Text

Rev 1 of Plant,Unit 2:Probabilistic Safety Assessment W/ Unit 3 Operating
	ML18038B928
Person / Time
Site:	Browns Ferry
Issue date:	05/31/1996
From:	Dante Johnson, Loh W, Rodgers S; PLG, INC. (FORMERLY PICKARD, LOWE & GARRICK, INC.)
To:	;
Shared Package
ML18038B926	List: ML18038B925; ML18038B927; ML18038B928; ML18038B929;
References
	PLG-1112, PLG-1112-R01, PLG-1112-R1, NUDOCS 9708130378
	Download: ML18038B928 (147)
	v • d • e

PLG-1112 BROWNS FERRY NUCLEARPLANT UNIT 2 PROBABILISTICSAFETY ASSESSMENT WITHUNIT 3 OPERATING by David H. Johnson, Sc.D.

Shawn R. Rodgers Wee Tee Loh, Ph.D.

Andrew A. Dykes, Ph.D.

Stephen R. Melvin Grant A. Tinsley Leiming Xing, Ph.D.

Thomas J. Mikschl Prepared for TENNESSEE VALLEYAUTHORITY Decatur, Alabama May 1996 Revision 1

9708i$ 0378 97080b PDR ADGCK 050002b0 P

PDR ENGINEERS

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APPLIED SCIENTISTS

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MANAGEMENTCONSULTANTS

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CONTENTS LIST OF TABLES AND FIGURES v

1 INTRODUCTION 1.1 Objective and Scope........................

1.1.1 Summary of Results 1.1.2 Discussion of the Top 10 Sequences 1.1.3 Functional Failure Group Contributions to CDF 1.1.4 Initiating Event Group Contribution to CDF 1.1.5 Important Operator Actions..............

1.1.6 Important Systems....................

1.2 Process Followed to Develop Current Model 1.3

$-MMatrix..............................

1-1 1-2 1-2 1-4 1-5 1-5 1-5 1-6 1-6 2

JUSTIFICATION FOR EXCLUSION OF CONTROL ROOM HVAC PSA MODEL 2..1 Background.................... ~..................

2.2 Description of Multi-UnitPRA HVAC Analysis

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2..3 Conclusions FROM 2-1 2-1 2-1 2-2 0

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3 PLANT CONFIGURATION................

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3.1 Description of Plant Configuration............................

3.2 Evaluation of Impact on Shared Systems and Structures 3.2.1 Electric Power System..... ~..................... ~....

3.2.2 Control and Service Air System 3.2.3 Raw Cooling Water System 3.2.4 Turbine Building............. ~.....................

3.2.5 Reactor Building Closed Cooling Water System..............

3.2.6 Reactor Building (Secondary Containment System) 3.2.7 Condenser Circulating Water System.....................

3.2.8 Pumping Station (Intake Building).......................

3.2.9 Control Rod Drive Hydraulic System.....................

3.2.10 RHR Cross-Connection and Standby Coolant Supply System.....

3.2.11 Residual Heat Removal Service Water System........ ~......

3.2.12 Emergency Equipment Cooling Water System...............

3.2.13 Fire Protection System...............................

3.2.14 Reactor Building and Control Bay Ventilation and Cooling Systems 3.3 System Success Criteria 3-1 3-1 3-1 3-2 3-2 3-2 3-3 3-3 3-3 3-3 3-4 3-4 3-4 3-4 3-4 3-5 3-5 3-5 4

MODIFICATIONSMADETO PREVIOUS PRA MODELS...............

4.1 Initiating Events 4.1.1 Refinement of Model for Floods in the Turbine Building 4.1.2 Loss of Offsite Power 4.1.3 Loss of Reactor Building Closed Cooling Water System...........

4-1 4-1 4-1 4-2 4-3

CONTENTS continued 4.1.4 Loss of Plant Air 4.1.5 Floods in the Intake Pumping Station.......................

4.2 Systems Analyses and Event Model 4.2.1 Modifications in Modeling of Battery Board Availability..........

4.2.2 Changes in the Model for Raw Cooling Water.................

4.2.3 Consideration of the Diesel-Driven Fire Pump to Provide Vessel Level Control 4.2.4 Control Rod Drive Hydraulic System...... ~................

4.2.5 Role of RBCCW Pump and Heat Exchanger 1C 4.2.6 Use of Unit 3 Diesel Generators to Support Unit2..............

4.2.7 Long-Term Operation of HPCI or RCIC... ~.................

4.2.8 Use of Unit 1 Division II RHR Pumps to Support Unit 2 and Use of Unit 3 Division I Pumps to Support Unit2.... ~.............

4.2.9 Transfer of Power at the 480V Shutdown Boards 2A and 2B; 250V RMOV Boards 2A and 2B.....,....... ~................

4.2.10 RHRSW and EECW Requirements for Two-Unit Operation 4.2.11 Recovery of BOP Equipment following Selected Initiating Events 4.2.12 Local Operation of the Hardened Wetwell Vent................

4.2.13 Operation of 2-Inch Primary Containment Vent Lines in Accordance with Emergency Operating Instructions......................

4.2.14 Other Model Modifications............. ~................

4.3 Operator Actions...............................

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4 3 4 3 4-3 4 3 4-4 4 5 4 5 45 4-6 4-6 4-6 4-6 4-6 47 4-8 4-8 4-8 4-9 REFERENCES

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APPENDIX A. BROWNS FERRY UNIT 2 PSA UNCERTAINTYANALYSIS ~ -

~. A-1 APPENDIX B. LISTING OF TOP 100 SEQUENCES......................

B-1 APPENDIX C. SPLIT FRACTION IMPORTANCE MEASURES.......

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APPENDIX D. P-M MATRIX......................................

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LIST OF TABLES 1-1 Contributions of Functional Failure Groups to CDF..................

1-2 Contribution to CDF by Initiating Event Group...'..................

1-3 Ten Most Important Operator Actions Failures Contributing to Core Damage 1-4 PSA Importance of Individual BFN Systems.......................

2-1 Impact of the Loss of HVAC Systems that Provide Cooling to Portions of the Control Bay.......................... ~..................

3-1 Shared Systems and Structures Associated with Unit 2 and Impacted by the Return of Additional Units to Service 3-2'omparison of Equipment Status in the Different Plant Configurations.....

3-3 Summary of Potential Impact on Systems and Structures Associated with Unit 3-4 Success Criteria for Plant Configuration Under Consideration...... ~....

4-1 Screening of Turbine Building Flooding Events 2

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3 7 3-9 3-10 4-12 LIST OF FIGURES l-l Probability Distribution of Browns.Ferry Unit 2 Core Damage Frequency......

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1. INTRODUCTIOW 1.1 OBJECTIVE AND SCOPE This report presents the results of an update to the Browns Ferry Unit 2 Probabilistic Safety Assessment (PSA) to reflect the shared mission of some components,

systems, and structures at the plant.

For this analysis, Unit 1 is assumed to remain in extended layup with no fuel in its core.

Also, Unit 3 is modeled in this analysis as having returned to service; specifically, Unit 3 is assumed to be either operating at power or in an outage.

These assumptions reflect the current operational configuration of the Browns Ferry Nuclear Plant (BFN).

This update builds on previous models that considered other plant configurations.

The Individual Plant Evaluation {IPE) (Reference

1) examined the three unit BFN site under the assumption that only Unit 2 was initially at power, with Units 1 and 3 in layup.

Consequently, Units 1 and 3 equipment permitted by plant design and plant status to support Unit 2 would have no other functional requirements.

The Multi-UnitPRA (Reference 2) examined initiating events at Unit 2 with all three units initiallyat power.

The current model, with Unit 2 initiallyoperating and Unit 3 in service, reflects a condition that is bounded by the two site configurations that were previously analyzed.

That is to say, the individual success criteria for plant systems in the current model are both no more stringent than the corresponding criteria appropriate for the Multi-UnitPRA and at least as restrictive as the corresponding criteria in the IPE.

In a like manner, the availability of specific shared equipment to support Unit 2 falls between the two extremes represented by the Multi-Unit PRA and the IPE.

This report documents the results of the first revision to an earlier model (Reference 3).

As such, the model discussed is this report contains a number of minor refinements made to the Revision 0 model.

None of the top 10 core damage scenarios differ from those reported in Reference 3.

This quantification considers the response of Unit 2 to initiating events while it is operating at full power, considering that Unit 3 may also be at full power and remain at power, may have also been affected by the same initiating event, or has been previously shut down.

The model considers the core damage frequency (CDF) due to internal events as well as internal flooding. The systems and components available. for use in bringing Unit 2 to a safe shutdown condition considers requirements of common systems to support Unit 3 under the above three circumstances as well as potential interactions and dependencies.

In addition to reflecting the latest operational configuration, the plant model has been revised to reflect selected functional capabilities of equipment.and systems that were not taken credit for in previous quantiflications.

Discussion of changes to the model is contained in Section 4.

This report summarizes only those changes to the plant model made to reflect the specific plant configuration described above.

Details of many of the underlying models can be found in the previous PRA reports (References 1, 2, and 4).

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SUMMARY

OF RESULTS

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The overall results indicate that the mean CDF for Unit 2 for the initiating events considered in this analysis is 5.39E-06 per year.

A single parameter, such as the mean value, however, does not tell the full story about the CDF. A probabilistic distribution was determined for the CDF. That distribution is given in Figure 1-1.

Besides the mean value, other characteristics of'this distribution are the 5th percentile (9.02E-07 per year), the 50th percentile (2.64E-06 per year), and the 95th percentile (1.48E-05 per year).

These percentiles permit the following interpretation of the CDF:

We are as confident that "the" CDF at Unit 2 is above 2.64E-06 per year as we are that it is below 2.64E-06.

Furthermore, the 5th and 95th percentiles allow us to claim that we are 90% confident that "the" CDF is between 9.02E-07 and 1.48E-05 per year.

The overall CDF is quite small.

Based on the mean CDF, the analysis suggests that the current procedures, practices, and equipment performance at Unit 2 would result in one core damage event, on average, approximately every 185,000 years.

The interval between expected core damage events is quite large compared to the plant lifetime, indicative of a well operated plant.

1.1.2 DISCUSSION OF THE TOP 10 SEQUENCES A summary description of the top 100 sequences is presented in Appendix B.

The sequences that individually are the 10 most frequent core damage sequences are described in this section.

Note that the frequencies of the individual sequences are quite small, with none larger than 1.01E-07 per year.

The highest frequency sequence is anticipated to occur on the order of once every 10,000,000 years.

Perspective on these small frequencies is necessary when interpreting the sequences.

When one sees, for example in the first sequence, a reference to the failure of the operator to control low pressure injection during an anticipated transient with scram (ATWS) given a stuck-open relief valve, it is easy to miss the fact that the model also indicates that under those circumstances, the operator will be successful in performing the necessary actions under these stressful and unusual conditions 11 out of 12 times.

The first sequence is initiated by a turbine trip; failure of the control rods to insert into the core; successful operation of the standby liquid control and initial level control by the high pressure injection systems; failure of one relief valve to reseat following initiallylifting to limit pressure; and failure to control the injection of low pressure systems once pressure has decayed.

Core damage is assumed to occur due to the large inflow of low pressure water diluting or displacing the borated vessel inventory resulting in an unanalyzed condition that may lead to recriticality. The mean frequency of this sequence is 1.01E-07 per year.

The second and third sequences are related.

Both are initiated by a turbine trip followed by failure of the control rods to insert into the core and failure of boron to inject to control reactivity.

In sequence two, boron injection failure is due to operator failure to initiate the standby liquid control system.

Sequence three is due to the standby liquid control system being unavailable due to hardware failures, or a combination of hardware failures and test or maintenance.

The mean frequencies of the second and third sequences are 7.52E-08 and 7.25E-08 per year, respectively.

Sequence four is a blackout of Units 1 and 2.

The sequence initiator is loss of offsite power (both the 500-kV and 161-kV grids) followed by failure of diesel generators A, B, C, and D to supply power.

The high pressure coolant injection and the reactor core isolation cooling systems are initially available to maintain vessel level control, but core damage eventually occurs since power is not recovered and no means of removing decay heat is established.

The mean frequency of this sequence is 6.81E-08 per year.

Sequence five is a transient with the loss of the ability to maintain the core covered.

This sequence is initiated by the loss of the raw cooling water system.

The high pressure coolant injection and reactor core isolation cooling systems are unavailable to inject water into the vessel.

The initiator prevents the control rod drive hydraulic system from being operable and the operator fails to depressurize the vessel in a timely manner to allow low pressure injection systems to maintain core coverage.

The mean frequency of this sequence is 5.98E-08 per year.

The sixth sequence is quite similar to the second sequence:

a transient, this time the closure of all main steam isolation valves, followed by failure of the control rods to insert and failure to initiate the standby liquid control system.

The mean'frequency of this sequence is 5.47E-08 per year.

The seventh sequence is similar to the fifth sequence.

In the seventh sequence, the sequence is initiated by the closure of all main steam isolation valves, successful scram, but failure of the high pressure injection system, the reactor core isolation cooling system, and the control rod drive hydraulic system, and failure to depressurize the vessel.

The initiator "MSIV Closure" occurs more frequently than "Loss of Raw Cooling Water;" the primary difference being how the control rod drive hydraulic system fails. In the fifth sequence, it is failed due to loss of support as a result of the initiating event, and in the seventh sequence, it is unavailable due to hardware failure or maintenance activities (both pumps 2A'and 1B are required for success).

The mean frequency of this sequence is 4.83E-08 per year.

The eighth sequence is also similar to the fifth sequence.

The initiator, loss of offsite power, like the loss of raw cooling water, defeats the operation of the control rod drive hydraulic system.

Core damage occurs following failure of the high pressure coolant injection system and the reactor core isolation cooling system, and failure to depressurize the vessel.

The mean frequency of this sequence is 4.66E-08 per year.

The ninth sequence is actually the sum of several individual sequences that were individually analyzed.

Each of these sequences have the characteristic that a system designed for low

pr'essure is inadvertently subjected to full reactor pressure resulting in an unisolated loss of coolant accident (LOCA). Since the break discharges into the reactor building, the subsequent degraded environment (high temperature and high humidity being the initial characteristics) is assumed to result in the failure of equipment that potentially could mitigate the accident.

The mean frequency of this family of sequences is 4.63E-08 per year.

The tenth sequence leads to core damage due to the loss of ability to remove decay heat.. The sequence is initiated by the failure of the raw cooling water system, followed by successful initial operation of the high pressure coolant injection and the reactor core isolation cooling systems, failure of a relief valve to reseat after initially lifting to limit pressure in the primary system, and failure to establish suppression pool cooling.

The specific reason for failure to establish suppression pool cooling is failure of the operator team to perform the required actions.

Core damage is assumed to be the final result; alternate means of removing decay heat are conservatively not credited since. the root cause of the decay heat removal failure is due to operator failure, which may involve failure of diagnosis, rather than mechanical failures.

The mean frequency of this sequence is 4.50E-08 per year.

A summary description of the top 100 sequences is presented in Appendix B.

1.1.3 FUNCTIONALFAILURE GROUP CONTRIBUTIONS TO CDF Table 1-1 presents the results of recasting the core damage frequencies into seven functional categories.

Consideration of the functional categories provides some insights into the nature of the results.

It should be noted that the functional categories are not mutually exclusive; individual sequences can be assigned to more than one functional category.

As can be seen, nearly 41% of the CDF is due to sequences involving failure to control reactivity.

Eighteen percent of the CDF is from sequences that can be characterized by the loss of the ability to remove decay heat.

Transients with the reactor vessel at high pressure represent 12.9% of the total core damage frequency.

The transients with the reactor at high pressure can be characterized typically as an initiating event involving the loss of feedvtater, the unavailability of both the high pressure coolant injection.and the reactor core isolation cooling systems, and the failure to manually depressurize the vessel to allow low pressure systems to maintain level control.

Transients followed by a loss ofvital DC power contribute 4.8% of the total core damage frequency.

This group is defined as any transient followed by the loss of battery board 1, 2, or 3.

For Unit 2, battery boards 2 and 3 are of particular interest.

Many sequences assigned to this group involve a failure of both battery boards 2 and 3, thus disabling high pressure coolant injection (HPCI) and reactor core isolation cooling (RCIC).

Sequences involving failure of battery boards 2 and 3 constitute 2.8% (1.49E-07 per year) of the total core damage frequency.

A typical sequence in this group is a transient that involves the loss of normal heat sink, such as closure of all main steam isolation valves, followed by failure of DC power resulting in the inoperability of HPCI, RCIC, and the ability to remove decay heat.

Two station blackout accident sequence groups are defined.

The first such functional category (7.4% of the total CDF) is due to the unavailability of AC power in the Unit I/Unit 2 portion of the plant.

Blackout in this case is defined to be the loss of offsite power followed by

failure of diesel generators A, B, C, and D. A smaller contribution (4.2% of the total CDF) is due to total station blackout (failure of offsite power as well as all eight diesel generators at the site).

O f A small contribution to

. 1 can be attributed to sequences involving degraded states of the emergency equipment cooling water system.

1.1.4 INITIATINGEVENT GROUP CONTRIBUTION TO CDF Table 1-2 summarizes the results at the initiating event group level.

The performance of a PSA begins with the identification of a comprehensive set of scenario initiators, often called initiating events or initiators.

Table 1-2 also summarizes the CDF contribution due to initiating event categories as well as the individual initiators.

1.1.5 IMPORTANTOPERATOR ACTIONS Table 1-3 identifies the 10 most "important" operator actions that were included in the model for the response of the plant and the operators to the entire set of initiating events.

The importance measures were derived from the split fraction importance measures (the "fraction importance") reported in the first numerical column in Appendix C. Split fraction importance is defined as the fraction of all core damage scenarios that include failure of the specific split fraction. This fraction can be determined by dividing the sum of the frequencies of scenarios containing the failed split fraction by the sum of the frequencies of all core damage frequencies.

Note that 2 of the 10 entries in Table 1-3 required adjusting.

These split fractions, RVD22 and U12, contain both hardware and operator action elements.

To eliminate the hardware portion of the fractional importance for RVD22 (0.134 from Appendix C), it was multiplied by the fraction of the split fraction value that is due to operator error (0.86).

In a similar manner, the fractional importance of U12 from Appendix C (0.016) was multiplied by 0.58.

It should be noted that the split fraction CRD4, which contains both hardware and operator

elements, has a fractional importance from 'Appendix C of 0.065.

However, the portion due to operator error is quite small (0.025).

Consequently, it does not appear in the list of the top 10 actions.

1.1.6 IMPORTANT SYSTEMS Table 1-4 identifies the importance of selected plant systems.

The top events that represent hardware and that comprise the mechanical support, signal, and frontline event trees were assigned to appropriate system groups.

Top events that represented operator actions were not assigned to a system group.

Two electrical groups were defined:

one for the diesel generators and one for the battery boards 1, 2, and 3.

These groups were used to determine importance measures.

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t The importance measures were determined from the information summarized in Appendix C by summing the importance of all split fractions (other than the one corresponding "guaranteed failure") associated with a given system.

1.2 PROCESS FOLLOWED TO DEVELOP CURRENT MODEL The model develope'd in this analysis used the Rev.

1 Interim Order P2 {I.O. P2) version of the Browns Ferry Unit 2 PRA (Reference 4) as a starting point. Information developed as part of the Multi-UnitPRA (Reference 2) was utilized in the model development.

The plant configuration being analyzed (Unit 1 in layup, Unit 2 initially at power, and Unit 3 returned to service) was scrutinized to determine which constituent models, those associated with the Rev.

1 1.0. P2 PRA or those associated with the Multi-UnitPRA, were more appropriate starting points.

The process of scrutinizing the plant configuration is summarized in Section 3.

Advantage was taken of the opportunity to make specific model elements more realistic and to make corrections.

These modeling changes are summarized in Section 4.

Where appropriate, updates to the system notebooks were performed.

1.3 ~MM YRIX A convenient way to summarize the results of a PSA is to construct a table that shows how each of the initiating events map to the plant damage states considered in the analysis. Ifthe initiating events are thought of as a vector {"$"), then the plant model, event trees, and fault trees could be represented by a transformation matrix ("M")that relates the initiators to the plant damage states.

$-M would then display the relationship of the initiators to the plant damage states.

The $-M matrix for Unit 2 is presented in Appendix D of this report.

Table 1-1. Contributions of Functional Failure Groups to CDF ATWS Accident Sequence Group Mean CDF*

(per Year) 2.19E-06 Percentage of Total*

40.9 Loss of Residual Heat Removal Transient with Reactor Vessel at High Pressure Blackout of Units 1 and 2 Transient followed by Loss of Vital DC Power Station Blackout Degraded Emergency Equipment Cooling Water 9.59E-07 6.92E-07 3.94E-07 2.57E-07 2.26E-07 2.14E-08 17.9 12.9 7.4 4.8

~The mean CDF is determined by examining the dominant sequence file. The sequences in the dominant sequence file represent in excess of 99% of the total CDF and form a convenient database for risk management applications.

The accident sequence groups are defined by specifying success or failure combinations of top events or split fractions.

For example, the "ATWS" accident sequence group is defined as all sequences with the Top Event "RPS" failed.

Since the dominate sequence file represents less than 100% of the total CDF, the "percentage of total" for each accident sequence group is determined by dividing the mean CDF for that group by the total CDF represented by the dominant sequence file. In the current model, the total CDF represented by the dominant sequence file is 5.36E-06 (per year).

For the ATWS accident sequence group, for example, the "percentage of total" is calculated as:

2.19E-06

5.36E-06 = 40.9%

Table 1-2 (Page 1 of 2). Contribution to CDF by Initiating Event Group Initiating Event Group Transients with Reactor not Isolated Loss of Feedwater Turbine Trip Inadvertent Scram Feedwater Rampup Events Requiring the Reactor to Scram Partial Los's of Feedwater Loss of All Condensate Partial Loss of All Condensate Loss of Offsite Power Transients with Reactor Isolated Closure of All Main Steam Isolation Valves Loss of Condenser Vacuum Turbine Trip without Bypass

. Loss of the 500-kV Grid to Unit 2 Loss of the 500-kV Grid to the Station Pressure Regulator Failure - Fails Open Break Outside of Containment Support System Failure Loss of Raw Cooling Water Loss of Plant Control Air Loss of IB'cC Bus 2A Loss of INC Bus 2B Loss of Unit Preferred Power Loss of Reactor Building Closed Cooling Water System Failure of Lower Instrument Tap IA Failure of Lower Instrument Tap IIA Failure of Lower Instrument Tap IB Failure of Lower Instrument Tap IIB Failure of Upper Instrument Tap I Failure of Upper Instrument Tap II Mean CDF (per Year) 1.58E-06 2.88E-07 6.99E-07 8.47E-08 1.07E-07 1.15E-07 1 40E-07 5.23E-08 9.48E-08 1.35E-06 1.04E-06 4.75E-07 2.35E-07 2.31E-07 3.55E-08 3.48E-08 3.07E-08 1.42E-09 7.03E-D7 5.38E-07 2.30E-08 3.08E-09 3.09E-09 3.75E-08 9.04E-08 1.91E-09

, 1.91E-09 1.99E-09 1.91E-09 2.23E-10 2.23E-10

Table 1-2 (Page 2 of 2). Contribution to CDF by Initiating Event Group Initiating Event Group Loss of Coolant Accidents Small LOCA Recirculation Discharge Line Break Recirculation Suction Line Break Core Spray Line Break Other Large LOCA Medium LOCA Very Small LOCA Excessive LOCA Stuck-Open Relief Valves Inadvertent Opening of One Relief Valve Inadvertent Opening of Two Relief Valves Inadvertent Opening of Three or More Relief Valves Internal Floods Small Flood in the Turbine Building Large Flood in the Turbine Building Flood in the Pumping Station Flood Scenario 1 in the Reactor Building Flood Scenario 2 in the Reactor Building Flood Scenario 3C in the Reactor Building Flood Scenario 3S in the Reactor Building Mean CDF (per Year) 4.41E-07 7.20E-08 1.12E-07 2.66E-OS 7.77E-OS 3.16E-08 1.06E-07 5.80E-09 9.10E-09 1.34E-07 6.8SE-OS 8.77E-09 5.65E-OS 9.29E-08 1.93E-08 2.22E-08 1.15E-08 4.35E-09 3.86E-10 6.90E-10 3.45E-08 0

pc>

Interfacing System LOCAs Total CDF 4.63E-08 5.39E-06

(*:

Table 1-3. Ten Most'Important Operator Actions Failures Contributing to Core Damage Operator Action Manual Depressurization of the Reactor Vessel using the Safety Relief Valves Manual Control of Low Pressure Injection during ATWS Manual Alignment of Residual Heat Removal to Suppression Pool Cooling Manual Start of Standby Liquid Control Given ATWS and the Reactor Vessel Isolated Manual Start of Standby Liquid Control Given ATWS and the Reactor Vessel Not Isolated Prevention of Automatic Depressurization System during ATWS Alignment of Unit 1 Residual Heat Removal to Unit 2 via Crosstie Reactor Vessel Level Control Using Residual Heat Removal/Core Spray Manual Start of Residual Heat Removal/Core Spray Level Control during ATWS PSA Importance 0.114 0.109 0.056 0.037 0.012 0.009**

0.008 0.008 0.005 Surrogate

. Split Fraction RVD22 OLA1 OSP1 OSLI OSL2 OAD1 U12 OLP1 ORP2 OAL1

~The fractional importance of 0.134 from Appendix C has been multiplied by the fraction (0,86) of the split fraction value that is due to operator action.

<<The fractional importance of 0.016 from Appendix C has been multiplied by the fraction (0.58) of the split fraction value that is due to operator action.

O.

System PSA Importance*

Table 1-4.

PSA Importance of Individual BFN Systems 0

Reactor Protection System Diesel Generators High Pressure Coolant Injection System Residual Heat Removal System Reactor Core Isolation Cooling System Residual Heat Removal Service Water System Control Rod Drive System Standby Liquid Control System Shared Actuation Instrumentation 250V DC Battery Boards Main Steam System Including Turbine Trip Core Spray RBCCW Emergency Equipment Cooling Water System Condensate and Feedwater System Plant Air 0.41 0.21 0.18 0.18 0.16 0.15 0.09 0.07 0.05 0.05 0.04 0.02 0.01

The fraction of CDF with sequences in which the failures occur in the indicated system.

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10'0 10'REQUENCY 10'0'igure 1-1. Probability Distribution of Browns Ferry Unit 2 Core Damage Frequency hTVAW0047.DOC.OS/I 3/96 l2 PLG

2. JUSTIFICATION FOR EXCLUSION OF CONTROL ROOM HVAC FROM PSA MODEL

2.1 BACKGROUND

The reactor building and control bay ventilation and cooling systems were not explicitly included in the IPE or Rev.

1 1.0. 02 PRA models (References 1, 2, and 4, respectively).

The IPE did include a quantitative evaluation for the upper bound of the impact on the CDF of Unit 2 following failure of the shutdown board room heating, ventilating, and air conditioning (HVAC) or control bay ventilation and cooling systems.

Failure of the shutdown board room cooling was shown not to lead to failure of components in the affected rooms.

Failure of control bay cooling was shown to have a small impact on CDF.

According to available information, the impact of the'reactor building HVAC does not lead to system failure and thus was determined not to require modeling.

However, for the Multi-UnitPRA, the control bay ventilation was explicitly added to the PRA model in order to quantitatively measure the risk significance of the control bay HVAC system.

The Multi-UnitPRA considered the control bay HVAC as both an explicit support system and a potential initiator category.

2.2 DESCRIPTION

OF MULTI-UNITPRA HVAC ANALYSIS An HVAC event tree was developed that used available analyses to address the loss of room cooling to various portions of the control bay. A bounding analysis was conducted that indicated that the unrecovered loss of room cooling to the main (Unit 1/Unit 2) control room is very unlikely. Thus, the loss of cooling to the main control room was not explicitly represented in the event tree.

Loss of cooling at the Elevation 593'evel was determined to cause heat up to temperatures above the equipment qualifications temperatures for equipment in both reactor protection system (RPS) motor-generator set rooms as well as the unit preferred power (UPS) mo'tor-generator set room.

Loss of cooling on the Elevation 593'evel was explicitly assumed to result in failure of,the equipment in the RPS and UPS motor-generator set rooms.

Cooling of the relay room (adjacent to the main control room),

the Unit 2 auxiliary instrument room, and the battery board room were all represented by individual top events in the event tree.

Operator recovery actions (such as opening doors locally) were also represented by top events for the relay room and the Elevation 593'ooms.

'4 In addition, electric power at vent boards A and B and the availability of Unit 1/Unit 2 chilled water are represented by top events in the HYAC event tree.

The Multi-UnitPRA modeled the impact of the loss of the HVAC system in terms of both an initiating event and a support system failure. The HVAC analyses were assumed to be applicable to both single and multi-unit operations; i.e., the same support requirements were assumed for the HVAC system whether or not the transient was multi-unit or single-unit in

nature.

The initiating events represented by their frequency of occurrence and contribution to core damage are provided in Table 2-1.

In terms of support systems, only the independent failure of chilled water provided a measurable contribution to the plant CDF. The loss of chilled water top event has an importance calculated as 3.447E-04; i.e., the fraction of sequences containing the independent failure top event.

Consequently, the total contribution of the chilled water top event to the plant CDF is less than 10 per year.

2.3 CONCLUSION

S The impact of the loss of HVAC to the control bay was conservatively modeled in the Multi-UnitPRA and the contributions to core damage for each of the initiating events analyzed were determined to be less than 3.2E-09 as compared to a total mean CDF from all initiators of 2.78E-OS.

The only measurable contribution due to the loss of the HVAC support system resulted in a contribution of less than.10 to the mean CDF.

Consequently, excluding the HVAC event tree from the Unit 2 model is determined to have an insignificant impact on the CDF evaluation and therefore willnot be represented explicitly in the event tree model.

Table 2-1. Impact of the Loss of HVAC Systems that Provide Cooling to Portions of the Control Bay Description I. Loss of 593 ft level HVAC 2.

Loss of Auxiliary Instrument Room HVAC 3.

Loss of Battery Room HVAC 4.

Loss of Chilled Water 5.

Loss of Relay Room HVAC

Less than 1.0E-12.

Frequency (per Year) 8.91E-07 2.39E-03 1.06E-03 9.13E-07 7.01E-05 Total Core Damage Contribution 1.35E-12 2.93E-09 2.50E-10 1.54E-12 3.18E-09 PLG

3. PLANT CONFIGURATION

3.1 DESCRIPTION

OF PLANT CONFIGURATION The plant configuration under consideration is one in which Unit 2 is initially at power, Unit 3 returned to service (i.e., it is either initially operating or shut down), and Unit 1 remaining in extended layup. An assessment of the potential for multi-unit interactions at BFN was performed in the Multi-UnitPRA to determine the impact on shared systems or structures associated with Unit 2 by the return to service of Units 1 and 3.

Guidelines or criteria were developed and used in that study to identify systems or structures that are potentially impacted by multi-unit interactions.

Interactions of interest are those that have the potential to (1) impact the success criteria for an individual system or group of systems associated with Unit 2, (2) change the frequency of an initiating event considered in the Unit 2 PRA, (3) introduce an initiating event not previously considered, (4) introduce new or to alter dependencies among systems, or (5) otherwise effect the response of the plant to an initiating event. It was determined that 14 of the shared systems and,structures associated with Unit 2 are potentially impacted by the return of additional units to service, and Table 3-1 shows a list of these shared systems and structures.

The review of system configurations and structures for the plant configuration under consideration utilized the results of the evaluation of all shared systems and structures performed in the Multi-UnitPRA. This review is consistent with the review of the 14 systems and structures associated with Unit 2 that were determined to be potentially impacted by the return to service of additional units.

For this study, it is sufficient to review this list of shared systems and structures because the plant configuration modeled in the Multi-UnitPRA is bounding, and all of the shared systems and structures impacted by the return of Unit 3 to service would be a subset of the shared systems and structures impacted by the return of both Units 1 and 3 to service.

The control bay HVAC system has been shown to be risk insignificant and is not considered in depth in this review. A comparison of the equipment/system status in the various plant configurations (the one under consideration, and those modeled in the Rev.

1 I.O. ¹2 and Multi-UnitPRAs) is provided in Table 3-2.

The equipment/system status may be the same in the various plant configurations considered, but the success criteria and plant response involving the shared systems may be different as discussed in the section below.

3.2 EVALUATIONOF IMPACT ON SHARED SYSTEMS AND STRUCTURES The potential impact on the shared systems and structures associated with Unit 2 when Unit 3 is returned to service can be characterized as changes in the system success criteria, changes in the initiating event frequency, or changes in the plant model with respect to those in adopted in the Rev.

1 I.O. ¹2 PRA model.

Based on the discussion of the system configurations and shared structures, and the comparison of the equipment status in the various plant configurations, the impact on the shared systems and structures as Unit 3 is returned to service is presented below and a summary of the impact is given in Table 3-3.

0 3.2.1 ELECTRIC POWER SYSTEM The return to service (return to operation or shutdown with fuel present) of Unit 3 impacts the success criteria used in the Rev.

1 I.O. 02 PRA for the analysis of the availability of individual electrical boards as loads on boards are increased.

In addition, the availability of boards is impacted ifthey no longer are considered "dedicated" to Unit 2 service.

These considerations will impact the actions considered as "recovery" actions in this study, as reflected in Table 3-4.

The loss of two large generating stations within a relatively small time window has the potential of increasing the frequency of the loss of the electrical grid. The return to power operation of Unit 3 therefore increases the likelihood of the induced loss of offsite power for initiating events, such as loss of raw cooling water, that involve a mechanism that potentially couples the response of the individual units.

In addition, the nature of the plant response, as compared to the Rev.

1 I.O. 42 PRA, to the loss of offsite power will change due to the role of other shared systems, such as residual heat removal service water (RHRSW) or emergency equipment cooling water (EECW).

It was concluded that the reanalysis of portions of the electric power system was required including the assessment of the availability of individual,electrical boards as well as the impact on the frequency of the loss of offsite power.

Modifications to modeling the battery

. board and diesel generators availability are discussed in Sections 4.2.1 and 4.2.14, respectively.

Changes to the frequency of loss of offsite power initiating events is discussed in Section 4.1.2.

3.2.2 CONTROL AND SERVICE AIR SYSTEM The control air and service air systems are shared among the three units.

The return to service of Unit 3 willnot impact the system success criteria, but may impact the frequency of the Loss of Plant Air initiator.

It was concluded that the reexamination of the plant air system analysis was required and that reexamination included a review of the success criteria for the system, the assessment of the frequency of the Loss of Plant Air initiator, and the plant response modeled for that initiator.

The results of reexamining the frequency of the Loss of Plant Air initiator are given in Section 4.1.4.

3.2.3 RAW COOLING WATER SYSTEM The raw cooling water system serves all three units.

The return to service of Unit 3 impacts both the system success criteria as well as the frequency of the initiator Loss of Raw Cooling Water.

These changes are described in Section 4.2.2.

3.2.4 TURBINE BUILDING The turbine building is shared among the units.

Flooding events in the turbine building were explicitly addressed in the Rev.

1 I.O. 42 PRA.

As Unit 3 is returned to service, both the frequency and plant response to such flooding events were reassessed.

The results and their impact on the plant model are discussed in Section 4.1.1.

3.2.5 REACTOR BUILDINGCLOSED COOLING WATER SYSTEM The reactor building closed cooling water system {RBCCW) servicing Unit 3 is independent of the system that services Units 1 and 2. The return of Unit 3 to service willnot impact the success criteria for the RBCCW system as modeled in the Rev.

1 I.O. N2 PRA.

It was determined that the loss of RBCCW would result in the loss of support to the drywell air compressors, and would also impact the drywell coolers.

This additional impact warrants the loss of RBCCW as a specific initiator category.

The required changes are described in Section 4.1.3.

Changes required to the systems analysis are described in Section 4.2.S.

3.2.6 REACTOR BUILDING(SECONDARY CONTAINMENTSYSTEM)

The reactor building is shared among the three units and is divided into three reactor zones and a common refueling zone.

When Unit 3 is returned to service, an indirect interaction is created ifa severe incident (such as extensive core damage) were to occur in Unit 3. In such a case, the accessibility of the Unit 2 reactor building will be affected.

It was concluded that the operator actions associated with reactor building entry when a severe event on one unit or in the common refueling zone impacts the habitability of the other reactor zones willmost likely not be possible.

The model change implemented to reflect this dependency is discussed in Section 4.2.14.

3.2.7 CONDENSER CIRCULATINGWATER SYSTEM In the normal mode of operation, this system is unitized. In the shutdown mode, with all of the units down and with the reactors streaming to the condensers via the turbine bypass system, only a small amount of condenser circulating water (CCW) flow is required to maintain normal condenser vacuum.

The plant design provides circulating water interties so that only one CCW pump can provide condensing water to all shutdown units.

In the modeled plant configuration, with Unit 2 initially at power, the CCW interties are not considered.

'ailures in the CCW system could potentially lead to flooding of the turbine building. The frequency of such events is reevaluated in Section 4.1.1.

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3.2.S PUMPING STATION (INTAKEBUILDING)

The RHR service water pumps and the emergency equipment cooling wate< pumps are located in four compartments of the pumping station.

As Unit 3 comes on line, the frequency and plant response to such flooding events as modeled in the Rev.

1 I.O. 42 PRA required reevaluation.

The reassessment of the frequency of and plant response to flooding of one of these compartments with Unit 3 returned to service is addressed in Section 4.1.5.

3.2.9 CONTROL ROD DRIVE HYDRAULICSYSTEM A common control rod drive (CRD) hydraulic system pump is shared by Units 1 and 2.

In the Rev.

1 I.O. 02 PRA, credit was taken for that pump as ifit were assigned solely to Unit 2. As Unit 3 returns to service, the availability of that swing pump to service Unit 2 will not be impacted.

As stated in Section 4.2.4, it was concluded that the Rev.

1 I.O. P2 PRA success criteria for the control rod drive hydraulic system analysis is valid when Unit 3 is returned to service.

3.2.10 RHR CROSS-CONNECTION AND STANDBYCOOLANT SUPPLY SYSTEM The use of the residual heat removal service water system for vessel injection via cross-connecting selected portions of the residual heat removal (RHR) systems in adjacent units is provided at the plant.

Credit for such alignments is taken in the Rev.

1 I.O. 82 PRA on a limited basis; that is, only from Unit 1 to Unit 2.

As Unit 3 is returned to service, cross-connecting Unit 3 to Unit 2 will also be available.

The availability of this alignment is dependent on the status of Unit 3.

It was concluded that updating the features represented by the standby coolant supply system features (as contained in the RHR system analysis) was required to reflect the condition of Unit 3 having returned to service.

This consideration is addressed in Section 4.2.8.

3.2.11 RESIDUAL HEAT REMOVALSERVICE WATER SYSTEM The RHRSW system is shared between the units and is explicitly modeled in the Rev.

1 I.O. 02 PRA.

As Unit 3 is returned to service, the success criteria associated with the RHRSW system change as additional loads are placed on the system.

The update of the success criteria for the RHRSW system is discussed in Section 4.2.10.

3.2.12 EMERGENCY EQUIPMENT COOLING WATER SYSTEM The EECW system is shared between the units and is explicitly modeled in the Rev, 1 I.O. P2 PRA. With Unit 3 returned to service, the success criteria associated with the EECW system was reviewed and determined not to change.

The success criteria for the EECW system is discussed in Section 4.2.10.

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The fire protection system is shared among the units. Of potential interest in the PSA is the one diesel-driven fire pump that could provide fiow to the vessel under station blackout conditions.

The return to service of Unit 3 would impact the.availability of this pump to

= serve Unit 2.

However, in the current model, the use of the fire protection system to provide flow to the vessel is not considered.

'.2.14 REACTOR BUILDINGAND CONTROL BAYVENTILATIONAND COOLING SYSTEMS A discussion of the impact of failure of these systems on core damage frequency is given in Section 2.

3.3 SYSTEM SUCCESS CRITERIA The results of the evaluation of the impact on the shared systems and structures associated with Unit 2 when Unit 3 is returned to service indicated that the system success criteria, the frequency of initiating event, or the plant model adopted in the Rev.

1 I.O. P2 PRA model required modification.

To establish the system success criteria for the plant configuration under consideration, those criteria adopted in the Rev.

1 I.O. 02 and Multi-UnitPRAs are first reviewed.

The success criteria for the shared systems in the plant configuration under consideration are then inferred from those adopted in the two PRAs.

The success criteria from the Rev.

1 I.O. P2 and Multi-UnitPRAs are either directly applicable to the plant configuration being considered, or they are conservative when used in the PSA model for the plant configuration under consideration.

Table 3-4 sumniarizes the success criteria for shared systems in the PSA model for the plant configuration being considered as well as the criteria used in the Rev.

1 I.O. 82 and Multi-UnitPRAs.

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Table 3-1.

Shared Systems and Structures Associated with Unit 2 and Impacted By the Return of Additional Units to Service Electric Power System*

Control and Service Air System Raw Cooling Water System Turbine Building and Radwaste Building Reactor Building Closed Cooling Water System Reactor Building (Secondary Containment System)

Condenser Circulating Water System Pumping Station (Intake Building)

Control Rod Drive Hydraulic System RHR Cross-Connection and Standby Coolant Supply System

. Residual Heat Removal Service Water System Emergency Equipment Cooling Water System Fire Protection System Reactor Building and Control Bay Ventilation and Cooling Systems

~includes offsite power system (switchyard, station service transformers, and normal auxiliary power switchboards), plant preferred and nonpreferred AC system, auxiliary DC power supply and distribution system, 250V DC power supply system, and standby AC power system.

Table 3-2 (Page 1 of 2). Comparison of Equipment Status in the Different Plant Configurations System Electric Power AC Power DC Posvcr Diesel Generators Control and Service Air Raw Cooling Water Turbine Building and Radwastc Building Reactor Building Closed Cooling Water Reactor Building (Secondary Containment System)

Condenser Circulating Water Equipment Status in Unit 2 PRA Switchgear, buses, and boards are nominally available to power all equipment associated with Units I, 2, and 3. Unit 3 boards are available to serve Unit 2 loads by crossticing the boards.

Boards arc nominally available to support all equipment associated with Units I, 2, and 3.

Unit 3 boards are available to Unit 2 via crossticing the boards.

Alleight diesel generators available.

Two comprcssors arc fully loaded, with the other two compressors running but unloaded or on standby.

Although interconnected, thc portion of the system that serves Unit 3 is independent ofthat portion that serves Units I and 2.

Buildings shared among all three units.

Unit 2 RBCCW pumps 2A and 28 arc normally operating, and the common RBCCW pump IC is dedicated to Unit 2.

Building shared among all three units.

Three Unit 2 CCW pumps are initiallyoperating; pumps from other units in standby with interties betwccn the units.

Equipment Status In hfulti-Unit PRA Switchgear, buses, and boards are nomin'ally available to power all equipment associated with Units I, 2, and 3.

Sclectcd Unit 3 boards may bc available to serve Unit 2 loads since the loads on the affected Unit 3 boards arc increased and they are no longer considered "dedicated to Unit 2 service.

