Units 1 and 2, Virginia Electric and Power Company, November 1991.

5-19 NUREG/CR-6144

UNITY F1IB2W1 SEQ # END-S' I 1 I

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UNITY F5IR3W4 F5SR3W4 SEQ # END 1 OK 2 OK 3 CD Fig. 5.48 SAFEGUARD BUILDING FLOOD SCENARIO 5 F5R3W4D6

UNITY F5IR3W4 VW4 F5GR3W4 SEQ # END 1 OK 2 OK 3 CD 4 CD Fig. 5.49 SAFEGUARD BUILDING FLOOD SCENARIO 5 F5R3W4R1

UNITY F5IR3W4 VW4 F5GR3W4 SEQ #

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Scenario Development Table 5-1 Success Criteria for Mitigating Features Feature Time Window Success Criteria Reflux Cooling Short Term Long Term

< 75 hours8.680556e-4 days 0.0208 hours 1.240079e-4 weeks 2.85375e-5 months 3 SGs AFW to 3 SGs

>= 75 hours8.680556e-4 days 0.0208 hours 1.240079e-4 weeks 2.85375e-5 months 2 SGs AFW to 2 SGs and < 475 hours0.0055 days 0.132 hours 7.853836e-4 weeks 1.807375e-4 months

>= 475 hours0.0055 days 0.132 hours 7.853836e-4 weeks 1.807375e-4 months 1 SG AFW to 1 SG Feed and Spill < 107 hours0.00124 days 0.0297 hours 1.76918e-4 weeks 4.07135e-5 months lLHSI * (SV removed+ 2PORV)

> 107 hours0.00124 days 0.0297 hours 1.76918e-4 weeks 4.07135e-5 months lLHSI *(SV removed + 1 PORV)

< 129 hours0.00149 days 0.0358 hours 2.132936e-4 weeks 4.90845e-5 months 2HHSI*(SV removed + 2 PORV)

> 129 and < 138 lHHSI*(SV removed+ 2 PORV) hours

Gravity Feed

>= 138 hours0.0016 days 0.0383 hours 2.281746e-4 weeks 5.2509e-5 months

< 70 hours8.101852e-4 days 0.0194 hours 1.157407e-4 weeks 2.6635e-5 months

> 70 hours8.101852e-4 days 0.0194 hours 1.157407e-4 weeks 2.6635e-5 months and

< 150 hours0.00174 days 0.0417 hours 2.480159e-4 weeks 5.7075e-5 months lHHSI * (SV removed+ 1 PORV) at least 1 SV removed , less than 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months of subcooling at least 1 SV removed, 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months of subcooling

> 150 hours0.00174 days 0.0417 hours 2.480159e-4 weeks 5.7075e-5 months and at least 1 SV removed, 3 hours3.472222e-5 days 8.333333e-4 hours 4.960317e-6 weeks 1.1415e-6 months of subcooling less than 768 hours0.00889 days 0.213 hours 0.00127 weeks 2.92224e-4 months

>= 768 hours0.00889 days 0.213 hours 0.00127 weeks 2.92224e-4 months at least 1 SV removed, sufficient for 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months Recirculation <=3days needed

> 3 days and not needed if RWSTs are cross tied, otherwise needed

<=10 days

> 10 days not needed Spray <= 3 days needed to prevent recirculation failure Recirculation

> 3 days and not needed if RWSTs are cross tied, otherwise needed to

<=10 days prevent recirculation failure

> 10 days not needed

NUREG/CR-6144 5-89

Table 5-2 Definition and Characterization of Time Windows Window 1 Window2 Window3 Window4 Definition <= 75 hours8.680556e-4 days 0.0208 hours 1.240079e-4 weeks 2.85375e-5 months > 75 hours8.680556e-4 days 0.0208 hours 1.240079e-4 weeks 2.85375e-5 months and > 240 hours0.00278 days 0.0667 hours 3.968254e-4 weeks 9.132e-5 months and > 32days

<= 240 hours0.00278 days 0.0667 hours 3.968254e-4 weeks 9.132e-5 months <= 32 days Representative 13.23 MW 10 MW(5 days) 7 MW(12 days) 5 MW(32 days)

Decay Heat (2 days)"

Success Criteria Reflux Cooling 3 SGs 2SG 2SG 1 SG Feed and Bleed LHSI lLHSl*(SV lLHSI*(SV lLHSI *(SV lLHSI *(SV removed+ 2 removed+ 2 removed+ removed+

PORV) PORV) lPORV) lPORV) lHHSI*(SV lHHSJ*(SV lHHSl*(SV lHHSl*(SV HHSI removed+ 1 removed+ 1 removed+ 1 removed+ 1 PORV) PORV) PORV) PORV)

Gravity Feed 1 SV removed

1 SV removed

1 SV removed

1 SV removed

LHSI flow path LHSI flow path LHSI flow path LHSI flow path provides provides 6.5 provides provides sufficient 4.3 hours3.472222e-5 days 8.333333e-4 hours 4.960317e-6 weeks 1.1415e-6 months for hours for 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months for cooling for 24 operator actions operator actions operator actions hours (with more (with less than 2 (with 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months of (with 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months of than 3 hours3.472222e-5 days 8.333333e-4 hours 4.960317e-6 weeks 1.1415e-6 months of hours of subcooling) subcooling) subcooling) subcooling)

Recirculation needed(HPR + 1 RWST,needed not needed not needed LPF&Steam

+ LPF&Spill) 2 RWST, not needed Recirculation needed 1 RWST,needed not needed not needed Spray 2 RWST,not needed Probability that IE Occurs in the Window (RHR2A based on time to mid-loop)

D6 1.17E-01 0.536 0.375 7.20E-02 (0.31) (0.454) (0.21) (2.6E-02)

R6 1.7E-02 0.543 0.41 3.4E-02 (5.82E-02) (0.7) (0.24) (1.48E-03)

RlO 0.0 0.0 0.016 9.84E-01 (2.2E-02) (0.98) 5-90 NUREG/CR-6144

Scenario Development Table 5-2 (Continued)

Definition and Characterization or Time Windows Window 1 Window2 Window3 Window4 Decay Heat 13.23 10 MW(5 days) 7 MW(l2 days) 5 MW(32 days)

MW(2days)

Time to Boiling 15 min 20 min 27 min 37 min Time to Tygon 23 min 31 min 43 min 59 min Tube Rupture(40 psia)

Time to PRT 51 min 63 min 78min 96 min Rupture(lOO psig)

TlDle to 165 41 min with 2 63 min with 2 227 min with 2 352 min with 2 psia PORV PORV PORV PORV 43 min with 1 60 min with 1 89 min with 1 147 min with 1 PORV PORV PORV PORV Time to 615 145 miil with 1 . - -

psig PORV

-with two TlDle to RWST 10 hrs 13.5 hrs 18.7 hrs 38.6 hrs Depletion TimetoAFW 743 min 669 min 925 min 628 min Initiation(with 25% SG inventory remaining)

Time to Core 120 min 157 min 209 min 273 min Uncovery Time to Core 219 min 297 min 411 min 557 min Damage

NUREG/CR-6144 5-91

Table !-3 Definition of Dynamic Human Actions Flood Initiating Events Event Title of Action Action Remarks Designator DFlWl Diagnose the loss of RHR and two-unit D-B2Wl-XHE The large flood in the Turbine building overflows DF1W2 station blackout (with instrumentation D-B2W2-XHE the flood dikes at the ESGRs and Auxiliary DF1W3 available) due to damage to all 4 kV D-B2W3-XHE Building Pipe Tunnel and results in flooding of DF1W4 and 480 V buses by large Turbine D-B2W4-XHE majority of the electrical equipment in ESGR for Building flood at mid-loop in both units. All 4 kV and 480 V buses are lost (i.e.,

Wl/W2/W3/W4 refueling outages. two-unit station blackout). SG PORVs and instrumentation are still available.

DF2Wl Same as Fl with DC Power/Panels D-B2Wl-XHE Same as Fl with No DC Power. Instrumentation DF2W2 Shorted D-B2W2-XHE may be erratic.

DF2W3 D-B2W3-XHE DF2W4 D-B2W4-XHE DF3Wl Diagnose the loss of RHR due to D-R3Wl-XHE All 4 CCW pumps, all 3 charging pumps, and DF3W2 damage to CCW pumps, charging D-R3W2-XHE HHSI MOVs (e.g., RWST suction valve 1115D, DF3W3 pumps, and HHSI MOVs by large D-R3W3-XHE VCT suction isolation valve 1115E, cold leg DF3W4 Auxiliary Building flood at mid-loop in D-R3W4-XHE injection valves 1842 and 1867C/D, hot leg Wl/W2/W3/W4 of refueling outages. injection valves 1869A/B, and LHSI to HHSI cross-connect valves 1863A/B) are disabled.

DF4Wl Diagnose the loss of RHR due to D-R3Wl-XHE All 4 CCW pumps, all 3 charging pumps, HHSI DF4W2 damage to CCW pumps, charging D-R3W2-XHE MOVs (e.g., RWST suction valve 1115D, VCT DF4W3 pumps, HHSI MOVs, and RWST water D-R3W3-XHE suction isolation valve 1115E, cold leg injection DF4W4 supply by large Auxiliary Building flood D-R3W3-XHE valves 1842 and 1867C/D, hot leg injection valves at mid-loop in 1869A/B, and LHSI to HHSI cross-connect valves Wl/W2/W3/W4 of refueling outages. 1863A/B), and RWST water supply are disabled.

Table 5-3 ued)

Defmition or Dynamic Human Actions Flood Initiating Events Event Title or Action Action Remarks Designator DFlWl Diagnose the loss of RHR and two-unit D-B2W1-XHE The large flood in the Turbine building overflows DF1W2 station blackout (with instrumentation D-B2W2-XHE the flood dikes at the ESGRs and Auxiliary DF1W3 available) due to damage to all 4 kV D-B2W3-XHE Building Pipe Tunnel and results in flooding of DF1W4 and 480 V buses by large Turbine D-B2W4-XHE majority of the electrical equipment in ESGR for Building flood at mid-loop in both units. All 4 kV and 480 V buses are lost (i.e.,

W1/W2/W3/W4 refueling outages. two-unit station blackout). SG PORVs and instrumentation are still available.

DF5Wl Diagnose the loss of RHR due to D-R3Wl-XHE All 4 CCW pumps, all 3 charging pumps, HHSI DF5W2 damage to CCW pumps, charging D-R3W2-XHE MOVs (e.g., RWST suction valve 1115D, VCT DF5W3 pumps, HHSI MOVs, LHSI pumps, D-R3W3-XHE suction isolation valve 1115E, cold leg injection DF5W4 and RWST water supply by large D-R3W4-XHE valves 1842 and 1867C/D, hot leg injection valves safeguard area flood overflowing to the 1869NB, and LHSI to HHSI cross-connect valves Auxiliary Building basement at mid- 1863NB), LHSI pumps, and RWST water supply loop in Wl/W2/W3/W4 of refueling are disabled outages.

DF6Wl Diagnose the loss of RHR due to D-R4Wl-XHE One RHR train is lost due lo damage to the DF6W2 damage to the operating RHR pump D-R4W2-XHE operating RHR pump by spray inside the DF6W3 by spray inside the containment at mid- D-R4W3-XHE containment.

DF6W4 loop in POS 6 of refueling outages. D-R4W4-XHE DF7Wl Diagnose the loss of RHR due to D-B2Wl-XHE The flood in MER No. #3 overflow:

DF7W2 damage to all 4 kV and 480 V buses by D-B2W2-XHE The dikes and causes damage in the ESGR DF7W3 a flood from MER No. #3. D-B2W3-XHE Electrical Equipment cost. SG PORvs and DF7W4 D-B2W4-XHE instrumentation available.

Table 5-3 (Continued)

Definition or Dynamic Human Actions flood Initiating Events Event 11tle or Action Action Remarks Designator DFlWl Diagnose the loss of RHR and two-unit D-B2Wl-XHE The large flood in the Turbine building overflows DF1W2 station blackout (with instrumentation D-B2W2-XHE the flood dikes at the ESGRs and Auxiliary DF1W3 available) due to damage to all 4 kV D-B2W3-XHE Building Pipe Tunnel and results in flooding of DF1W4 and 480 V buses by large Turbine D-B2W4-XHE majority of the electrical equipment in ESGR for Building flood at mid-loop in both units. All 4 kV and 480 V buses are lost (i.e.,

Wl/W2/W3/W4 refueling outages. two-unit station blackout). SG PORVs and instrumentation are still available.

GFlWl Establish gravity feed following loss of A-B2Wl-XHE-G-4 Loss of all 4 kV and 480 V buses.

GF1W2 RHR due to flood in ESGR loss of all A-B2W2-XHE-G-4 GF1W3 4 KV & 48V buses. A-B2W3-XHE-G-4 GF1W4 A-B2W4-XHE-G-4 GF2Wl Same as GFlW x event with erratic Loss of all 4 kV and 480 V buses, DC buses.

GF2W2 instrumentation GF2W3 GF2W4

Scenario Development Table 5-3 nued)

Definition of Dynamic Human Actions Flood lnitiadng Events Event 11tle of Action Action Remarks Designator DF1Wl Diagnose the loss of RHR and two-unit D-B2W1-XHE The large flood in the Turbine building overflows DF1W2 station blackout (with instrumentation D-B2W2-XHE the flood dikes at the ESGRs and Auxiliary DF1W3 available) due to damage to all 4 kV D-B2W3-XHE Building Pipe Tunnel and results in flooding of DF1W4 and 480 V buses by large Turbine D-B2W4-XHE majority of the electrical equipment in ESGR for Building flood at mid-loop in both units. All 4 kV and 480 V buses are lost (i.e.,

Wl/W2/W3/W4 refueling outages. two-unit station blackout). SG PORVs and instrumentation are still available.

SF3Wl Establish SG bleed and feed following A-R3W1-XHE-S1-9 All 4 CCW pumps, all 3 charging pumps and SF3W2 loss of RHR due to damage to CCW A-R3W2-XHE-S1-9 HHSI MOVs (e.g., RWST suction valve 1115D, SF3W3 pumps, charging pumps, and HHSI A-R3W3-XHE-S1-8 VCT suction isolation valve 1115E, cold leg SF3W4 MOVs by large Auxiliary Building A-R3W4-XHE-S1-8 injection valves 1842 and 1867C/D, hot leg flood at mid-loop. injection valves 1869NB, and LHSI to HHSI A-R3W1-XHE-S2-9 cross-connect valves 1863NB) are disabled.

A-R3W2-XHE-S1-9 A-R3W3-XHE-S1-8 A-R3W4-XHE-S1-8 A-R3Wl-XHE-SF-9 A-R3W2-XHE-SF-9 A-R3W3-XHE-SF-8 A-R3W4-XHE-SF-8

Table !-3 (Continued)

Definition of Dynamic Buman Actions Ji1ood Initiating Events Event Title of Action Action Remarks Designator DFlWl Diagnose the loss of RHR and two-unit D-B2Wl-XHE The large flood in the Turbine building overflows DF1W2 station blackout (with instrumentation D-D2W2~XHE the flood dikes at the ESGRs and Auxiliary DF1W3 available) due to damage to all 4 kV D-82W3-XHE Building Pipe Tunnel and results in flooding of DF1W4 and 480 V buses by large Turbine D-B2W4-XHE majority of the electrical equipment in ESGR for Building flood at mid-loop in both units. All 4 kV and 480 V buses are lost (i.e.,

Wl/W2/W3/W4 refueling outages. two-unit station blackout). SG PORVs and instrumentation are still available.

FF3Wl Align primary feed and bleed following A-R3Wl-XHE-FH-4 FF3W2 loss of RHR due to damage to CCW A-R3W2-XHE-FH-4 FF3W3 pumps, charging pumps, and HHSI A-R3W3-XHE-FH-3 FF3W4 MOVs by large Auxiliary Building A-R3W4-XHE-FH-3 flood at mid-loop in POS 6 of refueling outages. A-R3Wl-XHE-FH-9 A-R3W2-XHE-FH-9 A-R3W3-XHE-FH-7 A-R3W4-XHE-FH-7 A-R3Wl-XHE-FL-4 A-R3W2-XHE-FL-4 A-R3W3-XHE-FL-3 A-R3W4-XHE-FL-3 A-R3Wl-XHE-FL-9 A-R3W2-XHE-FL-9 A-IUW3-XHE-FL-7 A-R3W4-XHE-FL-7

Table 5- nued)

Definition or Dynamic Human Actions Flood Initiating Events Event Title or Action Action Remarks Designator DFlWl Diagnose the loss of RHR and two-unit D-B2Wl-XHE The large flood in the Turbine building overflows DF1W2 station blackout (with instrumentation D-B2W2-XHE the flood dikes at the ESGRs and Auxiliary DF1W3 available) due to damage to all 4 kV D-B2W3-XHE Building Pipe Tunnel and results in flooding of DF1W4 and 480 V buses by large Turbine D-B2W4-XHE majority of the electrical equipment in ESGR for Building flood at mid-loop in both units. All 4 kV and 480 V buses are lost (i.e.,

Wl/W2/W3/W4 refueling outages. two-unit station blackout). SG PORVs and instrumentation are still available.

GF3Wl Establish gravity feed from RWST after A-R3Wl-XHE-G-5 All 4 CCW pumps and MOVs (1115D, 1115E, GF3W2 failure to establish primary feed and A-R3W3-XHE-G-5 1842, 1867 C/D, 1869 A/8, GF3W3 bleed following loss of RHR due to A-R3W3-XHE-G-4 1863 A/8) disabled GF3W4 damage to CCW pumps, charging A-R3W4-XHE-G-4 pumps, and HHSI MOVs by large Auxiliary Building flood at mid-loop in refueling outages.

SF4Wl Establish SG bleed and feed following A-R4W1-XHE-S1-8 All 4 CCW pumps, all 3 charging pumps, HHSI SF4W2 loss of RHR due to damage to CCW A-R3W2-XHE-S1-8 MOVs (e.g., RWST suction valve 1115D, VCT SF4W3 pumps, charging pumps, HHSI MOVs, A-R3W3-XHE-S1-7 suction isolation valve 1115E, cold leg injection SF4W5 and RWST water supply by large A-R3W4-XHE-S1-7 valves 1842 and 1867C/D, hot leg injection valves Auxiliary Building flood at mid-loop in I 1869A/B, and LHSI to HHSI cross-connect valves POS 6 of refueling outages. A-R4Wl-XHE-S2-8 1863A/B), and RWST water supply are disabled.

A-R4W2-XHE-S2-8 A-R4W3-XHE-S2-;7 A-R4W4-XHE-S2i7 I

A-R4Wl-XHE-sFis A-R4W2-XHE-SFf8 A-R4W3-XHE-SFi7 A-R4W4-XHE-SFt7 I

l j

Table 5-3 (Continued)

Definition of Dynamic Human Actions Flood Initiating Events Event Title of Action Action Remarks Designator DFlWl Diagnose the loss of RHR and two-unit D-B2Wl-XHE The large flood in the Turbine building overflows DF1W2 station blackout (with instrumentation D-B2W2-XHE the flood dikes at the ESGRs and Auxiliary DF1W3 available) due to damage to all 4 kV D-B2W3-XHE Building Pipe Tunnel and results in flooding of DF1W4 and 480 V buses by large Turbine D-B2W4-XHE majority of the electrical equipment in ESGR for Building flood at mid-loop in both units. All 4 kV and 480 V buses are lost (i.e.,

Wl/W2/W3/W4 refueling outages. two-unit station blackout). SG PORVs and instrumentation are still available.

CF3Wl Establish recirculation cooling. A-R3Wl-XHE-C-3 CF3W2 A-R3W2-XHE-C-3 CF3W3 A-R3Wl-XHE-C-8 CF3W4 A-R3W2-XHE-C-8 PF3Wt Establish recirculation spray. A-R3Wl-XHE-P-3 PF3W2 A-R3W2-XHE-P-3 A-R3W2-XHE-X SF5Wl Establish SG bleed and feed following All 4 CCW pumps, all 3 charging pumps, HHSI SF5W2 loss of RHR due to damage to CCW MOVs (e.g., RWST suction valve ll15D, VCT SF5W3 pumps, charging pumps, HHSI MOVs, suction isolation valve 1115E, cold leg injection SF5W4 LHSI pumps, and RWST water supply valves 1842 and 1867C/D, hot leg injection valves by large Safeguard Area flood 1869A/B, and LHSI to HHSI cross-connect valves overflowing to the Auxiliary Building at 1863A/B), both LHSI pumps, and RWST water mid-loop in refueling outages. supply are disabled.

RF6Wl Restore RHR cooling following a A-R4Wl-XHE-R-4 Train A RHR is lost due to spray damage to the RF6W2 recoverable loss of RHR due to A-R4W2-XHE-R-4 operating RHR pump.

RF6W3 damage to the operating RHR pump A-R4W3-XHE-R-4 RF6W4 by spray inside the containment at mid- A-R4W4-XHE-R-4 loop in refueling outages.

Definition of Dynamic Human Actions Flood Initiating Events Event Title of Action Action Remarks Designator DFlWl Diagnose the loss of RHR and two-unit D-B2Wl-XHE The large flood in the Turbine building overflows DF1W2 station blackout (with instrumentation D-B2W2-XHE the flood dikes at the ESGRs and Auxiliary DF1W3 available) due to damage to all 4 kV D-B2W3-XHE Building Pipe Tunnel and results in flooding of DF1W4 and 480 V buses by large Turbine D-B2W4-XHE majority of the electrical equipment in ESGR for Building flood at mid-loop in both units. All 4 kV and 480 V buses are lost (i.e.,

Wl/W2/W3/W4 refueling outages. two-unit station blackout). SG PORVs and instrumentation are still available.

SF6Wl Establish SG bleed and feed after A-R4W1-XHE-S1-9 Same equipment failures as for RF6Wx.

SF6W2 failure to restore RHR following a A-R4W2-XHE-Sl-9 SF6W3 recoverable loss of RHR due to A-R4W3-XHE-Sl-8 SF6W4 damage to the operating RHR pump A-R4W4-XHE-S1-8 by spray inside the containment at mid-loop in refueling outages. A-R4W1-XHE-S2-9 A-R4W2-XHE-S2-9 A-R4Wl-XHE-S2-8 A-R4Wl-XHE-S2-8 A-R4Wl-XHE-SF-9 A-R4W2-XHE-SF-9 A-R4W3-XHE-SF-8 A-R4W4-XHE-SF-8

Table 5.3 (Continued)

Definition ol Dynamic Buman Actions F1ood Initiating Events Event 11tle ol Action Action Remarks Designator DFlWl Diagnose the loss of RHR and two-unit D-B2Wl-XHE The large flood in the Turbine building overflows DF1W2 station blackout (with instrumentation D-B2W2-XHE the flood dikes at the ESGRs and Auxiliary DF1W3 available) due to damage to all 4 kV D-B2W3-XHE Building Pipe Tunnel and results in flooding of DF1W4 and 480 V buses by large Turbine D-B2W4-XHE majority of the electrical equipment in ESGR for Building flood at mid-loop in both units. All 4 kV and 480 V buses are lost (i.e.,

Wl/W2/W3/W4 refueling outages. two-unit station blackout). SG PORVs and instrumentation are still available.

FF6Wl Align primary feed and bleed after A-R4Wl-XHE-FH-5 HPI feed and bleed.

FF6W2 failure to restore RHR following a A-R4W2-XHE-FH-5 FF6W3 recoverable loss of RHR due to A-R4W3-XHE-FH-4 Ul FF6W4 damage to the operating RHR pump A-R4W4-XHE-FH-4 I

0 0

by spray inside the containment at mid-loop in refueling outages. A-R4Wl-XHE-FH-10 A-R4W2-XHE-FH-10 A-R4W2-XHE-FH-8 A-R4W2-XHE-FH-8 A-R4Wl-XHE-FL-5 LPI feed and bleed.

A-R4W2-XHE-FL-5 A-R4W3-XHE-FL-4 A-R4W4-XHE-FL-4 A-R4Wl-XHE-FL-10 A-R4W2-XHE-FL-10 A-R4W3-XHE-FL-8 A-R4W4-XHE-FL-8

Table 5-3 ued)

Definition of Dynamic Human Actions Flood Initiating Events Event Tide of Action Action Remarks Designator*

DFlWl Diagnose the loss of RHR and two-unit D-B2Wl-XHE The large flood in the Turbine building overflows DF1W2 station blackout (with instrumentation D-B2W2-XHE the flood dikes at the ESGRs and Auxiliary DF1W3 available) due to damage to all 4 kV D-B2W3-XHE Building Pipe Tunnel and results in flooding of DF1W4 and 480 V buses by large Turbine D-B2W4-XHE majority of the electrical equipment in ESGR for Building flood at mid-loop in both units. All 4 kV and 480 V buses are lost (i.e.,

Wl/W2/W3/W4 refueling outages. two-unit station blackout). SG PORVs and instrumentation are still available.

GF6Wl Establish gravity feed from RWST after A-R4Wl-XHE-G-6 Train A of RHR is lost due to spray damage to GR6W2 failure to restore RHR and establish A-R4W2-XHE-G-6 the operating pump.

GR6W3 primary feed and bleed following a A-R4W3-XHE-G-5 GR6W4 recoverable loss of RHR due to A-R4W3-XHE-G-5 VI I

0 damage to the operating RHR pump by spray inside the containment at mid-loop in POS 6 of refueling outages.

CF6Wl Establish recirculation function. A-R4Wl-XHE-C-4 CF6W2 A-R4W2-XHE-C-4 A-R4Wl-XHE-C-9 A-R4W2-XHE-C-9 PF6Wl Establish recirculation sprays. A-R4Wl-XHE-P-4 PF6W2 A-R4W2-XHE-P-4 A-R4W2-XHE-X DF7Wl Same as Fl events. D-B2Wl-XHE DF7W2 D-B2W2-XHE DF7W3 D-B2W3-XHE DF7W4 D-B2W4-XHE.

Table !-3 (Continued)

Definition of Dynamic Human Adions Flood Initiating Events Event Title of Adion Adion Remarks Designator DF1W1 Diagnose the loss of RHR and two-unit D-B2W1-XHE The large flood in the Turbine building overflows DF1W2 station blackout (with instrumentation D-B2W2-XHE the flood dikes at the ESGRs and Auxiliary DF1W3 available) due to damage to all 4 kV D-B2W3-XHE Building Pipe Tunnel and results in flooding of DF1W4 and 480 V buses by large Turbine D-B2W4-XHE majority of the electrical equipment in ESGR for Building flood at mid-loop in both units. All 4 kV and 480 V buses are lost (i.e.,

Wl/W2/W3/W4 refueling outages. two-unit station blackout). SG PORVs and instrumentation are still available.

GF7Wl Same as Fl Events. A-B2Wl-XHE-6-4 GF7W2 A-B2W2-XHE-G-4 GF7W3 A-B2W3-XHE-G-4 GF7W4 A-B2W4-XHE-G-4 VI I

e N

Table 5-4 Evaluation of Dynamic Actions Flood Initiating Events Preceding Plant Time Procedures Complexity Trainin&'fup Stress Action Interfaces Adequacy Actions DF1W1 Weight 0 0.24 0.18 0.12 0.12 0.24 0.12 Score 1 5 10 2 5 5 10 P(Fail)= 1.68E-02 DF1W2/W3

...s V,

I Weight 0 0.24 0.18 0.12 0.12 0.24 0.12 Score 1 5 10 2 5 5 9 P(Fail)= 1.28E-02 DF1W4 Weight 0 0.24 0.18 0.12 0.12 0.24 0.12 Score 1 5 5 2 5 5 8 P(Fail)= 1.24E-03 DF3Wl Weight 0 0.24 0.18 0.12 0.12 0.24 0.12

Table S-4 Evaluation or Dynamic Buman Adions Flood Initiating Events (continued)

Preceding Plant Time Procedures Complexity Training/Exp Stress Action Interfaces Adequacy Score 1 4 9 3 4 3 9 P(Fail)= 1.63E-03 DF3W2/W3 Weight 0 0.24 0.18 0.12 0.12 0.24 0.12 Score 1 4 8 3 4 3 7 P(Fail)= 6.24E-04 DF3W4 V,

I

~ Weight 0 0.24 0.18 0.12 0.12 0.24 0.12 Score 1 4 5 3 4 3 6 P(Fail)= 1.38E-04 DF5Wl Weight 0 0.24 0.18 0.12 0.12 0.24 0.12 Score 1 5 10 3 5 4 10 P(Fail)= 1.28E-02 DF5W2/W3

Table 5-4 Evaluation of Dynamic Human Flood Initiating Events (continued)

Preceding Plant Time Procedures Complexity Training/Exp Stress Action Interfaces Adequacy Weight 0 0.24 0.18 0.12 0.12 0.24 0.12 Score 1 5 9 3 s 4 9 P(Fail)= 6.44E-03 DF5W4 Weight 0 0.24 0.18 0.12 0.12 0.24 0.12 Score 1 s 5 3 s 4 8 P(Fail)= 9.42E-04

...~

V, I

DF6Wl Weight 0 0.24 0.18 0.12 0.12 0.24 0.12 Score 1 2 7 2 2 2 6 P(Fail)= 2.65E-05 DF6W2/W3 .

Weight 0 0.24 0.18 0.12 0.12 0.24 0.12 Score 1 2 5 2 2 2 5 P(Fail)= 8.84E-06

Table 5-4 Evaluation of Dynamic Buman Actions Flood Initiating Events (continued)

Preceding Plant Time Procedures Complexity Training/Exp Stress Action Interfaces Adequacy DF6W4 Weight 0 0.24 0.18 0.12 0.12 0.24 0.12 Score 1 2 2 2 2 2 4 P(Fail)= 1.95E-06 GFlWl GF3Wl Weight 0.19 0.1 0.14 0.14 0.1 0.19 0.14 Score 9 6 9 4 6 5 10

-°'

VI I

0 P(Fail)= 1.59E-01 GF1W2/W3 GF3W2/W3*

Weight 0.19 0.1 0.14 0.14 0.1 0.19 0.14 Score 9 6 7 4 6 5 10 P(Fail)= 8.28E-02 GF1W4 GF3W4 Weight 0.19 0.1 0.14 0.14 0.1 0.19 0.14 Score 9 6 4 4 6 5 10

Table 5-4 Evaluation of Dynamic Human Preceding Action Plant Interfaces Time Adequacy s Flood Initiating Events (continued)

Procedures Complexity Training/Exp Stress P(Fail)= 3.llE-02 GF2Wl Weight 0.19 0.1 0.14 0.14 0.1 0.19 0.14 Score 10 7 9 5 7 6 10 P(Fail)= 8.55E-Ol GF2W2/W3 Weight 0.19 0.1 0.14 0.14 0.1 0.19 0.14

'f' 0

-...I Score 9 7 8 4 7 5 10 P(Fail)= 1.83E-01 GF2W4 Weight 0.19 0.1 0.14 0.14 0.1 0.19 0.14 Score 8 6 6 4 6 5 10 P(Fail)= 3.83E-02 GF6Wl Weight 0.19 0.09 0.19 0.14 0.09 0.19 0.09

Table S-4 Evaluation or Dynamic Human Actions Flood Initiating Events (continued)

Preceding Plant Time Procedures Complexity Training/Exp Stress Action Interfaces Adequacy Score 7 5 7 4 6 2 9 P(Fail)= 4.0SE-03 GF6W2/W3 Weight 0.2 0.1 0.15 0.15 0.1 0.2 0.1 Score 7 5 5 4 6 2 7 P(Fail)= 1.lOE-03 I

GF6W4 0

00 Weight 0.21 0.11 0.11 0.16 0.11 0.21 0.11

Score 7 5 3 4 6 2 5 P(Fail)= 4.13E-04 SFlWlSl Weight 0.17 0.09 0.17 0.09 0.17 0.17 0.13 Score 9 8 9 4 5 7 10 P(Fail)= 4.83E-01 SF1W2/W3S 1

Table !-4 Evaluation of Dynamic Duma s Flood Initiating Events (continued)

Preceding Plant Time Procedures Complexity Training/Exp Stress Action Interfaces Adequacy Weight 0.17 0.09 0.17 0.09 0.17 0.17 0.13 Score 9 8 7 4 5 7 10 P(Fail)= 2.17E-01 SF1W4Sl Weight 0.17 0.09 0.17 0.09 0.17 0.17 0.13 Score 9 8 5 4 5 7 9 P(Fail)= 7.16E-02

-'° VI 0

I SF1W1S2 Weight 0.17 0.09 0.17 0.09 0.17 0.17 0.13 Score 9 8 9 4 5 7 10 P(Fail)= 4.83E-01 SF1W2{W3S 2

Weight 0.17 0.09 0.17 *0.09 0.17 0.17 0.13 Score 9 8 7 4 5 7 10 P(Fail)= 2.17E-01

. Table 5-4 Evaluation of Dynamic Human Actions Flood Initiating Events (continued)

Preceding Plant Time Procedures Complexity Training/Exp Stress Action Interfaces Adequacy SF1W4S2 Weight 0.17 0.09 0.17 0.09 0.17 0.17 0.13 Score 9 8 5 4 5 7 9 P(Fail)= 7.16E-02 SFlWlSF Weight 0.17 0.09 0.17 0.09 0.17 0.17 0.13 Score 9 8 9 4 5 7 10 V,

0 I

P(Fail)= 4.83E-01 SF1W2/W3S F

Weight 0.17 0.09 0.17 0.09 0.17 0.17 0.13 Score 9 8 7 4 5 7 10 P(Fail)= 2.17E-01 SF1W4SF Weight 0.17 0.09 0.17 0.09 0.17 0.17 0.13 Score 9 8 5 4 5 7 9 P(Fail)= 7.16E-02

Table !-4 Evaluation of Dynamic Duma Preceding Action Plant Interfaces Time Adequacy s Flood Initiating Events (continued)

Procedures Complexity Training/Exp Stress SF3W1S2 Weight 0.18 0.09 0.18 0.09 0.14 0.18 0.14 Score 10 8 9 3 3 7 10 P(Fail)= 4.lSE-01 SF3W2/W3S 2

Weight 0.18 0.09 0.18 0.09 0.14 0.18 0.14 UI I

Score 8 8 8 3 3 7 10 P(Fail)= 1.18E-01 SF3W4S2 Weight 0.18 0.09 0.18 0.09 0.14 0.18 0.14 Score 8 8 7 3 3 7 10 P(Fail)= 7.72E-02 SF3W1Sl Weight 0.18 0.09 0.18 0.09 0.14 0.18 0.14 Score 8 8 8 3 3 7 10

Table 5-4 Evaluation of Dynamic Human Actions Flood Initiating Events (continued)

Preceding Plant Time Procedures Complexity Training/Exp Stress Action Interfaces Adequacy P(Fail)= 1.18E-01 SF3W2/W3S 1

Weight 0.18 0.09 0.18 0.09 0.14 0.18 0.14 Score 8 8 6 3 3 7 10 P(Fail)= 5.07E-02 SF3W4Sl Weight 0.18 0.09 0.18 0.09 0.14 0.18 0.14 Score 8 8 4 3 3 7 9 P(Fail)= 1.58E-02 SF3W1SF Weight 0.18 0.09 0.18 0.09 0.14 0.18 0.14 Score 8 8 5 3 3 7 7 P(Fail)= 1.25E-02 SF3W2/W3S F

Table S-4 Evaluation of Dynamic Huma s Flood Initiating Events (continued)

Preceding Plant Time Procedures Complexity Training/Exp Stress Action Interfaces Adequacy Weight 0.18 0.09 0.18 0.09 0.14 0.18 0.14 Score 8 8 4 3 3 7 7 P(Fail)= 8.21E-03 SF3W4SF Weight 0.18 0.09 0.18 0.09 0.14 0.18 0.14 Score 8 8 3 3 3 7 7 P(Fail)= 5.40E-03 SF5W1S2 Weight 0.18 0.09 0.18 0.09 0.14 0.18 0.14 Score 10 8 10 3 3 7 10 P(Fail)= 6.31E-01 SF5W2/W3S 2

Weight 0.18 0.09 0.18 0.09 0.14 0.18 0.14 Score 8* 8 10 3 3 7 10 P(Fail)= 2.72E-01

Table 5-4 Evaluation of Dynamic Human Actions flood Initiating Events (continued)

Preceding Plant Time Procedures Complexity Training/Exp Stress Action Interfaces Adequacy SF5W4S2 Weight 0.18 0.09 0.18 0.09 0.14 0.18 0.14 Score 8 8 8 3 3 7 10 P(Fail)= 1.lSE-01 SF5W1S1 Weight 0.18 0.09 0.18 0.09 0.14 0.18 0.14 Score 8 8 9 3 4 7 9 y,

.i:,.

P(Fail)= 1.79E-01 SF5W2/W3S 1

Weight 0.18 0.09 0.18 0.09 0.14 0.18 0.14 Score 8 8 7 3 4 7 9 P(Fail)= 7.72E-02 SF5W4S1 Weight 0.18 0.09 0.18 0.09 0.14 0.18 0.14 Score 8 8 5 3 4 7 9 P(Fail)= 3.33E-02

Table S-4 Evaluation of Dynamic Human ns Flood Initiating Events (continued)

Preceding Plant Time Procedures Complexity Training/Exp Stress Action Interfaces Adequacy SF5W1SF Weight 0.18 0.09 0.18 0.09 0.14 0.18 0.14 Score 7 8 6 3 4 7 7 P(Fail)= 1.73E-02 SF5W2JW3S F

Weight 0.18 0.09 0.18 0.09 0.14 0.18 0.14 VI I

VI Score 7 8 5 3 4 7 7 P(Fail)= 1.14E-02 SF5W4SF Weight 0.18 . 0.09 0.18 0.09 0.14 0.18 0.14 Score 7 8 4 3 4 7 7 P(Fail)= 7.48E-03 .

SF1W1S1 Weight 0.17 0.09 0.17 0.09 0.17 0.17 0.13 Score 9 8 9 4 5 7 10

Table !-4 Evaluation of Dynamic Buman Actions Flood Initiating Events (continued)

Preceding Plant Time Procedures Complexity Training/Exp Stress Action Interfaces Adequacy P(Fail)= 4.83E-01 SF1W2/W3S 1

Weight 0.17 0.09 0.17 0.09 0.17 0.17 0.13 Score 9 8 7 4 5 7 10 P(Fail)= 2.17E-01 SF1W4S1

-°'

VI I

Weight 0.17 0.09 0.17 0.09 0.17 0.17 0.13 Score 9 8 5 4 5 7 10 P(Fail)= 9.73E-02 SF1W1S2 Weight 0.17 0.09 0.17 0.09 0.17 0.17 0.13 Score 9 8 10 4 5 7 10 P(Fail)= 7.22E-Ol SF1W2/W3S 2

Table 5-4 Evaluation o( Dynamic Human s Flood Initiating Events (continued)

Preceding Plant Time Procedures Complexity Training/Exp Stress Action Interfaces Adequacy Weight 0.17 0.09 0.17 0.09 0.17 0.17 0.13 Score 9 8 8 4 s 7 10 P(Fail)= 3.24E-01 SF1W4S2 Weight 0.17 0.09 0.17 0.09 0.17 0.17 0.13 Score 9 8 6 4 5 7 10 P(Fail)= 1.45E-01 VI I

-.l SFlWlSF Weight 0.17 0.09 0.17 0.09 0.17 0.17 0.13 Score 8 8 8 4 6 7 7 P(Fail)= 1.29E-01 SF1W2/W3S F

Weight 0.17 0.09 0.17 0.09 0.17 0.17 0.13 Score 8 8 6 4 6 7 7 P(Fail)= 5.79E-02

Table !-4 Evaluation of Dynamic Human Actions Flood Initiating Events (continued)

Preceding Plant Time Procedures Complexity Training/Exp Stress Action Interfaces Adequacy SF1W4SF Weight 0.17 0.09 0.17 0.09 0.17 0.17 0.13 Score 8 8 4 4 6 7 7 P(Fail)= 2.00E-02 SF6W1Sl Weight 0 0.12 0.24 0.12 0.18 0.24 0.12 Score 6 7 7 3 3 6 9

,.,. P(Fail)= 8.48E-03 I

00 SF6W2/W3S 1

Weight 0 0.12 0.24 0.12 0.18 0.24 0.12 Score 6 7 5 3 3 6 9 P(Fail)= 2.83E-03 SF6W4Sl Weight 0 0.12 0.24 0.12 0.18 0.24 0.12 Score 6 7 3 3 3 6 9 P(Fail)= 9.42E-04

Table 5-4 Evaluation of Dynamic Human Preceding Plant Time ns Flood Initiating Events (continued)

Procedures Complexity TraininwExJ, Stress Action Interfaces Adequacy SF6W1S2 Weight 0 0.12 0.24 0.12 0.18 0.24 0.12 Score 6 7 9 3 3 6 10 P(Fail)= 3.35E-02 SF6W2/W3S 2

Weight 0 0.12 0.24 0.12 0.18 0.24 0.12

-'° VI I

Score 6 7 7 3 3 6 10 P(Fail)= 1.12E-02 SF6W4S2 Weight 0 0.12 0.24 0.12 0.18 0.24 0.12 Score 6 7 5 3 3 6 10 P(Fail)= 3.72E-03 SF6W1SF Weight 0 0.12 0.24 0.12 0.18 0.24 0.12 Score 6 7 7 3 3 6 7

Table 5-4 Evaluation of Dynamic Human Actions Flood Initiating Events (continued)

Preceding Plant Time Procedures Complexity Training/Exp Stress Action Interfaces Adequacy P(Fail)= 4.89E-03 SF6W2/W3S F

Weight 0 0.12 0.24 0.12 0.18 0.24 0.12 Score 6 7 5 3 3 6 7 P(Fail)= 1.63E-03 SF6W4SF

'JI I

Weight 0 0.12 0.24 0.12 0.18 0.24 0.12

~

Score 6 7 3 3 3 6 7 P(Fail)= 5.44E-04 FF3W1FH Weight 0.19 0.1 0.19 0.1 0.1 0.19 0.14 Score 7 6 8 4 8 5 9 P(Fail)= 8.13E-02 FF3W2/W3F H

Table 5-4 Evaluation of Dynamic Huma Preceding Action Plant Interfaces Time Adequacy s Flood Initiating Events (continued)

Procedures Complexity Training/Exp Stress Weight 0.2 0.1 0.15 0.1 0.1 0.2 0.15 Score 7 6 6 4 8 5 9 P(Fail)= 3.66E-02 FF3W4FH Weight 0.21 0.11 0.11 0.11 0.11 0.21 0.16 Score 7 6 4 4 8 5 8 P(Fail)= 1.61E-02 VI

....N I

.... FF3WlFL Weight 0.19 0.1 0.19 0.1 0.1 0.19 0.14 Score 9 6 8 4 8 5 9 P(Fail)= 1.96E-01 FF3W2/W3F L

Weight 0.2 0.1 0.15 0.1 0.1 0.2 0.15 Score 9 6 6 4 8 5 9 P(Fail)= 9.31E-02

Table .5-4 Evaluation of Dynamic Buman Actions F1ood Initiating Events (continued)

Preceding Plant Time Procedures Complexity Training/Exp Stress Action Interfaces Adequacy FF3W4FL Weight 0.21 0.11 0.11 0.11 0.11 0.21 0.16 Score 9 6 4 4 8 5 8 P(Fail)= 4.21E-02 FF6W1FH Weight 0.17 0.08 0.17 0.08 0.17 0.17 0.17 Score 6 6 9 5 8 3 9 UI P(Fail)= 7.59E-02 I

~

FF6W2/W3F H

Weight 0.19 0.1 0.19 0.1 0.1 0.19 0.14 Score 6 6 5 5 8 3 6 P(Fail)= 2.78E-03 .

FF6W4FH Weight 0.11 0.11 0.22 0.11 0.06 0.22 0.17 Score 6 6 3 5 8 3 4 P(Fail)= 2.72E-04

Table 5-4 Evaluation of Dynamic Huma.s Flood Initiating Events (continued)

Preceding Action Plant Interfaces Time Adequacy Procedures Complexity Training/Exp Stress FF6W1FL Weight 0.17 0.08 0.17 0.08 0.17 0.17 0.17 Score 8 6 9 5 8 3 9 P(Fail)= 1.66E-01 FF6W2/W3F L

Weight 0.19 0.1 0.19 0.1 0.1 0.19 0.14 Score 8 6 5 5 8 3 6 P(Fail)= 6.70E-03 FF6W4FL Weight 0.11 0.11 0.22 0.11 0.06 0.22 0.17 Score 8 6 3 5 8 3 4 P(Fail)= 4.54E-04 RF6W1R Weight 0.09 0.14 0.18 0.09 0.14 0.18 0.18 Score 2 6 7 2 8 4 7

Table 5-4 Evaluation of Dynamic Human Actions Flood Initiating Events (continued)

Preceding Plant Time Procedures Complexity Traininyfup Stress Action Interfaces Adequacy P(Fail)= 4.58E-03 RF6W2/W3 R

Weight 0.1 0.14 0.19 0.1 0.14 0.19 0.14 Score 2 5 5 2 7 4 6 P(Fail)= 5.23E-04 RF6W4R Weight 0.11 0.17 0.11 0.11 0.17 0.22 0.11 Score 2 5 3 2 7 4 4 P(Fail)= 1.63E-04 CF3WlC3 Weight 0.2 0.08 0.2 0.14 0.14 0.08 0.14 Score 7 5 7 5 7 5 8 P(Fail)= 4.42E-02 CF3W2C3 Weight 0.2 0.08 0.2 0.14 0.14 0.08 0.14

Table S-4 Evaluation of Dynamic Ruma s Flood Initiating Events (continued)

Preceding Plant Time Procedures Complexity Training/Exp Stress Action Interfaces Adequacy Score 7 5 5 5 7 5 7 P(Fail)= 1.22E-02 CF3W2x Weight 0.2 0.08 0.2 0.08 0.1 0.08 0.2 Score 7 5 3 3 3 3 7 P(Fail)= 9.20E-04 PF3W1P Weight 0.17 0.08 0.17 0.08 0.17 0.17 0.17 Score 6 6 7 3 8 3 9 P(Fail)= 2.39E-02 PF3W2P Weight 0.17 0.08 0.17 0.08 0.17 0.17 0.17 Score 6 6 5 3 8 3 9 P(Fail)= 1.09E-02 PF6W1P

Table S-4 Evaluation o( Dynamic Buman Actions Flood Initiating Events (continued)

Preceding Plant Time Procedures Complexity Training/Exp Stress Action Interfaces Adequacy Weight 0.17 0.08 0.17 0.08 0.17 0.17 0.17 Score 6 6 7 3 8 3 5 P(Fail)= 4.96E-03 PF6W2P Weight 0.17 0.08 0.17 0.08 0.17 0.17 0.17 Score 6 6 5 3 8 3 5 P(Fail)= 1.24E-03

6. ACCIDENT SEQUENCE AND SENSITIVITY CALCULATIONS 6.1 Accident Sequence Quantifications The core damage sequences were quantified with the IRRAS code similarly to the internal event analysis.

Truncation limits were also set at 1.00E-10 both for the system and event tree analysis at the cutset level The flood analysis event trees were generally the same as those used in the internal event analysis and were slightly modified as needed. This enabled the use of the same high level fault trees which were previously developed.

The necessary modifications were entered through modifying the system fault trees either by setting certain failure rates to definite fault (true) or by adding flood-specific basic event failures. These accounted for the effects of flood on certain locations and equipment.

Recovery factors were applied to individual cutsets again using the IRRAS code by specifying rules that defined their applicability. The results of the analysis are listed in Tables 6-1 through 6-9 indicating the frequency of each core damage sequence before and after recovery actions. Sequences below 1.00E-10 per year are not listed. The following recovery actions were modeled.

Reflux Cooling - R-B2Wl-XHE-S. R-B2W2-XHE-S. R-B2W3-XHE-S. R-B2W4-XHE-S. The long-term failure of the AFW system disables the reflux cooling method after the initial inventory in the SGs is utilized

(-10 hr). However, alternate means to provide AFW flow exists and may be recovered in the initial -10 hr time period. This may be accomplished by initiating the fire water pumps. Table 6-1 lists the recovery factors in each time window.

Cross Connecting the Unit Charging Systems - R-R3Wl-XHE-F. R-R3W2-XHE-F. R-R3W3-XHE-F. R-R3W4-XHE-F. A large-scale flood inside the charging pump cubicles or one including the rupture of RWST supply pipes may disable the Unit 1 charging system. However, cross connection to the Unit 2 charging system may be utilized to establish the feed-and-bleed method of heat removal. This also requires the opening of at least one of the PORVs (if the safety valves are not removed). Table 6-1 lists the appropriate recovery factors in each time window.

Uncertainty in Reflux Cooling Criterion- R-B2Wl-XHE-A, R-R3Wl-XHE-A. Analyses by Westinghouse, Idaho National Engineering Laboratory, and BNL indicate that one SG may be adequate for reflux cooling at all times. The model has followed the plant procedure (AP.27), which is more restrictive demanding 3 SGs in Time Window 1 and 2 in Time Window 2. This restrictive and therefore conservative modeling was taken into consideration by applying a "recovery" factor. This is not a purely recovery factor, but simply takes into account the uncertainty related to the modeling. Its value was selected at R-B2/R3Wl-XHE-A=.1 consistent with the internal event analyses.

6.2 Sensitivity Calculations As a result of the IPE analysis, Virginia Power has proposed a number of modifications to reduce the risk from flood-related events. The proposed changes involve certain hardware modifications as well as improved procedural or operating practices. Sensitivity calculations were performed to quantify the projected effects of the proposed changes which could serve as a basis for any further cost-benefit type of analysis. In the following a brief summary is given of those proposed modifications which were analyzed in the present study:

Option 1: Turbine Building Sump Pumps Long-Term Operability The power supply of the sump pumps is expected to be shorted out given an increasing water level in the Turbine Building. This is estimated to occur at about the 8" water level. The power supply cabinet may be located at higher elevation to ensure continued operation of the sump pumps for increasing water level in the building. This option is effectively reflects the modification of relocating the electrical cabinet. The results

of the calculations are listed in Table 6-9 indicating the relatively insignificant risk reduction potential (34%

6-1 NUREG/CR-6144

Accident Sequence and Sensitivity Calculations of the total CDF) of Option 1. This is primarily due to the dominant contributions of large-scale floods where

the dewatering capacity is irrelevant.

Option 2: Watertight Door between the Turbine Building and ESGR The fire door connecting the Turbine Building and the ESGR for the plant may be modified to be watertight up to 6'. This would delay considerably the water ingress into the ESGR. The pipe tunnel connecting to the Auxiliary Building would be flooded after the flood dikes are overflowed at 2'. The flood scenario, would start first with a flood in the Auxiliary Building, where about 135,000 gal are required to disable the CCW system leading to the loss of RHR function. After a while, if the flood may not be isolated and the water level reaches 6', the Unit ESGR would be flooded. For the different flood rates, the time evolution is somewhat different in the two buildings. The ratio of the time periods resulting in critical flood volumes in the Auxiliary Building and ESGR, respectively, is close to a factor of two and to a good approximation this ratio is independent of the flood rate. That is, if the Auxiliary Building is flooded in 45 min (135,000 gal leak) then the ESGR will be flooded in 90 min. It is also estimated that for these large flood rates the recovery potential is very poor, therefore, the ESGR will eventually be flooded.

This enables the use of only one class of event trees (F1B2WxD6/R6/Rl0) representing the Flood Scenarios in the ESGR. In this approach, the time period while only the Auxiliary Building is flooded, but not the ESGR, is modeled with the F1B2Wx trees. This method is conservative, because these event trees assume that forced feed and bleed is unavailable, and in reality, this function is available for a certain time period before the ESGR is flooded. Using the Flood Scenario 1 event trees is slightly conservative, but this represents only a fraction of the total mission time (5% at the smallest leak rate), that is judged to be insignificant. The results listed in Table 6-9 indicate that this option is capable of reducing the CDF contribution in mid-loop operations by about 57% from 5.llE-06 to 2.18E-06.

Option 3: Modification of Intake Level Structure The plant is also considering a modification to the intake level structure which would enable personnel to close or isolate the inlet water canal in a short notice. This may be accomplished by modified sliding gates or permanently installed isolation valves. This would effectively ensure a positive isolation outside the Turbine Building reducing the risk from large-scale Turbine Building flood events. The calculated CDF is listed in Table 6-9 and this option is capable of reducing the total CDF in mid-loop operation by about 75% from*

5.llE-06/yr to 1.29E-06/yr.

6.3 Uncertainty Analysis In this section a brief summary is given on the sources and treatment of uncertainty for the flood analysis.

Uncertainty is expressed as a quantitative bounding of the central value and is derived based on assumptions involved on parameters, modeling assumptions, and completeness of the analysis. Uncertainty in the parameter values is propagated through the quantification process obtaining the core damage estimates with numerical bounds.

6.3.1 Sources and Treatment of Uncertainties The flood analysis primarily identified uncertainties in the area of parameter values, that is, modeling uncertainties were not explicitly handled. The parameters of interest are the individual component failure rates, initiating event frequencies and human error probabilities. Sources of parameter uncertainty include lack of data on component failure modes, interpretation of data and component records, and using industry-wide data for plant-specific analyses.

NUREG/CR-6144 6-2

Accident Sequence and Sensitivity Calculations arameter value uncertainties have been handled in this study similar to the NUREG-1150 study, that is, a probability distribution is defined on the value of the parameter such that the nth percentile of the distribution represents the value below which the analyst has a degree of belief of n/100 that the true value lies. This leads to a simple sequence quantification procedure using Monte-Carlo or other sampling techniques. The uncertainty ranges for the distributions are based on generic estimates. These range factors consider variations due to the failure properties of the components in different uses and environments as well as plant-to-plant variations.

6.3.2 Development of Parameter Distributions Probabilistic distributions for parameter values were developed from several sources of information including data developed in NUREG-1150, plant-specific data, and past PRA analyses.

If sufficient plant-specific data were available for a particular component failure mode (primarily maintenance) then the mean value of the parameter distribution was based on plant-specific data. Generic estimates were used for the error factors. Most distributions are assumed to be log-normal distribution even the initiating event frequencies. The error factors for the latter one was obtained through Bayesian updating technique assuming uniform priors with wide ranges. The error factors for the HEPs were established using a simplified approach related to its estimated point value (if HEP>.1 EF=2._HEP>.01 EF=S, HEP<.01 EF=lO).

6.3.3 Quantification of Accident Sequence Uncertainty The uncertainty of the parameter values was propagated through the accident sequence model using the IRRAS computer code using Mon~e-Carlo sampling techniques. First the minimal cutsets were generated for each event tree accident sequence. These minimal sequence cutsets were collected into a core damage cutset xpression. The uncertainty quantification was accomplished on this core damage cutset. The model was not eanalyzed for each sample, that is, it was assumed that for each sample set of all parameters would result in the same cutset. The results are indicated in Table 6-10 with a mean value of CDF 6.24E-06/yr and the 5%

and 95% are 3.21E-07/yr and 2.17E-05/yr.

6.4 References

1. Virginia Power, Surry Nuclear Power Plant, Individual Plant Examination Program, Appendix E:

Internal Flooding.

Internal Flooding Analysis for the Individual Plant Examination, Supplemental Report, Surry *units 1 and 2, Virginia Electric and Power Company, November 1991.

6-3 NUREG/CR-6144

Table 6-1 Evaluation of Recovery Buman Actions Flood Initiating Events Preceding Plant Interfaces Time Adequacy Procedures Complexity Training/Exp Stress Actions Recovery Actions R-R3Wl-XHE-F Weight 0.17 0.12 0.17 0.12 0.12 0.12 0.17 Score 7 6 9 4 8 7 10 P(Fail)= 4.20E-01 R-R3W2/W3-XHE-F Weight 0.17 0.12 0.17 0.12 0.12 0.12 0.17 Score 6 6 8 4 7 7 10 P(Fail)= 1.42E-01 R-R3W4-XHE-F Weight 0.17 0.12 0.17 0.12 0.12 0.12 0.17 Score 5 6 7 4 7 7 10 P(Fail)= 6.36E-02

Table 6-1 Evaluation of Recovery Human Actions Flood Initiating Events (continued)

Preceding Plant Interfaces Time Adequacy Procedures Complexity Training/Exp Stress Actions R-B2Wl-XHE-S Weight 0.14 0.10 0.17 0.12 0.14 0.14 0.17 Score 7 6 9 4 4 5 10 P(Fail)= 6.31E-02 R-R3W2/W3-XHE-S Weight 0.14 0.10 0.17 0.12 0.14 0.14 0.17 Score 6 6 6 4 4 5 8 P(Fail)= 8.95E-03 R-R3W4-XHE-S Weight 0.14 0.10 0.17 0.12 0.14 0.14 0.17 Score 5 6 5 4 4 5 6 P(Fail)= 5.39E-04

Table 6-2 Core Damage Frequencies of Flood Event Trees Flood in Turbine Building, Two-Unit SBO Event Tree Sequence Core Damage Frequency Core Damage Recovery w/o Recovery (/yr) Frequency Actions w/ Recovery

(/yr)

FlB2WlD6 2 5.72E-07 5.72E-08 R-B2Wl-XHE-A FlB2WlR6 3 3.88E-10 4 3.84E-08 l.19E-08 R-B2Wl-XHE-S F1B2W2D6 2 2.13E-06 l.91E-08 R-B2W2-XHE-S F1B2W2R6 3 6.20E-08 4 l.17E-06 8.28E-07 R-B2W2-XHE-S F1B2W3D6 2 l.83E-06 l.64E-08 R-B2W3-XHE-S F1B2W3R10 3 3.06E-08 4 3.40E-09 FlB2W3R6 3 8.43E-07 4 9.36E-08 F1B2W4D6 2 3.52E-07 l.90E-10 R-B2W4-XHE-S F1B2W4R10 3 2.27E-08 3.22E-09 R-B2W4-XHE-G 4 1.46E-06 F1B2W4R6 3 7.22E-10 4 5.43E-08 I TOTAL I I 8.64E-06 I 3.49E-06 I I NUREG/CR-6144 6-6

Table 6-2 Core Damage Frequencies of Flood Event Trees Flood in Turbine Building, Two-Unit SBO (continued)

Event Tree Sequence Core Damage Frequency Core Damage Recovery w/o Recovery (/yr) Frequency Actions w/ Recovery

(/yr)

Recovery 1 R-B2Wl-XHE-S Actions R-B2W2-XHE-S Reflux R-B2W3-XHE-S Cooling R-B2W4-XHE-S 2 R-B2W3-XHE-G Gravity Feed R-B2W4-XHE-G 3 R-B2Wl-XHE-A Uncertainty in Reflux Criterion

6-7 NUREG/CR-6144

Table 6-3 Core Damage Frequencies of Flood Event Trees Flood in Turbine Building, Two-Unit SBO Event Tree Sequence Core Damage Frequency Core Damage Recovery Action w/o Recovery (/yr) Frequency w/ Recovery

(/yr)

F2B2WlD6 2 l.36E-07 l.36E-08 R-B2W1-XHE-A F2B2WlR6 3 -

4 9.13E-09 2.83E-09 R-B2Wl-XHE-S F2B2W2D6 2 5.06E-07 4.53E-09 R-B2W2-XHE-S F2B2W2R6 3 1.47E-08 4 2.79E-07 l.96E-07 R-B2W2-XHE-S F2B2W3D6 2 4.36E-07 3.90E-09 R-B2W3-XHE-S F2B2W3R10 3 7.28E-09 4 8.09E-10 F2B2W3R6 3 2.00E-07 4 2.22E-08 F2B2W4D6 2 8.37E-08 5.93E-11 R-B2W4-XHE-S F2B2W4R10 3 6.30E-09 6.27E-10 R-B2W4-XHE-G 4 3.48E-07 F2B2W4R6 3 2.lOE-10 4 l.29E-08 I TOTAL I I 2.06E-06 I 8.29E-07 I I NUREG/CR-6144 6-8

Table 6-3 Core Damage Frequencies of Flood Event Trees Flood in Turbine Building, Two-Unit SBO (continued)

Event Tree Sequence Core Damage Frequency Core Damage Recovery Action w/o Recovery (/yr) Frequency w/ Recovery

(/yr)

Recovery 1 R-B2Wl-XHE-S Actions R-B2W2-XHE-S Reflux R-B2W3-XHE-S Cooling R-B2W4-XHE-S 2 R-B2W3-XHE-G Gravity Feed R-B2W4-XHE-G 3 R-B2Wl-XHE-A Uncertainty in Reflux Cooling Criterion 6-9 NUREG/CR-6144

Table 6-4 Core Damage Frequencies of Flood Event Trees Flood in Auxiliary Building Event Tree Sequence Core Damage Frequency Core Damage Recovery Actions w/o Recovery (/yr) Frequency w/ Recovery

(/yr)

F3R3WlD6 3 2.38E-08 2.38E-09 R-R3Wl-XHE-A 4 7.33E-08 7.87E-09 R-R3Wl-XHE-R F3R3W1R6 3 -

4 -

5 -

8 3.29E-10 9 1.99E-09 F3R3W2D6 4 1.SOE-08 5 l.33E-08 F3R3W2R6 3 4.84E-09 4 -

5 1.61E-09 8 6.79E-08 l.40E-08 R-R3W2-XHE-F 9 5.54E-08 l.26E-08 R-R3W2-XHE-F F3R3W3D6 4 4.56E-09 F3R3W3R10 3 -

4 7.38E-10 6 2.06E-10 NUREG/CR-6144 6-10

Table 6-4 Core Damage Frequencies of Flood Event Trees Flood in Auxiliary Building (continued)

Event Tree Sequence Core Damage Frequency Core Damage Recovery Actions w/o Recovery (/yr) Frequency w/ Recovery

(/yr)

F3R3W3R6 3 -

4 2.26E-08 3.SOE-09 R-R3W3-XHE-F 6 5.84E-09 F3R3W4D6 4 -

F3R3W4R10 4 8.06E-09 6 4.37E-08 2.90E-09 R-R3W4-XHE-F F3R3W4R6 4 2.42E-10 6 1.59E-09 TOTAL 3.45E-07 1.02E-07 Recovery 1 R-R3Wl-XHE-A Uncertainty . ,~ .

