NUREG/CR-5378

EGG-2567

Aging Data Analysis

and Risk Assessment

Development and

Demonstration Study

Prepared by

A. J. Wolford, C. L. Atwood, W. S. Roesener

Idaho National Engineering Laboratory

EG&G Idaho, Inc.

Prepared for

U.S. Nuclear Regulatory Commission
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I~
NUREG/CR-5378

EGG-2567

GF, R9, RM

Aging Data Analysis

and Risk AssessmentDevelopment and

Demonstration Study

Manuscript Completed: July 1992

Date Published: August 1992

Prepared by

A. J. Wolford*, C. L. Atwood, W. S. Roesener

G. H. Weidenhamer, NRC Technical Monitor

Idaho National Engineering Laboratory

Managed by the U.S. Department of Energy

EG&G Idaho, Inc.

Idaho Falls, ID 83415

Prepared for

Division of Engineering

Office of Nuclear Regulatory Research

U.S. Nuclear Regulatory Commission

Washington, DC 20555

NRC FIN A6389

IDNV Technica

355 East Campus View Blvd.

Suite 710

Columbus, OH 43235
ABSTRACT

This work develops and demonstrates a probabilistic risk assessment (PRA)

approach to assess the effect of aging and degradation of active components on

plant risk. The work (a) develops a way to identify and quantify age-dependent failure rates of active components, and to incorporate them into PRA; (b) demonstrates these tools by applying them to a fluid-mechanical system, using the key elements of a NUREG-1150 PRA; and (c) presents them in a step-by-step approach, to be used for evaluating risk significance of aging phenomena in systems of interest.

Statistical tests are used for detecting increasing failure rates and for testing datapooling assumptions and model adequacy. The component failure rates are assumed

to change over time, with several forms used to model the age dependence- exponential, Weibull, and linear. Confidence intervals for the age-dependent failure

rates are found and used to develop inputs to a PRA model in order to determine the

plant core damage frequency. This approach was used with plant-specific data,

obtained as maintenance work requests, for the auxiliary feedwater system of an

older pressurized water reactor. It can be used for extrapolating present trends into

the near future, and for supporting risk-based aging management decisions.

FIN A6389-Aging-Components and Systems IV

iii iii ~~~~NUREG/CR-5378
CONTENTS

ABSTRACT..................................................................... iii

EXECUTIVE SUMMARY . ......................................................... xiii

ACKNOWLEDGMENTS . ......................................................... xvii

1. INTRODUCTION ............. ...... 1-1

1.1 Purpose and Scope .1-1

1.2 Background .1-1

1.2.1 History .1-1

1.2.2 Motivation .1-1

1.3 Report Organization .. 1-2

2. PROJECT APPROACH ....................................................... 2-1

2.1 The Definition of Aging ....................... .......................... 2-1

2.2 Objectives for the Present Work ..................... ....................... 2-1

2.3 Assumptions ................................. 2-2

2.3.1 Assumptions Regarding the Data Employed in the Study ..... ........... 2-2

2.3.2 Assumptions Regarding the Analysis and Use of the Data ..... .......... 2-2

2.4 Limitations ............................................................ 2-3

2.5 Practical Inference: Is There Aging? ........................................ 2-4

2.5.1 General Approach ............ .................................. 2-4

2.5.2 Specific Application ........... .................................. 2-5

2.6 Step-by-Step Approach for Aging Risk Analysis ........... .. ................. 2-6

2.6.1 Step 1. Develop Time Histories of Components ....................... 2-6

2.6.2 Step 2. Define Relevant Component Failure Modes ..... ................ 2-8

2.6.3 Step 3. Define Failure Criteria ..................................... 2-8

2.6.4 Step 4. Apply the Failure Criteria to the Time Histories ..... ............ 2-8

2.6.5 Step 5. Construct Failure Timelines and Cumulative Failure Plots .... ..... 2-8

2.6.6 Step 6. Perform Statistical Analysis ................................. 2-8

2.6.7 Step 7. CalculateA(t) ............................................. 2-10

2.6.8 Step 8. Quantify the Age-Dependent Risk ............................ 2-10

3. PWR AUXILIARY FEEDWATER SYSTEM REVIEW .............................. 3-1

3.1 Design Function . ....................................................... 3-1

v NUREG/CR-5378
3.2 Flowpath .............................................................. 3-1

3.3 Support Systems . ...................................................... 3-3

3.4 Automatic Actuation and System Response .................................. 3-3

4. COMPONENT FAILURE DATA ....................... .......................... 4-1

4.1 Component History . .................................................... 4-1

4.2 Definition of Relevant Component Failure Modes ............................. 4-3

4.3 Definition of Failure Criteria ............ .................................. 4-3

4.4 Application of Failure Criteria to the Data ................................... 4-5

4.4.1 Broadly Defined Failure Data ...................................... 4-5

4.4.2 Narrowly Defined Failure Data ..................................... 4-11

4.5 Failure Timelines and Cumulative Failure Curves ........... .. ................. 4-15

5. STATISTICAL METHODS FOR ANALYZING TIME-DEPENDENT FAILURES .5-1

5.1 Aging Models .. 5-1

5.2 Assumptions Regarding Failure Data .. 5-2

5.3 Inference Methods .. 5-3

5.3.1 Inference for P .................................................. 5-5

5.3.2 Investigating the Assumed Model Form .5-8

5.3.3 Inference for As, Given P ......................................... 5-10

5.3.4 Joint Inference for Both Parameters and for the Failure Rate .5-11

5.3.5 Joint Asymptotic Normality .5-11

6. TIME-DEPENDENT FAILURE DATA ANALYSIS ............. .. .................. 6-1

6.1 Preparation of the Input . .................................................. 6-1

6.2 Statistical Screening Analysis ............ ................................. 6-1

6.2.1 Common P Test for All Components ................................ 6-1

6.2.2 Aging Test . .................................................... 6-9

6.2.3 Adequacy Check of the Assumed Form of the Aging Model ..... ......... 6-9

6.2.4 Common A, Test for All Components Exhibiting Aging ..... ............ 6-16

6.2.5 MLE for ( .,A .)........................................ 6-16

6.2.6 Check of the Normal Approximation for Distribution of MLE .... ........ 6-16

6.3 Calculation of A(t) as a Function of Time ......... ........................... 6-18

6.4 Case Study Problem Specifications ........... .............................. 6-18

4UREG/CR-5378 vi
7. QUANTIFICATION OF TIME-DEPENDENT RISK ............. .. ................. 7-1

7.1 Time-Dependent Risk Analysis for AFW System ............................... 7-1

7.1.1 Use of Maximum Likelihood Results to Define Bayesian Distributions ..... 7-1

7.1.2 Resulting Time-Dependent Component Failure Rate Inputs ..... ......... 7-1

7.1.3 PRA Adjustment to Allow Time-Dependent Risk Quantification .... ...... 7-3

7.1.4 Results . ....................................................... 7-3

7.1.5 Simultaneous Aging ............................................. 7-5

7.2 Potential Applications ............... .................................... 7-8

7.2.1 Extrapolation to Distant Future ..................................... 7-8

7.2.2 Periodic Risk-Based Management .................................. 7-8

8. CONCLUSIONS............................................................. 8-1

9. REFERENCES .. 9-1

Appendix A-Estimating Hazard Functions for Repairable Components .................. ... A-1

Appendix B-Tables of Maintenance Records .......................................... B-1

vii NUREG/CR-5378
2-1.

2-2.

3-1.

4-1.

4-2.

4-3.

4-4.

4-5.

4-6.

4-7.

4-8.

4-9.

4-10.

LIST OF FIGURES

Hypothetical 90% confidence intervals for P .....................................

An aging risk quantification approach ..........................................

Schematic diagram of the PWR auxiliary feedwater system .........................

Process used to develop component failure data ..................................

Failure timelines to determine the occurrence times of steam binding of the AFW

system pumps .............................................................

Failure to run timeline for steam- and motor-driven pumps ..........................

Cumulative failure plot for steam-driven pumps, broadly defined failures to run .........

Cumulative failure plot for steam-driven pumps, narrowly defined failures to run.

Cumulative failure plot for motor-driven pumps, broadly defined failures to run ........

Failure to start timeline for steam- and motor-driven pumps .........................

Cumulative failure plot for motor-driven pumps, broadly defined failures to start.

Cumulative failure plot for motor-driven pumps, narrowly defined failures to start.

Plugging failure timeline for 3-in. MOVs (feed header isolation valves) ...............

2-5

2-7

3-1

4-2

4-12

4-16

4-16

4-17

4-17

4-18

4-18

4-19

4-19

4-11. Cumulative failure plot for 3-in. MOVs (feed header isolation valves),

broadly defined plugging failures ..................................

4-12. Cumulative failure plot for 3-in. MOVs (feed header isolation valves),

narrowly defined plugging failures ................................

4-13. Failure to stay closed timeline for 6-in. MOVs (cross-connect valves) .....

4-14. Cumulative failure plot for 6-in. MOVs (cross-connect valves), broadly

defined failures to stay closed ....................................

4-15. Cumulative failure plot for 6-in. MOVs (cross-connect valves), narrowly

defined failures to stay closed ....................................

4-16. Backflow failure timeline for pump discharge check valves .............

4-17. Cumulative failure plot for pump discharge check valves, broadly defined

backflow leakage failures ........................................

4-18. Steam binding failure timeline for the steam- and motor-driven pumps ....

4-19. Cumulative failure plot for the steam- and motor-driven pumps, broadly

and narrowly defined steam binding failures .........................

4-20 

4-20 

4-21 

4-21 

4-22 

4-22 

4-23 

4-23 

4-24 

NUREG/CR-5378 viii v
5-1. Approach for statistical analysis of one data set .......... ........................ 5-4

5-2. Component comparisons for ................................................. 5-6

5-3. Component comparisons for A, based on hypothetical data ........ ................. 5-6

5-4. Q-Q plot ........................................... 5-9

5-5. Q-Q plot, based on hypothetical data .......................................... 5-9

5-6. Component comparisons for A ............................................ 5-11

5-7. 90% confidence region for (flAo,), based on conditional likelihood .5-12

5-8. 90% confidence ellipse for (fl, A,), based on joint asymptotic normality,

overlaid on the region of Figure 5-7 .5-13

5-9. 90% confidence regions for (fi,2,) based on Weibull failure rate model with t,

at the middle of observation periods .5-13

5-10. 90% confidence regions for (flA,,), based on linear failure rate model with time

measured from the component's installation .5-15

5-11. 90% confidence regions for (,B,,), based on linear failure rate model with time

measured from the middle of observation periods .5-15

5-12. MLE and 90% confidence band for A(t), based on joint asymptotic normality

for all three models .5-16

5-13. MLEs and 90% confidence bands for A(t), based on conservative calculations

and on asymptotic normality for exponential model .5-16

5-14. MLEs and 90% confidence bands for A(t), based on conservative calculations

and on asymptotic normality for Weibull model .5-17

5-15. MLEs and 90% confidence bands for A(t), based on conservative calculations

and on asymptotic normality for linear model .5-17

6-1. Process used to develop time-dependent failure rates ........ ...................... 6-2

6-2. Q-Q plot for pump discharge check valves, broadly defined back leakage failures,

exponential model, based on failures before the data were reinterpreted ..... ........... 6-10

6-3. Q-Q plot for pump discharge check valves, broadly defined back leakage failures,

Weibull model, based on failures before the data were reinterpreted ...... ............. 6-10

6-4. Q-Q plot for pump discharge check valves, broadly defined back leakage failures,

linear model, based on failures before the data were reinterpreted ...... .............. 6-11

6-5. Q-Q plot for 3-in. MOVs (header isolation valves), broadly defined

plugging failures, exponential model . .......................................... 6-11

IX NUREG/CR-5378
6-6. Q-Q plot for 3-in. MOVs (header isolation valves), broadly defined

plugging failures, Weibull model .......................... 6-12

6-7. Q-Q plot for 3-in. MOVs (header isolation valves), broadly defined

plugging failures, linear model .......................... 6-12

6-8. Q-Q plot for 3-in. MOVs (header isolation valves), narrowly defined

plugging failures, exponential model .......................... 6-13

6-9. Q-Q plot for 3-in. MIOVs (header isolation valves), narrowly defined

plugging failures, Weibull model .......................... 6-13

6-10. Q-Q plot for 3-in. MOVs (header isolation valves), narrowly defined

plugging failures, linear model .......................... 6-14

6-11. Q-Q plot for either broadly or narrowly defined pump steam binding failures,

exponential model .......................... 6-14

6-12. Q-Q plot for either broadly or narrowly defined pump steam binding failures,

Weibull model . 6-15

6-13. Q-Q plot for either broadly or narrowly defined pump steam binding failures,

linear model . 6-15

6-14. 90% confidence regions for (j3,A,) for pump discharge check valves,

broadly defined back leakage failures, exponential model, based on failures

before the data were reinterpreted .6-19

6-15. 90% confidence regions for (#,A,) for pump discharge check valves,

broadly defined back leakage failures, Weibull model, based on failures

before the data were reinterpreted . 6-19

6-16. 90% confidence regions for (fl,A,) for 3-in. MOVs (header isolation valves),

narrowly defined plugging failures, exponential model . 6-20

6-17. 90% confidence regions for (fl,A,) for 3-in. MOVs (header isolation valves),

narrowly defined plugging failures, Weibull model . 6-20

6-18. 90% confidence regions for (P,B,) for 3-in. MOVs (header isolation valves),

narrowly defined plugging failures, linear model, time measured from

component's installation . 6-21

6-19. 90% confidence regions for (P, A,) for 3-in. MOVs (header isolation valves),

narrowly defined plugging failures, linear model, time measured from

middle of observation periods . 6-21

6-20. 90% confidence regions for (/La,) for pump steam binding, broadly or

narrowly defined failures, exponential model . 6-22

6-21. 90% confidence regions for (PA,) for pump steam binding, broadly or

narrowly defined failures, Weibull model . 6-22

NUREG/CR-5378 x
7-1. Calculated mean CDF and 90% interval after the data were reevaluated ............... 7-5

7-2. Calculated mean CDF and 90% interval before the data were reevaluated ........... 7-7

LIST OF TABLES

ES-I. Example decision matrix .........................-.--------------- !-'-'-----xv

3-1. PWR AFW system component status and support system dependency summary ..... .... 3-2

4-1. Distribution of raw maintenance events for the AFW system according

to component type .......................................................... 4-3

4-2. AFW system component failure modes, descriptions, and relevant component

numbers, corresponding to Figure 3-1 ............ .............................. 4-4

4-3. Distribution of broadly defined failure occurrences according to component type .... .... 4:6

4-4. Distribution of broadly defined failure occurrences according to failure mode ..... ...... 4-6

4-5. Sample of maintenance records for the AFW system steam-driven pumps .............. 4-7

4-6. Sample of maintenance records broadly classified as failures for the AFW system

steam-driven pumps ..................................................... '.4-8

4-7. Sample of maintenance records broadly classified as failures for the AFW system

steamrdriven pumps, rewritten format .................. ........................ 4-9

4-8. Sample of maintenance records narrowly classified as failures for the AFW system

steam-driven pumps, rewritten format ................................. .... 4-13

4-9. Distribution of narrowly defined failure occurrences according to component type ....... 4-14

4-10. Distribution of narrowly defined failure occurrences according to failure mode .... ..... 4-14

6-1. Formatted data used for the analysis of broadly defined failures .6-3

6-2. Formatted data used for the analysis of narrowly defined failures .6-5

6-3. Results of statistical analysis of the broadly defined failures .6-7

6-4. Results of statistical analysis of the narrowly defined failures ............ ........... 6-8

6-5. MLEs for fi and A, by aging model and failure definition ......... ................. 6-17

6-6. MLEs of A(t) and associated confidence intervals by failure mode definition for the

exponential model ........................................... 6-23

6-7. MLEs of A(t) and associated confidence intervals by failure mode definition for the

Weibull model ................................. 6-24

xi NUREG/CR-5378
6-8. MLEs of A(t) by failure mode definition for the linear model ....... ................. 6-25

6-9. Failure sets analyzed as a function of failure definition and significance Ievel .6-26

7-1. Mean values of A(t) and associated error factor by failure definition and failure model .... 7-2

7-2. Mean values of CDF and associated uncertainties quantified after reinterpretation

of raw data ................ 7-4

7-3. Mean values of CDF and associated uncertainties quantified before reinterpretation

of raw data......... o ........... 7-6

8-1. Example decision matrix ......... ............. 8-2

NUREG/CR-5378 xxii
EXECUTIVE SUMMARY

The present work develops and demonstrates a

, probabilistic risk assessment (PRA) approach to.

assess the effect of aging and degradation of active

8 components on plant risk. The work supports the

Nuclear Plant Aging Research Program sponsored

by the U.S. Nuclear Regulatory Commission

(USNRC). The work consists of three tasks:

* Develop a way to identify and quantify agedependent failure rates of active components, and to incorporate them into PRA. -

* Demonstrate this approach by applying it,

with plant-specific data, to a fluid-mechanical system, using the key elements of a

NUREG-1150a PRA.

* Present it as a step-by-step approach, so that

others can use it for evaluating risk significance of aging phenomena in systems of

interest.

The approach was applied to analyze maintenance data from the auxiliary feedwater (AFW)

,system of an older pressurized water reactor

(PWR). Only the AFW system was assumed to be

aging. The age-dependent failure rates were then

input to the plant's NUREG- 1150 PRA at various

assumed plant ages to show the effect of aging on

core damage frequency.

A number of assumptions were made to accomplish this work. For the data, it was assumed that

the component maintenance records obtained for

use in this study were complete and the "return-toservice-date" for corrective maintenance performed on components determined to have failed

was an acceptable surrogate for the date of failure.

For the data analysis and system modeling it was

assumed that the failures of a component follow a

nonhomogeneous (time-dependent) Poisson process, with time-dependent failure rate A(t). The

Poisson assumption implies that failures are

a. USNRC, Severe Accident Risk Assessment for

Five U.S. Nuclear Power Plants, NUREG-1150,

Draft 2, 1989.

independent. The general form assumed for A(t)

involved a parameter fi that governs the rate of

aging by means of a function h and a constant

multiplier A,, all related by

A(t) = A.h(t;pi)

The three specific models considered in this

report are

A(t) = Roe A

At) = Ao(tlt°)fl

(exponential failure rate)

(Weibull failure rate)

A(t) = 2o(l + fit) (linear failure rate).

For the Weibull model, to is an arbitrary

normalizing time. Each assumed model was routinely checked in the data analyses with the

following results. There was some clustering of

the failure times; during an intermediate analysis,

but not after the final analysis, there was enough

clustering in one data set to cast strong doubt on

the Poisson assumption. The choice of an exponential, Weibull, or linear form for A(t) never had

much effect on the fit of the model to the data.

It was further assumed that replaced components in the data record could be considered as

good as new, while repaired components could be

considered as good as old; and that the components in place at the start of the data period were

installed when the plant began commercial operation, approximately four years before the start of

the data period. For risk modeling, it was assumed

that an increasing failure rate reflected aging, and

so could be extrapolated into the near future; and

the published NUREG-1150 PRA was complete

as modeled and could adequately model all systems other than the AFW system, with only minor

modifications needed for the AFW system to

account for aging.

The approach used statistical tests to detect

increasing failure rates and to test data-pooling

assumptions and model adequacy. Point estimates

and confidence intervals were found for the

model parameters fl and A, These were

.x.i. xiii ~~~NUREG/CR-5378
translated into estimates for the age-dependent

failure rates. In any short time period, such as one

year, each failure rate A, was treated as a constant

and used to develop inputs to a PRA model, yielding the plant core damage frequency (CDF).

Based on the statistical data analyses, only

selected components were modeled as aging in

the PRA. To identify these components, two criteria were used. Components were modeled as

aging if a test showed statistically significant

aging (a) at the 5% significance level (strong evidence of aging) or (b) at the 40% significance

level (very weak evidence of aging). Both significance levels were used because there is no sharp

dividing line between aging and non-aging.

To help account for the subjectivity in interpreting the maintenance records, two definitions of

failure were used. A broadly defined failure was

one where the maintenance record might possibly

have described a safety-related failure, whereas a

narrowly defined failure was one where the maintenance record certainly described a failure. The

narrowly defined failures were a subset of the

broadly defined failures. The exact criteria for

each definition are clearly stated in this work to

allow for repeatability of the analysis.

The final result of applying the above approach

was that two components showed some evidence

of increasing failure rate. Extrapolation of these

failure rates into the near future resulted in negligible changes in CDF from those calculated in the

NUREG-l150 PRA.

Two conclusions of importance are as follows:

* A step-by-step approach was developed and

demonstrated that provides a workable way

to estimate present and near-term future risk

based on the modeling assumptions.

* Three aging models were considered: the

exponential, Weibull, and linear failure rate

models. With the data used, they produced

very similar results for the data observation

period and for extrapolations into the near

future. However, the exponential model

clearly behaved best for quantifying uncertainties, and the linear model clearly behaved

worst, being in some ways unusable.

Several, difficulties were noted in applying the

approach. First, data from 10 years of AFW system operation at two units provided too little in--;

formation to precisely estimate the degree of

aging for many failure modes, although this data

set was comparatively large for such a plant-specific sample of failure events., Second, classification of failure data from old records was difficult,

and necessitated the use of broad and narrow definitions of failure. Third, failures tended to cluster

in time: Finally, the maintenance and operational

environment may have changed at times in the

plant's history. Some of these difficulties could be

addressed by discussions with people directly

familiar with the plant equipment, practices, and

history.

We also make the following observations

concerning the possible application of the

methodology:

* Extrapolation of observed trends to the

distant future would require more explicit

incorporation of maintenance and replacement policies. They are treated implicitly

here, as part of the environment for the

observed past failure events. Therefore, the

approach of this report should not be used for

distant extrapolation.

* Periodic use of the approach at a plant is

suggested to help prioritize surveillance,

maintenance, and engineering analysis

efforts according to risk.

For managers who must make decisions based

on three models, two definitions of failure, and

two significance levels, we, the authors of this

report, offer the following suggestions. Use the

exponential failure model. When aging of a component results in a significant increase in CDF,

use a table similar to the following example.

NUREG/CR-5378 xiv
Table ES-1. Example decision matrix.

Broadly defined failures Narrowly defined failures

No-aging assumption Awareness. Inform operations and Strong interest. Inform operations

rejected at significance maintenance staffs of potential and maintenance staffs of potenlevel of 0.40 problem. Reanalyze if failures persist. tial problem. Reanalyze after

short period of time.

No-aging assumption Strong interest. Investigate immediately Very strong interest. Investigate

rejected at significance to determine which maintenance immediately and determine what

level of 0.05 records describe actual failures of mitigating action should be taken.

concern.

xv NUREG/CR-5378
ACKNOWLEDGMENTS

The authors of this report acknowledge Jitendra P. Vora, USNRC Nuclear Plant

Aging Research (NPAR) Program Coordinator, and Gerald H. Weidenhamer,

USNRC NPAR Project Manager, for their management of this work.

Special thanks go to Robert C. Bertucio of NUS Corporation for clarifying

questions about the PRA quickly and thoroughly, and to the director of Nuclear

Operations and Maintenance Support at the power station for providing additional

information about some of the events reported in the maintenance records. Thanks

are also due to William E. Vesely, SAIC, for oral comments and for initially identifying Laplace's test, which is a rudiment of the work presented in this report.

Thanks also go to John Boccio of Brookhaven National Laboratory for sharing the

raw maintenance data that were collected as a part of the USNRC's Performance

Indicator Program.

Thanks are due to many additional colleagues at the INEL: Lee C. Cadwallader,

Dennis A. Conley, Babette M. Meale, Ollie B. Meeky, and R. Niall M. Hunt for

assisting with data processing and interpretation; Tammy Swantz and Carol L.

Olaveson for updating the PRA models used in the IRRAS program; Geraldine S.

Reilly for preparing many of the technical illustrations; H. Lowell Magleby for

advice and review; and Julie M. Steffes and Karen MacDonald for guiding the

report through the many steps of publication.

Written comments on Revision 1 of the draft report were received from Dale

Rasmuson and Les Lancaster of the USNRC, from Elizabeth Kelly and Richard

Beckman of Los Alamos National Laboratory, and from the Director of Nuclear

Operations and Maintenance Support at the power station. Written comments on

Revision 2 were received from William E. Vesely of SAIC. We carefully considered each comment and made use of nearly all of them, either by incorporating the

suggestions into the present version of the report or by clarifying the earlier text.

We are grateful for all the comments.

xvii NUREG/CR-5378
Aging Data Analysis and Risk

Assessment-Development and

Demonstration Study

1. INTRODUCTION

1.1 Purpose and Scope

The present work was planned to develop and

demonstrate a probabilistic risk assessment

(PRA) approach to assess the effect of aging and

degradation of active components on plant risk.

This goal consisted of three tasks:

* Develop a way to identify and quantify agedependent failure rates of active components, and to incorporate them into PRA.

* L Demonstrate this approach by applying it,

with plant-specific data, to a fluid-mechanical system, using the key elements of a

NUREG-1 150 PRA (USNRC 1989).

* Present it as a step-by-step approach, so that

others can use it to evaluate the risk significance of aging phenomena in systems of

interest.

This study was restricted to active components.

Parallel work on passive components is described

by Phillips et al. (1990).

1.2 Background

1.2.1 History. The oldest licensed commercial

nuclear power station has been operating for about

30 years. As a part of its responsibilities to protect

the health and safety of the public, the United

States Nuclear Regulatory Commission (USNRC)

is concerned about the aging of major components, structures, and safety systems in nuclear

power plants. Therefore, the USNRC has initiated

the Nuclear Plant Aging Research (NPAR) Program (USNRC 1987) to develop technical bases

for the systematic assessment of the effects of

aging on plant safety and public risk.

Many hardware- and material-oriented research

programs have been implemented in the NPAR

program to gain an understanding of aging and

degradation phenomena in safety-significant

nuclear power plant equipment. This understanding will contribute to the identification and

resolution of aging-related technical issues, and to

recommendations on how to identify, detect, and

control (manage) the effects of equipment aging.

Aging management must use appropriate tools

and techniques to ensure that components and

systems are identified according to their risk significance, and that they are maintained at an

acceptable level of reliability over the operating

life of the plant.

One specific task of the NPAR program, Risk

Evaluation of Aging Phenomena, was chartered to

develop and extend PRA techniques to evaluate

the impacts of equipment aging and degradation

on overall plant risk indices, such as safety system

unavailability and core damage frequency (CDF).

The present work was performed as part of this

task.

1.2.2 Motivation. Risk assessment is a key

element of the NPAR program. Aging risk assessment is envisioned for the following purposes:

* Identify risk-significant components and

systems in which aging is a concern

* Provide assurance that ongoing aging management programs maintain an acceptable

level of plant safety

* Provide input to set schedules for activities

that control the effects of aging, such as

testing, surveillance, and replacement

1-1 NUREG/CR-5378
* Examine the risk significance of plantspecific design features/modifications and

select effective ways to reduce plant risk

* Prioritize resources for hardware-oriented

aging research (Levy et al. 1988)

* Perform value-impact regulatory analysis.

A close look at current state-of-the-art PRA

technology reveals that incorporation of timedependence requires (a) development of a way to

treat time-dependence in PRA inputs, (b) examination of the standard PRA approaches for

implicit non-aging assumptions, and (c) documentation of PRA approaches for aging. The goal

of the Risk Evaluation of Aging Phenomena task

is to develop ways to incorporate the effects of

aging into PRA, thereby supporting the development of regulatory criteria and strategies and

addressing the technical issues related to plant

aging.

1.3 Report Organization

Section I states the purpose and scope of this

report. It also gives a brief background and

motivation for this study.

Section 2 gives the overall approach taken in

this report. It presents definitions, specific objectives, assumptions, and limitations. It explains

points to consider when facing the question "Is

there aging?" Finally, it gives a summary of the

step-by-step approach developed in this work.

Section 3 describes the pressurized water reactor (PWR) auxiliary feedwater (AFW) system

used in demonstrating the approach.

Section 4 describes how the data from the AFW

system were interpreted for the demonstration.1-

Section 5 presents a conceptual view of the statistical elements of the data analysis, with the

technical details relegated to Appendix A.

Section 6, presents the application of this analysis approach to the AFW data. The result is a set

of estimated age-dependent failure rates for certain components in the AFW system.

Section 7 uses these age-dependent failure

rates to modify the NUREG-1 150 PRA and then

to calculate risk as a function of time.

Section 8 summarizes the main results of the

report.

Section 9 lists the references cited.

Finally, Appendix A contains technical details

of the statistical methods, and Appendix B

contains tables of the AFW maintenance records.

NUREG/CR-5378 1-2
2. PROJECT APPROACH

2.1 The Definition of Aging

The NPAR definition of aging used in this work

is "...the cumulative degradation which occurs

with the passage of time in a component, system,

or structure [that] can, if unmitigated, lead to loss

of function and an impairment of safety."

(USNRC 1987) It is important to consider the

details of this definition to understand, in context,

the assumptions made in the development and

application of the aging assessment approach.

First, consider the meaning of "passage of

time." Often this is interpreted as simply a calendar process. However, the amount of degradation

that occurs within a given period of time depends

on the degrading conditions present. The degrading conditions are created by the operational

environment, which includes the effects of

operational procedures, policies, and maintenance. Changes in the operational patterns affect

the degrading environment. In this report we

assumed that degrading conditions remained constant, so that calendar time could be used as a

surrogate for time at degrading conditions.

Next, consider "cumulative degradation." In

some cases degradation occurs so slowly under

the degrading conditions present that it can not be

observed. Practically speaking, the aging is negligible. If the effects of degradation can be

observed, an equation describing the amount of

degradation as a function of time is necessary in

order to quantify and predict the aging.

Next, consider "mitigation." The amount of

degradation and the rate at which degradation

accumulates can be changed (mitigated) through

the performance of maintenance activities. If a

maintenance activity results in complete renewal/

replacement of all the degraded parts of a component, then that component may be considered as

good as new, that is, unaged. If the maintenance

activity results in the renewal/replacement of only

a subset of the degraded parts, the component may

be considered better than old but not as good as

new; that is, the functional form of further

degradation may well be different from that occurring before the maintenance because of the complicated interaction of new and degraded parts. If

the maintenance activity results in the return of the

component to a condition nearly equivalent to that

before the maintenance was performed (for example, the repair/replacement of a single part) then

the component may be considered as good as old.

Finally, the component may be better than new if

a part or parts were replaced with better than original equipment, or worse than old as a result of

faulty parts or improper performance of the maintenance. The quantitative modeling of this report

assumes that replacement makes a component as

good as new, while repair makes it as good as old.

Mitigating surveillance and maintenance programs are considered as part of the normal conditions at the plant and are not modeled explicitly.

Finally, consider degradation that can "lead to a

loss of function and an impairment of safety." The

important detail to understand here is that not all

degradation that results from the passage of time

contributes to the failure of a safety-specific

function. For example, the leakage of water from

a secondary system valve may well be inconvenient, but may not affect the functional safety

of the valve. On the other hand, the leakage of

primary coolant from a reactor coolant system

valve does represent safety-related functional

degradation, which needs to be quantified to

describe aging. For this report, maintenance

records were screened and only safety-related

events were used.

2.2 Objectives for the Present

Work

In order to meet the purposes listed in

Section 1. 1, the objectives of the present work are

to develop and document an understandable

step-by-step approach for accomplishing the

following analysis:

Identify statistically significant and nonsignificant increasing failure rates for

components in the AFW system of an older

2-1 NUREG/CR-5378
Project Approach

PWR nuclear power station using available

plant-specific component history information (standard plant maintenance records)

and simple trend tests.

* Quantify the failure rate for those components found to exhibit statistically significant

trends.

* Incorporate the failure estimates and

uncertainties into an appropriate PRA model

and compute the implied age-dependent

plant risk index (CDF), uncertainty, and

important contributors (sequences, component faults). A NUREG- 1150 PRA was used

for this computation.

2.3 Assumptions

This section lists the assumptions used to make

inferences for this work and distinguishes these

nonstandard assumptions from the normal tenets

of nuclear plant PRA. Not one of these assumptions is believed to be perfectly true. They all

simplify reality somewhat in order to build a mathematical model of the plant and thereby allow the

risk to be quantified. With a more intimate

knowledge of the plant history or with more

detailed repair records, it might be possible to

modify some of the assumptions. When refining

the assumptions, however, one must take care not

to build a model with so many parameters that they

cannot be estimated well with the available data.

The assumptions are listed here to make

explicit the scope of applicability of the approach.

If in a different setting some of the assumptions

are known to be far from correct, then the

approach given in this report must be modified or

applied separately to distinct portions of the data

for which the assumptions are approximately

true.

2.3.1 Assumptions Regarding the Data

Employed in the Study. Section 4 provides a

detailed description of the steps involved in

developing component history data. The following is a concise list of the assumptions that directly

involve the data.

1. The component maintenance records

obtained for use in this study were complete

in the sense that all corrective repairs and

replacements were included (for the time

spanned by the records).

2. The "return-to-service-date" for corrective

maintenance performed on components

determined to have failed was an acceptable

surrogate for the date of failure.

3. Unit-specific data for two sister units

reflected similar operating environments

and maintenance and, therefore, could be

pooled to increase the sample size. This

assumption was always tested formally and

always appeared acceptable.

These assumptions are also commonly made

for an ordinary PRA. The only difference is that

the failure date in Assumption 2 is not needed

when estimating a constant failure rate.

2.3.2 Assumptions Regarding the Analysis and Use of the Data. Details of the statistical methods employed are described in Section 5

and Appendix A. Assumptions regarding data

analysis and system modeling are as follows:

1. The failures of a component follow a nonhomogeneous (time-dependent) Poisson

process, with time-dependent failure rate,

A(t). The Poisson assumption implies that

failures are independent. The general form

assumed for A(t) involves a parameter fi that

governs the rate of aging by means of a function h and a constant multiplier A, all related

by

A(t) =

The three specific models considered in this

report are

A (t) = Ae#

A t) = ).0(t/t0 )#

(exponential failure

rate)

(Weibull failure rate)

A(t) = AJ(l + flt) (linear failure

rate)

NUREG/CR-5378 2-2
Project Approach

For the Weibull model, t, is an arbitrary

normalizing time.

2. The components' environments (ambient

conditions, maintenance and operation

practices, and any degrading conditions)

were constant throughout the data period.

As a consequence it follows that

* Increasing failure rate reflects aging,

and therefore the increase can be

extrapolated into the near future. Simple extrapolation into the far future is

unjustified because it is likely that

badly aged components will be

discovered and replaced eventually.

* Calendar time is an acceptable surrogate for the time at degrading

conditions.

3. Replaced components were considered as

good as new, while repaired components

were considered as good as old.

4. The components in place at the start of the

data period were installed when the plant

began commercial operation. This means

that no components were replaced during

the first 4.5 (approximately) years; note that

in 10 years of data records, very few

components were replaced.

5. The published NUREG-1150 PRA was

complete as modeled and could adequately

model all systems other than the AFW

system. Minor modifications to the AFW

system fault trees are specifically identified

in Section 7.1.3.

Assumptions 1 through 4 go beyond those of an

ordinary PRA, as follows. Assumption 1: Normally, the failures are assumed to follow a Poisson

process with a constant failure rate. Assumption 2:

The assumption of a constant environment is

implicit in the assumption of a constant failure

rate. Assumption 3: The concepts good-as-new

and good-as-old are irrelevant when the failure

rate is constant. Assumption 4: The age of a

component at the start of the data period is irrelevant when the failure rate is assumed not to depend

on the component's age.

A non-constant environment may affect the

calculated failure rate. For example, if maintenance practices are evolving and improving, the

calculated failure rate will gradually decrease. If

the environment fluctuates, but has no long-term

trend, then failures may be more frequent when

the operating environment is less than optimal.

However, no long-term upward or downward

trend will result in the calculated failure rate.

Assumption I was routinely checked in the data

analyses. There was some clustering of the failure

times. During an intermediate analysis, but not

after final analysis, there was enough clustering in

one data set to cast strong doubt on the Poisson

assumption. The choice of an exponential,

Weibull, or linear form for A(t) had little effect on

the fit of the model to the data. The good-as-new

portion of Assumption 3 was checked through a

test for equality of the A,, values. We did not have

a technique for checking the good-as-old portion

of Assumption 3, and we did not have enough

information to check Assumptions 2, 4, and 5.

2.4 Limitations

It goes without saying that the approach of this

report is not the only possible one. For example,

Bayesian approaches could be used, such as in

Bier et al. (1990). Other forms for A(t) could also

be developed, besides the three used here. An

approach may be developed for allowing A(t) to

vary continuously in a PRA; this would avoid the

stepwise approximation used here. The indistinct

border between aging and nonaging could be handled in various ways. Although these other

approaches might yield somewhat different

results, valid approaches should not yield substantially different conclusions from the same data.

A related issue is extrapolation. The three models for A(t) considered here (exponential, Weibull,

and linear) could not be distinguished by how well

they fit the data used in this report. However, they

would yield very different results at times far in the

future. This means that none of the models can be

2-3 NUREG/CR-5378
Project Approach

used for reliable distant extrapolation of this data

set. This is no surprise to experienced data

analysts, who recognize the pitfalls of ever

extrapolating a model far beyond the observed

data; for example see Hahn and Meeker (1982).

There is an additional issue affecting extrapolation in the present context. The analysis approach

of this report treats maintenance policies as part of

a component's operating environment, assumed to

be constant. The failure data were generated within

this environment. The maintenance policies would

very probably change, however, if failures started

to occur much more frequently. Therefore, for

extrapolation do not simply ask "Which of the

assumed forms of A(t) is correct?" In reality, none

of them can be extrapolated beyond the point where

maintenance policies would change. Any distant

extrapolation using only the approach of this report

must be regarded at best as a diagnostic tool, not as

a realistic prediction. This report does not show any

extrapolation more than three years beyond the last

year of data.

A valid distant extrapolation, using existing

data, would require the following as a minimum:

thorough knowledge of the past maintenance

policies and the way they affected the failures of

record; explicit incorporation in the model of the

past policies and hypothesized future policies;

and interpretation of the failure data so that what

was observed under the past maintenance policies

can be extrapolated to occurrences when the

future policies are in place. This would be a

formidable task.

2.5 Practical Inference: Is

There Aging?

2.5.1 General Approach. Sometimes we

would like to decide whether aging is present or

not. When the question is phrased in this way, data

analysts often cannot give a conclusive answer.

This apparent indecisiveness follows not from

some perversity of statistical methodology, but

from the poor phrasing of the question. There is no

clear dividing line between aging and non-aging.

Without enormous amounts of data, extremely

slow aging cannot be distinguished from no aging,

and indeed a practical decision-maker probably

does not wish to make a distinction between

extremely slow aging and no aging. It is, therefore,

more informative to replace the yes-or-no question, "Is there aging?" by a quantitative question,

"How much aging is there?"

Aging is modeled in this report, and the amount

of aging is measured by a parameter P3. In each of

the three models assumed in this report, P3 = 0

means that the failure rate is constant, that is,

there is no aging. An increasing failure rate, interpreted as aging of the component, is modeled by

/ > 0, and a decreasing failure rate by P3 < 0.

The yes-or-no question "Is there aging?" corresponds to a statistical test of the hypothesis /3 = 0.

The quantitative question "How much aging is

there?" corresponds to a statistical confidence

interval for P3. In general, a confidence interval

provides more information than a hypothesis test.

The two are related in the following simple way.

Suppose that data have been collected. For any

number P,3g we can test the hypothesis P3 = P,/. A

confidence interval consists of all the values /3o

that would be accepted by the test.

For example, suppose that (IE -5, 6E -5) is a

90% confidence interval for P3. This says that we

are95%confidentthat/ > lE-5and95%confident that /3 < 6E-5, and therefore 90% confident that the interval contains P. The value

P3 = 1E-5isrejectedinfavorofalarger/3atthe

5% significance level. (A significance level is 1

minus a confidence level, so 5% significance and

95% confidence are equivalent.) The value /3 = 0

is also rejected at a significance level less than 5%

because 0 is less than IE -5. In fact, every value

of P3 that is less than IE -5 would be rejected at a

significance level less than 5%. Therefore, the

confidence interval shows not only whether a particular hypothesized P3 is rejected, but also all the

values that are rejected at a given significance

level.

Figure 2-1 shows five hypothetical 90% confidence intervals from imaginary data sets. The

NUREG/CR-5378 2-4
Project Approach

A

B

Q0

D

E

I -I

HI

l

-I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

-6E-5 -4E-5 -2E-5 0 2E-5 4E-5 6E-5 BE-5 1 OE-5

fP (1/h)

Figure 2-1. Hypothetical 90% confidence intervals for P3.

solid vertical line marks fi = 0, indicating no

aging. The dashed vertical line at P3 = 0.5E -5

marks a level that has been judged to be practically negligible. (This number is an illustration

only, not a claim that any particular value of fl is

negligible in reality.) The wide confidence intervals presumably come from data sets with few

observed failures, while the short intervals come

from data sets with many observed failures.

The confidence intervals for A and B both

include the value 0. Therefore, in both cases a test

would not reject the hypothesis /3 =0 at the 5%

level, and the analyst could report that there is no

statistically significant evidence of aging. The

confidence intervals reveal much more, however.

Interval A lies to the left of 0.5E -5, so we are

95% confident that any aging is negligible. Interval B, on the other hand, is quite wide. Failure to

find aging really indicates failure to reach any

firm conclusion at all because of insufficient data.

The intervals C and D both lie to the right of

zero. Therefore, both cases show statistically significant evidence of aging at the 5% level. In

case C, however, the aging is positive, but small

enough to be negligible, while in case D the aging

is clearly not negligible.

Interval E lies entirely to the left of zero.

Therefore, this interval represents the only data

set for which we are 95% confident that there is

no aging.

In this example the five confidence intervals

provide much more information than five

yes-or-no answers to the question, "Is there statistically significant evidence of aging?" As a result,

in this report confidence intervals are generally

preferred over tests as .a way of reporting conclusions. Tests are used only as a preliminary

screening device. A test result should be thought

of as shorthand for part of the information

contained in a confidence interval.

2.5.2 Specific Application. The data for this

report differ from the preceding hypothetical

example in two ways. First, no negligible value

for if has been established. Second, because the

data come from only 10 years at one system in

one plant, they do not yield the extremely short

intervals exemplified by A and C. The interval B

is most typical of the intervals produced from the

small numbers of failures actually observed.

2-5 2-5 ~~~~NUREG/CR-5378
Project Approach

Suppose that interval B corresponded to data

from real components. How should those components be treated in a risk quantification? Should

they be treated as aging or not? In this study, two

options were followed.

* Unless the data show statistically significant

aging at the 5% level, do not change the

PRA. Therefore, the components corresponding to interval B would be treated as

non-aging, with a constant failure rate taken

from the PRA.

* Follow the same approach, but use the 40%

significance level instead of 5%. This is

equivalent to treating the component as

aging only if the 20% confidence interval for

,3 lies to the right of zero. A 20% interval is

much shorter than a 90% interval, so under

this option the components corresponding to

interval B might be treated as aging.

The first option makes minimal changes to the

PRA, only changes that are forced by statistically

significant evidence of aging. The second option

makes more changes. Set D would be treated as

aging under either option, while set B could be

considered aging only under the second. In principle, the second option introduces wider uncertainty bands in the final results, for two reasons.

First, the model for plant risk involves more

parameters, the Pls, and therefore more sources of

uncertainty. Second, components that appear to be

aging at the 40% significance level but not at the

5% level often have large uncertainties in P,

resulting in substantial contributions to the uncertainty in the calculated plant risk.

No data sets in this report give intervals resembling set E, which has a decreasing failure rate

that is statistically significant at the 5% level.

However, some cases of decreasing failure rates

are significant at the 40% level. These are

modeled not as decreasing, but as constant failure

rates, just as in the PRA. Therefore, the second

option biases the approach toward more aging

than is actually present, as follows. Consider a set

of components that actually have a constant

failure rate. There is a 40% chance that they will

appear to be aging at the 40% significance level

because of the random nature of the failures. If

this occurs, they will be modeled as having an

increasing failure rate. On the other hand, there is

no chance that they will be modeled as having a

decreasing failure rate because we choose not to

do this.

2.6 Step-by-Step Approach for

Aging Risk Analysis

Sections 4 through 7 follow a step-by-step

approach for aging risk analysis. These steps are

summarized in the following sections and shown

in the flow diagram of Figure 2-2. The first five

steps of are explained and shown in more detail in

Section 4.1. Steps 6 and 7 are explained and

shown in more detail in Sections 5 and 6.

2.6.1 Step 1. Develop Time Histories of

Components. The first step is to obtain the

information required to develop time histories for

the systems/components to be analyzed. Possible

sources of information include maintenance

records, material histories, operating records, and

plant process computer data. Comparison of data

from numerous sources will aid in the development of the most reliable histories. Although

very little attention was given to this step while

developing this aging risk assessment approach, it

should not be construed that the development is

trivial or unimportant. On the contrary, the time

histories are the backbone of the analysis and may

be extremely difficult to develop. Poorly

developed time histories can result in either the

false identification of aging where none is occurring or the false conclusion that aging is not

occurring when it actually is. These two kinds of

errors result in over- and under-estimation of

future risk, respectively. An overview for data

base development that could be applied to the

development of component time histories was

prepared by the Yankee Atomic Electric

Company (Ghahramani 1989).

NUREG/CR-5378 2-6
Project Approach

MODEL

STEP 1

Section 4

STEP 2 uefine iele

Section 4 Component F Modes

STEP 3 Define Fail

Section 4 Criteria

STEP 4 Apply FailL

Section 4 Data

STEP 5 Construct Fe

Section 4 Timelines and CL Failure Plc

STEP 6 Perform

Sections 5 and 6 Statistical An,

STEP 7 CalculatE

Sections 5 and 6 A(t)

STEP 8 Quantify tl

Section 7 Age-Depender

* MLE = maximum likelihood estimate

vant

:ailure H

tilure

imule

)ts

STEP 6A Test for Common fi

STEP 6B Test for Aging

Test for Assumed

STEP 6C Form of Aging

Model

STEP 6D Test for Common A,

STEP 6E Find MLE* for

Check Normal

STEP 6F Approximation for

Distribution of MLE* ]

LF91 0310

Figure 2-2. An aging risk quantification approach.

2-7 NUREG/CR-5378
Project Approach

Once the raw time-history data are collected,

they should be categorized and stored in some

convenient computer format to allow for easier

reduction and analysis. Section 4 of this report

details the process of data development followed

for this demonstration, from raw maintenance

records to failure occurrence timelines.

2.6.2 Step 2. Define Relevant Component

Failure Modes. The second step is the identification of the failure modes associated with

components or systems being analyzed that will

contribute to an increase in plant risk. These

failures modes should be obtained from a plantspecific PRA. Failure modes removed from consideration in a PRA at an early stage should not be

ignored because of the low contribution to risk

(e.g., removed from the cut sets by truncation).

These failure modes may become more important,

potentially even controlling, as a result of the

increase in their frequency with the passage of

time. The specific component boundaries used in

the PRA for establishing failure modes should also

be noted. These boundaries are necessary to

correctly relate failure history to failure mode.

Section 4.2 contains the definitions of the failure

modes used in this demonstration study.

2.6.3 Step 3. Define Failure Criteria. The

determination of whether a particular record from

the information gathered in Step 1 describes the

occurrence of one of the failure modes listed in

Step 2 is often subjective. The information in the

records was not designed for the development of

failure tracking; therefore, the information is

imprecise as to the exact condition of the component. In order to bracket this subjectivity and to

facilitate a more repeatable development of failure time histories, two sets of failure criteria for

each failure mode are developed in this report.

The first set of criteria is developed for a

"broad" definition of failure. The criteria consist

of a list of those conditions considered to possibly

describe a failure, but which may only describe a

problem that was fixed before it was actually

necessary to remove the component from service.

The second set of criteria is developed for a

"narrow" definition of failure. The criteria consist

of a list of those conditions considered to describe

the actual occurrence of a failure. These failures

resulted either in an automatic loss of component

function or the immediate manual removal of the

component from service to avoid damage.

The narrow failures are a subset of the broad

failures. The use of the narrow definition of failure

allows risk to be quantified with data describing

failures that certainly took place, without the

masking effect caused by information in which

less confidence is placed. At the same time, the use

of broadly defined failures identifies risk trends

that should be investigated further to check their

validity. The setting of these criteria is not simple

and may involve some iteration with their application, as described in Step 4. The broad and narrow

definitions used in this study are given in

Section 4.3.

2.6.4 Step 4. Apply the Failure Criteria to

the Time Histories. The component time histories are reviewed in Step 4 to identify the failures,

using both the broad and narrow definitions. The

failure criteria defined in Step 3 are updated, as

necessary, to incorporate knowledge gained by

the in-depth review of the data. This process is

detailed in Section 4.4.

2.6.5 Step 5. Construct Failure Timelines

and Cumulative Failure Plots. It is useful to

construct graphical representations before starting more formal statistical analysis to summarize

the results. These representations provide a "feel"

for the data and allow some simple trends to be

immediately identified. However, without statistical analysis of the data, it is difficult to determine whether the apparent trends are statistically

significant, and in no case can the trends be quantified. Examples of these graphs are provided in

Section 4.5.

2.6.6 Step 6. Perform Statistical Analysis.

The next step is to model the age-dependent

behavior of the components for which time histories have been developed and to estimate model

parameters from the data. The failure data, using

both the broad and narrow definitions of failure,

should be placed in an appropriate format and

then analyzed statistically. The approach is

explained more fully in Section 5 and carried out

NUREG/CR-5378 2-8
Project Approach

for this demonstration in Section 6. The steps to

perform the statistical analysis are explained

briefly in the following sections.

Step 6A. Test for Common /3 for all Components. Recall that /3 governs whether the failure rate is increasing or not. The assumption that

the /3 values for like components are equal should

be checked by evaluating the significance level

for equality of P3. This testis accompanied by a

plot of confidence intervals for P3, with each interval based on a single component. Although the

assumption of a common P3 was never rejected

with the data of this report, the data should routinely be screened in this way for outliers or other

evidence of dissimilarity among the components.

A decision to delete an outlier should be based on

an engineering evaluation, with the goal of understanding the physical process that resulted in the

observed anomalous behavior.

Step 6B. Test For Aging. Test for the presence

of aging by checking the significance level of the

null hypothesis (P3 = 0) for all sets of components

with homogeneous P3. As mentioned in Section 2.4, two analyses are performed in this

report, one with a critical value of 0.05 and one

with a critical value of 0.40. If the significance

level is less than the critical value, then the null

hypothesis is rejected and the components are

considered to be aging. Otherwise, the components are considered to have a constant failure

rate. All of the remaining steps below are carried

out only if the components are considered to be

aging.

Step 6C. Test Assumed Form of Aging

Model. A graphical check consists of a QuantileQuantile (Q-Q) plot. If a plot shows no marked

divergence of the plotted points from the

45-degree line, then the model appears adequate.

If the overall trend in the data shows a marked

divergence, such as a large "S" shape, then the

assumed aging model appears inadequate to

describe the data and should not be applied. Supplementing the plot, the Kolmogorov-Smirnov

test can be used as a formal test of the assumed

model.

In this report, the Q-Q plots show some indication that the recorded failures tend to cluster in

time. Clustering casts doubt on the assumed

independence of the failures. For most of the data

sets, the clustering was not extreme. For one data

set, however, the clustering was severe enough

that the Kolmogorov-Smimov test rejected or

nearly rejected any of the models assumed. In the

intermediate analysis, the components were modeled as aging, and this data set turned out to be the

dominant contributor to the risk caused by aging.

Therefore, follow-up inquiries at the plant were

made regarding this data set, resulting in a reinterpretation of all those events as non-failures.

This reinterpreted data set was used for the final

analysis. See Section 6.2.3.

Step 6D. Test for Common A, forAll Components. The assumption that the A1 values for like

components are equal should be tested statistically. This is similar to the test for common P.

The assumption never was rejected with the data

of this study.

Step 6E. Find the MLE for (3,,Ad). Having

examined the data and having concluded that the

components may be assumed to have a failure rate

determined by /3 and A,,, the maximum likelihood

estimates (MLEs) of these two parameters should

be found.

Step 6F. Check Normal Approximation for

Distribution of MLE. The MLEs for the two

parameters yield the MLE for the failure rate A(t)

at any time t. The MLE is a point estimate only.

To also get a confidence band for A(t), it is very

useful to say that the MLE for (/3,log A,,) has an

approximately normal bivariate distribution. This

yields a distribution for A(t) that is approximately

lognormal and merges neatly with standard PRA

calculations. The check for the adequacy of the

normal approximation is graphical. For the data

of this demonstration study, approximate normality appeared true when the exponential or Weibull

failure model was used. Approximate normality

was clearly false with the linear model; much

larger data sets would have been needed before

the asymptotic normal distribution was

approached.

2-9 NUREG/CR-5378
Project Approach

2.6.7 Step 7. Calculate A(t). For all sets of

components that survive the screening of Step 6,

the estimated value of A(t) and its associated

confidence interval are calculated as a function of

time using statistical analysis techniques. This

calculation is explained in Section 5 and carried

out in Section 6 using the data of this

demonstration study.

2.6.8 Step 8. Quantify the Age-Dependent

Risk. The final step is to calculate the risk associated with the plant as a function of time. In

Step 7, the MLE for A(t) was found to have an

approximately lognormal distribution. For PRA

calculations, let this distribution define the

Bayesian distribution of A(t). This is not the usual

way to obtain a Bayesian distribution because it

does not involve a prior distribution. It is used

because it yields probability intervals that are

numerically the same as the confidence intervals,

but with a Bayesian interpretation. Based on this

distribution, age-dependent basic-event input is

defined to the PRA. The approaches used in

PRAs are somewhat plant specific, and the details

of the quantification are not presented here. For

this study, the Integrated Reliability and Risk

Analysis System (IRRAS) computer code was

used (Russell et al. 1989).

The results of this time-dependent risk assessment are presented in Section 7. The plant CDF

implied by the increasing failure rates of the components is computed and compared to the PRA

results that were based on constant failure rates.

An approach is suggested in Section 7.2 for using

such results in risk-based management of aging

components.

The demonstration calculation reported in

Section 7 includes only the aging of the components in the AFW system and, therefore, does not

include the interaction of the aging of these components with the aging of components in other

systems. This interaction is described in

Section 7.1.5.

NUREG/CR-5378 2-10
3. PWR AUXILIARY FEEDWATER SYSTEM REVIEW

3.1 Design Function

The auxiliary feedwater (AFW) system supplies feedwater to the steam generators following

the interruption of the main feedwater supply. If

the reactor trips and the main feedwater pumps

cease to operate for any reason, feedwater must

be provided to remove heat from the reactor coolant system using the steam generators. The AFW

system must operate during both normal transient

conditions (e.g., unit startup and shutdown) and

abnormal transient conditions (e.g., loss of main

feedwater, loss of offsite power, and station

blackout).

The AFW system design is both redundant

(there are two trains in parallel) and separate (the

two trains are supplied by different support systems) to ensure its capability to remove heat from

the core. As a result of its design, the AFW system

can function even in the presence of a single active

component failure during the initial demand for

the system or a single passive component failure

during long-term operation.

3.2 Flowpath

The system is shown schematically in

Figure 3-1, and normal system status is summarized in Table 3-1. The normal source of water for

the system is the 110,000-gallon condensate storage tank (CST). Each of the three pumps takes its

suction from the CST through a dedicated line. If

the normal water source is depleted, then one of

three backup sources may be lined up to supply

water to any or all of the AFW pumps. The lineup

is performed by manipulating manually operated

valves. The three alternate water sources are the

300,000-gallon CST, the emergency makeup

system, and the firewater system.

Three pumps move the water from the various

sources to the steam generators. One AFW

system train consists of two electric motor-driven

pumps configured in parallel, each with a capacity of 350 gpm. The other train consists of a single

steam turbine-driven pump, with a capacity of

700 gpm. Flow from each pump discharges

S252 WSR-0690-OD

Figure 3-1. Schematic diagram of the PWR auxiliary feedwater system.

3-1 NUREG/CR-5378
AFW System.Review

Table 3-1. PWR AFW system component status and support system dependency summary.

Support system

dependency

Response to

support system

Component Normal status failure

Pumps

MDP-A

MDP-B

TDP

Standby

Standby

Standby

ac Bus 1H

dc Bus IA

ac Bus 1J

dc Bus lB

Main Steam

Failure to start

or run

Failure to start

or run

Failure to start

or run

Motor Operated Valves

MOV-A, -C, -E

MOV-B, -D, -F

MOV-G

MOV-H

MOV-I

MOV-J

Normally open

Normally open

Normally closed

Normally closed

Normally closed

Normally closed

ac Bus IH

ac Bus IJ

ac Bus IH

ac Bus IJ

ac Bus 2H

acBus2J

Fails as is

Fails as is

Fails as is

Fails as is

Fails as is

Fails as is

Air Operated Valves

AOV-A

AOV-A

Normally closed

Normally closed

Instrument Air

dc Bus IA

Instrument Air

dc Bus IA

Fails open

Fails open

Fails open

Fails open

through a unique discharge isolation check valve

(CV-A, -B, or -C) and then joins flow from the

other pumps in the two combined flow headers

(PS-4 and -5). Normally open manual isolation

valves can be used to isolate any pump from

either of the combined flow headers.

A cross-connect tap on each combined flow

header allows flow from one or both of the headers

to be sent to the other unit. The taps are located outside of containment, upstream of the containment

isolation check valves. Each of the supply lines to

the opposite unit contains a normally open manual

isolation valve and a normally shut motoroperated valve (MOV) (MOV-G and -H). Flow in

each of the combined headers passes through an

outboard containment isolation check valve

(CV-D or -E), through the containment wall, and

then through an inboard isolation check valve

(CV-F or -G). A cross-connect tap on each combined flow header downstream of the containment

isolation check valves allows flow from the other

unit's AFW system to be supplied to one or both

of the combined flow headers. Backflow to the

other unit-via the supply line is prevented by two

NUREG/CR-5378 3-2
AFW System Review

check valves and a normally closed MOV (MOV-I

and -J).

Flow from each of the combined flow headers

branches into six individual headers (PS-6 to -11)

downstream of the supply cross-connect from the

other unit. Each of the six individual headers contains a normally open MOV (MOV-A to -F) and a

stop valve. These six individual headers are then

combined in twos, one from each of the combined

flow headers, to make three new flow headers

(PS-13, -14, and -15). One each of the three new

flow headers is used to feed one of the three steam

generators via the normal feedwater piping.

Backflow from the normal feedwater system is

prevented by a check valve (CV-H, -I, and -J) in

each of the three AFW headers. The AFW flow

taps into the feedwater line with no valves

between the tap and the steam generator.

3.3 Support Systems

Numerous systems support the successful operation of the AFW system. Table 3-1 contains a

summary of support system dependencies and

responses to failure. Suction water is normally

supplied from the condensate system, but may also

be supplied from an emergency makeup system or

from the fire main. Electrical motive power is

supplied to the motor-driven AFW pumps from

the ac emergency power busses. Bus 1H supplies

the 3A pump, and Bus 1J supplies the 3B pump.

Motive power in the form of steam is supplied to

the turbine-driven AFW pump from each of the

three steam generators. The supply lines (PS-15,

-16, and -17) tap off the main steam lines between

the steam generators and the main steam isolation

valves (see schematic in Figure 3-1). The three tap

lines combine into a single header and then split

into two lines (PS-18 and -19), each of which contains an air-operated valve (AOV-A and -B) that is

normally closed, but will open to start steam flow

to the turbine-driven pump; Emergency dc power

can be supplied to control all the pumps. Bus IA

supplies control power for the 3A pump, and

Bus lB supplies control power for the 3B pump.

Failure of dc control power will fail the associated

-motor-driven pump. Busses IA and lB supply the

control power for the air system, which in turn supplies the control air for the air-operated valves that

control the steam supply to the turbine-driven

AFW pump. Failure of dc power or air to the

turbine-driven pump control system will cause the

air-operated valves to fail open, resulting in the

start of the turbine-driven AFW pump. DC control

power is also used to control and position the

motor-operated valves in the six branch lines and

in the cross-connect lines. The valves fail as is on

loss of power. Finally, the automatic actuation of

the AFW system is dependent on the actuation

signals discussed in detail in the next section.

3.4 Automatic Actuation and

System Response

The supply circuit breakers for the motordriven AFW pumps will receive a signal to close

and the pumps will start automatically upon

receiving any one of the following signals:

1. Safety injection actuation signal

2. Trip of the main feedwater pumps

3. Low level in any steam generator

4. Loss of offsite power.

The air-operated steam supply valves for the

turbine-driven AFW pump will receive a signal to

open and the pump will start automatically upon

receiving any one of the following signals:

1. Low level in any two steam generators

2. Undervoltage on any reactor coolant system

main pump bus.

In addition to starting the pumps, the above

signals will also cause an open signal to be sent

to all six of the normally open MOVs in the six

individual headers.

3-3 3-3 ~~~~NUREG/CR-5378
4. COMPONENT FAILURE DATA

The process used in developing the plantspecific AFW system component failure data is

illustrated in Figure 4-1. The individual steps

represented in the figure are described in the

following sections.

4.1 Component History

The first step was to obtain historical information pertaining to the components of interest.

Numerous sources were available, including

maintenance records, operating logs, and monthly

summaries. The combination of information from

all of the sources would obviously result in the

most comprehensive and reliable history. Often,

however, in the interest of time and money, only a

select few sources would be used. Such was the

case for this study, and only documentation

obtained from the maintenance work order system

of an older, dual-unit PWR nuclear power station

was used to develop component histories.

History

Summary

Return to

Service

Date

A very brief summary of what

repairs were performed on the

component.

The day that the component was

declared fully operational.

Maintenance An identification number

Record sequentially assigned to each

Number maintenance work order.

The preceding structure represents the

expected minimum, or rudimentary, data

structure present in any given nuclear power

plant.

To facilitate development of failure data for

subsequent statistical analysis, these additional

categories were added to the data.

Component

Type

A consistent component type

definition)'

The maintenance records for the station were

grouped by major system, with the AFW system

records mixed with the main feedwater (FW) and

the emergency feedwater (EFW) system records.

Plant piping and instrument diagrams were used in

conjunction with the maintenance records to distinguish components among these three systems.

A total of 1156 AFW events were thus identified

for further analysis.

Classification

Replace

Number of

Replacements

A code reflecting the final classification of the record as either

describing a failure or describing

some other maintenance action.

A flag indicating complete

component replacement events.

The running

replacements

component

number).

total number of

for the particular

location (mark The data were received encoded in the

following data structure:

Mark Number

Component

Problem

Description

Alpha-numeric identification for

the component. In fact, this

number refers to a component

location in the plant system.

Type name of the component.

A very brief and typically cryptic

explanation of why work was

performed on the component.

Notes on specific alterations or changes in the

data (e.g., correction of misspellings or standardization of formats for consistency) were maintained in a change field, unique to each record.

After the standardization, the AFW component

b. As an example, three separate, independent

maintenance activities on a single 3-in. check valve

referred to the valve as a"valve," a"checkvalve," and

an "isolation valve" in the component field of the

maintenance work order documentation.

4-1 NUREG/CR-5378
Component Failure Data

MODEL ACTUAL

Obtain Component

History 1

Define Relevant

Component

Failure Modes

Define Failure

Criteria

Apply Failure

Criteria to Data

A. Used maintenance records for the feedwater

system of an older dual-unit PWR. Records

covered 10 years of plant operation.

B. Identified AFW subset.

Used representative PRAs to identify all failure

modes that could result in loss of safety-significant

component functions.

Developed two sets of criteria:

1. Broad - A list of conditions that could possibly

describe a failure, but may have described a

problem that was fixed before the component

had to be removed from service.

2. Narrow - A list of conditions that could describe

the actual occurrence of a failure (a subset of

the broad category).

A. Reviewed all AFW system records to identify

those describing conditions satisfying the

broad criteria.

B. Reviewed all failures classified as broad to

identify those describing conditions satisfying

the narrow criteria.

A. Plotted timeline of each component's failures,

grouping similar components to show gross

trends.

B. Plotted cumulative failure curves by failure

mode.

Construct Failure

Timelines and

Cumulative Failure

,

Curves I

LF91 0312

Figure 4-1. Process used to develop component failure data.

NUREG/CR-5378 4-2
Component Failure Data

event records were sorted and then segregated

into 12 major component groups, as shown in

Table 4- 1.

Table 4-1. Distribution of raw maintenance

events for the AFW system according to

component type.

Number

Component type of events

Steam-driven pump (TDP)

Motor-driven pump (MDP)

3-in. motor-operated valve (MOV)

(individual feed header isolation)

6-in. motor-operated valve (MOV)

(cross-connect header isolation)

l-in. check valve (CV)

(pump recirculation)

3-in. check valve (CV)

(individual feed header)

4-in. check valve (CV)

(pump discharge header)

6-in. check valve (CV)

(pump discharge header)

190

262

354

54

11

44

11

9

28

4.2 Definition of Relevant

Component Failure Modes

A list of 15 component failure modes (basic

events) was developed from a survey of the AFW

models contained in three representative PRAs.

Table 4-2 lists these AFW component failure

modes. The component numbers can be matched

to the component locations on the AFW system

schematic shown in Figure 3-1. Because the data

were incomplete, we made no attempt to quantify

the two failure modes involving unavailability

resulting from testing or maintenance. The

remaining 13 modes were considered in the failure

evaluations described in Sections 4.3 and 4.4.

The system boundaries used to establish the

failure modes in Table 4-2 are basically evident by

inspection of the modes. The following specific

ground rules were used to develop the component

boundaries in the NUREG-1150 PRA (USNRC

1989) and to develop the failure criteria in the

following section:

* Assume pump and valve breakers and

control circuits are part of the component

* Model ac and dc power to the breaker and

control circuits as a separate support system

and, thus, not an AFW failure mode.

4.3 Definition of Failure Criteria

Failure modes for the components of the AFW

system were described in the previous section.

The interpretation of the maintenance records to

determine which ones indicated the presence of a

failure was subjective. Because the information in

the records was not designed for the development

of failure tracking, the information was imprecise

concerning the exact condition of the component.

In order to bracket this subjectivity and to facilitate a more repeatable analysis, or comparison

with similar analyses, it was necessary to develop

a set of criteria to define when a failure mode was

satisfied. To cover the spectrum of events that

might reasonably be considered failures, two sets

of criteria were developed for each failure mode.

6-in. check valve (CV)

(combined feed header)

Stop valves (various) 61

Piping (various)

Instruments (various)

111

21

Total 1156

4-3 NUREG/CR-5378
Component Failure Data

Table 4-2. AFW system component failure modes, descriptions, and relevant component numbers,

corresponding to Figure 3-1.

Failure mode Description

AFW-ACT-FA-PMP-* No actuation signal to pump. *MDP-A, -B

AFW-ACT-FA-* No actuation signal to steam supply valve. *AOV-A, -B

AFW-AOV-LF-* Loss of flow through steam supply valve. *AOV-A, -B

AFW-CKV-FI-* Check valve fails to open. *3 in. CV-H, -I, -J; 4 in. CV-B, -C; 6 in. CV-A,

-D, -E, -F, -G; Main Steam, 3 in., CV-K, -L, -M.

AFW-CKV-OO-* Backflow through pump discharge check valve. *CV-A, -B, -C

AFW-MOV-PG-* Motor-operated valve plugged. *MOV-A, -B, -C, -D, -E, -F

AFW-PMP-LK-STMBD-* Undetected, simultaneous leakage through one of the following

combinations of check valves: [At least one of CV-H, -I, -J] and [either

CV-D and -F or CV-E and -G] and [CV-A for *TDP or CV-B for *MDP-A;

CV-B or CV-C for *MDP-B].

AFW-PMP-FR-* Pump fails to run. *TDP, MDP-A, -B

AFW-PMP-FS-* Pump fails to start. *TDP, MDP-A, -B

AFW-PMP-TM-* Pump unavailable due to testing or maintenance.

*TDP, MDP-A, -B

AFW-PSF-FC-XCONN-* Flow diversion to opposite unit through motor-operated valves.

*MOV-G, -H, -I, -J

AFW-PSF-LF-* Faults in pipe segments. *Various pipe segments.

AFW-TNK-VF-CST Insufficient water available from 11 0,000-gal condensate storage tank.

AFW-XVM-PG-XV-* Manual valve plugged. *Various manual valves.

AFW-*-TM-* Component unavailable due to testing or maintenance. *Any AFW

component in testing or maintenance when it is required to be in service.

* Refers to the components listed at the end of the associated description. For example, the two failure modes corresponding to the first entry of the table are AFW-ACT-FA-PMP-MDP-A for motor-driven pump A and AFW-ACT-FAPMP-MDP-B for pump B.

NUREG/CR-5379 4-4
Component Failure Data

The first set of criteria was developed for what

is called a "broad" definition of failure. The criteria consist of conditions that could possibly have

described a failure, but which may have described

a problem that was fixed before the component

had to be removed from service. For example, a

failure record for steam-driven pumps was considered to describe a broad failure if it stated one

of the following:

1. Conditions existed that led to the repair of

the lubricating oil cooling system.

2. Conditions existed that led to a bearing

repair or replacement.

3. Conditions existed that led to the repair of

the trip/governor valve.

4. Conditions of high vibration existed.

5. Conditions existed that led to the repair of

the pump for some unspecified reason.

6. Conditions existed that led to a control

system repair.

7. Pump failed to start or run.

Records that were not considered as failures by

the broad definition included those resulting from

preventive maintenance programs (including

planned overhauls), design changes, functionally

unimportant boundary leaks, gauge replacements,

and minor deficiency repairs. Also removed were

failures that resulted directly from improperly

performed maintenance, such as a failure of the

turbine-driven feed pump from overpressurization caused by an improper valve lineup during a

surveillance test.

The second set of criteria was developed for a

"narrow" definition of failure. The criteria consist

of those conditions considered to describe the

actual occurrence of a failure. These failures

resulted either in an automatic loss of component

function or the immediate manual removal of the

component from service to avoid damage. For

example, a failure record for steam-driven pumps

was considered to describe a narrow failure if it

stated one of the following:

1. The pump failed to start or run.

2. A gross loss of lubrication occurred.

3. The governor valve did not open.

4. Gross vibration occurred.

The narrow failures are a subset of the broad

failures. Risk can be quantified with the narrow

definition of failure (using data describing failures that certainly took place) to avoid the masking effect caused by information in which less

confidence is placed. At the same time, risk

trends can be identified with the broadly defined

failures that should be investigated further to

check their validity. Setting these criteria was not

simple and involved some iteration with their

application.

4.4 Application of Failure

Criteria to the Data

4.4.1 Broadly Defined Failure Data. The 1156

records were evaluated carefully to determine

which ones indicated that a broadly defined failure

had occurred. There were 163 broad failure

records identified in the maintenance events distributed across component types, as indicated in

Table 4-3. These 163 records were reduced to

118 failure events distributed across failure

modes, as indicated in Table 4-4. The reduction

occurred because, on occasion, several maintenance records described the same failure event.