Similarly, selected Unit 2 boards may be available to serve Unit 3 loads.

Boards are normally available to support all equipment associated with Units I, 2, and 3.

Selected battery boards may bc available to serve Unit 2 loads since the loads on the affected Unit 3 boards are increased and they are no longer considcrcd "dedicated" to Unit 2 service.

Alleight diesel generators available.

Two comprcssors are fully loaded, with the other two compressors running but unloaded or on standby.

Although interconnected, the portion of the system that serves Unit 3 is independent ofthat portion that serves Units I and 2.

Buildings shared among all three units.

Unit 2 RBCCW pumps are normally operating, and the common RBCCW pump IC is available to Unit I, 2, or 3.

Building shared among all three units.

All nine ofthc CCW pumps arc initiallyoperating with thc intcrties between the units closed.

Equipment Status In the Plant Conliguration with Unit I Remaining in Layup Switchgear, buses, and boards arc normally available to power cquipinent associated with Units 2 and 3.

Selected Unit 3 boards may be available to serve Unit 2 loads since the loads on the affected Unit 3 boards are increased and they are no longer considered "dedicated to Unit 2 service.

Similarly, selected Unit 2 boards may b>>

available to serve Unit 3 loads.

Boards are normally available to support equipment associated with Units 2 and 3.

Selected battery boards may be available to serve Unit 2 loads since the loads on the aAcctcd Unit 3 boards are increased and they are no longer considered "dedicated" to Unit 2 service.

Alleight diesel generators availablc.

Two compressors are fully loaded, with the other two compressors running but unloaded or on standby.

The cntirc system is modeled with thc portion serving Unit 2 dependent on the portion serving Unit 3 and vice versa.

Buildings shared among'll three units.

Unit 2 RBCCW pumps are nomially operating, and thc common RBCCW pump IC is availablc to Unit I, 2, or 3.

Building shared among all three units.

The three Umt 2 CCW pumps arc mitially operating and the number of Unit 3 CCW pumps operating depends on the status of Unit 3. llie interties between thc units are closed.

Pumping Station (Intake Building)

The pumping station contains RIIRSW pumps and The pumping station contains RIIRSW pumps and thc EECW pumps that are shared among thc units.

the EECW pumps that are shared among the units.

Thc pumping station contains RIIRSW pumps and the EECW pumps that are shared among thc units.

Table 3-2 (Page 2 of 2). Comparison of Equipment Status in the Different Plant Configurations System Control Rod Drive Hydraulic RlIR Cross<onncction and Standby Coolant Supply Residual Heat Removal Service Water Emergency Equipment Cooling Water Equipment Status in Unit 2 PRA Unit 2 CRD pump 2A is normally running, and the common control CRD swing pump is dedicated to Unit 2.

Cross-connecting a selected portion of the RHR systems from Unit 2 to Unit I is available.

Four RHRSW pumps are dcsignatcd to provide RHR function, and four RHRSW pumps are swing pumps.

The latter can replace designated EECW pumps when their corresponding EECW pumps are taken off-line.

The EECW north and south header are each supplied by two RIIRSW pumps with one pump in

<<ach header normally running.

Equipment Status in Multi-Unit PRA Unit 2 CRD pump 2A is normally running, and the common control CRD swing pump is shared by Units I and 2.

Cross~nnecting between Units 2 and I, and between Units 2 and 3 are available.

Four RHRSW pumps arc designated to provide RHR function, and four RHRSW pumps are swing pumps.

Thc latter can replace designated EECW pumps when their corresponding EECW pumps arc taken off-line.

The EECW north and south header are each supplied by two RHRSW pumps with one pump in each header normally running.

Equipment Status in the Plant Conliguration with Unit I Remaining in leyup Unit 2 CRD pump 2A is normally running, and thc common control CRD swing pump is dedicated to Unit 2.

Cross~nnccting between Units 2 and I is maintained available, and crosstieing between Units 2 and 3 is dependent on thc status of Unit 3.

Four RHRSW pumps are designated to provide RHR function, and four RHRSW pumps are saving pumps.

The latter can replace designated EECW pumps when their corresponding EECW pumps arc taken off-line.

Thc EECW north and south header are each supplied by two RIIRSW pumps with onc pump in.

each header normally running.

Table 3-3.

Summary of Potential Impact on Systems and Structures Associated ivith Unit 2 System or Structure Electric Power System Control and Service Air System Raw Cooling Water System Turbine Building'nd Radwaste Building Reactor Building Closed Cooling'ater System Reactor Building (Secondary Containment System)"

Condenser Circulating Water System Pumping Station (Intake Building)

Control Rod Drive Hydraulic System RHR Cross-Connection and Standby Coolant Supply System Residual Heat Removal Service Water System Emergency Equipment Cooling Water System

'Impacts nature and frequency of turbine flood.

"May impact local manual operations in reactor building.

System Success Criteria or Systems Analysis X

Initiating Event Frequency Plant Model X

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System or Top Event Initiating Event Rev. 1 I.O. ¹2 PRA Success Criteria hiti-Unit PRA Success Criteria Table 3A (Page 2 of 4).

Success Criteria for Plant Configuration Under Consideration Success Criteria for Units 2 and 3 with Unit 1 Remaining in Layup I

Impact on PSA Event Model for Units 2 and 3 with Unit 1 Remaining in Layup v >liable os

~ re Card 250V DC Battery Charger 28 Control and Service Air System Raw Cooling Water System Turbine Building Reactor Building Closed Cooling Water N/A Loss of Plant Air LRCW FLTB LRBCCW Remain available to support the loss of the normal charger fo'r battery board 1,

2, or 3. Only the recovery of battery board 2 or-3 was considered in the Rev.

1 I.O. ¹2 PRA.

Requires at least two of the four control air compressors to supply all three air receiver and the Unit 2 air dryer train.

This is conservative since per Design Criteria BFN-50-732, Rev. 2, January 31, 1991, the plant control air system requires one ofthe four compressors ifonly Unit 2 is in operation.

Two of six raw coohng water (RCW) normally operating pumps modeled as two of three Unit 1 or two of three Unit 2 normally operating pumps must be available.

Pump ID replaces a normally operating pump that is in maintenance.

N/A

'umps 2A and 2B and their associated heat exchangers must remain in service for 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

Pump 1C replaces a normally operating pump that is in maintenance.

Success criteria remains the same.

The charger unavailability will change.

i The success criterion for the system requires three comlIressors in operation when three units are in operation.

criteria is made:

tyro of three Unit 1 and two of three Unit 2 pumps must be available (two are required per operating unit). This is modeled as four of six RCV pumps be available.

Pump 1D is available to replace a Unit 2 pump in maintenance ifitself is not in maintenance or it is not being used to replace a Unit 1 pump in maintenance.

Unit 3 RCW is independent, and two of the five Unit 3 p success.

utnps were assumed for I

N/A ii f/

The success criteria remains the same.

tt The system analysis was changed to reflect ossible ali nment of pump 1C to P,g Unit l.

t The following assumption on the success Success criteria remains the same.

Ti>e charger unavailabihty willchange.

The success criterion for the system I

requires three compressors in operation when three units are in operation.

Any four pumps.

N/A The success criteria remains the samei Pump IC could support Unit 2 or 3.

The charger may be in use by Unit 3 in supporting maintenance.

Frequency of fiooding reevaluated.

See Section 4.1.1.

Same as Rev.

1 I.O. ¹2 PRA. The irutiating event LRBCCW was introduced in the Multi-UnitPRA and is considered in the current analysis.

The demands on the plant air system may increase as more units are at power.

The initiating event frequency is based on industry experience and does not change when applied to this plant configuration. A review of a recent plant modification to sectionalize units given a piping failure determined that the modification would not significantly impact the quantitative system analysis results.

Required changes to the system model and the initiating event frequency.

See Section 4.2.2.

ETVAQ40047a.DOC,04/06/96 3-1 1

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P System or Top Event Initiating Event Rev.

1 I.O. ¹2 PRA Success Criteria Multi-UnitPRA Su'ccess Criteria Table 3-4 (Page 3 of 4).

Success Criteria for Plant Configuration Under Consideration Success Criteria for Units 2 and 3 with Unit 1 Remaining in Layup AMSVEC APEA7UBB RG callable on i tore Card Impact on PSA Event Model Ape for Units 2 and 3 with Unit I Remaining in Layup Reactor Building (Secondary Containment)

N/A Isolate all three-reactor zones and the common refueling zorre.

events that may involve entry.

reactor building A new top event (ACM) to specify degraded scenarios on other unit(s) has been added representing a fiag for those The new top event (ACM) introduced in

.'he Multi-UnitPRA has been implemented in the current analysis to specify when a degraded scenario occurs on Unit 3, thus impacting the ability to enter the Unit 2 reactor building.

An accident in Unit 3 may impact the habitabihty of the Umt 2 reactor building. This would then limitthe capability of remote manual actions by operators in response to events at Unit 2.

Event tree structure, logic rules, as well as new operator assessment from Multi-UnitPRA are applicable to this plant configuration.

Pumping Station (Intake Building)

Control Rod Drive Hydraulic RHR Cross-Connection and Standby Coolant Supply FLPHI N/A N/A N/A The control rod drive hydraulic system is available for 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months to act as a source of vessel makeup for reactor level control.

Depending on the circumstances, either pump 2A is sufficient for makeup, or pumps 2A and IB ("enhanced" flow) must act together.

1.

Unit 1 RHR pumps 1B and 1D can be aligned to support Unit 2 suppression pool cooling.

2.

RHRSW pumps Dl and D2 are available to align to the Unit 2 RHR loop I header providing an alternate standby coolant supply.

N/A The success criteria reniains the same.

The system analysis was changed to reflect possible assigronent of pump 1B to Unit 2 In addition to Rev.

1 I.'O. ¹2 PRA success criteria, the following are available to support Unit 2:

1.

RHRSW pumps Bl and B2 are available to align to Unit 2 RHR loop II header providing additional standby coolant supply.

2.

Unit 3 RHR pump's 3A and 3C can be aligned to support Unit 2 suppression pool 'c'ooling.

il N/A The control rod drive hydraulic system is available for 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months to act as a source of vessel makeup for reactor level control.

Depending on the circumstances, either pump 2A is sufficient for makeup, or pumps 2A and 1B ("enhanced" flow) must act together.

In addition to Rev.

1 I.O. ¹2 PRA success criteria, the following are available to support Unit 2:

1.

RHRSW pumps Bl and B2 are available to align to Unit 2 RHR loop II header providing additional standby coolant supply.

2.

Unit 3 RHR pumps 3A and 3C can,'e aligned to support Unit 2 suppression pool cooling.

However, the availability of the Unit 3 RHR system is dependent on the status of Unit 3.

The plant model already considers that four different sets of pumps could be lost due to this initiator. The initiating event frequency considers the contribution by three units.

The model developed for the Rev.

1 I.O. ¹2 PRA is applicable.

Both Units 1 and 3 RHR pumps can be aligned to support Unit 2 suppression cooling and alternate injection. In addition, specific RHR service water pumps can be used to provide alternate standby coolant supply.

The model takes credit for RHRSW pumps Bl and B2 for Unit 2 standby coolant supply, and RHR pumps 3A and 3C for Unit 2 suppression pool cooling and alternate injection.

3-12

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'ystem or Top Event Initiating Event Rev. 1 I.O. 02 PRA Success Criteria Multi-UnitPRA Success Criteria Table 3-4 (Page 4 of 4).

Success Criteria for Plant Configuration Under Consideration

,T Success Criteria for Units 2 and 3 I with Unit 1 Remaining in Layup I

Impact on PSA Event Model

'or Units 2 and 3 with Unit I Remaining in Layup ion I'0 RHR Service Water Emergency Equipment Cooling Water N/A N/A At least one of the four RHR heat exchangers must be supplied with cooling water from an associated RHRSW pump for shutdown cooling.

For ATWS conditions, all four RHR heat exchangers with cooling water from the associated RHRSW pump are available for suppression pool cooling.

(The model developed requires all three RHR heat exchangers.)

Two of the four EECW pumps must operate for 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

The success criteria pe effected if Units 1 and 3 rem 'n operation and the diesel generato are not running The flow paths for are such that three ou required.

An alternate model to look at th s of RCW and ifRC acceptance criteria) h EECW pumps isa e

ee unit operation t of four pumps are criteria is for the uccessRI operation is available (meets en two of four ptable.

At least two RHR pumps supplying cooling water to the i4sociated heat exchangers (for transients only). For all other events, the success criteria is the same as the Rev.

1 I O. N2 PRA.

One pump per unit (not on same header) for non-ATWS conditions.

For ATWS'onditions, four RHR heat exchangers are required.

Two pumps not on same end of a header.

.Because the trains of RHRSW are modeled separately in the support tree, the systems analysis willnot change.

The event tree modeling accounts for the use of specific pumps by specific units (heat exchangers).

The event tree logic rules account for the RHRSW swing pumps to EECW.

Specific logic rules address the requirement for four pumps in ATWS scenarios.

>>th two umts fueled, the availabihty of RHRSW pumps to replace EECW pumps that require mamtenance willbe limited. The system model remains the same as the trains are modeled in four separate top events.

For two-unit shutdown scenarios (e.g., those initiated by LOSP), the new system success criteria can be implemented via the event tree logic rules.

The event tree logic rules account for the RHRSW swing pumps to EECW.

3-13

Table 4-1 (Page 2 of 2). Scrccning of Turbine Building Flooding Events Event Plant System/Component Plant Status Size Included in Initiating Event FLTB2 Applicable to Initiating Event FLTB Comment 58 93 Surry LaSalle. I and 2 Feedwater-Elbow of MFW Pump Suction Ruptured Circulating Water-Expansion Joint Between Pump and Discharge Valve During Trip At Power Large 2,000 gpm Yes No No No Insufficient inventory to impact RCW.

Flooding at the pumphouse will not cause a flood in the BFN turbine building and impact RCW.

94 Peach Bottom 3 Circulating Water-Water Box Vent Left Open At Power 6togflof Water in the Pump Room No No Insufficient flood water to impact RCW.

Flooding at the pumphouse will not cause a flood in the BFN turbine building.

5.

REFERENCES "Browns Ferry Nuclear Plant Unit 2 Probabilistic Risk Assessment Individual Plant Examination," Revision 0, R11 921007838, September 1992.

"Browns Ferry Multi-UnitProbabilistic Risk Assessment,"

R08 950413896, January 1995.

Johnson, D. H., et al., "Browns Ferry Nuclear Plant Unit 2 Probabilistic Safety Assessment with Unit 3 Operating," PLG, Inc., prepared for Tennessee Valley Authority, PLG-1112, Revision 0, April 1996.

4.

"Browns Ferry Unit 2 Individual Plant Examination Revision 1, Interim Order No. 2,"

R92 950912800, September 1995.

5.

PLG, Inc., "Database for Probabilistic Risk Assessment of Light Water Nuclear Power Plants," PLG-0500, 1989 (Proprietary).

Sandia National Laboratories, "Analysis of Core Damage Frequency:

Peach Bottom, Unit 2:

Internal Event Appendices," Appendix D prepared for U.S. Nuclear Regulatory Commission, NUREG-CR/4550 Volume 4, Revision 1, Part 2 (SAND86-2084)

~ 1989.

iTvM40047.DOC.OSII 386 5-1 PLG

APPENDIX A. BROWNS FERRY UNIT 2 PSA UNCERTAINTYANALYSIS The Browns Ferry Unit 2 PSA uncertainty analysis was performed using the group "All" defined in the model BFNU2M. The number of sequences retained in the important sequence file, "ALL.SEQ," was 2,500.

The conditional split fractions in the important sequence files were replaced by the corresponding intermediate split fractions, as listed in Table A-1. The tuSKMAN distribution file, CSF.DRA, was updated, incorporating modifications of top events in several systems.

In addition, several database variables were developed to represent the distributions of several initiators; this is shown in Table A-2.

The total CDF for the Browns Ferry Unit 2 PSA was calculated with the following results:

Mean 5th Percentile Median 95th Percentile 5.39E-06 9.02E-07 2.64E-06 1.48E-05 PLG

Table A-1 (Page 1 of 7). Split Fraction (SF) Substitutions to Support Core Damage Uncertainty Calculation for Unit 2 PSA Top Events in SF Group AA, AB, AC, AD DE, DH, DG EP EP System

'plit Fractions in SF Group

-AD1

-AA2 -AC16 -AD30

-ABS -AC16 -AD30

-Acl

-AB1

-DH3 -DGK

-DGJ

-DEl -DH1 -DGB

-DGL

-DH4 -DGM

-DE1 -DH1 Replace SFs in the Group With

-S110

-S303

-S110

.-S110

-DYGHS

-DYGH3

-DE1 -DXGHS

-DYGH3

-DYGH7

-DR1 -DXGH1 EA, EB, EC, ED EECW

-EA2 -EBS -EC10 -ED29

-EA1 -EB2 -ED10

-EA2 -EBS -ED28

-EA2 -EBS -ED30

-ED34

-EA1 -EB2 -EC4 -ED11

-EB1 -EC2 -ED5

-EA1 -EC2 -EDS

-EA2 -EC11 -ED32

-EA1 -EB2 -EC4

-EA2 -EBS -EC10

-EC12

-EA2 -EBS

-EB6

-EA2

-EE30

-EE12

-EE27

-EE19

-EE15

-EE14

-EE13

-EE28

-EE11

-EE26

-EE18

-EE20

-EE17

-EE16 ETVAW0047.DOC.04/06/96 A-2 PLG

Table A-1 (Page 2 of 7). Split Fraction (SF) Substitutions to Support Core Damage Uncertainty Calculation for Unit 2 PSA Top Events in SF Group EPR30, EPR6 GA, GD, GB, GC System MISC EP Split Fractions in SF Group

-EPR304 (...) -EPR64

-EPR303 {...) -EPR63

-EPR301 (...) -EPR62

-EPR301

-EPR302

.-EPR303

-EPR304

-GA1 -GD2 -GB4 -GC4

-GA1 -GB2 -GC3

-GC1

-GD1 -GC2

-GB1 -GC2

-GD3 (-FD1) -GB4 -GC7

-GA1 -GC2

-GA1 (-FB1) -GC6

(-FA1) -GB3 -GC6

-GCS

-GA1 -GD2 (-FB1) -GC7

-GD1 -GB2 -BC3

-GA1 -GD2 -GC3

-GC8

-GA1 -GB2

-GD1 -GB2

-GB1

-GA1 -GD2 -GB4

-GB3 Replace SFs in the Group With

-STA6H4

-STA6H3

-STA6H2

-STA301

-STA302

-STA303

-STA304

-DG4

-DG3

-DG1

-DG2

(-FD1) -DG3

-DG2

(-FB1) -DG2

{-FA1) -DG2

-DG1

-FB1 -DG3

-DG3

-DG1

-DG2

-DG1

-DG3

-DG1

<TVALhl0047.DOC.04I06I96 A-3 PLG

Table A-1 (Page 3 of 7). Split Fraction (SF) Substitutions to Support Core Damage Uncertainty Calculation for Unit 2 PSA Top Events in SF Group GE, GG, GF, GH EP System Split Fractions in SF Group

-GA1 (-FD1) -GB4

-FAI -GD3 -GB4

-GD1

-GAI -GD2

-GA1

-GH1

-GEI -GH2

-GH3

-GG1 -GH2

-GFI -GH2

-GEI -GF2 -GH4

-GEI -GG2 -GH4

-GEl -GF2

-GF1

-GE1 -GG2 -GF4

-GF3

-GG1 -GF2

-GGI

-GE1 -GG2

-GG3 Replace SFs in the Group With

(-FDI) -DG2

-FA1 -DG2

-DGI

-DG2

-DG1

-DG31

-DG32

-DG31

-DG32

-DG33

-DG32

-DG31

'-D633

-DG31

-DG32

-DG31

-DG32

-DG31 HXA, HXC, HXB, RHR HXD

-GE1

-HXA1 -HXC2 -HXB5

-HXD7

-HXA1 -HXB2 -HXDS

-HXD10

-HXA1 -HXC2 -HXD6

-DG31

-HX4.

-HX3

-HX1

-HX3 ETVAW0047.DOC.04/06/96 A 4 PLG

0

Table A-I (Page 4 of 7). Split Fraction (SF) Substitutions to Support Core Damage Uncertainty Calculation for Unit 2 PSA Top Events in SF Group NPI, NPII PX1, PX2 System SAI SAI Split Fractions in SF Group

-HXDI

-HXB3

-HXB6

-HXB1

-HXC1

-HXA1

-NPI1 -NPII2

-PX23

-PX11 -PX22

-PX21

-PX11 Replace SFs in the Group With

-HX1

-HXl

-Hxl

-HX1

-NP2

-PXI

-PXII

-PXI

-PXI RCI, HPI RCL, HPL RCIC/HPCI

-RCIC -HPI4

-HPI6

-HPIl

-HPI2

-HPI4

-RCI1 RCIC/HPCI

-RCL1 -HPL3

-HPL5

-HPL1

-HPL3

-RCL1

-HRSSYl

-HRSHP1

-HRSHP2

-HRSHP I

-HRSSY1

-HRSRC1

-HRXSY1

-HRXHP1

-HRXSY1

-HRXRC1 RPA, RPC, RPB, RPD

-RPA1 -RPC2 -RPD10

-RPX3

-RPA1 -RPC2 -RPB3 -RPD4

-RPX4

-RPB5 -RPD9

-RPA1 -RPB2 -RPD3

-RPX2AC

-RPX3

~~vn~inn~~ one n~ nt'en PLG

Table A-1 (Page 5 of 7). Split Fraction (SF) Substitutions to Support Core Damage Uncertainty Calculation for Unit 2 PSA Top Events in SF Group RS, RT EP System Split Fractions in SF Group PRPB 1 -RPD2

-RPA1 -RPD7

-RPC3 -RPD7

-RPB2 -RPD9

-RPA1 -RPD9

-RPD9

-RPA1 -RPB6 -RPD10

-RPC3 -RPB6 -RPD10

-RPB6 -RPD10

-RPAl (-HX1) -RPD2

-RPA1 -RPC2 (-HX1) -RPD3

-RPDS

-RPA1 -RPC2 -RPD3

-RPD1

-RPD8

-RPA1 -RPC2 -RPD4

-RPB6

-RPB1

-RPA1 -RPB2

-RPA1 -RPC2

-RPC3

-RPC1 PRPAl

-RS1 -RT2

-RT1

-RT3 Replace SFs in the Group With

-RPX2AC

-RPX1

-RPX3

-RPX2AC

(-HX1) -RPX2AC

(-HX1) -RPX3

-RPX1

-RPX3

-RPX1

-RPX3

-RPX1

-RPX2AB

-RPX2AC

-RPX1

-RPXl

-SDBD22

-SDBD21

0

Table A-I (Page 6 of 7). Split Fraction (SF) Substitutions to Support Core Damage Uncertainty Calculation for Unit 2 PSA Top Events in SF Group SW2A, SWIA, SW2C, SWI C SW2B, SWIB, SW2D, SWID System RHRSW RHRSW Split Fractions in SF Group

-RSI

-SWICI

-SWI C7

-SW2C I -SWI C2

-SW2A I -SWIA2 -SW2C4

-SWI C6

-SW2c1

-SWIAI

-SW2AI -SWIA2

-SW2AI

-SW2B I -SW IB2 -SW2D4

-SWID6

-SWID7

-SWID14

-SWID16

-SWID17

-SWIDII

-SW2DI -SWID2

-SW2B I -SWIB2.-SW2CI

-SWIC2 -SW2D4 -SWID6 Replace SFs in the Group With

-SDBD21

-NB

-NAC

-NABCD

-NA

-NB

-NAC

-NA

-SABCD

-SB

-SAC

-SW2CI -SWIC2

-SABCD

-SW2B I -SW2D9 -SWID13

-SABC

-SWIDI

-SW2DI

-SW2D6

-SW2D7

-SW2D5

-SWIB3

-SB

-SA

-SB h.>

PLCi

4

Table A-1 (Page 7 of 7). Split Fraction (SF) Substitutions to Support Core Damage Uncertainty Calculation for Unit 2 PSA Top Events in SF Group Initiator System RBCCW Split Fractions in SF Group

-SWI BI

-SW2B1 -SW182

-SW2B1 LRBCCW Replace SFs in the Group With

-SB

-SAC

-SA RBCIE

Table A-2. Database Variables Representing Distribution of Initiating Events (Lognormal)

DPD Variable Mean Range Factor Initiating Events HS2 HS3 0.085 0.057 4

LOCV PLOC PLFW CIV HS4 HSS HS6 HS7 0.3 0.126 0.142 0.09 2.5 3.5 LOFW LOPA PRFC TTWB LOSP L500PA L500U2

0

APPENDIX B. LISTING OF TOP 100 SE UENCES

Figure B-1 presents a listing of the top 100 sequences for the Unit 2 PSA model.

4TVA>Y0047,DOC,OS/1 3I96 B-1 PLG

HOOEt Manes BFJRJ2H Top-Ranking sequences Contributing to Croup I ALL Frequency ALL Atl DANACE STATES RXCRPT SUCCESS OYI56>44 09 HAY 1996 Ranr No.

Sequence Description

~ ~ Events--- ~-----------

Cuaranteed Events/Coeraents En4 State Frequency Percent tper yearl TURBINE TRIP VESSEL INJECYION MITE CROSS UlJAVAILABLE AVTOHATIC/HANVALREAClOR SCRAH FAILURE CONDITIONS RRtATINC TO STUCK OPEJJ SRVS to, I, 2, 30 SORVSJ STATS 1

REJ IEP VAJ.VE STUCK OPEN OPERATOR FAtLS TO CONIROL L'Pl DVRINC ATMS

~

~\\ ~ 00 ~

~

0 ~ 0

~ ~

~ 0 ~ 0

~

~ ~

~ ~ ~ ~ ~

~ 0 ~ ~ 00 ~ 0

~ ~ ~ 000 ~

0

~ 0

~

~ 0

~

~ 0 ~ 000 ~

~

~ 0

~

TURBINE TRIP RPV DEPRESSURI)ATION AQIOHATIC/NANJALREACIOR SCRAN PAILURE OPERATOR FAILS TO START SLC Olhv NKCV 1.01E 09 1.44 9.5)E.OI 1.40 9.25E F 04 1.35 HIAV TURBINE TRIP AIJIOHATIC/HANJALREACfOR SCRAN FAIWRE STANDBY I IQVID CONTROL SYSTRH UNAVAIIABLS CONDITiONS RElATIHQ TO STUCK OPEN SRVS 10 ~

1 e 2 ~

3 0 SORVSJ STATS 0 RRLIEP VALVES STUCX OPEN

~

0

~

~\\ ~ ~ 0

~ ~ ~

~ ~

TOTAL LOSS OF OFFSITE POMER DQ h UNAVAILABLE DQ D UNAVAILABLE DQ 8 WAVAILABLR DQ C VNAVAILABLS FAILURE TO RECOVER OFFSITS POMSR IN 30 HINUTRS COHNON CAVSB COVPLINC OP UNIT 1/2 AND UNIT 3 DIESELS CONDITIONS RELATINC TO STUCK OPEN SRVS 10, 1, 2, )i SORVSJ STATE 0 RELIEP VAI,VES STUCK OPEN thlLVRE TO RECOVER ELECTRIC POMER IN 6 lJOURS PICX 6.41E 04 I.)Y 500 KV OttSITE GRID UNAVAILABLE 161 KV OFPSITB GRID UNAVAIIABLE OPERATOR PAILS TO RSSYORE POMER TO WIT BOARDS 4KV UNIT BD IA UNAVAILASLS 4XV UNIT BD 18 UNAVAILABLE 4KV UNIT BD 1A UNAVAILABLE 4KV UNIT BD 28 WlVAlLABLE SNQYDOMN BUS 1 WAVAILASLS SNJJDOMN BVS 2 UlSVAILABLE 4XV SD BD A WAVAILABLR 440V SNVIDOMH BOARD ll

- 440V RHOV BD ih POMSR WAVAILAILE 440V DIESEL AUX. BD A POllER UNAVAIIABL'I 4KV SD BD 8 UNAVAILABLR 440V SNJTDOMN BOARD )h 440V RHOV BD )A POMER UNAVAILABLE

- 4KV UNIT BD )C POMER WAVAILABLB 120 V RPS BVS ihi WAVAILABLE

- 4KV SD BD C UNAVAIIABLE 440V SNVIDO Ol BOARD 18 440V RJKIV BD 18 PONER UNAVAILABLR 4XV SD BD D UNAVAllABLE 440V SNVIDOMN BOARD 28 440V RNOV BD 20 POMER WAVAILABLR

- 440V RNOV SD 2$ POMER WAVAILABLE 440V RHOV BD 28 POMER UNAVAILABLS 440V RHOV BD )C tOMER UNAVAILABLE

~ IOV DIESEL AVX BD 8 POMER JJNAVAIIABLE

- 120 V RPS BVS iS'NAVAILABLE 120 V IIC BUS 28i UNAVAILABLE 4KV WIT BD )A VNAVAILABLS 4KV WIT BD 38 WAVAILABLE DQ 3A WAVAILABILITY 4KV SD BD )EA AHD 440V SO BD 3A POMSR UNAVAltABLE 440V SNJIDOMH BOARD 3l 440V DIESEL AVX BD )Eh POMIR VNAVAILABLE 120 V IIC BVS i)Ai WAVAILABLE DC 3C WAVAIIABLE 4KV SD 80 )EC AND 440V SD BD )8 JJHAVAILABLE

- DQ 38 WAVAIIABLS 4KV SD BD 3$8 UNAVAILABLE 440V SNJlDOMN BOARD 38

- 440V DiESEl AVX BD )SS POSER WAVAILABLE DC 3D WAVAIIABLE

~KV SD BD )ED UNAVAILABLE RAN COOLINC NATRR SYSTEH WAVAILABLE RECN PUHP A WAVAILABLE EECM PUHP 8 WAVAILABLR SECH PUHP C UlQVAIIABLE 0 ~ii

~ 0 0 ~ 0 ~ 00

~

~ 00 ~

0 ~

~ 00 ~ 00 ~ 0

~ 000 ~ 0

~

0

~

~ 0

~

~ 00 ~

~ 00

~ 0 ~ 0

~

~ 000 ~ 0 ~

~ 0 ~ 0 ~ 0 ~ 0 00

~ 0 ~ 0

~ ~

~

~ ~

~

0

~

~ 0 ~

0

~ ~ ~

~

~ ~ 0 ~

~

Figure B-1 (Page 1 of 26). Top 100 Sequences in Brogans Ferry Unit 2 PSA Model

CO U0O cD IA NODEt. Mane>

BFMVIN Rank No.

Sequence Description Top.Ranking Sequences Contributing to Croup

ALL Prequency AL(

ALL DAMAGE STATES EKCEPT SUCCESS

~ ---- ~ ----Svents---------------

Guaranteed Events/Coements EECN PUMP D UNAVA(LABLE RX BUILDIMC COMPONENT COOLIMQ MATER SYSTEM UNAVAILABLE RHRSM PUMP A2 UNAVAILABLE RHRSM PUMP Al (SMINQ PUMP) WAVAILABLE RNRSM PVMP $2 UNAVAILABLE RHRSM PWP Bl (SMINQ PUMP) WAVAILABLE RNRSM PWP C2 UNAVAILABLR RMRsll PVNP Cl (SMIMQ PUMP)

UNAVAILABLE RHRSM PUMP D2 UNAVAILASLE RHRSM PUMP Dl (SMINQ PWP)

UNAVAILABLE PLANT COMIROL'IR SYSTEM UNAVAILABLE DRYMELL CONTROL AIR SYSTEM UNAVAILABLR CONTAINMENT AIMOSPHSRIC DILUTION

- OPERATOR FAILS To RECOVER SECH (START SMINQ PUMP)

HSIVS PAIL TO REMAIN OPEN 1 CND/CND BSIR PUMP, INCLVDES SHORT CYCLE VALVE UMAVAILAS!

RCIC UNAVAILABLRLONQ TERM HPCI UNAVAILABLELOMQ TERN

- VRSSS(

INJECTION MITE CRDHS WAVAILABLE OPRRATOR tAILS TO MANUALLYSTART RHR/CORE SPRAY FAILURE TO RECOVER 480V RNOV BDS 2A OR 2B RHR PUMP A UMAVAILABLR RHR PUMP C WAVAILABLR Ul To U2 RNR CROSS CONNECT WAVAILABLR RHR PWP B WAVAILABLR RNR PUMP D VNAVAILABIE

- Ul To U2 RHR CROSS CONNECT WAVAIIABLR OPERATOR FAILS TO ESTABLISN TORUS COOLIMQ RHR LOM PRESSURE INJECTION l'ATH UNAVAILABLE 02 56. ~ 8 09 MAY 1996 Rnd Frequency Percent State (per year) 5 LOSS Ot RAM COOLINQ MATER CONDITIONS RELATINQ TO STUCK OPEN SRVS

{0~ I ~

2 ~ le SORVS)

STATS 0 RELISP VALVSS STUCK OPEN

- RCIC VNAVAILABLR{6 HOURS)

HPCI UNAVAILABLR (6 HOURS)

RPV DBPRESSURI2ATION RAN COOLINQ NATER SYSTEM WAVAIIJLBLR HAIN CONDENSER UNAVAILABLR 1 CMD/CMD BSTR PVNP, INCLUDES SHORT CYCLE VALVE VMAVAILABL VESSEL INJECTION MITE CRDNS UNAVAILABt.s M)AV 5 ~ 988 ~ 08 l.Il 0

~

~ 0 6

CLOSVRS.OF ALL MSIVS AVIOMATIC/MANUALREACIOR SCRAM PAILURE OPERATOR PAILS To START SLC

- NSIVS PAIt"TO REMAIN OPEN RPV DEPRESSURISATION HKCV 5.478 F 08 1.02 8

CLOSURE Ot ALL NSIVS CONDITIONS RELATIMQ 'IO STVCK OPEN SRVS (0. I, 2, le SORVS)

STATE 0 RELIEF VALVES S'IVCK OPEN RCIC UMAVAILABLS (6 HOURS),

- HPCI WAVAILASLE (6 HOURS)

RPV DEPRESSURISATION VESSEL INJRCTIOH MITH CRDHS UNAVAILABLE

~

$ $ ~ 0 ~ 0 ~ oo ~ SI ~ 0 ~

~ ooo ~ ~ v ~

TOTAI, LOSS Ot OPPSITE POMSR CONDITIONS RELATINQ To STUCK OPEN SRVS (0, 1, 2, 2+ SORVS)

STATE 0 RSLIBP VALVES STUCK OPEN RCIC UNAVAILABLE (6 HOURS)

NPCI WAVAILABLE (6 HOURS)

RPV DRPRSSSVRI SATION

- NSIVS PAIL TO REMAIN OPEN RFM HARDMARS UMAVAILABLR OPERA'IOR FAILS TO INHIBIT CLOSURE OF NSIVS ON LEVEL 500 KV OFFSITE GRID UMAVAILABLR 161 KV OFFSITE GRID WAVAILABLE OPERATOR tAILS To RSSTORR POMER 'IO UNIT BOARDS 4KV VMIT BD IA UNAVAILABLR

- 4KV WIT BD IB WAVAIIABLR 4KV UNIT BD 2A UNAVAILABLE 4KV UNIT BD 2B UNAVAILABLE

- SHVIDOMM BUS 1 WAVAILABLR SHVIIOMM BVS 2 WAVAILABLE 4KV UNIT BD 2C PONER UNAVAILABLE

- RAM COOLIHQ WATER SYSTEM WAVAILABLB NSIVS FAIL 'IO REMAIN OPEN 1 CMD/CND BSYR PUMP, INCLUDES SHORT CYCLE VALVE VNAVAILABL VESSE(

INJRCIION NITN CRDMS WAVAILABLE MIAV 4.84E.08

.90 HIAV 4.662 F 08

.87 Figure B-1 (Page 2 of 26). Top 100 Sequences in Browns Ferry Unit 2 PSA Model

MOOEI Nanei BFNVIH Top-Ranking sequences contrlbutlng to Group:

ALL Frequency ALI, ~ ALL DAMACS STATES EXCSPT SUCCESS 01:56c48 09 MAY 1996 Rank No.

Sequence Descrlptlon

~ - ~ ------------Events.--------------

Guaranteed Events/Coetaents End State Frequency Percent lper yearl 9

INTSRtACING SYSTEH LOCA

~

~I

~I~\\ ~

~I

~

~\\ ~ ~\\ ~

~ ~ ~I~

~ ~ ~ 0 ~ ~ ~ 0 ~ ~ ~ ~ ~I~ ~ ~ ~ ~

~ ~ ~ ~\\ ~ ~ ~ ~ ~I~I~ 00 ~\\ ~

~I

~

NIAX 4.63C 0$

.$ 6 10 LOSS OF RAN COOLINC MATER CONDITIONS RELATINC IO SIVCK OPEN SRVS lo, I, 2 ~

30 SORVSI STATS I REI IEF VALVE STUCK OPRH OPERATOR PAILS TO ESTABLISH TORUS COOLINC RAM COOLING 'NATER SYSTEM UNAVAILABLE MAIN CONDENSER UNAVAILABLS 1 CMD/CND SSTR

PUMP, INCLUDES SNORT CYCLE VALVE VMAVAILABL VESSEL INJECTION MITH CRDMS VNAVAILABLS OLCV 4.508.08

.84

~I

~ 0

~ 0 ~ 0 ~ 0 ~ 00 ~

~I I

~ 0 ~ 00 ~ 00000 ~ 000000 ~ 000

~

~ 0

~ 0 ~ 0 ~

~

~ 0 ~ ~

~\\

~ 000 I 00 ~\\ ~

~ 0 \\ ~ 00 000000 00000

~

~ 0

~I I~

~

~I

~I 11 SHALL LOSS OF COOLANT ACCIDENT ILOCAI AUTOMATIC/MANUALREACTOR SCRAM tAILVRE CONDITIONS RELATING IO STUCK OPEN SRVS lo, I, 2, 3 ~

STATE 1 RELIEF VALVE SIVCK OPEN VESSEL IN3ECTION MITE CRDHS UNAVAILABLE 000000 00000000000000

~ 000 ~I~\\ ~ 0 0

~ 0 ~

~

CONDITIONS REIATINC TO STUCK OPEN SRVS lo, 1, 2 ~

30 STATE 3

OR HORS VALVES STUCK OPEN O'PERATOR tAILS 'TO ESTABLISH SNVIDOMN COOLINC

~I~ 000 ~I~ 00000

~ 0000 00 ~ 000 ~ 000 ~I

~

~ ~ ~I

~ ~ ~ ~ ~ ~

500 KV OttSITR GRID UNAVAILABLE 161 KV OtPSITR GR'ID UNAVAILABLR OPERATOR FAILS TO RSSIORE POMER TO UNIT BOARDS 4KV INIT BD 1A WAVAILABLE 4KV UNIT BD IB UNAVAILABLR 4KV lNIT BD 2A UMAVAILABLR 4KV UNIT Bb 18 WAVAILABLE SNVIDOMM BVS 1 WAVAICABLE SN'IDOMN BUS 2 UNAVAIIASLE DC A WAVAILABLE DC D INAVAILASLE DC 8 UNAVAILABLE DC C UNAVAILABLE

~ KV SD BD A UNAVAILABLE 440V SNlIDOMN BOARD IA 480V RHOV BD IA POllER UNAVAILABLE 480V DIESEL AVX. BD A POMER UNAVAILABLE 4KV SD BD 8 UNAVAILABLE 480V SMVIDOMN BOARD 2A 480V RHOV BD 2A PONER UNAVAILABLE 4XV WIT BD 2C POMER VNAVAIIABLE 110 V RPS BVS OA UNAVAILABLR 4XV SD BD C UNAVAILABLE 480V SMUIDOMN BOARD 1B 480V RMOV BD IB POWER WAVAILABLE 4KV SD BD D UNAVAILABLE 480V SHUIIXNN BOARD 28 480V RMOV BD 2D POMER UNAVAILABLE 480V RNOV BD 28 POMER UNAVAILABLE

~ lOV RHOV BD 28 POMRR INAVAIIABLE 440V RHOV BD 2C POMER UNAVAILABLR 480V DIBSRL AUX BD B POSER UNAVAIIABLE 120 V RPS BUS 080 UNAVAILABLR 110 V 16C BUS 018'NAVAILABLE 4KV WIT SD 3A VNAVAIIABLE 4KV UNIT BD 3B UNAVAILABLS FURL OIL SYSTEM POR DIESEL 3A WAVAILABLE DC 3A lNAVAZIABILITY 4KV SD BD 3RA AND 480V SD BD 3A POMER WAVAILABLR 480V SNUTDOMN BOARD 3A 4$ 0V DIESEL AUX BD 3EA POMER UMAVAILABLS 110 V Z6C BQS 02AO WAVAILASLE tVEL OIL SYSTEH tOR DIRSSI 3C UNAVAILABLE DC 3C VNAVAILASLR 4KV SD BD 3EC AND 480V SD BD 38 UNAVAILABLE FVEL OIL SYSTEM FOR DIESEL 38 WAVAILABLE DC 38 INAVAILABLR 4KV SD BD 3EB WAVAILABLE 480V SMVTDOMM BOARD 38 00

~I~\\ ~I~ 0 ~\\

~ ~

~

~ 0

~I~\\

~ 00000 ~ 0 ~

12 INADVERTENT OPRNIHG OP THREE OR HORS SRVS

- OPERA'IOR PAILS TO ESTABLISH TORUS COOLINC I~ 000 00 I~ I~ 00000000

~ 0000 000 ~ 00 00 ~

~I

~\\ ~ 0 ~

13 TOTAL LOSS Ot OFtSITE POMER FVEL OIL SYSTEM tOR DIESEL A WAVAILABLS FVEI OIL POR DIESEI D UNAVAILABLE tUEL OIL SYSTEM POR DIESEL 8 INAVAIIABLR tUSL OIL SYSTEM FOR DIRSEL C WAVAZLABLE tAILURR 'TO RECOVER OttSITE POMER IN 30 HINVTES CONDITIONS RELATINC TO SIUCK OPEN SRVS l0 ~ I 2 ~

3$

SORVSl STATE 0 RELIEF VALVES SIUCK OPEN tAILURR 'TO RECOVSR ELECIRIC POMER IN 6 HOURS SORVS) 0'IAV SORVS)

OLCV PICK 3.638 ~ 0$

.64

~

~ ~

~I~ ~ ~I

~

3.35E F 08

.62

~ ~

~

3 ~ 268 0$

~ 61 Figure 8-1 {Page 3 of 26). Top 100 Sequences in Browns Ferry Unit 2 PSA Model

MODEL Naa>>:

BFMVIM Top-Rank(ng Sequences contr(but(ng to Group L ALL Frequency AL(, 0 ALL DAMAQR STATES EXCSPT SUCCESS 01:56:68 09 MAY 1996 Rank No.

