reliability data book

RELIABILITYDATA BOOK

for components in Swedishnuclear power plants

RKS SKiNUCLEAR SAFETY BOARD SWEDISH NUCLEAR POWER

OF THE SWEDISH UTILITIES INSPECTORATE

RELIABILITYDATA BOOK

for components in Swedishnuclear power plants

Prepared by

j-P Bento, project leader, Nuclear Safety Board of theSwedish Utilities

S Björe, Asea-Atorn A BG Ericsson, Asea-Atom ABA Hasler, Asea-Atom ABC-0 Lydén, Asea-Atom ABL Wallin, Asea-Atom A BK Pörn, Studsvik Energiteknik ABO Åkerlund, Studsvik Energiteknik AB

Prepared for

RKS - Nuclear Safety Board of the Swedish Utilities

SKI - Swedish Nuclear Power Inspectorate

Contents1. Introduction

2. Scope and limitations2.1 Plants and periods2.2 Systems in the failure statistics2.3 Types of components in the failure statistics

3 . Physical boundary of components

3.1 Mechanical components3.2 Instruments3.3 Electrical components

4. Definitions

4.1 General4.2 Gassification of failures for mechanical components4.3 Gassification of failures for instruments4.4 Gassification of failures for electrical components (incl diesel generators)4.5 Others

5. Statistical procedure

5.1 Estimating reliability parameters5.2 How to use this book calculating reliability for specific components

6. Results

6.1 Component failure rates6.2 Licensee event reports

7. Comments on evaluated component failures

7.1 General7.2 Pumps7.3 External leakage7.4 Internal leakage7.5 Indication failures7.6 Failure to change position7.7 Self pressure operated valves with motor7.8 Pneumatic valves7.9 Check valves7.10 Safety valves for the pressure relief system7.11 Other safety valves7 1 2 Control rods and rod drives7 !3 Instruments7.54 Diesel generators•.15 Batteries7.16 Static rectifiers7.17 Static inverters7.18 Rotating converters7.19 Transformers7.20 Busbars7.21 Circuit switching units7.22 Generator breakers7.23 Breakers7.24 Static converters

8. References

9. Reliability data tables 1 - 54

Reliability Data Tables

Centrifugal pumps in operationCentrifugal pumps, intermittent operationCentrifugal pumps, standbyReciprocating pumps, standby

AM - Isolation valvesAM - Self pressure operated valvesAP - Isolation valves, pneumaticBV - Check valvesRM - control valves, motor operatedSV - Safety valvesSolenoid valvesTabulation of indication failures for valves

Tables 1 - 4Tables 5 - 6Tables 7 - 9Table 10

Tables 1 1 - 1 3Tables 1 4 - 15Tables 1 6 - 1 7Tables 1 8 - 19Tables 20Tables 21 - 22Tables 23 - 24Table 25

Control rods / Rod drives

Pressure sensor/transmitterPressure difference sensor/transmitterFlow sensor/transmitterLevel sensor/transmitterTemperature sensor/transmitterElectronic limit switches / indicating instruments

Diesel generators, standbyBatteriesRectifiersInvertersRotating convertersTransformersBus barsBreakersStatic rectifiers

Table 26

Tables 28 - 29Tables 30-31Tables 32 - 33Tables 34 - 35Tables 36 - 37Tables 38 - 39

Table 40Table 41Table 42Table 43Table 44Tables 45 - 47Tables 48 - 50Tables 5 1 - 5 3Table 54

1 INTRODUCTION

ASEA-ATOM has been commissioned by the Nuclear Safety Boardof the Swedish Utilities and the Swedish Nuclear Power Inspector-ate to outline a manual regarding reliability data for componentsin the Swedish nuclear power plants. The work succeeds andupdates the previous »T-bok», version 1 -RKS 82-07.

The main objective of the project has been to provide (improve)failure data for reliability calculations as parts of safety analysesfor Swedish nuclear power plants.

The work is based primarily on evaluations of failure reportsin the ATV*-system and Licensee Event Reports reported to theSwedish Nucelar Power Inspectorate, as well as informationprovided by the operation and maintenance staff of each plant.

In the report are presented charts of reliability data for:

- pumps- valves- control rods/rod drives- electrical components- instruments

The statistical evaluation of presented failure data has been madeby Studsvik Energiteknik AB.