Note that evidence of only 6 of the 13 failure

modes was found in the documentation. The

following paragraphs describe the logic employed

in evaluating the maintenance data for broadly

defined failures, as well as the logic for classification of the remainder of the events as non-failures.

Table B-1 in Appendix B lists the AFW records

grouped by component type, indicating failure

classification by record. Table 4-5 is a short

sample of entries from Table B- 1. In Table B-2 of

Appendix B, all the non-failure records in

4-5 NUREG/CR-5378
Component Failure Data

Table 4-3. Distribution of broadly defined

failure occurrences according to component type.

Number of

Component type failure records

Table 4-4. Distribution of broadly defined

failure occurrences according to failure mode.

Number of

Failure mode failures

AFW-ACT-FA-PMP 0 Steam-driven pump (TDP)

Motor-driven pump (MDP)

3-in. motor-operated valve

(MOV) (individual feed header

isolation)

6-in. motor-operated valve

(MOV) (cross-connect header

isolation)

3-in. check valve (CV)

(individual feed header)

4-in. check valve (CV)

(pump discharge header)

28

27

AFW-ACT-FA 0

AFW-AOV-LF 0

45

AFW-CKV-FT 0

AFW-CKV-OO 12, Oa

15 AFW-MOV-PG 41

AFW-PMP-LK-STMBD 2

AFW-PMP-FR-MDP 11

18

-TDP 24

8 AFW-PMP-FS-MDP 16

-TDP 0

6-in. check valve (CV)

(pump discharge header)

6-in. check valve (CV)

(combined feed header)

Stop valves (various)

6 AFW-PSF-FC-XCONN 12

AFW-PSF-LF 0

16

0

AFW-TNK-VF-CST 0

AFW-XVM-PG 0

Total 118, 106a

Piping (various) 0

Instruments (various) 0

a. Twelve events were initially classified as backflow failures of check valves. After discussion with

personnel from the power station, these events were all

Total 163 reinterpreted as non-failures. See Section 6.2.3.

Table B-1 have been removed, and only the

records fitting the broad definition of failure

remain. Table 4-6 is a sample portion of records

from Table B-2. To assist further in the evaluation

of the failures, the "Problem Description" and

"History Summary" sections for each of the

163 broadly defined failures were rewritten in a

more readable format as the "Problem/Repair

Summary." Table B-3 in Appendix B contains the

rewritten records, and a sample portion is shown

in Table 4-7. (Refer to Appendix B for the specific

records described in the following discussion.)

NUREG/CR-5378 4-6
Table 4-5. Sample of maintenance records for the AFW system steam-driven pumps (excerpted from Table B-1).

Maintenance Return to service

Mark request Mode/mechanism (if applicable) datea/

number Component number Problem description history summary classification'

1-TDP

1 -TDP

I-TDP

1-TDP

2-TDP

I-TDP

2-TDP

1-TDP

1-TDP

A41- 1-TDP

_J 1-TDP

1-TDP

1-TDP

1-TDP

2-TDP

1-TDP

1-TDP

1-TDP

2-TDP

1-TDP

Pump

Pump

Valve

Pump

Pump

Turb

Pump

Pump

Pump

Pump

Pump

Turb

Instr

Pump

Pump

Valve

Pump

Pump

Instr

Instr

801010430

803030420

10176160

901030450

901261550

810040500

902131328

905021900

905181332

902040100

905101032

811030530

910201310

911011230

902201305

910201305

Gross oil-low discharge pressure

Excessive discharge PREE-PT15

Body to bonnet leak

Gov valve will not control pump

speed

Refuel PMS

Various repairs

trip valve

Oil cooler end bell cracked

Drain, clean, inspect sump refill

Sight glass has oil leak

Head gasket leaks on pump

Adjust packing

Governor valve inoperative

Replace gauge and repair leak

Oil leak on pump

PMS as per MMP-P-FW-004

Replace handwheel

Renewed thrust bearing linings

Reduced speed of Pump at

governor

Renewed bonnet gasket

Fixed satisfactory

Did PMS checks

Repaired and tested governor

Void

Drained oil, cleaned sump

Tightened sight glass

Void

Void

Void

Replaced gauge

Repaired Pump and held pm check

Void

Found handwheel to be properly

installed

Renewed thrust bearing

throwing oil

Renewed thrust shoe

Replaced glass

Installed new switch

780111 FR

780303 FR

780508 BL

790204 FR

790228 PMS

790420 FR

790420 VOID

790515 PMS

790611 MD

790917 VOID

790917 VOID

791002 VOID

791102 GAUGE

791116 MD

791128 VOID

791209 MD

791223 FR

800210 FR

800319 MD

800429 FR

912172125 Outboard pump bearing

1240708

2191428

4131129

Oil seal packing leak

Deficiency punch list

Broken case switch

LIV

00

Q0

0

.0

b

a. Note that date format is year, month, and day.

b. PMS - preventive maintenance; BL - boundary leak; VOID - record voided; MD - minor deficiency; GAUGE - gauge replacement or calibration; FR - failure

to run.
Q

o4

00

00

Table 4-6. Sample of maintenance records broadly classified as failures for the AFW system steam-driven pumps (excerpted from Table B-2).

Maintenance Return to service

Mark request Mode/mechanism (if applicable) datea/

number Component number Problem description history summary classificationb

1-TDP Pump 801010430 Gross oil-low discharge Renewed thrust bearing linings 780111 FR

pressure

1-TDP Pump 803030420 Excessive discharge Reduced speed of pump at governor 780303 FR

PREE-PT 15

1-TDP Pump 901030450 Gov valve will not control Fixed satisfactory 790204 FR

pump speed

1-TDP Turb 810040500 Various repairs Repaired and tested governor trip valve 790420 FR

1-TDP Pump 912172125 Outboard pump bearing Renewed thrust bearing 791223 FR

throwing oil

1-TDP Pump 1240708 Oil seal packing leak Renewed thrust shoe 800210 FR

1-TDP Instr 4131129 Broken case switch Installed new switch 800429 FR

2-TDP Pump 11170730 Overspeed trip valve trips Straightened linkage 801118 FR

2-TDP Pump 205081945 Governor set at 4060 RPM Reset RPM to 3880 820513 FR

l-TDP Pump 208132145 Repair oil leak Changed thrusted shaft collar journal 820824 FR

2-TDP Governor 212061305 Repair feedback arm Reinstalled setscrew 821207 FR

2-TDP Pump 302111050 Pump trips Adjusted overspeed trip 830216 FR

2-TDP Pump 303101430 Set screw missing Adjusted damper 830314 FR

2-TDP Pump 303181232 Overspeed trip Put spring back on hook 830321 FR

2-TDP Pump 304250400 Oil seal leaking Replaced bearing and thread shoes 830429 FR

2-TDP Bearing 306200726 Replace bearing Replaced bearing and shoes 830927 FR

2-TDP Pump 309271700 High bearing vibrations Adjusted linkage 831013 FR

1-TDP PMPGov 312311328 Repair governor Installed new seat 840111 FR

2-TDP Switch 402240947 Pump will not cut off in auto Checked switch 840330 FR

1-TDP Pump 14061 Mechanical linkage broken Reinserted rod and closed socket 850214 FR

ends around ball tip

a. Note that date format is year, month, and day.

b. FR - failure to run.

n- 0

2

lt0

0

q*1

-t
Table 4-7. Sample of maintenance records broadly classified as failures for the AFW system steam-driven pumps, rewritten format (excerpted

from Table B-3).

Mark

number

I-TDP

1-TDP

1-TDP

I-TDP

I-TDP

I-TDP

1-TDP

'O I-TDP

2-TDP

2-TDP

I-TDP

2-TDP

2-TDP

Component

Pump

Pump

Pump

Turb

Pump

Pump

Instr

Pump

Pump

Pump

Governor

Pump

Maintenance

request number

801010430

803030420

901030450

810040500

912172125

1240708

4131129

11170730

205081945

208132145

212061305

302111050

Problem/repair summary

The lubricating oil pressure failed low resulting in bearing damage, replaced

thrust bearing lining.

The pump discharge pressure was high, adjusted the governor to reduce the

pump speed and thus discharge pressure.

The governor valve was not controlling pump speed, governor was repaired in

some manner.

Various non-specified repairs were made to the pump, the pump was returned

to service.

The outboard pump bearing was throwing enough oil that it was necessary to

renew the thrust bearing.

An oil seal packing leak was large enough that it was necessary to renew the

thrust bearing shoe.

A broken case switch associated with the discharge pressure trip was found and

replaced.

Deficiencies in the overspeed trip valve caused a pump trip, the linkage was

straightened.

The governor was controlling pump speed high at 4060 rpm, it was reset to

control at 3880 rpm.

An oil leak was large enough that it was necessary to replace some bearings.

The feedback arm of the governor was not working correctly, a setscrew was

installed.

The overspeed trip caused inappropriate pump trips, the overspeed trip was

correctly adjusted.

Return to service

datea/

classificationb

780111 FR

780303 FR

790204 FR

790420 FR

791223 FR

800210 FR

800429 FR

801118 FR

820513 FR

820824 FR

821207 FR

830216 FR

O

IV

(!h W__J 00

nI To

El

ITI

W.

Pa

a. Note that date format is year, month, and day.

b. FR -; failure to run.
Component Failure Data

Main AFW Steam-Driven Pumps (AFWPMP-FR-TDP and AFW-PMP-FS-TDP). A

failure record was considered to describe a broad

failure if it stated one of the following:

1. Conditions existed that led to the repair of

the lubricating oil cooling system.

2. Conditions existed that led to a bearing

repair or replacement.

3. Conditions existed that led to the repair of

the trip/governor valve.

4. Conditions of high vibration existed.

5. Conditions existed that led to the repair of

the pump for some unspecified reason.

6. Conditions existed that led to a control

system repair.

7. Pump failed to start or run.

Of the 190 records, 28 were determined to fit

the broad failure category. Four of these 28 were

determined to reflect previous failure events, and

thus 24 unique failures were seen. The items eliminated from failure consideration were 47 void

records, 17 packing leaks, 25 preventive maintenance items, 23 gauge replacements/calibrations,

30 minor deficiencies, 10 design changes, seven

nonfunctional failures, and three failures caused

by improperly performed maintenance.

Main AFW Motor-Driven Pumps (AFWPMP-FR-MDP and AFW-PMP-FS-MDP). A

failure record was considered to describe a broad

failure if it stated one of the following:

1. Conditions existed that led to the repair of

the lubricating oil cooling system.

2. Conditions existed that led to a bearing

repair or replacement.

3. The motor heaters failed.

4. Conditions existed that led to the repair of

the pump for some unspecified reason.

5. Conditions existed that led to an electrical

control system repair.

6. Pump failed to start or run.

Of the 262 records, 27 were determined to fit

the broad failure category. The items eliminated

from failure consideration were 46 void records,

44 packing leaks, 52 preventive maintenance

items, 28 gauge replacements/calibrations,

55 minor deficiencies, seven design changes, and

three failures caused by improperly performed

maintenance.

3-In. MOV (Individual Feed Header

Isolation, AFW-MOV-PG). A failure record

was considered to describe a broad failure if it

stated one of the following:

1. Conditions existed that led to an electrical

control system repair. (All torque switch

problems were considered failures, but

adjustment of limit switches was generally

not considered a failure.)

2. Mechanical binding/obstruction was noted.

3. Valve was replaced.

4. Supply breaker tripped.

5. Valve failed to open or stay open.

Of the 354 records, 45 were determined to fit

the broad failure category. Four of these were

determined to reflect previous failure events, and

thus 41 unique failures were seen. The items

eliminated from failure consideration were

66 void records, 37 pressure boundary leaks,

112 preventive maintenance items, 21 seat leaks,

14 limit switch malfunctions, 37 design changes,

20 minor deficiencies, and two failures caused by

improper maintenance.

6-In. MOV (Cross-Connect Header

Isolation, AFW-PSF-FC-XCONN). A failure

record was considered to describe a broad failure

if it stated one of the following:

1. Conditions existed that led to an electrical

control system repair. (All torque switch

problems were considered failures, but

NUREG/CR-5378 4-10
Component Failure Data

adjustment of limit switches was generally

not considered a failure.)

2. Mechanical binding/obstruction was noted.

3. Valve was replaced.

4. Supply breaker tripped.

5. Valve failed to close or stay closed.

Of the 54 records, 15 were determined to fit the

broad failure category. The items eliminated from

failure consideration were 19 void records, one

boundary leak, 14 preventive maintenance items,

one limit switch malfunction, and four minor

deficiencies.

3-, 4-, and 6-In. Check Valves (Individual, Combined, and Pump Discharge

Headers AFW-CKV-FT, AFW-CKV-OO, and

AFW-PMP-LK-STMBD). A failure record was

considered to describe a broad failure if it stated

one of the following:

* For the failure-to-open mode:

The valve failed to open.

* For the backflow mode (applicable only to

pump discharge check valves):

1. Conditions existed that led to the

repair of the valve seat or disc.

2. Seat leakage occurred.

* For the steam binding mode:

1. Conditions existed that led to the

repair of the valve seat or disc.

2. Seat leakage occurred.

Of the 92 records, none indicated a failure to

open, but 14 were determined to fit the broad definition of backflow and 48 were determined to

indicate leakage that might lead to steam binding.

The 14 backflow records were a subset of the

records that contributed to steam binding. Two of

these 14 were determined to reflect previous

failure events, and thus 12 unique failures were

seen. The remaining 44 records were eliminated:

19 void records, nine preventive maintenance

items, and 16 boundary leaks.

As noted in Table 4-2, for steam binding to

occur, one of the three 3-in. (CV-H, -I, and -J)

check valves had to leak simultaneously with

either of the two 6-in. combined header check

valves (CV-D and -F or CV-E and -G) and one

pump discharge check valve (CV-A, -B, or -C). A

failure timeline containing all 48 broadly defined

check valve failures was constructed to search for

combinations that could lead to failure (Figure 4-2). Failure could have occurred on one

occasion each for a steam-driven pump and a

motor-driven pump (MDP-B), both in Unit 2.

Thus, only two broadly defined occurrences of

steam binding were observed.

1-In. Check Valves, Stop Valves, Piping,

and Instruments. None of the 204 records in

these four categories were determined to be broad

failures for the following reasons: none of the stop

valves became plugged; none of the instrument

failures caused failure of any associated equipment; and neither 1-in. check valves nor pipe failures were modeled in the PRA. The records

included minor valve deficiencies, piping support

deficiencies, gauge calibrations/replacements,

and preventive maintenance items.

4.4.2 Narrowly Defined Failure Data. A small

fraction of the maintenance narrative records

(5%) contained sufficient information to fit the

category of a narrowly defined failure. These

were determined by careful reevaluation of the

163 broad failure records, as shown in Table B-3

of Appendix B. The 72 narrowly defined failure

records are shown in Table B-4 of Appendix B. A

sample portion of Table B-4 is shown in

Table 4-8. The distribution of the 72 failure

records across component types is shown in

Table 4-9. The 72 failure records were reduced

to 35 failure events distributed across failure

mode, as shown in Table 4-10. The reduction

occurred because, on occasion, several maintenance records described the same failure event.

The following paragraphs present the logic used

4-11 NUREG/CR-5378
Component Failure Data

Component Mark No. 1978 1979 1980 1981 1982 19B3 19B4 1985 1986 1987

Individual [ c header L ic1-CV-D

Pump l-CV-F

discharge I-CV-E

_1-CV-G

Combined F 1CV-A

header L I-Cv-C

2-CV-H

2-CV-H(H I

Individual 2-Cv-1

header 2-CV- I W

2-CV-J

2-.CV-J (R)

2-CV-D

Pump 2-CV-F

discharge 2-CV-E

2-CV-G

Combined F 2 CV-A

header L 2-CV-C

I i I I I I I I I

- --- ----------------- --- - -0-------- 0- - ------ - - -------------------

_ ..................................................... ..................................................................................................................... .............................-

- .. _ .. .................................................-

..

_ _. .0.. -1-------- ------------- --- 0 0 ----- -------- ----........................... ............ ....................................... .......................... - -_

- ------------- ----------------- --- -------------- 0------------- ------- _

- ............................................- ............................. .......................... ............ .......

_------.----------------X--------------------------------- ------ -------- -------- _., _ _ . _ . . .....

.......... .. I.... .. . ..... I... I .....

0 10 20 30 40 50 60

u Broadly defined failures Hours to failure from August 24. 1977

* Narrowly defined failures - (thousands)

o Broadly defined failures with component replacement

70 80 90

S252 SR-0391-O7

Figure 4-2. Failure timelines to determine the occurrence times of steam binding of the AFW system

pumps.

to determine which of the broadly defined failure

records could be classified as failures by the

narrow definition.

Main AFW Steam-Driven Pumps (AFWPMP-FR-TDP and AFW-PMP-FS-TDP). A

failure record was considered to describe a

narrow failure if it stated one of the following:

1. The pump failed to start or run

2. A gross loss of lubrication occurred

3. The governor valve did not open

4. Gross vibration occurred.

Of the 28 broadly defined failures, only nine

were determined to fit the narrow failure category. Four of these nine were determined to

reflect previous failure events, and thus

five unique failures were seen. Records

representing apparently minor deficiencies not

considered to be failures were eight bearing/

lubrication deficiencies, nine control valve deficiencies, one nonspecified pump repair, and one

vibration event.

Main AFW Motor-Driven Pumps (AFWPMP-FR-MDP and AFW-PMP-FSR-MDP).

A failure record was considered to describe a

narrow failure if it stated one of the following:

1. The pump failed to start or run

2. The supply breaker tripped

3. A gross loss of lubrication occurred

4. Gross vibration occurred.

Of the 27 broadly defined failures, only four

were determined to fit the narrow failure category. Records representing apparently minor

deficiencies not considered to be failures were

nine lube oil cooler deficiencies, one bearing/

NUREG/CR-5378 4-12
Table 4-8. Sample of maintenance records narrowly classified as failures for the AFW system steam-driven pumps, rewritten format (excerpted

from Table B-4).

Mark

number

1-FW-P-2

2-FW-P-2

2-FW-P-2

Component

Pump

Pump

Pump

(A2-FW-P-2 Pump

Maintenance

request number

801010430

11170730

302111050

303181232

40487

41325

40450

40488

40491

Problem/repair summary

The lubricating oil pressure failed low resulting in bearing damage, replaced

thrust bearing lining.

Deficiencies in the overspeed trip valve caused a pump trip, the linkage was

straightened.

The overspeed trip caused inappropriate pump trips, the overspeed trip was

correctly adjusted.

Failure of the overspeed trip spring to stay engaged led to a pump trip, the

spring was reinstalled.

The governor valve would not open, spring was replaced but this did not help.

Governor was removed and overhauled because poor operation.

(This event was combined with record 40487)

Additional governor work combined with record 40487.

Additional governor work combined with record 40487.

Additional governor work combined with record 40487.

Return to service

datea/

classificationb

780111 FR

801118 FR

830216 FR

830321 FR

860907 FR

860927 FR

860930 FR

860930 FR

860930 FR

I-FW-P-2

I-FW-P-2

Pump

Pump

I-FW-P-2 Pump

1-FW-P-2 Pump

1-FW-P-2 Pump

00

0

0

~1

a. Note that date format is year, month, and day.

b. FR - failure to run.
Component Failure Data

Table 4-9. Distribution of narrowly defined

failure occurrences according to component type.

Number of

Component type failure records

Table 4-10. Distribution of narrowly defined

failure occurrences according to failure mode.

Number of

Failure mode failures

AFW-ACT-FA-PMP 0 Steam-driven pump (TDP)

Motor-driven pump (MDP)

3-in. motor-operated valve

(MOV) (individual feed

header isolation)

6-in. motor-operated valve

(MOV) (cross-connect

header isolation)

3-in. check valve (CV)

(individual feed header)

4-in. check valve (CV)

(pump discharge header)

9

4

22

AFW-ACT-FA 0

AFW-AOV-LF 0

AFW-CKV-FT 0

AFW-CKV-OO 0

7

AFW-MOV-PG 18

AFW-PMP-LK -STMBD 2

4 AFW-PMP-FR -MDP 0

-TDP 5

7

AFW-PMP-FS -MDP 4

6-in. check valve (CV)

(pump discharge header)

6-in. check valve (CV)

(combined feed header)

Stop valves (various)

Piping (various)

Instruments (various)

6 -TDP 0

AFW-PSF-FC-XCONN 6

13

0

0

AFW-PSF-LF

AFW-TNK-VF-CST

AFW-XVM-PG

0

0

0

Total 35

0

Total 72 1. The valve failed closed

2. The valve failed to open

lubrication deficiency, one vibration event, four

slow pump starts, three motor wetting events, and

five heater failures.

3-In. MOV (Individual Feed Header

Isolation, AFW-MOV-PG). A failure record

was considered to describe a narrow failure if it

stated one of the following:

3. The valve was stuck (no specified direction)

4. The supply breaker tripped.

Of the 45 broadly defined failures, only

22 were determined to fit the narrow failure category. Four of these 22 were determined to reflect

previous failure events, and thus 18 unique

NUREG/CR-5378 4-14
Component Failure Data

failures were seen. Records representing apparently minor deficiencies not considered to be failures were eight control deficiencies, nine

mechanical deficiencies, and six failure-to-close

events.

6-In. MOV (Cross-Connect Header

Isolation, AFW-PSF-FC-XCONN). A failure

record was considered to describe a narrow

failure if it stated one of the following:

1. The valve failed open

2. The valve failed to close

3. The valve was stuck (no specified direction)

4. The supply breaker tripped.

Of the 15 broadly defined failures, only seven

were determined to fit the narrow failure category. One of these seven was determined to

reflect a previous failure event, and thus six

unique failures were seen. Records representing

apparently minor deficiencies not considered to

be failures were one control deficiency, three

mechanical deficiencies, and four failure-to-close

events.

3-, 4-, and 6-1n. Check Valves (AFWCKV-OO and AFW-PMP-LK-STMBD). A

failure record was considered to describe a

narrow failure if it stated one of the following:

* For the backflow mode (applicable only to

the pump discharge check valves): gross

seat leakage occurred.

* For the steam binding mode: seat leakage

occurred.

Of the 48 broadly defined failures, none were

determined to fit the narrow category of backflow

failure, and 30 were detennined to fit the narrow

failure category for steam binding failure.

Records representing apparently minor

deficiencies not considered failures were 18 valve

inspections/overhauls where the record did not

state that the valve had been leaking.

A failure timeline was constructed to search for

those combinations of valves leading to steam

binding, as was done for the broadly defined failures (Figure 4-2). Failure could have occurred on

one occasion each for a steam-driven pump and a

motor-driven pump (MDP-B), both in Unit 2.

Thus, only two narrowly defined occurrences of

steam binding were observed.

In summary, based on maintenance records and

the logical application of the important failure

modes modeled in the PRA, 118 broadly defined

and 35 narrowly defined failures were determined to have occurred in the AFW system in the

10-year period. These failures were statistically

analyzed to determine if the rate of failure was

increasing with time.

Finally, note that the "retum-to-service-date"

was used as a surrogate for the actual date a failure occurred because actual dates were not available for this period of operation. In general, the

return-to-service-date was within one month of

the actual failure date.

4.5 Failure Timelines and

Cumulative Failure Curves

The timelines and cumulative failure curves

corresponding to the descriptions in the previous

sections appear as Figures 4-3 through 4-19. A

time plot is simply a graphical tabulation of the

failure times. A cumulative failure curve is a plot

of the cumulative numbers of failures as a function of time. This plot will be an approximately

straight line for a constant failure rate process

(see Section 5.3.2). A general observation for the

behavior of the data can be derived from the timelines and cumulative failure plots. If the failures

are largely concentrated in later years and the

cumulative failure curve is therefore concave

upward, then there is a general indication of

increasing failure rate, suggesting aging of the

components. If the failures are largely concentrated in the earlier years and the cumulative failure curve is therefore concave downward, then

there is a general indication of decreasing failure

rate.

4-15 NUREG/CR-5378
Component Failure Data

1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 Compo

Mark

1~

2.

1-MI

1-MI

2-MI

2-M

nen . : No.

-TDP o.. 00.000 o o- - oo o 0 . 0 ............... . 0 o -.0- -o ... -

-TDP . -. ... o..... o-- 0 .........-..... -

)P-A -...... 0 . .... 0.............. .-

DP- W.0.0. o ---------

)P-A.0......:.0.-

DP-B_.0..---------- :) - ............... 0 ....... ............... ......................................................................................... .....

0 10 20 30 40 50 60 70 80 _0

Hours to failure from August 24, 1977 (thousands)

0 Broadly defined failures to run

* Narrowly defined failures to run S252 SR-0690-

Figure 4-3. Failure to run timeline for steam- and motor-driven pumps.

II

-01

1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 - v I , I I

LI)

._6

0,

o

-0

0,

-o

E

in

0)

Co

._

20

15

10

5

.,,

* -I

- -"'a

- 0-

,, I _ _ ,I I . . . I

. S"

I* --I

0v0

* ---,

* --

0-1

* --

I

I

I .. . .... I I....I .... I....

0

Figure 4-4.

- . . . . . . . . . . . . . . . . . .. .. . . . .

0 10 20 30 40 50 60 70 80 90

Hours to failure from August 24, 1977 (thousands) SA-0690-09

Cumulative failure plot for steam-driven pumps, broadly defined failures to run.

NUREG/CR-5378 4-16
Component Failure Data

1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 6

U)

0,

-o

E

-o

E

C5

4

3

2

1

I I I I I

-- 0 -

*

- S

0

-o --

0 a I a 10 I at II 20 a at a 30 II a a i 40 Ia i a a 50 I a a a a 60 Ia a a a 70 I at gal 80 i a. 90

0

Figure 4-5.

0 10 20 30 40 50 60 70 80 90

Hours to failure from August 24, 1977 (thousands) 5252 SR 0690 10

Cumulative failure plot for steam-driven pumps, narrowly defined failures to run.

1978 1979 1980 1981 1982 1983 1984 1985 1986 1987

._

n

W

>-

4-

0

CD

-D

E

0)

co

E

U12

11

10

9

8

7

6

5

4

3

2

1

0

I I I I I I I I ,

a 0-

6/ -

S, _

, _

* ,, _

-o' 0

0

I I

. I . . . . . . .II I I 1.1 I I 1 1 I I I I 1 1 I 1 1 1 I I I I I I I I I I I -, .. . . . a.1 . . .i . .

0 10 20 30 40 50 60 70 80 90

Hours to failure from August 24, 1977 (thousands) S252 SR-0690-11

Figure 4-6. Cumulative failure plot for motor-driven pumps, broadly defined failures to run.

4-17 NUREG/CR-5378
Component Failure Data

1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 Component

Mark No.

1-TDP

2-TDP

1-MDP-A

1-MDP-B

2-MDP-A

2-MDP-B

_ .................................................... ........................................... ........ ............................................................................................. ......... .....

_ ---.. ... -.... .. ........ ......... .... .... ..... ........ .... ..... ..-.......... .... .... ..... .... .. .... -. .... .... ..... .... ....... ..... .... .... ......... .... . ...... .... .... .... . ............................. . . 0 .... 0 .

.. Id 0 ... I .... ..... . ... I.... I.... I ....

0 10 20 30 40 50 60 70

Hours to failure from August 24, 1977 (thousands)

o Broadly defined failures to start

o Narrowly defined failures to start

Figure 4-7. Failure to start timeline for steam- and motor-driven pumps.

80 90

S252 SR-0690-01A

1978 1979 1980 1981 1982 1983 1984 1985 1986 1987

._

0

0)

.

0

(-)

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

l

n)

-

. . . . . . . . .

I I I I I 1 I -.

0

S

-5-

*

* -

S --

* --

* --

S --

9--

S --

8

- -- S

0 10 20 30 40 50 .60 70 80 90 ii. ii, I, I r p H I H I i i I I i a I I I I v

0 10 20 .30 40 50 60 70 BO 90

Hours to failure from August 24. 1977 (thousands) S252 SR-0890-12

Figure 4-8. Cumulative failure plot for motor-driven pumps, broadly defined failures to start.

NUREG/CR-5378 4-18
Component Failure Data

1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 5

to

co

0

C)

E

a)

E

C-,

4

3

2

1

I I I

S -'

S -

-- S

S

I I p I I I p

0

0 10 20 30 40 50 60 70

Hours to failure from August 24, 1977 (thousands)

80 90

S252 SR-0690-13

Figure 4-9. Cumulative failure plot for motor-driven pumps, narrowly defined failures to start.

Component Mark NW. 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987

I rI I I I I i I I i

1-MOV-A - ......................... .. . 0 . . . . . . . ........................................ ............... .........................-............._

1-MOV-E -...............-

1-MOV-C -.-----. o....................................

I-MOV-D . ...... .... 0. -

1-MOV-E .. ....... ._

1-MOV-f -.... I0-.... . -.. ..0.-o.-----.x

1-MOV-F(R)

2-MOV-A 4.......

2-I

2-

2-MOV-B ... ........ ..

2-MOV-C ......... .... ---------..-.... -----...-.

MOV-C(R) I..1- - --. °.-

2-MOV-D . . ............... - . ...... o. . .......---.-.... 0... ---.......--.. . .

2-MOV-E ......... .: .............-.o.-0.-

MOV-E(R) I . ............................. .. -

2-MOV-F -.-..............-----.--.......--. o..----------------..-..-....---..--o-o-.......

. . .I. . . . . . ., .I . . . . I 1,. . . .1, 1,. . . . I . . . I . . . . .1 ,. . .

0 10 20 30 40 50 60 70

Hours to failure from August 24, 1977 (thousands) O Broadly defined failures

* Narrowly defined failures K Narrowlydefined failures with component replacement

x Valve did not fail, it was moved to 1-MOV-E location end a new valve was installed

Figure 4-10. Plugging failure timeline for 3-in. MOVs (feed header isolation valves).

4-19 NI

80 90

5252 SR-690-03

JREG/CR-5378
Component Failure Data

1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 42

36

30

a)

0

-o

E

c

>

E

Figure

plugginE

- I I I I I I I I I - , _~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I "

0 I

0 -" 0"

04,,-0 1

.- ,-

0SI . ,,

I,- _ ,,~~~~~~~~~~~~~~~~~~~~~

24 a 0 ,---

18 ,o

12

0 lO 20 30 40 50 60 70 80 90

Hours to failure from August 24, 1977 (thousands) S2.52 SR-0690-14

4-11. Cumulative failure pl ot for 3-in. MOVs (feed header isolation valves), broadly defined

i failures. L7

1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 18 I

CD,

4--

0

-D

0)

co~

E

M

15

12

9

6

3

,-.

,, 0

,,0'

_~~~ ,, ~~ 

,, O

_ ,//

.~~~~

,,.~~~

0',,,,1....S..|....g...

,--I

- I . I U . . .

0 10 20 30 40 50 60 70 80 90

Hours to failure from August 24, 1977 (thousands) S252 SR-0690 t5

Figure 4-12. Cumulative failure plot for 3-in. MOVs (feed header isolation valves), narrowly defined

plugging failures.

NUREG/CR-5378 4-20
Component Failure Data

1978 1979 1980 1981 1982 1983 1984 1985 1986 1987

Component l1 1 I I I I I I

Mark No.

1-MOV-G -0.0 *-- -- --- -- - -o . o 2- - - -

1-MOY-HI

2-MOV

... ................................................................................................................................................ ........................... ... ........ a ...I.-0 ......................... ,@

................................ ............. .... ......... a -

.... 1;.I..I..I..I.... I....I .... I.... I....I . ...

2MOV-I(R)l

2-MOV-J

0 10 20 30 40 50 60 70

Hours to failure from August 24, 1977 (thousands)

o Broadly defined failures

* Narrowly defined failures u Narrowly defined failures with component replacement

Figure 4-13. Failure to stay closed timeline for 6-in. MOVs (cross-connect valves).

80 90

5252 SR-0690-02

1978 1979 1980 1981 1982 1983 1984 1985 1986 1987

U)

va

c3

4-

.,0

8

E

C

c

co

E

U

13

12

11

10

9

8

7

6

5

4

3

2

1

f%

I

-. '. . . I

-r' -0.

I I i I I I I I I .

0 ' -

*~ ~ ~ ~ ~ ~ ~ ~ ~

* ,,

* ,, _

*,

* * _

o -, ~: 'I, "

0

, -- ~I "

0 10 20 I .. .. 30 I .. .. I. . .. I . .. .I. .. . I. .. . I . 40 , 0 , 60 , 7 , 80 , 9 U/

0 10 20 30 40 50 60 70 80 90

Hours to failure from August 24, 1977 (thousands) S252 SR-0690-16

Figure 4-14. Cumulative failure plot for 6-in. MOVs (cross-connect valves), broadly defined failures to

stay closed.

4-21 NUREG/CR-5378
Component Failure Data

1978 1979 1980 1981 1982 1983 1984 1985 1986 1987

6 _ ,,

co

0

~ 4 0 -o,,

C.) 4

a 2 _ ., E

0 . '.. .. 1...1 ..1, I I...1..1..1,

0 10 20 30 40 50 60 70 80 90

Hours to failure from August 24, 1977 (thousands) S252 SRO069017

Figure 4-15. Cumulative failure plot for 6-in. MOVs (cross-connect valves), narrowly defined failures

to stay closed.

Component 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987

Mark No. , I I I I X I I

1-CV-A --- -a o.--

2-CV-B . -. a...

2-CV-E _-. . ... - -----o

2 -C V -A . .. .... ..... . .. .. ... .. ... .. .. .. ... .. . ..... ... ... ... ..... .......... ... ... ... ...... ................................ .. .......... ...--. .... . .a

2-C V -A .................................................................................................. o_................ 0................. .......................... .....................................

2-CV-C -.--- oxo--

0 10 20 30 40 50 60 70 80 90

Hours to failure from August 24, 1977 (thousands)

0 Broadly defined failures S252 SR-0690-04

Figure 4-16. Backflow failure timeline forpump discharge check valves. Following discussion with personnel from the power station, these events were all reinterpreted as non-failures. See Section 6.2.3.

NUREG/CR-5378 4-22
Component Failure Data

1978 1979 1980 1981 1982 1983 1984 1985 1986 1987

V,

0)

.0

E

a)

E

C-,

13

12

11

10

9

8

7

6

5

4

3

2

1

0

a a a a a I I --

-0 -

- C -

0 --

C --

-i

- 0

- 0

- 0

C

0

0

0

a a a a I aaa.I.,aa I I I I a

0 10 20 30 40 50 60 70

Hours to failure from August 24, 1977 (thousands)

80 90

S252 SR-01390-18

Figure 4-17. Cumulative failure plot for pump discharge check valves, broadly defined backflow leakage failures. Following discussion with personnel from the power station, these events were all reinterpreted

as non-failures. See Section 6.2.3.

r'nmnrannn-'- 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987

N

i~r_~ - .I I I I I I I i I I

lar No.

1 -T O P ..-.... ..... .. .... .... .. .. .. . ....... ....... -..... .. .......... .... .. .... ...... ... . ... .. ........ .. ...... ... .. ..... ... .. .. ...

22 T D ....................... ............................................... .............................................

P - A- -- ---M O - - - - - -- - -- - - - - -- ---...-..-- - -- - - - -- - - - -- -

1 - M O P - B .... .. ... ..... .. .. .. .. .......... ... ... .. ..... ..... .. ..... ... ... .... ... ... ... ..... ........ .I ... ... .... ... ..... ... .. .. .. ....

- M O P - A ..... .. ....... .... .. .... .. . ... ... ... ... .... ... ... .... .... ..... ..... ...... ....... .. ... ... .... .... .... ... .... .. .... .. ...... ..

.- D - ............................ ....................................................... I..................................

2

. 1. . . . . . . I., ..... ...... ..... . . .

0 10 20

Hours to

* Narrowly defined steam binding

30 40 50 60 70

failure from August 24. 1977 (thousands)

80 90

S252 SR-O69O-05

Figure 4-18. Steam binding failure timeline for the steam- and motor-driven pumps.

4-23 4-23 ~~~NUREG/CR-5378
Component Failure Data

1978 1979 1980 1981 1982 1983 1984 1985 1985 1987

3

en

co

0

-E

E

D

C)

E

U

2

I I I I I

0 -

- 7 0

0

0 10 20 30 40 50 60 70 80 90

Hours to failure from August 24, 1977 (thousands) S252 SR 0690.19

Figure 4-19. Cumulative failure plot for the steamdefined steam binding failures.

One overall observation about this graphical

display of the data is that the plots are basically

uninformative in the cases with few failure occurrences. In addition, it is difficult to test any component data pooling assumptions with this

graphical display. The statistical methods discussed in Section 5 are specifically designed to

analyze such sparse data and to test the

homogeneity of the (aggregated) sample of

component failures.

Many of the cumulative plots, such as

Figure 4-4, show little departure from a straight

line, indicating that the failure rate appears to be

roughly constant. This is consistent with the corresponding timelines, such as shown in the top

portion of Figure 4-3, where the failure times

appear to be uniformly scattered over time. Other

and motor-driven pumps, broadly and narrowly

cumulative plots, (Figures 4-6, 4-8, and 4-17)

show clustering of the failures. In these cases, the

timelines can help clarify the kind of clustering

that occurred. For example, Figure 4-7 shows that

the failures tended either to occur in pairs or to be

repaired in pairs. Figure 4-16 shows that three

valves were repaired for leakage almost simultaneously, while a different valve had recurrent

repairs. The clustering in Figures 4-16 and 4-17

was strong enough to motivate questioning of the

personnel at the power station, which led to a

reinterpretation of the data, as described in Section 6.2.3. There are no obvious cases of increasing failure rate, although Figures 4-6 and 4-15

may show decreasing failure rates. Sections 5

and 6 present analysis approaches that are more

sensitive and less subjective than simple inspection of these figures.

NUREG/CR-5378 4-24
5. STATISTICAL METHODS FOR ANALYZING

TIME-DEPENDENT FAILURES

The usual assumption in PRAs is that each

component has a constant failure rate A. This

leads to familiar formulas such as I - e-i' for

the probability of failure by time t, and AWt for

the approximate probability of failure within a

short time a t .The data are said to be generated

by a homogeneous Poisson process because the

number of failures occurring in any time t is a

Poisson random variable with parameter A(t).

One feature of this process is that the component

does not age. That is, the probability of failure in

a short interval of length At, assuming that the

component is operable immediately before the

start of the time interval, remains the same

ASt, whether the component is new or old. In an

investigation of aging, therefore, more complicated models must be introduced, and the familiar

formulas must be modified.

The development of such models and associated techniques of data analysis form the subject of this section. For this development, we step

away from the PWR context of the previous sections, and consider the statistical methods themselves. These methods are the basis for the

analysis in Sections 6 and 7. The topics are outlined here without proofs or many details. Details

about the theory, including the necessary proofs,

are given in Appendix A. Details about the

numerical methods for implementing the theory

are given by Atwood (1990). The most recent presentation of the statistical methods is Atwood

(1992). They are illustrated here by both real and

hypothetical examples. Unless indicated otherwise, all the figures are based on the data for plugging of 3-in. motor-operated valves (MOVs),

failure mode AFW-MOV-PG with the broad definition of failure, and on the exponential failure

rate model defined below.

5.1 Aging Models

The approaches used for inference about aging

assume that the failures of a component follow a

time-dependent Poisson process. That is,

* The occurrence of a failure in any time

- interval is independent of the presence or

absence of failures in other non-overlapping

time intervals.

* The probability of a failure in a short period

(t, t + A t) asymptotically approaches A(t)A t

as At - 0.

* The probability of more than one failure in a

short period (t, t + At) becomes negligible

compared to the probability of one failure as

A t- 0.

Therefore, the failure process has failure rate

A(t) . If A(t) is an increasing function of t, failures

tend to become more frequent as time goes on. A

statistical approach can be used to decide whether

A(t) is increasing.

When applying this model to investigate aging,

t represents the age of a component. It is assumed

that the form of A(t) is the same for all similar

components, depending only on the ages of the

components, not on the portion of the plant's history when the components were in service. This

in turn rests on an assumption that we make

explicit: The environments of the components

(ambient conditions, maintenance and operation

practices, and any degrading conditions) are constant throughout the life of the plant.

The general form assumed for A is

A(t) = Aoh(t; f)

The three specific models considered in this

report are

A(t) = A0e fl' (exponential failure rate)

A(t) = 20 (t/to)fi (Weibull failure rate)

A(t) = A2(l + Pt) (linear failure rate)

In each model, A, is a normalizing constant,

with units 1/time, and h(t;fl) is a dimensionless

5-1 NUREG/CR-5378
function of time t and a parameter P3. The value of

P determines the shape of the failure rate function. The failure rate is increasing if P > 0; it is

constant if/3 = 0; and it is decreasing if P3 < 0.

For the exponential and linear failure rate models, A, is the value of the failure rate at time t = 0.

In these two models, P3 has units 1/time, so that

the product Pt is dimensionless. For the Weibull

model, t0 is some normalizing time, and P3 is

dimensionless. The choice of to is arbitrary, but a

value somewhere in the range of observed values

of t is convenient. Then A, is the value of the failure rate at time to.

The analysis considers each of the three

models. There are no theoretical reasons for postulating one over the others. The data used in this

study, however, give much less satisfactory

results when the linear model is used than when

the exponential or Weibull model is used. With

the linear failure rate model, it is not uncommon

for the MLE for P to be infinite, for the uncertainties to be very large, or for the normal

approximation to be unusable. In the bestbehaved examples, the three models give similar

estimated failure rates in the region of the

observed failures. Therefore, all three models

were tried initially, but full results are reported

only for the exponential and Weibull models. The

results using these two models are similar and

would diverge only if an analyst tried to extrapolate far beyond the time period of the

observations.

Each of the three models has its own special

characteristics. Under the exponential model with

P > 0, the failure rate doubles every log(2)//3

hours. Under the linear model the failure rate

doubles from its initial value in I1/3 hours,

doubles again in the next 2//3 hours, and so forth.

Under the Weibull model, the failure rate at time

O either is zero (if P > 0) or is undefined (if

/ < 0). Therefore, it is not meaningful to speak of

the failure rate doubling from its initial value.

However, the failure rate doubles between times

t1 and t

2 whenever (t2/tO) = 21P. As has been

mentioned, the linear failure rate model is the

least tractable of the three models. This may be

surprising, but follows from the fact that both the

mathematical formulas and the calculated numbers in applications are best behaved when

logA(t) is linear in /3. This log-linearity is present

for the exponential and Weibull failure rate models, but not for the linear failure rate model. See

Appendix A for more detail on all three models.

Some other references for the use of the models

are as follows. Cox and Lewis (1966) give a

detailed treatment of the exponential failure rate

model when there is just one component. The

Weibull model has been explored by Crow (1974,

1982 and works cited there) and Donelson (1975)

and is reviewed by Engelhardt (1988). The Crow

and Donelson papers derive explicit formulas for

the MLEs when all the components are observed

from their time of installation. These formulas are

also mentioned in Appendix A, but are not useful

for the data of this report because very few of the

components are observed from their time of

installation. Most papers on the Weibull model

use /3-1 in the exponent, a slightly different parameterization from the one given in this section.

The parameterization with /3 in the exponent is

used here because it allows the same interpretation of P3 in all three models, with P3 =0 corresponding to a constant failure rate. The linear

model has been less widely used in the literature,

although it is considered by Salvia (1980) and

Vesely (1987).

It was assumed that each component's failure

rate is of the same form (exponential, Weibull, or

linear), and that the value of P is the same for all

the components. It was not assumed initially that

the components have the same value of A.,

although examination of the data for this report

always led to the conclusion that the values of A

may be treated as all the same.

5.2 Assumptions Regarding

Failure Data

Failure data for a component can arise in the

following ways:

NUREG/CR-5378 5-2
Statistical Methods

* A random number of failure occurrences in

a fixed observation period (time-censored

data)

Distinct components are assumed to fail independently of each other.

5.3 Inference Methods

* A fixed number of failure occurrences in a

random observation period (failurecensored data)

* More complicated ways.

Time-censored data arise if the component is

watched or plant records are examined for a fixed

time period. During that time, a random number

of failures occur. At each failure, the component

is repaired (made as good as it was just before the

failure) and returned to service.

Failure-censored data arise if the component is

repaired until a predetermined number of failures

have occurred. At that time the component is

removed from service and replaced by a new

component. Both of these types of failure data

result in tractable formulas for statistical

inference.

In reality, the decision to repair or replace a

component is based on a number of considerations, such as the availability and cost of replacement components, the severity of the particular

failure mode (including the difficulty, cost, and

potential safety hazards of repair), any recent history of failures, and other similar factors. These

considerations are difficult to express in a simple

mathematical model. Therefore, the data analysis

considered here assumes that the data for a component are generated in one of two simple ways:

if the final failure time is less than the observation

time, the data for the component are considered

time-censored; whereas, if the final failure time

equals the observation time because the component was replaced, then the data for the component are considered failure-censored.

It is never required that components be

observed starting from the moment of installation, only that each component be observed

starting at some known time, which may or may

not coincide with the component's installation.

The approach shown in Figure 5-1 is outlined

here. (Figure 5-1 expands a portion of Figure 2-2.) First, investigate the assumption that all

the components have the same value of P. If the

data show no strong evidence against this

assumption, accept that portion of the model.

Then test whether Pi = 0, that is, whether the failure rate is constant. If the data show evidence

(statistically significant at the selected level) of a

non-constant failure rate, continue with the analysis; otherwise, treat the failure rate as constant

and stop the analysis of this set of components.

When the failure rate appears to be nonconstant, investigate the assumption that it is of

the assumed form (exponential, Weibull, or

linear). If the data seem consistent with the

assumed form, investigate the assumption that all

the components have the same value of Ao If the

data show no strong evidence against this

assumption, accept that all the components have a

common A, as well as a common fl. Find the

MLEs of Pi and A,, and obtain the corresponding

MLE of A(t) at any t. Now investigate whether the

joint MLE of the two parameters (P,logA,,) may

be treated as having a normal distribution. If so,

the approximate normality of the MLE yields an

approximate confidence interval for A(t) .

The first four steps in Figure 5-1 involve statistical testing, that is, looking for evidence against

the default assumptions. As in all testing situations, when the data set is small the tests have low

power. That is, when there are few failures, there

will be no strong evidence of differences in fi

between the components, and no strong evidence

of aging, or of lack of fit to the model, or of differences in A0. Thus, small data sets typically give

no reason to discard the usual PRA model of a

constant failure rate that is the same for all similar

components.

Statistical inference is generally based on the

likelihood function, which depends on the data

5-3 NUREG/CR-5378
Statistical Methods

Consider Splitting Data

Stop

Try New Model

Consider Splitting Data

Use Conservative

Bound or New Model

LF91 0311

Figure 5-1. Approach for statistical analysis of one data set.

NUREG/CR-5378 5-4
Statistical Methods

and on the parameter(s). Inference for fi is of primary interest in a study of aging, because it is fi

that determines whether the failure rate is increasing. It is shown in Appendix A that the conditional likelihood can be used to perform inference

for fi, without assuming that the components necessarily have a common value of A, and without

estimating either the single Ao, or all the A),s. The

conditional likelihood is defined as the probability density of the non-replacement failure times,

given the failure counts for time-censored components and given the final failure times for

failure-censored components. As shown in

Appendix A, if the components are not assumed

necessarily to have the same value of A,, and if

the components are all time-censored, there are

strong theoretical grounds for using the conditional likelihood. In other cases, some information about fi is lost by using the conditional

likelihood.

Therefore, the first exploratory analysis used to

verify assumptions of the model is based on the

conditional likelihood. In this way the first four

steps in Figure 5-1 are carried out without assuming that there is a common A, Later, when both

parameters must be estimated simultaneously to

produce an estimate of the failure rate A(t) at various times t, the full likelihood is used.

All the computations were carried out by the

computer code PHAZE, documented by Atwood

(1990). The portions of the approach just outlined

are described in more detail in the next sections.

5.3.1 Inference for Pi.

Estimation and Confidence Intervals for fi.

Appendix A gives formulas for the conditional

likelihood of the non-replacement failure times,

conditional on the failure counts or the final

replacement failure times, whichever is random.

This conditional likelihood depends only on P,

not on the (possibly different) values of A, for the

components. Therefore, P can be estimated while

A, or the Aos are ignored. Based on L(P), the logarithm of the conditional likelihood, the MLE /3

is the value satisfying

(d/dP)L(3) = 0,

and can be found by numerical iteration.

Let P3 be the true value governing the failure

rate. Then (didf)L(/3) has expectation 0 and

variance denoted by 1(X5), calculated by formulas given in Appendix A. The distribution of

(didfl)L(/P) is asymptotically normal by the Central Limit Theorem. Therefore, an approximate

confidence interval for P3 is the set of all p% such

that

(d/d/3)L~i0o)/[lfi0) l /

2 (5-1)

lies in the interval (-c, c), where c is the appropriate number from a normal table; for example,

c = 1.645 yields an approximate 90% confidence

interval.

When the linear failure rate model is used with

a small data set, it is not uncommon for the MLE,

or at least for one end of the confidence interval,

to be infinite. This is one reason for preferring the

exponential or Weibull model.

Component Comparisons for P3. Consider

the possibility that the different components have

different values of /l . Let Pi denote the actual

value of P3 corresponding to the jth component. It

is estimated by using only the data from one

component.

A visual comparison of the components can be

made by plotting confidence intervals for the various /3j values, each interval based only on data

from a single component. Two examples are

shown in Figures 5-2 and 5-3. If the intervals

largely overlap, as they do in Figure 5-2, then the

data are consistent with the assumption that the Pi

values are all equal.

If one or more confidence intervals are clearly

shifted away from the others, as for components 8

and 9 in Figure 5-3, then those few components

are evidently aging at a different rate from the

others.

5-5 NUREG/CR-5378
Statistical Methods

C

0

£

0

0

0

I -MOV-A

1 -MOV-B i

1 -MOV-C

1 -MOV-D

1 -MOV-E

1 -MOV-F

1 -MOV-F(R)

2-MOV-A

2-MOV-B

2-MOV-C

2-MOV-C(R)

2-MOV-D

2-MOV-E

2-MOV-E(R)

2-MOV-F

OVERALL

-5.01E-4

I I

a a *-

* MLE(J)

n MLE(-])

* MLE

9E% Conf. Int.

0.60

0.11

0.96

0.063

0.80

0.23 u

0.64 O

0.58 U

0.55 =

1 0.30 '

0.41 ')

0.66

0.92

0.83

7.5 E-4

i " v

"H

-2.51E-4 0.0E0 2.5E-4

j3 (1 /h)

5.0E-4

Figure 5-2. Component comparisons for PB.

COMP1

COMP2

COMP3

COMP4

COMP5

0 COMP6

C

0

°. COMP7

E

o COMP8 0

COMP9

COMP10

OVERALL

i *E I

V

I .3

0.52

0.14

0.62

0.85

0

0.75 a

0

0.67 %

0.08 o

0.007

0.73

0.065

2.5E-4

v

* MLE()

* MLE(-J)

* MLE

- 95% Conf. Int.

I I I . I I

1-4

HN

* I -. - .

-5.0E-4 -2.5E-4 0

13(I1/h)

Figure 5-3. Component comparisons for ,B, based on hypothetical data.

NUREG/CR-5378 5-6
Statistical Methods

These anomalous components are called "outliers." At the end of this section we mention that

engineering judgment must play a decisive role in

the subsequent treatment of outliers. Of course,

no confidence interval for Pi can be calculated if

the component has no observed failures or if the

only observed failure resulted in replacement of

the component. This is why some of the components have no associated interval in Figures 5-2

and 5-3.

is used, as described in Section 6.1 of Appendix A.

When making multiple comparisons, as here

when a comparison is made for each component,

it is necessary to recognize that some values will

appear extreme just because of random scatter.

One way to account for this fact is with the

Bonferroni inequality, discussed in many texts

and by Alt ( 1982). In the present context, for any

number c it says that

A more quantitative comparison can be performed by considering

A A

Here P,/ is the MLE of /3g. based on the data from

only the jth component. The quantity /3 . is the

overall MLE of /3, assuming that the components

have a common ,8 and using all the data except

the data from component j. Because the estima- A A

tors /, and ,Bj are based on different data, they

are statistically independent, and therefore the

variance of their difference is the sum of their

variances. If in fact all the values of Pij are equal,

then the random variable Zj, defined as A A A A

will have mean 0 and variance 1. Here s.d.()

denotes the standard deviation of the quantity in

parentheses. A large observed absolute value of

Z4 gives evidence that ij is different from the

average fi for the components other than the jth.

The significance level for the component is the

probability that Z, would be as far from zero as

actually observed, if in fact all the components

have the same / . Figures 5-2 and 5-3 illustrate A A

this: if /, is far from /3_., compared to the length

of the confidence interval for fj, the significance

level, shown at the right edge of the figure, is

small. If the two MLEs are close, the significance

level is large. The significance is based on the

normal approximation. When component j has

only one non-replacement failure, the normal

approximation is clearly poor and a better method

P (at least one of k significance levels is < c) < •c.

The inequality is close to equality when kc is

small. Therefore, the overall significance level

for testing equality of the Pjs is the number of

components examined times the minimum significance level calculated for a component. A small

value of the attained overall significance level

(say 0.05 or smaller) shows that there is strong

evidence against the hypothesis that all the components have the same value of / . The overall

attained significance level is shown in each of

Figures 5-2 and 5-3.

The decision of what to do with an outlier

should rest on engineering understanding of the

possible causes of the anomalous behavior, not

merely on statistical calculations. The statistical

quantities may stimulate an engineer to discover a

previously unrecognized difference between the

outlying component and the others, justifying a

split of the data. In other cases, careful engineering consideration of the components may lead to

confidence that the components have no important differences, that the anomalous data just

resulted from randomness; in such cases, the data

would not be split.

Testing Whether /3 = 0. Suppose that, based

on the analysis described above, we are willing to

assume that the components have a common P.

To test the hypothesis /3 = 0, the test statistic (5-1 )

can be used with P, = 0, and the hypothesis

rejected if the test statistic is in an extreme tail of

the normal distribution. This is equivalent to

rejecting the hypothesis if 0 is not within the

confidence interval. The form of the test statistic

depends on the assumed model. When the

5-7 NUREG/CR-5378
Statistical Methods

exponential or linear failure rate model is

assumed, the test statistic (5-1) becomes

[=(ti- j)]I/(.nj rj 2 /12)'/ 2 (5-2)

where tij is the ith non-replacement failure of the

jth component, Yj is the midpoint of the observation period for the component, and the range rj is

the length of the observation period. If the statistic (5-2) is positive and far from zero, there is evidence of an increasing failure rate. This test was

first proposed by Laplace (Bartholomew 1955).

When the Weibull failure rate model is

assumed, statistic (5-1) takes a different form. In

the case when every component is observed starting from its installation time, the test statistic

becomes

2 [1 + log(tjlrj)]/(Znj)12

In the general case, the test statistic can be built

from formulas given in Appendix A.

Although each test statistic has been motivated

and derived based on a particular model, its

asymptotic null distribution, normal(O,1), holds

under the assumption that /3 = 0, that is, that A(t)

is constant. Therefore, either test is a valid test of

the hypothesis of constant failure rate, even if the

mathematical formula governing non-constant A

is not of the assumed form. The tests differ only in

their power to detect various alternatives to the

constant failure rate model.

As mentioned in Section 2.5.1, a confidence

interval provides information that a test result

does not. Therefore, in addition to performing the

test described here, it is helpful to find a confidence interval for /3 using statistic (5-1). This

gives a range of plausible values of /3 and shows

whether the uncertainty on P is small or large.

5.3.2 Investigating the Assumed Model

Form.

0-0 Plot. A Q-Q plot (see Snee and Pfeifer

1983) is a visual check of the correctness of an

assumed distributional form that can be used

in many contexts. In this context, let tj < . . . < t,

be the ordered observed ages at non-replacement

failures. They represent sample quantiles corresponding to probabilities p < .. . < p,, with pi set

to i/(n+1). For example, the median of the tis corresponds to pi = 0.50. Let F denote the assumed

cumulative distribution function, using estimated

values for any unknown parameters. This F is the

conditional distribution of the non-replacement

failure times, conditional on the failure counts

and the replacement times. The expression for an

estimate of F is given in Section 6.3 of Appendix A. The Q-Q plot is a plot of F-'(pi) versus ti,

for i from 1 to n. The name "quantile-quantile"

stems from the fact that F-'(pi) is the model-based

estimate of thepi-quantile, and tj is a nonparametric estimate of the same quantile. The plot is useful as a check of the assumed form of F, because

if the data really arise from F, the points of the

Q-Q plot fall approximately on a straight line.

Pronounced curvature or other departures from

straightness should arouse suspicions about the

correctness of the assumed form F. Figures 5-4

and 5-5 illustrate two Q-Q plots, with Figure 5-4

showing good fit to the assumed model and Figure 5-5 giving reason to question the model.

It is interesting to note that the cumulative failure plots given in Section 4.5 are equivalent to

Q-Q plots. In those plots, the observed failure

times are expressed as calendar hours from the

beginning of the observation period, not as age of

the components from their installation, but this is

only a trivial difference. The number of components under observation at any time is constant

because any component that is removed from service is immediately replaced by another. Therefore, if all the components have the same constant

failure rate, then the failures are generated by a

homogeneous Poisson process and the random

failure times are uniformly distributed. The

expected failure times, F-I(p1 ), are therefore

rl(n+l), 2r1(n+l), . . . , nr/(n+l), where r is the

length of the observation period in hours. The

plots of Section 4 have their points plotted on the

vertical axis at 1, 2, .. . , n, which differ from the

expected failure times only by a constant factor,

NUREG/CR-5378 5-8
Statistical Methods

125.56

U)

V)

U)

0

-c

0

0

-C

"0

0)

U

m 130.00 * . 0 ..

I.' 0.. * ..

0 " 9.I..

* ."

0.'

Jo

0

"'ia . 0 , 9

'. 0

-1, : " 0

_ * .~~~~B

a,

0 ~ ~ ~ ~ I

15.36

0 1

L

5.4

I I I j 11 flfi II I..I .. I t..... 11 ................. I I I....... 1

.8 122.53

Actual hours to failure (thousands) S252 SR-0690.21

Figure 5-4. Q-Q plot.

87.91

0

-C

0)

I0

0

C')

10

:3

C.m

CO

0

0

0

-a

0 . _.

0.06

; 92.21

'OF

..

'. " 0

a

0

0

*

0

0

a

0

0

S

I

.

a

S

a

.¢

4.24

0 I 11 I I I 1 11 HI 11 I _ . ..... . . = _ . _ _

Actual hours to failure (thousands) 89.39

S241 CA-0590-02

Figure 5-5. Q-Q plot, based on hypothetical data.

5-9 NUREG/CR-5378
Statistical Methods

rI(n+1). Therefore, except for a relabeling of the

vertical axis, the plots are Q-Q plots for investigating whether the components all have the same

constant failure rate. The reason why the diagonal

line was drawn from (0,0) to (rn+1) is that if the

vertical axis were relabeled as is usual on a Q-Q

plot, the diagonal line would go from (0,0) to (rfr).

Testing for the Form of A(t). The

Kolmogorov-Smirnov test, or some other similar

nonparametric goodness-of-fit test, can be used to

test whether data come from an assumed distribution. The data are the non-replacement failure

times. The assumed distribution is F, used before

for Q-Q plots and given in Section 6.3 of Appendix A. This test tends not to reject often enough;

in statistical terminology, the Type I error is

smaller than the nominal value. There are two

reasons for this: one is that the estimated , is used

to calculate F; the other is that when the components are observed over different time periods,

the data resemble a stratified sample rather than a

true random sample. The fact that the test does

not reject often enough is discussed in more detail

in Section 6.3 of Appendix A.

This test can also be used to test whether all the

components have the same constant failure rate,

paralleling the use of cumulative failure plots as

Q-Q plots. The hypothesis to be tested is that

/3 = 0 and that all components have the same

value of A,. The corresponding distribution F is

uniform, so no parameters need to be estimated.

Therefore, the Kolmogorov-Smirnov test is a

nonparametric exact test of the hypothesis that all

the components have the same constant failure

rate.

5.3.3 Inference for A,, Given P3. Suppose at

this point that the preceding analyses have led us

to accept that the components have a common P,

that P3 appears to be non-zero, and that the

assumed form of A(t) is consistent with the data.

It is now time to consider A,.

Estimation and Confidence Intervals for Aow

The average failure rate during a component's

observation period can be estimated as the

observed number of failures divided by the observation time. If Pf is known or assumed, a calculation back to time zero (or to time to for the

Weibull model) can be used to estimate A), This

is the conceptual basis for inference about At

given P3 . The formulas are given in Appendix A.

Component Comparisons for A, This diagnostic check is a parallel of the comparison

method for if. The value of P3 now is treated as A

known and equal to P3. We investigate whether A,

is the same for the jth component and for all the

components except the jth. The mathematical

methods are given in Section 6.2 of Appendix A.

They are not based on normal approximations.

Rather, they use the exact distributions of the failure counts (for time-censored data) and of the final

failure times (for failure-censored data).

The theory in Appendix A assumes that all

components have the same censoring type, either

time censoring or failure censoring. In a typical

data set, however, most of the components are

time censored, but a few are replaced upon some

failure and are therefore treated as failure censored. To analyze such data, when component] is

compared to all the components except thefth, all

components are treated as if they were censored

the way component] was. For example, if componentj was replaced at the time of its third failure,

then all the components, not merely component],

are treated as if they were failure censored for this

comparison. The reason is that the dominant

uncertainty typically comes from the individual

component with its few failures rather than from

the many other components with their many

failures.

These individual tests can be combined using

the Bonferroni inequality, just as when testing for

equality of the Ps. A useful picture is a plot of

confidence intervals for AO, each interval based

on data from a single component, as shown in

Figure 5-6. As was pointed out when we considered comparing components for P, engineering

judgment must be used in deciding how to treat

any outliers.

NUREG/CR-5378 5-10
Statistical Methods

C_

0

0.

ca

E

0

0

I -MOV-A

I -MOV-B

I -MOV-C

I -MOV-D

I -MOV-E

I -MOV-F

1 -MOV-F(R)

2-MOV-A

2-MOV-B

2-MOV-C

2-MOV-C(R)

2-MOV-D

2-MOV-E

2-MOV-E(R)

2-MOV-F

i , a -i

i, _

I, $ ..

-

_ .

I

i N -

A

I * K

0.18

0.18

0.18

0.094

1.00

0.12

0.63 C,

0.44 O

0.78 C'

0.97 !=

1.00 a

0.26 Ci

1.00

0.26

0.26

l

, ._

I i N

* MLE()

* MLE(-J)

* MLE

I-95% Cont. Int.

-

OVERALL

0.0E0

1.00

I I I I I I - I- L - , -1 -1 -

5.OE-5 1 .OE-4 1.5 E-4

Xo (1 /h)

Figure 5-6. Component comparisons for A,

5.3.4 Joint Inference for Both

Parameters and for the Failure

Rate.

Confidence Region for Both Parameters.

Suppose that a confidence interval for j3 has been

found. Then for each value of fi in the confidence

interval, a confidence interval for AO can be

.found. This leads to a confidence region for

(fA,), such as the one shown in Figure 5-7. If the

one-dimensional confidence intervals each have

confidence coefficient (1 - a), then the twodimensional region has approximate coefficient

(I - 2a). For example, 95% confidence intervals

for fi and A, yield an approximate 90% confidence region for (fi,2 0) Figure 5-7 is based on

the exponential failure rate model with A, plotted

on a logarithmic scale. The mathematical details

are given in Appendix A, as are some other plots

based on the exponential, Weibull, and linear

failure rate models.

Conservative Confidence Interval for the

Failure Rate. For any time t of interest, a conservative confidence interval for A(t) = A)Lh(t;fl) can

be constructed as follows. Find the maximum and

minimum values that A(t) attains as A, and fi

range over the two-dimensional confidence

region. These values are confidence bounds for

A(t), with the same confidence coefficient that the

confidence region has. The interval is conservative (possibly wider than necessary), because the

shape of the joint confidence region was not

designed to produce the shortest possible

intervals.

5.3.5 Joint Asymptotic Normality. Until

now, inference has been largely exploratory, not

estimating any quantities until the relevant

assumptions had been tested. Therefore fi was

estimated using the conditional likelihood to

eliminate the assumption of a common A2, and

when A, was eventually estimated, it was for each

possible assumed fi.

The viewpoint now changes. The model

assumptions have been investigated and

accepted. The goal is now to estimate the timedependent failure rate A(t) at various times t. For

5-11 NUREG/CR-5378
Statistical Methods

2.0E-5

1.5E-5

1.0E-5

_ 5.0E-6

O.OEO

-5.OE-6

-1 .OE-5. . .. . 5 6 7 8 9 2 3 4

1 0-5

Xo (1 /h)

Figure 5-7. 90% confidence region for (,A) based on conditional likelihood.

5 6 7 8

this, both parameters are estimated simultaneously using maximum likelihood, based on the

full (not conditional) likelihood. The formulas for

the MLEs are given in Appendix A. Confidence

regions are based on the joint asymptotic normality of the MLEs.

It turns out that the normal approximation is

usually better when the model is parameterized in

terms of logA, rather than A, This was discovered empirically, but has heuristic justifications:

for failure-censored data, the log transformation

replaces the scale parameter A, by a location

parameter; also, the log transformation helps

symmetrize the confidence intervals for A, for

both types of censoring. The MLE of (fl,logA,) is

asymptotically bivariate normal, and formulas for

the asymptotic variance-covariance matrix are

given in Appendix A.

Approximate Confidence Region for Both

Parameters. Based on asymptotic normality, the

confidence region for (p,logA,) is an ellipse.

Equivalently, the confidence region for (P,,AO) is

elliptical when AO is plotted on a logarithmic

scale.

To investigate whether the sample size is large

enough for the normal approximation to be adequate, we can compare the two confidence

regions for (8,AO), one calculated as in Section 5.3.;4 and the other being the confidence

ellipse just described. If the two regions have substantial overlap, the normal approximation

appears adequate. If the two regions are quite different, the normal approximation should not be

used. Figure 5-8 shows the ellipse overlaid on the

region of Figure 5-7, assuming the exponential

failure rate. Figure 5-9 shows the overlaid regions

based on the same data and a Weibull failure rate.

For the Weibull model, the normalizing time t0

was chosen in the middle of the observed failure

times. In the example shown, it happens that the

lower end of the 95% confidence limit for the

Weibull j

3 equals the theoretical lower limit of -1.

This value is unattainable, but it is the lower confidence limit, and it forces A, to equal zero.

NUREG/CR-5378 5-12
Statistical Methods

2.OE-5

1.5E-5

1.OE-5

~.5.OE-6

O.OEO

-5.OE-6

-1.OE-5 , ,,,.. . . . 5 6 7 8 9 2 3 4 5 6 7 8

1 0-5

Xo (1 h)

Figure 5-8. 90% confidence ellipse for (fi,,), based on joint asymptotic normality, overlaid on the

region of Figure 5-7.

1.5

1.0

0.5

0.0

-0.5

-1.0

OEO 1 E-5 2E-5 3E-5 4E-5 5E-5 6E-5

Xo (1/h)

Figure 5-9. 90% confidence regions for (, A,), based on Weibull failure rate model with to at the middle

of observation periods.

5-13 NUREG/CR-5378
Statistical Methods

Therefore A, cannot be plotted on a logarithmic

scale. In Figure 5-9, both parameters are plotted

on a linear scale, distorting the ellipse slightly.

Similar plots for the linear model are shown in

Figures 5-10 and 5-11. With the linear model,

time may be measured from an arbitrary origin,

and the two figures show the confidence regions

when time is measured from the component's

installation and when time is measured from a

point in the middle of the observation periods,

respectively.

In Figure 5-8, the overlap of the two regions is

quite good. The confidence ellipse is somewhat

smaller, which is to be expected because it uses

all the information in the full likelihood. In Figure 5-9 the overlap is also good, except when fi is

near the unattainable value of-l. In Figure 5-11

the overlap is not bad, while in Figure 5-10 the

overlap is at best fair. A problem in Figures 5-10

and 5- 1 1 is that the ellipse is truncated at the theoretical limits of fi. The conclusions from these

observations for this example are these: the normal approximation appears very good with the

exponential failure rate model, adequate with the

Weibull model, and inadequate (because of the

truncation) with the linear model.

Similar figures for different data sets are shown

in Figures 6-14 through 6-21 and in Appendix A.

Confidence Band for the Failure Rate.

Recall that the failure rate is assumed to be of the

form

A(t) = A)h(t;p)

so that a Taylor expansion yields.

logA(t) - logA(t) - log0A - 1ogAO

+ (8 - fi)(a/ap) log[h(t;fP)]

For the three specific models considered in this

report we have

A A

logA(t) - logA(t) = logA0

-logA 0 + (8 -f)t

(exponential failure rate),

A A

logA(t) - logA(t) = logA0 - logA0

+ (8 - fi) log(t/t0 )

(Weibull failure rate), and

lgA A

logA(t) - logl(t) - logA. - logAO

+ (8-f)t/(1 +fit)

(linear failure rate).

The first two equations are exact. The approximation for the linear failure rate model is adequate if (,B - fi)t/(1 + fit) is not too large. For this

case, let S denote the estimated standard deviation

of ,B . As a rule of thumb, the approximation may

be judged adequate if I 2St/(l + Alt)I is less than

0.1, and fair if the quantity is less than 0.5. The

possible need to keep t small may seem to restrict

the approach to times near the components' installations. In fact, this is not the case because the

time origin may be assigned arbitrarily. This is

allowed in the algebraic formulas, as discussed in

Appendix A. The meaning of Pi and k., depend on

which point is defined as t = 0.

Therefore, for any model and for a sufficiently

large sample, the MLE logA(t) is approximately

normal. Let D denote the derivative

(alaP) log[h(t;fi)]

The approximate mean of logA(t) is logA(t),

and the approximate variance equals

var(log A0) + D2var(fi) + 2Dcov(,B,log A)

NUREG/CR-5378 5-14
Statistical Methods

1 .5E-4

1 .OE-4

5.OE-5

O.OEO

-5.0E-5

3 4 5 6 7 2 3 4 5 6 7

10-5

Xo (1Ih)

Figure 5-10. 90% confidence regions for (f, A) based on linear failure rate model with time measured

from the component's installation.

1.5E-5 r

1.OE-5 F

5.OE-6IO.OEO F

-5.OE-6

-1.0E-5 L

2

I I I I I I I

3 4 5 6 7 8 9 1 0-4

vo (1/h)

Figure 5-11. 90% confidence regions for (f,A,), based on linear failure rate model with time measured

from the middle of observation periods.

5-15 NUREG/CR-5378
Statistical Methods

This yields an approximate confidence interval

for 1(t) for any t. Figure 5-12 shows examples of

the resulting bands for A(t), based on all three

failure rate models.