Sequence Descript)on

~ -- ~ ~ ~ ~ ~ - -- ~ ~ ~Evente-------

Cuaranteed Evente/Coen>>nts End State Frequency Percent (per year) le LOSS OF CONDENSRR VACVUH CONDITIONS RSLATINQ TO STUCK OPEN SRVS (0, 1 ~ 2, 30 SORVS)

STATE 0 RELIRt VALVES SIUCK OPEN RCIC WAVAILABLE (6 HOURS)

HPCI UNAVAILABLEl6 HOURS)

RPV DEPRESSURIIATIOM VESSEL llQECTION 'MITH CRDNS VMAVAILABLR eeOV DISSRL AUX BD 3EB POMER UNAVAlLABLR FUEL Oll FOR DIESSL 30 UNAVAIIABLR DQ 3D WAVAILABLR eKv SD BD 3ED UNAYAILABLE RAM COOLINQ MATER SYSTEM UNAVAILABLE

- ESCN WMP A WAVAILABLS EECN PVHP B UNAVAILABLS EECN PUMP C UNAVAILABLS SRCN WHP D VNAVAILABLR RX BUILDINQ COHPOMENF COOL)NO MATER SYSTEM WAVAILABLE RNRSM PUMP A2 VNAVAILAB(R RMRSM WHP Al (SNINQ PWP)

UMAVAILABLS RNRSN PUMP B2 UNAVAILABLR RNRSM WHP 81 (SMINQ WMP) UNAVAILABLE RHRSN PUM('2 WAVAILABLE RMRSM PUMP Cl (SNINQ PUMP) VNAVAILABLE RMRSM PUM('2 WAVAILABLE RNRSN PVHP Dl (SNINQ WMP) UMAVAILABLS PLANT CONTROL ALR SYSTEM WAVAILABLE DRYNELL COMIROL AIR SYSTEM UNAVAILABLE CONTAINMENT AI)OSPNERIC DILUTION OPRRAIOR FAILS TO RECOVER RECM (START SNINQ Ptn(P)

NSIVS FAIL 'IO REMAIN OPEN 1 CND/CND BSTR PUHP, INCLVDES SHORT CYCLE VALVE UNAVAILABL RCIC WAVAILABLSLONQ TERN HPCI UNAVAILABLELONQ TERH VESSEL IlQECYION MITE CRDHS WAVAILAB(E OPERATOR tAILS TO MANUALLYSTART RNR/CORE SPRA'Y tAILURE TO RECOVER 640V RHOV BDS 2A OR 2B RMR PWP A UNAVAILABLE RMR PUMP C UMAVAILABLR Ul IO V2 RMR CROSS CONNECT WAVAILABLE RMR PVHP B WAVAILABLR

~ RNR PUMP D UMAVAILABLR U3 TO U2 RNR CROSS CONNECT UMAVAIIABLE OPERATOR tAILS IO ESTABLISH TORUS COOLINQ RNR IA)N PRESSURE IIQECTION PAIN UNAVAILABLE

~

0 000000

~ 0 0000000

~ MAIN CONDENSER UNAVAILABLE RFM NARDMARS WAVAILABLS

~ OPERATOR tAILS TO DEPRESSURISE USINQ TBV'S M(AV 2.91E ~ Oe

.55 15 TURBINE TRIP NITMOUT B'YPASS AVIOMATIC/MANUALREACIOR SCRAM PAILVRE OPERATOR FAILS 'TO START SLC 0

00

~

~ 00 0

~

16 INADVERTENT OPEN)NQ Ot ONE SRV

- AVIOMATIC/MANVA(REACTOR SCRAN FAILURE

- OPERATOR tAILS TO CONTROI L'Pl DVRINQ AIMS

~ 0 ~ 0 ~ 0 ~ 0 ~ 0 ~ 0 ~ 0 ~

~ 0

~

~ 0

~ 0 ~

~ 0 ~ 0 ~ 0

~

~ 0

~ ~

~ ~ 0 ~ 0

~ 00

~ ~ 0 ~ 0 ~ ~ 0 17 CLOSURE OF ALL NSIVS AVIOMATIC/NANVALREACIOR SCRAH PAILVRE

- CONDITIONS RELATINQ TO STUCK OPEN SRVS lo, 1, 2,

30 SORVS)

STATS I RE()EP VALVE STUCK OPBM

- OPERATOR PAILS IO CONTROL LPI DVRINQ AIMS

~ 0 ~ 0 ~ 0 ~ 00 ~ 0 ~ 0 ~ 0 0 ~ 0 ~ 0 ~ 0 ~ 000 ~ 00 ~\\

le TOTAL LOSS OF OttSITE POllER

- DQ A UNAVAILABLE DQ D UNAVAILABLE DQ B WAVAILABLE

'IBVS PAIL IO RELIEVE LMAINYAINRX PRESSURE

~

RPV DRPRSSSURIZATIOM CONDITIONS RELATINQ 'TO SIUCK OPEN SRVS lo, I, 2, 30 SORVS)

STA'IE 1 RELIEF VALVE SIUCK OPEN VESSEL INJECTION NITH CRDHS UNAVAILABLE

~\\ ~ 0 ~ 0 ~ 000 ~ 000 ~ 0000 ~ 0 ~\\ ~ 0 ~ 00000000 ~ 0

~\\ ~ 0 ~ 00 ~

~ 0 ~ ~ ~

~ ~

- MSIVS FAIL IO REMAIN OPEN OPERATOR tAILS IO COOLDONN USINQ TME TBVS

- VESSE(

INJECIION MITE CRDNS WAVAILABLR 500 KV OFFSITE QRlD UNAVAILABLE 161 KV O'FPSITE GRID WAVAILABLE OPERATOR tAILS TO RESIORS POMER TO UNIT BOARDS eKV UNIT BD 1A WAVAILABLS

~ 0'0'

~

~ 0

~ 0 F 0' 00'

~ 0 ~ 0 ~ 0 ~

~

~ 0

~ 0 F 0' 0 ~ 0 ~ ~ 0 ~ 0 ~ 00 ~ 000 ~ 0 ~ 000 ~ 0 ~ 0

~ 0 ~ 0 ~ 0 ~ 00 ~ 0

~ 0

~

MKCV

~

~ ~ ~ 0 ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~

2.46E-OS

.53 0(AV 2.83K F 01

.53 0(AX 2.61K F 04

~ ~

~ ~ ~

.69 OIAV 2.9eE-04

.51 Figure B-1 (Page 4 of 26). Top 1DD Sequences in Browns Ferry Unit 2 PSA Model

-)

z ca CD U

HGDSL Mane BFNUIH Top.Rank(ng Sequences Contr(but(ng to Croup

> ALL Frequency ALL ALL DAMAGE STATES EXCEPT SUCCESS Rank No.

Sequence Descr(ption

~ -------Events

-- ~

Guarinteed Event ~ /Coen>ants FAILURE TO RECOVER OFFSITE POMER IN lo MINUTES DG 3D WAVAILABLS CONDITIONS RELATING TO SYUCX OPEN SRVS (0, I~ 2, 3 ~

SORVS)

STATS 0 RELIEF VALVES STUCK OPEN FAILURE TO RECOVER SLECYRIC POMSR IN 6 HOURS 4KV UNIT BD 1$ UNAVAILABLE 4KV UNIT BD 2A UNAVAILABLE 4KV WIT BD 2$ (NAVAILABLR SNUIDOMH BUS I UNAVAIlABLR SNUIDOMN BUS 2 UNAVAILABLE 4XV SD BD A UNAVAILABLS 440V SNUYDOMN BOARD IA 440V RHOV BD IA POMSR UNAVAILABLR 440V DIESEL AUX. SD A POMER WAVAILABLS 4KV SD BD B UNAVAILABLE 440V SMUIDOMN BOARD 2A 440V RHOV BD 2A POMER UNAVAILABLR 4KV WIT BD 2C POMRR WAVAIIABLS 120 V RPS BUS >A> UNAVAILABLB, 4KV SD BD D UNAVAILABLE 440V SMUIDOMN BOARD 2$

440V RHGV SD 2D POMER UNAVAILABLR 440V RHOV BD 2R POMER WAVAILABLE 440V RHGV BD 2B POMRR UNAVAILABLE 440V RHGV BD 2C POMER UNAVAILABLE 440V DIESEL AUX BD B POMER WAVAIIABLE 120 V RPS BUS 'B'AVAILABLS 4KV UNIT BD 3A WAVAILXBLE 4KV UN(T BD 3B WAVAILABLE

- 4XV SD BD 3ED UNAVAILABLS RAM COOLING MATER SYSTEM UNAVAILABLE RX BUILDING COMPONENT COOLING MATER SYSTEH UNAVAILABLE RMRSM P(NP A2 UNAVAILABLE

- RMRSM PWP Al (SHING PWP)

WAVAILABLR RNRSM PUMP C2 UNAVAILABLR RNRSM PUMP Cl (SHING PUHP)

UNAVAILABLE RNRSM PUNP D2 UNAVAILABLE RNRS'M PWP Dl (SHING PUMP) WAVAILABLR PLANT CONIROL AIR SYSTRH WAVAILABLS

- DRYMRLL COÃIROL AIR SYSTEM WAVAILABLS HSIVS FAIL 10 REMAIN OPEN 1 CND/CND BSTR PUHP, INCLUDES SHORT CYCLE VALVE UNAVAILABL RCIC WAVAILABLELONG TERN NPCI UNAVAILABLSLONG TERN VESSEL IHJECIION MITH CRDNS WAVAILABLE

~ RNR PUNP A WAVAILABLR RMR NNP C UNAVAILABLR RMR PWP $ UNAVAILABLR RNR PUMP D WAVAILABLR Ul '10 Ul RNR CROSS CONNECT WAVAILABLR CS LOM PRESSURE INJECTION (NAVAILABLE RMR LOM PRESSURE INJSCI'ION PATH UNAVAILABLR OOOO'O

~ 010

~ 0 ~I

~ 0 ~

~ ~ 0 ~

~ 0 ~ ~ ~

0

~

~ ~

~

>> TBVS PAI(> '10 RELIEVE%MAINTAINRX PRESSURE RPM NARDMARE WAVAIIABLR OPERATOR FAILS TO DEPRESSURIXS USING TBV'S 19

'IURBINE TRIP MITNOUT BYPASS

- CONDITIONS RELATING '10 SIUCK OPEN SRVS (0, I>

STATS 0 RSLIEF VALVES STUCK OPEN RCIC UNAVAILABLE (6 NOURS)

HPCI UNAVAILABLS (6 HOURS)

RPV DRPRESSURIXATION VESSEL INJSCTION M(TN CRDNS WAVAILABLE OOO

~

20 IURS INE TRIP CONDITIONS RELATING '10 STUCK OPEN SRVS (0, I~

STATE l OR HORS VALVES STUCK OPEN OPERATOR FAILS TO ESTABLISH TORUS COOLING 2,

3+

SORVS)

OPERATOR FAILS TO ESTABLISH SNUIDOMN COO( ING 2>

3>

SORVS)

~

~\\

0 ~ IO

~\\

~I~ OIO ~ 0 ~I~

~ > ~

~

~ 0

~

~ ~

~

~ ~ ~ ~ 0 ~

07 S6 44 09 NAY 1996 End State Frequency I'ercent (per year)

HIAV 2.92S 04

.47 OLCV 2.42E.04

.4S 21 TOTAL LOSS OF OFPSITS POMER DG A UNAVAILABLR DG B UNAVAILABLE SOO KV OPFSITR GRID WAVAILABLR ICI KV OPFSITE GRID WAVAILASLS OPERATOR FAILS TO RESTORE POMER '10 UN(T BOARDS PLFV 2.4IE ~04,4$

Figure B-1 (Page 5 of 26). Top 100 Sequences in Browns Ferry Unit 2 PSA Model

MODEL Mane J BFNUIH Top-Ranking Sequencea Contributing to Oroup s ALL Frequency aLL - at,t, DAMAOE sIayss Excspy soccsss 07:56J48 09 MAY 1996 Rank Jlo ~

Sequence Deacription

Rvente----

Ouaranteed Evente/CoeJaenta End State Frequency

Percent, (per year)

DC C UNAVAIIABLE FAILURE TO RECOVER OPFSITS POMER IN 30 MINUTES Do 3C UNAVAILABLR CONDITIONS RELATIW IO SIIJCK OPEN SRVS (0, I, 2, 3v SORVS)

STATE 0 RELIEP VALVES STUCK OPEN FAILURE To RECOVER ELECIRIC POMSR IN 6 HOURS 22 CLOS(JRE OF ALL MSIVS AUIOMATIC/MANUALREACIOR SCRAM PAILURR STANDBY LIQUID CONTROL SYSTEM UNAVAILABLE CONDITIONS RELATIW IO SIUCK OPEN SRVS (0, I, 2, lv SORVS)

STATE - 0 RELIEF VA(VES STUCK OPEN

~ 0 ~ 0 ~ ~

~\\ ~ ~ OO ~\\ ~ S ~

~

~ ~

~\\ ~

~

~ ~ ~ ~ 0 ~ ~

~

23 PARTIAL LOSS OF FEEOMATER

- AUTOMATIC/MANUALREACTOR SCRA)4 FAIUJRR CONDITIONS RELATIHG TO STUCK OPEN SRVS (0, I, 2>

3v SORVS)

STATE I RELIEF VALVE SIUCK OPEN

- OPERA'IOR FAILS TO CONIROL LPI DURIW AIMS

~ 0 ~ $ 0 ~

~ $ $ $ ~ OO ~ S ~ ISO ~ $ 00$ $ ~ 0 OOOO

~ SSOWSO ~ 0 ~\\ ~ S ~ P

~ ~ 0 ~ 0 ~ ~ ~

~

INADVERTENT (DINER)

SCRAM

- CONDITIONS RELaTIW TO STUCK OPEN SRVS (0. I, 2, )a SORVS)

STATS 3 OR MORS VALVES STUCK OPEN OPERAIOR PAILS TO ESTABLISH TORUS COOt INQ 4KV UNIT BD IA UNAVAILABLE 4XV UNIT BD IB UNAVAILABLE 4KV UNIT BD 2A UNAVAILABLE 4XV UNIT BD 2B UNAVAILABLE SNUIDOMN BUS I UNAVAILABLE SNUIDOMN BUS 2 UNAVAILABLE 4KV SD BD A (JNAVAILABLR 480V SNUIIJOMN BOARD IA 480V RMOV BD lh POMSR UNAVAIIABLE 480V DIESEL AUX. BD A POMSR UNAVAILABLE 4KV SD BD B UNAVAILABLE 480V SNUiDOMN BOARD 2A 480V RMOV BD 2h POMER UNAVAIlABLE 4KV UNIT BD 2C POMER UNAVAILABLR 120 V RPS BUS A

UNAVAIIABLS 4KV SD BD C UNAVAILABLR 480V SNUIDOMN BOARD IB

~ 80V RMOV BD IB POSER UNAVAILABLE 4KV UNIT BD 3A UNAVAttABLE 4KV UNIT BD 3B WAVAILABLS 4KV SD BD 3RC AND 480V SD BD 3B WAVAflABLE 480V SNUIDOMN BOARD 3$

C 480V DIESEL AUX BD 3SB POMRR WAVAILABL'8

- RAM COOL)NO MATER SYSTEH UNAVAILABLR ESCM PUMP B UNAVAILABLS RNRSM PUMP A2 WAVAILABLE RNRSN PUMP Al (SNIW PUMP) WAVAILABLE RNRSM PWP B2 WAVAIIABLE RNRSN PWP Bl (SNINO PUNP)

UNAVAIIABLE

- RHRSM PUMP C2 WAVAtLASLE RNRSM PUMP Cl (SMINO PUMP) UNAVAILABLE PLANT CONTROL AIR SYSTSN UNAVAILABLR DRYMELL CONIROL AIR SYSTEM UNAVAIIABLE HSIVS FAIL To RlMAIN OPEN I CHD/CND BSIR PUMPr INCLUDES SNORT CYCLE VALVE UNAVAILABL RCIC UNAVAILABLELONO TERM NPCI UNAVAILABLELOW TERN VESSEL INJECTION MITE CRDNS UNAVAIIABLR RNR PUMP A UNAVAILABLS RNR

'PUMP C UNAVAILABLE Ul To Ul RHR CROSS CONNECT UNAVAIIABLE

~ RNR PWP B WAVAILABLR TORUS COOLIW HARDMARR WAVAtLABLS FAILURE IO RECOVER TORUS COOLINO OPERATOR FAILS To ESTABLISH SNUIDOMN COOLIW MSIVS FAIL 'IO REMAIN OPEN Vsssst INJECTION NIIN CRDHS UNAVAILABLE OPERA'IOR PAILS 'IO ESTABl.ISH SNUIDOMN COOLIW OIAV 2.34E.08

. ~ 4 OLCV 2.2)E.08

,42 OIAV 2.30E F 08

. ~ )

25 TOTAL LOSS OF PSEDMATSR

~

~I~ ~

~I~ 0

~

~ I

~

~ 0 ~ 10

~

OI I

~ 0 OO

~ 0

~

OO

~ 0 ~ 0

~ ~ ~ ~ 0 ~I~ ~ ~

~I

~ ~

RFM NARDMARE WAVAILABLE OIAV 2.14E'08

.40 Figure B-1 (Page t3 of 26). Top 100 Sequences in Browns Ferry Unit 2 PSA Model

HOQEL Mane>

BFNQZH Top.Ranking Sequences contributing to Croup

> ALL Prequency ALL ~ ALL DAMAGE STATES EXCEPT SUCCESS 09>56>44 09 HAY 1996 Rank No.

Sequence Description Events Guaranteed Events/Coen>ants Rnd State Frequency I'ercent lper yearl AUZOHATIC/MANUALREACTOR SCRAM FAILURB

- CONDITIONS RELATIW TO STUCK OPEN SRVS lo, I. 2. 3.

SORVSI STATE I RELIRP VALVE SYUCK OPEN OPERATOR FAILS TO COÃZROL LPI DURING AYMS

~ ~

<< ~

~

~ <<

~ << ~ ~ ~ <<

~

~ <<

~

~ ~ <<

26 CLOSURE OF ALL NSIVS AUTOMATIC/MANUALRSACIOR SCRAM FAILUR8 CONDITIONS RELATING TO STUCK OPEN SRVS lo> I, 2.

3 ~ SORVS)

STATS 0 RRLIRF VALVES STUCK OPEN RMR PUMP B UNAVAILABLR RMR PUMP D QNAVAILABLS

- VESSEL INJECTION Mllll CRDMS UNAVAILABLE HSIVS FAIL TO REMAIN OPEN OPERATOR FAILS TO COOLDOMN QSIW TNS TBVS OPERATOR FAILS 'IO ESTABLISH TORUS COOLING HIBV 2.008 F 04

.39

~ ~

~

~\\

~

<< ~

~

~ <<

~ << ~

~ <<

~ ~ <<

21 TOTAL LOSS OP OFFSITS POMER DG A UNAVAILABLR DG D UNAVAILABLR DG 8 QNAVAILABLS DG C UNAVAIIABLS FAILURE TO RECOVER OFFSITE POMER IN 30 HINUZES DG 3D UNAVAILABLE CONDITIONS RELATING 'IO SIUCK OPEN SRVS l0> I, 2 ~

3>>

STATS - 0 RELIEF VALVES STUCK OPEN FAILURE TO RECOVER SLECZRIC POMER IN 4 HOURS SORVSI QNAVAILAB LE VALVE UNAVAILABL 500 KV OFFSITR GRID UNAVAILABLE 161 KV OFFSITE GRID UNAVAILABLE OPERA'TOR FAILS YO RESTORE POMER TO UNIT BOARD

~ KV UNIT BD lh UNAVAILABLR 4KV UNIT BD IB UNAVAILABLE 4KV UNIT BD 2A QNAVAILABLS 4XV UNIT BD 2S UNAVAILABLE SMQZDOMN BQS I UllAVAILABLR SMUZDOOI BQS 2 UNAVAIIABLS 4KV SD BD A UNAVAILABLE 440V SMQZDOMM BOARD IA 440V RHOV BD IA POMER UNAVAIIABLB 440V DIESEL AUX. BD

POMRR UNAVAILABLE 4KV SD BD B UNAVAIIABLE 440V SMQIDOMN BOARD 2A 440V RHOV BD Zh POMER UNAVAILABLE 4XV UHIT BD 2C POMER UNAVAILABLE 120 V RPS BUS 'A>> UNAVAILABLR 4KV SD BD C UNAVAILABL'8 440V SMQIDOMN BOARD IB 440V RHOV BD 1$

POMER UNAVAILABLE 4XV SD BD D UNAVAILABLR 440V SMUIDOMN BOARD 2$

440V RHOV BD 2D POMER UMAVAILABLS 440V RHOV BD 28 POMER UNAVAILABLS 440V RHOV BD 2$

POMER UNAVAILABLE 440V RHOV SD 2C POMRR UNAVAILABLR 440V DIESRI AUX BD S POMER UNAVAILABLE 120 V RPS BQS 'B>> UNAVAILABLS 120 V 14C BUS <<2B>> UNAVAILABLE 4KV UNIT SD 3A UNAVAILABLE 4KV UNIT SD 3$ UNAVAILABLE 4KV SD BD 3ED UNAVAILABLR RAM COOLIW MATER 8'YSTEH UNAVAILABLE SECH PUHP B UNAVAILABLE RX BUILDIWCOHPONSÃl'OOLIW MATER SYSTEM RNRSN PUMP A2 UMAVAZLABLS RMRSM PUMP Al lSMIW PQHPI UNAVAILABLE RNRSM PUMP BZ UNAVAILABLS RMRSM PUMP C2 UNAVAILABLS RMRSM PQHP CI lSMING PUNPI UMAVAILABLR RNRSM PQHP D2 UNAVAILABLE RNRSll PUNP Dl (SMIW PUMP) UNAVAILABLE PLANT COHIROL AIR SYSTEM UNAVAIIABLE DRYMELL CONZROL AIR SYSTEM QNAVAILABLS HSIVS FAIL TO REMAIN OPEN I CND/CND BSTR PUMP>

INCLUDES SNORT CYCLE RCIC UNAVAILABLELOW TERM NPCZ UMAVAILABLRLONG TSRH VESSEL INJECTION MITN CRDNS UNAVAILABI,E FAILURE 'IO RECOVER 440V RHOV BDS 2A OR 2$

RMR PQNP A QNAVAZLABLS PIGX 1.988-04

.39 Figure B-I (Page 7 of 26). Top 100 Sequences in Brosvns Ferry Unit 2 PSA Model

HODEL Mane:

BFNUIH Top.Ranking Sequences Contributing to Croup i ALL Frequency ALL ~ AL( Dtu(AGE sTATES EKCspT SvccESs 09:56: ~ 8 09 MAY 1996 Rank No.

Sequence Description

~ ---- ~ --- ~ ~ ~ ~ - ~Svents---------------

Cuaranteed Events/CoeLaents Snd Frequency Percent State (per year) 28 SCRAM REQUIRED (MANUAL SCRAMS)

AVTOMATIC/MANUALREACTOR SCRAM PAILVRE CONDITIONS RSIATING IO STUCK OPEN SRVS (0 ~ l~

2 ~

STATS 1 RRLIEP VALVE STUCK OPEN OPERATOR PAILS To CONTROL LPI DVRlNQ ATMS 3a SORVS)

RNR PUMP C UNAVAILABLE Vl To Ul RMR CROSS CONNECT UNAVAILABLE RNR PUMP 8 UNAVAILABLS RNR PUMP D VNAVAILABLE U3 TO Vl RMR CROSS CONNECT WAVAILABLE OPERATOR FAILS TO ESTABLISH TORUS COOL))a)

RNR IXN) PRESSURE INJECTION PATH UNAVAILABLE VESSEL INJECTION MITE CRDHS UNAVAILABLE OIAV 1.998.08

~ 36

~ a

~

~r

~ ee ~

~r

~er es ~

~ a er

~ r ~r ~ s

~ e ~

~ ~r

~

~ ~

~ ~r ~r

~r

~ ~ ee eee eee ~r

~r ~r

~

~ a ~

~

~r ~r 10 RECIRC DISCNARCE LINE BREAK RNR PtNP A WAVAILABLS RNR PUMP C WAVAILABLE RNR PUHP 8 VNAVAILABLR RHR PVHP D WAVAILABLS r

reresr ee rare e

TOTAL IA)SS OF FSEDMATSR AVIOHATIC/MANUALREACTOR SCRAM PAILVRE OPERATOR PAILS 'To START SLC CROSS CONNRCT TO WIT I RHR SYSTEM UNAVA)LAB(8 CROSS CONNECT TO UNIT 3 RNR SYSTEM UNAVAILABLR OPERATOR FAILS TO IHITIATE SP COOLIHQ CONTAINMENT VENT UNAVAILABLE RPV DEPRESSURIEATION r ~

~ a

~r

~r ~\\ ees eee

~error ~seer ~

error ~ e ee ~

~ a

~r ~

OLFV I 9ls.oa

.36 MKCV 1.908 F 08

,)5 250 RHGV BD 2A UNAVAILABLE 250 V RHOV BD 28 UNAVAILABLR POMER SUPPLY DIVISION I (NAVAILABLR POMER SVPPLY DIVISION li UNAVAILABLS VESSEL LEVEL SICNAL UNAVAILABLS DIV I VBSSSL LOM PRESSURE SICNAL UNAVAIIABLE Dlv 11 VESSEL IX)M PRESSVRE SICNAL lNAVAItABLE DIV I HI RX PRBSS SIGNAL UNAVAILABLE DIV Il HI RX PRESS SICNAL VNAVAILABLR RAM COOLINQ MATER SYSTEM UNAVAILABLE RNRSM PWP Bl (SNlNC FUNP)

VNAVAILABLS RRRSM PUMP Dl (SNINC PVMPl UNAVAltASLE MAIN CONDENSER UNAVAILABLR I CND/CND BSTR PUMP, INCLUDRS SNORT CYCLE VALVE RCIC (NAVAILABLR (C HOURS)

NPCI UNAVAILABl,s (6 BOURS)

VESSEL INJECTION MIT)t CRDNS tNAVAILABLE RNR P(NP h UNAVAILABLR RNR PUHP C (NAVAIIABLS Rl(R PUMP B WAVAILABLE RNR WHP D UNAVAILABLR Vl To tl2 RNR CROSS CONNECT (NAVAILASLR TORUS COOLING HARDMARE (NAVAILABLS CS LOM PRESSVRR INJECTION tNAVAILABLE RNR IA)M PRESSURE INJECTION PATH UNAVAILABt8 eeeeeereeereere

~r rare reer ~ eeeear

~

~r ~\\ ~ ~ ~

~r ~

CROSS CONNECT TO WtT I RNR SYSTEM WAVAILABLS CROSS CONNECT To WIT 3 RNR SYSTEM WAVAILABLS OPERATOR PAILS To INITIATE SP COOLING CONTAINMEHT VSNT UNAVAILABLS 31 LOSS OP RAM COOLING MATER 250 V DC CONTROL POMER fOR 6'Kv SD BD 3ED WAVAILABLR

- 25o v oc coNTRGL pousR toR axv so so lsc AND 680V so Bo 388 CONDITIONS RSLATINQ TO STUCK OPEN SRVS (0 ~ I ~

2a la SORVS)

STATE 0 RELIEF VALVES STVCK OPRN PINY 1.908 ~ 08

.35 WAVAILA UNAVAlLABL e

~

rare 32 MEDIUM LOCA

- RNR PVMP A WAVAILABLS RNR P(NP C UNAVAILABLS RNR PVMP B (NAVAILABLE RNR PUMP D UNAVAILABI.R

~r ~\\ ~\\ ~r ~re ~ra ~

~r ~

33 TOTAL LOSS OP OFPSITR POMER DG A UNAVAILABLE DQ D UNAVAILABLS DQ B UNAVAILABLE DQ C VNAVAILABLE FAILURE TO RECOVER OttSITB POMER IN 30 MINUTES DG 3C WAVAILABLS

- CONDITIONS RSLATINQ To STUCK OPEN SRVS (0, I ~ 2,

.35 OLFV 1.888-08 500 Kv OttSITE CRlb (NAVAllABLS ICl Xv OFtSITR CRIb WAVAILABLE OPSRA'IOR PAILS To RESTORE POMRR To UNIT BOARDS

- 4KV UNIT BD lA UNAVAIIABLR IXV lNIT BO 18 VNAVAILABLS CKV UNIT BD 2A UNAVAIIABLE

- 4KV UNIT BD 28 UNAVAILABLR SNUIDOMN BVS 1 WAVAILASLE PLPX 1.8as 08 lo SORVS)

~

~ r ~ sssss rerresrr rose ererrrreerreeerreree eeeerrerrsaerrre sa aa

~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

aa ~ a

~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~

Figure 8-1 (Page 8 of 26). Top 100 Sequences in Browns Ferry Unit 2 PSA Model

MODE( Mane:

BFNQIN Top-Ranking Sequences Contrlbutlng to Croup s ALL l'requency AL(.

ALL DANAOE STATES EXCEPT SUCCESS 09:56:48 09 HAY )996 Rank Ho.

Sequence Descrlptlon

.Events---------------

Guaranteed Events/Cocnaents End State Prequency Percent (per year)

I 3

n 3

STATE 0 RSLIEP VALVES STUCK OPEN FAILURE TO RECOVER ELECTRIC POMER IN C HOURS I, 2, 3e SORVS)

I, 2 ~ 3i SORVS)

~i~ ~i~iii~ii~iii~i~ii~i~i~i~i~

34 LOSS OP UNIT 2 120V PRRFRRRED POMER CONDITIONS RELATINO TO STUCK OPEN SRVS (0 ~

STATE 0 RELIEP VALVES STUCK OPEN HPCI UNAVAILABLR (8 HOURS)

- RPV DSPRESSURITATIOM VESSEL INJECTION NITH CRDNS UNAVAILABLE i i~i~iii~i

~

3S TURBINE TRIP UNIT 3 HOT AT POMER

- hl)IONATIC/MANUALREACIUR SCRAM PAILURE CONDITIONS RELATIHO TO 511)CK OPEH SRVS (0, STATE 1 RELIEF VALVE STUCK OPEN SHUITOMN BUS 2 WAVAILABLS 4KV SD BD A UNAVAILABLS 480V SHUTDO(ll BOARD 1A 480V RNOV BD lA POMER UNAVAILABLE 480V DIESEL AUX..BD A POMSR WAVAIIASLE 4KV SD BD B UNAVAILABLR 480V SHUIDOMN BOARD 2A 480V RMOV BD 2A POMER UNAVAILABLE 4XV UNIT BD 2C POllER WAVAILABLR 120 V RPS BQS iAi UNAVAILABLE 4KV SD BD C UNAVAILABLS 480V SHUIDOMN BOARD 1$

480V RNOV BD 1B POMER UNAVAILABLE 4KV SD BD D WAVAILABLE 480V SHUIDOHM BOARD 2B 480V RHOV BD 2D POMRR UNAVAILABLR 480V RNOV BD 2R POMER WAVAILABLR 480V RHOV BD 2$

POMER UNAVAILASLS 480V RNOV BD 2C POMER UNAVAILABLE 480V DISSE(

AUX BD B POMER WAVAILABLR 120 V RPS BUS iB'HAVAIIABLE 120 V 18C BUS <<2B>> UNAVAILABLE 4KV UNIT BD 3A WAVAILABLR 4KV UNIT BD 3B WAVAILABLS 4KV SD BD 3EC AHD 480V SD BD 3$ UNAVAILABLE 480V SHUIDOMN BOARD 3B 480V DIESSL AUX BD IEB POMSR UNAVAILABLE RA)i COOLINO HATER STSTEH UNAVAILABLE RRCM PWP B WAVAILABLE RX BUILDING COMPONENT COOLIN) MATER SYSTEM UNAVAILABLE RNRSM PUMP A2 UNAVAILABLE RHRSN PUMP Al (SHING PWP)

UNAVAILABLR RHRSM PUMP Sl WAVAILABLS RNRSM PWP Bl (SNlNG PUNP)

UNAVAILABLE RHRSM PUMP C2 UNAVAILABLR RHRSM PUMP Cl (SNINQ PWP)

WAVAIIABLE PLANT CONTROL AIR SYSTEM UNAVAILABLR DRYMELL CONTROL AIR SYSTEM UNAVAILABLE HSIVS FAIL 'IO REMAIN OPEN I CND/CND BSTR PWP, INCLUDES SNORT CTCLR VALVE UNAVAILASL RCIC UNAVAILABLRLONO TERN HPCI WAVAILABLRLONQ TERN VESSEL INIECTIOH NITH CRDHS UNAVAILABLR FAILURE TO RECOVER 480V RHOV BDS 2A OR 20 RHR PUNP A WAVAILABLR RNR PUMP C UHAVAILAB(E Ul TO U2 RNR CROSS CONNECT UNAVAILABLE RHR PWP B UNAVAILASLR TORUS COOLI)K) HARDMARE UNAVAILABLE FAILURE TO RECOVER TORUS COOLIH2 OPERATOR FAILS TO ESTABLISH SNUIDOMN CODLING

~

~i

~ii ~

~iiii

~iiiii

~i~

~ ~

~ ~ ~

110 V AC UNIT 2 PREFERRED POMER UNAVAILABLE HAIN CONDENSER WAVAILABLR RP)l NARD)(ARE WAVAIIABLR RCIC UNAVAILABLR(8 HOURS)

OPERATOR FAILS TO DEPRSSSURIZR USIHO TBV'8 HIAV iiii~iiiiiiiiiiii

~iii

~i~i ii~ii~

~ ~i

~ ~ ~ ~

~ ~ ~

~ ~ ~ ~i~i

~

OIAV VESSEL IN3ECTION MlTH CRDHS WAVAILABLE 1.8)E 08

.)4 1.98E F 08

.3)

Figure 8-1 (Page 9 of 26). Top 100 Sequences in Bro~vns Ferry Unit 2 PSA Model

HODBI. NaauJs BFNV2H Top-Ranking Sequences Contributing to Croup: ALL Frequency AIL I ALL DAJQGE STATES EXCEPT SUCCESS 07J56:48 09 HAY 1996 Rank No.

sequence Description

-- ~

~ ------

~ Events Guaranteed Events/Ccements End State Frequency Percent fper year)

OPERA1OR tAILS TO CONIROL LPI DURING ATMS

~

~I

~

36 PARTIAl lOSS OF tEBDMATER AVIOHATIC/HANUAI REACIOR SCRAM PAILURB OPERATOR FAILS TO START SLC RPV DBPRSSSURIIATION I.J58-08

~

~ ~ 0

~\\

~I~I~ ~

~ 00 ~I~I

~

~\\

~\\ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~

~

~ ~

~I

~

~ ~

~

I ~ 70K.08

.32 OIAV 1.67E ~ 08 31 HlAV HIAV 1.65E F 08 CIAV I. 61K.08, 30 HIBV 1.56K F 08

.29

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~I 1.5)E-08

.28 HIBV 1,51B ~ 08

.28 HKCV

~ ~ ~ ~ ~ ~

~

P IVX

~

~ ~ ~ ~ ~ ~ ~

1,47B ~08,27 500 KV OFFSITS CRID UNAVAILABLE 161 KV OPPSITS CRID UNAVAILABLE OPERATOR PAILS TO RESIDES POMBR TO WIT BOARDS 4KV UJIIT BD lA UNAVAILABLE 4KV UNIT BD IB WAVAILABLE

- 4KV VHIT BD 2A IJNAVAILABLE 4KV UNIT BD '28 QNAVAILABIE SHVIIXNN BUS 1 WAVAILABLE

- SHUIIOMN BUS 2 WAVAILABLE 4KV UNIT BD 2C POMBR WAVAILABLB

- 4KV SD BD C VNAVAIIABLE 480V SHU1DOMH BOARD 1$

480V RHGV BD 1B POMBR WAVAILABLR 4KV SD BD D WAVAILABLS 480V SHVIDOMM BOARD 2B 480V RHOV BD 2$ REER UNAVAILABLE 480V RHOV BD 2C POMBR WAVAILABLS 480V DIESEL AVX BD B POKER VHAVAIIABLE 37 LOSS Ot COIJDBNSBR VACUNI AVIOHATIC/MANUALREACTOR SCRAM tAILURS CONDfTfONS RELATING TO STUCK OPEN SRVS (0, I, 2, 3> SORVS)

STATB -

1 RELIBP VALVE SIVCK OPEN OPERATOR FAILS 'YO CONTROL I Pf DURII43 ATMS

~I~ 0 ~ ~

0 ~ 00

~I~ 0

~ 00 ~ 0 ~ 00 ~ 0000 ~I~ 0 ~

~ 0 ~ 0000 ~I~ 0

~ 0 ~ 00 ~I~ ~

~

~ ~\\

~ 0

~0000 0000 ~I~I~

~I~I I

~

~ ~

~

38 TURBINB TRIP VESSEL II4JSCTION MITM CRDHS WAVAILABLB AVIOHATIC/MANUALREACIOR SCRAH FAILURE OPERATOR FAILS TO INHIBIT ADS

~\\ ~ 0 ~

~ ~ 00 ~ 00

~I

~I~I~I~ 0 ~ 0 ~I~\\

~ 0 ~

~ 00 ~ 0 ~ 0 ~I~I~I

~ 0 ~

~

~ ~ ~

~ ~ ~ ~

~ ~

~ 0

~ 00 ~ 0 ~

~ ~ ~

~ 0 ~

~ 0 ~I~ 0 ~ 0

~ 00

~

~ 0 ~ ~

~I

~I~I~

~

39 PARTIAL LOSS Ot PERINATER AVIOHATIC/IQNUALRRACIOR SCRAH FAILURE STANDBY I IQUID COÃIROL SYSTEH UNAVAILABLB

- CONDITIONS RELATING TO SYVCK OPEN SRVS lo ~ I, 2 ~ 3.

SORVS)

STATS - 0 RELIEt VALVES STVCK OPEN 0000 ~ 000000000000000000

~ 00 ~ 00 ~\\ ~I 000 ~I~ 00 ~ 00 ~ 00 ~

~I

~

~ I~

~\\

~I

~ 00 00 00

~

0 ~

~I

~

~ ~

~

40

'IOTAL IXJSS Ot PEEDMATER RFM MARDMARE UNAVAILABLE AVIOHATIC/HANVALREACTOR SCRAH FAILURE STANDBY f IQUID CONTROL SYSTEH UNAVAIlABLS CONDfTIOHS RELATING TO S'IQCK OPSN SRVS 10, I, 2>

3 ~ SORVS)

STATS 0 RELIEF VALVES SYQCK OPEN

~ I~

~I 0000 ~ 00 ~ 000000 ~ 000 I~ I~III~ 00000 ~I

~

~I ~

~

00 ~ 00

~ I ~I~

~ 0000

~I

~I 00000 ~

~I

~

~ ~

~

41 1OTAL LOSS Ot tEEDMATER RPN HARINARE UIQVAILABLE AVIOHATIC/MANUALREACIOR SCRAM FAILURE OPERAYOR thlLS TO ESTABLISH TORUS COOLING CONDITIONS RELATING TO STVCK OPEN SRVS lo> I> 2 ~

3 ~ SORVS)

STATE 0 RELIEF VALVES STUCK OPEN RHR PVHP B WAVAILABLE RHR PUMP D UNAVAILABLE 000 ~ 0 ~I~I~ 00 ~I~IIO~ 00 ~ 0

~

~ 0

~I

~

~ I

~ 000 ~ 0 ~I~I~

~ 0 ~I~ 0 ~

~ 0 ~I~ 0 ~ 00 ~ 00000 ~I~ 000 ~I~ 000000 ~

~ 0 ~\\

~I~\\ ~ 0 ~ 00

~ 0 ~

~I~ 0

~ ~ ~ ~ ~ ~ 0 ~ ~ ~ ~ ~

~

~I 42 CLOSURE Ot ALL HSIVS

- NSIVS tAfL TO RBHAIH OPEN AUIOHATIC/IQNVALREACIOR SCRAM tAILURE OPERATOR tAILS '1O COOLDOMN USING TME TBVS CONDITIONS RELATING TO STUCK OPEN SRVS lo, I, 2, la SORVS)

OPERATOR tAILS TO ESTABLISH TORUS COOLIHG STATE 0 RELIEF VALVES Sll)CK OPBN RHR PUMP A UHAVAIlABL' RHR PVHP C UJQVAILABLE

~\\ ~ 00 ~ 00 ~ 0 ~ 00 ~I~I

~

~ I~

~I

~ 0

~

~ 0

~I~ ~\\ ~ I~ ~

~ 0 ~\\ ~ 0

~I~I~

~

~I~

~I

~

43 LOSS OF CONDENSER VACUUM IQIN CONDENSER UNAVAILABLE

- AVIOHATIC/MANUALREACIOR SCRAM tAlllJRE RPV DBPRESSURIBATION OPERATOR FAiLS 'TO START SLC I~\\ ~ 00 ~ ~I~I~ 00

~

I

~

0 ~ 0

~ ~\\ ~ ~I

~I~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~

TOTAL LOSS OP OPPSITE POMBR DG D WAVAILABLE DG C UNAVAIIABLR FAILVRE TO RECOVER OPPSITE POMBR IN 30 HINJIES

- DG 3A WAVAIIABILITY

- DG 3D WAVAILABLE CONDITIONS RELATING 'IO SYVCK OPEN SRVS lo, I, 2, 3 ~

SORVS)

STATB 0 RELIEP VALVES SIUCK OPEN FAILlJRB 'TO RBCOVBR ELECTRIC POMBR IN 6 MOORS Figure B-1 {Page 10 of 26). Top 100 Sequences in Broavns Ferry Unit 2 PSA Model

MODEL Mane:

BPNU2N Top-Ranking sequences contr(bur(ng ro Group

ALL Frequency ALL ALL DAHAGR STATES EXCEPT SUCCESS 09 56i48 09 HAY 1996 Rank No.