Actions in Reflux Cooling Criterion R-R3W2-XHE-F Cross-2 R-R3W3-XHE-F connecting R-R3W4-XHE-F Charging System to Unit 2 6-11 NUREG/CR-6144

Table 6-5 Core Damage Frequenc1es o fFl 00dEven tTrees Flood in Auxiliary Building Event Tree Sequence Core Damage Frequency Core Damage Recovery Actions w/o Recovery (/yr) Frequency w/ Recovery

(/yr)

F4R3WlD6 2 2.73E-07 2.73E-08 R-R3Wl-XHE-A F4R3WlR6 3 1.85E-10 5 8.53E-09 F4R3W2D6 3 l.OSE-07 l.49E-08 R-R3W2-XHE-F F4R3W2R6 3 2.96E-08 4.21E-09 R-R3W2-XHE-F 5 4.14E-07 7.64E-08 R-R3W2-XHE-F F4R3W3D6 3 9.03E-08 l.27E-08 R-R3W3-XHE-F F4R3W3R10 3 1.46E-08 2.0SE-09 R-R3W3-XHE-F 4 l.63E-09 F4R3W3R6 3 4.03E-07 5.72E-08 R-R3W3-XHE-F 4 4.47E-08 6.36E-09 R-R3W3-XHE-F F4R3W4D6 3 2.20E-09 F4R3W4R10 3 3.00E-07 l.91E-08 R-R3W4-XHE-F 4 7.0IE-07 4.46E-08 R-R3W4-XHE-F F4R3W4R6 3 l.llE-08 7.0SE-10 R-R3W4-XHE-F 4 2.60E-08 l.65E-09 R-R3W4-XHE-F TOTAL 2.42E-06 2.SOE-07 Recovery 1 R-R3Wl-XHE-F Actions R-R3W2-XHE-F Cross-R-R3W3-XHE-F connecting R-R3W4-XHE-F Charging System to Unit 2 2 R-R3Wl-XHE-A Uncertainty in Reflux Cooling Criterion NUREG/CR-6144 6-12

Table 6-6 Core Damage Frequencies of Flood Event Trees Flood in Safeguard Area Event Tree Sequence Core Damage Frequency Core Damage Recovery Actions w/o Recovery (/yr) Frequency w/ Recovery

(/yr)

F5R3W1D6 2 3.83E-07 3.83E-08 R-R3Wl-XHE-F F5R3W1R6 3 2.59E-10 5 l.39E-08 F5R3W2D6 3 7.76E-07 2.50E-08 R-R3W2-XHE-F F5R3W2R6 3 4.14E-08 5.89E-09 R-R3W2-XHE-F 5 5.96E-07 8.47E-08 R-R3W2-XHE-F F5R3W3D6 3 1.SOE-07 2.14E-08 R-R3W3-XHE-F F5R3W3R10 3 2.0SE-08 2.91E-09 R-R3W3-XHE-F 4 2.28E-09 F5R3W3R6 3 5.63E-07 8.00E-08 R-R3W3-XHE-F 4 6.26E-08 8.89E-09 R-R3W3-XHE-F F5R3W4D6 3 4.47E-09 F5R3W4R10 3 4.20E-07 2.67E-08 R-R3W4-XHE-F 4 9.81E-07 6.24E-08 R-R3W4-XHE-F F5R3W4R6 3 l.55E-08 9.91E-10 R-R3W4-XHE-F 4 3.63E-08 2.31E-09 R-R3W4-XHE-F I TOTAL I I 3.47E-06 I 3.81E-07 I I Recovery R-R3Wl-XHE-F Cross-Actions R-R3W2-XHE-F Connecting R-R3W3-XHE-F Charging R-R3W4-XHE-F System to Unit 2 6-13 NUREG/CR-6144

Table 6-7 Core Damage Frequencies of Flood Event Trees Spray in Containment Event Tree Sequence Core Damage Frequency Core Damage Frequency w/o Recovery (/yr) w/ Recovery (/yr)

F6R4W1D6 4 -

5 -

F6R4W1R6 4 -

5 -

6 -

9 -

10 -

F6R4W2D6 5 -

6 -

F6R4W2R6 4 -

5 -

6 -

9 -

10 -

F6R4W3D6 5 -

F6R4W3Rl0 4 -

5 -

7 -

F6R4W3R6 4 -

5 -

7 -

NUREG/CR-6144 6-14

Table 6-7 (Continued)

Core Damage Frequencies of Flood Event Trees Spray in Containment Event Tree Sequence Core Damage Frequency Core Damage Frequency w/o Recovery (/yr) w/ Recovery (/yr)

F6R4W4D6 5 -

F6R4W4R10 5 -

7 -

F6R4W4R6 5 -

7 -

I TOTAL I I - I I 6-15 NUREG/CR-6144

Table 6-8 Core Damage Frequencies of Flood Event Trees Flood in Mechanical Equipment Room No. #3, Tuo-Unit SBO Event Tree Sequence Core Damage Frequency Core Damage Recovery w/o Recovery (/yr) Frequency Acti.ons w/ Recovery

(/yr)

F7B2WlD6 2 3.0lE-09 F7B2W1R6 3 -

4 2.02E-10 F7B2W2D6 2 l.12E-08 1.00E-10 R-B2W2-XHE-s F7B2W2R6 3 -

4 6.19E-09 F7B2W3D6 2 9.65E-09 F7B2W3R10 F7B2W3R6 3

4 3

3.76E-10 4 4.92E-10 F7B2W4D6 2 l.85E-09 F7B2W4R10 3 1.02E-10 4 7.71E-09 F7B2W4R6 3 -

4 2.85E-10 I TOTAL I I 4.38E-08 I 3.26E-08 I I Recovery l R-B2W2-XHE-S Reflux Actions Cooling NUREG/CR-6144 6-16

Table 6-9 Core Damage Frequencies for Flood Events Sensitivity Cases Core Damage Frequency Options w/ Recovery

~CDF POS 6 POS 6 POS 10 Total (Base-Total)

Drained Refueling Refueling 1 - Relocation of Sump Pump 2.77E-07 l.83E-06 1.25E-06 3.36E-06 l.75E-06 Power Supply 2 - Watertight Door on ESGR 2.49E-07 l.22E-06 7.13E-07 2.18E-06 2.93E-06 3 - Modification of Intake Level 2.27E-07 752E-07 3.08E-07 l.29E-06 3.82E-06 Structure Base Case-Internal Flood 3.19E-07 2.75E-06 2.04E-06 5.1 IE-06 -

Events 6-17 NUREG/CR-6144

Table 6-10 Core Damage Frequencies for Flood Events Uncertainty Results Flood Analysis Core Damage Frequency (/yr)

Point Estimate 5.llE-06 Mean Value 4.80E-06 5% Value 2.18E-07 95% Value l.78E-05 Median Value l.71E-06 NUREG/CR-6144 6-18

7. PLANT DAMAGE STATE ANALYSIS

In this section a brief summary is presented on the development and identification of plant damage states for Level 2 analysis. This process delineates the dominant core damage sequences and cutsets into plant damage states (PDSs). The plant damage state analysis involved the identification of detailed PDS categories using a seven state indicator. The event trees discussed in the previous sections assessed the severity of accident consequences, whether or not a core damage occurs. In order to assess the severity of accident consequences, the degree to which containment systems remain operable must also be determined.

7.1 Definition of Plant Damage State Indicators A total of seven PDS indicators were used to identify the unique plant damage states. The number of cutsets comprising the flood analysis is limited to less than 500 cutsets above the truncation limit of l.E-10. This limited number of cutsets allowed to incorporate all of the cutsets into appropriate PDSs. The seven indicators address the following issues:

Time of accident initiation Status of AC power Human error Status of RCS at onset of core damage Status of ECCS Status of recirculation spray system Status of RWST The above PDS indicators question the status of various safety system and their actual state is indicated by various letters indicating the possible status of these variables. Table 7-1 lists a more detailed description of the indicators and their possible status with the appropriate letter designations.

7.2 PDS Analysis, Rules The PDS analysis was based on the previous event tree analysis. All core damage sequences were identified and logic rules were developed to assign the flood sequence cutsets to the various PDSs. The rules were developed and applied in the IRRAS code. The code automatically assigned the flood cutsets into the appropriate PDS according to the specified rules. The final cutset assignment was manually verified to insure full consistency of the results. A total of 35 different PDSs were obtained.

The most dominant PDSs are designated as 2UNLUUN, 3UNLUUY and 4UNLUUN. All of these PDSs describe similar plant damage states with the exception of the status of the RWST and time windows. In general, these PDSs represent large scale flooding of the ESGR resulting in nonrecoverable loss of emergency power (simulated as two unit SBO). It does not involve any human error and mostly occurs in time window 2, 3 or 4, when the RCS may not reach high pressure. The loss of emergency power automatically disables the power for the ECCS and recirculation spray system equipment .

7-1 NUREG/CR-6144

Plant Damage State Analysis 7.3 PDS Uncertainty Analysis Uncertainty analysis were performed for each of the PDSs utilizing a Monte-Carlo sampling routine in the IRRAS code. The calculations for each PDS were done independently not accounting for effects represented by the sharing of many basic events through the PDSs. The results are listed in Table 7-2.

NUREG/CR-6144 7-2 L

Plant Damage State Analysis

PDS Indicator Table 7-1 Plant Damage State Definitions Status Designator I I I Time of Accident Initiation 1 - Window 1 2 - Window 2 3 - Window 3 4 - Window 4 Status of AC Power Y - Available U - Nonrecoverable blackout B - Recoverable blackout (using off-site power)

F - Loss of 4 kV Bus Human Error N - No human error or nonrecoverable human error D - Diagnosis error A - Action error Status of RCS at Onset of Core Damage L - Low pressure G - 5% probability that pressure is high Status of ECCS U - Hardware Failure R - Recoverable if human error, LOSP, or 4 kV recovered C - Failure of recirculation Status of Recirculation Spray System R - Recoverable U - Nonrecoverable Status of RWST Y - Injected R - Recoverable, not injected N - Nonrecoverable, not injected 7-3 NUREG/CR-6144

Plant Damage State Analysis Table 7-2 Plant Damage States Results of Uncertainty Analysis PDS POINT MEAN 5% MEDIAN 95%

1 lUNGUUN 8.88E-08 6.97E-08 2.20E-09 2.12E-08 2.60E-07 2 lUNGUUY 3.88E-10 2.70E-10 6.96E-13 2.84E-11 1.0SE-09 3 lYAGRRR 9.06E-09 9.03E-09 1.09E-10 2.09E-09 3.23E-08 4 lYAGRRY 1.96E-09 1.68E-09 1.14E-11 2.56E-10 5.97E-09 5 lYAGRUR 5.37E-08 5.98E-08 1.29E-09 1.35E-08 2.30E-07 6 lYAGRUY 1.85E-10 l.34E-10 4.24E-13 1.33E-11 4.27E-10 7 lYDGRRR 5.95E-10 5.41E-10 3.37E-12 1.08E-10 2.02E-09 8 lYNGRRR 1.llE-10 8.23E-11 1.06E-13 5.40E-12 3.33E-10 9 lYNGRRY 3.0SE-10 2.0lE-10 5.17E-13 2.llE-11 7.87E-10 10 lYNGRUR 7.35E-09 7.34E-09 4.73E-11 1.28E-09 2.97E-08 11 lYNGRUY 2.77E-08 2.88E-08 2.02E-10 4.37E-09 9.75E-08 12 2UNLUUN 1.0SE-06 1.21E-06 2.65E-08 2.98E-07 4.47E-06 13 2UNLUUY 7.67E-08 6.0SE-08 5.70E-10 l.48E-08 2.lSE-07 14 2YALRRR 2.31E-08 2.09E-08 2.03E-10 4.88E-09 7.880E-08 15 2YALRRY 3.09E-09 2.92E-09 3.59E-11 6.55E~10 8.53E-09 16 2YALRUR 1.98E-07 1.89E-07 6.lSE-09 6.19E-08 7.79E-07 17 2YALRUY 1.14E-08 l.03E-08 7.91E-ll 2.0lE-09 5.03E-08 NUREG/CR-6144 7-4

Table 7-2 (Continued)

Plant Damage States Results of Uncertainty Analysis PDS POINT MEAN 5% MEDIAN 95%

19 2YDLRUR 3.49E-10 3.22E-10 3.92E-12 7.46E-ll 1.14E-09 20 2YNLRRR 3.18E-09 3.llE-09 1.99E-ll 4.52E-10 1.13E-08 21 2YNLRRY 8.0lE-10 7.97E-10 5.17E-12 1.05E-10 2.84E-09 22 2YNLRUR 1.02E-08 1.27E-08 9.58E-ll l.86E-09 4.22E-08 23 2YNLRUY l.85E-08 l.59E-08 l.97E-10 3.50E-09 6.73E-08 24 3UNLUUN l.51E-07 l.84E-07 3.59E-09 4.82E-08 5.79E-07 25 3UNLUUY l.OSE-06 9.83E-07 2.19E-08 2.81E-07 3.92E-06 26 3YALRRR l.35E-08 l.99E-08 l.96E-10 2.60E-09 3.70E-08 27 3YALRUR l.94E-07 l.90E-07 6.47E-09 7.0lE-08 6.79E-07 28 3YDLRRR 1.07E-09 9.42E-10 2.14E-ll 2.85E-10 3.68E-09 29 3YNLRRR 1.82E-10 l.89E-10 1.72E-13 8.87E-12 4.39E-10.

30 4UNLUUN l.89E-06 1.99E-06 l.02E-08 2.34E-07 7.30E-06 31 4UNLUUR 4.88E-09 5.21E-09 l.94E-11 5.09E-10 1.23E-08 32 4YALRRR 1.lOE-08 6.98E-09 4.47E-11 9.37E-10 2.86E-08 33 4YALRUR 1.65E-07 1.59E-07 l.93E-09 2.56E-08 5.76E-07 34 4YDLRRR l.33E-10 l.06E-10 1.17E-13 7.41E-12 3.97E-10 35 4YNLRRR l.62E-09 1.25E-09 2.14E-12 7.56E-11 4.38E-09 7-5 NUREG/CR-6144

8. CONCLUSIONS AND

SUMMARY

The major objective of the Suny internal flood analysis was to provide an improved understanding of the risk arising from internal flood related events. The present analysis concludes that the most dominant contributors to core damage due to internal floods are accident scenarios initiated in the Turbine Building draining the intake canal. This potentially could result in a flood encompassing the plant ESGRs leading to a two unit loss of all emergency power (Fl and F2 scenarios).

The Turbine Building internal flood accident scenarios account for approximately 85% of the total core damage frequency due to internal floods. This result is mainly due to the specific features of the Surry circulating water system and may not be applicable to other plants. The second most dominating flood scenario involves flooding of the Safeguard/Auxiliary Building in combination with the unavailability of the RWST. The contribution of these scenarios ( F4 and F5) is approximately 13% of the total internal CDP.

These specific findings again may not be generalized to other plants due to the plant-specific nature of the actual evolvement of these accident scenarios.

8.1 Plant-Specific Conclusions The internal flood CDP is dominated by Turbine Building flood events. These events are primarily initiated by either valve or expansion joint failures in the main inlet lines of the circulating water system. These failures may lead to pipe ruptures upstream of the condenser water box and inlet valves. At Surry the circulating water system is gravity fed from a very large capacity intake canal and its isolation may not be accomplished in a timely manner. This is in contrast with other common design arrangement where dedicated pumps provide the required cooling water flow through the system. In that case, by stopping the pumps would effectively isolate the system limiting potential water outflow.

The potential draining of the intake canal inventory in the Turbine Building is risk significant due to a plant-specific spatial interdependence. For both units the ESGRs are located in the Service Building on the same elevation as the Turbine Building basement. These areas are separated by a fire door with 2' high flood dikes in front of them. A large scale flood could potentially overflow the dikes enter into the two unit ESGR leading to the potential loss of both unit emergency power including the loss of RHR stub busses. The normal off-site power supply to the plant would not be affected since the normal SGR is located at higher elevation in the Service Building.

The next important contributor to internal flood CDP is due to flood events originated or entering into the Auxiliary Building. These flood scenarios, mainly supply pipe ruptures from the RWST, result in the loss of all CCW and consequently RHR function at the plant. This coupled with the unavailability of the RWST inventory to be injected into the reactor core leads to core damage. Again, the plant-specific spatial arrangement of piping and equipment is the main reason for the development of the accident scenario and its risk significance.

8.2 Accident Sequence Conclusions The main results of the flood analysis are presented in Table 8-1 listing the core damage frequencies of the analyzed operating states. The most dominant flood scenario, 85% of the total CDP, is the one occurring in the Turbine Building and overflowing the flood dikes at the unit ESGR causing the loss of all emergency power for the two units (Fl and F2 scenarios).

8-1 NUREG/CR-6144

Conclusions and Summary The most dominant sequences, F1B2W4R10 - 4, F1B2W2R6 - 4 and F1B2W3R6 - 3, represent large s c a l e .

flooding of the E~GR initiated in the Turbine Building coupled with the inability of recovering. The flood in the ESGR disables all equipment required for feed-and-bleed operations and thus only reflux cooling and/or gravity feed options may be utilized. However, the primary coolant loops are isolated 70 % in Time Window 2 and 100% of the time in Time Windows 3 and 4, respectively. In these sequences, the pressurizer safety valves are not removed which prevents the use of the gravity feed options. Therefore, these sequences are effectively nonrecoverable except by some "ad hoc" means, which is not taken into account in these analyses.

The second group of accident sequences, F2B2W4R10 - 4, F2B2W2R6 - 4 and F2B2W3R6 - 3, are similar as the first group with the addition of the postulated difficulties in diagnosing accident conditions due to potential damage to the DC panels (instrumentation signals) in the ESGR.

The next most important group of sequences are associated with Auxiliary Building floods, F5R3W2R6 - 5 and F4R3W2R6 - 5. In both cases, the flood is initiated by a pipe rupture draining a large fraction of the RWST inventory into the Safeguard or Auxiliary Building. The flood would eventually collect in the Auxiliary Building basement leading to a loss of CCW and RHR event. Forced feed and bleed is unavailable since the RWST must be isolated. In these sequences, either the RCS loops are isolated or other malfunction prevents the utilization of the steam generators through the reflux cooling technique.

8.3 Uncertainty Considerations The probabilistic assessment and accident sequence modeling of the plant involves the combination of many individual events representing initiating frequencies, component and operator failures. The core damage frequency estimates are derived by using these individual events which of themselves have in many cases significant uncertainties. The probabilistic accident sequence model may be used to develop importance measures and to calculate the appropriate uncertainty distribution of the individual and the sum of the accident sequence core damage frequencies.

These uncertainty analyses have been completed and the main results of these calculations are listed in Table 8-2 indicating the uncertainty bounds of the core damage frequency due to internal floods. The important measures of the uncertainty distribution are the 5%, mean and 95% values at 2.18E-07, 4.SOE-06 and 1.78E-05/yr, respectively. The mean and point value estimate of the CDF are 4.SOE-06 and 5.llE-06/yr.

8.4 Other Considerations Important recovery options are related to the long-term operation of the reflux cooling method (AFW supply) and to the establishment of backup charging flow from Unit 2. The analysis also took credit for uncertainty in the success criterion used for the reflux cooling.

The flood initiating event analysis indicated that the shutdown and specifically the mid-loop operational period does not pose a unique flood risk with the exception of flood events coupled with loop isolation in Time Windows 2, 3 and 4. In general, the risk contribution from flood events is relatively significant and is dominated by potential flood events into the ESGR coupled with loop isolation.

Sensitivity calculations were also completed for a number of proposed options and the results are summarized in Table 8-3. The most effective analyzed options are the installation of watertight doors on the ESGR NUREG/CR-6144 8-2

Conclusions and Summary (Option 2) and modification of the intake structure (Option 3), which are capable of reducing the CDP contribution in mid-loop by 57 and 75%, respectively, i.e., 2.18E-06/yr and 1.29E-06/yr from the base 5.llE-06/yr.

8-3 NUREG/CR-6144

Conclusions and Summary Table 8-1 Core Damage Frequencies for Flood Events Summary Core Damage Frequency Scenario w/ Recovery POS6 POS6 POS 10 Total Refueling Drained Refueling Turbine Building 1.89E-06 9.29E-08 1.50E-06 3.49E-06 Fl Turbine Building 4.49E-07 2.21E-08 3.57E-07 8.28E-07 F2 Auxiliary Building 4.65E-08 4.31£-08 1.19E-08 1.02E-07 F3 Auxiliary Building 1.55E-07 5.71E-08 6.74E-08 2.SOE-07 F4 Safeguard Area 1.97E-07 8.92E-08 9.43E-08 3.81E-07 FS Spray in Containment - - - -

F6 Mechanical Equipment 1.02E-08 1.46E-08 7.81£-09 3.26E-08 Room No. #3 - F7 I Total-Flood I 2.75E-06 I 3.19E-07 I 2.04E-06 I 5.llE-06 I

Total-Internal Events 1.45E-06 3.12E-06 3.12E-07 4.88E-06 NUREG/CR-6144 8-4

Table 8-2 Core Damage Frequencies for Flood Events Uncertainty Results Flood Analysis Core Damage Frequency (/yr)

Point Estimate 5.llE-06 Mean Value 4.SOE-06 5% Value 2.18E-07 95% Value 1.78£-05 Median Value 1.71£-06

8-5 NUREG/CR-6144

Conclusions and Summary Table 8-3 Core Damage Frequencies for Flood Events Sensitivity Cases, Summary Core Damage Frequency Options w/ Recovery aCDF POS6 POS 6 POS 10 Total (Base-Tot~I)

Drained Refueling Refueling 1 - Relocation of Sum Pump 2.77E-07 1.83E-06 1.25E-06 3.36E-06 1.75E-06 Power Supply 2 - Watertight Door on ESGR 2.49E-07 1.22E-06 7.13E-07 2.18E-06 2.93E-06 3 - Modification of Intake Level 2.27E-07 7.52E-07 3.08E-07 1.29E-06 3.82E-06 Structure Base Case-Internal Flood 3.19E-07 2.75E-06 2.04E-06 5.llE-06 .

Events NUREG/CR-6144 8-6

Appendix A Equipment Locations Appendix A Equipment Locations A-1

Appendix A Equipment Locations Tag# Description Containment Elevation : -27'*7" Recirculation Spray Pumps Top of containment sump screen HCV-1310A MOV-1701 FCV- 1605 MCV -1758 MOV-1720A&B LT-1797 Steam Generator level monitor 1-RH-2S 1-RH-29 RS coolers HX inside crane wall. SW side of Containment Accumulators MOV - 1865 NB!C Accumulator discharge valves Sump Pumps (1) in-core instrumentation room, (2) containment sump, (3) primary vent, (4) primary drain transfer pump Primary drain transfer Compressed air tanks near tank and HX accumulator IA 1-IA-TK-2NB Elevation: -13'-0" 1-RHR-P-lA,lB RHR pumps + motors 1-CC-185 1-CC-182 1-CC-178 1-CC-181 1-CC-110 A-2

Tag#

1-CC-112 Description Appendix A Equipment Locations 1-CC-122 1-CC-118 Excess letdown HX I Elevation: -3'-6" I

LCV

1460 A,B Letdown isolation MCV - 1200 A,B,C Letdown isolation MCV-1142 MOV-1700 PT- 1402-1 PT- 1449

'IE - 1413-2,1423-2,1433-l Instrumentation

'IE - 1410-A,1420-A,1430 LT - 1477A,1487A Regenerative HX BehindPRT Elevation: 18'-4" PT-MS137A,B Steam Generator pressure LT-1459A,1461 Pressurizer Level RCPC-4C Communication antenna levation : 47'-4" MOV-FW-151 A,B,C,D,E AFW valves SV-1551 A,B,C Pressurizer Safety Valves Safeguards Area Elevation : -3'-6" A-3

Appendix A Equipment Locations Tag#

AFW-1-FW-P-4A.B Description AFW Booster Pumps PT-MS-101 A.B,C Regulators EP-MS-101 A.B,C 1-IA-C-4NB Instrument Air 1-IA-D-4NB Instrument Air Elevation : -27' Valve Pit LHSI pumps MOV-1860NB Valve pit leakoff pot Elevation: 12' RS pumps MOV -18621 NB MOV-1864NB MOV -1890 NB/C Safeguard area sump pumps Elevation : 19' MOV - 1885 NB/CID Elevation : 18'-4" MOV-CS101A 1-CS-P-lA. 1B Containment Spray Pumps MOV-CS-lOOA l-FW-P-2, 3A. 3B AFW Pumps Turbine + 2 Motor Driven PCV-MS102A, B Steam to AFW Pumps A-4

Appendix A Equipment Locations Tag# Description

RV-MSI01A, B, C SGPORV MOV-260A,B AFW Cross-connect valves TV-MS-lOlA, B, C Main Steam Isolation Valves 1-FW-288, 119, 120, 185, 169, 140

-154, 184 1-RS-P-2A, B Recirculation Spray Pumps 1-SI-P-lA, lB SI Pumps Refueling Recirculation Pumps PT-1474, 1485, 1496 SG Pressure Instrumentation PT-MS137A, B Auxiliary Building Elevation : 2'-0" MOV-1275 A,B,C MOV-1289NB FCV-1172 MOV-1373 1-CH-728 Charging Xconnect 2-CH-447 Charging Xconnect 1-CH-294,297,300 Seal water supply TV-CC-109A,B MOV-1370 MOV-1381 MOV-1286 NB/C MOV-1267A,1269A,1270A 1-CH-P-lA,B,C Charging pumps TCV-SWI08NB/C 1-CC-P-lNB/C/D CCWpumps 1-CC-P-2NB Charging pump cooling water pump A-5

Appendix A Equipment Locations Tag#

1V-SI-102 NB Description

HCV-1186 1-CC-104,108 MOV-1287NB/C 1-RT-P-lNB/C SG recirc. and transfer pumps 1-RT-AX-lNB/C SG recirc. and transfer coolers Charging pump seal cooling surge tank Intermediate seal coolers Charging pump lube oil coolers CH/HHSI pumps in charging pump cubicles MOV-1115 DIE HHS! suction from RWST, in "C' CH pump cubicle.

(LHSI to HHSI XTIE) in "B" CH pump cubicle, upper MOV-1863NB level.

(HHSI to cold leg) penetration area MOV-1867 CID (HHSI to hot leg) penetration area MOV-I869NB (HHS! to cold leg) penetration area MOV-1842 Non-regenerative HX Letdown filter Seal water injection filters Seal water HX Aux. Bldg. sump pumps Elevation: 13'-0" LCV-1115E(C)

M0D-l01NB/C RCPC-4C Communication Antenna RV-MS-I01NB/C SG PORV isolation panel LCV-1115D Charging pump suction from RWST

A-6

Tag#

LCV-1115B Description Appendix A Equipment Locations Charging pump suction from RWST 480 MCC lHl-2 480 MCC lJl-2 Non-regenerative HX (first & second floor)

Demineralizes RCS filter Seal water return filter Boric Acid Tank (2nd & 3rd fl)

Boric Acid Batching Tank Boric Acid Transfer pump Boric Acid Filter

Elevation 27'-6"

HT-T-2A3 Emergency communication XFERSW PWR Heat tracing distr. panel 1-CD-E-lNB/C Aux. Bldg. 3rd Fl. west side.

CCW surge tank chemical addition tank 1-CV-P-lNB chilled CCW pumps 1-CV-HX-lNB chilled CCW coolers containment vacuum pump Hydrostatic Test pump Radiation monitors CH-128/129 Volume Control Tank Chemical Mixing Tank MCC-1A2-1 (West)

A-7

Appendix A Equipment Locations Tag# Description MCC-1C2-1 Elevation: 45'-10" A0D-VS-103NB A0D-VS-101A/B MOD-VS-lOONB A0D-VS-107NB AOD-VS-108 AOD-VS-lllNB M0D-VS-58NB 1-VS-F-9A/B Exhaust fan 1-VS-F-58A/B Filtered exhaust fan 1-VS-DMP-60A/B,61NB Starter 588 for 1-VS-F-58B Telecommunication system repeaters Containment vacuum air ejector 47' Level Service Building Elevation !8'-0" Unit 1 Switchgear Room 4160 VAC Bus lA, lB, IC Transfer Bus D,E,F 480 VAC Bus 1Al,1A2 480 VAC Bus 1Bl,1B2 480 VAC Bus 1Cl,1C2 MCC-182-1 (West)

MCC-lCI-2 (West)

A-8

Tag#

Elevation: 42', 45', 47' Mech. Eqp. Room 1 & 2 Description Appendix A Equipment Locations PNL REM & RMP-1 Remote monitoring panel 1-VS-E-3NB Central chiller 1-VS-247 1-VS-251 1-VS-E-3NB Power transfer cabinet 1-VS-P-3NB Central chilled water pump Antenna for station operations 1-repeater-AE, I-Repeater-A Telecommunication repeaters FW regulating valves FW regulating bypass valves MOV-154 NB!C water source/chillers cable spreading &

Mech. Eq. Room Penetration to MCR Sealed Elevation 27'-0" MCR + Computer Room Vital Bus CAB 1-1 1-III 1-IV 1-III 1-SVB-1-Semi-vital bus &

transformer 1-VS-AC-1,2,8,9 Air conditioninig I Diesel-Generator Area I

Emergency DG-1/2/3 Emergency DG control cab-1/2/3 DIP-DGRM-Local control panel 1/2

A-9

Appendix A Equipment Locations Tag#

1-EE-EG-1/2 2-EE-EG-1 Description Control cabinet MCC-lHl-lA MCC-lJl-lA MCC-2Hl-1A Elevation

9'-6" Emergency Switchgear Room 4160 VAC Emergency buses lH/lJ 480 V AC Emergency buses lH/lJ 480 Emergency buses lHl/lJl (includes Stub bus lH/lJ)

MCC lHl-1 and lJl-1 Vital buses 1-IA, IIA, IIIA, IVA DC Buses lA, lB, DC Sub panel 1B Station Batteries lA, 1B UPS lB-1, 1B2 UPS lAl, lA-2 Generator relay cabinet AuxSHTDPNL I Elevation 9'-6" Mechanical Eq Rm No. #3 I

2-SW-443 CPSW pump cross-connect 1-SW-P-108 Charging PMP SW Pump 1-VS-P-lC Condenser water pump PCV-SW-lOOC 2-IA-1106/1107/1108/1109 Vacuum Breaker Trip Valves MOV-PG-107C 1-VS-E-4C Chiller A-10

Tag#

1-VS-P-2C Description Chilled water pump Appendix A Equipment Locations Turbine Building Elevation 9'and 6" Mechanical Eq. Room 3 1-SW-269 CPSW Cross Connect 1-SW-P-lONB Charging PMP SW pump Elevation, Ground Floor : 9'-6" MOV-SW-181 NB MOV-SW-182 NB MOV-CW-180 NB/CID MCC-lAl-2, 1A2-3 (West)

MCC-lBl-3 (West)

MCC-182-2 (East) 1-BD-E-1A,1B,2A,2B,1C,2C Blowdown HX (East wall)

Main FW pumps MOV-150NB FW valves, West FCV-150NB next to MFW pumps FW heaters-vertically in basement CCWHX Component cooling radiation monitors BCP-lNB Brg cooling water pump BC-P-2 BRGcoolers SW-P-4NB SW pumps Condensate pumps

A-11

Appendix A Equipment Locations I

Tag#

Elevation : 29', 35', 50' Mezzanine Description I

l-AS-3, 19,28 MOV-CW-186A!B/C/D TCV-MS-105A!B, 106A/B Steam Dump Valves 107A/B, 108A!B FCV-MS-104A!B/C/D PCV-AS-108 1-VP-AOV-220El/E2/Fl/F2 Vacuum Breakers 1-VP-AOV-220Gl/G2/Hl/H2 MCC-1A2-2 West MCC-1C2-2 West 1-CD-REF-lA/B Chilled water, northwest corner 1-CD-P-4A/B/C Chilled water circulating pump 1-SW-P-13A!B in Mech. Eq. Room 3 Gland seal condenser Main air ejectors Hogger ejectors Elevation : 58'6" Operating Floor TV-MS-1,2,3,4 Turbine stop valve 1-CD-TK-lA/B chilled water tank - north Intake Structure 1-CW-P-lA!B/C/D Circulating water pumps 1-CW-P-2A!B/C/D 1-SW-P-lA/B/C Control Panel P-lA!B/C A-12

Appendix B High Level System Fault Trees

B.-1

Gravity from 1n B2, Window 1 Gravity from RWST in B2 Safety Valve Removed in Window 1

INSLF FLOW Faihre to Diaqnose Operator Failure THROUGH LOW HEAD Loss of RHR Event to establish IN-.ECTJJN FLOW in POS 6 gravity feed PATH 1n window 1 D6-CG D-F1B2W1-XHE A-F1B2W1-X-G-4

Gravity from R\VST In B2, Window 2 Grovity from RWST in 82 Safety Valve Removed in Window 2

sv-we INSUF FLOW FailLre to Diagnose THROUGH LOW HEAD Loss of RHR Event IN.ECTIJN FLOW in POS 6 PATH D6-CG D-F1B2W2-XHE A-F1B2W2-X-G-4 I

Gravity from RV\/ST B2, Window 3 Gr<lVitv from RWSf in B2 S<ifety V<ilve Removed in Window 3

INSUF FLOW F<iilu-e to Dklgnose Tl-ROUGH LOW 1-EAD Loss of RHR Event INJ::CTON FLO/i' in POS 6 PATH D6-CG D-F1B2W3-XHE .A-F1B2W3-X-G-4

Gravity from R\VST 1n B2, Window 4 Gravity from RWST in B2 Safety Valve Removed in Window 4

SV-W4 INSlf FLOW Faihre to Diaqnose Tl-ROUGH LOW HEAD Loss of RHR Event INJ::CTK>N FLO.V in POS 6 PATH D6-CG D-F1B2W4-XHE A-F1B2W4-X-G-4

Top Event for B2 LOSP B2 ,n Window 1 PRJIQ-PiBZ td I

°'

OURATION-R 10 RErua POS-R10 rRAC-POS10 PROB-'1/IRIO DURATION-RS REfU!l. POS-RS PR0B-'l/1R6 OR-MT PROB-'11106 POS-06

Top Event for B2 LOSP B2 1n Window 2 PRBQ-PlB2 DURATION--R 10 REfua POS-RIO FRAO-POSIO PR0B-W2R1C DURATION-RS REFUEL P0S-R6 PR0B-W2Rfl DR-MT DU~.TION-06 PROB-W2Dl! POS-06

Top Event for 82 LOSP 82 1n Window 3 PRBQ-PlB~

tJj I

00 fl'AC-POS10 PROB-'W3R1D DUl'ATION--R6 REFUEL POS-R6 PROB-'1'13RB OR-I.IT PROB-'W3DB POS-06

Top Event for B2 LOSP B2 1n Window 4 PRl1Q-P1B2 DUR,!.TIO>>-R 10 REfua POS-RIO fll'.0-POSIO PROB-W~RlD DU1l'.TION-R6 REfua P0S-R6 PROB-W~RB DR-MT DUfvl.TION-D6 PROB-W~D~ POS-06

Gravity from B2, Window 1 Gravity from RWST in B2 c::f 0

I Safety Valve Removed in Window 1

SV-W1 INSUF FLOW FailU'e to Diagnose THROUGH LOW HEAD Loss of RHR Event INJECn:>N FLOW in POS 6 PATH D6-CG D-F2B2W1-XHE .A.-F2B2W1-X-G-4

Gravity from 1n B2, Window 1 Gr<lVitv from RWST in B2 S<1fety V<1lve Removed in Window 1

sv-we INSlF FLOW F<1iltre to Dklgnose ~rntor F<1ihre THROUGH LOW HEAD Loss of RHR Event to est<Jblish INJECTON FLON in POS 6 gr<1vity feed PATH in wuidow 1 D6-CG D-F2B2W2-XHE A-F2B2W2-X-G-4

Gravity from RVVST ,n B2, Window 3 Gr<JVitv from RWSI in 82 Safety Valve Removed in Window 3

SV-W3 INSIF FLOW FailLYe to Di<lgnose Tl-ROUGH LOW HEAD Loss of RHR Event IN£CTON FLOh' in POS 6 PATH D6-CG D-F2B2W3-XHE A-F2B2W3-X-G-4

Gravity from R\VST B2, Window 4 Gravity from RWsr in B2 Safety Valve Removed in Window 4

SV-W4 INSUF FLOW Faihre to Diagnose THROUGH LOW HEAD Loss of RHR Event INJECHJN FLOW in POS 6 PATH D6-CG D-F2B2W4-XHE A-F2B2W4-X-G-4

Top Event for B2 LOSP B2 Window 1 PRBQ-PZBZ DUR6.TION-R10 RErua P0S-R10 fMC-POS10 PROB-'111R10 D1JPATKlN-R6 REFUEL OR-1..tT DUR<I.TION-06 PROB...l/1106 POS-06

Top Event for B2 LOSP B2 Window 2 ILl 102 PRJIQ-P2B2 DUR.\TION-RIO REFua POS-RIO FR.\C-POS10 PR0B-W2R1C DUAATION-R6 REFUa P05-R6 PR0B-W2RB DR-MT DURO.TIDl+-06 PROB-W2DB POS-06

Top Event for B2 LOSP B2 1n Window 3 PRIIQ-PaB2 P0S-R10 fRAC-POS10 PR0B-W3Rta DURATKJtl-R6 REFUa P0S-R6 PR0B-W3R6 DR-I.IT OUR'.TION-06 PROB-W3DB POS-06

Top Event for B2 LOSP 82 Window 4 PRBQ-P2B2 OlJR,\TION-R10 REFUEL POS-R10 FRAC-POSIO PROB-W./,RID DURATIOlf-R6 REFUEi. P0S-R6 OR-t.tT OUR'.TION-D6 PROB-W..DB POS-06

Failure of High Pressure Recirculation

,n Window 1 7:!PRS11'1 Wl1 I.FR TO OOlD LBJ Fdkro to DP°!ro,o Lon tf~rfwrt 11'.S 11'.SH.O VEIITL12 D-YSR!WL-J:KII 11'.S A-f'lR~1-X-C-J O-f'!R"'11-XHE A-f'l!Wl1-X-C-J D-f'llWl1-XHE

Failure of High Pressure Recirculation in Window 1 HI JHlll:l1H D-Jlll'ft.l-:ml

Foilure of High Pressure Recirculation in Window 2 HI H2 FSl'/12H D-P3Jl:!'!r2-XHB .L-P3R3W2-X-C-3 D-1'3El3W2-XHJ: .A.-J'3B.3W2-XHI-X vwa VBHTLl.2

.6.-1"3R3WZ-X-C-3 D-P3113W2-XHB D-P3R3\I/Z-XHH J.-P3RS'i'1Z-X~-3 IIA.SDI.G Ill* BA.Sm.a

F oilure of High Pressure Recirculation in Window 2 HI A-1'3RSW2-X-C-B D-PSJ13Wie-Xll!I vw* F9PR3WeJ'I' A-P3B31l'2-I--<:-8 D-P3113WZ-XHB D-1'3R3\Yi-Dlll A-P3R31'1Z-x-c-a RAS BA9HLC HAB

Feed and Bleed the RCS 1n RHR3, Window 1 Feed and Blsed lho RCS ;, RIR3, Window 1 Feed and Bleed Safely W,w lho RCS ;, RHR3, Removed in W"111dow POS 6 of Refueffng 1

'iN-W1 D-F3R3Wl-XBE F/>JLURE OF FEED FA'LURE OF FEED AND SPLL USING ANO SPLL USING LPI HPI F9N12H

.A-F3R3Wl-X-FL-~ .A-F3R3Wl-X-FB-4

Feed and Bleed the RCS with V failed ,n RHR3, Window 1 Feed ond Blaed the RCS in RHR3, POS 6 of Refueling Failure to Diagnose Loss of RH'l Event in POS 6 FR3W1VGO D-F3R3W1 -XHE FAILLRE OF FEED FALLRE OF FEED ANO SPLL LSING AND SPLL LSING HPI LPI FSW12H FSW12L A-F3R3W1-X-FH--9 A-F3R3W1-X-FL-9

Feed and Bleed the RCS 1n RHR3, Window 2 Feed and Beed the RCS in ~3.

Wndow 1 Feed and Bleed the RCS in R-IR3, POS 6 of Refueling

'£N-W2.

[g!"""c,tt~~

in POS 6 D-l':lR:lW2-XHB FAR.lRE CF FEED FAURE CF FEED ANO 9'LL USING AND SPILL IJSm LPI HPI A-l':lR:liV2-X-l'L4

Feed and Bleed the RCS with V foiled RHR3, Window 2 Faed ond Bleed the RCS in RHU, POS 6 of Refueling Failure to Diagnose Loss of RI-R Event in POS 6 D-F3R3W2-XHE FALi.RE OF FEED FALi.RE OF FEED A1'0 SPLL USING AND SPLL USING HPI LPI FSW12H FSW12L

.A-F3R3W2-X-FH-9 .A-F3R3W2-X-FL~

Feed and Bleed the RCS 1n RHR3, Window 3 Feed end Bleed the RCS in RHR3, Window 1 11311R3'\V3 Feed ond Beed the RCS in R-R3, POS 6 of RefueUng S>/-W3 D-113R3'\V3-Ji:HB FALLRE OF FEED FAILLRE OF FEED AND 9"11.L USING Al'll 9"LL USING HPI LP1 FSW34H FSW34L A-ll3R3'\V3-Ji:-11L-3 A-113R3W3-Ji:-11H-3

Feed and Bleed the RCS with V foiled 1n RHR3, Window 3 Feed and Bleed the RCS in RHR3, POS 6 of Refueling F3FB3W3V Failure to Diagnose Loss of RI-R Event in POS 6 D-F3B3W3-XHE FALLRE OF FEED FAILLRE OF FEED Af,[) SPLL USING ANO SPLL I..SING HPI LPI FSW34H FSW34L A-F3B3W3-X-FH-7 A-F3B3W3-X-FL-7

Feed and Bleed the RCS RHR3, Window 4 Feed and Bleed the RCS in R~J, Window 1 F3FR3W4-Feed and Bleed Safety Valve the RCS in R~J, Removed in Window POS 6 of Refueling 1 SV-W4 Failure to Diagnose Loss of lnve ntory in Window 4 D-F3R3W4--XHE FAILLRE OF FEED FAILLRE OF FEED AND SPLL USING AND SPLL USING HPI LPI

A-F3R3W4--X-FH

A-F3R3W4--X -FL FSWJ4L

Feed and Bleed the RCS with V failed RHR2B, Window 4 Feed ond Bleed the RCS in RHR3, POS 6 of Refueling Foiltre to Di<Jgnose Lo~ of Inventory in Window 4 D-F3R3W4-XHE FAURE OF FEED FALURE OF FEED At'-0 SPII.L USING Al'D SPU. USING I-Pl LPI FSW34H FSW34L A-F3R3W4-X-PH-7 A-P3R3W4-X-PL-7

Gravity from RWST RHR3, Window 1 Gravity from RWST in RHR3 POS 6 of Refuefing Safety Valve Removed in Window 1

SV-W1 INSU: FLOW Failire to Diagnose Operator Faihre THROUGH LOW HEAD Loss of RHR Event to establish IN.£CWN FLON in POS 6 grav\ty feed PATH In Wlrid<>W 1 D6-CG D-F3R3W1-XHE A-F3R3W1-X-G-5

Gravity from RWST RHR3, Window 1 Gravity from R\VST 1n RHR3 POS 6 of Refueting S<1fety V<1lve Removed in Window 1

sv-we INSLF FLOW F<1iltre to Dkignose Operntor F<1ilure Tl-ROUGH LOW HEAD Loss of RHR Event to est<Jblish INJ::CTKJN FLOW in POS 6 grnvitv feed PATH ,n window 1 D6-CG D-F3R3We-XHE A-F3R3We-X-G-5

Gravity from RWST 1n RHRj, Window 3 Gravity from RWST 1n RHR3 POS 6 of Refuefing Safety Valve Removed in Window 1

SI/-W3 INSUF FLOW THROUGH LOW HEAD INJECTK)N FLOW PATH D6-CG D-F3R3W3-XHE A-F3R3W3-X-G-4

Gravitv from RWST 1n RHR3, Window 4

/

Gr<ivity from RWST rn RHR3 POS 6 of Refuenng Safety Valve Removed in Window 1

SV-W4 INSlf" FLOW Faihre to Diagnose THROUGH LOW HEAD Loss of Inventory IN.£Cn:JN FLO/!' in Window 4 PATH D6-CG D-F3R3W4-XHE A-F3R3W4-X-G-4

Top Event for Loss of RHR- R3 1n Window 1 PRBQ-PJRHRJ OUMTION--R10 REFUO. POS-R10 flv\C-POS10 PR0B-W1R10 OUMTION-R6 P0S-R6 PR0B-W1R6 OR-I.IT OUMTION-06 POS-06

Top Event for Loss of RHR- R3 In Window 2 PRBQ-P3RHR3 OURATKJH-R IO REfUEI. POS-RIO fR-'.0-POSIO PROB--W2RIO DUAATIOH-R6 REFUEL POS-R6 PROB-W2R6 OR-MT OURATIOH-06 PROB-W206 POS-06

Top Event for Loss of RHR- R3 Window 3 PRJIQ-P3RHR3 DURATION--R10 REfUO.. POS-R10 fRAC-POSIO PROB--WJR10 POS-R6 PR0B--W3R6 DURATION-RS REFUa DR-IJT OURATION--06 PR0B--W306 POS-06

Top Event for Loss of RHR 1n Window 4 l'R81-J'lJR!IRS DUR1>J"DN-R1D REFUIL POS-R1D FAAC-POS10 PROB-W4R1l DUIWDN-R6 REFOO. POS-R6 PROB-W4R6 OR-I.IT OURATDN-06 PROB-W4D6 POS-D8

Failure of Recirculation Spray Windovv 1-cause HPR failure loss of HPSH d e to open containme t t,:I I

w 00 CON-VFC-RP-COREM Failtre to Diaqnose Loss of RHR Event in POS 6 D-F3R3W1-XHE A-F3R3W1-X-P-3 FALURE OF 1NSIC£ FAURE OF OLJTSU:

RAY RECIRCULATIO SPRAY RECRCULATIO F1LPSD F2LPSD

Failure of Recirculation Spray 'Ni ndovv 1-cause HPR failure Foiltre to Dioqnose Loss of RHR Event in POS 6 D-F3R3W1-XHE A-F3R3W1-X-P-3 FALLRE OF i'jSU: FALffiE OF OUTSU:

RAY ~CIRCULATIO SPRAY ~CRCULATIO F1LPSD F2LPSD

F a1lure of Rec1rculat1on Spray 1n Window 2-cause HPR failure ailure of Recircubtio Spray i~ Window loss of HPSH to open contoinm nt CON-VFC-RP-COREM Failllf"e to Diagnose Failure to Diagnose FALL.RE OF FEED Loss of RHR Event Loss of RHR Event AND SPLL USNG in POS 6 in POS 6 HPI FSW12H D-f3R3W2-XHE A-F3R3W2-X-P-3 D-F3R3W2-XHE A-F3R3W2-XHE-X F2LPSD

Failure of Recirculation Spray 1n Windovv 2-cause HPR failure F<JilLYe to D]<lqnose Loss of RHR Event in POS 6 D-F3R3W2-XHE A-F3R3W2-X-P-3 FALURE OF t-lSl[E FALURE OF oursa::

PRAY ~CRCULATIO PRAY ~CIRCULATIO F1LPSD F2LPSD

I Reflux Cooling 1n 1

~;:,x ac°Rt~

in POS 6 of Refueling RCS Loop, l,ola\ed

\o Cauoo FoikJl-e of Reflux Cocing IS0-W1 D-F3R3W'l-XBE A-F3R3Wl-X-SF-8 o~:~.lt~e FAJLURE OF SECCNOAAY SIDE FAJL TO QOSE BOTH POR\IS FAl.URE OF SECCNOAAY SIDE SGs 1 given R3 HEAT REMOVAL HEAT REMOVAL SSHN1 PORl/1 SS1-r.V1 A-F3R3"Kl-X-S1-8 A-F3R3Wl-X-B2-8

Reflux Cooling 1n 2

~~!::'?fH!l~

in POS 6 of Refueling Foiura lo Diogno*e RCS Loop* l..,l<,led Loo* of RHR Evenl lo Cou .. Foikro in POS 6 of Reflux Coc:ing 190-11'2 D-F3R3W2-XBE INSUF A.OW TO 3 SG FRM AT LEAST 1 AfW PUMP LSl\'23 A-F3R3W2-X-SF-fl Operolor Failure F/.l.URE OF FAA. TO Q.OSE F/>l.URE OF lo Bleed tho SECctlO/>RY SOE BOTH POR\/S SECctlD.ARY SIDE SG, 1 given R3 HEAT REMOWL HEAT REMOWL SSBl\'23 POR.11 SSBl\'23

.A-F3R3"K2-X-S1-fl .A-F3R3W2-X-S2-fl

Reflux Cooling Windo,N 3

~t:: a~~~

in POS 6 of Refueling RCS L<:<>po l,olaled lo Cau"8 Failure of Reflux Cocling 1SO--W3 D-F3R3W3-XB!:

INSUF FLOW TO 2 SG FRM AT l.EI\ST 1 AF¥/ PUMP LSN23 SR3W3G11 A-F3113W3-X-SF-7 FAA.URE OF SGS FM.. TO QOSE FAA_URE OF SGS o~~r1';.,h~* STEAM PATH TO BOTH PffiVS STEAM PATH TO SGo given R3 M'.tl STEAM HEIIDER MA.IN STEAM HtADER SSHW23 PQR./1 A-F31137f3-X-91-7 A-F3113W3-X-92-7

Reflux Cooling 1n Window 4

~~!:."a~'3 in POS 6 of Rofuol;,g Foiuro lo Diagnose RCS Loops Isolated Loos of Inventory to Couse F01b-e in Window+ of Reflux Coc:ong ISO-W+

D-F3R3W4-XBE NSUF R.OW TO 1 SG FRM AT LEAST 1 AfW PUMP SR3 403 A-F3R3W4-X-SF-7 Operala- Failure FALURE OF FM.. TO QC& FA'LURE OF to Bleed tho SECrn!:l'RY SOE BOTH PmvS SECrnD,t,RY SIDE SGs in Wndow HEAT REMOVN.. HEAT REMOVN..

+

SSIM'4 POR>/1 SSHW+

A-F3R3"K4-X-S1-7

I Gravity from RWST 1n RHR3, Window 1 Gravity from RWST in RHRJ POS 6 of Refuefing Sofety Volve Removed in Window 1

INSLf" FLOW Foiltre to Dioqnose Tl-ROUGH LOW HEAD Loss of RHR Event INJECTON FLOW in POS 6 PATH D6-CG D-F4R3W1-XHE A-F3R3W1-X-G-5

Gravity from RWST RHR3, Window 1 Gravity from RWST in RHRJ POS 6 of Refuefing Safety Valve Removed in Window 1

SV-W2 INSLf" FLOW Failtre to Diaqnose THROUGH LOW HEAD Loss of RHR Event IN.ECTON FLON in POS 6 PATH D6-CG D-F3R3W2-XHE A-F3R3W2-X-G-5

Gravity from RWST 1n RHRj, Window 3 Gravity from RWST m RHR3 POS 6 of Refuering Sofety Volve Removed in Window 1

INSUF FLOW Foiltre to Dkignose Operotor Foihre THROUGH LOW l£AD Loss of RHR Event to estoblish IN.£CTON FLON in POS 6 g-avjtv feed PATH in window 3 D6-CG D-F3R3W3-XHE A-F3R3W3-X-G-4

Gravity from RWST 1n RHR3, Window 4

./

Grovity from RWST m RHR3 POS 6 of Refuenng Safety Valve Removed in Window 1

SV-W4 INSLf" FLOW Failtre to Diagnose Tl-ROUGH LOW l-£AD Loss of Inventory INJECHJN FLOW in Window 4 PATH D6-CG D-F3R3W4-XHE A-F3R3W4-X-G-4

Top Event for Loss of RHR- R3 In Window 1 PREQ-P<lRHR3 OURATKJN-RIO REfUEl. P0S-R10 ffl6.C-POS10 PROB-W1RIO DUAATION-RS REfueI. POS-RS PROB-W1RS OR-MT DURATION-OS PROB-V/106 POS-06

Top Event for Loss of RHR- R3 ,n Window 2 PRBQ-HRHR3 OUMT10N-R IO REFUEL POS-RIO FRAC-POSIO PR0B-W2RIO DUflATl0H-R6 REFUEL POS-R6 Pll0B-W2R6 OR-NT OUMTION-06 PROB-W2D6 POS-D6

Top Event for Loss of RHR- R3 1n Window 3 PRBQ-HRHR3 OORAIDN-RIO REfUfl. POS-RIO fRAC-POSIO PROB-WJRIO P0S-R6 PROB-WJR6 0URATIOI-I-R6 REFUa DR-MT OURATION-D6 PROB-WJD6 POS-06

Top Event for Loss of RHR Window 4 FRDl-F-lRHR~

DUR",JDN-R1D REFUEL POS-R10 FRAC-POS1D PROB-W4R10 DUR/>1DN-R6 REFUEL P0S-R6 PR08-W4R6 DR-MT DURATDN-06 PR0B-W4D6 POS-06

Reflux Cooling ,n Windovv 1

~t::."ac~1 in POS 6 of Refueling RCS Loops lsololed lo Cause Failuro of Reflux Coding ISO-W1 D-F4R3Wl-XHE tlSUF FLOW TO 3 SG FRM AT LE'AST 1 AfW PUMP LS'W1 A-FU!3Wl-X-9F-8 Operator Failure FM.URE OF FA\. TO Q.OSE FM.URE OF to Bleed the SECa-lDAAY SVE BOTH PCRVS SECa-lDARY SIDE SG, 1 given R3 f£AT REMOV>L HEAT REMOV/i.

5Sfffl1 PCRv1 SSHW1 A-F4R3Wl-X-92-8

Reflux Cooling 1n Window 2

~t::.Xa~1 in POS 6 of Refueling RCS Loop* l,-,laled lo Cau'" Fa,l.n-e of Reflux Cocling c:,

I VI VI 1BO-W2 D-F4R3W2-XHE tlSUF A..OW TO 3 SG FRM AT L.fAST 1 AFW PUMP LBW23

.A-FU3W2-X-BF-8 Operator Failure F/.l.URE OF FALTO U.OSE FM.URE OF lo Bleed lho SECctl~ SIDE BOTH PCRvS SECctlD.ARI' SIDE SG, 1 given R3 HEAT REMOV!i.. HEAT REMOV.Al...