The work succeeds and updates previous work by ASEA-ATOM,Studsvik Energiteknik AB, VTT and NUS Corp, references 1-5.

* ATV ("The Swedish Thermal Power Reliability Data System")data collecting system jointly established by the Swedish utilities.

8

2 SCOPE AND LIMITATIONS

2.1 Plants and PeriodsIn order to obtain well defined statistical basic data it has b«ennecessary to exclude certain portions of the available ATV-material.It has been agreed to exclude the operation start up periods ofeach reactor as well as periods where the failure reporting has i.otbeen found to be satisfactory.

Thus the revision or annual refueling outages and other durablestops normally are not included in the component statistics.Exceptions are made for components and systems in operationthroughout the whole year (Residual Heat Removal System)and components tested mainly during the annual refuelin» outage(safety valves in the Reactor Pressure Relief System, system 314).

The statistics cover the following plants and periods:

Barsebäck 1 77.10.01-82.12.31

Barsebäck2 79.01.01-82.12.31

Forsmark 1 81.01.01-82.12 31

Forsmark 2 81.07.01-82.12.31

Oskarshairn 1 74.01.01-82.12.31

Oskarshamn 2 76.01.01-82.12.33

Ringhals 1 76.10.01-82.12.3 5

Ringhals 2 77.10.01-82.12.31

The plant specific basic data (ATV Failure Reports) ironi >Ring-hals 2 Safety Study» (ref 5 and 9) have been used for Ringhals 2for the period 77.10.01 -81.05.01 when it comes to mechanicaland electrical components.

2.2 Systems in the failure statistics

The study mainly comprises components belonging to safety relatedsystems. The nason for this is partly that the statistics is to beused for calculations in safety analyses for operating and plannednuclear power plan's, partly that for these systems the obligationto report is clearly stated. Furthermore, these systems are testedregularly in accordance with the Technica' Specifications. When-ever possible the opportunity has been taken to consider com-oonents in systems used in normal plani operation. A compilationof analysed systems is Miown below:

System B1.B2 F1,F2 01 02 Rl R2

Reactor vessel ifControl rods/rod drivesMain steam systemFeed water systemReactor coolant systemPressure relief systemCondensation system 7^Residual heat removal systemContainment spray systemEmergency cooling systemCooling and cleaning systemfor spent fuelAux.feedwater systemChemical and volume controlBoron injection systemHydraulic system for controlrod dtiveiGoverning and safety oil sys -ftDumping equipment system wCondensate system i*

211221/221311312313314316321322323

324327

351

354443

462Area monitoring in react.build& 546/547Electric power equipmentSalt water systemClosed cooling system for321/322Component cooling systemService water system

600712

721723

211221/222411415313314328321322323

324327

351

354442

414545/546600715

711712

211221/222311312313314315/316321322323

324327

351

354416432441/442546600712

721

211221/222311312313314316321322323

324327

351

354416432441/442546/547600712

721723

211221/222411415313314327321322323

324416

351

354442423414545/546600715

711712

211

411415313

321

323

416334

442

414

600715

711

761

includes instruments only

10

Electrical equipment (600) has been divided into following main groups:

System

Generator transformerGenerator switchyardAux power ordinary AC netPriority AC net,standby dieselFrequency converter for maincirculation pumpsStandby diesel systemInverters and distribution sysAux power system DC netControl equipment for electricpowerCable ways

B1.B2

611630640662/663

650661664/665670

680690

F1.F2

612611640654

649650655/656660

570690

01

611631640672/673

650660675/677678/679

680683

02

611630640662/663

650661664/665670

680690

Rl

612611640653/654

649650655/656660

570690

R2

640653/654

650

660

570690

As to the analysed systems in Ringhals 2 the plant specific basic data from the»Ringhals 2 Safety Study» have served as guidelines.

u

2.3 Types of components in the failure statisticsFollowing types of components (belonging to the above men-tioned systems) have been studied:

Pumps main categories:

- centrifugal pumps- reciprocating pumps- screw pumps

Further division into subgroups has been made and the followingcharacteristics have been considered:

- horisontal/vertical- dry/wet- turbine driven- flow rate/developed head- operation mode (in operation, intermittent or standby)

Valves main categories:

- Isolation valvesmotor operated (AM)pneumatic operated (AP)self pressure operated (AE)

- Control valves, motor operated (RM)- Check valves (BV)- Safety/Relief valves (SV)- Solenoid valves

Further division into subgroups has been made according tovalve dimensions.