The band for the linear model (corresponding

to Figure 5-11) is plotted in Figure 5-12 for comparative purposes, even though the joint normal

approximation is poor. If the confidence band

were seriously advocated, it would be plotted

only for values of t satisfying

2St/(1 + 'it) I < 0.5,

A

where S is the estimated standard deviation of fi;

outside this range, the first-order Taylor approximation is inadequate. This restriction corresponds

to requiring t > 3.3E4 hour. If the upper and

lower bounds for the linear model are ignored

where t < 3.3E4 hour, the bands for the three

models look similar, except that the Weibull failure rate approaches 0 at time 0. Moreover, the

exponential band forms an envelope for the linear

band as the graph is extrapolated to the right.

These observations support the decision to report

only confidence limits based on the exponential

and Weibull models.

When the asymptotic normal approximation

seems unsuitable, an alternative is to use the conservative band for the failure rate (Section 5.3.4).

For the three models and the MOV data, the confidence bands based on asymptotic normality and

on conservative calculations are shown in Figures

5-13 through 5-15. In this example, the conservative bands are much wider than the bands based

on normality. The Weibull lower bound is not

shown because it is zero. With other data sets, the

bands based on conservative bounds and on

approximate normality differ less.

10-'

1 0-4

0

-L' ¢L

3

3

-c

AI 3L

2

I's

10-5 Li

10 _

7 a,

a -t-o

1 0-5

7 X-_

2.0E4 4.0E4 8.0E4 8.0E4 0.0E0 2.0E4

Age (h)

1.0E5 1.2E5 4.0E4 6.0E4 8.0E4 i.0E5 1.2E5

Age (h)

Figure 5-12. MLE and 90% confidence band

for A(t), based on joint asymptotic normality for

all three models.

Figure 5-13. MLEs and 90% confidence

bands for A(t), based on conservative calculations

and on asymptotic normality for exponential

model.

NUREG/CR-5378 5-16
Statistical Methods

1 0-4

8

4

1 0-4

6

S

a:

'a

LI.

8,

'a

2,V

LI.

3

2

4~~~I I/ I Wt

Conservalive

/ Y , _ - - Asymp. Norm.

I = I I ./ =

_| z .1 .~~~ I I I -

2

I 0-5 10-5

7 .

O.OEO 2.0E4

aa

4.0E4 6.0E4 8.0E4 1.OE5 1.2E5

Age (h)

O.OEO 2.0E4 4.CE4 6.0E4 8.0E4

Age (h)

1.0E5 1.2E5

Figure 5-14. MLEs and 90% confidence

bands for A(t), based on conservative calculations

and on asymptotic normality for Weibull model.

Figure 5-15. MLEs and 90% confidence

bands for AQ), based on conservative calculations

and on asymptotic normality for linear model.

5-17 NUREG/CR-5378
6. TIME-DEPENDENT FAILURE DATA ANALYSIS

The process used for analyzing the component

failure data is illustrated in Figure 6-1, which is

essentially the same as Figure 5-1 and expands a

portion of Figure 2-2. The individual steps to

perform the analysis are described in the following sections.

6.1 Preparation of the Input

The raw failure-time data sets developed as

described in Section 4 were the source of data for

this analysis. A FORTRAN computer program,

PHAZE (Atwood 1990), was written to carry out

the approach presented in Section 5. A data file

was a coded representation of the failure occurrence timeline that contained the data for each of

the individual components as a series of records.

In each record, the component name was stated

first, then the beginning and ending dates of

observation, followed by the specific failure

dates. If a component was replaced at the end of

its observation period, then the last date of failure

was given the trailing designator, R. Tables 6-1

and 6-2 present the formatted input failure data

for the broadly and narrowly defined failures,

respectively. These data sets correspond exactly

to the timelines of Section 4.

6.2 Statistical Screening

Analysis

6.2.1 Common P Test for All Components.

A single component of a nuclear safety system

will rarely incur enough failures, even over its

installed life, to analyze singly. Therefore, component failure histories must be combined, or

pooled, together. Pooling of component failure

data by type for use in quantification of PRAs has

become a casual, and sometimes untested, standard practice. Good practice for data analysis,

however, requires that data from the individual

components be examined and compared before

being pooled.

The pooling of component failure data is determined to be acceptable or not depending on the

significance level for the test of the equality of fi

(see Section 5.3.1). If the significance level were

less than 0.05 (meaning that there is less than a

5% chance that such disparate component data

could arise if fi is the same for all components),

then the pooling assumption would be rejected

and the significance levels and confidence interval plots associated with the component comparisons would be visually checked for indication

of an outlier. Engineering judgement would be

used to help decide whether to treat the outlier(s)

separately.

In this analysis of AFW system components,

the value of the significance level ranged from

0.15 to 1.00 for all but one set of components discussed separately below. The values are shown

in Tables 6-3 and 6-4. Therefore, the assumption

of equality of fi was accepted, and all components

passed this step in the screening process. Use of

the confidence interval plots for identification of

outliers was not necessary because all significance levels were greater than 0.05. However, to

help the reader visualize the process, a typical

confidence interval plot for fi is shown in

Figure 5-2. The plot is shown for the 3-in. MOVs,

the broad failure definition, and the failure mode

AFW-MOV-PG. The overall significance level is

0.83, indicating that equality of fi is a good

assumption.

One data set, AFW-MOV-FC for narrowly

defined failures, showed a significance level of

0.05 based on the linear model. However the

extreme component in this case had Pf= A, which

was based on one observed failure. Therefore, we

did not feel that there was enough information to

justify any decision. Because the exponential

model had allowed the components to be pooled,

the components were also pooled with the linear

model.

One disturbing feature shown in Tables 6-3 and

6-4 is the frequent inability of the linear model

and the occasional inability of the Weibull model

to provide an answer to the test for equality. This

is a result of the mathematics associated with the

6-1 NUREG/CR-5378
Time-Dependent Failure Data Analysis

MODEL ACTUAL

Reformatted the failure data (Section 4) to be consistent

with the input requirements for the statistical analysis

code.

Perform Statistical

Screening Analysis

Using the statistical analysis code PHAZE:

A. Checked the adequacy of the assumption that

the fi values for like components were

equal.

B. Tested for the presence of aging.

C. Checked the adequacy of the assumed form

of the aging model (exponential, Weibull,

linear) to predict the observed data.

D. Checked the adequacy of the assumption that

the Aovalues for like components exhibiting

aging were equal.

E. Found the MLEs of p and t,

F. Checked the adequacy of the bivariate normal

approximation for the construction of confidence

intervals.

Using the statistical analysis code:

Calculated the value of A(t) and its associated

confidence interval as a function of time.

LF91 0313

Figure 6-1. Process used to develop time-dependent failure rates.

NUREG/CR-5378 6-2
Time-Dependent Failure Data Analysis

Table 6-1. Formatted data used for the analysis of broadly defined failures.

Start and end Number

In service datesa of I of

Mark number datea observations failures Datea of failure

Failure Mode AFW-PMP-FR

1-TDP 721201 77082'

2-TDP 730501 77082'

1 871001 13 780111 780303 790204 790420 791223

800210 800429 820824 840111 850214

860509 860820 860907

4 871001 11 801118 820513 821207 830216 830314

830321 830429 830927 831013 840330

850819

Failure Mode AFW-PMP-FS

1-MDP-A2

1-MDP-B

2-MDP-A

2-MDP-B

1-MDP-A

1-MDP-B

2-MDP-A

2-MDP-B

721201

721201

730501

730501

721201

721201

730501

730501

770824 871001 5 810522 830611 820320 820330 86082

770824 871001 3 810522 860826 870522

770824 871001 4 790209 790910 831006 831012

770824 871001 4 790207 790910 800725 850712

Failure Mode AFW-PMP-FR

770824 871001 5 791223 810101 810114 810201 821014

770824 871001 2 810114 820309

770824 871001 2 790324 870331

770824 871001 2 810616 870807

Failure Mode AFW-MOV-PG

1-MOV-A

1-MOV-B

1-MOV-C

1-MOV-D

1-MOV-E

1-MOV-F

1-MOV-F(R)

2-MOV-A

-MOV-B

2-MOV-C

2-MOV-C(R)

721201

721201

721201

721201

721201

721201

820815

730501

730501

730501

830427

770824 871001

770824 871001

770824 871001

770824 871001

770824 800219

770824 820814

820815 871001

770824 871001

770824 871001

770824 830426

830427 871001

1

1

1

7

1

4

2

2

4

2

1

810618

780706

830423

830411 830520 840620 850814 860128

860131 861123

800219 Rb

780605 810325 811001 820814 Rb

821018 850213

781015 851029

800826 801104 821218 850620

811207 830426 Rb

870225

6-3 NUREG/CR-5378
Time-Dependent Failure Data Analysis

Table 6-1. (continued).

Start and end Number

In service datesa of of

Mark number datea observations failures Datea of failure

2-MOV-D

2-MOV-E

2-MOV-E(R)

2-MOV-F

730501 770824 871001 6 780407 800513 800602 821218 850620

860715

3 810611 830313 870219

0

730501

800323

730501

770824 871001

800323 871001

7710824 871001 6 800509 821218 830424 830819 840412 . . 850620

Failure Mode AFWV-PSF-FC-XCONN

1-MOV-G

1-MOV-H

2-MOV-I

2-MOV-I(R)

2-MOV-J

721201

721201

730501

800807

730501

770824 871001 3 810423 811212 850823

770824 871001 2 860211 860807

770824 800807 1 800807 Rb

800808 871001 1 830423

770824 871001 5 781006 781204 800814 810120 830423

Failure Mode AFW-CKV-OOC

1-CV-A

1-CV-B

1-CV-C

2-CV-A

2-CV-B

2-CV-C

721201

721201

721201

730501

730501

730501

770824 871001 3 830520 870214 870528

770824 871001 1 830525

770824 871001 1 830504

770824 871001 2 830117 831129

.770824 871001 0

770824 871001 5 830926 831119 840128 840313 841218

Failure Mode AFW-PMP-LK-STMBD

1-TDP

1-MDP-A

1-MDP-B

2-TDP

2-MDP-A

2-MDP-B

721201

721201

721201

730501

730501

730501

770824 871001

770824 871001

770824 871001

770824 871001

770824 871001

770824 871001

0

0

0

1 831120

0

1 831118

a. Note that date format is year, month, and day.

b. R indicates that the component was replaced at the date of the final failure.

c. Following discussion with personnel from the power station, the CV events were reinterpreted as non-failures,

and the data file was no longer used. See Section 6.2.3.

NUREG/CR-5378 6-4
'lime-Dependent Failure Data Analysis

Table 6-2. Formatted data used for the analysis of narrowly defined failures.

In service

Mark number datea

1-TDP

2-TDP

1-MDP-A

1-MDP-B

2-MDP-A

2-MDP-B

1-MDP-A

I -MDP-B

2-MDP-A

2-MDP-B

721201

730501

721201

721201

730501

730501

721201

721201

730501

730501

Start and end Number

datesa of of

observations failures Datea of fa

Failure Mode AFW-PMP-FR

770824 871001 2 780111 860907

770824 871001 3 801118 830216 830321

Failure Mode AFW-PMP-FS

770824 871001 2 820330 830611

770824 871001 0

770824 871001 1 831012

770824 871001 1 800725

Failure Mode AFW-PMP-FR

770824 871001 0

770824 871001 0

770824 871001 0

770824 871001 0

ailure

Failure Mode AFW-MOV-PG

1-MOV-A

1-MOV-B

1-MOV-C

1-MOV-D

1-MOV-E

1-MOV-F

1-MOV-F(R)

2-MOV-A

2-MOV-B

2-MOV-C

2-MOV-C(R)

721201

721201

721201

721201

721201

721201

820815

730501

730501

730501

830427

770824 871001

770824 871001

770824 871001

770824 871001

770824 800219

770824 820814

820815 871001

770824 871001

770824 871001

770824 830426

830427 871001

0

1

0

780706

4 830520 840620 850814 860128

1 800219 Rb

2 811001 820814 Rb

1 850213

2 781015 851029

1 801104

1 830426 Rb

0

6-5 NUREG/CR-5378
Time-Dependent Failure Data Analysis

Table 6-2. (continued).

Start and end Number

In service datesa of of

Mark number datea observations failures Datea of failure

2-MOV-D

2-MOV-E

2-MOV-E(R)

2-MOV-F

1-MOV-G

1-MOV-H

2-MOV-I

2-MOV-I(R)

2-MOV-J

1-TDP

1-MDP-A

1-MDP-B

2-TDP

2-MDP-A

2-MDP-B

730501

730501

800323

730501

721201

721201

730501

800807

730501

721201

721201

721201

730501

730501

730501

770824 871001

770824 871001

800323 871001

770824 871001

Failure Mode

770824 871001

770824 871001

770824 800807

800808 871001

770824 871001

Failure Mode

770824 871001

770824 871001

770824 871001

770824 871001

770824 871001

770824 871001

2 800602 860715

1 870219

0

1 800509

AFW-PSF-FC-XCONN

1 811212

1 860211

1 800807 Rb

0

3 781006 781204 810120

AFW-PMP-LK-STMBD

0

0

0

1

0

1

831120

831118

a. Note that date format is year, month, and day.

b. R indicates that the component was replaced at the date of the final failure.

NUREG/CR-5378 6-6
Table 6-3. Results of statistical analysis of the broadly defined failures.

Significance Significance

level for testing level for testing

equality of P. P = ob

Significance Significance

level for testing level for testing

adequacy of model equality of AOa

Conclusion at

confidence levels

Failure mode Exponential Weibull Linear Exponential Weibull Linear Exponential Weibull Linear Exponential Weibull Linear 0.05 0.40

AFW-PMP-FR-TDP 0.29 0.15 C 0.55 0.47 0.55 N/A N/A Not aging Not aging

AFW-PMP-FS-MDP 0.52 0.55 0.72 0.52 0.48 0.52 N/A N/A Not aging Not aging

AFW-PMP-FR-MDP 0.97 0.97 0.84 0.70 0.63 0.70 N/A N/A Not aging Not aging

AFW-MOV-PG 0.83 0.46 0.93 0.15 0.32 0.15 0.83 0.53 0.85 1.00 1.00 1.00 Not aging Aging

AFW-MOV-FC 0.25 0.56 0.80 0.65 0.56 0.65 N/A N/A Not aging Not aging

(ON AFW-PMP-LK-STMBD 0.88 0.78 -c 0.28 0.23 0.28 >0.20 >0.20 >0.20 1.00 1.00 1.00 Not aging Aging

AFW-CKV-OOd 1.00 1.00 -c 0.02 0.02 0.02 0.06 0.04 0.09 0.18 0.18 0.18 Aging Aging

a. A value of 0.05 or less indicates strong evidence that the components do not have the same aging rate, P, or the same initial failure rate, A,

b. A value of 0.05 or less indicates strong evidence that the components failures were not generated by a constant failure rate process. A value of 0.40 or less indicates weak statistical evidence of aging but is investigated as aging in order to be conservative for the sake of safety.

c. Could not be calculated for this case.

d. Following discussion with personnel from the power station, these events were all reinterpreted as non-failures, and the data file was no longer used. See Section 6.2.3.

z

C)

t.1

00

=i =1

0

n

11:3

n

:3Q.

n

:3

171

E.

r-

1

t

w

P

;11 

k<

4 - Cn
z

c)rri

0

Po(!A

00

Table 6-4. Results of statistical analysis of the narrowly defined

Significance Significance

level for testing level for testin

equality of /3 b P = Oc

Significance Significance

g level for testing level for testing

adequacy of model equality of Aob

Conclusion at

confidence levels

El

t:)

0a.

CD

Pz

1I-

_.

az

Failure modea Exponential Weibull Linear Exponential Weibull Linear Exponential Weibull Linear Exponential Weibull Linear 0.05 0.40

AFW-PMP-FR-TDP 0.98 0.69 _d 0.59 0.59 0.59 N/A N/A Not aging Not aging

AFW-PMP-FS-MDP 1.00 1.00 0.34 0.55 0.45 0.55 N/A N/A Not aging Not aging

AFW-MOV-PG 0.84 0.85 0.72 0.24 0.25 0.24 >0.20 >0.20 >0.20 0.94 0.98 0.95 Not aging Aging

AFW-MOV-FC 0.13 _ d 0.05 0.85 0.85 0.85 N/A N/A Not aging Not aging

AFW-PMP-LK-STMBD 0.88 0.78 _d 0.28 0.23 0.28 >0.20 >0.20 >0.20 1.00 1.00 1.00 Not aging Aging

00

a. There were no narrowly defined failures for modes AFW-CKV-OO and AFW-PMP-FR-MDP. The narrowly and broadly defined failures for mode AFW-PMP-LK-STMBD were identical.

b. A vatue of 0.05 or less indicates strong evidence that the components do not have the same aging rate, P, or the same initial failure rate, A,

c. A value of 0.05 or less indicates strong evidence that the components failures were not generated by a constant failure rate process. A value of 0.40 or less indicates weak statistical evidence of aging

but is investigated as aging in order to be conservative for the sake of safety.

d. Could not be calculated for this case.
Time-Dependent Failure Data Analysis

models. In mathematical terms, they are not wellbehaved. While this is inconvenient, it does not

prevent the use of the models for other sets of

data, and with the support of the exponential

model, does not necessarily prevent the further

application of the Weibull and linear models. For

example, even though the linear model was incapable of providing a result for the case of the narrowly defined, pump steam-binding failure, both

the exponential and Weibull models indicated

acceptance of the equality of the Ps. Therefore,

the linear model continued to be applied to this

case as though the set of components had shown

equality using this model.

6.2.2 Aging Test. After the test for common fi,

the next task was to test for statistically significant aging. The significance level of the null

hypothesis, fi = 0, was checked for all sets of

components passing the first screening test.

Recall that the null hypothesis assumed a homogeneous Poisson process, implying constant failure rate. The test for significance must identify

any statistically significant evidence to the contrary. Therefore, evidence of an increasing rate of

failure, assumed in this report to be aging, can be

modeled by a positive Pi.

The approach for analyzing data for the presence of aging used two significance levels, 0.05

and 0.40 (Section 2.5). Traditional statistics

would use only the 0.05 value for testing statistical significance of aging. However, for a safety

analysis it can be argued that the relaxation of this

convention is conservative and, therefore, justified. The result is that components are identified

in which there is less confidence that the aging

trend is present. Frequently, these components

have a large uncertainty, indicating the need for

more data to make any confident statement on the

failure trends. The result of including components

to the 0.40 significance level is that more aging,

and thus more risk, is predicted than may actually

be present. This is generally conservative and,

therefore, acceptable.

The significance level values for fi 0 ranged

from 0.85 to 0.02, as shown in Tables 6-3 and 6-4.

One broadly defined failure set and no narrowly

defined failure sets exhibited significance levels

less than 0.05. The broadly defined failure set was

the pump discharge header check valve backflow

failure (AFW-CKV-OO). After the check valve

maintenance records were reinterpreted, as

described below, no data sets showed aging at a

significance level less than 0.05. Two additional

sets exhibited aging at the 0.40 level of significance for both the broadly and narrowly defined

failures. These two sets were the 3-in. MOV plugging failure (AFW-MOV-PG) and pump steam

binding failure (AFW-PMP-LK-STMBD).

6.2.3 Adequacy Check of the Assumed

Form of the Aging Model. Initially the five

component failure data sets that showed indication of aging at either the 0.05 or 0.40 significance level were tested to see if any of the three

assumed model forms provided an adequate

description of the data. As in the previous screening, 0.05 was used to test the assumption

(Section 5.3.2). The hypothesized model form

would be accepted if the failure times predicted

by the model were close to the actual failure

times. For all the data sets except one, the level of

significance ranged from 0.20 to 0.85, as shown

in Tables 6-3 and 6-4. For backflow of the check

valves, the significance level was from 0.04 to

0.09, depending on the assumed model.

The Q-Q plots (Section 5.3.2) for the five data

sets for each of the three models (shown in Figures 6-2 to 6-13) are consistent with the significance levels shown in Tables 6-3 and 6-4. The

plots indicate that some clustering of data

occurred, but except for backflow of the check

valves, the plots show no gross deviations from

the 45-degree line that represents perfect agreement between actual and predicted failure times.

For backflow of the check valves (failure mode

AFW-CKV-OO), based on the broad definition of

failures, clustering of the failure dates made the

fit to any of the models marginal at best. The clustering of failure times is shown in the timeline

(Figure 4-16), in the cumulative failure plot (Figure 4-17), and in the corresponding Q-Q plots

(Figures 6-2 through 6-4). Several possible

*causes of this clustering were conjectured, but the

6-9 NUREG/CR-5378
Time-Dependent Failure Data Analysis

125.04

I] 130.00

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-o

C

C)

U,

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s

0

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C,

CO

coU

CC

0

*

a

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--S

, S

S

58.13 L

L:1 I ""I I I 1

85.16 127.00

Actual hours to failure (thousands)

0

S252 Sn-0890-27

Figure 6-2. Q-Q plot for pump discharge check valves, broadly defined back leakage failures, exponential model, based on failures before the data were reinterpreted.

130.00

25.04 _ -I

Li,

s'a

a

co

V

D

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0

2

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0

is

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U

* , ,..

. .

.I

I

*

63.98 L

0

I gill I I I

85.16 127.00

Actual hours to failure (thousands) S252 SR-0890-28

Figure 6-3. Q-Q plot for pump discharge check valves, broadly defined back leakage failures, Weibull

model, based on failures before the data were reinterpreted.

NUREG/CR-5378 6-10
124.41

Time-Dependent Failure Data Analysis

:130.00 .0

0~~~ a

0 ~ ~ /

* 0 ,.

*

*

S..

e0

0R

C~

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ID

co

V)

0

U)

0

.0

0,

.Cl

IU

nl

U62.87 L .

L: I III I I I

0 85.16 127.00

Actual hours to failure (thousands)

Figure 6-4. Q-Q plot for pump discharge check valves, broadly defined back

model, based on failures before the data were reinterpreted.

S252 SR-0690-29

leakage failures, linear

125.56

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U)

C

coC)

0

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a .

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,.'*

15.36 L

L' L

0 15.4

l I I 11 III till 111 It I I I II I Il

8 122.53

Actual hours to failure (thousands) 5252 SR-0590-21

Figure 6-5. Q-Q plot for 3-in. MOVs (header isolation valves), broadly defined plugging failures,

exponential model

6-11 NUREG/CR-5378
Time-Dependent Failure Data Analysis

125.11

U,

a,

u,

0

a)

D

0

WE

0

2

10

2

2

0

a,

Uc

0

CD

;l 130.00

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I, Ia

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#. ' * ,.R'-

S

0 11-

I~~~~~~

0

16.71

- a.

1:." I I I I pi I Ill 11 i 11 1 I I I 1 111 11

0 15.48 122.53

Actual hours to failure (thousands) S252 SR-090-22

Figure 6-6. Q-Q plot for 3-in. MOVs (header isolation valves), broadly defined plugging failures,

Weibull model.

125.50

U,

_0

C

0

-!E

0

.C

;Aq 130.00 4.,

f,.

4S..

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S.1

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16.54

r S~~~01

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L:'' L I I

O'S

.0

I M

.'0

..0

0

P

0 15.48

111 I1I 111 I I I I1I I 1

122.53

Actual hours to failure (thousands) S252 SR-O890-23

Figure 6-7. Q-Q plot for 3-in. MOVs (header isolation valves), broadly defined plugging failures, linear

model.

NUREG/CR-5378 6-12
Time-Dependent Failure Data Analysis

122.89

] 130.00

q,.

,. a

* 0

a

0 0

. a

C3

CO

co

V)

0

._

2

.2o

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0 .

0 "

0 .

.- '

I

39.29 a

E ~ I ~ 1 lI I i il I

0 21.92 121.02

Actual hours to failure (thousands) S252 SR-0690-24

)-Q plot for 3-in. MOVs (header isolation valves), narrowly defined plugging failures,

lel.

Figure 6-8. C

exponential mod

1;i 130.00

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C

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.''A

39.77 0

." I ii " f I I I i I I

0 21.92 121.02

Actual hours to failure (thousands) S252 SR-069O-25

Figure 6-9. Q-Q plot for 3-in. MOVs (header isolation valves), narrowly defined plugging failures,

Weibull model.

6-13 NUREG/CR-5378
Time-Dependent Failure Data Analysis

122.67

C

Cu3

V)

0

:2

:2

0

1)

U

Ad, 13 0.0 0

G.

, a

0

D ,0

. 0

0..'

,. 0 

0

a

. 0 

A

39.46 0

0 21.92 121.02

Actual hours to failure (thousands) S252 SR-0690-26

Figure 6-10. Q-Q plot for 3-in. MOVs (header isolation valves), narrowly defined plugging failures,

linear model.

§1130.00

_ 108.41 - v)

'a

a

coTo V)

0

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0

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m,

Mo

to

CU

Uo

S

. S

0 92.48,92.53

Actual hours to failure (thousands) S252 SR-0G90-30

Figure 6-11. Q-Q plot for either broadly or narrowly defined pump steam binding failures, exponential

model.

NUREG/CR-5378 6-14
Time-Dependent Failure Data Analysis

. 130.00

0~~~~~~~~

U)

C

0

is

2!

0

IU

co

U110.24 -

87.67 -

I

C,, 0 92.48,92.53

Actual hours to failure (thousands) S252 SR-0890-31

Figure 6-12. Q-Q plot for either broadly or narrowly defined pump steam binding failures, Weibull

model.

-7i 130.00

110.09 r

C~

Cuco

V) L

o 88.93

._i

0

CO

0

co

U

Cu

.

E '.

0 92.48.92.53

Actual hours to failure (thousands) S252 SR-0690-32

Figure 6-13. Q-Q plot for either broadly or narrowly defined pump steam binding failures, linear model.

6-15 NUREG/CR-5378
Time-Dependent Failure Data Analysis

true causes could not be established from the

available maintenance records.

Because the lack of fit was at the borderline

between acceptance and rejection (at the 0.05 significance level), the data were analyzed based on

the assumed aging models. This decision was

influenced by two considerations:

* Modeling the failure rate as increasing is

conservative.

* Failures that cluster are not specifically a

problem for aging models. They are a problem for any data analysis that is typically

done for a PRA. In particular, the usual

analysis assumes that the failures are independent with a constant failure rate; clustering violates the independence assumption.

Thus, the lack of fit is present whether the

check valves are treated as aging or not.

If this failure mode had had little effect on the

risk, the issue would have been dropped. However, as discussed in Section 7, backflow of check

valves turned out to be the dominant contributor

to risk. Therefore, when review comments on a

draft were received from personnel at the power

station, we inquired specifically about the leakage

failures.

The inquiry revealed three nearly simultaneous

repairs of the pump discharge check valves at

Unit 1 in May 1983 (see Figure 4-16 and

Table 6-1). These repairs were made as a

response to notification that leakage of check

valves might be a generic, industry-wide problem. Indeed, some leakage was found, but the

time of the onset of the leakage in each valve is

unknown. The recurrent repairs of valve 2-CV-C

were unsuccessful attempts to stop leakage that

came from a different source, a failed orifice on a

recirculation line, not through the check valve at

all.

The most important discovery, however, was

that none of the leakage events was severe enough

to cause failure mode AFW-CKV-OO, backflow

through the pump discharge check valve. (Recall

that a maintenance record was classified as a failure under the broad definition if it was considered

to possibly describe a failure, although it might

only describe a problem that was fixed before the

component had to be removed from service).

Based on this additional knowledge, all the leakage events were reclassified as non-failures for

the failure mode AFW-CKV-OO. The events

were retained, however, for the steam binding

failure mode (AFW-PMP-LK-STMBD) because

minimal leakage is needed for that failure mode.

Therefore, the reinterpretation of the raw data

eliminated AFW-CKV-OO as a failure mode

affected by aging and left the calculations for

AFW-PMP-LK-STMBD unchanged. After the

reinterpretation, there was no problem with lack

of fit to any of the aging models.

6.2.4 Common A, Test for All Components

Exhibiting Aging. Next, the five component

failure data sets that were determined to show

time-dependent trends were analyzed to test the

adequacy of the assumption that the data should

be pooled based on equality of A, (Section 5.3.3).

As for the equality test for A, if the significance

level had been less than 0.05, then the significance levels and confidence interval plots associated with the component comparisons would

have been visually checked for indication of an

outlier, and engineering judgement would have

been used to help decide whether to split the data.

The assumption of pooling was found acceptable

for all five data sets at significance levels ranging

from 0.18 to 1.00, as shown in Tables 6-3 and 6-4.

The confidence interval plot for A, for the 3-in.

MOV plugging failure is shown in Figure 5-6.

6.2.5 MLE for (/3A). The MLEs for j3 and A,

were found for the five component failure data

sets that passed the screening to this point (Section 5.3.5). The results are shown by data set and

assumed model in Table 6-5.

6.2.6 Check of the Normal Approximation

for Distribution of MLE. The MLE is a point

estimate only. To get a confidence band for A(), it

was assumed that the MLE (#,'logA,) had a

bivariate normal distribution (Section 5.3.5). This

assumption resulted in an approximately

NUREG/CR-5378 6-16
Table 6-5. MLEs for /3 and A, by aging model and failure definition.

Aa > b

Failure mode Exponential Weibullc Linearc Exponential Weibullc Linear'

AFW-MOV-PG

AFW-PMP-LK-STMBD

AFW-CKV-OOd

7.47E - 06

1.34E-05

2.34E -05

0.3

1.5(

2.3'

Broadly Defined Failures

12 7.66E-06

9 2.17E-05

7 2.17E-05

Narrowly Defined Failures

2.18E-05

1.16E -06

2.77E -06

3.97E-05

3.60E-06

1.96E-05

3.86E -05

3.76E -06

2.26E - 05

AFW-MOV-PG 9.07E-06 0.603 9.79E-06 7.92E-06 1.64E-05 1.60E - 05

AFW-PMP-LK-STMBD 1.34E -05 1.59 2.17E -05 1. 16E -06 3.6E -06 3.76E -06

a. Units are 1/hour under the exponential and linear models, and dimensionless under the Weibull model.

b. Units are 1/hour.

c. For the linear model the data were centered, that is, all times were measured from a point near the middle of the observation period (tmid. defined in Section 4.3

of Appendix A.) For the Weibull model, the normalizing time t, was set equal to this same tmid.

d. Following discussion with personnel from the power station, the events with leakage of check valves were all reinterpreted as non-failures. and the failure mode

AFW-CKV-OO was no longer regarded as affected by aging. See Section 6.2.3.

z

C'

00
Time-Dependent Failure Data Analysis

lognormal distribution for A(t), which could then

be used for PRA input. To check the adequacy of

the bivariate normal assumption, a graphical

comparison was made of the conservatively estimated confidence region and the confidence

region based on the asymptotic normality

assumption. The comparisons are shown in

Figures 5-8 through 5-11 for 3-in. MOVs (AFWMOV-PG) with broadly defined failures and in

Figures 6-14 to 6-21 for the other data sets. No

figure is shown for the linear model when id was

at the end of the allowed range; in those cases

asymptotic normality did not hold. For all the failure sets, the assumption of approximate normality

appeared good enough when the exponential or

Weibull model was used. Approximate normality

was clearly false with the linear model; much

larger data sets would have been needed before

the asymptotic normal distribution was

approached.

For pump steam binding under the Weibull

model (Figure 6-21), the confidence ellipse was

truncated at the minimum allowed value of

is = -1. This indicated that the normal approximation was not very good. The difficulty does not

affect the upper bound for future A(t), however,

and therefore was ignored.

6.3 Calculation of 2(t) as a

Function of Time

With the screening completed, the value of A(t)

and its associated confidence interval were calculated as a function of time for the five data sets

showing a time-dependent behavior (Section 5.3.5). The point estimate of A(t) was calculated for all three models to allow comparison,

but the confidence intervals were calculated for

only the exponential and Weibull models because

of the failure of the asymptotic normality

assumption for the linear model. The results of

the calculations are shown in Tables 6-6 to 6-8.

The year 1987 in these tables represents the

value of A at the "present" time, the time at which

the data collection ceased. The years 1988, 1989,

and 1990 represent the "future" and show the predicted value of A based on the demonstrated

trend. No values of A were calculated further in

the future because the unknown, but significant,

effects of human interaction (mitigation) can

drastically change the rate of aging.

6.4 Case Study Problem

Specifications

The results of all raw failure data collection,

development, and analysis were used in the calculation of time-dependent plant risk. Numerous

cases were analyzed in this work. Each case was

a combination of the definition of failure (broad

or narrow), the significance level at which the

no-aging assumption was rejected (0.40 or 0.05),

and the model employed (exponential, Weibull,

or linear). Remember that only point estimates

were possible for the linear model because the

confidence interval on the MLE could not be calculated. The failure sets analyzed as a result of the

different combinations are shown in Table 6-9.

NUREG/CR-5378 6-18
Time-Dependent Failure Data Analysis

5.5E-5 -

4.5 E-5 -

3.5E-5

1. 2.5 E-5

1 .5E-5

5.0 E-6

-5.OE-6 _

10-7

I I I I I. ,...

2 3 4 2 3 4 2 3

1 0-6 1 0-5

Xo (1 /h)

Figure 6-14. 90% confidence regions for (fiA,,) for pump discharge check valves, broadly defined back

leakage failures, exponential model, based on failures before the data were reinterpreted.

5.5 r

4.5

3.5

o- 2.5

1.5

0.5

-0.5

6 7 8 9 2 3 4

10-5

Xo (1 /h)

Figure 6-15. 90% confidence regions for (f,B,) for pump discharge check valves, broadly defined back

leakage failures, YWeibull model, based on failures before the data were reinterpreted.

6-19 NUREG/CR-5378
Time-Dependent Failure Data Analysis

3.0E-5

2.0E-5

1 .OE-5

O.OEO F

-1 .OE-5

-2.OE-5

2 3 4 5 6 2 3 4 5 6

10-6 10-5

Xo (1 /h)

Figure 6-16. 90% confidence regions for (PLAo) for 3-in. MOVs (header isolation valves), narrowly

defined plugging failures, exponential model.

2.0

1.5

1.0

a- 0.5

0.0

-0.5

-1.0

0.0 EO 5.OE-6 1.0E-5 1.5E-5

X0 (1/h)

2.OE-5 2.5E-5 3.OE-5

Figure 6-17. 90% confidence regions for (,B) for 3-in. MOVs (header isolation

defined plugging failures, Weibull model.

valves), narrowly

NUREG/CR-5378 6-20 62
Time-Dependent Failure Data Analysis

2.5E-4

2.0E-4

1 .5E-4

- 1.OE-4

5.OE-5

O.OEO

-5.OE-5 I . . . . ..... . . ...

2 3 4 2 3 4 2 3 4

10-7 10-6 10-5

Xo (1 /h)

Figure 6-18. 90% confidence regions for (filo) for 3-in. MOVs (header isolation valves), narrowly

defined plugging failures, linear model, time measured from component's installation.

1.5E-5 r

1.OE-5 F

5.0E-6

O.OEO

-5.0E-6

-1 .OE-5

-1.5 E-5

-2.OE-5 I I I P

7 8 9 2 3

I 0-5

Xo (1/h)

Figure 6-19. 90% confidence regions for (#,A,) for 3-in. MOVs (header isolation valves), narrowly

defined plugging failures, linear model, time measured from middle of observation periods.

6-21 NUREG/CR-5378
Time-Dependent Failure Data Analysis

7.5 E-5

5.0E-5

M

C-)

2.5E-5

O.OEO

-2.5 E-5 [

-5.OE-5 '11111 2 I2 2 2 2 2

1 0-9 2 1 0-8 2 1 07 2 1 0-6 1 0-5 2 1 0-42

Xo (1/h)

Figure 6-20. 90% confidence regions for (MA,) for pump steam binding, broadly or narrowly defined

failures, exponential model.

7.5

6.0

4.5

<m 3.0

1.5

0.0 F

. . . . . . I -1.5 L

1 0-'7

2 3 4 5 2 3 4 5

10-6

2,o (1/h)

1 0-5

Figure 6-21. 90% confidence regions for (f,A,) for pump steam binding, broadly or narrowly defined

failures, Weibull model.

NUREG/CR-5378 6-22
Table 6-6. MLEs of 1(t) and associated confidence intervals by failure mode definition for the exponential model.

A(t) and confidence interval

Failure mode 1987 1988 1989 1990

Broadly Defined Failures

AFW-MOV-PG

AFW-PMP-LK-STMBD

AFW-CKV-OOa

5.81E -05

3.50E-05 to 9.64E-05

6.70E - 06

7.66E-07 to 5.86E-05

6.20E-05

3.50E-05 to I.IOE-04

7.53E-06

6.03E -07 to 9.42E -05

7.08E-05

2.65E-05 to 1.89E-04

6.62E -05

3.50E-05

8.47E-06

4.67E-07

8.69E-05

2.77E -05

to I.26E-04

to 1.53E-04

to 2.72E-04

7.07E -05

3.48E-05

9.52E-06

3.59E-07

1.07E - 04

2.89E - 05

to I.44E-04

to 2.53E-04

to 3.94E-04

5.77E-05

2.52E-05 to 1.32E-04

Narrowly Defined Failures

AFW-MOV-PG

AFW-PMP-LK-STMBD

2.61E-05

1.20E-05 to 5.67E-05

6.70E -06

7.66E-07 to 5.86E-05

2.83E-05 3.06E-05

1.18E-05 to 6.80E-05 1.15E-05 to 8.18E-05

to 1.53E-04

3.32E-05

1.12E-05

9.52E -06

3.59E - 07

to 9.86E-05

to 2.53E-04

7.53E-06

6.03E-07 to 9.42E-05

8.47E-06

4.67E-07 la

a. Following discussion with personnel from the power station, the events with backflow of check valves were all reinterpreted as non-failures, and the failure mode

AFW-CKV-OO was no longer regarded as affected by aging. (See Section 6.2.3.) Therefore, A(t) was taken to be the constant value given in the NUREG- I150 PRA.

in

-o

00
C.)

O~

00

Table 6-7. MLEs of A(t) and associated confidence intervals by failure mode definition for the Weibull model.

A(t) and confidence interval

Failure mode 1987 1988 1989 1990

-3

9'

0

0

CD

C).

O'

III

E

C

8

t: p

p

EL

,--e_

14. W

Broadly Defined Failures

AFW-MOV-PG

AFW-PMP-LK-STMBD

AFW-CKV-OOa

4.76E-05

3.21E-05

7.37E-06

1. 12E -06

5.68E-05

2.70E-05

to 7.07E-05

to 4.83E-05

to 1.20E-04

4.86E-05

3.20E-05 to 7.39E-05

8.17E -06

9.99E-07 to 6.67E-05

4.95E -05

3.18E-05

8.99E -06

8.87E-07

7.64E-05

2.97E -05

to 7.71E-05

to 9.12E-05

to 1.96E-04

5.04E-05

3.17E-05

9.85E-06

7.87E-07

8.75E-05

3.09E -05

to 8.03E-05

to 1.23E-04

to 2.47E-04 0"

6.62E -05

2.84E -05 to 1.54E-04

Narrowly Defined Failures

AFW-MOV-PG

AFW-PMP-LK-STMBD

2.34E -05

1.25E-05

7.37E-06

1. 12E - 06

to 4.40E -05

to 4.83E-05

2.34E-05AE-0 2.44E -05

1.24E-05

8.17E-06

9.99E -07

to 4.79E -05

to 6.67E-05

2.53E -05

1.23E-05

8.99E -06

8.87E -07

to 5.19E-05

to 9.12E-05

2.62E-05

1.22E-05

9.85E-06

7.87E-07

to 5.60E-05

to 1.23E-04

a. Following discussion with personnel from the power station, the events with backflow of check valves were all reinterpreted as non-failures, and the failure mode

AFW-CKV-OO was no longer regarded as affected by aging (Section 6.2.3). Therefore, A(t) was taken to be the constant value given in the NUREG- 1150 PRA.
Table 6-8. MLEs of A(t) by failure mode definition for the linear model.

A(t)

Failure mode 1987 1988 1989 1990

AFW-MOV-PG

AFW-PMP-LK-STMBD

AFW-CKV-OOa

Broadly Defined Failures

5.58E-05 5.84E-05

7.65E-06 8.36E-06

4.59E-05 5.02E-05

Narrowly Defined Failures

6.10E-05

9.08E -06

5.45E-05

6.36E-05

9.79E -06

5.87E -05

0o%

tAj

AFW-MOV-PG 2.51 E-05 2.65E -05 2.79E -05 2.93E -05

AFW-PMP-LK-STMBD 7.65E -06 8.36E -06 9.08E -06 9.79E -06

a. Following discussion with personnel from the power station, the events with backflow of check valves were all reinterpreted as non-failures, and the failure mode

AFW-CKV-OO was no longer regarded as affected by aging (Section 6.2.3). Therefore, A(r) was taken to be the constant value given in the NUREG-l 150 PRA.

O-q

9'

t

CD

IC$

0

-CL

CD

ZI

E, . R

0

to

W

P

4.

LIn

z

00
Time-Dependent Failure Data Analysis

Table 6-9. Failure sets analyzed as a function of failure definition and significance level.a

Broadly defined failures Narrowly defined failures

No-aging assumption

rejected at significance

level of 0.40

1. 3-in. MOV plugging failure

2. Pump failure due to steam

binding

3. Pump discharge check valve

failure to closeb

1. 3-in. MOV plugging failure

2. Pump failure due to steam

binding

No-aging assumption

rejected at significance

level of 0.05

1. Pump discharge

check valve failure

to closeb

None

a. All combinations of failure definitions and confidence intervals were analyzed using each of the three models

(exponential, Weibull, and linear).

b. Following discussion with personnel from the power plant, this failure mode was no longer regarded as affected by

aging. See Section 6.2.3.

NUREG/CR-5378 6-26
7. QUANTIFICATION OF TIME-DEPENDENT RISK

7.1 Time-Dependent Risk

Analysis for AFW System

The final step in the risk quantification was the

calculation of CDF using a PRA model. The usual

inputs to a PRA include the time-averaged failure

rates for various failure modes. In order to calculate the time-dependent CDF associated with the

aging of the AFW system, the time-dependent

failure rates developed in previous chapters were

substituted for the time-averaged values.

7.1.1 Use of Maximum Likelihood Results to

Define Bayeslan Distributions. The work of

Section 6 resulted in point estimates and confidence intervals for A(t), the failure rate of a type of

component at a specified time t. The MLE A(t)

has a distribution that is approximately lognormal

(Section 5.3.5). Plots were examined (Figures 5-8

through 5-11 and 6-14 through 6-21) to ensure

that this lognormal approximation was acceptable

with our data. Use of the lognormal distribution

then yielded the approximate 90% confidence

bands developed in Section 5 (Figure 5-12) and

Section 6 (Tables 6-6 and 6-7).

The usual PRA techniques require a different

input to the computer code, a Bayesian distribution for A(r), The conversion from a confidence

interval to a Bayesian distribution was accomplished as follows. There is a Bayesian distribution that results in intervals that are numerically

the same as the confidence intervals, but now

with a Bayesian interpretation. That is, the 90%

confidence interval equals a 90% interval given

by the Bayesian density, the 95% confidence

interval equals a 95% Bayesian interval, and so

forth. This perfect agreement occurs if the Bayesian distribution is identical to the lognormal distribution for the MLE. Therefore, the required

Bayesian distribution for A(t) for an aging component was set equal to the distribution of A(t) calculated by PHAZE.

The usual textbook development of a Bayesian

distribution assumes a prior distribution and

combines it with the data to yield a posterior

distribution. For a sample application, see Bier

et al. (1990). By contrast, the approach of this

report does not use a prior distribution at all. One

important reason is the difficulty in obtaining

well-justified prior distributions for aging rates.

For example, the widely cited TIRGALEX report

(Levy et al. 1988, p. 2.19) presents aging rates,

but states "it is the relative positioning of the components, not the absolute numerical values ...

[that are] important." The Bayesian distributions

of the present report are based on the data alone

because confidence intervals depend on the data

alone. The results are as if the prior distributions

corresponded to complete ignorance. This is a

conservative approach, which has been advocated, for example, by Vaurio (1990).

7.1.2 Resulting Time-Dependent Component

Failure Rate Inputs. The PRA model was solved

using the IRRAS computer code (Russell et al.

1989). For lognormal inputs, IRRAS requires a

mean failure rate and an error factor as failure

mode inputs. This mean is somewhat larger than

the median; the median is numerically equal to

the MLE calculated by PHAZE.

Table 7-1 is a summary of these means and

error factors by aging model, by failure definition, and by failure mode. The values were calculated for the time when data collection ceased in

1987 and for the three years following. As mentioned in Section 2.4, we do not recommend

extending the aging rates further into the future

because human interactions are unpredictable,

unless possible mitigating actions are explicitly

modeled.

For comparison, the time-dependent failure

rates were also calculated for 1973 and 1974, as

summarized in Table 7-1. The year 1973 is the

initial operation date and can be used to calculate

the initial CDF. The values are shown for one year

later, 1974, to allow a useful comparison for the

Weibull failure rate, because this rate is zero at

time zero for any positive value of Pi. Also shown

in Table 7-1 are the time-averaged failure rates

7-1 NUREG/CR-5378
Z

-.1

00

Table 7-1. Mean values of A(t) and associated error factora by failure definition and failure model.

A(t) and error factor

Failurc

Failure mode model NUREG-1150 1973 1974 1987 1988 1989 1990

Broadly Defined Failure

AFW-MOV-PG

AFW-PMP-STMBD

AFW-CKV-OOd

Exponential

Weibull

Linear

Exponentiale

Weibull

Linear

Exponential

Weibull

Linear

Exponential

Weibull

Linear

Exponential

Weibull

Linear

2.40E-05 2.1 2.52E-05 1.9 6.09E-05 1.66

L.OE-07 3 N/Ab 2.50E-05 2.8 4.90E-05 1.48

1.70E-05 1.96E-05 5.58E-05

4.85E-05 89.7 2.91E-05 60.3 1.60E-05 8.74

2.5E-05 30 N/Ab 2.48E-05 69.4 1.42E-05 6.56

0.00 0.0 7.64E -06

5.88E-06 7.9 6.36E-06 6.6 6.55E-05 2.29

2.OE-06 3 N/Ab 5.17E-06 105 6.29E-05 2.11

0.00 0.00 4.59E -05

Narrowly Defined Failure

1.02E-05 3.2 1.05E-05 2.8 2.92E-05 2.17

I.OE-07 3 N/Ab 9.20E-06 7.0 2.52E-05 1.88

4.53E-06 5.91E-06 2.51E-05

4.85E-05 89.7 2.91E-05 60.3 1.60E-05 8.74

2.5E-05 30 N/Ab 2.48E-05 69.4 1.42E-05 6.56

0.00 0.00 7.64E-06

6.59E -05

5.02E-05

5.84E -05

2.44E -05

1.84E-05

8.36E -06

8.46E -05

7.55E-05

5.02E -05

3.26E -05

2.65E -05

2.65E -05

2.44E-05

1.84E-05

1.77 7.14E-05 1.89

1.52 5.14E-05 1.56

6.10E-05

12.50 3.99E-05 18.12

8.17 2.42E-05 10.14

9.08E -06

2.67 L.IIE-04 3.13

2.33 9.01E-05 2.57

5.45E -05

2.40 3.66E-05 2.67

1.97 2.78E -05 2.05

2.79E -05

12.50 3.99E-05 18.12

8.17 2.42E-05 10.14

7.76E-05 2.03

5.25E-05 1.59

6.36E -05

6.93E-05 26.52

3.21E-05 12.52

9.79E -06

1.46E-04 3.70

1.07E-04 2.83

5.87E -05

10

a

P

a

_n0

0

0

El

I?

t:

CD ,Fe

0

CL

CD

Z

1

M

C6

P71

t'j

AFW-MOV-PG

AFW-PMP-STMBD

4.13E-05 2.97

2.91E-05 2.14

2.93E -05

6.93E-05 26.52

3.21E-05 12.52

8.36E -06 9.08E -06 9.79E -06

a. For the exponential and Weibull models, the mean and error factor are given. The mean is larger than the MLE calculated in Section 6. For the linear model, only the MLE is given, as explained in

Section 6.3. The Weibull failure rate is undefined at time zero (1973). Units of X are 1/hour.

b. The Weibull failure rate is either zero or undefined at the beginning of the component's life.

c. While point estimates (MLEs) for X at time zero are always less than MLEs for X at one year, the mean value may be larger because of a larger uncertainty at time zero.

d. The values shown are based on failures before the data were reinterpreted. Following discussion with personnel from the power station, the events with backflow of check valves were all reinterpreted as non-failures, and the failure mode AFW-CKV-OO was no longer regarded as affected by aging. (See Section 6.2.3.) The constant failure rate from the NUREG-1150 PRA was used.
Quantification of Time-Dependent Risk

taken from the NUREG-I150 PRA (USNRC

1989).

7.1.3 PRA Adjustment to Allow TimeDependent Risk Quantification. The PRA, as

loaded into IRRAS, was verified by regenerating the cutsets from the fault trees and event trees

using the same truncation values as used in the

original NUREG- 1150 analysis. The cutsets

generated by IRRAS matched those of

NUREG-1150.

Changes were made to the PRA, in addition to

the input, in order to account appropriately for

those components that were aging. The most

fundamental change was to include component

failure modes that were exhibiting aging and had

been truncated from the time-averaged analysis. This change was accomplished by completely

reanalyzing the PRA using an extremely large value for the failure rate of the failure modes

showing aging: pump steam binding, 3-in. MOV

plugging, and pump discharge check valve backflow. The top cutsets were then regenerated. The

resulting cutsets included the originals and

approximately 1,000 additional cutsets. Note, the

additional 1,000 cutsets had been truncated from

the original PRA because they made a negligible

contribution. They were included in the age- dependent PRA because it was not known if they would make a contribution. This was not a change

in the conceptual fault tree, only a change of

detail in the computation.

These cutsets were used to calculate risk as a

function of time by using the failure rates shown

in Table 7-1. For example, in order to calculate

the predicted risk associated with the exponential

aging model in the year 1990 for the narrow definition of failure at the 0.40 level of aging significance, the inputs for 3-in. MOV plugging would

be 7.76E-05 and 2.03, the inputs for pump steam

binding would be set to 6.93E-05 and 26.52, and

the inputs for all other failure modes would be set

to the time-averaged values from the

NUREG- 1150 PRA.

7.1.4 Results. After the data were reinterpreted,

as described in Section 6.2.3, the two failure

modes affected by aging were (a) 3-in. MOV

plugging failure and (b) pump failure from steam

binding, as given in Tables 6-9 and 7-1. The failure modes, though not the failure rates, were the

same under both the broad and narrow definitions

of failure. The aging was statistically significant

at the 0.40 level, but not at the 0.05 level.

The calculated risks for the various cases are

shown in Table 7-2. The risk is expressed as total

CDF. The associated uncertainties were calculated by IRRAS with standard simulation

techniques using Latin-Hypercube sampling. Remember that since the linear model was unable

to produce a distribution, an uncertainty or a

mean for this model could not be produced.

Figure 7-1 is a graphical plot of the values from

Table 7-2 corresponding to the broad definition of

failure. The figure shows the mean and 90% interval for the CDF, assuming the exponential or

Weibull model. For the linear model, the figure shows only the point estimate of the CDF, based

on MLEs, because uncertainty intervals were not

calculated for the linear model. The calculated

CDF is shown for three years: the initial year of

commercial operation, 1973; the following year, 1974; and the year when data collection ceased,

1987. The predicted CDF is shown for the three

following years, 1988 to 1990. Also shown is the

CDF taken from the NUREG-1 150 PRA, a time

averaged value.

The striking feature of Figure 7-1 is that the

"aging" CDF is virtually constant, negligibly different from the steady-state values of the

NUREG-1150 PRA. The increases in the two

component failure rates have almost no effect on

the overall CDF. Although not shown, a figure based on the narrow definition of failures would

be very similar to Figure 7-1.

This report is primarily a demonstration of an

approach, not a presentation of plant-specific

results. Therefore, it is worth dwelling on some of

the intermediate steps that led to Figure 7-1. Initially, pump discharge check valve failure-toclose was considered to exhibit statistically

significant aging, as shown in Tables 6-9 and 7- 1,

when the broad definition of failure was used.

7-3 NUREG/CR-5378
z

ni

c-I

-Ij

Table 7-2. Mean values of CDF and associated uncertainties quantified after reinterpretation of raw data.

Mean value CDF (yrt

) and 90% intervalb

Significance

levela Failure model 1973 1974 1987 1988 1989 1990

Broadly Defined Failure

0.40 Exponential 4.09E - 05 4.09E-05 4.09E - 05 4.09E - 05 4.09E-05 4.09E - 05

6.55E-06to 1.18-04 6.55E-06to 1.18-04 6.55E-06to 1.18E-04 6.55E-06to 1.18E-04 6.55E-06to 1.18E-04 6.55E-06to 1.18E-04

Weibull N/A 4.09E-05 4.09E - 05 4.09E - 05 4.09E-05 4.09E-05

6.55E-06to 1.18E-04 6.55E-06to l.18E-04 6.55E-06to 1.18E-04 6.55E-06to 1.18E-04 6.55E-06to 1.18E-04

Linear 3.30E - 05 3.30E - 05 3.30E-05 3.30E - 05 3.30E-05 3.30E - 05

Narrowly Defined Failure

0.40 Exponential 4.09E-05 4.09E -05 4.09E -05 4.09E - 05 4.09E - 05 4.09E - 05

6.55E-06to 1.18-04 6.55E-06to 1.18E-04 6.55E-06to 1.18E-04 6.55E-06to 1.18E-04 6.55E-06to 1.18E-04 6.55E-06to 1.18E-04

Weibull N/A 4.09E - 05 4.09E - 05 4.09E - 05 4.09E - 05 4.09E - 05

6.55E-06to 1.18E-04 6.55E-06to 1.18E-04 6.55E-06to 1.18E-04 6.55E-06to 1.18E-04 6.55E-06to 1.18E-04

Linear 3.30E - 05 3.30E-05 3.30E - 05 3.30E - 05 3.30E-05 3.30E - 05

a. There were no failure modes that rejected the no-aging assumption at the 0.05 level of significance.

b. Uncertainties could not be calculated for the linear model; therefore, only point estimates are given.

-o

0

0
Quantification of Time-Dependent Risk

U-3

c10-

a) -4

CD

0c

G)

a)

0)

CD

EE 10

a)

0

U

- Exponential

-- * Weibull

A Linear

-_____-- NUREG-1150 PRA

time-averaged base case

-- r il- i1-l- T-1--- I lT

A ,1

10,

1973 19

iA~ 1

1987 1988 1989 1990 ,,

Year for which risk calculation is applicable S306 SR-0191-02

Figure 7-1. Calculated mean CDF and 90% interval after the data were reevaluated. Note that the

Weibull failure rate is undefined at time zero (1973) and that for the linear model the MLEs are plotted

because means could not be calculated.

Although the checks for fit of the model cast

strong doubt on the assumption of independent

failures, the failure rate for this failure mode was

tentatively modeled as increasing, pending

receipt of further information about the events

recorded in the data base. This led to the data in

Table 7-3 and Figure 7-2, in which the CDF is

predicted to increase by a factor of about 2 in

17 years of plant operation. This increase results

entirely from backflow of pump discharge check

valves, which has a calculated failure rate of

about 1 per year at the end of the time period.

Such a failure rate is contrary to experience.

Although Figure 7-2 was eventually discarded

in favor of Figure 7-1, the following observations

apply to both figures.

* The mean and 90% interval of the total CDF

is essentially the same regardless of whether

the exponential or the Weibull model is

used.

* The point estimate of CDF produced by the

linear model is similar to the mean

calculated using the other two models.

* The initial CDFs calculated from the timedependent failure rates are consistent with

the CDF from the PRA.

7.1.5 Simultaneous Aging. Caution must be

used in applying the approach to be sure the interaction of the aging of components is considered.

If the increase in CDF is calculated separately for

the aging of each component, the sum of the

change in CDF will underestimate the change

with all components aging simultaneously. This

occurs because the aging interaction will not be

included. The concept can be demonstrated by a

simple example of a two-component cutset with

both components aging. If pi and P2 are the initial

failure probabilities and Ap, and zip 2 are the

increases in failure probabilities from aging, then

the increase in failure probability of the cutset

from aging calculated as the sum of the increase

7-5 NUREG/CR-5378
~Cl

-I1

00

Table 7-3. Mean values of CDF and associated uncertainties quantified before reinterpretation of raw data.

Mean value CDF (yrl) and 90% intervalb

Signilicance

IcveP Failure model 1973 1974 1987 1988 1989 1990

Broadly Defined Failure

0.4(0 Exponential 3.97E-05 4.25E-05 6.64E-05 7.87E-05 7.92E-05 I.09E-04

6.79E-06 to 1.19-04 7.08E-06 to 1.43E-04 9.02E-06 to 2.37E-04 9.47E-06 to 2.47E-04 9.45E-06 to 2.55E-04 7.53E-06 to 3.19E-04

Weibull N/A 4.51E-05 7.02E - 05 7.17E-05 7.29E-05 7.70E - 05

6.31E-06 to 1.33E-04 9.14E-06 to 2.04E-04 9.81E-06 to 2.23E-04 9.81E-06 to 2.39E-04 9.85E-06 to 2.61E-04

Linear 3.22E-05 3.22E-05 5.21E-05 5.39E-05 5.58E - 05 5.75E - 05

0.05 Exponential 3.97E - 05 4.25E-05 6.64E-05 7.87E-05 7.92E - 05 1.09E - 04

6.79E-06to 1.19-04 7.08E-06to 1.43E-04 9.02E-06to2.37E-04 9.47E-06to2.47E-04 9.45E-06to2.55E-04 7.53E-06to3.19E-04

Weibull N/A 4.51E-05 7.02E-05 7.17E-05 7.29E-05 7.70E-05

6.3 1E-06 to 1.33E - 04 9.14E - 06 to 2.04E-04 9.81E - 06 to 2.23E-04 9.81E - 06 to 2.39E - 04 9.85E - 06 to 2.61E - 04

Linear 3.22E-05 3.22E-05 5.21E-05 5.39E-05 5.58E-05 5.75E-05

Narrowly Defined Failure

0.40 Exponential 4.09E - 05 4.09E-05 4.09E-05 4.09E-05 4.09E - 05 4.09E - 05

6.55E-06to 1.18-04 6.55E-06to 1.18E-04 6.55E-061to .18E-04 6.55E-06to 1.18E-04 6.55E-06to 1.18E-04 6.55E-06to 1.18E-04

Weibull N/A 4.09E - 05 4.09E - 05 4.09E - 05 4.09E - 05 4.09E - 05

6.55E-06to 1.18E-04 6.55E-06to 1.18E-04 6.55E-06to 1.18E-04 6.55E-06to 1.18E-04 6.55E-06to 1.18E-04

Linear 3.30E-05 3.30E-05 3.30E - 05 3.30E - 05 3.30E-05 3.30E - 05

a. There were no narrowly defined failures that rejected the no-aging assumption at the 0.05 level of significance.

b. Uncertainties could not be calculated for the linear model, therefore only point estimates are given.

to

0

* O

0

0

.

~0

(b

0

CD

co

3

C:
Quantification of Time-Dependent Risk

10-3

U

r / V

Exponential

Weibull

Linear

NUREG-1150 PRA

time-averaged base case

C

a)

L..

4ia)

co

Eco

_0C)

To

.-4

0-5

1-- - -- - - - =

I A

T

I Tt A

I A

ii -A-L- , -_i -- - - - - - - - - - -- - - - - - - - - - -

-6

i-l/TI_1* 1973 19 ,,_ 1987 1988 1989 1990

Year for which risk calculation is applicable S306 SR-0191-01

Figure 7-2. Calculated mean CDF and 90% interval before the data were reevaluated. Note that the

Weibull failure rate is undefined at time zero (1973) and that for the linear model the MLEs are plotted

because means could not be calculated.

in failure probabilities with the components aging

separately is

[PI(P2 + ziP2) - PIP2]

+ [(pa + AP )P2 - PIP2]

P 1AP2 + P2aPI (7-1)

However, the change in failure probability calculated with the components aging simultaneously is

[(KP + Ap0(p2 + 4P2)] - PIP21

aging interactions will be important. Therefore,

to accurately calculate the increase in CDF when

the aging interactions are important, the increase

in failure probabilities for all aging components

should be included simultaneously in the PRA.

An objective of the research for this project

was to demonstrate the approach by calculating

the increase in CDF from the aging of components in a single system. Therefore, the demonstration in this section calculates the CDF if only

the AFW system ages. For the demonstration

case, only a few components were shown to be

aging. Increases in failure probabilities of these

components were input simultaneously and their

mutual interactions were included. However, the

terms for the interaction of aging with the aging

of components in other systems were not

included, and therefore, the effects of the interaction were not evaluated for the demonstration

study.

The above reasoning may also be applied to

systems rather than components. Of the

sequences leading to core damage and involving

= P1AP2 + p24pI + ap 1Ap 2 (7-2)

Obviously, the calculation with the components aging separately does not include the interaction term Ap,1Ap2. Of course, for cutsets with

more components there will be more interaction

terms that are not included. If the increases in

failure probabilities from aging are small, the

aging interactions will be products of small numbers and will not be significant. However, if the

increases in failure probabilities from aging are

comparable to those of the retained cutsets, the

7-7 NUREG/CR-5378
Quantification of Time-Dependent Risk

the AFW system, the vast majority involve simultaneous unavailability of the AFW system and

other safety systems. Simultaneous unavailability

of two systems corresponds to a "system-level

cutset," in contrast to the usual component-level

cutset. Equations (7-1) and (7-2) can be applied

to the system-level cutsets by letting p denote the

probability that a system in unavailable, and letting Ap be the change in this probability that

results from aging. Although we argued above

that everything should be treated as aging simultaneously, this report considered aging in only

one system, the AFW system. However, the calculated effect of AFW aging was very small; in

Equation (7-1), PothersAPAFW is very small, so

zPAFIV must be small. Therefore, either APothers

is small, in which case the interaction term is very

small, or APothers is moderate or large, in which

case the interaction term is much less than the

noninteraction term PAFIVAPothers. In either case,

the calculated aging of the AFW system would

have little effect on CDF, even if all the systems in

the plant were treated as aging simultaneously.

In summary, an aging analysis normally

requires simultaneous consideration of aging of

all components in all systems. In this particular

case, when only aging in the AFW system was

considered, the effect on CDF was extremely

small. This shows that, even if aging of other systems were considered simultaneously, the interaction terms would be small and aging of the AFW

system would have a very small effect. If the

effect of aging of the one system had not been so

small, it would have been necessary to consider

simultaneous aging of the other systems as well.

7.2 Potential Applications

7.2.1 Extrapolation to Distant Future. The risk

quantification approach presented in the preceding section has not accounted explicitly for mitigating or corrective actions. Therefore, as

discussed in Section 2.4, the methodology presented here is only useful for predicting risk for a

few years in the future. Maintenance and replacement are treated implicitly as part of the environment for observed past failures and, therefore,

also for extrapolations to the future. Schemes

may be developed for future applications, such as

the use of periodic replacement intervals to reset

the time-dependent failure rate to the time-zero

value (see Vesely et al. 1990) and/or the use of

component replacement when the failure rate

reaches a predetermined maximum allowed level.

7.2.2 Periodic Risk-Based Management.

Another option is to apply the approach on a yearly

basis. This results in current risk knowledge with

a small expenditure of effort. If such an analysis

shows that the present or near-future calculated

CDF is substantially greater than the time-averaged CDF from the PRA, the components or systems causing the increase should be identified.

These components or systems could then be considered for increased surveillance, maintenance,

and/or engineering analysis.

This approach was applied to the AFW data of

this study for the years 1979 through 1987. For

each year, only the data available at that time

were analyzed. For example, the 1982 analysis

used the data from 1978 through 1982. These

analyses, based on the narrow definition of failure, showed possible aging problems in three of

the years. None of these problems persisted year

after year. This observation indicates that either

(a) the trends identified were not actually present,

but were false alarms, or (b) the maintenance programs in place for the AFW system successfully

detected and mitigated the significant aging that

was occurring.

NUREG/CR-5378 7-8
8. CONCLUSIONS

The objectives of this study were as follows:

* Develop a way to identify and quantify agedependent failure rates of active components and to incorporate them into PRA.

* Demonstrate this approach by applying

it, with plant-specific data, to a fluidmechanical system using the key elements

of a NUREG-1150 PRA.

* Present it as a step-by-step approach, so that

others can use it for evaluating the significance of risk from aging phenomena in systems of interest.

These objectives have been met. Several conclusions of importance are as follows.

* A step-by-step approach has been developed and demonstrated, which provides a

workable way to estimate present and nearterm future risk based on the modeling

assumptions.

* Aging in the AFW system at the analyzed

plant has a negligible effect on plant CDF

when aging of only the AFW system is

assumed; however, with this assumption the

interaction with aged components in other

systems is not evaluated.

* Three aging models were considered: the

exponential, Weibull, and linear failure rate

models. With the data used, they produced

very similar results at times during the data

observation period and for extrapolations a

few years into the future. However, the

exponential model clearly behaved best for

quantifying uncertainties, and the linear

model clearly behaved worst, being in some

ways unusable.

* The availability of statistical diagnostic

tools encourages the analyst to check the

validity of the modeling assumptions. In

this demonstration, these routine checks

identified clustering in one data set with

12 failures, necessitating a follow-up

investigation. The other assumptions that

were checked appeared acceptable in this

demonstration.

We note the following difficulties in applying

the approach. These observations are not surprising to people experienced in risk assessment.

* Aging cannot be detected without highquality data covering a substantial time

period. Ten years of data from the AFW

system at two units provided minimal

information, so that for many failure modes

the degree of aging could not be estimated

with precision.

* The data of this report are likely to represent

a large plant-specific sample of failure

events for the period of time examined.

Other standby safety systems have been

found to exhibit very few failures in a similar period of time (for example, Bier et al.

1990).

* Classification of failure data from old

records is difficult. In this report, the problem was addressed by using broad and narrow definitions of failure. Judgment was

also necessary in combining maintenance

records that referred to the same event. In

one case, inquiry at the power station

resulted in a major reinterpretation of the

maintenance records and a substantial

change in the calculated CDF.

* Failures tend to cluster in time. In one case

this cast strong doubt on the assumption of

independent failures. In this demonstration,

the difficulty was resolved by better interpretation of the raw maintenance reports. In

other cases, it might be necessary to develop

a model that does not assume independence.

* The maintenance and operational environment may have changed at times in the

plant's history, resulting in permanent

impact on trends. For example, it is possible

8-l NUREG/CR-5378
Conclusions

that certain early failure mechanisms have

been eliminated. Any such changes could

not be determined from the maintenance

records alone; they may, however, influence

the estimated trend in the failure rate. The

desire for data covering a substantial time

period, mentioned above, conflicts with the

fact that operational practices change over

time.

To help interpret the maintenance records correctly, it is useful to have input from people

directly familiar with the plant equipment, practices, and history. This partially removes some of

the above difficulties, although others are

inherent in any effort to detect and quantify aging.

We also make the following observations concerning the possible application of the

methodology.

* Extrapolation of observed trends to the distant future would require more explicit

incorporation of maintenance and replacement policies. They are treated implicitly

here, as part of the environment for the

observed past failure events. Therefore, the

approach of this report should not be used

for distant extrapolation.

* Periodic use of the approach at a plant is

suggested as a means of supporting riskbased prioritization of surveillance, maintenance, and engineering analysis efforts.

For managers who must make decisions based

on three models, two definitions of failure, and

two significance levels, we, the authors of this

report, offer the following suggestions. Use the

exponential failure model. When aging of a component results in a significant increase in CDF,

use a table similar to the following example.

Table 8-1. Example decision matrix.

Broadly defined failures Narrowly defined failures

No-aging assumption

rejected at significance

level of 0.40

No-aging assumption

rejected at significance

level of 0.05

Awareness.

Inform operations and

maintenance staffs of

potential problem.

Reanalyze if failures

persist.

Strong interest.

Investigate immediately to

determine which

maintenance records

describe actual failures of

concern.

Strong interest.

Inform operations and

maintenance staffs of

potential problem.

Reanalyze after short

period of time.

Very strong interest.

Investigate immediately

and determine what

mitigating action should be

taken.

NUREG/CR-5378 8-2
9. REFERENCES

Alt, F. B., 1982, "Bonferroni Inequalities and Intervals," Encyclopedia of Statistical Sciences, Vol. 1,

S. Kotz and N. L. Johnson (eds.), New York: John Wiley & Sons.

Atwood, Corwin L., 1990, User's Guide to PHAZE, a Computer Program for Parametric Hazard Function

Estimation, EGG-SSRE-9017.

Atwood, Corwin L., 1992, "Parametric Estimation of Time-Dependent Failure Rates for Probabilistic Risk

Assessment," Reliability Engineering and System Safety, 37, pp.1 81- 19 4 .

Bartholomew, D. J., 1955, Discussion of article by D. R. Cox, Journal of the Royal Statistical Society, Series

B, 17, pp. 162-163.

Bier, V. M., D. C. Bley, Y.-M. Hou, D. H. Johnson, S. Kaplan, and J. E. Williamson, 1990, Development and

Demonstration of Methods for Nuclear Power Plant Aging Risk Analysis: Bayesian Data Analysis,

EGG-SSRE-8990, PLG-0743.

Cox, D. R. and P. A. W. Lewis, 1966, The Statistical Analysis of Series of Events, Section 3.3, London:

Chapman and Hall.

Crow, Larry H., 1974, "Reliability Analysis for Complex, Repairable Systems," in Reliability and Biometry: Statistical Analysis of Lifelength, F. Proschan and R. J. Serfling (eds.), Philadelphia: SIAM,

pp. 370-410.

Crow, Larry H., 1982, "Confidence Interval Procedures for the Weibull Process with Applications to Reliability Growth," Technometrics, 24, pp. 67-72.

Donelson, III, John, 1975, Duane's Reliability Growth Model as a Nonhomogeneous Poisson Process,

P-1162, Arlington, VA: Institute for Defense Analysis, December.

Engelhardt, Max, 1988, "Weibull Processes," Encyclopedia of Statistical Sciences, Vol. 9, S. Kotz and

N. L. Johnson (eds.), New York: John Wiley & Sons.

Ghahramani, K., 1989, "PRA Data Base Development: An Integrated Approach," Proceedings of the

International Topical Meeting on Probability, Reliability and Safety Assessment, Volume 2, April 2-7,

Pittsburgh, Pennsylvania, pp. 882-891.

Hahn, G. J. and W. Q. Meeker, Jr., 1982, "Pitfalls and Practical Considerations in Product Life Analysis-Part I: Basic Concepts and Dangers of Extrapolation," Journal of Quality Technology, 14, pp. 144-152.

Levy, I. S., J. Wreatherall, G. DeMoss, A. Wolford, E. P. Collins, and D. B. Jarrell, 1988, Prioritization of

TIRGALEX-Recommended Components for Further Aging Research, NUREG/CR-5248, PNL-670 1.