BBHW23 POR-11 BBHW23

.A-F4113W2-X-B2-8

Reflux Cooling 1n Window 3 RCS Loop* laololed lo C"" Foilure of Reflux Cocling ISO-W3 INSUF R..OW TO Operola- Foilure 2 SG FRM AT LEAST lo Feed SG* in 1 f.F\11 PUMP W-,ndcr,v 3 LSN23 A-F4.B3W3-X-SF-7 Operola- Foi'1.!re FM.URE OF SGS FM. TO Q.06E FM.URE OF SGS lo Bleed the STEAM PATH TO BOTH PCRvS STEAM PATH TO SG* given R3 M'.IN STEAM HE"ADER IAAft'l STEAM HE"ADER PORv1 SSKW23

.A-F4.B3W3-X-B 1-7 A-F<lB3W3-X-B2-7

Reflux Cooling 1n Window 4

§r:Ca~~

in POS 6 of Refuelng Fo,Jyra lo Diagnose RCS Loops lsokiled L"'s of Inventory lo Couse Failure in Window 4- of Refl'Jx Coding D-F4.R3W4.-XBE tlSUF FLOW TO 1 SG FRM AT LEAST 1 JlFW PUMP LSW4-A-F4R3W4.-X-SF-7 FAt.URE OF FAI.. TO Q06E FM..URE OF SECCNCIARY SIDE BOTH PO!NS SECCNCAAY SOE HEAT REMOWL HEAT REMOVAL SSHW4- PORv1 SSHW4-A-F4.R3W4.-X-S1-7 A-F4.R3W4.-X-S2-7

Gravity from RWST RHR3, Window 1 Gravity from RWST m RHR3 POS 6 of Refuefing Safety Volve Removed in Window 1

INSUF FLOW Failtre to D~nose THROUGH LOW 1-EAD Loss of RHR Event INJ:CnJN FLO,\/ in POS 6 PATH D6-CG D-F5R3W1-XHE A-F3R3W1-X-G-5

from RWST 1n RHR3, Window 1 Gravity from RWST in RHR3 POS 6 of Refuefing Safety Valve Removed in Window 1

sv-we INSUF FLOW Faihre to Diagnose THROUGH LOW 1-EAD Loss of RHR Event INJ::CTKJN FLCW in POS 6 PATH D6-CG D-P3R3W2-XHE A-F3R3W2-X-G-5

Gravit,; from RWST

/

1n RHRj, Window 3 Gravity from RWST in RHR3 POS 6 of Refueflng t:,::l I

°'0 - Safety Valve Removed in Window 1

Sv-W3 INSLf FLOW Failtre to Diognose THROUGH LOW 1-EAD Loss of RHR Event INJECTJJN FLON in POS 5 PATH D6-CG D-F3R3W3-XHE A-F3R3W3-X-G-4

Gravit\/ from RWST 1n RHR3, Window 4

/

Gr<JVity from RWST 1n RHR3 POS 6 of Refuefing Sofety Volve Removed in Window 1

INSI.F FLOW THROUGH LOW 1-EAD INJECTON FLOW PATH D6-CG D-F3R3W4-XHE A-F3R3W4-X-G-4

Top Event for Loss of RHR- R3 Window 1 PRIIQ-PBRHR3 DURATION-RIO REfLJa P0S-R10 fRAC-POSIO Pfl08...l/11R10 DURATION-RS REfLJa P0S-R6 PR08--WIR6 DR-tJT DUMTION-D6 PROB...l/1106 POS-D6

Top Event for Loss of RHR- R3 ,n Window 2 PHBQ-PBHHHJ OURATIOIHl10 REfUfl POS-R10 FRAC-POS10 PROB-W2RIO DURATION-RS REFUEL POS-R6 PROB-W2R6 OR-MT OUR4TION-06 PR0B-W206 POS-D6

Top Event for Loss of RHR- R3 1n Window 3 PRBQ-PBRHR3 DUAATION-RIO REfUfl. POS-RIO fR4C-P0510 PR0B-W3RIO POS-R6 OOR4TIOI-I-R6 REflJEL OR-MT 00R4TIOH-D6 PR0B-W306 POS-06

Top Event for Loss of RHR Window 4 J'!IIII-J'5RBR3 Duratfan af Fr*~Y Df POS 10 ot R>fuallng Rofumg Outog,,

DUR"1'DN-R10 RfFUIL POS-R10 FRAC-POS10 DUR/'JDN-R6 REFUEL POS-R6 PR0B-W4R6 DR-Mr DURATDN-06 PR0B-W4D6 POS-06

Reflux Cooling 1n Window 1 Foilure to Diagnose RCS Loops lsolotod L08s of RHR Evon\ to C"" Foilure in POS 5 of Reflux Cocling

~

I O'I O'I ISO-W1 D-F6R3W1-XBE tlSUF FLOW TO 15 SG FRM AT LEAST 11'FW PUMP LSW1 A-F6R3W1-X-SF-8 Opera\,;,- Failure FM.URE OF FM.. TO QOSE FM-URE OF to Bleed the SEC~CIARY SOE BOTH P(R\/S SEC~CIARY SIDE SGs 1 given R3 HEAT REMOV/>L HEAT REMOVAL SS1-W1 SSHW1 A-F6R3°K1-X-S1-8 A-F6R3W1-X-S2-8

Reflux Cooling 2

~~x 0Co~~

in POS 6 of Refueling RCS Loop, loolo\ed lo Cou,e Foilure of Reflux Cocling t::c I

0\

....J D-F5R3W2-XHE tlSUF FLOW TO 3 SG FRM AT LEAST 1 AFW PUMP LBl\'23 A-F6R3W2-X-BF-8 Operolc:,- Foilure FALURE OF FALTO QOSE lo Bleed lhe SECOND/ffi' SIDE BOTH POO/S SGs 1 !t,en R3 1£AT REMOVAL SSHl\'23 PORv1 SSBW23 A-F5R3"K2-X-S1-8 A-F6R3W2-X-B2-8

Reflux Cooling 1n Windo,N 3

~~~ac~1 in POS 6 of Refueling RCS Loops lsol<lled lo Cau"" Foiluro of Reflux Cooling ISO--W3 t,.j I D-F6H3W3-XBE 0\

00 INS\JF FLfJII T0 Oporalt<" Foiluro 2 SG FRM AT LEAST lo Food SG* i, 1 AF¥/ PUMP Wndow 3 LS,'/23 SR3W3G11 A-F6H3W3-X-9F-7 Oporal<<" Foik.-o FAA.URE OF SGS FAA.. TO QOSE FAA..URE OF SGS Qi>eral<<" fai<Jre lo Bleed the STEAM PATH TO BOTH PORVS STEAM PATH TO to estabish SGs rj,,en R3 ~ STEAM HfADER MIIIN STEA.M HEADER reflux after SSIW23 PORv1 SSHW23 A-FGH:J"K3-X-9l-7 A-F6H3W3-X-92-7

Reflux Cooling 1n Window 4 Foluro to Diagnose RCS Loops lsoloted Loos of Inventory to <Auso Foiillro in Window '4- of Roflux Cooing IS0-W'4-D-F6R3W4-XBE INSUF FLOW TO 1 SG FRM AT LEAST 1 />FW PUMP LSW'4- 9113 4'G4 A-F6R31n-X-SF-7 Operator Foiluro FM.URE OF FAIL TO Q.OSE FAI..URE OF to 01<,ed tho SECONDAAY SIDE BOTH PORVS SECOND,l>ffi' SIDE SGs in Wind""' HEAT REMOY.AL HEAT REMOWL SSHN+ SSHW'4-A-F6R3"K4-X-S1-7 A-F5R3W4-X-S2-7

Failure of High Pressure Recirculation

,n Vvindow 1 F&STEl'/.I F&SPU.

LPR LPR CM 1114, t,::1 A-MWl-X!lll-04 D-MWl-Xllll I

-.J 0

H1 Hl PB3Yll V\111 VENT VEIITL12

Failure of High Pressure Recirculation In VVindow 1 A-Jl'll l-XIIE-0-9 D-IWll'l-Xllll H1 H2 PBffll PflJ/11 W/1 LPfl TO VENT CQ.D LEG H'.SK.G VENTL12 PRJ/l"ll ifll,,S

~

fl'.SfLG

Failure of High Pressure Recirculation in Window 2 H1 PR3'1/2 FSW12H D-lUWZ-XBJ: .A.-Rll'ffl-:lftl!-C--4 Il-1Uw2-na: .l.-lU'WZ-XBt:-X PRSW2 D-lU.W2-XBt:

HAS JIABIILG HAS JIASBLG

Failure of High Pressure Recirculation

,n Window 2 HI HZ PR31'/2 FSW12H D-RiW2-Xllll A-R~W2-XII£-C-9 D-IHW2-XHB A-11:,wz-xm:-x PllSW2 Vl'/2 VENTL!2 D-R'-W2-XDB D-JUW2-Xll!I A.-A.4.W2-XH!-C-9 HAS JIASHLO HAB JIAIIHLO

Feed and Bleed the RCS RHR4, Window 1 Feed and Bleed lho i~.!:. rR4-,

Feed and Bleed Safely Vavo lho RCS i1 RHR4-, Removed i1 W"ndow W"ndow 1 1 td I

i F"t';, t~/li~**

Event in Vi!ndow D-R4Wl-XBE FM.URE OF FEED FM.URE OF FEED AfO SPlL USING AND SPLL USING LP1 H'I F9N12L F9H12H A-R4Wl-XBE-FL-5 A-R4Wl-XBE-FB-6

Feed and Bleed the RCS with V Foiled RHR4, Window 1 Faed and Bleed the RCS in Rt-R4, Window 1 Foiltn to Diagnose Loss of RI-R4 Event in Window 1

D-R4-WJ-XHE FALLRE OF FEED FALLRE OF FEED AND SPLL LS l'JG AND SPLL LSl'lG HPI LPI FSW12H FSW12L A-R4-WJ-XHE-FH-JO A-R4-WJ-XHE-FL-JO

Feed and Bleed the RCS 1n RHR4, Window 2 Feed and Bleed the RCS in RHR4, Window 1 Feed and Bleed Safety Valve the RCS in RHR4, Removed in Window Window 2 2

~I

-.l 0\

Faihre to Diagnose Loss of Rt-R4 Event in Window 2

D-R4-W2-XBE FALL.RE OF FEED FAURE OF FEED Al>O SPLL USl-lG Al-0 SPLL USNG HPI LPI FSW12L A-R4-W2-XBE-FR-0 A-R4-W2-XBE-FL--O

Feed and Bleed the RCS with V Failed 1n RHR4, Window 2 Feed and Bleed the RCS in R~4, Window 2 Failure to Diagnose Loss of RI-R 4 Event in Window 2

D-R4-W2-XHE FAURE Of FEED FAILLRE OF FEED Al-0 SPLL 1.61-lG AND SPLL l.61NG t-PI LPI FSW12H FSW12L A-R4-W2-XHE-FH-JO A-R4-W2-XHE-FL-JO

Feed and Bleed the RCS RHRS, Window 3 Feed ond Beed the RCS in FHl5, W-ndow 3 Feed ond Beed So' etv Valve the RCS in ~5. Removecf in Wirdow W-ndow 3 1 Sl/-W3 Fcih.re to Dicq,ose Loss of ~ 5 Event in Wndow 3 Operator Failu-e FALL.RE Cf" FEED FALL.RE OF FEED Operator fcilure to use HHSI in Al'O SPLL USING Al'O SPLL USl'JG o~ use LHSI in f ~ end ~1 I-Pl LPI F~ed end ~I FSW34L A-R.j,W3-:UIB-l'H-4 A-R.j,W:!-:UIB-l'L-.j,

Feed and Bleed the RCS with V Foiled 1n RHR4, Window 3 Feed and Bleed the RCS in R~4, Window 3 Faihre to Diagnose oss of RI-R-4 Even in Window 3 D-R4-W3-XIIE FAURE OF FEED FAURE Cf" FEED Af,O SPLL UStlG Ai'O SPLL USI-JG I-Pl LPI FSW34H FSW34L A-R4-W3-XBE-FH-8 A-R4-W3-XHE-FL-8

Feed and Bleed the RCS ,n RHR4, Window 4 Feed and Bleed the RCS in RHR4, Window 4 Feed and Bleed Safety Valve the RCS in RHR4, Re moved in Window Window 4 4 t:Jj I

00 0

Failure to Diagnose Loss of lnvento,y in Window 4 D-R4-W4--XHE FAL~E OF FEED FAIL~ OF FEED At-0 SPLL USNG AND SPLL USING 1-f'I LPI FSW34L FSW34H A-R4-W 4--XHE-FH -0 A-R4-W4--XHE-FL-O

Gravity from RWST ,n RHR4, Window 1 GrCNity from RWsr ,n RHR4, Wirdow 1 Safety Valve Removed in Window 1

SV-W1 Failure to Diagnose INSUF FLOW Loss of RHR4 THROUGH LON HEAD Event in Window INJECTION FLOW 1 PATH D6-CG D-R4-W1-XHE A-R4-W1-XHE-G-6

Gravity from RWST 1n RHR4, Window 2 Gr<Nity from RWST in RHR4 Window 2 t:tlI 00 N

Safety Valve Removed in Window 2

SI/-W2 Failt.re to Diagnose INSlF FLOW Loss of RHR4 Tl-ROUGH LOW f-EAD Event in Window IN-.ECWN FLOW 2 PATH D6-CG D-R4W2-XHE A-R4W2-XHE-G-6

Gravity from RWST

/

RHRS, Window 3 Gr<ivity from RWST in RHR4, Window J c::J I

00 w

S<lfety Valve Removed in Window 1

Sv-WJ INSl,f FLOW Failtre to Diagnose Operator Faih.re THROUGH LOW HEAD oss of RHR-4 Even to estabfish IMA::CTJJN FL' in Window J g-avjty feed PATH in w1ridow J 06-CG D-R4W3-XHE A-R4W3-XHE-G-5

Gravity from RWST 1n RHR4, Window 4 Gr<1Vity from RWfil in RHR4, Window 4 Safety Valve Removed in Window 4

INSLf" FLOW Failu-e to Diagnos,e Tl-ROUGH LOW f£AD Loss of Inventory IN..ECHJN FLCM' in Window 4 PATH D6-CG D-R4W4-XHE A-R4W4-XHE-G-5

Top Event for Loss of RHR- R4 Window 1 c:i I

00 Vt IJJR,\TION-R10 REfUU. POS-RIO flWJ-POSIO PROB-WIRIO P0S-R6 Pfl0B-WIR6 OURATION-R6 REfUll. DR-MT !Utb.TIOIHJ6 PR08-WID6 POS-06

Top Event for Loss of RHR- R4 1n 'vVindow 2 PREQ-RHR~

t,:j I

00

°'

IMl'.TION-RIO REflJEJ.. POS-RIO ffl.\0-POSIO PROB-W2RIO P05-R6 PROB-W2R6 0Ulv\TKJN-R6 DR-I.IT ClJR6.TION-D6 PROll-W206 POS-06

Top Event for Loss of RHR-4 1n Window 3 t:,::J I

00

....J R£fUa POS-RIO FRAC-POS.i PROO-WJR.i POS-R6 PR08-W3R6 OUR6,TIOl~R6 DR-MT DURATION-OS PR08-W306 POS-06

Top Event for Loss of RHR-4 Window 4 J'IIUI-RBM

~

00 00 DurDtiin ar POS 1l of Alrudng 0utDg11 OUR'1l'DN-R10 REFUIL POS-R10 FRo\C-POS1l PROO-W4R10 DUIWDN-RB REFua POS-RB PR08-W4RB DR-I.IT OUIWDN-OB PROB-W4DB POS-OB

Fa,lure of Rec1rculat1on Spray 1n Window 1 due to HPR failure

<1iltre of Recircukltio Spr<1y in Window 1

loss of f-PSH

<l e to open confoirme t CON-VFC-RP-COREM

~r<1tor F9ihxe F<1iltre to Di(lg_nose to Est<lbish Loss of RHR4 Recrcukltion Event in Window in W1 1 A-R4W1-XHE-P-4 D-R4W1-XHE F2LPSD F1LPSO

Failure of Recirculation Spray 1n Windovv 1-cause HPR failure tt1 I

IO 0

Foiltre to Diagnose Loss of RHR Event in POS 6 D-R4W1-XHE .A-R4W1-XHE-P-4 F1LPSD F2LPSD

Failure of Recirculation Spray in Window 2-cause HPR failure ailure of Recircuoti Sirq,, i 2 Wirdow loss of HPSH d e to open cortdnme t COl-'vf"c-RP-COREM Operator Failure to Estcblish Recircuotion Fat:,, t~f~se Event in Wndow Fa,t:s t~f D i ~

Event in Wndow FALLRE OF FEED AND 9'!.L USl'lG HPI in W2 2 2 FSW12H A-R-'W2-ll:HB-P--4. D-R.iW2-ll:HB D-R-'W2-ll:HB A-R-iW2-ll:HB-ll:

F2LP9J Ft.F'SD

Failure of Recirculation Spray 1n Windovv 2-cause HPR failure t,j I

I.O N

Failtre to Diagnose O~ator F9ilure Loss of RHR Event to EstdJish in POS 6 Recrculation in W1 D-R4W2-XHE A-R4W2-XHE-P-4 FALlJRE OF OUTS[

RAY RECRCULATIO F1LPSD F2LPSD

Restore RHR given RHR4 Window 1 Restore RHR Given RHR4 in Window 1

Failure to Restore Fanure to Diagnose Loss of RHR-4 RHR, given RHR4 Loss of RHR4 P0Ss 3-13 in Window 1 Event in Window 1

W3-S A-R4W1-XHE-R-4 D-R4W1-XHE

r Restore RHR given RHR4 Window 2 Restore RHR Given RHR4 in Window 2 F<iili.re to Restore F<iili.re to Dkignose Loss of RHR RHR, given RHR4 Loss of RHR4 POSs 3-13 in Window 2 Event in Window 2

W3-S A-R4W2-XHE-R-4 D-R4W2-XHE

Restore RHR given RHR4 In Window 3 Restore Rm Given RHR4- in window 3 tdI Foih.re to Restore Foih.re to Diognose Loss of RHR ~ RHR, given Rm4- Loss of RHR Event in Window POSs 3-13 in Win<low 3 3

WJ-S A-R4W3-XHE-R-4 D-R4W3-XHE

Restore RHR given RHR4 1n Window 4 Restore RHR Given RHR4 in Window 4

~I

\0 0\

Failure to Restore Failure to Diag'lose Loss of RHR RHR, .given RHR4 Loss of Inventory POSs 3-13 in Window 4 in Window 4 W3-S A-R4-W"4--XHE-R-5 D-R4-W4--XHE

Reflux Cooling 1n window 1 ISO-W1 D-R<I.WI-XBE tlSUF FLOW TO 3 SG FRM AT LfAST 1 />F#I PUMP LSW1 A-RSN1->>iE-SF-9 POR,11 A-R4Wl-XBE-B1-9 A-R4Wl-XHE-S2-9

Reflux Cooling windovv 2

~~o~"i in Wirmw 2 F~'! ~ ~** RCS Loop,, loololed lo eou .. Foikro Evonl in Vi!ndow of Roflwc Coding bj I

\0 00 D-R4W2-XBE INSUF R..OW TO Operola- Foikro 2 SG FRM AT LEAST lo Food SG* i, 1 N'V/ PUMP Window 2-R5 LSN23 A-R4W2-XBE-SF~

Oi,erola- FoilJro F/ll.JJRE OF SGS FM. TO QO'SE Fl>l..URE OF SGS lo !hod lho STEAM PATH TO BOTH PffiVS STEAM PATH TO SGo 1 Given RHR~ tAAl'I STEAM HE'ADER IAArl STEAM HE'ADER SSttN23 POR',11 SSHl',"23 A-R4W2-XBE-S1-9 A-R4W2-XBE-S2~

Reflux Cooling In windovv 4 FaiOJ"' lo Diagnooo RCS Loopo look,led Loo* of RHR+ Even l lo eou .. Failure in Window 3 of Rol~x Coorng ISO--W3 t.d I

\0

\0 Oporalor Fa,l..-e lo Food SGo i1 W-.-.dow 3 A-R4W3-XD!:-SF~

Oporalor Faikro F,'I.URE OF SGS FM.. TO Q.OSE F,'1.URE OF SGS lo Blood lho STEAM PATH TO BOTH l'aNS STEAM PATH TO SG* given R+ Mlltl STEAM HE"ADER MA.ti STEAM HEADER PQR./1 SSW.-23 A-R4W3-XD!:-S1-8 A-R4W3-XBE-S2~

Reflux Cooling ,n windovv 4

~~~Q~,

in Window +

Faiure lo Diagnose RCS Loop* 180la\ed Losa of lnvenlcxy lo CO\Joo Faikn in Window+ of Rofkix Cocing t,:I

-, D-R4.lH-XBE

~

0 0 NSUF FLOW TO 1 SG FRM AT LEAST 1 AFW PUMP A-R4.W4.-XBE-SF-8 Opera\a- Faikiro Ff.l.URE OF FM. TO QOSE lo Bleed tho SECCWlAffi' SOE BOTH Pm\lS SG~ i, W"ndow f£AT REMOW.l P00/1 SSH/I+

A-R4.W4.-XBE-S1--8 A-R4.W4.-XBE-S2-8

Sof ety Valves not Removed 1n Window 1 Safety Volves Not Remove in Window 1 POS 6 of a Drained Maintenance Outage t,:I POS-R10 POS-06 I

0

...... POS 6 of a Refusing Outage POS-R6 Pressurizer Safety Volves Removed in W1R6 PZR-s-J-REMOVEOW1

Safety Valves not Removed 1n Window 2 Safety V<llves Not Remove in Window 1 POS 10 of <l POS 6 of <l Dr<lined Refuefing Outage M<linteoonoe Outage tp 0

N P0S-R10 POS-06 OS 6 of <l Refueli Outage P0S-R6 Presstrizer S<lfety V<llves Removed in W'R6 PZR-SV-REMOVEDW2

Safety Valves not Removed

,n Window 3 Safety Valves Not Remove in Window 3 POS 6 of a Drained Maintenanoe Outage POS-D6 6 of a Refueli POS 10 of a Outage Refueling Out<ige POS-R6 POS-R10 Pressurizer PressL¥izer Safety Valves Safety Valves Removed in WJR6 Removea in W3R6 PZR-SV--REM0\1£DWJ PZR-SV-REMO'vEDWJ

Safety Valves not Removed ,n Window 4 Safety Valves Not Remove in Window 3 POS 6 of a Drained Maintenance Outage POS-06 POS 6 of a Refusing POS '(] of a Outage Refueling Outage POS--R6 POS-R10 Pressurizer Pressurizer Safety Valves Safety Valves Removei! in W4R6 Removai! in W4R6 PZR-SV-REMCJI/EDW4 PZR-SV-REMCNEDW4

Gravity from R'NST B2, Window 1 Gravity from RWST in 82 0:,

0 I

Ul Safety Valve Removed in Window 1

SV-W1 INSIF FLOW Faihre to Diognose Operator Failure Tl-ROUGH LOW 1-EAD Loss of RHR Event to establish IN.£CTON FLO/ii in POS 6 grovitv feed PATH In WlrlOOW 1 D6-CG D-F7B2W1-XHE A-F7B2W1-X-G-4

Gravity from R\VST 1n B2, Window 2 Grovity from RWsr in B2 Sofety Volve Removed in Window 2

SV-W2 INSUF FLOW FoilLre to Di<Jgnose Tl-ROUGH LOW f£AD Loss of RHR Event IN..ECTON FLON in POS 6 PATH D6-CG D-F7B2W2-XHE A-P7B2W2-X-G-4

Gravity from RVVST 1n B2, Window 3 Gr<lVity from RWST in 82 S<ifety V<ilve Removed in Window 3

SV-W3 INSUF FLOW F<iilu-e to Di<Jgnose Operntor F<iilure T~OUGH LOW HEAD Loss of RHR Event to est<Jblish INJECTKJN FLOW in POS 6 gravjty feed PATH rn wrridow 3 D6-CG D-F7B~W3-XHE A-F7B~W3-X-G-4

Gravity from R\VST B2, Window 4 Grovity from RWST in 82 o:I 0

I 00 Sofety Volve Removed in Window 4

SV-W4 INSlF FLOW Foilll'e to Dklgnose T~OUGH LOW 1-EAD Loss of RHR Event INJ:CTKJN FLOW in POS 6 PATH D6-CG D-F7B2W4-XHE A-F7B2W4-X-G-4

Top Event for B2 LOSP B2 Window 1 c;

0 I

\0 PRIIQ-P?B2 DUAATION-RS REFUEL POS-RS PR08...\/11R6 OR-fJT OUR'.TION-06 PROB...\/1106 POS-06

Top Event for B2 LOSP B2 Window 2 IL! 102 PRBQ-P7B2 DURAmH-RIO POS-RIO Ff\A.C-POSIO PR0B-W2R1D DURATIJH-RS REFUEL POS-RS PR0B-W2RB OIH.IT IJUR'.TIOH-D6 PROB-W2DB POS-D6

Top Event for 82 LOSP 82 1n Window 3 PRllQ-P?B2 DURATI0!-1-RIO REfUB. POS-RIO f1WJ-P0S10 Pll0B-'ll3R1D REfUEI. POS-RS Pll0B-'ll3RB DR-t.!T DlJR.O.TION-D6 Pll0B-'W3DB POS-D6

Top Event for B2 LOSP B2 1n Window 4 PRJIQ-P7Ba POS-RIO fPAC-POSIO PROB-114-Rln DUMTIO~RIO REF\JD..

DR-MT DUR'.TIOO--D6 PROB-W4-D8 POS-06 REFUa POS-R6 PR0B-W4-R8

Appendix C Flow Exceedance Frequency Curves

C-1

Exceedance Frequency Turb. Bldg. - SW Events Frequency [/yr]

1 E-03 ~,,,- - -.................,...........,~..........-.---._..,....._-.........---,-----,-~,........,.....-..........,..-----,.---_,............,-r-....-,_.,..,

1 E-05 ~~~~~~~--=--'-'~~~~-'-'--'--~----'---'----'---'----'---L--1....1 1E+03 1 E+04.

.w [gpm]

1E+05 1E+06

Exceedan Aux. Bldg.

Frequency Frequency [/yr]

1 E-0 2 ~:;;:p::::::;:i~~::p::::;:;::::;;;::p:;:;:~~g;:::::::~~FPRq::i:::::;;;::;::q;::::::q:::q:++=+=R+====+==i=t=+++m

-- ******::: .. ,:::::le::::*::::::::::::::::::::::::***

. *.:: :=;= ,::

lj?,§U/,,,: ::.:I::::::::::: ****** :::. . .... :,::.:.,:::*. , .. ,.I , *..

1 E-03 '. :*. ~.. . .\rt~::::: \._*: \.:*- *-_*.\ !\ !t 1 = i,<,,,.,1\i::H,,,.i'

.:::*: :::::~**:::.~:; ;***

=******

-==-=*,:***=**=-* =i:*-=

:::::::;:::::.;~.:::::::: .. **: ... ..** .: .*

=: :, -*-**** **= :::. : = .. =* *==**I: : * :.*:* ., *** ?~,;.: *== ,, *

_-,:,>*

- - - - ,::::.. ... : : :=:k**:::*:::::1:

- ...... ,::: **=.. _:::*

=::::::* :: .. ,.. ,=:.:=-:

- y1*=='*:***::::': . . .. : : ~ . : .. : . ... * ...... . -*.

1

__:+/-=cSE:12:t:EEIEE:Siil>saa****:E**:f:2$ ***s**1*:,.E**:a:2**'s**s**==***::*3==*e*m**a,E*==*==*:*_-Er-...=e'~t:r--..::E~=E::l=l*_*.S:iS=EEllllS 1

1 E-04 ~*S53.

1 1 1

. :. . \** --....

!\: ::: . I': : I/ >*.* * *

F. . . : ?I 1* **** : . ' ** 1 * /: *** *: .: .. - ,

FYI'* *::;: * ---,,-,: ...

1::: .. *::: :.

I -!:' :**- .- .. .

.- _ !=,,::**,:::. :'- :__

1 E-05 l:=L .. T:.1:.I ; * *: *[ J:, ***=* ::, *. -- . : . I,. ::

1E+OO 1E+01 1E+02 1E+03 1E+04 1E+05 Flow [gpm]

Appendix D Dominant Cutsets and Basic Event Importance

D-1

Family->FLOOD/WINDOW Partition Cut Set Report Mincut Upper Bound-> 1.704E-005 End State ->CD This Partition-> 1.704E-005 Cut % % Cut No. Total Set Frequency Cut Sets 1 12.5 12.5 2.135E-006 UNITY, FREQ-F1B2, PROB-W2D6, DR-MT, DURATION-D6 2 23.2 10.7 1.836E-006 UNITY, FREQ-F1B2, PROB-W3D6, DR-MT, DURATION-D6 3 31. 9 8.6 1.468E-006 UNITY, REFUEL, FREQ-F1B2, /PZR-SV-REMOVEDW4, PR0B-W4R10, FRAC-POSlO, DURATION-RlO 4 38.8 6.9 1.179E-006 UNITY, REFUEL, DURATION-R6, FREQ-F1B2,

/PZR-SV-REMOVEDW2, PR0B-W2R6 5 44.5 5.7 9.817E-007 UNITY, REFUEL, /PZR-SV-REMOVEDW4, PROB-W4R10, FREQ-F5RHR3, FRAC-POS10, DURATION-RlO 6 49.5 4.9 . 8.431E-007 UNITY, REFUEL, DURATION-R6, FREQ-F1B2, PZR-SV-REMOVEDW3, PROB-W3R6 7 53.6 4.1 7.019E-007 UNITY, REFUEL, /PZR-SV-REMOVEDW4, PROB-W4R10, FREQ-F4RHR3, FRAC-POS10, DURATION-R10 8 57.0 3.3 5.728E-007 UNITY, FREQ-F1B2, PR0B-W1D6, DR-MT, DURATION-D6 9 60.3 3.3 5.638E-007 UNITY, REFUEL, DURATION-R6, PZR-SV-REMOVEDW3, PR0B-W3R6, FREQ-F5RHR3 10 63.5 3.2 5.517E-007 UNITY, LOOPIS0LATED2R6, REFUEL, DURATION-R6,

/PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-F5RHR3 11 66.5 2.9 5.070E-007 UNITY, PR0B-W2D6, FREQ-F2B2, DR-MT, DURATION-D6 12 69.0 2.5 4.361E-007 UNITY, PR0B-W3D6, FREQ-F2B2, DR-MT, DURATION-D6 13 71.5 2 .4 4.207E-007 UNITY, REFUEL, PZR-SV-REMOVEDW4, PR0B-W4R10, FREQ-F5RHR3, FRAC-POS10, DURATION-RlO 14 73.9 2.3 4.031E-007 UNITY, REFUEL, DURATION-R6, PZR-SV-REMOVEDW3, PR0B-W3R6, FREQ-F4RHR3 15 76.2 2.3 3.945E-007 UNITY, LOOPIS0LATED2R6, REFUEL, DURATION-R6,

/PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-F4RHR3 16 78.4 2.2 3.831E-007 UNITY, PR0B-W1D6, FREQ-F5RHR3, DR-MT, DURATION-D6 17 80.5 2.0 3.525E-007 UNITY, FREQ-F1B2, PR0B-W4D6, DR-MT, DURATION-D6 18 82.5 2.0 3.486E-007 UNITY, REFUEL, /PZR-SV-REMOVEDW4, PR0B-W4R10, FREQ-F2B2, FRAC-POS10, DURATION-RlO 19 84.3 1. 7 3.00SE-007 UNITY, REFUEL, PZR-SV-REMOVEDW4, PROB-N4R10, FREQ-F4RHR3, FRAC-POS10, DURATION-RlO 20 85.9 1.6 2.799E-007 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-F2B2 21 87.6 1.6 2.739E-007 UNITY, PR0B-W1D6, FREQ-F4RHR3, DR-MT, DURATION-D6 22 88.7 1.1 2.002E-007 UNITY, REFUEL, DURATION-R6, PZR-SV-REMOVEDW3, PR0B-W3R6, FREQ-F2B2 23 89.5 0.8 1.360E-007 UNITY, PROB-W1D6, FREQ-F2B2, DR-MT, DURATION-D6 24 90.1 0.5 9.368E-008 UNITY, REFUEL, DURATION-R6, FREQ-F1B2,

/PZR-SV-REMOVEDW3, PR0B-W3R6 25 90.6 0.4 8.372E-008 UNITY, PROB-W4D6, FREQ-F2B2, DR-MT, DURATION-D6 26 91. 0 0.4 7.074E-008 UNITY, FREQ-F3RHR3, PR0B-W1D6, A-F3R3Wl-X-FL-9, DR-MT, DURATION-D6 27 91.4 0.3 6.265E-008 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW3, PR0B-W3R6, FREQ-F5RHR3 28 91.7 0.3 6.203E-008 UNITY, REFUEL, DURATION-R6, FREQ-F1B2, 1993/11/24 09:23:41 page 1

D-3

Family->FLOOD/WINDOW Partition Cut Set Report Mincut Upper Bound-> l.704E-005 End State ->CD This Partition-> l.704E-005 Cut % % Cut No. Total Set Frequency Cut Sets PZR-SV-REMOVEDW2, PROB-W2R6 29 92.0 0.3 5.438E-008 UNITY, REFUEL, DURATION-R6, FREQ-F1B2,

/PZR-SV-REMOVEDW4, PROB-W4R6 30 92.3 0.3 5.363E-008 UNITY, LOOPISOLATED2R6, REFUEL, FREQ-F3RHR3, DURATION-R6, /PZR-SV-REMOVEDW2, PROB-W2R6, LPR-CCF-PG-SUMP2 31 92.6 ,Q.2 4.987E-008 UNITY, LOOPISOLATED2R6, REFUEL, FREQ-F3RHR3, DURATION-R6, /PZR-SV-REMOVEDW2, PROB-W2R6, A-F3R3W2-X-FL-9 32 92.9 0.2 4.479E-008 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW3, PROB-W3R6, FREQ-F4RHR3 33 93.1 0.2 4.148E-008 UNITY, REFUEL, DURATION-R6, PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-FSRHR3 34 93.4 0.2 4.00SE-008 UNITY, REFUEL, FREQ-F3RHR3, /PZR-SV-REMOVEDW4; PROB-W4R10, FRAC-POS10, A-F3R3W4-X-FL-7, DURATION-R10 35 93.6 0.2 3.845E-008 UNITY, REFUEL, DURATION-R6, FREQ-F1B2, PROB-W1R6, /PZR-SV-REMOVEDWl 36 93.8 0.2 3.637E-008 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW4, PROB-W4R6, FREQ-FSRHR3 37 94.0 0.1 3.283E-008 UNITY, SGB-DRAINED-R, PR0B-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6 38 94.2 0.1 3.283E-008 UNITY, SGA-DRAINED-R, PR0B-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6 39 94.4 0.1 3.069E-008 UNITY, REFUEL, FREQ-F1B2, PZR-SV-REMOVEDW3, PR0B-W3R10, FRAC-POS10, DURATION-R10 40 94.6 0.1 3.006E-008 UNITY, PR0B-W2D6, FREQ-FSRHR3, DR-MT, A-F5R3W2-X-S1-8, A-F5R3W2-X-S2-8, DURATION-D6 41 94.7 0.1 2.966E-008 UNITY, REFUEL, DURATION-R6, PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-F4RHR3 42 94.9 0.1 2.824E-008 UNITY, SGB-DRAINED-R, PR0B-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6 43 95.1 0.1 2.824E-008 UNITY, SGA-DRAINED-R, PROB-W3D6, FREQ-FSRHR3,.

DR-MT, DURATION-D6 44 95.2 0.1 2.600E-008 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW4, PROB-W4R6, FREQ-F4RHR3 45 95.4 0.1 2.586E-008 UNITY, PR0B-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6, A-FSR3W3-X-S1-7, A-F5R3W3-X-S2-7 46 95.5 0.1 2.347E-008 UNITY, SGB-DRAINED-R, PR0B-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 47 95.6 0.1 2.347E-008 UNITY, SGA-DRAINED-R, PROB-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 48 95.8 0.1 2.225~-008 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW3, PR0B-W3R6, FREQ-F2B2 49 95.9 0.1 2.052E-008 UNITY, REFUEL, PZR-SV-REMOVEDW3, PR0B-W3R10, FREQ-FSRHR3, FRAC-POS10, DURATION-RlO so 96.0 0.1 2.028E-008 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6, 1993/11/24 09:23:41 page 2 1).4

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> l.704E-005 This Partition-> l.704E-005 Cut % % Cut No. Total Set Frequency Cut Sets PZR-SV-REMOVEDW3, PR0B-W3R6, A-F3R3W3-X-FL-3 51 96.1 0.1 2. 019E--008 UNITY, SGB-DRAINED-R, PR0B-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6 52 96.3 0.1 2.019E-008 UNITY, SGA-DRAINED-R, PR0B-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6 53 96.4 0.1 l.950E-008 UNITY, REFUEL, A-F1B2W4-X-G-4, FREQ-FlB2, PZR-SV-REMOVEDW4, PR0B-W4R10, FRAC-POS10, DURATION-RlO 54 96.5 0.1 l.660E-008 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F5RHR3, A-F5R3W2-X-S1-8, A-F5R3W2-X-S2-8 55 96.6 0.1 l.638E-008 UNITY, FREQ-F3RHR3, PROB-WlD6, DR-MT, DURATION-D6, A-F3R3Wl-X-C-8 56 96.7 0.0 l.570E-008 UNITY, PR0B-W2D6, FREQ-F5RHR3, DR-MT, A-F5R3W2-X-SF-8, DURATION-D6 57 96.7 0.0 l.559E-008 UNITY, REFUEL, DURATION-R6, PZR-SV-REMOVEDW4, PR0B-W4R6, FREQ-F5RHR3 58 96.8 0.0 l.473E-008 UNITY, REFUEL, DURATION-R6, PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F2B2 59 96.9 0.0 l.467E-008 UNITY, REFUEL, PZR-SV-REMOVEDW3, PROB-W3Rl0, FREQ-F4RHR3, FRAC-POS10, DURATION-RlO 60 97.0 0.0 l.351E-008 UNITY, PR0B-W3D6, FREQ-F5RHR3, DR-MT, DURATION-D6, A-F5R3W3-X-SF-7 61 97.1 0.0 l.291E-008 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW4, PROB-W4R6, FREQ-F2B2 62 97.1 0.0 l.122E-008 UNITY, PR0B-W2D6, FREQ-F7B2, DR-MT, DURATION-D6 63 97. 2 0.0 l.114E-008 UNITY, REFUEL, DURATION-R6, PZR-SV-REMOVEDW4, PROB-W4R6, FREQ-F4RHR3 64 97. 3 0.0 l.071E-008 UNITY, MSS-AOV-FC-lOlB, MSS-NRV-MA-lOlB, PR0B-W2D6, FREQ-F5RHR3, DR-MT, DURATI0N-D6 65 97.3 0.0 l.071E-008 UNITY, MSS-AOV-FC-lOlA, MSS-NRV-MA-lOlA, PROB-W2D6, FREQ-F5RHR3, DR-MT, DURATION-D6 66 97.4 0.0 9.650E-009 UNITY, PROB-W3D6, FREQ-F7B2, DR-MT, DURATION-D6 67 97.4 0.0 9.369E-009 UNITY, PROB-W2D6, FREQ-F4RHR3, A-F4R3W2-X-S1-8, A-F4R3W2-X-S2-8, DR-MT, DURATION-D6 68 97.5 0.0 9.209E-009 UNITY, MSS-AOV-FC-lOlB, MSS-NRV-MA-101B, PROB-W3D6, FREQ-F5RHR3, DR-MT, DURATION-D6 69 97.6 0.0 9.209E-009 UNITY, MSS-AOV-FC-101A, MSS-NRV-MA-lOlA, PR0B-W3D6, FREQ-F5RHR3, DR-MT, DURATI0N-D6 70 97.6 0.0 9.136E-009 UNITY, PROB-W2D6, FREQ-F5RHR3, DR-MT, DURATION-D6, D-F5R3W2-XHE 71 97.7 0.0 9.133E-009 UNITY, REFUEL, DURATION-R6, PR0B-W1R6,

/PZR-SV-REMOVEDWl, FREQ-F2B2 72 97. 7 0.0 8.BBOE-009 UNITY, PROB-W2D6, FREQ-F4RHR3, A-F4R3W2-X-SF-8, DR-MT, DURATION-D6 73 97.8 o*. o 8.670E-009 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F5RHR3, A-F5R3W2-X-SF-8 1993/11:/24 09:23:41 page 3 D-5

Family->FLOOD/WINDOW Partition Cut Set Report Mincut Upper Bound-> l.704E-005 Cut % % Cut End State ->CD This Partition-> 1.704E-005 No. Total Set Frequency Cut Sets 74 97.8 0.0 8.059E-009 UNITY, PROB-W3D6, FREQ-F4RHR3, A-F4R3W3-X-Sl-7, A-F4R3W3-X-S2-7, DR-MT, DURATION-D6 75 97.9 0.0 7.858E-009 UNITY, PROB-W3D6, FREQ-F5RHR3, DR-MT, DURATION-D6, D-F5R3W3-XHE 76 97.9 0.0 7. 716E-009 UNITY, REFUEL, /PZR-SV-REMOVEDW4, PROB-W4Rl0, FREQ-F7B2, FRAC-POSlO, DURATION-RlO 77 97. 9 0.0 7.715E-009 UNITY, REFUEL, DURATION-R6, PROB-W1R6, LOOPISOLATED1R6, /PZR-SV-REMOVEDWl, FREQ-FSRHR3 78 98.0 0.0 7.655E-009 UNITY, MSS-AOV-FC-lOlB, MSS-NRV-MA-lOlB, PROB-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 79 98.0 0.0 7.655E-009 UNITY, MSS-AOV-FC-101A, MSS-NRV-MA-101A, PROB-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 80 98.1 0.0 7.637E-009 UNITY, PROB-W3D6, FREQ-F4RHR3, A-F4R3W3-X-SF-7, DR-MT, DURATION-D6 81 98.1 0.0 7.289E-009 UNITY, REFUEL, PZR-SV-REMOVEDW3, PROB-W3R10, FREQ-F2B2, FRAC-POS10, DURATION-RlO 82 98.2 0.0 6.584E-009 UNITY, MSS-AOV-FC-101B, MSS-NRV-MA-101B, PROB-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6 83 98.2 0.0 6.584E-009 UNITY, MSS-AOV-FC-101A, MSS-NRV-MA-lOlA, PROB-W3D6, FREQ-F4RHR3, DR-MT, DURATI0N-D6 84 98.2 0.0 6.543E-009 UNITY, REFUEL, FREQ-F3RHR3, PZR-SV-REMOVEDW4,

PROB-W4Rl0, FRAC-POS10, A-F3R3W4-X-FL-4, DURATION-RlO 85 98.3 0.0 6.542E-009 UNITY, REFUEL, SGS-DRAINED-R, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-FSRHR3 86 98.3 0.0 6.435E-009 UNITY, LOOPIS0LATED2R6, REFUEL, FREQ-F3RHR3, DURATION-R6, /PZR-SV-REMOVEDW2, PROB-W2R6, A-F3R3W2-X-C-8 87 98.4 0.0 6.195E-009 UNITY, REFUEL, DURATI0N-R6, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F7B2 88 98.4 0.0 S.678E-009 UNITY, REFUEL, PZR-SV-REMOVEDW4, PROB-W4Rl0, A-F2B2W4-X-G-4, FREQ-F2B2, FRAC-POS10 ,*

DURATION-RlO 89 98.4 0.0 5.663E-009 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW3, PROB-W3R6, A-F3R3W3-X-FL-7 90 98.4 0.0 S.516E-009 UNITY, REFUEL, DURATION-R6, PROB-WlR6, LOOPIS0LATED1R6, /PZR-SV-REMOVEDWl, FREQ-F4RHR3 91 98.5 0.0 S.173E-009 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3, A-F4R3W2-X-S1-8, A-F4R3W2-X-S2-8 92 98.5 0.0 5.044E-009 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-FSRHR3, D-FSR3W2-XHE 93 98.5 0.0 4.903E-009 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3, A-F4R3W2-X-SF-8 94 98. 6 0.0 4.741E-009 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, PROB-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6 95 98.6 0.0 4.677E-009 UNITY, REFUEL, SGS-DRAINED-R, DURATION-R6, 1993/11/24 09:23:41 page 4 D-6

Family->FLOOD/WINDOW Partition Cut Set Report Mincut Upper Bound-> l.704E-005 Cut % % Cut End State ->CD This Partition-> l.704E-005 No. Total Set Frequency Cut Sets

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3 96 98.6 0.0 4.078E-009 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, PROB-W3D6, FREQ-F5RHR3, DR-MT, DURATION-D6 97 98.6 0.0 4.032E-009 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6, PZR-SV-REMOVEDW2, PROB-W2R6, LPR-CCF-PG-SUMP2 98 98.7 0.0 3.723E-009 UNITY, FREQ-F3RHR3, PROB-W1D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMPl 99 98.7 0.0 3.569E-009 UNITY, MSS-NRV-MA-101B, MSS-AOV-MA-lOlB, PROB-W2D6, FREQ-F5RHR3, DR-MT, DURATION-D6 100 98.7 0.0 3.569E-009 UNITY, MSS-NRV-MA-101A, MSS-AOV-MA-lOlA, PROB-W2D6, FREQ-F5RHR3, DR-MT, DURATION-D6 101 98.7 0.0 3.410E-009 UNITY, REFUEL, FREQ-FlB2, /PZR-SV-REMOVEDW3, PROB-W3R10, FRAC-POS10, DURATION-R10 102 98.7 0.0 3.390E-009 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, PROB-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 103 98.8 0.0 3.191E-009 UNITY, FREQ-F3RHR3, SGB-DRAINED-R, PROB-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 104 98.8 0.0 3.191E-009 UNITY, FREQ-F3RHR3, SGA-DRAINED-R, PROB-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 105 98.8 0.0 3.070E-009 UNITY, MSS-NRV-MA-101B, MSS-AOV-MA-101B, PROB-W3D6, FREQ-F5RHR3, DR-MT, DURATION-D6 106 98.8 0.0 3.070E-009 UNITY, MSS-NRV-MA-lOlA, MSS-AOV-MA-lOlA, PROB-W3D6, FREQ-F5RHR3, DR-MT, DURATION-D6 107 98.8 0.0 3.011E-009 UNITY, PROB-WlD6, FREQ-F7B2, DR-MT, DURATION-D6 108 98.9 0.0 2.968E-009 UNITY, FREQ-F3RHR3, SGB-DRAINED-R, PROB-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6.

109 98.9 0.0 2.968E-009 UNITY, FREQ-F3RHR3, SGA-DRAINED-R, PROB-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 110 98.9 0.0 2.916E-009 UNITY, REFUEL, DURATION-R6, PROB-W1R6,

/PZR-SV-REMOVEDW1, FREQ-FSRHR3, A-F5R3Wl-X-S1-8, A-F5R3Wl-X-S2-8 111 98.9 0.0 2.916E-009 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, PROB-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6 112 98.9 0.0 2.863E-009 UNITY, REFUEL, LPI-MDP-FS-SI1B, FREQ-F3RHR3,

/PZR-SV-REMOVEDW4, PROB-W4R10, FRAC-POSlO, DURATION-R10 113 98.9 0.0 2.789E-009 UNITY, LOOPIS0LATED2R6, REFUEL, LPR-MOV-FT-1862B, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6 114 99.0 0.0 2.784E-009 UNITY, MSS-AOV-FC-101B, SSHR-AOV-XHE-105, PROB-W2D6, FREQ-F5RHR3, DR-MT, DURATION-D6 115 99.0 0.0 2.784E-009 UNITY, MSS-AOV-FC-101A, SSHR-AOV-XHE-105, PR0B-W2D6, FREQ-F5RHR3, DR-MT, DURATION-D6 116 99.0 0.0 2.618E-009 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F5RHR3 117 99.0 0.0 2.552E-009 UNITY, MSS-NRV-MA-101B, MSS-AOV-MA-lOlB, 1993/11/24 09:23:41 page 5 D-7

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> l.704E-005 This Partition-> l.704E-005 Cut % % Cut No. Total Set Frequency Cut Sets PR0B-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 118 99.0 0.0 2.552E-009 UNITY, MSS-NRV-MA-lOlA, MSS-AOV-MA-101A, PROB-W2D6, FREQ-F4~R3, DR-MT, DURATION-D6 119 99.0 0.0 2.394E-009 UNITY, MSS-AOV-FC-lOlB, SSHR-AOV-XHE-105, PROB-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6 120 99.0 0.0 2.394E-009 UNITY, MSS-AOV-FC-lOlA, SSHR-AOV-XHE-105, PROB-W3D6, FREQ-F5RHR3, DR-MT, DURATION-D6 121 99.1 0.0 2.280E-009 UNITY, REFUEL, /PZR-SV-REMOVEDW3, PROB-W3Rl0, FREQ-F5RHR3, FRAC-POS10, DURATION-RlO 122 99.1 0.0 2.195E-009 UNITY, MSS-NRV-MA-lOlB, MSS-AOV-MA-lOlB, PROB-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6 123 99.1 0.0 2.195E-009 UNITY, MSS-NRV-MA-lOlA, MSS-AOV-MA-lOlA, PROB-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6 124 99.1 0.0 2.141E-009 UNITY, MSS-AOV-FC-lOlB, CIR-COND-UNAVLBL, PROB-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6 125 99.1 0.0 2.141E-009 UNITY, MSS-AOV-FC-lOlA, CIR-COND-UNAVLBL, PROB-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6 126 99.1 0.0 l.990E-009 UNITY, MSS-AOV-FC-lOlB, SSHR-AOV-XHE-105, PROB-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 127 99.1 0.0 l.990E-009 UNITY, MSS-AOV-FC-lOlA, SSHR-AOV-XHE-105, PROB-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 128 99.1 0.0 l.936E-009 UNITY, LPR-MOV-FT-1862B, FREQ-F3RHR3, PROB-WlD6 DR-MT, DURATION-D6 129 99.2 0.0 1. 887E-009 UNITY, REFUEL, LPR-MOV-FT-1890B, FREQ-FlB2, PZR-SV-REMOVEDW4, PROB-W4R10, FRAC-POS10, DURATION-RlO 130 99.2 0.0 l.872E-009 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3 131 99.2 0.0 l.853E-009 UNITY, PR0B-W4D6, FREQ-F7B2, DR-MT, DURATION-D6 132 99.2 0.0 1.842E-009 UNITY, MSS-AOV-FC-101B, CIR-COND-UNAVLBL, PR0B-W3D6, FREQ-F5RHR3, DR-MT, DURATION-D6 133 99.2 0.0 1. 842E-009 UNITY, MSS-AOV-FC-101A, CIR-COND-UNAVLBL, PROB-W3D6, FREQ-F5RHR3, DR-MT, DURATION-D6 134 99.2 0.0 1. 768E-009 UNITY, PR0B-W4D6, FREQ-F5RHR3, DR-MT, DURATION-D6, A-F5R3W4-X-SF-7 135 99.2 0.0 1.712E-009 UNITY, MSS-AOV-FC-101B, SSHR-AOV-XHE-105, PROB-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6 136 99.2 0.0 1. 712E-009 UNITY, MSS-AOV-FC-lOlA, SSHR-AOV-XHE-105, PROB-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6 137 99.2 0.0 1. 644E-009 UNITY, REFUEL, LPI-MDP-FS-SilB, FREQ-F3RHR3, DURATION-R6, PZR-SV-REMOVEDW3, PR0B-W3R6 138 99.2 0.0 1. 630E-009 UNITY, REFUEL, /PZR-SV-REMOVEDW3, PR0B-W3R10, FREQ-F4RHR3, FRAC-POS10, DURATION-RlO 139 99.3 0.0 1.609E-009 UNITY, L00PIS0LATED2R6, REFUEL, LPR-MOV-FT-1860B, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW2, PR0B-W2R6 1993/11/24 09:23:41 page 6 D-8

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> l.704E-005 This Partition-> 1.704E-005 Cut % % Cut No. Total Set Frequency Cut Sets 140 99.3 a.a 1.609E-009 UNITY, LOOPISOLATED2R6, REFUEL, LPI-MDP-FS-SI1B, FREQ-F3RHR3, DURATION-R6, /PZR-SV-REMOVEDW2, PR0B-W2R6 141 99.3 a.a l.531E-009 UNITY, MSS-AOV-FC-101B, CIR-COND-UNAVLBL, PR0B-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 142 99.3 a.a l.531E-009 UNITY, MSS-AOV-FC-lOlA, CIR-COND-UNAVLBL, PR0B-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 143 99.3 a.a l.505E-009 UNITY, AFW-MDP-MA-FW3A, AFW-MDP-MA-FW3B, PR0B-W2D6, FREQ-F5RHR3, DR-MT, DURATION-D6 144 99.3 0.0 l.492E-009 UNITY, REFUEL, FREQ-F3RHR3, DURATI0N-R6, PZR-SV-REMOVEDW2, PR0B-W2R6, A-F3R3W2-X-FL-4 145 99.3 a.a l.485E-009 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW4, PR0B-W4R6, A-F3R3W4-X-FL-7 146 99.3 0.0 l.428E-009 UNITY, PROB-W2D6, SGS-DRAINED-CSD, FREQ-F5RHR3, DR-MT, DURATION-D6 147 99.3 0.0 1. 428E-009 UNITY, AFW-CKV-00-CV142, PR0B-W2D6, FREQ,-F5RHR3, DR-MT, DURATION-D6 148 99.3 0.0 l.425E-009 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6, PR0B-W1R6, LOOPIS0LATED1R6, /PZR-SV-REMOVEDWl, A-F3R3Wl-X-FL-9 49 99.3 0.0 1.317E-009 UNITY, MSS-AOV-FC-101B, CIR-COND-UNAVLBL, PR0B-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6

150 99.4 0.0 1.317E-009 UNITY, MSS-AOV-FC-lOlA, CIR-COND-~AVLBL, PROB-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6 151 99.4 a.a l.295E-009 UNITY, AFW-MDP-MA-FW3A, AFW-MDP-MA-FW3B, PR0B-W3D6, FREQ-F5RHR3, DR-MT, DURATION-D6 152 99.4 0.0 l.274E-009 UNITY, FREQ-F3RHR3, PR0B-W2D6, A-F3R3W2-X-S1-8, A-F3R3W2-X-S2-8, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 153 99.4 0.0 l.228E-009 UNITY, PR0B-W3D6, SGS-DRAINED-CSD, FREQ-F5RHR3, DR-MT, DURATION-D6 154 99.4 0.0 1.228E-009 UNITY, AFW-CKV-00-CV142, PR0B-W3D6, FREQ-F5RHR3, DR-MT, DURATION-D6 155 99.4 0.0 l.227E-009 UNITY, REFUEL, LPI-MDP-FS-SI1B, FREQ-F3RHR3, PZR-SV-REMOVEDW4, PR0B-W4R10, FRAC-POS10, DURATION-RlO 156 99.4 0.0 1.185E-009 UNITY, FREQ-F3*RHR3, PR0B-W2D6, A-F3R3W2-X-FL-9, A-F3R3W2-X-S1-8, A-F3R3W2-X-S2-8, DR-MT, DURATION-D6 157 99.4 0.0 1.138E-009 UNITY, FREQ-F3RHR3, PR0B-W2D6, A-F3R3W2-X-SF-8, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 158 99.4 0.0 l.117E-009 UNITY, LPI-MDP-FS-SI1B, FREQ-F3RHR3, PR0B-W1D6, DR-MT, DURATION-D6 159 99.4 0.0 l.117E-009 UNITY, LPR-MOV-FT-1860B, FREQ-F3RHR3, PR0B-W1D6, DR-MT, DURATION-D6 160 99.4 0.0 1.076E-009 UNITY, AFW-MDP-MA-FW3A, AFW-MDP-MA-FW3B, PR0B-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 1993/11/24 09:23:41 page 7 D-9

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> 1.704E-005 This Partition-> l.704E-005 Cut % % Cut No. Total Set Frequency Cut Sets 161 99.4 0.0 1.073E-009 UNITY, LOOPISOLATED2R6, REFUEL, PPS-MOV-FT-1536, FREQ-F3RHR3, DURATION-R6, PORV-PATH-CLSD,

/PZR-SV-REMOVEDW2, PROB-W2R6 162 99.4 o.o 1.058E-009 UNITY, FREQ-F3RHR3, PROB-W2D6, A-F3R3W2-X-FL-9, A-F3R3W2-X-SF-8, DR-MT, DURATION-D6 163 99.4 0.0 1.041E-009 UNITY, MSS-AOV-FC-lOlB, FREQ-F3RHR3, MSS-NRV-MA-lOlB, PROB-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 164 99.4 0.0 1.041E-009 UNITY, MSS-AOV-FC-101A, FREQ-F3RHR3, MSS-NRV-MA-lOlA, PROB-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 165 99.5 0.0 1.021E-009 UNITY, PROB-W2D6, SGS-DRAINED-CSD, FREQ-F4RHR3, DR-MT, DURATION-D6 166 99.5 0.0 1.021E-009 UNITY, AFW-CKV-00-CV142, PROB-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 167 99.5 0.0 1.016E-009 UNITY, FREQ-F3RHR3, SGB-DRAINED-R, PROB-W3D6, A-F3R3W3-X-FL-3, DR-MT, DURATION-D6 168 99.5 0.0 1.016E-009 UNITY, FREQ-F3RHR3, SGA-DRAINED-R, PROB-W3D6, A-F3R3W3-X-FL-3, DR-MT, DURATION-D6 169 99.5 0.0 9.678E-010 UNITY, MSS-AOV-FC-101B, FREQ-F3RHR3, MSS-NRV-MA-lOlB, PROB-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 170 99.5 0.0 9.678E-010 UNITY, MSS-AOV-FC-101A, FREQ-F3RHR3, MSS-NRV-MA-lOlA, PROB-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 1 71 99. 5 0.0 9.279E-010 UNITY, SSHR-AOV-XHE-105, MSS-AOV-MA-lOlB, PROB-W2D6, FREQ-F5RHR3, DR-MT, DURATION-D6 172 99.5 0.0 9.279E-010 UNITY, SSHR-AOV-XHE-105, MSS-AOV-MA-lOlA, PROB-W2D6, FREQ-F5RHR3, DR-MT, DURATION-D6 173 99.5 0.0 9.270E-010 UNITY, PROB-W4D6, FREQ-F4RHR3, DR-MT, A-F4R3W4-X-SF-7, DURATION-D6 174 99.5 0.0 9.266E-010 UNITY, REFUEL, DURATION-R6, PROB-WlR6,

/PZR-SV-REMOVEDWl, FREQ-F4RHR3, A-F4R3Wl-X-S1-8, A-F4R3Wl-X-S2-8 175 99.5 0.0 9.256E-010 UNITY, AFW-MDP-MA-FW3A, AFW-MDP-MA-FW3B, PROB-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6 176 99.5 0.0 8.778E-010 UNITY, PROB-W3D6, SGS-DRAINED-CSD, FREQ-F4RHR3, DR-MT, DURATION-D6 177 99.5 0.0 8.778E-010 UNITY, AFW-CKV-00-CV142, PROB-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6 178 99.5 0.0 8.603E-010 UNITY, FREQ-F3RHR3, PROB-W2D6, D-F3R3W2-XHE, DR-MT, DURATION-D6 179 99.5 0.0 8.557E-010 UNITY, PROB-W4D6, FREQ-F5RHR3, DR-MT, DURATION-D6, A-F5R3W4-X-S1-7, A-F5R3W4-X-S2-7 180 99.5 0.0 8.311E-010 UNITY, AFW-MDP-MA-FW3A, AFW-MDP-MA-FW3B, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F5RHR3 1993/11/24 09:23:41 page 8 D-10

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> 1.704E-005 This Partition-> 1.704E-005 Cut % % Cut No. Total Set Frequency Cut Sets 181 99.5 0.0 8.099E-010 UNITY, REFUEL, /PZR-SV-REMOVEDW3, PR0B-W3R10, FREQ-F2B2, FRAC-POS10, DURATION-RlO 182 99.5 0.0 7.981E-010 UNITY, SSHR-AOV-XHE-105, MSS-AOV-MA-101B, PR0B-W3D6, FREQ-F5RHR3, DR-MT, DURATION-D6 183 99.5 0.0 7.981E-010 UNITY, SSHR-AOV-XHE-105, MSS-AOV-MA-101A, PR0B-W3D6, FREQ-F5RHR3, DR-MT, DURATION-D6 184 99.6 0.0 7.882E-010 UNITY, AFW-CKV-00-CV142, REFUEL, DURATION-R6,

/PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-FSRHR3 185 99.6 0.0 7.830E-010 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, PR0B-W4D6, FREQ-F5RHR3, DR-MT, DURATION-D6 186 99.6 0.0 7.550E-010 UNITY, REFUEL, D-F1B2W4-XHE, FREQ-F1B2, PZR-SV-REMOVEDW4, PR0B-W4Rl0, FRAC-POS10, DURATION-RlO l87 99.6 0.0 7.447E-010 UNITY, PPS-MOV-FT-1536, FREQ-F3RHR3, PORV-PATH-CLSD, PR0B-W1D6, DR-MT, DURATION-D6 188 99.6 0.0 7.399E-010 UNITY, FREQ-F3RHR3, PR0B-W3D6, D-F3R3W3-XHE, DR-MT, DURATION-D6 189 99.6 0.0 7.381E-010 UNITY, REFUEL, FREQ-F3RHR3, PZR-SV-REMOVEDW3, PR0B-W3R10, A-F3R3W3-X-FL-3, FRAC-POS10, DURATION-RlO 90 99.6 0.0 7.225E-010 UNITY, REFUEL, DURATION-R6, A-F1B2W4-X-G-4, FREQ-F1B2, PZR-SV-REMOVEDW4, PR0B-W4R6 91 99.6 0.0 7.138E-010 UNITY, CIR-COND-UNAVLBL, MSS-AOV-MA-101B, PR0B-W2D6, FREQ-F5RHR3, DR-MT, DURATION-D6 192 99.6 0.0 7.13SE-010 UNITY, CIR-COND-UNAVLBL, MSS-AOV-MA-101A, PR0B-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6 193 99.6 0.0 7.033E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW2, PR0B-W2R6, A-F3R3W2-X-S1-8, A-F3R3W2-X-S2-8, LPR-CCF-PG-SUMP2 194 99.6 0.0 6.703E-010 UNITY, CON-VFC-RP-COREM, LOOPISOLATED2R6, REFUEL, FREQ-F3RHR3, DURATION-R6, OSR-TRA-MA, ISR-TRA-MA, /PZR-SV-REMOVEDW2, PR0B-W2R6 195 99.6 o.o 6.634E-010 UNITY, SSHR-AOV-XHE-105, MSS-AOV-MA-101B, PR0B-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 196 99.6 0.0 6.634E-010 UNITY, SSHR-AOV-XHE-105, MSS-AOV-MA-101A, PR0B-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 197 99.6 0.0 6.540E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATI0N-R6,

/PZR-SV-REMOVEDW2, PR0B-W2R6, A-F3R3W2-X-FL-9*,

A-F3R3W2-X-S1-8, A-F3R3W2-X-S2-8 198 99.6 0.0 6.424E-010 UNITY, MSS-AOV-FC-101B, MSS-NRV-FT-101B, PR0B-W2D6, FREQ-F5RHR3, DR-MT, DURATION-D6 199 99.6 0.0 6.424E-010 UNITY, MSS-AOV-FC-lOlA, MSS-NRV-FT-lOlA, PR0B-W2D6, FREQ-F5RHR3, DR-MT, DURATION-D6 200 99.6 0.0 6.359E-010 UNITY, REFUEL, SGS-DRAINED-R, FREQ-F3RHR3, DURATION-R6, /PZR-SV-REMOVEDW2, PR0B-W2R6, LPR-CCF-PG-SUMP2 201 99.6 0.0 6.328E-010 UNITY, PR0B-W2D6, FREQ-F4RHR3, D-F4R3W2-XHE, 1993/11/24 09:2.3:41 page 9 D-11

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> 1.704E-005 This Partition-> 1.704E-005 Cut % % Cut No. Total Set Frequency Cut Sets DR-MT, DURATION-D6 202 99.6 0.0 6.282E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6, A-F3R3W2-X-SF-8, LPR-CCF-PG-SUMP2 203 99.6 0.0 6.139E-010 UNITY, CIR-COND-UNAVLBL, MSS-AOV-MA-101B, PR0B-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6 204 99.6 0.0 6.139E-010 UNITY, CIR-COND-UNAVLBL, MSS-AOV-MA-101A, PR0B-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6 205* 99.6 0.0 5.957E-010 UNITY, FREQ-F3RHR3, PR0B-W1D6, D-F3R3Wl-XHE, DR-MT, DURATION-D6 206 99.6 0.0 5.942E-010 UNITY, AFW-MDP-MA-FW3A, AFW-MDP-MA-FW3B, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-F4RHR3 207 99.6 0.0 5.915E-010 UNITY, REFUEL, DURATION-R6, SGC-DRAINED-R, PR0B-W1R6, /PZR-SV-REMOVEDWl, FREQ-FSRHR3*

208 99.6 0.0 5.915E-010 UNITY, REFUEL, DURATION-R6, SGB-DRAINED-R, PR0B-W1R6, /PZR-SV-REMOVEDWl, FREQ-FSRHR3 209 99.6 0.0 S.915E-010 UNITY, REFUEL, DURATION-R6, SGA-DRAINED-R, PR0B-W1R6, /PZR-SV-REMOVEDWl, FREQ-FSRHR3 210 99.7 0.0 S.914E-010 UNITY, REFUEL, SGS-DRAINED-R, FREQ-F3RHR3, DURATION-R6, /PZR-SV-REMOVEDW2, PR0B-W2R6,

A-F3R3W2-X-FL-9 211 99.7 0.0 5.842E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW2, PR0B-W2R6, A-F3R3W2-X-FL-9, A-F3R3W2-X-SF-8 212 99.7 0.0 5.706E-010 UNITY, SSHR-AOV-XHE-105, MSS-AOV-MA-10.lB, PR0B-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6 213 99.7 0.0 5.706E-010 UNITY, SSHR-AOV-XHE-105, MSS-AOV-MA-lOlA, PR0B-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6 214 99.7 0.0 S.635E-010 UNITY, AFW-CKV-OO-CV142, REFUEL, DURATION-R6,

/PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-F4RHR3 215 99.7 0.0 5.598E-010 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, PR0B-W4D6, FREQ-F4RHR3, DR-MT, DURATION-D6 216 99.7 0.0 5.525E-010 UNITY, MSS-AOV-FC-101B, MSS-NRV-FT-lOlB, PR0B-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6 217 99.7 0.0 5.525E-010 UNITY, MSS-AOV-FC-lOlA, MSS-NRV-FT-101A, PR0B-W3D6, FREQ'-FSRHR3, DR-MT, DURATION-D6 218 99.7 0.0 5.482E-010 UNITY, SAS-CPS-FR-1SAC1, IAS-CPS-FS-IAC-1, PR0B-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6 219 99.7 0.0 5.482E-010 UNITY, SAS-CPS-FR-2SAC1, IAS-CPS-FS-IAC-1, PR0B-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6 220 99.7 0.0 S.443E-010 UNITY, PROB-W3D6, FREQ-F4RHR3, D-F4R3W3-XHE, DR-MT, DURATION-D6 221 99.7 0.0 5.103E-010 UNITY, CIR-COND-UNAVLBL, MSS-AOV-MA-101B, PROB-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 222 99.7 0.0 5.103E-010 UNITY, CIR-COND-UNAVLBL, MSS-AOV-MA-101A, PR0B-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 1993/11/24 09:23:41 page 10 D-12

Partition Cut Set Report Farnily->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> 1.704E-005 This Partition-> 1~704E-005 Cut % % Cut No. Total Set Frequency Cut Sets 223 99.7 0.0 4.996E-010 UNITY, AFW-CCF-FS-FW3AB, PR0B-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6 224 99.7 0.0 4.924E-010 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW3, PROB-W3R6, FREQ-F7B2 225 99.7 0.0 4.839E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6, PZR-SV-REMOVEDW2, PR0B-W2R6, A-F3R3W2-X-C-3 226 99.7 0.0 4.750E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6, D-F3R3W2-XHE 227 99.7 0.0 4.715E-010 UNITY, SAS-CPS-FR-1SAC1, IAS-CPS-FS-IAC-1, PROB-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6 228 99.7 0.0 4.715E-010 UNITY, SAS-CPS-FR-2SAC1, IAS-CPS-FS-IAC-1, PROB-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6 229 99.7 0.0 4.654E-010 UNITY, CON-VFC-RP-COREM, FREQ-F3RHR3, OSR-TRA-MA, ISR-TRA-MA, PROB-WlD6, DR-MT, DURATION-D6 230 99.7 o.o 4. 608E-010 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B.,

FREQ-F3RHR3, PROB-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 231 99.7 0.0 4.593E-010 UNITY, MSS-AOV-FC-101B, MSS-NRV-FT-101B, PROB-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 232 99.7 0.0 4.593E-010 UNITY, MSS-AOV-FC-101A, MSS-NRV-FT-101A, PR0B-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 233 99.7 0.0 4.483E-010 UNITY, REFUEL, LPR-MOV-FT-1890B, PZR-SV-REMOVEDW4, PR0B-W4R10, FREQ-F2B2, FRAC-POS10, DURATION-RlO 234 99.7 0.0 4.389E-010 UNITY, CIR-COND-UNAVLBL, MSS-AOV-MA-101B, PROB-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6 235 99.7 0.0 4.389E-010 UNITY, CIR-COND-UNAVLBL, MSS-AOV-MA-101A, PR0B-W3D6, FREQ-F4RHR3, DR-MT, DURATION~D6 236 99.7 0.0 4.372E-010 UNITY, REFUEL, DURATION-R6, PR0B-W1R6,

/PZR-SV-REMOVEDWl, FREQ-FSRHR3, A-FSR3Wl-X-SF-8 237 99.7 0.0 4.297E-010 UNITY, AFW-CCF-FS-FW3AB, PR0B-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6 238 99.7 0.0 4.294E-010 UNITY, REFUEL, LPI-CCF-FS-SilAB, FREQ-F3RHR3,