Sequence Descr(pc(on

-- ~ - ~ ~ ---------Svenrs-------- ~--~---

Guaranteed Evenr s/CoeIaenrs End Scare Frequency

Percent, (per year)

FFSITS Ol POM Ol, POM SLATING I IEP VAL POMSR ER POR ER FOR TO SYQC VES STU 4KV SD B 4KV SD B X OPEN S CK OPEN D 3SD D 3RC RVS

(

45 TOTAL LOSS OF 0 250 V DC CONTR 250 V DC CONTR CONDITIONS R STATE

~ 0 RE WAV AND 0,

BLS V SD 3v AILA 4$ 0 2 ~

BD IE SORVS)

S WAVAILA-120 V Rl'S BUS <<B" WAVAILABLE 120 V 16C BUS ~28~ Ul(AVAILABLE 4KV UNiT BD 3A WAVAILABLE 4KV WIT BD 3B UNAVAILABLE 4KV SD BD 3EA AND 4SOV SD BD 3A POMSR UNAVAILABIS 4SOV SNUIDOMN BOARD 3A 4$ 0V DIESEL AUX BD 3EA POMSR UNAVAILABLR 4KV SD BD 3SD WAVAILABLE RAM COOLING MATER SYSTEM WAVAILABLE SECH PWP A UNAVAILABLS SSCM PUMP B UNAVAILABLR EECN tUHP D WAVAILABLE RX BUILDING COHPONRNT COOLING MATER SYSTEM UNAVAILABLE RHRSM PUMP B2 UNAVAILABLE RNRSM PWP Dl WAVAILABLR RNRSM PUHP Dl (SHING PUMP) WAVAILABLE PLANT CONIROL AIR SYSTEM UNAVAILABLS DRYMSLL CONIROL AIR SYSTEM WAVAILABLE OPERATOR thILS 'YO RECOVER ERCM (START SMlNG PWP)

NSIVS PAIL YO RENAIH OPEN 3 CND/CND BSTR PWP, INCLUDES SNORT CYCLB VALVE UNAVAILABL RCIC WAVAILABLRIA)NG TERN HPCI UNAVAILABLRLONG TSAH VESSEL INJECTION MITE CRDHS UNAVAILABLE OPERATOR FAILS 'IO MANUALLYSTART RNR/CORE SPRAY RHR PWP h UNAVAIIABLR RNR PUMP C UNAVAILABLR Ql 'IO Q2 RNR CROSS CONNECI'AVAILABLE RNR PUMP B UNAVAILABLE RNR PUMP D UNAVAILABLE Ql 'YO U2 RNR CROSS CONNECT WAVAILABLE OPERATOR FAILS TO ESTABLISH 'IORUS COOl IW RNR LOM PRESSURE INJRCTION PATH UNAVAILABLE

~ 0 ~I

~ 0

~\\ ~ 0 ~

~\\ ~ ISO ~

~ OOOO ~ OSOOOO

~ 0 ~ 0 ~

0 ~

~ 0

~

0 ~ ~I~ ~

~

500 KV OttSITS GRID WAVAILABLR 161 KV OttSITS GRID UNAVAILABLE OPERATOR tAILS TO RSSIORE POWER TO UNIT BOARDS 4KV UNIT BD IA UNAVAILABLR 4KV UNIT BD IB WAVAIIABLS 4KV UNIT BD 2A UNAVAILABLE 4KV UNIT BD IB UNAVAILABLR SNUIDOMN BUS I UNAVAILABLE SNUITOlN BUS 2 UNAVAILABLR 4KV UNIT BD 2C POMSR WAVAILABLE 250 RHOV BD 2A UNAVAILABLS 250 V RHOV BD 2B UNAVAILABLE POMSR SUPPLY DIVISION I UNAVAILABLE POMSR SUPPLY DIVISION 11 UNAVAILABLE VESSEL LSVSL SIGNAL WAVAILASLS DIV I VESSEL IA)M 'PRESSURE SIGNAL UNAVAILABLE DIV 11 VESSEL LOM PRRSSURE SIGNAL UNAVAILABLE DIV'I Hl RX PRESS SIGNAL UNAVAILABLR DIV 11 Hl RX PRESS SIGNAL UNAVAILABLR RAM CODLING MATER SYSTEM WAVAILABLR RNRSM PUMP Bl (SHING PUMP)

UNAVAILABLE RNRSM PUMP Dl (SHING PUMP)

UNAVAILABLE HSIVS FAil TO REHAIH OPEN 1 CND/CND BSTR PUHt, INCLUDES SHORT CYCLE VALVE UNAVAILABI RCIC WAVAILABLR(6 HOURS)

HPCI UNAVAILABLR (6 BOURS)

VESSEL INJECTION NITN CRONE WAVAILABLE TORUS COOLING HARDMARR UNAVAILABLE CS LOM PRESSURE INJECTION WAVAILABLE RNR IA)M PRESSURE INJRCIION PATH UNAVAILABI,E PIHV 1.46E.OS

.27 Figure B-1 (Page ll of 26). Top 100 Sequences in Browns Ferry Unit 2 PSA Model

MODEL Mane c BFNU2H Top.Rank(ng Sequences Conrribuaing ao Qroup I ALL Frequency AL(

ALL DAMAGE STATES EXCEPT SUCCESS OIK66:46 09 HAY 1996 Sequence Descr(pc(on Even'Ls Quaranteed Events/Ccaraenrs End Scale Frequency Percenc (per year) 46 TOTAL LOSS OF OFPSITR POMER DQ B UNAVAILABLE DQ C WAVAILABLS

- tAlLURE TO RECOVER OFFSITS POMER IN 30 MINUTES

- DQ 3A WAVAILABILITY DQ JB WAVAIIABLR CONDITIONS RSLATINQ TO STUCK OPEH SRVS (0, 1, 2. 3i SORVSl STATE 0 RSLlEF VALVES STUCK OPEN tAILURE TO RECOVER ELECTRIC POMER IN 6 HOURS

~ 0 ~

~

0 ~ 0 ~

~ S ~ OOI ~\\ ~ 0 ~I~ 0 ~I~ 0

~

47 46 SCRAM REQUIRED (MANUAL SCRAHS)

AUIOHATIC/MANUALREACIOR SCRAM FAILURE OPERATOR FAILS TO START SLC

~ eo 4

~ OOO ~ 0

~ 0 ~ 0 ~

~I

~I~ 0 ~ 0 0 ~

~\\

~

TOTAL LOSS OF FESDMATER CONDITIONS RELATINQ TO STUCK OPEN SRVS (0, I, 2, 3 ~

SORVS)

STATE - 0 RELIEt VALVES STUCK OPEN VESSEL INJECTION l(ITH CRDNS UNAVAILABLR OPERATOR FAILS TO ESTABLISH TORUS COOLINQ

~I~

~ %11

~

49 TURBINE TRIP MITHOUT BYPASS AUIOHATIC/MANUALRRACIOR SCRAM FAILURE CONDITIONS RE(ATINQ TO STUCK OPEN SRVS lo, I~

2< Ja SORVS)

ILABLR UNAVAILABL RFM NARDMARR UNAVAIIABLR

~ TBVS tAI( TO RELIEVE(MAINTAINRX PRESSURE OPERATOR tAILS 'TO COOIJNMN USINQ THE TBVS VESSEL INJECTION MITH CRDNS WAVAILABLE 600 KV OPPSITE CRID WAVAILABLE 161 KV OttslTE CRIB WAVAILABLS OPERATOR PAILS TO RRS'IORS POMER TO UNIT BOARDS 4KV UNIT BD IA UNAVAILABLE 4KV UNIT BD IB UNAVAIIABLE 4KV UNIT BD 2A WAVAILABIE 4KV WIT BD 2$ UNAVAILABLE SHUIDOMN BUS 1 UNAVAILABLR SNUIDOMN BUS 2 UNAVAILABLE 4KV SD BD B WAVAILABLR 460V SNUIDOMN BOARD 2A 460V RHOV BD 2A POMER UNAVAILABLE 4KV UNIT BD 2C POMER UNAVAILABLE 120 V RPS BUS

~A~ UNAVAILABLE 4KV SD BD C UNAVAILABLE 4$ 0V SNUIDOMN BOARD IB 460V RHOV BD IB POMER UNAVAIIABLE 4KV UNIT BD 3A UNAVAILABLE 4KV UNIT BD 3B UNAVAILABLE 4KV SD BD 3EA A)O 460V SD BD IA POMER UNAVAILABL 460V SNUIDOMN BOARD 3A 460V DIESEL AUX BD 3EA POMER UNAVAILABLE 120 V 16C BUS i2hi WAVAILABLR 4KV SD BD 3RB UNAVAILABLE RA)I COOLINQ MATER SYSTRH UNAVAILABLR RECM PWP A WAVAILABLR EECM PWP B UNAVAILABLR EECN PWP C UNAVAIIABL'E RX BUILDINQ COMPONENT COOLINQ MATER SYSTEM UNAVA RNRSM PU!4P B2 UNAVAIIABLR RNRSM PUHP C2 UNAVAILABLE RNRSM PUMP C1 (SMINQ PUMP) WAVAILABLE HANT CONTROL AIR SYSTEM UNAVAILABLR DRYMELL CONTROL AIR SYSTEM UNAVAILABLE OPERA'IOR PAILS 'IO RECOVER EECM lSTART SM(NQ PWP HSIVS PAIL TO REMAIN OPEN 1 CND/CND BSTR PUHP, INCLUDES SNORT CYCLE VALVE RCIC WAVAILABLELONQ TER)(

NPC( UNAVAILABLELONQ TERN VESSEL INJECTION NITS CRDHS WAVAILABLE OPERATOR 'FAILS TO MANUALLYSTART RNR/CORE SPRAY RNR PUMP A UNAVAILABLR RNR PWP C WAVAILABLE Ul TO U2 RHR CROSS CONNECT UNAVAILABLS RNR PUNP B UNAVAILABLR RNR PWP D UNAVAILABLE U3 TO U2 RNR CROSS CONNECT UNAVAILABLE OPERATOR tAILS TO ESTABLISH TORUS COOL)NO RNR LOM PRESSURE INJECTION PATH UNAVAI(ABLE

~ IOS ~ OOS ~ 0 ~ 0 S ~ 0 ~ $ 0 ~

~ I~ OOS

~

~ 0 RPV DRPRRSSURIYATION HKCV

).49E.08

,27 HLCV 1.45E ~ 06

.22 OIAV 1.4)E ~ oa 22 PICX 1.46E.Oe

-.22 Figure B-1 (Page 12 of 26). Top 100 Sequences in Browns Ferry Unit 2 PSA Model

HOOEL Nenes BFNU2H Top-Ranking Sequences Contrtbuttng to Group c ALL Frequency ALL a ALL DAMAGE STATES EXCEPT SUCCESS 07:56:48 09 HAY 1996 Rank No.

Sequence Description

- ~-------~

Events-.------- ~-----

Guaranteed Events/Ccavaents End State Frequency Percent (per year)

STATE I RELIEF VALVE STUCK OPEN OPERATOR FAILS TO CONIROL LPI DURING ATWS

~

s s

a s ~

a bats

~ a ~

~ s ~\\ ~ ~ a ~ ~ ~

~

~ ~ a ~

50 SCRAM REQUIRED (MANUAL SCRAHS)

AUIOHATIC/HANUALREACIOR SCRAH FAILURE STANDBY LIQUID CONTROL SYSTEM UNAVAILABLE

- CONDITIONS RELATI>>Q TO STUCK OPEN SRVS (0, I, 2. 3.

SORVS)

STATE - 0 RELIEF VALVES STUCK OPEN

$ $ \\aasaasa

$ $ $ sass ~

s

~ sass

~ s

~

aa ~

~\\

~ s 51 TOTAL LOSS OF OFPSITE POWER

- DQ C WAVAILABLE FAILURE TO RECOVER OFFSITR POWER IN 30 HINUTES DQ 3A WAVAILABILITY

- DQ IB UNAVAILABLE RHRSW PWP Cl lSNIHQ PUNP)

UNAVAILABLE

- CONDITIONS RELATINQ TO STUCK OPEN SRVS (0, I, 2.

3$

SORVS)

STATE 0 RELIEF VALVES STUCK OPEN FAIL()RE TO RECOVER ELSCTRIC POWER IN 6 HOURS

~s ~ s ~ s ~ s ~ $ $ ~ s ~ $ $

~ s ~

$ $ ~ $ $ ~ $ $ ~ s ~ s s

~ s ~

52 RECIRC DISCHARGE LINE BREAK, OPERA'TOR FAILS TO INITIATE SP COOLIN)

~ a ~ s ~

~ sass ~ a ~ a ~ s ~ s ~ a ~ a ~ s ~ s s

s ~

~ s ~ s

~ o ~ o ~\\ ~ s ~\\

53 TURBINE TRIP UNIT 3 NOT AT POWER

~ AQIOHATIC/Hl)n)ALRSACTOR SCRAM FAILURE OPERATOR PAILS TO START SLC

~ s ~

~ s ~ $ $ ~ a ~ $ $ ~ s ~ s ~ s

~ s ~ ~ a

~ s ~ s ~

Sl PARTIAL LOSS OF CONOENSATS CONDITIONS RRLATIHQ TO STUCK OPEN SRVS (Or te 2 ~

3$

SORVS)

STATS 0 RELIBP VALVES STUCK OPEN

- RCIC WAVAILABLR(6 BOURS)

HIAV I 40E-OS 26

- 500 KV OFFSITE GRiD UNAVAILASLR 161 KV OFFSITE GRID WAVAILABLE

- OPERATOR FAILS TO RESTORE POWER TO UNIT BOARDS 4KV WIT BD IA WAVAILABLE 4KV UNIT BD IB UNAVAILABLR 4KV UNIT BD 2A UNAVAILABLR

- 4KV UNIT BD 2S WAVAIIABLR SHUIDOHM BQS 1 WAVAILABLE

- SHUIDOMM BUS 2 UNAVAILABLE 4KV UNIT BD 2C POWER WAVAIIABLR 4KV SD BD C QNAVAILABLR 440V SHUTDOWN BOARD IB 440V RHOV BD IB POWER WAVAILABLE

- 4KV WIT BD IA WAVAILABLR

~ KV WIT BD IB UNAVAILASLR 4KV SD BD 3EA AND l40V SD BD 3A POWER WAVAIIABLE 460V SHUIDONN BOARD 3A 460V DIESEL AUX BD 3EA POWER UNAVAILABLE 4KV SD BD 3EB UNAVAILABLS RAN COOLINQ WATER SYSTEH WAVAILABLE ERCN PWP A WAVAILABLR ERCN PUHP B WAVAILABLE ERCN PWP C llNAVAILABLR RX BUILDING COHPONEMI'ODLING MATER SYSTEM UNAVAILABLR RHRSW PUNP B2 QNAVAILABLR PLANT CONIROL AIR SYSTEM WAVAILABLE DRYNSLL COÃIROL AIR SYSTEM UNAVAILABLE OPERATOR PAILS TO RECOVER ERCW (START SHING PUMP)

- HSIVS PAIL TO RN(AIN OPEN I CND/CND BSTR PUMP, INCLUDRS SHORT CYCLE VALVE WAVAILAB RCIC UNAVA'tLABLELONG TERN HPCI UHAVAILABLSLONQ TERN VESSEL INJECTION NIT)t CRDNS WAVAILABLE OPERATOR FAILS TO MANUALLYSTART RHR/CORR SPRAY RHR PWP A QNAVAILABLE RHR PUMP C UNAVAILABLE Ql TO U2 RHR CROSS CONNECT WAVAILABLE RHR PUMP B WAVAILABLR RHR PUMP D WAVAILABLE Ul TO UI RHR CROSS CONNECT QNAVAlthBLE OPERATOR FAILS TO ESTABLISH TORUS CODLING

~

RHR WN PRESSURE INJECTION PATH WAVAILABLS

~

~ $ $ ~ $ $ $ ~ s ~\\ ~ $ $ $ $ $ $ $ $ $ $ ~ s ~ $ $ ~ s ~\\ ~ $ $

~ s

~\\

~

~ ~ ~ o ~

~ a ~ ~ a

~ CONTAINNSNT VENT UNAVAILABLE PIOX 1.378 F 04

.26 OLCV 1.34E ~ 09

.25

~ s ~ o ~ saaas

~\\ ~

~ ssasssaasoaaasas

~\\ ~

~ a ~ a ~ ~ ~ ~ ~ ~

~

~ ~ ~ ~ ~ ~

~ a ~ ~ ~ ~ a

~ ~ ~ ~

~

NKCV RPV DEPRE$ SURIIATION 1.33E.OS

.25 TBVS PAIL TO RELISVEtNAINTAINRX PRESSURE RFW HARDWARE WAVAILABLE OPERATOR FAILS TO DEPRESSURIIR USIHQ TBV'S HIAV 1.30E.04

.24

~

~ s ~ s

~ s

~ s ~ s

~ s

~\\ ~ ~ ~ ~ ~ ~

~ a ~

~ ~ oa

~

~ ~ ~

Figure B-1 (Page 13 of 26). Top 100 Sequences in Browns Ferry Unit 2 PSA Model

0 MODEL Name c BFNltH Top-Rsnktn9 Sequences concrtbuctn9 co Croup s ALL Prequency ALL ALL DAHACS STATES EXCEPT SUCCESS 09c56<48 09 NAY 1996 Rsnk No.

Sequence Description

~ ~ Evenrs Cusrenteed Events/Coecsents Ad Stets Frequency Percent (per teer)

NPCI UNAVAILABLS (6 MOVRS)

RPV DEPRESSURltATION VESSEL INJECTION MITS CRDMS UNAVAILABLE

~

~\\ ~

0 ~ 0 ~ 00 ~I~I~I I~

~

~ ~ ~

~

~ ~ ~I

~I~I~ ~ ~

~ 0 0' I~ I~

~I~ 00 ~ 00 00000

~

~I~ 0 ~\\

~I~ ~

~

~ I

~I~

~ ~ I~ ~ ~I~I~I OLCV I ~ 30K F 08

.24 1.28E.08

.24 OIAV 1.28E.08

.24 1.27E.08

.24 1,27E F 08

.24

- RAN COOLINQ MATER SYSTEM WAVAILABLS PLFV HAIN CONDENSER WAVAILABLR 1 CND/CN) BSTR PWP, INCLUDES SNORT CYCLS VALVE WAVAILABL HPCI UNAVAILABLE(6 BOURS)

RCIC WAVAILABLSIONQ TERN

- VESSRI INJECTION NITS CRDMS UNAVAILABLE RMR PWP B UMAVAILABLR RMR PUMP D WAVAILABLS

- Vl TO U2 RMR CROSS CONNECT UNAVAILABLE OPERATOR tAILS TO ESTABLISH TORUS COOLINQ

~ 0 ~I~I~I~ 00

~I~\\ ~I~ ~ 0 ~I~I~ 0 ~ 0 ~ 00 ~\\

~I~I

~I~ 0 ~

HIBV 1.24E.08 HAIN CONDENSER WAVAILASLS RFM MARDMARE UMAVAILABLR

- OPSRAlOR FAILS TO ESTABLISH 'TORUS COOLING

.23 60 LOSS Ot CONDENSER VACUUM AUIOHATIC/HANV1LREAC(OR SCRAH PAILVRE

- CONDITIONS RELATIMQ TO STUCK OPEN SRVS (0, I, 2, 30 SORVS)

STATS 0 RRLIEP VALVES STUCK OPEN RMR PWP B WAVAILABLS RMR PUMP D UNAVAILABLE

~I~\\ ~ 00 ~ 00 ~I~ 0 ~ 00

~

00

~I~ 00 ~ 000 ~ 000 ~ 000

~ 0 ~I~ 00 ~I~ 0 ~ 0 000 6l TURBINE TRIP HITNOUT BYPASS AUIOHATIC/MANUALREACIOR SCRAH FAILURE

- STANDBY LIQUID CONTROL SYSTEM VNAVAILABLE CONDITIONS RRLATINQ TO STUCK OPEN SRVS (0~

10 1 ~

30 SORVS)

STATS 0 RELIEF VALVES STUCK OPEN I~ OI~ 00000 ~ 0 ~ 000 ~I~\\ ~I~ 000 ~ 0 ~I~ 000 ~ 000 ~ 0 ~I

~ 0 ~ 0 ~

~

61

'IOTAL LOSS OF OttSITS POMSR DQ A UNAVAILABLE CQ D WAVAILABLS DC B UNAVAILABLE DQ C UNAVAILABLE FAILURE 'TO RECOVER OFI'SITR POMER IN l0 HIMVTES COMMON CAVSB COUPLINC OF UNIT I/1 AND UNIT 3 DISSELS UNIT 3 NOT AT POMER CONDITIONS RRLATINC TO STUCK OPEN SRVS (0, I, 2 ~ ls SORVS)

STATS - 0 RELIEF VALVES STUCK OPEN FAILURE TO RECOVER RLECIRIC POSER IN 6 HOURS

~

~I

~ ~ ~

~

OIAV 1.22S.08

.23

- TBVS FAIL TO RELIEVE'tHAINTAIMRX PRESSURE

~

~ 0 ~\\ 0 ~ 0 ~ 0

~ 0 ~I~ 00 ~ 0 I 000 ~

~I~ 00 ~I~ 0 ~I~ 0 ~I~ ~ 00 I~

~ 000

~ 0 ~ 0

~

~I

~ 0 ~\\

~

~ 00

~ 0 ~

~ 0

~

PICX 1.10E ~ 08 500 KV OFFSITE CRID UNAVAILABLE 161 Kv OFFS ITS CRID UNAVAILABL' OPRRAIOR tAILS TO RESTORE POMER TO UNIT BOARDS 4KV UNIT SD 11 UNAVAILABLE 4XV WIT BD 1$ UNAVAILABLE

- 4XV WIT BD 11 UNAVAILABLE

- 4XV UNIT BD 10 UNAVAILASI,R SMVIDOMN BUS 1 UNAVAILABLS

- SNllDOMN BUS 2 WAVAILABLE 4KV SD BD A UNAVAILABLE

- 480V SMVIDOOI BOARD IA 480V RHOV BD IA POMER WAVAILABLS 480V DIESEL AUX. BD A POMER UNAVAILABLE 4KV SD BD B UMAVAILABLS

- 480V SNltDOMN 801RD 2A

- 480V RHOV BD 11 POMRR WAVAILABLE 22 55 NSDIVH LOCA COMIAINNENT VENT UNAVAILABLE OPERATOR PAILS TO INITIATE SP COOLINQ

~I~I

~I~ 0 ~\\ ~ 00 ~I~ 0 ~

~\\ ~

~ 0 ~ 00 00 ~I~ 0 ~I I

~ ~

~

I~

~I~

~

56

'IVRBINE TRiP NIAV VNIT 1 NOT AT POSER AVIOHATIC/MANUALREACIOR SCRAM FAILURE STANDBY LIQUID COMIROL SYSTEM UNAVAILABLS CONDITIONS RELATINQ TO STUCK OPEN SRVS (0, I, 2, 30 SORVSI STATB 0 RELIEF VALVES STUCK OPEN I~I 00 0000 ~ 00 ~I I~

0 ~

~ 00 00 ~ 00 ~ I~ 0 ~ 00 0 ~I

~I~ 0

~ 0

~ 0 ~ ~ ~ ~ ~I~I ~ ~

~ 000 ~ 0000 ~

~I 0 ~\\ ~I~ 0 ~

~ 0 ~ 0 ~I~

~ 0 ~ ~ 0

~ 0 ~

~ ~\\

~ ~

59 LOSS OF CONDENSER VACUUH

- HAIN CON)ENSSR UNAVAILABLR AUTOMATIC/MANUALREACTOR SCRAH PAILVRE RFM MARDMARR WAVAILABLR STANDBY LIQUID CONTROL SYSTEM UNAVAILABLE CONDITIONS RELATINC 'TO STVCK OPEN SRVS (Oe I~ 2r 30 SORVS)

STATE 0 RELIEF VALVES STUCK OPEN

~\\ ~

~I

~ 0 ~I

~I

~ 00 ~I~ 0 ~I~I~I~I~ 00 ~I

~ 00 ~ 000 ~ 0 ~\\ ~I~ 0 ~ 0 ~

~I~I~ ~ ~I~\\ ~

~ 000000 ~ 00 I~ 0 ~

~I~ 0 ~I~\\

~I~ ~ 0 ~ ~ ~I~I~

~ OOOO

~ 000 ~I

~ 00 ~ ~I~

0 ~ 00 0

~

58 MEDIUM IOCA COMTAINNEMT VENT UNAVAILABLR OIAV MICH PRESSURE COOLANT INJECTION SYSTEM WAVAILABLE FAILURE 'IO DEPRBSSURISR VIA TMR SRVS I

~

00

~ 0 00 ~ 0000

~I~ I~\\

~ 0

~ 0 ~I

~ 0

~ 000

~ 0 ~

\\

~ 00000 ~ 00 00

~ 000 000 ~ 0000 0000 ~

~I~ 0

~ 0

~

~ 0 ~

~ 0 ~\\

~ ~

~I

~ ~

59 LOSS OF RAM COOLIIKI MATER SUPPRESSION POOL (TORUS) WAVAILABLE CONDITIONS RSLATINQ TO STUCK OPRM SRVS (0~

10 1 ~

30 SORVSI STATS 0 RELIEF VALVES STVCK OPEN Figure B-1 (Page 14 of 26). Top 100 Sequences in Browns Ferry Unit 2 PSA Model

NOBEL Mane BFNU2H Top-Ranktng Sequences concrtbuctng to Croup c Alt Frequency ALt ALL DAHACE STATES EXCEPT SUCCESS 09r96:4S 09 HAY 1996 ltank No.

Sequence Descrtptlon

~ ~ ~

-Evencs-- ---~-

Guaranteed Events/Comeenta Enc State Frequency Percent tper yearl

~ << ~ <<

~ <<

~

~ ~

~ <<<< ~

~

~ <<<< ~ << ~

63 TOTAL LOSS OF FEEDllATER

~ 4KV WIT BD 2C POMER UNAVAIIABLS 120 V RPS BUS <<A<<WAVAILABLE 4KV SD BD C UNAVAILABLE 490V SNUIDOMN BOARD 18 480V RHOV BD IB POMER WAVAILABLE 4KV SD BD D UNAVAILABLB 490V SNUIIOMN BOARD 28 490V RHOV BD 2D POMER UNAVAILABLR

- 4lov RHOV BD 28 POMER WAVAILABLR 480V RHOV BD 28 POllER WAVAILABLR 4SOV RHOV BD 2C POMER WAVAILABLE 440V DIESEL AUX BD S POMER WAVAILASLE 120 V RPS BUS <<8'NAVAILABLR 120- V 16C BUS <<28<<UNAVAILABLE 4KV UNIT BD 3A UNAVAILABLS 4XV UNIT BD 38 UNAVAIIABLE DO 3A UNAVAILABILITY 4KV SD BD 3EA AND 4SOV SD BD 3A POMER WAVAILABLE 480V SNUIDOMN BOARD 3A 440V DIESRL AUX BD 3EA POMER UNAVAILABLE 120 V 16C BUS <<2A<<UNAVAILABLE DO 3C WAVAILABLE 4KV SD BD 3EC AND 440V SD BD 38 UNAVAILABLE DO 38 UNAVAILABLE

~XV SD BD 388 UNAVAILABLR 4SOV SNUIDONN BOARD 38

~ 40V DISSRl AUX BD 388 POMER WAVAILABLE DO 3D UNAVAILABI8 4KV SD BD 3ED UNAVAIIABLR

- RAM COOLINO MATER SYSTEH UNAVAILABLE EECN PUMP A WAVAILABLR EECM PWP 8 UNAVAILABLS RECM PWP C WAVAILABLE SECN PWP D WAVAILABLE RX BUILDING COHPONENI'OOLINO NATSR SYSTEM UNAVAILABI8 RNRS'M PUHP A2 UNAVAILABLE RNRSM PUHP Al ISlllNQ PWPI WAVAILABLE RNRSM PUNP 82 UNAVAILABLR RNRSM PWP 81 ISllINO PUHPI UNAVAILABLE RNRSll PWP C2 WAVAILABL'8 RNRSM PUMP CI ISMINQ PUHPI WAVAILABLE RNRSll PWP D2 UNAVAILABL'8

- RNRSM PWP Dl ISMINO PUMP) UNAVAIIABLE PLANT CONTROI AIR SYSTEM UNAVAILABLR

- DRYMELL CONIROL AIR SYSTEH UNAVAIIABLE CONTAINHENI'TMOSPHERIC DttllYION OPERATOR FAILS YO RECOVER ESCM ISTART SHINS PUHP)

HSIVS FAIL TO REMAIN OPEN I CND/CND BSTR PWP<<

INCLUDES SNORT CYCt,$ VALVE WAVAIIABL RCIC WAVAILABLELONO TERN HPCI UNAVAILABLSLONQ TERN VESSEL II47ECTION NITH CRDNS UNAVAIIABLE OPERATOR PAILS TO HANUALLYSTART RNR/CORE SPRAY PAILURE 'IO RECOVER 410V RHOV BDS 2A OR 28 RNR PWP A UNAVAIIABLE RNR PUMP C UNAVAILABLS Ul 'IO U2 RNR CROSS CONNECT UNAVAILABLR RNR PUHP 8 UNAVAILABLR RNR PUHP D WAVAILABLE

- U3 'IO U2 RNR CROSS CONNECT WAVAILABLE OPSRAIOR FAILS TO ESTABLISH '1ORUS COOLINO RNR LOM PRESSURE IlQECYION PATH UNAVAILABLE RFM NARDMARR WAVAILABLR HIBV 1.198 ~ Ol

.22 Figure 8-1 (Page 15 of 26). Top 100 Sequences in Broavns Ferry Unit 2 PSA Model

HOOEl Naeei BFNUIH Top Ranking Sequences contr(buctng co Croup

ALL Frequency ALL ALL DAHAQE STATES EXCEPT SUCCESS 07:56>> ~ 4 09 HAY 1996 Rank No.

Sequence Descrtpeton Svenrs----

ouaranreed Events/cove>>ence Rnd Stare Frequency Percenc (per year)

A(IIOHATIC/MANUALREACIOR SCRAM FAILURE

- CONDITIONS RELATINQ TO STUCK OPEN SRVS (0. l. 2, 3>>

SORVS)

STATE 0 RE) IEF VALVES STUCK OPEH RHR PWP A UNAVAttABLS RHR PUMP C WAVAI(A8LE 64 TOTAL LOSS OP OFFSITE POMSR DQ D WAVAILABLE DQ C WAVAILABLE FAILURE TO RECOVER OFP'SITE POMRR 1)l 30 MINUTES DQ 3A WAVAILABILITY RHRSM PWP Dl (SMINQ PUHP)

UNAVAILABLS CONDITIONS RELATINQ YO STUCK OPEN SRVS (0. I, 2, 3>>

STATE 0 RELIEP VALVES STUCK OPEN FAILURE TO RECOVRR ELECIRIC POMER IH 6 HOURS SORVS)

<<<<<< ~ ~ << ~ <<<< ~ << ~ <<

~

65 TURBINE TRIP

~ AUIOHATIC/MANUALREACTOR SC)OH PAILURR CONDITIOMS REIATIHQ 'IO STUCK OPEN SRVS to, I ~ 2, 3>>

SORVS)

STATE I RELIEP VALVE S'IUCK OPEN

~ O'PSRATOR PAILS TO CONTROL LPI DURINQ ATMS OPERA'TOR FAILS 'IO ESTABLISH TORUS COOLINQ 500 KV OPFSITE GRID UNAVAILAB(R 161 KV OFFSITE GRID WAVAILABLE OPERATOR PAILS 'TO RESTORE POMRR TO UNIT BOARDS 4KV UNIT BD lh UNAVAILABLE 4KV UNIT BD 1$ UNAVAILABLR 4KV UNIT BD 2A WAVAILABLE 4KV WIT BD 2$ UlQVAILASLE SHUTDOMN BUS 1 UNAVAILABLE SHUIDOMN BUS 2 WAVAILASLR 4KV UNIT BD 2C POMER UNAVAILABLE 4KV SD BD C UNAVAILABLR 440V SHUIIOMN BOARD 1$

460V RHOV BD 1$

POMSR UHAVAILABLR 4KV SD BD D WAVAILASLE 440V SHUIDOMN BOARD 2$

440V RNOV BD 2$ POMSR UNAVAILABLE

- 460V RHOV BD 2C POMER WAVAILABLR 440V DIESEL AUX BD B POllER UHAVAIIABLR 120 V RPS BUS>>$

WAVAILABLR 120 V ILC BUS <<2B>> WAVAIIABLS 4KV Ul(IT BO 3A UNAVAILABLE 4KV UNIT BD 3$ UMAVAILABLR

- 4KV SD BD 3RA AHD 460V SD BD 3A POMER UNAVAIIABLE 440V SHUIDOMH BOARD 3A 440V DIESEL AUX BD 3RA POMER UNAVAILABLE

- RAM COOLINQ MATER SYSTEM WAVAILABLE SECH

'PUMP A UNAVAILABLE BECM PWP B WAVAILABLR EECN PUHP D WAVAILABLS RX BUILDINQ COMPONENT COOLINQ MATER SYSTEM WAVAILABLE RHRSM PUNP $2 WAVhttABLE

- PLANT CONTROL AIR SYSTEM WAVAILABLE DRYMELL CONTROL AIR SYSTEM UNAVAILABLE OPERATOR PAILS TO RECOVER EECM (START SMtNQ PWP)

NSIVS FAIL 'TO REMAIN OPEN I CHD/CND SSTR PWP>>

INCLUDSS SHORT CYCLE VALVE UNAVAILABL RCIC WAVAILABLRIX)NQ TERN HPCI UNAVAILABLELONQ TERN

- VESSEL INJECTION NITH CRDHS WAVAILABLE OPERA'IOR FAILS TO MANUALLYSTART RHR/CORE SPRAY RHR PUMP h UHAVAILASLE RHR PUMP C UNAVAILABLR Ul 'IO U2 RHR CROSS COHNSCF UNAVAILABLS RNR PWP B UNAVAILABLE RHR PUHP D WAVAILABLE

. U3 'IO U2 RHR CROSS COHNSCT WAVAILASLS OPERATOR FAlLS TO ESTABLISH TORUS COOLINQ

- RHR (DM PRESSURE 1)(JECYION PATH UNAVAILABt,R

<< ~ << ~ << ~ << ~ << ~ >> ~

~

\\

~

~ ~

~ <<

- VESSEL INJECTION MITH CRDHS WAVAIIABLE PIGX

~

~ ~ ~ ~ ~ ~ ~ ~ ~

l.l6$.06

.22 OIAX 1.14E-04

.21 66 LOSS OF RBCCM

~ AUIOHATIC/MANUALREACTOR SCRAM FAILURE OPERATOR PAILS 'IO START SLC RX SUILDIHQ COMPONENT COOL)NO MATER SYSTEM UNAVAILABLR NKCV 1.12E ~ 04 21 DRYMELL CONTROL AIR SYSTEH UNAVAILABLE

- NSIVS FAIL TO REMAIN OPEN Figure B-1 (Page 16 of 26). Top 100 Sequences in Browns Ferry Unit 2 PSA Model

MODEL Bane

< BFNUlH Top Ranking Sequences Contr(but(ng to Group J ALL Frequency ALL ~ ALL DAHAGS STATES EXCEPT SUCCESS 0/c56J48 09 HAY 1996 Rank No.

Sequence Des<<rlptlon

Events---------------

Guaranteed Events/Conoents End State Frequency Percent (per year) 68 LOSS OF RAM COOLING MATER CONDITIONS RELATING TO STUCK OPEN SRVS (0 ~

1 ~

2 30 SORVS)

STATE - I RELIEF VALVE STUCK OPSB OPRRATOR FAILS TO START CS/LPCI OR TO ESTAB TORUS VRNY

~

0

~

~ 0 0

000000 ~ 000 ~ 0 ~

~ 0 0

0$

00 LOSS Ot RAM COOLING MATER UNIT 3 NOT AT POMER CONDITIONS RELATING TO STUCK O'EN SRVS (0

ly 1 ~

3 ~ SORVS)

STATS 0 RRLIR'F VALVES STUCK OPEN RCIC WAVAILABLE (6 HOURS)

HPCI WAVAILABLRl6 HOURS)

RPV DSPRESSURIEATIOH LOSS OF RAM COOLING MATER DIV I VESSEL LOM PRESSURE SIGNAL UNAVAILABLE DIV Il VESSEL LOM PRRSSURR SIGNAL UNAVAILABLE CONDITIONS RELATING IO STUCK OPEN SRVS l0 I~

1 ~

30 SORVS)

STATE 1" RELIEF VAlVE STUCK OPEN RPV DEPRESSURISATION

~

0 ~

~

~ ~ ~ ~

~

~ ~\\ ~

~

RAM COOLING MATER SYSTEM UNAVAILABLE HAIN CONDENSER UNAVAILABLR I CND/CND BSTR PUMP, INCLUDES SHORT CYCLE VALVE UNAVAILABL VSSSEL INJECIION NITN CRDMS WAVAILABLE RAN CODLING MATER S'YSTEH WAVAILABLR

- HAIN COMDRNSSRIVAILABLE 1 CND/CND BSTR PUMP, INCLUDES SNORT CYCLE VALVE UNAVAILABL VESSEL INJECTION M(IN CRDBS WAVAILABLE RAM COOLING MATER SYSTEM UNAVAILABLE HAIN CONDENSER UNAVAILABLR

- 1 CND/CND BSTR

PUMP, INCLUDES SHORT CYCLE VALVE WAVAILABL VESSEL INJECTION NITN CRDNS UNAVAILABLE CS LOM PRESSURE INJECTION WAVAILABLR RMR IX)M PRESSURE INJECTION PATH UNAVAILABLE OIAV H(AV OIAV I ~ 08S ~ 08

.20 1.05E ~ 04

.20 1.05E.08

.20.

~ 0 ~

~ 0 0 ~ 00 ~ 0 ~ 000 ~ 00 ~ 0

~ 0 ~ 0

~

~ 0

~

~ 0 ~ 00 0 ~ 00 ~ 0 ~ 0 0 00 ~ 000 0 0000 00 00000000

~ 0 000 ~ 0 ~ 0 ~ 0 ~ 00 ~ 0 ~

~ 0

~ ~

~

I OO 90

'IURBINR TRIP MITMOUT BYPASS

- AUIOHATIC/MANUALREACIOR SCRAM PAILURE CONDITIONS RELATING TO STUCK OPE)l SRVS l0, 1, 2, 3 ~ SORVS)

STATE 0 RRLIRP VALVES STUCK OPEN RNR PWP B UNAVAILABLE RMR WHP D WAVAILABLR

~

~i~ 0 ~ ~ 0

~ 00 ~ 0 ~ 0 F 00 00

$ 0 ~ 000000 ~ 000 ~ 0 ~ 0 ~ 0 ~ 0 ~ 0 YI TOTA(

LOSS OP OFFSITS WMER DG A UNAVAILABIR DO B WAVAILABLR DO C UNAVAIlABLE tAILURE 'IO RECOVER OttSITE PURER IN 30 HINUTES RHRSM PUMP Bl (SNIHG PUMP)

UNAVAILABLE

- COJJDITIONS RELATING TO STUCK OPEN SRVS (0, 1, 2, 3a SORVSI STATS 0 RELIEF VALVBS STUCK OPEN thILURE TO RECOVER RLECTRIC POMER IN 6 HOURS TBVS PAII TO RELIEVE%MAINTAINRX PRESSURR

- OPERATOR tAILS YD COOLDOMN USING TNS TBVS OPERA'IOR PAILS 'IO ESTABLISH TORUS COOLING MIBV 1.04E-08

.19

~ii~\\ ~ 0 ~ 0 ~ 0 ~

~ 000 ~ 0 ~Oiiii~ 0 ~ 0 ~ 0

~ 0 ~ 0 ~ 0 ~ 0 ~i~ ~ 0 ~\\

0 ~ 0 ~ ~ ~ ~ 00 ~

~ ~ ~ 0 ~ 0 ~

~ ~ ~ ~ ~ ~ 0 ~ ~ 0 ~ 0 ~

~ ~

~

PLFV 1.01S.04 500 KV OFPSITR GRID WAVAILABLE 161 KV OPtSITR GRID UNAVAILABLE OPERATOR tAILS TO RESTORE POMER TO WIT BOARDS 4KV WIT BD IA WAVAIIABLE 4KV UNIT BD IB WAVAILABLR 4KV WIT BD 2A WAVAILABLR 4KV UNIT BD 2B WAVAILABLE SMUIDOMN BUS I UNAVAILABLE SIJIDOMN BUS 2 WAVAILABLE 4'KV SD BD A WAVAILABLR 480V SMUIDOMN BOARD IA 440V RHOV RD lh WMER UNAVAILABLE 480V DIESEL AUX. BD A POMER UNAVAIIABLE 4KV SD BD B UNAVAILABLR

- 440V SNUYDOMN BOARD 2A 480V RHOV BD 2A POMER WAVAILABLE 4KV UNIT SD 2C POMER UNAVAILABLE I'20 V RPS BUS ihi UNAVAILABLE 4KV SD BD C WAVAILABLR 480V SMUIDOMN BOARD Ib 480V RHOV BD IB POMER UNAVAILABLE

~ KV UNIT BD 3A UNAVAILABLR 4KV UNIT BD 3B UNAVAILABLE

- RAM COOLING MATER SYSTEM UNAVAILABLE SECH WNP B WAVAILABLE RMRSN PWP A2 WAVAILABLE

- RHRSN PUMP Al lSMING PUHP) WAVAIIABLR RMRSM WHP B2 WAVAILABLE RXRSM WHP Cl UNAVAILABLE RMRSN WHP Cl lSMING WHP) WAVAILABLE PLANT CONTROL AIR SYSTEM UNAVAIIABLE DRYNELL CONTROL AIR SYSTEH UNAVAILABLE HSIVS PAIL TO REMAIN OPEN 1 CND/CND BSTR PUMP, INCLUDES SNORT CYCLE VALVE WAVAILABL RCIC WAVAILABLELONG TRR)4

~ 19 Figure B-1 {Page 17 of 26). Top 100 Sequences in Browns Ferry Unit 2 PSA Model

HOOEL Nano>

BFNUIH Top Ranking Sequences Contributing to Croup i ALL Frequency ALL ALI, DAHACE STATES EXCEPT SUCCESS 07r$ 6:4$

09 HAY 1996 RanR No.

Sequente Descrlptlon

Events------------~--

Guaranteed Events/Coeraents End State Frequency Percent (per yearl 92 TOTAL LOSS OF OPPSITR POMER FVSL OIL SYSTEH FOR DIRSEL A UNAVAILABLR FVEL OIL FOR DIESEL D UNAVAILABLE FUEI OIL SYSTEH fOR DIESEL 8 UNAVAILABLR FUEL OIL SYSTEH FOR DIESEL C VNAVAILABI8

- FAILURE TO RECOVER OFPSITR POMER IN 30 HINVTES COHHON CAUSR COUPLINC Ot WIT I/2 AND UNIT l DIESELS CONDITIONS REIATING TO STUCK OPEN S'RVS I0~ I ~

2 ~

3 a SORVSI STATE - 0 RELIRt VALVES STUCK OPEN PAILURE 'TO RECOVER ELECIRIC POMER IN 6 HOURS HPCI WAVAILABLELONG TERN VESSEL INJECTION MilliCRDNS UNAVAILABLR RNR PUMP A UNAVAILABLE RNR PUHP C UNAVAILABLE Ul TO V2 RNR CROSS CONNECI'AVAILABLE RNR PUMP 8 VNAVAILABLR TORUS COOLINC NARDMARE UNAVAILABLE FAILURE TO RRCOVER TORUS COOLINC OPERATOR FAILS 'TO ESTABLISH SMUIIIOMN COOLING

~

~ oe

~ se ~ ~ ~ ~ ~ s ~

aces@

~ oo

~ ~

~

~ aoe ~

~ aA

~ ~ ~ ~ ~ ~ ~ ~ ~

~

SOO KV OFFSITE CRID WAVAILABLE PIGX I 01E 0$

l9 161 KV OFtSITR CRID WAVAILABLE OPERAIUR FALLS TO RESTORE POMER TO UNIT BOARDS 4KV WIT BD IA WAVAILABLR 4KV WIT BD IS WAVAILABLR 4KV UNIT BD 2A UNAVAILABLR 4KV WIT BD 28 WAVAILABLR SNVIDOMN BVS I UNAVAIIABIR SNlllDOMN SUS 2 WAVAILABLR DG A WAVAILABLE DG D WAVAILABLS DC 8 WAVAILABLR DC C UNAVAILABLR 4KV SD BD A WAVAILABLR 4$ 0V SNVIDOMN BOARD IA

~ $ 0V RHOV BD IA PURER WAVAILABLR 4$ 0V DIESEL AUX. BD A POMRR UNAVAILABLR 4KV SD BD 8 UNAVAILABLR 4$ 0V SNVIDOMN BOARD 2A 4$ 0V RHOV BD 2A POMRR UNAVAILABLE 4KV WIT BD 2C POMRR UNAVAILABLE 120 V RPS BUS A

WAVAfLABLE 4KV SD BD C UNAVAILABLE 4$ 0V SNVIDOMN BOARD IB 4$ 0V RHOV BD IS POMER UNAVAILABLR

~ KV SD BD D WAVAILASLE 4$ 0V SNVIDOMN BOARD 28 4$ 0V RHOV BD 2D POMER UNAVAILABLE 4$ 0V RHOV BD 28 POMRR UNAVAILABLE 4$ 0V RHOV BD 28 POMER UNAVAIIABLR 4$ 0V RHOV BD 1C POKER UNAVAILABLR 4$ 0V DIESEL AVX BD 8 POMER UNAVAILABLE 120 V R'PS BUS aB'NAVAIIABLR 120 V ICC BVS a28'AVAILABLE

~ KV UNIT BD 3A UNAVAILABLE 4KV WIT BD 38 WAVAIIABLE PVEL OIL SYSTEN FOR DIESEL 3A UNAVAILABLE DC 3A UNAVAILABILITY 4KV SD SD 3EA AND 4$ 0V SD BD 3A POMRR UNAVAILABLE 4$ 0V SNVIDOMN BOARD 3A 1

4$ 0V DIRSRL AUX BD 3EA PONER UNAVAILABLR 120 V 16C BUS <<2Aa UNAVAILABLR FUEL OIL SYSTEH FOR DIESEL 3C UNAVAIIABLR DC 3C WAVAIIABLR 4KV SD BD 3EC AND 4$ 0V SD BD 38 UNAVAILABLR FVEL OIL SYSTRH FOR DISSRL 38 UNAVAILABLE DC 38 WAVAILABLR 4KV SD BD 3$8 WAVAILABLR 4$ 0V SNVIUOMN BOARD 38 4$ 0V DISSRL AUX BD 388 POMER UNAVAILABLR PURL OIL tOR DIESRL lD UNAVAIIASLE DG 3D UNAVAILABLE 4KV SD BD 3ED WAVAffABLE RAM COOLIHO NATER SYSTEN UNAVAILABLR Figure 8-1 (Page 18 of 26). Top 100 Sequences in Browns Ferry Unit 2 PSA Model

MODEL Mane<

BFNV2H Top Rank(ng Sequences Contr(butlng to Croup s A(.L Frequency ALL ~ AL(

DAMAGE STATES EXCEPT SUCCESS 01:56: ~ 8 09 HAY 1996 ca co Rank No.