Phillips, J. H., W. S. Roesener, H. L. Magleby, and V. Geidl, 1990, "Aging Risk of Passive Components,

Status of the Project," 18th NRC Water Reactor Information Meeting, Rockville, MD, October 22-24.

Russell, Kenneth D. and Martin B. Sattison, 1989, Integrated Reliability andRiskAnalysis System (IRRAS),

Version 2.0 User's Guide, NUREG/CR-5111.

Salvia, Anthony A., 1980, "Maximum Likelihood Estimation of Linear Failure Rate," IEEE Transactions

on Reliability, R-29, pp. 49-50.

9-1 NUREG/CR-5378
References

Snee, Ronald D. and Charles G. Pfeifer, 1983, "Graphical Representation of Data," Encyclopedia of Statistical Sciences, Vol. 3, S. Kotz and N. L. Johnson (eds.), New York: John Wiley & Sons.

USNRC, 1987, Nuclear Plant Aging Research (NPAR) Program Plan, NUREG- 1144, Revision 1.

USNRC, 1989, Severe Accident Risk Assessment for Five U.S. Nuclear Power Plants, NUREG-1 150,

Draft 2.

Vaurio, J. K., 1990, "On the Meaning of Probability and Frequency," Reliability Engineering and System

Safety, 28, pp. 121-130.

Vesely, William E., 1987, Risk Evaluations of Aging Phenomena: The Linear Aging Reliability Model and

Its Extensions, NUREG/CR-4769, EGG-2476.

Vesely, W. E., R. E. Kurth, and S. M. Scalzo, 1990, Evaluation of Core Melt Frequency Effects Due to

Component Aging and Maintenance, NUREG/CR-55 10.

NUREG/CR-5378 9-2
Appendix A

Estimating Hazard Functions

for Repairable Components

A-1 NUREG/CR-5378
The pages printed here as Appendix A have been issued as a separate EG&G Idaho report. They are reproduced here

with page numbers changed to make them more accessible to readers of this NUREG.

NUREG/CR-5378 A-2
EGG-SSRE-8972

ESTIMATING HAZARD FUNCTIONS

FOR REPAIRABLE COMPONENTS

Corwin L. Atwood

Published May 1990

Idaho National Engineering Laboratory

EG&G Idaho

Idaho Falls, ID 83415-3421

Prepared for the

U.S. Nuclear Regulatory Commission

Washington, D.C. 20555

Under DOE Contract No. DE-AC07-761DO1570

A-3
ABSTRACT

This is a tutorial report, applying known formulas and tools in a way suitable for risk

assessment. A parametric form is assumed for the hazard function of a set of identical components.

The parameters are estimated, based on sequences of failure times when the components are restored to

service (made as good as old) immediately after each failure. In certain circumstances, the failure

counts are ancillary for the parameter that determines the shape of the hazard function; this suggests

natural tools for diagnostic checks involving the individual parameters. General formulas are given for

maximum likelihood estimators and approximate confidence regions for the parameters, yielding a confidence band for the hazard function. The results are applied to models where the hazard function, is of

linear, exponential, or Weibull form, and an example analysis of real data is presented.

KEY WORDS: Time-dependent failure rate, Non-homogeneous Poisson process, Poisson intensity,

Exponential distribution, Exponential failure rate, Linear failure rate, Weibull distribution.

FIN No. A6389-Aging Components and Systems IV:

Risk Evaluation and Aging Phenomena

A-4
SUMMARY

This tutorial report presents a parametric framework for performing statistical inference on a

hazard function, based on repairable data such as might be obtained from field experience rather than

laboratory tests. This framework encompasses many possible forms for the hazard function, three of

which are considered in some detail. The theory is neatest and the asymptotic approximations most

successful when the hazard function has the form of a density in the exponential family. The results

presented include formulas for maximum likelihood estimates (MLEs), tests and confidence regions,

and asymptotic distributions. The confidence regions for the parameters are then translated into a

confidence band for the hazard function. For the three examples considered in detail, a table gives all

the building blocks needed to program the formulas on a computer; this table includes asymptotic

approximations when they are necessary to maintain numerical accuracy. Diagnostic checks on the

model assumptions are sketched.

The report gives an example analysis of real data. In this example, the methods are unable to

discriminate among an exponential hazard function, a linear hazard function, and a Weibull hazard

function. The MLE for the two parameters appears to have approximately a bivariate normal distribution under the exponential or Weibull hazard model, but not under the linear hazard model. If the

analysis using approximate normality is carried out in any case, the results appear similar for all three

models. If some model is preferred for theoretical or other reasons, the framework of this report

indicates a way to use it.

A-5
ACKNOWLEDGMENTS

I am grateful to my colleagues Andrew J. Wolford and W. Scott Roesener for the stimulus and

insights provided during the course of this work. I also thank Max Engelhardt for pointing out early

related papers.

A-6
CONTENTS

ABSTRACT ........................................................................................................... ...................... A-4

SUMMARY ... A-5

ACKNOWLEDGMENTS ................. .. A-6

1. INTRODUCTION ................................. A-9

2. MODEL FORMULATION ................................. A-10

2.1 Basic Assumptions and Definitions ................ ...................................... A-10

2.2 One Notation for Two Types of Data .................. .................................... A-11

Types of Data ...................................................... A-11

Unified Notation ...................................................... A-12

2.3 Examples ...................................................... A-13

Exponential Hazard Function ...................................................... A-13

Linear Hazard Function ...................................................... A-17

Weibull Hazard Function ............. ......................................... A-18

3. LIKELIHOOD................. ................. A-18

3.1 Summary of Likelihood Formulas ................................ A-18

3.2 Ancillarity ................................ A-20

3.3 Examples ................................ A-20

4. MAXIMUM LIKELIHOOD ESTIMATION ............. .. ................. A-21

4.1 Maximum Likelihood Estimation Based on the Conditional Likelihood .......... ............ A-21

4.2 Maximum Likelihood Estimation Based on the Full Likelihood ................ .................. A-21

4.3 Examples ...................................................... A-22

Exponential Hazard Function ................. ..................................... A-22

Linear Hazard Function ...................................................... A-23

Weibull Hazard Function .............. ........................................ A-24

5. CONFIDENCE REGIONS AND HYPOTHESIS TESTS .......................................... A-25

5.1 Inference Based on the Conditional Likelihood ......... ......................... A-25

Inference for , .................................. A-25

Inference for AO .................................. A-27

5.2 Inference Based on the Full Likelihood .................................. A-28

5.3 Examples .................................. A-29

Exponential Hazard Function .................................. A-29

Linear Hazard Function .................................. A-30

Weibull Hazard Function .................................. A-30

A-7
6. DIAGNOSTIC CHECKS .............................................................. A-31

6.1 Common , .............................................................. A-31

6.2 Common AO .............................................................. A-31

6.3 Form of h(t) ............................................................... A-32

6.4 Adequacy of Asymptotic Normal Approximation ........................................................ A-33

7. EXAMPLE DATA ANALYSIS............................................................................................. A-34

8. DERIVATIONS AND PROOFS .............................................................. A-40

8.1 Derivation for Time-Censored Data ............................. ................................. A-42

The Likelihood .............................................................. A-42

Ancillarity ............................................................... A-42

8.2 Derivation for Failure-Censored Data ..................................... ......................... A-43

9. REFERENCES .............................................................. A-45

TABLES

1. Formulas for examples considered .............................................................. A-14

2. Summary of example data .............................................................. A-35

FIGURES

1. Component Comparisons for fi, Exponential Hazard Model ................................................. A-35

2. Q-Q Plot for Exponential Hazard Model ............................ .................................. A-37

3. Confidence Regions for (i3, AO), Based on Exponential Hazard Model ............. ...................... A-38

4. Confidence Regions for (,8, A0), Based on Linear Hazard Model, Centered Data ..... .............. A-38

5. Confidence Regions for (fl, AO), Based on Weibull Hazard Model ......................................... A-39

6. Confidence Regions for (,6, AO), Based on Linear Hazard Model, Uncentered Data ... ............. A-39

7. MLE and 90% Confidence Band for A(t), Based on Three Models ................. ........................ A-41

A-8
ESTIMATING HAZARD FUNCTIONS

FOR REPAIRABLE COMPONENTS

1. INTRODUCTION

This report is concerned with the failure behavior of components. It is a tutorial report,

applying previously known results in a way suitable for risk assessment. The model is defined in terms

of the random variable T, the (first) failure time of a component. In many published articles, it is

assumed that many components are tested until their first failure. The resulting failure times are used

as data, and the properties of the distribution of T are then inferred. By contrast, this report deals

with field data, not test data: it is assumed that each failed component is immediately restored to

operability (made as good as old) and again placed in service. The data then consist of a sequence of

failure times for each component.

A question of interest is whether the hazard function (or failure rate) is increasing, that is,

whether the failures tend to occur more frequently as time goes on. This and related questions are

investigated by postulating a parametric form for the distribution of T, and then performing the usual

statistical inference about the parameters of the model, with special emphasis on the parameter(s) that

determine whether the hazard function is increasing. The final goals of the inference are a point

estimate and a confidence interval for the hazard function at any time t.

The general methods are applied in detail to three assumed parametric forms for the hazard

function. A table gives all the formulas needed to implement the methods on a computer for these

three models.

The outline of the report is as follows. Section 2 presents the assumptions and notation, and

introduces three examples. Sections 3, 4, and 5 develop the likelihood formulas and equations for

maximum likelihood estimators and tests/confidence intervals. Each of these three sections also

discusses the application of the general results to the three examples. People who can appreciate theory

without considering examples may skip the application portions. Section 6 outlines diagnostic checks,

A-9
and Section 7 presents an analysis of data from motor-operated valves. Proofs arc in Section 8.

2. MODEL FORMULATION

2.1 Basic Assumptions and Definitions

Assume that the failures of a component follow a time-dependent (or non-homogeneous)

Poisson process. See, for example, Karr (1986) for a simple description, or Cox and Isham (1980) for a

fuller introductory treatment. Alternatively, one can parallel the development from fundamental

assumptions as given by Meyer (1970, Section 8.3) for the homogeneous case. The most important

properties are the following: there is a nonnegative function A(t) defined for i > 0, with the

probability of a failure in a short period (1, I + At) asymptotically approaching A(t)At as At - 0; the

failure counts in non-overlapping time intervals are independent; and the number of failures occurring

between 0 and t is a Poisson random variable with parameter A(t), where

A t) Jt A(u) du

Implicit in the independence property is the assumption that the component is restored to

service immediately after any failure, with negligible repair time. In operational data, it is not

uncommon to find that a component has failed several times in quick succession for the same reason.

Presumably. the first repairs did not treat the true cause of the failure. This situation violates the

independence property-the fact that a failure has occurred recently increases the chance that another

failure will occur soon, because the problem may not have been really fixed. It may be difficult to

force such data into the Poisson-process model: counting the failures as distinct ignores their apparent

dependence, while counting them as a single failure may make the time to true repair far from negligible.

The function A is called the hazard function, the failure rate, or the intensity function of the

Poisson process, and A is the cumulative hazard function. Assume now that A is continuous in I. It is

related to the cumulative distribution function (c.d.f.) F of the time to first failure, and to the

corresponding density function f by

A(i) = JRt)l[l- F(t)]

and

1 - F(1) = exp[-A(tl)]

A-10
Any one of the three functions F, f, and A uniquely determines the others. Note that because F(t) _ 1

as t - oo, it follows that

lim A(t) = oo . (1)

If A(t) is constant, as has been assumed for simplicity in many studies, the time to first failure

has an exponential distribution. Often the concern is whether A(t) is increasing in L. It is therefore

convenient to write A in the form

A(1) = Aoh(i;#). (2)

Here, A0 > 0 is a constant multiplier and h(t; P) determines the shape of A(t).

Because data generally come from more than one component, the following additional assumptions are made. The failures of one component are assumed to be independent of those of another

component. All the components are assumed to have the same function h with the same value of /3;

that is, a proportional hazards model is assumed. Depending on the context, it may or may not be

assumed that the different components have the same value of A0. Some simple regularity conditions

on h, needed for asymptotic results, are discussed at the beginning of the section on confidence intervals

and tests.

Sometimes there are gaps in the failure data. For example, the plant may have been shut

down for an extended period, during which no component failures were possible, or the failure data

may not have been collected for some period. This can be accommodated in the above framework by

treating each component as two components, one observed before the gap and one after the gap, having

the same installation date and, at the analyst's discretion, the same or possibly different values of A0.

2.2 One Notation for Two Types of Data

Types of Data

Failure data for a component can arise in a number of ways. Two simple ones to analyze are:

* A random number of failures in a fixed observation period (time-censored data)

* A fixed number of failures in a random observation period (failure-censored data).

The terms "time-censored" and 'failure-censored" follow the analogous usage for tests that are terminated before all the items have failed (e.g. Nelson, 1982, Sec. 7.1). Time-censored data arise if there is a

A-11
fixed time period when the component is watched or plant records are examined. During that time,

the component is restored to service after each failure. Failure-censored data might arise if the

component is repaired until a predetermined number of failures has occurred, at which time the component is removed from service and replaced by a new component. Both of these types of data result in

tractable formulas for statistical inference.

In reality, the decision to repair or replace a component is based on a number of considerations, such as the availability of replacement components, the severity of the particular failure mode

(including the difficulty and cost of repair), and any recent history of failures. These considerations are

difficult to express in a simple mathematical model. Therefore, only the two types listed are analyzed

here. In practice, one might simplify reality by treating failures that resulted in component replacement as if they were failure-censored.

Unified Notation

Let so and s, denote the beginning and end of the component's observation period; so does not

necessarily coincide with the component's installation. Let n be the number of observed failures not

counting any failure that results in replacement of the component. Let m be the total number of

observed failures, including any failure that results in replacement. Let il, ... , im denote the ordered

failure times. The two special cases then are

* Time-censored data: The observation period is from so to a fixed time sj. The random

number of failures is n, and therefore m is random and equal to n.

* Failure-censored data: The number of failures is fixed at m, and n is therefore fixed at

m - 1. The observation period starts at so and ends at a random time sj, with s, = im.

In general there are C components, indexed by j, and the quantities defined above are all indexed by j

sOj, slj n,, mj, and tij. In the formulas to be given, it is often convenient to define the midpoint -9

= (soj + slj)/2, and to define the range ri = (slj - soj). This notation, sometimes with the

subscript j suppressed, will be used without further comment.

Normally, time 0 is defined to be the installation time of the component. It may, however, be

useful to center the data by measuring all times from some value in the middle of the observed time

period(s). This can lead to negative failure times, allowed in the above formulation.

A-12
2.3 Examples

The methods of this report are applicable to a rather arbitrary hazard function, such as the

ones discussed by Cox and Oakes (1984, Chapter 2). Three such examples of hazard functions are

considered in this report. In each example, /3 is one-dimensional, the hazard function is increasing if /

> 0, is constant if / = 0, and is decreasing if if < 0. The units of AO are 1/time. The units of /3

depend on the example, but make h(i;/3) dimensionless in every case.

In some of the work presented below, the hazard function is treated as proportional to a

density function. Therefore, models can be expected to be most tractable when the hazard function is

of a standard form, such as a member of the exponential family. This is illustrated by the three

examples of this report, with the linear hazard model consistently producing problems that the

exponential and Weibull hazard models do not have. The differences result from the fact that logA(t)

is linear in /3 for the exponential and Weibull models, but not for the linear hazard model.

Various formulas and expressions are developed throughout this report. The forms that these

expressions take in the example models are all collected in Table 1, given at the end of the report. To

program the formulas for a computer, sometimes asymptotic approximations must be used to maintain

numerical accuracy. These approximations are also given in Table 1. All the formulas of Table 1 were

either derived or confirmed by using the symbolic computer program Mathematica (Wolfram, 1988).

Exponential Hazard Function

The hazard function is defined by

A(t) = Aoexp(fli),

with 63 measured in units of 1/time. This example is considered in detail by Cox and Lewis (1966,

Section 3.3). If P is negative, then A does not integrate to oo and Equation (1) is not satisfied;

therefore, A is not a hazard function. This quirk is interesting, but is not important in practice. It is

certainly possible for A(t) to have exponential form with negative / for I in the time period when data

are observed, and to have some other form for other i, so that A integrates to oo. In this case, A is a

hazard function, and it is decreasing exponentially in the observed time period.

A-13
Table 1. Formulas for examples considered

Expression

Constraints

h(t) [Eq. (2)9

Cond. suff. stat

for ,

[logh(0)]'

[logh(l)]"

v [Eq. (3)9

Asymptoticf

z, A

aO

al

a2

J

Asymptoticf

z, A

ao

a2

Exponential

None for t in finite interval

exp(/31)

EET;

0

0

exp(/3 so)[exp(/3r) - 1]/#

/3r, exp(Pso)r

1

1/2

1/6

exp(flso)[)3(sleXr- so)

_ (e3r7_1)]/,/2

13r, exp(/3so)r

Model

Lineara Weibullb

-l/max(s1 j)<fl<-l/min(soj) ,3 > -1

s1+/> 'oj(<° )

1 + ,lt (j/to),3

(.. I Tij, .. ) S EEogT;j

1/(1+/3u)

-{flogK, +/3SI)/(,+/3s0 )]

-/3r + /32 rg}/13

r1

log(t/to)

0

0

IoCD96 e/(/+l)

/3+1, to

Dlb,e

D2

D3

to[Clb!- CUl/(,/+1)]

/ (9+1)

/3+1, to

D~b,e

2D3

3D4

s0 /2 + r/3

s0 /6 + r/8

exp(/3so) [el3( 1 -_Bl)2

-(1-3sO)2

+ e-r 1] / /3

0 Io[C2 - 2Cl/(/3+1)

+2CU1(,6+l)2j1(,6+l)be

A-14
Table 1. (continued)

Asymptoticf

x, A 13r, exp(,Bso)r

ao s02 + sor + r

2 /3

a, SO2 /2 + 2 sor/3 + r2 /4

a2 SO2/6+ sor/4 + r

2

/10

13+1, to

2D3b, e

6D4

12D5

[logvj'

Asymptoticf

x, A

so- 1/

+r/[1-exp(-Pr)]

,B r, 1

Cl / C:O -1/(13+1)

aO

a,

a2

a3

r/12

0

- r/720

(13+1), 1/2

logso + logs,

D12/ 6

6

,e

0

-D1 4 /360

[logv]"/ r2 u/(1+a2u),

a = 13r

u = (ea + ea - 2 - a2)/ 4

t (1/12)[1 + a2

/30 + a4 /1680]

-f[logh(t)]"h(I)/v See individual terms {-,Br + (1+,63)x

+ flogv]I" log[(1+±1s 1)/(1+±6so)]}

Asymptotic' {r,83 (1-l63)2}

x, A See [logv]" 13, [r/(l+±3s)] 2

ao 1/12

C2 be/a) - (Cl/Cu)2

+ 1/(13+1)2

See individual terms

(13+1), D1 2 /2 be

0 a,

a2

a3

a4

(20-j2+ r2

)/80

_3 3+ r2

3/20) g

(56Og4 + 168r2 32

-D1 2/20

+ 3r4)/1344

A-15
Table 1. (continued)

L'(0)/[1(0)1 "2 EE(ti-s 1 ) EE(ts(i-ij) See text

/[En .r 2/ 12] 1/2 /[Enrj 2/12]1/ 2

a. If the data are centered at .mid = Erj j/Erj, then lij, soj, and s1j must be replaced by tij-imid

s0j - mid, and sj- 'mid, respectively, and Evj and its derivatives are replaced by 0.

b. For the Weibull failure rate model, any terms involving so should be omitted if so= 0. In this case,

the asymptotic expressions are not needed.

c. Equation numbers refer to defining equations in text.

d. The integral is for t from so to s,.

e. The notation Ck is defined as (s,/t0 )

3

0[1log(s1 /to)]k - (so/to) '+l[1og(so/to)]k, for k = 0, 1, 2. The

notation Dk is defined as {[log(s 1/to)]k-[log(so/to)]k)/k!, for k = 1, 2, 3, 4, 5.

f. The asymptotic approximation of the expression in the line immediately above is of the form

AEakxk. The next lines give the variable z and the values of A, ao, a,, .... The expression may be

computed as A(ao + alx) if a2 z2 is numerically insignificant compared to ao. For example, under the

exponential failure rate model, the asymptotic approximation for v is

v ; exp(3iso)rl + (1/2),/r + (1/6)(pr)2 + ...].

Therefore, v may be computed as exp(flso)r(l + &r/2) if

1 + (1ar)2 /6- 1

to the limits of the machine accuracy.

g. On a machine where a number has approximately 16 significant digits (IBM PC double precision),

for 5-digit accuracy in all cases, including cases when s is virtually zero, the expansion for the linear

hazard model should be evaluated out to the ,34 term. If this term is negligible compared to ao, the

series through the j 3 term should be used to evaluate the expression.

A-16
The constant AO is interpreted as the value of A(t) at time t = 0. This time 0 is customarily

taken to be the component's installation time, but any other time is allowed in principle. Measuring I

from a time other than the installation may make t negative, which is allowed. If each component has

a different AOj, the hazard function of each component changes by the same relative amount in any

specified time, but the hazard functions of the components are not equal. For example, the hazard

function doubles every (log2)/P time units, regardless of A0 j and regardless of what time is assigned

the value 0.

Linear Hazard Function

The hazard function is defined by

A(t) = A0 + at = .A0 (1 + fit),

with /3 measured in units of 1/time. This distribution is mentioned by Johnson and Kotz (1970b).

Salvia (1980) uses the model with test data, in which many components are tested until their first

failures. Vesely (1987) uses the model with field data for which failures from aging (corresponding to

the increasing portion of the hazard function) can be distinguished from failures from other causes

(corresponding to the constant portion of the hazard function). The cases considered by Salvia and

Vesely both turn out to be much simpler analytically than the cases considered in this report.

As with the exponential hazard model, it is possible that A has the specified form for the time

period for which data are observed, and some other form for other i. Therefore, it is possible for O to

be negative. However, /3 must not be such that A(t) is negative in the observed time period. In fact,

not even A(t) = 0 is allowed, because logA(t) is often used in the methods below. The details are

complicated by the fact that it is sometimes convenient to center the data, leading to observed times

expressed as negative values. Let sj and s8j be the beginning and ending observation times for

component j, following the unified notation defined above. To keep A(t) positive for all observed times,

/3 must satisfy /6 > -l/slj for all positive slj, and /3 < -1/sOj for all negative soj.

The constant A0 is the value of the hazard function at time t = 0. This time is the

component's installation time, or the central time, depending on how time is measured. Note that the

relative change in the hazard function approaches 0 as t -_ oo. For example when /3 > 0, the hazard

function doubles from the value at I = 0 in 1/fl time units, doubles again in the next 2/,6 time units,

A-17
and so forth.

Weibull Hazard Function

The hazard function is defined by

A(t) = AO(1/10) a

where to > 0 is a normalizing time. It is common (Johnson and Kotz, 1970a, Cox and Oakes, 1984) to

write the exponent as c - 1. The P notation is consistent with the other two examples because /3 = 0

corresponds to a constant failure rate. Both t and to have units of time, and /3 is dimensionless. The

constant AO is measured in units of 1/time, and is the value of the failure rate at time t = to.

Changing to does not change the value of /3, but does change the value of AO. For A(i) to be integrable

at 0, /3 must satisfy the constraint /3 > -1. Negative times are not allowed. If /6 > 0, A(0) equals 0;

if 3 < 0, A(0) is undefined.

The hazard function doubles between times tj and t2 if logt 2 - log0 1 = (log 2)//3. Because

A(O) is either zero or undefined, the hazard function cannot double from the initial value.

3. LIKELIHOOD

3.1 Summary of Likelihood Formulas

In this section, the expressions for the likelihood are presented. All derivations and proofs are

given in Section 8.

Let C denote the number of components. Define

H(t;,6) = J h(u;/3) du

and

Vj(/3) H(s1 j;/3) - I(sOj;/3) (3)

Depending on whether the data are time- or failure-censored, vj is fixed or is the realization of a

random variable. The parameter /3 will sometimes not be shown.

A-18
The logarithm of the likelihood based on all the data is shown in Section 8 to be

C [,mn

Lpulm(,1, Lo\a *--, AOC) = , [iogh(tij;I3) + mjlogX0,- Aoivj(B)] . (4)

This follows the unified notation established earlier, with the interpretation of mj and slj depending on

the way the data for the jth component were generated. The values of Aoj may be distinct, or assumed

to all be equal to a common AO. In the latter case, Ljlu, depends only on 6l and AO, and can be

written as

Lfull(, Ao) = [ Elogh(tijj;f) + mjlogAo - Aovj(i)] (4')

Now consider the conditional distribution of the ordered failure times, conditional on the values

of nj or imj, whichever is random. The conditional log-likelihood is shown in Section 8 to be

Lco nd() = c [>logh(tiij;) - njlogv j(P) + log(nj!) ] (5)

C n.

= E 1og{(nj!).t [h(t'j))3vj(3)]} (5')

From now on, the subscripts full and cond will be omitted, with the meaning being clear from the

number of parameters given as arguments of L. It is crucial to note that the conditional log-likelihood

(5) depends on /, but not on AO or the Aojs.

For component j, consider the term inside curly brackets in Expression (51), and suppress the

index j. The expression is the conditional joint density of the ordered failure times (T1 , ..., Ta).

Therefore, conditional on N = n or Tm = tm1 the n unordered failure times T, are independent and

identically distributed (i.i.d.), each with density h(t)/v on the interval [so, s1l, and density 0 outside

this interval. Therefore, inference for /3 can be performed in standard ways, based on observations that

are conditionally independent, and conditionally identically distributed for each component. This can

be done whether or not the components have a common value of AO.

Two other facts are needed to carry out inference for all the parameters. For time-censored

data, Nj is Poisson(Acovi). For failure-censored data, it is shown in Section 8 that 2AcO, VI has a

X2 (2mj) distribution. The values of AcO may or may not be assumed to equal some common value.

A-19
3.2 Ancillarity

Suppose that there is a multidimensional paramenter (13, 0), and a sufficient statistic (X, 1).

Y is said to be ancillary for if if the marginal distribution of Y does not depend on /3. X is called

conditionally sufficient for /3 if the conditional distribution of X given y does not depend on 0. When

these conditions hold, inference for / should be based on the conditional likelihood of X given y. When

maximum likelihood estimation is used, the same value for 13 is found whether the full likelihood or the

conditional likelihood is used, but the appropriate variance of , is the conditional variance. See

Kalbfleisch (1982) or Cox and Hinkley (1974, Sections 2.2viii and 4.8ii) for more information.

Return now to the setting of component failures, and consider time-censored data from C

components, when either (1) the components are not assumed to have a common value of AO, or (2) the

components have a common AO and all the vj's have a common value. In the examples of this report,

case (2) can occur only if all the components are observed over the same period so to sj. For case (1),

it is shown in Section 8 that (N1 , ..., Nc) is ancillary for 13, and that the failure times Tij form a

conditionally sufficient statistic for 1. (A lower dimensional conditionally sufficient statistic for i3 can

be determined in some examples by examining the form of EElogh(Ti,).) For case (2), the

components may be pooled into a single super-component, and N = DNj is ancillary for 13. In these

cases, therefore, basing inference for 3 on Equation (5) is not only possible but best. In all other cases,

basing inference for /3 on Equation (5) involves some loss of information.

3.3 Examples

The building blocks for the above formulas are all given in Table 1, at the end of this report.

A few points are worth noting here: The exponential hazard model is worked out in some detail by

Cox and Lewis (1966, Section 3.3). With this model, EElogh(Tij;P1) equals 13EETij, and it follows

that that EETij is conditionally sufficient for P3. For the linear hazard function, SElogh(T 1j;fl) equals

EElog(1 + 13Tij), and there is no one-dimensional statistic that is conditionally sufficient for l3. This

is one of several problems with the linear hazard model, which will be mentioned in this report as they

are encountered. For the Weibull hazard function, we have logh(T;fl) = jolog(T/10 ). Therefore,

EElogTij is conditionally sufficient for P3.

A-20
4. MAXIMUM LIKELIHOOD ESTIMATION

4.1 Maximum Likelihood Estimation Based on the Conditional Likelihood

If (N1, ..., NC) is ancillary for fl, then inference for fl should be based on the conditional loglikelihood given by Equation (5). Even in other cases, one could use this conditional log-likelihood at

the cost of some loss of information. The maximum conditional likelihood equation is formed by

setting the derivative of Expression (5) with respect to j3 equal to 0, resulting in:

Zl Zs{ [logh(kijQ;)]' - [logvj( 4 )]'l = 0 (6)

Here, the prime denotes the derivative with respect to /3. If /3 has dimension k, there are k such

equations, each involving the partial derivative with respect to one component of /3. The maximum

likelihood estimate (MLE) 3 typically is found by numerical iteration to solve Equation (6). If any

algebraic cancellation can be performed on the terms inside the curly brackets in Equation (6), then the

order of evaluation should be as suggested by the bracketing, for numerical accuracy. If no algebraic

cancellation can be performed, the evaluation may take advantage of the fact that Sj[logvj]'.

nj[logvj'.

Suppose that no common value of A0 is assumed. The MLE of A0j, corresponding to the jth

component, is A0j = mj/vj(/3). This is shown directly from Equation (4) by maximizing L(/3, AO, .

AOc) with respect to A0j. Suppose instead that a common value of A0 is assumed for all C

components. Then it is shown similarly that A0 = Emj/Evj(/3).

4.2 Maximum Likelihood Estimation Based on the Full Likelihood

Inference proceeds first by estimating A0, if a single common value is assumed, or by

estimating the various A0 j. Substitute the MLE(s) into the expression for the full log-likelihood,

differentiate the resulting expression with respect to /, and find the MLE /3.

When no common A0 is assumed, the equation for /3 is

C X-

(o/O/3)Lgi, A01, ..., I 4) _= E { [logh(41j;/fl' - plogv//3)]' =0 .(7)

A-21
This is identical to Equation (6), except that m appears in place of n. Therefore, use of either the

conditional or the full likelihood yields the same MLE ,3 from time-censored data; this agrees with the

conclusion of the ancillarity argument given earlier. For failure-censored data, Equation (7) differs

from Equation (6) by inclusion of the final failure times im and use of m = n + 1.

When a common A0 is assumed, the maximum likelihood equation for /l is

LiL,(v3, A0) = E [logh(tIj;f)]' - (Emj) [Evj'(/3)]/[vEj(/3)] = 0 . (8)

j=1 j=l 1=1

This differs from Equation (6) in two ways: mi is used instead of nj, which makes a difference only

with failure-censored data; and the portion involving vi reverses the order of summation and

multiplication and division.

4.3 Examples

All the expressions used in Equations (6) through (8) are presented in Table 1, for the three

examples. A few points of interest are mentioned here. Typical features of all the models are discussed

using the first example as an illustration.

Exponential Hazard Function

Consider first estimation based on the conditional likelihood. The maximum conditional likelihood equation for 6 is, from Equation (6) and the expressions given in Table 1,

C nj C C

E E (tij - so) + L nj/1 - nirj/[I - exp(-,3rj)] = 0 . (9) =1 i= j=1 =1

This agrees with the special case C = 1 and so = 0 worked out by Cox and Lewis (1966). It must be

solved numerically for 3. When ft is near 0, the last two terms in Equation (9) are very large,

although the difference is bounded. Therefore an asymptotic approximation should be used. From

expressions given in Table 1, a first order approximation is

E E+ }

j=1 Fi ~(j - soj) - (rj/2)(1 + flr,/6) }=0

A-22
When 6 is small, this asymptotic approximation must be used to prevent complete loss of numerical

significance; of course, when /3 = 0 the limiting value must be used. Note. that 8 equals 0 when

that is, when the sum of the (non-replacement) failure times equals the corresponding sum of the midpoints of the observation periods. This is intuitively consistent with the fact that when fl equals 0, the

conditional distribution of Tij is uniform on (so, sl). The MLE for AO or for the AOj's can be obtained

in a direct way from the results given above.

Inference based on the full likelihood is similar, using Equation (7) or (8) and expressions given

in Table 1.

Linear Hazard Function

It is straightforward to substitute the expressions for h(t) and vj into the general equations

given above. For example, consider the conditional log-likelihood based on a single component. Its

derivative is

L%(8) = Eti/(l + flij) -. n n/(l + /3)

It follows that the MLE /3, based on the conditional log-likelihood, equals zero if Mtj = Enjsj, just

as with the exponential hazard model. The following two points, however, deserve special notice:

The MLE , may be infinite. To see this, consider the expression for L'(fl) just given. If 1i >

1 for all i, then L'(,/) is positive for all /3. There is no finite solution to the maximum likelihood

equation. Thus, in cases when the evidence for an increasing failure rate is strongest, the rate of

increase may not be estimable by maximum likelihood.

With time-censored data and a common AO assumed, there is some advantage to centering the

data. In this case mi _ ni, and the full log-likelihood is

L(/3, AO) = EnilogAo + MElog(l + t j) - AoEri- AOErjsgj.

The last sum can be made to vanish by centering the data, that is, by measuring all times from

'mid = Erjsj / Erj

The log-likelihood then becomes

L(/3, Ao) = EnjlogAo + Mlog[1 + 6(lij - 'mid)] - Ao0rIn this formulation, A0 equals the value of A(t) at i = t

mid. If any value is assumed for /3, ENj is

A-23
Poisson(AoErj), independent of fi. Similarly, if any value is assumed for AO, L(3,Ao) is a function of

AO plus a function of , and the tij's; therefore, inference for fl is independent of AO. This ability to

perform independent inference for /3 and AO is a convenient property, which may be sufficient in the

eyes of some analysts to justify centering the data.

Suppose that when the data are uncentered, there is no finite MLE /3. Centering the data is

not a cure-all. When the data are centered, /3 is restricted to a finite range, as discussed in the

introduction to the linear hazard model in Section 2. In this case, the MLE II is at an end point of the

possible range; it is finite, but cannot be treated as asymptotically normal.

Weibull Hazard Function

In this case, [Pogh(ti j)J' = log(ti,/to). The remaining terms needed for Equations (6), (7), and

(8) depend on whether soj is zero or nonzero, and are all given in Table 1.

There is a noteworthy simplification in Equations (6) and (7) when soj = 0 for all j, that is,

when every component is observed from its time of installation. In this case, [logv]' equals log(sl/t&)

-1/(,3 + 1), and Equation (6) has the explicit solution

/3 = -En j/EIlog(1ij/s 1 j) - 1 . (10)

The solution of Equation (7) replaces nj by mj. These are the only cases considered in this report for

which the MLE /3 can be found without numerical iteration.

In this case, the value /3 satisfying Equation (6) equals 0 not when MEtij equals Enjsj, as in

the other examples, but when

-EElog(t j/s1 j) = n .

This initially surprising fact has the following intuitive basis. For notational simplicity, consider a

single component, suppress the index i, let to = 1, and condition the observations on the value of n or

sl. To derive the conditional distribution of -log(Tl/sl), begin with

P[-log(T*/sl) > a 1 = P[ Tj < slexp(-x) ]

Following the discussion below Equation (5), Ti has conditional density h(t)/tr, therefore, this

probability equals

J[slexp(-r)]p+ /(P + 1)} / {s1 ''/(fl + 1)} = exp[-x(,3 + 1)]

Therefore, the conditional distribution of -log(Tl/sl) is exponential with mean y = 1/(13 + 1).

A-24
Equation (10) can be rewritten as

-EElog(ji1/s1 j) / Enj = 1/(/ + 1) = p

that is, the MLE is based on equating the mean of -log(Tij/slj) to the sample mean. In particular,

the case /3 = 0 corresponds to Ai = 1, that is, -EElog(tij/s 1 j) / Enj = 1.

When the values of soj are not all zero, the expressions are more complicated, but the maximum likelihood equation is still equivalent to setting the mean of EElogTij equal to its sample mean.

5. CONFIDENCE REGIONS AND HYPOTHESIS TESTS

The standard regularity conditions, such as given by Cox and Hinkley (1974, Section 9.1) are

assumed. The assumptions involving the parameter space, identifiability of the distributions, and

existence of derivatives are all satisfied in the examples considered in this report. There is also an

assumption involving the behavior of the third derivative of the log-likelihood as n goes to infinity.

For field data, such an assumption is typically difficult to affirm or deny. Practitioners must always

treat asymptotic approximations with care.

5.1 Inference Based on the Conditional Likelihood

The procedure described here might be used when /3 is the primary parameter of interest, or

when (N1, ..., Nc) is ancillary for 63. The presentation here assumes that 63 is one-dimensional. The

generalizations to multidimensional /3 are straightforward. We remark in passing that when logh(t) is

linear in one-dimensional 63, as is the case for the exponential and Weibull models, then the one-sided

tests given below are uniformly most powerful.

Inference for /3

The derivative with respect to /6 of the conditional log-likelihood, L%(/3), is given by Equation

(6). The information is

I(^) = -EtL"(,3)) = El [L'(,8)]2 }

A-25
= -E E E [ogh(;ij! - 1n. Pogvj(0)]1'}

= Ejnj{-f [1ogh(t;#)]"hi(i;)3) dt/v,(j1) + [logvj(,O)"} * (11)

If , is k-dimensional, I(13) is the kxk matrix defined by taking all the mixed partial derivatives of L.

Let , be the true value. Under the assumed regularity conditions, the expectation of L%(3) is 0, and

the variance (or covariance matrix for k-dimensional 13) of L%(13) is 1(,1).

As a corollary to the Lindeberg-Feller Central Limit Theorem, Feller (1968, Section X.5) gives

a sufficient condition for asymptotic normality of L'(#). Rewrite Equation (6) as L'(p) = rEXk. If

there is a constant A such that IXkI < A for all k, and if (11) -_ co, then

L'(,3 0) / [1(130)]1/2 (12)

converges in distribution to normal(0,1). The assumptions must be verified for each example.

Typically, the assumptions are satisfied if all the values of s~i and slj are bounded by some constant,

and if some fixed fraction of the ri's is bounded away from 0. For the exponential hazard model, it is

enough for the rj's to be bounded by some constant and for a fixed fraction to be bounded away from

0. For the linear hazard model, it is necessary in addition for 1 + 13soj and 1 + Oslj to be uniformly

bounded away from 0. Qualitatively, the approximation is best if the soj's are approximately equal

and if the s1 j's are approximately equal. The approximation also is better if ,3 and h are such that

[logh(T 1

j;,8)]' does not have a highly skewed distribution. If it is very important to know whether the

normal approximation is adequate in some application, a simulation study should be performed.

An approximate confidence interval for l3 is the set of all 130 such that the statistic (12) lies in

the interval (-c, c), where c is the appropriate number from a normal table; for example, c = 1.96

yields an approximate 95% confidence interval. Actually, this defines a confidence region for 13. To

show that the region is an interval rather than some more complicated set, one must show that

Expression (12) is a monotone function of 83. Alonotonicity is difficult to show analytically. -It can be

checked numerically by a computer program in any example. In experience so far with real data, (12)

has always been monotone for the exponential hazard model, but has not always been monotone with

the linear hazard model when the confidence interval was unbounded, or for the Weibull hazard model

near 3 = -1.

To test the hypothesis 13 = 13o for some particular value Po, the test statistic (12) can be used,

A-26
and the hypothesis rejected if the test statistic is in an extreme tail of the normal distribution. In

particular, the hypothesis P = 0 is often of interest; the test statistic (12) may then have an especially

simple form, as discussed below for the examples.

Infcrence for A0

Once a value of 13 is assumed, it is easy to find a confidence interval for AO or confidence

intervals for the various Auj's. The method is shown here when the components are assumed to have a

single common A0 .

For time-censored data, define N = E2N, and v = v with v evaluated at the assumed value

of 13. Because N is Poisson(A0 Svj), a two-sided 100(l - a)% confidence interval for A0 is given by

Johnson and Kotz (1969, Section 6.2) as

AOL =X 2,,/2/(2v)

AOU = 22(n + 1),1 - a/ 2 /(2v) * (13)

If instead the data are failure-censored, define m = Emj and v = Evj with v evaluated at the

assumed value of 6. Because 2AOV has a X2 (2m) distribution, a two-sided 100(1-a)% confidence

interval for A0 is given by

AOL = X 22m.,/2/(2v)

AOU = X2 2m,1 _- (/ 2 /(2v) . (14)

Note that Formulas (13) and (14) agree except for the degrees of freedom.

A two-dimensional confidence region, with confidence coefficient approximately 100(1 -ca)%,

can be formed as follows. Form a 100(1 - ca/2)% confidence region for 13. At each 130 in the

confidence interval, evaluate v and form the resulting 100(1 - a/2)% confidence interval for A0. The

approximation results from the use of a large-sample approximation for the confidence interval for 1,

and from the way the two individual confidence coefficients are combined to yield a joint confidence

coefficient.

If /3 is treated as known and equal to 13, Equations (13) or (14) give an approximate confidence

interval for AO. It is too short, however, because it does not account for the randomness of the

estimator B. If this interval for AO depends strongly on the assumed value of 1f, a more exact

A-27
confidence interval is obtained by taking the largest and smallest values of AO in the two-dimensional

region for (dl, AO).

A conservative confidence interval for the hazard function A(t) is given by the largest and

smallest values of A(t) attained in the two-dimensional confidence region for (fl, AO).

5.2 Inference Based on the Full Likelihood

When all the model parameters are of interest, an analyst either could follow the procedure

presented above, or could perform inference based on the full model as follows. The discussion assumes

that all the components have a common A0. Formulas for A0 will be based on joint asymptotic

normality. There are heuristic arguments for why parameterization in terms of p = logAO improves

the normal approximation: for failure-censored data, this transformation replaces the scale parameter

A0 by a location parameter; also, the log transformation of Equations (13) and (14) yields more nearly

symmetrical intervals.

The log-likelihood L(13, AO) is given by Equation (4'). The sample information matrix for (,

P) (1, logA0 ) is

(8 2 /a13 2 )L(3, AO) (9 2/0139p)L(8, AO)

SI(#, logAo) =alq -0/P L 2/a ap)L( ,, AO) ( 2 /0p2 )L(j3, A)

-{1 i11ogh('ijj]T1} + AOvjIt AOvj1

= {Th~lo~h~iu~iu} j. (15)

Aovjl mj

In some situations, evaluation of the above terms at (13, A0) is made easier by using the identities

E mj/So = Ev and EE[logh(iij)]' = A Ev1 , with the second identity following from Equation (8)

evaluated at (0, A0 ).

The information matrix is then defined by

1(13, logAO) = E[SI(3, logAo)J -

The expectation is based on the randomness of Tij and of either Vi or Mlj. Depending on the form of

A-28
A, the analyst may choose to estimate the information matrix by 1(13, logAO) or by SI(/3, logAO); see

Cox and Hinkley (1974, p. 302). In practice, expecially when Vj is random, it is much more

convenient to use SI to estimate A(O, logAO).

Asymptotic inference is based on the fact that (13, logio) is asymptotically normal with mean

(l, IogAO) and covariance matrix r 1(fl, logAO). This allows for approximate confidence intervals for

1, for AO, and for functions of the two parameters, such as A(t). To do the last, write

logA(I) = logo + logh(i;/) -

Take the first-order Taylor expansion of logh(ft;,) around fi = 13. This yields the asymptotic distribution of logh(i;h), and its asymptotic covariance with logAO. Then logA(f) is asymptotically normal,

with mean equal to the sum of the means, and variance equal to the sum of the variances plus twice

the covariance. This may be used for t such that the Taylor approximation is adequate.

5.3 Examples

The building blocks for the formulas are all given in Table 1. Asymptotic approximations are

also given, to be used when , is near 0 with an exponential or linear hazard function, and when 13 is

near -1 with a Weibull hazard function. Special cases are now considered.

Exponential iHazard Function

To test if = 0, based on the conditional log-likelihood, the asymptotic formulas in Table 1

show that the test statistic (12) equals

j{iij -njuj1 }/[Ej njrj2/12]i/2 (16)

Here i goes from 1 to nj. When there is just one component (j = 1), the statistic becomes

[Eiti/n -s]/[r/(12n)1/2],

which has a simple intuitive interpretation. If the failure rate is constant (13 0), the conditional

distribution of the failure times for the component is uniform between so and sl. The test statistic is

the average observed time minus the midpoint of the observation period, all divided by the standard deviation of an average of uniformly distributed variables. This test was first proposed by Laplace in

1773, according to Bartholemew (1955).

A-29
In this case, logA(i) = logA0 + fli. Therefore, the asymptotic distribution of logAQ() follows

neatly from the asymptotic distribution of (/3, logA0 ).

Linear Hazard Function

Recall that time-censored data can be centered. This redefines the meaning of A0 and /, the

function h(f) becomes 1 + 3(1 - 'mid), and Evjp equals 0. The sample information matrix (15) then

becomes a diagonal matrix, and /3 and A0 are asymptotically uncorrelated.

The test of /3 = 0, based on the conditional log-likelihood, can be built from the elements in

Table 1. The statistic is given by Expression (16). That is, the natural large-sample test of constant

failure rate is the same, whether an exponential or linear hazard model is postulated.

The asymptotic distribution of A(t) is obtained by making the approximation

logh(l;B) _ log(1 + /3t) + (3-/)t/(1 + fit)

The approximation may be used when the second term is small compared to 1. For practical use, the

approximation is good enough if twice the standard deviation of S/3(1 + flt) is less than 0.1, and fair

if this standard deviation is less than 0.5.

Weibull Hazard Function

The necessary expressions are given in Table 1. In this model, the test statistic (12) differs

from Expression (16). When all the values of sO equal 0, the test statistic simplifies to

{EE[log(tiI/sl) + 1]} / (Enj)1 /2, (17)

with i going from 1 to nj. Recall from the discussion of maximum likelihood estimation below Equation (10) that the conditional distribution of -log(Tij/slj) is exponential with mean and variance

equal to 1/(, + 1), and that the MLE of 1/(/3 + 1) is the sample mean of the terms -log(tij/s1 j).

Therefore, the negative of the test statistic (17) can be written as the MLE of 1/(&6 + 1) standardized

by the mean and variance when l3 = 0.

The estimated hazard function satisfies A(t) = logA0 + ,log(i/t 0 ), so the asymptotic normal

distribution follows directly from the corresponding result for (p3, logA0 ).

A-30
6. DIAGNOSTIC CHECKS

The methods presented above have assumed a common value of /3 for all components, perhaps

a common value of A0, and a hazard function of the form ALh(t;/3). Computations are often based on

the assumption that asymptotic normality yields an adequate approximation. Diagnostic checks-both

tests and plots-should be used to investigate the validity of these assumptions.

6.1 Common /3

To see if a particular component, the kth say, has /3 significantly different from the other

components, calculate the MLE based on the kth component only and on all components (pooled)

except the kth. At this point there is no reason for confidence that the components have a common A0;

therefore, use the MLE based on the conditional likelihood, which is independent of the value(s) of A0 .

The difference /k - /L_ has variance equal to the sum of the variances, and mean zero if all

components have the same fl. Therefore it yields a test, using asymptotic normality, of the hypothesis

that the kth component has the same /3 as do the others. The C tests can be combined using the

Bonferroni inequality to form an overall test of the hypothesis that the components have a common /l.

If any component has no nonreplacement failures, /3 cannot be estimated for that component, and

fewer than C test statistics and confidence intervals can be calculated.

A single component may not have enough failures to justify asymptotic methods. In the

extreme case when the kth component has only one non-replacement failure, a practical expedient is to

treat /3-k as known, and test whether p3k = /-k. based on the single observed failure time for the kth

component. This test is based on the fact that the single failure has conditional density h(i)Ivk, with /3

set to fl-k.

In addition to the test for common /3, a useful visual diagnostic is a plot of C confidence

intervals for the parameter, placed side by side, with each interval based on the data from a single

component.

6.2 Common A0

Suppose that the assumption of a common /3 is accepted, and consider how to test whether the

components have a common A0 . Treat /3 as known and equal to /; this introduces an approximation

A-31
into the tests for AO, but it does not a priori treat any component differently from any other. Consider

now the kth component, pool all the components except the kth, and test whether A0

O, equals AO-k

Assume for the moment the null hypothesis that the components have a common AO.

With time-censored data, the conditional distribution of Nk, conditional on the ancillary statistic Enj, is binomial(Enj, pk), with pk = vk()/Evj(P). This yields a test of the hypothesis that AOk

is the same as AO for the other components. These tests may be combined with the Bonferroni

inequality. Alternatively, if the failure counts are not too small, a x2 test may be used, based on the

fact that (N1, ..., Nc) is multinomial (Enj, Pi, ..., Pc).

With failure-censored data, the distribution of 2Ao Vt(,8) is X2(2mk), and the sum of the

observation periods for all components except the kth is likewise proportional to a x2 random variable.

Therefore the ratio of Vk to the sum of such terms over all components except the kth is proportional

to an F random variable. This yields a test of the hypothesis that AOk is the same as A0 for the other

components. The tests may be combined with the Bonferroni inequality.

As when comparing the components for fl, a side-by-side plot of confidence intervals for A

provides useful visual diagnostic information.

6.3 Form of h(t)

To test whether h is of the assumed form, use the fact that for the jth component, conditional

on the observed failure count nj or on the final observation time sli, the Tfj's are independent and for

each component are identically distributed, with density proportional to h, as discussed below Equation

(51). Therefore, under the assumed model, the conditional probability that a random failure T occurs

by. time t is

P[T < t] = 7P[T < t failure is in component JI P[failure is in component j]

= 7PtT < t failure is in component 33 (nj/Eni)

with

P[T < I I failure is in component )] = [H(t) - H(s0j)I/vj if s~j < t < Slj

= 0 if t < sOj

= 1 if t > sj.

Tests for a hypothesized distribution may now be used, such as the Kolmogorov-Smirnov test or the

A-32
Anderson-Darling test.

Routine use of one of these tests gives a Type I error smaller than the nominal value; the test

tends not to reject often enough. There are two reasons for this. One is the familiar reason that the

estimated value of /3 must be used to evaluate H and v. The second reason arises if the components

are observed over different time periods. The distribution used is conditional on the failure counts or

final failure times, so the Tij's are not truly a random sample. As an extreme example, suppose that

component 1 was observed for only the first year of its life and that it had n1 failures, that component

2 was observed for only the second year of its life and that it had n2 failures, and so forth. The

conditional distribution then says that of Snj failures in the first C years, on the average ni will occur

in year i. The Ti1 's are a stratified sample from this distribution, and are therefore forced to fit the

distribution rather well. They fit well regardless of the form of h, because the stratification does not

involve the hypothesized h.

To avoid this difficulty, it is good to try to use components that are observed over the same

time period; if a few components have-a different observation window from all the others, try partitioning the data and performing the test on the two sets separately. In the extreme case given by the

above example, the following method could be used. Find 3 using all the data, and treat it as known.

Then for each of the C components perform a separate Kolmogorov-Smirnov test of Ho: , = /. This

yields p1 , ..., Pc, the attained significance levels or p-values. It is well-known that under Ho, a p-value

is uniformly distributed on (0, 1), so that -2Sog(pj) has a XN2(20) distribution. Thus Ho would be

rejected at level a if -2Sog(p1 ) > X2

1 .. (2C).

Two pictures may accompany the test. One is the plot of the above model-based c.d.f.

overlayed with the empirical c.d.f.. The other is a Q-Q plot, as described, for example, by Snee and

Pfeifer (1983). It plots the n observed failure times versus the inverse of the model-based c.d.f.

evaluated at 1/(n + 1), ... , n/(n + 1).

6.4 Adequacy of Asymptotic Normal Approximation

An MLE can be inspected to see if it is near the mid-point of a two-sided confidence interval; if

not, the normal approximation may not be adequate. Also, a two-dimensional confidence region for

(/3, logA0 ) can be constructed from an interval for /3 and conditional intervals for A0 given A, as

A-33
discussed below Equation (14). This can then be compared to the confidence ellipse based on the

asymptotic joint normality of (/3, logA0 ). If the two regions are very different, approximate joint

normality should be questioned.

7. EXAMPLE DATA ANALYSIS

A nuclear power plant for a commercial utility has 12 motor-operated valves in the auxiliary

feedwater systems at the two units of the plant. Maintenance records covering about 10 years were

examined, and the failure times for the valves were tabulated. The data are summarized in Table 2,

and are given in more detail by Wolford et al. (1990). Three valves were replaced upon failure, and

one was replaced for administrative reasons, leading to 16 valves shown in Table 2. The three valves

that were replaced upon failure were regarded as failure-censored. The other 13 valves were regarded as

time-censored. A Fortran program PHAZE (for Parametric HAZard Estimation) was written and used

on a personal computer to analyze the data, following the methods of this report; the program is

documented by Atwood (1990).

The valves were first compared to see if they have clearly different values of fi. Figure 1 shows

a side-by-side plot of the confidence intervals based on the individual components. It also shows the

significance levels based on a comparison of Is, to /-k. The diamond in each confidence interval

shows 1k while the square shows /-k. Note that there is no estimate or interval for components with

no non-replacement failures. The overall significance level, based on the Bonferroni combination of the

individual significance levels, is 1.0, confirming the pictorial impression that there is no real difference

in /3 for the various components. The exponential hazard function was assumed for these calculations.

The results were similar when the linear or Weibull hazard function was assumed. The only striking

difference was that many of the MLEs and all of the upper confidence limits were infinite with the

linear hazard function. A similar comparison of the components for AO led to a conclusion that the

components do not have greatly different values of AO. Therefore, the components were assumed to

have a common value of jJ and of AO.

Tests of 3 = 0 were performed based on the test statistic (12), and the hypothesis was rejected

in favor of 3 > 0. The test based on EEtij, when Expression (12) takes the form of Expression (16),

rejected at one-sided level 0.021. The test based on EElogtij, when Expression (12) is evaluated under

the Weibull model, rejected at one-sided level 0.025.

A-34
Table 2. Summary of example data

Nonrepl. Observed Mean Failure Replaced Initial

Component

MOV-1A

MOV-1B

MOV-1C

MOV-1D

MOV-1E

MOV-1E(R)

MOV-1F

MOV-1F(R)

MOV-2A

MOV-2B

MOV-2C

MOV-2C(R)

MOV-2D

MOV-2E

MOV-2E(R)

MOV-2F

Fails.

1

1

2

7

0

3

3

1

4

5

1

1

6

0

2

7

Hrs. Time (Normed)

8.8584E+04 0.378

8.8584E+04 0.086

8.8584E+04 0.752

8.8584E+04 0.743

2.1840E+04

6.6744E+04 0.498

4.3608E+04 0.568

4.4976E+04 0.487

8.8584E+04 0.619

8.8584E+04 0.567

4.9728E+04 0.756

3.8856E+04 0.866

8.8584E+04 0.464

2.2608E+04

6.5976E+04 0.698

8.8584E+04 0.593

on Fail.? Age (Hrs.)

4.1448E+04

4.1448E+04

4.1448E+04

4.1448E+04

Y 4.1448E+04

0.0000

Y 4.1448E+04

0.0000

3.7824E+04

3.7824E+04

Y 3.7824E+04

0.OOOOE-01

3.7824E+04

3.7824E+04

0.0000

3.7824E+04

MOV-1A

MOV-t B

0

0

C.)

MOV-1D

MOV-1E

MOV-1 E(R)

MOV-1 F

MOV-1 F(R)

MOV-2A

MOV-2B

MOV-2C

MOV-2C(R)

MOV-2D

MOV-2E

MOV-2E(R)

MOV-2F

OVERALL

._ * MLE(k)

* MLE(-k)

- 95% Conf. Int.

I'

I'

I * , I

.I

0.48

0.09

0.44

0.14

0.64

0.91 0 0.82 u

0.87 e

0.80 o

0.61 ',

-0.33 -9

0.21

0.54

0.97

1.00

7.5E-4

HIH

S

-5.0E-4 -2.5E-4 0 2.5E-4

Ji (1 /h)

5.0E-4

Figure 1. Component Comparisons for fi, Exponential Hazard Model

A-35
To test the form of the model, the Kolmogorov-Smirnov test was performed, as described in

Section 6.3. The test saw nothing wrong with any of the three models; the three significance levels

were all greater than 0.8. To account for the partial stratification of the data, the components were

partitioned into two groups, the twelve that were in place at the start of observation, and the four that

were installed during the observation period. The overall MLE, based on the conditional likelihood for

all the components, was used to estimate Pi. This value was treated as known in the two data sets,

and the Kolmogorov-Smirnov test was used to test the fit of each data set to each of the three models.

The three significance levels corresponding to the larger data set were calculated using asymptotic

formulas and were all greater than 0.79; the significance levels corresponding to the smaller data set

(seven failures) were not calculated exactly but were all substantially greater than 0.20. Even allowing

for the fact that the hypothesized model had an estimated parameter, it seems that the data give no

reason to question any of the three models.

Figure 2 shows the Q-Q plot of the full data set, based on the exponential hazard model. Q-Q

plots based on the other models look similar. The only evident departure from the assumed model is

shown by several strings of nearly vertical dots, indicating repairs that cluster in time. The effect of

this clustering is ignored below.

For each model, an approximate two-dimensional 90% confidence region was found for (/L,

logAo), as discussed below Equation (14). Similarly, a 90% confidence ellipse was found based on the

asymptotic normality of (/3, logA0 ). These two regions are superimposed in Figure 3 for the exponential hazard function, and in Figures 4 and 5 for the linear and Weibull hazard functions. The circle

and the ellipse show the MLE and the confidence region based on the full likelihood and asymptotic

normality, while the square and the non-elliptical region show the MLE and confidence region based on

the conditional likelihood. For the linear model the data were centered, and for the Weibull model the

normalizing to was set to Imid. For the exponential and Weibull models, the regions overlap fairly

well, suggesting that the asymptotic distribution is an adequate approximation. For the linear hazard

function, the confidence regions must be truncated at the maximum allowed value for /3. Therefore the

normal approximation is not adequate. By the way, when the linear hazard model was used with

uncentered data, the confidence regions were as shown in Figure 6. The non-elliptical region is thin

and strongly curved, and it hardly overlaps the truncated ellipse at all; therefore, centering seems to

improve the normal approximation, even though the approximation still is inadequate.

A-36
1.2E5

gl .0E5

0

2_

< 8.0E4

Cu

0as

.: 6.0E4

0

cow

: 4.OE4

'a0

2.0E4

.3-

p1/.

fI.

Sd,

/

A

/ 0 I I I I t. , XI

0 2.0E4 4.0E4 6.0E4 8.0E4 I.0E5

Observed Age at Failure (h).

1.2E5

Figure 2. Q-Q Plot for Exponential Hazard Model

A-37
3.0E-5

2.5E-5

2.0E-5

1.5E-5

1 .OE-5

5.0E-6

nOw 3 4 5 6 7 8 1 1O 2 Z5s3 4 5 6

0Xo (1/h)

Figure 3. 90% Confidence Regions for (dl, AO), Based on Exponential Hazard Model

1 .50E-5

1.25E-5

1 .OOE-5

- 7.50E-6

5.0OE-6 -

2.50 E-6-

o ........ , , , , ., .,, I,1 2 25 3 3.5 4 4.5 5 5

Xo (1 /h)

Figure 4. 90% Confidence Regions for (/3, A0), Based on Linear Hazard

10-4

Model, Centered Data

A-38
1.8

1.6

1.4 -

1.2

1.0

<- 0.8

0.6

0.4

0.2

0.0

-0.2 2

2

Figure 5. 90%

8.0E-4

6.OE-4

4.OE-4

2.0E-4

0

2.5 3 3.5 4 4.5 5 6 7 8 9

lo (1 /h) 1 0-4

Confidence Regions for (Ii, AO), Based on Weibull Hazard Model, Uncentered Data

U====

v3 n A . ,, I I I I II . .9.,.. .I .-I. I .,. I I I I I I ,..I - I..I . I4 5 1.5 2 3 4 a 1.5 2 3 4 5 10-6 (I Sh) 1-o I0-5

Figure 6. 90% Confidence Regions for (/6, AO), Based on Linear Hazard Model, Uncentered Data

A-39
Finally, the hazard function was estimated with a confidence interval based on the asymptotic

joint normal approximation. In spite of the poorness of the joint normal approximation for the linear

hazard model, the method was used for all three models, for comparative purposes. Figure 7 shows the

MLE and 90% confidence interval for A(t), at various values of t, for the three models. If the

confidence band for the linear hazard model were seriously advocated, it would be plotted only for

values of t satisfying

2 sd t/(1+,t) < 0.5,

where sd is the estimated standard deviation of /; outside this range, the first-order Taylor approximation of logh(t;j3) is inadequate. This restriction corresponds to requiring t > 1.6E4 h. If the upper

and lower bounds for the linear model are ignored where t < 1.6E4 h, the bands for the three models

look similar, except that the Weibull hazard function approaches 0 at time 0. Most of the components

were observed between ages 4.1E4 h and 13.0E4 h. It is not surprising that the confidence intervals are

narrowest [in the scale of logA(l)] in the middle of this period of the observed data. If the model were

extrapolated far beyond the data, the uncertainties would become very large.

8. DERIVATIONS AND PROOFS

The likelihood formulas developed here have long been known; for example, see Equations (2.1)

and (3.1) of Boswell (1966), or Bain et al. (1985). The derivations are sketched here for completeness.

Consider a single component. The fundamental idea to be used repeatedly here is that the transformation

u(t) = A(t) - A(so)

converts the non-homogeneous Poisson process to a homogeneous one with unit rate. That is, the

count of events occurring at transformed times u(t) with u(a) < u(t) < u(b) is Poisson with parameter

u(b) - u(a), and counts for disjoint intervals are independent. For such a homogeneous process, it is

well known that the time between successive events is exponential with parameter 1.0. Likelihood

formulas may be derived using the relation between the density of t, denoted by f, and the density of

u(t), denoted by 9:

J(t) = gAu(M)] 19u(t)/01I = exp[-u(W)]A(t)

ttjlti_1) = g[u(tj)Iu(1._1)]A(1i) = exp[u(it_) - u(ti)]A(ti)

Here, J(Iilti;_) is the conditional density of a failure at time ti, conditional on the component's being

operable (restored to service) at time li-.

A40
10-4 1,l..

6 ds

4 .5

4 .- S. ____=___ ______

.0 ' t.'~~~~~~~~~~~~-;f tat .

1 1.5 1. X , 

N

I 10-5 ! * _iExpon.

.-- i Linear * X~ ~~..... We! Ul

6 I

5

0 2.0E4 4._E4 6.0E4 8.0E4 1.0E5 1.2E5 14E5

Age (h)

Figure 7. MLE and 90% Confidence Band for A(t), Based on Three Models

A-41
8.1 Derivation for Time-Censored Data

The Likelihood

Consider a single component and suppress the subscript j and the argument /?. Suppose that a

random number of failures is observed in a fixed time interval (so, Sl], and that the ordered failure

times are il, ..., in. In the formulas below, define to = so and u, = u(ti). Note that U(so) = 0 and

u(sl) = Aov. The likelihood is the joint density of the observed failure times, multiplied by the probability of no failures after 4n; that is,

If u1 11 (f Ao) = [HAtilti l)] exp[A(in) - A(s 1 )]

- [HlA(id)][IexP(u1 i- - ti;] exp[un - u(si)]

= Ao" [rlh(li)] exp(-Aov), (18)

Taking logs and summing over the components yields Equation (4), as claimed.

For a single component, consider now the conditional distribution of the failure times given n.

Because N is Poisson(Aov), the probability of n failures is

exp(-AOv) (POv)" / n! * (19)

Therefore the conditional likelihood, the likelihood corresponding to the conditional distribution of t1,

.,n given n, is the quotient of Expression (18) divided by Expression (19):

1cond(#) =Th(t;)] (V)-n n!-

Taking logs and summing over components yields Equation (5), as claimed.

Ancillarity

Consider again a single component. The failure count N is ancillary for '8. To see this, define

M = Aov. Reparameterize so that the parameters defining the model are P and /3. Then N is

Poisson(p), so the distribution of N involves only p, not fl. Given N = n, the unordered failure times

Ti are i.i.d., each with density h(t)/v on the interval [so, sl]. This conditional density depends on 3

A-42
only, not on p. Therefore, N is ancillary for I3 and (T1 , ..., Tn) is conditionally sufficient for /3.

Suppose now that there are C components, C > 1, and that the components are not assumed

to have a common value of A0 . Then (N1, ..., Nc) forms a C-dimensional ancillary statistic for /3.

This is easily shown by a generalization of the above argument for a single component, parameterizing

the model in terms of /3 and (pi, ..., pc), with pj = X0 jvj.

Similarly, suppose that there are C components with a common value of AO, and that vj has

the same value v for all the components, regardless of /3. (Remark: In the three examples of this

report, this can occur only if the components all have a common value of so and s1. To see this, set vj

= Vk and = vk'. Evaluate these quantities at / = 0 using the formulas of Table 1. It follows

that soj = 80k and slj = s

8 k; this is immediate for the exponential and linear hazard function, and

can be shown with a little effort for the Weibull hazard function.) Now set P = Aov and note that N

= ENj is Poisson(Cp). Consider the conditional log-likelihood analogous to Expression (5), only now

conditional on n rather than on (n1, ..., n It is equal to

C 3

logl(n!)C" l I1 h(thN)/1]}

j=1 i=l

This is the log of the conditional density of the ordered failure times, with each time assigned at

random to one of the C components. Therefore, the Tjj's are conditionally i.i.d., each with conditional

density h(i)/v for so < t < sl. The components may therefore be pooled as a single super-component,

and N = ENj is ancillary for 8.

Finally, suppose that there are C components, C > 1, that the vj's are not all equal, and that

the components are assumed to have a common value of A0. There does not seem to be a reparameterization such that the distribution of (N., ..., NC) is independent of /3. Therefore (N1, ..., Nc) does not

appear to be ancillary. To show conclusively that (N., ..., Nc) is not ancillary, we note that Equations

(6) and (8) yield different values of /.

8.2 Derivation for Failure-Censored Data

Now suppose that a single component is observed starting at time so, and that m failures are

observed, with m fixed. The full likelihood is the joint density of the failure times:

A-43
lf-,(p, AO) = I

= [HA(Ij) exp(uo - um)

- Aion[j'h(ti)] exp(-Ache)] (20)

Taking logs and summing yields Equation (4).

To condition on the value t1,a the distribution of Tm must first be derived.

THEOREM. The time to the mth failure Tm has density

fm(tm) = Wm-l CWA(tm) / (m-1)! (21)

where w = A(tm) - A(so), and im > so

COROLLARY. Define AOVby A(Tm) - A(so). Then 2A0Vhas a X2 (2m) distribution.

PROOF OF THEOREM. Here, w _- u(tm), the mth transformed failure time. Because the transformed failure times correspond to a Poisson process with unit rate, it is. well known that the mth

transformed time has a gamma distribution. The asserted result follows. 0

The conditional distribution of (T1 , ..., Tm) given Tm = Im is (20) divided by (21). Take

logs and sum over the components to show that Lcond(fl) is exactly equal to Expression (5).

A-44
9. REFERENCES

Corwin L. Atwood, User's Guide to PHAZE, a Computer Program for Parametric Hazard Function

Estimation, EGG-SSRE-9017, 1990.

Lee J. Bain, Max Engelhardt, and F. T. Wright, "Tests for an Increasing Trend in the Intensity of a

Poisson Process: A Power Study," Journal of the American Statistical Association, 80, 1985, pp. 419-

422.

D. J. Bartholomew, Discussion of article by D. R. Cox, Journal of the Royal Statistical Society, Series

B, 17, 1955, pp. 162-163.

M. T. Boswell, 'Estimating and Testing Trend in a Stochastic Process of Poisson Type," Annals of

Mathematical Statistics, 37, 1966, pp. 1564-1573.

D. R. Cox and D. V. Hinkley, Theoretical Statistics, London: Chapman and Hall, 1974.

D. R. Cox and Valerie Isham, Point Processes, London: Chapman and Hall, 1980.

D. R. Cox and P. A. W. Lewis, The Statistical Analysis of Series of Events, London: Chapman and

Hall, 1966.

D. R. Cox and D. Oakes, Analysis of Survival Data, London: Chapman and Hall, 1984.

William Feller, An Introduction to Probability Theory and Its Applications, Volume I, Third Edition,

New York: John Wiley & Sons, 1968.

Norman L. Johnson and Samuel Kotz, Discrete Distributions, New York: John Wiley & Sons, 1969.

Norman L. Johnson and Samuel Kotz, Continuous Univariate Distributions - 1, New York: John Wiley

& Sons, 1970a.

Norman L. Johnson and Samuel Kotz, Continuous Univariate Distributions - 2, New York: John Wiley

& Sons, 1970b.

A-45
John D. Kalbfleisch, 'Ancillary Statistics," Encyclopedia of Statistical Sciences, Vol. 1, S. Kotz and N.

L. Johnson, eds., New York: John Wiley & Sons, 1982.

Alan F. Karr, "Poisson Processes," Encyclopedia of Statistical Sciences, Vol. 7, S. Kotz and N. L.

Johnson, eds., New York: John Wiley & Sons, 1986.

Paul L. Meyer, Introductory Probability and Statistical Applications, Reading MA: Addison-Wesley,

1970.

Wayne Nelson, Applied Life Data Analysis, New York: John Wiley & Sons, 1982.

Anthony A. Salvia, "Maximum Likelihood Estimation of Linear Failure Rate," IEEE Transactions on

Reliability, R-29, 1980, pp. 49-50.

Ronald D. Snee and Charles G. Pfeifer, "Graphical Representation of Data," Encyclopedia of Statistical

Sciences, Vol. 3, S. Kotz and N. L. Johnson, eds., New York: John Wiley & Sons, 1983.

William E. Vesely, Risk Evaluations of Aging Phenomena: the Linear Aging Reliability Model and Its

Extensions, NUREG/CR-4769, EGG-2476, 1987.

Andrew J. Wolford, Corwin L. Atwood, and W. Scott Roesener, Aging Risk Assessment Methodology

Demonstration Study on a PWR Auxiliary Feedwater System, NUREG/CR-5378, EGG-2567, DRAFT,

Rev. 1, 1990.

Stephen Wolfram, Mathematica: A System for Doing Mathematics by Computer, Redwood City, CA:

Addison-Wesley Publishing Company, 1988.