Evaluating Control rods/rod drives the hydraulic as well as theelectromechanical insertion function have been considered.

Instruments main categories measuring:

- pressure- pressure difference- flow- level- temperature

12

Further division into subgroups has been made considering func-tion/design and following types:

- sensors, switches- transmitters- electronic limit switches- indicating instruments

For instruments, neither size, working media, working tempera-ture nor environment have been considered.

Electrical components (diesel generators included) are dividedinto the following main categories:

- diesel generators- batteries- circuit switching unit- generator breaker- breakers- static rectifier- static inverter- rotating converter- static converter- transformer- bus bar

Further division into subgroups has been made according to actualvoltage level.

13

PHYSICAL BOUNDARYOF COMPONENTS

3.1 Mechanical componentsIn addition to the main component and its equipment,component related switchyard equipment, control equipment(object related logics incl) as well as manoeuvre and indicationequipment generally are included.The component boundary of the various groups of analysedcomponents is shown in the tables. The construction is generaleven though the figures are drawn for specific components.Equipment included within the component boundary is definedby the dashed and dots lines.

Equipment not associated with the main component: powersupply and signals as well as logics not to be considered objectrelated, i e is included in another system number. Normally, powerbreakers and fuses are included in the feeded component. However,exceptions may occur for the manoeuvre power where severalobjects may be supplied from the same fuse and power breaker.

3.2 Instruments

Instruments are divided by function into groups as follows:r

- sensors, switches- transmitters- electronic limit switches- indicating instruments

14

Examples of the physical boundary of the various types of ana-lysed instruments are shown in the tables. In case where themeasure points are complete channels with sensors, transmitters,electronic limiting switches and indicating instruments, those areincluded in the analysis but treated as separate components.The following usually applies to the installation limitations:

— neither process piping, condensate nor reference measur-ing cells are part of any type of instrument

— neither instrument piping, containment isolation valvesfor instruments nor drain pipes are part of any type ofcomponent

— local electric connections and local cabling are parts ofeach instrument

In the same way as for the mechanical components, the boundaryof the component is marked by the dashed and dots lines.

3.3 Electrical components(diesel generators incl)

Examples of the physical boundary of analysed electrical com-ponents are shown in the tables. Correspondingly to themechanical components, auxiliary equipment such as cooling andrelay protection is included. N.B. breakers supplying processobjects are not included in the switchyard distribution.

Equipment included in the analysed component is markedby the dashed ond dots lines.

15

4 DEFINITIONS

4.1 GeneralCritical failures: Any failure that stops the function of the com-ponent, such as, primarily, pump does not start when needed orstops spupiously, and valve does not open/close on demand.Critical failures always lead to repairs.

Degraded failures: The component in question is still working butcertain properties not crucial to the function have degraded.Examples: external leakage (is critical function in case radio-activity should be contained), vibrations and failures in the in-dicating equipment. These failures do not always lead to repairsbut are often postponed to reactor shut down or when convenient.

Incipient failures: The fully function of the component in ques-tion cannot be maintained. Action not taken, the imperfectionmay grow worse and, consequently, repairs are done withoutdelay. Examples: considerable vibrations of pumps, internalleakage in valves, binding valves or loss of lubricant.

Being difficult to distinguish the critical from the incipient, thelatter often are classed among critical failures, when motivated,an incipient failure might be classified as degraded failure.

Failure per demand - the probability that a component does notwork on demand is expressed as failure per demand.

Failure rate - the probability for a component failure per unittime (failure per hour).

Active repair time - the time during which the component isactively repaired (hour).

Down time - the time during which the component is out oforder (hour).