Sequence Descript(on

~

- ~ ~

--Events Cuaranteed Events/Coelaents End State Frequency Percent (per year) ca

~Js

'ua 13 LOSS OP RBCCN CONDITIONS RELATING 'IO STUCK OPEN SRVS (Oi STATS 0 RRLIEP VALVES SIVCK OPEN RCIC VNAVAILABLS (C HOURS)

HPCI UNAVAILABLE (6 HOURS)

RPV DEPRRSSURIEATION VESSEL INJECTION M(2M CRDMS UNAVAILABLE 16 CLOSURE Ot ALL HSIVS UNIT 3 NOT AT POMER AVIOHATIC/MANUALREACIOR SCRAM PAILURR OPERATOR FAILS 'IO START SLC I~ 2, 3a SORVS)

EECM PVHP A UNAVAILABLS SECM PWP B UNAVAILABLE EECM PUMP C UNAVAILABLR EECM NNP D WAVAILABLS RX BUILDING COMPONENT COOLING MATER SYSTEM UNAVAILAB RHRSM PWP A2 WAVAIIABLS RMRSM PVHP Al (SMING PUMP) UNAVAIIABLE RMRSM PUMP $2 VNAVAILABLS RNRSM PUMP Bi (SHING PVHP) WAVAIIABLE RNRSM PUMP C2 UNAVAILABLE RNRSM PUHP Cl (SMINC PWP)

WAVAILABLS RMRSM PWP D2 VNAVAILABLE RNRSM PUMP Dl (SMING PlNP)

UNAVAILABLE PLANT CONIROL AIR SYSTEH UNAVAILABLE DRYMELL CONTROL AIR SYSTEM UNAVAILABLR CONTAINMENT ATMOSPHERIC DILUTION OPERATOR FAILS TO RECOVER EECN (START SMINC PVHP)

HSIVS tAIL TO REMAIN OPEN I CND/CND BSTR PUMP, INCLUDES SNORT CYCLE VALVE'U)

RCIC UNAVAILABLRLONG TERM HPCI UNAVAILABLELONG TERN VESSEL INJECTION MITH CRDNS UNAVAILABLE OPSRATOR PAILS TO MANUALLYSTART RNR/CORE SPRAY PAILVRR TO RECOVER 880V RHOV BDS 2A OR 2B RHR PUMP A UNAVAILABLS RHR PUMP C UNAVAILABLS Ul 'lY) U2 RMR CROSS CONNRCP UNAVAILABLE RMR PWP B WAVAILABLE RMR PUMP D WAVA(LASLS

- U3 TO U2 RMR CROSS CONNECT WAVAIIABLE OPERATOR FAILS TO ESTABLISN TORUS COOLING RNR LOM PRESSURE INJECTION tATH UNAVAILABLR lAVAIIABL HSIVS PAIL TO REMAIN OPEN RPV DEPRESSVRIZATION RX BVILDING COMPONENT COOLING MATER SYSTEM UNAVAILABLE DRYMSLL CONIROL AIR SYSTEM WAVAILABLE HSIVS FAIL TO REMAIN 0'PEN RFM MARDMARE UNAVAILABLS OPERATOR FAILS 'TO INHIBIT CLOSURE OP MS(VS ON LEVEL HIAV

9. 89E ~ 09

~ 18 9.66E 09

.18 15 CLOSURE OF ALL HSIVS 250 V DC CONTROL POMER fOR 4KV SD BD 3ED UNAVAILABLR 250 V DC CONTROL POMER POR eKV SD BD 3$C AND ~ 80V SD BD 388 CONDITIONS RELATING TO STUCK OPEN SRVS (0, 1, 2, 3v SORVS)

STATS 0 RELIRP VALVES STUCK O'PSN Ul TO U2 RNR CROSS CONNECT UNAVAILABLS DNAVAILA 250 RMOV BD 2A UNAVAILABLE 250 V RMOV BD 2B VNAVAILABLS POMER SUPPLY DIVISION I UHAVAILABLE POMER SUPPLY DIVISION 11 UNAVAIIABLE VESSEL LEVEL SIGNAL UNAVAILABLR DIV I VESSEL LON PRESSURE SIGNAL UNAVAILABLE DIV 11 VESSEL Ir)M PRESSURE SIGNAL WAVAILABLE DIV I HI RX PRESS SIGNAL UNAVAILABLE DIV 11 Hi RX PRESS SIGNAL WAVAILABLE HSIVS tAIL TO REMAIN OPEN RFM HARDMARE VNAVAILABLR RCIC WAVAILABLS (6 MOORS)

HPCI UNAVAILABLS (6 NOVRS)

OPERATOR FAILS TO IlOIIBITCIX)SURE OP MSIVS ON LEVEL

'MR NNP A UNAVAILABLE RMR P(NP C UNAVAILABLS RNR NNP B UNAVAILABLE RHR PUMP D UNAVAILABLR PIFV 9.60E ~ 09

.18 Figure 8-1 (Page 19 of 26). Top 100 Sequences in Browns Ferry Unit 2 PSA Model

MODE( Nasa>

BFMUIN Top.Ranking Sequences Contr)but(ng to Group

ALL Frequency ALL ~ ALI. DAMAGE STATES EXCEPT SUCCESS Ol:56res 09 HAY 1996 Rank Mo.

Sequence Description

~Events-Guaranteed Events/Ccevnents End Frequency I'ercent State (per year) 76 LOSS OP CONDENSER VACUUM AUTOMATIC/MANUALREACIOR SCRAM FAILURE

- CONDITIONS REIATING TO STUCK OPEN SRVS (0, I, 2. 3.

SORVS)

STATE 0 RELIEF VALVES STUCK OPEN RNR PUHP A WAVAILABLE RMR PWP C UNAVAILABLE TORUS COOLINQ NARDMARE UNAVAILABLE PAILURS YO RECOVER 'IORUS COOLlNG RMP. LOM PRESSURE INJECTION PATH UNAVAIIABLE OPERATOR FAILS 'IO START CS/LPCI OR TO ESTAB TORUS VENT HAIN CONDENSER WAVAIIABLR RFII NARDMARE UNAVAIIABLS OPERATOR PAILS TO ESTABLISH TORUS COOLlNG HIBV 9.67E.09

.14 71 CURB SPRAY LINE BREAK ONS CORE SPRAY LOOP FAILS TO INJSCT RMR PUMP B UNAVAILABLE RMR PUMP D UNAVAILABLE CROSS CONNECT TO UNIT 3 RNR SYSTEN UNAVAILABLE RNR LPCI INJECTION PATH UNAVAILABLE CONTAINNSMT VENT WAVAIIABLE OIAV 9,1SE ~ 09

.11 CROSS CONNECT TO UNIT 1 RNR SYSTEN WAVAILABLR RNR LPCI INJECTION PATH UNAVAILABLE CONTAINMENT VENT UNAVAILABLE 79 40 41

~ v

~

0

~

43 TURBINB TRIP AUTOMATIC/MANUALREACIOR SCRAM FAlLURE OPERATOR FAILS TO START SLC CORE SPRAY LINE BREAK ONS CORE SPRAY LOOP PAILS TO INJECT RMR PUMP A UNAVAILABLS RNR PUMP C UMAVAILABLS

~\\

~ 0

~

OO ~

~

0%

0 ~ 0 ~

~ 0 ~ IO~ 0 ~I~ 0 ~ ~I~ 0

~ 1$ ~ 0 ~ v ~\\ ~ 0

~

~ 0 ~

0

\\

0 ~ 0 ~

~

~ IO

~

TURBINR tRIP

~

- VESSEL INJECTION NITN CRDNS WAVAIIABLE AllIONATIC/MANUALREACTOR SCRAN FAILURE

- CONDITIONS RSIATIHG TO STUCK OPEN SRVS (0, I, 2, 3 ~ SORVS)

STATR 1 RELIEF VALVES STUCK OPEN OPERATOR FAILS TO COMIROL LPI DURING AIMS

~ 0 ~ v

~ 0 ~ ~ v ~I

~ S ~ v ~I~ 0 ~

~ 0 ~ ~

~ 0 ~ IO~

~ ~ 0 ~\\

~I~ 0

~ 0

~ 0 ~ 0 ~

~ ~ ~

~ 0 ~ 0$ ~

~ OO

~ 0 ~\\

~

OO ~\\

~ 0

~\\

~ 0

~

~ ~ ~ ~ ~ ~ ~ 0 ~ ~ ~

~ ~ ~ ~ ~ ~ ~

FIEDMATSR RANPUP INITIATOR IS BOC,

FMRU, PRFOPEM AUIONATIC/NA)IALREACTOR SCRAM FAILURE INITIATOR IS FHRU CONDITIONS RELATING TO STUCK OPEN SRVS (0, I~ 1, 3 ~

SORVS)

RFN NARDMARS WAVAILABLR STATS I RELIEF VALVE STUCK OPEN VESSEL INJECTION MITE CRDMS UNAVAILABLS OPERATOR FAILS TO CONTROL LPI DURING ATMS

~\\ ~ $ 0 0 ~ $ 0 ~ 0 ~ 0 ~ ~

~ 0

~ 0 ~ OP ~ 0

~ 0 ~ v ~ S ~ PO OO I~ 0 ~ OO ~ 0 ~ 0 ~ 0 ~\\

~ 0

~ ~ ~ ~ 0 ~ I

~

~ v ~

~ ~ ~

CLOSURE OF ALL HSIVS HSIVS FAIL 'IO REMAIN OPEN

- WIT 3 NOT AT POMER RFM HARDMARS UMAVAIIABLR

- CONDITIONS RELATING TO STUCK OPEN SRVS (0, I> 1.

Ja SORVS)

OPERATOR FAILS TO INHIBIT CLOSURE OF HSIVS ON LEVEl.

STATE 0 RELIEF VALVES STUCK OPEN RCIC UNAVAILABLS ls MOURS)

NPCI WAVAILABLEl6 HOURS)

- RPV DSPRSSSURIIATION VESSE(

I)QECTIOM NITN CRUMB WAVAIIABLE

~

~ 0

~I~ ~

~ ~

~ 0 ~ 0

~ 0 ~ v ~ ~ 0

~I~ 0

~ 0 ~ v ~

~I

~

~I~ IOOI

~ 0 ~

~

~ OO

~

~ ~

~

~ 4 LOSS OP RAN COOLING HATER 250 V RNOV BD 2$ UNAVAIIAB)E 250 V DC CONTROL'POMER POR eKV SD BD JEC AMD ~ 40V SD BD JEB WAVAILA POMER SUPPLY DIVISION I UNAVAILABLE POMER SUPPLY DIVISION 11 WAVAILABLS VESSEL LEVEL SIGNAL WAVAILABLE CONDITiONS RELATING TO S'IUCK OPEN SRVS (0 ~ I ~

2 ~

3 ~

SORVS)

DIV I VESSI(

LON PRESSURE SIGNAL UNAVAILABLE STATE 0 RS( (SF VALVES STUCK OPEN DIV Ii VESSEL LOM PRESSURE SlGNAL UNAVAILABLE DIV I Hl RX PRRSS SIGNAL WAVAIIABLE DIV 11 NI RX PRESS SIGNAL WAVA11ABLE RAH COOLING MATER I'YSTEH UNAVAILABLS RNRSM PWP Bl lSNINQ PUMP) WAVAILABLR HAIN CONDENSER WAVAILABLR CND/CND BSTR PWP, IMCLUDBS SHORT CICLE VALVE UNAVAI RCIC UNAVA'ILABLE (6 HOURS)

HPCI WAVAILABLS l6 HOURS)

VESSEL INJECTION MITE CRDNS WAVAIIABLE RMR PWP A WAVAILABLR

- CS IA)M PRESSURE 1)QRCTIOM WAVAIIABLE RMR LOM PRSSSURS INJECTION PATH WAVAILABLE

~ ~ JI ~

ov ~

~

~\\

~ 0 ~

~ ~

RPV DRPRRSSURIZATION OIAV 9.14S ~ 09

.11 OIAV 9.1eS 09 IY OlAV 4.41S ~ 09 NIAV 4.5as-09

. 16 P IMV

~ ~ ~

~ 0 ~ ~

4.53'9

.16 HXCX 4.51S.09

.16 Figure B-1 (Page 20 of 26). Top 100 Sequences in Browns Ferry Unit 2 PSA Model

MODEL Na>ae>

BFWIH Rank No.

Sequence Descr(pt(on Top Ranking Sequences Contr(butlng to Group

> ALL Frequency ALI e ALI. DAMAGE STATES EXCEPT SUCCESS

~

~ Euents

~ ~

Guaranteed Events/Coen>ants End State 07:56:id 09 HAY 1996 Frequency Percent (per year) 84 TOTA(

LOSS OP OFFSITE POMER UNIT 3 NOT AT PO>IER

- CONDITIONS REIATING TO STUCK OPEN SRVS (0. I, 2>

3>

SORVS)

STATS 0 RELIEF VALVES STUCK OPEN RCIC UNAVAILABLE (6 HOURS)

NPCI UNAVAILABLS (6 MOORS)

RPV DEPRESSURISATIOM 500 KV OFFSITS GRID WAVAIIABLE 161 KV OFFSITS GRlD UNAVAILABLS OPERATOR PAILS TO RESTORE PONER TO UMlT BOARDS

- 4KV UNIT BD IA UNAVAI(ABLE 4KV UNIT BD 18 UNAVAIIABLS 4KV UNIT BD 2A WAVAILABLR 4KV UNIT BD 28 UNAVAILABLE SNUIDONM BUS 1 WAVAILABLR SNUIDONM BUS 2 WAVAIIABLE 4KV UNIT BD 2C PONER WAVAILABLE RAN COOLING MATER SYSTEM UNAVAIIABLB ItSIVS FAIL TO REMAIN OPEN 1 CND/CND BSTR PWP, INCLUDSS SHORT CYCLE VALVE UNAVAILABL VESSEL INJECTION MITE CRDNS UNAVAILABLE HIAV 8 ~ 238'9 AD )5

~ >

~

~ $ 1 ~ 0 ~I

~ OO ~ 0 ~I~ > ~ ~I~ ~\\ ~ OO

~ > ~

~ 0 ~

~ > ~ 0 ~

OO ~ OO OO

~ 0 ~

~ 0 ~ 0 OOO ~ 0 ~ 0 ~ <

~ 0

~ ~ ~

85 TURBINE TRIP AUTOHATIC/MANUALREACIOR SCRAM PAILURE STANDBY LIOUID CONTROL SYSTEM UNAVAILABLR CONDITIONS RELAT'ING TO STUCX OPEN SRVS (0> I ~

2 ~

3 ~ SORVS)

STATS - 0 RRLIEP VALVES STUCK OPEN HIAE

~ ~

~

8.208 09

.15

~ o

~ 0

~

1 ~ 0

~

~ ~ ~

~

0 ~

~

~ ~ ~ > ~ ~ ~

~ ~ ~

~

86 TURBINE TRIP MITHOUT BYPASS AUIOHATIC/HAWALREACTOR SCRAM FAILURE CONDITIONS RELATING TO STUCK OPEN SRVS (0, I 2,

3 ~ SORVS)

STATE 0 RELIEF VALVES STUCK OPEN RMR PUH'P A UNAVAILABLE RNR PWP C UNAVAILABLS TBVS PAIL TO RELIEVE'(MAINTAINRX PRESSURE O'PERATOR FAILS 'IO COOLDOIN USING TNE TBVS OPERATOR PAILS TO ESTABLISN TORUS COOLING HIBV 7.96E-09

. )5

~

I

~

~\\

~ 0 ~

0 ~ 0 ~ O<OO OOO

~ 0 ~

~

OOSOOIOOOO ~ 0

~ 0 ~ OIOO ~ 0 0 ~

~ OOOO OO ~

~ OO ~

~

~I 4'7 LOSS OP RAM COOLING MATER UNIT 3 NOT AT PONSR CONDITIONS REIATING TO STUCK OPEN SRVS (0>

I>

2>

STATB I RELISt VA(VE STUCK OPEN OPERATOR FAILS TO ESTABLISH TORUS COOLING 0 ~ 0 ~ > ~ OPS

~

~ 0 ~ 0 ~ 0 ~ 0 ~ 0

~ IO~ > ~ OO ~ 1 ~ OO

~ 0 ~\\ ~

~

88 FEEDNATBR RAHPUP AUIOHATIC/ICUIUALREACIOR SCRAM PAILURE OPERA'IOR FAILS 'IO START SLC

~ S ~ 0 ~ ~ 00 ~Iio~ $ 0 I $ $ ~ 0 ~ 0 ~I~ 0 ~\\ ~ 0 ~\\

~ 0 ~ ~\\ ~

~

89 CLOSURE OF AL( MS(VS CONDITIONS RELATING TO STUCK OPEN SRVS (0, I, 2, STATB 3 OR HORS VALVES STUCK OPEN OPERATOR FAILS TO ESTABLISH TORUS COOLING

~ 0

~

~ 0 ~\\

~ 0 ~ 0

~

~ ~

90 FLOOD FROM TNE TORUS CONDITIONS RS(AT(NO TO STUCK OPEN SRVS (0

I ~

2 ~

STATS 1 RELIRF VALVE STUCK OPEN RFH NARDNARE UNAvAILABLE 3>

SORVS) 3+

SORVS)

I> SORVS)

~ >

~ 0 ~ 0 ~ 0 ~ 0 ~

~ 0 ~ 0 ~ ~ > ~ ~ 0 ~ ~ ~ 1 ~I~ ~ ~

91 TOTAL LOSS OP OFPSITE POSER DG A WAVAILABLS DG D UNAVAILABLE DG 8 UNAVAILABLE DG C UNAVAIIABLE FAILURE 'IO RECOVER OPPSITB PONER IN )0 NIWTES RNRSN PWP Bl (SHING PUMP) WAVAILABLE CONDITIONS RElATING 'IO STUCK OPEN SRVS (0, 1, 2, 3>

SORVS)

INITIATOR IS BOC,

FNRU, PRFOPEM INITIATOR IS FNRU

- RPV DEPRSSSURIEATIOH HSIVS FAIL TO REMAIN OPEN

- OPERATOR FAILS TO ESTABLISH SNUIDON COOL(NG SUPPRESSION POOL (TORUS)

UNAVAIlABLR RCIC UNAVAILABLS (6 HOURS)

HPCI (NAVAIIABLE(6 HOURS)

OPERATOR PAILS TO MANUALLYSTART RNR/CORE SPRAY RMR PWP A WAVAILABLR RNR PUMP C UNAVAIlABLS RER PUMP B UNAVAILIUILS RNR PUMP D INAVAILABLE OPERATOR PAILS TO ESTABLISH TORUS COOLING OPERATOR PAILS TO BSTABLISN SNUIOONM COOL)NG O'PERAIOR FAILS TO START CS/LPCI OR TO ESTAB TORUS

~rssoi ~ $01$ $ $ $0<<

WOO 00000000 solos

~ 0 ~ Oo ~ 0 ~

~

500 KV OPPSITE GRID UNAVAllABLE 161 KV OFPSITS GRID UNAVAILABLS OPERATOR tAILS TO RESTORE PONER TO UNIT BOARDS 4XV UNIT BD IA WAVAIIABLS 4KV IN(T BD IB UNAVAIIABLE 4KV UN!T BD 2A UNAVAILABLE 4XV WIT BD 28 UNAVAILABLE SNUIDONN BUS 1 INAVAILABLE VENT

~ 5 RAM COOLING MATER SYSTEH UNAVAILABLR

- HAIN CONDENSER UMAVAIIABLE 1 CND/CND BSTR PUMP, INCLUDES SNORT CYCLE VALVS UNAVAILABI VESSEL INJECTION MITH CRONE UNAVAILABLE

7. 948.09, 15 7 878 ~ 09

.15 PJAV 7.74E-09 PLFX 7.7)8-09

.14 HKCV 7 876'9 IS Figure B-1 (Page 21 of 26). Top 100 Sequences in Browns Ferry Unit 2 PSA Model

NOBEL Name:

BFN)2H Top-Ranking Sequences Contributing to Group s ALL Prequency ALL ~ ALL DAMAGE STATES EXCEPT SUCCESS 07:$ 6:44 09 HAY 1996 Rank No.

Sequence Description Events-- ------

Guaranteed Events/Cour<<ants End State Frequency Percent tper year)

STATE 0 RELIEF VALVES STVCK OPEN FAILVRE TO RECOVER El ECTRIC POWER IN 6 NOVNS

~

~ << ~ ~ <<<< ~ << ~

<< ~ <<<< ~ << ~

~ ~ <<

~ << ~ <<<<

91

'IOTAL LOSS OF OFFSITE POWER DQ A UNAVAILABLE DG D UHAVAILABLE DG 8 UNAVAILABLE DC C WAVAILABM FAILURE TO RECOVER OFFSITS POWER IN 30 NtNltES COMMON CAUSE COUPLINQ OF UNIT 1/1 AND UNIT 3 DIESRLS CONDITIONS RELATING 'IO STVCK OPEN SRVS IO ~

1 ~

2 ~

3 <<SORVS)

STATE 0 RELIRP VALVES STUCK OPEN PAILVRE 'TO RECOVER ELECTR'IC POMER IN 6 HOURS SNltDOMN BVS 2 UNAVAILABLE 4KV SD BD A WAVAILABM 440V SNVIDOMN BOARD 1A 440V RNOV BD IA POWER UNAVAILABLE 440V DIESEL AUX. BD A POWER UNAVAILABLE 4KV SD BD 8 UNAVAILABLR 440V SNVIDONl BOARD 2A 440V RHOV BD 2A POWER UNAVAltABM 4KV UNIT BD 2C POWER UNAVAIIABLE 110 V RPS BUS <<A>> VNAVAILABLE 4KV SD BD C UNAVAILABLE 440V SNVIDOWN BOARD 18 440V RHOV BD 18 POWER WAVAILABLE 4KV SD BD D VNAVAIIABM 440V SNUIDOMN BOARD 28 440V RHOV BD 2D POWER WAVAIIABLE 440V RNOV BD 2R POWER WAVAILABLS 440V RHOV BD 28 POWER WAVAILABLE 440V RNOV BD 2C POWER UNAVAILABLR 440V DIESEL AUX BD 8 POWER UNAVAILABLS 120 V RPS BUS <<8<<UNAVAILABLS 120 V IIC BVS <<2S'AVAILABLE

~ XV UNIT BD 3A WAVAILABLE 4XV UNIT BD 38 UNAVAILABLE RAM CODLING MATER SYSTEM UNAVAILABLE SECH PUMP 8 VNAVAILABLS RX BUIIDINQ COHFONEMT CODLING MATER STSTEH VNA RNRSM PVHP Al WAVAILABLR RNRSM PVNP Al (SWING PUMP) WAVAILABLE RERSM PVNP S2 UlQVAILABLS RNRSM PUMP C2 UNAVAILABLE RNRSM PWP Cl ISMING PWP)

UNAVAIIABM PLANT CONTROL AIR STETS!i UNAVAILABtR DRYMRLL CONIROL AIR SYSTEM UNAVAILABLE HSIVS FAIL TO REMAIN OPEN 1 CND/CND BSTR

PUMP, INCLVDES SNORT CYCLE VALV RCIC WAVAILABLRLONG TERN NPCI UNAVAILABLRLONG TERN VRSISL 1)tIECTION MITE CRDNS VNAVAILABLR FAILURE TO RECOVER 440V RHOV BDS lA OR 18 RNR PUMP A WAVAILABLR RNR PWP C UNAVAILABM Ul TO U1 RNR CROSS CONNECT VNAVAILABLR RNR PUMP 8 WAVAILABM TORUS COOLINQ HARDWARE UNAVAILABLR FAILURE TO RECOVER TORUS CODLING OPERATOR PAILS 'IO SSTASLISH SNVIDOWN COOLING

$ 00 KV OFFSITS GRID UNAVAILABLR 161 KV OPFSITR CRID UNAVAILABLR OPERATOR FAILS TO RESIDRE POMSR TO UNIT BOARDS 4KV UNIT SD IA UNAVAILABLR 4KV UNIT BD 18 UNAVAILABLE

- 4KV UNIT BD 1A UNAVAILABLE iKV UNIT BD '28 WAVAIIABLE SNllUOMN BUS 1 UNAVAILABLR SNVIDOMN BUS 2 UHAVAILABIR 4XV SD BD A UNAVAIIABLE 440V SNVIVOMN BOARD 1A 440V RHOV BD IA POMER WAVAILABLS 440V DIESEL AUX. BD A POWER UNAVAILABLR 4KV SD BD 8 WAVAILABLE 440V SNJIDOMH BOARD 2A 440V RNOV BD 1A POWER UNAVAILABLR VAILABLE E UNAVAILABL PICZ 9.TIE F 09 Figure B-1 (Page 22 of 26). Top 100 Sequences in Browns Ferry Unit 2 PSA Model

5 3

3 n

~<<

HODEI. Mane:

BFNU2H Rank No.

Sequence Description Top-Ranking Sequence!

Contributing to Group>>

ALL Frequency ALL ALI, DAMAGE STATSS EXCEPT SUCCESS

~------ ~Events.-----------"-

Guaranteed Events/Ccee<<enta 4KV UNIT BD 2C POMER WAVAILABLR 120 V RPS BUS 'A>> UNAVAILASLE 4KV SD BD C UNAVAILABLR 440V SMUIIOMN BOARD 18 400V RHOV BO 18 POMER UNAVAILABLR 4KV SD BD D WAVAILABLE 440V SMUIDOMN BOARD 28 440V RHOV BD 2D POMER UNAVAILASLR 4$ 0V RHOV BD 2S POMER WAVAILABIE 490V RHOV BD 28 IOMER UNAVAIIABLR 490V RHOV BD 2C POMER WAVAILABLR 490V DISSEL AUX BD 8 IOMER UNAVAILABLR 120 V RPS BUS '8>> UNAVAILABLE 120 V 16C BUS <<28>> WAVAILABLS 4KV UNIT BD 3A UNAVAILABLS 4KV UNIT BD 38 UNAVAIIABLE DG 3A UNAVAILABILITY 4KV SD BD 3EA AND 400V SD BO 3A POSER UNAVAILABLE 490V SMUIDOMN BOARD 3A 4SOV DIESEL AUX SD 3EA POMER UNAVAILABLE 120 V 16C BUS <<2A>> UNAVAILABLS DG 3C UNAVAILABLR 4KV SD BD 3RC AND 490V SD BD 38 UNAVAILABLR DG 38 UNAVAILABLE 4KV SD BD 3EB WAVAILABLS 400V SNUTDOMN BOARD 38 440V DIESEL AUX BD IEB POMER UNAVAILABLE DG 3D UNAVAILABLE 4KV SD BD 3ED UNAVAILABLE RAN COOLINI MATER SYSTEH UNAVAILABLE EECM PWP h UNAVAILABLS RECM PWP 8 UNAVAILABLR EECM PWP C WAVAILASLE RECN PWP D UNAVAILABLE RX BUILDING COMPONENT COOLING MATER SYSTEH UNAVAILABLE RMRSM PUMP A2 UNAVAILABLE RMRSM PUHP Al (SHING PWP)

WAVAILABLE RMRSM PWP 82 UNAVAILABLS RMRSM PWP 81

{SHING PUNP)

UNAVAILABLR RMRSM PWP C2 WAVAILABLR RMRSM PUHP Cl (SHING PWPI UNAVAILABLE RMRSM PUHP D2 UNIVAILABLE RMRSN PWP Dl ISMING PWPI UNAVAILABLE PLANT CONIROL AIR SYSTEM UNAVAILABLE DRYMELL CONTROL AIR SYSTEM UNAVAILABLE CONTAINMENT AYHOSPMERIC DILUFION OPERATOR FAILS TO RECOVER EECN ISTART SMING PWPI HSIVS FAIL TO REMAIN OPEN I CND/CND BSTR PWP, INCLUDES SNORT CYCLE VALVE UNAVAILABI RCIC WAVAILABLRLONG TERN NPCI WAVAILABLRLONG TERN VESSEI, INJECTION NITH CRDMS UNAVAILABLE OPERATOR FAILS TO MANUALLYSTART RMR/CORE SPRAY FAILURE TO RECOVER 490V RHOV SDS 2A OR 2S RMR PUMP A UNAVAILABLE RMR PWP C WAVAILABLR Ul 'IO U2 RMR CROSS CONNECT WAVAILABLS RMR PUMP 8 UNAVAILABLE RMR PUMP D UNAVAILABLR U3 TO U2 RNR CROSS CONNECT UNAVAILABLE OPERAIOR FAILS TO ESTABLISH TORUS COOLINO RMR LOM PRESSURR IN3ECTION 'PATH WAVAILABLS End State OTH86:48 09 HAY 1996 Frequency Percent.

lper year) 93 PARTIAL LOSS OF CONDENSATE TBVS PAIL TO RELIEVE)MAINTAINRX PRESSURE OIAV 7.4 ~ E ~ 09

.14 Figure 8-1 (Page 23 of 26). Top 100 Sequences in Browns Ferry Unit 2 PSA Model

MODEL Hanoi BFNUIH Top.Ranking Sequences contrtbuttng to Croup

ALL Prequency at.). - at,t. DAMAGE syaTEs RxcEFT succEss OYJSCJ44 09 HAY 1996 Rank No.

Sequence Description

~Events---------------

Guaranteed Events/Coeieents End state Frequency Percent (per year)

AUTOMATIC/MANUALREACTOR SCRAM FAILURE CONDITIONS RELATING TO STUCK OPEN SRVS (0~

te 2e 3 ~

SORVS)

STATB 1 RELIRP VALVE STUCK OPEN OPERATOR FAILS TO CONTROL L'Pt DURING ATMS 9 ~

T)JRBINS TRIP AQIOHATIC/MANUALREACIOR SCRAM FAILURE STANDBY LIQUID CONTROL SYSTEM UNAVAILABLE CONDITIONS RELATINC TO STUCK OPEN SRVS (0, I, 1, 3 ~

SORVS)

STATS 1 RELIEP VALVE Sll)CK OPS)l 95 lOSS OP RAM COOLINC MATER 500 KV OPPSITE CRID UNAVAILABM CONDITIONS RELATING TO STUCK OPEN SRVS lo, 1, 1, lv SORVS)

STATS 0 RELISP VALVES STUCK OPEN Rclc wavaILABLE (6 HDURs)

HPCI UNAVAILABLE (6 HOURS)

RPV DEPRESSURIEATION 96 TURBINE TRIP AUIOHATIC/MANUALREACTOR SCRAN PAILURE CONDITIONS RElATING TO SIQCK OPEN SRVS (0, 1 ~ 2, lv SORVSI STATE 1 RELISP VALVE STUCK OPEN RHR PUMP B UNAVAILABLE RHR PUHP D UNAVAILABLE

~ 0 \\ ~ 0 ~ SOS ~ 0 ~

97 LOSS OF RAM COOLIHG MATER CONDITIONS RELATING TO STUCK OPEN SRVS (0, I, '2, le SORVS)

STATE 0 RRLIEP VALVES STUCK OPS)I RCIC UNAVAILABLE l6 BOURS)

HPCI WAVAILABLElC HOURS)

RPV DEPRESSURIZATION RFM HARDKARS WAVAILABLS VESSSL INJECTION NITH CRDNS WAVAILABLR VESSSL INJECTION KITH CRDNS UNAVAILABLE RAM COOLINC MATER SYSTEM UNAVAILABLE

. HAIN CONDENSER WAVAILABLR 1 CND/CND BSTR PtNP, INCLUDES SHORT CYCLE VALVE UNAVAILABL VSSSEL INJECTION NITH CRDHS UNAVAILABLE VESSEL INJRCTION NITH CRDNS WAVAILABLE OPERATOR tAILS TO ESTAB( ISH 'IORUS COOLING RAM COOLING MATER SYSTEM UNAVAILABM HAIN CONDENSER UNAVAILABLE 1 CND/CND BSTR PUMP, INCLUDES SNORT CYCLR VALVE WAVAILABL VESSEL INJECTION KITH CRDHS UNAVAltABLE olav HIAV 0 IBV HIAE Iis 09 13 1.0)ST 09

.13 6.96E 09

.13 6.')1E ~ 09

.13 94 TOTAL LOSS OP OPFSITR POKER DG A UNAVAILABLE FUEL OIL FOR DIESEL D UNAVAILABLE DG B UNAVAILABLE FAILURE 'IQ RECOVER OPPSITE POMER IN 30 MINUTES DG )D WAVAILABLE CONDITIONS RRLATING TQ STUCK OPEN SRVS (0, 1, l. le SORVSI STATS 0 RELIEF VALVES STUCK OPEN PAILURE TO RRCOVER ELECTRIC POKER lN C HOURS

- 400 KV OtFSITE GRID UNAVAILABLE 161 KV OPFSITS CRID UNAVAILABLE OPSRA'IOR PAILS '10 RESYQRE POKER TO UNIT 4KV WIT BD 1A WAVAILABLE 4KV WIT BD 1$ UNAVAILABLR 4KV UNIT BD 2A (NAVAILABLE

- 4KV WIT BD 2B WAVAILABM SHUIDOMH BUS I UNAVAILABM SHUIDOIN BUS 2 (NAVAILABLE DG D UNAVAILABLE

~ KV SD BD A UNAVAILABLE 440V SHUTDOMN BOARD IA 440V RHOV BD IA POKER UNAVAILABLS 440V DIESEL AUX~

BD A POKER UNAVAILABLE iKV SD BD B UNAVAILABLR 440V SHQI)JOHN BOARD 2A 440V RHOV BD 2A POKER WAVAILABLS

~ KV UNIT BD 2C POKER UNAVAILABLS 120 V RPS BUS 'A UNAVAILABLE 4KV SD BD D UNAVAILABLE 440V SNUIDOIN BOARD 2B 440V RHOV BD 1D tOIIER (NAVAILABLS 440V RHOV BD 2E POKER WAVAILABLR 440V RHOV BD 2$

POMER UNAVAILABLE 440V RHOV BD 2C POKRR UNAVAILABLE 440V DIESEL AUX BD B POKER UNAVAILABLE 110 V RPS BUS IB'NAVAILABLE 4KV UNIT BD lA UHAVAILXBLE 4KV UNIT BD )B WAVAILABLS

- 4KV SD BD 3SD WAVAILABLE RAN COOLIHG MATER SYSTEM UNAVAILABLR BOARDS 0 IAX 6 69S 09 12 Figure B-1 (Page 24 of 26). Top 100 Sequences in Bro>vns Ferry Unit 2 PSA Model

MODEL Mane<<

BFNVlM Top-Rankins Sequences contribut(ns to Group

ALL Frequency ALL ~ ALI, DAHACE STATES EXCEPT SVCCESS olr66:44 09 HAY 1996 Rank No.

Sequence Descrlptlon

~

Events Guaranteed Events/Coeeents fnd State Frequency Percent (per year) 99 TOTAL LOSS OF OFFSITE POMER FVEL OIL SYSTEM FOR DIRSRI. A UNAVA'ILABLE DG D UNAVAILABLE DG 8 UNAVAILABLE FAILURS TO RECOVER OPFSITE POMER IN 30 MINUTES

- DG 3D WAVAILABLR CONDITIONS RRLATINC TO STUCK OPEN SRVS (0, I, 2, 3<<SORVS)

STATE 0 RSLIEF VALVES SIUCK OPEN FAILVRE TO RECOVER ELECTRIC POMER IM 6 HOURS RX BUILDING COMPONENT COOLINC MATER SYSTEM UNAVAILABLE RHRSM PUMP A2 VNAVAILABLE RNRSN PWP Al (SMIHC PUMP)

VNAVAILASLE RNRSM PUHP C2 WAVAILASLE RMRSM P(NP Ci (SHING PWP)

UNAVAILABLE RNRSM I'WP D2 WAVAILAB)8 RHRSM PUMP Dl (SHING PUMP)

UNAVAILABLE PLAÃr COMIROI AIR SYSTEM UNAVAILABLE DRYMSLL CONTROL AIR SYSTEM UNAVAILABLE

~

RNR PVHP C WAVAILABLR

- RNR PUHP B QNAVAILABLR RNR PWP D (NAVAILABLR

~ Q3 TO U2 RNR CROSS CONNECT (NAVAILABLR

~ CS LOM PRESSURE INJECTION UNAVAILABLE RNR IOM PRESSURE INJECTION PATH UNAVAILABLE SOO KV OttSITR GRID (NAVAILABLE 161 KV OFFSITR GRID VNAVAILABLE OPERATOR PAILS TO RESTORE POMRR TO UNIT BOARD 4XV UNIT BD IA UNAVAILABLE 4XV UNIT BD IB VNAVAILABLR 4KV UNIT BD 2A WAVAIIABLE iKV UNIT BD 2$ UlQVAILABLE SNQIDONN BVS I UNAVAILABLE SNVIDOlIN BUS 2 UNAVAILABLE DG A VNAVAILABL8 4KV SD BD A WAVAILABLE 440V SNVYDOMN BOARD 1A 440V RHOV BD IA POWER 'VMAVAILASLE

~ 40V DISSEI AUX. BD A POMER UNAVAILABLE 4XV SD SD 8 UNAVAILABLE 440V SNVIDOMN BOARD 2A 440V RNOV BD 2A PONER WAVAILABLE 4KV UNIT BD 2C POMER VNAVAILABL8 120 V RPS BUS <<A<<UNAVAILABLR

~ KV SD BD D UNAVAILABLE 440V SNVIDOMN BOARD 28 440V RHOV BD 2D POMER VNAVAILABLR 440V RHOV BD 2S POMSR WAVAILABLE 440V RHOV BD 28 PONER WAVAIIABLR 440V RHOV BD 2C PONER UNAVAILABLR 440V DIESEL AVX BD 8 POMER UNAVAILABLE 120 V RPS BVS <<8'NAVAILABLR 4KV WIT BD 3A VNAVAILABLE iKV UNIT BD 38 UNAVAILABLE 4KV SD BD 3ED UNAVAILABLR RAM COOLIHC MATER SYSTEH UNAVAILABLE RX BVILDING COMPONENT COOLING MATER SYSTEH RNRSM PUHP A1 (NAVAILABLE RNRSN PWP Al (SHING PUHPI UNAVAILABLE RHRSM PWP C2 UNAVAllABLE RNRSM PWP Cl (SMING PUNP)

UNAVAILABLE RMRSM PUHP D1 UNAVAILABLR RNRSM PWP Dl (6'NINC P(NP)

WAVAILASLE PLANT COHIROI AIR SYSTEM UNAVAILABLE DRYMELL CONTROL AIR SYSTRM UNAVAIIABLE HSIVS FAIL TO REMAIN OPEN I CND/CND BSTR PUMP, INCLVDES SHORT CYCL UNAVAILABLE 8 VALVE WAVAILABI HSIVS tAIL TO REHAIN OPEN 1 CND/CND BSTR

PUMP, INCLUDES SHORT CYCLE VALVE UNAVAILASL RCIC UNAVAILABLELONG TERM HPCI QNAVAILABI.ELONG TERM VESSEL INJECTION MITN CRDNS UNAVAILABLE RNR PUHP A VNAVAILABLR 0 )AX 6 ~ 648 09

.12 Figure 8-1 (Page 25 of 26). Top 100 Sequences in BroNns Ferry Unit 2 PSA Model

NODEL Nenes BFNUIN Top-Ranking Sequences Contr)Doting to Croup i ALL Prequency ALL ~ ALI DANAGE STATES EXCEPT SUCCESS OIr56re$

09 HAY )996 Rank No.

Sequence Descrlptlon Events.