A-46
Appendix B

Tables of Maintenance Records

B-1 NUREG/CR-5378
Table B.1

Maintenance Records for

Auxiliary Feedwater System

B-3 NUREG/CR-5378
Table B.1.a. MAINTENANCE RECORDS FOR THE AUXILIARY FEEDWATER SYSTEM TURBINE DRIVEN FEED PUMPS

MODE/MECHANISM(if applicable)

MARK NO. COMPONENT M. R. # PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSSIFICATION*

1-TDP

1-TDP

1-TDP

1-TDP

2-TOP

1-TOP

2-TDP

1-TDP

1-TDP

1-TDP

1-TDP

1-TDP

1-TDP

1-TDP

2-TDP

1-TDP

1-TDP

1-TDP

2-TDP

1-TDP

2-TDP

1-TDP

2-TDP

2-TDP

2-TDP

2-TDP

1-TDP

2-TDP

1-TOP

1-TDP

1-TOP

2-TDP

2-TDP

1-TDP

PUMP

PUMP

VALVE

PUMP

PUMP

TURB

PUMP

PUMP

PUMP

PUMP

PUMP

TURB

INSTR

PUMP

PUMP

VALVE

PUMP

PUMP

INSTR

INSTR

PUMP

VALVE

PUMP

INSTR

PUMP

MOTOR

PUMP

INSTR

INSTR

PUMP SEAL

VALVE

GAUGE

PUMP

TURBINE

801010430

803030420

10176160

901030450

901261550

810040500

902131328

905021900

905181332

902040100

905101032

811030530

910201310

911011230

902201305

910201305

912172125

1240708

2191428

4131129

7221245

903271145

8300800

11010524

11170730

102080443

102091232

103030900

102270712

103091251

7270315

105110915

105231115

105130010

GROSS OIL-LOW DISCHARGE PRESSURE

EXCESSIVE DISCHARGE PREE-PT1S

BODY TO BONNET LEAK

GOV VALVE WILL NOT CONTROL PUMP SPEED

REFUEL PMS

VARIOUS REPAIRS

OIL COOLER END BELL CRACKED

DRAIN, CLEAN. INSPECT SUMP REFILL

SIGHT GLASS HAS OIL LEAK

HEAD GASKET LEAKS ON PUMP

ADJUST PACKING

GOVERNOR VALVE INOPERATIVE

REPLACE GAUGE AND REPAIR LEAK

OIL LEAK ON PUMP

PMS AS PER MMP-P-FW-004

REPLACE HANDWHEEL

OUTBOARD PUMP BEARING THROWING OIL

OIL SEAL PACKING LEAK

DEFICIENCY PUNCH LIST

BROKEN CASE SWITCH

PUMP HAS AUTOMATIC SIGNAL

REWORK GOV VALVE AND OVERSPEED TRIP

FIND AND REPAIR OIL LEAKS

CALIBRATE

OVERSPEED TRIP VALVE TRIPS

MOTOR TORQUES OUT

PERFORM MMP-FW-005

CHECK CALIBRATION OF GAUGE

REPAIR FLEX CONDUIT

OUTBOARD SEAL LEAKS EXCESS

TRIP VALVE

INSTALL NEW PRESSURE GAUGE

LEAK ON SUCTION PACKING GLAND

D/C 80-S88 ISOLATION OF AUX FEEDWATER

RENEWED THRUST BEARING LININGS

REDUCED SPEED OF PUMP AT GOVERNOR

RENEWED BONNET GASKET

FIXED SATISFACTORY

DID PMS CHECKS

REPAIRED AND TESTED GOVERNOR TRIP VALVE

VOID

DRAINED OIL, CLEANED SUMP

TIGHTENED SIGHT GLASS

VOID

VOID

VOID

REPLACED GAUGE

REPAIRED PUMP AND HELD PM CHECK

VOID

FOUND HANDWHEEL TO BE PROPERLY INSTALLED

RENEWED THRUST BEARING

RENEWED THRUST SHOE

REPLACED GLASS

INSTALLED NEW SWITCH

VOID - WORK PERFORMANCE ON MR 2007221802

VOID - DONE UNDER ANOTHER MR

TIGHTENED OIL FITTINGS

CAL GAUGES, REPLACED SUCTION GAUGE

STRAIGHTENED LINKAGE

CLEANED TORQUE SWITCH CONTACTS

PERFORM PREVENT MAINT SERVICE ON PUMP

INSTALLED NEW GAUGE, OLD ONE IS GOOD

MADE CORRECTIONS TO PS-FW-152

REPLACED ONE RING & PACKING

VOID - THIS HAS ALREADY BEEN WORKED

INSTALLED NEW GAUGE

TIGHTENED PACKING

INSTALLED LINE AS PER D/C

780111

780303

780508

790204

790228

790420

790420

790515

790611

790917

790917

791002

791102

791116

791128

791209

791223

800210

800319

800429

800725

800828

800830

801104

801118

810208

810218

810304

810317

810331

810430

810520

810531

810604

FR

FR

BL

FR

PMS

FR

VOID

PMS

MD

VOID

VOID

VOID

GAUGE

MD

VOID

MD

FR

FR

MD

FR

VOID

VOID

MD

GAUGE

FR

NFF

PMS

GAUGE

MD

BL

VOID

GAUGE

BL

DC

to

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY GAUGE - GAUGE REPLACEMENT OR CALIBRATION

DC - DESIGN CHANGE FR- FAILURE TO RUN FS - FAILURE TO START NFF - NON-FUNCTIONAL FAILURE
Table B.1.a. (continued)

MODE/MECHANISM(if applicable)

MARK NO. COMPONENT M. R. # PROBLEM DESC HISTORY SUMMARY RTSVOT CLASSIFICATION*

1-TDP

1-TDP

2-TDP

1-TDP

2-TDP

2-TOP

2-TDP

1-TDP

1-TDP

2-TOP

1-TDP

1-TDP

1-TOP

2-TDP

2-TDP

2-TDP

1-TDP

2-TDP

2-TDP

2-TDP

1-TDP

1-TDP

1-TDP

2-TOP

2-TDP

1-TOP

2-TDP

1-TOP

1-TDP

1-TDP

2-TOP

1-TDP

2-TOP

2-TDP

INSTR

TURBINE

VALVE

TURBINE

INSTR

VALVE

PUMP

TURB

PUMP

PUMP

VALVE

VALVE

SWITCH

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

VALVE

INSTR

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

TURB

GLASS

SIGHTGLA

PUMP

VALVE

SWITCH

106081328

107080847

107190318

109271530

110010900

102111400

8301025

7110905

110200400

8210243

112061246

112230958

110210224

102120300

110091528

7110907

112160430

201060807

201060812

112051530

202231420

204261123

204240356

205081945

205271700

206161054

206161053

207212001

207211430

208081600

208132143

208132145

209031049

209101905

GAUGE MISSING - REPLACE

CHANGE OIL

VALVE DOESN'T FULLY CLOSE

INSPECT TERRY TURBINE

CALIBRATE OR REPLACE GAUGES

OVERSPEED TRIP VALVE

FIND AND REPAIR OIL LEAKS

PERFORM PMS

EXCESSIVE PACKING

OIL LEAK ON TURBINE OUTBOARD

DIAPHRAGM LEAK

VALVE INDICATES OPEN

PRESSURE SWITCH MALFUNCTIONING

OIL LEAK

PERFORM MMP-P-FW-004

PERFORM PMS

MANUAL TRIP LEVER

RESET THRUST BEARING CLEARANCE

RESET THRUST BEARING CLEAR

POSITION LIGHT INDICATES OPEN

STEAM DRIVEN PUMP SUCTION GAUGE

REPACK INBOARD END OF PUMP

PUMP SEAL BENT. PUMP AND TURB LEAKING

GOVERNOR SET AT 4060 RPM

CRACK IN WELD

CHANGE OUT GOVERNOR

CHANGE OUT GOVERNOR

EXCESSIVE PACKING LEAK ON OUTBOARDS

FIND AND REPAIR CAUSE OF TERRY TURBINE

OIL LEVEL SITE GAUGE LEAKING

REPLACE OIL SIGHT GLASS

REPAIR OIL LEAK

POSITION LIGHTS INDICATE INTERM VALVE

LIMIT SWITCH NOT INDICATING VALVE 0

REPLACED MISSING GAUGE

VOID - DONE ON ANOTHER MR

ADJUSTED LIMIT SWITCH

COMPLETE

CALIBRATED GAUGES

VOID

VOID - TO BE UPDATED

VOID

ADJUSTED PACKING AND PUMP STILL LEAKS

VOID - UNABLE TO FIND LEAK

STOPPED DIAPHRAGM LEAK

ADJUSTED LIMITS AND PRESSURE SWITCH

VOID

COMPLETE

VOID

VOID

VOID

RESET THRUST CLEARANCE BY CHARGING

RESET THRUST CLEARANCE

NO PROBLEMS FOUND

REPLACED GAUGE

VOID - COMPLETED ON MRS 0204240356

ADJUSTED PACKING

RESET RPM TO 3880

REPLACED PIPE

CHANGED OUT GOVERNOR

REPLACED WITH NEW GOVERNOR

ADJUSTED PACKING

VOID

TIGHTENED TOP AND BOTTOM OF SIGHT GLASS

INSPECTED SIGHT GLASS FOR LEAK FOUND

CHANGED THRUSTED SHAFT COLLAR JOURNAL

ADJUSTED LIMITS FOR

ADJUSTED LIMITS ON SOV

810611

810708

810723

810930

811006

811014

811022

811028

811029

811123

811209

811224

820104

820104

820105

820106

820108

820128

820223

820301

820310

820427

820428

820513

820527

820621

820621

820723

820809

820816

820823

820824

820908

820910

GAUGE

VOID

NFF

PMS

GAUGE

VOID

VOID

VOID

BL

VOID

NFF

NFF

VOID

MD

VOID

VOID

VOID

PMS

PMS

VOID

GAUGE

VOID

BL

FR

NFF

DC

DC

BL

VOID

MD

MD

FR

NFF

NFF

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY GAUGE - GAUGE REPLACEMENT OR CALIBRATION

DC - DESIGN CHANGE FR- FAILURE TO RUN FS - FAILURE TO START NFF - NON-FUNCTIONAL FAILURE
Table B.1.a. (continued)

MODE/MECHANISM(if applicable)

MARK NO. COMPONENT M. R. # PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSIFICATION*

2-TDP

1-TOP

1-TOP

1-TDP

1-TDP

2-TDP

2-TDP

1-TDP

1-TDP

2-TDP

2-TDP

2-TDP

1-TDP

1-TDP

2-TDP

1-TDP

2-TDP

2-TDP

2-TOP

1-TOP

1-TDP

1-TDP

1-TOP

2-TDP

1-TDP

1-TDP

1-TDP

1-TDP

2-TDP

1-TDP

2-TDP

1-TOP

1-TDP

2-TDP

PUMP

GAUGE

PUMP

INSTR

INSTR

GAUGE

PUMP

BOTTLE

BOTTLE

GOVERNOR

PUMP

PUMP

PUMP

BOTTLE

GAUGE

PUMP

PUMP

PUMP

PUMP

PACKING

PUMP

INDICATOR

PUMP

PUMP

GAUGE

BOTTL

GAUGE

GAUGE

PUMP

PUMP

BEARING

GAUGE

N2 BOTTL

PUMP

209092200 PUMP OUTBOARD BEARING THROWS OIL

210141057 REPLACE OIL PRESSURE GAUGES TO BEARING

211060800 ADJUST OIL PRESSURE RELIEF

211060852 CALIBRATE PRESSURE GAUGE

211102345 REPLACE BEARING OIL PRESSURE GAUGES

211102343 REPLACE BEARING OILPRESSURE

211102100 OIL PRESS REGULATOR NEEDS TO BE ADJ

211091807 CHANGE OUT NITRO BOTTLES

211280901 CHANGE N2 BOTTLE

212061305 REPAIR FEEDBACK ARM

211151410 COUPLING GUARD MISSING

212070837 PACKING LEAK

212230847 REPLACE NITROGEN

212300500 REPLACE N2 BOTTLE

301140952 DISCHARGE GAUGE NEEDS CALIBRATING

302050907 N2 BOTTLE PRESSURE LOW

302111050 PUMP TRIPS

303101430 SET SCREW MISSING

303181232 OVERSPEED TRIP,

211112045 REPACK, ADJUST AUX FEEDWATER PUMP

211061159 PUMP NEEDS REPACKING

303091559 LEAKING CONNECTION BET PIPE AND PRES

304011235 TEN YEAR HYDRO

304250400 OIL SEAL LEAKING

305042040 CHECK CALIBRATION

307212225 REPLACE NITROGEN BOTTLE

308110835 GAUGE NEEDS RECALL

308110834 GAUGE NEEDS RECALL

308291127 OIL POSSIBLY CONTAMINATED

309200751 HANGER MISSING

306200726 REPLACE BEARING

305311605 REPLACE GAUGE

310030700 REPLACE NITROGEN BOTTLES

309271700 HIGH BEARING VIBRATIONS

VOID - COMPLETED ON MR 2209092200

REPLACED GAUGE WITH

ADJUSTED OIL PRESSURE RELIEF

CHECKED GAUGE, CALIBRATED

INSTALLED GAUGE AND

INSTALLED GAUGE AND

RESET OIL PRESSURE REGULATOR

REPLACED NITRO-2 BOTTLE

REPLACED N2 BOTTLE AND

REINSTALLED SETSCREW

INSTALLED COUPLING

INSTALLED ONE RING OF

REPLACED NITROGEN BOTTLE

REPLACED NITROGEN BOTTLE

CHECKED SATISFACTORY

CHANGED N2 BOTTLES

ADJUSTED OVERSPEED TRIP

ADJUSTED DAMPER

PUT SPRING BACK ON HOOK

VOID - COMPLETED NO 1211061159

REPACKED PUMP

TIGHTENED AND TAPED

INSPECTION COMPLETE

REPLACED BEARING AND THREAD SLOES

REPLACED GAUGE WITH

REPLACED NITROGEN BOTTLE

CLEANED + CALIBRATED GAUGE

CLEANED + CALIBRATED GAUGE

CHANGE OIL

MADE AND INSTALLED HANGER

REPLACED BEARING AND SHOES

INSTALLED NEW CAL GAUGE

CHANGED NITROGEN BOTTLES

ADJUSTED LINKAGE

820916

821014

821109

821109

821112

821112

821115

821120

821129

821207

821210

821212

821228

830110

830117

830209

830216

830314

830321

830404

830404

830418

830428

830429

830511

830726

830813

830813

830912

830923

830927

831004

831006

831013

VOID

GAUGE

MD

GAUGE

GAUGE

GAUGE

MD

MD

MD

FR

MD

BL

MD

MD

GAUGE

MD

FR

FR'

FR

VOID

BL

BL

PMS

FR

GAUGE

MD

GAUGE

GAUGE

MD

MD

FR

GAUGE

MD

FR

5

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY GAUGE - GAUGE REPLACEMENT OR CALIBRATION

DC - DESIGN CHANGE FR- FAILURE TO RUN FS - FAILURE TO START NFF - NON-FUNCTIONAL FAILURE
Table B.1.a. (continued)

MARK NO.

1-TOP

1-TDP

1-TOP

1-TDP

2-TOP

1-TDP

1-TOP

2-TDP

1-TOP

1-TOP

1-TDP

2-TOP

2-TDP

1-TOP

2-TDP

1-TOP

1-TDP

1-TOP

w 1-TDP

,J~ 2-TOP

1-TDP

2-TOP

1-TDP

1-TDP

1-TDP

2-TDP

1-TDP

COMPONENT

VALVE

PUMP

PUMP

PUMP

GAUGE

PUMP

VALVE

VALVE

PMP GOV

PUMP

PUMP

SWITCH

GAUGE

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

M. R. #

310272330

310221306

310301600

306200725

311210152

310201430

401040826

401040811

312311328

402171445

403030615

402240947

404051830

307211530

406121600

11029

12360

14061

13659

13711

13660

20077

12350

22684

21903

23379

PROBLEM DESC

CAP LEAKING

OUTBOARD LEAKS 1-TDP

REPACK PUMP

OIL LEAK

PLACE DAMPENER IN LINE

PUMP HAS LOW DELTA PRESSURE

CLEAN AND GREASE VALVE STEM

CLEAN AND GREASE VALVE STEM

REPAIR GOVERNOR

REPLACE N2 BOTTLE

TRIP VALVE LEAKS EXCESSIVELY

PUMP WILL NOT CUT OFF IN AUTO

GAUGE MISSING

BEARING HAS NON-QUALIF THRUST COLLAR

MANUFACTURE 2 COUPLINGS

REPLACE NITROGEN BOTTLE

REPLACE OIL SLINGER RING

MECHANICAL LINKAGE BROKEN

REPLACE BROKEN GAUGE

REPLACE PRESS GAUGE 2-TDP

REPLACE BROKEN GAUGE GLASS

INVEST/REPAIR SOV-MS-A/B

OUTBOARD BEARING THROWS OIL

REPAIR OUTBOARD BEARING SEAL

LEAK

TIGHTEN OUTBOARD PKG GLAND

PUMP INOPERABLE, REPAIR

MODE/MECHANISM(if applicable)

HISTORY SUMMARY

TIGHTENED CAP ON CHECK VALVE

VOID - TO BE DONE ON MR 0310301600

CHECKED LEAK RATE

VOID

INSTALLED FLOW OSCILLATOR

VOID - NOT A PROBLEM

CLEANED & LUBRICATED

CLEANED & LUBRICATED

INSTALLED NEW SEAT

REMOVED & REPLACED BOTTLE

NO PROBLEM

CHECKED SWITCH

INSTALLED NEW GAUGE

REPLACED NON QUALIFIED THRUST COLLAR

MANUFACTURED 6 COUPLINGS

VOID - AS PER SHIFT SUPERVISOR.

VOID - TO BE COMPLETED ON WO 012350.

REINSERTED ROD AND CLOSED SOCKET ENDS AROUND BALL

TIP.

REPLACE GAUGE.

REPLACE GAUGE

INSTALLED NEW CALIBRATED GAUGE.

BOTH VALVES ARE OPEN WITH OPEN INDICATION IN

CONTROL ROOM ON BOTH VALVES NO WORK PERFORMED

VOID - WORK COMPLETED ON WO 004170.

REPLACED GASKET, MANUFACTURED OIL PAPER.

REPACKED PUMP, ONE-HALF PACKING USED, SHOP SPARE.

REMOVED INBOARD AND OUTBOARD BEARING CAPSFOUND BOTH JOURNAL BEARINGS IN GOOD CONDITIONOUTBOARD THRUST BEARING -THRUST SHOES- WIPED AND

ROLLED OVER WITH BABBITT. ALIGNMENT

VOID - NOT REQUIRED AS PER ATTACHED MEMO.

RTSVDT

831031

831101

831104

831107

831122

840103

840109

840109

840111

840222

840305

840330

840427

840517

840613

850103

850207

850214

850314

850314

850315

850620

850726

850809

850809

850819

CLASSIFICATION*

BL

VOID

BL

VOID

DC

VOID

PMS

PMS

FR

MD

VOID

FR

GAUGE

MD

PMS

VOID

VOID

FR

GAUGE

GAUGE

GAUGE

VOID

VOID

MD

BL

FR

23564 INVESTIGATE/REPAIR PUMP

1-TOP

851213 VOID

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY GAUGE - GAUGE REPLACEMENT OR CALIBRATION

DC - DESIGN CHANGE FR- FAILURE TO RUN FS - FAILURE TO START NFF - NON-FUNCTIONAL FAILURE
Table B.1.a. (continued)

MODE/MECHANISM(if applicable)

MARK NO. HISTORY SUMMARY

1-TDP

1-TDP

2-TOP

2-TOP

1-TDP

2-TDP

1-TDP

2-TOP

2-TDP

1-TOP

1-TDP

* tz

1-TOP

1-TDP

1-TDP

1-TDP

1-TDP

2-TDP

1-TDP

COMPONENT

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

M. R. # PROBLEM DESC RTSVDT CLASSIFICATION*

24333 INVESTIGATE/REPAIR PUMP 851213 VOID

28462

28719

28865

29554

28417

29443

28172

31029

32273

26976

27017

27016

37655

33554

38556

1-TDP

REPLACE N2 BOTTLE

REPLACE NITROGEN BOTTLE

ADJUST PACKING GLANDS

CHANGE OUT BOTTLE

INVEST/ADJUST GOVERNOR RPM

CHANGE OUT BOTTLE

-I-INSPECT FOR BLOCKAGE

REPLACE NITROGEN BOTTLE

VOID TO WO 031510

P-REPLACE GLAND STUDS/NUTS

P-REPAIR OIL LEAKS

ADJUST/REPACK GOV VALVE

PERFORM CTS 87-86

CALIBRATE/REPLACE GAUGE

CHECK INSTRUMENTS

VOID - NOT REQUIRED AS PER ATTACHED MEMO.

REPLACED NITROGEN BOTTLE.

CHANGED OUT NITROGEN BOTTLE IAW PROCEDURE.

TIGHTENED OUTBOARD GLAND ONE FLAT LEAK STOPPED

100%. TIGHTENED INBOARD END 3 FLATS LEAK DECREASED

TO 20 DROPS PER MIN.

REMOVED EMPTY BOTTLE, INSTALLED NEW BOTTLE

(210oPSI), CHECKED FITTINGS FOR LEAKS. TESTED

SATISFACTORY.

VOID NO PROBLEM DURING PT

VOID - WORK PERFORMED ON EMERGENCY WO 029544.

REMOVED OIL COOLER FROM SYSTEM TESTED FOR

BLOCKAGE. NO BLOCKAGE FOUND. REINSTALLED IN SYSTEM

REPLACE NITROGEN BOTTLE

VOID - COMPLETED ON WO 031510.

PACKING LEAK/NORMAL WEAR

UNCLOGGED DRAIN LINES, REPLACED PACKING GLAND

STUDS, REPACKED INBOARD SIDE OF PUMP. 4 RINGS OF

PACKING USED. SHAFT SLEEVE IS WORN.

BAD BEARINGS/INSUFF. OIL FLOW

REPLACED BEARINGS. THRUST BEARINGS, AND REPACKED

PUMP.

INSPECTED GOVERNOR. STEM IS SEALED BY LEAK

OFF-CHANNELS, NO ADJUSTMENT AVAILABLE. VALVE TO BE

OVERHAULED ON WR 352517.

VOID - NOT REQUIRED.

REPLACED GAUGE.

OUT OF CAL/TIME & USE.

GAUGES WERE EACH: OIL PRESSURE, 1 OIL TEMP, 1

PUMP SUCTION, I PUMP DISCHARGE, AND 1 STEAM

PRESSURE.

VOID WORK NOT REQUIRED

BROKEN PART INTERNAL/OVER PRESSURIZATION

DISASSEMBLED PUMP, REPLACED IMPELLERS, DIFUSERS,

AND BEARINGS. TESTED PUMP AND RAN SATISFACTORY.

851223

860102

860106

860120

860121

860122

860224

860224

860318

860509

860509

860512

860627

860706

860715

MD

PMS

DC

MD

VOID

VOID

PMS

PMS

VOID

BL

FR

BL

VOID

GAUGE

GAUGE

21964 INVEST/REPAIR HI DISCH PRESS.

38507 OVERHAUL AUX FEED PUMP

860715 VOID

860718 NAF

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY GAUGE - GAUGE REPLACEMENT OR CALIBRATION

DC - DESIGN CHANGE FR- FAILURE TO RUN FS - FAILURE TO START NFF - NON-FUNCTIONAL FAILURE NAF - NOT AN AGING FAILURE (MAINTENANCE ERROR)
Table B.1.a. (continued)

MARK NO.

1-TDP

1-TDP

1-TDP

1-TDP

1-TDP

1-TOP

1-TDP

1-TDP

COMPONENT

PUMP

PUMP

PUMP

PUMP

PUMP.

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

M. R. I PROBLEM DESC

38591 INVESTIGATE/REPAIR TERRY

TURBINE

36784 PERFORM EWR 85-544

38639 INSTALL SPOOL PIECE

35392 P-OVERHAUL GOVERNOR

4170 INVESTIGATE PUMP BEARING LEAK

39823 REPLACE BEARINGS AS REQUIRED

40056 ASSIST TECH REP AS REQUIRED

40487 SPRING REPLACEMENT

40494 GOVERNOR ADJUSTMENT

41325 OPENINSPECT,REPAIR GOV VALVE

41215 ASSIST TECH REP AS REQUIRED

40454 ADJUST GOVERNOR VALVE LINKAGE

41324 ADJUST LINKAGE. HIGH DISCHARGE

40488 REPAIR OVERSPEED TRIP

MODE/MECHANISM(if applicable)

HISTORY SUMMARY

WORN BEARINGS/NORMAL USE

DISASSEMBLED WORN BEARINGS, AND REPLACED WORN

JOURNAL BEARINGS (.060).

REMOVED PIPING AND INSTALLED 3-1/2 PIPE PLUGS.

REMOVED TRAINER FROM PIPE. REINSTALLED PIPE.

VOID - WORK WAS PERFORMED ON TURBINE AND MOTOR. NO

PROBLEM FOUND WITH GOVERNOR VALVE.

BROKEN SLINGER/THRUSTING

REPLACED SLINGER, BEARINGS, WEAR RINGS, BALANCE

WIPED THRUST SHOES/IMPROPER SET THRUST

UNCOUPLED PUMP, TOOK ALIGNMENT CHECK AND CHECKED

THRUST. REMOVED BEARING HOUSING OUTBOARD THAT WAS

FOUND INBOARD.

ASSIST TECH REP VERIFIED PROPER LINKAGE

SETTINGS ON GOVERNOR LINKAGE.

GOVERNOR VALVE NOT OPEN ALL THE WAY, SUSPECT BAD

SPRING. REMOVED OLD SPRING AND REPLACED WITH NEW

SPRING. OPS DID AN OPERABILITY TEST AND GOVERNOR

VALVE IS STILL NOT OPENING.

REMOVED BONNET AND ROTATED 90 DEGREES TO PUT FLAT

MACHINED SURFACE TO NORTH POSITION. READJUSTED

LINKAGE AND TEST RAN PUMP.

VALVE GOV LEAK THRU/STEAM CUT SEATS

REMOVE LINKAGE AND VALVE FORM SYSTEM. FOUND BODY

TO BE STEAM CUT ON SEATS. AS WE REMOVED BUSHING

TEST RAN PUMP IAW OPS PT. TEST SAT, NO REPAIR

REQUIRED 9/24/86

LINKAGE/IMPROPER SET

DISCONNECTED LINKAGE L2 AND LI, REMOVED PIN FROM

SHAFT LI. SET STEAM GOVERNOR VALVE, LOOSENED

FISHER REGULATING SPRING AND SET AT 3/8.

VOID - COMPLETED ON WO 041325.

VALVE CHECKED FOR FREEDOM OF MOVEMENT. FOUND TO BE

STICKING APPROXIMATELY 50% IN THE CLOSED POSITION.

VALVE DISASSEMBLY REVEALED HEAVY WEAR AND SOME

STEAM CUTS TO GUIDE.

RTSVDT CLASSIFICATION*

860718 NAF

860721

860721

860807

860820

860821

860828

860907

PMS

PMS

VOID

FR

NAF

PMS

FR

W 1-TDP 860907 MD

1-TDP 860927 FR

2-TDP

1-TDP

1-TDP

1-TDP

860929

860930

PMS

FR

860930 VOID

860930 FR

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY GAUGE - GAUGE REPLACEMENT OR CALIBRATION

DC - DESIGN CHANGE FR- FAILURE TO RUN FS - FAILURE TO START NFF - NON-FUNCTIONAL FAILURE NAF - NOT AN AGING FAILURE (MAINTENANCE ERROR)
Table B.1.a. (continued)

MARK NO.

I-TOP

2-TDP

1-TDP

1-TDP

1-TDP

2-TDP

2-TDP

by 2-TOP

2-TDP

2-TDP

2-TDP

2-TDP

1-TOP

1-TDP

1-TDP

COMPONENT

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

M. R. # PROBLEM DESC

40491 VALVE LINKAGE ADJUSTMENT

38609 REFURBISH ROTATING ASSY.

40418 INVESTIGATEREPAIR T/T VALVE

41217 ASSIST TECH REP AS REQUIRED

39931 BEARING REPAIR

44339 2-TDP EWR 86-452

26975 REPLACE PCKG GLND BOLTS

44993 OVERHAUL GOVERNOR VALVE

41408 -P. L- OVERHAUL TURBINE

46180 TEST CASING SENTINEL VALVE

41407 -P- OVERHAUL PUMP

47554 CHANGE OIL

40126 REPAIR/REPLACE GOVERNOR VALVE

41624 PACKING REPLACEMENT/REPAIR

MODE/MECHANISM(if applicable)

HISTORY SUMMARY

WE FOUND THE LINKAGE OUT OF ADJUSTMENT AND

GOVERNOR LEVER HAD EXCESS WEAR. WE REMOVED THE OLD

LINKAGE AND GOVERNOR LEVERS,REPLACING SAME WITH

NEW LEVERS. THE NEW LEVERS HAD

ROTOR ASSY. HAS BEEN REFURBISHED AND IS LOCATED

IN THE WAREHOUSE.

INSPECT/INSPECT STRAINER

REMOVED VALVE FROM SYSTEM, CLEANED SEATING AND

GASKET SURFACES. FOUND GASKET SURFACE STEAM CUT,

WELD REPAIRED STEAM CUT.

ASSISTED TECH REP IN RUNNING PUMP AND MAKING MINOR

ADJUSTMENTS.

VOID - NOT REQUIRED AS PER ENGINEER.

TFE IN TWO DRAIN LINES INTO TURBINE CASING WHERE

AN EXISTING PLUG IS NOW. WELD CONDENSATE POTS IN

EXHAUST STEAM TURBINE.

REMOVED OLD STUDS AND NUTS. INSTALLED NEW

STUDS AND NUTS PUMP REPLACED UNDER WO 041407

LEAKS/WEAR

REMOVED GOVERNOR VALVE FROM TURBINE. BOTH SEATS

WERE BAD AND HAD TO BE REPLACED. REPLACED PLUG

AND STEM. REPLACED FLANGE GASKETS.

OVERHAUL/WEAR.

REMOVED LAGGING AND UNCOUPLED TURBINE FROM PUMP.

REPLACED ALL BEARINGS AND BUSHINGS ON TURBINE.

REMOVED WHEEL AND FOUND IT TO BE WORN.

TEST/OVERHAUL.

REMOVED VALVE FROM SYSTEM AND TRANSPORTED TO

INSTRUMENT SHOP CAL. LAB. SET UP ON TEST STAND

AND VALVE STARTED LIFTED AT 2 PSI ADJUSTED TO

REMOVED OLD ROTATING ASSEMBLY FOUND THRUST BRG

WIPED-ONE SET OF SHOES WRONG FOR SIDE USED,

OUTBOARD BEARINGS WORN FROM THRUST BRG

DRAINED OIL FROM RESEVOIR. REMOVED COVER PLATE,

WIPED OUT WITH LINT FREE DIAPER AND REFILLED WITH

NON-PARFIL TURBINE OIL APPROX 17 GALS.

VOID - WORK PERFORMED UNDER WO 055496.

VOID - PUMP PERFORMED SATISFACTORY ON

VOID - NO LEAK AS PER WALKDOWN.

RTSVDT CLASSIFICATION*

860930 FR

861001

861005

861008

861114

861131

861201

861201

PMS

BL

PMS

VOID

DC

MD

PMS

861201 PMS

861203 PMS

861211 PMS

861229 PMS

861230 VOID

861230 VOID

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED

DC - DESIGN CHANGE FR- FAILURE TO RUN FS - FAILURE TO START

MD - MINOR DEFICIENCY GAUGE - GAUGE REPLACEMENT OR CALIBRATION

NFF - NON-FUNCTIONAL FAILURE
Table B.1.a. (continued)

MARK NO.

2-TOP

2-TOP

1-TOP

1-TDP

1-TOP

1-TDP

1-TDP

1-TOP

1-TDP

COMPONENT M. R. #

PUMP 45013

PUMP 48794

1-TDP w

t~.)

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

44576

49060

40557

49601

44074

51012

52935

PROBLEM DESC

IMPLEMENT BWR 86-452

-P- REPR/REPL CONNECTING ROD

REFURBISH ROTATING ASSEMBLY

P-REPLACE END BELL GASKET

VALVE REPLACEMENT

REPLACE OIL COOLER FLANGE

GASKET

REPLACE SIGHT GLASS

INSTALL COUPLING GUARD

REPAIR LEAK

MODE/MECHANISM(if applicable)

HISTORY SUMMARY

VOID TO 44339

UNIT 2-FW-T-2 OVERHAULED DURING 1986 REFUELING

OUTAGE. OVERSPEED TEST WAS PERFORMED DEC 1986

SATISFACTORILY. INSPECTED LINKAGE WITH

VOID - WORK ORDER CREATED TO OBTAIN PARTS ONLY.

VOID - NOT LEAKING AS PER OPS RUN.

VOID - TO 049601

LEAK/WEAR

MANUFACTURED NEW GASKET AND INSTALLED ON COOLER.

BROKEN SIGHT GLASS/ACCIDENT

REMOVED OLD SIGHT GLASS THAT WAS BROKEN. DRAINED

OIL OUT OF SUMP AND CLEANED, QC. CLOSED OUT.

REPLACED SIGHT GLASS.

NO FAILURE. INSTALLED COUPLING GUARD. CHECKED

TO BE SURE COUPLING WILL NOT RUB WHEN ROTATING.

MACHINERY HAS BEEN FRESHLY PAINETED. NO LEAK,

PAINTERS WERE STILL PAINTING ON MACHINERY. PAINT

HAS SEALED PREVIOUS LEAK.

OIL LEAKAGE/LOOSE CAP

FOUND UNION WAS NOT LEAKING. THE CAP ON A 3/4-

CHECK VALVE LEADING TO THE SUCTION SIDE OF THE

LUBE OUL PUMP WAS LEAKING. TIGHTENED.

INSTALLED VENT LINE AND VALVE IN THE EMERGENCY

WATER SUPPLY LINE CONNECTING THE FIRE PROTECTION

MAIN TO THE SUCTION LINES OF THE AUX FW PUMPS.

INSTALLED DRAINS ON UNIT 1 TURBINE DRIVER AUX

FW PUMP FOR STEAM EXHAUST, STEAM RING AND TURBINE

CASING.

INSTALLED VENTS AND VALVE IN THE EMERGENCY WATER

SUPPLY LINE CONNECTING THE EMERGENCY MAKE-UP TANK

TO THE SUCTION LINES OF THE AUX FW PMPS.

INSTALLED A VENT ON THE FIRE PROTECTION SYSTEM

SUPPLY HEADER 6- WCMU-108-151

CHECKED GAGE. GAGES WAS IN CAL. AND HAD A STICKER

NO FURTHER WORK REQUIRED.

870207

870207

870220

870302

870304

870316

870526

RTSVDT CLASSIFICATION*

870205 VOID

870225 PMS

1-TDP

1-TDP

1-TDP

2-TDP

2-TDP

54171 TIGHTEN/REDOPE FITTING

48005 1-TDP, EWR 86-553

48003 1-TDP ADD DRAIN LINES

48004 1-TDP EWR 86-554

VOID

VOID

VOID

BL

MD

MD

BL

870615 MD

870716 DC

870716 DC

870716 DC

44338

56858

2-TDP EWR 86-443

CAL/REPLACE GAUGE

870716

870918

DC

GAUGE

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY GAUGE - GAUGE REPLACEMENT OR CALIBRATION

DC - DESIGN CHANGE FR- POTENTIAL FAILURE TO RUN FS - FAILURE TO START NFF - NON-FUNCTIONAL FAILURE
Table B.1.b. MAINTENANCE RECORDS FOR THE AUXILIARY FEEDWATER SYSTEM MOTOR DRIVEN FEED PUMPS

MODE/MECHANISM(if applicable)

MARK NO. COMPONENT M. R. # PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSIFICATION*

2-MDP-A

2-MDP-B

2-MDP-A

2-MDP-B

2-MDP-B

2-MDP-A

2-MDP-B

2-MDP-A

2-MDP-A

2-MDP-A

2-MDP-B

2-MDP-B

2-MDP-B

2-MDP-A

2-MDP-B

1-MDP-A

1-MDP-B

1-MDP-B

2-MDP-A

2-MDP-B

1-MDP-B

1-MDP-A

1-MDP-A

2-MDP-A

2-MDP-B

1-MDP-B

1-MDP-A

2-MDP-A

2-MOP-B

2-MDP-A

2-MDP-B

1-MDP-B

2-MOP-A

1-MDP-A

PMP MTR

PUMP

PUMP

PMP MTR

PUMP

PMP MTR

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

INSTR

INSTR

PUMP

PUMP

PUMP

PMP MTR

HX

PUMP

PUMP

PUMP

PUMP

PMP MTR

INSTR

HX

INSTR

INSTR

PUMP

PUMP

PUMP

INSTR

PUMP

803091354

20170210

804030936

803091355

804061450

901261800

902050137

902050130

902131327

901091437

809080610

901091438

805080342

903061116

903061115

907030545

907030546

906030500

902111545

901081400

10162020

910030700

910212130

910230640

911042204

912071559

912211400

1040745

1040746

911050725

1160213

1301305

2020715

3011545

CHANGE OIL

HEADBOLTS 1 2 AND 1 6 LEAK

LUBE OIL RES LEVEL INDICATOR BROKE

CHANGE OIL

COUPLING GUARD MISSING

REMOVE HEAT LAMPS

PUMP START NOT SATISFACTORY

PUMP START NOT SATISFACTORY

OIL COOLER END BELL CRACKED

REPACK INBOARD AND OUTBOARD GLANDS

HEAD BOLT LEAKS-NOS. 8. 12, 15, 16, 19

REPACK INBOARD AND OUTBOARD GLANDS

CASING BOLTS 2. 3. 5 E SIDE 2 W SIDE

CHECK ON 6-1-79

CHECK ON 6-1-79

REPACK PUMP

REPACK PUMP

SEALS THROW WATER

MOTOR HEATER NOT WORKING

REPAIR HEATERS

REBUILD SPARE ROTATING ELEMENT

OIL SUMP LEVEL INDICATOR IS BROKE

REPLACE PACKING

REPACK PUMP

NO LEAK OFF THRUST BEARING & PACKING

INSTALL NEW GAUGE

TUBE LEAK

REPLACE OIL PRESS GAUGES

REPLACE OIL PRESS GAUGES

OUTBOARD PUMP PACKING BURNED UP

REPLACE START SWITCH

OIL PRESSURE GAUGE

SWITCH STICKS

NO-LOAD AMPS

CHANGED OIL AND CHECKED BEARINGS

INSTALLED SEALANT MATERIAL

INSTALLED DIPSTICK ARRANGEMENT

CHANGED OIL AND REPLACED BEARING

REINSTALLED GUARD

REMOVED HEAT LAMPS

TIME DELAY TESTED SATISFACTORY

TIME DELAY TESTED SATISFACTORY

REPAIRED COOLER

REPACKED GLANDS

PERFORMED PREVENTATIVE MAINTENANCE

VOID

VOID

RESET AND TESTED AGASTAT

RESET AND TESTED AGASTATS

REPACKED PUMP

REPACKED PUMP

ADJUSTED PACKING

INSTALLED NEW HEATERS - TESTED SAT

INSTALLED NEW HEATERS - TESTED SAT

VOID

ADJUSTED FLOAT VALVE

REPACKED INBOARD PACKING BOX

REPAIRED PUMP

ADJUSTED

INSTALLED NEW GAUGE

COMPLETED REPAIRS

CHECKED CAL AND REPLACED GAUGES

CHECKED CAL AND REPLACED GAUGES

REPACKED

TESTED SAT

GAUGE CHECKED SAT

SWITCH OPERATIONAL

PI CURVE SAT

780330

780330

780404

780406

780407

790129

790207

790209

790324

790324

790430

790502

790511

790619

790621

790709

790710

790720

790910

790910

791002

791003

791021

791031

791106

791211

791223

800106

800106

800128

800128

800131

800211

800318

PMS

BL

MD

PMS

MD

DC

FS

FS

FR

BL

BL

VOID

VOID

PMS

PMS

BL

BL

BL

FS

FS

VOID

MD

BL

BL

MD

GAUGE

FR

GAUGE

GAUGE

MD

MD

GAUGE

MO

PMS

w

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY GAUGE - GAUGE REPLACEMENT OR RECALIBRATION

DC - DESIGN CHANGE FR- FAILURE TO RUN FS - FAILURE TO START
Table B.1.b. (continued)

MODE/MECHANISM(if applicable)

MARK NO. COMPONENT M. R. # PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSIFICATION*

1-MDP-B

2-MOP-A

2-MDP-B

1-MDP-A

2-MDP-A

1-MOP-A

2-MDP-A

1-MOP-B

2-MDP-B

2-MDP-B

2-MDP-B

1-MDP-A

2-MDP-A

1-MDP-A

1-MOP-B

2-MDP-B

1-MDP-A

1-MOP-A

1-MDP-A

1-MDP-B

1-MDP-A

1-MDP-A

1-MDP-B

2-MDP-B

2-MDP-A

1-MDP-B

1-MDP-A

1-MDP-B

1-MDP-B

1-MDP-A

1-MDP-B

1-MDP-B

1-MDP-B

1-MDP-A

PUMP

INSTR

PUMP

PUMP

PUMP

PUMP

VALVE

PMP MTR

PUMP

VALVE

INSTR

PUMP

PUMP

HX

HT EXCH

PUMP

PUMP

PUMP

PUMP

PUMP

HX

PMP MTR

PMP MTR

INSTR

VALVE

PUMP

PUMP

PUMP

PMP MTR

PUMP

INSTR

PMP MTR

PMP MTR

PMP MTR

3011546

4120800

912181500

5020510

4180732

5290447

6181100

7151510

7222155

4161555

11010523

12270930

101080715

101130847

101130846

101080714

101291401

101291403

101291402

101291404

101311306

8271712

102011220

102080500

102111630

102091230

7110909

7110912

8271711

103102255

103050933

12112345

103121811

102270714

NO-LOAD AMPS

GAUGE BROKEN

SPLIT CASING IS LEAKING ON PUMP

OIL LEAK ON INBOARD

OUTBOARD PACKING LEAK

VENTILATION SHIELD MISSING ON MOTOR

REPAIR HANDWHEEL AND STEM

WRONG OIL IN REDUCTION GEAR

PUMP WILL NOT AUTO START

NUT MISSING ON VALVE HANDWHEEL

CALIBRATE

DAMAGE WAS CAUSED BY FREEZING

SUCTION PRESSURE GAUGE MISSING

REPAIR BROKEN LUBE OIL COOLER

HEAD-ON COOLER BROKEN

LOW OIL LEVEL

LUBE OIL COOLER BROKEN

HEAT TRACE LUBE OIL COOLER

HEAT TRACE LUBE OIL COOLER

HEAT TRACE LUBE OIL COOLER

MANUFACTURE GASKET

PERFORM PMS ON MOTOR

UNCOUPLE PUMP FROM MOTOR

REPLACE 2-MDP-B DISCHG PRESS GAUGE

INSPECT VALVE DISC

PERFORM MMP-FW-004

PERFORM PMS

PERFORM PMS

PERFORM PMS ON MOTOR

PUMP WOULD DEVELOP NO DISCHARGE PRESS

REPLACE GAUGE DEFECTIVE ON TESTING

UNCOUPLE MOTOR

ALIGN AND COUPLE PUMP MOTOR

REPAIR FLEX CONDUIT

PI CURVE SAT

ADJUSTED GAUGE POINTER

VOID

INSPECTED BEARINGS

INSTALLED TEFLON PACKING

SHIELD REPLACED

REPLACED GASKET

COMPLETED DRAINING AND REFILLED OIL

TESTED SATISFACTORY

INSTALLED NUT

CAL GAUGES. REPLACED SUCTION GAUGE

FIXED SPLIT CASING

REPLACED MISSING GAUGE WITH CAL ONE

REPLACED GASKET AT HEAD

REMOVED HEAD, BRAZED TOGETHER

OIL LEVEL NORMAL

REPAIRED LUBE OIL COOLER HEADER

HEAT TRACING INSTALLED

HEAT TRACING INSTALLED

HEAT TRACING INSTALLED

REMOVED HEAD

DISASSEMBLED AND REASSEMBLED MOTOR

UNCOUPLED MOTOR FROM PUMP

REPLACED WITH NEW CALIBRATED GAUGE

FURMANITED MANWAY

PMS SERVICE WORK DONE

VOID - DONE ON PREVIOUS MR

VOID - DONE ON PREVIOUS MR

DISASSEMBLED AND ASSEMBLED MOTOR - SAT

VOID.

REPLACED GAUGE

UNCOUPLING MOTOR FROM PUMP

RECOUPLED PUMP TO MOTOR

MADE REPAIRS TO 1-MDP-A

800318

800424

800428

800508

800603

800619

800625

800717

800725

800830

801104

810101

810109

810114

810114

810115

810201

810202

810202

810202

810205

810207

810207

810209

810212

810214

810217

810217

810228

810311

810311

810312

810316

810317

PMS

GAUGE

VOID

MD

BL

MD

MD

MD

FS

MD

GAUGE

FR

GAUGE

FR

FR

MD

FR

DC

DC

DC

BL

PMS

PMS

GAUGE

BL

PMS

VOID

VOID

PMS

VOID

GAUGE

PMS

PMS

MD

4w

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD

DC - DESIGN CHANGE FR- FAILURE TO RUN FS - FAILURE TO START

- MINOR DEFICIENCY GAUGE - GAUGE REPLACEMENT OR RECALIBRATION
Table B.1.b. (continued)

MODE/MECHANISM(if applicable)

MARK NO. COMPONENT M. R. # PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSIFICATION*

1-MDP-A

1-MDP-A

1-MDP-B

1-MDP-A

2-MDP-A

1-MDP-B

1-MDP-A

1-MDP-B

1-MDP-A

1-MDP-A

1-MDP-B

2-MDP-A

1-MDP-A

2-MDP-B

1-MDP-A

1-MDP-B

2-MDP-B

1-MDP-A

2-MDP-A

2-MDP-B

2-MDP-A

2-MDP-B

2-MDP-A

2-MDP-A

2-MDP-B

2-MOP-A

2-MDP-B

1-MOP-B

2-MDP-A

2-MDP-B

2-MDP-A

2-MOP-A

2-MDP-B

2-MDP-A

PUMP

PUMP

PUMP

PUMP

VALVE

INSTR

GAUGE

INSTR

GAUGE

INSTR

INSTR

INSTR

PMP MTR

PUMP

PUMP

PUMP

INSTR

PUMP

PUMP

PUMP

MOTOR

MOTOR

MOTOR

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

TC

8271030

102091231

104011900

104070800

6160900

105030601

105120750

105030600

105120751

105220735

105220737

106020610

12112330

4180731

107090729

107090729

110010720

812291330

111121500

111121502

111121503

111121504

112092200

112081530

112081827

112211101

112150596

112212300

110091534

110091537

7110906

111020615

111020615

112291236

REPAIR GAUGE

PERFORM HMP-FW-004

PACKING GLAND SPRAYING WATER

PACKING LEAKS BOTH ENDS

INSTALL CAP

CHECK CALIBRATION

CALIBRATE GAUGE OR REPLACE

CHECK CALIBRATION

CALIBRATE GAUGE OR REPLACE

PUMP STARTED IN 62

PUMP STARTED IN 66

PRESSURE INDICATOR NEEDS REPLACING

ALIGN AND COUPLE MOTOR TO PUMP

NO OIL PRESSURE

RETUBE BYPASS LINES

RETUBE BYPASS LINE

CALIBRATE GAUGE

OIL LEAK FROM INBOARD PUMP BEARING

BREAK COUPLING FOR ELECT

UNCOUPLE COUPLING

RECONDITION MOTOR

RECONDITION MOTOR

MOTOR LEAKING OIL

COUPLE PUMP TO MOTOR

COUPLE 2-MOP-B

ALIGN PUMP AND MOTOR

OUTBOARD SHAFT SEAL ON PUMP LEAKS

REPACK 38 AFP

PERFORM MMP-P-FW-004

PERFORM MMP-P-FW-004

PERFORM PMS

INSTALL HEAT TRACING

INSTALL HEAT TRACING

REPLACE T/C ON 2-MDP-A

DISASSEMBLED GAUGE

PREVENTIVE MAINTENANCE SERVICE AND C

ADJUSTED PACKING

ADJUSTED PACKING

REMOVED CHICAGO FITTING AND INSTALLED

REPLACED GAUGE

REPLACED GAUGE

REPLACED GAUGE

REPLACED GAUGE

RESET AGASTATS

RESET AGASTATS

INSTALLED NEW GAUGE

VOID - WORK COMPLETED PRIOR TO REC

PACKED STUDS CHECKED OIL PRESSURE

COMPLETE

COMPLETE

CALIBRATED GAUGE

VOID

COMPLETED

COMPLETED

VOID

VOID

FIXED OIL LEAK, SATISFACTORY

RECOUPLED PUMP

COUPLED

ALIGNED COUPLING

REPLACED, UNCOUPLED

COMPLETED

VOID

VOID

VOID

INSTALLED HEAT TRACE, SATISFACTORY

INSTALLED HEAT TRACE, SATISFACTORY

REPLACED THERMO READING, SATISFACTORY

810323

810328

810403

810410

810418

810515

810515

810515

810515

810522

810522

810602

810611

810616

810925

810925

811006

811028

811114

811114

811116

811116

811210

811211

811211

811229

811229

820104

820105

820105

820106

820112

820112

820221

GAUGE

PMS

BL

BL

BL

GAUGE

GAUGE

GAUGE

GAUGE

FS

FS

GAUGE

VOID

FR

PMS

PMS

GAUGE

VOID

PMS

PMS

VOID

VOID

MD

PMS

PMS

PMS

BL

BL

VOID

VOID

VOID

DC

DC

GAUGE

L

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY GAUGE - GAUGE REPLACEMENT OR RECALIBRATION

DC - DESIGN CHANGE FR- FAILURE TO RUN FS - FAILURE TO START
Table B.1.b. (continued)

MODE/MECHANISM(if applicable)

MARK NO. COMPONENT M. R. # PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSIFICATION*

2-MDP-A

2-MDP-B

1-MDP-B

2-MDP-B

2-MDP-B

1-MDP-A

1-MDP-B

1-MDP-B

1-MDP-B

1-MDP-A

1-MDP-B

2-MDP-B

2-MDP-A

1-MDP-A

2-MDP-A

2-MDP-A

1-MDP-B

2-MDP-B

1-MDP-A

1-MDP-A

1-MDP-B

1-MDP-A

2-MDP-A

1-MDP-B

1-MDP-B

2-MDP-B

2-MDP-B

2-MDP-A

1-MDP-A

1-MDP-A

1-MDP-B

1-MDP-B

1-MDP-A

1-MDP-B

MOTOR

MOTOR

PUMP

PUMP

PUMP

MOTOR

MOTOR

PUMP

PUMP

PUMP

PUMP

INSTR

MOTOR

MOTOR

PUMP

PUMP

PUMP

PMP MTR

GAUGE

PUMP

GAUGE

INSTR

INSTR

PUMP

PUMP

VALVE

VALVE

GAUGE

PUMP

VALVE

VALVE

PUMP

PUMP

PUMP

203050957

203050956

111110340

202090532

202090531

203200519

203110845

203130335

203092235

203261300

204110408

206200426

206022605

206022599

208020025

209011502

209110240

210101905

210141054

210050528

210141056

211102352

211102348

212071150

212071930

212070836

212070835

212141458

302102307

302141430

302141431

304110429

304011411

304011433

BRIDGE MEGGER & RUN PI CURVE

BRIDGE MEGGER & RUN PI CURVE

BEARING VIBRATION PUMP

NO GUARD ON COUPLING

CASING LEAK

MOTOR WAS SPRAYED WITH STEAM

UNCOUPLE PUMP

EXCESSIVE VIBRATION PUMP

INBOARD BEARING HAS HIGH VIBRATION

DETERMINE FAILURE OF PUMP

HIGH VIBRATION POINT 15.1B

OIL LEVEL GAUGE HAS BEEN REMOVED

FW-SV-E/A1

FW-SV-E/A1

COVER MISSING - REPLACE

COUPLING GUARD MISSING, REPLACE

BEARING ON PUMP IS LEAKING

BRIDGE MEGGAR PI CURVE MOTOR

REPLACE OIL PRESSURE GAUGES

FW LEAK UPSTREAM OF LUBE OIL COOLER

REPLACE OIL PRESSURE GAUGES

CALIBRATE BEARING OIL PRESSURE

CALIBRATE BEARING OIL PRESSURE

REPACK PUMP

PUMP NEEDS TO BE REPACKED

PACKING LEAK

PACKING LEAK

INSTALL GAUGE

INBOARD PACKING NEEDS ADJUSTED

VALVE EXTREMELY HARD TO CYCLE

VALVE EXTREMELY HARD TO CYCLE

INBOARD GLAND HAS EXCESSIVE LEAKAGE

TEN YEAR HYDRO

TEN YEAR HYDRO

BRIDGED & MEGGERED MOTOR 820305 PMS

BRIDGED & MEGGERED MOTOR 820305 PMS

REPLACED INBOARD BEARING 820309 FR

INSTALLED COUPLING GUARD 820311 MD

TIGHTENED BOLTING 820311 BL

PERFORMED PI CURVE 820320 FS

VIBRATION RODS INDICATE MOTOR/DKP, SAT 820322 PMS

VOID - HOLDING PREVIOUS MR 820323 VOID

VOID 820324 VOID

BREAKER CLOSED SATISFACTORY 820330 FS

OBSERVED IRD VIBRATION 820517 PMS

NO REPAIR NEEDED 820628 VOID

PERFORMED PMS 820703 PMS

PERFORMED PMS 820704 PMS

REPLACED COVER 820825 MD

FOUND COUPLING GUARD 820913 MD

TIGHTENED UP BOLTS AND 820920 MD

PI CURVE SATISFACTORY 821010 PMS

REPLACED GAUGE WITH 821014 GAUGE

REPAIRED LEAK ON 3/4 PIPE 821014 FR

REPLACED GAUGE WITH 821014 GUAGE

INSTALLED NEW GAUGES 821112 GAUGE

INSTALLED NEW GAUGES 821112 GAUGE

ADDED PACKING 821207 BL

VOID - WORK DONE ON 1212071150 821208 VOID

INSTALLED 7 RINGS OF PACKING 821212 BL

ADJUSTED VALVE PACKING GLAND 821212 BL

REPLACED MISSING 821216 GAUGE

ADJUSTED PACKING 830216 BL

VOID OPERATOR LUBRICATED THE VLV 830217 VOID

VOID OPERATOR LUBRICATED THE VLV 830217 VOID

ADJUSTED PACKING 830420 BL

INSPECTION COMPLETE 830428 PMS

INSPECTION COMPLETE 830428 PMS

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY GAUGE - GAUGE REPLACEMENT OR RECALIBRATION

DC - DESIGN CHANGE FR- FAILURE TO RUN FS - FAILURE TO START
Table B.1.b. (continued)

MODE/MECHANISM(if applicable)

HISTORY SUMMARY MARK NO. COMPONENT M. R. / PROBLEM DESC RTSVDT CLASSIFICATION*

1-MDP-B

1-MDP-A

1-MDP-A

2-MDP-A

2-MDP-B

1-MDP-A

1-MDP-B

2-MDP-A

2-MOP-B

2-MDP-A

2-MDP-B

2-MOP-A

2-MDP-A

2-MDP-B

2-MDP-A

2-MDP-B

2-MDP-A

2-MDP-A

1-MDP-A

1-MDP-B

2-MDP-B

1-MDP-B

2-MOP-A

2-MDP-A

2-MDP-B

2-MDP-B

2-MDP-B

1-MDP-A

1-MDP-A

1-MDP-B

2-MDP-A

2-MDP-B

1-MDP-A

1-MOP-A

GAUGE

VALVE

BOLT

MOTOR

MOTOR

BREAKER

PUMP

PUMP

PUMP

VALVE

MOTOR

PUMP

PUMP

BREAKER

MOTOR

PUMP

MOTO

RELAY

GAUGE

GAUGE

GAUGE

PUMP

PUMP

GUARD

VALVE

PUMP

GAUGE

BOLT

VALVE

VALVE

VALVE

VALVE

MOTOR

PUMP

304271100

305011737

302112151

305060227

305060230

306072125

306110230

304020343

304020342

307080532

306021043

308091500

306080928

306241524

306021042

306080929

309211500

310060105

310201508

310201507

310201557

310221305

310300751

310280742

311071146

309041254

311292204

312040340

401040828

401040832

401040815

401030818

304041600

403030100

DISCH PRESS GAUGE NEEDS TO BE CALI

VALVE COUPLING

1ST BOLT INBOARD ON TOP LEAKS

INSTALL WIRE MESH SCREENS ON MOTOR

INSTALL WIRE MESH SCREWS

RELAY DROP ON A PHSE INST

LUBE OIL LEAK ON OIL COOLER

REPLACE PLASTIC PLUGS ON MOTOR

REPLACE PLASTIC PLUGS ON MTR

PACKING LEAK

DISCONNECT AND RECONNECT

DAMPEN THE PULSATIONS TO GAUGE

UNCOUPLE PUMP

INSP ELEC INTERLOCKS

DISCONNECT + RECONNECT

UNCOUPLE PUMP

REPAIR OR REPLACE MOTOR HEATER

REPLACE 2-MDP-A RELAY

LOCAL LEVEL GAUGE DOESN'T WORK

LUBE OIL RESERVOIR DOESN'T WORK

FIX OR REPLACE LUBE OIL GAUGE

INBOARD SEAL LEAKS 1-MDP-B

INSTALL COUPLING COVER

REINSTALL COUPLING GUARD

PACKING LEAK

INBRD + OUTBRD PMP SEALS LEAK

CALIBRATE DISCHARGE PRESSURE GAUGE

CASING BOLT IS CRACKED

CLEAN AND GREASE VALVE STEM

CLEAN AND GREASE VALVE STEM

CLEAN AND GREASE VALVE STEM

CLEAN AND GREASE VALVE STEM

DISCONNECT MOTOR

ADJUST PACKING

REPLACED GAUGE

REPLACED VARIOUS LEAKING FITTINGS

REPLACED GASKET AND

INSTALLED SCREENS

INSTALLED SCREENS

MOTOR BRIDGED + MEGGERED

TIGHTENED LUBE OIL

NO PLUGS NEEDED

NO PLUGS NEEDED

ADJUSTED PACKING GLAND

DISC + INSPECT BEARINGS

INSTALLED VIBRATION DAMPENERS

ALIGNED AND COUPLED PUMP

INSPECTED INTERLOCKS

DISASSEMBLE INSPECT REASSEMBLE

RECOUPLED PUMP

REPLACED HEATER

REPLACED RELAY COIL FAILED

CLEANED UP LEVEL GAUGE

CLEANED UP LEVEL GAUGE

CLEANED UP LEVEL GAUGE

ADJUSTED PACKING

VOID - TO BE COMPLETED ON 0310280742

INSTALLED COUPLING GUARD

ADJUSTED PACKING GLAND

VOID

CHECKED CALIBRATION OF GAUGE

DETORQUED

CLEANED & LUBRICATED

CLEANED & LUBRICATED

CLEANED & LUBRICATED

CLEANED & LUBRICATED

VOID-COMPLETED ON MR 1307012547

ADJUSTED PACKING GLAND

830428

830511

830525

830531

830531

830611

830621

830710

830710

830724

830730

830811

830815

830815

830822

830906

831006

831012

831027

831027

831027

831029

831101

831102

831111

831202

831205

831209

840109

840109

840109

840109

840118

840303

GAUGE

BL

BL

MD

MO

FS

MD

VOID

VOID

BL

PMS

DC

PMS

PMS

PMS

PMS

FS

FS

MD

MD

MD

BL

VOID

MD

BL

VOID

GAUGE

MD

PMS

PMS

PMS

PMS

VOID

BL

-J

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED

DC - DESIGN CHANGE FR- FAILURE TO RUN FS - FAILURE TO START

MD - MINOR DEFICIENCY GAUGE - GAUGE REPLACEMENT OR RECALIBRATION
Table B.I.b. (continued)

MARK NO.

2-MDP-B

2-MOP-B

1-MDP-A

1-MDP-B

1-MDP-A

2-MOP-A

2-MDP-B

1-MDP-B

2-MDP-B

2-MOP-A

2-MDP-B

1-MDP-A

1-MDP-B

1-MDP-A

1-MDP-A

1-MDP-A

2-MDP-B

2-MOP-B

2-MDP-A

1-MDP-A

COMPONENT

MOTOR

PUMP

VALVE

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

VALVE

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

M. R. #

308310600

404011513

404141200

405081516

405081515

405081536

405081535

407161400

311161040

408010723

312070509

5707

5706

10303

10304

10300

11952

02703

03088

13467

PROBLEM OESC

PLACE SIGHTGLASS ON OUTBRD MTR

REPACK PACKING GLAND

BODY TO BONNET LEAK

INSPECT INSULATION AT MOTOR

INSPECT INSULATION AT MOTOR

INSPECT INSULATION AT MOTOR

INSPECT INSULATION AT MOTOR

COUPLE BOLTS/NUTS CROSS THREADED

REPLACE OUTBOARD BEARING SIGHT GLASS

REPLACE BREAKER SPRING/COTTER PIN

BROKEN STEM

UNCOUPLE AND RECOUPLE

UNCOUPLE/RECOUPLE

INBOARD PACKING LEAK 1-MDP-A

ADJUST OUTBOARD PACKING LEAK

RESERVOIR INDICATOR CAP

MISSING

ADJUST PACKING LEAK W/PMP RUNN

REPACK PUMP

PIN AND SPRING 25-14

REPAIR/REPLACE OIL SIGHT GLASS

MODE/MECHANISM(if app1icable)

HISTORY SUMMARY

VOID COMP ON MR2311161040

REPACKED PUMP

INSTALLED NEW SEAL RING

ADDED INSULATION TO MOTOR LEADS FOR

INSPECTED LEADS TAPED FOR

INSPECTED MOTOR LEADS TAPED FOR

INSPECTED AND TAPED MOTOR LEADS

REPAIRED COUPLING GUARD AND

CHECK FOR LEVEL GAUGE

VOID - COMPLETED ON WO 003088

VOID - TO BE COMPLETED ON WO 001471

VOID - WORK NOT TO BE PERFORMED THIS OUTAGE.

VOID - WORK NOT TO BE PERFORMED THIS OUTAGE.

ADJUSTED INBOARD PACKING GLAND 1 FLAT ON GLAND

NUTS.

ADJUSTED OUTBOARD PACKING GALND 1 FLAT ON GLAND

NUTS.

NEED CAP IN ORDER TO FIX. CAPS ALL IN PLACE ON AUX

FEED PUMPS.

ADJUSTED PACKING

VOID--NO PROBLEM EXISTS.

VOID TO BE COMPLETED ON WO 12924

REPLACE SIGHTGLASS TUBE 1/2-X2 LONG SIGHT GLASS

USED FROM PIECE IN SPARE PARTS CAGE IN MACHINE

SHOP.

WORK PERFORMED BY AUTOMATION AND CONTROL.

FOUND TRIP FUSES 25A5/25A6 PULLED CAUSING

2-MOP-A NOT TO AUTO START WHEN REQUIRED.

WORK PERFORMED BY AUTOMATION CONTROL/FOUND TRIP

FUSES FOR 2585/2506 PULLED CAUSING 2-MDP-B NOT

TO AUTO START WHEN REQUIRED 5/10/85.

REMOVED BAD HEATER FROM MOTOR -NO STOCK ITEMHEATER ORDERED 3/25/85. REPLACED DEFECTIVE

HEATER, TEST SAT.

RTSVDT

840403

840403

840417

840514

840517

840517

840517

840727

840809

840811

840817

841113

841113

841207

841207

850118

850107

850301

850306

850312

CLASSIFICATION*

VOID

BL

BL

PMS

PMS

PMS

PMS

MD

MD

VOID

VOID

VOID

VOID

BL

BL

MD

BL

VOID

VOID

MD

00

2-MOP-A

2-MOP-B

2-MDP-B

20053 INVEST/REPAIR PUMP 2-MDP-A

20076 2-MDP-B NO AUTO START

15531 2-MOP-B CHECK HEATERS

850517 NAF

850620 NAF

850712 FS

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY GAUGE - GAUGE REPLACEMENT OR RECALIBRATION

DC - DESIGN CHANGE FR- FAILURE TO RUN FS - FAILURE TO START NAF - NOT AN AGING FAILURE (MAINTENANCE ERROR)
Table B.1.b. (continued)

MARK NO.

2-MDP-A

1-MDP-A

1-MOP-A

1-MDP-B

1-MDP-B

1-MDP-B

2-MOP-B

2-MDP-B

w 1-MOP-B

I

'0

2-MDP-A

2-MDP-A

2-MDP-A

2-MDP-B

1-MDP-B

1-MDP-A

COMPONENT

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

M. R. # PROBLEM DESC

01077 10 YR ISI HYDRO TEST AF PUMP

13371 REPAIR INBOARD/OUTBOARD

LEAKAGE

6020 1-MDP-A CHANGE BEARINGS

6019 1-MDP-B

DISCONNECTINSPECT,RECONNECT

23128 UNCLOG DRAIN LINE 1-MDP-B

23127 ADJUST PACKING/REMOVE EDCTR ON

PUMP CSG

27629 REPAIR EXCESS INBOARD VIBRATIONS

28864 ADJUST PACKING GLANDS

26260 REPACK PUMP

28853 ADJUST PACKING GLANDS

26971 REPLACE PKG BLND BOLTS

MODE/MECHANISM(if applicable)

HISTORY SUMMARY

VOID-WORK NOT REQUIRED

RAN PUMP. NEEDED REPACKING. REMOVED PACKING INBD/

OUTBD ENDS. CLEAN/INSPECT GLAND STUDS NUTS WASHERS

SHAFT SLEEVE CONDITION AS PER PROCEDURE. REPACKED

WITH NEW PACKING WITH

VOID - NOT REQUIRED.

VOID - NOT REQUIRED.

DISCONNECTED LINE AND BLEW OUT WITH AIR HOSE.

ADJUSTED OUT BOARD END. REMOVED PIPING. CAPED

2 OPEN HOLES WITH 1/2 PIP CAPS 3/4 WRO

SUBMITTED TO REPACK.

OPS RAN PUMP WITH DISCHARGE CLOSE AND RECEIVED

HIGH VIBRATIONS ON INBOARD BEARING. SHIFT

SUPERVISOR WANTED TO PULL COUPLING GUARD AND

INSPECT COUPLING.

THE PACKING HAS A FREE FLOW LEAK-OFF, AN

ADJUSTMENT TO A DRIP WILL CAUSE THE STUFFING

BOX TO OVERHEAT LEFT AS IS.

LEAK MECHANISM/WORN PACKING

REMOVED OLD PACKING, INSTALLED NEW 1/2 - GARLOCK

PACKING. ADJUSTED WITH PIMP RUNNING SAT.

VOID COMPLETED ON WO 26971.

CLEANED OUT CATCH BASIN, DISCONNECTED LINES,

CLEANED DIRT FROM THEM AND RECONNECTED.

DRAIN CLOGGED/DIRT

OIL ADDED 5/6/86 OUTBOARD BEARING AMER. IND 58 OIL

OIL ADDED IN OUTBOARD BEARING 5/6/86 AMERICAN

IND 58 OIL.

REPACKED PUMP AGIAN AFTER PREVIOUS PACKING HAD

BEEN SMOKED . PASSED PT.

REMOVED TAPE AND FOUND CABLE A WAS BRAKING. WE

REPLACED THE LUG AND RAYCHEM ALL THREE OF THE

LEADS WITH NM CK-72.

RTSVDT CLASSIFICATION*

850726 VOID

850731 BL

850802

850802

851015

851106

VOID

VOID

MD

BL

851210 NAF

860211 BL

860409 BL

860423 VOID

860502 MD

34892

34891

26973

37002

2-MDP-A ADD OIL

2-MDP-B ADD OIL

P-REPACK PUMP

1-MDP-A EWR 86-174

860510

860510

860611

860620

MD

MD

BL

PMS

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY GAUGE - GAUGE REPLACEMENT OR RECALIBRATION

DC - DESIGN CHANGE FR- FAILURE TO RUN FS - FAILURE TO START NAF - NOT AN AGING FAILURE (MAINTENANCE ERROR)
Table B.1.b. (continued)

MARK NO.

1-MDP-B

1-MDP-A

1-MDP-A

1-MOP-B

1-MDP-B

1-MDP-B

COMPONENT

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

M. R. # PROBLEM DESC

37003 1-MOP-B EWR 86-174

26972 P-REPLACE GLAND BOLTS/REPACK

36782 IMPLEMENT EWR 85-544

34951 1-MDP-B REPAIR CONDUIT

36783 PERFORM EWR 85-544

38277 REPACK PUMP

35286 UNPLUG THE PUMP BASE

39854 1-MDP-A MOTOR WET

39853 1-MOP-B MOTOR WET

35287 ADJUST/REPACK PUMP

38610 REFURBISH ROTATING ASSY.

42940 REPAIR BEARING/LEAKOFF LINE

45005 2-MDP-A RAYCHEM CABLE LEADS

MODE/MECHANISM(if applicable)

HISTORY SUMMARY

REMOVED ALL TAPE AND CLEANED THE CABLE WITH A-2

CABLE PREPARATION KIT THEN REPLACED THE TAPE WITH

RAYCHEM SPLICE KIT NM CK-IL.

BAD THREADS/NORMAL WEAR

DO NOT NEED TO REPLACE AND SAVE STUDS AND NUTS FOR

ENGINEERING AS PER TEL CONVERSATION. UNCLOGGED

DRAIN.

REMOVE LINE FAILURE/UNNEEDED

REMOVE PIPE SUPPORT AS PER EWR FLUSH AND SUBMIT

SERVICE REQUEST TO REPAINT.

CONDUIT BROKEN/ABUSE - SAT ON

REPAIRED CONDUIT CHECKED RESISTANCE ON RTD, OK.

REMOVE LINE FAILURE/UNNEEDED

REMOVE PIPE SUPPORT AND GRIND FLUSH AS PER EWR.

SUBMIT SERVICE TO PAINT SURFACES.

LEAKING PKG FAILURE/BURNED PACKING

REMOVED 6 RINGS OLD PACKING, REPLACED WITH 6 RINGS

1/2 - GARLOCK, TEST RUN PMP PT SAT.

CLEANED DRAIN LINES ON PUMP WITH A ROD.

PERFORM PI CURVE ON MOTOR WINDINGS, TESTED

SATISFACTORY.

PERFORMED PI CURVE ON MOTOR WINDING.

VOID - COMPLETED ON WO 026972.

ROTOR ASSY HAS BEEN REFURBISHED AND IS LOCATED

REMOVED OLD PACKING - 8 RINGS - AND INSTALLED

GARLOCK 98 - 7 RINGS-. INSTALLED GLAND NUTS FINGER

TIGHT - SLIGHTLY SNUGGED-. TSTS RAN PUMP. ADJUSTED

PACKING GLAND SAT. LEAK OFF

VOID RAYCHEM NOT NEEDED, ENG. HAS ACCEPTED

TAPE-UP.