16

4.2 Classification of failures formechanical components

Classifying failures - critical or not — often is difficult, especiallysince the ATV-reports do not always fully describe the event whenit occurred. In order to facilitate interpretation each type of com-ponent has been divided as follows (exceptions see paragraph 7.3regarding external leakage):

Pumps

Isolation valves/control valves

Check valves

Safety/Reliefvalves

Control rods/rod drives

Critical failures

Fails to startSpurious stop

Fails to change position(open/close)Internal leakage

Fails to open/closeStuck in open positionInternal leakage

Spurious openingFails to open/recloseInternal leakage

Insertion function blockedhydraulicly and electro-mechanically respectively

Degraded/incipientfailures

External leakageVibration, noise

Indication errorExternal leakage



EAtemal leakage

In general, the critical failures have been divided into differentgroups depending on how the failure occurred:

- power supply- control equipment- mechanical failure

Within each group a number of failure causes are given whichenables a refinement of the statistics for component failuresat the level of cause. However, any such study is not within theframework of this project except for indication failures, seechapter 7.5.

17

4.3 Classification of failures forinstruments

For each type of instrument the following rough division has beenmade as to critical failures.

Sensors, switches- fails to operate on demand- spurious operation- other critical failures (leakage, circuit and

ground faults )

Transmitters- fails to give high/low signal

Electronic limit switches- fails to operate on demand- spurious operation

Electronic indicating instruments- fails to measure/incorrect measurement

Division into closed circuit current or working circuit currentinstruments has not been made.

4.4 Classification of failures for electricalcomponents (incl diesel generators)

For each type of component the following rough division con-cerning critical failures has been made:

Diesel generators- fails to startspurious stop

Batteries- fails to supply on demand

Rectifiers/static inverters/rotating converters/ static converters- loss of supplied current

Transformers- interruption- short circuit

?8

Busbars- interruption- short circuit- ground leak

Circuit swi ching units- faik d switching- spurious switching

Generator breakers- failed switch off- spurious switch off

Breakers- failed on/off operation on demand- spumous, on/off operation

4.5 OthersThe number of demands has been obtained from test intervalsin the Technical Specifications and from other demands in con-nection with disturbances,for example (scrams) at the plants.Normally, only one demand per test has been accounted for.

In some cases, duration of test intervals have been altered. In thismatter it has been difficult to clarify afterwards when the alter-ations actually took place. Have such problems occurred, thenumber of demands has been conservatively estimated.

The operating time of the various components is estimated fromthe operation profiles of the plants complemented with infor-mation from readings of operating time (pumps).

Average repair time is calculated as arithmetic mean values of thenumber of failures based on time repairs given in the failurereports.

Component replaced by a new one of the same type, and itssubstitute in turn, have all been regarded one and the same fromevalutation point of view.

19

5 STATISTICAL PROCEDURE

5.1 Estimating reliability parameters

Parameteis and moH:K

Two type* A values A;r failure probability have been estimated:

Failure rate X , stating the probability of a component out oforder per unit time. This goes for component in continuousas well as in intermittent operation.

Failure per demand q, stating the probability of a standbycomponent not working on demand.

Statistical models used for estimates of above mentioned para-meters imply the following basic assumptions:

- Each individual component is assumed to have constantfailure rate within the interval studied. This leads toPoisson- and binomial distribution respectively of thenumbers of failures per operating time or per demand.

- Failure rate and failure probability vary for the com-ponents of the studied population. The variation can becaused by varying qualities of materials, environment,maintenance and so on. Therefore failurecharacteristics in question are looked upon as a stocasticvariable described by some suitable distribution.

- Observed failure data (kj, Tj ) or (kj, nj), i = 1, ,N,for N similar components are assumed stocasticallyindependent.

20

The models are described in detail in Ref 7 and 10. The variationof parameters within the observed population of componentsis described in a double parametric distribution. For analyticaland calculation reasons Gamma-distribution in cases of failurerates and Beta-distribution in cases of variations in failure prob-ability have been chosen. So far robustness analysis carried outhave not led to the choice of other types of distribution.

Estimation methods

Estimating the parameters a and 0 in this complex model is not atrivial problem. The Maximum Likelihood Method, used exclusivlyin version 1 of the »T-book» does not always provide solutions orgives unreasonable solutions. In spite of its good qualities from anasymptotic point of view this method is not sufficient enough formoderate numbers of random samples. Therefore, different typesof moment methods have been used as well. The results from thevarious methods have been evaluated in the following order:

1. (ML) the Maximum Likelihood Method

2. (WMM) the Weighted Marginal Moment Method

3. (WPM) the Weighted aPriori Moment Method

The estimate of likelihood is based on the size of calculatedparameter values and on adaptability to observations made,measured by the likelihood function. In as :^any cases as possiblethe aim has been to present pairs of values (a,/3) describing aunique distribution reasonable from the users point of view.Above mentioned estimation methods are described in Ref 10 and11, whereas the likelihood estimate is delt with in Ref 12.