Guaranteed Events/Coeieents End State Frequency Percent (per year) 100 PRE DHATER RANPI.'P AUIOHATIC/NANUALREACTOR SCRAN FAILURE STANDBY LIQUID CO)lIROL SYSTEN UNAVAILABLE CONDITIONS RELATINO 'YO STUCK OPEN SRVS (0, I, I, 3e SORVS)

STATE 0 RELIEF VALVES STUCK OPEN RCIC UNAVAILABLSLONO TERN

- HPCI UNAVAILABLELONO TERN VESSEL INJECTION NITH CRDHS UNAVAILABLE RHR I'UNP A UNAVAILABLR RHR PUNP C UNAVAILABLE RHR PUNt B UNAVAILABLE RHR PUNP D UNAVAILABLE

- UI 'IO UI RHR CROSS CONNECT UNAVAILABLE CS LOll PRESSURB INJECTION UNAVA11ABLE RHR LON PRESSURE INJECTION PATH UNAVAILABLE INITIATOR IS BOC,

FNRU, PRFOPEN INITIATOR IS FNRU RFN HARDNARS UNAVAILABLE OIAV 6.6'lS ~ 09

.13 Figure B-1 (Page 26 of 26). Top 100 Sequences in Browns Ferry Unit 2 PSA Model

0

APPENDIX C. SPLIT FRACTION IMPORTANCE MEASURES MODEL Name:

BFNU2H Split Fraction Imporrance for Group

ALL Sorted hy Praction Importance Group Frequency i 5.3621E-06 07:06:03 09 HAY 1996 Page 1

SF Name.

Fraction.

Importance Fussel-Vesely.

Birnbaum...

Importance Importance Achievement. Reduction...

Worth Worth SF Value..

Frequency.

1.2.

3.

5.

6.7.

8.

9.

10

~

11.

12

~

13 ~

14.

15.

16.

17.

18.

19

~

20

~

21.

22.

23

'4.

25.

26.

27

~

28

'9

'0.

31.

32

~

33

~

34.

35.

36.

37.

38.

39.

40.

41.

42.

43.

44.

45.

~

46.

47.

48.

49.

50.

51.

52.

53.

54.

55.

56.

57:

58.

59.

60.

61.

62.

63.

64.

65.

66.

67.

68.

69.

70.

71.

72.

73.

74.

75.

FIMTRF NCDF MEITF DWF CPRECF SDRECF UBRECF FWAF HSF CDAF INAF CRDF HRLF INBF INCF INDF INEF INFF RXSI NAF RVCO IVOF CDF HR6P LPRESF RCMP INGF NRVF OAIF INHF JHF JAF OSPF DWSF OGSF UB42AF UB41AF UB41BF SHUT1F UB42BF SHT2F UB42CF OUBF OG16F DCAF RPAF RPBF WETF LPCF RPCF U3F PCAF U1F UB43BP UB43AP FMHF RBCF RPDF KCF KFF KHF HUMP RCLF SW2BF HCDF EBF RFF RRF ACF DKP HPLF RHF SGTOPF RSF SW1CF 9 ~ 9136E-01

9. 9136E 01

9. 9136E Ol

$.9860E-01 8.9404E-01 8.9387E 01 8.7644E 01

'7.5164E 01 6.3026E-01 6.2987E 01 5.6329E-01 5.2907E 01 4.9733E 01 4.7587E 01 4.7587K 01 4.7141K-01 4.6898K-01 4.5246E 01 4.0590E 01 4.0503E 01 3.8344E 01 3 '850E-01 3.7010E 01 3.6373E 01 3.6073E 01 3.5883E 01 3.2005K 01 3.0076E-01 2 '582E-01 2.8736B-01 2 '091E-01 2.8091E-01 2.6912K 01 2.6527E 01 2 '506E-01 2.5436K 01 2.5436E 01 2.5436E 01 2.5436E 01 2.5436E-01 2.5436E 01 2.5258K 01 2.5202E-01 2.5195E-01 2.4682E 01 2.4566E-01 2.4371K-01 2.4354E 01 2.4243E 01 2.3836B 01 2.3296K 01

2. 1047K-01

2. OS16E 01 2.0338K-01 2.0338K 01 2.0054E 01 1 ~ 9964K 01 1.9224E 01 1 ~ 8599E 01 1.8344E 01 1.8336K 01 1.7391E-01 1 ~ 7373E 01 1.7320E-01 1.7302E 01 1 ~ 7010E-01 1.6989E-01 1.6987E 01 1.6968E-01 1.6837E 01 1.6695E-oi 1 ~ 6465K. 01 1.6230K 01 1.6172E-01 1 ~ 5982E 01 4.0589E 01 4.8803E+00 1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00 1.0000Eioo 1.0000E+00 1.0000K+00 1.0000Bioo 1.0000Eioo 1.0000Eioo 1.0000Eioo 1.0000E+00

1. 0000Eioo 1.0000Beoo 1 ~ OOOOE+00 1.0000E+00 1.0000K+00 1.0000K+00

1. 8818K~04 1.0000E+00 6.4449K 01 1.0000K+00 1

OOOOE+00 1.0000E+00 1

~ OOOOE+00 1.0000K+00 1.0000K+00 1.0000E+00 1.0000E+00 1.0000E+00 1 ~ 0000Bioo 1.0000E+00 1.0000E+00 1 ~ 0000E+00 1.0000E+00 1.0000K+00 1.0000E+00 1.0000E+00 1.0000K+00 1.0000E+00 1 ~ OOOOE+00 1.0000Ei00 1.0000K+00 1.0000E+00 1.0000E+00 1.0000K+00 1 ~ 0000E+00 1.0000K+00 1.0000E+00 1.0000E+00 1.0000B+00 1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00 1.0000K+00 1.0000E+00 1.0000B+00 1.0000E+00 1

~ 0000E+00 1

OOOOE+00 1 ~ 0000E+00 1 ~ OOOOE+00 1.0000E+00 1 ~ OOOOE+00 1.0000K+00 1.0000K+00 1 ~ OOOOE+00 1.0000K+00 1.0000E+00 1 ~ 0000E+00 1.0000E+00 1.0000K+00 1 ~ 0000E+00 1.0000K~00 5.9411E 01 5.8803K+00 1.0000E+00 1.0000K+00 1.0000E+00 1.0000K+00 1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00 1.0000K+00 1.0000K+00 1.0000E+00 1.0000K+00 1.0000K+00 1.0000K+00 1.0000E+00 1.0000K+00 1.0000E+00 1.0000E+00 2.1570E 05 1.0000K+00 9.3210K 01 1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00 1.0000K+00 1.0000K+00 1.0000K+00 1.0000K+00 1.0000K+00 1.0000E+00 1.0000E+00 1.0000K+00 1.0000B+00 1.0000E+00 1.0000E+00 1.0000K+00 1.0000K+00 1.0000Eioo 1.0000K+00 1.0000K+00 1.0000E+00 1.0000E+00 1.0000K+00 1.0000E+00 1.0000E+00 1.0000K+00 1.0000K+00 1.0000K+00 1.0000E+00 1.0000K+00 1.0000B+00 1.0000E+00 1 ~ 0000E+00 1 ~ OOOOE+00 1.0000B+00 1.0000E+00 1.0000E+00 1.0000K+00 1.0000E+00 1.0000K~00 1.0000K+00 1.0000E+00 1.0000K+00 1.0000K+00 1.0000K+00 1.0000K+00 1.0000B+00 1.0000K+00 1 ~ 0000E+00 1.0000B+00 1.0000K+00 1.0000E+00 1.0000E+00 1.0000E+00

5. 3158E 06 5.3158E 06

5. 3158E-06 4.8184E-06 4.7940K 06 4.7930K 06 4.6996E 06 4.0304E-06 3.3795E-06 3.3775E 06 3.02058-06 2.8369E 06 2.6668K 06 2.5517K 06 2.5517K 06 2.5277K-06 2.5147K-06 2.42628-06 2.1765E 06 2.1718E 06 2.0561E 06 2.0296E 06 1 ~ 9845E 06 1 ~ 9504E 06 1.9343E 06 1 ~ 9241E 06 1 ~ 7161K-06

1. 6127E 06 1.5863E-06 1.5409E-06 1.5063K 06 1.5063E 06 1 ~ 4430E 06 1.4224E 06 1.4213K 06 1.3639E 06 1.3639E 06 1.3639E 06 1.3639E 06 1.3639E 06 1.3639E 06 1.3544E 06 1.3513K 06 1.3510K 06 1.3235E 06 1. 3 1'73E 06 1.3068E 06 1.3059B 06 1.2999K 06 1 ~ 2781E 06 1.2492E 06

1. 1286K 06

1. 1162K 06 1 ~ 0906E-06 1.0906K 06 1.0753E 06 1 ~ 0705K 06 1.0308E-06 9.9729E 07 9.8361E-07 9.8318E 07 9.3251K 07 9.3155E 07 9.2873K 07 9.2777K-07 9.1210E 07 9.1098K 07 9.1087E-07 9.0987E 07 9.0280K 07

8. 9521K 07 8.8287E-07 8.7026E 07 8.6/18E 07 8.5696K 07

~~'a~a,nn "nnr n4>>-.~r, PLG

HODEL Name:

BFNU2H spile Fraccion Imporcance for croup

ALL Sorced by Fraccion Importance Group Frequency 5.3621E-06 07:06:03 09 HAY 1996 Page 2

SF Name...

Fraccion...

Fussel-Vesely.

Imporcance Imporcance Birnbaum...

Imporcance Achievemene.

worth Reducrion...

SF Value..

~.... Frequency.

Worch

'I6.

77.

18.

79.

80, 81.

82.

83.

84.

85.

86.

87.

88.

89, 90, 9L.

92.

93.

94.

95.

96.

97, 98.

99.

100.

101.

102.

103.

104.

105.

'06 107.

108.

109.

110.

111.

112.

113.

114.

115.

116.

117.

118.

119.

120.

121.

122.

123.

124.

125.

126.

127.

128.

129.

130.

131.

132.

133.

134.

135.

136.

137.

138.

139.

140.

141.

142.

143.

144.

145

~

146

~

147.

148

~

149.

150.

151.

152.

153.

154.

155.

156.

SW2CF ABF RCI1 RVC4 DLF RIF RJF RTF RNF ADF SW2AF SW1AF RVD22 RQF REF RMF AAF HPI4 SGTF SWlDF EAF ROF RXF A3EAF OEEF U3AP1 ORPF OLA1 RVC5 RLF REF SW2DF CA1 SWlBF A3EDF CSP1 DOF RVD45 A3EBF CSDF ECF BDF RYF RPP A3ECF CB4 RVC1 R480F CSF OBCF SPF DNF LECF GD2 EPR304 SL1 RBISOF RBZ2 OSVF BPR64 CE1 AIF VNTF RPA1 CRD4 RPC2 EPR303 EPR63 BVRF RCIF HPZF SPRF CHF OSL1 CBDF GC4 CADP CEP GFF EPR302 CGF 1.2195E 01

-1.1642E+00 1.3401E 01 1 ~ 2903E-01 3.9532E 02 1.0943E 01 1 ~ 014 $E-01 li0011E 01

1. 0861E-01 8.1604E 02 7.5692E 02

'l. 1 4 9 8E 02 7.3420E-02 1 ~ 1097E 02 3 '308E 02 7.0048E 02 5.6567E 02

5. 5221E-02 5.9$ 81E 02 5 '963E-02 6.1497E-02 6.0592E 02 5.4418E 02 3.9727E 02 4.4914E 02 1.5982E-01 1.5788E-01 1.5061B-Ol 1.4698B 01 1.4361E 01 1.4309E 01 1.4309E-01 1.4180E 01 1.4180E 01 1.4024E-01 l.3922 E-01 1.3922E 01 1.3420E 01 1.3307E-01 1.3307E-01 1.3307E 01 1.3302E 01

1. 3091E-01 1.2864E-01 1.2614E 01 1.2404E-01 1.1952E 01 1.1952E 01 1.1945E-01 1.1564E-01

1. 1510E-01 1.1438E 01 1.1380E-01 1.1301E 01 1.1252E 01 1.1252E 01 1.1238E 01

1. 1184E-01 1.1025E-01 1.0866E Ol 1.0863E 01 1.0605E 01 9.6736E 02 9.6647E-02 9.5697E 02 9.5559E 02 9.0289E 02 8.6I03E 02 8.6703E-02 8.6684E-02 8.2113E 02 8.1004E 02 7.9728E 02 7.9589E-02 7.9282E 02 1.6493E-02 7.5316E 02 1.4918E 02

'7.4S02E-02

'l.3429E 02 7.2476E 02

'l.1768E-02 1.1768E-02 1.1460E 02 7.0056E-02 6 '091E 02 6 ~ 7480E 02 6 ~ 14$ 0E 02 6.5115E 02 6.4821E 02 6.1680E-02 6.1541E 02 6.0592E 02 5.9101E-02 5.9099E 02 5.7394E 02 5.6774E 02 5.5809E 02 5.5676E 02 5.3388E-02

5. 1013E-02 5.0087E 02 4.9204E 02 4

~ 1075E-02 4 '367E 02 4 '350E 02 1.0000Bioo l.DODOS+00 2.1181E+00 8.6950E-01 1.0000E+00 1.0000E+00 1.000OE+00 1.0000E+00 1.0000B+00 1.0000E+00 1.0000E+00 1.0000E+00 1.6888E+02 1.0000E+00 1.0000E+00 1.0000Eioo 1.0000E+00 2. 04 5 1E+ 00 1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+OD 1.0000E+00 8.7805E-01 2 '642E+00 Se6599E-01 8 '097E-01 1.0000B+00

2. 2914 E+00 1.9944E+00 1.0000E+00 1.0000E+00 1.0000B+00 2.O173E+OO 1.0000E+00 1.0000E+00 1.3904B+D3

'.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00 1.0000B+00 1.4166E+00

2. 1543E+00 1.00DOE+00 1.0000E+00 1.0000E+00 1.0000Eioo 1.0000E+00 1.0000E+00 1.7263E+00 1.2002E+00 1.3274E+01 1.0000E+00 7 ~ 1453E 01 1.0000E+00

1. 5186E+00 1.3843E+00 1.0000E+00 1.0000E+00 4 '983E+00 2.4751E+00 1.0874E+00

1. 24 16E+ 0 0 1.4469E+00 1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00 1 ~ OOOOE+00 1 ~ 1134E+01 1 ~ OOOOE+00 1 ~ 0590E+00 1 ~ 0000E+00 1 ~ 0000E+00 1.0000E+00 1-1835E+00 1 ~ 0000E+00 8 '057E-01 8 '852E 01 8.9989E 01 8 9139E-01 9 ~ 1840E 01 9.2431E 01 9.2850E-01 9 '65SE-01 9.2890E 01 1.0323E+00 9.2995E 01 9 '343E 01 9.4418E 01 9.4012E-01 9 '004E 01 9 '850E-01 9 ~ 3941E-01 9.4558E-01 9.6027E-01 9 5509E 01 7.7599B 01 1.0395E+00 1 ~ 0000E~OD 1.0000E+00 6 '250E 02 8 '920E"01 1 ~ 0000Bioo 1 ~ OOODE+00 1 ~ ODOOE+00 1 ~ OOOOE+00 1.0000E+00 1.0000Bioo 1.0000Bioo 1.0000E400 7 '760E 04 1.0000E+00 1 ~ OOOOE+00 1.0000Eioo 1 ~ 0000E+00 1.0990E 01 1.000OE+00 1.0000E+00 1.0000E+00 1.0000E+00 1.0000B+00 1.0000E+00 1.0000E+00 1.5000E 01 1.0000Bioo 7.8120E 02 9.2600E 02 1 ~ 0000E+00 1

DODOS+00 1.0000E+00 Si9590E 02 1 ~ 0000E+00 1.0000Ei00 7.8170E 05 1.0000E+00 1.000OE+00 1,0000E+00 1.0000E+00 1.0000E+00'.0000B+00 1.0000E+00 1.0000E+00 1.0000E+00 1.6380E-01 6 ~ 1540E 02 1.0000E+00 1 ~ OOOOE+00 1.0000E+00 1.0000E+00 1.0000E+00 1 ~ 0000B+00 8.9620E 02 2 '830E-01 5.1591B 03 1.0000E+00

1. 0167E 01 1.0000E+00 1 ~ 1900E 01 le2830E 01 1.0000E+00 1

DODOS+00 1.4330E 02

3. 9011E-02 4.0700E 01 2.0290E-01 1.1940E 01 1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00 5.3410E-03 1.0000E+00 4.0240E 01 1.0000E+00 1.0000E+00 1.0000E+00 1.9660E Ol 1.0000E+00 8.5696E 0'7 8.4657E-D7 8.0759E-07 7.8812E 07

7. 700'IE 0 I 7.6728E-07 I.6728E-07

7. 6035E-0 I 7.6035E 07 7.5201E-07 7.4651E 07 l.4651E-07 7.1962E 07 7.1355E 07 7.1355E 07 7.1355E-07 7.1328E 0'I I ~ 0198E-07 6.89$ 0E 07 6.7962E-07 6.6510E 07 6.4089E 07 6.4089E 07 6 '052E-07 6.2009E-07 6 ~ 1719E 07 6 ~ 1334E 07 6.1022B 07 6.0599E 07 6.0334E 07 6.0334E-07 6.0259E-07 5 '968E 07 5 ~ 9116E 07 5.8264E 07 5 '24$ E 07 5.6865E 07

5. 1871E-07 5.1824E 07 5.1314E 07 5.1240E 07 4.8414E 07 4.6491E 07 4.6491E 07 4 ~ 6481E 07 4.4030E 07 4.3435E 07 4.2751E 07 4.2677E 07 4.2512E 07 4 ~ 1016E 0'7 4.0385E 07 4.0112E 01 3.9949E 07 3.9374E 07 3 '863E 07 3.8483E 07 3.8483E 07 3 ~ 8318E 07 3.1565E 07 3.7047E 07

3. 6184 E>>07

3. 6184E-07 3 '916E-07 3.4758E 07 3.3074E-07 3.2999E 07 3.2490E-07 3 ~ 1691E-0 I 3 ~ 1689E 07 3.0776E 07 3.0443E-07 2.9926E 07 2.9854E 07 2.8628E-07 2.'l354E-07 2o6858B-07 2.6384B-07 2.5243E 07 2.4326E-07 2.4317E-07 PLG

NODEL Name:

BFNU2N Split Fraction Importance Ior Croup Sorted by Fraccion Importance Croup Frequency

~ 5.3621E-06 07:06:03 09 MAY 1996 Page 3

ALL SF Name...

Fraccion...

Fussel-vesely.

Import'ance Importance Birnbaum...

Importance Achievement.

worth Reduction...

SF Value.......

Frequency.

worch 157.

158.

159.

160.

161.

162.

163.

164.

165.

166.

167.

168.

169.

170.

111.

172.

113.

174.

17S.

176.

177.

178.

179.

180.

181.

1$ 2.

183.

184.

1$ 5.

186.

187.

188.

189.

190.

191.

192.

193.

194.

195.

196.

197.

198.

199

~

200.

201.

202.

203.

204.

205.

206.

207.

208.

,209.

210, 211.

212.

213

~

214.

215

~

216.

217.

218.

219.

220.

221

'22

'23.

224.

225.

226.

227.

228.

229.

230.

231.

232.

233.

234.

235.

236.

237.

NPZIF NH2F EPR62 RPBL NHlF NPIF RPD2 LVF PX1F RVC9 OSL2 RCF GDI OZVF GB2 PX2F RBF DGCL DH3 GC2 GF2 RVC3 GC3 GG1 DGK SWLCL GH1 NZEF GCF GDF SW2B1 FAL CAF EPR301 OLPF HPI2 GBF SW2DL NRUF GC1 RPB3 RPD4 GH2 OXF SW2C1 SW2AL EPR61 HPZ6 U12 GBI NCDL RVC2 FD2 FB3 FEF FGF FHF FFF FC4 SW183 GG2 OADL SWLD7 SDC2 TBL FDL CRDI CS4 FCI NPI 1 NPZI2 GC52 RVC6 DGJ RPDLO CRDS TOR2 RPD3 SWLAL OLP1 FBL 4.3803E 02 4.3803E-02 4.32188 02 4.2995E-02 4.2535E 02 4.2535E 02 4.1382E 02 4.0816E 02

3. 9119E-02 3.7783E 02 3.722'7E-02 3.70508-02 3.63328 02 3.5500E 02 3.4'715E 02 3.34248-02 3.1637E 02 3.1582E 02 3.07448-02 2.9862E 02 2.9071E 02

2. 8183E 02

2. 7921E 02 2.7610E 02

2. 7251E-02 2.64648-02

2. 62218 02

2. 59618-02

2. 5159$ -02 2.4879E-02 2.3587E 02 2.34878 02 2.34878 02 2.3046E 02 2.2862E 02 2.2561E 02 2.2396E 02

2. 01308-02 1.99768-02 1.9068E 02 1.8482E 02 1.8460E 02 1.7923E 02 1.7578E-02 1.7390E 02 1.68038 02 1.6401E 02 1.5864E 02 1.5638E 02 1.5401E-02 1.50278-02 1.4360E 02 1.38368-02 1.3623E 02 1.3598E 02 1 ~ 3598E 02 1.3598E 02 1.3598E 02 1 ~ 3598E 02 1.295BE 02 1.2647E 02 1.2463E 02 1.2348E 02 1.20338-02 1.1096E 02 1.10438 02 1

~ 0785E 02 1.0479E 02 1.0317E 02 1.0013E 02 9.8947E 03 9.5096E 03 8.9890E 03 8.9828E 03 8.7182E 03 8.6950E 03 8.4541E 03 8.3792E 03 8.28$ 9E 03

$.1631$

03 8 '989E 03 4.3204E 02 3.4635E 02 3 '989E 02 3.6288E 02 2.8609E 02 3.2112E 02 1.8647E-02 2.9994E-02 2.90038-02

2. 4417E-02 2.81718 02 2.7024E 02 1.91508 02 2.7246E 02 1.3326E 02 2.29638 02

-1.1023E 02 1.9617E 02 2.03878-02

-1.2183E 02 1.39388-02 1.5046E-02 1.7227E-02 1.8253E 02 1.45'268 02 1.49538-02 1.51848 02 1.5605E-02 1.30698 02 1.4071$

02 9.3269E 03 3.90508 03 1

F 42988-02 I ~ 36358 02 1.3563$

02 1-31868 02 6 '628E-03

1. 10848-03

1. 21328-02 9 '8898-03 1.0634R 02 1.75268 03 7.42838-03 1 ~ 06368 02 1.01668 02 7.0071E 03 9.8045E-03 9.8947E-03

2. $ 105E 03 8.9017E-03 8.27938 03 7 '6638-03 8.67468 03 8.45298-03 1.0115E 03

-'7.48108-03 8 ~ 1610$

03

4. 61738-03 1.0000E+00 1.00008+00

1. 3180E+00 3.45188+00 L.OOOOE+00 1.0000E+00 1.0531E+00 1.0000E+00 1.0000E+00 9.62228-01 4.0004E+00 1.00008+00 1.29078+00 1.00008+00 1.3580E+00 1.0000E+00 L.00008+00 1.06048+00 3.25668+01 1.33'728+00 1.2643E+00 6.49688+01 1.2039E+00 1.12398+00 1.7445E+01 1.17398+00 1.12878+00 L.00008+00 L.OOOOEtoo 1.00008+00 7.4694E 01 2.19278+00 1.00008+00 1.06868+00 1 ~ 00008+00 8 '889E 01 1.00008+00 7 ~ 08628 01 1 ~ 00008+00 1 ~ 14968+00 1 ~ 55578i00 1.01128+00 I. 16328+00 L.OOOOE+00 6 '9648 01 6 '347E-OL 1 11548+00

1. 13778+00 1.4774E+00 1.0939E+00

1. 1197E+00 4.34698+00 1.65748+00 L.04798+00 1.0000E+00 1.0000E+00 L.00008+00 1 ~ 0000E+00 1

F 00088+00 1 '944E+00 1 ~ 07148+00 9 ~ 1 247E+00 1 ~ 11228+00 1 ~ 3159E+00

l. 1063E+00 1.45208+00 9.05148+00 1.2751E+00 1.42638+00 3 '3448+01 1 ~ 15098+00 9 ~ 7604E 01 I ~ 91618+00 9.66028+00 1.01228+00 1.13468+00 6.51828+03 9 '6908 01 8 '2358-01 4.50888+02 1.28098+00 9 '6808 01 9 '5368-01 9 ~ 63018-01 9 ~ 6371E 01 9 '1398-01 9 ~ 6789$

01 9

~ 8135E 01 9 '0018 01 9.'71008-01 9 '5588-01 9 ~ 71838-01 9 ~ 72988 01 9 ~ BOBSE 01 9.7275E 01 9 '6678 01 9.7704$

01 L.OLLOE+00 9e80328 01 9 ~ 19618 01

1. 01228+00 1,01398+00 9,84958 01 9.82778 01 9 ~ 81758 01

9. 854'78-01

1. 01508+00

1. 0152E+00 9.8440E 01 9.8693E 01 9.8593E 01 9.9067E 01 9.9610E 01 9.8570E 01 9.$ 636E 01 9.8644$

01 9.8681E 01 9.93048 01 9.9289E 01 9.87878 01 9.9081E 01 9.893'7$

01 9.98258 01

9. 9257E-01 9.8936E-OL 9.89$ 3E-OL

9. 9299E-01 9.9020E 01

9. 9011E-01 1.0028E+00

9. 9110$

01 9.91728 01

9. 92138 01 9.9133E 01 9.9155E 01 1.00108+00 L.00758+00 9 '184E 01 9.95388 01 L.OOOOE+00 1.00008+00 I ~ 1960E 01 1.3930E 02 1.0000E+00 1.0000E+00 4 ~ 1070E 01 L.0000$ ioo L.00008+00 1.0000E+00 I ~ 1950$

02 L.OOOOE+00 8.9590E-02 L.00008+00 8.2320E 02 1.00008+00 1.00008+00 2.3600E 01 9.4930E 04

'7.92008 02 8.4570$

02 4.4020E 04 1.1700E 01 1 ~ 33908 01 1.65408 03 7.11808 02 1.5140E 01 1.00008+00 1.0000E+00 1.00008+00 4.17408 02 1.6230$

02 1.0000E+00 2.29108 01 1.00008+00 8.50208 02 1.0000E+00 4.5650$

02 1.0000E+00 9.1410E 02, 3.0070E 02

6. 19008-01 8 ~ 1740E-02 1.00008+00 3.98408-02 3.6880E 02

1. 1910E-01 8.6610E 02 2.8628E 02 9.0310E 02 3.15908 02 4.25408-03 2.03208-02 2.2050$

01 1.0000E+00 1.0000E+00 1.00008+00 1.00008+00 9.42808 01 6 '6808 02 9.05508 02 I. 4910$ -03 7.5690$

02 3.2569E 02 1.6216E 02 1.61708-02 1.31938 03 3.56398 02 I ~ 61'70E 02 2.85408-04 6.15408 02 1 '5008-01 9.6170$

03 9.55108 04 3 '2208-01 6.0532E 02 1.29708 06 2.45908 01 6.4980E 02 1.8140$ -05.

1 ~ 61708-02 2.3488E 07 2.3488E-07 2.3174E 0'7 2.30548 01

'2.2808E 07 2.2808E 07 2.2190E 07 2.1918E-07 2 '9768-07 2.0260E 07 1.9962E-07 I ~ 9867E-07 1.94$ 2E-07 1 ~ 90368-01

1. 8615E-01 1.7922E 07 1.69648-07 1.6935E 07 1.6485$

07

1. 60128-07 1.55$ 8E-07 1.5112E-07 1.4971E-07

1. 4831E-07 1.4613E 07 1.4190$ -07 1;40608-07

1. 3921E-07 1.3491E 07 1.3340E-07 1.26488-07 1.2S948-07 1.2594E-07 1.23578-07 1.22598-07 1.20978-07 L.20098 0'7 1.0794E 07 1.07128 07 1.0225E 07 9.9105E 08 9.89838 08 9.6107$

0$

9.4253E 0$

9.32508 08 9.0099E 08 8.7944E 08 8.5063$

08 8.38518 08 8.2585E 08

8. 0517E 08 7.6999E 08 7.4188E 08 7.3050E 08 7.2916E 08 7.2916E 08 7.2916$

08 7.2916E 08

'7.2916$

08 6.94818 08 6 ~ 7816E 08 6.6829E 08 6.62128 08 6.4524E 08 5.9500E 08 5.9214E 08 5.7830E 08 5.61908 08 5.5324E 08 5.4010E-OB 5.3057E 08 5.0992E 08 4.8200E 08

4. 8167E-OB 4 ~ 6148E 08 4.66248 08 4.53328-08 4.4930E 08 4.4446$ -08 4.3115E 08 4 34288 08

MODEL Name~

BFNU2M Splic Fraction Xmporcance for Group Sorted by Fraction Importance Group Frequency 5.36218-06 07:06:03 09 MAY 1996 Page 4

At L SF Name...

Fraction...

Fussel-Vesely.

tmporrance fmporcance Birnbaum...

importance Achievement.

worch Reduction.,

SF Value..

Worth Frequency.

238.

239.

240.

241.

242.

243.

244.

245.

246.

247.

248.

249.

250.

251.

252.

253.

254.

255.

256.

257.

258.

259.

260.

261.

262.

263.

264.

265.

266.

267.

268.

269.

270.

271.

272.

273.

274.

27S.

276 277.

278.

279.

280.

281.

282.

283.

284.

28S.

286.

287.

288.

289.

290.

291.

292.

293.

294.

295.

296.

297.

298.

299.

300.

301.

302.

303.

304.

305.

306.

307.

308.

309.

310.

311 312 313 314 315 316 317 318 GFX ORP2 RDF RPD9 GF4 DRX SMXBX TBF FRX RPB6 PX23 DJF GC'I SW1D1 GD3 BVRX TORF RBCQ HRC1 HXAX ODWS2 GHi OALX FHX FFX GC6 HXC2 GCS HPZX HXD7 HXB5 RPB5 LPC2 DAX RPDX GF3 ABX Dt 1 DK1 RHX LC1 RVD14 V32 OHS3 HXDF PX11 FGX DB1 CS2 CSS HXBF GB3 OAD2 RS1 PX22 SP21 CS7 OHRF HS7 RPCX HXCF GH3 OUB2 HXAF FWHX HXBX OBDX JC1 TB2 RC1 LCF HXDX RPC3 SMXB2 OLC1 RBX 8'W2D4 SM1D6 DCAX UX4 OAL2 8.0839E 03 7.9812E-03

7. 88118-03 7.85528-03

/.65528 03 7.6552E 03

7. 6184E-03 7.4735E 03 7.39038-03 7.33598 03

7. 13528 03 7.00208 03 7.00078 03 6.94918 03 6.8088E-03 6.5294E-03 6.4428E-03 6.4257E-03 5.80938 03 5.70698 03 5.66138 03

5. 53168-03 5.1367E-03 5.06388 03 4 '8438-03 4.$ 328E 03 4.49928-03 4.4692E 03 4.33508-03 4.29188 03 4.2918E 03 4.22028-03 4.0604E-03

4. 0071E-03 4.0034E-03 3 '4988-03 3.8185E-03 3.77878-03 3.7780E-03 3. 71738-03 3.6623E-03 3.5416E 03 3.51838 03 3.4284E 03 3.42188-03 3.41638 03 3.4 BOE 03 3.33068-03 3.2291E 03 3.1946E 03 3.1653E 03

3. 1220E-03 3.00628 03 2.9263E-03 2 ~ 8601E-03 2.1769E-03 2.12048 03 2.66708 03 2.6489E-03 2.49048 03 2.3742E 03 2.37278 03 2.3441E-03 2.3436E 03 2.1824E 03

2. 1519E-03 2.1044E-03 2.0717E 03 2 '694E 03 2.0684E 03 2.0682E 03 1.8943E 03 1.8830E 03 1 ~ 8218E 03

1. 8176E 03 1 ~ 18698-03 1.17198 03 1.77798-03 l.'7061E 03 1.6404E 03 1.60368 03 4.1232E-04 4.2132E 03 7.1403E 03 6.$ 336E-03 3.4116E 03

-4. 51758-03 4. 3812E-03 5.0009E-03

1. 1340E-03 5.30808 03 3.6553E 03 6.5290E 03 2.6853E 03 1.1089E-03 5.59638-03 1.9957E 03

-5.4412E 03

1. 9081E 03 1.5191E 03

2. 28718-03 2.12448 03 4.1246E 03 4.46208-03 4.3897E 03

3. 01988-03 4.29188 03 4.1936E 03 3.1806E 03 3.6542E"03 2.2204E 03

-9.2292E 04 3.1592E-03 3.11468 03

-6.4132E 03

-6.3673E 03 3.5$ 44E 03 2.2434E-03

3. 5391E-03 1.6763E 03 2 '4208-03 2.6618E 03 4.6626E 04 1.65068-03

3. 15168-03 3.0561E 03 2.7576E-03 2.89648-03 2.8311E 03 2.8595E 03

-2.4599E 03 2.6032E-03 2.6489E 03 3 '2228 03 1.95838-03 2.24228-03 1.8552E-03 9.22468 04

1. 1256 E-03 2.0549E 03 1.0346E 03

1. 93118-03

-1.1113E 03 1.7573E-03 1.50008-03 X.78748 03 1.6488E-03 1.7671E 03 1.77798-03 1.76 IXE 03 5.6839E-04 4.55618 04 1.0025E+00 8 ~ 35088-01 1.00008+00 1.0113E+00 1.0385E+00 1.6860E+00 9.40098-01 1.00008+00 1.2656E+00 1.0073E+00

9. 9721E+00 1.00008+00

1. 0271E+00 9.5723E 01 1.06638+00 1.19238+00 1.0000E+00 9.1376E-ol 1.0669E+01 1.36178i00 8.0295E 01

l. 01418+00 1.0940E+00

1. 1392E+00 1.12938+00

1. 0521E+00

1. 1450E+00 1.04428+00 1.03238+00 1.0030E+00 1.0089E+00 1.2645E+00 1.44788+00 2.06168+00 8 '006E 01 1.0204E+00 2.72308+01 5 '865E 01 5 ~ 46308 01 2.3200E+01 X ~ 37798ioo 5.33158+00 1 ~ 0511E+00 1.4810E+00 1.0000E+00

4. 34778ioo 1.02848+00 1 ~ 80388+00 2,47988+00 4

~ 3904E+00 1.00008+00 1.0280E+00 2.9674E+00 2 '5948+01 1

~ 7339E+00 8 ~ 53838 01 1 ~ 0952E+00 1 ~ 00008+00 1.02688+00 6

~ 4101E 01 1.0000E+00 1 ~ 0119E+00 1 4444E+00 1 ~ 00008+00 1 ~ 58$ 6E+00 8 ~ 25888 01 1 '0758~00 1.0409E+00 1.01628+00 1.43908+01 1 ~ 00008+00 1.8769E 01 1 ~ 1209E+00 1.0928E+00 4.34798+00 1 ~ 2432E+01 1.0072E+00 X.OOXOEioo 6 '505E 01 1 ~ OXX28+00 1 ~ 02378+00

9. 9959E-01 1.00428+00

9. 9226 E-01 9.9317E 01 9 '658E 01 1.0046E+00 9.95628-01 9.9500E 01 9.9287E 01 9.9469E 01 1.00378+00 9.9347E 01

9. 9731E-01

1. 0011E+00 9.94408-01 9.9800E-01 1.00548+00 9.9809E 01 9.98488 01 9.97718 01 9 '788E 01 9.9528E 01 9 '554E-01 9 '5618-01 9.9698E 01 9.9571E 01 9.9581E 01 9.96228-01 9.96358 01 9.97788 01 1.00098+00

9. 96848-01 9 '6298-01 1 00648+00 1.00648+00 9.96428 01 9 ~ 97'l6E 01 9 ~ 96468-01 9 '8328 01 9 ~ 9146E 01 9.9734E-OX 9.99538-01

9. 98358 01 9 '685E OL 9.96948 01 9.9724E 01 9.9110E 01

9. 9717E-01

9. 9114E-OX 1 ~ 0025E+00 9 ~ 9740E-01 9.9735E 01 1.0031E+00 9.98048-01 9 '776E-OX 9.9814E-01 1.0009E+00 9.988IE 01 9.9I958 01 9.9$ 97E 01

9. 98078 01 X.OOXX8400 9.9$ 24E 01 9.9850E 01

9. 98218 01 9.98358 01

9. 98238 01 9.9822E 01 1.0018E+00 9.99438 01 9.9954E 01 1 ~ 4150E-01

'2 '9108 02 X.OOOOE+00 4

~ 01SOE 01 1

~ 507OE Ol 4

~ 95108 03 7

~ 09808 02 X.OOOOE+00 1.6230E 02 4.07008-01 7.9450E-04 1.00008+00 1.6380E 01 7.8740E 02 8.9590E 02 1.37708 02 X.OOOOEioo 1.26958 02 5,7846E 04 5.4880E 03 2.6900E 02 1.1520E 01 1.59108 02 1 ~ 61708 02

1. 61708 02 8.23208 02 2.9850E 02 9.0310E 02 8 '600E 02 5.8920E 01 3.21508 01 1.4090E 02 8.0944E-03 2.0872E 03 8.3250E 03 1.3390E 01 1.4160E 04 1.4010E 02 1.3840E 02 1.6143E 04 5.90208 03 8.1640E 04 2.8531E 02 5.25708 03 1.00008+00

7. 94508 04 1.6170E 02 2.0492E-03

2. 12528-03 9.005$ E 04 X.OOOOEioo 8.9590E 02 1.47008 03 1.1510E 04 3.8810E 03 1.65508 02 2.6615E 02 1.0000E+00 9.0000E 02 8.6220E 03 1.0000E+00

1. 41508-01 5.0200E 03 1.0000E+00 3.1422E 03 5.27008 03 1.3120E 01 4.'7790E 02 6.00588 02 1.44208-04 X. 00008i00 5.20'70E 03 1.4330E 02 1.59108 02 5.33608 04 1.44208 04 1.98008 01 6.36108 01 4.69088-03

4. 81158-02 1.88508 02 4.334'7E F 08 4.21968 08 4.2263E 08 4.2121E 08 4.loiBE 08 4.1048E 08 4.085XE OB 4.0074E 08 3.96288 08 3.9336E 08 3.8260E 08 3.7546E 08 3.7539E 08 3.7262E 08 3.6510E 08 3.5012E 08 3.4547E 08 3.4456E 08 3.1150E 08 3.06018 08 3.0357E 08 2.9661E 08 2.7544E 08 2.1153E 08 2.6726E 08

2. 59148-08 2.41258 08 2.39648 08 2.3245E 08 2.3013E 08

2. 30138-08 2.2630E 08 2.17728 08

2. 1487E-OB 2.146 IE-08 2.06438 08 2.04758-08 2.0262E 08 2.0258E 08 1.9933E-OB 1.9638E 08 1.89918 0$

1.88668-08 1.83848-08 1.8348E 08 1.8319E 0$

1.82748-08 1.7859E 08 1 ~ 73158-08 1.7130E 08 1.6973E-OB 1.6740E-OB 1.61208 08 1.5691E 08 1.53368-08 1.4890E 08 1.4581E 08 1.4301E-OB 1.4204E 08 1..3354E-OB 1.27318 08 1.27238 08 1.25698-08 1.25678 08 1.1'102E-08 1.15398-08 1.12848 08 1.1109E 08

l. 10968-08 1.1091E 08 1.1090E-OB

1. 0158E-08 1.00918-08 9.76868-09 9.7464E-09 9.58118 09 9.5336E-09 9.53368 09 9 ~ 1481E-09 8.1959E-09 8 '9888 09

0

NODCL Name:

BFNU2H Split Fraction Importance for Group

ALL Sorted by Fraction Importance Group Frequency

~ 5.3621E-06 07:06:03 09 NAY 1996 Page 5

SP Name...

Fraction...

Fussel-Vesely.

Importance Importance Birnbaum...

Importance Achievement.

'Worth Reduction...

SF Value...

Worth Frequency.

0 319.

320.

321.

322.

323.

324.

325.

326.

327

'28.

329.

330.

331.

332.

333.

334.

335.

336.

337.

338.

339.

340

'41~

342.

343

~

344

~

345.

346.

347.

348

'49.

350.

351

'52

'53.

354.

355.

356.

357.

358.

359

'60.

361

~

362

'63.

364.

365

'66

'6'68.

369.

370.

371.

372.

373.

374.

375.

376.

377.

378.

379.

380.

3814 382.

383.

384.

385.

386.

387.

388.

389.

390.

391.

392.

393.

394.

395.

396.

397.

398.

399.