RTSVDT CLASSIFICATION*

860620 MD

860708 MD

860710 PMS

860710

860710

MD

MD

860711 BL

0

1-MDP-A

1-MDP-A

1-MDP-B

1-MDP-A

2-MDP-A

1-MOP-B

860804

860826

860826

860828

861001

861011

MD

FS

FS

VOID

PMS

BL

2-MDP-A 861110 VOID

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY GAUGE - GAUGE REPLACEMENT OR RECALIBRATION

DC - DESIGN CHANGE FR- FAILURE TO RUN FS - FAILURE TO START
Table B.1.b. (continued)

MARK NO.

1-MDP-A

1-MDP-B

1-MDP-A

1-MDP-B

1-MDP-B

1-MOP-B

COMPONENT

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

M. R. 1 PROBLEM DESC

46435 CALIBRATE/REPLACE GAUGE

46436 CALIBRATE/REPLACE GAUGE

45559 CLEAN DRAIN LINE

35597 P-UNCLOG DRN/REPK/REPL STUDS

47744 REMOVE/INSTALL OLD-DOWN BOLTS

49510 1-MDP-B INSPECT BEARINGS

48408 UNCOUPLE/RECOUPLE PUMP

43431 REMOVE AND REPLACE COUPLING PART

50038 OVERHAUL PUMP

49133 UNCOUPLE PMP MOTOR

49122 ENG EVAL HIGH VIPES PT-15.1A

50003 CHANGE OIL IN CENTRAL LUBE SYSTEM

50816 ADJUST PACKING

50637 REPLACE LUBE OIL COOLER

MODE/MECHANISM(if applicable)

HISTORY SUMMARY

WEAR/

REPLACED GAUGE WITH NEW 0-601 GAUGE.

WEAR/VIBRATION

REPLACED GAUGE WITH NEW 0-60# GAUGE.

LINE PLUGGED/FOREIGN MATTER IN LINE

CLEANED DRAIN LINE BY INSERTING WIRE INTO LINE.

LINE FLOWED FREELY WATCHED IT FOR 10 MINUTES.

UNCLOG DRAIN PIPE. REPACKED PUMP. REPLACED GLAND

STUDS RAN PUMP ADJUSTED PACKING.

REMOVED MOTOR HOLD DOWN BOLTS ONE AT A TIME.

CLEANED FEL-PRO REINSTALLED MOTOR HOLD DOWN BOLTS.

TORQUED TO 110 FT.LBS. WORKED WITH

WORN/BEARINGS

REMOVED OUTBOARD BEARING FOR INSPECTION/FOUND

READING OUT OF TOLERANCE BY APPROX .01. AMER. IND

#68 REASSEMBLED MOTOR. TOOK

ALIGNED PUMP TIR .0025 RECOUPLED.

VOID ORDERED PARTS ARRIVED IN TIME NOT TO HAVE

TO USE UNIT 2 PARTS.

VIBRATION/EXCESS VIBRATION AND WEAR.

FOUND THE PUMP UNCOUPLED AND THE BEARING HOUSING

COVER AND HOUSING TOP'S REMOVED.

REMOVED THE STUFFING BOX EXTENSIONS.

PUMP WAS OVERHAULED AND MOTOR ALIGNED AND

RECOUPLED ON WO 52038 3/3/87. UNCOUPLED 2/2/87.

VOID TO 52038.

CHANGED OIL IN CENTRAL LUBE SYSTEMS ON 2-MDP-B

MOTOR DRIVEN AUX FEED PUMP. FLUSHED SYSTEM WITH

CLEAN OIL AND REFILLED TO OIL LEVEL.

LEAKING/ADJUSTMENT

ADJUSTED PACKING. OUTBOARD PACKING NEEDS TO BE

REPACKED.

VOID RECENT OIL ANALYSIS REVEALS APPARENT COOLER

LEAKAGE

RTSVDT CLASSIFICATION*

861216

861216

861218

870108

870116

GAUGE

GAUGE

MD

BL

MD

870212 PMS

1-MDP-B

2-MOP-B

w 2-MDP-A

870212

870214

870303

870304

870309

870309

PMS

VOID

PMS

PMS

VOID

PMS

2-MDP-A

2-MDP-A

2-MDP-B

2-MOP-A

2-MDP-B

870314 BL

870317 VOID

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED

DC - DESIGN CHANGE FR- FAILURE TO RUN FS - FAILURE TO START

MD - MINOR DEFICIENCY GAUGE - GAUGE REPLACEMENT OR RECALIBRATION
Table B.1.b. (continued)

MARK NO.

1-MOP-A

2-MDP-A

2-MDP-B

2-MDP-A

2-MOP-A

2-MDP-A

2-MDP-A

COMPONENT

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

PUMP

M. R. I

50699

51215

50289

51214

PROBLEM DESC

1-MOP-A ADD OIL AS NEEDED

2-MDP-A REMOVE/REPLACE H. T.

ADD OIL TO BEARINGS

REPLACE/REPAIR LUBE OIL COOLER

w

1-MDP-A

2-MDP-B

2-MDP-A

2-MDP-B

51233 CHANGE OIL

51852 FLUSH OIL SYSTEM

51834 REPACK INBOARD END

51995 1-MDP-A MOTOR OIL FLOW

52246 2-MOP-B REPLACE OIL RESERVOI

51085 -P-REPACK OUTBOARD PACKING GLAND

50818 ADJUST PACKING

51500 2-MOP-B REPLACE SIGHT GLASS

49509 P-REPLACE MOTOR HEATERS

53202 2-MDP-B ADD OIL TO MOTOR

MODE/MECHANISM(if applicable)

HISTORY SUMMARY

ADDED OIL TO INBOARD AND OUTBOARD BEARING, ABOUT

1/2 PINT IN EACH (3/16/87).

REPLACED HEAT TAPE THAT HAD BEEN REMOVED. CHECKED

CHECKED AMPS TO SEE IF TAPE WORKED. 3.0 AMPS.

VOID NO WORK PERFORMED OIL LEVELS ARE SAT.

LEAK/OIL IN WATER/WATER IN OIL.

REMOVED LUBE OIL COOLER AND HYORO WITH 100 PSI

SERVICE AIR. NO LEAKAGE EVIDENT.

REMOVED OLD OIL FROM PUMP AND FLUSHED PUMP WITH

NEW OIL. AFTER FLUSHING THE PUMP. THEN REFILLED

WITH NON PAREIL TURBINE OIL MEDIUM AS REQUESTED.

WATER IN OIL/UNKNOWN.

DRAIN WATER AND OIL FROM INBOARD BEARING HOUSING.

DRAIN WATER AND OIL FROM OUTBOARD ENDBEARING

HOUSING ADDED APPROX 1 GAL.

PACKING BURNT/TOO TIGHT.

REMOVED OLD PACKING AND FOUND THAT IT HAD BEEN

BURNT.

REPLACED PUMP WITH 7 RINGS OF 1/2-GARLOCK 98.

HAD OPS RUN PUMP.

ADDED OIL TO INBOARD AND OUTBOARD MOTOR BEARINGS.

CHECKED FOR OIL LEAKS.

REPLACED SIGHT GLASSES. REPLACED OIL. TEST RAN

SAT 4/14/87

VOID TO 51384.

AS FOUND PACKING LEAKING IN STREAM APPROX. THE

SIZE OF PENCIL LEAD. PRE-OILED BOTH BEARINGS

TIGHTENED PACKING GLAND NUTS ONE HALF OF ONE FLAT

TO DECREASE LEAKAGE TO BROKEN

VOID COMPLETED ON WO#380002275

HEATERS BAD/AGE. REPLACED HTRS

MEGGERED 14 MEGOHMS AMPS .8 1.1 WORKED SAT.

CHANGED OVERLOADS INSTALLED 1O1BL.

LOW LEVEL/UNKNOWN

ADDED OIL TO OUTBOARD BRG. 7 OZ INBOARD WAS SAT.

RTSVDT CLASSIFICATION*

870403 PMS

870403 PMS

870403 MD

870319

870323

870324

870331

PMS

MD

VOID

FR

870410

870414

870414

870416

MD

MD

VOID

BL

2-MDP-B

1-MDP-B

2-MDP-B

870421 VOID

870522 FS

870522 MD

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY GAUGE - GAUGE REPLACEMENT OR RECALIBRATION

DC - DESIGN CHANGE FR- FAILURE TO RUN FS - FAILURE TO START
Table B.1.b. (continued)

MODE/MECHANISM(if applicable)

MARK NO. COMPONENT M. R. # PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSIFICATION*

2-MDP-B PUMP 49544 ENGINEERING EVALUATION VOID PUMP TESTED SAT ON 3-11-87, 4-8-87, AND

5-8-87.

1-MDP-A PUMP 54236 1-MDP-A CLEANED SIGHT GLASS NO ACTUAL FAILURE INVOLVED. CLEANED PAINT OFF OF

SIGHT GLASS FOR SLING RING AND THE ONE FOR OIL

LEVEL ON THE INBOARD END OF MOTOR.

1-MDP-A PUMP 54772 1-MDP-A ADD OIL TO MOTOR ADDED INDUSTRIAL 68 OIL TO INBOARD AND OUTBOARD

BEARINGS TO PROPER LEVELS. NO LEAKS.

2-MDP-B PUMP 54745 2-MDP-B ADD OIL TO MOTOR ADDED OIL TO INBOARD AND OUTBOARD MOTOR BEARINGS.

DID NOT SEE ANY OIL LEAKS OUTSIDE OF MOTOR.

INDUSTRIAL 68 OIL.

1-MDP-A PUMP 54736 INVESTIGATE/REPAIR WORN OUT/OLD AGE

REPLACED GAGE WITH NEW GAGE FROM ATTACHED MATERIAL

REQUISISTION. NEW GAGE WAS TESTED OK.

2-MDP-A PUMP 54737 CAL/REPLACE GAUGE WORN OUT/OLD AGE.

REPLACED GAGE WITH NEW GAGE FROM ATTACHED COPY

OF MATERIAL REQUISITION NEW GAGE WAS TESTED OK.

2-MDP-B PUMP 52414 -P- REPLACE LO COOLER LEAKING OIL/

INSTALL NEW COOLER. AS FOUND- COOLER LEAKING.

WORK PERFORMED-INSTALLED NEW OIL COOLER. AS

LEFT-TEST SAT.

2-MDP-B PUMP 54267 CHANGE OIL FLUSH LINES AS REQD AS FOUND- OIL CLEAN. NO FOREIGN OBJECTS IN

OIL RESERVOIR, NO BEARING MATERIAL PRESENT IN

RESERVOIR OR FILTER. WORK BONE- DRAINED OIL FROM

2-MDP-B PUMP 52248 2-MDP-B REPLACE SIGHT GLASS VOID TO 053124

2-MDP-A PUMP 55679 2-MDP-A ADD OIL ADDED AMER INDUSTRIAL 058. ADDED ABOUT 5 OZ AND

LEVEL CAME UP A LITTLE ABOVE THE HALF WAY MARK.

1-MDP-A PUMP, 48997 ADJUST PACKING GLANDS NO ADJUSTMENT REQUIRED. PROPER LEAK OFF.

2-MDP-B PUMP 53124 2-MDP-B INSTALL SIGHTGLASS REMOVED PLUG AND INSTALLED BULL'S EYE SIGHT GLASS

9/11/87

1-MDP-B PUMP 56885 P-REPLACE MOTOR BEARING OIL CHECKED SIGHT GLASS OIL LEVEL. FOUND OIL LEVEL TO

BE A LITTLE LOW ADDED OIL TO 1-MDP-A INBOARD

MOTOR BEARING. ADDED AMERICAN INDUSTRIAL

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MO - MINOR'DEFICIENCY GAUGE - GAUGE REPLACEMENT OR

DC - DESIGN CHANGE FR- FAILURE TO RUN FS - IYNCIPIENT FAILURE TO START

870529

870625

870714

870714

VOID

MD

MD

MD

870724 GAUGE

870725 GAUGE

870807 FR

870807 PMS

wI

t~)

870811

870819

870903

870916

870929

VOID

MD

BL

MD

MD

CALIBRATION
Table B.1.c. MAINTENANCE RECORDS FOR THE AUXILIARY FEEDWATER SYSTEM 3-INCH MOTOR OPERATED VALVES

NODE/NECHANISM(if applicable)

MARK NO. COMPONENT N. R. # PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSIFICATION*

Z-MOV-A

2-MOV-D

1-NOV-B

1-NOV-C

1-MOV-E

1-MOV-D'

1-MOV-F

1-MOV-B

1-NOV-C

1-MOV-C

1-MOV-D

1-MOV-E

1-MOV-E

1-MOV-F

1-MOV-F

1-MOV-C

1-MOV-E

1-MOV-F

1-MOV-A

1-MOV-A

1-MOV-A

1-MOV-B

1-MOV-D

1-MOV-F

1-MOV-B

1-MOV-D

1-MOV-B

1-MOV-F

2-MOV-A

1-MOV-C

1-MOV-E

1-MOV-F

1-MOV-E

1-MOV-F

NOV

MOV

MOV

NOV

NOV

NOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

NOV

MOV

MOV

MOV

VALVE

VALVE

VALVE

MOV

MOV

803201901

804061950

805011126

805011125

805011123

805011124

805011122

10185580

806010833

10185570

10185560

806010831

10185550

10185540

806022200

806131540

806131542

806131543

805011127

806131538

10185590

806010832

806041005

806041006

806302330

806131541

806131539

809162130

810110135

812140713

812141007

812141008

906071201

906071200

PACKING LEAK

WON'T STAY CLOSED

CLEAN AND INSPECT

CLEAN AND INSPECT

CLEAN AND INSPECT

CLEAN AND INSPECT

CLEAN AND INSPECT

LEAKS BY SEAT

INSPECT SEAT FOR CRACKS

LEAKS BY SEAT

LEAKS BY SEAT

INSPECT SEAT FOR CRACKS

LEAKS BY SEAT

LEAKS BY SEAT

TORQUE SWITCH BAD

DISCONNECT/RECONNECT FOR MECHANICS

DISCONNECT/RECONNECT FOR MECHANICS

DISCONNECT/RECONNECT FOR MECHANICS

CLEAN AND INSPECT

DISCONNECT/RECONNECT FOR MECHANICS

LEAKS BY SEAT

INSPECT SEAT FOR CRACKS

REPAIR OR REPLACE CRACKED SEATS

REPAIR OR REPLACE CRACKED SEAT

BREAKER WILL NOT RESET AND VALVE

DISCONNECT/RECONNECT FOR MECHANICS

DISCONNECT/RECONNECT FOR MECHANICS

VALVE LEAKS THRU-CHECK LIMITS

DID NOT AUTO OPEN

1-MOV-C HAS PACKING LEAK

PACKING LEAKS

PACKING LEAKS

REPLACE JAMMED BOLT ON FLANGE

PACKING LEAK

REPACKED VALVE

ADJUSTED SWITCH

DISCONNECTED/RECONNECTED AND TESTED

DISCONNECTED/RECONNECTED AND TESTED

DISCONNECT/RECONNECTED AND TESTED

CLEANED. INSPECTED AND TESTED

CLEANED. INSPECTED AND TESTED

CUT DISC - LAPPED SEAT

INSPECTED SEAT

CUT DISC - LAPPED SEAT

INSPECTED AND REASSEMBLED VALVE

INSPECTED SEAT

CUT DISC - LAPPED SEAT

INSPECTED VALVE AND REASSEMBLED

REPLACED TORQUE SWITCH

VOID

DISCONNECTED/RECONNECTED - SET LIMITS

VOID

CLEANED AND INSPECTED

RECONNECTED AND TESTED SATISFACTORY

REPLACED SEAT

CHECK VALVE FOR SEATING

REPLACED SEAT RING

REPLACED SEAT RING

REPAIRED - TESTED SATISFACTORY

DISCONNECTED/RECONNECTED - TEST SAT

VOID

CHECKED LIMITS - SATISFACTORY

CHECKED OUT CONTROL CIRCUIT - OK

INSTALLED NEW PACKING

INSTALLED NEW PACKING

INSTALLED NEW PACKING

REPAIRED BOLT

TIGHTENED PACKING GLAND

780330

780407

780527

780527

780527

780602

780602

780604

780604

780604

780604

780604

780604

780604

780605

780616

780616

780616

780627

780627

780629

780629

780629

780629

780706

780710

780814

780918

781015

781222

781222

781222

790611

790611

BL

PG

PMS

PMS

PmS

PMS

PMS

SL

PMS

SL

PMS

PMS

SL

PMS

PG

VOID

PmS

VOID

PMS

PmS

SL

PmS

SL

SL

PG

PmS

VOID

PmS

PG

BL

BL

BL

MD

BL

w

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED ND - MINOR DEFICIENCY SL - SEAT LEAKAGE

DC - DESIGN CHANGE PG - PLUGGING FAILURE SWITCH - NON-FUNCTIONAL FAILURE OF LIMIT SWITCH
Table B.1.c. (continued)

MODE/MECHANISM(if applicable)

MARK NO. COMPONENT M. R. # PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSIFICATION*

1-MOV-A

1-MOV-D

1-MOV-A

2-MOV-D

2-MOV-D

2-MOV-D

1-MOV-E

1-MOV-A

1-MOV-B

1-MOV-C

1-MOV-D

1-MOV-E

1-MOV-F

2-MOV-F

2-MOV-F

1-MOV-E

2-MOV-A

2-MOV-B

2-MOV-C

2-MOV-D

2-MOV-E

2-MOV-F

2-MOV-E

2-MOV-E

2-MOV-E

2-MOV-B

2-MOV-C

2-MOV-A

2-MOV-A

2-MOV-B

2-MOV-C

2-MOV-E

2-MOV-F

2-MOV-F

NOV

MOV

NOV

MOV

MOV

NOV

MOV

MOV

MOV

NOV

NOV

NOV

MOV

NOV

NOV

MOV

NOV

MOV

NOV

NOV

NOV

VALVE

NOV

907031530

909171517

10142910

901251409

911081020

911081355

1061910

1041823

1041830

1041842

1041845

1041825

1041826

1210100

1181431

1061825

3050930

3050931

3050932

3050933

3050934

3050935

1062046

901251410

1062045

901251407

901251408

901251406

4090913

4090914

4090915

4090917

4291230

4090918

REPLACE HANDWHEEL

PACKING LEAK

PERFORM PROCEDURE EMP-P-MOV-45

MOV PMS

SEVERE PACKING LEAK

LIMIT SWITCH NEEDS ADJUSTMENT

MOTOR HOUSING SHATTERED

VALVE LEAKS BY

VALVE LEAKS BY

VALVE LEAKS BY

VALVE LEAKS BY

LEAKS BY SEAT CHECK LIMITS

LEAK BY SEAT CHECK LIMITS

DISCONNECT+RECONNECT FOR MECH

REMOVE STEM NUT FOR MEASUREMENT

DISCONNECT AND RECONNECT POWER

REPACK 2-MOV-A

REPACK 2-MOV-B

REPACK 2-MOV-C

REPACK 2-MOV-D

REPACK 2-MOV-E

REPACK 2-MOV-F

REMOVE MOV FOR USE ON UNIT 1

MOV PMS

DISCONNECT MOV FOR MECHANICS

NOV PMS

MOV PMS

MOV PMS

MOV LEAKS BY

MOV LEAKS BY

MOV LEAKS BY

MOV LEAKS BY

DISASSEMBLE LIMITORQUE FOR INSPECTION

MOV LEAKS BY

REPLACED HANDWHEEL

ADJUSTED PACKING

VOID

COMPLETED AS PER EMP-P-MOV-45

REPACKED VALVE

VOID

REPLACED WITH LIMTORQUE FROM MOV 251

A TORQUE SWITCH

ADJUSTED TORQUE SWITCH

ADJUSTED TORQUE SWITCH

ADJUSTED TORQUE LIMITS

ADJUSTED TORQUE LIMITS

ADJUSTED TORQUE LIMITS

VOID

COMPLETED

MOV REPLACED ON UNIT I

REPACKED VALVE

REPACKED VALVE

REPACKED VALVE

REPACKED VALVE

REPACKED VALVE

REPACKED VALVE

COMPLETED

PERFORMED PMS ON MOV

RECONNECTED AND TESTED MOV

TESTED SATISFACTORY

TESTED SATISFACTORY

COMPLETED

REPACKED VALVE

REPACKED VALVE

REPACKED VALVE

REPACKED VALVE

UNSTUCK

REPACKED VALVE

790808

790919

791023

791106

791110

791217

800107

800119

800119

800119

800119

800119

800119

800124

800124

800219

800307

800307

800307

800307

800307

800307

800323

800325

800325

800410

800410

800411

800509

800509

800509

800509

800509

800509

MD

BL

VOID

PMS

BL

VOID

PG

SWITCH

SWITCH

SWITCH

SWITCH

SWITCH

SWITCH

VOID

PMS

PG

BL

BL

BL

BL

BL

BL

PG

PMS

PMS

PMS

PMS

PMS

BL

BL

BL

BL

PG

BL

w

tU

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY SL - SEAT LEAKAGE

DC - DESIGN CHANGE PG - PLUGGING FAILURE SWITCH - NON-FUNCTIONAL FAILURE OF LIMIT SWITCH
Table B.1.c. (continued)

MODE/MECHANISM(if applicable)

MARK NO. COMPONENT M. R. I PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSIFICATION*

2-MOV-D

2-MOV-A

2-MOV-B

2-MOV-D

2-MOV-F

2-MOV-B

2-MOV-A

2-MOV-D

2-MOV-B

2-MOV-B

2-MOV-B

1-MOV-B

1-MOV-B

1-MOV-B

1-MOV-D

1-MOV-D

1-MOV-F

1-MOV-F

1-MOV-C

1-MOV-E

1-MOV-C

1-MOV-E

1-MOV-F

2-MOV-A

1-MOV-D

1-MOV-A

1-MOV-A

1-MOV-A

1-MOV-E

1-MOV-B

1-MOV-A

1-MOV-D

1-MOV-E

1-MOV-F

VALVE

VALVE

VALVE

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

VALVE

VALVE

MOV

VALVE

VALVE

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

4211429

4280457

4280456

5281601

901251411

7160826

7161130

4090916

8230940

11011730

8230615

905180840

11191101

9070120

9070118

11191102

11191103

9070116

9070119

9070117

10323747

103230748

906180842

104221730

104300145

8081510

103131730

9070121

106100420

101201701

103110840

9241901

109300130

110011750

VALVE OPEN WHEN SHOULD BE SHUT

HANDWHEEL MISSING

HANDWHEEL MISSING

MOV IS SHUT BREAKER IS OPEN

MOV PMS

PACKING LEAK

PACKING LEAK

MOV LEAKS BY

TORQUE SWITCH PROBLEM

MOV WILL NOT OPERATE

VALVE WILL NOT OPEN

LEAKS THROUGH

DISCONNECT AND RECONNECT FOR MECHANICS

PERFORM PMS

PERFORM PMS

DISCONNECT AND RECONNECT FOR MECH

DISCONNECT AND RECONNECT FOR MECHANICS

PERFORM PMS

PERFORM PMS

PERFORM PMS

REPACK VALVE

REPACK VALVE

LEAKS THRU

REPACK, ADJUST PACKING

ADJUST LIMITS

REPAIR LIMIT SWITCH

DISCONNECT/RECONNECT FOR MECHANICS

PERFORM PMS

CHECK CONTROL CIRCUIT FOR POSS GROUND

CONT AND PWR CABLES DETERM FROM OPER

VALVE STIFF

GROUND AND REPAIR WELDS

VALVE HAS BODY BONNET LEAK

MOV INDICATE CLOSED LOCALLY

VALVE OPERATES AS DESIGNED

VOID

VOID

ADJUSTED SWITCH

COMPLETED AS PER ABOVE PROCEDURES

CLEANED VALVE STEM

REPAIRED LEAK

VOID

REPAIRED BROKEN WIRE

REPAIRED LEADS, TEST SWITCH SATISFACTORY

VOID - MRS2011011730

COMPLETED

COMPLETED AS PER EMP-C-MOV-11

PMS COMPLETED

PMS COMPLETED

COMPLETED AS PER EMP-C-MOV-l1

DISCONNECT AND RECONNECT

PERFORMED AS PER PMS

PERFORMED PMS ON VALVE

PERFORMED PMS ON VALVE

REPACKED VALVE

REPACKED VALVE

NEEDED TO BE WIRED UP

COMPLETED

COMPLETED AS PER EMP-C-MOV-63

VOID - PERFORMED ON ANOTHER MR

ADJUSTED LIMITS AS PER PROCEDURE

COMPLETED AS PER PMS PROCEDURE

COMPLETED AS PER EMP-C-MOV-63

VOID - WORK PERFORMED ON ANOTHER MR

COMPLETED

VOID - INSPECTION SHOWS NO WELD REPAIR

REPLACED GASKET

COMPLETED - VALVE DOES NOT WORK SAT

800513

800521

800521

800602

800604

800717

800718

800724

800826

801104

810107

810112

810222

810222

810222

810222

810308

810308

810311

810311

810324

810324

810325

810425

810531

810601

810604

810604

810611

810612

810618

810624

811001

811001

PG

VOID

VOID

PG

PMS

BL

BL

VOID

PG

PG

VOID

SL

PMS

PMS

PMS

PMS

PMS

PMS

PMS

PMS

BL

BL

PG

BL

SWITCH

VOID

PMS

PMS

PG

VOID

PG

VOID

BL

PG

tS)

0o

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY SL - SEAT LEAKAGE

DC - DESIGN CHANGE PG - PLUGGING FAILURE SWITCH - NON-FUNCTIONAL FAILURE OF LIMIT SWITCH
Table B.l.c. (continued)

MODE/MECHANISM(if applicable)

HISTORY SUMMARY MARK NO. COMPONENT M. R. # PROBLEM DESC RTSVDT CLASSIFICATION*

1-MOV-A

1-MOV-E

1-MOV-F

2-MOV-C

2-MOV-C

1-MOV-F

1-MOV-F

1-MOV-C

2-MOV-C

2-MOV-F

2-MOV-E

1-MOV-F

2-MOV-F

2-MOV-F

2-MOV-D

1-MOV-F

1-MOV-F

1-MOV-F

1-MOV-F

1-MOV-F

1-MOV-C

1-MOV-E

1-MOV-E

1-MOV-F

1-MOV-F

2-MOV-A

2-MOV-A

2-MOV-B

2-MOV-B

2-MOV-B

1-MOV-F

2-MOV-BDF

2-MOV-A

2-MOV-A

MOV

MOV

VALVE

VALVE

MOV

VALVE

MOV

INSTR

MOV

VALVE

MOV

MOV

VALVE

VALVE

VALVE

SWITCH

MOV

MOV

VALVE

MOV

VALVE

VALVE

VALVE

VALVE

MOV

VALVE

VALVE

VALVE

VALVE

VALVE

MOV

CONTROL

MOV

MOV

905180841

905180843

112050738

111121519

112211400

201140700

201072020

203201713

204090840

204121330

204092327

205120140

205201502

206090901

204090700

203120415

208140700

208120135

208141901

210130602

210130858

210151232

210141540

210151234

210140101

204150708

203010317

204150711

212101721

212101720

209081016

212172011

212151515

212161045

LEAKS THROUGH

LEAKS THROUGH

VALVE INDICATES INTERMITTENT POSITION

REPAIR GEAR BOX

INTERMEDIATE INDICATION

1-MOV-F FAILS TO INDICATE FULLY

INTERMEDIATE INDICATION ON VALVE

VALVE SHOWS INTERMEDIATE INDICATION

INTERMEDIATE LIGHT

BODY TO BONNET LEAK

BODY TO BONNET

VALVE WOULD NOT CLOSE FULLY

DISCONNECT/RECONNECT FOR MECH DEPT

FURMANITE BODY TO BONNET LEAK

VALVE DOES NOT CLOSE

VALVE CYCLES NORMALLY, HOWEVER, LIGHT

CHANGE LIMITORQUE

VALVE WILL NOT OPERATE BREAKER THERM

VALVE MOVES SLOW PER PT 18.6, INSPECT

VALVE WILL NOT FULLY CLOSE

PACKING LEAK

VALVE HAS SLIGHT PACKING LEAK

ADJUST LIMIT SWITCH

VALVE HAS PACKING LEAK

MOV WILL NOT CLOSE

DISCONNECT/RECONNECT FOR MECHANICS

VALVES LEAK BY WHEN SHUT

DISCONNECT/RECONNECT FOR MECHANICS

DISCONNECT/RECONNECT FOR NECHANICS

OVERHAUL

DISASSEMBLE LIHITORQUE

WHEN LO-LO S/G LEVEL WAS RECEIVED

BODY TO BONNET LEAK

DISCONNECT/RECONNECT FOR MECHANICS

VOID

VOID

LIMITS ADJUSTED, SATISFACTORY

RENEWED BEVEL GEAR

VALVE OPERATES SATISFACTORY

ADJUSTED VALVE, SATISFACTORY

VOID

ADJUSTED LIMITS. CYCLED SATISFACTORY

REPLACED LIMIT SWITCH, TESTED SAT

TIGHTENED BONNET NUTS ON VALVE

VOID

VOID

RECONNECTED, TESTED SAT

VOID

VOID - NO WORK PERFORMED, OPER DIDN'T HO

WORK PERFORMED ON MRS 1208120135

INSTALLED NEW LIMITORQUE

DISCONNECTED/RECONNECTED SATISFACTORY

VOID - COMPLETED ON MR 0208140700

DISCONNECTED/RECONNECTED MOV. SAT

REPACKED VALVE

ADJUSTED PACKING

CYCLED SATISFACTORY

ADJUSTED PACKING

REMACHINED SEAT RING

DISCONNECT/RECONNECT. TESTED SAT

INSPECTED, FOUND NOTHING WRONG

RECONNECTED, TESTED SATISFACTORY

VOID - DUPLICATE WKPERF ON MR 0204150711

MANUFACTURED AND INSTALLED

VOID - NOT ENOUGH LEFT TO REBUILD

REWIRED BREAKERS AS

REPLACED BONNET GASKET

RECONNECTED, TESTED SATISFACTORY

811024

811024

811206

811207

811223

820114

820115

820407

820409

820412

820415

820517

820522

820615

820809

820814

820814

820814

820827

821014

821015

821018

821018

821018

821018

821211

821212

821214

821214

821216

821218

821218

821221

821221

* VOID

VOID

SWITCH

PG

SWITCH

SWITCH

VOID

SWITCH

SWITCH

BL

VOID

VOID

PMS

VOID

VOID

VOID

PG

PG

VOID

PG

BL

BL

SWITCH

BL

PG

PMS

PMS

PMS

VOID

SL

VOID

PG

BL

PMS

.w

-j

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY SL - SEAT LEAKAGE DC - DESIGN CHANGE PG - PLUGGING FAILURE SWITCH - NON-FUNCTIONAL FAILURE OF LIMIT SWITCH
Table B.1.c. (continued)

MODE/MECHANISM(if applicable)

HISTORY SUMMARY MARK NO. COMPONENT M. R. I PROBLEM DESC RTSVDT CLASSIFICATION*

1-MOV-E

1-MOV-C

1-MOV-E

1-MOV-A

1-MOV-F

1-MOV-B

1-MOV-D

1-MOV-F

1-MOV-B

1-MOV-C

1-MOV-D

1-MOV-B

1-MOV-D

1-MOV-E

1-MOV-F

1-MOV-C

2-MOV-F

1-MOV-E

1-MOV-F

2-MOV-C

1-MOV-B

1-MOV-C

1-MOV-E

1-MOV-B

1-MOV-D

1-MOV-F

1-MOV-D

2-MOV-A

2-MOV-C

2-MOV-C

2-MOV-F

2-MOV-E

2-MOV-C

1-MOV-F

MOV

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

MOV

MOV

MOV

MOV

VALVE

VALVE

VALVE

MOV

VALVE

LIMITORQ

MOV

VALVE

MOV

NOV

MOV

MOV

MOV

MOV

MOV

COUPLING

VALVE

MOV

MOV

MOV

MOV

VALVE

303100215

302131114

302131004

302131117

302131001

302131115

302131111

302131109

303162000

303162001

303162002

304071316

304072030

304072057

304072101

304230521

304240145

304130900

304130905

304230659

304260408

304260411

304260421

305061620

305061618

305061617

305111830

306061519

305131902

304231524

307050610

308120142

306121830

210130601

AGASTAT CONTACT IS STICKING

VALVE LEAK BY

PACKING LEAK

VALVE LEAKS BY

PACKING LEAK

VALVE LEAKS BY

VALVE LEAKS BY

VALVE LEAKS BY

DISC/RECON FOR MECHS

DISC/RECON FOR MECHS

DISC/RECON FOR MECHS

PACKING LEAK

VALVE OPENS BUT WILL NOT CLOSE

VALVE LEAKS

VALVE LEAKS BY SEAT

VALVE MOTOR IS LOOSE

VLV WHEN CLOSED CAME BACK OPEN

VALVE LEAKS THRU

VALVE LEAKS THRU

DRIVE MECHANISM BROKEN

OPENING TIME IS GREATER THAN 25 PERC

OPENING TIME IS GREATER THAN 25 PERC

OPENING TIME IS GREATER THAN 25 PERC

REPLACE OVERLOAD ASSEMBLY

REPLACE OVERLOAD

REPLACE OVERLOAD

VALVE CLOSES

FLEXIBLE COUPLING LEAKS

MOV EXCEEDS INVESTIGATE CAUSE

INSTALL LOCAL INDICATING ROD ON MOV

MOV WONT STAY CLOSED

2-MOV-E HAS BODY TO BONNET LEAK

STRK TIME GREATER THAN 25 PERC

VALVE WILL NOT GO FULLY CLOSED

ADJUSTED MICROSWITCH

COMPLETED

COMPLETED

OVERHAULED VALVE

VOID COMP UNDER MR 302131109

OVHL VALVE + REPLACED

OVHL VALVE + REPACKED

OVHL VALVE

VOID DISC/REC PERF BY DANIELS

VALVE RECONNECTED

VOID DISC/REC PERF BY DANIELS

ADJUSTED PACKING

ADJUSTED LIMITS

INVESTIGATE LEAK

INVESTIGATE LEAK

DISCONNECTED AND

VALVE CYCLED SAT

VALVE CYCLED SAT

VALVE CYCLED SAT

REPLACED DESTROYED MOV WITH NEW MOV

PT 18.6 UPDATED

PT 18.6 UPDATED

PT 18.6 UPDATED

REPLACED OVERLOADS

REPLACED OVERLOADS

REPLACED OVERLOADS

CYCLED VALVE

REPLACED LEAKING TUBE

VOID DUPLICATE MR

FABRICATED + INSTALLED INDICATOR

CYCLED SAT

TIGHTENED ALL NUTS

ENGINEERING TO EVALUATE STROKE

VOID

830313

830314

830314

830315

830318

830321

830321

830321

830406

830406

830406

830411

830411

830417

830417

830423

830424

830426

830426

830426

830505

830505

830505

830511

830511

830511

830520

830608

830616

830810

830819

830822

830913

831019

PG

SL

BL

SL

VOID

SL

SL

SL

VOID

PMS

VOID

BL

PG

SL

SL

PG

PG

PMS

PMS

PG

MD

MD

MD

DC

DC

DC

PG

MD

VOID

PMS

PG

BL

MD

VOID

w

Io

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY SL - SEAT LEAKAGE DC - DESIGN CHANGE PG - PLUGGING FAILURE SWITCH - NON-FUNCTIONAL FAILURE OF LIMIT SWITCH
Table B.1.c. (continued)

MODE/MECHANISM(if applicable)

HISTORY SUMMARY MARK NO. COMPONENT M. R. # PROBLEM DESC RTSVDT CLASSIFICATION*

2-MOV-A

2-MOV-C

2-MOV-E

1-MOV-B

1-MOV-C

1-MOV-D

2-MOV-B

2-MOV-f

2-MOV-F

1-MOV-C

1-MOV-E

2-MOV-A

2-MOV-A

2-MOV-A

2-MOV-B

2-MOV-B

2-MOV-B

2-MOV-B

2-MOV-C

2-MOV-C

2-MOV-D

2-MOV-D

2-MOV-f

2-MOV-E

2-MOV-E

2-MOV-E

2-MOV-F

2-MOV-F

1-MOV-E

2-MOV-F

1-MOV-F

1-MOV-F

1-MOV-F

1-MOV-B

MOV

MOV

MOV

MOV

MOV

MOV

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

MOV

AGASTAT

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

AGASTAT

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

312120912

312120910

312120911

401271144

410271145

402251534

403140646

403131424

403140648

403290922

403290924

403140728

403140645

403311426

404010900

403140729

403310711

403310712

403131423

308061207

403310710

403300845

308061209

404011400

403140647

403140730

403140731

403300847

403290930

401131605

403290931

404142132

404142131

403290927

WRONG PLUG IN BOTTOM OF MOV

WRONG PLUG IN BOTTOM OF MOV

WRONG PLUG IN BOTTOM OF MOV

LIFT LEAD AS REQUESTED BY OPS

LIFT LEAD AS REQUESTED BY OPERATORS

LIMIT SWITCH DOES NOT MAKEUP

DISCONNECT AND RECONNECT VALVE

ELECTRICAL DISCONNECT/RECONNECT VALVE

DISCONNECT AND RECONNECT VALVE

OPEN, INSPECT, REPAIR

OPEN, INSPECT, AND REPAIR

SUSPECT VALVE LEAKING AT SEAT

DISCONNECT AND RECONNECT VALVE

BODY TO BONNET LEAK

CLEAN AGASTAT

SUSPECT VALVE LEAKING BY SEAT

OPEN, INSPECT, REPAIR

DISCONNECT/RECONNECT FOR MAINTENANCE

ELECTRICAL DISCONNECT/RECONNECT VALVE

REPAIR VALVE

OPEN, INSPECT, AND REPAIR.

DISCONNECT AND RECONNECT VALVE

REPAIR VALVE

CLEAN AGASTAT

DISCONNECT AND RECONNECT VALVE

SUSPECT VALVE LEAKING BY SEAT

SUSPECT VALVE LEAKING BY SEAT

DISCONNECT AND RECONNECT MOV

ELECTRICAL DISCONNECT AND RECONNECT

VALVE OPENS

ELECTRICAL DISCONNECT AND RECONNECT

REPAIR PACKING LEAK

REPAIR BODY TO BONNET LEAK

ELECTRICAL DISCONNECT AND RECONNECT

CORRECT PLUG INSTALLED

CORRECT PLUG INSTALLED

CORRECT PLUG INSTALLED

VOID

VOID

CYCLED VALVE

ADJUSTED LIMITS, RECONNECTED LOAD,

RECONNECTED LOAD CHECK BRIDGE & MEGGER

RECONNECTED LOAD, CHECKED BRIDGE & MEG

VOID - VERIFIED NO LEAK BY

VOID - VERIFIED NO LEAK BY

DISASSEMBLED VALVE CRACKED

DISCONNECTED AND RECONNECTED AS

TORQUED BOLTS

CLEANED AGASTAT AND OPERATED

DISASSEMBLED VALVE CRACKED

DISSAMBLED VALVE TACK WELDED PLUG

DISCONNECTED AND RECONNECTED MOTOR

DISCONNECTED AND RECONNECTED AS

DISASSEMBLED VALVE CRACKED

CLEANED FOR TACKING TACH WELD PLUG

DISCONNECTED/RECONNECTED MOTOR

DISASSEMBLED VALVE CRACKED

CLEANED AGASTAT AND OPERATED SAT

DISCONNECTED AND RECONNECTED AND

DISASSEMBLED VALVE CRACKED

DISASSEMBLED VALVE CRACKED

DISCONNECTED AND RECONNECTED

VOID - NOT TO BE WORKED

AGASTAT STICKING

DISCONNECTED AND RECONNECTED

VOID - COMPLETED ON MR 1404142131

TORQUED BODY TO BONNET

VOID - NO WORK NEEDS TO BE PERFORMED

840107

840107

840107

840130

840130

840309

840326

840330

840330

840404

840404

840406

840406

840406

840406

840406

840406

840406

840406

840406

840406

840406

840406

840406

840406

840406

840406

840406

840410

840412

840417

840417

840417

840419

MD

MD

MD

VOID

VOID

SWITCH

PMS

PMS

PMS

VOID

VOID

SL

PMS

BL

PMS

SL

MD

PMS

PMS

SL

MD

PMS

SL

PMS

PMS

SL

SL

PMS

VOID

PG

PMS

VOID

BL

VOID

w

k"I

%O

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY SL - SEAT LEAKAGE DC - DESIGN CHANGE PG - PLUGGING FAILURE SWITCH - NON-FUNCTIONAL FAILURE OF LIMIT SWITCH
Table B.I.c. (continued)

MODE/MECHANISM(if applicable)

MARK NO. COMPONENT M. R. I PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSIFICATION*

1-MOV-C

1-MOV-D

1-MOV-A

1-MOV-A

I-MOV-E

1-MOV-D

1-MOV-D

1-MOV-D

1-MOV-D

1-MOV-F

1-MOV-A

1-MOV-D

1-MOV-A

1-MOV-B

1-MOV-C

1-MOV-D

1-MOV-E

1-MOV-F

1-MOV-D

2-MOV-A

2-MOV-B

2-MOV-B

2-MOV-C

2-MOV-D

2-MOV-D

2-MOV-E

2-MOV-E

2-MOV-F

2-MOV-F

2-MOV-A

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

BREAKER

BREAKER

BREAKER

BREAKER

BREAKER

BREAKER

BREAKER

BREAKER

BREAKER

VALVE

BREAKER

BREAKER

VALVE

BREAKER

VALVE

VALVE

VALVE

MOV

MOV

403290928 ELECTRICAL DISCONNECT AND RECONNECT

403290932 ELECTRICAL DISCONNECT AND RECONNECT.

403290926 ELECTRICAL DISCONNECT AND RECONNECT

403280920 OPEN, INSPECT, REPAIR

210151233 VALVE HAS SLIGHT PACKING LEAK

406140300 LIMITS NOT WORKING

406131858 THERMALS BREAKER OPENING

406191135 REPAIR/REPLACE GEAR ASSEMBLY

406190408 VALVE WON'T CLOSE OR OPEN

405120310 STROKE TIME EXCEEDED REFERENCE

407021902 HANDLE LOOSE

406200605 REPLACE 1 INCH, 45 DEGREE CONNECTOR

407251001 INCREASE OVERLOADS TO SIZE 1024

407251002 REPLACE OVERLOADS WITH SIZE 1024

407251003 REPLACE OVERLOADS WITH SIZE 1024

407251004 REPLACE OVERLOADS WITH SIZE 1024

407251005 REPLACE OVERLOADS WITH SIZE 1024

407251006 REPLACE OVERLOADS WITH SIZE 1024

407271235 PERFORM TEP-5

407251007 REPLACE OVERLOADS WITH SIZE 1024

407251008 REPLACE OVERLOADS WITH SIZE 1024

405122130 EXCESSIVE STROKE TIME

407251009 REPLACE OVERLOADS WITH SIZE 1024

407251010 REPLACE OVERLOADS WITH SIZE 1024

406091945 EXCEEDS STROKE TIME AS PER PT 18.6

407251011 REPLACE OVERLOADS WITH SIZE 1024

405122135 EXCESSIVE STROKE TIME

407251012 REPLACE OVERLOADS WITH SIZE 1024

406091948 EXCEEDS STROKE TIME AS PER PT 18.6

02943 REPLACE OVERLOADS W/SIZE 10 24

02944 REPLACE OVERLOADS W/SIZE 10 24

VOID - NO WORK PERFORMED

VOID - NO WORK PERFORMED

DISCONNECTED AND RECONNECTED FOR

REPAIRED VALVE

VOID

REPLACED LIMIT SWITCH, GEAR WORN

VOID - COMPLETED ON 1406140306

INSPECTED, FOUND LIMITORQUE SAT

REPLACED LIMITS, DISCONNECTED

STROKE TIME OF VALUE BEING CHANGED

INSTALLED WASHER

REPAIRED FLEX TO LIMIT SWITCH

REPLACED OVERLOADS WITH CORRECT SIZE

REPLACED OVERLOADS WITH CORRECT SIZE

REPLACED OVERLOADS WITH CORRECT SIZE

REPLACED OVERLOADS WITH CORRECT SIZE

REPLACED OVERLOADS WITH CORRECT SIZE

REPLACED OVERLOADS WITH CORRECT SIZE

PERFORMED TEP-5 BREAKER

VOID - TO BE COMPLETED ON WO 002943

VOID - TO BE COMPLETED ON WO 002944

VOID - TO BE COMPLETED ON WO 002140

VOID - TO BE COMPLETED ON WO 002945

VOID - TO BE COMPLETED ON WO 002946

VOID - TO BE COMPLETED ON WO 002382

VOID - TO BE COMPLETED ON WO 002947

VOID - TO BE COMPLETED ON WO 002141

VOID - TO BE COMPLETED ON WO 002948

VOID - TO BE COMPLETED ON WO 002385

REPLACED OVERLOADS. VALVE CYCLED SAT BY OPS

OVERLOAD-HEADERS -2- 0735038

REPLACED OVERLOADS VALVE CYCLED SAT BY OPS

OVERLOAD HEATERS -2- 0735038

840419

840419

840420

840428

840516

840614

840615

840620

840620

840623

840706

840724

840726

840726

840726

840726

840726

840726

840727

840816

840816

840816

840816

840816

840816

840816

840816

840816

840816

840918

VOID

VOID

PMS

SL

VOID

PG

VOID

PG

PG

MD

MD

MD

DC

DC

DC

DC

DC

DC

PMS

VOID

VOID

VOID

VOID

VOID

VOID

VOID

VOID

VOID

VOID

DC

0

2-MOV-B 840918 DC

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY SL - SEAT LEAKAGE

DC - DESIGN CHANGE PG - PLUGGING FAILURE SWITCH - NON-FUNCTIONAL FAILURE OF LIMIT SWITCH
Table B.1.c. (continued)

MARK NO.

2-MOV-C

2-MOV-D

2-MOV-E

2-MOV-F

1-MOV-B

1-MOV-B

1-MOV-D

COMPONENT

MOV

MOV

MOV

MOV

MOV

M. R. #

02945

02946

02947

02948

1876

PROBLEM DESC

REPLACE OVERLOADS W/SIZE 10 24

REPLACE OVERLOADS W/SIZE 10 24

REPLACE OVERLOADS W/SIZE 10 24

REPLACE OVERLOADS V/SIZE 10 24

INSPECT VALVE

1-MOV-D

w 1-MOV-D

1-MOV-F

1-MOV-F

1-MOV-F

1-MOV-A

1-MOV-B

1-MOV-Df

1-MOV-F

MOV 4484 DISCONNECT/RECONNECT MOV FOR

MECH

MOV 9491 REPAIR LINEAR INDICATION

MOV 1877 INSPECT VALVE

MOV 4483 DISCONNECT/RECONNECT

1-MOV-D

MOV 1878 INSPECT VALVE

MOV 4485 DISCONNECT/RECONNECT

1-MOV-F

MOV 10301 PACKING LEAK 1-MOV-F

MOV 7118 1-MOV-A PMS

MOV 7119 1-MOV-8 PMS

MOV 7121 1-MOV-D PMS

MOV 7123 1-MOV-F PMS

MODE/MECHANISM(if applicable)

HISTORY SUMMARY

INSTALL OVERLOADS. VALVE CYCLED SAT BY OPS

OVERLOAD HEATERS -2- 0735038

REPLACED OVERLOADS. VALVE CYCLED SAT BY OPS

OVERLOAD HEATERS -2- 0735038

REPLACED OVERLOADS. VALVE CYCLED SAT BY OPS

OVERLOAD HEATERS -2- 0735038

REPLACED OVERLOADS. VALVE CYCLED SAT BY OPS

OVERLOAD HEATERS -2- 0735038

OPENED VALVE, INSPECTED INTERNALS, CLEANED PLUG

AND SEAT, BLUED TO 100% CONTACT. REINSTALLED BODY

TO BONNET.

DISCONNECTED MOV 10/24/84. VALVE RECONNECTED

10/26/84, BUT HAVE NOT CYCLED. CYCLED

MOV-MOV4B ,. OK.

GROUND INDICATION OUT OF BODY OF VALVE. MINIMUM

WALL THICKNESS WAS NOT VIOLATED BY GRINDING. NDE

PART AND REPORT SATISFACTORY.

DISASSEMBLED VALVE, AND INSPECTED INTERNALS LAP

SEAT AND PLUG AS NECESSARY.

MOV DISCONNECTED, COVER HAS 3 BOLTS MISSING

(10/24/84). RECONNECTED MOV-CH 11/24/84. CYCLED

MOV-MOV-D , SATISFACTORY.

DISASSEMBLED BODY TO BONNET. INSPECTED INTERNALS,

CLEANED PLUG AND SEAT, BLUED TO 100%, CONTACT

MOV DISCONNECTED 10/24/84. VALVE RECONNECTED

10/26/84, BUT HAVE NOT CYCLED. CYCLED MOV-MOV-F

OK.

EVENED OUT AND ADJUSTED PACKING GLAND, 4 FLATS ON

GLAND NUTS. CYCLED VALVE TO ENSURE FREE MOVEMENT.

CYCLE VALVE. CHECK LIGHTS INDICATION, AND AMPS.

PERFORMED PMS SATISFACTORY (11/30/84).

PERFORMED PMS ON MOV-MOV-f (11/30/84).

REMOVED MEGGERED MOTOR AND-TOOK LOAD CHECK WHEN

CYCLING VALVE, 11/30/84.

841203 PMS

841203 MD

841203

841203

841203

841203

841207

841213

841213

841213

841213

PMS

PMS

PMS

PMS

BL

PMS

PMS

PMS

PMS

840918

840918

840918

840918

841203

DC

DC

DC

DC

PMS

RTSVDT CLASSIFICATION*

* PMS - PREVENTIVE-MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY SL - SEAT LEAKAGE

DC - DESIGN CHANGE PG - PLUGGING FAILURE SWITCH - NON-FUNCTIONAL FAILURE OF LIMIT SWITCH
Table B.I.c. (continued)

MODE/NECHANISM(if applicable)

MARK NO. HISTORY SUMMARY

1-MOV-C

1-MOV-E

2-MOV-F

1-MOV-F

2-MOV-F

.2-MOV-B

2-MOV-A

2-MOV-E

2-MOV-D

2-MOV-F

2-MOV-B

2-MOV-D

COMPONENT M. R. I PROBLEM DESC

NOV 7120 1-MOV-C PMS

NOV 7122 1-MOV-E PMS

MOV 20986 REPAIR VLV 2-MOV-F

NOV 13893 1-MOV-F BREAKER TRIPPED

MOV 31197 2-MOV-F INSTALL T DRAIN

MOV 11243 2-MOV-B AGASTAT TIMER

MOV 11246 2-MOV-A AGASTAT TIMER

MOV 11244 2-MOV-E AGASTAT TIMER

MOV 11245 2-MOV-D AGASTAT TIMER

MOV 13826 2-MOV-F REPLACE AGASTAT

MOV 18180 2-MOV-B DISCONN/RECONN

MOV 18179 2-MOV-D DISCONN/RECONN

MOV 18178 2-MOV-F DISCONN/RECONN

RTSVDT CLASSIFICATION*

PERFORMED PMS SATISFACTORY (11/30/84).

PERFORMED PMS, SATISFACTORY 11/30/84.

VOID SELECTED AS REPETITIVE MAINT RMN02430

BRIDGED AND MEGGERED SATISFACTORY, CYCLED SEVERAL

INSTALLED -T- DRAIN PLUG IN 2-NOV-F

REPLACED AGASTAT TIMER, TESTED SAT.

REPLACED AGASTAT TIMER CONNECTED L1-62 COIL LEADS

REPLACED AGASTAT TIMER. LI-L2 COIL LEADS ONE

CONNECTED. COMPLETED WD AGASTAT OK 5/31/85

REPLACED AGASTAT. TESTED SAT.

REPLACED AGASTAT 4485 CYCLED SAT 6/1/85

AGASTAT 4605291

DISCONNECTED MOV AS PER EMP-C-HOV-11. RECONNECTED

MOTOR AND LIMITS ADJUSTED AS PER PROCEDURE

EMP-C-MOV-11 UNABLE TO CHECK ROTATION OF MOTOR

TASS MISSING 5/23/85

DISCONNECTED MOV AS PER EMP-C-MOV-11 4/8/85.

RECONNECTED. COMPLETED STEPS 3.1-523 REQUIRE ELEC

RUN AND LOAD CHECK. COMPLETED SAT

DISCONNECTED MOV AS PER EMP-C-MOV-1 1 RECONNECTED

NOV CABLE MARKINGS POOR. VALVE CYCLED SAT

GASKET COVER 4606098

VOID NOT LEAKING 6/12/85

REPLACED AGASTAT TIMER CONNECTED 61-62 COIL LEADS

5/25/85 COMPLETED. MR AGASTAT 8c

VOID NOT LEAKING 6/17/85

INSPECT FOR MISSING ZERK FITTINGS NONE MISSING

INSTALLED SWITCH COVER SCREW

VOID NOT LEAKING

INSPECT FOR MISSING ZERK FITTINGS. NONE MISSING

INSPECT FOR MISSING ZERK FITTINGS. NONE MISSING

INSPECT FOR MISSING ZERK FITTING. NONE MISSING

INSPECT EDR MISSING ZERK FITTING. NONE MISSING

INSPECT FOR MISSING ZERK FITTING. NONE MISSING

841214

841214

850204

850213

850228

850523

850531

850531

850523

850601

850605

PMS

PMS

VOID

PG

DC

DC

DC

DC

DC

DC

PMS

850605 DC

850605 PMS co

WI

t')

2-MOV-F

2-MOV-E

2-MOV-C

2-MOV-A

2-MOV-A

2-MOV-B

2-MOV-F

2-MOV-B

2-MOV-C

2-MOV-D

2-MOV-E

2-MOV-F

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

20331

13787

20326

20830

20436

20327

20831

20832

20833

20834

20835

VALVE LEAKS THRU

2-MOV-B REPLACE AGASTAT

VALVE LEAKS THRU

INSPECT AS REQUIRED

2-MOV-B SWITCH COVER

VALVE LEAKS THRU

INSPECT

INSPECT

INSPECT

INSPECT

INSPECT

850612

850613

850617

850617

850617

850617

850618

850618

850618

850618

850618

VOID

DC

VOID

PMS

MD

VOID

PMS

PMS

PMS

PMS

PMS

* PNS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY SL - SEAT LEAKAGE

DC - DESIGN CHANGE PG - PLUGGING FAILURE SWITCH - NON-FUNCTIONAL FAILURE OF LIMIT SWITCH
Table B.l.c. (continued)

MODE/MECHANISM(if applicable)

MARK NO. HISTORY SUMMARY

2-MOV-B

2-MOV-C

2-MOV-D

2-MOV-E

2-MOV-E

2-MOV-F

2-MOV-E

2-MOV-F

2-MOV-A

2-MOV-E

2-MOV-A

1-MOV-A

1-MOV-B

W I-MOV-C

1 1-MOV-D

1-MOV-E

1-MOV-F

1-MOV-D

2-MOV-B

2-MOV-A

2-MOV-A

2-MOV-B

2-MOV-C

2-MOV-E

C OM PO0NENMT

NOV

MOV

NOV

NOV

NOV

MOY

MOV

MOV

MOV

MOV

NOV

MOV

MOV

NOV

NOV

MOV

M. R. f

02140

20360

02382

02141

20359

02333

20984

20935

20983

18177

13646

2275

2276

2277

2278

2279

2280

22962

42036

20540

25950

25949

25948

25946

PROBLEM DESC RTSVDT CLASSIFICATION*

EXCESSIVE STROKE TIME

INSTALL GREASE FITTING

INVESTIGATE STROKE TIME

OVERHAUL VALVE

INSTALL GREASE FITTING

INVESTIGATE STROKE TIME

2-MOV-E ASSIST MECH

2-MOV-F ASSIST MECHS

2-MOV-A ASSIST MECH

2-MOV-E DISCON/RECONN

STROKE TIME EXCEEDS AVG PT18.6

REPLACE AGASTAT

REPLACE AGASTAT

REPLACE AGASTAT

REPLACE AGASTAT

REPLACE AGASTAT

REPLACE AGASTAT

1-MOV-D INVESTIGATE TRIP

2-MOV-B PERFORM EWR WORK

2-MOV-A WONT XFER CONTR

2-MOV-A INSTALL T-DRAIN

2-MOV-B INSTALL T-DRAIN

2-MOV-B INSTALL T-DRAIN

2-MOV-E INSTALL T-DRAIN

DISASSEMBLE VALVE AND INSPECT PARTS

INSTALL GREASE FITTING #2295726

DISASSEMBLED VALVE CLEAN AND INSPECTED INTERNALS

REASSEMBLED VALVE WITH NEW BONNET GASKET. STEM,

PLUG AND ROTATE REPACKED VALVE

REPACKED VALVE WITH GARLOCK 98

INSTALL GREASE FITTING #2295726

DISASSEMBLED VALVE REPLACED STEM, DISC TORQUE KEY,

GASKET DISC WASHER-100 PERCENT BLUE CHECK

REASSEMBLED VALVE

ADJUSTED TORQUE SWITCH SETTING TO 2

VALVE CYCLED SAT AS PER OPERATIONS/ NO ADJUSTMENTS

NECESSARY

VALVE CYCLED SAT AS PER OPERATIONS/ NO

ADJUSTMENTS WERE NECESSARY

VOID COMPLETED ON WO 020984

VOID VALVE CYCLED SAT 6/20/85 NO WORK PERFORMED

VOID TO MR 1405251145.

VOID TO 1405251146.

VOID TO MR 1405251147.

VOID TO MR 1405251148.

VOID TO MR 1405251149.

VOID TO MR 1405251150.

WORKED WITH OPERATORS AND CYCLED VALVE;

SATISFACTORYNO PROBLEMS FOUND (OPEN 2.5 AMPS,

CLOSED 2.5 AMPS).

INSTALLED NEW HEATERS AND CHANGED FIELD LEADS AS

PER PROCEDURE 10/10/86. SET UP THRUST VALVES AS

PER EWR

REPLACED COIL ON LATCHING RELAY OLD COIL BURNT UP

REPLACED OLD PLUGS WITH 2 BREATHER PLUGS IN MTR.

REPLACED OLD PLUGS WITH 2 BREATHER PLUGS IN MTR

REPLACE OLD PLUGS WITH 2 BREATHER LUGS IN MTR.

REPLACED OLD PLUGS WITH 2 BREATHER LUGS IN MTR.

850620

850620

850620

850620

850620

850620

850624

850624

850626

850627

850628

850711

850711

850711

850711

850711

850711

850814

851012

851029

851101

851101

851101

851101

PG

DC

PG

PMS

DC

PG

PMS

PMS

PMS

VOID

PMS

VOID

VOID

VOID

VOID

VOID

VOID

PG

DC

PG

DC

DC

DC

DC

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY SL - SEAT LEAKAGE

DC - DESIGN CHANGE PG - PLUGGING FAILURE SWITCH - NON-FUNCTIONAL FAILURE OF LIMIT SWITCH
Table B.1.c. (continued)

MARK NO.

2-MOV-D

2-MOV-F

2-MOV-D

2-MOV-E

1-MOV-F

1-MOV-D

1-MOV-D

1-MOV-D

1-MOV-D

1-MOV-D

1-MOV-A

COMPONENT

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

M. R. #

25947

25945

38412

38413

2963

29885

29920

29937

35288

30701

36114

PROBLEM DESC

2-MOV-D INSTALL T-DRAIN

2-MOV-F INSTALL T-DRAIN

-L-ACTUATOR INSPECTION/REPAIR

-L-ACTUATOR INSPECTION/REPAIR

INVESTIGATE STROKE TIME

INVESTIGATE/REPAIR MOV

E-INVESTIGATE/REPAIR AS

REQUIRED

1-MOV-D

DISCONNECT/RECONNECT

PACKING ADJUSTMENT

INVESTIGATE/REPAIR LEAK

EWR 85-018C, 85-261A, 85-224B

MODE/MECHANISM(if applicable)

HISTORY SUMMARY

REPLACED OLD PLUGS WITH -2- BREATHER PLUGS IN MTR

REPLACED OLD PLUGS WITH 2 BREATHER PLUG IN MTR

BAD GREASE/WRONG GREASE INSTALLED

REMOVED DISASSEMBLED, CLEANED, REASSEMBLED AND

INSTALLED. CHANGED OUT TRIGGER FINGER.

PARTS -7/16- 9/16- 15/16- 1 1/16-

BAD GREASE/WRONG KIND

RMO, DISASSEMBLED, CLEANED, REPLACED

AND LUBRICATED ACTUATOR, PLACED TRIGGER FINGER

SPRING. PARTS- EXXON NEBULA EP-O

VOID - NOT REQUIRED AS PER ATTACHED MEMO.

RESET THERMO OVERLOADS, TURNED BREAKER ON AND

VALVE AUTOMATICALLY WENT OPEN DRAWING 2.7 AMPS.

DREW 2.7 ALL THE WAY CLOSED, THEN DREW 11.3 AMPS.

WE THINK THE TORQUE SWITCH IS BROKEN.

AS FOUND - DISASSEMBLED LIMITORQUE, FOUND NO

INTERNAL DAMAGE OF COMPONENTS. GREASE WAS VERY

HARD, CLEANED ALL PARTS AND HOUSINGCHANGED OUT

GREASE WITH EP-O, AND REASSEMBLED.

DISCONNECTED MOTOR AND LIMIT SWITCH, 1/28/86.

REMOVED LIMIT SWITCH AND TORQUE SWITCH. ALSO

REMOVED MOTOR FOR MECHANICAL DEPARTMENT,

1/29/86. HOOKED UP AND PERFORMED EMP-C-MOV-11

SATISFACTORILY.

LEAK/PACKING

TIGHTENED PACKING.

INVESTIGATION REVEALED THAT GREASE WAS NOT

LEAKING, IT WAS JUST RECENTLY CHANGED AND THE

GREASE THAT WAS SEEN WAS JUST EXCESS THAT DIDN'T

GET WIPED OFF, GREASE WIPED OFF.

BRIDGED AND MEGGERED TOO AMP READING. MOTOR

PULLED HIGHER AMPS THAN NORMAL.

RTSVDT CLASSIFICATION*

851104

851104

851128

851128

851213

860128

860131

860204

860607

860609

860610

DC

DC

PMS

PMS

VOID

PG

PG

PMS

BL

VOID

PMS

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY SL - SEAT LEAKAGE

DC - DESIGN CHANGE PG - PLUGGING FAILURE SWITCH - NON-FUNCTIONAL FAILURE OF LIMIT SWITCH
Table B.I.c. (continued)

MARK NO.

1-MOV-A

1-MOV-D

1-MOV-E

1-MOV-F

COMPONENT

NOV

M. R. # PROBLEM DESC

35258 ACTUATOR INSTALLATION

NOV 35255 ACTUATOR INSPECTION

MOV 35254 ACTUATOR INSPECTION

MOV 36992 1-MOV-F STATIC TEST

MOV 37045 MOV-B EWR 86-224, 85-224C

MOV 36362 MOV-B EWR 85-2248,261A,018C

MOV 37040 NOV-F EWR 86-224, 85-224C

NOV 36367 MOV-D EWR, 85-224B, 261,

018C

NOV 37043 NOV-D EWR 86-224. 85-224C

MODE/MECHANISM(if applicable)

HISTORY SUMMARY

GREASE/NORMAL WEAR

DISASSEMBLED, CLEANED, INSPECTED ACTUATOR.

REPLACED BAD GASKETS, AND SEAL 0-RINGS.

REINSTALLED AND LUBRICATED ACTUATOR. TOOLS 1-1/16

COMBINED. 18-

BAD LUBRICANT/WRONG LUBRICANT

REMOVED ACTUATOR, DISASSEMBLED, CLEANED,

INSPECTED, REPLACED GASKETS, AND LUBRICATED AND

REINSTALLED.

GREASE/NORMAL WEAR

DISASSEMBLED. CLEANED, INSPECTED ACTUATOR,

REPLACED BAD GASKETS, O-RINGS, QUAD-RINGS, AND

REINSTALLED AND LUBRICATED ACTUATOR.

HIGH AMP READING, 6/17/86. ASSISTED MOVATS IN

TESTING OF VALVE. VALVE OPERATED SATISFACTORY,

6/17/86. THRUST SETTINGS 15160, OPENED 15838.

COMPLETED EWR 86-224-PI. FINAL THRUST VALVES NO.

16160 OPEN, NO. 16020 CLOSE.

RESET TORQUE SWITCH 5/31/86. PERFORMED EWR

85-224B, 85-01, AND 85-261A.

COMPLETED EWR 86-224-Pi. VALVE OPERATED

SATISFACTORY, 6/20/86.

MADE ADJUSTMENTS ON TORQUE SWITCH OLD SETTING,

2-1/4 OPEN: 2-1/4 CLOSE. CHANGE TO 2-3/8 OPEN;

2-3/8 CLOSE. PERFORMED EWR 85-2248.85-068C, AND

COMPLETED EWR 86-224-PI. COMPLETED EMP-COMOV-151,

COMPLETED EMP-C-MOV-18, RETAGGED MOV-MOV-D . TAG

REPORT NO. SI-8318

BRIDGED AND MEGGERED, AND TOOK LOAD CHECK.

COMPLETED EWR-86-224-P1, 6/16/86. ASSISTED MOVATS

IN TESTING OF VALVE. COMPLETED EMP-C-MOV-151.

VALVE OPERATED SATISFACTORY.

RTSVDT CLASSIFICATION*

860611 PMS

860611 PMS

860611 PMS

860624 PMS

LA

1-MOV-B

1-MOV-B

1-MOV-F

1-MOV-D

860701

860702

860702

860705

PMS

PMS

PMS

PMS

1-MOV-D

1-MOV-E

I-MOV-E

860705 PMS

860705 PMS

860705 PMS

MOV

NOV

36115 EWRS 85-018C. 85-261A, 85-2248

37042 MOV-E EWR 86-224, 85-224C

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY SL - SEAT LEAKAGE

DC - DESIGN CHANGE PG - PLUGGING FAILURE SWITCH - NON-FUNCTIONAL FAILURE OF LIMIT SWITCH
Table B.1.c. (continued)

MARK NO.

1-MOV-F

1-MOV-C

1-MOV-F

1-MOV-B

1-MOV-C

1-MOV-A

COMPONENT

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

M. R. f PROBLEM DESC

35253 ACTUATOR INSPECTION

37044 MOV-C EWR 86-224, 85-224C

37650 1-MOV-F TEST WITH MOVATS

35257 ACTUATOR INSPECTION

35256 ACTUATOR INSPECTION

37037 1-MOV-A EWR 86-224

37465 1-MOV-D EWR 85-224C

37058 MOV-F EWR 85-224B, 261A,

018C

37688 2-MOV-D WILL NOT OPEN

42032 2-MOV-A PERFORM EWR.S

42038 2-MOV-B PERFORM EWR WORK

42043 2-MOV-E PERFORM EWR WORK

MODE/MECHANISM(if applicable)

HISTORY SUMMARY

IMPROPER LUB./DIDN'T USE PRO SPECS

REMOVED ACTUATOR FROM VALVE AND TOOK TO

REFURBISHING SHOP. DISASSEMBLED ACTUATOR, CLEANED,

INSPECTED, AND REPLACED ALL GASKETS.

DELTA P - COMPLETED PROCEDURE AND EWR 86-224-PI ON

6-24-86. FIND THRUST.

MOVAT TEST COMPLETED.

REMOVED, DISASSEMBLED, CLEANED, AND INSPECTED CASE

AND MECHANICAL PARTS. REPLACED GASKETS, O-RINGS,

AND QUAD-RINGS. REASSEMBLED AND REINSTALLED.

GREASE/NORMAL WEAR

DISASSEMBLED, CLEANED, INSPECTED ACTUATOR. AND

REPLACED ALL.

REMOVED FROM LIST - LEADS FROM OPEN SIDE OF TORQUE

SWITCH, NO. 18 AND CONTROL LEAD 43. CONNECTED

LEAD 43 AND OPENED SIDE OF TORQUE SWITCH NO. 18,

LEADS TO LS 13.

PERFORMED EWR 85-244C AND TESTED IN ACCORDANCE

WITH PROCEDURE. 6/23/86. FINAL THRUST VALVES CLOSE

AT 15,180 LBS, OPEN AT 15,220 LBS.

HIGH AMP READING. REPLACED OLD HEATER COILS.

FAILURE/VALVE WOULD NOT OPER.

AUX. CONTACTS STUCK. CHECKED AND FOUND AUX.

CONTACTS WERE STUCK OPERATED AND CHECKED SAT.

INSTALLED NEW HEATERS AND CHANGED FIELD LEADS AS

PER PROCEDURE 1-/10/86. LOAD CHECKED/BRIDGE/MEGGER

OPERATED SAT 10/15/86. PERFORMED

INSTALLED NEW HEATERS AND CHECKED FIELD LEAD TO

BE SAT 10/10/86. EWR'S COMPLETED 2248 224H 018

261 10/15/86

PERFORMED EWR'S 85-018 AND 85-261 SAT 10/14/86

PERFORMED EWR 86-224B AND 85-224H AS STATED WITH

MOVATS THRUST VALUES SET AS PER EWR-224H

RTSVDT CLASSIFICATION*

860705 PMS

t0do

1-MOV-D

1-MOV-F

2-MOV-D

2-MOV-A

2-MOV-C

2-MOV-E

860706

860706

860707

860707

860708

860715

860717

860715

861015

861015

861015

PMS

PMS

PMS

PMS

PMS

PMS

PMS

PG

DC

DC

DC

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY SL - SEAT LEAKAGE

DC - DESIGN CHANGE PG - PLUGGING FAILURE SWITCH - NON-FUNCTIONAL FAILURE OF LIMIT SWITCH
Table B.1.c. (continued)

MARK NO.

2-MOV-D

2-MOV-F

2-MOV-A

2-MOV-B

2-MOV-A

COMPONENT M. R. # PROBLEM DESC

MOV 42040 2-MOV-D PERFORM EWR WORK

MOV 42050 2-MOV-F PERFORM EWR WORK

MOV 38409 ACTUATOR INSPECTION AND REPAIR

MOV 38410 ACTUATOR INSPECTION AND REPAIR

MOV 20987 REPAIR VLV 2-MOV-A

MODE/MECHANISM(if applicable)

HISTORY SUMMARY

INSTALLED HEATERS AND CHANGED FIELD LEADS AS PER

PROCEDURE 10/10/86 PERFORMED EWR 86-2248 85-224H

IAW MOVATS AND EMP-C-MOV- 10/24/86

PERFORMED EWR 85-018 + 85-261 + 86-224 AND TESTED

VALVES PER EWR-85-224H AND MOVATS 10/13/86

NA/.

BAD GREASE/IMPROPER GREASE INSTALLED

REMOVED ACTUATOR, TRASPORTED TO REFURB SHOP.

DISASSEMBLED, CLEANED AND INSPECTED, REPLACED

ALL SOFTWARE, REPLACE

REMOVED ACTUATOR FROM VALVE & TRANSPORTED TO

REFERB SHOP DISASSEMBLED CLEANED, INSPECTED,

REPLACED ALL SOFTWARE & DEFECTIVE PARTS.