/PZR-SV-REMOVEDW4, PROB-W4R10, FRAC-POS10, DURATION-RlO 239 99.7 0.0 4.286E-010 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, FREQ-F3RHR3, PROB-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 240 99.7 0.0 4.229E-010 UNITY, REFUEL, DURATION-R6, SGC-DRAINED-R, PR0B-W1R6, /PZR-SV-REMOVEDWl, FREQ-F4RHR3 241 99.7 0.0 4.229E-010 UNITY, REFUEL, DURATION-R6, SGB-DRAINED-R, PROB-W1R6, /PZR-SV-REMOVEDWl, FREQ-F4RHR3 242 99.7 0.0 4.229E-010 UNITY, REFUEL, DURATI0N-R6, SGA-DRAINED-R, PR0B-W1R6, /PZR-SV-REMOVEDWl, FREQ-F4RHR3 243 99.7 0.0 4.170E-010 UNITY, REFUEL, DURATION-R6, SGB-DRAINED-R, SGC-DRAINED-R, /PZR-SV-REMOVEDW2, PR0B-W2R6, 1993/11/24 09:23:41 page 11 D-13

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> 1.704E-005 This Partition-> 1.704E-005 cut % % cut No. Total Set Frequency Cut Sets FREQ-F5RHR3 244 99.7 0.0 4.170E-010 UNITY, REFUEL, DURATION-R6, SGA-DRAINED-R, SGC-DRAINED-R, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F5RHR3 245 99.8 0.0 4.170E-010 UNITY, REFUEL, DURATION-R6, SGA-DRAINED-R, SGB-DRAINED-R, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F5RHR3 246 99.8 o.o 4.152E-010 UNITY, REFUEL, LPR-MOV-PG-1890B, FREQ-FlB2, PZR-SV-REMOVEDW4, PR0B-W4R10, FRAC-POS10, DURATION-Rio 247 99.8 0.0 4.054E-010 UNITY, FREQ-F3RHR3, PROB-W3D6, A-F3R3W3-X-FL-3, A-F3R3W3-X-S1-7, A-F3R3W3-X-S2-7, DR-MT, DURATION-D6 248 99.8 0.0 3.950E-010 UNITY, MSS-AOV-FC-101B, MSS-NRV-FT-101B, PROB-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6 249 99.8 0.0 3.950E-010 UNITY, MSS-AOV-FC-101A, MSS-NRV-FT-lOlA, PR0B-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6 250 99.8 0.0 3.919E-010 UNITY, SAS-CPS-FR-1SAC1, IAS-CPS-FS-IAC-1, PROB-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 251 99.8 0.0 3.919E-010 UNITY, SAS-CPS-FR-2SAC1, IAS-CPS-FS-IAC-1, PROB-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 252 99.8 0.0 3.884E-010 UNITY, REFUEL, DURATION-R6, FREQ-FlB2, PROB-WlR6, PZR-SV-REMOVEDWl 253 99.8 0.0 3.830E-010 UNITY, FREQ-F3RHR3, SGB-DRAINED-R, PROB-W2D6, DR-MT, DURATION-D6, A-F3R3W2-X-C-8 254 99.8 0.0 3.830E-010 UNITY, FREQ-F3RHR3, SGA-DRAINED-R, PR0B-W2D6, DR-MT, DURATION-D6, A-F3R3W2-X-C-8 255 99.8 0.0 3.767E-010 UNITY, REFUEL, DURATION-R6, PZR-SV-REMOVEDW3, PROB-W3R6, FREQ-F7B2, A-F7B2W3-X-G-4 256 99.8 0.0 3.712E-010 UNITY, AFW-MOV-CC-151, PROB-W2D6, FREQ-F5RHR3, DR-MT, DURATION-D6 257 99.8 0.0 3.621E-010 UNITY, FREQ-F3RHR3, PR0B-W3D6, A-F3R3W3-X-FL-3, A-F3R3W3-X-SF-7, DR-MT, DURATION-D6 258 99.8 0.0 3.572E-010 UNITY, AFW-CCF-FS-FW3AB, PROB-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 259 99.8 0.0 3*. 494E-010 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3, D-F4R3W2~XHE 260 99.8 0.0 3.469E-010 UNITY, FREQ-F3RHR3, MSS-NRV-MA-101B, MSS-AOV-MA-lOlB, PROB-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 261 99.8 0.0 3.469E-010 UNITY, FREQ-F3RHR3, MSS-NRV-MA-101A, MSS-AOV-MA-lOlA, PROB-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 262 99.8 0.0 3.398E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6, PZR-SV-REMOVEDW3, PROB-W3R6, D-F3R3W3-XHE 263 99.8 0.0 3.371E-010 UNITY, SAS-CPS-FR-1SAC1, IAS-CPS-FS-IAC-1, PR0B-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6 1993/U/24 09:23:41 page 12 D-14

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> 1.704E-005 This Partition-> 1.704E-005 Cut % % Cut No. Total Set Frequency Cut Sets 264 99.8 0.0 3.371E-010 UNITY, SAS-CPS-FR-2SAC1, IAS-CPS-FS-IAC-1, PROB-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6 265 99.8 0.0 3.343E-010 UNITY, REFUEL, DURATION-R6, PROB-W1R6,

/PZR-SV-REMOVEDWl, FREQ-F5RHR3, D-F5R3Wl-XHE 266 99.8 0.0 3.312E-010 UNITY, MSS-AOV-FC-lOlB, FREQ-F3RHR3, MSS-NRV-MA-101B, PROB-W3D6, A-F3R3W3-X-FL-3, DR-MT, DURATI0N-D6 267 99.8 0.0 3.312E-010 UNITY, MSS-AOV-FC-101A, FREQ-F3RHR3, MSS-NRV-MA-101A, PROB-W3D6, A-F3R3W3-X-FL-3, DR-MT, DURATION-D6 268 99.8 0.0 3.299E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6, PROB-W1R6, LOOPIS0LATED1R6, /PZR-SV-REMOVEDWl, A-F3R3Wl-X-C-8 269 99.8 0.0 3.226E-010 UNITY, FREQ-F3RHR3, MSS-NRV-MA-101B, MSS-AOV-MA-101B, PROB-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 270 99.8 0.0 3.226E-010 UNITY, FREQ-F3RHR3, MSS-NRV-MA-101A, MSS-AOV-MA-101A, PROB-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATI0N-D6 271 99.8 0.0 3.192E-010 UNITY, AFW-MOV-CC-151, PROB-W3D6, FREQ-FSRHR3, DR-MT, DURATI0N-D6 272 99.8 0.0 3.072E-010 UNITY, AFW-CCF-FS-FW3AB, PROB-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6 273 99.8 0.0 3.027E-010 UNITY, REFUEL, DURATION-R6, SAS-CPS-FR-2SAC1, IAS-CPS-FS-IAC-1, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F5RHR3 274 99.8 0.0 3.027E-010 UNITY, REFUEL, DURATION-R6, SAS-CPS-FR-1SAC1, IAS-CPS-FS-IAC-1, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F5RHR3 275 99.8 0.0 2.981E-010 UNITY, REFUEL, DURATI0N-R6, SGB-DRAINED-R, SGC-DRAINED-R, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3 276 99.8 0.0 2.981E-010 UNITY, REFUEL, DURATION-R6, SGA-DRAINED-R, SGC-DRAINED-R, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3 277 99.8 0.0 2.981E-010 UNITY, REFUEL, DURATION-R6, SGA-DRAINED-R, SGB-DRAINED-R, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3 278 99.8 0.0 2.858E-010 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW4, PROB-W4R6, FREQ-F7B2 279 99.8 0.0 2.759E-010 UNITY, AFW-CCF-FS-FW3AB, REFUEL, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-FSRHR3 280 99.8 0.0 2.706E-010 UNITY, MSS-AOV-FC-101B, SSHR-AOV-XHE-105, FREQ-F3RHR3, PROB-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 281 99.8 0.0 2.706E-010 UNITY, MSS-AOV-FC-101A, SSHR-AOV-XHE-105, FREQ-F3RHR3, PROB-W2D6, DR-MT, DURATION-D6, 1993/11/24 09:23:41 page 13

D-15

Family->FLOOD/WINDOW Mincut Upper Bound-> l.704E-005 Cut % % Cut Partition Cut Set Report End State ->CD This Partition-> l.704E-005 No. Total Set Frequency Cut Sets LPR-CCF-PG-SUMP2 282 99.8 0.0 2.654E-010 UNITY, AFW-MOV-CC-151, PROB-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 283 99.8 0.0 2.598E-010 UNITY, REFUEL, DURATION-R6, PROB-WlR6, PZR-SV-REMOVEDWl, FREQ-FSRHR3 284 99.8 0.0 2.574E-010 UNITY, REFUEL, DURATION-R6, PROB-WlR6,

/PZR-SV-REMOVEDWl, FREQ-F4RHR3, A-F4R3Wl-X-SF-8 285 99.8 0.0 2. 544E-010 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, REFUEL, FREQ-F3RHR3, DURATION-R6, /PZR-SV-REMOVEDW2, PROB-W2R6, LPR-CCF-PG-SUMP2 286 99.8 0.0 2.516E-010 UNITY, MSS-AOV-FC-101B, SSHR-AOV-XHE-105, FREQ-F3RHR3, PROB-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 287 99.8 0.0 2.516E-010 UNITY, MSS-AOV-FC-lOlA, SSHR-AOV-XHE-105, FREQ-F3RHR3, PROB-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 288 99.8 0.0 2.486E-010 UNITY, AFW-MDP-MA-FW3A, AFW-MDP-MA-FW3B, PROB-W4D6, FREQ-FSRHR3, DR-MT, DURATION-D6 289 99.8 0.0 2.481E-010 UNITY, REFUEL, LPR-CCF-FT-890AB, FREQ-F3RHR3,

/PZR-SV-REMOVEDW4, PROB-W4R10, FRAC-POSlO, DURATION-RlO 290 99.8 0.0 2.466E-010 UNITY, REFUEL, LPI-CCF-FS-SilAB, FREQ-F3RHR3, DURATION-R6, PZR-SV-REMOVEDW3, PROB-W3R6 291 99.8 0.0 2.424E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6, PZR-SV-REMOVEDW4, PROB-W4R6, A-F3R3W4-X-FL-4 292 99.8 0.0 2.413E-010 UNITY, L00PISOLATED2R6, REFUEL, LPI-CCF-FS-SilAB, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6 293 99.8 0.0 2.393E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6, PROB-WlR6, /PZR-SV-REMOVEDWl, A-F3R3Wl-X-FL-9, A-F3R3Wl-X-S1-8, A-F3R3Wl-X-S2-8 294 99.8 0.0 2.385E-010 UNITY, LOSP, PR0B-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6 295 99.8 0.0 2.366E-010 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, REFUEL, FREQ-F3RHR3, DURATION-R6, /PZR-SV-REMOVEDW2, PROB-W2R6, A-F3R3W2-X-FL-9 296 99.8 0.0 2. 3.57E-010 UNITY, PR0B-W4D6, SGS-DRAINED-CSD, FREQ-FSRHR3, DR-MT, DURATION-D6 297 99.8 0.0 2.357E-010 UNITY, AFW-CKV-OO-CV142, PROB-W4D6, FREQ-FSRHR3, DR-MT, DURATION-D6 298 99.8 0.0 2.305E-010 UNITY, REFUEL, MSS-AOV-FC-lOlA, MSS-AOV-FC-lOlC, SSHR-AOV-XHE-105, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-FSRHR3 299 99.8 0.0 _, 2 .305E-010 UNITY, REFUEL, MSS-AOV-FC-lOlB, MSS-AOV-FC-lOlC, SSHR-AOV-XHE-105, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-FSRHR3 300 99.9 0.0 2.305E-010 UNITY, REFUEL, MSS-AOV-FC-101A, MSS-AOV-FC-101B, 1993/11/24 09:23:41 page 14 D-16

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> l.704E-005 This Partition-> 1.~04E-005 Cut % % Cut No. Total Set Frequency Cut Sets SSHR-AOV-XHE-1.05, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F5RHR3 301 99.9 0.0 2.282E-010 UNITY, AFW-MOV-CC-151., PROB-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6 302 99.9 0.0 2.21.6E-010 UNITY, PR0B-W4D6, FREQ-FSRHR3, DR-MT, DURATION-D6, D-FSR3W4-XHE 303 99.9 0.0 2.1.64E-01.0 UNITY, REFUEL, DURATION-R6, SAS-CPS-FR-1.SACl.,

IAS-CPS-FS-IAC-1., /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3 304 99.9 0.0 2.1.64E-01.0 UNITY, REFUEL, DURATION-R6, SAS-CPS-FR-2SAC1.,

IAS-CPS-FS-IAC-1., /PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-F4RHR3 305 99.9 0.0 2.1.41.E-010 UNITY, AFW-PSF-FC-XCONN, PROB-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6 306 99.9 0.0 2.1.41.E-01.0 UNITY, MSS-NRV-FT-101.B, MSS-AOV-MA-101B, PR0B-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6 307 99.9 0.0 2.1.41.E-010 UNITY, MSS-NRV-FT-1.01.A, MSS-AOV-MA-1.0lA, PROB-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6 308 99.9 0.0 2.1.34E-01.0 UNITY, REFUEL, SGS-DRAINED-R, DURATION-R6, PROB-W1R6, /PZR-SV-REMOVEDWl, FREQ-FSRHR3 309 99.9 0.0 2.1.03E-010 UNITY, REFUEL, DURATION-R6, PZR-SV-REMOVEDW4, PROB-W4R6, A-F2B2W4-X-G-4, FREQ-F2B2 31.0 99.9 0.0 2.097E-01.0 UNITY, REFUEL, LPR-MOV-FT-1862B, FREQ-F3RHR3, DURATION-R6, PZR-SV-REMOVEDW2, PR0B-W2R6 311. 99.9 0.0 2.081.E-01.0 UNITY, MSS-AOV-FC-101.B, FREQ-F3RHR3, CIR-COND-UNAVLBL, PR0B-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 31.2 99.9 0.0 2.081.E-01.0 UNITY, MSS-AOV-FC-1.01.A, FREQ-F3RHR3, CIR-COND-UNAVLBL, PR0B-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 313 99.9 0.0 2.076E-01.0 UNITY, PROB-W4D6, FREQ-F4RHR3, A-F4R3W4-X-S1-7, DR-MT, A-F4R3W4-X-S2-7, DURATION-D6 31.4 99.9 0.0 2.061.E-01.0 UNITY, REFUEL, FREQ-F3RHR3, /PZR-SV-REMOVEDW3, PR0B-W3R10, A-F3R3W3-X-FL-7, FRAC-POS10, DURATION-Rl.0 31.5 99.9 0.0 2.051.E-01.0 UNITY, LOSP, PR0B-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6 316 99.9 0.0 2.049E-01.0 UNITY, REFUEL, DURATION-R6, AFW-MOV-CC-151,

/PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-FSRHR3 31.7 99.9 0.0 2.021.E-010 UNITY, REFUEL, DURATION-R6, PR0B-W1R6,

/PZR-SV-REMOVEDWl., FREQ-F7B2 318 99.9 0.0 1.. 972E-01.0 UNITY, AFW-CCF-FS-FW3AB, REFUEL, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3 31.9 99.9 0.0 1.. 936E-01.0 UNITY, MSS-AOV-FC-1.01.B, FREQ-F3RHR3, CIR-COND-UNAVLBL, PROB-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 320 99.9 0.0 1..936E-01.0 UNITY, MSS-AOV-FC-101.A, FREQ-F3RHR3, 1.993/1.1./24 09:23:41. page 15

D-17

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> 1.704E-005 This Partition-> l.704E-OOS Cut % % Cut No. Total Set Frequency Cut Sets CIR-COND-UNAVLBL, PR0B-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 321 99.9 0.0 1. 929E-010 UNITY, REFUEL, MSS-AOV-FC-101C, DURATION-R6, MSS-NRV-MA-lOlC, PR0B-W1R6, /PZR-SV-REMOVEDWl, FREQ-FSRHR3 322 99.9 0.0 1. 929E-010 UNITY, REFUEL, MSS-AOV-FC-101B, DURATION-R6, MSS-NRV-MA-101B, PR0B-W1R6, /PZR-SV-REMOVEDWl, FREQ-FSRHR3 323 99.9 0.0 1.929E-010 UNITY, REFUEL, MSS-AOV-FC-101A, DURATION-R6, MSS-NRV-MA-lOlA, PR0B-W1R6, /PZR-SV-REMOVEDWl, FREQ-FSRHR3 324 99.9 o.o 1.857E-010 UNITY, REFUEL, DURATION-R6, PR0B-W1R6, PZR-SV-REMOVEDWl, FREQ-F4RHR3 325 99.9 0.0 1. 842E-010 UNITY, AFW-PSF-FC-XCONN, PROB-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6 326 99.9 0.0 1.842E-010 UNITY, MSS-NRV-FT-101B, MSS-AOV-MA-101B, PR0B-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6 327 99.9 0.0 l.842E-010 UNITY, MSS-NRV-FT-lOlA, MSS-AOV-MA-lOlA, PROB-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6 328 99.9 0.0 1. 840E-010 UNITY, REFUEL, LPI-CCF-FS-SilAB, FREQ:-F3RHR3, PZR-SV-REMOVEDW4, PROB-W4Rl0, FRAC-POS10, DURATION-RlO 329 99.9 0.0 1.827E-010 UNITY, REFUEL, LPI-MDP-FS-SilB, FREQ-F3RHR3, DURATION-R6, /PZR-SV-REMOVEDW3, PR0B-W3R6 330 99.9 0.0 l.793E-010 UNITY, REFUEL, PZR-SV-REMOVEDW4, PROB-W4Rl0, D-F2B2W4-XHE, FREQ-F2B2, FRAC-POS10, DURATION-RlO 331 99.9 0.0 l.787E-010 UNITY, CON-VFC-RP-COREM, FREQ-F3RHR3, PR0B-W1D6, DR-MT, DURATION-D6, A-F3R3Wl-X-P-3 332 99.9 0.0 l.777E-010 UNITY, AFW-MDP-MA-FW3A, AFW-MDP-MA-FW3B, PROB-W4D6, FREQ-F4RHR3, DR-MT, DURATION-D6 333 99.9 0.0 l.773E-010 UNITY, REFUEL, MSS-AOV-FC-lOlB, MSS-AOV-FC-lOlC, DURATI0N-R6, CIR-COND-UNAVLBL,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-FSRHR3 334 99.9 o.o l.773E-010 UNITY, REFUEL, MSS-AOV-FC-101A, MSS-AOV-FC-lOlC, DURATION-R6, CIR-COND-UNAVLBL,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-FSRHR3 335 99.9 o.o 1. 773E-010 UNITY, REFUEL, MSS-AOV-FC-lOlA, MSS-AOV-FC-lOlB, DURATION-R6, CIR-COND-UNAVLBL,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-FSRHR3 336 99.9 o.o 1.705E-010 UNITY, LOSP, PROB-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 337 99.9 0.0 1. 685E-010 UNITY, PROB-W4D6, SGS-DRAINED-CSD, FREQ-F4RHR3, DR-MT, DURATION-D6 338 99.9 0.0 l.685E-010 UNITY, AFW-CKV-00-CV142, PROB-W4D6, FREQ-F4RHR3, DR-MT, DURATION-D6 339 99.9 0.0 l.676E-010 UNITY, LPI-CCF-FS-SilAB, FREQ-F3RHR3, PR0B-W1D6, 1993/11/24 09:23:41 page 16 D-18

Family->FLOOD/WINDOW Partition Cut Set Report Mincut Upper Bound-> 1.704E-005 Cut % % Cut End State ->CD This Partition-> l.704E-005 No. Total Set Frequency Cut Sets DR-MT, DURATION-D6 340 99.9 0.0 1.659E-010 UNITY, LPR-MOV-FT-1862B, FREQ-F3RHR3, SGB-DRAINED-R, PROB-W2D6, DR-MT, DURATION-D6 341 99.9 0.0 1.659E-010 UNITY, LPR-MOV-FT-1862B, FREQ-F3RHR3, SGA-DRAINED-R, PROB-W2D6, DR-MT, DURATION-D6 342 99.9 0.0 l.648E-010 UNITY, REFUEL, MSS-AOV-FC-101B, MSS-AOV-FC~lOlC, SSHR-AOV-XHE-105, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3 343 99.9 0.0 l.648E-010 UNITY, REFUEL, MSS-AOV-FC-lOlA, MSS-AOV-FC-101C, SSHR-AOV-XHE-105, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3 344 99.9 0.0 1.648E-010 UNITY, REFUEL, MSS-AOV-FC-lOlA, MSS-AOV-FC-lOlB, SSHR-AOV-XHE-105, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3 345 99.9 0.0 l.636E-010 UNITY, REFUEL, LPR-CCF-FT-890AB, FREQ-FlB2, PZR-SV-REMOVEDW4, PROB-W4Rl0, FRAC-POS10, DURATION-RlO 346 99.9 0.0 l.531E-010 UNITY, AFW-PSF-FC-XCONN, PROB-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 347 99.9 0.0 l.53iE-010 UNITY, MSS-NRV-FT-lOlB, MSS-AOV-MA-lOlB, PROB-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6

.348 99.9 0.0 l.531E-010 UNITY, MSS-NRV-FT-lOlA, M'SS-AOV-MA-lOlA, PROB-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 349 99.9 0.0 l.528E-010 UNITY, FREQ-F3RHR3, PROB-W2D6, A-F3R3W2-X-S1-8, A-F3R3W2~X-S2-8, DR-MT, DURATION-D6, A-F3R3W2-X-C-8 350 99.9 0.0 l.526E-010 UNITY, REFUEL, SGS-DRAINED-R, DURATION-R6, PROB-WlR6, /PZR-SV-REMOVEDWl, FREQ-F4RHR3 351 99.9 0.0 l.467E-010 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, FREQ-F3RHR3, PR0B-W3D6, A-F3R3W3-X-FL-3, DR-MT, DURATION-D6 .

352 99.9 0.0 l.466E-010 UNITY, LOSP, PROB-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6 353 99.9 0.0 l.465E-010 UNITY, REFUEL, DURATION-R6, AFW-MOV-CC-151,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3 354 99.9 0.0 l.463E-010 UNITY, AFW-MDP-MA-FW3A, AFW-MDP-MA-FW3B, FREQ-F3RHR3, PROB-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 355 99.9 0.0 l.428E-010 UNITY, AFW-CCF-LK-STMBD, PROB-W2D6, FREQ-F5RHR3, DR-MT, DURATION-D6 356 99.9 0.0 1.4288-010 UNITY, AFW-CKV-FT-CV27, PROB-W2D6, FREQ-F5RHR3, DR-MT, DURATION-D6 357 99.9 0.0 l.428E-010 UNITY, AFW-CKV-FT-CV58, PROB-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6 358 99.9 0.0 1.4258-010 UNITY, REFUEL, LPR-CCF-FT-890AB, FREQ-F3RHR3, DURATION-R6, PZR-SV-REMOVEDW3, PROB-W3R6 359 99.9 0.0 l.394E-010 UNITY, LOOPIS0LATED2R6, REFUEL, 1993/11/24 09:23:41 page 17

D-19

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> l.704E-005 This Partition-> l.704E-OOS Cut % % Cut No. Total Set Frequency Cut Sets LPR-CCF-FT-862AB, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW2, PR0B-W2R6 360 99.9 0.0 l.394E-010 UNITY, LOOPISOLATED2R6; REFUEL, LPR-CCF-FT-860AB, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW2, PR0B-W2R6 361 99.9 0.0 l.394E-010 UNITY, LOOPISOLATED2R6, REFUEL, LPR-CCF-FT-890AB, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6 362 99.9 0.0 l.388E-010 UNITY, FREQ-F3RHR3, PROB-W2D6, SGS-DRAINED-CSD, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 363 99.9 0.0 l.388E-010 UNITY, AFW-CKV-00-CV142, FREQ-F3RHR3, PROB-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 364 99.9 0.0 l.379E-010 UNITY, REFUEL, MSS-AOV-FC-101B, DURATION-R6, MSS-NRV-MA-lOlB, PROB-W1R6, /PZR-SV-REMOVEDWl, FREQ-F4RHR3 365 99.9 0.0 l.379E-010 UNITY, REFUEL, MSS-AOV-FC-101C, DURATION-R6, MSS-NRV-MA-101C, PROB-W1R6, /PZR-SV-REMOVEDWl, FREQ-F4RHR3 366 99.9 0.0 1. 379E-010 UNITY, REFUEL, MSS-AOV-FC-101A, DURATION-R6, MSS-NRV-MA-lOlA, PROB-W1R6, /PZR-SV-REMOVEDWl, FREQ-F4RHR3 367 99.9 0.0 1. 365E-010 UNITY, FREQ-F3RHR3, PROB-W2D6, A-F3R3W2-X-SF-8, DR-MT, DURATION-D6, A-F3R3W2-X-C-8 368 99.9 0.0 1. 361E-010 UNITY, AFW-MDP-MA-FW3A, AFW-MDP-MA-FW3B, FREQ-F3RHR3, PR0B-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 369 99.9 0.0 1. 360E-010 UNITY, REFUEL, MSS-AOV-FC-101B, DURATION-R6, MSS-NRV-MA-101B, SGC-DRAINED-R,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F5RHR3 370 99.9 0.0 1.360E-010 UNITY, REFUEL, MSS-AOV-FC-101C, DURATION-R6, MSS-NRV-MA-lOlC, SGB-DRAINED-R,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F5RHR3 371 99.9 0.0 1. 360E-010 UNITY, REFUEL, MSS-AOV-FC-101C, DURATION-R6, MSS-NRV-MA-lOlC, SGA-DRAINED-R,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F5RHR3 372 99.9 0.0 1. 360E-010 UNITY, REFUEL, MSS-AOV-FC-101A, DURATION-R6, MSS-NRV-MA-lOlA, SGC-DRAINED-R,

/PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-F5RHR3 373 99.9 0.0 l.360E-010 UNITY, REFUEL, MSS-AOV-FC-101B, DURATION-R6, MSS-NRV-MA-101B, SGA-DRAINED-R,

/PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-F5RHR3 374 99.9 0.0 1. 360E-010 UNITY, REFUEL, MSS-AOV-FC-101A, DURATION-R6, MSS-NRV-MA-lOlA, SGB-DRAINED-R,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F5RHR3 375 99.9 0.0 1.355E-010 UNITY, AFW-MDP-FR-3A6HR, AFW-MDP-MA-FW3B, PROB-W2D6, FREQ-F5RHR3, DR-MT, DURATION-D6 376 99.9 0.0 l.336E-010 UNITY, PPS-MOV-00-1536, PPS-SOV-00-1456, 1993/11/24 09:23:41 page 18 D-20

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> l.704E-005 This Partition-> l.704E-005 Cut % % Cut No. Total Set Frequency Cut Sets PROB-W2D6, FREQ-FSRHR3, DR-MT, A-F5R3W2-X-S1-8, DURATION-D6 377 99.9 0.0 l.336E-010 UNITY, PPS-MOV-00-1535, PPS-SOV-00-1455C, PROB-W2D6, FREQ-FSRHR3, DR-MT, A-FSR3W2-X-Sl-8, DURATION-D6 378 99.9 0.0 l.336E-010 UNITY, REFUEL, FREQ-F3RHR3, /PZR-SV-REMOVEDW4, PROB-W4Rl0, FRAC-POSlO, D-F3R3W4-XHE, DURATION-RlO 379 99.9 0.0 l.317E-010 UNITY, MSS-NRV-FT-101B, MSS-AOV-MA-101B, PROB-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6 380 99.9 0.0 l.317E-010 UNITY, AFW-PSF-FC-XCONN, PROB-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6 381 99.9 0.0 1.317E-010 UNITY, MSS-NRV-FT-lOlA, MSS-AOV-MA-101A, PROB-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6 382 99.9 o.o l.317E-010

UNITY, REFUEL, LOSP, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-FSRHR3 383 99.9 0.0 1.290E-010 UNITY, FREQ-F3RHR3, PROB-W2D6, SGS-DRAINED-CSD, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 384 99.9 o.o 1.290E-010 UNITY, AFW-CKV-00-CV142, FREQ-F3RHR3, PROB-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 385 99.9 0.0 l.285E-010 UNITY, MSS-AOV-FC-lOlB, MSS-NRV-PG-lOlB, PROB-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6

386 99.9 0.0 l.285E-010 UNITY, MSS-AOV-FC-101A, MSS-NRV-PG-lOlA, PROB-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6 387 99.9 o.o 1.268E-010 UNITY, REFUEL, MSS-AOV-FC-101B, MSS-AOV-FC-lOlC, DURATION-R6, CIR-COND-UNAVLBL,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3 388 99.9 0.0 l.268E-010 UNITY, REFUEL, MSS-AOV-FC-lOlA, MSS-AOV-FC-lOlC, DURATION-R6, CIR-COND-UNAVLBL,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3 389 99.9 0.0 l.268E-010 UNITY, REFUEL, MSS-AOV-FC-lOlA, MSS-AOV-FC-101B, DURATION-R6, CIR-COND-UNAVLBL,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3 390 99.9 0.0 l.249E-010 UNITY, MSS-AOV-FC-101B, FREQ-F3RHR3, MSS-NRV-MA-lOlB, PROB-W2D6, DR-MT, DURATION-D6, A-F3R3W2-X-C-8 391 99.9 0.0 l.249E-010 UNITY, MSS-AOV-FC-lOlA, FREQ-F3RHR3, MSS-NRV-MA-101A, PROB-W2D6, DR-MT, DURATION-D6, A-F3R3W2-X-C-8 392 99.9 0.0 l.247E-010 UNITY, SGA-DRAINED-R, SGB-DRAINED-R, PROB-W4D6, FREQ-FSRHR3, DR-MT, DURATION-D6 393 99.9 0.0 l.228E-010 UNITY, AFW-CKV-FT-CV27, PROB-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6 394 99.9 0.0 l.228E-010 UNITY, AFW-CKV-FT-CV58, PROB-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6 395 99.9 0.0 l.228E-010 UNITY, AFW-CCF-LK-STMBD, PROB-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6 1993/11/24 09:23:41 page 19

D-21

Family->FLOOD/WINDOW Partition Cut Set Report Mincut Upper Bound-> 1.704E-OOS Cut % % cut End State ->CD This Partition-> 1.704E-OOS No. Total Set Frequency Cut Sets 396 99.9 0.0 1.210E-010 UNITY, REFUEL, LPR-MOV-FT-1860B, FREQ-F3RHR3, DURATION-R6, PZR-SV-REMOVEDW2, PROB-W2R6 397 99.9 0.0 1.210E-010 UNITY, REFUEL, LPI-MDP-FS-SI1B, FREQ-F3RHR3, DURATION-R6, PZR-SV-REMOVEDW2, PROB-W2R6 398 99.9 0.0 l.194E--010 UNITY, LOOPISOLATED2R6, CPC-MDP-FR-SWlOA, CPC-MDP-MA-SWlOB, REFUEL, FREQ-F3RHR3, DURATI0N-R6, OSR-TRA-MA, ISR-TRA-MA,

/PZR-SV-REMOVEDW2, PROB-W2R6 399 99.9 0.0 l.182E-010 UNITY, AFW-PSF-FC-XCONN, REFUEL, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-FSRHR3 400 99.9 0.0 1.180E-010 UNITY, CON-VFC-RP-COREM, LOOPIS0LATED2R6, REFUEL, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6, A-F3R3W2-X-P-3 401 99.9 0.0 l.165E-010 UNITY, AFW-MDP-FR-3A6HR, AFW-MDP-MA-FW3B, PROB-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6 402 99.9 0.0 l.149E-010 UNITY, PPS-MOV-00-1536, PPS-SOV-00-1456, PROB-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6, A-F5R3W3-X-S1-7 403 99.9 0.0 l.149E-010 UNITY, PPS-MOV-00-1~35, PPS-S0V-00-1455C, PROB-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6, A-F5R3W3-X-S1-7

404 99.9 0.0 1.lOSE-010 UNITY, MSS-AOV-FC-101B, MSS-NRV-PG-101B, PROB-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6 405 99.9 0.0 1.lOSE-010 UNITY, MSS-AOV-FC-101A, MSS-NRV-PG-lOlA, PROB-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6 406 99.9 0.0 1.104E-010 UNITY, FREQ-F3RHR3, MSS-NRV-MA-lOlA, MSS-AOV-MA-101A, PROB-W3D6, A-F3R3W3-X-FL-3, DR-MT, DURATION-D6 407 99.9 0.0 l.104E-010 UNITY, FREQ-F3RHR3, MSS-NRV-MA-101B, MSS-AOV-MA-101B, PROB-W3D6, A-F3R3W3-X-FL-3, DR-MT, DURATION-D6 408 100.0 0.0 1.092E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6, SGB-DRAINED-R, PROB-W1R6, /PZR-SV-REMOVEDWl, A-F3R3Wl-X-FL-9 409 100.0 0.0 1.092E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6, SGC-DRAINED-R, PR0B-W1R6, /PZR-SV-REMOVEDWl, A-F3R3Wl-X-FL-9 410 100.0 0.0 l.092E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6, SGA-DRAINED-R, PROB-W1R6, /PZR-SV-REMOVEDWl, A-F3R3Wl-X-FL-9 411 100. 0 0.0 1.063E-010 UNITY, REFUEL, LPR-CCF-FT-890AB, FREQ-F3RHR3, PZR-SV-REMOVEDW4, PROB-W4R10, FRAC-POSlO, DURATION-RlO 412 100.0 0.0 1.060E-010 UNITY, REFUEL, LPI-MDP-FS-SilB, FREQ-F3RHR3, DURATION-R6, /PZR-SV-REMOVEDW4, PROB-W4R6 413 100.0 0.0 1.025E-010 UNITY, REFUEL, PZR-SV-REMOVEDW4, PROB-W4R10, FREQ-F7B2, FRAC-POS10, DURATION-RlO, 1993/11/24 09:23:41 page 20 D-22

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> 1.704E-005 This Partition-> 1.704E-005 Cut % % Cut No. Total Set Frequency Cut Sets A-F7B2W4-X-G-4 414 100.0 0.0 1.021E-010 UNITY, AFW-CKV-FT-CV27, PR0B-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 415 100.0 0.0 1.021E-010 UNITY, AFW-CKV-FT-CV58, PR0B-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 416 100.0 0.0 1.021E-010 UNITY, AFW-CCF-LK-STMBD, PR0B-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6 417 100.0 0.0 1.019E-010 UNITY, CON-VFC-RP-COREM, L00PISOLATED2R6, REFUEL, ISR-MDP-FS-RS1A, FREQ-F3RHR3, DURATION-R6, OSR-TRA-MA, /PZR-SV-REMOVEDW2, PR0B-W2R6 1993/11/24 09:23:41 page 21

D-23

Appendix D.2 Basic Event Importances Based on Cutsets without Recovery Actions

D-24

Family Analysis Case IMPORTANCE MEASURES REPORT FLOOD/WINDOW USERl ALTERNATE (Alternate Cut Sets)

EndState (Sorted by Fussell-Vesley Importance)

CD Num. Probability Fussell- Risk Risk of of Vesely Reduction Increase Event Name 0cc. Failure Importance Ratio Ratio UNITY 417 l.OOOE+OOO 1.000E+OOO l.OOOE+OOO REFUEL 184 6.000E-001 5.657E-001 2.303E+OOO 1.377E+OOO FREQ-FlB2 20 1.600E-008 5.099E-001 2.040E+OOO 1.238E+018 DR-MT 233 1.200E+OOO 4.343E-001 1.768E+OOO 9.276E-001 DURATION-D6 233 2.550E+002 4.343E-001 1.768E+OOO 5.674E-001 DURATION-R6 149 2.380E+002 3.0SOE-001 1.44SE+OOO 6.933E-001 DURATION-Rio 35 4.440E+002 2.577E-001 1. 347E+OOO 7.429E-001 FRAC-POS10 35 5.000E-001 2.577E-001 1. 347E+OOO 1.258E+OOO PR0B-W4Rl0 25 9.840E-001 2.529E-001 1. 338E+OOO 1. 004E+OOO FREQ-F5RHR3 137 l.070E-008 2.037E-001 1.256E+OOO 5.866E+004 PR0B-W2D6 117 4.360E-001 1. 738E-001 l.210E+OOO l.225E+OOO PR0B-W2R6 87 5.430E-001 1.616E-001 l.193E+OOO l.136E+OOO PR0B-W3D6 83 3.750E-001 l.483E-001 1.174E+OOO 1.247E+OOO FREQ-F4RHR3 113 7.650E-009 1. 425E-001 1.166E+OOO 5.866E+004 PR0B-W3R6 17 4.lOOE-001 1.328E-001 l.153E+OOO 1.191E+OOO FREQ-F2B2 17 3.SOOE-009 1.212E-001 1.138E+OOO 2.938E+Ol8 PR0B-W1D6 16 1. l 70E-001 8.600E-002 1.094E+OOO 1.649E+OOO LOOPIS0LATED2R6 17 7.000E-001 6.247E-002 1.067E+OOO l.027E+OOO PR0B-W4D6 17 7.200E-002 2.609E-002 1.027E+OOO l.336E+OOO FREQ-F3RHR3 119 l.040E-008 2.026E-002 1. 021E+OOO S.849E+004 PR0B-W4R6 12 3.400E-002 9.353E-003 l.009E+OOO 1.266E+OOO SGA-DRAINED-R 19 2.300E-002 6.771E-003 l.007E+OOO 1.288E+OOO SGB-DRAINED-R 19 2.300E-002 6.771E-003 1.007E+OOO l.288E+OOO PR0B-W3Rl0 10 1. 600E-002 4.825E-003 1.00SE+OOO l.297E+OOO PR0B-W1R6 33 1.700E-002 4.309E-003 1. 004E+OOO 1.249E+OOO LPR-CCF-PG-SUMP2 22 l.OOOE-001 4.300E-003 1. 004E+OOO 1.039E+OOO A-F3R3Wl-X-FL-9 6 1.900E-001 4.267E-003 1. 004E+OOO 1.0lSE+OOO A-F3R3W2-X-FL-9 21 9.300E-002 3.779E-003 1. 004E+OOO 1. 037E+OOO MSS-AOV-FC-101A 38 1. SOOE-001 3.376E-003 1.003E+OOO 1.019E+OOO MSS-AOV-FC-101B 38 1. SOOE-001 3.376E-003 1. 003E+OOO 1. 019E+OOO MSS-NRV-MA-101B 19 5.000E-002 2.897E-003 1. 003E+OOO 1.055E+OOO MSS-NRV-MA-lOlA 19 5.000E-002 2.897E-003 1. 003E+OOO 1.055E+OOO A-F5R3W2-X-Sl-8 4 7.800E-002 2.753E-003 1.003E+OOO 1.033E+OOO A-F5R3W2-X-S2-8 2 2.700E-001 2.737E-003 l.003E+OOO 1.007E+OOO A-F3R3W4-X-FL-7 2 4.200E-002 2.438E-003 1.002E+OOO 1. 056E+OOO FREQ-F7B2 11 8.410E-011 2.411E-003 1.002E+OOO 5.308E+Ol6 AFW-MDP-MA-FW3B 25 5 .272E-001 l.741E-003 1. 002E+OOO 1.002E+OOO A-F5R3W3-X-Sl-7 3 7.SOOE-002 1.530E-003 1. 002E+OOO 1.018E+OOO SSHR-AOV-XHE-105 26 1. 300E-002 1.520E-003 1.002E+OOO 1.115E+OOO A-F5R3W3-X-82-7 1 2.700E-001 1. 517E-003 1.002E+OOO 1.004E+OOO A-F3R3W3-X-FL-3 11 3.700E-002 1.457E-003 1.00lE+OOO l.038E+OOO A-F5R3W2-X-SF-8 2 1. lOOE-002 1. 430E-003 l.OOlE+OOO 1.129E+OOO AFW-MDP-FS-FW3A 13 6.300E-003 1. 319E-003 1.00lE+OOO 1.208E+OOO A-F1B2W4-X-G-4 2 3.lOOE-002 1.187E-003 l.OOlE+OOO l.037E+OOO 1993/11/24 09:26:47 page 1

D-25

IMPORTANCE MEASURES REPORT (Alternate Cut Sets)

Family FLOOD/WINDOW EndState : CD Analysis USERl Case ALTERNATE (Sorted by Fussell-Vesley Importance)

Num. Probability Fussell- Risk Risk of of Vesely Reduction Increase Event Name 0cc. Failure Importance Ratio Ratio CIR-COND-UNAVLBL 26 l.OOOE-002 l.169E-003 l.001E+OOO 1.116E+OOO MSS-AOV-MA-lOlB 19 5.000E-002 1. 061E-003 l.OOlE+OOO 1.020E+OOO MSS-AOV-MA-lOlA 19 5.000E-002 1.061E-003 1.00lE+OOO 1.020E+OOO PZR-SV-REMOVEDW2 87 5.000E-002 1.026E-003 l.OOlE+OOO 1.019E+OOO A-F3R3Wl-X-C-8 2 4.400E-002 9.804E-004 l.OOlE+OOO 1.021E+OOO LOOPISOLATED1R6 4 3.000E-001 8.791E-004 l.OOlE+OOO 1.002E+OOO A-F4R3W2-X-S2-8 2 1.SOOE-001 8.531E-004 l.001E+OOO 1.004E+OOO A-F4R3W2-X-S1-8 2 5.lOOE-002 8.531E-004 l.OOlE+OOO 1.016E+OOO D-F5R3W2-XHE 2 6.400E-003 8.319E-004 l.OOlE+OOO 1.129E+OOO A-F4R3W2-X-SF-8 2 8.700E-003 8.0SSE-004 l.OOlE+OOO 1.092E+OOO A-FSR3W3-X-SF-7 1 l.lOOE-002 7.923E-004 l.OOlE+OOO l.071E+OOO SGS-DRAINED-R 6 8.300E-003 7.516E-004 l.OOlE+OOO 1.090E+OOO LPI-MDP-FS-SI1B 8 3.000E-003 5.203E-004 l.OOlE+OOO 1.173E+OOO A-F4R3W3-X-S2-7 1 1. SOOE-001 4. 727E-004 l.OOOE+OOO 1.002E+OOO A-F4R3W3-X-S1-7 1 S.lOOE-002 4. 727E-004 l.OOOE+OOO 1.009E+OOO D-FSR3W3-XHE 1 6.400E-003 4.610E-004 l.OOOE+OOO 1.072E+OOO A-F3R3W2-X-C-8 7 l.200E-002 4.541E-004 l.OOOE+OOO 1.037E+OOO A-F4R3W3-X-SF-7 1 8.700E-003 4.480E-004 l.OOOE+OOO 1.0SlE+OOO AFW-MDP-MA-FW3A 10 2.000E-003 4.069E-004 l.OOOE+OOO 1.203E+OOO A-F3R3W4-X-FL-4 2 1.600E-002 3.981E-004 l.OOOE+OOO 1.024E+OOO AFW-CKV-00-CV142 10 l.OOOE-003 3.859E-004 l.OOOE+OOO 1.385E+OOO A-F2B2W4-X-G-4 2 3.SOOE-002 3.454E-004 l.OOOE+OOO 1.009E+OOO A-F3R3W3-X-FL-7 2 9.300E-002 3.443E-004 l.OOOE+OOO 1.003E+OOO LPR-MOV-FT-1862B 5 5.200E-003 3.089E-004 1.000E+OOO 1.059E+OOO SGS-DRAINED-CSD 8 1. OOOE-003 3.066E-004 l.OOOE+OOO 1.306E+OOO IAS-CPS-FS-IAC-1 12 8.000E-002 2.661E-004 l.OOOE+OOO l.003E+OOO A-F3R3W2-X-S1-8 5 5.lOOE-002 2.328E-004 1.000E+OOO 1.004E+OOO A-F3R3W2-X-S2-8 5 1.SOOE-001 2.328E-004 1.000E+OOO 1.001E+OOO LPR-CCF-PG-SUMPl 1 1.000E-002 2.184E-004 l.OOOE+OOO 1.022E+OOO A-F3R3W2-X-SF-8 5 8.200E-003 2.0SOE-004 l.OOOE+OOO 1.025E+OOO A-F5R3W1-X-S2-8 1 6.300E-001 1.711E-004 l.OOOE+OOO 1.000E+OOO A-F5R3W1-X-S1-8 1 1.SOOE-001 l.711E-004 l.OOOE+OOO 1.00lE+OOO LPR-MOV-FT-1860B 3 3.000E-003 1.670E-004 l.OOOE+OOO 1.056E+OOO SGC-DRAINED-R 9 2.300E-002 1.658E-004 1.000E+OOO 1.007E+OOO MSS-NRV-FT-lOlB 8 3.000E-003 1.603E-004 l.OOOE+OOO 1.053E+OOO.

MSS-NRV-FT-lOlA 8 3.000E-003 1. 603E-004 l.OOOE+OOO 1.053E+OOO LPR-MOV-FT-1890B 2 3.000E-003 1.370E-004 1.000E+OOO 1.046E+OOO SAS-CPS-FR-2SAC1 6 4.SOOE-003 1.330E-004 1. OOOE+OOO l.028E+OOO SAS-CPS-FR-lSACl 6 4.SOOE-003 1.330E-004 l.OOOE+OOO 1.028E+OOO AFW-CCF-FS-FW3AB 6 3.SOOE-004 1. 213E-004 l.OOOE+OOO 1.346E+OOO MSS-AOV-FC-lOlC 12 1.SOOE-001 l.174E-004 l.OOOE+OOO 1.00lE+OOO PPS-MOV-FT-1536 2 4.000E-002 1.066E-004 l.OOOE+OOO 1.003E+OOO PORV-PATH-CLSD 2 5.000E-002 1.066E-004 l.OOOE+OOO 1.002E+OOO A-F5R3W4-X-SF-7 1 7.SOOE-003 l.037E-004 1.000E+OOO 1.014E+OOO 1993/11/24 09:26:47 page 2 D-26

IMPORTANCE MEASURES REPORT (Alternate Cut Sets)

Family FLOOD/WINDOW EndState : CD Analysis USER1 Case ALTERNATE (Sorted by Fussell-Vesley Importance)

Num. Probability Fussell- Risk Risk of of Vesely Reduction Increase Event Name 0cc. Failure Importance Ratio Ratio AFW-MOV-CC-151 6 2.600E-004 9.007E-005 l.OOOE+OOO l.346E+OOO CON-VFC-RP-COREM 5 2.000E-002 9.00lE-005 1.000E+OOO 1.004E+OOO A-F3R3W2-X-FL-4 1 3.700E-002 8.752E-005 l.OOOE+OOO l.002E+OOO OSR-TRA-MA 4 2.SOOE-001 7.961E-005 l.OOOE+OOO l.OOOE+OOO D-F3R3W2-XHE 2 6.200E-004 7.833E-005 l.OOOE+OOO l.126E+OOO LPI-CCF-FS-SilAB 5 4.SOOE-004 7.444E-005 l.OOOE+OOO l.165E+OOO ISR-TRA-MA 3 2.SOOE-001 7.363E-005 1.000E+OOO 1.000E+OOO D-F3R3W3-XHE 2 6.200E-004 6.334E-005 l.OOOE+OOO l.102E+OOO D-F4R3W2-XHE 2 6.200E-004 5.762E-005 l.OOOE+OOO 1. 093E+OOO A-F4R3W4-X-SF-7 1 S.SOOE-003 S.438E-005 l.OOOE+OOO l.OlOE+OOO A-F4R3W1-X-Sl-8 1 1. 20QE-,.Q01 S.436E-005 l.OOOE+OOO l.OOOE+OOO A-F4R3Wl-X-S2-8 1 4.200E-001 S.436E-005 1. OOOE+OOO l.OOOE+OOO LOSP 5 l.670E-004 S.235E-005 l.OOOE+OOO 1. 313E+OOO A-FSR3W4-X-Sl-7 1 3.300E-002 5.020E-005 l.OOOE+OOO l.OOlE+OOO A-F5R3W4-X-S2-7 1 1.100E-001 S.020E-005 1.000E+OOO l.OOOE+OOO AFW-PSF-FC-XCONN 5 1.SOOE-004 4.701E-005 l.OOOE+OOO 1. 313E+OOO LPR-CCF-FT-890AB 5 2.600E-004 4.692E-005 l.OOOE+OOO l.180E+OOO D-FlB2W4-XHE 1 l.200E-003 4.429E-005 l.OOOE+OOO l.037E+OOO SS-NRV-MA-lOlC 4 5.000E-002 3.536E-005 1.000E+OOO l.OOlE+OOO D-F3R3Wl-XHE 1 1. 600E-003 3.495E-005 1. OOOE+OOO 1. 022E+OOO D-F4R3W3-XHE 1 6.200E-004 3.193E-005 l.OOOE+OOO 1. OSlE+OOO A-F3R3W2-X-C-3 1 1. 200E-002 2.838E-005 1. OOOE+OOO 1. 002E+OOO A-FSR3Wl-X-SF-8 1 1. 700E-002 2.565E-005 1. OOOE+OOO l.OOlE+OOO LPR-MOV-PG-1890B 1 6.600E-004 2.436E-005 l.OOOE+OOO 1. 037E+OOO A-F3R3W3-X-S1-7 1 5.lOOE-002 2.378E-005 l.OOOE+OOO l.OOOE+OOO A-F3R3W3-X-S2-7 1 l.SOOE-001 2.378E-005 l.OOOE+OOO 1 .'OOOE+OOO A-F7B2W3-X-G-4 1 8.SOOE-002 2.210E-005 1. OOOE+OOO l.OOOE+OOO AFW-CKV-FT-CV27 3 1. OOOE-004 2.156E-005 1. OOOE+OOO 1. 216E+OOO AFW-CKV-FT-CVSS 3 1. OOOE-004 2.156E-005 1. OOOE+OOO l.216E+OOO AFW-CCF-LK-STMBD 3 1. OOOE-004 2.156E-005 1. OOOE+OOO l.216E+OOO A-F3R3W3-X-SF-7 1 8.200E-003 2.124E-005 l.OOOE+OOO 1. 003E+OOO D-FSR3Wl-XHE 1 1. 300E-002 l.961E-005 l.OOOE+OOO l.OOlE+OOO A-F4R3Wl-X-SF-8 1 l.400E-002 1. SlOE-005 l.OOOE+OOO l.OOlE+OOO AFW-MDP-FR-3A6HR 2 1. SOOE-004 l.478E-005 l.OOOE+OOO l.082E+OOO PPS-S0V-00-l455C 2 3.000E-002 l.458E-005 l.OOOE+OOO l.OOOE+OOO PPS-MOV-00-1535 2 4.000E-002 l.458E-005 l.OOOE+OOO l.OOOE+OOO PPS-MOV-00-1536 2 4.000E-002 l.458E-005 l.OOOE+OOO l.OOOE+OOO PPS-SOV-00-1456 2 3.000E-002 l.458E-005 1.000E+OOO l.OOOE+OOO A-F3R3Wl-X-S1-8 1 l.200E-001 l.404E-005 1.000E+OOO l.OOOE+OOO A-F3R3Wl-X-S2-8 1 4.200E-001 l.404E-005 l.OOOE+OOO l.OOOE+OOO MSS-NRV-PG-101A 2 6.000E-004 l.402E-005 l.OOOE+OOO l.023E+OOO MSS-NRV-PG-101B 2 6.000E-004 l.402E-005 l.OOOE+OOO l.023E+OOO D-FSR3W4-XHE 1 9.400E-004 1. 300E-005 l.OOOE+OOO 1.014E+OOO A-F4R3W4-X-S1-7 1 1.600E-002 l.218E-005 l.OOOE+OOO l.OOlE+OOO 1993/11/24 09:26:47 page 3

D-27

IMPORTANCE MEASURES REPORT (Alternate Cut Sets)

Family FLOOD/WINDOW EndState : CD Analysis USERl Case ALTERNATE (Sorted by Fussell-Vesley Importance)

Num. Probability Fussell- Risk Risk of of Vesely Reduction Increase Event Name 0cc. Failure Importance Ratio Ratio A-F4R3W4-X-S2-7 1 7.700E-002 1.218E-005 1.000E+OOO 1.000E+OOO D-F2B2W4-XHE 1 1.200E-003 1.052E-005 1.000E+OOO 1.009E+OOO A-F3R3Wl-X-P-3 1 2.400E-002 l.048E-005 1.000E+OOO 1.000E+OOO LPR-CCF-FT-862AB 1 2.600E-004 8.179E-006 1.000E+OOO 1.031E+OOO LPR-CCF-FT-860AB 1 2.600E-004 8.179E-006 1.000E+OOO 1.031E+OOO D-F3R3W4-XHE 1 1.400E-004 7.837E-006 1.000E+OOO 1.056E+OOO CPC-MDP-FR-SWlOA 1 3.840E-003 7.002E-006 1.000E+OOO 1.002E+OOO CPC-MDP-MA-SWlOB 1 9.274E-001 7.002E-006 1.000E+OOO 1.000E+OOO A-F3R3W2-X-P-3 1 1.lOOE-002 6.921E-006 1.000E+OOO 1.00lE+OOO A-F7B2W4-X-G-4 1 3.lOOE-002 6.014E-006 1.000E+OOO 1.000E+OOO ISR-MDP-FS-RS1A 1 3.SOOE-002 5.977E-006 1.000E+OOO 1.000E+OOO PZR-SV-REMOVEDWl 33 1.000E-002 5.891E-006 1.000E+OOO 1.001E+OOO PZR-SV-REMOVEDW3 27 9.000E-001 -2.061E-003 9.979E-001 9.998E-001 PZR-SV-REMOVEDW4 37 3.000E-001 -4.645E-002 9.556E-001 8.916E-001 1993/11/24 09:26:47 page 4 D-28

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> 5.lllE-006 This Partition-> 5.lllE-006 cut % % cut No. Total Set Frequency cut Sets 1 28.7 28.7 1.468E-006 UNITY, REFUEL, FREQ-F1B2, /PZR-SV-REMOVEDW4, PR0B-W4R10, FRAC-POS10, DURATION-R10 2 45.2 16.4 8.431E-007 UNITY, REFUEL, DURATION-R6, FREQ-F1B2, PZR-SV-REMOVEDW3, PR0B-W3R6 3 61.4 16.2 8.286E-007 UNITY, REFUEL, DURATION-R6, FREQ-F1B2,

/PZR-SV-REMOVEDW2, PR0B-W2R6, R-B2W2-XHE-S/R6 4 68.2 6.8 3.486E-007 UNITY, REFUEL, /PZR-SV-REMOVEDW4, PR0B-W4R10, FREQ-F2B2, FRAC-POS10, DURATION-R10 5 72.1 3.9 2.002E-007 UNITY, REFUEL, DURATION-R6, PZR-SV-REMOVEDW3, PR0B-W3R6, FREQ-F2B2 6 76.0 3.8 1.968E-007 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-F2B2, R-B2W2-XHE-S/R6 7 77.8 1. 8 9.368E-008 UNITY, REFUEL, DURATION-R6, FREQ-F1B2,

/PZR-SV-REMOVEDW3, PR0B-W3R6 8 79.4 1.5 8.006E-008 UNITY, REFUEL, DURATION-R6, PZR-SV-REMOVEDW3, PR0B-W3R6, FREQ-F5RHR3, R-R3W3-XHE-F 9 80.9 1. 5 7.835E-008 UNITY, LOOPISOLATED2R6, REFUEL, DURATION-R6,

/PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-F5RHR3, R-R3W2-XHE-F 10 82.1 1.2 6.244E-008 UNITY, REFUEL, /PZR-SV-REMOVEDW4, PR0B-W4R10, FREQ-F5RHR3, FRAC-POS10, DURATION-R10, R-R3W4-XHE-F 11 83. 3 1.2 6.203E-008 UNITY, REFUEL, DURATION-R6, FREQ-F1B2, PZR-SV-REMOVEDW2, PR0B-W2R6 12 84.5 1.1 5.728E-008 UNITY, FREQ-F1B2, PR0B-W1D6, DR-MT, DURATION-D6, R-B2Wl-XHE-A 13 85.6 1.1 5.724E-008 UNITY, REFUEL, DURATION-R6, PZR-SV-REMOVEDW3, PROB-W3R6, FREQ-F4RHR3, R-R3W3-XHE-F 14 86.7 1.1 5.601E-008 UNITY, LOOPISOLATED2R6, REFUEL, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3, R-R3W2-XHE-F 15 87.7 1. 0 5.438E-008 UNITY, REFUEL, DURATION-R6, FREQ-F1B2,*

/PZR-SV-REMOVEDW4, PR0B-W4R6 16 88.6 0.8 4.464E-008 UNITY, REFUEL, /PZR-SV-REMOVEDW4, PR0B-W4R10, FREQ-F4RHR3, FRAC-POS10, DURATION-R10, R-R3W4-XHE-F 17 89.4 0.7 3.831E-008 UNITY, PR0B-W1D6, FREQ-F5RHR3, DR-MT, DURATION-D6, R-R3Wl-XHE-A 18 90.0 0.6 3.069E-008 UNITY, REFUEL, FREQ-F1B2, PZR-SV-REMOVEDW3, PR0B-W3R10, FRAC-POS10, DURATION-RlO 19 90.5 0.5 2.739E-008 UNITY, PR0B-W1D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-B2Wl-XHE-A 20 91. 0 0.5 2.676E-008 UNITY, REFUEL, PZR-SV-REMOVEDW4, PR0B-W4R10, FREQ-FSRHR3, FRAC-POS10, DURATION-R10, R-R3W4-XHE-F 21 9L4 0.4 2.225E-008 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW3, PR0B-W3R6, FREQ-F2B2 1993/11/24 09:19:27 page 1 D-30

Family->FLOOD/WINDOW Partition Cut Set Report Mincut Upper Bound-> 5.lllE-006 Cut % % Cut End State ->CD This Partition-> 5.lllE-006 No. Total Set Frequency cut Sets 22 91. 8 0.3 1.913E-008 UNITY, REFUEL, PZR-SV-REMOVEDW4, PR0B-W4R10, FREQ-F4RHR3, FRAC-POSlO, DURATION-RlO, R-R3W4-XHE-F 23 92.2 0.3 1.911E-008 UNITY, FREQ-FlB2, PR0B-W2D6, DR-MT, DURATION-D6, R-B2W2-XHE-S 24 92.5 0.3 1.643E-008 UNITY, FREQ-F1B2, PROB-W3D6, DR-MT, DURATION-D6, R-B2W3-XHE-S 25 92.8 0.2 1.473E-008 UNITY, REFUEL, DURATION-R6, PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-F2B2 26 93.1 0.2 1.360E-008 UNITY, PR0B-W1D6, FREQ-F2B2, DR-MT, DURATION-D6, R-B2Wl-XHE-A 27 93.3 0.2 1.291E-008 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW4, PR0B-W4R6, FREQ-F2B2 28 93.6 0.2 1.192E-008 UNITY, REFUEL, DURATION-R6, FREQ-F1B2, PR0B-W1R6, /PZR-SV-REMOVEDWl, R-B2W1-XHE-S/R6 29 93.7 0.1 9.650E-009 UNITY, PR0B-W3D6, FREQ-F7B2, DR-MT, DURATION-D6 30 93.9 0.1 8.896E-009 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW3, PR0B-W3R6, FREQ-FSRHR3, R-R3W3-XHE-F 31 94.1 0.1 7.716E-009 UNITY, REFUEL, /PZR-SV-REMOVEDW4, PR0B-W4R10, FREQ-F7B2, FRAC-POS10, DURATION-RlO 32 94.2 0.1 7.715E-009 UNITY, REFUEL, DURATION-R6, PR0B-W1R6, LOOPISOLATED1R6, /PZR-SV-REMOVEDWl, FREQ-F5RHR3

33 94.4 0.1 7.615E-009 UNITY, LOOPISOLATED2R6, REFUEL, FREQ-F3RHR3, DURATION-R6, /PZR-SV-REMOVEDW2, PR0B-W2R6, LPR-CCF-PG-SUMP2, R-R3W2-XHE-F 34 94.5 0.1 7.289E-009 UNITY, REFUEL, PZR-SV-REMOVEDW3, PR0B-W3R10, FREQ-F2B2, FRAC-POS10, DURATION-RlO 35 94.7 0.1 7.082E-009 UNITY, LOOPISOLATED2R6, REFUEL, FREQ-F3RHR3, DURATION-R6, /PZR-SV-REMOVEDW2, PR0B-W2R6, A-F3R3W2-X-FL-9, R-R3W2-XHE-F 36 94.8 0.1 7.074E-009 UNITY, FREQ-F3RHR3, PR0B-W1D6, A-F3R3Wl-X-FL-9, DR-MT, DURATION-D6, R-B2Wl-XHE-A 37 94.9 0.1 6.543E-009 UNITY, REFUEL, FREQ-F3RHR3, PZR-SV-REMOVEDW4, PR0B-W4R10, FRAC-POS10, A-F3R3W4-X-FL-4, DURATION-RlO 38 95.0 0.1 6.360E-009 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW3, PR0B-W3R6, FREQ-F4RHR3, R-R3W3-XHE-F 39 95.2 0.1 6.195E-009 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-F7B2 40 95.3 0.1 5.891E-009 UNITY, REFUEL, DURATION-R6, PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-FSRHR3, R-R3W2-XHE-F 41 95.4 0.1 5.663E-009 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW3, PR0B-W3R6, A-F3R3W3-X-FL-7 42 95.5 0.1 5.516E-009 UNITY, REFUEL, DURATION-R6, PR0B-W1R6, LOOPISOLATED1R6, /PZR-SV-REMOVEDW1, FREQ-F4RHR3 43 95.6 0.1 5.173E-009 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-F4RHR3, A-F4R3W2-X-S1-8, 1993/11/24 09:19:27 page 2

D-31

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> 5.lllE-006 This Partition-> 5.lllE-006 Cut % % Cut No. Total Set Frequency Cut Sets A-F4R3W2-X-S2-8 44 95.7 0.1 4.903E-009 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-F4RHR3, A-F4R3W2-X-SF-8 45 95.8 0.0 4.677E-009 UNITY, REFUEL, SGS-DRAINED-R, DURATION-R6,

/PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-F4RHR3 46 95.9 0.0 4.662E-009 UNITY, SGA-DRAINED-R, PR0B-W2D6, FREQ-F5RHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 47 96.0 0.0 4.662E-009 UNITY, SGB-DRAINED-R, PR0B-W2D6, FREQ-F5RHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 48 96 .1 0.0 4.537E-009 UNITY, PR0B-W2D6, FREQ-F2B2, DR-MT, DURATION-D6, R-B2W2-XHE-S 49 96.1 0.0 4.269E-009 UNITY, PR0B-W2D6, FREQ-F5RHR3, DR-MT, A-F5R3W2-X-S1-8, A-F5R3W2-X-S2-8, DURATION-D6, R-R3W2-XHE-F so 96.2 0.0 4.212E-009 UNITY, REFUEL, DURATION-R6, PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-F4RHR3, R-R3W2-XHE-F 51 96.3 0.0 4.032E-009 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6, PZR-SV-REMOVEDW2, PR0B-W2R6, LPR-CCF-PG-SUMP2 52 96.4 0.0 4.0lOE-009 UNITY, SGA-DRAINED-R, PR0B-W3D6, FREQ-F5RHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 53 96.5 0.0 4.0lOE-009 UNITY, SGB-DRAINED-R, PR0B-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 54 96.5 0.0 3.903E-009 UNITY, PR0B-W3D6, FREQ-F2B2, DR-MT, DURATION-D6, R-B2W3-XHE-S 55 96.6 0.0 3.672E-009 UNITY, PR0B-W3D6, FREQ-F5RHR3, DR-MT, DURATION-D6, A-F5R3W3-X-S1-7, A-F5R3W3-X-S2-7, R-R3W3-XHE-F 56 96.7 0.0 3.410E-009 UNITY, REFUEL, FREQ-F1B2, /PZR-SV-REMOVEDW3, PR0B-W3R10, FRAC-POS10, DURATION-RlO 57 96.7 0.0 3.333E-009 UNITY, SGA-DRAINED-R, PR0B-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 58 96.8 0.0 ~.333E-009 UNITY, SGB-DRAINED-R, PR0B-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 59 96.9 0.0 3.191E-009 UNITY, FREQ-F3RHR3, SGB-DRAINED-R, PR0B-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 60 96.9 0.0 3.191E-009 UNITY, FREQ-F3RHR3, SGA-DRAINED-R, PR0B-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 61 97.0 0.0 3.0llE-009 UNITY, PR0B-W1D6, FREQ-F7B2, DR-MT, DURATION-D6 62 97.0 0.0 2.968E-009 UNITY, FREQ-F3RHR3, SGB-DRAINED-R, PROB-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 63 97.1 0.0 2.968E-009 UNITY, FREQ-F3RHR3, SGA-DRAINED-R, PR0B-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 64 97 .2 0.0 2.916E-009 UNITY, REFUEL, DURATION-R6, PR0B-W1R6,

/PZR-SV-REMOVEDWl, FREQ-F5RHR3, A-F5R3W1-X-S1-8, A-F5R3W1-X-S2-8 65 97.2 0.0 2.914E-009 UNITY, REFUEL, PZR-SV-REMOVEDW3, PR0B-W3R10, FREQ-FSRHR3, FRAC-POS10, DURATION-RlO, 1993/11/24 09:19:27 page 3 D-32

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> 5.lllE-006 This Partition-> 5.lllE-006 Cut % % Cut No. Total Set Frequency Cut Sets R-R3W3-XHE-F 66 97.3 0.0 2.879E-009 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6, PZR-SV-REMOVEDW3, PROB-W3R6, A-F3R3W3-X-FL-3, R-R3W3-XHE-F 67 97.3 0.0 2.867E-009 UNITY, SGA-DRAINED-R, PROB-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 68 97.4 0.0 2.867E-009 UNITY, SGB-DRAINED-R, PR0B-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 69 97.4 0.0 2.831E-009 UNITY, REFUEL, DURATION-R6, PROB-WlR6,

/PZR-SV-REMOVEDWl, FREQ-F2B2, R-B2Wl-XHE-S/R6 70 97.5 0.0 2.549E-009 UNITY, REFUEL, FREQ-F3RHR3, /PZR-SV-REMOVEDW4, PROB-W4Rl0, FRAC-POS10, A-F3R3W4-X-FL-7, DURATION-RlO, R-R3W4-XHE-F 71 97. 5 0.0 2.357E-009 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-FSRHR3, A-F5R3W2-X-S1-8, A-F5R3W2-X-S2-8, R-R3W2-XHE-F 72 97.6 0. ci 2.313E-009 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW4, PROB-W4R6, FREQ-FSRHR3, R-R3W4-XHE-F 73 97.6 0.0 2.280E-009 UNITY, REFUEL, /PZR-SV-REMOVEDW3, PROB-W3Rl0, FREQ-FSRHR3, FRAC-POS10, DURATION-RlO 74 97.7 0.0 2.230E-009 UNITY, PROB-W2D6, FREQ-FSRHR3, DR-MT, A-FSR3W2-X-SF-8, DURATION~D6, R-R3W2-XHE-F 75 97.7 0.0 2.084E-009 UNITY, REFUEL, PZR-SV-REMOVEDW3, PROB-W3Rl0, FREQ-F4RHR3, FRAC-POS10, DURATION-RlO, R-R3W3-XHE-F 76 97.8 0.0 l.918E-009 UNITY, PR0B-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6, A-FSR3W3-X-SF-7, R-R3W3-XHE-F 77 97. 8 0.0 1 .. 887E-009 UNITY, REFUEL, LPR-MOV-FT-1890B, FREQ-FlB2, PZR-SV-REMOVEDW4, PROB-W4Rl0, FRAC-POS10, DURATION-RlO 78 97.8 0.0 l.872E-009 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-F4RHR3 79 97.9 0.0 l.853E-009 UNITY, PROB-W4D6, FREQ-F7B2, DR-MT, DURATION-D6 80 97.9 0.0 l.768E-009 UNITY, PR0B-W4D6, FREQ-FSRHR3, DR-MT, DURATION-D6, A-FSR3W4-X-SF-7 81 97.9 0.0 l.654E-009 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW4, PROB-W4R6, FREQ-F4RHR3, R-R3W4-XHE-F 82 98.0 0.0 l.638E-009 UNITY, FREQ-F3RHR3, PR0B-WlD6, DR-MT, DURATION-D6, A-F3R3Wl-X-C-8, R-B2Wl-XHE-A 83 98. 0 0.0 l.630E-009 UNITY, REFUEL, /PZR-SV-REMOVEDW3, PR0B-W3Rl0, FREQ-F4RHR3, FRAC-POS10, DURATION-RlO 84 98.0 0.0 l.609E-009 UNITY, LOOPIS0LATED2R6, REFUEL, LPR-MOV-FT-l860B, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW2, PR0B-W2R6 85 98.1 0.0 l.609E-009 UNITY, LOOPISOLATED2R6, REFUEL, LPI-MDP-FS-SilB, FREQ-F3RHR3, DURATION-R6, /PZR-SV-REMOVEDW2, 1993/11/24 09:19:27 page 4

D-33

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> 5.lllE-006 This Partition-> 5.lllE-006 Cut % % Cut No. Total Set Frequency Cut Sets PROB-W2R6 86 98.1 0.0 1.520E-009 UNITY, MSS-AOV-FC-lOlA, MSS-NRV-MA-lOlA, PROB-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 87 98.1 0.0 1.520E-009 UNITY, MSS-AOV-FC-lOlB, MSS-NRV-MA-101B, PROB-W2D6, FREQ-F5RHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 88 98.1 0.0 1.492E-009 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6, PZR-SV-REMOVEDW2, PROB-W2R6, A-F3R3W2-X-FL-4 89 98.2 0.0 1.485E-009 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW4, PROB-W4R6, A-F3R3W4-X-FL-7 90 98.2 0.0 1.425E-009 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6, PROB-WlR6, LOOPISOLATED1R6, /PZR-SV-REMOVEDWl, A-F3R3Wl-X-FL-9 91 98.2 0.0 l.330E-009 UNITY, PROB-W2D6, FREQ-F4RHR3, A-F4R3W2-X-S1-8, A-F4R3W2-X-S2-8, DR-MT, DURATION-D6, R-R3W2-XHE-F 92 98. 3 0.0 l.308E-009 UNITY, MSS-AOV-FC-101B, MSS-NRV-MA-101B, PROB-W3D6, FREQ-F5RHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 93 98. 3 0.0 l.308E-009 UNITY, MSS-AOV-FC-101A, MSS-NRV-MA-101A, PROB-W3D6, FREQ-F5RHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 94 98. 3 0.0 1.297E-009 UNITY, PROB-W2D6, FREQ-F5RHR3, DR-MT, DURATION-D6, D-F5R3W2-XHE, R-R3W2-XHE-F 95 98.3 0.0 1.274E-009 UNITY, FREQ-F3RHR3, PROB-W2D6, A-F3R3W2-X-S1-8, A-F3R3W2-X-S2-8, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 96 98 .4 0.0 1.261E-009 UNITY, PROB-W2D6, FREQ-F4RHR3, A-F4R3W2-X-SF-8, DR-MT, DURATION-D6, R-R3W2-XHE-F 97 98.4 0.0 1.231E-009 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F5RHR3, A-F5R3W2-X-SF-8, R-R3W2-XHE-F 98 98.4 0.0 l.227E-009 UNITY, REFUEL, LPI-MDP-FS-SilB, FREQ-F3RHR3, PZR-SV-REMOVEDW4, PROB-W4Rl0, FRAC-POSlO, DURATION-RlO 99 98.4 0.0 1.lSSE-009 UNITY, FREQ-F3RHR3, PROB-W2D6, A-F3R3W2-X-FL-9, A-F3R3W2-X-S1-8, A-F3R3W2-X-S2-8, DR-MT, DURATION-D6 100 98.4 0.0 1.144E-009 UNITY, PR0B-W3D6, FREQ-F4RHR3, A-F4R3W3-X-S1-7, A-F4R3W3-X-S2-7, DR-MT, DURATION-D6, R-R3W3-XHE-F 101 98.5 0.0 1.138E-009 UNITY, FREQ-F3RHR3, PROB-W2D6, A-F3R3W2-X-SF-8, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 102 98.5 0.0 1.116E-009 UNITY, PR0B-W3D6, FREQ-F5RHR3, DR-MT, DURATION-D6, D-F5R3W3-XHE, R-R3W3-XHE-F 103 98.5 0.0 1.087E-009 UNITY, MSS-AOV-FC-lOlA, MSS-NRV-MA-101A, 1993/11/24 09:19:27 page 5 D-34

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> 5.lllE-006 This Partition-> 5.lllE-006 Cut % % Cut No. Total Set Frequency Cut Sets PR0B-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 104 98.5 0.0 1.087E-009 UNITY, MSS-AOV-FC-101B, MSS-NRV-MA-101B, PR0B-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 105 98.6 0.0 1.084E-009 UNITY, PR0B-W3D6, FREQ-F4RHR3, A-F4R3W3-X-SF-7, DR-MT, DURATION-D6, R-R3W3-XHE-F 106 98.6 0.0 1.073E-009 UNITY, LOOPISOLATED2R6, REFUEL, PPS-MOV-FT-1536, FREQ-F3RHR3, DURATION-R6, PORV-PATH-CLSD,

/PZR-SV-REMOVEDW2, PR0B-W2R6 107 98.6 0.0 1.058E-009 UNITY, FREQ-F3RHR3, PR0B-W2D6, A-F3R3W2-X-FL-9, A-F3R3W2-X-SF-8, DR-MT, DURATION-D6 1Q8 98.6 0.0 1.041E-009 UNITY, MSS-AOV-FC-101B, FREQ-F3RHR3, MSS-NRV-MA-101B, PR0B-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 109 98.6 0.0 1.041E-009 UNITY, MSS-AOV-FC-101A, FREQ-F3RHR3, MSS-NRV-MA-101A, PR0B-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 110 98.7 0.0 1.016E-009 UNITY, FREQ-F3RHR3, SGB-DRAINED~R, PR0B-W3D6, A-F3R3W3-X-FL-3, DR-MT, DURATION-D6 111 98.7 0.0 1.016E-009 UNITY, FREQ-F3RHR3, SGA-DRAINED-R, PR0B-W3D6, A-F3R3W3-X-FL-3, DR-MT, DURATION-D6 112 98. 7 0.0 9.912E-010 UNITY, REFUEL, DURATION-R6, PZR-SV-REMOVEDW4, PR0B-W4R6, FREQ-F5RHR3, R-R3W4-XHE-F 113 98.7 0.0 9.678E-010 UNITY, MSS-AOV-FC-101B, FREQ-F3RHR3, MSS-NRV-MA-101B, PR0B-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 114 98.7 0.0 9.678E-010 UNITY, MSS-AOV-FC-101A, FREQ-F3RHR3, MSS-NRV-MA-101A, PR0B-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 115 98.8 0.0 9.349E-010 UNITY, MSS-AOV-FC-101A, MSS-NRV-MA-101A, PR0B-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 116 98.8 0.0 9.349E-010 UNITY, MSS-AOV-FC-101B, MSS-NRV-MA-101B, PR0B-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 117 98.8 0.0 9.290E-010 UNITY, REFUEL, SGS-DRAINED-R, DURATION-R6,

/PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-FSRHR3, R-R3W2-XHE-F 118 98.8 0.0 9.270E-010 UNITY, PR0B-W4D6, FREQ-F4RHR3, DR-MT, A-F4R3W4-X-SF-7, DURATION-D6 119 98.8 0.0 9.266E-010 UNITY, REFUEL, DURATION-R6, PR0B-W1R6,

/PZR-SV-REMOVEDWl, FREQ-F4RHR3, A-F4R3W1-X-S1-8, A-F4R3W1-X-S2-8 120 98.8 0.0 9.138E-010 UNITY, LOOPIS0LATED2R6, REFUEL, FREQ-F3RHR3, DURATION-R6, /PZR-SV-REMOVEDW2, PR0B-W2R6, A-F3R3W2-X-C-8, R-R3W2-XHE-F 1993/11/24 09:19:27 page 6 D-35

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> 5.lllE-006 This Partition-> 5.lllE-006 cut % % cut No. Total Set Frequency Cut Sets 121 98.9 0.0 8.603E-010 UNITY, FREQ-F3RHR3, PROB-W2D6, D-F3R3W2-XHE, DR-MT, DURATION-D6 122 98.9 0.0 8.557E-010 UNITY, PROB-W4D6, FREQ-F5RHR3, DR-MT, DURATION-D6, A-FSR3W4-X-Sl-7, A-F5R3W4-X-S2-7 123 98.9 0.0 8.099E-010 UNITY, REFUEL, /PZR-SV-REMOVEDW3, PROB-W3R10, FREQ-F2B2, FRAC-POSlO, DURATION-RlO 124 98.9 0.0 7.830E-010 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, PROB-W4D6, FREQ-F5RHR3, DR-MT, DURATION-D6 125 98.9 0.0 7.SSOE-010 UNITY, REFUEL, D-F1B2W4-XHE, FREQ-F1B2, PZR-SV-REMOVEDW4, PROB-W4Rl0, FRAC-POSlO, DURATION-RlO 126 98.9 0.0 7.399E-010 UNITY, FREQ-F3RHR3, PR0B-W3D6, D-F3R3W3-XHE, DR-MT, DURATION-D6 127 98.9 0.0 7.381E-010 UNITY, REFUEL, FREQ-F3RHR3, PZR-SV-REMOVEDW3, PROB-W3R10, A-F3R3W3-X-FL-3, FRAC-POSlO, DURATION-RlO 128 99.0 0.0 7.225E-010 UNITY, REFUEL, DURATION-R6, A-F1B2W4-X-G-4, FREQ-F1B2, PZR-SV-REMOVEDW4, PROB-W4R6 129 99.0 0.0 7.163E-010 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F5RHR3, D-F5R3W2-XHE, R-R3W2-XHE-F 130 99.0 0.0 7.087E-010 UNITY, REFUEL, DURATION-R6, PZR-SV-REMOVEDW4, PROB-W4R6, FREQ-F4RHR3, R-R3W4-XHE-F 131 99.0 0.0 7.033E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6, A-F3R3W2-X-S1-8, A-F3R3W2-X-S2-8, LPR-CCF-PG-SUMP2 132 99.0 0.0 6.733E-010 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, PROB-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 133 99.0 0.0 6.703E-010 UNITY, CON-VFC-RP-COREM, L00PISOLATED2R6, REFUEL, FREQ-F3RHR3, DURATION-R6, OSR-TRA-MA, ISR-TRA-MA, /PZR-SV-REMOVEDW2, PROB-W2R6 134 99.0 0.0 6.540E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6, A-F3R3W2-X-FL-9, A-F3R3W2-X-S1-8, A-F3R3W2-X-S2-8 135 99.1 0.0 6.359E-010 UNITY, REFUEL, SGS-DRAINED-R, FREQ-F3RHR3, DURATION-R6, /PZR-SV-REMOVEDW2, PROB-W2R6, LPR-CCF-PG-SUMP2 136 99.1 0.0 6.282E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6, A-F3R3W2-X-SF-8, LPR-CCF-PG-SUMP2 137 99.1 0.0 5.957E-010 UNITY, FREQ-F3RHR3, PR0B-W1D6, D-F3R3Wl-XHE, DR-MT, DURATION-D6 138 99.1 0.0 S.942E-010 UNITY, AFW-MDP-MA-FW3A, AFW-MDP-MA-FW3B, REFUEL, DURATI0N-R6, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3 139 99.1 0.0 S.915E-010 UNITY, REFUEL, DURATION-R6, SGB-DRAINED-R, 1993/11/24 09:19:27 page 7 D-36

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> 5.lllE-006 This Partition-> 5.lllE-006 Cut % % Cut No. Total Set Frequency Cut Sets PR0B-W1R6, /PZR-SV-REMOVEDWl, FREQ-FSRHR3 140 99.1 0.0 5.915E-010 UNITY, REFUEL, DURATION-R6, SGC-DRAINED-R, PR0B-W1R6, /PZR-SV-REMOVEDWl, FREQ-FSRHR3 141 99.1 0.0 5.915E-010 UNITY, REFUEL, DURATION-R6, SGA-DRAINED-R, PR0B-W1R6, /PZR-SV-REMOVEDWl, FREQ-FSRHR3 142 99.1 0.0 5.914E-010 UNITY, REFUEL, SGS-DRAINED-R, FREQ-F3RHR3, DURATION-R6, /PZR-SV-REMOVEDW2, PR0B-W2R6, A-F3R3W2-X-FL-9 143 99.2 0.0 S.842E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW2, PR0B-W2R6, A-F3R3W2-X-FL-9, A-F3R3W2-X-SF-8 144 99.2 0.0 S.791E-010 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, PR0B-W3D6, FREQ-F5RHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 145 99.2 0.0 5.635E-010 UNITY, AFW-CKV-00-CV142, REFUEL, DURATION-R6,

/PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-F4RHR3 146 99.2 0.0 5.598E-010 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, PR0B-W4D6, FREQ-F4RHR3, DR-MT, DURATION-D6 147 99.2 0.0 5. 068E-010 UNITY, MSS-NRV-MA-101A, MSS-AOV-.MA-lOlA, PR0B-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 148 99.2 0.0 S.068E-010 UNITY, MSS-NRV-MA-101B, MSS-AOV-MA-101B, PR0B-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 149 99.2 0.0 4.924E-010 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW3, PR0B-W3R6, FREQ-F7B2 150 99.2 0.0 4.839E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6, PZR-SV-REMOVEDW2, PR0B-W2R6, A-F3R3W2-X-C-3 151 99.2 0.0 4.814E-010 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, PR0B-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 152 99.2 0.0 4.750E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6, D-F3R3W2-XHE 153 99. 3 0.0 4.608E-010 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, FREQ-F3RHR3, PR0B-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 154 99.3 0.0 4.483E-010 UNITY, REFUEL, LPR-MOV-FT-1890B, PZR-SV-REMOVEDW4, PR0B-W4R10, FREQ-F2B2, FRAC-POS10, DURATION-RIO 155 99.3 o.o 4.372E-010 UNITY, REFUEL, DURATION-R6, PR0B-W1R6,

/PZR-SV-REMOVEDWl, FREQ-FSRHR3, A-FSR3Wl-X-SF-8 156 99.3 0.0 4.359E-010 UNITY, MSS-NRV-MA-101B, MSS-AOV-MA-101B, PR0B-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 157 99.3 0.0 4.359E-010 UNITY, MSS-NRV-MA-101A, MSS-AOV-MA-101A, PR0B-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 1993/11/24 09:19:27 page 8 D-37

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> 5.lllE-006 This Partition-> 5.lllE-006 Cut % % Cut No. Total Set Frequency Cut Sets 158 99.3 0.0 4.286E-010 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, FREQ-F3RHR3, PR0B-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 159 99.3 0.0 4.229E-010 UNITY, REFUEL, DURATION-R6, SGB-DRAINED-R, PR0B-W1R6, /PZR-SV-REMOVEDWl, FREQ-F4RHR3 160 99.3 0.0 4.229E-010 UNITY, REFUEL, DURATION-R6, SGC-DRAINED-R, PR0B-W1R6, /PZR-SV-REMOVEDWl, FREQ-F4RHR3 161 99.3 0.0 4.229E-010 UNITY, REFUEL, DURATION-R6, SGA-DRAINED-R, PR0B-W1R6, /PZR-SV-REMOVEDWl, FREQ-F4RHR3 162 99.3 0.0 4.152E-010 UNITY, REFUEL, LPR-MOV-PG-1890B, FREQ-FlB2, PZR-SV-REMOVEDW4, PROB-W4Rl0, FRAC-POSlO, DURATION-RlO 163 99.3 0.0 4.140E-010 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, PROB-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 164 99.3 0.0 4.054E-010 UNITY, FREQ-F3RHR3, PROB-W3D6, A-F3R3W3-X-FL-3, A-F3R3W3-X-Sl-7, A-F3R3W3-X-S2-7, DR-MT, DURATION-D6 165 99.3 0.0 3.960E-010 UNITY, LOOPISOLATED2R6, REFUEL, LPR-MOV-FT-1862B, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6, R-R3W2-XHE-F 166 99.4 0.0 3.953E-010 UNITY, MSS-AOV-FC-lOlA, SSHR-AOV-XHE-105, PR0B-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 167 99.4 0.0 3.953E-010 UNITY, MSS-AOV-FC-lOlB, SSHR-AOV-XHE-105, PROB-W2D6, FREQ-F5RHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 168 99.4 0.0 3.884E-010 UNITY, REFUEL, DURATION-R6, FREQ-FlB2, PROB-WlR6, PZR-SV-REMOVEDWl 169 99.4 0.0 3.830E-010 UNITY, FREQ-F3RHR3, SGB-DRAINED-R, PROB-W2D6, DR-MT, DURATION-D6, A-F3R3W2-X-C-8 170 99.4 0.0 3.830E-010 UNITY, FREQ-F3RHR3, SGA-DRAINED-R, PR0B-W2D6, DR-MT, DURATION-D6, A-F3R3W2-X-C-8 171 99.4 0.0 3.767E-010 UNITY, REFUEL, DURATION-R6, PZR-SV-REMOVEDW3, PR0B-W3R6, FREQ-F7B2, A-F7B2W3-X-G-4 172 99.4 0.0 3*. 723E-010 UNITY, FREQ-F3RHR3, PR0B-W1D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMPl, R-B2Wl-XHE-A 173 99.4 0.0 3.717E-010 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-FSRHR3, R-R3W2-XHE-F 174 99.4 0.0 3.623E-010 UNITY, MSS-NRV-MA-101A, MSS-AOV-MA-lOlA, PR0B-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 175 99.4 0.0 3.623E-010 UNITY, MSS-NRV-MA-101B, MSS-AOV-MA-101B, PR0B-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 176 99.4 0.0 3.621E-010 UNITY, FREQ-F3RHR3, PR0B-W3D6, A-F3R3W3-X-FL-3, 1993/11/24 09:19:27 page 9 D-38 L

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> 5.lllE-006 This Partition-> S.lllE-006 Cut % % Cut No. Total Set Frequency Cut Sets A-F3R3W3-X-SF-7, DR-MT, DURATION-D6 177 99.4 0.0 3.494E-010 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-F4RHR3, D-F4R3W2-XHE 178 99.4 0.0 3.469E-010 UNITY, FREQ-F3RHR3, MSS-NRV-MA-101B, MSS-AOV-MA-101B, PROB-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 179 99.5 0.0 3.469E-010 UNITY, FREQ-F3RHR3, MSS-NRV-MA-101A, MSS-AOV-MA-lOlA, PR0B-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 180 99.5 0.0 3.400E-010 UNITY, MSS-AOV-FC-101B, SSHR-AOV-XHE-105, PR0B-W3D6, FREQ-F5RHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 181 99.5 0.0 3.400E-010 UNITY, MSS-AOV-FC-lOlA, SSHR-AOV-XHE-105, PR0B-W3D6, FREQ-F5RHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 182 99.5 0.0 3.398E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6, PZR-SV-REMOVEDW3, PROB-W3R6, D-F3R3W3-XHE 183 99.5 o.o 3.343E-010 UNITY, REFUEL, DURATION-R6, PROB-WlR6,

/PZR-SV-REMOVEDWl, FREQ-F5RHR3, D-F5R3Wl-XHE 184 99.5 0.0 3.312E-010 UNITY, MSS-AOV-FC-lOlB, FREQ-F3RHR3, MSS-NRV-MA-lOlB, PR0B-W3D6, A-F3R3W3-X-FL-3, DR-MT, DURATION-D6 185 99.5 0.0 3.312E-010 UNITY, MSS-AOV-FC-lOlA, FREQ-F3RHR3, MSS-NRV-MA-lOlA, PROB-W3D6, A-F3R3W3-X-FL-3, DR-MT, DURATION-D6 186 99.5 0.0 3.299E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6,.

PR0B-W1R6, LOOPIS0LATED1R6, /PZR-SV-REMOVEDWl, A-F3R3Wl-X-C-8 187 99.5 0.0 3.226E-010 UNITY, FREQ-F3RHR3, MSS-NRV-MA-101B, MSS-AOV-MA-lOlB, PR0B-W2D6, A-F3R3W2-X~FL-9, DR-MT, DURATION-D6 188 99.5 0.0 3.226E-010 UNITY, FREQ-F3RHR3, MSS-NRV-MA-101A, MSS-AOV-MA-lOlA, PR0B-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 189 99.5 0.0 3.116E-010 UNITY, MSS-NRV-MA-lOlA, MSS-AOV-MA-lOlA, PR0B-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 190 99.5 0.0 3.116E-010 UNITY, MSS-NRV-MA-101B, MSS-AOV-MA-lOlB, PR0B-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 191 99.5 0.0 3.041E-010 UNITY, MSS-AOV-FC-lOlA, CIR-COND-UNAVLBL, PR0B-W2D6, FREQ-F5RHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 192 99.5 0.0 3.041E-010 UNITY, MSS-AOV-FC-101B, CIR-COND-UNAVLBL, PR0B-W2D6, FREQ-F5RHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 193 99.5 0.0 2.981E-010 UNITY, REFUEL, DURATION-R6, SGB-DRAINED-R, 1993/11/24 09:19:27 page 10 D-39

Family->FLOOD/WINDOW Cut % % Cut Partition Cut Set Report Mincut Upper Bound-> 5.lllE-006 End State ->CD This Partition-> 5.lllE-006 No. Total Set Frequency Cut Sets SGC-DRAINED-R, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3 194 99.5 0.0 2.981E-010 UNITY, REFUEL, DURATION-R6, SGA-DRAINED-R, SGB-DRAINED-R, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3 195 99.6 0.0 2.981E-010 UNITY, REFUEL, DURATION-R6, SGA-DRAINED-R, SGC-DRAINED-R, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3 196 99.6 0.0 2.858E-010 UNITY, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW4, PROB-W4R6, FREQ-F7B2 197 99.6 0.0 2.826E-010 UNITY, MSS-AOV-FC-lOlA, SSHR-AOV-XHE-105, PROB-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 198 99.6 0.0 2.826E-010 UNITY, MSS-AOV-FC-lOlB, SSHR-AOV-XHE-105, PROB-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 199 99.6 0.0 2.706E-010 UNITY, MSS-AOV-FC-lOlB, SSHR-AOV-XHE-105, FREQ-F3RHR3, PROB-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 200 99.6 0.0 2.706E-010 UNITY, MSS-AOV-FC-lOlA, SSHR-AOV-XHE-105, FREQ-F3RHR3, PROB-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 201 99.6 0.0 2.615E-010 UNITY, MSS-AOV-FC-101B, CIR-COND-UNAVLBL, PROB-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 202 99.6 0.0 2.615E-010 UNITY, MSS-AOV-FC-101A, CIR-COND-UNAVLBL, PROB-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 203 99.6 0.0 2.59BE-010 UNITY, REFUEL, DURATION-R6, PROB-W1R6, PZR-SV-REMOVEDWl, FREQ-FSRHR3 204 99.6 0.0 2.574E-010 UNITY, REFUEL, DURATION-R6, PROB-W1R6,

/PZR-SV-REMOVEDW1, FREQ-F4RHR3, A-F4R3Wl-X-SF-B 205 99.6 0.0 2.544E-010 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, REFUEL, FREQ-F3RHR3, DURATION-R6, /PZR-SV-REMOVEDW2, PROB-W2R6, LPR-CCF-PG-SUMP2 206 99.6 0.0 2.516E-010 UNITY, MSS-AOV-FC-101B, SSHR-AOV-XHE-105, FREQ-F3RHR3, PROB-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 207 99.6 0.0 2.516E-010 UNITY, MSS-AOV-FC-101A, SSHR-AOV-XHE-105, FREQ-F3RHR3, PROB-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 208 99.6 0.0 2.486E-010 UNITY, AFW-MDP-MA-FW3A, AFW-MDP-MA-FW3B, PROB-W4D6, FREQ-FSRHR3, DR-MT, DURATION-D6 209 99.6 0.0 2.431E-010 UNITY, MSS-AOV-FC-101A, SSHR-AOV-XHE-105, PROB-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 210 99.6 0.0 2.431E-010 UNITY, MSS-AOV-FC-101B, SSHR-AOV-XHE-105, 1993/11/24 09:19:27 page 11 D-40

Partition cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> 5.111E-006 This Partition-> 5.111E-006 Cut % % Cut No. Total Set Frequency Cut Sets PROB-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 211 99.6 0.0 2.424E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6, PZR-SV-REMOVEDW4, PROB-W4R6, A-F3R3W4-X-FL-4 212 99. 6 0.0 2.413E-010 UNITY, LOOPISOLATED2R6, REFUEL, LPI-CCF-FS-SI1AB, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6 213 99.6 0.0 2.393E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6, PROB-W1R6, /PZR-SV-REMOVEDW1, A-F3R3W1-X-FL-9, A-F3R3Wl-X-S1-8, A-F3R3W1-X-S2-8 214 99.6 0.0 2.366E-010 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, REFUEL, FREQ-F3RHR3, DURATION-R6, /PZR-SV-REMOVEDW2, PROB-W2R6, A-F3R3W2-X-FL-9 215 99.7 0.0 2.357E-010 UNITY, PROB-W4D6, SGS-DRAINED-CSD, FREQ-F5RHR3, DR-MT, DURATION-D6 216 99.7 0.0 2.357E-010 UNITY, AFW-CKV-00-CV142, PROB-W4D6, FREQ-FSRHR3, DR-MT, DURATION-D6 217 99.7 0.0 2.33SE-010 UNITY, REFUEL, LPI-MDP-FS-SilB, FREQ-F3RHR3, DURATION-R6, PZR-SV-REMOVEDW3, PR0B-W3R6, R-R3W3-XHE-F 218 99.7 0.0 2.216E-010 UNITY, PROB-W4D6, FREQ-F5RHR3, DR-MT, DURATION-D6, D-FSR3W4-XHE 219 99.7 0.0 2.174E-010 UNITY, MSS-AOV-FC-101A, CIR-COND-UNAVLBL, PR0B-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 220 99.7 0.0 2.174E-010 UNITY, MSS-AOV-FC-101B, CIR-COND-UNAVLBL, PR0B-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 221 99.7 0.0 2.164E-010 UNITY, REFUEL, DURATION-R6, SAS-CPS-FR-1SAC1, IAS-CPS-FS-IAC-1, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3 222 99.7 0.0 2.164E-010 UNITY, REFUEL, DURATION-R6, SAS-CPS-FR-2SAC1, IAS-CPS-FS-IAC-1, /PZR-SV-REMOVEDW2, PROB-W2R6,*

FREQ-F4RHR3 223 99.7 0.0 2.137E-010 UNITY, AFW-MDP-MA-FW3A, AFW-MDP-MA-FW3B, PROB-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 224 99.7 0.0 2.1348-010 UNITY, REFUEL, SGS-DRAINED-R, DURATION-R6, PROB-WlR6, /PZR-SV-REMOVEDWl, FREQ-FSRHR.3 225 99.7 0.0 2.103E-010 UNITY, REFUEL, DURATION-R6, PZR-SV-REMOVEDW4, PROB-W4R6, A-F2B2W4-X-G-4, FREQ-F2B2 226 99.7 0.0 2.097E-010 UNITY, REFUEL, LPR-MOV-FT-1862B, FREQ-F3RHR3, DURATION-R6, PZR-SV-REMOVEDW2, PR0B-W2R6 227 99.7 0.0 2.0BlE-010 UNITY, MSS-AOV-FC-101B, FREQ-F3RHR3, CIR-COND-UNAVLBL, PROB-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 228 99.7 0.0 2.081E-010 UNITY, MSS-AOV-FC-101A, FREQ-F3RHR3, 1993/11/24 09:19:27 page 12 D-41

Partition Cut Set Report Farnily->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> 5.lllE-006 This Partition-> 5.lllE-006 Cut % % Cut No. Total Set Frequency Cut Sets CIR-COND-UNAVLBL, PR0B-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 229 99.7 0.0 2.076E-010 UNITY, PROB-W4D6, FREQ-F4RHR3, A-F4R3W4-X-Sl-7, DR-MT, A-F4R3W4-X-S2-7, DURATION-D6 230 99.7 0.0 2.061E-010 UNITY, REFUEL, FREQ-F3RHR3, /PZR-SV-REMOVEDW3, PR0B-W3R10, A-F3R3W3-X-FL-7, FRAC-POS10, DURATION-R10 231 99.7 0.0 2.027E-010 UNITY, AFW-CKV-00-CV142, PR0B-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 232 99.7 0.0 2.027E-010 UNITY, PROB-W2D6, SGS-DRAINED-CSD, FREQ-FSRHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 233 99.7 0.0 2.021E-010 UNITY, REFUEL, DURATION-R6, PR0B-W1R6,

/PZR-SV-REMOVEDWl, FREQ-F7B2 234 99.7 0.0 l.972E-010 UNITY, AFW-CCF-FS-FW3AB, REFUEL, DURATION-R6,

/PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-F4RHR3 235 99.7 0.0 1.936E-010 UNITY, LPR-MOV-FT-1862B, FREQ-F3RHR3, PROB-W1D6, DR-MT, DURATION-D6, R-B2W1-XHE-A 236 99.7 0.0 1.936E-010 UNITY, MSS-AOV-FC-101B, FREQ-F3RHR3, CIR-COND-UNAVLBL, PR0B-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 237 99.7 0.0 l.936E-010 UNITY, MSS-AOV-FC-101A, FREQ-F3RHR3, CIR-COND-UNAVLBL, PR0B-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 238 99.7 0.0 1.929E-010 UNITY, REFUEL, MSS-AOV-FC-101B, DURATION-R6, MSS-NRV-MA-101B, PR0B-W1R6, /PZR-SV-REMOVEDWl, FREQ-FSRHR3 239 99.7 0.0 l.929E-010 UNITY, REFUEL, MSS-AOV-FC-101C, DURATION-R6, MSS-NRV-MA-101C, PR0B-W1R6, /PZR-SV-REMOVEDW1, FREQ-FSRHR3 240 99.8 0.0 l.929E-010 UNITY, REFUEL, MSS-AOV-FC-101A, DURATION-R6, MSS-NRV-MA-101A, PR0B-W1R6, /PZR-SV-REMOVEDWl, FREQ-FSRHR3 241 99.8 0.0 l.900E-010 UNITY, FREQ-FlB2, PR0B-W4D6, DR-MT, DURATION-D6, R-B2W4-XHE-S 242 99.8 0.0 l.870E-010 UNITY, MSS-AOV-FC-lOlA, CIR-COND-UNAVLBL, PR0B-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 243 99.8 0.0 1.870E-010 UNITY, MSS-AOV-FC-101B, CIR-COND-UNAVLBL, PR0B-W3D6, FREQ-F4RHR3, DR-MT,. DURATION-D6, R-R3W3-XHE-F 244 99.8 0.0 1.857E-010 UNITY, REFUEL, DURATI0N-R6, PR0B-W1R6, PZR-SV-REMOVEDW1, FREQ-F4RHR3 245 99.8 0.0 l.840E-010 UNITY, REFUEL, LPI-CCF-FS-SI1AB, FREQ-F3RHR3, PZR-SV-REMOVEDW4, PR0B-W4R10, FRAC-POS10, DURATION-R10 246 99.8 0.0 l.838E-010 UNITY, AFW-MDP-MA-FW3A, AFW-MDP-MA-FW3B, PROB-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6, 1993/11/24 09:19:27 page 13 D-42

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> 5.lllE-006 This Partition-> 5.lllE-006 Cut % % Cut No. Total Set Frequency Cut Sets R-R3W3-XHE-F 247 99.8 0.0 1. 827E-010 UNITY, REFUEL, LPI-MDP-FS-SilB, FREQ-F3RHR3, DURATION-R6, /PZR-SV-REMOVEDW3, PR0B-W3R6 248 99.8 0.0 l.821E-010 UNITY, REFUEL, LPI-MDP-FS-SilB, FREQ-F3RHR3,

/PZR-SV-REMOVEDW4, PROB-W4Rl0, FRAC-POSlO, DURATION-RlO, R-R3W4-XHE-F 249 99.8 0.0 l.793E-010 UNITY, REFUEL, PZR-SV-REMOVEDW4, PROB-W4Rl0, D-F2B2W4-XHE, FREQ-F2B2, FRAC-POS10, DURATION-RlO 250 99.8 0.0 l.777E-010 UNITY, AFW-MDP-MA-FW3A, AFW-MDP-MA-FW3B, PR0B-W4D6, FREQ-F4RHR3, DR-MT, DURATION-D6 251 99.8 0.0 l.744E-010 UNITY, PR0B-W3D6, SGS-DRAINED-CSD, FREQ-F5RHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 252 99.8 0.0 l.744E-010 UNITY, AFW-CKV-00-CV142, PROB-W3D6, FREQ-F5RHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 253 99.8 0.0 l.685E-010 UNITY, PR0B-W4D6, SGS-DRAINED-CSD, FREQ-F4RHR3, DR-MT, DURATION-D6 254 99.8 0.0 l.685E-010 UNITY, AFW-CKV-OO-CV142, PROB-W4D6, FREQ-F4RHR3, DR-MT, DURATION-D6 255 99.8 0.0 l.659E-010 UNITY, LPR-MOV-FT-1862B, FREQ-F3RHR3, SGB-DRAINED-R, PROB-W2D6, DR-MT, DURATION-D6 256 99.8 0.0 l.659E-010 UNITY, LPR-MOV-FT-1862B, FREQ-F3RHR3, SGA-DRAINED-R, PROB-W2D6, DR-MT, DURATION-D6 257 99.8 0.0 l.648E-010 UNITY, REFUEL, MSS-AOV-FC-101B, MSS-AOV-FC-lOlC, SSHR-AOV-XHE-105, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3 258 99.8 0.0 l.648E-010 UNITY, REFUEL, MSS-AOV-FC-101A, MSS-AOV-FC-lOlB, SSHR-AOV-XHE-105, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3 259 99.8 0.0 l.6~8E-010 UNITY, REFUEL, MSS-AOV-FC-lOlA, MSS-AOV-FC-lOlC, SSHR-AOV-XHE-105, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3 260 99.8 0.0 l.636E-010 UNITY, REFUEL, LPR-CCF-FT-890AB, FREQ-F1B2, PZR-SV-REMOVEDW4, PROB-W4Rl0, FRAC-POS10, DURATION-RlO 261 99.8 0.0 l.528E-010 UNITY, FREQ-F3RHR3, PR0B-W2D6, A-F3R3W2-X-S1-8, A-F3R3W2-X-S2-8, DR-MT, DURATION-D6, A-F3R3W2-X-C-8 262 99.8 0.0 l.528E-010 UNITY, AFW-MDP-MA-FW3A, AFW-MDP-MA-FW3B, PROB-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 263 99.8 0.0 l.526E-010 UNITY, REFUEL, SGS-DRAINED-R, DURATI0N-R6, PROB-WlR6, /PZR-SV-REMOVEDWl, FREQ-F4RHR3 264 99.8 0.0 l.467E-010 UNITY, AFW-MDP-FS-FW3A, AFW-MDP-MA-FW3B, FREQ-F3RHR3, PR0B-W3D6, A-F3R3W3-X-FL-3, DR-MT, DURATION-D6 265 99.8 0.0 l.465E-010 UNITY, REFUEL, DURATION-R6, AFW-MOV-CC-151, 1993/11/24 09:19:27 page 14 D-43

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> 5.lllE-006 This Partition-> 5.lllE-006 cut % % cut No. Total Set Frequency Cut Sets

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3 266 99.8 0.0 1.463E-010 UNITY, AFW-MDP-MA-FW3A, AFW-MDP-MA-FW3B, FREQ-F3RHR3, PROB-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 267 99.8 0.0 1. 449E-010 UNITY, AFW-CKV-00-CV142, PROB-W2D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 268 99.8 0.0 1. 449E-010 UNITY, PROB-W2D6, SGS-DRAINED-CSD, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 269 99.8 0.0 1.394E-010 UNITY, LOOPIS0LATED2R6, REFUEL, LPR-CCF-FT-860AB, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6 270 99.9 0.0 1. 394E-010 UNITY, LOOPIS0LATED2R6, REFUEL, LPR-CCF-FT-862AB, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6 271 99.9 0.0 1. 394E-010 UNITY, LOOPIS0LATED2R6, REFUEL, LPR-CCF-FT-890AB, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW2, PROB-W2R6 272 99.9 0.0 1.388E-010 UNITY, FREQ-F3RHR3, PROB-W2D6, SGS-DRAINED-CSD, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 273 99.9 0.0 1.388E-010 UNITY, AFW-CKV-OO-CV142, FREQ-F3RHR3, PR0B-W2D6, DR-MT, DURATION-D6, LPR-CCF-PG-SUMP2 274 99.9 0.0 1. 379E-010 UNITY, REFUEL, MSS-AOV-FC-101B, DURATION-R6, MSS-NRV-MA-101B, PROB-W1R6, /PZR-SV-REMOVEDW1, FREQ-F4RHR3 275 99.9 0.0 1. 379E-010 UNITY, REFUEL, MSS-AOV-FC-101C, DURATION-R6, MSS-NRV-MA-101C, PROB-W1R6, /PZR-SV-REMOVEDW1, FREQ-F4RHR3 276 99.9 0.0 1. 379E-010 UNITY, REFUEL, MSS-AOV-FC-101A, DURATION-R6, MSS-NRV-MA-lOlA, PROB-W1R6, /PZR-SV-REMOVEDW1, FREQ-F4RHR3 277 99.9 0.0 1. 365E-010 UNITY, FREQ-F3RHR3, PROB-W2D6, A-F3R3W2-X-SF-8, DR-MT, DURATION-D6, A-F3R3W2-X-C-8 278 99.9 0.0 1. 361E-010 UNITY, AFW-MDP-MA-FW3A, AFW-MDP-MA-FW3B, FREQ-F3RHR3, PR0B-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 279 99.9 0.0 1. 336E-010 UNITY, REFUEL, FREQ-F3RHR3, /PZR-SV-REMOVEDW4, PROB-W4R10, FRAC-POS10, D-F3R3W4-XHE, DURATION-R10 280 99.9 0.0 1.318E-010 UNITY, SSHR-AOV-XHE-105, MSS-AOV-MA-lOlA, PR0B-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 281 99.9 0.0 1. 318E-010 UNITY, SSHR-AOV-XHE-105, MSS-AOV-MA-101B, PR0B-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 282 99.9 0.0 1. 314E-010 UNITY, AFW-MDP-MA-FW3A, AFW-MDP-MA-FW3B, PR0B-W3D6, FREQ-F4RHR3, DR-MT, DURATION~D6, R-R3W3-XHE-F 1993/11/24 09:19:27 page 15 D-44

Family->FLOOD/WINDOW Partition Cut Set Report Mincut Upper Bound-> 5.lllE-006 Cut % % Cut End State ->CD This Partition-> 5.lllE-006 No. Total Set Frequency Cut Sets 283 99.9 0.0 1.290E-010 UNITY, FREQ-F3RHR3, PR0B-W2D6, SGS-DRAINED-CSD, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 284 99.9 0.0 1.290E-010 UNITY, AFW-CKV-OO-CV142, FREQ-F3RHR3, PR0B-W2D6, A-F3R3W2-X-FL-9, DR-MT, DURATION-D6 285 99.9 0.0 1.268E-010 UNITY, REFUEL, MSS-AOV-FC-lOlA, MSS-AOV-FC-101C, DURATION-R6, CIR-COND-UNAVLBL,

/PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-F4RHR3 286 99.9 0.0 1.268E-010 UNITY, REFUEL, MSS-AOV-FC-101B, MSS-AOV-FC-101C, DURATION-R6, CIR-COND-UNAVLBL,

/PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-F4RHR3 287 99.9 0.0 1.268E-010 UNITY, REFUEL, MSS-AOV-FC-lOlA, MSS-AOV-FC-101B, DURATI0N-R6, CIR-COND-UNAVLBL,

/PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-F4RHR3 288 99.9 0.0 1.249E-010 UNITY, MSS-AOV-FC-101B, FREQ-F3RHR3, MSS-NRV-MA-101B, PROB-W2D6, DR-MT, DURATION-D6, A-F3R3W2-X-C-8 289 99.9 0.0 1.249E-010 UNITY, MSS-AOV-FC-lOlA, FREQ-F3RHR3, MSS-NRV-MA-101A, PROB-W2D6, DR-MT, DURATION-D6, A-F3R3W2-X-C-8 290 99.9 0.0 l.247E-010 UNITY, SGA-DRAINED-R, SGB-DRAINED-R, PROB-W4D6, FREQ-F5RHR3, DR-MT, DURATION-D6

.291 99.9 0.0 1.247E-010 UNITY, AFW-CKV-00-CV142, PROB-W3D6, FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 292 99.9 0.0 1.247E-010 UNITY, PR0B-W3D6, SGS-DRAINED-CSD; FREQ-F4RHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 293 99.9 0.0 l.210E-010 UNITY, REFUEL, LPR-MOV-FT-1860B, FREQ-F3RHR3, DURATION-R6, PZR-SV-REMOVEDW2, PROB-W2R6 294 99.9 0.0 1.210E-010 UNITY, REFUEL, LPI-MDP-FS-SilB, FREQ-F3RHR3, DURATION-R6, PZR-SV-REMOVEDW2, PR0B-W2R6 295 99.9 0.0 1.194E-010 UNITY, LOOPIS0LATED2R6, CPC-MDP-FR-SWlOA, CPC-MDP-MA-SWlOB, REFUEL, FREQ-F3RHR3, DURATION-R6, OSR-TRA-MA, ISR-TRA-MA,

/PZR-SV-REMOVEDW2, PR0B-W2R6 296 99.9 0.0 1.lBOE-010 UNITY, AFW-MDP-MA-FW3A, AFW-MDP-MA-FW3B, REFUEL, DURATION-R6, /PZR-SV-REMOVEDW2, PROB-W2R6, FREQ-FSRHR3, R-R3W2-XHE-F 297 99.9 0.0 l.lBOE-010 UNITY, CON-VFC-RP-COREM, LOOPIS0LATED2R6, REFUEL, FREQ-F3RHR3, DURATION-R6,

/PZR-SV-REMOVEDW2, PR0B-W2R6, A-F3R3W2-X-P-3 298 99.9 0.0 l.133E-010 UNITY, SSHR-AOV-XHE-105, MSS-AOV-MA-101B, PR0B-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F

-299 99.9 0.0 1.133E-010 UNITY, SSHR-AOV-XHE-105, MSS-AOV-MA-lOlA, PR0B-W3D6, FREQ-FSRHR3, DR-MT, DURATION-D6, R-R3W3-XHE-F 300 99.9 0.0 1.119E-010 UNITY, AFW-CKV-OO-CV142, REFUEL, DURATION-R6,

/PZR-SV-REMOVEDW2, PR0B-W2R6, FREQ-F5RHR3, 1993/11/24 09:19:27 page 16 D-45

Partition Cut Set Report Family->FLOOD/WINDOW End State ->CD Mincut Upper Bound-> 5.lllE-006 This Partition-> 5.lllE-006 Cut % % Cut No. Total Set Frequency Cut Sets R-R3W2-XHE-F 301 99.9 0.0 l.ll7E-010 UNITY, LPI-MDP-FS-SI1B, FREQ-F3RHR3, PR0B-W1D6, DR-MT, DURATION-D6, R-B2Wl-XHE-A 302 99.9 0.0 l.117E-010 UNITY, LPR-MOV-FT-1860B, FREQ-F3RHR3, PR0B-W1D6, DR-MT, DURATION-D6, R-B2Wl-XHE-A 303 99.9 0.0 l.104E-Ol0 UNITY, FREQ-F3RHR3, MSS-NRV-MA-101B, MSS-AOV-MA-101B, PROB-W3D6, A-F3R3W3-X-FL-3, DR-MT, DURATION-D6 304 99.9 0.0 l.104E-010 UNITY, FREQ-F3RHR3, MSS-NRV-MA-101A, MSS-AOV-MA-101A, PROB-W3D6, A-F3R3W3-X-FL-3, DR-MT, DURATION-D6 305 99.9 0.0

l.092E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6, SGC-DRAINED-R, PR0B-W1R6, /PZR-SV-REMOVEDWl, A-F3R3Wl-X-FL-9 306 99.9 0.0 l.092E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6, SGB-DRAINED-R, PR0B-W1R6, /PZR-SV-REMOVEDWl, A-F3R3Wl-X-FL-9 307 99.9 0.0 l.092E-010 UNITY, REFUEL, FREQ-F3RHR3, DURATION-R6, SGA-DRAINED-R, PR0B-W1R6, /PZR-SV-REMOVEDWl, A-F3R3Wl-X-FL-9 308 99.9 0.0 l.063E-010 UNITY, REFUEL, LPR-CCF-FT-890AB, FREQ-F3RHR3,

PZR-SV-REMOVEDW4, PR0B-W4R10, FRAC-POS10, DURATION-RlO 309 99.9 0.0 l.060E-Ol0 UNITY, REFUEL, LPI-MDP-FS-SI1B, FREQ-F3RHR3, DURATION-R6, /PZR-SV-REMOVEDW4, PR0B-W4R6 310 99.9 0.0 l.025E-010 UNITY, REFUEL, PZR-SV-REMOVEDW4, PR0B-W4R10, FREQ-F7B2, FRAC-POSlO, DURATION-RlO, A-F7B2W4-X-G-4 311 99.9 0.0 l.Ol9E-010 UNITY, CON-VFC-RP-COREM, LOOPISOLATED2R6, REFUEL, ISR-MDP-FS-RS1A, FREQ-F3RHR3, DURATION-R6, OSR-TRA-MA, /PZR-SV-REMOVEDW2, PR0B-W2R6 312 100.0 0.0 1.0l4E-010 UNITY, CIR-COND-UNAVLBL, MSS-AOV-MA-101B, PR0B-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 313 100.0 0.0 l.Ol4E-Ol0 UNITY, CIR-COND-UNAVLBL, MSS-AOV-MA-lOlA, PR0B-W2D6, FREQ-FSRHR3, DR-MT, DURATION-D6, R-R3W2-XHE-F 314 100.0 0.0 1.004E-010 UNITY, PR0B-W2D6, FREQ-F7B2, DR-MT, DURATION-D6, R-B2W2-XHE-S 1993/11/24 09:19:27 page 17 D-46

Appendix D.4 Basic Event Importances Based on Cutsets with Recovery Actions D-47

IMPORTANCE MEASURES REPORT (Alternate Cut Sets)

Family FLOOD/WINDOW EndState : CD Analysis RANDOM Case ALTERNATE (Sorted by Fussell-Vesley Importance)

Num. Probability Fussell- Risk Risk of of Vesely Reduction Increase Event Name 0cc. Failure Importance Ratio Ratio UNITY 314 l.OOOE+OOO l.OOOE+OOO l.OOOE+OOO REFUEL 157 6.000E-001 9.381E-001 l.616E+001 l.625E+OOO FREQ-F1B2 19 l.600E-008 6.834E-001 3.158E+OOO -2.902E+009 DURATION-R6 126 2.380E+002 5.382E-001 2.165E+OOO 4.641E-001 FRAC-POS10 31 S.OOOE-001 3.999E-001 l.666E+OOO 1.400E+OOO DURATION-RlO 31 4.440E+002 3.999E-001 l.666E+OOO 6.0lOE-001 PROB-W4R10 21 9.840E-001 3.897E-001 l.639E+OOO l.006E+OOO PROB-W3R6 15 4.lOOE-001 2.586E-001 l.349E+OOO 1.372E+OOO PROB-W2R6 66 S.430E-001 2.568E-001 1. 345E+OOO 1. 216E+OOO R-B2W2-XHE-S/R6 2 7.030E-001 2.006E-001 l.251E+OOO 1.085E+OOO FREQ-F2B2 15 3.800E-009 l.622E-001 l.194E+OOO -3.088E+009 FREQ-F5RHR3 78 1. 070E-008 7.411E-002 l.OSOE+OOO 1.973E+OOS DR-MT 157 1. 200E+OOO 6.189E-002 l.066E+OOO 9. 897E-*001 DURATION-D6 157 2.550E+002 6.189E-002 l.066E+OOO 9.384E-001 FREQ-F4RHR3 80 7.650E-009 5.455E-002 l.058E+OOO 1.959E+005 R-R3W2-XHE-F 52 1:420E-001 4.00SE-002 l.042E+OOO 1.242E+OOO R-R3W3-XHE-F 43 1.420E-001 3.786E-002 l.039E+OOO l.229E+OOO R-R3W4-XHE-F 10 6.360E-002 3.157E-002 l.033E+OOO 1. 465E+OOO LOOPISOLATED2R6 17 7.000E-001 3.058E-002 l.032E+OOO 1.013E+OOO PR0B-W1D6 12 l. l 70E-001 2.928E-002 1. 030E+OOO 1. 221E+OOO R-B2Wl-XHE-A 9 1. OOOE-001 2.108E-002 1. 022E+OOO !.190E+OOO FREQ-F3RHR3 111 1. 040E-008 1. 987E-002 1. 020E+OOO 1.956E+005 PR0B-W2D6 81 4.360E-001 l.771E-002 1. 018E+OOO 1.023E+OOO PROB-W4R6 12 3.400E-002 l.487E-002 1. OlSE+OOO l.422E+OOO PROB-W3D6 48 3.750E-001 1. 319E-002 l.013E+OOO 1.022E+OOO PROB-W3R10 10 l.600E-002 1. 018E-002 l.OlOE+OOO 1.626E+OOO PROB-W1R6 33 l.700E-002 7.945E-003 1. 008E+OOO 1.459E+OOO R-R3Wl-XHE-A 1 l.OOOE-001 7.494E-003 l.008E+OOO 1.067E+OOO FREQ-F7B2 11 8.410E-011 5. 866E-003* 1. 006E+OOO 2.595E+Ol4 PZR-SV-REMOVEDW2 66 S.OOOE-002 S.705E-003 1. 006E+OOO 1.108E+OOO LPR-CCF-PG-SUMP2 22 1. OOOE-001 S.337E-003 l.005E+OOO 1.048E+OOO SGA-DRAINED-R 15 2.300E-002 4.781E-003 1. 005E+OOO 1.203E+OOO SGB-DRAINED-R 15 2.300E-002 4.781E-003 1. 005E+OOO 1. 203E+OOO R-B2W2-XHE-S 3 8.950E-003 4.64SE~003 1. 005E+OOO 1. 514E+OOO A-F3R3W2-X-FL-9 21 9.300E-002 4.230E-003 l.004E+OOO 1. 041E+OOO R-B2W3-XHE-S 2 8.950E-003 3.978E-003 1. 004E+OOO 1. 441E+OOO L00PIS0LATED1R6 4 3.000E-001 2.932E-003 1. 003E+OOO 1.007E+OOO R-B2Wl-XHE-S/R6 2 3.lOOE-001 2.886E-003 1. 003E+OOO 1. 006E+OOO MSS-AOV-FC-lOlA 26 1. SOOE-001 2.227E-003 1. 002E+OOO 1. 013E+OOO MSS-AOV-FC-lOlB 26 1. 500E-001 2.227E-003 l.002E+OOO 1.013E+OOO MSS-NRV-MA-lOlB 17 5.000E-002 1. 964E-003 1. 002E+OOO 1.037E+OOO MSS-NRV-MA-lOlA 17 S.OOOE-002 1. 964E-003 l.002E+OOO 1.037E+OOO AFW-MDP-MA-FW3B 23 5.272E-001 1. 832E-003 l.002E+OOO l.002E+OOO A-F3R3Wl-X-FL-9 6 1.900E-001 l.774E-003 1.002E+OOO 1.008E+OOO 1993/11/24 09:28:13 page 1 D-48

Family Analysis Case IMPORTANCE MEASURES REPORT (Alternate Cut Sets)

FLOOD/WINDOW RANDOM ALTERNATE EndState : CD (Sorted by Fussell-Vesley Importance)

Num. Probability Fussell- Risk Risk of of Vesely Reduction Increase Event Name 0cc. Failure Importance Ratio Ratio PROB-W4D6 16 7.200E-002 1.707E-003 1.002E+OOO l.022E+OOO A-F3R3W3-X-FL-3 11 3.700E-002 1.457E-003 1.00lE+OOO 1.038E+OOO AFW-MDP-FS-FW3A 13 6.300E-003 1.420E-003 1.00lE+OOO 1.224E+OOO SGS-DRAINED-R 6 8.300E-003 1.408E-003 1.00lE+OOO l.168E+OOO A-F3R3W4-X-FL-4 2 1.600E-002 1.327E-003 1.00lE+OOO l.082E+OOO A-F5R3W2-X-S2-8 2 2.700E-001 1.296E-003 1.00lE+OOO l.004E+OOO A-FSR3W2-X-Sl-8 2 7.SOOE-002 1.296E-003 1.00lE+OOO 1.0lSE+OOO A-F4R3W2-X-S1-8 2 5.lOOE-002 1. 272E-003 1.00lE+OOO 1.024E+OOO A-F4R3W2-X-S2-8 2 1. SOOE-001 1. 272E-003 l.OOlE+OOO 1.006E+OOO A-F4R3W2-X-SF-8 2 8.700E-003 1.206E-003 l.OOlE+OOO 1.137E+OOO A-F3R3W3-X-FL-7 2 9.300E-002 1.148E-003 l.OOlE+OOO 1.0llE+OOO SSHR-AOV-XHE-105 19 1.300E-002 8.903E-004 l.OOlE+OOO l.068E+OOO A-F3R3W4-X-FL-7 2 4.200E-002 7.890E-004 l.OOlE+OOO 1.018E+OOO A-F3R3W2-X-S1-8 5 S.lOOE-002 7.764E-004 l.OOlE+OOO 1.014E+OOO A-F3R3W2-X-S2-8 5 1.SOOE-001 7.764E-004 l.OOlE+OOO 1.004E+OOO LPI-MDP-FS-SI1B 8 3.000E-003 7.380E-004 l.OOlE+OOO 1.245E+OOO A-F5R3W3-X-S1-7 1 7.SOOE-002 7.183E-004 l.OOlE+OOO 1.008E+OOO

-F5R3W3-X-S2-7 1 2.700E-001 7.183E-004 l.OOlE+OOO 1.002E+OOO

-F3R3W2-X-SF-8 5 8.200E-003 6.935E-004 1.00lE+OOO 1.084E+OOO

A-FSR3W2-X-SF-8 2 1. lOOE-002 6.771E-004 l.OOlE+OOO 1.061E+OOO CIR-COND-UNAVLBL 17 1.000E-002 6.507E-004 l.OOlE+OOO 1.064E+OOO A-FSR3Wl-X-S2-8 1 6.300E-001 5.705E-004 1.00lE+OOO 1.000E+OOO A-F5R3W1-X-S1-8 1 1.SOOE-001 S.705E-004 l.OOlE+OOO 1.003E+OOO MSS-AOV-MA-lOlB 10 S.OOOE-002 S.366E-004 l.OOlE+OOO 1.0lOE+OOO MSS-AOV-MA-lOlA 10 5.000E-002 S.366E-004 l.OOlE+OOO 1.0lOE+OOO LPR-MOV-FT-1890B 2 3.000E-003 4.569E-004 1.000E+OOO 1.152E+OOO A-F3R3W2-X-C-8 7 1. 200E-002 4.341E-004 1.000E+OOO 1.036E+OOO AFW-MDP-MA-FW3A 10 2.000E-003 4.113E-004 1. OOOE+OOO 1.205E+OOO D-FSR3W2-XHE 2 6.400E-003 3.939E-004 l.OOOE+OOO 1. 061E+OOO AFW-CKV-OO-CV142 10 1.000E-003 3.901E-004 1. OOOE+OOO 1. 390E+OOO A-F3R3Wl-X-C-8 2 4.400E-002 3.SSOE-004 l.OOOE+OOO 1.008E+OOO A-FSR3W3-X-SF-7 1 1. lOOE-002 3.752E-004 l.OOOE+OOO 1.034E+OOO LPR-MOV-FT-1860B 3 3.000E-003 3.602E-004 l.OOOE+OOO 1.120E+OOO A-FSR3W4-X-SF-7 1 7.SOOE-003 3.459E-004 l.OOOE+OOO 1.046E+OOO SGC-DRAINED-R 5 2.300E-002 3.364E-004 l.OOOE+OOO 1.014E+OOO A-F3R3W2-X-FL-4 1 3.700E-002 2.919E-004 1.000E+OOO 1.008E+OOO D-F3R3W2-XHE 2 6.200E-004 2.612E-004 l.OOOE+OOO 1. 421E+OOO SGS-DRAINED-CSD 8 1.000E-003 2.SSOE-004 1.000E+OOO 1.258E+OOO A-F4R3W3-X-S1-7 1 5.lOOE-002 2.239E-004 1.000E+OOO 1.004E+OOO A-F4R3W3-X-S2-7 1 1.SOOE-001 2.239E-004 1.000E+OOO 1.00lE+OOO LPR-MOV-FT-1862B 5 S.200E-003 2.213E-004 1.000E+OOO 1.042E+OOO D-FSR3W3-XHE 1 6.400E-003 2.183E-004 1.000E+OOO l.034E+OOO A-F4R3W3-X-SF-7 1 8.700E-003 2.122E-004 1.000E+OOO 1.024E+OOO D-F3R3W3-XHE 2 6.200E-004 2.112E-004 l.OOOE+OOO 1.340E+OOO 1993/11/24 09:28:13 page 2 D-49

IMPORTANCE MEASURES REPORT (Alternate Cut Sets)

Family FLOOD/WINDOW EndState : CD Analysis RANDOM Case ALTERNATE (Sorted by Fussell-Vesley Importance)