RCL1 DCI RPDS SW2D6 Ul1 RVC7 OJC1 U31 ODWS1 EA2 SW1D14 HXCl FC2 DD1 AD1 OHR1 SWIC7 RPD7 PCAA H$ 6 RXS2 HXB6 HS4 GG3 DHl RBCT SL2 RBCN GFS

$86 U842C1 EBS VNT1 882D7 H$2 CI81 GHS FB2 HPL1 EAl OF4 EC10 OSP2 DV2F SW1D17 RT1 HS3 RX$10 ED29 HPL3 SW1D16 RI 1 DJ1 ED34 SP11 SW2D5 RT3 DGB RK3 HPLS SDCF PX21 FWH2 CD1 EC12 CRD3 GHC4 EB2 CRD2 PCAB HXD10 GHI 1 DV2 1 NH11 NH21 EDS EC2 DFI RPDB AD32 EBI 1.6014E 03 1.5994E 03 1.5837E-03 1.5493$ -03 1.4642E-03 1.4584$ -03 1.4322E-03 1.4305E-03 1.3840E-03 1.3784E 03 1.3139E 03 1.2026$ -03

1. 1691E-03 1.1064E-03 1'.0498$ -03 1.0009E-03 9.8109E 04 9 '999E-04 9 '557E-04 8 '945E 04 8.5366E-04 8.4032E-04 8.2599E-04

8. 1322E-04

7. 9672E 04 7.8314$

04 7.68398 04 7.4489E 04 7.2326E 04 7.0939E 04 6.9647E 04 6.9235E 04 6.9186E 04 6.8216E 04 6.8176$

04 6.'7773E 04 6.'7755E 04 6.7368E 04 6 '8138 04 6.4645E 04 6.3063E 04 6.2043E 04 6.1956E-OI 5.9665E 04 5 '405E 04 5.7318$

04 S.'7186E 04 5.6947E 04 5 '730E 04

'5.3575$

04 5.2373$

04 5.1909E 04 4.9371E 04 4.9234E 04 4.7964$

04 4.6123E 04 4.5414E 04 4.4386E 04 4.4216$

04 4.2277$

04 4.1815E 04 3.8385E 04 3.8025$

04 3.76338 04 3.7381E 04 3.7113E-04 3.7078E-OI 3 '027E-04 3.6898E-04 3.6539E 04 3.6393$ -04 3.6386E-04 3.6062$

04 3 ~ 3817E 04 3.3810E 04 3 '5S3E 04 3.3553E 04 3 '246E 04 3 ~ 1744E 04 2 '9588-04 2 '225E 04

-6.9795$ -04

-8.5142E 05 9.7785$ -04 8.3396E-04 1.1765E 03 1.4550E-03 1.2867E-03 I ~ 1013E 03 4.4513E 03 7.9347E 04 6.2223$

04

-2. 2231$ -03 7 '64OE 04 6.0225E 04 9.4614E-04

9. S691E-04 5.9051$

04 9.5999E 04 1.3317E 03 8.5945E 04 8.5359$

04 5

~ 8941$ -04 8 '5998-04 9.3519E 05 7 '347E-Oh

-1.0897E 03 7.5709$

04 6.5874E 04 6.3330E 04 6.6121E 04 6.0166E 04 6.9130$ -04

-5.2956E 05

-5.9693E 04

6. 8176$ -04

-3.5155$ -03 5.4675E-05 3.4482E 04 1.3206E-03 3.1659E 05 2.6202E 04 5 ~ 9601$

04 1.20388 03 4.0453E-04 4 ~ 8154$ Ol 5.7186E 04 5.6881E 04 4.6191$

04 4 '408E 04 3.5829$

04 3.8221$ -04 3.3279$

06 4.8312$

04 3.4617$

Ol 5.1631E 04 4.4841E-04 4 '3238 Oh

-8.4462E 04 4 '7328 05 3.6589$

04 3.4176$

05 2.32898 04 2 '725E 04

-3.5649E-04 1.3092$

03 3.6677E 04 3.6779E-04

4. 8561$ -04 1+32608 04 1 ~ 5049E 04 3.4669$

Oh

-2.5283E-03 2.4833E-03 3.3553$ -04 3.3553E Ol 2.4721E 03 1.6818$

04 2.8719$ -04 3.9922E 04 9.6239$ -01

9. 58I9$ -01 1.06738+00 9.8192E 01 1.0207E+00

1. 62198+00 1.0389E+00

1. 01958+00 5.5568E 01 1. 2 0 5 1E+ 00 9.9186E-01 5.8693E-01 1.04428+00

'7. 01588-01 7.6808E+00 1.02868+00 1.0085E+00

l. 0014E+00 5.4655$ -01 1.0052E+00

4. 08878+01 1,10688+00

1. 00198+00 9.9936E-OI

1. 14 968+00 9.4458E 01 1.0268E+00 9.88108-01 1.0064$ <<00

1. 17268+00 5.68388+00 1.0212E+00 9.8869$

01 9.8630E 01 1.00738+00 1.6944E OI 9.9941E 01 1.02108+00 9.2271E 01 9.6666E 01 9.6657$ -01 1.0006E+00 7.9272E-01 1.00008+00

1. 0051E+00

5. 1832E+00 1.0095E+00

1. 86108+02

1. 00018+00 1.00528+00 1.0049E+00 3.3673E+00

9. 9341$ -01 1.12908+00

1. 39418+00 9.8850E 01 4.895IE+00 1.2480E+00 9.6607$ -01 1.00278+00 1.00008+00 5.3838E-01 1 00148+00

8. 1466E 01 1.0668$ <<00

9. 9114E 01 8.7482$

01 1.0289$ <<00 1.0434E+00

9. 9125$

01 1.02408+00 1.1019$ +00 1.O764$ +OO 1.6341E 01 1.6805E 01 1.00088+00 1.02878+00 2.2905$

01

1. 0119E+00 1 ~ 41128+00 S. 8794E 01 1.0007E+00

1. 0001E+00

9. 9902$ -01 1.0008E+00

9. 9882$

01 9.9855E-01 9.9871E 01 9.9890E-01 1.0045$ <<00 9.9921$

01 1.0006E+00 1.0022E+00 9.9927$

01 1 ~ 0006E<<00 9 ~ 9905$

01

9. 9904$

01 9.9941E 01 9 '904E 01 1.0013E<<00 9.9914E 01 9.9915E 01 9.9941$

01 9.9917$

01 1.0001E+00 9.9924E 01

1. 0011E+00 9.9924E 01 1.0007E+00 9.9937$

01 9.9934E 01 9.9940E 01 9.9931$

01 1.00018+00 1.00068+00 9.9932E 01 1.0035$ <<00 I.. 00018+00 9.9966$

Ol 1.00138+00 1.0000E<<00 1.0003E+00

9. 9940$ -01 1 00128+00 9 '9608 01 9 '9528-01 9 ~ 9943$

01

9. 9943E 01 9.9954E 01 9.9953E 01 9.9964$ -01

9. 9962$

01 1.0000E+00 9.9952E-01 9 ~ 99658 01 1.00058+00 9 9955E 01 9.99S6E 01 1.0008E+00 9.9995$

01 1.0004E+00 9.9997E 01 1.00028+00 9.9974$

01 1.0004E+00 1 ~ 00138+00 9.9963$ -01 9 ~ 9963$

01 1.00058+00 9.9987$ -01 9.9985E 01 9 ~ 9965$

01 1.00258+00 1.00258+00 9 ~ 9966$

01 9.9966$ -01 1 0025E+00 9.9983$ -01 9 '9718-01 1.0004E+00 1 ~ 82208-02 2.0467$ -03 1.4330$ -02 4.4100R 02 5.3889$

02 2.3340$

03 3.2040R 02 5 '5398-02 9.9190$

03 3 '5408 03 7 '9808 02 5.3530$

03 1 ~ 6160$

02 2 ~ 0141$

03 1 ~ 4160$

04 3.2400E 02 6 '9808-02 4 '7008 01 2 '283E 03 1 ~ 4200E 01 2.1400$ -05 5

~ 4880$

03 3.0000$

01 1 ~ 2830E 01 5.0780E 03 1.9284$

02 2.7449$

02 5.2470$

02 9.0550$

02 3.8170E 03 1 ~ 2844$

04 3 '580E 02 Is6587$

03 4.1740E 02 8.5000E 02 4 ~ 2148$

03 8.4570$

02 1.6160$

02 1 ~ 6800E 02 9.4870$ -04 7 '7708-03 5 ~ 0110E 01 5.7740$

03 1.0000E+00 7.2920E 02 1.1510E 04 5.7000E 02 3.0730E-06 7.8590$

01 8.3410E 02 6.8680E-02 1.6143E 04

5. 0510E-04 3.7310$

03 8.7750E 04 4.2970E 02

1. 1510E 04 1.7840$

03 2.4290E 02 1.8020E 02 1.0000E+00 7.9200$ -04 2.4612E 02 1.2550$

03 3.8390E-03 3.8661$

02 1.0350$ -02 1.2530$

02 8.3944E-03 5.2577E-02 5.4880$ -03 1.4740E 03 4.5200$ -03

3. 0130E-03 2.9760$ -03 2.9250E 01 1.1550E 02

3. 1963E-03 1.39308 02 6.9790E 04 9.6790$ -04 8.5871E 09 8.5765$

09 8.4922E 09

'.3074E 09 7.8510$

09

7. 8201$ ~ 09 7.6796E-09 7.6706$

09 7.4214E 09 7.3914E 09 7.0454E 09 6.4485E 09 6.2688E 09 5.9327E 09 5.629IE 09 5.3668$

09 5.2607$

09 5.1476E 09 4.8558$

09 4.6085E 09 4.5774E 09 4.5059E 09 4.4291$

09 4.3606E 09 4.2721E 09 4.1993E 09 4.1202E 09 3.9942E 09 3.8782$

09 3.8039$

09 3.7346E-09 3.7125E 09 3.7099E 09 3.6579E 09 3.6557E 09 3.6341E 09 3.6331E 09 3.6124E 09 3.4754E 09 3.4664E 09 3.3815$ -09 3.3268E 09 3 '222E 09 3 ~ 1993E 09 3 ~ 0781$ -09 3.0735E-09 3 '664E 09 3 '536E 09 3 ~ 0419E 09 2 '728E 09 2 '083E-09 2 '8348 09 2 '473E 09 2.6400E 09 2 '71.9E 09 2 '732E 09 2 '352E 09 2 '800E-09 2.3709E 09 2.2670$ -09 2 '422E 09 2.0583E 09 2 '3908-09 2 ~ 0179$

09 2 '044E 09 1 ~ 99018 09 1 ~ 9882R 09 I ~ 9854E 09 1 ~ 9785E-09 1 ~ 95928 09 1.9515$

09 1.9511E-09 1,9337E 09 l.8133E-09 1,8129E-09 1 ~ 79928 09 1.7992E 09 1.7291$

09 1.7021E 09 1.6064$

09 1 ~ 5671E 09

~ 'A<<

PLG

MODEt Name:

BFNUXM Split Fraction tmportance for Group Sorted by Fraction Importance Group Frequency e 5.362XE-06 0/:06:03 09 NAY 1996 Page 6

ALL SF Name.

Fraction.

Importance Fussel-Vesely.

Imporrance Birnbaum...

Importance Achievement.

worth Reduction...

SF Value...

Morth Frequency.

400.

401.

402.

403.

404.

405.

406.

407.

408.

409

~

410.

411

~

412.

413.

414.

415.

416.

417.

418.

419.

420.

421.

422.

423

'24.

425.

426.

427.

428.

429.

430.

431.

432.

433.

434.

435.

436.

437.

438.

439.

440.

441

~

442.

443.

444.

445.

446.

447.

448.

449

'50.

451.

452.

453.

454.

455

'56.

457.

458.

459.

460.

461.

462.

463.

464.

465.

466.

467.

468.

469.

470.

471.

472.

473.

4 l4.

415.

476.

417.

478.

q 479.

480.

SM1D11 RT2 NBOCF RVL3 RPTX SGT2 DE2 DF2 LPC1 GB6 DK2 HXD3 DGL GCS EC4 OLP3 SW2C4 SMXA2 SM1C6 VNT2 RXS4 SDREC2 ED10.

DMS2 RPB2 GC9 DL4 HSS FF2 NPII3 AD5 SP13 FF3 FG2 OSP3 Rt 6 HRX CSTF OSVX SM2D9 HRC3 CD5 DX6 SHUTXX DGH DH4 ACX DV11 RBCU DD2 RBCA IVC1 RJ1 HRCS SW2CS DGA EC11 SGTX Ox 1 OG161 A3EA2 U13 FH2 OSD1 RPB4 SPRXX ODSB1 ORP3 CD6 AAX HXD2 ED32 A3EB21 AD23 AC4 SM1D2 SM2DS SP2 OSMX RBCV 2.6864E 04 2.66198 04 2.6529E 04 2.58598 04

2. 5818E-04 2.4595E 04 2.26438-04 2.22018 04

2. 1506E-04 2.1220E-04 2.10298 04 2.0737E 04

'2.02038 04 2.01248-04 1.9819E 04 1.89768>>04 1.8651E-04

1. 8651E-04

1. 8651E 04 1.8463E 04 1.82208 04 1.7636E 04 1.72088 04

1. 63818-04

'1.59288 04 1.56128 04 1.5592E 04 1.51258 04 1.49718 04 1.47328-04 1.3899E-04 1.2803E 04 1 ~ 2783E-04 1.21838 04 1.27838 04 1.23798 04 1 ~ 22138-04 1.20788-04 1.19418 04 1 ~ 19058 04 1.1170E-04 1.0983E-04 1.05698 04 1.0115E 04 9.89958 05 9.66358 05 9.66358 05 9.60848 05 9.0562E 05 8.9225E 05 8.79108 05 8.48868-05 8.36608 05 7.97358 05 7.64768-05 7.37688 05 I.35'74E 05 7.20548 05 7.1600E 05

'1.06578 05

7. 0061E-OS 6.9841E 05 6.7421E-OS 6.3801E 05 5.7924E 05 5.46428-05

5. 11468-05 5.09258 05 5.0501E 05 5.0335E-OS 5.02688 05 5.0242E-OS 4.8924E-OS 4.60128 05 4.43978 05 4.4149E 05 4.38158-05 4.3369E 05 4.2761E 05 4.2486E 05 4.0782E 05

-2.9022E-04 2.6590E-04 2 '8598 04 2 '2008 04

-1 ~ 0669E-03 3.9420E 04

-9 '373E 05

1. 83318-04

2. 12208-04

8. 55/2E-04 1.32948-04 1 '6608 04 1.9878E-04 1.12048-04 8.45448 o4 1.8651E 04 7 ~ 8015E-05 1.8651E-04

-8. 2761E-04 1.81978 04 1.11148-04 1.72088-04

-7. /8628-04 5.69968-05 1.0883E 04 5.88508-04 1.5125E 04

-2.3099E 05 1.46898 04 1.3877E 04 8.82058-05 1.21838-04 1.27838 04 2.28048 05 1.15418 O4

-6.35978 04 X.0996E-04 3.64528 04 8,1307E 05 1.0126E 04 6.85678 05 4 ~ 1301E 04 1.09038 05 9.6635E 05

6. 19828-06

-'I.7137E 06 8.6596E 05 1.54148 04

-1.33828 04

-1.99418 04 8.25928-05

-5.72108 05 6.55148 05 3.2780E 04 4.4790E 05 5.14488 05

-1.1839E 03

-8.4791E 05

-3'.67818 04

3. 1563E-06

-2.42348 04 1.89838-04 6.2850E 06 1.28028 05 5.0921E 05 8.46608-05 1.78818 04 8.5410E 05 5.4411E-OS 4.1150E 05 2.4608E 05 2.32518 05 2.65018-05 1.39518-05 2.3121E 04 1.4449E 04 1.81678 04 5.8509E 04 1.5170E 04 9.9635E 01 3 '5988+00 1.0000E+00 1

~ 32XXEi00 2.83428+00 9.59428 01 9.1562E 01 9 '5498-01 X.57948 F 00 X.00228+00 9.2285E-01 1.00768+00 1.12198+00 1.00208+00 1.00028+00 8.63758-01 X.00078+00 9.95108 01

1. 00018+00 8.63758 01 9.78238+00 1.03608+00 1.00038+00 9.59548 01 1.00298+00 1.00118+00 9.47238 01 1.00108+00 9.9859E 01 X.SX458ioo 3.4577E+00 9.93468 01 1.0000E+00 1.00058+00 9 ~ 98908 01 2.59998+00 9.7445E-01

1. 01218+00 1.00008+00 8.44128 01 1.00438+00 1.35458+00 1.02458+00 9.6276E 01 X.08878400 1.06908+00

l. 01128+00 9.45538 01 l.01178+00 9.93168 01 9.1338E 01 9.97998 01

2. 07198+00 6.45668 01 X.X9798ioo

9. 91448 01 1.0089E+00 X.OOX68400 2.33878-01 9.46968 01 3.78958 01 9.9637E-OX

9. 95518 01 9.8844E-01 1.00598+00 1.00098+00 1.0969E+00 9.47508 01 9.96008 01 9.90368-01 6 '580E-OX

9. 9223E 01 1.0000E+00 1 ~ 02898+00 1.03978+00 X.02098+00 9.80708 01

9. 9106E-01 9.19378 01 2.2284E-OX 9.6751E-01 1.00038+00 9.99738 01 9.9974E-01

9. 9919E-01

1. 0011E+00 X.00048100 1.000XEioo 9.99828 01 9.9979E 01 1.00098+00 9.9987E 01 9 '988E-01 9 '980E-01 9 '989E-01 1 ~ 0008E+00 9 '981E-01 1 ~ 0001E+00 9 ~ 99818 01 1.00088+00 9 ~ 9982E 01

9. 9989E 01 9 ~ 9983E 01 1 ~ 0008E+00 9 '9948 01 9 '989E 01 1 ~ 00068+00 9 '985E 01 X.00008ioo 9 '9858 01 9 '986E-OX 1

F 00018+00 9 '987E 01 9.9987E 01 1.00008+00 9 '9888 01 1.0006E+00 9.99898-01 1.0004E+00 9.9992E 01 9.9990E-01 9.99938 01 1.0004E+00 9.9999E 01 9.9990E-01 9 '9998 01 1.0000E+00 9.99918 01 1.0002E+00 1.00018+00 1.0002E+00 9.9992E-01 1.0001E+00 9.9993E 01 1.0003E+00 9.99968 01 9.9995E-01

l. 00128+00

1. 0001E+00 1.00048+00 X.00008+00 1.00028+00 1.00028+00 9.99998 01 9.99998 01 9.99958 01 1.00018+00 1.0002E+00

1. 0001E+00 X.OOOXEioo 1.0000E+00 9.99988-01 9.9998E 01

9. 99918-01 9.99998 01 1.0002E+00 1 ~ 0001E+00 1.00028+00 X.00068+00 1.0002E+00 l.35908-02 1.2310E 04 X.OOOOEioo 8.04808-04 1.155'IE 04 2.56198-02

4. 65018-03 2.6116E 03 3.1630E-04 8.9590E 02 1.0970E-02

1. 7170E-02 9.5550E-04 8.9590E-02 3.3360E-01 6.1670E-03 2 '6908-01

1. 5610E-02 6.59908-01 6.037/8 03 2.07208 05 3.07608 03 3.4S608 01 1.88838 02 1.95808 02 8.96208 02 1.1030E 02 1.2600E-01 1 ~ 6160E 02 2.8540E 04 5.64608 OS 1.33008-02 9.4280E 01 2.2050E-01 2.0320E-02 7.21308 05 2.42908 02 9.0000E-03 1.0000E+00 2.33308-03 1.85708-02 2.SSSBE 04 2.7922E 03 1.0970E 02 1.2290E-04 1.39908 03

5. 5120E-04 1.4160E-04 4.86508 03 2.20398 02 1.5425E 03 9.0372E-02 7.70448 05 1.6143E 04

3. 3091E 04 3.6880E 02 5.0000E 03 3.16908 02 1.5429E 03 1.5960E 03

5. 9198E-04 8.69708 04 5.1228E 02 1.61608 02 1.0630E 03 1 ~ 4330E 02 5.25308 04 1.61008 03 4.2740E 02 8 '8478 03 1.41608 04 5.27008-03

5. 1250E 01 8 ~ o44oE oi 6 '700E 04 6.6700E 04 1.1840E-02 1.59108 02 8 ~ 7310E-03

'/.5230E 04 4.6474E 03 1.4405E 09 1.4274E-09 1.42258 09 1.3866E-09 1.3844E-09

1. 31BBE-09 1.214XE 09 1.1904E-09 1.1532E 09

1. 1378E-09

1. 1216E-09

1. 1120E 09 1.0833E 09 1.07918-09 1.06278-09 l.01758-09 1.0001E 09 1.0001E-09 1.000XE-09 9.9004E 10 9.76968 10 9.4566E-XO 9.22738-10 8.18678-10 8.54118 10

8. 37148-10 8.36078-10

8. 1101E-10 8.0277E-10 7.8994E-10 7.4527E-10 6.8653E 10 6.8545E 10 6.85458 10 6.8545E 10

6. 6317E-10 6.5490E-lo 6.4766E 10 6 '0288"10 6.3835E 10 5.9895E 10 5.8891E 10

5. 6671E-10 5.4236E-10 5.30838-10 5.1817E-10 5.18178 10 5 ~ 1522E-10 4 '56XE-10 4.7844E-XO 4.11398-10 4.5517E 10 4.4860E-10 4.2755E 10 4.1007E-10 3.9555E 10 3.9451E-XO 3.863/8 10 3.8393E 10 3.7887E-XO 3.7571E-10 3.1450E 10 3.6152E-10 3.42118 10 3.10608-10 2.93008 10 2.7425E-XO

2. 7306E-10 2.'IOBOE 10 2.6990E-10 2.6954E-10 2.69418 10 2.6234E lo 2.4673E 10 2.3806E 10 2.3673E-10 2.3494E 10 2.3255E 10 2.29298 10 2.2781E 10 2.1868E 10

~~y'signs<- nn/ neuter, P[ Cv

0

MODEL Name:

BFNU2N Split Fraction Importance for Group Sorted by Fraction Imporrance Group Frequency 5.3621E-06 0/:06:03 09 NAY 1996 Page 7

SF Name...

Fraction...

Fussel-Vesely.

Importance Importance Birnbaum...

Importance AChieuement.

Worth Reduction...

SF Value..

Worth Frequency.

481.

482

~

483.

484.

485.

486.

487

~

488.

489.

490.

491.

492.

493.

494.

495.

49Y.

497.

498.

499.

500.

501.

502

'03.

504.

505

~

506.

507.

508.

509.

510.

511.

512

'13.

514.

515

~

516.

517 518

~

519.

520.

521.

522.

523.

524.

525.

526.

527 Ri,l RKX RVO2 EB4 ED27 ED36 EPRXB Lvl DWSX AB2 AC14 SWXC3 ED30 A3ED23 ED31 UBREC2 FC3 AC18 SPRX BPX AD3 5 LBHX A3ED4 SWXD8 RRX DA2 DB2 LV2 DC2 RDX A3EC8 HXB3 RCWXA OG5I ED9 RPT8 RQX RPT2 RPTS RR3 RPD6 SW2C3 SW2D2 SM2C2 SWXDNN TBB SW2D3 528.

TBO 529.'XNN 530

~

SMXD12 531

~

SMXDXS 532.

533.

534.

535.

536.

SW1DXO BWXD9 SW1D4 SMXD18 SW1D3 537.

SMXCNN 53'B43AX 539

~

UB4 3B1 540

~

UB42B4 541.

UB42BX 542.

METS 54 3.

UBRECX 544.

UBREC3 545.

U3NN'46.UB41A2 547.

UB41B1 548.

UB41Al 549.

UB42A3 550.

UB42AX 551.

UB41B3 552

~

RVD13 553.

RXSO 554

~

RKS5 555.

Rxl 556.

RVOB 557.

RY3 558.

RXB7 559.

RY1 560 'DREC1 561.

RVD18 4.0671E-OS 4.0670E 05 3.4513E-OS 3.1844E 05 2.9981E 05 2.9339E-OS 2.8332E-OS 2.5117E 05 2.4727E 05 2.4569E 05

2. 4410E 05 2,4304E 05 2.3887E 05 2.3805E-OS 2.3328E-OS 2.3123E-OS 2.3112E-05 2.2984E 05 2 ~ 1572E 05

2. 1572E 05

2. 1550E-05 2 '092E 05 2.0519E-OS 2.0507E-OS 2.0263E 05 1.9721E 05 1 ~ 9333E-05 1 ~ 9215E-OS 1 '182E-OS X'139E 05 1.8992E-OS.

4 '797E 06 8.1924E 07 4.6380E 07 2.6463E 07 0.0000E+00 0 ~ OOOOE<<00 0.0000E<<00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0 ~ OOOOE<<00 0.0000E+00 0.000OE+00 0.0000E+00 O.OOOOE<<00 0.0000E+00 0.0000E<<00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E<<00 0.000OE+00 0.0000E+00 0.0000E+00 0.0000E+00 0 '000E+00 0.0000E+00 0 ~ OOOOE+00 0.0000E<<00 0.0000E+00 0.0000E<<00 0.0000E+00 0

~ OOOOE+00 0.0000E<<00 0 ~ OOOOE<<00 0.0000E<<00 0.0000E<<00 0.0000E<<00 0 ~ OOOOE+00 0 ~ 0000E+00 0 ~ OOOOE<<00 0

~ OOOOE+00 0.0000E+00 0.0000E<<00 0.0000E<<00 0.0000E<<00 0 ~ OOOOE<<00 0 ~ OOOOE+00

-6. 6'731E-OS 6.6737E-OS 2.8960E-OS 3.0524E-04 2.2373E 05 8.764'7E-05 2.3588E-OS 4.0901E 05

-8.5645E 04

-3 ~ 8291E-05 1.6678E-OS 4.7589E-OS

~

0.0000E<<00

-6.9545E-06 2.3328E 05 9.9158E-OS 8.93XBE-06 1.3952E 06 2.1572E 05 1.4242E OS 8.6595E-07

-1. 5395E-04 6.9308E 06

-8.1329E-05

-2.5838E-04

-1. 8676E-04

-2.3911E-04 1.2212E 05 2.3493E 04 1.2270E 04

-2.4265E-OS

-1 ~ 8661E 04

2. 6170E-06 2.3963E 04 1.8593E 09 1.2118E 06 2 '458E-04 1.4327E 07 1.4950E 06

-1.0126E-05

-3.5718E 05 1.9266E 04

-5.2043E-OS 5.5224E-OS

-2.0622E 04

1. 1147E-OS 1.0111E 05

-1.1053E 05

-1.4650E 05 4.6669E-06

-9.758IE 07 5.7871E 05 1.7588E 04 1.8373E-04 4.5292E 06

-1.6727E 04

1. 9195E-05 5.1020E 06

-4.5252E 06 1.6727E 04

-1.6'727E 04 4.5272E 06

-1.6727E-04

-7.1452E 07 6.3919E 08

-1.2253E 09

-5.4847E-04 4.0230E 05 5.7379E 07 5.3819E 04 2.4177E 04 9.9164E 06 5 ~ 054 0E 01 5 '535E 01 3 ~ 1108E+00 9 '803E-OX 1.0060E+00 9 '724E 01 1.0505E<<00 4

~ 1400E-01 3 ~ 4892E-01 9 '5X7E-01 1.0239E+00 9.9500E-OX 1.0000E+00 9.9103E 01 1.0014E+00 9.8827E-OX 1.0005E+00

l. 0018E+00 1.0496E<<00 1.0308E+00 1.0011E+00

9. 9463E-01 1.0092E+00 9.9144E-OX 2,6498E-OX 8.7966E 01 8.4284E 01 1.0029E+00 8.4436E-01 1.4925E-OX 9.6986E 01 9.6533E-OX 5.1884E 01 3.8941E 01 1.000OE+00 9.9614E 01 1.41'71E-01

9. 98 /7E-01 9.9982E-OX 9 ~ 7119E 01 9.9'750E 01 9.8366E 01 9.9341E-01 9.9242E-OX 9.8064E 01 9.9915E 01 9.9937E 01 9.9996E-01 9.9888E 01 9.9996E-01 9.9991E 01 9.9343E-01 2.1203E 01 2.1203E-01 9.7979E 01 2.8321E 01 9.9766E 01 9.9922E-01 9.79'79E-01

2. 8321E 01 2.8321E-OX 9.7979E 01 2.8321E 01 9.7979E-01 9.9992E-01 9.9994E-01 1.2816E 01 9.3705E 01 9.7160E 01 1 ~ 5829E-01 9 ~ 2382E 01 9 '690E-OX 1.0001E<<00 1.0001E<<00 9.9997E 01 1.0003E<<00 9.9998E Ol

1. OOOXE+00 9.9998E-OX 1.000OE<<00 1.0009E+00 X.OOOOE<<00 9.9998E-01 1

~ OOOOE+00 1.0000E+00 1.0000E+00 9.9998E 01 1.0001E<<00

9. 9999 E-01 1.0000E+00 9.9998E-01 9.9999E-OX 1.0000E+00 1.0002E+00 9.9999E 01

1. 0001E<<00 1.0003E+00 1.0002E+00 1.0002E+00 9.9999E-OX 1.0002E+00 X.0001E<<00 1.0000E+00 1.0002E<<00 1.0000E<<00 1.0002E+00 1.0000E+00 1.0000E+00 1.0003E+00 1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00 1.0002E<<00 1.0001E+00

1. 0001E+00 1.0000E+00 1.0000E+00 1.0002E<<00 1.0000E+00 1.0000E<<00 1.0000E<<00 1.0000E+00 1.0000E+00 1.0000E+00 X.OOOOE+00 1.0000E+00

1. 0001E+00 1.0000E+00 1.0002E+00 1.0002E<<00 1.0000E+00 1.0002E<<00 1.0000E+00 1.0000E+00 1.0000E<<00 1.0000E+00 1.0000E+00 1.0002E+00 1.0002E+00 1

~ 0000E+00 1'0002E<<00 1 ~ 0000E+00 1.0000E<<00 1 ~ 0000E+00 1 ~ 0000E+00 1 ~ OOOSE+00 1 ~ OOOOE+00 1 ~ OOOOE<<00 1 ~ 0000E+00 1 ~ OOOSE<<00 1 ~ 0002E<<00 1 ~ OCOOE<<00 1.3490E 04 1.3490E-04 1.3720E 05 3.7100E-03 3.7290E-03 3.8370E-03 4.6650E 04

6. 9791E-OS 1 ~ 3137E 03 6 '790E-04 6.9 /90E-04 9.4230E-03 5.0180E-OX 7.7500E 04 1.5900E-02 8.3859E 03

1. 6170E 02 7.6310E 04 4.3480E 04 4.6180E 04 7.6310E-04 2.7872E-02 7.5350E-04 9.4140E-03

3. 5140E-04 1.5495E 03

1. 5191E 03 4.2520E 03 1.5072E 03 1.4420E 04 8.0440E-04 5.3530E 03 5.4390E-06 3.9230E-04 3.7100E-03

3. 1400E-04 3.4310E-04 1.1631E 04 8.1386E 03 3.5140E 04 a

1.4090E 02

1. 1650E-02 7.8300E 03 7 ~ 2310E 03 0,0000E+00 0.0000E+00 1 '540E 02 0

OOOOE+00 0 ~ OOOOE+00 1 '940E 02 1 '910E-02 2 '310E-01 1 ~ 2880E 02 9 '230E-02 1 ~ 1290E 02 8 '290E-03 0.0000E+00 2.2316E-04 2.3311E 04 2.2410E 04 2.3330E 04 0.0000E+00

8. 1422E-03 6.4999E 03 0.0000E+00 2.2390E 04 2.3330E-04 2.3330E 04 2.2400E-04 2.3330E 04 3.5360E 05 8.0480E 04 0.0000E+00 2 ~ 1000E 05 6.2870E 04 0.0000E+00 6.3870E 04 2.0200E 05 6.3900E 04 3 ~ 1638E 03 7.5630E-04 2.1808E-XO 2.1808E 10 1.8506E-XO 1 ~ 7075E 10 1.6076E 10 1.5732E-10 1 ~ 5192E-XO 1.3468E 10 1.3259E-10

1. 3174E-XO 1.3089E-XO 1.3032E 10 1.2809E 10 1.2765E-10 1.2509E-XO 1.2399E 10 1.2393E-10 1.2324E 10

'.1567E-10

1. 1567E-10 1.1555E 10 1.1310E-10 1.1003E-XO 1.0996E-XO 1.0865E-10

1. 05'75E 10 1.0367E 10 1 ~ 0303E 10 1 0285E-10

1. 0263E-XO 1.0184E 10 2 '702E 11 4.3929E 12 2.4870E 12 1 'X90E 12 0 ~ OOOOE+00 0.0000E<<00 0.0000E<<00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E<<00 O.OOOOE<<00 0.0000E<<00 0 ~ 0000E<<00 0.0000E+00 0.0000E<<00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0 ~ OOOOE+00 0.0000E+00 0 ~ OOOOE+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E<<00 0.0000E+00 0.0000E+00 0 ~ OOOOE+00 0.0000E+00 0.0000E<<00 0 ~ OOOOE+00 0.0000E+00 0 '000E+00 0 '000E<<00 0.0000E<<00 0.0000E<<00 0.0000E+00 0.0000E+00 0.0000E<<00 0.0000E+00 0.0000E<<00 0.0000E+00 0 ~ OOOOE+00 0.0000E<<00

MODEt Name:

BFNU2M Split Fraction Importance for Group Sorted by Fraction Importance Group Frequency a 5.3621E-O6 07:06:03 09 MAY 1996 Page 8

SF Name...

Fraction...

Fussel-Vesely.

Importance Importance Birnbaum.

Importance achievement.

Worth Reduction...

SF Value..

Morth Frequency.

562

'63.

564.

565.

566.

567.

568.

569.

570.

571.

572.

573.

574.

575.

576.

577.

578.

579.

580.

581

~

582.

583.

5$ 4.

585

'86.

587.

588.

589.

590.

591.

592.

593.

594.

595

'96.

597.

598.

599

~

600.

601.

602.

603.

6o4.

605.

606.

607.

608.

609.

610.

611.

612.

613.

614.

615.

616.

617.

.618.

619

~

620.

621.

622.

623.

624.

625.

626.

627

'28.

629.

630.

631.

632.

633.

634.

635.

636.

637.

638.

639.

640.

641.

642.

RVD21 RVDl7 RVOI RVI I RVD38 RVI 0 SW1C8 SPR2 SPR8 SPR17 SPR15 SWIC2 SWIANN SWIBNN SGTOPS SHT22 SHT27 SHT21 SP3 SP12 S HUT1 2 A3EA1 DV28 DV29 DW1 OV22 DV27 DV18 EC8 EC3 DW2 DWPl EB3 BC9 DN2 DN1 DN3 DL3 DLS DV12 DT2 1 DTlI Dol DO2 DO3 DL2 FWA1 FHB FMC1 FGB FH3 FFB GDB GCB GAB GBB GC10 ECNN EDNN ED35 EPR308 ED11 ED33 FEB FDB FCB EPR68 FAB FBB GEB ABS A83 AC13 A3EO32 AA2 A38027 AD22 ACM3 AC5 ACMI ACM2 O.OOOOE+00 O.OOOOE+00 0.0000B+00 0.0000E+OO 0 ~ OOOOE+00 O.DODOS+00 0.00008+00 O.DODOS+00 0 ~ OOOOE+00 O.OOODE+00 0.0000E+00 O.DOOOE+00 0.0000E+00 O.OOOOE+00 0.0000E+00 0.0000E+00 0.0000E+00 0 ~ DOOOE+00 0 ~ OOOOE+00 O.DOOOE+00 0.00008+00 0 ~ ODOOE+00 0.00008+00 D.OODDE+00 0.0000E+00 0 ~ DODDE+00 0 ~ OOOOE+00 O.DDODE+00 O.ODOOE+00 0 ~ DOOOE+DO 0.00008+00 0 ~ OOOOE+00 0 ~ OOOOEioo D.DDDOE+00 0.0000E+00

, 0 ~ ODOOE+00 0.0000E+00 0 ~ DODOE+00 0.00008+00 O.ODODE+OD 0 ~ OOOOE+00 0.00008+00 0 ~ OOOOE+00 D.DOODE+00 0 ~ ODOOE+00 0 ~ ODODB+00 0 ~ OODOE+00 D.DODOS+Do 0 ~ OOOOE+00

'O.ODDOE+00 0.0000E+00 O.DDDDE+OD 0.00008+00 0.0000E+00 0.00008+00 0.000DE+00 0 ~ OOOOE+00 0 ~ ODDDEioo 0.00008+00 D.OODDE+00 0.0000E+00 0 ~ OOOOE+00 0.0000E+00 D.DODOS+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.000OE+00 0.0000E+00 0.0000Eioo 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.00008+00 O.DOOOE+00 0.0000E+00

-1.0510E 04 1.9654E 06

6. 1532E 06 4.5391E ll 4.41588 0$

-1.11358 06 3.2001E 08 2.1725E 06 8.6879E 06 6.8188E 08 2.4241E 04

-2.4836E 06

-1.9859E 09 8.$ 092E 05 3.9001E 05

-1.0509E 04

-4.9119E 05 2.136DE 04

-3.99588 06 5.10778 06 6.406$ E 06 9.0463E 06 1.0658E 06 5.42228 06 9.20968 06 2.78918 05 2.00478 06

-2.14968 04 2.0525E 05

-9.4983E 05 4,93938 05 1.31818 04 9.17248 07 1.0150E 06

-3.9972E 06 4.0279E 06

-9.5216E 05 1.46908 05 4.1450E 05 7.2639E 06 2.58758-07

-2.4606E 06

2. 4591E-06

-1.21028 05 4.84688 05 2.06558 05 5.0003E-06 2.8383E-09 1.4020E-08 2.96978 05 9.0983E 05 3.5689E-O6

-1.40208 08

-1.08648 06 2 ~ 1844E 07 4.61428 05

-5.11998 06 9 '1668 01

9. 9831E 01 5.34568-01 9.9777E 01 9.99958-01 9.9993E-01 9.99968-01

9. 95668 01 9 ~ 9204E 01

9. 9987E 01 9.7$ 77E 01 9.79798-01 9.9990E-01 2.$ 3318-01

9. 9549E 01 9.92148 01 9.79798-01 2.12038-01 9.9928E 01 9.0907E 01 9.9991E 01

9. 9833E 01 9.99948-01 9.98578-01 9.9817E 01 8.64248-03 9 '795E-01 9.42608-01 9.1034E 01 2.18158 01 9.5547E 01 9.9061E 01 9.9984E-01

9. 9988E 01 8.6424E 03 8.6424E 03 2.1623E 01 9.3583E-01 9.6263B-01 9.9622E-01

9. 9701E-01 9.9985E-01 9.9998E 01 9 '963E 01 9 '980E-01 9 '937E-01 9.9345E 01 9.9995E 01

9. 9990E 01

9. 63118 01 8.8086E 01 9.9991E 01 9 '990E-01 4.56808-01 9.9613E 01 7.69338 01 8.9761E 01 1.0001E+00 1

ODOOE+00 I ~ OOOOE+00 1

OOOOE+DO 1.0000E+00 1.0000E+00 1 ~ 00008+00 1.0000E+00 1 ~ OOOOE+00 1

OOOOE+00 1 ~ 0000E+00 1.00028+00 1.0000E+00 1.00008+00 1.00008+00 1.00008+00 1.00008+00 1.0001E+00 1.0000E+00 1.0001E+00 1.00008+00 1 ~ 0002E+00 1.00008+00 1.00008+00 1.00008400 1.0000E+00 1 ~ 0000E+00 1.00008+00 1.00008+00 1.00008+00 1.00008+00 1.0000E+00 1.0000E+00 1 ~ 0002E+00 1 ~ OOOOB+00

1. 0001B+00 1.0000E+00 1 ~ 0001E+00 1.00008+00 1 ~ 00008+00 1.00008+00 1 ~ OOOOE+00

l. 00018+00 1.00008+00 1.00008+00 1.00008+00 1.00008+00 1.0000E~OO 1.0000E+00 1.0000E+00 1 ~ OOOOE+00 1 ~ 0000E+00 1 ~ OOOOE+00 1.00008+00 1.0000E+00 1.00008+00 1.00008+00 1.00008+00 1.00008+00 1.00008+00 1.00008+00 1.0000E+00 1.00008+00 1.0000E+00 1.0000E+00 1.00008+00 1.0000E+00 1.00008+00 1.00008+00 1 ~ 00008+00 1 ~ OOOOE+00 1 ~ 00008+00 1 ~ OOOOE+00 1.0000E+00 1.0001E+00 1.0000E+00 1 ~ OOOOE+00 1.00008+00

~

1 ~ OOOOE+00 1.0000E+00 1 ~ OOOOE+00 3.6950E 03 1.1640E-O3 1

~ 32208-05 2 '3408-08 8.1640E 04 0.0000Eioo 1.4870E-02 7.47808-04 5.0020E-04 1.0900E 03 5.3230E 04 1.1290E-02 0.0000Ei00 0.00008+00 0.0000E~OO 1.2290E-04 2.0060E-OS 1.22908-04 8.56908 03

1. 31908-02 2.4250E 03

2. 71008-04 0 ~ 00008+00 5.55508 03 5.61708 05 6.6070E 02 5.38208-03 0.0000Ei00 1.6380E 02 3.76708 03 5.00868 03 2.8133E 05 9.78908-04 3.7310E 03 2.2887E-04 1 ~ 2147E-04

1. 1079E-03 1.38408-02 5.85008-03 8.40208 03 4.0320E-06 4.0630E 06 1 ~ 2147E 04 2.2887E-04 1.10798-03 1.91908-03 0.00008+00 0.00008+00 8.6480E-OS 0 ~ OOOOE+00 1.6170E-02 0.0000E+00 0.0000E+00 0.00008+00 0.0000Eioo 0.00008+00 8 '5908 02 0 ~ OOOOE+00 0 ~ OOOOE+00 3 ~ 13608 02 0.0000B+00 1 ~ 9650E-01 3.1640E 02 0.00008+00 0.00008+00 0.00008+00 0.0000E+00 0.00008+00 0.0000E+00 0.00008+00 7.63108 04 5.6460E 05 1.4160E 04 8 '440B 04 7.6310E-04 3.7330E 02 1.4160E 04 2.00008 06 5.64608 05 2.0000E 04 5.00008 05 0.0000E~OO D.OODDEi00 0 ~ OOOOEioo 0.0000E+00 0.0000Eioo 0.0000E+00 0.0000E+00 0.00008+00 0.0000E+00 0.0000E+00 0.0000E+00 0.00008+00 0.00008+00'.0000E+00 0.0000E+00 0.0000E400 0.0000E+00 0.0000E+00 0.0000Eioo 0.00008+00 0.00008+00 0.00008+00 0.00008+00 0.00008+00 0.00008+00 0.0000E+00 0.00008+00 0.00008ioo 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.00008+00 0.00008ioo 0.0000E+00 0.0000E+00 0.00008+00 0.00008+00 0.0000E+00 0.0000E+00 0.00008+00 0.0000E+00 0.00008+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000Eioo 0.0000E+00 0.0000E+00 0.00008+00 0.00008+00 0.0000E~OO 0.0000E+00 0.0000E+00 0.00008+00 0.0000E+00 0.00008+00 0.0000E+00 0 ~ OOOOE+00 0.00008+00 0

~ OOOOE+00 0.0000E+00 0.00008+00 0.0000E+00 0.0000Eioo 0.0000E+00 0.00008+00 0.0000E+00 0.0000E+00 0.00008+00 0.0000E+00 0.00008+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000Eioo 0.00008+00

0

NODEL Name!

BFNU2N Split Fraction Importance for Group Sorted by Fraction Importance

'Group Frequency

> 5.3621E-06 07:06:03 09 NAY 1996 Page 9

ALL SF Name.,

Fraction.

Importance Fussel-Vesely.

Imporrance Birnbaum...

Importance Achievement.

worth Reduction...

SF Value...

Worr.h Frequency.

643.

644.

645.

646.

647.

648.

649.

650.

651.

652

'53.

654.

655.

656.

657.

658.

659.

660.

661.

662.

663.

664.

665.

666.

667.

668.

669.

670

'71.

672.

673.

674.

675.

676.

677.

678.

679.

680.

681.

682.

683.

684.

685.

686.

687.

688.

689

'90.

691.

692.

693.

694.

695.

696.

697

'98.

699.

700.

701.

702.

703.

704.

705.

706.

707.

708.

709.

710.

7'1.

712.

713

~

714.

715.

716.

717.

718

'19.

720.

721.

722.

723.