REASSEMBLED USING EXXON NEBULA EP-O GREASE

DISASSEMBLED VALVE IAW PROCEDURE & TAPED OPENING

IN SYSTEM SHUT & ALL PARTS IN BAS BY VALVE BODY.

LAPPED SEAT & PLUG REINSTALLED BONNET WITH NEW

GASKET TROQUED TO 150 FT LBS.

REMOVED, DISASSEMBLED. CLEANED, INSPECTED,

ASSEMBLED, LUBRICATED, & INSTALLED. BAD GREASE/.

WRONG GREASE INSTALLED.

UNPACKED AND REPACKED VALVE WITH GARLOCK 98.

VOID TO 038413

ASSISTED OPERATORS IN OPENING VALVE FULLY FROM

MCC. VALVE WENT FULL OPEN, FULL CLOSE WITH PROPER

INDICATION. WORK PERFORMED ON WO 047506, 1/8/87.

BAD GREASE/WRONG GREASE INSTALLED

REMOVED DISASSEMBLED, CLEANED, INSPECTED,

ASSEMBLED, LUBRICATED, INSTALLED. TOOLS-9/16

1/2 7/16 COMBINATION 5/16 3/8 ALLEN

REPAIRED PRONG ON MOV. NEEDED SMALL ADJUSTMENT

CYCLED 5 TIMES. EVERYTHING RAN SAT.

RTSVDT CLASSIFICATION*

861025 DC

861025 DC

861101 PMS

861101 PMS

861119 MD

861119 PMS

-J

2-MOV-F

2-MOV-F

2-MOV-E

1-MOV-D

MOV 38414 -L-ACTUATOR INSPECTION/REPAIR

REPACK VALVE

REPAIR VLV 2-MOV-E

INVESTIGATE/REPAIR AS NEEDED

MOV

MOV

MOV

43066

20988

45967

861119

861120

861123

PMS

VOID

PG

2-MOV-C

2-MOV-B

MOV 38411 -L-ACTUATOR INSPECTION/REPAIR

MOV 45784 2-MOV-8 ADJUST LIMITS

861128 PMS

861204 SWITCH

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY SL - SEAT LEAKAGE

DC - DESIGN CHANGE PG - PLUGGING FAILURE SWITCH - NON-FUNCTIONAL FAILURE OF LIMIT SWITCH
Table B.1.c. (continued)

MARK NO.

1-MOV-D

1-MOV-C

1-MOV-D

1-MOV-F

1-MOV-E

tU 2-MOV-C

00

1-MOV-C

1-MO V-D

2-MOV-C

2-MOV-F

COMPONENT

MOV

MOV

MOV

MOV

MOV

M. R. #

47664

PROBLEM DESC

ACTUATOR GREASE REPLACEMENT

47314 P.E-OVERHAUL MOV

46491

49034

1-MOV-D ADJUST INDICATOR

SWITCH

1-MOV-F INSPECT HOOK-UP

49801 INVESTIGATE MALFUNCTION

MODE/MECHANISM(if applicable)

HISTORY SUMMARY

REPLACED GREASE/PM

REMOVED TOP COVER AND CHECKED GREASE, PULLED SIDE

PLUG AND CHECKED SAMPLE OF GREASE. DRAINED OUT

GREASE AND FILLED TO LEVEL WITH NEW GREASE.

CLEAN SPRING PAK./PM

REMOVED MOTOR. REPLACED GREASE, REMOVED

WORM/TORQUE SPRING ASSEMBLY, CLEANED. GREASED, AND

REINSTALLED.

VOID - TO BE COMPLETED ON 047506

MOTOR HEATER LEADS ARE NOT TERMINATED. 1/31/87.

REMOVED LIMIT COVER. LEADS FOR MOTOR HEATERS ARE

TOO SHORT TO TERMINATE PROPERLY WITHOUT REMOVING

GEARBOX

VALVE WOULEN'T OPEN/AUXILIARY OPEN

INTERLOCK STUCK ON OPENING CIRCUIT. REPLACED

CONTACTOR 2/18/87, CHECKED SATISFACTORY.

TIMES. FLA 2.4 ACTUAL, T1 2.4, T2 2.4, AND T3 2.4

OKAY.

SPRING PACK DISASSEMBLED 12/30/86. S/N 347490.

INSTALLED SPRING PACK ONLY. LEFT WITH MOVAT.

WORK WAS PERFORMED BY MOVAT.

VALVE WOULDN'T OPEN/INCORRECT WIRING

STARTED TROUBLE SHOOTING. FOUND ONE AGASTAT WIRE

IN WRONG PLACE. RETURNED TO PROPER PLACE AS PER

VALVE WOULDN'T OPEN/INCORRECT WIRING

FOUND X1 LANDED ON WRONG TERMINAL ON AGASTAT.

RELANDED CORRECTLY AS ESK 6BY. FOUND IT ON NO. 1

CONTACT.

PERFORMED DELTA R. EVERYTHING WORKED FINE 3/6/87

VALVE WAS CYCLED SATISFACTORY DURING ACTUAL FLOW

CONDITION. THRUST VALVE RECORDED DURING CLOSE

VOID TO 040444

RTSVDT

870106

CLASSIFICATION*

PMS

870109

870201

VOID

MD

870108 PMS

MOV 46218 REPAIR VALVE

MOV 49725 1-MOV-C CHECK LOGIC, CKT

MOV 49735 1-MOV-D CHECK LOGIC CKT

MOV 49525 2-MOV-B DELTA-R TESTING

MOV 45553 2-MOV-F HIGH AMP READING

870219 PG

870225 PG

870304 NAF

870304 NAF

870316 PMS

870501 VOID

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY SL - SEAT LEAKAGE

DC - DESIGN CHANGE PG - PLUGGING FAILURE SWITCH - NON-FUNCTIONAL FAILURE OF LIMIT SWITCH NAF - NOT AN AGING FAILURE (MAINTENANCE ERROR)
Table B.l.d. MAINTENANCE RECORDS FOR THE AUXILIARY FEEDWATER SYSTEM 6-INCH MOTOR OPERATED VALVES

MODE/MECHANISM(if applicable)

MARK NO. COMPONENT M. R. I PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSIFICATION*

2-MOV-I

1-MOV-G

1-MOV-H

2-MOV-J

2-MOV-J

1-MOV-G

1-MOV-H

1-MOV-G

2-MOV-I

2-MOV-I

2-MOV-I

2-MOV-I

2-MOV-J

2-MOV-J

2-MOV-J

1-MOV-G

1-MOV-G

1-MOV-G

1-MOV-G

1-MOV-G

1-MOV-G

1-MOV-G

2-MOV-I

2-MOV-I

2-MOV-J

2-MOV-J

2-MOV-J

2-MOV-I

2-MOV-I

2-MOV-J

2-MOV-I

2-MOV-I

2-MOV-J

MOV

MOV

MOV

VALVE

MOV

MOV

MOV

MOV

VALVE

MOV

MOV

MOV

MOV

VALVE

VALVE

MOV

MOV

MOV

VALVE

MOV

MOV

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

MOV

VALVE

VALVE

MOV

MOV

20160580

805091028

805091029

810030726

812040631

910230641

4262145

909111345

7301209

7231425

8050929

8050855

8122234

101131200

101131201

6120630

112120420

112150300

107011537

112241242

112281344

112132230

304191635

304231500

304191637

304231427

308261835

309051430

308311504

304231705

408050956

03352

20409

PERFORM EMP-P-MOV-45

CLEAN AND INSPECT

CLEAN AND INSPECT

WILL NOT OPERATE

THERMALS OUT WON'T OPEN

MOV WILL NOT OPEN

MANUAL ENGAGEMENT HANDLE

VALVE BINDING

DISCONNECT FOR MECHANICS

VALVE IS BINDING UP

REPLACE LIMITORQUE

DISCONNECT/RECONNECT FOR MECHS

VALVE WILL NOT COME FULL OPEN

VALVE BINDS UNABLE TO CLOSE

DISCONNECT/RECONNECT FOR MECHANICS

VALVE WILL NOT OPEN

VALVE WILL NOT CYCLE

VALVE DOES NOT TRAVEL

VALVE BINDS UP

ELECTRICAL DISC LIMIT ON 1-MOV-A

DISCONNECT/RECONNECT MOV

WILL NOT FULLY CLOSE

VLV CYCLES HI AMPS ON MTR

2-MOV-I WILL NOT OPEN

VLV CYCLES HI AMPS ON MTR

2-MOV-J WILL NOT OPEN

LIMITORQUE GEARBOX LEAKING

VALVE NOT FULLY CLOSED

REPLACE OR REPAIR FLEXIBLE CONDUIT

VALVE WILL NOT OPEN

ADJUST PACKING OR REPLACE

ADJUST PACKING OR REPLACE

2-MOV-J TORQUE SWITCH

COMPLETED

VOID

VOID

MEG BRIDGED AND TESTED SATISFACTORY

CLEANED, CHECKED MOTOR - TEST SAT

VOID

VALVE OPERATES OK

VOID

CONNECTED - TESTED SAT

REPAIRED VALVE

REPAIRED LIMITORQUE OPERATOR

COMPLETED AS PER EMP-C-MOV-11

NO PROBLEMS FOUND

CLEANED, STEM THREADS

MOV TESTED SATISFACTORY

COMPLETE

ADJUSTED LIMITS ON MOV-MOV-A , SAT

VOID

VOID - COMPLETED UNDER MR 112132230

RECONNECTED & TESTED SATISFACTORY

VOID

VOID - UPDATING MR

ADJUSTED PACKING

CLEANED TORQUE SWITCH

ADJUSTED PACKING

ADJUSTED TORQUE SWITCH

FOUND NO GREASE LEAK ON MOV

CLEANED CONTACTS, TESTED SATISFACTORY

REPLACE FLEX COMPLETE

VOID

ADJUSTED GLAND

VOID-NO PROBLEM EXITS

CHECKED TORQUE SWITCH WITH PROCEDURE EMP-S-MOV-143

770928

780718

780718

781006

781204

791024

800429

800522

800801

800801

800807

800808

800814

810120

810214

810423

811212

811215

820128

820205

820211

820217

830423

830423

830423

830423

830912

830913

830913

840130

840808

850301

850610

PMS

VOID

VOID

FC

FC

VOID

VOID

VOID

PMS

FC

FC

PMS

FC

FC

PMS

FC

FC

VOID

VOID

PMS

VOID

VOID

FC

FC

FC

FC

MD

SWITCH

MD

VOID

MD

VOID

PMS

wv

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY SL - SEAT LEAKAGE

DC - DESIGN CHANGE FC - CROSS-CONNECTING FAILURE SWITCH - NON-FUNCTIONAL FAILURE OF LIMIT SWITCH
Table B.1.d. (continued)

MODE/MECHANISM(if applicable)

MARK NO. HISTORY SUMMARY

2-MOV-J

2-MOV-I

1-MOV-G

1-MOV-G

1-MOV-H

1-MOV-H

1-MOV-H

COMPONENT

MOV

MOV

MOV

MOV

MOV

MOV

M. R. f

43600

20406

23350

10274

10275

26527

PROBLEM DESC

2-MOV-J INSP GREASE

2-MOV-I TORQUE SWITCH

INVESTIGATE/REPAIR

1-MOV-G

1-MOV-G ADJUST TORQUE

1-MOV-H ADJUST TORQUE

SWITCH

1-MOV-H CHECK CONTROLS

RTSVDT CLASSIFICATION*

w

lb.

0D

1-MOV-H

1-MOV-H

1-MOV-G

MOV 30387 1-MOV-H WILL NOT STROKE

MOV 32946 1-MOV-H REPAIR FLEX

MOV 35735 PERFORM EWR-85-224-B

MOV 38638 ACTUATOR GREASE REPLACEMENT

MOV 38692 ACTUATOR GREASE REPLACEMENT

MOV 39300 1-MOV-H REPLACE BEARINGS

MOV 43599 2-MOV-I TNSP GREASE

CHECKED LUBRICANT FOUND IT NOT TO BE NEBULA ER-O 851128

TOOLS 10- CRESENT WRENCH

CHECK TORQUE SWITCH PROCEDURE EMP-C-3PL-143 850610

REMOVED MOUNTING BOLTS FROM TORQUE SWITCH AND 850823

REPLACED THEM WITH THE RIGHT LENGTH BOLTS.

TIGHTENED SECURELY AND REQUESTED OPERATORS TO

CYCLE VALVE. VALVE OPERATED UNSATISFACTORY AND

VOID - WORK TO BE DONE ON EW4 85-224A 851101

VOID - WORK TO BE DONE ON EWR 85-224A. 851101

INVESTIGATED SWITCH, FOUND NO PROBLEM. CONTROL 851114

ROOM - CYCLED VALVE, NO PROBLEM WAS FOUND,

SATISFACTORY VALVE, 11/13/85.

CYCLED VALVE SEVERAL TIMES. OPENED T1 2.4, T2 2.8, 860211

AND T3 2.9;

CLOSED T1 2.8, T2 2.6, T3 2.6, FOUND NO PROBLEM AT

THIS TIME.

NO PROBLEM FOUND. 860421

ADJUSTED RESET AND PROPORTIONAL BAND ON 860517

CONTROLLER. CYCLING DAMPENED OUT, OPERATES

GREASE CHANGEOUT/NEW TYPE GREASE 860730

DISASSEMBLED MOV AND INSPECTED IAW PROCEDURE, ALL

INTERNAL PARTS, SEALS, AND GASKETS. SEALS AND

GASKETS SATISFACTORY, INTERNAL PART

HARD TO OPERATE/DIRT ON STEM 860806

DISASSEMBLED, CLEANED, REASSEMBLED, AND INSTALLED

NEBULA EP-O GREASE. VALVE TESTED SATISFACTORY ON

OPERATION, WR 333665.

MOTOR HOIST/BEARINGS BAD 860807

DISCONNECTED MOTOR, REPLACED BEARINGS, RECONNECTED

AND CYCLED SATISFACTORY. RECONNECTED MOTOR TEST, RAN

SATISFACTORY.

CHECKED LUBRICANT. FOUND THAT IT IS NOT NEBULA 861128

EP-O TOOLS- 10- CRESENT.

PMS

PMS

FC

VOID

VOID

VOID

BL

PMS

PMS

FC

1-MOV-H

1-MOV-H

2-MOV-I

PMS

FC

PMS

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY SL - SEAT LEAKAGE

DC - DESIGN CHANGE FC - CROSS-CONNECTING FAILURE SWITCH - NON-FUNCTIONAL FAILURE OF LIMIT SWITCH
Table B.1.d. (continued)

MARK NO.

1-MOV-H

1-MOV-H

2-MOV-J

2-MOV-I

2-MOV-J

2-MOV-I

1-MOV-G

2-MOV-J

COMPONENT M. R. I PROBLEM DESC

MOV 33601 1-MOV-H CHECK BEARINGS

MOV 39313 INSTALL PIPE CAP

MOV 44510 REPLACE GREASE

MOV 10272 2-MOV-I RESET TORQUE

MOV 10273 2-MOV-J ADJUST TORQUE

MOV 44511 CHANGE OUT GREASE

MOV 35366 PE-INVESTIGATE/REPAIR NOV

MOV 45271 2-MOV-J HIGH AMPS

MODE/MECHANISM(if applicable)

HISTORY SUMMARY

VOID - COMPLETED ON WO 039300.

INSTALLED PIPE CAP.

BAD GREASE/WRONG GREASE INSTALLED

CHANGED GREASE TO EXXON NEBULA EPO. PARTS-EXXON

NEBULA EPO 0214701 GASKET SET 4610484

VOID TO 044985

VOID TO 044986

BAD GREASE/WRONG GREASE INSTALLED

DISASSEMBLED, CLEANED, REPLACE DEFECTED PARTS

TIPPER FLANGE FINGER SPACER, UPPER RACE AND

UPPER BEARING.'

VOID - VALVE TESTED OPEN AT 65 SEC - MAXIMUM

ALLOWABLE IS 90 SEC - IAW PT 18.6 AT STATIC

CONDITION WITH NO DELTA-P ACROSS VALVE

SATISFACTORY.

VOID... IN REVIEWING MOVATS TEST REPORT #2B1-11-886

THIS VALVE IS FULLY OPERABLE. A SLIGHT OVERCURRENT

CONDITION CAN BE TOLERATED DUE TO IT BEING A

NON CONTINUOUS DUTY MOTOR

RTSVDT CLASSIFICATION*

860815

860902

861122

861124

861124

861128

VOID

MD

PMS

VOID

VOID

PMS

870115 VOID

870122 VOID

* PMS - PREVENTIVE MAINTENANCE VOID - VOIDED MD - MINOR DEFICIENCY

FC - CROSS-CONNECTING FAILURE

SWITCH - NON-FUNCTIONAL FAILURE OF LIMIT SWITCH
Table B.1.e. MAINTENANCE RECORDS FOR THE AUXILIARY FEEDWATER SYSTEM 3-INCH CHECK VALVES

MODE/MECHANISM(if applicable)

MARK NO. COMPONENT M. R. I PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSIFICATION*

1-CV-J

1-CV-H

2-CV-J

1-CV-I

2-CV-I

2-CV-H

1-CV-H

2-CV-1

2-CV-I

2-CV-I

1 -CV- I

1-CV-H

1-CV-J

2-CV-I

2-CV-H

I-CV-I

2-CV-H

2-CV-I

1 -CV- I

1 -CV- I

1-CV-I

2-CV-J

2-CV-J

2-CV-J

2-CV-J

2-CV-J

2-CV-J

2-CV-I

2-CV-H

2-CV-H

2-CV-I

2-CV-J

1-CV-H

1-CV-H

2-CV-H

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

4102000

4150916

4170136

4150915

4170137

4170138

8041550

101151201

105010745

107311540

109210813

109210811

109210815

10091400

111190310

111301340

110290942

110290938

112071058

112061045

112031010

110290941

202230826

203011630

202260813

205170805

205070641

205161150

205161147

312071039

312071040

312071041

401011220

312160902

312301334

INSPECT VALVE

INSPECT INTERNALS AND REPAIR

PULL AND INSPECT

INSPECT INTERNALS AND REPAIR

PULL AND INSPECT

PULL AND INSPECT

CHECK VALVE LEAKING

NEEDS FURMANITE MATERIAL

BODY TO BONNET LEAK

FURMANITE HAS BEEN BEFORE

OVERHAUL VALVE

OVERHAUL VALVE

OVERHAUL VALVE

CHECK VALVE

INSTALL CHECK VALVE

CHECK VALVE HAS BODY TO BONNET LEAK

REPLACE VALVE

REPLACE VALVE

PLUG ON VALVE LEAKS

CHECK VALVE LEAKS

REPLACE GASKET

REPLACE VALVE

FURMANITE

REPAIR FURMANITE

REPAIR CAP

WELD CHECK VALVE DISC SHAFT PLUG

PLUGS ON BODY OF CHECK VALVE

WELD DISC SHAFT PLUGS

WELD DISC SHAFT PLUGS

CHECK VALVE LEAKS THROUGH

CHECK VALVE LEAKS THROUGH

CHECK VALVE LEAKS THROUGH

FURMANITE

LEAKS THROUGH

BODY TO BONNET LEAK

REPAIRED VALVE

REPAIRED VALVE

INSPECTED SAT

INSPECTED AND REPAIRED VALVE

INSPECTED SAT

COMPLETED

WELDED PLUG AS PER REQUEST

COMPLETED

FURMANITE BONNET LEAK

SEALED LEAK

COMPLETED AS ABOVE

COMPLETED AS ABOVE

COMPLETED AS ABOVE

VOID - TO BE UPDATED

VOID - WORK DONE ON ANOTHER MR

VOID

REPLACED CV CHECK VALVE 2-CV-H

REPLACED CHECK VALVE

SEAL WELDED PLUGS

FIXED PLUG ON VALVE

REPLACED RING

REPLACED CHECK VALVE 2-CV-J

COMPLETED MR FOR REPAIRS

INSTALLED NEW BONNET RING GASKET

INSTALLED BONNET RING

SEAL WELDED PLUG

VOID

SEAT WELDED PLUG

SEAL WELDED PLUG

LAPPED VALVE DISH TO SEAT

CUT OUT SEAL WELD

LAPPED SEATS

PEENED PLUG IN BODY

CLEANED VALVE & LAP SET

VOID - COMPLETED ON MR 312310920

800415

800417

800422

800424

800425

800426

801017

810123

810511

810807

810930

810930

810930

811022

811120

811203

811205

811205

811207

811207

811211

811215

820226

820302

820303

820520

820520

820522

820522

831214

831221

831221

840107

840107

840127

LK

LK

PMS

LK

PMS

PMS

BL

BL

BL

BL

LK

LK

LK

VOID

VOID

VOID

LK

LK

BL

BL

BL

LK

BL

BL

BL

BL

VOID

BL

BL

LK

LK

LK

BL

LK

VOID

w

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED LK - UNDETECTED LEAKAGE FAILURE
Table B.1.e. (continued)

MODE/MECHANISM(if applicable)

MARK NO. COMPONENT M. R. # PROBLEM DESC HISTORY SUMMARY RTSVOT CLASSIFICATION*

1-CV-H

1-CV-H

2-CV-J

2-CV-I

2-CV-H

1-CV-H

2-CV-H

1-CV-I

1-CV- I

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

401180631

401031302

403131437

403131441

401031301

404080900

312310920

406120857

2385

NO ADJUSTMENT LEFT ON PACKING GLAND

REPAIR TO ORIGINAL WELD PLUGS

OPEN & INSPECT VALVE

OPEN AND INSPECT VALVE

REPAIR TO ORIGINAL FURMANITED

CHECK VALVE LEAKS THROUGH

FURMANITE BODY TO BONNET LEAK

CHECK VALVE LEAKS THROUGH

OVERHAUL VALVE

VOID - THIS VALVE IS AN AUX FD CK VALVE

WELDED PLUGS

CUT OUT VALVE, SHIP TO CRANE FOR REPAIR

CUT OUT VALVE, SHIP TO CRANE FOR REPAIR

SHIPPED VALVE TO CRANE FOR REPAIRS

OVERHAULED CHECK VALVE

VOID - COMPLETED ON MR 2312371920

VOID - NO PROBLEM

DISASSEMBLED VALVE AND INSPECTED INTERNALS. LAP

SEAT AND DISC GOT 100% BLUEING. REMOVED 2-PIN

RETAINIG PLUGS. INSTALLED PIN, RETAINING PLUGS

AND WELDED.

840307

840313

840406

840406

840406

840509

840521

840723

841210

VOID

BL

LK

LK

LK

LK

VOID

VOID

LK

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED LK - UNDETECTED LEAKAGE FAILURE
Table B.1.f. MAINTENANCE RECORDS FOR THE AUXILIARY FEEDWATER SYSTEM 4-INCH CHECK VALVES

MODE/MECHANISM(if applicable)

MARK NO. COMPONENT M. R. # PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSIFICATION*

1-CV-C

1-CV-B

2-CV-C

2-CV-C

2-CV-C

2-CV-C

2-CV-C

2-CV-C

2-CV-B

2-CV-C

2-CV-C

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

304291402

304291400

305040509

311181137

311201310

311202330

401270925

403070933

403131354

01742

01799

LEAKS BACK THROUGH

LEAKS BACK THROUGH

CHECK VALVE

CHECK VALVE LEAKS BY

2-CV-C IS LEAKING BY

CHECK VALVE LEAKS BACK

RESEAT VALVE

LEAKS THROUGH RESEAT

OPEN AND INSPECT VALVE

LEAKS THROUGH RESEAT

OVERHAUL VLV.

REPAIR VALVE

REBUILT VALVE

LAPPED SEAT REPLACED NUTS

PERFORMED CLEANLINESS INSPECTION

INSPECTED VALVE INTERNALS

VOID - COMPLETED ON MR 311201310

LAPPED SEAT AND DISC

VALVE CHECKED 2-CV-C

NOTHING FOUND 100%

VOID--TO BE COMPLETED ON WO #01799.

DISASSEMBLE VALVE LAPPED SEAT AND DISC, HAVE

100% BLUEING.

830504

830525

830926

831119

831120

831121

840128

840313

840408

841218

841218

LK/OO

LK/0O

LK/00

LK/00

LK/OO

VOID

LK/00

LK/OO

PMS

VOID

LK/O0

* PMS - PREVENTIVE MAINTENANCE VOID - VOIDED LK - UNDETECTED LEAKAGE FAILURE 00 - BACKFLOW FAILURE
Table B.1.g. MAINTENANCE RECORDS FOR THE AUXILIARY FEEDWATER SYSTEM 6-INCH CHECK VALVES

MODE/MECHANISM(if applicable)

HISTORY SUMMARY MARK NO. COMPONENT M. R. # PROBLEM DESC

RTSVDT CLASSIFICATION*

2-CV-D

2-CV-F

2-CV-E

2-CV-G

2-CV-F

2-CV-A

2-CV-A

2-CV-F

2-CV-G

1-CV-A

2-CV-O

2-CV-F

2-CV-E

2-CV-A

2-CV-A

2-CV-F

2-CV-D

2-CV-G

2-CV-D

2-CV-D

2-CV-E

2-CV-G

2-CV-F

2-CV-F

2-CV-F

2-CV-F

2-CV-F

2-CV-F

2-CV-A

2-CV-E

2-CV-E

VALVE 4141442 CHECK VALVE

VALVE 4141441 CHECK VALVE

VALVE 4141440 CHECK VALVE LEAKS

VALVE 4141443 CHECK VALVE

VALVE 203040635 REPAIR VALVE LEAK

VALVE 301131830 LEAKS BY SEAT

VALVE 301131150 OVERHAUL LEAK THROUGH CHECK VALVE

VALVE 304212311 LEAKS THRU

VALVE 304212312 LEAKS THRU

VALVE 304291401 LEAKS BACK THROUGH

VALVE 301131002 OVERHAUL LEAKS THROUGH

VALVE 301131004 OVERHAUL LEAKS THROUGH

VALVE 309062204 VALVE LEAKING

VALVE 311202358 VALVE LEAKING BACK

VALVE 311201520 CHECK VALVE LEAKING BACK THROUGH

VALVE 312071055 CHECK VALVE LEAKS THROUGH

VALVE 312071100 CHECK VALVE LEAKS THROUGH

VALVE 312090840 INSPECT VALVE FOR LEAKAGE

VALVE 403271000 OPEN & INSPECT VALVE

VALVE 404031130 LEAKS THROUGH

VALVE 403270840 OPEN AND INSPECT VALVE

VALVE 403131346 OPEN AND INSPECT VALVE

VALVE 404072152 VALVE LEAKS THROUGH

VALVE 404031540 LEAKS THROUGH

VALVE 404070928 VALVE LEAKS THROUGH

VALVE 404081000 REMOVE BONNET & INSPECT

VALVE 404021320 VALVE LEAKS BY

VALVE 403131342 OPEN AND INSPECT VALVE

VALVE 403131349 OPEN AND INSPECT VALVE

VALVE 304212314 LEAKS THRU

VALVE 01222 OVERHAUL VLV.

VALVE 25925 -PS- OVERHAUL VALVE

VOID

VOID

VOID

VOID

VOID - TO BE WORKED ON 2112111242

VOID - NOT A PROBLEM AT THIS TIME

OVERHAULED VALVE

LAPPED SEAT + DISK

LAPPED DISK + SEAT

REWORKED VALVE

LAPPED SEATS

GROUND SEAT AND DISCONNECTED

SEAL WELDED PLUGS TO VALVE BODY

VOID - TO BE DONE ON MR 311201520

DISASSEMBLED VALVE

INSPECTED VALVE INTERNALS

NO LEAKS FOUND

REMOVED VALVE & BLUED TO 100%

OPENED VALVE FOR INSPECTION, FOUND

REWORKED VALVE

HAD DISC MACHINED, LAPPED DISC

100% BLUE CHECK

INSPECTED VALVE AND LAPPED

OVERHAULED INTERNALS

RELAPPED & TESTED PRIOR TO ASSEMBLY

OPENED AND INSPECTED VALVE

MACHINED TEN FROM DISC 100%

100% BLUE CHECK GOOD

100% BLUE CHECK CHANGED

VOID-COMPLETED ON WK ORDER 001222

DISASSEMBLE VALVE AND INSPECT INTERNALS LAP SEAT

AND DISC AS NECESSARY TO GET 100% BLUEING

VOID NOT REQUIRED

800610

800610

800610

800610

821213

830117

830117

830426

830426

830520

830815

830926

831006

831121

831129

831213

831214

831214

840406

840406

840406

840406

840408

840408

840408

840408

840408

840408

840408

840810

841114

861124

VOID

VOID

VOID

VOID

VOID

VOID

LK/OO

LK

LK

LK/0O

LK

LK

BL

VOID

LK/OO

LK

PMS

PMS

LK

LK

LK

PMS

LK

LK

LK

LK

LK

PMS

PMS

VOID

LK

VOID

tw

2-CV-F

* PMS - PREVENTIVE MAINTENANCE

00 - BACKFLOW FAILURE

BL - BOUNDARY LEAK VOID - VOIDED LK - UNDETECTED LEAKAGE FAILURE
Table B.1.g.

MARK NO.

2-CV-D

2-CV-E

1-CV-A

I-CV-A

1-CV-A

(continued)

COMPONENT

VALVE

VALVE

VALVE

VALVE

VALVE

M. R. #

25924

30558

49606

49058

53704

PROBLEM DESC

-P,S- OVERHAUL VALVE

-P,S- INSPECT/REPAIR VALVE

REPAIR LEAK

P-REPAIR CHECK VALVE

P-INVESTIGATE, REPAIR CHECK

VALVE

BL - BOUNDARY LEAK VOID - VOIDED LK

MODE/MECHANISM(if applicable)

HISTORY SUMMARY

DISSASEMBLED VALVE GROUND SEAT ON FLAPPER BLUED

SEATING SURFACES. REASSEMBLED VALVE TORQUED TO

368 FR LB. SEAL WELD PLUG INSIDE OF VALVE.

REWORK VALVE/UNK

TACK WELDS ON PIN PLUG TO BE GROUND OFF

THEN REWELDED AFTER VALVE WORK COMPLETE. OPEN

VALVE AND INSPECTED INTERNALS. FOUND 1/16-

LEAKING THROUGH/NORMAL WEAR

AS FOUND - CHECK VALVE SUPPOSEDLY LEAKING BY.

WATER RUNNING OUT OF DRAIN VALVE BETWEEN PUMP

AND CHECK VALVE. REMOVED CAP ON

LEAK BY SEAT/WORN DISC

DISASSEMBLED VALVE BLUED SEAT. SEAT LOOKED OK.

DISC WORN OUT AND PITTED. LAPPED DISC BLUED 100%.

REASSEMBLED VALVE.

LEAK/WEAR

AS FOUND - VALVE SEAT CORRODED AND SLIGHTLY PITTED,

WORK PERFORMED. REMOVED BONNET PIN AND DISK,

CLEANED VALVE PIN AND BONNET.

- UNDETECTED LEAKAGE FAILURE

RTSVDT

861202

870104

870214

870214

870528

CLASSIFICATION*

LK

LK

LK/OO

LK/OO

LK/OO

W

oz * PMS - PREVENTIVE MAINTENANCE

00 - BACKFLOW FAILURE

I,\
Table B.I.h. MAINTENANCE RECORDS FOR THE AUXILIARY FEEDWATER SYSTEM 1-INCH CHECK VALVES

MODE/MECHANISM(if applicable)

MARK NO. COMPONENT M. R. # PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSIFICATION*

1-FW-159

1-FW-163

1-FW-159

I-FW-144

1-FW-174

1-FW-144

1-FW-159

1-FW-144

1-FW-175

1-FW-144

1-FW-174

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

910212300

910212340

106180924

305012002

305012003

304291401

304291400

28174

LEAKS BY

LEAKS BACK BY

REPLACE HANDLE ON VALVE

CHECK VALVE LEAK

CHECK VALVE LEAK

LEAKS BACK THROUGH

LEAKS BACK THROUGH

OPEN AND INSPECT FOR BLOCKAGE

ADJUST PACKING

INSPECT VALVE AS REQUIRED

P-REPAIR VALVE

VOID - NO PROBLEM AT THIS TIME

VOID - NO PROBLEM AT THIS TIME

REPLACED HANDLE WITH NUT

REWORKED VALVE

REPAIR VALVE

REBUILT VALVE

REBUILT VALVE

INSPECT/EWR

DISASSEMBLED VALVE CLEANED, INSPECTED INTERNALS,

BLUED SEAT, GOT 100% BLUE, REASSEMBLED VALVE

TORQUED BOLTS TO 45 FT LBS NO BLOCKAGE

LEAK/ADJUST

FOUND VALVE LEAKING, ADJUSTED 4 FLATS, LEAK

STOPPED. ROOM FOR MORE ADJUSTMENT.

OPENED VALVE, INSPECTED INTERNALS AND FOUND

EVERYTHING SATISFACTORY. CLOSED OUT VALVE.

METAL BROKEN/PISTON AND SEAT

AS FOUND 2/6/87 - VALVE SEATS BROKEN AWAY FROM

PISTON, CUT OLD VALVE OUT OF SYSTEM, INSTALLED

NEW VALVE AND CLEANED FOR NDE.

810429 VOID

810429 VOID

810621 MD

830524 NFF

830524 NFF

830525 NFF

830525 NFF

860221 PMS

860320 BL

860722 PMS

870219 NFF

VALVE 32186

VALVE 38576

VALVE 49059

w

*VOID - VOIDED MD - MINOR DEFICIENCY NFF - NON-FUNCTIONAL FAILURE
Table B.l i. MAINTENANCE RECORDS FOR THE AUXILIARY FEEDWATER SYSTEM 1-INCH CHECK VALVES

MODE/MECHANISM(if applicable)

MARK NO. COMPONENT M. R. # PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSIFICATION*

2-FW-130

1-FW-300

2-FW-134

l-FW-91

1-FW-304

FE-202A

FE-202B

w

2-FW-288

1-FW-30

1-FW-31

1-FW-61

1-FW-93

1-FW-60

1-FW-61

1-FW-30

1-FW-31

1-FW-92

1-FW-59

1-FW-62

1-FW-93

2-FW-130

1-FW-92

2-FW-130

2-FW-135

2-FW-134

1-FW-30

1-FW-29

1-FW-30

1-FW-185

2-FW-185

2-FW-134

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

807102341

808201850

911141147

4170340

101160931

202230830

202230825

104201040

112111243

302131003

302131108

302141703

302141125

302141701

302131113

302131112

302131002

302131116

302141702

302131107

302131106

304220820

306261210

304211457

304221001

312010741

312151155

312160917

312160916

401040834

401040820

401191900

LEAKS THROUGH WHEN SHUT

LEAKS BY SEAT

VALVE HANDLE BROKEN

AUX FEEDWATER FLOW ORIFICE

VALVE NOT OPERABLE, STEM BROKEN

UPPER ISOLATION VALVE LEAKING FURMANITE

LOWER ISOLATION VALVE BLOWS FURMANITE

REPAIR AUX FEEDWATER CHECK VALVE

HANOWHEEL MISSING

VALVE HAS PACKING LEAK

VALVE LEAKS BY WHEN SHUT

PACKING LEAK

PACKING LEAK

PACKING LEAK

VALVE LEAKS

VALVE LEAKS

VALVE HAS PACKING LEAK

VALVE LEAKS BY WHEN SHUT

PACKING LEAK

VALVE LEAKS

VALVE LEAKS BY WHEN SHUT

VALVE STEM BROKEN

VALVE BODY TO BONNET LEAK

VLV NEEDS NEW STEM AND HANDWHEEL

VALVE LEAKS BY

HANDWHEEL SPINS FREE

VALVE CASING LEAK

WON'T OPERATE

HOLE IN VALVE - WON'T OPERATE

CLEAN AND GREASE VALVE STEM

CLEAN AND GREASE VALVE STEM

PACKING GLAND FOLLOWER BLEW OUT

CLEANED INTERNALS

VOID

REPLACED VALVE 2-CV-134

REPAIRED PACKING LEAK

DISASSEMBLE, MAKE NEW STEM

COMPLETED MR FOR REPAIRS

COMPLETED

REMOVED FURMANITE AND PLUGGED HOLES

REPLACED MISSING HANDWHEEL

VOID COMP ON MR 302131112

VOID WK DONE ON MR 302131002

VOID DONE ON MR 302131113

VOID DONE ON MR1302131106

ADDED ONE RING GARLOCK 98

COMPLETED

COMPLETED LAPPED + REPACKED

COMPLETED REPACKED + LAP

COMPLETED LAPPED + REPACKED

ADDED PACKING

LAPPED GATE AND SEAT

LAPPED GATE AND SEAT

VOID

VOID WK TO DONE ON MR1306290246

REPLACED VALVES

REPLACED VALVE + NIPPLE CAP

REPLACED HANDWHEEL

VOID - TO BE DONE ON MR 312160916

TOOK VALVE OFF BACK

LUBED STEM

CLEANED & LUBRICATED

CLEANED & LUBRICATED

INSTALLED 7 RINGS OF PACKING

- MINOR DEFICIENCY** SL - SEAT LEAKAGE

780713

781218

791129

800420

810119

820226

820226

820422

820522

830215

830215

830223

830223

830314

830314

830315

830315

830315

830317

830322

830322

830422

830628

830806

830922

831209

831219

831221

831221

840109

840109

840111

SL

VOID

MD

BL

MD

BL

BL

BL

MD

VOID

VOID

VOID

VOID

BL

SL

SL

SL

SL

BL

SL

SL

VOID

VOID

MD

SL

MD

VOID

MD

MD

PMS

PMS

BL

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED

** MANY OF THE MINOR DEFICIENCIES ARE MINOR BECAUSE THE FAILED COMPONENT HAS NO SIGNIFICANT SAFETY FUNCTION, FOR EXAMPLE

THE FAILURE OF A STEM IN A 3/4 INCH DRAIN VALVE IS INSIGNIFICANT FROM A SAFETY STANDPOINT.
Table B.1.i. (continued)

MARK NO.

1-FW-61

1-FW-61

2-FW-134

2-FW-61

2-FW-62

1-FW-93

1-FW-286

1-FW-61

1-FW-61

1-FW-130

1-FW-299

2-FW-130

1-FW-130

2-FW-130

1-FW-61

1-FW-61

COMPONENT M. R. # PROBLEM DESC

VALVE 401100540 ONE HALF GPM PACKING LEAK

VALVE 401082321 BODY TO BONNET LEAK

VALVE 403311445 VALVE LEAKS BY

VALVE 308061204 REWORK VALVE

VALVE 308061206 REPAIR VALVE

VALVE 404080903 VALVE BINDS UP, FREE UP

VALVE 404110401 VALVE STEM SHEARED OFF

VALVE 406092115 NEEDS TO BE FURMANITED

VALVE 406120856 BODY TO BONNET LEAK, FURMANITE

VALVE 407222111 VALVE LEAKS THROUGH WHEN SHUT

VALVE 408011327 NEEDS 3/4 PIPE CAP

VALVE 112111242 REPLACE HANDWHEEL

VALVE 407231629 REPLACE VALVE

VALVE 803250015 WELD LEAK

VALVE 2474 RETURN VALVE TO ORIGINAL

VALVE 10345 REPAIR B/B LEAK

VALVE 20212 2-FW-93 PACKING LEAKS

VALVE 27653 REPAIR LEAK AT HINGE PINS

VALVE 28178 INSPECT FOR BLOCKAGE

MODE/MECHANISM(if applicable)

HISTORY SUMMARY

VOID - COMPLETED ON MR 1401082321

REPLACED GASKET AND REPACKED

REPLACED VALVE & SECTION OF PIPING

LAPPED IN VALVE

LAPPED IN DISK TO SEAT

VOID - AS PER EWELL

REPLACED VALVE BONNET ON

VOID - TO MR 1406180436

INJECTED BODY TO BONNET LEAK WITH

REPLACED PIPE CAP

INSTALLED PIPE CAP

VOID - COMPLETED ON WO 001017

VOID - COMPLETED ON WO 002925

REPLACED CORRODED LINE

DISASSEMBLED VALVE AND INSPECTED INTERNALS, REPAIR

AS NECESSARY. INSTALLED NEW SEAL RING, STUDS, AND

NUTS.

LAPPED SEATING SURFACE. BLUE CHECKED VALVE 100%

ONE SIDE, 90% OTHER. TORQUED BOLTS TO 167 FT/LBS.

REPAIRED.

PACKED VALVE

REMOVED HINGE PIN PLUGS AND PUT THREAD COMPOUND

ON PLUGS AND REINSTALLED.

PULL TO INSPECT/NO BLOCKAGE

REMOVED BONNET FROM BODY FOUND NO

BLOCKAGE IN LINE ON EITHER SIDE OF VALVE. BLUED

SEATING SURFACE FOUND TO HAVE 100% CONTACT. CLEANED

RTSVDT

840130

840313

840408

840408

840408

840412

840417

840625

840627

840730

840810

840810

840811

780329

110284

CLASSIFICATION*

VOID

BL

SL

SL

SL

VOID

MD

VOID

BL

BL

BL

VOID

VOID

BL

PMS

121584 BL

'.0 2-FW-93

2-FW-177

2-FW-145

060485

020886

022186

BL

BL

PMS

* PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY** SL - SEAT LEAKAGE

** MANY OF THE MINOR DEFICIENCIES ARE MINOR BECAUSE THE FAILED COMPONENT HAS NO SIGNIFICANT SAFETY FUNCTION, FOR EXAMPLE

THE FAILURE OF A STEM IN A 3/4 INCH DRAIN VALVE IS INSIGNIFICANT FROM A SAFETY STANDPOINT.
Table B.1.i. (continued)

MARK NO.

2-FW-147

1-FW-62

1-FW-93

1-FW-62

1-FW-61

1-FW-145

1-FW-147

2-FW-146

2-FW-168

1-FW-155

COMPONENT

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

M. R. I

28176

16733

35289

37511

37512

38600

38601

28177

42338

33987

PROBLEM DESC

-I- INSPECT FOR BLOCKAGE

P-REPLACE B/B GASKET

REPACK VALVE

REPAIR AS REQUIRED

REPAIR AS REQUIRED

INSPECT VALVE

INSPECT VALVE INTERNALS

-P- INSPECT VALVE

REPAIR PACKING LEAK

ADJUST PACKING

MODE/MECHANISM(if applicable)

HISTORY SUMMARY

OPENED VALVE ACCCORDING TO PROCEDURE, INSPECTED

INTERNAL. BLUED SEATS.

SEAT LEAKAGE/NORMAL WEAR

DISASSEMBLED VALVE LAP SEAT AND GATE. 100%

BLUEING. REPACKED AND REASSEMBLED.

PACKING LEAK/NORMAL WEAR

REPACKED VALVE.

PACKING LEAK/NORMAL WEAR

TIGHTENED PACKING TO STOP LEAK.

TIGHTENED PACKING TO STOP LEAK.

OPENED VALVE FOR OPERATORS. INSPECTED AND FOUND

SATISFACTORY. CLOSED OUT VALVE.

OPENED VALVE FOR OPERATORS INSPECTION, ALL WAS

FOUND SATISFACTORY. CLOSED VALVE.

VOID NOT REQUIRED PUMP OVERHAULED

VOID NOT REQUIRED.

VALVE PACKING GLAND ADJUSTED.

RTSVDT

022186

052886

060986

062486

062486

072286

072286

110586

111886

011187

CLASSIFICATION*

PMS

BL

BL

BL

BL

PMS

PMS

VOID

VOID

PMS

tza * PMS - PREVENTIVE MAINTENANCE BL - BOUNDARY LEAK VOID - VOIDED MD - MINOR DEFICIENCY** SL - SEAT LEAKAGE

** MANY OF THE MINOR DEFICIENCIES ARE MINOR BECAUSE THE FAILED COMPONENT HAS NO SIGNIFICANT SAFETY FUNCTION, FOR EXAMPLE

THE FAILURE OF A STEM IN A 3/4 INCH DRAIN VALVE IS INSIGNIFICANT FROM A SAFETY STANDPOINT.

.. I
Table B.1.j. MAINTENANCE RECORDS FOR THE AUXILIARY FEEDWATER SYSTEM PIPING

MARK NO. COMPONENT M. R. I PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSIFICATION*

6-WAPD-4

6-WCMV-52

6-WCMV-53

6-WAPD-2

6-WCMU-6

6-WCMU-7

6-WCMU-6

6-WCMU-7

1-FW-227

8-WCMU-5

8-WCMU-5

6-WCMU-8

6-WCMU-39

6-WAPD-50

6-WCMU-52

6-WCMU-52

6-WAPD-50

6-WCMU-4

6-WCMU-4

6-WCMU-4

6-WCMU-52

6-WCMU-52

6-WCMU-4

6-WCMU-4

6-WCMU-4

6-WCMU-4

6-WCMU-52

6-WAPD-150

6-WCMU-39

6-WAPD-150

6-WAPD-150

6-WAPD-50

6-WCMU-104

6-WCMU-104

6-WCMU-104

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

908131523

908131543

908131544

908131039

909171244

909171224

909171234

909171237

909121627

909171317

909171247

2071346

3251246

3211326

3211346

3211347

4260812

4150734

4081056

4081104

5061346

5061347

4150733

4150735

4081106

4150736

5061348

4241049

7021422

7151315

7151318

4230720

9080941

9080940

9091002

SHIM PER ATTACHED SKETCH

SHIM PER ATTACHED SKETCH

SHIM PER ATTACHED SKETCH

DC 79-S32A INSTALL CONSTRAINT

D/C 79-S32B INSTALL SNUBBER

D/C 79-S32B INSTALL SNUBBER

D/C 79-S32B INSTALL SNUBBER

DC 79-S32B INSTALL SNUBBER

PIPING BENT AND BROKEN 3A AUX FD PMP

0/C 79-S32B INSTALL SNUBBER

0/C 79-S32B INSTALL SNUBBER

DC 79-S32A REMOVE ROD HANGER

DC 79-S32C REMOVE U-BOLT

DC 79-S32C INSTALL STRAP

DC 79-S32C INSTALL STRAP

DC 79-S32 INSTALL STRUT

D/C 79-S32C SUPPORT MOD.

D/C 79-S32C INSTALL SUPPORT

DC 79-S32C INSTALL CONSTRAINT

DC 79-S32C INSTALL CONSTRAINT

D/C 79-S32C MODIFY SUPPORT

D/C 79-S32C MODIFY SUPPORT

D/C 79-S32C INSTALL SUPPORT

D/C 79-S32C INSTALL SUPPORT

DC 79-S32C INSTALL CONSTRAINT

D/C 79-S32C INSTALL SUPPORT

D/C 79-S32C INSTALL SUPPORT MOD.

D/C 79-S32C SUPPORT MOD.

D/C 79-S32C INSTALL SUPPORT MOD.

D/C 79-S32C INSTALL SHIM

D/C 79-S32C INSTALL SHIM

D/C 79-S32C SUPPORT MOD.

D/C 79-S56A INSTALL SUPPORT MOD

D/C 79-S56A INSTALL SUPPORT MOD

D/C 79-S56A INSTALL SUPPORT MOD

COMPLETED AS PER ATTACHED SKETCH

COMPLETED AS PER ATTACHED SKETCH

COMPLETED AS PER ATTACHED SKETCH

INSTALLED CONSTRAINT

INSTALLED SNUBBER MOUNT

INSTALLED SNUBBER MOUNT

COMPLETED AS PER ATTACHED SKETCH

COMPLETED AS PER ATTACHED SKETCH

REPLACED TUBING

COMPLETED AS PER ATTACHED SKETCH

COMPLETED AS PER ATTACHED SKETCH

COMPLETED

COMPLETED

COMPLETED

INSTALLED CONSTRAINT AS PER SKETCH

COMPLETED

COMPLETED

COMPLETED

COMPLETED

COMPLETED

COMPLETED

COMPLETED

COMPLETED

COMPLETED

COMPLETED

COMPLETED

COMPLETED

COMPLETED

COMPLETED

CLOSED

COMPLETED

VOID - NO WORK PERFORMED

BASE PLATE TUBES, ANCHOR BOLTS, WELDS

BASE PLATE TUBES, ANCHOR BOLTS, WELDS

BOXED IN PIPE AND INSTALLED BASE PLATE

790816

790816

790816

790817

790924

790924

790925

790925

790926

790927

791003

800212

800402

800409

800420

800425

800502

800520

800520

800520

800520

800520

800521

800527

800527

800527

800527

800603

800718

800728

800728

800902

800919

800919

800924

DC

DC

DC

DC

DC

DC

DC

DC

MD

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

* PMS - PREVENTIVE MAINTENANCE VOID - VOIDED MD - MINOR DEFICIENCY DC - DESIGN CHANGE
Table B.I.j. (continued)

MARK NO. COMPONENT M. R. # PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSIFICATION*

6-WCMU-104

6-WCMU-104

6-WAPD-50

6-WCMU-104

6-WCMU-104

6-WCMU-105

6-WAPD-50

6-WAPD-150

6-WCMU-150

6-WAPD-150

6-WAPD-50

6-MCMU-104

6-WAPD-150

6-WAPD-50

6-WAPD-50

6-WAPD-2

6-WAPD-50

6-WAPD-152

6-WAPD-50

6-WAPD-50

6-WAPD-50

6-WAPD-150

6-WCMU-150

6-WAPD

6-WAPD-1

8-WCMU-5

6-WAPD-2

6-WCMU-4

6-WAPD-150

6-WAPD-50

6-WCMU-1l

6-WCMV-104-151

6-WCMV-139-151

6-WAPD-102

1-FW-229

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

PIPING

9091003

9031004

4221422

9031001

9091001

9091000

4221424

4300909

9150939

4300901

4221423

8260931

9221304

10020736

5281301

9091041

9021406

9260902

9041301

4260811

9050715

9300900

12030900

9110847

9260816

8251003

9260817

4241053

104130910

5011039

9091040

105111259

105111320

106161203

106091207

D/C 79-S56A INSTALL SUPPORT MOD

DC79-S56C INSTALL SUPPORT

D/C 79-S32C INSTALL SUPPORT

0C79-556C INSTALL SUPPORT

D/C 79-S56A INSTALL SUPPORT MOD

D/C 79-S56A INSTALL SUPPORT MOD

D/C 79-S32C SUPPORT MOD.

D/C 79-S32C SUPPORT MOD.

D/C 79-S56A INSTALL SUPPORT MOD

D/C 79-S32C SUPPORT MOD.

D/C 79-S32C SUPPORT MOD.

DC 79-556A INSTALL SUPPORT

D/C 79-S56A INSTALL SUPPORT MOD

D/C 79-S32C REMOVE PORTION OF SUPPORT

D/C 79-532C INSTALL SUPPORT MOD.

D/C 79-S32A REMOVE ROD HANGER

DC79-S32C INSTALL SUPPORT

D/C 79-S56A INSTALL SUPPORT MOD

D/C 79-S32A INSTALL SHIMS PER

D/C 79-S32C SUPPORT MOD.

D/C 79-S32A INSTALL SUPPORT MOD

0/C 79-S56A INSTALL SUPPORT MOD

D/C 79-S56A INSTALL SUPPORT MOD

D/C 79-S32A INSTALL SPRING HANGER

D/C 79-S32A INSTALL VERTICAL/LATERAL

INSTALL SUPPORT

D/C 79-S32A INSTALL NEW SPRING

D/C 79-S32C INSTALL SUPPORT

D/C 79-S56A INSTALL SUPPORT MOD

D/C 79-S32C INSTALL SUPPORT

D/C 79-S32C REMOVE ROD HANGER

D/C 79-S56A INSTALL SUPPORT MOD

D/C 79-S56A INSTALL SUPPORT MOD

0/C 79-S56A INSTALL SUPPORT MOD

LEAK IN PIPING UPSTREAM 1-FW-229

COMPLETE

INSTALLED SUPPORT AS PER SKETCH

COMPLETE

BOXED IN PIPE AND INSTALLED BASEPLATE

NEW PIPE SUPPORT

INSTALLED NEW PIPE SUPPORT

INSTALLED PIPE CLAMP

INSTALLING ANGLE

INSTALLED TWO ANGLES WITH WELDS

INSTALL SUPPORT

INSTALL GUSSETS WITH WELDS

COMPLETED

BASE PLATES AND GUSSETS WITH WELDS

COMPLETED AS PER REVISION REQUEST

COMPLETED

REMOVED HANGER

COMPLETE PER PROCEDURE

BASE PLATE TUBE STAINLESS STEAL BOX

COMPLETE

INSTALLED SUPPORT

COMPLETED

INSTALLED SUPPORT MOD

INSTALL ANGLE AND SHIM PLATE

INSTALLED SPRING HANGER

JOB COMPLETED 12-9-80

INSTALLED SUPPORT

INSTALLED SPRING CAN PER SKETCH

COMPLETE

NEW SHIM

VOID

VOID

COMPLETE

COMPLETE

COMPLETE

TIGHTENED SWEDGELOCK FITTINGS

800925

800925

800926

800929

801001

801001

801004

801006

801009

801010

801015

801017

801021

801022

801102

801107

801109

801110

801111

801113

801117

801126

801203

801205

801216

801216

810202

810312

810421

810506

810506

810602

810602

810618

810927

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

DC

MD

w

N)

* PMS - PREVENTIVE MAINTENANCE VOID - VOIDED MD - MINOR DEFICIENCY DC - DESIGN CHANGE
Table B.1.j. (continued)

MARK NO. COMPONENT M. R. # PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSIFICATION*

2-TOP PIPING

FW-100ABC PIPING

6-WCMU-52-151 PIPING

2-FW-PI-255AB&CINSTR

PI-FW-155AB,C INSTR

6-WAPD-50-601 PIPING

6-WAPD-50-601 PIPING

6-WAPD-150-601 PIPING

2-MOV-F FLANGE

6-WCM11-5-151 PIPING

I-FW-FT-100A PIPE

6-WAPD-150-601 PIPING

FW-FT-100A PIPING

1-TDP PIPING

2-TDP PIPING

2-TDP PIPING

2-TDP PIPING

2-MDP-B PIPING

1-TDP PIPING

6-WCMU-8-151 PIPING

6-WUMU-108-151 PIPING

6-WCMU-111-151 PIPING

6-WCMU-111-151 PIPING

6-WCMU-111-151 PIPING

6-MUMV-56-151 PIPING

6-WCMU-11-151 PIPING

6-WCMU-54-151 PIPING

6-WAPD-50-601 PIPING

1-MOP-A PIPING

l-FW-FE-100A FLOW

1-FW-FE-lOOA ELEMENT

2-CN-TK-1 TANK

1-MDP-B PIPING

2-FW-258 PIPE

2-MDP-A LAGGING

111020616

109271040

202101658

203241104

203250402

203180859

203180849

203080917

205070640

202101615

209021530

208110752

210120841

211080901

211080902

212062200

211011412

211020108

210300431

301101812

301251010

301251347

301251352

301251338

301130947

301130944

301241325

301112345

211020106

302131005

304052210

307271145

211020107

310201059

311211202

INSTALL HEAT TRACING ON AUX FO LINE

REPLACE GASKETS

D/C 79-S32A INSTALL SHIM

FABRICATE MOUNTING PLATES

FABRICATE AND INSTALL MOUNTING PLATE

0/C 79-532A PER SKETCH

D/C 79-S32A TIGHTEN U-BOLT

D/C 79-S32A PER SKETCH

FLANGE LEAKS BY

D/C 79-S32A INSTALL SHIM PER SKETCH

FLANGE LEAK ON FLOW TRANSMITTER

D/C 79-S32A INSTALL MODIFICATION

FLANGE LEAK AT FLOW ELEMENT

CLEAN OUT DRAINS ON PUMP

CLEAN OUT ALL DRAINS TO PUMP

FLANGE LEAK

10-YR ISI HYDROSTATIC TEST AUX FD PUMP

10-YR ISI HYDRO TEST OF AUX FEED PUMP

10 YEAR ISI HYDROSTATIC TEST

TEN-YEAR HORO

TEN-YEAR HYDRO

10-YEAR INSPECTION

10-YEAR INSPECTION

PERFORM TEN-YEAR INSPECTION

TEN-YEAR HYDRO TEST

TEN-YEAR HYDRO TEST

TEN-YR HYDRO

TEN-YEAR ISI HYDRO

10-YR ISI HYDRO TEST OF AUX FD PUMP

FLANGES TO FLOW ELEMENT LEAK

FLANGE LEAKS

10 YEAR HYDRO

10-YR ISI HYDRO TEST OF AUX FEED PUMP

PIPE NEEDS NEW INSULATION

OIL COOLER NEEDS LAGGING

INSTALLED HEAT TRACE, SATISFACTORY

VOID

ADDED SHIM

COMPLETED

FABRICATED MOUNTING BRACKETS

TIGHTENED U-BOLT

TIGHTENED U-BOLT

DELETED SHIM

WELD REPAIRED STEAM CUTS & HANDFITTED

ADDED SHIM

TIGHTENED UP THE ISOLATION

INSTALLED HANGER STRAP

INSTALLED 2 NEW FLEX

CLEANED OUT FOUNDATION DRAINS

CLEARED FOUNDATION DRAINS

SANDWICHED OLD GASKET

INSPECTION OF AUX FEED PUMP UNDER NO

INSPECTION OF AUX FEED PUMP

INSPECTION OF PIPING

FIRE MAIN INSPECTED, NO PROBLEM

TEST PERFORMED

INSPECTION COMPLETED

INSPECTION COMPLETED

INSPECTION COMPLETED

INSPECT PIPING, NO PROBLEM

PIPING INSPECTED, NO PROBLEM

INSPECT PIPING, NO PROBLEM

INSPECTION COMPLETED

WORK DONE UNDER STEAM GENERATOR HYDR

REPLACED 2 FLEX GASKETS

REPLACED GASKET

INSPECTION COMPLETE

INSPECTION COMPLETED

REINSULATED PIPE

REPLACED INSULATION

820112

820212

820215

820331

820331

820407

820407

820419

820527

820729

821013

821013

821015

821115

821115

821207

821207

821207

821220

830125

830125

830126

830126

830126

830127

830127

830127

830216

830228

830314

830407

830810

831019

831104

831202

DC

VOID

DC

DC

DC

DC

DC

DC

MD

DC

MD

DC

MD

PMS

PMS

MD

PMS

PMS

PMS

PMS

PMS

PMS

PMS

PMS

PMS

PMS

PMS

PMS

PMS

PMS

PMS

PMS

PMS

PMS

MD

w

LA

* PMS - PREVENTIVE MAINTENANCE VOID - VOIDED MD - MINOR DEFICIENCY DC - DESIGN CHANGE
Table B.1.j. (continued)

MARK NO. COMPONENT M. R. I PROBLEM DESC HISTORY SUMMARY

FW-FT-lOOA PIPING 210130841 FLANGE LEAK VOID - TO BE DONE ON MR 1312081531

1-FW-FE-100A ELEMENT 312081531 FURMANITE STEAM LEAK SEAL WELDED PIPE PLUGS

1-FW-153 BRACKET 403081501 TUBING TRAY BROKEN OFF REWELD SUPPORT

2-FW-89 PIPE 403171638 REMOVE RESTRAINT AS NECESSARY REMOVED AND REPLACED RESTRAINT

1-FW-FE-1O0A ELEMENT 404131324 BLANK CAVITATING VENTURI BLANKED VENTURI FOR HYDRO

2-FW-PP-151 PIPE 406211048 REMOVE FURMANITE BOX, REPAIR VOID - TO BE COMPLETED ON WO 002510

* PMS - PREVENTIVE MAINTENANCE VOID - VOIDED MD - MINOR DEFICIENCY DC - DESIGN CHANGE

RTSVDT CLASSIFICATION*

831216 VOID

831230 MD

840313 MD

840411 PMS

840427 PMS

840816 VOID
Table B.1.k. MAINTENANCE RECORDS FOR THE AUXILIARY FEEDWATER SYSTEM INSTRUMENTATION

MARK NO. COMPONENT M. R. # PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSIFICATION*

1-FW-FE-IOOA INSTR

1-FW-FE-100B INSTR

I-FW-FT-IOOA INSTR

1-FW-FT-IOOB INSTR

1-FW-FT-1ODC INSTR

2-FW-FT-200C INSTR

1-FW-FE-100C INSTR

1-FW-FE-IOOA INSTR

1-FW-FE-200B INSTR

1-FW-FE-200C INSTR

1-FW-FE-200ABC INSTR

1-FW-FE-100C INSTR

1-FW-FE-200C INSTR

I-FW-FE-IOOA INSTR

1-FW-FT-IOOB TRANS

1-FW-FE-200C INSTR

1-FW-FE-IOOB INSTR

2-FW-FT-200C TRANSMIT

2-FW-FI-200C METER

2-FW-FI-200B METER

2-FW-FI-200C METER

10185490

807061000

5050755

5050756

5050757

4020800

105221547

109300310

112100548

112100543

202021305

205191249

212140636

211240135

308110249

309062154

308170805

403191015

402151134

404011836

404011840

CALIBRATE FLOW INDICATOR

INDICATES 175 GPM WITH PUMP OFF

CALIBRATE TRANSMITTER

CALIBRATE TRANSMITTER

CALIBRATE TRANSMITTER

REPLACE TRANSMITTER

FLOW INDICATOR DOES NOT WORK-STUCK

A STEAM GAUGE AUXILIARY FEED FLOW

FLOW INDICATOR

FLOW INDICATOR

METERS BOUNCING

METER BOUNCING OFF ZERO

FLANGE MISSING STUD

CALIBRATE AS NECESSARY

REPLACE TRANSMITTER

ERRATIC INDICATION

FEED FLOW SPIKES FI-FW-IOOB

REDO THE ELECTRICAL SPLICES

METER INDICATES FLOW

CHECK TRANSMITTER & METER

CHECK TRANSMITTER & METER

CALIBRATED TRANSMITTER

REPLACES TRANSMITTER

CALIBRATED TRANSMITTERS

CALIBRATED TRANSMITTER

CALIBRATED TRANSMITTER

REPLACED AND CALIBRATED TRANSMITTER

WRONG VALVE LINE-UP

CHECKED CALIBRATION, OPENED VALVE

REPLACED INDICATOR

REPLACED INDICATOR

FILLED AND VENTED TRANSMITTER

CALIBRATED TRANSMITTER

INSTALLED STUD & NUTS

CALIBRATED TRANSMITTER

CHECKED LOOP AND XMTR

TRANSMITTED, STABILIZED

REPLACED AND CALIBRATED TRANSMITTER

VOID - NOT NEEDED

PERFORMED TRANSMITTER CALIBRATION

PERFORMED CALIBRATION 61

PERFORMED CALIBRATION 62

780516

780917

800506

800506

800506

800625

810710

811005

820119

820119

820305

821015

821221

830329

830811

830913

830930

840320

840325

840406

840411

GAUGE

GAUGE

GAUGE

GAUGE

GAUGE

GAUGE

GAUGE

GAUGE

GAUGE

GAUGE

GAUGE

GAUGE

MD

GAUGE

GAUGE

GAUGE

GAUGE

VOID

GAUGE

GAUGE

GAUGE

w

LA

* VOID - VOIDED MD - MINOR DEFICIENCY GAUGE - GAUGE REPLACEMENT OR CALIBRATION
Table B.2

Maintenance Records Broadly Classified as Failures

for the Auxiliary Feedwater System

B-57 NUREG/CR-5378
Table B.2.a. MAINTENANCE RECORDS BROADLY CLASSIFIED AS FAILURES FOR THE AUXILIARY FEEDWATER SYSTEM TURBINE DRIVEN FEED PUMPS

MARK NO.

1-TDP

1-TOP

I-TDP

1-TDP

1-TDP

1-TDP

1-TDP

2-TDP

2-TDP

1-TDP

2-TDP

2-TDP

2-TOP

2-TDP

2-TOP

2-TDP

2-TDP

1-TDP

2-TDP

1-TDP

2-TDP

COMPONENT

PUMP

PUMP

PUMP

TURB

PUMP

PUMP

INSTR

PUMP

PUMP

PUMP

GOVERNOR

PUMP

PUMP

PUMP

PUMP

BEARING

PUMP

PMP GOV

SWITCH

PUMP

PUMP

M. R. # PROBLEM DESC

801010430 GROSS OIL-LOW DISCHARGE PRESSURE

803030420 EXCESSIVE DISCHARGE PREE-PT15

901030450 GOV VALVE WILL NOT CONTROL PUMP SPEED

810040500 VARIOUS REPAIRS

912172125 OUTBOARD PUMP BEARING THROWING OIL

1240708 OIL SEAL PACKING LEAK

4131129 BROKEN CASE SWITCH

11170730 OVERSPEED TRIP VALVE TRIPS

205081945 GOVERNOR SET AT 4060 RPM

208132145 REPAIR OIL LEAK

212061305 REPAIR FEEDBACK ARM

302111050 PUMP TRIPS

303101430 SET SCREW MISSING

303181232 OVERSPEED TRIP

304250400 OIL SEAL LEAKING

306200726 REPLACE BEARING

309271700 HIGH BEARING VIBRATIONS

312311328 REPAIR GOVERNOR

402240947 PUMP WILL NOT CUT OFF IN AUTO

14061 MECHANICAL LINKAGE BROKEN

23379 PUMP INOPERABLE, REPAIR

27017 P-REPAIR OIL LEAKS

4170 INVESTIGATE PUMP BEARING LEAK

40487 SPRING REPLACEMENT

MODE/MECHANISM(if applicable)

HISTORY SUMMARY

RENEWED THRUST BEARING LININGS

REDUCED SPEED OF PUMP AT GOVERNOR

FIXED SATISFACTORY

REPAIRED AND TESTED GOVERNOR TRIP VALVE

RENEWED THRUST BEARING

RENEWED THRUST SHOE

INSTALLED NEW SWITCH

STRAIGHTENED LINKAGE

RESET RPM TO 3880

CHANGED THRUSTED SHAFT COLLAR JOURNAL

REINSTALLED SETSCREW

ADJUSTED OVERSPEED TRIP

ADJUSTED, DAMPER

PUT SPRING BACK ON HOOK

REPLACED BEARING AND THREAD SLOES

REPLACED BEARING AND SHOES

ADJUSTED LINKAGE

INSTALLED NEW SEAT

CHECKED SWITCH

REINSERTED ROD AND CLOSED SOCKET ENDS AROUND BALL

TIP.

REMOVED INBOARD AND OUTBOARD BEARING CAPSFOUND BOTH JOURNAL BEARINGS IN GOOD CONDITIONOUTBOARD THRUST BEARING -THRUST SHOES- WIPED AND

ROLLED OVER WITH BABBITT. ALIGNMENT

BAD BEARINGS/INSUFF. OIL FLOW

REPLACED BEARINGS, THRUST BEARINGS, AND REPACKED

PUMP.

BROKEN SLINGER/THRUSTING

REPLACED SLINGER, BEARINGS, WEAR RINGS, BALANCE

GOVERNOR VALVE NOT OPEN ALL THE WAY, SUSPECT BAD

SPRING. REMOVED OLD SPRING AND REPLACED WITH NEW

SPRING. OPS DID AN OPERABILITY TEST AND GOVERNOR

VALVE IS STILL NOT OPENING.

RTSVDT

780111

780303

790204

790420

791223

800210

800429

801118

820513

820824

821207

830216

830314

830321

830429

830927

831013

840111

840330

850214

850819

CLASSSIFICATION*

FR

FR

FR

FR

FR

FR

FR

FR

FR

FR

FR

FR

FR

FR

FR

FR

FR

FR

FR

FR

FR

U'

1-TDP

1-TDP

1-TDP

PUMP 860509 FR

PUMP

PUMP

860820

860907

FR

FR

* FR- POTENTIAL FAILURE TO RUN
Table B.2.a.

MARK NO.

1-TOP

I-TDP

1-TDP

1-TDP

(continued)

COMPONENT

PUMP

PUMP

PUMP

PUMP

M. R. #

41325

40454

40488

40491

PROBLEM DESC

OPEN,INSPECT,REPAIR GOV VALVE

ADJUST GOVERNOR VALVE LINKAGE

REPAIR OVERSPEED TRIP

VALVE LINKAGE ADJUSTMENT

MODE/MECHANISM(if applicable)

HISTORY SUMMARY

VALVE GOV LEAK THRU/STEAM CUT SEATS

REMOVE LINKAGE AND VALVE FORM SYSTEM. FOUND BODY

TO BE STEAM CUT ON SEATS. AS WE REMOVED BUSHING

LINKAGE/IMPROPER SET

DISCONNECTED LINKAGE L2 AND LI, REMOVED PIN FROM

SHAFT LI, SET STEAM GOVERNOR VALVE, LOOSENED

FISHER REGULATING SPRING AND SET AT 3/8.

VALVE CHECKED FOR FREEDOM OF MOVEMENT, FOUND TO BE

STICKING APPROXIMATELY 50X IN THE CLOSED POSITION.

VALVE DISASSEMBLY REVEALED HEAVY WEAR AND SOME

STEAM CUTS TO GUIDE.

WE FOUND THE LINKAGE OUT OF ADJUSTMENT AND

GOVERNOR LEVER HAD EXCESS WEAR. WE REMOVED THE OLD

LINKAGE AND GOVERNOR LEVERS,REPLACING SAME WITH

NEW LEVERS. THE NEW LEVERS HAD

RTSVDT CLASSSIFICATION*

860927 FR

860930 FR

860930 FR

860930 FR

w

'0
Table B.2.b. MAINTENANCE RECORDS BROADLY CLASSIFIED AS FAILURES FOR THE AUXILIARY FEEDWATER SYSTEM MOTOR DRIVEN FEED PUMPS

MODE/MECHANISM(if applicable)

MARK NO. COMPONENT M. R. # PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSIFICATION*

2-MOP-B

2-MDP-A

2-MDP-A

2-MDP-A

2-MDP-B

1-MDP-A

2-MDP-B

1-MDP-A

1-MDP-A

1-MDP-B

1-MDP-A

1-MDP-A

1-MDP-B

2-MDP-B

1-MDP-B

1-MDP-A

1-MDP-A

1-MDP-A

1-MOP-A

2-MOP-A

2-MDP-A

2-MDP-B

PUMP

PUMP

PUMP

PMP MTR

HX

HX

PUMP

PUMP

HX

HT EXCH

PUMP

INSTR

INSTR

PUMP

PUMP

MOTOR

PUMP

PUMP

BREAKER

MOTO

RELAY

PUMP

PUMP

PUMP

PUMP

902050137

902050130

902131327

902111545

901081400

912211400

7222155

12270930

101130847

101130846

101291401

105220735

105220737

4180731

111110340

203200519

203261300

210050528

306072125

309211500

310060105

15531

PUMP START NOT SATISFACTORY

PUMP START NOT SATISFACTORY

OIL COOLER END BELL CRACKED

MOTOR HEATER NOT WORKING

REPAIR HEATERS

TUBE LEAK

PUMP WILL NOT AUTO START

DAMAGE WAS CAUSED BY FREEZING

REPAIR BROKEN LUBE OIL COOLER

HEAD-ON COOLER BROKEN

LUBE OIL COOLER BROKEN

PUMP STARTED IN 62

PUMP STARTED IN 66

NO OIL PRESSURE

BEARING VIBRATION PUMP

MOTOR WAS SPRAYED WITH STEAM

DETERMINE FAILURE OF PUMP

FW LEAK UPSTREAM OF LUBE OIL COOLER

RELAY DROP ON A PHSE INST

REPAIR OR REPLACE MOTOR HEATER

REPLACE 2-MDP-A RELAY

2-MOP-B CHECK HEATERS

TIME DELAY TESTED SATISFACTORY

TIME DELAY TESTED SATISFACTORY

REPAIRED COOLER

INSTALLED NEW HEATERS - TESTED SAT

INSTALLED NEW HEATERS - TESTED SAT

COMPLETED REPAIRS

TESTED SATISFACTORY

FIXED SPLIT CASING

REPLACED GASKET AT HEAD

REMOVED HEAD, BRAZED TOGETHER

REPAIRED LUBE OIL COOLER HEADER

RESET AGASTATS

RESET AGASTATS

PACKED STUDS CHECKED OIL PRESSURE

REPLACED INBOARD BEARING

PERFORMED PI CURVE

BREAKER CLOSED SATISFACTORY

REPAIRED LEAK ON 3/4 PIPE

MOTOR BRIDGED + MEGGERED

REPLACED HEATER

REPLACED RELAY COIL FAILED

REMOVED BAD HEATER FROM MOTOR -NO STOCK ITEMHEATER ORDERED 3/25/85. REPLACED DEFECTIVE

HEATER, TEST SAT.