Num. Probability Fussell- Risk Risk of of Vesely Reduction Increase Event Name 0cc. Failure Importance Ratio Ratio PORV-PATH-CLSD 1 S.OOOE-002 2.098E-004 1. OOOE+OOO 1. 004E+OOO PPS-MOV-FT-1536 1 4.000E-002 2.098E-004 l.OOOE+OOO l.OOSE+OOO A-F4R3W4-X-SF-7 1 5.SOOE-003 l.813E-004 l.OOOE+OOO l.033E+OOO A-F4R3Wl-X-Sl-8 1 l.200E-001 1. 813E-004 l.OOOE+OOO l.OOlE+OOO A-F4R3Wl-X-S2-8 1 4.200E-001 l.813E-004 l.OOOE+OOO l.OOOE+OOO MSS-AOV-FC-lOlC 6 l.SOOE-001 1.78SE-004 l.OOOE+OOO l.OOlE+OOO OSR-TRA-MA 3 2.SOOE-001 l.744E-004 l.OOOE+OOO l.OOlE+OOO CON-VFC-RP-COREM 3 2.000E-002 l.742E-004 l.OOOE+OOO l.009E+OOO A-F5R3W4-X-S2-7 1 l.lOOE-001 1. 674E-004 l.OOOE+OOO l.OOlE+OOO A-F5R3W4-X-S1-7 1 3.300E-002 1. 674E-004 l.OOOE+OOO 1. OOSE+OOO ISR-TRA-MA 2 2.SOOE-001 1.545E-004 l.OOOE+OOO l.OOOE+OOO D-F1B2W4-XHE 1 1. 200E-003 l.477E-004 l.OOOE+OOO l.123E+OOO A-F1B2W4-X-G-4 1 3.lOOE-002 l.413E-004 l.OOOE+OOO l.004E+OOO D-F3R3Wl-XHE 1 l.600E-003 1.165E-004 l.OOOE+OOO l.073E+OOO A-F3R3W2-X-C-3 1 l.200E-002 9.466E-005 l.OOOE+OOO l.OOBE+OOO A-FSR3Wl-X-SF-8 1 1. 700E-002 8.552E-005 l.OOOE+OOO l.OOSE+OOO IAS-CPS-FS-IAC-1 2 8.000E-002 8.467E-005 l.OOOE+OOO l.OOlE+OOO PZR-SV-REMOVEDWl 33 1. OOOE-002 8.453E-OOS l.OOOE+OOO l.OOBE+OOO LPI-CCF-FS-SI1AB 2 4.SOOE-004 8.321E-005 l.OOOE+OOO l.lBSE+OOO LPR-MOV-PG-1890B 1 6.600E-004 8.123E-005 1.000E+OOO l.123E+OOO LPR-CCF-FT-890AB 3 2.600E-004 8.00SE-005 l.OOOE+OOO l.308E+OOO A-F3R3W3-X-S2-7 1 1. SOOE-001 7.930E-005 l.OOOE+OOO l.OOOE+OOO A-F3R3W3-X-S1-7 1 S.lOOE-002 7.930E-005 l.OOOE+OOO l.OOlE+OOO A-F7B2W3-X-G-4 1 8.SOOE-002 7.369E-005 l.OOOE+OOO 1. OOlE+OOO LPR-CCF-PG-SUMPl 1 1. OOOE-002 7.284E-005 l.OOOE+OOO l.007E+OOO A-F3R3W3-X-SF-7 1 8.200E-003 7.083E-005 l.OOOE+OOO 1. 009E+OOO D-F4R3W2-XHE 1 6.200E-004 6.835E-005 l.OOOE+OOO l.llOE+OOO D-FSR3Wl-XHE 1 l.300E-002 6.540E-005 1. OOOE+OOO l.OOSE+OOO MSS-NRV-MA-lOlC 2 S.OOOE-002 6.471E-005 l.OOOE+OOO l.OOlE+OOO A-F4R3Wl-X-SF-8 1 1. 400E-002 S.035E-005 1. OOOE+OOO l.004E+OOO A-F3R3Wl-X-S1-8 1 l.200E-001 4.682E-005 l.OOOE+OOO 1. OOOE+OOO A-F3R3Wl-X-S2-8 1 4.200E-001 4.682E-OOS l.OOOE+OOO l.OOOE+OOO D-FSR3W4-XHE 1 9.400E-004 4.335E-005 1. OOOE+OOO l.046E+OOO SAS-CPS-FR-1SAC1 1 4.SOOE-003 4.233E-005 l.OOOE+OOO l.009E+OOO SAS-CPS-FR-2SAC1 1 4.SOOE-003 4.233E-005 l.OOOE+OOO l.009E+OOO A-f2B2W4-X-G-4 1 3.SOOE-002 4.llSE-005 l.OOOE+OOO l.OOlE+OOO A-F4R3W4-X-S2-7 1 7.700E-002 4.062E-005 1. OOOE+OOO l.OOOE+OOO A-F4R3W4-X-S1-7 1 l.600E-002 4.062E-005 1. OOOE+OOO l.002E+OOO AFW-CCF-FS-FW3AB 1 3.SOOE-004 3.SSSE-005 l.OOOE+OOO l.llOE+OOO R-B2W4-XHE-S 1 S.390E-004 3.717E-005 l.OOOE+OOO l.069E+OOO D-F2B2W4-XHE 1 l.200E-003 3.SOSE-005 l.OOOE+OOO l.029E+OOO AFW-MOV-CC-151 1 2.600E-004 2.866E-005 l.OOOE+OOO l.llOE+OOO LPR-CCF-FT-860AB 1 2.600E-004 2.728E-005 l.OOOE+OOO l.lOSE+OOO LPR-CCF-FT-862AB 1 2.600E-004 2.728E-OOS l.OOOE+OOO l.lOSE+OOO 1993/11/24 09:28:13 page 3 D-50

IMPORTANCE MEASURES REPORT (Alternate Cut Sets)

Family FLOOD/WINDOW EndState : CD Analysis RANDOM Case ALTERNATE (Sorted by Fussell-Vesley Importance)

Num. Probability Fussell- Risk Risk of of Vesely Reduction Increase Event Name 0cc. Failure Importance Ratio Ratio D-F3R3W4-XHE 1 l.400E-004 2.613E-005 l.OOOE+OOO l.187E+OOO CPC-MDP-MA-SW10B 1 9.274E-001 2.335E-005 l.OOOE+OOO l.OOOE+OOO CPC-MDP-FR-SWlOA 1 3.840E-003 2.335E-005 l.OOOE+OOO l.006E+OOO A-F3R3W2-X-P-3 1 1. lOOE- 002 2.308E-005 l.OOOE+OOO l.002E+OOO A-F7B2W4-X-G-4 1 3.lOOE-002 2.00SE-005 l.OOOE+OOO l.OOlE+OOO ISR-MDP-FS-RS1A 1 3.SOOE-002 l.993E-005 l.OOOE+OOO l.OOlE+OOO PZR-SV-REMOVEDW3 25 9.000E-001 -1. 654E-*D02 9.837E-001 9.982E-001 PZR-SV-REMOVEDW4 33 3.000E-001 -1.564E-001 8.647E-001 6.350E-001 1993/11/24 09:28:13 page 4 D-51

Appendix E Basic Event Data E-1

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 1

A-F1B2Wl-X-G-4 T 1.000E+OOO +0.000E+OOO +O.OOOE+OOO Operator Failure to establish gravity feed in window 1 2 A-F1B2W2-X-G-4 T 1.000E+OOO +O.OOOE+OOO +O.OOOE+OOO Operator Failure to establish gravity feed in window 2 3 A-F1B2W3-X-G-4 T 1.000E+OOO +0.000E+OOO +O.OOOE+OOO Operator Failure to establish gravity feed in window 3 4 A-F1B2W4-X-G-4 1 3.lOOE-002 +0.000E+OOO +O.OOOE+OOO Operator Failure to establish gravity feed in window 4 5 A-F2B2W1-X-G-4 T 1.000E+OOO +0.000E+OOO +O.OOOE+OOO Operator Failure to establish gravity feed in window 1 6 A-F2B2W2-X-G-4 T l.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO Operator Failure to establish gravity feed in window 1 7 A-F2B2W3-X-G-4 T 1.000E+OOO +O.OOOE+OOO +O.OOOE+OOO Operator Failure to establish gravity feed in window 3 8 A-F2B2W4-X-G-4 1 3.SOOE-002 +0.000E+OOO +O.OOOE+OOO Operator Failure to establish gravity feed in window 4 9 A-F3R3W1-X-C-3 1 4.400E-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Establish High P Recirc in Window 1 10 A-F3R3W1-X-C-8 1 4.400E-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Establish High P Recirc in Window 1 11 A-F3R3W1-X-FH-4 1 8.lOOE-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to use HHSI in feed and spill in Window 1 12 A-F3R3W1-X-FH-9 1 l.900E-001 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to use HHSI in feed and spill in Window 1 13 A-F3R3W1-X-FL-4 1 8.100E-002 +0.000E+OOO +O.OOOE+OOO Operator failure ot use LHSI in Feed and Spill in Window 1 14 A-F3R3W1-X-FL-9 1 1.900E-001 +0.000E+OOO +O.OOOE+OOO Operator failure ot use LHSI in Feed and Spill in Window 1 15 A-F3R3W1-X-G-5 1 1. 600E-001 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to establish gravity feed in window 1 16 A-F3R3W1-X-P-3 1 2.400E-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Establish Recirculation Spray in W1 17 A-F3R3W1-X-Sl-8 1 1.200E-001 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Bleed the SGS 1 given R3 18 A-F3R3W1-X-S2-8 1 4.200E-001 +O.OOOE+OOO +O.OOOE+OOO Operator failure to establish reflux after PRT rupture 19 A-F3R3W1-X-SF-8 1 1.300E-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Feed SGs in Window 1-R3 20 A-F3R3W2-X-C-3 1 1.200E-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Establish High P Recirc in Window 2 21 A-F3R3W2-X-C-8 1 1.200E-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Establish High P Recirc in Window 2 22 A-F3R3W2-X-FH-4 1 3.?00E-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to use HHSI in f*eed and spill in Window 2 23 A-F3R3W2-X-FH-9 1 9.300E-002 +0.000E+OOO +O.OOOE+OOO Operator Failure to use HHS! in feed and spill in Window 2 24 A-F3R3W2-X-FL-4 1 3.700E-002 +O.OOOE+OOO +O.OOOE+OOO Operator failure ot use LHSI in Feed and Spill in Window 2 1993/11/24 09:45:14 page 1 E-2

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 25 A-F3R3W2-X-FL-9 1 9.300E-002 +0.000E+OOO +O.OOOE+OOO Operator failure ot use LHSI in Feed and Spill in Window 2 26 A-F3R3W2-X-G-5 1 8.500E-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to establish gravity feed in window 1 27 A-F3R3W2-X-P-3 1 1.lOOE-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Establish Recirculation Spray in Wl 28 A-F3R3W2-X-S1-8 1 5.lOOE-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Bleed the SGs 1 given R3 29 A-F3R3W2-X-S2-8 1 1.800E-001 +O.OOOE+OOO +O.OOOE+OOO Operator failure to establish reflux after PRT rupture 30 A-F3R3W2-X-SF-8 1 8.200E-003 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Feed SGs in Window 1-R3 31 A-F3R3W2-XHE-X 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Cross Connect RWST Given Successful "F" 32 A-F3R3W3-X-FH-3 1 3.700E-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to use HHSI in feed and spill in Window 3 33 A-F3R3W3-X-FH-7 1 9.300E-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to use HHSI in feed and spill in Window 3 34 A-F3R3W3-X-FL-3 1 3.700E-002 +O.OOOE+OOO +O.OOOE+OOO Operator failure ot use LHSI in Feed and Spill in Window 3 35 A-F3R3W3-X-FL-7 1 9.300E-002 +O.OOOE+OOO +O.OOOE+OOO Operator failure ot use LHSI in Feed and Spill in Window 3 36 A-F3R3W3-X-G-4 1 8.500E-002 +'O. OOOE+OOO +O. OOOE+OOO Operator Failure to establish gravity feed in window 3 37 A-F3R3W3-X-Sl-7 1 S.lOOE-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Bleed the SGs given R3 38 A-F3R3W3-X-S2-7 1 1.SOOE-001 +O.OOOE+OOO +O.OOOE+OOO Operator failure to establish reflux after PRT rupture 39 A-F3R3W3-X-SF-7 1 8.200E-003 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Feed SGS in Window 3 40 A-F3R3W4-X-FH-4 1 1.600E-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to use HHSI in feed and spill in Window 4 41 A-F3R3W4-X-FH-7 1 4.200E-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to use HHSI in feed and spill in Window 4 42 A-F3R3W4-X-FL-4 1 1.600E-002 +O.OOOE+OOO +O.OOOE+OOO Operator failure ot use LHSI in Feed and Spill in Window 4 43 A-F3R3W4-X-FL-7 1 4.200E-002 +O.OOOE+OOO +O.OOOE+OOO Operator failure ot use LHSI in Feed and Spill in Window 4 44 A-F3R3W4-X-G-4 1 3.lOOE-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to establish gravity feed in window 4 45 A-F3R3W4-X-Sl-7 1 1.600E-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Bleed the SGs in Window 4 46 A-F3R3W4-X-S2-7 1 7.700E-002 +O.OOOE+OOO +0.000E+OOO Operator failure to establish reflux after PRT rupture 47 A-F3R3W4-X-SF-7 1 S.400E-003 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Feed SGs in Window 4-RHR3 48 A-F4R3Wl-X-Sl-8 1 1.200E-001 +0.000E+OOO +O.OOOE+OOO Operator Failure to Bleed the SGS 1 given R3 1993/11/24 09:45:14 page 2 E-3

Event Number Primary Name BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Calculation Type Case: ALTERNATE Mean Probability Lamda Tau 49 A-F4R3Wl-X-S2-8 1

4.200E-001 +O.OOOE+OOO +O.OOOE+OOO Operator failure to establish reflux after PRT rupture so A-F4R3Wl-X-SF-8 1 l.400E-002 +O.OOOE+OOO +0.000E+OOO Operator Failure to Feed SGs in Window l-R3 51 A-F4R3W2-X-Sl-8 1 S.lOOE-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Bleed the SGs 1 given R3 52 A-F4R3W2-X-S2-8 1 l.800E-001 +O.OOOE+OOO +O.OOOE+OOO Operator failure to establish reflux after PRT rupture 53 A-F4R3W2-X-SF-8 1 8.700E-003 +O.OOOE+OOO +O. OOOE+OOO .

Operator Failure to Feed SGs in Window l-R3 54 A-F4R3W3-X-Sl-7 1 S.lOOE-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Bleed the SGs given R3 55 A-F4R3W3-X-S2-7 1 l.800E-001 +O.OOOE+OOO +O.OOOE+OOO Operator failure to establish reflux after PRT rupture 56 A-F4R3W3-X-SF-7 1 8.700E-003 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Feed SGs in Window 3 57 A-F4R3W4-X-Sl-7 1 l.600E-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Bleed the SGS in Window 4 58 A-F4R3W4-X-S2-7 1 7.700E-002 +O.OOOE+OOO +O.OOOE+OOO Operator failure to establish reflux after PRT rupture 59 A-F4R3W4-X-SF-7 1 5.SOOE-003 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Feed SGs in Window 4-RHR3 60 A-FSR3Wl-X-Sl-8 1 1. 800E-001 +O.OOOE+OOO +O.OOOE+OO Operator Failure to Bleed the SGS 1 given R3 61 A-FSR3Wl-X-S2-8 1 6.300E-001 +O.OOOE+OOO +O.OOOE+OOO Operator failure to establish reflux after PRT rupture 62 A-FSR3Wl-X-SF-8 1 l.?OOE-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Feed SGs in Window l-R3 63 A-FSR3W2-X-Sl-8 1 7.SOOE-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Bleed the SGs 1 given R3 64 A-FSR3W2-X-S2-8 1 2.?00E-001 +O.OOOE+OOO +O.OOOE+OOO Operator failure to establish reflux after PRT rupture 65 A-FSR3W2-X-SF-8 1 l . lOOE-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Feed SGs in Window l-R3 66 A-FSR3W3-X-Sl-7 1 7.SOOE-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Bleed the SGs given R3 67 A-FSR3W3-X-S2-7 1 2.?00E-001 +O.OOOE+OOO +O.OOOE+OOO Operator failure to establish reflux after PRT rupture 68 A-FSR3W3-X-SF-7 1 l . lOOE-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Feed SGs in Window 3 69 A-FSR3W4-X-Sl-7 1 3.300E-002 +O.OOOE+OOO +O. o*ooE+OOO Operator Failure to Bleed the SGs in Window 4 70 A-FSR3W4-X-S2-7 1 l . lOOE-001 +O.OOOE+OOO +O.OOOE+OOO Operator failure to establish reflux after PRT rupture 71 A-FSR3W4-X-SF-7 1 7.SOOE-003 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Feed SGs in Window 4-RHR3 72 A-F7B2Wl-X-G-4 1 1. 600E-001 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to establish gravity feed in window 1 1993/11/24 09:45:14 page 3 E-4

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 73 A-F7B2W2-X-G-4 1 8.500E-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to establish gravity feed in window 2 74 A-F7B2W3-X-G-4 1 8.500E-002 +O.OOOE+OOO +0.000E+OOO Operator Failure to establish gravity feed in window 3 75 A-F7B2W4-X-G-4 1 3.lOOE-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to establish gravity feed in window 4 76 ACC-CKV-FT-CV107 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV107 FAILS TO OPEN 77 ACC-CKV-FT-CV109 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV109 FAILS TO OPEN 78 ACC-CKV-FT-CV128 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV128 FAILS TO OPEN 79 ACC-CKV-FT-CV130 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV si 130 FAILS TO OPEN 80 ACC-CKV-FT-CV145 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV145 FAILS TO OPEN 81 ACC-CKV-FT-CV147 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV SI 147 FAILS TO OPEN.

82 ACC-MOV-PG-1865A 1 6.500E-004 l.OOOE-007 1.300E+004 ACC MOTOR OPERATED VALVE 1865A PLUGGED 83 ACC-MOV-PG-1865B 1 6.500E-004 l.OOOE-007 1.300E+004 ACC MOTOR OPERATED VALVE 1865B PLUGGED 84 ACC-MOV-PG-1865C 1 6.500E-004 l.OOOE-007 l.300E+004 ACC MOTOR OPERATED VALVE 1865C PLUGGED 85 ACP-BAC-MA-lHl 1 7.270E-006 +O.OOOE+OOO +O.OOOE+OOO BUS BAR OF 480V AC BUS lHl MAINTENANCE 86 ACP-BAC-MA-lHl-1 1 7.270E-006 +O.OOOE+OOO +O.OOOE+OOO 480V MCC lHl-1 UNAVAILABLE DUE TO MAINTENANCE 87 ACP-BAC-MA-lHl-2 1 7.270E-006 +O.OOOE+OOO +O.OOOE+OOO 480V AC MCC lHl-2 UNAVAILABLE DUE TO MAINTENANCE 88 ACP-BAC-MA-lJl 1 7.270E-006 +O.OOOE+OOO +O.OOOE+OOO BUS BAR OF 480V AC BUS lJl MAINTENANCE 89 ACP-BAC-MA-lJl-1 1 7.270E-006 +O.OOOE+OOO +O.OOOE+OOO 480V MCC lJl-1 UNAVAILABLE DUE TO MAINTENANCE 90 ACP-BAC-MA-lJl-2 1 7.270E-006 +O.OOOE+OOO +O.OOOE+OOO 480V AC MCC lJl-2 UNAVAILABLE DUE TO MAINTENANCE 91 ACP-BAC-MA-4801H 1 7.270E-006 +O.OOOE+OOO +O.OOOE+OOO BUS BAR OF 480V lH AC BUS MAINTENANCE 92 ACP-BAC-MA-4801J 1 7.270E-006 +O.OOOE+OOO +O.OOOE+OOO BUS BAR OF 480V lJ AC BUS MAINTENANCE 93 ACP-BAC-MA-4KV1H F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO 4160V AC BUS lH MAINTENANCE 94 ACP-BAC-MA-4KV1J F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO 4160V AC BUS lJ MAINTENANCE 95 ACP-BAC-MA-STBlH F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO 4160V AC STUB BUS lH MAINTENANCE 96 ACP-BAC-MA-STBlJ F +O. OOOE+OOO +O. OOOE+OOO +O. OOOE+OOO 4160V AC STUB BUS lJ MAINTENANCE 1993/11/24 09:45:14 page 4

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Event Number Primary Name BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Calculation Type Case: ALTERNATE Mean Probability Lamda Tau 97 ACP-BAC-MA-VBlII 1 +0.000E+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON VITAL BUS SUPPLY - STATE 6 98 ACP-BAC-MAOVBlII 1 +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON VITAL BUS SUPPLY - STATE 10 99 ACP-BAC-ST-lHl 1 9.000E-005 +0.000E+OOO +O.OOOE+OOO 480V AC BUS lHl BUSWORK FAILURE 100 ACP-BAC-ST-lHl-1 1 9.000E-005 +0.000E+OOO +0.000E+OOO 480V AC MCC lHl-1 BUSWORK FAILURE 101 ACP-BAC-ST-lHl-2 1 9.000E-005 +O.OOOE+OOO +O.OOOE+OOO 480V AC MUCC lHl-2 BUSWORK FAILURE 102 ACP-BAC-ST-lJl 1 9.000E-005 +O.OOOE+OOO +O.OOOE+OOO 480V AC BUS lJl BUSWORK FAILURE 103 ACP-BAC-ST-lJl-1 1 9.000E-005 +O.OOOE+OOO +0.000E+OOO 480V AC MCC lJl-1 BUSWORK FAILURE 104 ACP-BAC-ST-lJl-2 1 9.000E-005 +O.OOOE+OOO +0.000E+OOO 480V AC MCC lJl-2 BUSWORK FAILURE 105 ACP-BAC-ST-2Hl 1 9.000E-005 +O.OOOE+~OO +O.OOOE+OOO 480V AC BUS 2Hl BUSWORK FAILURE 106 ACP-BAC-ST-2Hl-l 1 9.000E-005 +O.OOOE+OOO +O.OOOE+OOO 480V AC MCC 2Hl-l BUSWORK FAILURE 107 ACP-BAC-ST-4801H 1 9.000E-005 +O.OOOE+OOO +O.OOOE+OOO 480V AC BUS lH BUSWORK FAILURE 108 ACP-BAC-ST-4801J 1 9.000E-005 +O.OOOE+OOO +O.OOOE+OOO 480V AC BUS lJ BUSWORK FAILURE 109 ACP-BAC-ST-4KV1H 1 9.000E-005 +O.OOOE+OOO +O.OOOE+OOO 4160V AC BUS lH BUSWORK FAILURE 110 ACP-BAC-ST-4KV1J 1 9.000E-005 +O.OOOE+OOO +O.OOOE+OOO 4160V AC BUS lJ BUSWORK FAILURE 111 ACP-BAC-ST-4KV2H 1 9.000E-005 +0.000E+OOO +O.OOOE+OOO 4160V AC BUS 2H BUSWORK FAILURE 112 ACP-BAC-ST-STBlH 1 9.000E-005 +O.OOOE+OOO +O.OOOE+OOO 4160V AC STUB BUS lH BUSWORK FAILURE 113 ACP-BAC-ST-STBlJ 1 9.000E-005 +O.OOOE+OOO +O.OOOE+OOO 4160V AC STUB BUS lJ BUSWORK FAILURE 114 ACP-BAC-ST-STB2H 1 9.000E-005 +O.OOOE+OOO +O.OOOE+OOO 4160V AC STUB BUS 2H BUSWORK FAILURE 115 ACP-BAC-ST-VlIII 1 9.000E-005 +O.OOOE+OOO +O.OOOE+OOO VITAL BUS lIII BUSWORK FAILURE 116 ACP-BAC-ST-VBlI 1 9.000E-005 +O.OOOE+OOO +O.OOOE+OOO VITAL BUS lI BUSWORK FAILURE 117 ACP-BAC-ST-VBlII 1 9.000E-005 +O.OOOE+OOO +O.OOOE+OOO VITAL BUS lII BUSWORK FAILURE 118 ACP-BAC-ST-VBlIV 1 9.000E-005 +O.OOOE+OOO +O.OOOE+OOO VITAL BUS lIV BUSWORK FAILURE 119 ACP-BCH-MA-UPSAl F +O.OOOE+OOO +O.OOOE+OOO +0.000E+OOO UPSAl BATTERY CHARGER MAINTENANCE 120 ACP-BCH-MA-UPSA2 F +0.000E+OOO +O.OOOE+OOO +O.OOOE+OOO UPSA2 BATTERY CHARGER MAINTENANCE 1993/11/24 09:45:14 page 5 E-6

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 121 ACP-BCH-MA-UPSBl. 1 4.003E-001 +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON BATTERY CHARGER Bl-STATE 6 122 ACP-BCH-MA-UPSB2 1 4.003E-001 +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON BATTERY CHARGER B2 - STATE 6 123 ACP-BCH-MAOUPSBl 1 +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON BATTERY CHARGER Bl - STATE 10 124 ACP-BCH-MAOUPSB2 1 +0.000E+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON BATTERY CHARGER B2 - STATE 10 125 ACP-CRB-C0-14Hl 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO AC CIRCUIT BREAKER 14Hl TRANSFERS OPEN 126 ACP-CRB-C0-14H13 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO AC CIRCUIT BREAKER 14H13 TRANSFERS OPEN 127 ACP-CRB-C0-14H14 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO AC CIRCUIT BREAKER 14H14 TRANSFERS OPEN 128 ACP-CRB-C0-14H15 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO AC CIRCUIT BREAKER 14H15 TRANSFERS OPEN 129 ACP-CRB-C0-14Jl 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO AC CIRCUIT BREAKER 14Jl TRANSFERS OPEN 130 ACP-CRB-C0-14Jll 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO AC CIRCUIT BREAKER 14Jll TRANSFERS OPEN 131 ACP-CRB-C0-14Jl4

1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO AC CIRCUIT BREAKER 14J14 TRANSFERS OPEN 132 ACP-CRB-C0-14J16 1 2.900E-005 +O.OOOE+OOO +0.000E+OOO AC CIRCUIT BREAKER 14Jl6 TRANSFERS OPEN 133 ACP-CRB-C0-15H7 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO AC CIRCUIT BREAKER 1SH7 TRANSFERS OPEN 134 ACP-CRB-C0-15H8 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO AC CIRCUIT BREAKER 15H8 TRANSFERS OPEN 135 ACP-CRB-C0-15H9 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO AC CIRCUIT BREAKER 15H9 TRANSFERS OPEN 136 ACP-CRB-C0-15J7 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO AC CIRCUIT BREAKER 15J7 TRANSFERS OPEN 137 ACP-CRB-C0-15J8 1 2.900E-005 +O.OOOE+OOO +0.000E+OOO AC CIRCUIT BREAKER 15J8 TRANSFERS OPEN 138 ACP-CRB-C0-15J9 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO AC CIRCUIT BREAKER 15J9 TRANSFERS 139 ACP-CRB-C0-1I35 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO VITAL BUS lI AC CKT BREAKER 35 TRANSFERS OPEN 140 ACP-CRB-CO-lII 1 2.900E-005 +O.OOOE+OOO +0.000E+OOO AC CIRCUIT BREAKER TO lII TRANSFERS OPEN 141 ACP-CRB-CO-lIV 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO AC CIRCUIT BREAKER TO lIV TRANSFERS OPEN 142 ACP-CRB-C0-24Hl4 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO AC CIRCUIT BREAKER 24Hl4 TRANSFERS OPEN 143 ACP-CRB-C0-24Hl5 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO AC CIRCUIT BREAKER 24Hl5 TRANSFERS OPEN 144 ACP-CRB-C0-25H7 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO AC CIRCUIT BREAKER 25H7 TRANSFERS OPEN 1993/11/24 09:45:14 page 6

E-7

Event Number Primary Name BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Calculation Type Case: ALTERNATE Mean Probability Lamda Tau 145 ACP-CRB-C0-25H9 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO AC CIRCUIT BREAKER 25H9 TRANSFERS OPEN 146 ACP-CRB-CO-FE9AE 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO AC CIRCUIT BREAKER FE9AE TRANSFERS OPEN 147 ACP-CRB-CO-FE9AF 1 2.900E-005 +0.000E+OOO +O.OOOE+OOO AC CIRCUIT BREAKER FE9AF TRANSFERS OPEN 148 ACP-CRB-CO-FE9AJ 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO AC CIRCUIT BREAKER FE9AJ TRANSFERS OPEN 149 ACP-CRB-CO-FE9AK 1 2.900E-005 +0.000E+OOO +O.OOOE+OOO AC CIRCUIT BREAKER FE9AK TRANSFERS OPEN 150 ACP-CRB-CO-FE9BE 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO AC CIRCUIT BREAKER FE9BE TRANSFERS OPEN 151 ACP-CRB-CO-FE9BF 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO AC CIRCUIT BREAKER FE9BF TRANSFERS OPEN 152 ACP-CRB-CO-FE9BJ 1 2.900E-005 +O.OOOE+OOO +0.000E+OOO AC CIRCUIT BREAKER FE9BJ TRANSFERS OPEN 153 ACP-CRB-CO-FE9BK 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO AC CIRCUIT BREAKER FE9BK TRANSFERS OPEN 154 ACP-CRB-CO-III35 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO VITAL B.US 1 I I I AC CKT BRKR 3 5 TRANSFERS OPEN 155 ACP-INV-MA-UPSAl 1 2.000E-004 +O.OOOE+OOO +O.OOOE+OOO UPSAl INVERTER MAINTENANCE 156 ACP-INV-MA-UPSA2 1 2.000E-004 +O.OOOE+OOO +O.OOOE+OOO UPSA2 INVERTER MAINTENANCE 157 ACP-INV-MA-UPSBl 1 2.000E-004 +O.OOOE+OOO +O.OOOE+OOO UPSBl INVERTER MAINTENANCE 158 ACP-INV-MA-UPSB2 1 2.000E-004 +O.OOOE+OOO +O.OOOE+OOO UPSB2 INVERTER MAINTENANCE 159 ACP-INV-NO-UPSAl 1 4.000E-002 +O.OOOE+OOO +O.OOOE+OOO UPS lAl INVERTER OUTPUT FAILS 160 ACP-INV-NO-UPSA2 1 4.000E-002 +O.OOOE+OOO +O.OOOE+OOO UPS 1A2 INVERTER OUTPUT FAILS 161 ACP-INV-NO-UPSBl 1 4.000E-002 +O.OOOE+OOO +O.OOOE+OOO UPS l.Bl INVERTER OUTPUT FAILS 162 ACP-INV-NO-UPSB2 1 4.000E-002 +O.OOOE+OOO +O.OOOE+OOO UPS 1B2 INVERTER OUTPUT FAILS 163 ACP-REC-NO-UPSAl 1 4.000E-004 +O.OOOE+OOO +O.OOOE+OOO UPS l.Al RECTIFIER OUTPUT FAILURE 164 ACP-REC-NO-UPSA2 1 4.000E-004 +O.OOOE+OOO +O.OOOE+OOO UPS l.A2 RECTIFIER OUTPUT FAILURE 165 ACP-REC-NO-UPSBl 1 4.000E-004 +O.OOOE+OOO +O.OOOE+OOO UPS l.Bl RECTIFIER OUTPUT FAILURE 166 ACP-REC-NO-UPSB2 1 4.000E-004 +O.OOOE+OOO +O.OOOE+OOO UPS l.B2 RECTIFIER OUTPUT FAILURE 167 ACP-TFM-NO-l.Al.-1 4 4.080E-005 1. 700E-006 2.400E+001 FAILURE OF UPS lAl TRANSFORMER PWR FM l.Hl-1 168 ACP-TFM-NO-l.Al-2 4 4.080E-005 1. 700E-006 2.400E+001 FAILURE OF UPS lAl TRANSFORMER PWR FMl.Hl-2 1993/11/24 09:45:14 page 7 E-8

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 169 ACP-TFM-N0-1A2-l 4 4.080E-005 l.700E-006 2.400E+001 FAILURE OF UPS 1A2 TRANSFORMER PWR FM lHl-2 170 ACP-TFM-N0-1A2-2 4 4.080E-005 1.700E-006 2.400E+001 FAILURE OF UPS 1A2 TRANSFORMER PWR FMlHl-1 171 ACP-TFM-NO-lBl-1 4 4.080E-005 l.700E-006 2.400E+Obl FAILURE OF UPS lBl TRANSFORMER PWR FM lJl-1 172 ACP-TFM-NO-lBl-2 4 4.080E-005 1.700E-006 2.400E+001 FAILURE OF UPS lBl TRANSFORMER PWR FM lJl-2 173 ACP-TFM-N0-1B2-l 4 4.080E-005 l.700E-006 2.400E+001 FAILURE OF UPS 1B2 TRANSFOMRER PWR FM lJl-2 174 ACP-TFM-N0-1B2-2 4 4.080E-005 1.700E-006 2.400E+001 FAILURE OF UPS XFMR PWR lJl-1 175 ACP-TFM-NO-lH 4 4.080E-005 1.700E-006 2.400E+001 FAILURE OF POWER TRANSFORMER TO BUS lH 176 ACP-TFM-NO-lHl 4 4.080E-005 1.700E-006 2.400E+001 FAILURE OF POWER TRANSFORMER TO BUS lHl 177 ACP-TFM-NO-lJ 4 4.080E-005 1.700E-006 2.400E+001 FAILURE OF POWER TRANSFORMER TO BUS lJ 178 ACP-TFM-NO-lJl 4 4.080E-005 1.700E-006 2.400E+001 FAILURE OF POWER TRANSFORMER TO BUS lJl 179 ACP-TFM-N0-2Hl 4 4.080E-005 1.700E-006 2.400E+001 FAILURE OF POWER TRANSFORMER TO BUS 2Hl 180 ACP-XHE-FO-STBBS 1 5.000E-005 +O.OOOE+OOO +O.OOOE+OOO OP FAILS TO RECONNECT STUB BUS(LOSP INIT ONLY 181 AFW-ACT-FA-PMP3A 1 6.000E-004 +O.OOOE+OOO +O.OOOE+OOO NO ACTUATION SIGNAL TO AFW PUMP 3A 182 AFW-ACT-FA-PMP3B 1 6.000E-004 +O.OOOE+OOO +O.OOOE+OOO NO ACTUATION SIGNAL TO AFW PUMP 3B 183 AFW-ACT-FA-VLVA 1 6.000E-004 +O.OOOE+OOO +O.OOOE+OOO NO ACTUATION SIGNAL TO AOV-MS102A 184 AFW-ACT-FA-VLVB 1 6.000E-004 +O.OOOE+OOO +O.OOOE+OOO NO ACTUATION SIGNAL TO AOV-MS102B 185 AFW-AOV-FT-102A 1 l.OOOE-003 +O.OOOE+OOO +O.OOOE+OOO AIR OPERATED VALVE MS102A FAILS TO OPEN 186 AFW-AOV-FT-102B 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO AIR OPERATED VALVE MS102B FAILS TO OPEN 187 AFW-AOV-FT-202A 1 l.OOOE-003 +O.OOOE+OOO +O.OOOE+OOO AIR OPERATED VALVE MS202A FAILS TO OPEN 188 AFW-AOV-FT-202B 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO AIR OPERATED VALVE MS202B FAILS TO OPEN 189 AFW-AOV-PG-102A 1 4.000E-005 1.000E-007 7.200E+002 AIR OPERATED VALVE MS102A PLUGGED 190 AFW-AOV-PG-102B 1 4.000E-005 1.000E-007 7.200E+002 AIR OPERATED VALVE MS102B PLUGGED 191 AFW-AOV-PG-202A 1 4.000E-005 l.OOOE-007 7.200E+002 AIR OPERATED VALVE MS202A PLUGGED 192 AFW-AOV-PG-202B 1 4.000E-005 1.000E-007 7.200E+002 AIR OPERATED VALVE MS202B PLUGGED 1993/11/24 09:45:14 page 8

E-9

Event Number Primary Name BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Calculation Type Case: ALTERNATE

,Mean Probability Lamda Tau 193 AFW-CCF-FS-FW3AB 1 3.500E-004 +0.000E+OOO +O.OOOE+OOO COMMON CAUSE FAILURE OF AFW MOTOR DRIVEN PUMP 194 AFW-CCF-FT-102AB 1 l.OOOE-004 +0.000E+OOO +O.OOOE+OOO COMMON CAUSE FAILURE OF MS102A AND B TO OPEN 195 AFW-CCF-FT-202AB 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO COMMON CAUSE FAILURE OF MS202A AND B TO OPEN 196 AFW-CCF-LK-2STMB 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO UNDETECT LEAKAGE THRU U2 CV STM BIND 197 AFW-CCF-LK-STMBD 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO UNDETECT LKAGE THRU CHK VLV CV27 CV58 OR CV89 198 AFW-CKV-CC-27588 1 l.OOOE-005 +O.OOOE+OOO +O.OOOE+OOO CCF 3/3 CHECK VALVE AFW-27 58 89 199 AFW-CKV-CC-3638 1 l.OOOE-005 +O.OOOE+OOO +O.OOOE+OOO CCF 2/2 CHECK VLVS AFW-131 133 200 AFW-CKV-CC-42577 1 l.OOOE-005 +O.OOOE+OOO +O.OOOE+OOO CCF 3/3 CHECK VALVES AFW-142 157 172 201 AFW-CKV-FT-CV131 1 l.OOOE-004 +0.000E+OOO +O.OOOE+OOO CHECK VALVE CV131 FAILS TO OPEN 202 AFW-CKV-FT-CV133 1 l.OOOE-004. +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV133 FAILS TO OPEN 203 AFW-CKV-FT-CV136 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV136 FAILS TO OPEN 204 AFW-CKV-FT-CV138 1 l.OOOE-004 ~O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV13B FAILS TO OPEN 205 AFW-CKV-FT-CV142 1 l.OOOE-004 +O.OOOE+OOO. +0.000E+OOO CHECK VALVE CV142 FAILS TO OPEN 206 AFW-CKV-FT-CV157 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV157 FAILS TO OPEN 207 AFW-CKV-FT-CV172 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV172 FAILS TO OPEN 208 AFW-CKV-FT-CV176 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV176 FAILS TO OPEN 209 AFW-CKV-FT-CV178 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV17B FAILS TO OPEN 210 AFW-CKV-FT-CV1B2 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV182 FAILS TO OPEN 211 AFW-CKV-FT-CV232 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV232 FAILS TO OPEN 212 AFW-CKV-FT-CV233 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV233 FAILS TO OPEN 213 AFW-CKV-FT-CV236 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV236 FAILS TO OPEN 214 AFW-CKV-FT-CV238 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV238 FAILS TO OPEN 215 AFW-CKV-FT-CV242 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV242 FAILS TO OPEN 216 AFW-CKV-FT-CV27 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV27 FAILS TO OPEN 1993/11/24 09:45:14 page 9 E-10

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 217 AFW-CKV-FT-CV58 1 1.000E-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV58 FAILS TO OPEN 218 AFW-CKV-FT-CV89 1 1.000E-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV89 FAILS TO OPEN 219 AFW-CKV-00-CV142 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO BACKFLOW THROUGH CV142 220 AFW-CKV-00-CV157 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO BACKFLOW THROUGH CV157 221 AFW-CKV-00-CV172 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO BACKFLOW THROUGH CV172 222 AFW-CKV-00-CV257 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO BACKFLOW THROUGH CV257 223 AFW-CKV-00-CV272 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO BACKFLOW THROUGH CV272 224 AFW-MDP-FR-3A1HR 4 3.000E-005 3.000E-005 1.000E+OOO MDP AFW 3A FAILS TO RUN 1 HOUR 225 AFW-MDP-FR-3A6HR 4 1.800E-004 3.000E-005 6.000E+OOO MDP AFW 3A FAILS TO RUN 6 HOURS 226 AFW-MDP-FR-3B1HR 4 3.000E-005 3.000E-005 1.000E+OOO MDP AFW 3B FAILS TO RUN 1 HOUR 227 AFW-MDP-FR-3B6HR 4 1.SOOE-004 3.000E-005 6.000E+OOO MDP AFW 3B FAILS TO RUN 6 HOURS 228 AFW-MDP-FS-FW3A 1 6.300E-003 +O.OOOE+OOO +O.OOOE+OOO MDP AFW 3A FAILS TO START 229 AFW-MDP-FS-FW3B 1 6.300E-003 +O.OOOE+OOO +O.OOOE+OOO MDP AFW 3B FAILS TO START 230 AFW-MDP-MA-FW3A 1 2.000E-003 +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON AFW MDP 3A 231 AFW-MDP-MA-FW3B 1 5.272E-001 +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON AFW MDP 3B - STATE 6 232 AFW-MDP-MAOFW3A 1 2.000E-003 +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON AFW MDP 3A 233 AFW-MDP-MAOFW3B 1 S.llOE-001 +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON AFW MDP 3B - STATE 10 234 AFW-MOV-CC-151 1 2.600E-004 +O.OOOE+OOO +O.OOOE+OOO CCF 2/2 MOV 151A B 235 AFW-MOV-FT-151A 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO MOV FW151A FAILS TO OPEN 236 AFW-MOV-FT-151B 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO MOV FW151B FAILS TO OPEN 237 AFW-MOV-FT-151C 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO MOV FW151C FAILS TO OPEN 238 AFW-MOV-FT-151D 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO MOV FW151D FAILS TO OPEN 239 AFW-MOV-FT-151E 1 3.000E-003 +0.000E+OOO +0.000E+OOO MOV FW151E FAILS TO OPEN 240 AFW-MOV-FT-151F 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO MOV FW151F FAILS TO OPEN 1993/11/24 09:45:14 page 10

E-11

Event Number Primary Name BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Calculation Type Case: ALTERNATE Mean Probability Lamda Tau 241 AFW-MOV-FT-160A 1 3.000E-003 +0.000E+OOO +O.OOOE+OOO MOV FW160A FAILS TO OPEN 242 AFW-MOV-FT-160B 1 3.000E-003 +0.000E+OOO +O.OOOE+OOO MOV FW160B FAILS TO OPEN 243 AFW-MOV-MA-151A 1 7.260E-002 +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON AFW TRAIN A MOVS - STATE 6 244 AFW-MOV-MA-151B 1 l.OOOE-003 +O.OOOE+OOO +O.OOOE+OOO AFW FW-151B IN MAINTENANCE 245 AFW-MOV-MA-151C 1 l.OOOE-003 +O.OOOE+OOO +O.OOOE+OOO AFW FW-151C IN MAINTENANCE 246 AFW-MOV-MA-151D 1 l.OOOE-003 +O.OOOE+OOO +O.OOOE+OOO AFW FW-151D IN MAINTENANCE 247 AFW-MOV-MA-151E 1 l.OOOE-003 +O.OOOE+OOO +0.000E+OOO AFW FW-151E IN MAINTENANCE 248 AFW-MOV-MA-151F 1 l.OOOE-003 +O.OOOE+OOO +0.000E+OOO AFW FW-151F IN MAINTENANCE 249 AFW-MOV-MA-160A 1 l.OOOE-003 +0.000E+OOO +O.OOOE+OOO AFW FW-160A IN MAINTENANCE 250 AFW-MOV-MA-160B 1 l.OOOE-003 +O.OOOE+OOO +0.000E+OOO AFW FW-160B IN MAINTENANCE 251 AFW-MOV-MA0151A 1 +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON AFW TRAIN A MOVS - STATE 10 252 AFW-MOV-PG-151A 1 4.000E-005 l.OOOE-007 7.200E+OO MOV FW151A PLUGGED 253 AFW-MOV-PG-l51B l 4.000E-005 l.OOOE-007 7.200E+002 MOTOR OPERATED VALV FWlSlB PLUGGED 254 AFW-MOV-PG-lSlC l 4.000E-005 1. OOOE-007 7.200E+002 MOTOR OPERATED VALVE FWlSlC PLUGGED 255 AFW-MOV-PG-lSlD l 4.000E-005 l.OOOE-007 7.200E+002 MOTOR OPERATED VALVE FWlSlD PLUGGED 256 AFW-MOV-PG-l51E l 4.000E-005 l.OOOE-007 7.200E+002 MOV FWlSlE PLUGGED 257 AFW-MOV-PG-lSlF l 4.000E-005 l.OOOE-007 7.200E+002 MOV FWlSlF PLUGGED 258 AFW-MS-PG-196 l 4. OOOE-005 +O. OOOE+OOO +O. OOOE'+OOO N.O. MANUAL VLV PLUGGED MS-196 259 AFW-MS-PG-296 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO N.O. MANUAL VLV PLUGGED MS-296 260 AFW-PSF-FC-XCONN 1 l.500E-004 +O.OOOE+OOO +O.OOOE+OOO FLOW DIVERSION TO UNIT 2 THRU PIPE SEG PS94 261 AFW-TDP-FR-2PlHR 4 5.000E-003 5.000E-003 l.OOOE+OOO AFW TURBINE DRIVEN PUMP 2 FAILS TO RUN l HOUR 262 AFW-TDP-FR-2P6HR 4 3.000E-002 5.000E-003 6.000E+OOO AFW TURBINE DRIVEN PUMP 2 FAILS TO RUN FOR 6 HOURS 263 AFW-TDP-FR-6HRU2 4 3.000E-002 5.000E-003 6.000E+OOO UNIT 2 AFW TDP FAILS TO RUN FOR 6 HRS 264 AFW-TDP-FS-FW2 1 l.lOOE-002 +O.OOOE+OOO +O.OOOE+OOO TURBINE DRIVEN AFW PUMP FAILS TO START 1993/11/24 09:45:14 page 11 E-12

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 265 AFW-TDP-FS-U2FW2 1 l.lOOE-002 +O.OOOE+OOO +O.OOOE+OOO AFW TDP FW2 AT UNIT 2 FAILS TO START 266 AFW-TDP-MA-FW2 1 3.719E-001 +O.OOOE+OOO +0.000E+OOO TEST AND MAINTENANCE ON AFW TDP 2 - STATE 6 267 AFW-TDP-MA-U2FW2 .1 1.000E-002 +O.OOOE+OOO +0.000E+OOO TEST AND MAINTENANCE ON AFW UNIT 2 TDP 2 268 AFW-TDP-MAOFW2 1 4.907E-001 +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON AFW TDP 2 - STATE 10 269 AFW-TNK-VF-CST 1 1.000E-006 +O.OOOE+OOO +0.000E+OOO INSUF WATER AVAILABLE FROM 110 000 GALLON CST 270 AFW-TNK-VF-U2CST 1 1.000E-006 +O.OOOE+OOO +O.OOOE+OOO INSUF WATER AVAIL AFW UNIT2 CST 271 AFW-XHE-FO-ACT F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO OPERATOR FAILS TO INITIATE AND ALIGN MD AFW PUMPS AND FW151 272 AFW-XHE-FO-UlSBO F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO OPERATOR FAILS TO CROSS CONNECT TO UNIT 2 AFW SYSTEM 273 AFW-XHE-F0-U2SB0 F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO OP F~ILS TO XCONN AFW SBO AT Ul/U2 274 AFW-XVM-PG-XV120 1 4.000E-005 1.000E-007 7.200E+002 MANUAL VALVE XV120 PLUGGED 275 AFW-XVM-PG-XV153 1 4.000E-005 1.000E-007 7.200E+002 MANUAL VALVE XV153 PLUGGED 276 AFW-XVM-PG-XV158 1 4.000E-005 1.000E-007 7.200E+002 MANUAL VALVE XV158 PLUGGED 277 AFW-XVM-PG-XV168 1 4.000E-005 1.000E-007 7.200E+002 MANUAL VALVE XV168 PLUGGED 278 AFW-XVM-PG-XV183 1 4.000E-005 1.000E-007 7.200E+002 MANUAL VALVE XV183 PLUGGED 279 AFW-XVM-PG-XV253 1 4.000E-005 1.000E-007 7.200E+002 MANUAL VALVE XV253 PLUGGED 280 AFW-XVM-PG-XV87 1 4.000E-005 1.000E-007 7.200E+002 MANUAL VALVE XV87 PLUGGED 281 BAT-HTR-FC-TRACE 1 5.000E-004 +O.OOOE+OOO +O.OOOE+OOO HEAT TRACING FAILS AND IS NOT DETECTED 282 BAT-HTR-VF-STANK 1 2.600E-004 +O.OOOE+OOO +O.OOOE+OOO BORIC ACID STORAGE TANK HEATER FAILS AND NOT DETECTED 283 CCW-AOV-FT-109A 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO cc-TV-109A FAILS CLOSED 284 CCW-AOV-FT-109B 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO CC-TV-109B FAILS CLOSED 285 CCW-AOV-MA-109A 1 2.000E-004 +O.OOOE+OOO +O.OOOE+OOO CC-TV-109A UNSCHEDULED MAIMTENANCE 286 CCW-AOV-OC-109A 1 7.500E-007 +O.OOOE+OOO +O.OOOE+OOO CC-TV-109A TRANSFERS CLOSED 287 CCW-AOV-OC-109B 1 7.500E-007 +O.OOOE+OOO +O.OOOE+OOO CC-TV-109B TRANSFERS CLOSED 288 CCW-AOV-OC-140A 1 7.500E-007 +O.OOOE+OOO +O.OOOE+OOO TRIP VLV 140A TF CLOSED 1993/11/24 09:45:14 page 12

E-13

Event Number Primary Name BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Calculation Type Case: ALTERNATE Mean Probability Lamda Tau 289 CCW-AOV-OC-140B 1 7.500E-007 +O.OOOE+OOO +O.OOOE+OOO CC-TV-140B TRANSFERS CLOSED 290 CCW-AOV-PG-109A 1 4.000E-005 1.000E-007 7.200E+002 CC-TV-109A PLUGS DURING OPERATION 291 CCW-AOV-PG-109B 1 4.000E-005 1.000E-007 7.200E+002 CC-TV-109B PLUGS DURING OPERATION 292 CCW-AOV-PG-140A 1 4.000E-005 +O.OOOE+OOO +0.000E+OOO TRIP VLV 140A PLUGGED 293 CCW-AOV-PG-140B 1 4.000E-005 +O.OOOE+OOO +0.000E+OOO CC-TV-140B PLUGGED 294 CCW-AOV-SC-120A 1 7.500E-007 +O.OOOE+OOO +O.OOOE+OOO AOV TRIP VALVE CC-TV-120A SP. CLOSES 295 CCW-AOV-SC-120B 1 7.SOOE-007 +0.000E+OOO +O.OOOE+OOO AOV TRIP VALVE CC-TV-120B SP. CLOSES 296 CCW-AOV-SC-120C 1 7.500E-007 +O.OOOE+OOO +0.000E+OOO AOV TRIP VALVE CC-TV-120C SP. CLOSES 297 CCW-AOV-XHE-109 1 1.700E-003 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Open 109 Valves Using a Portable Bottle 298 CCW-CCF-FT-8185 1 1.250E-005 +O.OOOE+OOO +O.OOOE+OOO CCF OF VALVES CC181 AND CC185. FAIL TO OPEN 299 CCW-CKV-FT-CC176 1 1.000E-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CC176 FAILS TO OPEN 300 CCW-CKV-FT-CC177 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OO CHECK VALVE CC177 FAILS TO OPEN 301 CCW-CKV-FT-CC563 1 1.000E-004 +0.000E+OOO +O.OOOE+OOO CHECK VALVE CC563 FAILS TO OPEN 302 CCW-CKV-FT-CV557 1 1.000E-004 +O.OOOE+OOO +0.000E+OOO CHECK VALVE CVSS7 FAILS TO CLOSE 303 CCW-CKV-00-563U2 1 l.OOOE-003 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CVS63U2 FLS TO SHUT CAUSE BACKFLOW 304 CCW-CKV-00-CVSS7 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV557 FAILS TO SHUT CAUSE BACKFLOW 305 CCW-HTX-LK-ElA 4 7.200E-005 3.000E-006 2.400E+001 CCW HEAT EXCHANGER ElA LEAKS 306 CCW-HTX-LK-E1B 4 7.200E-005 3.000E-006 2.400E+001 CCW HEAT EXCHANGER E1B LEAKS 307 CCW-HTX-LK-U2E1A 4 7.200E-005 3.000E-006 2.400E+001 CCW UNIT 2 HEAT EXCHANGER E1A LEAKS 308 CCW-HTX-MA-E1B 1 1.452E-001 +O.OOOE+OOO +O. OOOE+o*oo TEST AND MAINTENANCE HT EXCHGR ElB - STATE 6 309 CCW-HTX-MA-U2E1A 1 +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON CCW UNIT 2 HT EXCHGR E1B - STATE 6 310 CCW-HTX-MAOE1B 1 8.946E-001 +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE HT EXCHGR E1B - STATE 10 311 CCW-HTX-MAOU2E1A 1 5.280E-002 +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON CCW UNIT 2 HT EXCHGR E1B - STATE 10 312 CCW-HTX-PG-ElA 4 l.368E-004 5.700E-006 2.400E+001 CCW HEAT EXCHANGER E1A PLUGGED 1993/11/24 09:45:14 page 13 E-14

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 313 CCW-HTX-PG-ElB 4 1.368E-004 5.700E-006 2.400E+001 CCW HEAT EXCHANGER ElB PLUGGED 314 CCW-HTX-PG-U2E1A 4 1.368E-004 5.700E-006 2.400E+001 CCW UNIT 2 HEAT EXCHANGER ElB PLUGGED 315 CCW-LF-PSlOlA 1 1.380E-002 +0.000E+OOO +O.OOOE+OOO PRESSURE CHANNEL CC-PS-101A LOSS OF FUNCTION 316 CCW-LF-RHE2A 1 1.860E-002 +O.OOOE+OOO +O.OOOE+OOO RHR PUMP SEAL COOLER RH-E-2A LOSS OF FUNCTION 317 CCW-LF-RHE2B 1 1.860E-002 +O.OOOE+OOO +O.OOOE+OOO RHR PUMP SEAL COOLER RH-E-2B LOSS OF FUNCTION 318 CCW-LF-STKl 1 2.660E-006 +O.OOOE+OOO +O.OOOE+OOO SURGE TANK 1-CC-TKl LOSS OF FUNCTION 319 CCW-MDP-FR-CCPlA 4 7.200E-004 3.000E-005 2.400E+001 1-CC-P-lA FAILS TO RUN 1-CC-P-lA FAILS TO RUN 320 CCW-MDP-FR-CCPlB 4 7.200E-004 3.000E-005 2.400E+001 MDP CC-PlB FAILS TO RUN 321 CCW-MDP-FR-CCP2A 4 1.800E-004 3.000E-005 6.000E+OOO MDP CC-P2A FAILS TO RUN FOR 6 HRS 322 CCW-MDP-FS-CCPlB 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO MDP CC-PlB FAILS TO START ON DEMAND 323 CCW-MDP-FS-CCP2A 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO MDP CC-P2A FAILS TO START ON DEMAND 324 CCW-MDP-MA-CCP1B 1 2.000E-003 +0.000E+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON MDP CC-P1B 325 CCW-MDP-MA-CCP2A 1 2.000E-003 +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON MDP CC-P2A 326 CCW-SO-RV116A 1 9.330E-005 +O.OOOE+OOO +O.OOOE+OOO RELIEF VALVE RV 116A SP. OPEN 327 CCW-SO-RV116B 1 9.330E-005 +O.OOOE+OOO +O.OOOE+OOO RELIEF VALVE RV 116B SP. OPEN 328 CCW-S0-RV116C 1 9.330E-005 +O.OOOE+OOO +O.OOOE+OOO RELIEF VALVE RV 116C SP. OPEN 329 CCW-SO-RV118 1 9.330E-005 +O.OOOE+OOO +O.OOOE+OOO RELIEF VALVE CC-RV-118 SP. OPEN 330 CCW-SO-RV119A 1 9.330E-005 +O.OOOE+OOO +O.OOOE+OOO RELIEF VALVE RV 119A SP. OPEN 331 CCW-SO-RV119B 1 9.330E-005 +O.OOOE+OOO +O.OOOE+OOO RELIEF VALVE RV 119B SP. OPEN 332 CCW-SO-RV121 1 9.330E-OOS +O.OOOE+OOO +O.OOOE+OOO RELIEF VALVE CC-RV-121 SP. OPEN 333 CCW-XHE-10P14.1 1 l.200E-005 +O.OOOE+OOO +O.OOOE+OOO OP-14.1 RHR STEP 5.2 OPEN CC-TV-109B 334 CCW-XHE-lOPSl.1 1 2.lOOE-005 +O.OOOE+OOO +O.OOOE+OOO 1-0P-51.1 COMP. COOLING SUBSYSTEM 335 CCW-XHE-FO-SPlB 1 l.600E-004 +O.OOOE+OOO +O.OOOE+OOO OP. FAILS TO RESTORE PUMP SWITCH AFTER TEST & MAINTENANCE 336 CCW-XMV-PG-CClOO 1 4.000E-005 1.000E-007 7.200E+002 BUTTERFLY VALVE CClOO PLUGS (DURING OPERATION) 1993/11/24 09:45:14 page 14

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Event Number Primary Name BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Calculation Type Case: ALTERNATE Mean Probability Lamda Tau 337 CCW-XMV-PG-CC104 1 4.000E-005 1.000E-007 7.200E+002 BUTTERFLY VALVE CC104 PLUGS DURING OPERATION 338 CCW-XMV-PG-CC112 1 4.000E-005 1.000E-007 7.200E+002 GLOBE VALVE CC112 PLUGGED 339 CCW-XMV-PG-CC116 1 4.000E-005 l.OOOE-007 7.200E+002 GATE VALVE CC116 PLUGGED 340 CCW-XMV-PG-CCllB 1 4.000E-005 l.OOOE-007 7.200E+002 GLOBE VALVE CCllB PLUGGED 341 CCW-XMV-PG-CC122 1 4.000E-005 l.OOOE-007 7.200E+002 GATE VALVE CC122 PLUGGED 342 CCW-XMV-PG-CC178 1 4.000E-005 l.OOOE-007 7.200E+002 BUTTERFLY VALVE CC178 PLUGS DURING OPERATION 343 CCW-XMV-PG-CC181 1 4.000E-005 l.OOOE-007 7.200E+002 BUTTERFLY VALVE CC181 PLUGS DURING OPERATION 344 CCW-XMV-PG-CC182 1 4.000E-005 l.OOOE-007 7.200E+002 BUTTERFLY VALVE CC182 PLUGS DURING OPERATION 345 CCW-XMV-PG-CC185 1 4.000E-005 l.OOOE-007 7.200E+002 BUTTTERFLY VALVE CC185 PLUGS DURING OPERATION 346 CCW-XMV-PG-CC214 1 4.000E-005 l.OOOE-007 7.200E+002 BUTTERFLY VALVE CC-214 PLUGS DURING OPERATION 347 CCW-XMV-PG-CC220 1 4.000E-005 l.OOOE-007 1.680E+002 BUTTERFLY VALVE CC220 PLUGS (DURING OPERATION) 348 CCW-XVM-FT-CC181 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO BUTTERFLY VALVE CC181 FAILS TO OPEN 349 CCW-XVM-FT-CC185 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO BUTTERFLY VALVE CC185 FAILS TO OPEN 350 CCW-XVM-PG-580U2 1 4.000E-005 l.OOOE-007 7.200E+002 MANUAL VALVE XV580 (U2) PLUGGED 351 CCW-XVM-PG-583U2 1 4.000E-005 l.OOOE-007 7.200E+002 MANUAL VALVE XV583 (U2) PLUGGED 352 CCW-XVM-PG-CC104 1 4.400E-004 l.OOOE-007 8.760E+003 BUTTERFLY VALVE CC104 PLUGGED DURING STANDBY 353 CCW-XVM-PG-CC178 1 4.400E-004 +O.OOOE+OOO +Q.OOOE+OOO BUTTERFLY VALVE CC178 PLUGGED DURING STANDBY 354 CCW-XVM-PG-CC182 1 4.400E-004 +O.OOOE+OOO +O.OOOE+OOO BUTTERFLY VALVE CC182 PLUGGED DURING SRANDBY 355 CCW-XVM-PG-CC214 1 4.400E-004 +O.OOOE+OOO +O.OOOE+OOO BUTTERFLY VALVE CC-214 PLUGGED DURING STANDBY 356 CCW-XVM-PG-CC560 1 4.000E-005 l.OOOE-007 7.200E+002 BUTTERFLY VALVE CC560 PLUGGED 357 CCW-XVM-PG-CC564 1 4.000E-005 l.OOOE-007 7.200E+002 BUTTERFLY VALVE CC564 PLUGGED 358 CCW-XVM-PG-XV580 1 4.000E-005 l.OOOE-007 7.200E+002 MANUAL VALVE XV580 PLUGGED 359 CCW-XVM-PG-XV583 1 4.000E-005 l.OOOE-007 7.200E+002 MANUAL VALVE XV583 PLUGGED 360 CCW-XVM-PG-XV584 1 4.000E-005 l.OOOE-007 7.200E+002 MANUAL VALVE XV584 PLUGGED 1993/11/24 09:45:14 page 15 E-16