In case no distribution parameters or percentiles are given inthe tables, none of the above mentioned methods has providedreasonable distributions. If so, the estimated mean values only areused.

Since in most estimated distribution the 5% percentile is verysmall it has not been worthwhile to show a lower percentile inthe tables. Therefore, the interval from origo to 95%-percentilecould actually be regarded a measure of uncertainty around themean value.

21

I case the parameters are given (in the tables) they could be usedfor Bayesian estimates of failure probability or failure rate of aspecific component that in respect of type and environment couldbelong to the population described by a and j3. The procedure ofthis estimate, described in the following chapter, is that simplethanks to the choice of Gamma and Beta as apriori distributions.The posteriori distributions are of the same kind and consequentlythe mean values of these distributions are easy to calculate. It issomewhat more difficult, but still possible thanks to statisticaltables or computer programs, to use the posteriori distributionsfor calculating probability intervals at a certain level in order tostate the uncertainty related to the point estimates.

The plant specific values shown in the tables have been calculatedas described above regarding point estimates but instead of a speci-fic component, an average component characteristic to the plantin question has been used. Thereby the conditions of using Bayestheorem are fulfilled, i e to an apriori-distribution describing thevariation between individual components is added observed dataof comparable component. Then the result is regarded applicableto a component typical to the plant. Operating time number ofdemands and number of failures of an average component havebeen calculated as weighted mean values of the separate operatingtimes (demands) and numbers of failures at the plant (Ref 12).

5.2 How to use this book calculatingreliability for specific components

' Making use of the Bayesian method the a and j3 in the tables cani be used for calculating new specific failure data, component orI system specific data, even if the statistical basic data is poor. The* procedure is described below. The new distribution can be usedÄ to define a corresponding interval of uncertainty.

22

Calculating failure rate (Xs) for a specific component

1. Take a for the current kind of failure from the most relevanttable of components

2. Note the number of failures occurred according to kind offailure for the observed component = K

3. Add K to a in order to obtain a new a' = K + a

4. Take from the same table and line as a

5. Note the current operating time of the component = T

6. Add T to 0 in order to obtain a new 0 ' = 0 + T

7. Divide by the sum of a'and 0'. This gives the new specificpoint estimate

Xs= a / 0

Calculating failure probability (Qs) for a specific component

1. Take a for the current kind of failure from the most relevanttable of components

2. Note the number of failures occurred according to the kindof failure for the observed component = K

3. Add K to a in order to obtain a new a*= a + K

4. Add /3 from the same table and lines as a

5. Note the number of demands during the actual operatingtime of the component = N

6. Add N to 0 and subtract K, in order to obtain a new &'= ;>+N-K

7. Divide a by the total of a'and /?". This gives the new specificpoint estimate.

O s = a'/(a'0')

23

6 RESULTS

6.1 Component failure ratesThe results of the statistical evaluation are shown in tables 1 - 54.For each component type/category are shown actual failure modesand related failure rates as well as average time of repairs. In orderto broaden the statistical basic data, sometimes several componentcategories have been put together into one category (e g horisontaland vertical centrifugal pumps, sensors with one and two limitswitches respectively).

The basic data for certain plants and component categories issometimes limited. Therefore, in using presented failure data,primarily basic experiences from all plants should be turned tothe best possible account.

It should be mentioned that failure data for Ringhals 2 (PWR)have been excluded from other plants (BWR) in calculating»Mean value all plants».

24

6.2 Licensee Event ReportsThe number of critical failures reported to the Swedish NuclearPower Inspectorate and not found in the ATV-system, is shownbelow (per plant). Further is shown the total number of evaluatedATV-failure reports as well as the total number of critical failures(ATV).

Plant Number of Number of Licensee EventATV-reports critical failures Reports

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

Ringhals 2 *

570

370

300

250

780

515

690

100

81

69

34

27

126

92

137

24

5

9

7

5

9

11

11

3

Totally 3 575 590 60

* Period of time 81.05.01-82.12.31 for mechanical and electricalcomponents

25

7 COMMENTS ON EVALUATEDCOMPONENT FAILURES

7.1 GeneralThis chapter aims at pointing out limitations in the usefulness whichcould mean that some incorrect contributions are excluded fromthe tables and that the construction of specific components ismade clear in order to avoid misinterpretations.