AD27 A3EB19 A3EB18 A3EB23 A3EB1 A3EB17 A3ED10 A3ED1 A3EC9 A3EB25 A3EC1 A3EC10 DJ3 DG0 DGN DGP DGE DGH DGCS DJ2 DZ3 DH2 DI1 DZ2 AD34 CD2 CAD2 CDA1 AD4 CAD1 DGC DCA2 CST1 CIL1 CIL2 CS6 RP1 OHL2 OHC3 OHS1 OHC1 OHC2 OFTI OPTRZ OLP2 OHS2 OIV1 OLC2 GRF1 NRUB NPIZ1 NRV0 NH23 NIEB OF 1 GREB OEEI OBC1 OBD2 ODSBB NH22 RK2 RF1 RL2 RCW9 RR1 RCW2A Rol RN1 RL4 RLS RNI OSD2 R4801 PCA4 R480B DBWNN OUBNN RCI2 RBZSOB RBCB 0 ~ OOOOE+00 0

~ OOOOE+00 0.0000E+00 0 ~ OOOOE+00 0.0000E+00 0.0000E+00 0.0000E+00 O.OOOOE<<00 0.0000E<<00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0:OOOOE+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0,0000E+00 0.0000E<<00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E<<00 0.0000E<<00 0.0000R+00 0.0000E+00 0.0000E<<00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E<<00 0.0000E+00 0.0000E<<00 O.OOOOE+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0 ~ OOOOE+00 0

~ OOOOE+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 O.OOOOE+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E<<00 0.0000E<<00 0.0000E+00 0.0000E<<00 0.0000E+00 0.0000E+00 0.0000E<<00 0.0000E<<00 0

~ OOOOE<<00 0.0000E<<00 0.0000E<<00 0.0000E+00 0.0000E<<00 0.0000E+00

'0.0000E<<00 0.0000E<<00 0

~ OOOOE+00

-2.3004E 06

-7.3647E 07 9 '363E 07

-2 '603E 05 1 ~ 9830E 04 3 '627E-05

-5 '776E 07

-1.6764E 04

-5 '290E 06

-4'.8778E 06 2 ~ 1368E 04

-5 '732E 05 1 ~ 4497E 06 2.5982E 08 2.4101E 05 4.0980E 05 3.2025E 06 2.4011E 06 3.3805E 06 2 '395E 06 2 '291E 06

-5. 0142E 04 3.3385E 06 2 ~ 1689E 06 8 '580E 07 2 '875E 04

-2 '076E 05 4 ~ 4551E 06 1 ~ 8184E 07 1 ~ 3687E 04 2.9359E 06 2 '529E 06

-1 ~ 1872E 04 1 ~ 5219E 06 2.3221E 04 1.6734E 06

-1.6309E 05

-1.2260B 04

-2.5102E 04

-2.1320E 05 5.4460E 06 3.7927E 05 5 ~ 9521E 06 3 '463B 04 1 ~ 3957E 04 1.2112E 04 3 ~ 1761E 05

-2 '082E-04 5 ~ 0145E 06

-1.1240E-06

-3.8377E-06 2.4176E 05 2.0628E 08 5 '672E 06

-3. 1095E-05 2.2270E 04

6. 1950E-09

-1 ~ 2898E-09 2.3268E 04 1.7561E-08

-2.3636E-04 2.9154E 04 5.2621E-OS 4.3286E 07 2.9454E-04 7.7803E-06

1. 1790E-04 1.1226E 04 3 '960E 05

-5.5886E-OS 9.9995E-01 9.9998E-01 9.9998E 01 9.7317R 01 2.1203E-01 9.5407E 01 9 '998R 01 2 ~ 1203R 01 9 '993E 01 9.9440E 01

2. 1203E 01 9.3712E 01 9.9990E-01 9.9997E-01 9.5621E-01 9.2555R 01 9,9929R-01 9 '947E 01 9.9977R 01 9 '990R-01 9.9943E 01 8 '655E 03 9 '977R-01 9 '998E 01 9 '930E 01 9.1881R-01 9 '796E-01 8 '275E 01 9 '996E-01 9 ~ 9411R 01 8 ~ 7618E 03 2 ~ 2071E 01 7 '793E-01 9 '847E-01 9.5345R 02 9.9963E 01 9 '785E-01 9 '558E-01 7 '366E-01 9 '678E Ol 9 '701E-01 9.8002E 01 8.4018E 01 5.3717E-01 9 ~ 3819E-01 8 ~ 1190E 01 6 '102E-01 6.3999E 02 9 '834E-01 9 ~ 9707B 01 9.9263E 01 9.6955E-01 9 '997E 01 9.9966E-01 9.6943E 01 1.7853E-01 9.9996E 01 9.9995E-01 1.4171E-01 9 ~ 9930E 01 1.2816E-01 1 ~ 5044E 01 9 '831E 01 9 '956E-01 1 ~ 4171E 01 9 ~ 9450E-01 8 '095E-01 9 ~ 9751E-01 9 '968E-01 9 ~ 8784E 01 1.0000E<<00 1.0000R+00 1.0000E+00 1.0000R+00 1.0002E+00 1.0000E+00 1.0000E<<00 1.0002E+00 1.0000E+00 1.0000R+00 1.0002R+00

1. 0001R+00 1.0000R+00 1.0000R+00 1.0000R+00 1.0000R<<00 1.0000R+00 1.0000E+00 1.0000E+00 1.0000R+00 1.0000R+00 1.0000E+00 1 ~ OOOSR+00 1.0000E+00 1.0000R+00 1.0000R+00 1 ~ 0002E+00 1.0000E+00 1.0000E+00 1.00OOR+00 1

~ 0000E+00 1 ~ 0001E+00 1 ~ OOOOE+00 1 ~ OOOOE+00 1 ~ 0001E+00 1.0000E+00 1.0002E+00 1.0000E<<00 1.0000E+00 1 ~ 0001E+00 1 ~ 0003B+00 1 ~ 0000E+00 1.0000E+00 1.0000B+00 1.0000E+00 1.0004E+00 1.0001E+00

1. 0001E+00 1.0000E+00 1.0000E<<00 1.0003E+00 1 ~ 0000E<<00 1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00 1 ~ OOOOE+00 1 ~ OOOOE+00 1 ~ 0000E<<00 1 0002E+00 1.0000E+00 1.0000E+00 1.0002E+00 1.0000E<<00 1.0002E+00 1.0003E+00 1

~ 0001E+00 1 ~ OOOOE+00 1 ~ 0003E<<00 1.0000E+00

1. 0001E+00

1. 0001E+00 1.0000E+00 1.0000E<<00 1.0000E+00 1

~ OOOOE<<00 1 ~ OOOOE<<00

l. 0001E+00 4.4860E-02 3.7330E-02 3.7330E-02 8 ~ 0440E 04

2. 5160E-04 7.7500E 04 2.8530E 02 2.1270E 04 7 ~ S810E 02 8.6970R 04 2.7110B-04 8.6970E-04 1.4780E 02 8.0670E 04 5.5010E 04 5.5010E 04 4 '730E-03 4 '720E-03 0 ~ OOOOE<<00 1 ~ 4710E 02 2 ~ 1660E-02 4 ~ 4120E 03 5 '570E 04 1 ~ 4530E 02 8 '230E 02 1.2559E 03 2 '645E-03 0.0000E+00 6.436OE O4 3 '995B-05 4 '990E-03 2.2722E-02 2.9618E 06 3 '609E-06 5 '952E 04 9 '380E 04 2 '662E-04 4.4930E-03 7 '590E 04 8 '290E 03 1 ~ 0610E-03 9.1750E-04 1 ~ 8170E 03 1

~ 8950E 03 3 '240E-OS 7.8720E 04 2 '530E 03 6 '350E-04 9 '560E 05 0 ~ 0000E<<00 2.6790E 04 O.OOOOE+00 3

~ 0130E 03 0 ~ OOOOE+00 3 ~ 8410E-04 0 ~ OOOOE+00 5 ~ 2010E 04 7.9338E 04 7.9588E-04 0.0000E+00 1.5050E-02

1. 0160E-03 2.7103E 04 1.5230E 04 2.5658E-OS 2.7103E 04 2.5213E 05 2.7103E 04 3 '3OSE 04 1.0170E 03 9.7800E 04 3.4305E-04 1.4130E 03 1.0800E 03 4.3080E 02 0.0000E<<00 0.0000E<<00 0.0000E+00 1.0700E 01 0.0000E<<00 4.5736E 03 0.0000E<<00

'0.0000E<<00 0.0000E<<00 0.0000E<<00 0.0000E<<00 0.0000'0 0.0000E<<00 0

~ OOOOE<<00 0.0000'0 0.0000E<<00 0.0000E+00 0.0000E<<00 0 ~ OOOOE<<00 0 ~ OOOOE<<00 0.0000E+00 0.0000E<<00 0.0000E<<00 0.0000E<<00 O.OOOOE<<00 0

~ OOOOE<<00 0 ~ OOOOE+00 0 ~ OOOOE<<00 0.0000E+00 0 ~ OOOOE+00 0.0000E<<00 0.0000E<<00 0 ~ OOOOE<<00 0 ~ OOOOE<<00 0.0000E<<00 0.0000E+00 0.0000E<<00 0.0000E<<00 0.0000E<<00 0.0000E<<00 0.0000E<<00 0.0000E<<00 0.0000E<<00 0.0000E<<00 0.0000E<<00 0.0000E+00 0.0000E<<00

0. OOOOE<< 00 O.OOOOE<<00 0.0000E<<00 0.0000E<<00 O.OOOOE+OO 0.0000E+00 0.0000E<<00 0.0000E<<00 0.0000E<<00 0.0000E<<00 0.0000E<<00 0.0000E<<00 0.0000E<<00 0.0000E<<00 0.0000E<<00 0.0000E<<00 0.0000E<<00 0.0000E<<00 0.0000E+CO 0.0000E<<00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E<<00 0.0000E+00 0.0000E+00 0.0000E<<00 0.0000E<<00 0.0000B+00 0.0000E+00 0.0000E<<00 0.0000E<<00 0.0000E<<00 0.0000E+00 O.OOOOE<<00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E<<00 0.0000E+00

APPENDIX D.

-M MATRIX Table D-1 presents the $-M matrix for the Browns Ferry Unit 2 PSA.

ETVA'%0047.DOC.04/0686 PLG

MODRI, Name:

BFNU2M Split Fraction Importance for Group Sorted by Fraction Importance Group Frequency

~ 5.3621E-06 0'1:06:03 09 MAY 1996 Page 10 ALL SF Name....

Fraction...

Fussel-Vesely.

Birnbaum...

Achievement.

Reduction...

Importance Importance Importance worrh worth SF Value...

Frequency.

724.

725.

'726.

727.

728m 129.

730.

731.

732.

733

'34, 735.

736.

737.

738.

739.

740.

741, 742.

743

~

744.

745.

746.

747, 748.

749.

750.

151.

752.

153.

754.

755.

756.

757.

758.

759.

760.

761.

162.

763.

764.

765.

766.

767.

768.

769.

710.

711.

772.

713.

RBCI RECK RBCL GFB HXD5 HXD4 HXDS HXB2 HXC3 HUM3 INES INDS HXD9 INAS ZNBS INFS HPL2 GHB HPL6 GGB GH6 HUM2 HUM1 HSO HR60 HRC6 HRLO NBOCB LFS LECS LM1 LSH3 LSTRl LSH2 NAO MSVC1 LPRESS LV3 LVP1 INGS ZVC3 IVC2 ZV01 ZNHS ISD1 KHS KFS KCS JAS JC2 0

~ OOOOE<<00 O.OOOOE+00 0.000OE+00 O.OOOOE+00 0.0000E<<00 O.OOOOE+00 0.000OE+00 0.0000E+00 O.OOOOE<<00 0.0000E+00 0.000OE<<00 O.OOOOE+00 0.0000E+00 O.OOOOE<<00 0.000OE<<00 O.OOOOE+00 0.0000E<<00 0.00008+00 0.0000E+00 0.0000E+00 O.OOOOE<<00 0.0000E+00 O.OOOOE+00 O.OOOOE+00 0.0000E+00 0.0000E<<00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E<<00 0.0000E<<00 0.0000E+00 0.0000E<<00 O.OOOOE<<00 O.OOOOE<<00 0.0000E<<00 0.0000E+00 0.0000E+00 0

~ OOOOE+00 0.000OE+00 0.0000E+00 0.000OE+00 0.0000K<<00 0.0000E+00 0.0000E+00 0.0000E<<00 0.0000E+00 0.0000E+00 O.OOOOE<<00 0.0000E+00 2.5674E 05 2 '288E 05

-5.5967E 05 5 '133E-05 1 ~ 0614E 07

'1.6835E-04

-5.054SE 05

-7. 1407E 05

-4 '424E-OS

-1.8679E 05 2.8385E 05 5 ~ 2102E-06 2 ~ 3145E-05 4 '071R-08

-5.2142E-04 1 ~ 3590E 06

-4.6797E 05

-1.8722E 06 3.9305E 05 1.5084E 06 4.4068E 07

1. 2351E-05 2.8248E 05

-6.6980E-OS

2. 9514E-07 3.4521E 15 5 '955E 08 5,3954E 07 9 '973E-01 9.9442E 01 9.9592E 01 9.9979E 01 1.0000E<<00 9.6872E-01 9.9763E-01

9. 8106E 01 9.0356E 01 9.9939E-01 9.9968E-01 9.9995E 01 9.9985E-01 9.9988E 01 2.1910E-01 9.9983E 01 8.6424E 03 9.9989E-01 9.9428E-01 9.998'1E-01 9.9428E-01 9.9707E-01 8.6424E 03 9.9868E 01 9.9462E 01 4.7100E 01

9. 9973E 01 9.9801E-01 1.0000E<<00 1.00008<<00

1. 00018+00 1.0000E+00

1. 0001E+00 1.0000K+00 1.0002E<<00 1.0001E+00 1. 0001E+00 1.0000E<<00 1.0000E+00 1.0000E<<00 1.0000E<<00 1.0000E+00 1.00008<<00 1.0000E<<00 1.0000R+00 1.0000R+00 1.00008+00 1.0000E+00 1.00008+00 1.0000K+00 1.0005R+00 1 ~ 0000R+00 1.0000K+00 1.0000K+00 1.0000R+00 1.0000E+00 1.0000E+00 1.0000R+00 1.0000E+00 1.0000E<<00 1.0000R+00 1.0000R+00 1.000OR<<00 1.0000R+00 1.0000R<<00 1.0000R+00 1.0000R+00 1.00008<<00 1.0000E<<00 1.0000E+00 1 ~ 0000E<<00 1.0000E+00 1.0000E+00 1.0000E<<00 1.0000E<<00 1.0000E<<00 1.0000E<<00 1.0000E+00 8.6537E-02 4.8676E-O3 1.3528K 02 0.0000E<<00 1.9470K-01 2.0870E 02 5.3530E-03 2.0870E 02 5.4880E 03 4.8115E-04 0.0000E<<00 0.0000E+00 2.9850E 02 0.0000E+00 0.0000E<<00 0

OOOOE+00 8.2230E 02 0.0000E+00 8 ~ 8030R 02 0.0000R+00 1.3390E-01 4.1140E 04 7.2277R 04 0.0000E+00 0.0000E<<00 8.1246E 03 0.0000E+00 0.0000$ <<00 0.0000E+00 0.0000E<<00 4.7203E-OS 1.6761R 02 6.8250E 03 1.1431E 02 0.0000E+00 7.7040E-OS 0.0000E+00'.2033E 03 2.8493E-OS 0.0000R+00 5.0853E-OS 5.4966E 05 6.525'rE 15 0.0000E+00 2.2218R 04 0.0000E+00 0.0000E+00

, 0.0000E+00 0.0000E+00 2.7120E 04 0 ~ OOOOE+00 O.OOOOE+00 0.00008+00 0.0000E<<00 0.0000E+00 0.0000E+00 0.0000E+Oo 0.0000E<<00 O.OOOOE<<00 0.0000E+00 0.0000E<<00 0.0000E+00 0.0000E<<00 O.OOOOE<<00 0.0000E<<00 0.0000E+00 O.OOOOE<<00 0.0000E<<00 0.0000E+00 0.00008+00 O.OOOOE+00 0.0000E<<00 0.0000R+00 0.0000E+00 0.0000E<<00 0.0000E+00 0.0000E+00 O.OOOOE<<00 0.0000E+00 0.0000E<<00 0.0000R<<00 O.OOOOR<<00 0 ~ OOOOE+00 0.0000E+00 0.0000E+00 0.0000E<<00 0.0000E+00 0.0000E<<00 0 ~ OOOOE+00 0.0000E<<00 0.0000E<<00 0.0000R+00 0.0000E<<00 0.0000E+00 0.0000E+00 0.0000R+00 0.0000R<<00 0.0000E<<00 0.0000E<<00 0.0000E+00

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4. MODIFICATIONSMADE TO PREVIOUS PRA MODELS The modifications made to the PSA models are presented in this section.

Changes made to

'he initiating event analysis (incorporating new initiating events or refining the frequency of selected initiators) are presented in Section 4.1.

Changes made to systems analyses or the event models are presented in Section 4.2.

The assessment of riew operator actions is summarized in Section 4.3.

4.1 INITIATINGEVENTS 4.1.1 REFINEMENT OF MODEL FOR FLOODS IN THE TURBINE BUILDING In the previous PRA models, a single initiator was used to represent all potential flooding events in the turbine building. In the current model, two initiators are developed to represent the spectrum of potential flooding events, resulting in a more realistic representation.

The turbine building fiood initiating event frequency used in the IPE, Rev.

1 I.O. ¹2 PRA, and Multi-UnitPRA was developed from industry flooding experience.

The associated flooding events database (Reference 5) covers a total of 740 years of reactor power operation, which is approximately 1,081 calendar ye'ars.

The flooding events were screened to include only large flooding incidents in the turbine building. Of the 28 flooding events in the

database, 11 events were found to be applicable to the original analyses.

In the current evaluation of risk for the plant configuration in which Units 2 and 3 are returned to service and Unit 1 is in extended layup, the 11 applicable turbine building flooding events were reexamined together with the BFN turbine building layout in order to determine the more realistic flooding scenario(s) that can occur in the turbine building. The following items summarize the findings of the reexamination of the BFN turbine building layout and the applicable flooding events:

The raw cooling water (RCW) pumps for Units 1 and 2 are installed in one room and the Unit 3 RCW pumps are installed in a separate room about 50 ft away.

These rooms are isolated from the general condenser area by a solid wall to the south and walls with doors to the east and west.

The walls are about 8-ft high.

The RCW pumps are mounted approximately 18 (bottom) to 48 (top) inches above the floor.

~ 'he compressors for, the plant control air system are located at Elevation 565'.

Equipment associated with the feedwater and condensate systems are located on the basement floor of the turbine building at Elevation 557'.

The general floor area in the turbine building for the condenser areas at Elevation 557're estimated as approximately 40,000 ft for the Units 1 and 2 areas and 28,000 ft for the Unit 3 area, or about 68,000 ft total floor area.

No significant holdup that would contain a flood to one condenser area or another was identified. At 7.8 gallons per cubic foot of water and assuming an available volume of 50% (i.e., equipment and pLG

foundations occupy half the volumetric space) in the condenser areas of the turbine building, an estimated 265,000 gallons of water are required to cover the area up to 12 inches deep.

Ifit is assumed that the RCW pumps are not impacted by a flood in the general area of the turbine building until the water level in the area is at least 18 inches high and there is in-leakage into the RCW pump room through the normally closed doors, it would require a flood involving at least 400,000 gallons of water to fail the RCW pumps.

Most of the applicable turbine flooding events do not involve a flood of this magnitude (400,000 gallons) or have the potential to cause a flood of this magnitude.

Based on the above findings, two turbine building flood initiating events were defined and analyzed.

The first initiating event FLTB involved a very large flood that is severe enough to fail the feedwater system, condensate system, RCW system, and plant control air system.

The second turbine building flood initiating event FLTB2 is less severe and fails only the feedwater and condensate systems.

Table 4-1 shows the 11 flooding events applicable to the BFN turbine building flooding analysis.

The events were rescreened for the calculation of the frequencies for the two initiating events defined for this study. A two-stage Bayesian method was used to construct the prior distribution for the two turbine flooding frequencies and then updated with plant-specific experience of zero events in 1.69 years of operation.

The updated mean turbine building flood frequency for initiating event FLTB is 1.10E-03 per year, and 7.20E-03 per year for initiating event FLTB2. These initiating event frequencies are for a single unit.

The BFN turbine building is common to all three units, and, therefore, events at one unit during shutdown or at power could impact the other unit. For this study, Unit 1 is in extended layup and the Unit 1 systems that are potential flood sources in the turbine building, such as the circulating water system, are idle. Only the operating equipment and systems associated with Units 2 and 3 could cause a flooding event in the turbine building. The frequency of the initiating event is, therefore, estimated as two times the frequency for a single unit; that is, 2.20E-03 per year for FLTB, and 1.44E-02 per year for FLTB2.

4.1.2 LOSS OF OFFSITE PO%ER Loss of offsite power as an initiator i's represented by two distinct initiators: total loss of offsite power, meaning loss of all of the 500-kV and 161-kV supplies; and loss of only the 500-kV supply.

In turn, two classes of loss of 500-kV power were identified:

loss of 500-kV to a single unit (LSOOU2) and loss of 500-kV to the plant (LSOOPA).

The frequency for the loss of all offsite power remains at 3.39E-02 per year.

The frequencies for the initiators L500U2 and LSOOPA are 4.47E-02 and 3.59E-02 per year, respectively.

The conditional likelihood of losing the grid following a multiple unit initiator was taken from the Multi-UnitPRA.

4.1.3 LOSS OF REACTOR BUILDINGCLOSED COOLING WATER SYSTEM The frequency for the loss of the reactor building closed cooling water was included in the updated systems analysis that reflects the plant configuration being modeled.

That analysis concluded the frequency of this initiator is 8.87E-02 per year.

The plant response logic model for the loss of the reactor building closed cooling water system developed in the Multi-Unit PRA is applicable and was adopted.'.1.4 LOSS OF PLANT AIR A reexamination of the frequency for the Loss of Plant Air initiating event resulted in a value of 5.30E-02 per year.

The reexamination of this'requency assumed an 80% availability factor.

As part of the reexamination of the initiating event frequency, a review of a recent plant modification was made.

That modification involves the ability to isolate the air header on a unit ifa header break were to occur so that the other unit would be unaffected.

The evidence that was used to determine the initiating event frequency was taken from industry experience.

That experience indicates that the dominate causes of system failure are failures of compressor or dryer units.

While the plant modification does result in a lower incidence of loss of plant air, the reduction is not quantitatively significant. This finding is supported by the plant air systems analysis.

4.1.5 FLOODS IN THE INTAKEPUMPING STATION A review of the analysis of the frequency of floods in the intake pumping station for the plant configuration of interest resulted in the determination that the frequency used in the previous PRAs is applicable.

4.2 SYSTEMS ANALYSES AND EVENT MODEL 4.2.1 MODIFICATIONSIN MODELING OF BATTERYBOARD AVAILABILITY The model was changed to reflect the transfer of loads when a battery board is removed for maintenance.

In addition, the model was changed to restrict maintenance to a single battery board as reflected by actual plant practices; the earlier models contained terms that corresponded to simultaneous maintenance on battery boards 2 and 3 that did not correspond to actual plant practices.

The availability of battery boards 1, 2, and 3 is represented in the event model by Top Events DE, DH, and DG, respectively, found in the electric power support event trees (ELECT12 and ELECT3).

To ensure a contribution from simultaneous maintenance of battery boards 2 and 3 to the unavailability of both the battery boards does not occur, an intermediate top event fault tree model representing of the two battery boards was constructed using the existing individual battery board fault tree models.

Only top event alignments for the removal of one of the battery boards for maintenance were defined.

This top event model, therefore, determines the

e unavailability of the two battery boards due to hardware failure of both battery boards; hardware failure of battery board 2 and maintenance of battery board 3; and hardware failure of battery board 3 and maintenance of battery board 2.

In addition, the intermediate top event also calculates the unavailability of an individual battery board due to all causes.

The conditional split fractions for Top Events DH and DG are defined in terms of the unavailabilities or split fractions for battery boards 2 and 3 evaluated from the intermediate top,event model.

These split fractions are used in the plant model quantification for event sequences in which battery board 1 (Top Event DE) is unavailable.

To model the shifting of the loads from battery board 2 or 3 to battery board 1 when the battery board 2 or 3 is taken out of service for maintenance purpose, a new set of intermediate and conditional split fractions for Top Events DH and DG were defined.

The new split fractions or unavailabilities do not contain any contributions from maintenance activities for battery boards 2 and 3.

Only contributions from hardware failures are included in these new split fractions.

The split fractions are used in the plant model quantification for event sequences in which battery board 1 is available.

This implies that when battery board 1

is available, battery boards 2 and 3 can only be unavailable due to hardware failures.

Maintenance of battery board 2 or 3 does not contribute to the unavailability of Top Event DH or DG for event sequences in which battery board 1 (Top Event DE) is available due to the shifting of the loads from the battery board 2 or 3 to battery board 1 ~ However, for event sequences in which battery board 1 is not available, then maintenance contribution to the unavailability of battery boards 2 and/or 3 will be included.

4.2.2 CHANGES IN THE iVlODELFOR RAW COOLING WATER The success criteria for RCW has been changed to reflect that two pumps are sufficient to support one unit and that any four pumps are sufficient to support Units 2 and 3.

'I A new split fraction, R3CW1, was developed using the RCW pumps from all three units.

The top event name used in the System Analysis Module of RISKMAN for the three unit RCW model is R3CW.

The success criteria used for Top Event R3CW is that 4 of 10 pumps are. required to operate for 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

(As discussed below, one of the seven Unit I/Unit 2 RCW pumps and one of the five Unit 3 RCW pumps are assumed to be in standby and used for maintenance replacement of normally running pumps.)

The actual system model requires that at least two of the four Unit 3 pumps modeled and at least two of the six Units 1 and 2 pumps are available.

The combinations of failures in the fault tree are limited to failure of all four Unit 3 pumps with coincident failure of three Units 1 and 2 pumps or failure of all six Units 1 and 2 pumps combined with failure of any one Unit 3 pump.

The combinations of global common cause failure of one group of pumps with coincident failure of pumps in the other group dominate the contribution from pump failures.

Even so, the overall contribution of pump failures to split fraction R3CW1 is relatively small.

The six Units 1 and 2 pumps are grouped into one common cause group and the four Unit 3 pumps are grouped into another common cause group.

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The R3CW model assumes that the flow paths for Units 2 and 3 are both required to be available for the mission time. This assumption leads to several single order cutsets for manual valves transferring closed.

These cutsets are the major contributors to failure of split fraction R3CW1.

Pumps 1D and 3E were assumed to be spares used only for maintenance alignments and do not appear in the three unit fault tree for RCW. Therefore, no maintenance alignments were modeled for the RCW pumps, only for the strainers.

The'other 10 pumps from the 3 units are included in the fault tree used to develop split fraction R3CW1.

Split fraction R3CWl is only used when the support for all of the 10 pumps modeled in the fault tree is available.

Four RCW pumps are required to support both Units 2 and 3. A modeling assumption is made in order to avoid an unnecessarily complex model.

The four required pumps can be all from Units 1 and 2, all from Unit 3, or from a combination of both sets.

The model, however, only takes credit for Unit 3 pumps ifthree of the six running Unit 1/Unit 2 pumps fail. This assumption greatly simplifies the RCW model and is shown (by the low RCW importance) to not affect the quantitative results.

4.2.3 CONSIDERATION OF THE DIESEL-DRIVENFIRE PUMP TO PROVIDE VESSEL LEVEL CONTROL Currently, the diesel-driven fire pump is not credited for providing sufficient makeup to the vessel.

4.2.4 CONTROL ROD DRIVE HYDRAULICSYSTEM In the current model, CRD pump 18, nominally shared between Units 1 and 2, is assumed to be permanently assigned to support Unit 2.

CRD pump 18 would, therefore, be available to replace pump 2A when the latter is in maintenance, and is potentially available to work with pump 2A to provide enhanced CRD flow per EOI Appendix 5B. Also, an additional split fraction was developed to represent the local recovery of enhanced flow from the CRD hydraulic system following failure of unit preferred power and loss of plant air.

In a related activity, a review of the model developed for the CRD pump unavailability revealed that the generic maintenance distributions used in the analysis were overly conservative when compared to actual maintenance unavailabilities experienced for pumps'1B and 2A since the restart of Unit 2. More appropriate generic distributions were adopted resulting in a more realistic CRD model.

4.2.5 ROLE OF RBCCW PUMP AND HEAT EXCHANGER 1C RBCCW pump and heat exchanger 1C can be utilized by either Unit 2 or 3.

The model has been updated to reflect the shared nature of these components and-to take credit for them during pump or heat exchanger maintenance.

PLG

e 4.2.6 USE OF UNIT 3 DIESEL GENERATORS TO SUPPORT UNIT 2 Credit is taken for the Unit 3 diesel generator 3ED to support Unit 2 only in selected scenarios.

Specifically, the possibility of utilizing diesel generator 3ED to support Unit 2 is considered ifat least two other Unit 3 diesel generators are available to support Unit 3.

4.2.7 LONG-TERM OPERATION OF HPCI OR RCIC Ifhigh pressure coolant injection (HPCI) or reactor core isolation cooling (RCIC) are taking suction from the suppression pool, then suppression pool cooling is required to ensure their long-term operation.

The event model structure developed for the IPE included logic representing actions to ensure long-term operation of HPCI or RCIC given suppression pool cooling failure.

The specific actions involve transferring the suction of these pumps back to the condensate storage tank (CST) (or ensuring that RCIC remains aligned from the CST) and providing makeup to the CST.

The associated hardware and operator actions are represented in the low pressure general transient event tree (LPGTET) as Top Events HR and OHR, respectively.

In previous models, no credit was taken for these actions; in the current model, the possibility of recovery is considered for non-ATWS cases in which either HPCI or RCIC hardware availability has been ensured for 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

4.2.8 USE OF UNIT 1 DIVISIONIIRHR PUMPS TO SUPPORT UNIT 2 AND USE OF UNIT 3 DIVISIONI PUMPS TO SUPPORT UNIT 2 The current model includes consideration of the Unit 1 division II RHR pumps as being dedicated to support Unit 2. This feature is represented in the low pressure general transient event tree (LPGTET) as Top Event Ul.

For selected scenarios (specifically, for events involving only Unit 2), Unit 3 division I pumps can support Unit 2.

Likewise, division II pumps from Unit 2 can support Unit 3 in selected scenarios.

4.2.9 TRANSFER OF POWER AT THE 480V SHUTDOWN BOARDS 2A AND 2B; 250V RMOV BOARDS 2A AND 2B Transfer of power for selected boards is represented by Top Event R480 in the low pressure general transient event tree (LPGTET). The modeling of this top event refines the approach taken earlier.

4.2.10 RHRSW AND EECW REQUIREMENTS FOR TWO-UNITOPERATION The current model requires one RHRSW pump per unit for successful heat removal.

For two-unit events, two RHRSW or swing pumps not in the same room can be used to support both units.

For ATWS conditions, four RHRSW pumps (and four RHR pumps/heat exchangers) are required.

Two EECW pumps are required with the restriction that both cannot be in the same room.

Details are provided in Table 3-4.

PLG

4.2.11 RECOVERY OF BOP EQUIPMENT FOLLOWING SELECTED INITIATING'VENTS For selected scenarios that initially involve isolation of the reactor vessel, the possibility is considered that the main condenser can be recovered.

This recovery is reflected in the event model via split fractions developed for Top Event HS in the low pressure general transient event tree (LPGTET).

The information used to develop a basis for the recovery models came from two sources.

The first source was a review of pre-1985 operating experience at BFN. The plant response as reported in the operator's logs following selected initiators was reviewed to determine whether an attempt to restart the plant occurred within approximately 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months of the original initiator.

The choice of 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months is consistent with the 6-hour mission time for the initial phase of HPCI/RCIC operation. Ifrestart is not successful, the additional 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months of HPCI/RCIC operation would support cooldown activities.

Such actions were interpreted as evidence that the balance-of-plant (BOP) equipment had been recovered.

Data of this form were available for MSIV Closure, Loss of Condenser Vacuum, Turbine Trip without Bypass, Loss of Feedwater, and Loss of Plant Air initiators.

Events from the operating log that resulted in an unrelated shutdown were excluded from consideration.

A second source of data was required to support the recovery of BOP following loss of offsite I

power.

This information was adopted from the Peach Bottom analysis of NUREG/CR-4550 (Reference 6).

For loss of offsite power scenarios, recovery is considered ifscram was successful, HPCI or RCIC was determined to be available, and ifpower was restored within 30 minutes.

For the transient initiators Loss of Condenser Vacuum, Partial Loss of Condensate, Loss of.

Condensate, Partial Loss of Feedwater, Loss of Feedwater, MSIV Closure, Loss of Plant Air, Pressure Regulator Failure, and Turbine Trip without Bypass, the possibility of recovery is considered given successful scram and the availability of HPCI or RCIC.

In summary, the likelihood of successful recovery of BOP under the conditions described above was determined to be characterized by the following mean values:

Initiator Mean Value MSIV Closure Loss of Condenser Vacuum Turbine Trip without Bypass Loss of Feedwater 0.943 0.915 0.858 0.700 Loss of Plant Air Loss of Offsite Power 0.874 0.910

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Additional details on these likelihoods are reported in Table A-2 of Appendix A.

4.2.12 LOCAL OPERATION OF THE HARDENED WETWELLVENT For selected scenarios, which include station blackout conditions, local operation of the wetwell vent is considered.

4.2.13 OPERATION OF 2-INCH PRIMARY CONTAINMENTVENT LINES IN ACCORDANCE WITH EMERGENCY OPERATING INSTRUCTIONS The valves in question were previously included in the event tree Top Event CIS (found in the containment interface event tree CNTMT). In previous models, these vent lines were assumed to initially be open and were required to close on receipt of an isolation signal.

The current model augments this requirement by recognizing that, per procedure, the isolation

~

signals might be bypassed, and therefore the valves will require manual action to close.

4.2.14 OTHER MODEL MODIFICATIONS Other modifications made to the models include the consideration of recovery of support for diesel generator C given failure of diesel generators A, B, and D, and the addition of two top events that designate whether a core damage event has occurred on the adjacent unit and whether Unit 3 is at power, respectively.

The diesel generator auxiliary board, required for local ventilation/cooling of the diesel generator rooms, can be powered from diesel generator A, B, or D. Without the consideration of recovery, diesel generator C would have to be assumed to fail ifdiesel generators A, B, and D were determined to be unavailable, The potential for recovery is rather modest due to the common cause model lir&ngthe four diesel generators; however, recovery is possible by local actions to provide power to the necessary auxiliary board.

The possibility for recovery was added to the event model by the addition of a new top event (ODSB) in the electric power support event tree (ELECT12).

A similar depende'ncy exists for diesel generator 3ED on diesel generators 3EA, 3EB, and 3EC.

Recovery of diesel generator 3ED has not yet been considered.

(Recovery of diesel generator 3ED is considered in the Unit 3 PSA).

Two new top events were added to the signal event tree (SIGL). The first top event (ACM) represents the likelihood that a core damage event is occurring on the adjacent unit; a similar top event was used in the Multi-UnitPRA. This top event acts as a flag that signals when access to the reactor building is not possible.

The second top event (U3AP) determines the status (at power/shutdown) of Unit 3 and is used to flag different sets of conditional availability of Unit 3 equipment to support Unit 2.

Other modeling changes were incorporated to enhance the efficiency of the quantification process.

These changes included the elimination of the three top events (MT1, MT2, and MT3) in the ELECT12 tree that represented the three main transformers, respectively.

These top events were replaced by macros, thereby decreasing the quantification time with no signific'ant impact on the fidelity of the model.

Likewise, in the SIGL tree, the four ECCS vessel level top events (LT1, LT2, LT3, and LT4) were eliminated by incorporating their underlying logic into the existing Top Event LV. In addition, the four PCIS vessel level top events (LM1, LM2, LM3, and LM4) were combined into a single new Top Event LM.

The rules for the selection of Top Event NCD in the CNTMT event tree reflect the logic that specifies whether core damage is averted in a particular sequence.

For this model, the rules for NCD that evolved through the previous PRAs were reviewed and simplified.

4.3 OPERATOR ACTIONS The actions described below were incorporated into the plant model to address various issues.

They have either been quantified utilizing input from operators in the past or are sufficiently similar to other actions in terms of influences on performance-shaping factors to justify assignment of a surrogate distribution for this quantification.

This section discusses the context in which each action was evaluated and presents the resultant human error rates.

~

Operator Action HOCIS2 Close Containment Vent System Valves, Given Radiation Indications Exceed Allowable Limits. Action HOCIS2 has been established in recognition that when a transient occurs, the operators are'directed by EOI-2 PC/P-1 to monitor and control pressure below 2.4 psig using the vent system.

The vent is established by manipulating keylock switch 2-HS-84-20(19), which overrides the Group 6 isolation signal.

Therefore, ifEOI PC/P-1 is being executed when core damage occurs, the vent path must be manually closed to avoid a bypass of containment, resulting in failure of Top Event CIS, "Containment Penetration 3 Inches or Less in Diameter."

Action HOCIS2 involves the termination of an active process directed by the emergency operating instructions (EOI) when the conditions that permit the process are violated.

Operator Action HOCRD3 Establish CRD Enhanced Flow Injection to RPV Locally, Given Loss of VPS or Loss of Plant Air. Action HOCRD3 has been established to take credit for the fact that operators can manually align CRD to provide enhanced flow injection to the RPV ifthe capability to accomplish this action from the control room is lost due to loss unit preferred 120V AC. The split fraction CRDS has been added to Top Event CRD in the low pressure general transient event tree (LPGTET) to represent the early establishment of enhanced CRD flow given failure of UPS.

t The local manual steps required to align and adjust 2-FCV-85-11A(B) using 2-PCV-85-11 are clearly delineated in 2-OI-85, Section 8.24.3.

Moreover, the operator has easy access to the controls and, in the absence of a LOCA or ATWS, ample time to perform the actions due to the inventory of water available in the RPV to remove decay heat.

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The same action was determined to be applicable to Loss of Plant Air scenarios.

Operator Action HOHR1 Transfer HPCI/RCIC Suction to CST and Maintain CST Level Given Suppression Pool Cooling Lost. Action HOHR1 has been established to take credit for the capability of the operating crew to switch HPCI RCIC

/

suction back to the CST when the suppression pool water temperature becomes hot enough to potentially damage the HPCI/RCIC pumps.

This will occur when suppression pool cooling has been lost and remains unavailable despite the best efforts of the plant staff to restore it.

To be successful, the action includes the requirement that the operators provide makeup to the CST to maintain a sufficient inventory of water for the HPCI/RCIC t'o As there are multiple water storage tanks onsite and adequate resources to

'l ble if accomplish these actions, it is assumed that alternate sources of water are avai a e i the operator action is successful.

Operator Action HOLP3 Open the Hardened Wetwell Vent, Given AC Power is Not Available. Action HOLP3 evaluates the human actions required to locally open the hardened wetwell vent.

This action involves only those actions needed to actuate the valves locally, and adequate guidance for accomplishing the action is contained in EOI Appendix 13.

The action was evaluated by operators for various transient conditions during the preparation of the Rev.

1 I.O. ¹2 PRA.

Operator Action HOXDCrosstie De-Energized 4-kV Shutdown Board to Energized 4-kV Shutdown Board.

Action HOXD is used to recover power for the diesel generator auxiliary board supplying HVAC support for diesel generator C in the event that diesel generators A, B, and D are unavailable.

The 4-kV shutdow'n board C does not directly feed an diesel generator auxiliary board, so this manual action is necessary to provide the necessary crosstie.

Top Event ODSB has been established to incorporate this action into the plant model.

Discussion with operations personnel indicates that, ifdiesel generator C is the only Units 1 and 2 diesel generator available, the operator would most likely reenergize the auxiliary diesel generator board using a Unit 3 diesel generator or another Units 1

and 2 4-kV shutdown board by using 4-kV shutdown bus 1 or 2 as a crosstie.

Procedural guidance for this is provided in 0-AOI-57-1A (Loss of Offsite Power),

Attachments 1 and 8. A note in Attachment 8 specifies that, during accident conditions, diesel generator C is limited to supplying 4-kV shutdown "board D (not A or B).

Action HOXD was evaluated for the case in which the time constraints for crosstieing the 4-kV shutdown boards is not time sensitive.

When applied to the restoration of a failed diesel generator auxiliary board, the action becomes more time sensitive.

However, as discussed below, plant procedures key the operators to recognize the situation early, thus providing adequate time for the operators to accomplish the action.

Pi. Cr

In the event that only diesel generator C starts and operates, it is highly likely that the operators will identify that room HVAC is not available and will act to restore the auxiliary diesel generator board before the diesel generator is overheated by high room temperature.

First, Procedure 0-AOI-57-1A provides guidance for verifying that the appropriate support buses are energized within the first eight instructions, and states that steps may be performed out of order, depending on plant conditions.

The necessary realignment can be done from Panel 9-23 in the control room.

With only one diesel generator to provide all essential AC power, operators state that they will give high priority to verifying that it is functioning properly.

Second, the diesel generator procedure (0-01-82) states, "WHEN conditions allow, THEN MONITOR and RECORD diesel generator operating parameters using illustration 2." Illustration 2 requires that operating parameters be checked every 15 minutes during the first hour of operation.

Finally, height of the ceilings in the diesel generator rooms are on the order of 20 ft, so it is highly unlikely that the diesel. generator that has just started up can heat a room enough to fail the diesel generator in 15 minutes.

This is supported by operator experience working in a diesel ge'nerator room with an operating diesel generator and a failed HVAC fan.

Over the course of 15 minutes the room heated noticeably, but only to the degree of becoming uncomfortable for the operators, not inhabitable.

Therefore, an operator checking the diesel generator would be keyed restoring HVAC and the operator team willhave sufficient resources and time to accomplish the necessary actions to restore it.

~TVA44004'/.DOC,04/0686 4-11 PLCi

Table 4-1 (Page 1 of 2).

Screening of Turbine Building Flooding Events Event Plant System/Component Plant Status Size Included in Initiating Event FLT82 Applicable to Initiating Event FLTB Comment Quad Cities 2 Duane Arnold Feedwater - Feedwater Flow Regulating Valve Condensate - Backwash Valve Would Not Close At Power At Power 70,000 Gallons l23,000 Gallons Yes Yes No No Insufficien flood water and inventory to impact RCW.

Insufficient flood water and inventory to impact RCW.

4 Quad Cities Monticello Circulating Water-Water Box Expansion Joint Circulating Water-Cooling Tower Expansion Joint Failed Before Commercial Operations Shutdown 15 Feet of Water Flooded Discharge Structure Yes No Yes No Has potential to cause severe flooding.

Event will not cause a flood in the BFN turbine building and impact RCW.

22 Crystal River 3 Circulating Water-Secondary Services Heat Exchanger Block Valve At Power Medium-65,000 gpm Yes No Insufficient flood water to impact RCW.

23 Three Mile Island I Circulating Water-Pump Casing Refueling Large-Pumphouse Flooded No No Event will not cause a flood in the BFN turbine building and impact RCW.

53 Browns Ferry I 57 Trojan Condensate - Blank Flange Loosened Feedwater - Heater Drain Pump Discharge Line Rupture Before Commercial Operations During Trip Large (85,000 Gallons)

Large Yes Yes No No Insufficient flood water and inventory to impact RCW.

Insufficient inventory to impact RCW.

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ML18038B928

Contents

Text

SUMMARY

2.1 BACKGROUND

2.2 DESCRIPTION

2.3 CONCLUSION

3.1 DESCRIPTION

Navigation menu

ML18038B928

Text

SUMMARY

2.1 BACKGROUND

2.2 DESCRIPTION

2.3 CONCLUSION

3.1 DESCRIPTION

Navigation menu

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