PERFORM PI CURVE ON MOTOR WINDINGS. TESTED

SATISFACTORY.

PERFORMED PI CURVE ON MOTOR WINDING.

LEAK/OIL IN WATER/WATER IN OIL.

REMOVED LUBE OIL COOLER AND HYDRO WITH 100 PSI

SERVICE AIR. NO LEAKAGE EVIDENT.

790207

790209

790324

790910

790910

791223

800725

810101

810114

810114

810201

810522

810522

810616

820309

820320

820330

821014

830611

831006

831012

850712

FS

FS

FR

FS

FS

FR

FS

FR

FR

FR

FR

FS

FS

FR

FR

FS

FS

FR

FS

FS

FS

FS

to

I-MDP-A

1-MDP-B

2-MOP-A

39854 1-FW-M-3A MOTOR WET

39853 1-FW-M-3B MOTOR WET

51214 REPLACE/REPAIR LUBE OIL COOLER

860826 FS

860826 FS

870331 FR

* FR- FAILURE TO RUN FS - IYNCIPIENT FAILURE TO START
Table B.2.b. (continued)

MARK NO.

1-MDP-B

2-MDP-B

COMPONENT M. R. #

PUMP 49509

PROBLEM DESC

P-REPLACE MOTOR HEATERS

-P- REPLACE LO COOLER

MODE/MECHANISM(if applicable)

HISTORY SUMMARY

HEATERS BAD/AGE, REPLACED HTRS

MEGGERED 14 MEGOHMS AMPS .8 1.1 WORKED SAT.

CHANGED OVERLOADS INSTALLED 1018L.

LEAKING OIL/

INSTALL NEW COOLER. AS FOUND- COOLER LEAKING.

WORK PERFORMED-INSTALLED NEW OIL COOLER. AS

LEFT-TEST SAT.

RTSVDT CLASSIFICATION*

870522 FS

PUMP 52414 870807 FR

* FR- FAILURE TO RUN FS - IYNCIPIENT FAILURE TO START

w

61
Table B.2.c. MAINTENANCE RECORDS BROADLY CLASSIFIED AS FAILURES FOR THE AUXILIARY FEEDWATER SYSTEM 3-INCH MOTOR OPERATED VALVES

MODE/MECHANISM(if applicable)

MARK NO. COMPONENT M. R. I PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSIFICATION*

2-MOV-D

1-MOV-F

1-MOV-B

2-MOV-A

1-MOV-E

1-MOV-E

2-MOV-E

2-MOV-F

2-MOV-D

2-MOV-D

2-MOV-B

2-MOV-B

1-MOV-F

1-MOV-E

1-MOV-A

1-MOV-F

2-MOV-C

1-MOV-F

1-MOV-F

1-MOV-F

1-MOV-F

2-MOV-BDF

1-MOV-E

1-MOV-D

1-MOV-C

2-MOV-F

2-MOV-C

1-MOV-D

2-MOV-F

2-MOV-F

1-MOV-D

1-MOV-D

1-MOV-D

1-MOV-F

2-MOV-B

MOV

MOV

MOV

MOV

MOV

MOV

MOV

VALVE

VALVE

MOV

MOV

MOV

MOV

MOV

MOV

MOV

VALVE

MOV

MOV

NOV

MOV

CONTROL

MOV

VALVE

MOV

VALVE

VALVE

MOV

MOV

VALVE

VALVE

VALVE

VALVE

MOV

MOV

804061950

806022200

806302330

810110135

1061910

1061825

1062046

4291230

4211429

5281601

8230940

11011730

906180842

106100420

103110840

110011750

111121519

208140700

208120135

210130602

210140101

212172011

303100215

304072030

304230521

304240145

304230659

305111830

307050610

401131605

406140300

406191135

406190408

13893

02140

WON'T STAY CLOSED

TORQUE SWITCH BAD

BREAKER WILL NOT RESET AND VALVE

DID NOT AUTO OPEN

MOTOR HOUSING SHATTERED

DISCONNECT AND RECONNECT POWER

REMOVE MOV FOR USE ON UNIT 1

DISASSEMBLE LIMITORQUE FOR INSPECTION

VALVE OPEN WHEN SHOULD BE SHUT

MOV IS SHUT BREAKER IS OPEN

TORQUE SWITCH PROBLEM

MOV WILL NOT OPERATE

LEAKS THRU

CHECK CONTROL CIRCUIT FOR POSS GROUND

VALVE STIFF

MOV INDICATE CLOSED LOCALLY

REPAIR GEAR BOX

CHANGE LIMITORQUE

VALVE WILL NOT OPERATE BREAKER THERM

VALVE WILL NOT FULLY CLOSE

MOV WILL NOT CLOSE

WHEN LO-LO S/G LEVEL WAS RECEIVED

AGASTAT CONTACT IS STICKING

VALVE OPENS BUT WILL NOT CLOSE

VALVE MOTOR IS LOOSE

VLV WHEN CLOSED CAME BACK OPEN

DRIVE MECHANISM BROKEN

VALVE CLOSES

MOV WONT STAY CLOSED

VALVE OPENS

LIMITS NOT WORKING

REPAIR/REPLACE GEAR ASSEMBLY

VALVE WON'T CLOSE OR OPEN

1-MOV-F BREAKER TRIPPED

EXCESSIVE STROKE TIME

ADJUSTED SWITCH

REPLACED TORQUE SWITCH

REPAIRED - TESTED SATISFACTORY

CHECKED OUT CONTROL CIRCUIT - OK

REPLACED WITH LIMTORQUE FROM MOV 251

MOV REPLACED ON UNIT I

COMPLETED

UNSTUCK

VALVE OPERATES AS DESIGNED

ADJUSTED SWITCH

REPAIRED BROKEN WIRE

REPAIRED LEADS, TEST SWITCH SATISFACTORY

NEEDED TO BE WIRED UP

COMPLETED AS PER EMP-C-MOV-63

COMPLETED

COMPLETED - VALVE DOES NOT WORK SAT

RENEWED BEVEL GEAR

INSTALLED NEW LIMITORQUE

DISCONNECTED/RECONNECTED SATISFACTORY

DISCONNECTED/RECONNECTED MOV, SAT

REMACHINED SEAT RING

REWIRED BREAKERS AS

ADJUSTED MICROSWITCH

ADJUSTED LIMITS

DISCONNECTED AND

VALVE CYCLED SAT

REPLACED DESTROYED MOV WITH NEW MOV

CYCLED VALVE

CYCLED SAT

AGASTAT STICKING

REPLACED LIMIT SWITCH, GEAR WORN

INSPECTED, FOUND LIMITOROUE SAT

REPLACED LIMITS, DISCONNECTED

BRIDGED AND MEGGERED SATISFACTORY, CYCLED SEVERAL

DISASSEMBLE VALVE AND INSPECT PARTS

780407

780605

780706

781015

800107

800219

800323

800509

800513

800602

800826

801104

810325

810611

810618

811001

811207

820814

820814

821014

821018

821218

830313

830411

830423

830424

830426

830520

830819

840412

840614

840620

840620

850213

850620

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

PG

w

* PG - PLUGGING FAILURE
Table B.2.c. (continued)

MARK NO.

2-MOV-D

2-MOV-F

1-MOV-D

2-MOV-A

1-MOV-D

1-MOV-D

2-MOV-D

1-MOV-D

1-MOV-E

2-MOV-C

COMPONENT

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

MOV

M. R. I

02382

02333

22962

20540

29885

PROBLEM DESC

INVESTIGATE STROKE TIME

INVESTIGATE STROKE TIME

1-MOV-D INVESTIGATE TRIP

2-MOV-A WONT XFER CONTR

INVESTIGATE/REPAIR MOV

29920 E-INVESTIGATE/REPAIR AS

REQUIRED

37688 2-MOV-D WILL NOT OPEN

45967 INVESTIGATE/REPAIR AS NEEDED

49801 INVESTIGATE MALFUNCTION

MODE/MECHANISM(if applicable)

HISTORY SUMMARY

DISASSEMBLED VALVE CLEAN AND INSPECTED INTERNALS

REASSEMBLED VALVE WITH NEW BONNET GASKET. STEM,

PLUG AND ROTATE REPACKED VALVE

DISASSEMBLED VALVE REPLACED STEM, DISC TORQUE KEY,

GASKET DISC WASHER-100 PERCENT BLUE CHECK

REASSEMBLED VALVE

WORKED WITH OPERATORS AND CYCLED VALVE;

SATISFACTORY,NO PROBLEMS FOUND (OPEN 2.5 AMPS,

CLOSED 2.5 AMPS).

REPLACED COIL ON LATCHING RELAY OLD COIL BURNT UP

RESET THERMO OVERLOADS, TURNED BREAKER ON AND

VALVE AUTOMATICALLY WENT OPEN DRAWING 2.7 AMPS.

DREW 2.7 ALL THE WAY CLOSED, THEN DREW 11.3 AMPS.

WE THINK THE TORQUE SWITCH IS BROKEN.

AS FOUND - DISASSEMBLED LIMITORQUE, FOUND NO

INTERNAL DAMAGE OF COMPONENTS. GREASE WAS VERY

HARD, CLEANED ALL PARTS AND HOUSING,CHANGED OUT

GREASE WITH EP-O, AND REASSEMBLED.

FAILURE/VALVE WOULD NOT OPER.

AUX. CONTACTS STUCK. CHECKED AND FOUND AUX.

CONTACTS WERE STUCK OPERATED AND CHECKED SAT.

ASSISTED OPERATORS IN OPENING VALVE FULLY FROM

MCC. VALVE WENT FULL OPEN, FULL CLOSE WITH PROPER

INDICATION. WORK PERFORMED ON WO 047506, 1/8/87.

VALVE WOULEN'T OPEN/AUXILIARY OPEN

INTERLOCK STUCK ON OPENING CIRCUIT. REPLACED

CONTACTOR 2/18/87, CHECKED SATISFACTORY.

TIMES. FLA 2.4 ACTUAL, Ti 2.4, T2 2.4, AND T3 2.4

OKAY.

SPRING PACK DISASSEMBLED 12/30/86. S/N 347490.

INSTALLED SPRING PACK ONLY. LEFT WITH MOVAT.

WORK WAS PERFORMED BY MOVAT.

RTSVDT

850620

850620

850814

851029

860128

CLASSIFICATION*

PG

PG

PG

PG

PG

860131 PG

860715

861123

870219

PG

PG

PG

MOV 46218 REPAIR VALVE 870225 PG

* PG - PLUGGING FAILURE
Table B.2.d. MAINTENANCE RECORDS BROADLY CLASSIFIED AS FAILURES FOR THE AUXILIARY FEEDWATER SYSTEM 6-INCH MOTOR OPERATED VALVES

MODE/MECHANISM(if applicable)

MARK NO. COMPONENT M. R. # PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSIFICATION*

2-MOV-J

2-MOV-J

2-MOV-I

2-MOV-I

2-MOV-J

2-MOV-J

1-MOV-G

1-MOV-G

2-MOV-I

2-MOV-I

2-MOV-J

2-MOV-J

1-MOV-G

1-MOV-H

1-MOV-H

VALVE

NOV

NOV

NOV

NOV

VALVE

NOV

NOV

VALVE

VALVE

VALVE

VALVE

NOV

MOV

810030726

812040631

7231425

8050929

8122234

101131200

6120630

112120420

304191635

304231500

304191637

304231427

23350

30387

WILL NOT OPERATE

THERMALS OUT WON'T OPEN

VALVE IS BINDING UP

REPLACE LIMITORQUE

VALVE WILL NOT COME FULL OPEN

VALVE BINDS UNABLE TO CLOSE

VALVE WILL NOT OPEN

VALVE WILL NOT CYCLE

VLV CYCLES HI AMPS ON MTR

MOV-I WILL NOT OPEN

VLV CYCLES HI AMPS ON MTR

MOV-J WILL NOT OPEN

INVESTIGATE/REPAIR

MOV-H WILL NOT STROKE

MEG BRIDGED AND TESTED SATISFACTORY 781006 FC

CLEANED, CHECKED MOTOR - TEST SAT 781204 FC

REPAIRED VALVE 800801 FC

REPAIRED LIMITORQUE OPERATOR 800807 FC

NO PROBLEMS FOUND 800814 FC

CLEANED STEM THREADS 810120 FC

COMPLETE 810423 FC

ADJUSTED LIMITS ON MOV-FW-160A, SAT 811212 FC

ADJUSTED PACKING 830423 FC

CLEANED TORQUE SWITCH 830423 FC

ADJUSTED PACKING 830423 FC

ADJUSTED TORQUE SWITCH 830423 FC

REMOVED MOUNTING BOLTS FROM TORQUE SWITCH AND 850823 FC

CYCLED VALVE SEVERAL TIMES, OPENED TI 2.4, T2 2.8, 860211 FC

AND T3 2.9;

CLOSED Ti 2.8, T2 2.6, T3 2.6, FOUND NO PROBLEM AT

THIS TIME.

MOTOR HOIST/BEARINGS BAD 860807 FC

DISCONNECTED MOTOR, REPLACED BEARINGS, RECONNECTED

AND CYCLED SATISFACTORY. RECONNECTED MOTOR TEST, RAN

SATISFACTORY.

MOV 39300 1-MOV-H REPLACE BEARINGS

* FC - CROSS-CONNECTING FAILURE
Table B.2.e MAINTENANCE RECORDS BROADLY CLASSIFIED AS FAILURES FOR THE AUXILIARY FEEDWATER SYSTEM 3-INCH CHECK VALVES

MODE/MECHANISM(if applicable)

MARK NO. COMPONENT M. R. # PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSIFICATION*

1-CV-J

1-CV-H

1-CV-I

1-CV-I

1-CV-H

1-CV-J

2-CV-H

2-CV-I

2-CV-J

2-CV-H

2-CV-I

2-CV-J

1-CV-H

2-CV-J

2-CV-I

2-CV-H

1-CV-H

1-CV-I

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

4102000

4150916

4150915

109210813

109210811

109210815

110290942

110290938

110290941

312071039

312071040

312071041

312160902

403131437

403131441

401031301

404080900

2385

INSPECT VALVE

INSPECT INTERNALS AND REPAIR

INSPECT INTERNALS AND REPAIR

OVERHAUL VALVE

OVERHAUL VALVE

OVERHAUL VALVE

REPLACE VALVE

REPLACE VALVE

REPLACE VALVE

CHECK VALVE LEAKS THROUGH

CHECK VALVE LEAKS THROUGH

CHECK VALVE LEAKS THROUGH

LEAKS THROUGH

OPEN & INSPECT VALVE

OPEN AND INSPECT VALVE

REPAIR TO ORIGINAL FURMANITED

CHECK VALVE LEAKS THROUGH

OVERHAUL VALVE

REPAIRED VALVE

REPAIRED VALVE

INSPECTED AND REPAIRED VALVE

COMPLETED AS ABOVE

COMPLETED AS ABOVE

COMPLETED AS ABOVE

REPLACED FW CHECK VALVE 2-CV-H

REPLACED CHECK VALVE

REPLACED CHECK VALVE 2-CV-J

LAPPED VALVE DISH TO SEAT

CUT OUT SEAL WELD

LAPPED SEATS

CLEANED VALVE & LAP SET

CUT OUT VALVE, SHIP TO CRANE FOR REPAIR

CUT OUT VALVE, SHIP TO CRANE FOR REPAIR

SHIPPED VALVE TO CRANE FOR REPAIRS

OVERHAULED CHECK VALVE

DISASSEMBLED VALVE AND INSPECTED INTERNALS. LAP

800415

800417

800424

810930

810930

810930

811205

811205

811215

831214

831221

831221

840107

840406

840406

840406

840509

841210

LK

LK

LK

LK

LK

LK

LK

LK

LK

LK

LK

LK

LK

LK

LK

LK

LK

LK

SEAT AND DISC GOT 100% BLUEING. REMOVED 2-PIN

RETAINIG PLUGS. INSTALLED PIN, RETAINING PLUGS

AND WELDED.

* LK - UNDETECTED LEAKAGE FAILURE
Table B.2.f. MAINTENANCE RECORDS BROADLY CLASSIFIED AS FAILURES FOR THE AUXILIARY FEEDWATER SYSTEM 4-INCH CHECK VALVES

MODE/MECHANISM(lf applicable)

MARK NO. COMPONENT M. R. I PROBLEM DESC HISTORY SUMMARY RTSVDT CLASSIFICATION*

1-CV-C

1-CV-B

2-CV-C

2-CV-C

2-CV-C

2-CV-C

2-CV-C

2-CV-C

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

304291402

304291400

305040509

311181137

311201310

401270925

403070933

01799

LEAKS BACK THROUGH

LEAKS BACK THROUGH

CHECK VALVE

CHECK VALVE LEAKS BY

2-CV-C IS LEAKING BY

RESEAT VALVE

LEAKS THROUGH RESEAT

OVERHAUL VLV.

REPAIR VALVE

REBUILT VALVE

LAPPED SEAT REPLACED NUTS

PERFORMED CLEANLINESS INSPECTION

INSPECTED VALVE INTERNALS

LAPPED SEAT AND DISC

VALVE CHECKED 2-CV-C

DISASSEMBLE VALVE LAPPED SEAT AND DISC, HAVE

100% BLUEING.

830504

830525

830926

831119

831120

840128

840313

841218

LK/00

LK/00

LK/00

LK/OO

LK/OO

LK/OO

LK/00

LK/0O

* LK - UNDETECTED LEAKAGE FAILURE 00 - BACKFLOW FAILURE
Table B.2.g. MAINTENANCE RECORDS BROADLY CLASSIFIED AS FAILURES FOR THE AUXILIARY FEEDWATER SYSTEM 6-INCH CHECK VALVES

MODE/MECHANISM(if applicable)

MARK NO. HISTORY SUMMARY

2-CV-A

2-CV-F

2-CV-G

1-CV-A

2-CV-D

2-CV-F

2-CV-A

2-CV-F

2-CV-D

2-CV-D

2-CV-E

2-CV-F

2-CV-F

2-CV-F

2-CV-F

2-CV-F

2-CV-E

2-CV-D

2-CV-E

I-CV-A

1-CV-A

1-CV-A

COMPONENT M. R. # PROBLEM DESC RTSVDT CLASSIFICATION*

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

301131150

304212311

304212312

304291401

301131002

301131004

311201520

312071055

403271000

404031130

403270840

404072152

404031540

404070928

404081000

404021320

01222

OVERHAUL LEAK THROUGH CHECK VALVE

LEAKS THRU

LEAKS THRU

LEAKS BACK THROUGH

OVERHAUL LEAKS THROUGH

OVERHAUL LEAKS THROUGH

CHECK VALVE LEAKING BACK THROUGH

CHECK VALVE LEAKS THROUGH

OPEN & INSPECT VALVE

LEAKS THROUGH

OPEN AND INSPECT VALVE

VALVE LEAKS THROUGH

LEAKS THROUGH

VALVE LEAKS THROUGH

REMOVE BONNET & INSPECT

VALVE LEAKS BY

OVERHAUL VLV.

VALVE 25924 -PS- OVERHAUL VALVE

VALVE 30558 -P,S- INSPECT/REPAIR VALVE

VALVE 49606 REPAIR LEAK

VALVE 49058 P-REPAIR CHECK VALVE

VALVE 53704 P-INVESTIGATE, REPAIR CHECK

VALVE

OVERHAULED VALVE

LAPPED SEAT + DISK

LAPPED DISK + SEAT

REWORKED VALVE

LAPPED SEATS

GROUND SEAT AND DISCONNECTED

DISASSEMBLED VALVE

INSPECTED VALVE INTERNALS

OPENED VALVE FOR INSPECTION, FOUND

REWORKED VALVE

HAD DISC MACHINED, LAPPED DISC

INSPECTED VALVE AND LAPPED

OVERHAULED INTERNALS

RELAPPED' & TESTED PRIOR TO ASSEMBLY

OPENED AND INSPECTED VALVE

MACHINED TEN FROM DISC 100%

DISASSEMBLE VALVE AND INSPECT INTERNALS LAP SEAT

AND DISC AS NECESSARY TO GET 100% BLUEING

DISSASEMBLED VALVE GROUND SEAT ON FLAPPER BLUED

SEATING SURFACES. REASSEMBLED VALVE TORQUED TO

368 FR LB. SEAL WELD PLUG INSIDE OF VALVE.

REWORK VALVE/UNK

TACK WELDS ON PIN PLUG TO BE GROUND OFF

THEN REWELDED AFTER VALVE WORK COMPLETE. OPEN

VALVE AND INSPECTED INTERNALS. FOUND 1/16-

LEAKING THROUGH/NORMAL WEAR

AS FOUND - CHECK VALVE SUPPOSEDLY LEAKING BY.

WATER RUNNING OUT OF DRAIN VALVE BETWEEN PUMP

AND CHECK VALVE. REMOVED CAP ON

LEAK BY SEAT/WORN DISC

DISASSEMBLED VALVE BLUED SEAT. SEAT LOOKED OK.

DISC WORN OUT AND PITTED. LAPPED DISC BLUED 100%.

REASSEMBLED VALVE.

LEAK/WEAR

AS FOUND - VALVE SEAT CORRODED AND SLIGHTLY PITTED,

WORK PERFORMED. REMOVED BONNET PIN AND DISK,

CLEANED VALVE PIN AND BONNET.

830117

830426

830426

830520

830815

830926

831129

831213

840406

840406

840406

840408

840408

840408

840408

840408

841114

LK/O0

LK

LK

LK/DO

LK

LK

LK/OO

LK

LK

LK

LK

LK

LK

LK

LK

LK

LK

861202 LK

870104 LK

870214 LK/OO

870214 LK/O0

870528 LK/DO

* LK - UNDETECTED LEAKAGE FAILURE 00 - BACKFLOW FAILURE
Table B.3

Maintenance Records Broadly Classified

as Failures for the Auxiliary Feedwater System,

Rewritten Format

B-69 B-69 ~~~NUREG/CR-5378
Table B.3.a. MAINTENANCE RECORDS BROADLY CLASSIFIED AS FAILURES FOR THE AUXILIARY FEEDWATER SYSTEM TURBINE DRIVEN FEED PUMPS, REWRITTEN FORMAT

MARK NO. COMPONENT M. R. I PROBLEM/REPAIR SUMMARY RTSVDT CLASS*

1-TOP PUMP 801010430 THE LUBRICATING OIL PRESSURE FAILED LOW RESULTING IN BEARING DAMAGE, REPLACED THRUST BEARING LINING. 780111 FR

1-TDP PUMP 803030420 THE PUMP DISCHARGE PRESSURE WAS HIGH, ADJUSTED THE GOVERNOR TO REDUCE THE PUMP SPEED AND THUS 780303 FR

DISCHARGE PRESSURE.

1-TDP PUMP 901030450 THE GOVERNOR VALVE WAS NOT CONTROLLING PUMP SPEED, GOVERNOR WAS REPAIRED IN SOME MANNER. 790204 FR

1-TOP TURB 810040500 VARIOUS NON-SPECIFIED REPAIRS WERE MADE TO THE PUMP, THE PUMP WAS RETURNED TO SERVICE. 790420 FR

1-TDP PUMP 912172125 THE OUTBOARD PUMP BEARING WAS THROWING ENOUGH OIL THAT IT WAS NECESSARY TO RENEW THE THRUST BEARING. 791223 FR

1-TDP PUMP 1240708 AN OIL SEAL PACKING LEAK WAS LARGE ENOUGH THAT IT WAS NECESSARY TO RENEW THE THRUST BEARING SHOE. 800210 FR

1-TDP INSTR 4131129 A BROKEN CASE SWITCH ASSOCIATED WITH THE DISCHARGE PRESSURE TRIP WAS FOUND AND REPLACED. 800429 FR

2-TOP PUMP 11170730 DEFICIENCIES IN THE OVERSPEED TRIP VALVE CAUSED A PUMP:TRIP, THE LINKAGE WAS STRAIGHTENED. 801118 FR

2-TOP PUMP 205081945 THE GOVERNOR WAS CONTROLLING PUMP SPEED HIGH AT 4060 RPM. IT WAS RESET TO CONTROL AT AN RPM OF 3880. 820513 FR

1-TOP PUMP 208132145 AN OIL LEAK WAS LARGE ENOUGH THAT IT WAS NECESSARY TO REPLACE SOME BEARINGS. 820824 FR

2-TDP GOVERNOR 212061305 THE FEEDBACK ARM OF THE GOVERNOR WAS NOT WORKING CORRECTLY, A SETSCREW WAS INSTALLED. 821207 FR

2-TDP PUMP 302111050 THE OVERSPEED TRIP CAUSED CAUSED INAPPROPRIATE PUMP TRIPS.. THE OVERSPEED TRIP WAS CORRECTLY ADJUSTED. 830216 FR

2-TOP PUMP 303101430 THE SET SCREW WAS FOUND MISSING FROM THE FEEDBACK ARM. IT WAS REPLACED AND THE ARM ADJUSTED CORRECTLY. 830314 FR

2-TOP PUMP 303181232 FAILURE OF THE OVERSPEED TRIP SPRING TO STAY ENGAGED LED TO A PUMP TRIP, THE SPRING WAS REINSTALLED. 830321 FR

2-TOP PUMP 304250400 AN OIL SEAL LEAK WAS LARGE ENOUGH THAT IT WAS NECESSARY TO REPLACE SOME BEARINGS AND THRUST SHOES. 830429 FR

2-TDP BEARING 306200726 IT WAS NECESSARY, FOR SOME UNSPECIFIED REASON. TO REPLACE THE BEARINGS AND SHOES. 830927 FR

* FR - FAILURE TO RUN
Table B.3.a. (continued)

MARK NO. COMPONENT M. R. # PROBLEM/REPAIR SUMMARY RTSVDT CLASS*

2-TDP PUMP 309271700 HIGH BEARING VIBRATIONS REQUIRED THE ADJUSTMENT OF THE PUMP TO MOTOR COUPLING. 831013 FR

1-TDP PMP GOV 312311328 THE GOVERNOR WAS FOUND TO BE DAMAGED AND THE SEAT WAS REPLACED. 840111 FR

2-TDP SWITCH 402240947 THE DISCHARGE PRESSURE SWITCH WAS NOT AUTOMATICALLY TRIPPING THE PUMP. THE SWITCH WAS REPAIRED. 840330 FR

1-TOP PUMP 14061 THE MECHANICAL LINKAGE WAS FOUND TO BE BROKEN AND WAS REPAIRED. 850214 FR

2-TDP PUMP 23379 PUMP WAS SAID TO BE INOPERABLE, OUTBOARD THRUST SHOE WAS FOUND WIPED. IT WAS REPLACED. 850819 FR

1-TDP PUMP 27017 INSUFFICIENT OIL FLOW RESULTED IN BEARING DAMAGE, THE BEARINGS WERE REPLACED. 860509 FR

1-TDP PUMP 4170 THE BEARINGS WERE DAMAGED AS A RESULT OF A BAD SLINGER, THE SLINGER AND BEARINGS WERE REPLACED. 860820 FR

1-TOP PUMP 40487 THE GOVERNOR VALVE WOULD NOT OPEN, SPRING WAS REPLACED BUT THIS DID NOT HELP. 860907 FR

1-TDP PUMP 41325 GOVERNOR WAS REMOVED AND OVERHAULED BECAUSE POOR OPERATION. 860927 FR

(THIS EVENT SHOULD WAS COMBINED WITH RECORD 40487)

t 1-TOP PUMP 40450 ADDITIONAL GOVERNOR WORK COMBINED WITH RECORD 40487. 860930 FR

1-TOP PUMP 40488 ADDITIONAL GOVERNOR WORK COMBINED WITH RECORD 40487. 860930 FR

1-TDP PUMP 40491 ADDITIONAL GOVERNOR WORK COMBINED WITH RECORD 40487. 860930 FR

* FR - FAILURE TO RUN FS - FAILURE TO START
Table B.3.b. MAINTENANCE RECORDS BROADLY CLASSIFIED AS FAILURES FOR THE AUXILIARY FEEDWATER SYSTEM MOTOR DRIVEN FEED PUMPS, REWRITTEN FORMAT

MARK NO.

2-MOP-B

2-MOP-A

2-MDP-A

2-MDP-A

2-MDP-B

1-MOP-A

2-MDP-B

1-MDP-A

1-MDP-A

1-MDP-B

1-MOP-A w

t 1-MDP-A

1-MDP-B

2-MDP-B

1-MDP-B

1-MDP-A

COMPONENT

PUMP

PUMP

PUMP

PUMP MTR

HX

HX

PUMP

PUMP

HX

HX

PUMP

INSTR

INSTR

PUMP

PUMP

MOTOR

M. R. #

902050137

902050130

902131327

902111545

901081400

912211400

7222155

12270930

101130847

101130846

101291401

105220735

105220737

4180731

111110340

203200519

PROBLEM/REPAIR SUMMARY

THE PUMP DID NOT START QUICKLY ENOUGH, THE TIME DELAY CIRCUIT WAS ADJUSTED.

THE PUMP DID NOT START QUICKLY ENOUGH, THE TIME DELAY CIRCUIT WAS ADJUSTED.

THE OIL COOLER END BELL WAS FOUND TO BE CRACKED, IT WAS REPAIRED OR REPLACED.

THE MOTOR HEATER DID NOT WORK, A NEW HEATER WAS INSTALLED.

THE MOTOR HEATER DID NOT WORK, A NEW HEATER WAS INSTALLED.

TUBE LEAKS WERE FOUND IN THE HEAT EXCHANGER, THE LEAKING TUBES WERE PLUGGED OR REPLACED.

THE PUMP WOULD NOT START AUTOMATICALLY, IT WAS SOMEHOW REPAIRED.

THE PUMP CASING WAS SPLIT BY FREEZING, THE CASING WAS REPAIRED.

THE LUBE OIL COOLER WAS FOUND TO BE LEAKING, THE HEAD GASKET WAS REPLACED.

THE HEAD ON THE. LUBE OIL COOLER WAS FOUND TO BE BROKEN, THE HEAD WAS REPAIRED BY BRAZING.

THE LUBE OIL COOLER WAS FOUND TO BE BROKEN, THE COOLER WAS REPAIRED.

THE PUMP STARTED TOO SLOWLY, THE AGASTATS WERE ADJUSTED.

THE PUMP STARTED TOO SLOWLY, THE AGASTATS WERE ADJUSTED.

SOME PART OF THE PUMP WAS FOUND TO HAVE NO LUBE OIL PRESSURE, THE "STUDS" WERE "PACKED" TO REPAIR

THE PUMP, BEARINGS DAMAGE OR REPLACEMENT IS NOT MENTIONED.

BEARING VIBRATION ON THE PUMP WAS EXCESSIVE, THE INBOARD BEARING WAS REPLACED.

THE MOTOR WAS SPRAYED WITH STEAM, PI CURVE DATA WAS COLLECTED AND APPARENTLY WAS SATISFACTORY.

RTSVOT

790207

790209

790324

790910

790910

791223

800725

810101

810114

810114

810201

810522

810522

810616

820309

820320

CLASS*

FS

FS

FR

FS

FS

FR

FS

FR

FR

FR

FR

FS

FS

FR

FR

FS

* FR - FAILURE TO RUN FS - FAILURE TO START
Table B.3.b. (continued)

MARK NO. COMPONENT M. R. # PROBLEM/REPAIR SUMMARY RTSVDT CLASS*

1-MDP-A PUMP 203261300 THE PUMP FAILED BECAUSE THE BREAKER TRIPPED OPEN, BREAKER SHUT SATISFACTORILY AFTER REPAIR. 820330 FS

IT WAS ASSUMED THAT THE BREAKER TRIPPED ON PUMP START.

1-MOP-A PUMP 210050528 A FEED WATER LEAK WAS FOUND UPSTREAM OF LUBE OIL COOLER. THE LEAKING 3/4" PIPE WAS REPAIRED. 821014 FR

1-MDP-A BREAKER 306072125 A PHASE A RELAY DROPPED OUT, IT IS ASSUMED THAT THE PUMP TRIPPED SINCE A MEGGER WAS REQUIRED DURING 830611 FS

REPAIR.

2-MDP-A MOTOR 309211500 THE MOTOR HEATERS REQUIRED REPLACEMENT. THEY WERE REPLACED. 831006 FS

2-MDP-A RELAY 310060105 A RELAY COIL FAILED IN THE START OR POWER CIRCUIT AND IT IS ASSUMED THAT THE PUMP FAILED TO START, 831012 FS

THE RELAY WAS REPLACED.

2-MDP-B PUMP 15531 THE MOTOR HEATER WAS BAD. IT WAS REPLACED. 850712 FS

1-MDP-A PUMP 39854 THE MOTOR GOT WET, IT WAS DIRED AND CHECKED. 860826 FS

1-MOP-B PUMP 39853 THE MOTOR GOT WET, IT WAS DIRED AND CHECKED. 860826 FS 5 2-MDP-A PUMP 51214 LUBE OIL COOLER HAD A WATER TO OIL LEAK, IT WAS CHECKED OUT. 870331 FR

1-MDP-B PUMP 49509 THE MOTOR HEATER WAS BAD, IT WAS REPLACED. 870522 FS

2-MDP-B PUMP 52414 LUBE OIL COOLER WAS LEAKING, IT WAS REPLACED. 870807 FR

* FR - FAILURE TO RUN FS - FAILURE TO START
Table B.3.c. MAINTENANCE RECORDS BROADLY CLASSIFIED AS FAILURES FOR THE AUXILIARY FEEDWATER SYSTEM 3-INCH MOTOR OPERATED VALVES, REWRITTEN FORMAT

MARK NO. COMPONENT M. R. # PROBLEM/REPAIR SUMMARY RTSVDT CLASS*

2-MOV-D MOV 804061950 THE VALVE WOULD NOT STAY CLOSED, A SWITCH WAS ADJUSTED. 780407 PG

1-MOV-F MOV 806022200 THE TORQUE SWITCH WAS FOUND TO BE BAD. IT WAS REPLACED. 780605 PG

1-MOV-B MOV 806302330 THE SUPPLY BREAKER TRIPPED OPEN AND COULD NOT BE RESET, THE BREAKER WAS REPAIRED. 780706 PG

2-MOV-A MOV 810110135 THE VALVE DID NOT OPEN AUTOMATICALLY. THE CONTROL CIRCUIT WAS REPAIRED. 781015 PG

1-MOV-E MOV 1061910 THE MOTOR HOUSING FOR THE VALVE SHATTERED AND HAD TO BE REPLACED, IT WAS REPLACED WITH 251E MOTOR. 800107 PG

1-MOV-E MOV 1061825 POWER WAS DISCONNECTED AND RECONNECTED TO FACILITATE MOTOR REPLACEMENT. COMBINE WITH 1061910. 800219 PG

2-MOV-E MOV 1062046 THE MOTOR (AND MAYBE THE VALVE?) WAS REMOVED FOR USE ON UNIT 1. COMBINE WITH 1061910. 800323 PG

2-MOV-F VALVE 4291230 THE MOTOR WAS DISASSEMBLED FOR INSPECTION AND FOUND TO BE STUCK, IT WAS REPAIRED. 800509 PG

2-MOV-D VALVE 4211429 THE VALVE CONTROL CIRCUIT DID NOT OPERATE CORRECTLY AS THE VALVE WAS OPEN WHEN IT SHOULD HAVE BEEN 800513 PG

SHUT, THE CONTROL CIRCUIT WAS REPAIRED.

W 2-MOV-D MOV 5281601 THE SUPPLY BREAKER TRIPPED OPEN APPARENTLY ON OVERLOAD, A (TORQUE?) SWITCH WAS ADJUSTED TO FIX THE MOV. 800602 PG

2-MOV-B MOV 8230940 A BROKEN WIRE WAS FOUND IN THE TORQUE SWITCH CIRCUIT, THE WIRE WAS REPAIRED. 800826 PG

2-MOV-B MOV 11011730 THE MOV WOULD NOT OPERATE AND BAD LEADS WERE FOUND, THE LEADS WERE REPAIRED. 801104 PG

1-MOV-F MOV 906180842 THE VALVE WAS LEAKING THROUGH DUE TO IMPROPER WIRING, THE CIRCUIT WAS REWIRED. 810325 PG

1-MOV-E MOV 106100420 THE CONTROL CIRCUIT WAS CHECKED FOR A SUSPECTED GROUND, THE RESULTS ARE NOT INCLUDED IN THE SUMMARY. 810611 PG

1-MOV-A MOV 103110840 THE VALVE WAS FOUND TO BE STIFF IN ITS OPERATION, IT WAS REPAIRED SOMEHOW. 810618 PG

1-MOV-F MOV 110011750 THE MOV INDICATED CLOSED LOCALLY, THE VALVE WAS FOUND NOT TO OPERATE SATISFACTORILY. 811001 PG

2-MOV-C VALVE 111121519 THE BEVEL GEAR IN THE OPERATOR WAS WORN AND HAD TO BE REPLACED. 811207 PG

* PG - PLUGGING FAILURE
Table B.3.c. (continued)

MARK NO. COMPONENT M. R. # PROBLEM/REPAIR SUMMARY RTSVDT CLASS*

I-MOV-F MOV 208140700 THE OPERATOR WAS REPLACED. 820814 PG

1-MOV-F MOV 208120135 THE VALVE WOULD NOT OPERATE AND CAUSED THE BREAKER TO TRIP ON THERMAL OVERLOAD. 820814 PG

COMBINE WITH RECORD 208140700.

1-MOV-F MOV 210130602 THE VALVE WOULD NOT FULLY CLOSE. COMBINE WITH RECORD 210140101. 821014 PG

1-MOV-F MOV 210140101 THE VALVE WOULD NOT CLOSE, THE SEAT RING WAS MACHINED TO ALLOW CLOSURE. 821018 PG

2-MOV-BDF CONTROL 212172011 ALL THREE VALVES OPERATED INCORRECTLY UPON RECEIVING A LO-LO S/G LEVEL SINGLE, THE SUPPLY BREAKERS 821218 PG

WERE REWIRED TO REPAIR THE VALVES.

1-MOV-E MOV 303100215 THE AGASTAT CONTACT WAS STICKING, IT WAS ADJUSTED. 830313 PG

1-MOV-D VALVE 304072030 VALVE OPENED BUT WOULD NOT CLOSE INDICATING A CONTROL CIRCUIT PROBLEM, THE LIMITS WERE ADJUSTED. 830411 PG

1-MOV-C MOV 304230521 THE VALVE MOTOR WAS FOUND TO BE LOOSE. IT WAS REPAIRED. 830423 PG

2-MOV-F VALVE 304240145 THE VALVE CAME BACK OPENED WHEN IT WAS CLOSED INDICATING A CONTROL CIRCUIT PROBLEM, IT IS NOT APPARENT 830424 PG 5'd HOW THE VALVE WAS REPAIRED OR EVEN IF IT WAS REPAIRED.

2-MOV-C VALVE 304230659 THE DRIVE MECHANISM WAS FOUND TO BE BROKEN, THE OPERATOR WAS REPLACED. 830426 PG

1-MOV-D MOV 305111830 THE VALVE CLOSED APPARENTLY WHEN IT SHOULD NOT HAVE, IT IS NOT APPARENT FROM THE SUMMARY HOW THE 830520 PG

VALVE WAS REPAIRED.

2-MOV-F MOV 307050610 THE VALVE WOULD NOT STAY CLOSED INDICATING A CONTROL CIRCUIT PROBLEM, IT IS NOT APPARENT FROM THE 830819 PG

SUMMARY HOW THE VALVE WAS REPAIRED.

* PG - PLUGGING FAILURE
Table B.3.c. (continued)

MARK NO. COMPONENT M. R. # PROBLEM/REPAIR SUMMARY RTSVDT CLASS*

2-MOV-F VALVE 401131605 THE VALVE OPENED WHEN IT SHOULD NOT HAVE INDICATING A CONTROL CIRCUIT PROBLEM, THE AGASTAT WAS FOUND 840412 PG

TO BE STICKING AND WAS REPAIRED.

1-MOV-D VALVE 406140300 LIMIT SWITCH GEAR WAS WORN AND WAS REPLACED, COMBINED WITH RECORD 406190408. 840614 PG

1-MOV-D VALVE 406191135 THE GEAR ASSEMBLY WAS REPLACED, COMBINED WITH RECORDS 406190408. 840620 PG

1-MOV-D VALVE 406190408 THE VALVE WOULD NOT CLOSE OR OPEN. THE LIMITS WERE REPLACED. 840620 PG

1-MOV-F MOV 13893 THE SUPPLY BREAKER TRIPPED, IT WAS CHECKED. 850213 PG

2-MOV-B MOV 02140 THE VALVE WAS REPAIRED DUE TO EXCESSIVE STROKE TIME. 850620 PG

2-MOV-D MOV 02382 THE VALVE WAS REPAIRED DUE TO EXCESSIVE STROKE TIME. 850620 PG

2-MOV-F MOV 02333 THE VALVE WAS REPAIRED DUE TO EXCESSIVE STROKE TIME. 850620 PG

1-MOV-D MOV 22962 THE SUPPLY BREAKER TRIPPED, IT WAS CHECKED. 850814 PG

2-MOV-A MOV 20540 COIL IN LATCHING RELAY FAILED, IT WAS REPLACED. 851029 PG W

~4 1-MOV-0 MOV 29885 BREAKER TRIPPED ON THEMAL OVERLOAD, OVERLOADS RESET, NO FURTHER FAILURES. 860128 PG

1-MOV-D MOV 29920 VALVE MALFUNCTION, RECORD UNCLEAR. 860131 PG

2-MOV-D MOV 37688 VALVE DID NOT OPERATE BECAUSE AUXILIARY CONTACTS WERE STUCK, CONTACTS REPAIRED. 860715 PG

1-MOV-D MOV 45967 VALVE MALFUNCTION, RECORD UNCLEAR. 861123 PG

1-MOV-E MOV 29920 VALVE DID NOT OPEN DUE TO A STUCK INTERLOCK IN OPENING CIRCUIT. CONTACTOR REPLACED. 870219 PG

1-MOV-C MOV 46218 SPRING PACK HAD TO BE REPAIRED, APPARENTLY THE VALVE WOULD NOT WORK. 870225 PG

* PG - PLUGGING FAILURE
Table B.3.d. MAINTENANCE RECORDS BROADLY CLASSIFIED AS FAILURES FOR THE AUXILIARY FEEDWATER SYSTEM 6-INCH MOTOR OPERATED VALVES, REWRITTEN FORMAT

MARK NO. COMPONENT M. R. # PROBLEM/REPAIR SUMMARY RTSVDT CLASS*

2-MOV-J VALVE 810030726 THE VALVE WOULD NOT OPERATE, UNSPECIFIED REPAIRS WERE MADE AND THE VALVE WAS TESTED. 781006 FC

2-MOV-J MOV 812040631 THE SUPPLY BREAKER TRIPPED ON THERMAL OVERLOAD, THE VALVE WAS CLEANED AND THEN TESTED. 781204 FC

2-MOV-1 MOV 7231425 THE VALVE WAS BINDING UP, UNSPECIFIED REPAIRS WERE MADE. COMBINE WITH 8050929. 800801 FC

2-MOV-I MOV 8050929 THE LIMITORQUE OPERATOR WAS REPLACED OR REPAIRED. 800807 FC

2-MOV-J MOV 8122234 THE VALVE WOULD NOT COME FULLY OPEN. IT WAS CHECKED AND NO PROBLEMS WERE FOUND. 800814 FC

2-MOV-J VALVE 101131200 THE VALVE WAS BINDING AND WOULD NOT CLOSE, THE STEM THREADS WERE CLEANED. 810120 FC

1-MOV-G MOV 6120630 THE VALVE WOULD NOT OPEN, UNSPECIFIED REPAIRS WERE MADE. 810423 FC

1-MOV-G MOV 112120420 THE VALVE WOULD NOT CYCLE, THE LIMITS WERE ADJUSTED. 811212 FC

2-MOV-1 VALVE 304191635 THE MOTOR WAS DRAWING HIGH CURRENT DURING VALVE CYCLING, THE PACKING WAS ADJUSTED. 830423 FC

2-MOV-I VALVE 304231500 THE VALVE WOULD NOT OPEN, THE TORQUE SWITCH WAS CLEANED. COMBINE WITH 3014191635. 830423 FC

5 2-MOV-i VALVE 304191637 THE MOTOR WAS DRAWING HIGH CURRENT DURING VALVE CYCLING, THE PACKING WAS ADJUSTED. 830423 FC

2-MOV-J VALVE 304231427 THE VALVE WOULD NOT OPEN. THE TORQUE SWITCH WAS ADJUSTED. COMBINE WITH 3014191637. 830423 FC

1-MOV-G MOV 23350 REPIARED THE TORQUE SWITCH. 850823 FC

1-MOV-H MOV 30387 VALVE WOULD NOT STROKE, IT WAS CHECKED. 860211 FC

1-MOV-H MOV 39300 IT WAS NECESSARY TO REPLACE THE VALVE BEARINGS. 860807 FC

* FC - CROSS-CONNECTING FAILURE
Table B.3.e. MAINTENANCE RECORDS BROADLY CLASSIFIED AS FAILURES FOR THE AUXILIARY FEEDWATER SYSTEM 3-INCH CHECK VALVES, REWRITTEN FORMAT

MARK NO. COMPONENT M. R. # PROBLEM/REPAIR SUMMARY RTSVDT CLASS*

1-CV-J VALVE 4102000 THE WAS INSPECTED AND UNSPECIFIED REPAIRS WERE PERFORMED. 800415 LK

1-CV-H VALVE 4150916 THE WAS INSPECTED AND UNSPECIFIED REPAIRS WERE PERFORMED. 800417 LK

1-CV-I VALVE 4150915 THE WAS INSPECTED AND UNSPECIFIED-REPAIRS WERE PERFORMED. 800424 LK

1-CV-I VALVE 109210813 THE VALVE WAS OVERHAULED FOR SOME UNSPECIFIED REASON. 810930 LK

1-CV-H VALVE 109210811 THE VALVE WAS OVERHAULED FOR SOME UNSPECIFIED REASON. 810930 LK

1-CV-J VALVE 109210815 THE VALVE WAS OVERHAULED FOR SOME UNSPECIFIED REASON. 810930 LK

2-CV-H VALVE 110290942 THE VALVE WAS REPLACED FOR SOME UNSPECIFIED REASON. 811205 LK

2-CV-I VALVE 110290938 THE VALVE WAS REPLACED FOR SOME UNSPECIFIED REASON. IT HAD BEEN FURMANITED PREVIOUSLY. 811205 LK

2-CV-J VALVE 110290941 THE VALVE WAS REPLACED FOR SOME UNSPECIFIED REASON. 811215 LK

2-CV-H VALVE 312071039 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 831214 LK

2-CV-I VALVE 312071040 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 831221 LK

00

2-CV-J VALVE 312071041 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 831221 LK

1-CV-H VALVE 312160902 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 840107 LK

2-CV-J VALVE 403131437 THE VALVE WAS INSPECTED FOR SOME REASON. IT WAS CUT OUT AND SENT TO CRANE FOR REPAIR. IT HAD BEEN 840406 LK

FURMANITED SINCE IT WAS LAST REPLACED.

2-CV-I VALVE 403131441 THE VALVE WAS INSPECTED FOR SOME REASON, IT WAS CUT OUT AND SENT TO CRANE FOR REPAIR. 840406 LK

* LK - UNDETECTED LEAKAGE FAILURE
Table B.3.e. (continued)

MARK NO.

2-CV-H

1-CV-H

'-CV-'

COMPONENT

VALVE

VALVE

VALVE

M. R. # PROBLEM/REPAIR SUMMARY

401031301 THE CHECK VALVE WAS SENT TO CRANE TO REPAIR IT TO ORIGINAL CONDITION FOLLOWING USE OF FURMANITE.

404080900 THE CHECK VALVE SEAT WAS LEAKINGTHE SEAT WAS REPAIRED.

2385 THE CHECK VALVE WAS OVERHAULED. IT WAS ASSUMED TO BE BECAUSE OF A LEAK.

RTSVDT CLASS*

840406 LK

840509 LK

841210 LK

* LK - UNDETECTED LEAKAGE FAILURE

-4
Table B.3.f. MAINTENANCE RECORDS BROADLY CLASSIFIED AS FAILURES FOR THE AUXILIARY FEEDWATER SYSTEM 4-INCH CHECK VALVES, REWRITTEN FORMAT

MARK NO.

1-CV-C

1-CV-B

2-CV-C

2-CV-C

2-CV-C

2-CV-C

2-CV-C

2-CV-C

COMPONENT

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

VALVE

M. R. #

304291402

304291400

305040509

311181137

311201310

401270925

403070933

1799

PROBLEM/REPAIR SUMMARY

THE CHECK VALVE SEAT WAS

THE CHECK VALVE SEAT WAS

THE CHECK VALVE SEAT WAS

THE CHECK VALVE SEAT WAS

THE CHECK VALVE SEAT WAS

THE CHECK VALVE SEAT WAS

THE CHECK VALVE SEAT WAS

THE CHECK VALVE SEAT WAS

LEAKING, THE SEAT WAS REPAIRED.

LEAKING, THE SEAT WAS REPAIRED.

LEAKING, THE SEAT WAS REPAIRED.

LEAKING, THE SEAT WAS INSPECTED.

LEAKING, THE SEAT WAS INSPECTED. COMBINE WITH 311181137.

LEAKING. THE SEAT WAS REPAIRED.

LEAKING, THE VALVE WAS CHECKED.

LAPPED. IT WAS ASSUMED TO HAVE BEEN LEAKING.

RTSVDT

830504

830525

830926

831119

831120

840128

840313

841218

CLASS*

LK/OO

LK/00

LK/OO

LK/O0

LK/OO

LK/OO

LK/OO

LK/OO

* LK - INCIPIENT UNDETECTED LEAKAGE FAILURE 00 - BACKFLOW FAILURE

00

0
Table B.3.g. MAINTENANCE RECORDS BROADLY CLASSIFIED AS FAILURES FOR THE AUXILIARY FEEDWATER SYSTEM 6-INCH CHECK VALVES, REWRITTEN FORMAT

MARK NO. COMPONENT M. R. # PROBLEM/REPAIR SUMMARY RTSVDT CLASS*

2-CV-A VALVE 301131150 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 830117 LK/OO

2-CV-F VALVE 304212311 THE CHECK VALVE SEAT WAS LEAKING. THE SEAT WAS REPAIRED. 830426 LK

2-CV-G VALVE 304212312 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 830426 LK

1-CV-A VALVE 304291401 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 830520 LK/OO

2-CV-D VALVE 301131002 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 830815 LK

F-CV-F VALVE 301131004 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 830926 LK

2-CV-A VALVE 311201520 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS DISASSEMBLED, REPAIR WAS NOT SPECIFIED. 831129 LK/OO

2-CV-F VALVE 312071055 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS INSPECTED, REPAIR WAS NOT SPECIFIED. 831213 LK

2-CV-D VALVE 403271000 THE VALVE WAS INSPECTED, THE RESULTS WERE NOT SPECIFIED. 840406 LK

2-CV-D VALVE 404031130 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. COMBINE WITH 403271000. 840406 LK

W 2-CV-E VALVE 403270840 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 840406 LK

Jo 2-CV-F VALVE 404072152 THE CHECK VALVE SEAT WAS-LEAKING, THE SEAT WAS REPAIRED. 840408 LK

2-CV-F 

2-CV-F 

VALVE 404031540 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. COMBINE WITH 404072152. 840408 LK VALVE 404031540 THE CHECK VALVE SEAT WAS LEAK IING. THE SEAT WAS REPAIRED. COMBINE WITH 404072152. 840408 LK

2-CV-F VALVE 404070928 THE CHECK VALVE SEAT'WAS LEAKING. THE SEAT WAS REPAIRED. COMBINE WITH 404072152. 840408 LK

2-CV-F VALVE 404081000 THE VALVE WAS INSPECTED, THE RESULTS WERE NOT SPECIFIED. COMBINE WITH 404072152. 840408 LK

2-CV-F VALVE 404021320 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. COMBINE WITH 404072152. 840408 LK

* LK - UNDETECTED LEAKAGE FAILURE 00 - BACKFLOW FAILURE
Table B.3.g. (continued)

MARK NO. COMPONENT M. R. f PROBLEM/REPAIR SUMMARY RTSVDT CLASS*

2-CV-E VALVE 1222 THE CHECK VALVE SEAT WAS LEAKING. THE SEAT WAS REPAIRED. 841114 LK

2-CV-D VALVE 25924 THE CHECK VALVE SEAT WAS LEAKING. THE SEAT WAS REPAIRED. 861202 LK

2-CV-E VALVE 30558 IT WAS NECESSARY TO INSPECT AND REPAIR THE VALVE, IT IS ASSUMED THAT IT WAS LEAKING. 870104 LK

1-CV-A VALVE 49606 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 870214 LK/O0

1-CV-A VALVE 49048 THE CHECK VALVE SEAT WAS LEAKING. THE SEAT WAS REPAIRED. COMBINED WITH RECORD 49606. 870214 LK/OO

1-CV-A VALVE 53704 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 870528 1K/OO

* LK - UNDETECTED LEAKAGE FAILURE 00 - BACKFLOW FAILURE

w
Table B.4

Maintenance Records Narrowly Classified

as Failures for the Auxiliary Feedwater System,

Rewritten Format

B-83 NUREG/CR-5378
Table B.4.a. MAINTENANCE RECORDS NARROWLY CLASSIFIED AS FAILURES FOR THE AUXILIARY FEEDWATER SYSTEM TURBINE DRIVEN FEED PUMPS, REWRITTEN FORMAT

MARK NO. COMPONENT M. R. # PROBLEM/REPAIR SUMMARY RTSVDT CLASS*

1-TDP PUMP 801010430 THE LUBRICATING OIL PRESSURE FAILED LOW RESULTING IN BEARING DAMAGE, REPLACED THRUST BEARING LINING. 780111 FR

2-TDP PUMP 11170730 DEFICIENCIES IN THE OVERSPEED TRIP VALVE CAUSED A PUMP TRIP, THE LINKAGE WAS STRAIGHTENED. 801118 FR

2-TDP PUMP 302111050 THE OVERSPEED TRIP CAUSED CAUSED INAPPROPRIATE PUMP TRIPS, THE OVERSPEED TRIP WAS CORRECTLY ADJUSTED. 830216 FR

2-TDP PUMP 303181232 FAILURE OF THE OVERSPEED TRIP SPRING TO STAY ENGAGED LED TO A PUMP TRIP, THE SPRING WAS REINSTALLED. 830321 FR

1-TOP PUMP 40487 THE GOVERNOR VALVE WOULD NOT OPEN, SPRING WAS REPLACED BUT THIS DID NOT HELP. 860907 FR

1-TDP PUMP 41325 GOVERNOR WAS REMOVED AND OVERHAULED BECAUSE POOR OPERATION. 860927 FR

(THIS EVENT SHOULD WAS COMBINED WITH RECORD 40487)

1-TDP PUMP 40450 ADDITIONAL GOVERNOR WORK COMBINED WITH RECORD 40487. 860930 FR

1-TDP PUMP 40488 ADDITIONAL GOVERNOR WORK COMBINED WITH RECORD 40487. 860930 FR

1-TDP PUMP 40491 ADDITIONAL GOVERNOR WORK COMBINED WITH RECORD 40487. 860930 FR

* FR - FAILURE TO RUN FS - FAILURE TO START
Table 8.4.b.

MARK NO.

2-MOP-B

1-MOP-A

1-MDP-A

2-MDP-A

MAINTENANCE

COMPONENT

PUMP

PUMP

BREAKER

RELAY

RECORDS NARROWLY CLASSIFIED AS FAILURES FOR THE AUXILIARY FEEDWATER SYSTEM MOTOR DRIVEN PUMPS, REWRITTEN FORMAT

M. R. # PROBLEM/REPAIR SUMMARY

7222155 THE PUMP WOULD NOT START AUTOMATICALLY, IT WAS SOMEHOW REPAIRED.

203261300 THE PUMP FAILED BECAUSE THE BREAKER TRIPPED OPEN, BREAKER SHUT SATISFACTORILY AFTER REPAIR.

IT WAS ASSUMED THAT THE BREAKER TRIPPED ON PUMP START.

306072125 A PHASE A RELAY DROPPED OUT, IT IS ASSUMED THAT THE PUMP TRIPPED SINCE A MEGGER WAS REQUIRED DURING

REPAIR.

310060105 A RELAY COIL FAILED IN THE START OR POWER CIRCUIT AND IT IS ASSUMED THAT THE PUMP FAILED TO START,

THE RELAY WAS REPLACED.

RTSVDT CLASS*

800725 FS

820330 FS

830611 FS

831012 FS

* FR - FAILURE TO RUN FS - FAILURE TO START

ox
Table B.4.c. MAINTENANCE RECORDS NARROWLY CLASSIFIED AS FAILURES FOR THE AUXILIARY FEEDWATER SYSTEM 3-INCH MOTOR OPERATED VALVES, REWRITTEN FORMAT

MARK NO. COMPONENT M. R. # PROBLEM/REPAIR SUMMARY RTSVDT CLASS*

1-MOV-B MOV 806302330 THE SUPPLY BREAKER TRIPPED OPEN AND COULD NOT BE RESET, THE BREAKER WAS REPAIRED. 780706 PG

2-MOV-A MOV 810110135 THE VALVE DID NOT OPEN AUTOMATICALLY, THE CONTROL CIRCUIT WAS REPAIRED. 781015 PG

1-MOV-E MOV 1061910 THE MOTOR HOUSING FOR THE VALVE SHATTERED AND HAD TO BE REPLACED, IT WAS REPLACED WITH 251E MOTOR. 800107 PG

1-MOV-E MOV 1061825 POWER WAS DISCONNECTED AND RECONNECTED TO FACILITATE MOTOR REPLACEMENT. COMBINE WITH 1061910. 800219 PG

2-MOV-E MOV 1062046 THE MOTOR (AND MAYBE THE VALVE?) WAS REMOVED FOR USE ON UNIT 1. COMBINE WITH 106190. 800323 PG

2-MOV-F VALVE 4291230 THE MOTOR WAS DISASSEMBLED FOR INSPECTION AND FOUND TO BE STUCK, IT WAS REPAIRED. 800509 PG

2-MOV-D MOV 5281601 THE SUPPLY BREAKER TRIPPED OPEN APPARENTLY ON OVERLOAD, A (TORQUE?) SWITCH WAS ADJUSTED TO FIX THE MOV. 800602 PG

2-MOV-B MOV 11011730 THE MOV WOULD NOT OPERATE AND BAD LEADS WERE FOUND, THE LEADS WERE REPAIRED. 801104 PG

1-MOV-F MOV 110011750 THE MOV INDICATED CLOSED LOCALLY, THE VALVE WAS FOUND NOT TO OPERATE SATISFACTORILY. 811001 PG

1-MOV-F MOV 208140700 THE OPERATOR WAS REPLACED. 820814 PG

1-MOV-F MOV 208120135 THE VALVE WOULD NOT OPERATE AND CAUSED THE BREAKER TO TRIP ON THERMAL OVERLOAD. 820814 PG COMBINE WITH RECORD 208140700.

2-MOV-C VALVE 304230659 THE DRIVE MECHANISM WAS FOUND TO BE BROKEN, THE OPERATOR WAS REPLACED. 830426 PG

1-MOV-D MOV 305111830 THE VALVE CLOSED APPARENTLY WHEN IT SHOULD NOT HAVE, IT IS NOT APPARENT FROM THE SUMMARY HOW THE 830520 PG VALVE WAS REPAIRED.

* PG - PLUGGING FAILURE
Table B.4.c. (continued)

MARK NO. COMPONENT M. R. # PROBLEM/REPAIR SUMMARY RTSVDT CLASS*

1-MOV-D VALVE 406140300 LIMIT SWITCH GEAR WAS WORN AND WAS REPLACED, COMBINED WITH RECORD 406190408. 840614 PG

1-MOV-D VALVE 406191135 THE GEAR ASSEMBLY WAS REPLACED, COMBINED WITH RECORDS 406190408. 840620 PG

1-MOV-D VALVE 406190408 THE VALVE WOULD NOT CLOSE OR OPEN, THE LIMITS WERE REPLACED. 840620 PG

1-MOV-D MOV 13893 THE SUPPLY BREAKER TRIPPED, IT WAS CHECKED. 850213 PG

1-MOV-D MOV 22962 THE SUPPLY BREAKER TRIPPED, IT WAS CHECKED. 850814 PG

2-MOV-A MOV 20540 COIL IN LATCHING RELAY FAILED, IT WAS REPLACED. 851029 PG

1-MOV-D MOV 29885 BREAKER TRIPPED ON THEMAL OVERLOAD, OVERLOADS RESET, NO FURTHER FAILURES. 860128 PG

2-MOV-D MOV 37688 VALVE DID NOT OPERATE BECAUSE AUXILIARY CONTACTS WERE STUCK, CONTACTS REPAIRED. 860715 PG

1-MOV-E MOV 29920 VALVE DID NOT OPEN DUE TO A STUCK INTERLOCK IN OPENING CIRCUIT. CONTACTOR REPLACED. 870219 PG

* PG - PLUGGING FAILURE

tz

00

00
Table B.4.d MAINTENANCE RECORDS NARROWLY CLASSIFIED AS FAILURES FOR THE AUXILIARY FEEDWATER SYSTEM 6-INCH MOTOR OPERATED VALVES, REWRITTEN FORMAT

MARK NO. COMPONENT M. R. I PROBLEM/REPAIR SUMMARY RTSVDT CLASS*

2-MOV-J VALVE 810030726 THE VALVE WOULD NOT OPERATE, UNSPECIFIED REPAIRS WERE MADE AND THE VALVE WAS TESTED. 781006 FC

2-MOV-J MOV 812040631 THE SUPPLY BREAKER TRIPPED ON THERMAL OVERLOAD. THE VALVE WAS CLEANED AND THEN TESTED. 781204 FC

2-MOV-1 MOV 7231425 THE VALVE WAS BINDING UP, UNSPECIFIED REPAIRS WERE MADE. COMBINE WITH 8050929. 800801 FC

2-MOV-1 MOV 8050929 THE LIMITORQUE OPERATOR WAS REPLACED OR REPAIRED. 800807 FC

2-MOV-J VALVE 101131200 THE VALVE WAS BINDING AND WOULD NOT CLOSE, THE STEM THREADS WERE CLEANED. 810120 FC

1-MOV-G NOV 112120420 THE VALVE WOULD NOT CYCLE, THE LIMITS WERE ADJUSTED. 811212 FC

1-MOV-H MOV 30387 VALVE WOULD NOT STROKE. IT WAS CHECKED. 860211 FC

* FC - CROSS-CONNECTING FAILURE
Table B.4.e. MAINTENANCE RECORDS NARROWLY CLASSIFIED AS FAILURES FOR THE AUXILIARY FEEDWATER SYSTEM 3-INCH CHECK VALVES, REWRITTEN FORMAT

MARK NO.

2-CV-H

2-CV-I

2-CV-J

1-CV-H

COMPONENT

VALVE

VALVE

VALVE

VALVE

M. R. I PROBLEM/REPAIR SUMMARY

312071039 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED.

312071040 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED.

312071041 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED.

312160902 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED.

RTSVDT CLASS*

831214 LK

831221 LK

831221 LK

840107 LK

* LK - UNDETECTED LEAKAGE FAILURE

w

0
Table B.4.f. MAINTENANCE RECORDS NARROWLY CLASSIFIED AS FAILURES FOR THE AUXILIARY FEEDWATER SYSTEM 4-INCH CHECK VALVES, REWRITTEN FORMAT

MARK NO. COMPONENT M. R. I PROBLEM/REPAIR SUMMARY RTSVDT CLASS*

1-CV-C VALVE 304291402 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 830504 LK

1-CV-B VALVE 304291400 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 830525 LK

2-CV-C VALVE 305040509 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 830926 LK

2-CV-C VALVE 311181137 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS INSPECTED. 831119 LK

2-CV-C VALVE 311201310 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS INSPECTED. COMBINE WITH 311181137. 831120 LK

2-CV-C VALVE 401270925 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 840128 LK

2-CV-C VALVE 403070933 THE CHECK VALVE SEAT WAS LEAKING, THE VALVE WAS CHECKED. 840313 LK

* LK - INCIPIENT UNDETECTED LEAKAGE FAILURE
Table B.4.g. MAINTENANCE RECORDS NARROWLY CLASSIFIED AS FAILURES FOR THE AUXILIARY FEEDWATER SYSTEM 6-INCH CHECK VALVES, REWRITTEN FORMAT

MARK NO. COMPONENT M. R. # PROBLEM/REPAIR SUMMARY RTSVDT CLASS*

2-CV-A VALVE 301131150 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 830117 LK

2-CV-F VALVE 304212311 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 830426 LK

2-CV-G VALVE 304212312 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 830426 LK

1-CV-A VALVE 304291401 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 830520 LK

2-CV-D VALVE 301131002 THE CHECK VALVE SEAT WAS LEAKING. THE SEAT WAS REPAIRED. 830815 LK

2-CV-F VALVE 301131004 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 830926 LK

2-CV-A VALVE 311201520 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS DISASSEMBLED, REPAIR WAS NOT SPECIFIED. 831129 LK

2-CV-F VALVE 312071055 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS INSPECTED, REPAIR WAS NOT SPECIFIED. 831213 LK

2-CV-D VALVE 404031130 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. COMBINE WITH 403271000. 840406 LK

2-CV-E VALVE 403270840 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 840406 LK

to 2-CV-F VALVE 404072152 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 840408 LK

2-CV-F VALVE 404031540 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. COMBINE WITH 404072152. 840408 LK

2-CV-F VALVE 404070928 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. COMBINE WITH 404072152. 840408 LK

2-CV-F VALVE 404021320 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. COMBINE WITH 404072152. 840408 LK

2-CV-E VALVE 1222 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 841114 LK

2-CV-D VALVE 25924 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 861202 LK

1-CV-A VALVE 49606 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 870214 LK

1-CV-A VALVE 49048 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. COMBINED WITH RECORD 49606. 870214 LK

1-CV-A VALVE 53704 THE CHECK VALVE SEAT WAS LEAKING, THE SEAT WAS REPAIRED. 870528 LK

* LK - UNDETECTED LEAKAGE FAILURE.
NRC FORM 335 U.S. NUCLEAR REGULATORY COMMISSION 1. REPORT NUMBER

12-89) 4IAa.Ignd by NRC. Add Vol., Spp.. R._ NRCM 1102. ed Addendum Numbes, If mny.) 3201,3202 BIBLIOGRAPHIC DATA SHEET

(See instructions on the reverse) NUREG CR6 5378

2. TITLE AND SUBTITLE-2567

Aging Data Analysis and Risk Assessment--Development 3. DATE REPORT PUBLISHED

and Demonstration Study MONTH i YEAR

August 1992

4. FIN OR GRANT NUMBER

A6389

5. AUTHORIS) 6. TYPE OF REPORT

A. J. Wolford*, C. L. Atwood, W. S. Roesener Technical

7. PERIOD COVERED Itnclusive Dares)

B. PE RFO RM ING ORGAN IZATION -NAM E AND ADD RESS (If NRC.prrwide Divisio~n, Office Or ®ion, U.S.Nucb e Regu/arory Co-.isio and mailingaddress if ontroctof, provide nate and mailing address I

Idaho National Engineering Laboratory *DNV Technica

EG&G Idaho, Inc. 355 East Campus View Blvd.

Idaho Falls, ID 83415 Suite 710

Columbus, OH 43235

9. SPONSOR ING ORGAN IZATI ON -NAME AND ADDR ESSl WNRC, type S~ax sJ bove-; icontrrctofprovide NRC Division, Office or fegio~n, U.1 Nuclear Regulatory Commission, and mailing address.)

Division of Engineering

Office of Nuclear Regulatory Research

U.S. Nuclear Regulatory Commission

Washington, DC 20555

10. SUPPLEMENTARY NOTES

11. ABSTRACT 200 words or kae

This work develops and demonstrates a probabilistic risk assessment (PRA) approach to assess the effect of aging

and degradation of active components on plant risk. The work (a) develops a way to identify and quantify age-dependent failure rates of active components, and to incorporate them into PRA; (b) demonstrates the approach by applying

it to a fluid-mechanical system, using the key elements of a NUREG-1 150 PRA; and (c) presents it as a step-by-step

approach, to be used for evaluating the risk significance of aging phenomena in systems of interest.

The approach uses statistical tests to detect increasing failure rates and for testing data-pooling assumptions and model

adequacy. The component failure rates are assumed to change over time, with several forms used to model the age

dependence-exponential, Weibull, and linear. Confidence intervals for the age-dependent failure rates are found and

used to develop inputs to a PRA model in order to determine the plant core damage frequency. The approach was used

with plant-specific data, obtained from maintenance work requests for the auxiliary feedwater system of an older pressurized water reactor. The approach can be used for extrapolating present trends into the near future and for supporting riskbased aging management decisions.

12. KEY WORDS/DESCR!PTORS (List words orpihrases that willassist researchers in locating the report.) 13. AVAILABILITY STATEMENT

Management Management of Aging ~~~~~~~~~Unlimited of Aging 14. SECURITY CLASSIFICATION

Probabilistic Risk Assessment (This PageI

Unclassified

(This Report)

Unclassified

15. NUMBER OF PAGES

16. PRICE

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