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 361 CCW-XVM-PG-XV587 1 4.000E-005 1.000E-007 7.200E+002 MANUAL VALVE XV587 PLUGGED 362 CIA-AOV-FT-IA103 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO CONTAINMENT IA SUCTION VALVE FROM SGUARD BDG FAILS TO OPEN 363 CIA-AOV-PG-101A 1 4.000E-005 1.000E-007 +O.OOOE+OOO CIA SUCTION VALVE AOV-IA-101A PLUGGED 364 CIA-AOV-PG-101B 1 4.000E-005 1.000E-007 +O.OOOE+OOO CIA SUCTION VALVE 101B PLUGGED 365 CIA-AOV-PG-TV100 1 4.000E-005 1. OOOE-007 +O.OOOE+OOO CIA-AOV-PG-TVlOO 366 CIA-CCF-FR-IAC4 2 4.SOOE-004 2.000E-005 +O.OOOE+OOO COMMON MODE FAILURE OF CIA COMPRESSORS TO RUN 367 CIA-CPS-FR-IAC4A 2 4.SOOE-003 2.000E-004 +O.OOOE+OOO CONTAINMENT INSTRUMENT AIR COMPRESSOR 1-IA-C-4A FAILS TO RUN 368 CIA-CPS-FR-IAC4B 2 4.SOOE-003 2.000E-004 +O.OOOE+OOO CONTAINMENT INSTRUMENT AIR COMPRESSOR 1-IA-C-4B FAILS TO RUN 369 CIA-CPS-FS-IAC4B 1 8.000E-002 +O.OOOE+OOO +O.OOOE+OOO CONTAINMENT INSTRUMENT AIR COMPRESSOR 1-IA-C-4B FAILSTOSTART 370 CIR-COND-UNAVLBL 1 1.000E-002 +O.OOOE+OOO +O.OOOE+OOO condenser unavailable 371 CKV-CCF-FT-CLDLG 1 1.000E-005 +O.OOOE+OOO +O.OOOE+OOO CCF OF CV79 CV82 AND eves 372 CKV-CCF-FT-HTLG1 1 1.000E-005 +O.OOOE+OOO +O.OOOE+OOO CCF OF CV88 CV91 AND CV94 373 CKV-CCF-FT-HTLG2 1 1.000E-005 +O.OOOE+OOO +O.OOOE+OOO CCF OF CV238 CV239 AND CV240 374 CLS-ACT-FA-CLS2A 1 1. 600E-003 +O.OOOE+OOO +O.OOOE+OOO NO SIGNAL FROM CLCS TRAIN A 375 CLS-ACT-FA-CLS2B 1 1.600E-003 +O.OOOE+OOO +O.OOOE+OOO NO SIGNAL FROM CLCS TRAIN B 376 CLS-ACT-OP-CLS2 F +0.000E+OOO +O.OOOE+OOO +0,. OOOE+OOO NO OPER ACT'N 377 CON-VFC-RP-COREM 1 2.000E-002 +O.OOOE+OOO +O.OOOE+OOO loss of HPSH due to open containment 378 CONT/AFW-SGN F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO ACTUATION TRIP SIGNAL PRESENT 379 CPC-AOV-FT-108B 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO AOV TV-CC-108B FAILS TO OPEN 380 CPC-AOV-FT-108C 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO AOV TV-CC-108C FAILS TO OPEN

3a1 CPC-CCF-FT-8BC 1 1.000E-004 +O.OOOE+OOO +O.OOOE+OOO COMMON MODE FAILURE OF CPC TCV8B/C TO OPEN 382 CPC-CCF-LF-STRl 1 4.700E-005 7.900E-006 6.000E+OOO CCF OF STRAINERS lA & lB CCF OF STRAINERS lA & lB 383 CPC-CCF-LF-STRAB 1 4.700E-005 7.900E-006 6.000E+OOO COMMON MODE LOSS OF FLW STRAINERS 2A AND 2B 384 CPC-CKV-FT-CV108 1 1.000E-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV108 FAILS TO OPEN 1993/11/24 09:45:14 page 16

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Event Number Primary Name BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Calculation Type Case: ALTERNATE Mean Probability Lamda Tau 385 CPC-CKV-FT-CV262 1 1.000E-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV262 FAILS TO OPEN 386 CPC-CKV-FT-CV752 1 1.000E-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV752 FAILS TO OPEN 387 CPC-CKV-OO-CV113 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV113 FAILS TO SHUT CAUSE BACKFLOW 388 CPC-CKV-OO-CV764 1 1.000E-003 +0.000E+OOO +0.000E+OOO CHECK VALVE CV764 FAILS TO SHUT CAUSE BACKFLOW 389 CPC-ICC-FA-CCPBS 1 3.200E-004 +O.OOOE+OOO +0.000E+OOO NO ACTUATION SIGNAL TO START CPC PUMP 2B 390 CPC-ICC-FA-SWPBS 1 3.200E-004 +0.000E+OOO +0.000E+OOO NO ACTUATION SIGNAL TO START SW PUMP lOB 391 CPC-ICC-FA-TCV8B 1 1.600E-003 +0.000E+OOO +0.000E+OOO NO ACTUATION SIGNAL TO LUBE OIL COOLING TCV8B 392 CPC-ICC-FA-TCV8C 1 1.600E-003 +0.000E+OOO +O.OOOE+OOO NO ACTUATION SIGNAL TO LUBE OIL COOLING TCV8 393 CPC-MDP-FR-2CC2A 4 1.800E-004 3.000E-005 6.000E+OOO MDP CC2A U2 FAILS TO RUN FOR 6 HOURS 394 CPC-MDP-FR-CC2A 4 7.200E-004 3.000E-005 2.400E+001 MDP CC2A FAILS TO RUN AS LONG AS CHRGNG PUMPS 395 CPC-MDP-FR-CC2B 4 7.200E-004 3.000E-005 2.400E+001 MDP CC2B FAILS TO RUN FOR 24 HOURS 396 CPC-MDP-FR-SWlOA 1 3.840E-003 1.600E-004 2.400E+OO MDP SWlOA FAILS TO RUN AS LONG AS CHARGING PUMPS 397 CPC-MDP-FR-SWlOB 1 3.840E-003 1.600E-004 2.400E+001 MDP SWlOB FAILS TO RUN FOR 24 HRS 398 CPC-MDP-FR-SW20A 1 9.600E-004 1.600E-004 6.000E+OOO MDP SW20A FAILS TO RUN FOR 6 HRS 399 CPC-MDP-FS-2CC2A 1 3.000E-003 +O.OOOE+OOO +0.000E+OOO MDP UNIT 2 CC2A FAILS TO START 400 CPC-MDP-FS-CC2B 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO MDP CC2B FAILS TO START 401 CPC-MDP-FS-SWlOB 1 8.000E-003 +0.000E+OOO +0.000E+OOO MDP SWlOB FAILS TO START 402 CPC-MDP-FS-SW20A 1 8.000E-003 +0.000E+OOO +O.OOOE+OOO MDP SW20A FAILS TO START 403 CPC-MDP-MA-CC2B 1 2.000E-003 +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON MDP CC2B 404 CPC-MDP-MA-SWlOA 1 +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON MDP SWlOA - STATE 6 405 CPC-MDP-MA-SWlOB 1 9.274E-001 +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON MDP SWlOB - STATE 6 406 CPC-MDP-MAOCC2B 1 2.000E-003 +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON MDP CC2B 407 CPC-MDP-MAOSWlOB 1 4.473E-001 +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON MDP SW10B - STATE 10 408 CPC-STR-PG-1AU26 4 1.800E-004 3.000E-005 6.000E+OOO CPC STRAINER lA UNIT 2 PLUGGED W/IN 6 HR 1993/11/24 09:45:14 page 17 E-18

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean

. Number Primary Name Type Probability Lamda Tau 409 CPC-STR-PG-2AU26 4 l.BOOE-004 3.000E-005 6.000E+OOO CPC STRAINER 2A UNIT 2 PLUGGED W/IN 6 HR 410 CPC-STR-PG-STR1A 4 l.SOOE-004 3.000E-005 6.000E+OOO STRAINER lA PLUGGED 411 CPC-STR-PG-STRlB 4 l.SOOE-004 3.000E-005 6.000E+OOO STRAINER lB PLUGGED 412 CPC-STR-PG-STR2A 4 l.BOOE-004 3.000E-005 6.000E+OOO STRAINER 2A PLUGGED W/IN 6 HRS 413 CPC-STR-PG-STR2B 4 l.BOOE-004 3.000E-005 6.000E+OOO STRAINER 2B PLUGGED W/IN 6 HRS 414 CPC-XVM-PG-2SW11 6 8.400E-006 l.OOOE-007 l.680E+002 MANUAL VALVE 2-sw-11 PLUGGED 415 CPC-XVM-PG-SW474 6 8.400E-006 l.OOOE-007 l.680E+002 MANUAL VALVE 2-SW-474 PLUGGED 416 CPC-XVM-PG-XV109 1 8.400E-006 l.OOOE-007 l.680E+002 MANUAL VALVE XV109 PLUGGED 417 CPC-XVM-PG-XV117 1 3.650E-005 l.OOOE-007 7.200E+002 MANUAL VALVE XV117 PLUGGED 418 CPC-XVM-PG-XV118 1 8.400E-006 l.OOOE-007 1.680E+002 MANUAL VALVE XV118 PLUGGED 419 CPC-XVM-PG-XV119 1 8.400E-006 l.OOOE-007 1.680E+002 MANUAL VALVE XV119 PLUGGED 420 CPC-XVM-PG-XV120 1 3.650E-005 l.OOOE-007 7.200E+002 MANUAL VALVE XV120 PLUGGED 421 CPC-XVM-PG-XV122 1 3.650E-005 1. OOOE-007. 7.200E+002 MANUAL VALVE XV122 PLUGGED 422 CPC-XVM-PG-XV123 1 3.650E-005 1.000E-007 7.200E+002 MANUAL VALVE XV123 PLUGGED 423 CPC-XVM-PG-XV124 1 3.650E-005 l.OOOE-007 7.200E+002 MANUAL VALVE XV124 PLUGGED 424 CPC-XVM-PG-XV125 1 3.650E-005 1.000E-007 7.200E+002 MANUAL VALVE XV125 PLUGGED 425 CPC-XVM-PG-XV126 1 3.650E-005 l.OOOE-007 7.200E+002 MANUAL VALVE XV126 PLUGGED 426 CPC-XVM-PG-XV170 1 3.650E-005 l.OOOE-007 7.200E+002 MANUAL VALVE XV170 PLUGGED 427 CPC-XVM-PG-XV171 1 8.400E-006 l.OOOE-007 1. 680E+002 MANUAL VALVE XV171 PLUGGED 428 CPC-XVM-PG-XV172 1 3.6508-005 l.OOOE-007 7.200E+002 MANUAL VALVE XV172 PLUGGED 429 CPC-XVM-PG-XV173 1 3.650E-005 1.000E-007 7.200E+002 MANUAL VALVE XV173 PLUGGED 430 CPC-XVM-PG-XV261 1 8.400E-006 1.000E-007 1.680E+002 MANUAL VALVE XV261 PLUGGED 431 CPC-XVM-PG-XV305 1 8.400E-006 l.OOOE-007 1.680E+002 MANUAL VALVE XV305 PLUGGED 432 CPC-XVM-PG-XV306 1 8.400E-006 1. OOOE-007 1.680E+002 MANUAL VALVE XV306 PLUGGED 1993/11/24 09:45:14 page 18

E-19

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 433 CPC-XVM-PG-XV701 1 3.650E-005 l.OOOE-007 7.200E+002 MANUAL VALVE XV701 PLUGGED 434 CPC-XVM-PG-XV781 1 3.650E-005 l.OOOE-007 7.200E+002 MANUAL VALVE XV781 PLUGGED 435 CSS-CCF-FS-CSlAB 1 3.300E-004 +O.OOOE+OOO +0.000E+OOO COMMON CAUSE FAILURE OF CSS MDPS TO START 436 CSS-CCF-FT-lOlAB 1 2.600E-004 +O.OOOE+OOO +O.OOOE+OOO COMMON CAUSE FAILURE OF CSS MOVS 101A AND 101 437 CSS-CCF-FT-lOlCD 1 2.600E-004 +O.OOOE+OOO +O.OOOE+OOO COMMON CAUSE FAILURE OF CSS MOVS 101C AND 101 438 CSS-CKV-FT-CV13 1 1.000E-004 +O.OOOE+OOO +0.000E+OOO CHECK VALVE CV13 FAILS TO OPEN ON DEMAND 439 CSS-CKV-FT-CV24 1 1.000E-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV24 FAILS TO OPEN ON DEMAND 440 CSS-FLT-PG-CSlA 1 3.000E-005 3.000E-005 1.000E+OOO FILTER FLCSlA PLUGGED 441 CSS-FLT-PG-CSlB 1 3.000E-005 3.000E-005 1.000E+OOO FILTER FLCSlB PLUGGED 442 CSS-MDP-FR-lAlHR 4 3.000E-005 3.000E-005 1.000E+OOO CSS MDP lA FAILS TO RUN FOR 1 HOUR 443 CSS-MDP-FR-1BlHR 4 3.000E-005 3.000E-005 1.000E+OOO CSS MDP lB FAILS TO RUN FOR 1 HOUR 444 CSS-MDP-FS-CSlA 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OO CSS MDP lA FAILS TO START ON DEMAND 445 CSS-MDP-FS-CSlB 1 3.000E-003 +0.000E+OOO +O.OOOE+OOO CSS MDP lB FAILS TO START ON DEMAND 446 CSS-MDP-MA-CSlA 1 2.000E-003 +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON CSS MDP lA 447 CSS-MDP-MA-CSlB 1 2.000E-003 +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON CSS MDP lB 448 CSS-MDP-MAOCSlB 1 2.000E-003 +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON CSS MDP lB 449 CSS-MDP-OP-AB F +0.000E+OOO +O.OOOE+OOO +O.OOOE+OOO NO OPER ACT'N CSS SYSTEM POS 3-13 450 CSS-MOV-FT-lOlA 1 3.000E-003 +O.OOOE+OOO +0.000E+OOO MOTOR OPER VALVE 101A FAILS TO OPEN ON DEMAND 451 CSS-MOV-FT-lOlB 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO MOTOR OPER VALVE 101B FAILS TO OPEN ON DEMAND 452 CSS-MOV-FT-101C 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO MOTOR OPER VALVE 101C FAILS TO OPEN ON DEMAND 453 CSS-MOV-FT-101D 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO MOTOR OPER VALVE 101D FAILS TO OPEN ON DEMAND 454 CSS-MOV-PG-lOOA 1 1.095E-004 1. OOOE-007 2.160E+003 MOTOR OPERATED VALVE 100A PLUGGED 455 CSS-MOV-PG-100B 1 1.095E-004 1.000E-007 2.160E+003 MOTOR OPERATED VALVE lOOB PLUGGED 456 CSS-TRA-MA 1 2.500E-001 +O.OOOE+OOO +O.OOOE+OOO UN AVAIL OF TRAIN A (MAINT) 1993/11/24 09:45:14 page 19 E-20

Event Number Primary Name BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Calculation Type Case: ALTERNATE Mean Probability Lamda Tau 457 CSS-XVM-RE-XV15 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO MANUAL VLV XV15 LEFT OPEN FOLLOWING PUMP TEST 458 CSS-XVM-RE-XV8 1 3.000E-003 +0.000E+OOO +O.OOOE+OOO MANUAL VLV XV8 LEFT OPEN FOLLOWING PUMP TEST 459 CVC-MDP-FR-2A1HR 4 3.000E-005 3.000E-005 l.OOOE+OOO BORIC ACID TRANSFER PUMP FAIL TO RUN 1 HOUR 460 D-F1B2Wl-XHE 1 1.700E-002 +O.OOOE+OOO +O.OOOE+OOO Failure to Diagnose Loss of RHR Event in POS 6 461 D-F1B2W2-XHE 1 1.300E-002 +O.OOOE+OOO +O.OOOE+OOO Failure to Diagnose Loss of RHR Event in POS 6 462 D-F1B2W3-XHE 1 1.300E-002 +O.OOOE+OOO +O.OOOE+OOO Failure to Diagnose Loss of RHR Event in POS 6 463 D-F1B2W4-XHE 1 1.200E-003 +O.OOOE+OOO +O.OOOE+OOO Failure to Diagnose Loss of RHR Event in POS 6 464 D-F2B2Wl-XHE 1 1.700E-002 +O.OOOE+OOO +O.OOOE+OOO Failure to Diagnose Loss of RHR Event in POS 6 465 D-F2B2W2-XHE 1 1.300E-002 +O.OOOE+OOO +O.OOOE+OOO Failure to Diagnose Loss of RHR Event in POS 6 466 D-F2B2W3-XHE 1 1.300E-002 +O.OOOE+OOO +O.OOOE+OOO Failure to Diagnose Loss of RHR Event in POS 6 467 D-F2B2W4-XHE 1 l.200E-003 +O.OOOE+OOO +O.OOOE+OOO Failure to Diagnose Loss of RHR Event in POS 6 468 D-F3R3Wl-XHE 1 l.600E-003 +O.OOOE+OOO +O.OOOE+OOO Failure to Diagnose Loss of RHR Event in POS 6 469 D-F3R3W2-XHE 1 6.200E-004 +O.OOOE+OOO +O.OOOE+OOO Failure to Diagnose Loss of RHR Event in POS 6 470 D-F3R3W3-XHE 1 6.200E-004 +O.OOOE+OOO +O.OOOE+OOO Failure to Diagnose Loss of RHR Event in POS 6 471 D-F3R3W4-XHE 1 l.400E-004 +O.OOOE+OOO +O.OOOE+OOO Failure to Diagnose Loss of Inventory in Window 4 472 D-F4R3Wl-XHE 1 l.600E-003 +O.OOOE+OOO +O.OOOE+OOO Failure to Diagnose Loss of RHR Event in POS 6 473 D-F4R3W2-XHE 1 6.200E-004 +O.OOOE+OOO +O.OOOE+OOO Failure to Diagnose Loss of RHR Event in POS 6 474 D-F4R3W3-XHE 1 6.200E-004 +O.OOOE+OOO +O.OOOE+OOO Failure to Diagnose Loss of RHR Event in POS 6 475 D-F4R3W4-XHE 1 l.400E-004 +O.OOOE+OOO +O.OOOE+OOO Failure to Diagnose Loss of Inventory in Window 4 476 D-FSR3Wl-XHE 1 l.300E-002 +O.OOOE+OOO +O.OOOE+OOO Failure to Diagnose Loss of RHR Event in POS 6 477 D-FSR3W2-XHE 1 6.400E-003 +O.OOOE+OOO +O.OOOE+OOO Failure to Diagnose Loss of RHR Event in POS 6 478 D-FSR3W3-XHE 1 6.400E-003 +O.OOOE+OOO +O.OOOE+OOO Failure to Diagnose Loss of RHR Event in POS 6 479 D-FSR3W4-XHE 1 9.400E-004 +O.OOOE+OOO +O.OOOE+OOO Failure to Diagnose Loss of Inventory in Window 4 480 D-F7B2Wl-XHE 1 1.700E-002 +O.OOOE+OOO +O.OOOE+OOO Failure to Diagnose Loss of RHR Event in POS 6 1993/11/24 09:45:14 page 20 E-21

Event Number Primary Name BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Calculation Type Case: ALTERNATE Mean Probability Lamda Tau 481 D-F7B2W2-XHE 1 1.300E-002 +0.000E+OOO +O.OOOE+OOO Failure to Diagnose Loss of RHR Event in POS 6 482 D-F7B2W3-XHE 1 l.300E-002 +O.OOOE+OOO +O.OOOE+OOO Failure to Diagnose Loss of RHR Event in POS 6 483 D-F7B2W4-XHE 1 1.200E-003 +0.000E+OOO +0.000E+OOO Failure to Diagnose Loss of RHR Event in POS 6 484 DCP-BAT-LP-BATlA 1 7.200E-004 l.OOOE-006 l.440E+003 FAILURE OF BATTERY lA 485 DCP-BAT-LP-BATlB 1 7.200E-004 1. OOOE-006 1.440E+003 FAILURE OF BATTERY lB 486 DCP-BDC-MA-BATlB F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON BATTERY lB - STATE 6 487 DCP-BDC-MAOBATlB F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON BATTERY lB - STATE 10 488 DCP-BDC-ST-BUSlA 1 9.000E-005 +O.OOOE+OOO +O.OOOE+OOO 125V DC BUS lA BUSWORK FAILURE 489 DCP-BDC-ST-BUSlB 1 9.000E-005 +O.OOOE+OOO +O.OOOE+OOO 125V DC BUS lB BUSWORK FAILURE 490 DCP-CCF-LP-BTlAB 1 5.800E-006 +0.000E+OOO +O.OOOE+OOO COMMON CAUSE FAILURE OF BATTERY lA AND lB 491 DCP-CRB-C0-19 1 2.900E-005 +0.000E+OOO +O.OOOE+OOO DC CIRCUIT BREAKER 19 TRANSFERS OPEN 492 DCP-CRB-C0-20 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO DC CIRCUIT BREAKER 20 TRANSFERS OPEN 493 DCP-CRB-C0-23 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO DC CIRCUIT BREAKER 23 TRANSFERS OPEN 494 DCP-CRB-C0-24 1 2.900E-005 +O.OOOE+OOO +O.OOOE+OOO DC CIRCUIT BREAKER 24 TRANSFERS OPEN 495 DR-MT 1 1.200E+OOO +O.OOOE+OOO +O.OOOE+OOO Drained Maintanence 496 DURATION-D6 1 2.SSOE+002 +O.OOOE+OOO +O.OOOE+OOO Duration of PCS 6 of Drained Maintenance Outage 497 DURATION-RlO 1 4.440E+002 +O.OOOE+OOO +O.OOOE+OOO Duration of POS 10 of Refueling Outage 498 DURATION-R6 1 2.380E+002 +O.OOOE+OOO +O.OOOE+OOO Duration of R6 of Refuel 499 FL-BCKFL-CKV 1 1.000E-002 +O.OOOE+OOO +O.OOOE+OOO BACKFLOW CHECK VALVE TO HPI* PUMP CUBICLES 500 FL-HPI-MDP-CHlA F . +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO AUX BLDG FLOOD CHARGING PUMP DISABLED 501 FL-HPI-MDP-CHlB F +O.OOOE+OOO +O.OOOE+OOO +O. 00.0E+OOO AUX BLDG FLOOD CHARGING PUMP DISABLED 502 FL-HPI-MDP-CHlC F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO AUX BLDG FLOOD CHARGING PUMP DISABLED 503 FL-HPI-MOV-1115D F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO AUX BLDG FLOOD MOV DISABLED 504 FL-HPI-MOV-1115E F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO AUX BLDG FLOOD MOV DISABLED 1993/11/24 09:45:14 page 21 E-22

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 505 FL-HPI-MOV-1269A F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO AUX BLDG FLOOD MOV DISABLED 506 FL-HPI-MOV-1270A F +0.000E+OOO +O.OOOE+OOO +O.OOOE+OOO AUX BLDG FLOOD MOV DISABLED 507 FL-HPI-MOV-1286B F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO AUX BLDG FLOOD MOV DISABLED 508 FL-HPI-MOV-1286C F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO AUX BLDG FLOOD MOV DISABLED 509 FL-HPI-MOV-1867C F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO AUX BLDG FLOOD MOV DISABLED 510 FL-HPI-MOV-1867D F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO AUX BLDG FLOOD MOV DISABLED 511 FL-LPI-MDP-PMP1A F +0.000E+OOO +O.OOOE+OOO +O.OOOE+OOO SAFEGUARD AREA FLOOD LPI PMP DISABLED 512 FL-LPI-MDP-PMP1B F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO SAFEGUARD AREA FLOOD LPI PMPS DISABLED 513 FL-RWT-TNK-RWST F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO RWST SUPPLY PIPE RUPTURE DISABLES RWST 514 FL-SCl-1 T l.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TURBINE BLDG/ESGR FLOOD LOSS OF 4KV 515 FRAC-POSlO 1 5.000E-001 +O.OOOE+OOO +O.OOOE+OOO Probability of POS 10 Given Refueling Outage 516 FREQ-FlB2 1 l.600E-008 +O.OOOE+OOO +O.OOOE+OOO Frequency of B2 LOSP 517 FREQ-F2B2 1 3.SOOE-009 +O.OOOE+OOO +O.OOOE+OOO Frequency of B2 LOSP 518 FREQ-F3RHR3 1 l.040E-008 +O.OOOE+OOO +O.OOOE+OOO FREQUENCY OF FLOOD F3 IN AUX BLDG 519 FREQ-F4RHR3 1 7.650E-009 +O.OOOE+OOO +O.OOOE+OOO FREQUENCY OF FLOOD F4 IN AUX BLDG 520 FREQ-FSRHR3 1 l.070E-008 +O.OOOE+OOO +O.OOOE+OOO FREQUENCY OF FLOOD F5 IN SAFEGUARD BLDG 521 FREQ-F7B2 1 8.410E-Oll +O.OOOE+OOO +O.OOOE+OOO FREQUENCY OF MECH EQ RM FLOOD F7 522 FREQ-RHR3 1 4.170E-006 +O.OOOE+OOO +O.OOOE+OOO Frequency of Loss of RHR-3 during Mid-Loop 523 FREQ-RHR4 1 5.325E-006. +O.OOOE+OOO +O.OOOE+OOO Frequency of Loss of RHR-4 during Mid-Loop 524 HOUSE-AIR T l.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO Not Loss of Instrument Air 525 HOUSE-ALOCA F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO LARGE LOCA 526 HOUSE-LOSP F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO HOUSE EVENT LOSS OF OFSITE POWER 527 HOUSE-NOT-POS313 F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO NOT POS 3-13 528 HOUSE-NOT-POS412 F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO IN POS 1-3 13-15 1993/11/24 09:45:14 page 22 E-23

Event Number Primary Name BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Calculation Type Case: ALTERNATE Mean Probability Lamda Tau 529 HOUSE-POS313 T 1.000E+OOO +O.OOOE+OOO +O.OOOE+OOO POS 3-13 530 HOUSE-POS412 T 1.000E+OOO +O.OOOE+OOO +O.OOOE+OOO IN POS 4-12 531 HOUSE-RHR5A F +O.OOOE+OOO +0.000E+OOO +O.OOOE+OOO Loss of Operating Train 532 HOUSE-SBOl F +O.OOOE+OOO +0.000E+OOO +O.OOOE+OOO ONE UNIT SEO 533 HOUSE-SB02 F +O.OOOE+OOO +0.000E+OOO +O.OOOE+OOO TWO UNIT SEO 534 HPI-CCF-FS-CHlBC 1 8.400E-004 +0.000E+OOO +O.OOOE+OOO COMMON CAUSE FAILURE TO START MDPS CHlB CHlC 535 HPI-CCF-FT-115BD 1 2.600E-004 +O.OOOE+OOO +O.OOOE+OOO COMMON CAUSE FAILURE OF MOVS 1115B AND 1115D 536 HPI-CCF-FT-867CD 1 2.600E-004 +O.OOOE+OOO +0.000E+OOO COMMON CAUSE FAILURE OF HPI MOVS 1867C 1867D 537 HPI-CCF-FT-869AB 1 2.600E-004 +O.OOOE+OOO +O.OOOE+OOO COMMON CAUSE FAILURE OF HPI MOVs 1869A 1869B 538 HPI-CKV-FT-CV225 1 1.000E-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV225 FAILS TO OPEN 539 HPI-CKV-FT-CV25 1 1.000E-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV25 FAILS TO OPEN 540 HPI-CKV-FT-CV267 1 1.000E-004 +O.OOOE+OOO +O.OOOE+OO CHECK VALVE CV267 FAILS TO OPEN 541 HPI-CKV-FT-CV276 1 1.000E-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV276 FAILS TO OPEN 542 HPI-CKV-FT-CV410 1 1.000E-004 +0.000E+OOO +O.OOOE+OOO CHECK VALVE CV410 FAILS TO OPEN 543 HPI-CKV-00-267U2 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO UNIT 2 CV267 FAILS TO SHUT CAUSE BACKFLOW 544 HPI-CKV-00-276U2 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO UNIT 2 CV276 FAILS TO SHUT CAUSE BACKFLOW 545 HPI-CKV-OO-CV258 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV258 FAILS TO SHUT CAUSE BACKFLOW 546 HPI-MDP-FR-1A6HR 4 3.780E-004 6.300E-005 6.000E+OOO CHARGING PUMP CHlA FAILS TO RUN FOR 6 HOURS 547 HPI-MDP-FR-1B6HR 4 3.780E-004 6.300E-005 6.000E+OOO CHARGING PUMP CHlB FAILS TO RUN FOR 6 HOURS 548 HPI-MDP-FR-1C12H 4 7.560E-004 6.300E-005 1. 200E+001 CHARGING PUMP CHlC FAILS TO RUN FOR 12 HOURS 549 HPI-MDP-FR-1C6HR 4 3.780E-004 6.300E-005 6.000E+OOO CHARGING PUMP CHlC FAILS TO RUN FOR 6 HOURS 550 HPI-MDP-FR-2C6HR 4 3.780E-004 6.300E-005 6.000E+OOO CHRGNG PMP U2 CH2C FAILS TO RUN FOR 6 HOURS 551 HPI-MDP-FS-CHlB 1 4.000E-003 +O.OOOE+OOO +O.OOOE+OOO CHARGING PUMP CHlB FAILS TO START ON DMD 552 HPI-MDP-FS-CHlC 1 4.000E-003 +O.OOOE+OOO +O.OOOE+OOO CHARGING PUMP CHlC FAILS TO START ON DMD 1993/11/24 09:45:14 page 23 E-24

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 553 HPI-MDP-FS-CH2C 1 4.000E-003 +O.OOOE+OOO +O.OOOE+OOO U2 CHARGING PUMP CH2C FAILS TO START 554 HPI-MDP-MA-CHlA F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO MAINTENANCE OF CHARGING PUMP lA-POS 6 555 HPI-MDP-MA-CHlB T 1.000E+OOO +0.000E+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON HPI MDP CHlB - STATE 6 556 HPI-MDP-MA-CHlC T 1.000E+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON HPI MDP CHlC - STATE 6 557 HPI-MDP-MAOCHlA F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO MAINTENANCE OF CHARGING PUMP lA-POS 10 558 HPI-MDP-MAOCHlB T 1.000E+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON HPI MDP CHlB -'STATE 10 559 HPI-MDP-MAOCHlC T 1.000E+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON HPI MDP CHlC - STATE 10 560 HPI-MOD-FT-101B 1 1.090E-002 +O.OOOE+OOO +O.OOOE+OOO MOTOR OPERATED DAMPER MOD-101B FAILS TO OPEN 561 HPI-MOD-FT-101C 1 1.090E-002 +O.OOOE+OOO +O.OOOE+OOO MOTOR OPERATED DAMPER MOD-101C FAILS TO OPEN 562 HPI-MOV-FT-1115B 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO HPI MOV 1115B FAILS TO OPEN ON DEMAND 563 HPI-MOV-FT-1115C 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO HPI MOV 1115C FAILS TO CLOSE 564 HPI-MOV-FT-1115D 1 3.000E-003 +0.000E+OOO +O.OOOE+OOO HPI MOV 1115D FAILS TO OPEN ON DEMAND 565 HPI-MOV-FT-1115E 1 3.000E-003 +O.OOOE+ooo* +O.OOOE+OOO HPI MOV 1115E FAILS TO CLOSE 566 HPI-MOV-FT-1350 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO HPI MOV 1350 FAILS TO OPEN 567 HPI-MOV-FT-1867C 1 3.000E-003 +0.000E+OOO +O.OOOE+OOO HPI MOV 1867C FAILS TO OPEN ON DEMAND 568 HPI-MOV-FT-1867D l 3. OOOE-003 +O. OOOE+OOO +O. OOOE+"OOO HPI MOV 1867D FAILS TO OPEN ON DEMAND 569 HPI-MOV-FT-1869A 1 3. OOOE-003 +O. OOOE+OOO * +O. OOOE+OOO MOV- 1869A FAILS TO OPEN ON DEMAND 570 HPI-MOV-FT-1869B 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO MOV- 1869B FAILS TO OPEN ON DEMAND 571 HPI-MOV-PG-1115B 1 4.000E-005 l.OOOE-007 7.200E+002 MOTOR OPERATED VALVE 1115B PLUGGED 572 HPI-MOV-PG-1115D 1 4.000E-005 l.OOOE-007 7.200E+002 MOTOR OPERATED VALVE 1115D PLUGGED 573 HPI-MOV-PG-1269A 1 4.000E-005 l.OOOE-007 7.200E+002 MOTOR OPERATED VALVE 1269A PLUGGED 574 HPI-MOV-PG-1270A l 4.000E-005 l.OOOE-007 7.200E+002 MOTOR OPERATED VALVE 1270A PLUGGED 575 HPI-MOV-PG-1286B 1 4.000E-005 1.000E-007 7.200E+002 MOTOR OPERATED VALVE 1286B PLUGGED 576 HPI-MOV-PG-1286C 1 4.000E-005 1.000E-007 7.200E+002 MOTOR OPERATED VALVE 1286C PLUGGED 1993/11/24 09:45:14 page 24 E-25

Event Number Primary Name BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Calculation Type Case: ALTERNATE Mean Probability Lamda Tau 577 HPI-MOV-PG-1350 1 4.000E-005 1.000E-007 7.200E+002 HPI MOTOR OPERATED VALVE 1350 PLUGGED 578 HPI-MOV-PG-1867C 1 4.000E-005 1.000E-007 7.200E+002 MOTOR OPERATED VALVE 1867C PLUGGED 579 HPI-MOV-PG-1867D 1 4.000E-005 1.000E-007 7.200E+002 MOTOR OPERATED VALVE 1867D PLUGGED 580 HPI-MOV-PG-1869A 1 4.000E-005 1. OOOE-007 7.200E+002 MOV- 1869A PLUGGED 581 HPI-MOV-PG-1869B 1 4.000E-005 1. OOOE-007 7.200E+002 MOV- 1869B PLUGGED 582 HPI-XHE-FO-COLD F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO OPERATOR FAILS TO MANUALLY INITIATE HPI FLOW TO COLD LEGS 583 HPI-XHE-FO-FBHLG F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO OP FAILS TO ESTABLISH FEED AND BLEED THRU HOT LEGS 584 HPI-XHE-FO-FDBLD F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO OP FAILS TO ESTABLISH FEED AND BLEED OPERATIC 585 HPI-XHE-FO-HOTLG F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO OPERATOR FAILS TO MANUALLY INITIATE HPI FLOW TO HOT- LEGS 586 HPI-XHE-FO-PLLCK 1 2.700E-006 +O.OOOE+OOO +O.OOOE+OOO Operator fails to remove pulllock condition 587 HPI-XVM-PG-XV24 1 4.000E-005 l.OOOE-007 7.200E+002 MANUAL VALVE XV24 PLUGGED 588 HPR-MDP-FR-1Cl2H 1 8.000E-004 +O.OOOE+OOO +O.OOOE+OO HPR MOTOR DRIVEN PUMP lC FAILS TO RUN FOR 12 HRS 589 HPR-MDP-FR-Al8HR 4 l.224E-003 6.800E-005 1. 800E+001 CHARGING PMP MDP-CHlA FAILS TO RUN FOR 18 HRS 590 HPR-MDP-FR-B18HR 4 l.224E-003 6.800E-005 l.800E+001 CHARGING PUMP MDP-CH1B FAILS TO RUN FOR 18 HRS 591 IAS-AOV-FT-TV126 1 l.OOOE-003 +O.OOOE+OOO +O.OOOE+OOO IA-TV-126 FAILS TO OPEN 592 IAS-AOV-LK-CC107 1 2.400E-005 +O.OOOE+OOO +O.OOOE+OOO INSTRUMENT AIR LEAK TO TV-CC-107 593 IAS-AOV-OC-CC107 1 7.500E-007 +O.OOOE+OOO +O.OOOE+OOO CC-TV-107 TRANSFERS CLOSED 594 IAS-AOV-PG-CC107 1 4.000E-005 l.OOOE-007 7.200E+002 cc-TV-107 PLUGGED 595 IAS-AOV-PG-TV125 1 4.000E-005 1.000E-007 +O.OOOE+OOO IA-TV-125 PLUGGED 596 IAS-CCF-LF-INAIR 1 2.700E-005 +O.OOOE+OOO +O.OOOE+OOO COMMON CAUSE FAIL AOVS DUE TO LOSS OF AIR 597 IAS-CPS-FR-IAC-1 2 4.800E-003 2.000E-004 +O.OOOE+OOO TURBINE BUILDING IA COMPRESSOR IA-C-1 FAILS TO RUN 598 IAS-CPS-FS-IAC-1 1 8.000E-002 +O.OOOE+OOO +O.OOOE+OOO TURBINE BUILDING IA COMPRESSOR IA-C-1 FAILS TO START 599 IAS-DYR-LF-IAD1 2 7.200E-004 3.000E-005 +O.OOOE+OOO TURBINE BUILDING IA DRYER PLUGGED 600 ISO-W1 1 1.000E+OOO +O.OOOE+OOO +O.OOOE+OOO RCS Loops Isolated to Cause Failure of Reflux Cooling 1993/11/24 09:45:14 page 25 E-26

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 601 ISO-W2 1 l.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO RCS Loops Isolated to Cause Failure of Reflux Cooling 602 ISO-W3 1 l.OOOE+OOO +0.000E+OOO +O.OOOE+OOO RCS Loops Isolated to Cause Failure of Reflux Cooling 603 ISO-W4 1 l.OOOE+OOO +O.OOOE+OOO +0.000E+OOO RCS Loops Isolated to Cause Failure of Reflux Cooling 604 ISR-CCF-FS-RSlAB 1 4.200E-003 +O.OOOE+OOO +O.OOOE+OOO COMMON CAUSE FAIL TO START ISR PMPS 605 ISR-MDP-FR-RSlA 4 7.200E-004 3.000E-005 2.400E+001 ISR MOTOR DR PUMP RSlA FAILS TO RUN 606 ISR-MDP-FR-RS1B 4 7.200E-004 3.000E-005 2.400E+001 ISR MOTOR DR PUMP RSlB FAILS TO RUN 607 ISR-MDP-FS-RSlA 1 3.800E-002 +O.OOOE+OOO +O.OOOE+OOO ISR MDP RSlA FAILS TO START ON DEMAND 608 ISR-MDP-FS-RS1B 1 3.800E-002 +O.OOOE+OOO +O.OOOE+OOO ISR MDP RSlB FAILS TO START ON DEMAND 609 ISR-MDP-MA-RSlA 1 2.000E-003 +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON MDP RSlA 610 ISR-MDP-MA-RS1B 1 2.000E-003 +0.000E+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON MDP RSlB 611 ISR-MDP-OP-lAB F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO ISR NOT INIT BY OPER 612 ISR-STR-PG-RSlAS 4 7.200E-004 3.000E-005 2.400E+001 ISR STRAINER RSlAS PLUGGED 613 ISR-STR-PG-RSlBS 4 7.200E-004 3.000E-005 2.400E+001 ISR STRAINER RSlBS PLUGGED 614 ISR-TRA-MA 1 2.500E-001 +O.OOOE+OOO +O.OOOE+OOO TRAIN A MAINT UNAV.

615 K 1 6.000E-005 +O.OOOE+OOO +O.OOOE+OOO FAILURE OF RPS TO SCRAM THE RX 616 LOOP-ISOLATED-GT 1 7.000E-001 +O.OOOE+OOO +O.OOOE+OOO Loops Isolated in POS 6 Refuleing 617 LOOPl 1 1.000E+OOO +O.OOOE+OOO +O.OOOE+OOO LOOP TEST 618 LOOPISOLATED1D6 T l.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO Loops Isolated in window 1 of D6 619 LOOPISOLATED1R10 T 1.000E+OOO +O.OOOE+OOO +O.OOOE+OOO Loops Isolated in of window 1 of RlO 620 LOOPISOLATED1R6 1 3.000E-001 +O.OOOE+OOO +O.OOOE+OOO Loops Isolated in window 1 of R6 621 LOOPISOLATED2D6 F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO Loops Isolated in window 2 of D6 622 LOOPISOLATED2R10 T l.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO Loops Isolated in of window 2 of RlO 623 LOOPISOLATED2R6 1 7.000E-001 +O.OOOE+OOO +O.OOOE+OOO Loops Isolated in window 2 of R6 624 LOOPISOLATED3D6 F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO Loops Isolated in window 3 of D6 1993/11/24 09:45:14 page 26 E-27

Event Number Primary Name BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Calculation Type Case: ALTERNATE Mean Probability Lamda Tau 625 LOOPISOLATED3Rl0 T l.OOOE+OOO +0.000E+OOO +O.OOOE+OOO Loops Isolated in of window 3 of RlO 626 L00PISOLATED3R6 T l.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO Loops Isolated in window 3 of R6 627 L00PISOLATED4D6 F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO Loops Isolated in window 4 of D6 628 L00PISOLATED4R10 T l.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO Loops Isolated in of window 4 of RlO 629 LOOPISOLATED4R6 T l.OOOE+OOO +O.OOOE+OOO +0.000E+OOO Loops Isolated in window 4 of R6 630 LOSP 2 1. 670E-004 6.960E-006 +0.000E+OOO LOSP EVENT 631 LPI-CCF-FS-SilAB 1 4.SOOE-004 +O.OOOE+OOO +O.OOOE+OOO COMMON CAUSE FAILURE OF MDPS SilA AND SilB 632 LPI-CKV-FT-243 1 1.000E-004 +O.OOOE+OOO +O.OOOE+OOO Check valve CV243 fails to open 633 LPI-CKV-FT-CV239 1 1. OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV239 FAILS TO OPEN 634 LPI-CKV-FT-CV240 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV240 FAILS TO OPEN 635 LPI-CKV-FT-CV241 1 1. OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV241 FAILS TO OPEN 636 LPI-CKV-FT-CV242 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO Check valve CV242 fails to open 637 LPI-CKV-FT-CV46A 1 1.000E-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV46A FAILS TO OPEN 638 LPI-CKV-FT-CV46B 1 l.OOOE-004 +0.000E+OOO +O.OOOE+OOO CHECK VALVE CV46B FAILS TO OPEN 639 LPI-CKV-FT-CVSO 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CVSO FAILS TO OPEN 640 LPI-CKV-FT-CVS8 1 1.000E-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV58 FAILS TO OPEN 641 LPI-CKV-FT-CV79 1 1.000E-004 +0.000E+OOO +O.OOOE+OOO CHECK VALVE CV79 FAILS TO OPEN 642 LPI-CKV-FT-CV82 1 1.000E-004 +O.OOOE+OOO +O.OOOE+OOO Check valve CV82 fails to open 643 LPI-CKV-FT-CV85 1 1.000E-004 +O.OOOE+OOO +O.OOOE+OOO MOV1890C FROM LOW Check valve CV85 fails to open 644 LPI-CKV-FT-CV91 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV91 FAILS TO OPEN 645 LPI-CKV-FT-CV94 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV94 FAILS TO OPEN 646 LPI-CKV-00-CVSO 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CVSO FAILS TO SHUT CAUSE BACKFLOW 647 LPI-CKV-00-CV58 1 l.OOOE-003 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV58 FAILS TO SHUT CAUSE BACKFLOW 648 LPI-MDP-FR-lAlHR 4 3.000E-005 3.000E-005 l.OOOE+OOO LPI MDP SilA FAILS TO RUN FOR 1 HOUR 1993/11/24 09:45:14 page 27 E-28

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 649 LPI-MDP-FR-1A6HR 4 l.800E-004 3.000E-005 6.000E+OOO LPI MDP SilA FAILS TO RUN FOR 6 HOURS 650 LPI-MDP-FR-lBlHR 4 3.000E-005 3.000E-005 l.OOOE+OOO LPI MDP SilB FAILS TO RUN FOR 1 HOUR 651 LPI-MDP-FR-1B6HR 4 l.800E-004 3.000E-005 6.000E+OOO LPI MDP SilB FAILS TO RUN FOR 6 HOURS 652 LPI-MDP-FR-Al8HR 4 5.400E-004 3.000E-005 l.800E+001 LPI MDP SilA FAILS TO RUN FOR 18 HOURS 653 LPI-MDP-FR-A24HR 4 7. 200E-004 . 3.000E-005 2.400E+001 LPI MOP SilA FAILS TO RUN FOR 24 HOURS 654 LPI-MDP-FR-Bl8HR 4 5.400E-004 3.000E-005 l.800E+001 LPI MDP SilB FAILS TO RUN FOR 18 HOURS 655 LPI-MDP-FR-B24HR 4 7.200E-004 3.000E-005 2.400E+001 LPI MDP SilB FAILS TO RUN FOR 24 HOURS 656 LPI-MDP-FS-SilA 1 3.000E-003 +O.OOOE+OOO +0.000E+OOO LPI MDP SilA FAILS TO START ON DEMAND 657 LPI-MDP-FS-SilB 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO LPI MDP SilB FAILS TO START ON DEMAND 658 LPI-MDP-MA-SilA T l.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON LPI MDPSilA - STATE 6 659 LPI-MDP-MA-SilB F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON LPI MDPSilB - STATE 6 660 LPI-MDP-MAOSilA T l.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON LPI MDPSilA - STATE 10 661 LPI-MDP-MAOSilB F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON LPI MDPSilB - STATE 10 662 LPI-MOV-CC-1890C 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO LPI MOV- 1890C fails to open 663 LPI-MOV-MA-1862A 1 +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON LPI 1862A - STATE 6 664 LPI-MOV-MA01862A 1 +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON LPI 1862A - STATE 10 665 LPI-MOV-00-1890C 1 5.200E-003 +O. OOOE+OOO * +O.OOOE+OOO MOV- 1890C FAILS TO CLOSE 666 LPI-MOV-PG-1862A 1 4.000E-005 l.OOOE-007 7.200E+002 LPI MOTOR OFER VALVE 1862A PLUGGED 667 LPI-MOV-PG-1862B 1 4.000E-005 l.OOOE-007 7.200E+002 LPI MOTOR OFER VALVE 1862B PLUGGED 668 LPI-MOV-PG-1864A 1 4.400E-004 1.000E-'-007 8.760E+003 LPI MOTOR OPERATED VALVE 1864A PLUGGED 669 LPI-MOV-PG-1864B 1 4.400E-004 l.OOOE-007 8.760E+003 LPI MOTOR OPERATED VALVE 1864B PLUGGED 670 LPI-MOV-PG-1890C 1 4.400E-004 l.OOOE-007 8.760E+003 VALVE 1890C PLUGGED LPI motor operated 671 LPI-XHE-FO-COLD F +O.OOOE+OOO +0.000E+OOO +O.OOOE+OOO Operato'r fails to manually initiate LPI 672 LPI-XHE-FO-HOTLG F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO OPERATOR FAILS TO MANUALLY INITIATE LPI FLOW TO HOT- LEGS 1993/11/24 09:45:14 page 28 E-29

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 673 LPI-XVM-PG-XV48 1 3.650E-005 1. OOOE-007 7.200E+002 MANUAL VALVE XV48 PLUGGED 674 LPI-XVM-PG-XV57 1 3.650E-005 1. OOOE-007 7.200E+002 MANUAL VALVE XV57 PLUGGED 675 LPR-CCF-FT-860AB 1 2.600E-004 +O.OOOE+OOO +O.OOOE+OOO COMMON CAUSE FAILURE OF MOV 1860A/B 676 LPR-CCF-FT-862AB 1 2.600E-004 +O.OOOE+OOO +0.000E+OOO COMMON CAUSE FAILURE OF MOV 1862A/B 677 LPR-CCF-FT-863AB 1 2.600E-004 +O.OOOE+OOO +O.OOOE+OOO COMMON CAUSE FAILURE OF MOV 1863A/B 678 LPR-CCF-FT-890AB 1 2.600E-004 +O.OOOE+OOO +O.OOOE+OOO COMMON CAUSE FAILURE OF MOV 1890A/B 679 LPR-CCF-PG-SUMPl 1 1. OOOE-002 +O.OOOE+OOO +O.OOOE+OOO PLUGGING OF THE CONTAINMENT SUMP in Time Window 1 680 LPR-CCF-PG-SUMP2 1 1. OOOE-001 +O.OOOE+OOO +O.OOOE+QOO PLUGGING OF THE CONTAINMENT SUMP in Time Window 2 681 LPR-CKV-FT-CV228 1 1. OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV228 FAILS TO OPEN 682 LPR-CKV-FT-CV229 1 1. OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV229 FAILS TO OPEN 683 LPR-CKV-FT-CV47 1 1. OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CV47 FAILS TO OPEN 684 LPR-CKV-FT-CV56 1 1. OOOE-004 +O.OOOE+OOO +0.000E+OO CHECK VALVE CV56 FAILS TO OPEN 685 LPR-MOV-FT-1860A 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO LPR MOTOR OPERATED VALVE 1860A FAILS TO OPEN 686 LPR-MOV-FT-1860B 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO LPR MOTOR OPERATED VALVE 1860B FAILS TO OPEN 687 LPR-MOV-FT-1862A 1 5.200E-003 +O.OOOE+OOO +O.OOOE+OOO LPR MOTOR OPERATED VALVE 1862A FAILS TO CLOSE 688 LPR-MOV-FT-1862B 1 5.200E-003 +O.OOOE+OOO +0.000E+OOO LPR MOTOR OPERATED VALVE 1862B FAILS TO CLOSE 689 LPR-MOV-FT-1863A 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO LPR MOTR OP VLV 1863A FAILS TO OPEN 690 LPR-MOV-FT-1863B 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO LPR MTR OP VLV 1863B FAILS TO OPEN 691 LPR-MOV-FT-1890A 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO LPR MOTOR OPERATED VALVE 1890A FAILS TO OPEN 692 LPR-MOV-FT-1890B 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO LPR MOTOR OPERATED VALVE 1890B FAILS TO OPEN 693 LPR-MOV-PG-1863A 1 6.600E-004 1.000E-007 1.300E+004 LPR MOTOR OPER VALVE 1863A PLUGGED 694 LPR-MOV-PG-1863B 1 6.600E-004 1.000E-007 l.300E+004 LPR MOTOR OPER VALVE 1863B PLUGGED 695 LPR-MOV-PG-1890A 1 6.600E-004 l.OOOE-007 l.300E+004 LPR MOTOR OFER VALVE 1890A PLUGGED 696 LPR-MOV-PG-1890B 1 6.600E-004 l.OOOE-007 l.300E+004 LPR MOTOR OPERATED VALVE 1890B PLUGGED 1993/11/24 09:45:14 page 29 E-30

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 697 LPR-XHE-FO-HOTLG F +O.OOOE+OOO +0.000E+OOO +O.OOOE+OOO OP FAILS TO ALIGN THE SYSTEM FOR HOT LEG RECI 698 M 1 2.900E-003 +0.000E+OOO +O.OOOE+OOO FAILURE TO RESTORE MAIN FEEDWATER 699 MCW-CCF-VF-INLVL 1 1.000E-009 +O.OOOE+OOO +O.OOOE+OOO INSUFFICIENT INTAKE CANAL LEVEL 700 MCW-CCF-VF-SBO 1 5.860E-002 +O.OOOE+OOO +O.OOOE+OOO OPERS DONT CLOSE VALVES 701 MSS-AOV-FC-101A 1 1.500E-001 +O.OOOE+OOO +O.OOOE+OOO SG A PORV BLOCKED 702 MSS-AOV-FC-101B 1 1.500E-001 +O.OOOE+OOO +O.OOOE+OOO SG B PORV BLOCKED 703 MSS-AOV-FC-101C 1 1. 500E-001 +0.000E+OOO +O.OOOE+OOO SG C PORV BLOCKED 704 MSS-AOV-FT-101A 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO SG A PORV FAILS TO OPEN 705 MSS-AOV-FT-101B 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO SG B PORV FAILS TO OPEN 706 MSS-AOV-FT-101C 1 1. OOOE-003 +O.OOOE+OOO +O.OOOE+OOO SG C PORV FAILS TO OPEN 707 MSS-AOV-MA-101A 1 5.000E-002 +O.OOOE+OOO +O.OOOE+OOO SG A PORV IN TEST OR MAINTENANCE 708 MSS-AOV-MA-101B 1 S.OOOE-002 +O.OOOE+OOO +O.OOOE+OOO SG B PORV IN TEST OR MAINTENANCE 709 MSS-AOV-MA-101C 1 5.000E-002 +O.OOOE+OOO +O .*OOOE+OOO SG C PORV IN TEST OR MAINTENANCE 710 MSS-AOV-PG-101A 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO SG A PORV PLUGGED 711 MSS-AOV-PG-101B 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO SG B PORV PLUGGED 712 MSS-AOV-PG-101C 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO SG C PORV PLUGGED 713 MSS-AOV-XHE-105 1 1.300E-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Open Main Steam Dump Valves to Condenser 714 MSS-CCF-FT-01ABC 1 7.000E-005 +O.OOOE+OOO +O.OOOE+OOO CC FAILURE OF SG C PORV 715 MSS-CCF-FT-NRV 1 7.000E-005 +O.OOOE+OOO +O.OOOE+OOO CCF OF NRV VALVES 716 MSS-CCF-FT-STV 1 7.000E-005 +O.OOOE+OOO +O.OOOE+OOO 1 CCF OF MST VALVES 717 MSS-CCF-PG-XVM 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO CCF OF MST BPVS 718 MSS-HCV-FT-104 1 1. OOOE-003 +O.OOOE+OOO +O.OOOE+OOO HC-104 FAILS ~O OPEN 719 MSS-HCV-PG-104 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO HCV-104 PLUGGED 720 MSS-NRV-FT-101A 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO NRV FAILS TO OPEN 1993/11/24 09:45:14 page 30 E-31

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 721 MSS-NRV-FT-101B 1

3.000E-003 +O.OOOE+OOO +O.OOOE+OOO NRV FAILS TO OPEN 722 MSS-NRV-FT-lOlC 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO NRV FAILS TO OPEN 723 MSS-NRV-MA-lOlA 1 5.000E-002 +O.OOOE+OOO +0.000E+OOO NRV IN TEST OR MAINTENANCE 724 MSS-NRV-MA-101B 1 5.000E-002 +O.OOOE+OOO +O.OOOE+OOO NRV IN TEST OR MAINTENANCE 725 MSS-NRV-MA-lOlC 1 5.000E-002 +0.000E+OOO +O.OOOE+OOO NRV IN TEST OR MAINTENANCE 726 MSS-NRV-PG-lOlA 1 6.000E-004 +O.OOOE+OOO +O.OOOE+OOO NRV PLUGGED 727 MSS-NRV-PG-101B 1 6.000E-004 +O.OOOE+OOO +O.OOOE+OOO NRV PLUGGED 728 MSS-NRV-PG-lOlC 1 6.000E-004 +O.OOOE+OOO +0.000E+OOO NRV PLUGGED 729 MSS-STV-FT-101A 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO MSTV FAILS TO OPEN 730 MSS-STV-FT-101B 1 1. OOOE-004 +O.OOOE+OOO +O.OOOE+OOO MSTV FAILS TO OPEN 731 MSS-STV-FT-101C 1 1.000E-004 +0.000E+OOO +O.OOOE+OOO MSTV FAILS TO OPEN 732 MSS-STV-MA-lOlA 1 5.000E-002 +O.OOOE+OOO +O.OOOE+OOO MSTV 101A IN TEST OR MAINTENANCE 733 MSS-STV-MA-101B 1 5.000E-002 +O.OOOE+OOO +O.OOOE+OOO MSTV 101B IN TEST OR MAINTENANCE 734 MSS-STV-MA-lOlC 1 5.000E-002 +O.OOOE+OOO +O.OOOE+OOO MSTV 101C IN TEST OR MAINTENANCE 735 MSS-STV-PG-lOlA 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO MSTV PLUGGED 736 MSS-STV-PG-lOlB 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO MSTV PLUGGED 737 MSS-STV-PG-101C 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO MSTV PLUGGED 738 MSS-XVM-MA-084 1 +0.000E+OOO +O.OOOE+OOO +O.OOOE+OOO MST-A BPV 084 TEST OR MAINTENANCE 739 MSS-XVM-MA-116 1 +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO MST-B BPV 116 TEST OR MAINTENANCE 740 MSS-XVM-MA-153 1 +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO MST-C BPV 153 TEST OR MAINTENANCE 741 MSS-XVM-PG-084 1 4.400E-004 +O.OOOE+OOO +O.OOOE+OOO MST-A BPV 084 PLUGGED 742 MSS-XVM-PG-116 1 4.400E-004 +O.OOOE+OOO +.O. OOOE+OOO MST-B BPV 116 PLUGGED 743 MSS-XVM-PG-153 1 4.400E-004 +O.OOOE+OOO +O.OOOE+OOO MST-C BPV 153 PLUGGED 744 MSS-XVM-XHE-BYPS 1 1.700E-003 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Open MSTV Bypass Valves 1993/11/24 09:45:14 page 31 E-32

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 745 NB2Wl 1 l.OOOE+OOO +0.000E+OOO +O.OOOE+OOO 746 NB2W2 1 l.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO 747 NB2W3 1 l.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO 748 NB2W4 1 l.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO 749 NRAC-lHR 1 4.400E-001 +O.OOOE+OOO +O.OOOE+OOO NON-RECOVERY AC PWR W/IN 1 HR OF LOSP 750 NRAC-7HR 1 5.000E-002 +O.OOOE+OOO +O.OOOE+OOO NON-RECOVERY AC PWR W/IN 7 HRS OF LOSP 751 NRAC-HALFHR 1 6.000E-001 +O.OOOE+OOO +O.OOOE+OOO NON-RECOVERY AC PWR W/IN 30 MIN OF LOSP 752 OEP-BAC-ST-FDRD 1 9.000E-005 +O.OOOE+OOO +O.OOOE+OOO RESERVE STATION SERVICE FEEDER D BUSWORK FAILS 753 OEP-BAC-ST-FDRF 1 9.000E-005 +O.OOOE+OOO +O.OOOE+OOO RESERVE STATION SERVICE FEEDER F BUSWORK FAILS 754 OEP-CCF-FS-DG12 1 8.400E-004 +O.OOOE+OOO +O.OOOE+OOO CC FAIL TO START 1 & 2 DGS 755 OEP-CCF-FS-DG123 1 4.000E-004 +O.OOOE+OOO +O.OOOE+OOO CC FAIL TO START ALL 3 DGS 756 OEP-CCF-FS-DG13 1 8.400E-004 +O.OOOE+OOO +O.OOOE+OOO CC FAIL TO START 1 & 3 DGS 757 OEP-CCF-FS-DG23 1 8.400E-004 +O.OOOE+OOO +O.OOOE+OOO CC FAIL TO START 2 & 3 DGS 758 OEP-CRB-FT-15H3 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO DIESEL GEN #1 CKT BRKR 15H3 FAILS TO CLOSE 759 OEP-CRB-FT-1SJ3 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO DIESEL GEN #3 CKT BRKR 15J3 FAILS TO CLOSE 760 OEP-DGN-FC-DG3U2 1 3.400E-002 +O.OOOE+OOO +O.OOOE+OOO DIESEL GEN #3 UNAVAIL ALIGNED TO UNIT 2 761 OEP-DGN-FR-DG01 4 2.000E-003 2.000E-003 l.OOOE+OOO DG 1 FAILS TO RUN 1 HR 762 OEP-DGN-FR-DG03 4 2.000E-003 2.000E-003 1.000E+OOO DG 3 FAILS TO RUN 1 HR 763 OEP-DGN-FS-DG01 1 2.200E-002 +O.OOOE+OOO +0.000E+OOO DIESEL GENERATOR #1 FAILS TO START 764 OEP-DGN-FS-DG03 1 2.200E-002 +O.OOOE+OOO +O.OOOE+OOO DIESEL GENERATOR #3 FAILS TO START 765 OEP-DGN-MA-DG01 F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON DIESEL GENERATOR 1 - STATE 6 766 OEP-DGN-MA-DG03 F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON DIESEL GENERATOR 3 767 OEP-DGN-MAODGOl F +O.OOOE+OOO +0.000E+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON DIESEL GENERATOR 1 - STATE 10 768 OEP-DGN-MAODG03 F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON DIESEL GENERATOR 3 - STATE 10 1993/11/24 09:45:14 page 32 E-33

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 769 OSR-CCF-FS-RS2AB 1

3.300E-004 +O.OOOE+OOO +O.OOOE+OOO COMMON CAUSE FAIL TO START OSR MDPS 770 OSR-CKV-FT-CVll 1 1.000E-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CVll FAILS TO OPEN 771 OSR-CKV-FT-CV17 1 1.000E-004 +O.OOOE+OOO +0.000E+OOO CHECK VALVE CV17 FAILS TO OPEN 772 OSR-MDP-FR-A24HR 4 7.200E-004 3.000E-005 2.400E+001 OSR MDP RS2A FAILS TO RUN 24 HOURS 773 OSR-MDP-FR-B24HR 4 7.200E-004 3.000E-005 2.400E+001 OSR MDP RS2B FAILS TO RUN 24 HOURS 774 OSR-MDP-FS-RS2A 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO OSR MDP RS2A FAILS TO START ON DEMAND 775 OSR-MDP-FS-RS2B 1 3.000E-003 +O.OOOE+OOO +0.000E+OOO OSR MDP RS2B FAILS TO START ON DEMAND 776 OSR-MDP-MA-RS2A 1 2.000E-003 +O.OOOE+OOO +0.000E+OOO TEST AND MAINTENANCE ON OSR MDPRS2A 777 OSR-MDP-MA-RS2B 1 2.000E-003 +0.000E+OOO +0.000E+OOO TEST AND MAINTENANCE ON OSR MDPRS2B 778 OSR-MDP-OP-2AB F +O.OOOE+OOO +0.000E+OOO +O.OOOE+OOO NO OPER !NIT OSR 779 OSR-MOV-PG-155A 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO OSR MOTOR OPER VALVE 155A PLUGGED 780 OSR-MOV-PG-155B 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OO OSR MOTOR OPER VALVE 155B PLUGGED 781 OSR-MOV-PG-156A 1 4.000E-005 +O. OOOE+ooo* +O.OOOE+OOO OSR MOTOR OPER VALVE 156A PLUGGED 782 OSR-MOV-PG-156B 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO OSR MOTOR OPER VALVE 156B PLUGGED 783 OSR-STR-PG-RS2A 4 7.200E-004 3.000E-005 2.400E+001 OSR MDP RS2A SUMP STRAINER PLUGGED 784 OSR-STR-PG-RS2B 4 7.200E-004 3.000E-005 2.400E+001 OSR MDP RS2B SUMP STRAINER PLUGGED 785 OSR-TRA-MA 1 2.500E-001 +O.OOOE+OOO +O.OOOE+OOO TRAIN A MAINT UNAV.

786 PCS-AOV-FT-BYP-A 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO A BYP TO TURB BYPASS FAILS TO OPEN 787 PCS-AOV-FT-BYP-B 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO B BYP TO TURB BYPASS FAILS .TO OPEN 788 PCS-AOV-FT-BYPA 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO A BYPASS VALVE FAIL TO OPEN TCV 107/8 A 789 PCS-AOV-FT-BYPB 1 1.000E-003 +O.QOOE+OOO +O.OOOE+OOO B BYPASS VALVE FAIL TO OPEN TCV 107/8B 790 PCS-AOV-FT-MSTVA 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO A BYPASS VALVE TCV 105/6 A FAILS TO OPEN 791 PCS-AOV-FT-MSTVB 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO B BYPASS VALVE TCV 105/6 B FAILS TO OPEN 792 PCS-AOV-PG-BYP-A 1 4.000E-005 1.000E-007 7.200E+002 A BYP TO TURB BYPASS PLUGGED 1993/11/24 09:45:14 page 33 E-34

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 793 PCS-AOV-PG-BYP-B 1 4.000E-005 1.000E-007 7.200E+002 B BYP TO TURB BYPASS PLUGGED 794 PCS-AOV-PG-BYPA 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO A BYPASS TCV 107/8 A PLUGGED 795 PCS-AOV-PG-BYPB 1 4.000E-005 +O.OOOE+OOO +O. OOOE+o*oo B BYPASS TCV 107/8B PLUGGED 796 PCS-AOV-PG-MSTVA 1 4.000E-005 1.000E-007 7.200E+002 A BYPASS VALVE TCV 105/6 A PLUGGED 797 PCS-AOV-PG-MSTVB 1 4.000E-005 1.000E-007 7.200E+002 B BYPASS VALVE TCV 105/6 B PLUGGED 798 PCS-CCF-FT-TRBYP 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO cc failure of bypass valves 799 PORV-PATH-CLSD 1 5.000E-002 +0.000E+OOO +O.OOOE+OOO porv pathway closed 800 POS-D6 F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO POS 6 of a Drained Maintenance Outage 801 POS-RlO F +O.OOOE+OOO +O.OOOE+OOO +o*. OOOE+OOO POS 10 of a Refueling Outage 802 POS-R6 T l.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO POS 6 of a Refueling Outage 803 PPS-AOV-OC-1455C 1 7.500E-007 +O.OOOE+OOO +O.OOOE+OOO PORV TRANSFERS CLOSED 804 PPS-CCF-FT-15356 1 3.500E-003 +O.OOOE+OOO +O.OOOE+OOO COMMON CAUSE FAILURE OF PORV BLOCKING VALVES 805 PPS-CCF-FT-PORV 1 7.000E-005 +O.OOOE+OOO +O.OOOE+OOO COMMON CAUSE FAILURE OF THE PORVS TO OPEN COMMON CAUSE 806 PPS-CCF-FT-SRVS 1 7.000E-005 +O.OOOE+OOO +O.OOOE+OOO COMMON CAUSE FAILURE OF RCS SRVS TO OPEN 807 PPS-MOV-FC-1535 1 3.000E-001 +O.OOOE+OOO +O.OOOE+OOO BLOCK VALVE MOV 1535 SHUT DUE TO LEAKING PORV 808 PPS-MOV-FC-1536 1 3.000E-001 +O.OOOE+OOO +.O. OOOE+OOO BLOCK VALVE MOV 1536 SHUT DUE TO LEAKING PORV 809 PPS-MOV~FT-1535 1 4.000E-002 +O.OOOE+OOO +O.OOOE+OOO PORV BLOCK VALVE 1535 FAILS TO OPEN 810 PPS-MOV-FT-1536 1 4.000E-002 +O.OOOE+OOO +O.OOOE+OOO PORV BLOCK VALVE 1536 FAILS TO OPEN 811 PPS-MOV-00-1535 1 4.000E-002 +O.OOOE+OOO +O.OOOE+OOO PORV BLOCK VALVE 1535 FAILS TO CLOSE 812 PPS-MOV-00-1536 1 4.000E-002 +O.OOOE+OOO +O.OOOE+OOO PORV BLOCK VALVE 1536 FAILS TO CLOSE 813 PPS-MOV-PG-1535 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO PORV BLOCK VALVE 1535 PLUGGED 814 PPS-MOV-PG-1536 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO PORV BLOCK VALVE 1536 PLUGGED 815 PPS-OP-SET-SD 1 2.700E-003 +O.OOOE+OOO +O.OOOE+OOO OPERS DON'T SET PORVS 816 PPS-PCV-MA-145SC 1 +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON PORV 145SC - STATE 6 1993/11/24 09:45:14 page 34 E-35

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 81.7 PPS-PCV-MA-1.456 1. +O.OOOE+OOO +O.OOOE+OOO +0.000E+OOO TEST AND MAINTENANCE ON PORV 1.456 - STATE 6 81.8 PPS-PCV-MA01455C 1 +O.OOOE+OOO +0.000E+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON PORV 1.455C - STATE 1.0 81.9 PPS-PCV-MAOl.456 1. 4.41.0E-002 +O.OOOE+OOO +0.000E+OOO TEST AND MAINTENANCE ON PORV 1456 - STATE 1.0 820 PPS-SOV-FT-1455C 1. 1..000E-003 +O.OOOE+OOO +0.000E+OOO PORV PCV1455C FAILS TO OPEN ON DEMAND 821. PPS-SOV-FT-1456 1. 1.000E-003 +0.000E+OOO +O.OOOE+OOO PORV [CVl.456 FAILS TO OPEN ON DEMAND 822 PPS-SOV-00-1455C 1. 3.000E-002 +O.OOOE+OOO +O.OOOE+OOO PORV PCV1.4SSC FAILS TO RECLOSE 823 PPS-SOV-00-1456 1. 3.000E-002 +O.OOOE+OOO +0.000E+OOO PORV PCVl.456 FAILS TO RECLOSE 824 PPS-SRV-FT-1551.A 1. l.OOOE-003 +O.OOOE+OOO +O.OOOE+OOO SAFETY RELIEF VALVE 1551.A FAILS TO OPEN SAFETY RELIEF OPEN 825 PPS-SRV-FT-1551.B 1. l.OOOE-003 +O.OOOE+OOO +O.OOOE+OOO SAFETY RELIEF VALVE 1551.B FAILS TO OPEN SAFETY RELIEF OPEN 826 PPS-SRV-FT-1551.C l l.OOOE-003 +O.OOOE+OOO +0.000E+OOO SAFETY RELIEF VALVE 1551.C FAILS TO OPEN SAFETY RELIEF OPEN 827 PPS-XHE-F0-1PORV F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO FAILURE OF THE OP TO OPEN ONE PORV 828 PPS-XHE-FO-EMBOR F +O.OOOE+OOO +0.000E+OOO +0.000E+OO OPER FAILS TO CORRECTLY PERFORM EMERG BORATION 829 PPS-XHE-FO-PORVS F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO FAILURE OF THE OPERATOR TO OPEN BOTH PORVS 830 PPS-XHE-FO-UNBLK F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO OPERATOR FAILS TO UNBLOCK RCS PORV IN ATWS 831 PR0B-W1D6 1. l.170E-001 +O.OOOE+OOO +O.OOOE+OOO Probability that IE occurs in wl given D6 832 PR0B-W1Rl0 F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO Probability that IE occurs in wl given RlO 833 PR0B-W1R6 l l.700E-002 +O.OOOE+OOO +0.000E+OOO Probability that IE occurs in wl given R6 834 PR0B-W2D6 l 4.360E-001 +O.OOOE+OOO +O.OOOE+OOO Probability that IE occurs in wl given D6 835 PR0B-W2R10 F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO Probability that IE occurs in wl given RlO 836 PR0B-W2R6 l S.430E-001 +O.OOOE+OOO +O. OOOE+o*oo Probability that IE occurs in wl given R6 837 PR0B-W3D6 l 3.7SOE-001 +O.OOOE+OOO +O.OOOE+OOO Probability that IE occurs in w3 given D6 838 PR0B-W3R10 l 1.600E-002 +O.OOOE+OOO +O.OOOE+OOO Probability that IE occurs in w3 given RlO 839 PR0B-W3R6 1 4.1.00E-001 +O.OOOE+OOO +O.OOOE+OOO Probability that IE occurs in w3 given R6 840 PR0B-W4D6 1 7.200E-002 +0.000E+OOO +O.OOOE+OOO Probability that IE occurs in W4 given D6 1.993/1.1./24 09:45:14 page 35 E-36

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 841 PROB-W4Rl0 1 9.840E-001 +O.OOOE+OOO +O.OOOE+OOO Probability that IE occurs in W4 given RlO 842 PROB-W4R6 1 3.400E-002 +O.OOOE+OOO +O.OOOE+OOO Probability that IE occurs in W4 given R6 843 PZR-SV-REMOVED 1 l.OOOE-001 +O.OOOE+OOO +O.OOOE+OOO PRESSURIZER SRV REMOVED 844 PZR-SV-REMOVEDW 1 l.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO Event added by partition editor 845 PZR-SV-REMOVEDWl 1 l.OOOE-002 +O.OOOE+OOO +O.OOOE+OOO Pressurizer Safety Valves Removed in WlR 846 PZR-SV-REMOVEDW2 1 5.000E-002 +0.000E+OOO +O.OOOE+OOO Pressurizer Safety Valves Removed in W2R 847 PZR-SV-REMOVEDW3 1 9.000E-001 +O.OOOE+OOO +O.OOOE+OOO Pressurizer Safety Valves Removed in W3R 848 PZR-SV-REMOVEDW4 1 3.000E-001 +O.OOOE+OOO +O.OOOE+OOO Pressurizer Safety Valves Removed in W4R6 849 QS-SBO 1 2.700E-001 +O.OOOE+OOO +O.OOOE+OOO SG SRV/PORV STICK OPEN DURING SBO 850 QS-UNIT2 1 1.600E-001 +O.OOOE+OOO +O.OOOE+OOO UNIT 2 SG RELIEF STUCK OPEN DURING SBO 851 R-B2Wl-XHE-A 1 l.OOOE-001 +O.OOOE+OOO +O.OOOE+OOO RECOVERY DUE TO UNCERTAIN SUCCESS CRITERION OF REFLUX 852 R-B2Wl-XHE-S/R6 1 3.lOOE-001 ------E---- ------E----

recovery using reflux 853 R-B2W2-XHE-S 1 8.950E-003 +O.OOOE+OOO +O.OOOE+OOO RECOVER AFW TO ESTABLISH LONG TERM REFLUX/W2 854 R-B2W2-XHE-S/R6 1 7.030E-001 +O.OOOE+OOO +O.OOOE+OOO RECOVER AFW FOR REFLUX W2, IN R6 ISOLATION .7 855 R-B2W3-XHE-G 1 1.270E-003 ------E---- ------E----

recovery of gravity feed or other action 856 R-B2W3-XHE-S 1 8.950E-003 +O.OOOE+OOO +O.OOOE+OOO RECOVER AFW TO ESTABLISH LONG TERM REFLUX COOLING/W3 857 R-B2W4-XHE-G 1 1.270E-003 ------E---- ------E----

recovery of gravity feed or other action 858 R-B2W4-XHE-S 1 5.390E-004 +O.OOOE+OOO +O.OOOE+OOO RECOVER AFW TO ESTABLISH LONG TERM REFLUX COOLING/W4 859 R-R3R6-XHE-G-4 1 2.400E-001 +O.OOOE+OOO +O.OOOE+OOO Failure to Recover Given Successful Gravity Feed-RAR6 860 R-R3Wl-XHE-A 1 1.000E-001 ------E---- ------E----

RECOVERY DUE TO UNCERTAINTY IN REFLUX CRITERION 861 R-R3Wl-XHE-F 1 4.200E-001 +O.OOOE+OOO +O.OOOE+OOO RECOVER FEED AND BLEED, XCONNECTING TO UNIT 2 CHARGING/Wl 862 R-R3W2-XHE-F 1 l.420E-001 +O.OOOE+OOO +O.OOOE+OOO RECOVER FEED AND BLEED, XCONNECTING TO UNIT 2 CHARGING/W2 863 R-R3W3-XHE-F 1 l.420E-001 +O.OOOE+OOO +O.OOOE+OOO RECOVER FEED AND BLEED, XCONNECTING TO UNIT 2 CHARGING/W3 864 R-R3W4-XHE-F 1 6.360E-002 +0.000E+OOO +O.OOOE+OOO RECOVER FEED AND BLEED, XCONNECTING TO UNIT 2 CHARGING/W4 1993/11/24 09:45:14 page 36 E-37

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 865 R-R4R6-XHE-G-5 1 6.300E-001 +O.OOOE+OOO +O.OOOE+OOO Failure to Recover Given Successful Gravity Feed-RAR6 866 RCS-AOV-FT-1455A 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO FAILURE OF NORMAL SPRAY VLV 1455A TO OPEN 867 RCS-AOV-FT-1455B 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO FAILURE OF NORMAL SPRAY VLV 1455B TO OPEN 868 RCS-CCF-FT-455AB 1 1.000E-004 +O.OOOE+OOO +O.OOOE+OOO COMMON CAUSE FAILURE OF NORMAL SPRAY VLVS TO 869 RCS-FCV-FT-AUXSP 1 1.000E-003 +0.000E+OOO +O.OOOE+OOO FAILURE OF AUXILIARY SPRAY 870 RCS-MDP-FR-RCPlA 4 3.000E-005 3.000E-005 1.000E+OOO RCP lA FAILS TO RUN 871 RCS-MDP-FR-RCPlC 4 3.000E-OOS 3.000E-OOS 1.000E+OOO RCP lC FAILS TO RUN 872 RCS-MDP-MA-RCPlC 1 +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON RCP lC - STATE 6 873 RCS-MDP-MAORCPlC 1 +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON RCP lC - STATE 10 874 RCS-XHE-FO-DPRES F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO OPERATOR FAILS TO COOLDOWN AND DEPRESS 875 RCS-XHE-FO-DPRT7 F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO OPERATOR FAILS COOLDOWN AND DPRES FOR SGTR 876 REC-XHE-FO-SCOOL 1 1.250E-001 +O.OOOE+OOO +O.OOOE+OO.

OP FAILS TO GET RCP SEAL COOL DURING SBO 877 REFUEL 1 6.000E-001 +O.OOOE+OOO +0.000E+OOO Frequency of Refueling 878 RHR-AOV-C0-1758 1 1.200E-005 S.OOOE-007 +O.OOOE+OOO AOV 1758 opens spuriously 879 RHR-AOV-OC-1758 1 7.500E-007 +O.OOOE+OOO +O.OOOE+OOO HCV-17S8 FAILS SHUT.

880 RHR-AOV-00-160S 1 2.400E-006 +O.OOOE+OOO +O.OOOE+OOO FCV-160S TRANSFERS FULLY OPEN AND REMAINS OPEN 881 RHR-ASF-PG-160S 1 3.000E-004 +O.OOOE+OOO +O.OOOE+OOO RHR FLOW ORIFICE PLUGGED.

882 RHR-CCF-FS-MDPAB 1 4.SOOE-004 +O.OOOE+OOO +O.OOOE+OOO COMMON CAUSE FAILURE OF MDP lA AND lB TO START 883 RHR-CCF-FT-720AB 1 2.600E-004 +O.OOOE+OOO +O.OOOE+OOO COMMON CAUSE FAILURE OF RHR MOVS 1720A 1720B 884 RHR-CKV-FT-CVll 1 1.000E-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CVll FAILS TO OPEN 885 RHR-CKV-FT-CVS 1 1.000E-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE CVS FAILS TO OPEN 886 RHR-CKV-00-CVll 1 1.000E-003 +0.000E+OOO +O.OOOE+OOO BACKFLOW THROUGH CVll 887 RHR-CKV-00-CVS 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO BACKFLOW THROUGH CVS 888 RHR-HTX-LK-ElA 4 7.200E-OOS 3.000E-006 2.400E+001 RHR HEAT EXCHANGER ElA TUBE LEAKS 1993/11/24 09:4S:14 page 37 E-38

,. BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 889 RHR-HTX-LK-ElB 4 7.200E-005 3.000E-006 2.400E+001 RHR HEAT EXCHANGER ElB TUBE LEAKS 890 RHR-HTX-PG-ElA 4 1.368E-004 5.700E-006 2.400E+001 RHR HEAT EXCHANGER ElA PLUGGED 891 RHR-HTX-PG-ElB 4 1.368E-004 5.700E-006 2.400E+001 RHR HEAT EXCHANGER ElB PLUGGED.

892 RHR-MOP-FR-A24HR 4 7. 200E-004 3. OOOE-005 2. 400E+001 RHR MOP lA FAILS TO RUN 24 HOURS 893 RHR-MOP-FR-B24HR 4 7.200E-004 3.000E-005 2.400E+001 RHR MOP lB FAILS TO RUN FOR 24 HOURS 894 RHR-MOP-FS-RHRlA 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO RHR MOP lA FAILS TO START ON DEMAND 895 RHR-MOP-FS-RHRlB 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO RHR MOP lB FAILS TO START ON DEMAND 896 RHR-MOP-MA-RHR1B F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON RHR PUMP lB - STATE 6 897 RHR-MOP-MAORHR1B F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON RHR PUMP lB - STATE 10 898 RHR-MOV-FT-1700 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO RHR MOV 1700 FAILS TO OPERATE ON DEMAND 899 RHR-MOV-FT-1701 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO RHR MOV 1701 FAILS TO OPEN ON DEMAND 900 RHR-MOV-FT-1720A 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO RHR MOV 1720A FAILS TO OPERATE ON DEMAND.

901 RHR-MOV-FT-1720B 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO RHR MOV 1720B FAILS TO OPERATE ON DEMAND.

902 RHR-MOV-MA-1720A F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON RHR MOV 1720A - STATE 6 903 RHR-MOV-MA01720A F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON RHR MOV 1720A - STATE 10 904 RHR-MOV-PG-1700 1 4.400E-004 1.000E-007 8.760E+003 RHR MOTOR OPERATED VALVE 1700 PLUGGED 905 RHR-MOV-PG-1701 1 4.400E-004 1.000E-007 8.760E+003 RHR MOTOR OPER VALVE 1701 PLUGGED 906 RHR-MOV-PG-1720A 1 4.400E-004 1.000E-007 8.760E+003 RHR MOTOR OPERATED VALVE 1720A PLUGGED.

907 RHR-MOV-PG-1720B 1 4.400E-004 1.000E-007 8.760E+003 RHR MOTOR OPERATED VALVE 1720B PLUGGED.

908 RHR-SRV-C0-1721 4 9.360E-005 3.900E-006 2.400E+001 SRV-1721 RELIEF VALVE INADVERTENT OPEN.

909 RHR-XMV-FT-XV20 1 1.000E-004 +O.OOOE+OOO +O.OOOE+OOO Manual Valve RH-20 Fails to Open 910 RHR-XMV-FT-XV24 1 1.000E-004 +O.OOOE+OOO +O.OOOE+OOO Manual Valve RH-24 Fails to Open 911 RHR-XVM-PG-XV12 1 4.400E-004 1.000E-007 8.760E+003 MANUAL VALVE XV12 PLUGGED 912 RHR-XVM-PG-XV15 1 4.400E-004 1.000E-007 8.760E+003 MANUAL VALVE XVlS PLUGGED 1993/11/24 09:45:14 page 38 E-39

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 913 RHR-XVM-PG-XV19 1 4.400E-004 1.000E-007 8.760E+003 MANUAL VALVE XV19 PLUGGED 914 RHR-XVM-PG-XV2 1 4.400E-004 l.OOOE-007 8.760E+003 MANUAL VALVE XV2 PLUGGED 915 RHR-XVM-PG-XV20 1 4.400E-004 l.OOOE-007 8.760E+003 MANUAL VALVE XV20 PLUGGED 916 RHR-XVM-PG-XV24 1 4.400E-004 l.OOOE-007 8.760E+003 MANUAL VALVE XV24 PLUGGED 917 RHR-XVM-PG-XV6 1 4.400E-004 l.OOOE-007 8.760E+003 MANUAL VALVE XV6 PLUGGED 918 RHR-XVM-PG-XVS 1 4.400E-004 l.OOOE-007 8.760E+003 MANUAL VALVE XVS PLUGGED 919 RMT-ACT-FA-RMTSA F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO NO SIGNAL FROM RMTS TRAIN A 920 RMT-ACT-FA-RMTSB F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO NO SIGNAL FROM RMTS TRAIN B 921 RMT-CCF-FA-MSCAL F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO COMMON CAUSE FAILURE RMT DUE TO MISCALIBRATION 922 RWT-TNK-LF-RWST 1 2.700E-006 +O.OOOE+OOO +O.OOOE+OOO Insuff. water available from the RWST 923 SAS-CCF-FR-SACl 2 4.SOOE-004 2.000E-005 +O.OOOE+OOO COMMON CAUSE FAILURE OF SA COMPRESSORS TO RUN 924 SAS-CPS-FR-lSACl 2 4.SOOE-003 2.000E-004 +O.OOOE+OOO SERVICE AIR COMPRESSOR l-SA-C-1 FAILS TO RUN 925 SAS-CPS-FR-2SAC1 2 4.SOOE-003 2.000E-004 +O.OOOE+OOO SERVICE AIR COMPRESSOR 2-SA-C-l FAILS TO RUN 926 SAS-CPS-FS-2SAC1 1 8.000E-002 +O.OOOE+OOO +O.OOOE+OOO SERVICE AIR COMPRESSOR 2-SA-C-l FAILS TO START 927. SEMI-VIT-BUS 1 l.OOOE-005 +O.OOOE+OOO +O.OOOE+OOO FAILURE OF SEMI-VITAL BUS 928 SGA-DRAINED-R 1 2.300E-002 +O.OOOE+OOO +O.OOOE+OOO SG A SECONDARY SIDE DRAINED 929 SGB-DRAINED-R 1 2.300E-002 +O.OOOE+OOO +O.OOOE+OOO SG B DRAINED 930 SGC~DRAINED-R 1 2.300E-002 +O.OOOE+OOO +O.OOOE+OOO SG C DRAINED 931 SGRT-AOV-LK-lOOA 1 2.400E-005 +O.OOOE+OOO +O.OOOE+OOO INSTRUMENT AIR LEAKS AT TV-BD-lOOA 932 SGRT-AOV-LK-100B 1 2.400E-005 +O.OOOE+OOO +O.OOOE+OOO INSTRUMENT AIR LEAK AT TV-BD-100B 933 SGRT-AOV-LK-lOOC 1 2.400E-005 +O.OOOE+OOO +O.OOOE+OOO INSTRUMENT AIR LEAKS AT TV-BD-lOOC 934 SGRT-AOV-LK-lOOD 1 2.400E-005 +O.OOOE+OOO +O.OOOE+OOO INSTRUMENT AIR LEAK AT TV-BD-lOOD 935 SGRT-AOV-LK-lOOE 1 2.400E-005 +O.OOOE+OOO +O.OOOE+OOO INSTRUMENT AIR LEAKS AT TV-BD-lOOE 936 SGRT-AOV-LK-lOOF 1 2.400E-005 +O.OOOE+OOO +O.OOOE+OOO INSTRUMENT AIR LEAK AT TV-BD-lOOF J.993/11/24 09:45:14 page 39 E-40

Event BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Calculation Case: ALTERNATE Mean Number Primary Name Type Probability Lamda Tau 937 SGRT-AOV-OC-lOOA 1 7.500E-007 +O.OOOE+OOO +O.OOOE+OOO TV-BD-lOOA TRANSFERS CLOSED 938 SGRT-AOV-OC-lOOB 1 7.500E-007 +O.OOOE+OOO +O.OOOE+OOO TV-BD-lOOB TRANSFERS CLOSED 939 SGRT-AOV-OC-lOOC 1 7.500E-007 +O.OOOE+OOO +O.OOOE+OOO TV-BD-lOOC TRANSFERS CLOSED 940 SGRT-AOV-OC-lOOD 1 7.500E-007 +O.OOOE+OOO +O.OOOE+OOO TV-BD-lOOD TRANSFERS CLOSED 941 SGRT-AOV-OC-lOOE 1 7.500E-007 +O.OOOE+OOO +O.OOOE+OOO TV-BD-lOOE TRANSFERS CLOSED 942 SGRT-AOV-0C-100F 1 7.500E-007 +O.OOOE+OOO +O.OOOE+OOO TV-BD-lOOF TRANSFERS CLOSED 943 SGRT-AOV-PG-lOOA 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO TV-BD-lOOA PLUGGED 944 SGRT-AOV-PG-lOOB 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO TV-BD-lOOB PLUGGED 945 SGRT-AOV-PG-100C 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO TV-BD-100C PLUGGED 946 SGRT-AOV-PG-100D 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO TV-BD-lOOD PLUGGED 947 SGRT-AOV-PG-lOOE 1 4.000E-OQ5 +O.OOOE+OOO +O.OOOE+OOO TV-BD-100E PLUGGED 948 SGRT-AOV-PG-100F 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO TV-BD-100F PLUGGED 949 SGRT-CKV-FO-CMFA 1 1. OOOE-003 +O.OOOE+OOO +O.OOOE+OOO Failure of Check Valve to Chem feed to Open 950 SGRT-CKV-FO-CMFB 1 1. OOOE-003 +O.OOOE+OOO +O.OOOE+OOO Failure of Check Valve to Chem feed to Open 951 SGRT-CKV-FO-CMFC 1 1. OOOE-003 +O.OOOE+OOO +O.OOOE+OOO Failure of Check Valve to Chem feed to Open 952 SGRT-CKV-FT-RTll 1 1. OOOE-004 +O.OOOE+OOO +O.OOOE+OOO RT-11 FAIL TO OPEN 953 SGRT-CKV-FT-RT30 1 1. OOOE-004 +O.OOOE+OOO +O.OOOE+OOO RT-30 FAIL TO OPEN 954 SGRT-CKV-FT-RT49 1 1. OOOE-004 +O.OOOE+OOO +O.OOOE+OOO RT-49 FAIL TO OPEN 955 SGRT-HTX-LK-ElA 1 7.200E-005 +O.OOOE+OOO +O.OOOE+OOO HTX RT-ElA LEAKING 956 SGRT-HTX-LK-ElB 1 7.200E-005 +O.OOOE+OOO +O.OOOE+OOO HTX RT-ElB LEAKING 957 SGRT-HTX-LK-ElC 1 7.200E-005 +O.OOOE+OOO +O.OOOE+OOO HTX RT-ElC LEAKING 958 SGRT-HTX-MA-ElA 1 2.000E-004 +O.OOOE+OOO +O.OOOE+OOO HTX RT-ElA IN MAINTENANCE 959 SGRT-HTX-MA-ElB 1 2.000E-004 +O.OOOE+OOO +O.OOOE+OOO HTX RT-ElB IN MAINTENANCE 960 SGRT-HTX-MA-ElC 1 2.000E-004 +O.OOOE+OOO +O. OOOE+OO.O HTX RT-E1C IN MAINTENANCE 1993/11/24 09:45:14 page 40

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BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 961 SGRT-HTX-PG-ElA 1 l.400E-004 +O.OOOE+OOO +O.OOOE+OOO HTX RT-ElA PLUGGED 962 SGRT-HTX-PG-ElB 1 l.400E-004 +O.OOOE+OOO +O.OOOE+OOO HTX RT-ElB PLUGGED 963 SGRT-HTX-PG-ElC 1 l.400E-004 +O.OOOE+OOO +O.OOOE+OOO HTX RT-ElC PLUGGED 964 SGRT-MV-PG-150 1 4.000E-005 +0.000E+OOO +O.OOOE+OOO MV 150 PLUGGED 965 SGRT-MV-PG-160 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO MV 160 PLUGGED 966 SGRT-MV-PG-170 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO MV 170 PLUGGED 967 SGRT-MV-PG-BDl 1 4.000E-005 +O.OOOE+OOO +0.000E+OOO BD-1 PLUGGED 968 SGRT-MV-PG-BDll 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO BD-11 PLUGGED 969 SGRT-MV-PG-BD12 1 4.000E-005 +O.OOOE+OOO +0.000E+OOO BD-12 PLUGGED 970 SGRT-MV-PG-BD14 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO BD-14 PLUGGED 971 SGRT-MV-PG-BD2 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO BD-2 PLUGGED 972 SGRT-MV-PG-BD21 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OO BD-21 PLUGGED 973 SGRT-MV-PG-BD22 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO BD-22 PLUGGED 974 SGRT-MV-PG-BD24 1 4.000E-005 +O.OOOE+OOO +0.000E+OOO BD-24 PLUGGED 975 SGRT-MV-PG-BD4 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO BD-4 PLUGGED 976 SGRT-MV-PG-RTl 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO RTl PLUGGED 977 SGRT-MV-PG-RT13 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO RT13 PLUGGED 978 SGRT-MV-PG-RT18 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO RT18 PLUGGED 979 SGRT-MV-PG-RT19 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO RT19 PLUGGED 980 SGRT-MV-PG-RT2 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO RT2 PLUGGED 981 SGRT-MV-PG-RT20 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO RT20 PLUGGED 982 SGRT-MV-PG-RT21 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO RT21 PLUGGED 983 SGRT-MV-PG-RT25 1 4.000E-005 +0.000E+OOO +O.OOOE+OOO RT25 PLUGGED 984 SGRT-MV-PG-RT27 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO RT27 PLUGGED 1993/11/24 09:45:14 page 41 E-42

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 985 SGRT-MV-PG-RT32 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO RT32 PLUGGED 986 SGRT-MV-PG-RT37 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO RT37 PLUGGED 987 SGRT-MV-PG-RT38 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO RT38 PLUGGED 988 SGRT-MV-PG-RT39 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO RT39 PLUGGED 989 SGRT-MV-PG-RT40 1 4.000E-005 +0.000E+OOO +O.OOOE+OOO RT40 PLUGGED 990 SGRT-MV-PG-RT44 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO RT44 PLUGGED 991 SGRT-MV-PG-RT46 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO RT46 PLUGGED 992 SGRT-MV-PG-RT51 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO RT51 PLUGGED 993 SGRT-MV-PG-RT56 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO RT56 PLUGGED 994 SGRT-MV-PG-RT57 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO RT57 PLUGGED 995 SGRT-MV-PG-RT6 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO RT6 PLUGGED 996 SGRT-MV-PG-RTB 1 4.000E-005 +O.OOOE+OOO +O.OOOE+OOO RTB PLUGGED 997 SGRT-PMP-FR-RTlA 1 7.200E-004 +O.OOOE+OOO +O.OOOE+OOO SGRT PUMP RT-lA FAILS TO RUN 998 SGRT-PMP-FR-RTlB 1 7.200E-004 +O.OOOE+OOO +O.OOOE+OOO SGRT PUMP RT-lB FAILS TO RUN 999 SGRT-PMP-FR-RTlC 1 7.200E-004 +O.OOOE+OOO +O.OOOE+OOO SGRT PUMP RT-lC FAILS TO RUN 1000 SGRT-PMP-FS-RTlA 1 3.000E-003 +O.OOOE+OOO .+O;OOOE+OOO PUMP RT-lA FAILS TO START 1001 SGRT-PMP-FS-RTlB 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO PUMP RT-lB FAILS TO START 1002 SGRT-PMP-FS-RTlC 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO PUMP RT-lC FAILS TO START 1003 SGRT-PMP-MA-RTlA 1 1.000E-003 * +O.OOOE+OOO +O.OOOE+OOO PUMP RT-lA IN MAINTENANCE

1004 SGRT-PMP-MA-RT1B 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO PUMP RT-lB IN MAINTENANCE 1005 SGRT-PMP-MA-RTlC 1 1.000E-003 +O.OOOE+OOO +O.OOOE+OOO PUMP RT-lC IN MAINTENANCE 1006 SGRT-SGA F +O.OOOE+OOO +O.OOOE+OOO +0.000E+OOO SGRT A INOPERATIONAL 1007 SGRT-SGB F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO SGRT B INOPERATIONAL 1008 SGRT-SGC F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO SGRT C INOPERATIONAL 1993/11/24 09:45:14 page 42 E-43

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 1009 SGRT-XHE-FS-100 F +O.OOOE+OOO +0.000E+OOO +O.OOOE+OOO OPERATOR FAILS TO ALIGN SGRT SYSTEM 1010 SGS-DRAINED-CSD 1 l.OOOE-003 +0.000E+OOO +O.OOOE+OOO Secondary Side of SGs Drained in POSs 6 .of Drained Maintenan 1011 SGS-DRAINED-R 1 8.300E-003 +O.OOOE+OOO +O.OOOE+OOO Secondary Side of SGs Drained in POSs 6 or 10 or Refueliµg 1012 SIS-ACT-FA-SISA 1 +O.OOOE+OOO +O.OOOE+OOO +0.000E+OOO NO SIGNAL FROM SIS TRAIN A 1013 SIS-ACT-FA-SISB 1 +0.000E+OOO +O.OOOE+OOO +0.000E+OOO NO SIGNAL FROM SIS TRAIN B 1014 SLOCA-NRACSL-LT 1 9.200E-002 +O.OOOE+OOO +O.OOOE+OOO SEAL LOCA W/ NON REC AC POWER AND SEC DEPRESS 1015 SLOCA-NRACSL-ST 1 9.900E-002 +O.OOOE+OOO +O.OOOE+OOO SEAL LOCA W/ NON REC AC POWER AND NO DEPRESS 1016 SP-SI-CLSI-HE F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO SPURIOUS SI/CLSI SIGNAL 1017 SSHR-AOV-XHE-105 1 1.300E-002 +O.OOOE+OOO +O.OOOE+OOO Operator Failure to Use Steam Dump to Condenser 1018 SUMPPLUG 1 l.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO Contai~ment Sump Plugged 1019 SW-AOV-FT-SW263 1 l.OOOE+OOO +0.000E+OOO +0.000E+OOO l-SW-263 FAILS CLOSED ON LOSS OF OFFSITE POWER

1020 SW-AOV-SC-SW263 1 7.500E-007 +O.OOOE+OOO +O.OOOE+OO SOLENOID OPERATED VALVE 1-SW-263 SPURIOUSLY CLOSES 1021 SW-CCF-AIRINJ 1 3.200E-004 +O.OOOE+OOO +O.OOOE+OOO AIR INJESTION TO CC HXRs CCF 1022 SW-CCF-SC-MOV102 1 2.SOOE-004 +O.OOOE+OOO +O.OOOE+OOO MOVs l-SW-MOV-102A & 102B SPURIOUS CLOSE 1023 SW-CKV-PG6-SW333 1 6.000E-007 l.OOOE-007 6.000E+OOO 4C CHILLER SW l-SW-333 PLUGS DURING 6 HOUR LCO 1024 SW-PIPE-MA-2PS3 1 l.200E-005 +O.OOOE+OOO +O.OOOE+OOO UNSCHEDULED MAINT ON UNIT 2 SERVICE WATER SUPPLY PIPING (PS3 1025 SW-PIPE-MA-PS4 1 l.200E-005 +O.OOOE+OOO +O.OOOE+OOO UNSCHEDULED MAINT ON UNIT 1 SERVICE WATER SUPPLY PIPING (PS4 1026 SW-STR-PL-TS15CA 4 7.200E-004 3.000E-005 2.400E+001 STRAINER TS-15C FOR TRAIN A PLUGGED DURING MISSION 1027 SW-STR-PL-TSlSCC 4 7.200E-004 3.000E-005 2.400E+001 STRAINER TS-15C FOR TRAIN C PLUGGED DURING MISSION 1028 SW-TBFLOWDIVER 4 2.664E-006 l.llOE-007 2.400E+001 FLOW DIVERSION TO TURBINE BLDG - SW SUBSYSTEM 1029 SWS-AOV-SC-lOOA 1 l.200E-005 5.000E-007 2.400E+001 1-SW-PCV-lOOA SPURIOUS CLOSED DURING MISSION 1030 SWS-AOV-SC-lOOC 1 l.200E-OOS 5.000E-007 2.400E+001 1-SW-PCV-lOOC SPURIOUS CLOSED DURING MISSION 1031 SWS-CCF-FT-3ABCD 1 6.300E-004 +O.OOOE+OOO +O.OOOE+OOO COMMON CAUSE FAILURE OF SWS ISOL MOVS 103ABCD 1032 SWS-CCF-PG-TSlSC 1 l.900E-004 +O.OOOE+OOO +O.OOOE+OOO CCF 3/3 PG TS-lSC STRAINERS PLUG 1993/11/24 09:45:14 page 43 E-44

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 1033 SWS-CKV-FT-SW323 1 1.000E-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE 1-SW-323 FAILS TO OPEN 1034 SWS-CKV-PG-SW313 4 2.400E-006 1.000E-007 2.400E+001 CHECK VALVE 1-SW-313 PLUGS DURING MISSION 1035 SWS-CKV-PG-SW333 4 2.400E-006 1. OOOE-007 2.400E+001 CHECK VALVE 2-SW-333 PLUGS DURING MISSION 1036 SWS-MOV-FT-103A 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO SWS MOTOR OP VLV 103A FAILS TO OPEN 1037 SWS-MOV-FT-103B 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO SWS MOTOR OP VLV 103B FAILS TO OPEN 1038 SWS-MOV-FT-103C 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO SWS MOTOR OP VLV 103C FAILS TO OPEN 1039 SWS-MOV-FT-103D 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO SWS MOTOR OP VLV 103D FAILS TO OPEN 1040 SWS-MOV-MA-103A 1 2.000E-004 +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE SWS MOV 103A 1041 SWS-MOV-MA-103B 1 2.000E-004 +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE SWS MOV 103B 1042 SWS-MOV-MA-103C 1 2.000E-004 +O.OOOE+OOO +O.OOOE+OOO TEST .AND MAINTENANCE SWS MOV 103C 1043 SWS-MOV-MA-103D 1 2.000E-004 +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON SWS MOV103D 1044 SWS-MOV-MA-104D 1 +O.OOOE+OOO +b.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON SWS MOV 104D - STATE 6 1045 SWS-MOV-MA0103A 1 2.000E-004 +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE SWS MOV 103A 1046 SWS-MOV-MA0104D 1 +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO TEST AND MAINTENANCE ON SWS MOV 104D - STATE 10 1047 SWS-MOV-OP-RSFP 1 1.440E-003 +O.OOOE+OOO +O.OOOE+OOO OPERS DON'T OPEN SW MOVS 1048 SWS-MOV-OP-RSS 1 1.440E-003 +O.OOOE+OOO +O.OOOE+OOO OPER DON'T OPEN MOVS 1049 SWS-MOV-PG-104A 1 6.500E-004 l.OOOE-007 1.300E+004 SWS MOTOR OPER VALVE 104A PLUGGED 1050 SWS-MOV-PG-104B 1 6.500E-004 l.OOOE-007 1. 300E+004 SWS MOTOR OPER VALVE 104B PLUGGED 1051 SWS-MOV-PG-104C 1 6.500E-004 l.OOOE-007 1. 300E+004 SWS MOTOR OPER VALVE 104C PLUGGED 1052 SWS-MOV-PG-104D 1 6.500E-004 l.OOOE-007 1. 300E+004 SWS MOTOR OPER VALVE 104D PLUGGED 1053 SWS-MOV-PG-105A 1 6.500E-004 l.OOOE-007 1. 300E+004 SWS MOTOR OPER VALVE 105A PLUGGED 1054 SWS-MOV-PG-lOSB 1 6.500E-004 l.OOOE-007 1.300E+004 SWS MOTOR OPER VALVE 105B PLUGGED 1055 SWS-MOV-PG-105C 1 6.500E-004 l.OOOE-007 l.300E+004 SWS MOTOR OPER VALVE 105C PLUGGED 1056 SWS-MOV-PG-105D 1 6.500E-004 l.OOOE-007 l.300E+004 SWS MOTOR OPER VALVE 105D PLUGGED 1993/11/24 09:45:14 page 4_4

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Event Number Primary Name BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Calculation Type Case: ALTERNATE Mean Probability Lamda Tau 1057 SWS-MOV-PG-106A 1 6.500E-004 1.000E-007 l.300E+004 SWS MOTOR OPER VALVE 106A PLUGGED 1058 SWS-MOV-PG-106B 1 6.500E-004 1.000E-007 1.300E+004 SW$ MOTOR OPER VALVE 106B PLUGGED 1059 SWS-PCV-FT-lOOB 1 1.000E-003 +0.000E+OOO +O.OOOE+OOO PRES CONTROL VALVE 1-SW-PCV-lOOB FAILS TO OPEN DURING STANDB 1060 SWS-STR-PG-TS15C 6 1.080E-002 3.000E-005 7.200E+002 STRAINER TS-lSC PLUGGED DURING STANDBY 1061 SWS-XHE-AP12 1 1.000E+OOO +O.OOOE+OOO +O.OOOE+OOO 1062 SWS-XVM-PG-37U2 1 4.000E-005 1.000E-007 7.200E+002 MANUAL VALVE XV37 AT UNIT 2 PLUGGED 1063 SWS-XVM-PG-39U2 1 4.000E-005 1.000E-007 7.200E+002 MANUAL VALVE XV39 AT UNIT 2 PLUGGED 1064 SWS-XVM-PG-SW321 1 4.000E-005 1. OOOE-007 7.200E+002 GATE VALVE 1-SW-321 PLUGGED DURING STANDBY 1065 sws-XVM-PG-SW324 1 4.000E-005 1.000E-007 7.200E+002 GATE VALVE 1-SW-324 PLUGGED DURING STANDBY 1066 SWS-XVM-PG-XV33 1 4.000E-005 1. OOOE-007 7.200E+002 MANUAL VALVE XV33 PLUGGED 1067 SWS-XVM-PG-XV35 1 4.000E-005 1. OOOE-007 7.200E+002 MANUAL VALVE XV35 PLUGGED 1068 SWS-XVM-PG-XV37 1 4.000E-005 1.000E-007 7.200E+OO MANUAL VALVE XV37 PLUGGED 1069 SWS-XVM-PG-XV39 1 4.000E-005 1. OOOE-007 7.200E+002 MANUAL VALVE XV39 PLUGGED 1070 T-TOP 1 6.600E+OOO +O.OOOE+OOO +O.OOOE+OOO TURBINE TRIP SUBSEQUENT TO ATWS 1071 TB-FREQ-VSFM06 1 2.200E-002 +O.OOOE+OOO +O.OOOE+OOO FREQ OF MAINT TO OPER Ul AHU FAN MOTOR 1VSFM06A IN 1 YEAR 1072 UNIT2-LOW-POWER 1 3.SOOE-001 +O.OOOE+OOO +O.OOOE+OOO UNIT 2 LOW POWER INSUF STM FOR AFW TDP 1073 VS-AHU-FX-VSAC6 6 7.621E-003 1.740E-006 8.760E+003 FREQ OF 1-VS-AC-6 LOSS OF FUNCTION IN 1 YEAR INTERVAL 1074 VS-AHU-LF:..VSAC6 4 3.432E-OOS 1.430E-006 2.400E+001 LOSS OF FUNCTION IN AIR HANDLING UNIT 1-VS-AC-6 1075 VS-AHU-LF-VSAC7 4 3.432E-005 1.430E-006 2.400E+001 LOSS OF FUNCTION IN AIR HANDLING UNIT 1-VS-AC-7 1076 VS-AHU-LF7-VSAC7 6 1.201E-004 1.430E-006 1.680E+002 Ul AHU 1-VS-AC-7 LOSS OF FUNCTION DURING 7 DAY LCO 1077 VS-AHU-MA-VSAC6 F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO AIR HANDLING UNIT 1-VS-AC-6 UNSCHEDULED MAINTENANCE 1078 VS-AHU-MA-VSAC7 1 3.?SOE-003 +O.OOOE+OOO +O.OOOE+OOO FAN MOTOR 1-VS-FM0-7 FOR 1-VS-AC-7 UNAVAIL DUE TO MAIN 1079 VS-BCFLOWDIVER 4 2.664E-006 1.llOE-007 2.400E+001 CHILLED WATER DIVERSION TO BEARING COOLING SYSTEM 1080 VS-CCF-FT-PABC 1 1.080E-004 +O.OOOE+OOO +O.OOOE+OOO CCF 3/3 FR 24 HR 1-VS-P-lA BC FAIL (AIR LOW SUCTION) 1993/11/24 09:45:14 page 45 E-46

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BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 1081 VS-CHL-FR-VSE3A 4 3.600E*003 1.500E-004 2.400E+001 CHILLER 1-VS-E-3A FAILS TO RUN 24 HR 1082 VS-CHL-FR-VSE3B 4 3.600E-003 1.500E-004 2.400E+001 CHILLER 1-VS-E-3B FAILS TO RUN 24 HR 1083 VS-CHL-FR-VSE4A 4 3.600E-003 1.500E-004 2.400E+001 CHILLER 1-VS-E-4A FAILS TO RUN FOR 24 HR MISSION 1084 VS-CHL-FR-VSE4B 4 3.600E-003 1.500E-004 2.400E+001 CHILLER 1-VS-E-4B FAILS TO RUN FOR 24 HR MISSION 1085 VS-CHL-FR-VSE4C 4 3.600E-003 1.500E-004 2.400E+001 1-VS-E-4C FAILS TO RUN FOR 6 HOUR LCO 1086 VS-CHL-FR6-VSE4C 4 9.000E-004 1.500E-004 6.000E+OOO 1-VS-E-4C CHILLER FAILS TO RUN FOR 6 HOUR LCO 1087 VS-CHL-FR7-VSE4B 6 5.400E-002 1.500E-004 7.200E+002 1-VS-E-4B CHILLER FAILS TO RUN FOR 7 DAY LCO 1088 VS-CHL-FS-VSE4B 1 3.900E-003 +O.OOOE+OOO +O.OOOE+OOO CHILLER 1-VS-E-4B FAILS TO START 1089 VS-CHL-MA-VSE4B F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO MAINTENANCE OF CHILLER 1-VS-E-4B - STATE 6 1090 VS-CHL-MAOVSE4B F +O.OOOE+OOO +O.OOOE+OOO +O.OOOE+OOO MAINTENANCE OF CHILLER 1-VS-E-4B - STATE 6 1091 VS-CKV-FT-VS292 1 l.OOOE-004 +O.OOOE+OOO +O.OOOE+OOO CHECK VALVE 1-VS-292 FAILS CLOSED DURING STANDBY 092 VS-CKV-PG-VS271 4 2.400E-006 l.OOOE-007 2.400E+001 CHILLER l-VS-E-3B CHECK VALVE 1-VS-271 DURING 24 HR 1093 VS-CKV-PG-VS276 4 2.400E-006 1.000E-007 2.400E+001 CHILLER 1-VS-E-3A CHECK VALVE 1-VS-276 PLUGS DURING 24 HR 1094 VS-CKV-PG-VS288 4 2.400E-006 1.000E-007 2.400E+001 CHECK VALVE l-VS-288 PLUGS DURING MISSION 1095 VS-CKV-PG-VS296 4 2.400E-006 1.000E-007 2.400E+001 CHECK VALVE 1-VS-296 PLUGS DURING MISSION 1096 VS-CKV-PG6-VS296 1 6.000E-007 l.OOOE-007 6.000E+OOO 4C CHILLER CHILLED WATER 1-VS-296 PLUGS DURING 6 HOUR LCO 1097 VS-EVC-FR-VSElA 4 3.600E-003 1.500E-004 2.400E+001 EVAPORATIVE CON- DENSER 1-VS-E-lA FAILS TO RUN 24 HR 1098 VS-EVC-FR-VSElB 4 3.600E-003 1.500E-004 2.400E+001 EVAPORATIVE CON- DENSER 1-VS-E-lB FAILS TO RUN 24 HR 1099 VS-FMO-FR-FM06 4 9.864E-005 4.llOE-006 2.400E+001 1-VS-AC-6 FAN MOTOR FAILS TO RUN FOR MISSION 1-VS-FM0-6 1100 VS-FMO-FR-FM07 4 9.864E-005 4.llOE-006 2.400E+001 1-VS-AC-7 FAN MOTOR FAILS TO RUN FOR MISSION l-VS-FM0-7 1101 VS-FMO-FR7-FM07 6 3.452E-004 4.llOE-006 l.680E+002 FAN MOTOR l-VS-FM0-7 FOR l-VS-AC-7 FAILS TO RUN 7 DAY LCO 1102 VS-FMO-FS-FM06 1 3.900E-003 +O.OOOE+OOO +O.OOOE+OOO 1-VS-AC-6 FAN MOTOR FAILS TO START l-VS-FM0-6 1103 VS-FMO-FS-FM07 1 3.900E-003 +O.OOOE+OOO +O.OOOE+OOO FAN MOTOR l-VS-FM0-7 FOR 1-VS-AC-7 FAILS TO START 1104 VS-FRQ-MA-VSE4A 1 3.410E+OOO +O.OOOE+OOO +O.OOOE+OOO FREQ OF MAINTENANCE TO 1ST CHILLER TRAIN IN 1 YEAR INTERVAL 1993/11/24 09:45:14 page 46

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BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation ,Mean Number Primary Name Type Probability Lamda Tau 1.1.05 VS-MDF-FR-VSPlB 4 7.200E-004 3.000E-005 2.400E+001.

MOTOR DRIVEN PUMP 1-VS-P-lB FAILS TO RUN DURING MISSION 1.1. 0 6 VS-MDF-FR-VSPlC 4 7.200E-004 3.000E-005 2.400E+001 MOTOR DRIVEN PUMP 1-VS-P-lC FAILS TO RUN 1.1. 07 VS-MDP-FR-VSPlA 4 7.200E-004 3.000E-005 2.400E+001.

MOTOR DRIVEN PUMP 1-VS-P-lA FAILS TO RUN 1.1. 0 8 VS-MDP-FR-VSP2A 4 7.200E-004 3.000E-005 2.400E+001.

MOTOR DRIVEN PUMP l-VS-P-2A FAILS TO RUN DURING MISSION 1.1.0 9 VS-MDP-FR-VSP2B 4 7.200E-004 3.000E-005 2.400E+001 MOTOR DRIVEN PUMP l-VS-P-2B FAILS TO RUN DURING MISSION 1.1.1.0 VS-MDP-FR-VSP2C 4 7.200E-004 3.000E-005 2.400E+001 MOTOR DRIVEN PUMP l-VS-P-2C FAILS TO RUN DURING MISSION 1.1.1.1. VS-MDP-FR-VSP3A 4 7.512E-004 3.130E-005 2.400E+001 CHILLER l-VS-E-3A PUMP l-VS-P-3A FAILS TO RUN 24 HR 1.1.1.2 VS-MDP-FR-VSP3B 4 7.512E-004 3.130E-005 2.400E+001 CHILLER l-VS-E-3B PUMPS 1.-VS-P-3B FAILS TO RUN 24 HR 1.1.1.3 VS-MDP-FR6-VSP1C 4 l.SOOE-004 3.000E-005 6.000E+OOO 4C CHILLER SW PUMP 1.-VS-P-lC FAILS TO RUN FOR 6 HOUR LCO 1.1.1.4 VS-MDP-FR6-VSP2C 4 l.SOOE-004 3.000E-005 6.000E+OOO 4C CHILLER CHILLED WATER l-VS-P-2C PUMP FAILS TO RUN FOR 6 H 1.11.5 VS-MDP-FR7-VSP1B 1 l.080E-002 3.000E-005 7.200E+002 STANDBY 4B CHILLER 1.-VS-P-lB PUMP FAILS TO RUN FOR 7 DAY LCO 1116 VS-MDP-FR7-VSP2B 1 l.OBOE-002 3.000E-005 7.200E+OO STANDBY 4B CHILLER l-VS-P-2B PUMP FAILS TO RUN FOR 7 DAY LC 1117 VS-MDP-FS-VSPlB 1. 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO MOTOR DRIVEN PUMP 1-VS-P-lB FAILS TO START FROM STANDBY 1118 VS-MDP-FS-VSP2B 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO MOTOR DRIVEN PUMP 1-VS-P-2B FAILS TO START FROM STANDBY 111.9 VS-MOV-FT-PG1.07B 1 3.000E-003 +O.OOOE+OOO +O.OOOE+OOO MOTOR OPERATED VALVE 1.-PG-MOV-107B FAILS TO OPEN 1120 VS-MOV-SC-P107A 1 1..200E-005 5.000E-007 2.400E+001 MOV 1.-PG-MOV-107A SPURIOUS CLOSES DURING MISSION 1121 VS-MOV-SC-Pl.07C 1 1..200E-005 5.000E-007 2 .. 400E+001 MOV 1-PG-MOV-107C SPURIOUS CLOSES DURING MISSION 1122 VS-MSW-NO-TRANl 1. 2.660E-005 +O.OOOE+OOO +O.OOOE+OOO MANUAL SWITCH FAILS OPEN TRANSFER SW 1 FOR l-VS-E-4B 1123 VS-SW-CO-ACGRlB 1. 2.660E-005 +O.OOOE+OOO +O.OOOE+OOO MANUAL SELECTOR SWITCH FAILS OPEN A/C GROUP 1.B 1124 VS-XHE-FO-E018 1 1.000E+OOO +O.OOOE+OOO +O.OOOE+OOO 1.-E-O RX TRIP OR SI STEP 18 VERIFY VENTILATION ALIGNMENT 1125 VS-XHE-FO-FCAlO 1 1.000E+OOO +O.OOOE+OOO +O.OOOE+OOO FCA-1..00 SAFE SHUTDOWN AREA FIRE ATTACHMENT 10 VENT (OPEN CR 1126 VS-XVM-FT-VS247 6 3.600E-005 1.000E-007 7.200E+002 GATE VALVE 1.-VS-247 FAILS TO OPEN OR PLUGS (DURING SHUTDOWN 1.1.27 VS-XVM-FT-VS251 6 3.600E-005 1.000E-007 7.200E+002 GATE VALVE 1-VS-251 FAILS TO OPEN OR PLUGS (DURING SHUTDOWN) 1128 VS-XVM-PG-VS291. 6 3.600E-005 1.000E-007 7.200E+002 GATE VALVE 1-VS-291 PLUGS DURING STANDBY 1993/1.1/24 09:45:1.4 page 47 E-48

BASIC EVENTS PROBABILITY REPORT Family: FLOOD/WINDOW Case: ALTERNATE Event Calculation Mean Number Primary Name Type Probability Lamda Tau 1129 VS-XVM-PG-VS294 6 3.600E-005 l.OOOE-007 7.200E+002 GATE VALVE 1-VS-294 PLUGS DURING STANDBY 1130 Z 1 1.400E-002 +O.OOOE+OOO +0.000E+OOO UNFAVORABLE MODERATOR TEMP COEFFICIENT 1131 Z1 1 5.000E-001 +O.OOOE+OOO +O.OOOE+OOO VERY LOW MODERATOR TEMP COEFFICIENT 1993/11/24 09:45:14 page 48

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Kiyoharu Abe Ephraim Asculai

Dept. of Reactor Safety Research Division of Nuclear Safety Nuclear Safety Research Center Wagramestrasse, 5 Takai Research Establishment P.O. Box 100 JAERI A-1400 Wien Tokai-mura, Naga-gun AUSTRIA Ibaraki-ken, JAPAN Vladimar Asmolov Head, Nuclear Safety Department Sarbes Acharya I. V. Kurchatov Institute Department of Energy of Atomic Enegry NS-1/FORS Moscow, 123181 Washington, DC 20585 RUSSIA Dr. Ulvi Adalioglu J. de Assuncao Cekmece Nukleer Arastraima ve Cabinete de Proteccao e Egitim Merekezi Seguranca Nuclear P.K. 1 Ministerio da Indusstria Havaalani/ISTANBUL Ave. de Republica 45-6 TURKEY 1000 Lisbon PORTUGAL Dr. Eng. Kiyoto Aizawa Senior Engineer H.P. Balfanz, Head Reactor Eng. Dev. Department Institute of Probabilistic PNC Safety Analysis 9-13, Chome, Akasaka TUV Nord Minato-K, Tokyo Grosse Bahnstrasse 31 JAPAN D-22525 Hamburg 54 GERMANY Harry Alter Manager Applied Tech Pat Baranowsky Nuclear Systems Tech USNRC-AEOD/TPAB NE-46 MS: T-4A9 US DOE Washington, DC 20585 Robert A. Bari, Deputy Chairman Dept of Nuclear Energy R.M. Andrews Bldg 197C Nuclear Installations Insp. Brookhaven National Laboratory St. Peters House Upton, NY 11973 Balliol Raad, Bootle Merseyside L20 31Z UNITED KINGDOM Librarian Technical Information Section Battelle Pacific Northwest Lab George Apostolakis P. 0. Box 999 UCLA Richland, WA 99352 Boelter Hall, Room 5532 Los Angeles, CA 90024-1597 Dr. John Baum Dept of Nuclear Energy Director of Reactor Engineering Radiological Sciences Div Argonne National Laboratory Bldg 703 M 9700 S Cass Ave Brookhaven National Laboratory Bldg 208 Upton, NY 11973 Argonne, IL 60439

Dist-1

Eric Beckjord Dennis Bley USNRC-RES/DO Buttonwood Consulting MS: T-10F12 17291 Buttonwood St.

Fountain Valley, CA 92708 Robert Bernero USNRC-NMSS/DO Roger Blond MS: T-8A23 Booz-Allen & Hamilton 4330 East West Highway Bethesda, MD 20814 Andrea Besi Institute for Systems Engineering and Informatics M. P. Bohn CEC Joint Research Centre Division 6449 CP N 1 Sandia National Laboratories 1-21020 Ispra (Varese) Albuquerque, NM 87185 ITALY Dr. Mario Bonaca John Bickel Manager, Reactor Engineering Idaho National Engineering Lab. Northeast Utilities EG&G MS: 3850 P.O. Box 270 P.O. Box 1625 Hartford, Conn. 06141 Idaho Falls, ID 83415 Robert B. Borsum Vicki Bier Nuclear Power Division Dept. of Industrial Engineering B & W Nuclear Tech University of Wisconsin-Madison 1700 Rockville Pike 1513 University Avenue, Room 389 Suite 525 Wisconsin, WI 53706 Rockville, MD 20852 Scott Bigelow Stephen Bault S-CUBED Electrowatt Engineering Services 2501 Yale SE, Suite 300 (UK) Ltd.

Al=uquerque, NM 87106 Grandford House 16 Carfax, Horsham West. Sussex RH12 IUP Prof. Dr. Dr.-Ing. E. H. Adolf ENGLAND Birkhofer Gesellschaft fur Anlagen und Reaktorsicherheit (GRS) mbH Gary Boyd Forschungsgelande Safety & Reliability Optimization D-8046 Garching Services Federal Republic of Germany 9724 Kingston Pike, Suite 102 Knoxville, TN 37922 David Black American Electric Power Brookhaven National Laboratory (2) 1 Riverside Plaza Attn: Lev Neymotin Columbus, OH 43215 Arthur Tingle Building 130 Upton, NY 11973 Harold Blackman Idaho National Engineering Lab.

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Tom D. Brown A. L. Camp

Sandia National Laboratories Division 6412 Dept. 6413 MS: 0748 P.O. Box 5800 Sandia National Laboratories Albuquerque, NM 87185 Albuquerque, NM 87185-0748 Robert J. Budnitz John Forbes Campbel Future Resources Associates, Inc. HM Superintending Inspector 2039 Shattuck Avenue, Suite 402 Health & Safety Executive Berkeley, CA 94704 St. Peter's House Balliol Road Bootle L20 31Z Gary Burdick UNITED KINGDOM USNRC-RES/SAIB MS: T-10F13 Leonel Canelas New University of Lisbon Arthur Buslik Quinta de Torre USNRC-RES/PRAB 2825 Monte de Caparica MS: T-9F31 PORTUGAL Edward Butcher Harold Careway USNRC-NRR/SPSB General Electric Co., M/C 754 MS: 0-10E4 175 Curtner Ave.

San Jose, CA 95129 Technical Library B&W Nuclear Service Co D. D. Carlson P. 0. Box 10935 Division 6411 Lynchburg, VA 24506 Sandia National Laboratories Albuquerque, NM 87185 Stefaan Caeymaex Safety & Systems Section Jose E. De Carlos

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Mike Check S. Daggupaty NUS Environment Canada 910 Clopper Road 4905 Dufferin Street Gaithersburg, MD 20878 Downsview Ontario, M3H ST4 CANADA Nilesh Chokshi USNRC-RES/SSEB MS: T-lOLl Louise Dahlerup Inspectorate of Nuclear Inst.

Danish Civil Defense &

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NRC FORM 335 U.S. NUCLEAR REGULATORY COMMISSION 1. REPORT NUMBER

{2-891 (Assigned by NRC, Add Vol,, Supp,, Rev,,

NRCM 1102, and Addendum Numbers, If any.)

3201, 3202 BIBLIOGRAPHIC DATA* SHEET (See instructions on the reverse)

NUREG/CR-6144 E AND SUBTITLE BNL-NUREG-52399 Evaluation of Potential Severe Accidents During Low Vol. 4 Power and Shutdown Operations at Surry, Unit 1: 3. DATE REPORT PUBLISHED MONTH YEAR Analysis of Core Damage Frequency from Internal Floods During Mid-loop Operations July 1994 4, FIN OR GRANT NUMBER L1922

5. AUTHOR (S) 6. TYPE OF REPORT P. Kohut

7. PER JOD COVERED /Inclusive Dates/

8. PER FORM) NG ORGANIZATION - NAME AND ADDRESS /If NRC, provide Division, Office or Region, U.S. Nuclear Regulatory Commission, and mailing address; if contractor, provide name and mailing address.)

Brookhaven National Laboratory Upton, NY 11973 9, SPONSOR I NG ORGANIZATION - NAME AND ADDRESS /If NRC, type "Same as above"; if contractor, provide NRC Division, Office or Region, U.S. Nuclear Regulatory Commission, and mailing address.)*

Division of Safety Issue Resolution Office of Nuclear Regulatory Research U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 PLEMENTARY NOTES

11. ABSTRACT /200 words or less)

During 1989, the Nuclear Regulatory Commission (NRC) initiated an extensive program to carefully examine the potential risks during low power and shutdown operations. The program includes two parallel projects being performed by Brookhaven National Laboratory (BNL) and Sandia National Laboratories (SNL). Two plants, Surry (pressurized water reactor) and Grand Gulf (boiling water reactor), were selected as the plants to be studied. Th*e objectives of the program are to assess the risks of severe accidents initiated during plant operational states other than full power operation and to compare the estimated core damage frequencies, important accident sequences and other qualitative and quantitative results with those accidents initiated during full power operation as assessed in NUREG-1150. The objective of this report is to document the approach utilized in the Surry plant and discuss the results obtained. A parallel report for the Grand Gulf plant is prepared by SNL. This study shows that the core-damage frequency during mid-loop operation at the Surry plant is comparable to that of power operation. We recognize that there is very large uncertainty in the human error probabilities in this study. This study identified that only a few procedures are available for mitigating accidents that may occur during shutdown.

Procedures written specifically for shutdown accidents would be useful.

12, KEY WORDS/DESCR f PTO RS (List words or phrases that will assist researchers in locating the report.) 13. AVAILABILITY STATEMENT Surry-1 Reactor-Reactor Shutdown; Surry-1 Reactor-Risk Assessment; Unlimited Surry-2 Reactor-Reactor Shutdown; Surry-2 Reactor-Risk Assessment; 14. SECURITY CLASSIFICATION Failure Mode Analysis, Reactor Accidents, Reactor Core Disruption, (This Page)

Reactor Start-up, RHR Systems, Systems Analysis, Thermodynamics, Unclassified

/This Report)

Sandia National Laboratories Unclassified

15. NUMBER OF PAGES

16. PRICE NRC FORM 335 {2-891

Printed on recycled paper Federal Recycling Program

ML18151A168

Text

SUMMARY

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