In the following general comments as well as comments on con-ditions of specific components are given.

7.2 PumpsVibrations/noises in pumps usually are not classified amongcritical failures. However, in case of high vibrations or observedbearing plays or pumps being replaced or repaired, these have beenregarded critical failures.

For reactor main coolant pumps only the failure mode spuriousstop is shown in the table. Unstable regulation has not beenregarded critical failure.

26

7.3 External leakage

External leakage seldom lead to component critical failure eventhough classified like that in ATV. On the other hand secondaryeffects could result in failure to function. Examples: leakageflooding equipment or triggering some isolation signal.This phenomenon should be analysed separately for eachsituation.

7.4 Internal leakage

Internal leakage in valves almost always are discovered duringthe annual refueling outage. Therefore no compilation of thesefailures is made within the framework of this study. Some com-ments are worth mentioning:

Specifications for leakages on containment isolation valvesare very strict and therefore leakages reported very seldom aresignificant in a risk analysis. In respect of open/close opera-tions the valves often have sufficient function but they donot meet with the Technical Specifications for leakages.In case of significant leaking valves (e g leaking radio-active substance) a separate analysis have to be carried outalso using basic data from the annual revision periods.

7.5 Indication failuresIndication failures usually are not included as critical failures.However, it should be mentioned that indication failures may leadindirectly to critical failures, either through action taken by thestaff because of the misleading information or because the indi-cation in question is linked to blocking conditions of other com-ponents.

In the extent of the project is stated that failure to function oflimit switches should be presented as a separate type of com-ponent which failure to function should be analysed.

27

A compilation of indication failures for different types of valvesis shown below. The values for failure probabilities are not unam-biguously linked to the limit switches but are generally named»indication failures». Following types of failures are to be found:

- failures in electronic circuit cards

- limit deviation failures

- defective potentiometers

- defective adjusting device

Indication failures for various types of valves

Type of valve Loss of/incorrect Spurious/incorrectindication indication(10-3/demand) (10-6/n)

Isolation valvt (AM) 0.9 0.9motor operated

Isolation valve (AP) 0.8 0.6pneumatic operated

Check valve (BV) 33 23

»Loss of indication» is valid for failures discovered on demand ortest of main components. As to »spurious indication» the failureshave been discovered via control room indication, alarm etc.

For further information see enclosed tables where backgrounddata as number of failures, number of actuations and operationaltime are shown.

7.6 Failure to change positionThe failure modes »do not open/do not close» concerning valvesare difficult to separate. The available material does not alwaysstate whether the failure occurred when closing or opening.Furthermore it is not clear whether the failure occurred at the firstactivation or when the valve returned to its original position. Thedifference may seem minimal but in the first case it means thatthe number of demands equals the number of tests while in thesecond case there must be two demands per test. The basic datadoes not allow a division and therefore we have chosen to present»failure to change position» only. In this case Open/Close-operationis regarded as one demand.

28

7.7 Self pressure operated valves with motors

It should be mentioned that occurred failures mainly are linkedto the »close (open)-function» by means of the motor. The selfpressure closing function redundant to the motor operation isabout ten times more reliable. In application it is important toknow to what extent the two close-functions can be credited.

7.8 Pneumatic valvesPneumatic valves are not categorized by dimension into subgroups.Most of the valves (about 90%) have connections of 100 mm orless. Pneumatic spring opening valves in the Hydraulic ScramSystem (354) are treated separately. In principle, only the open-function, interesting from the safety point of view, is studied.

The most frequently reported kind of failure »crack or break inmembran» is considered not as critical failure. The reason forour conclusion is that the membran failures do not affect theinteresting open-function (spring opening). However, it is uncertainwhether the close-function could be maintained if the membranis broken. This aspect should be considered when studyingcharging/recharging of system 354.

7.9 Check valvesCritical failures have been grouped into:

1. failure to open2. failure to close (stuck in open position)3. Internal leakage

Distinction between 2 and 3 is vague. Internal leakages reportedhave almost always been discovered during the annual revisionperiod in pressure boundary tests, see chapter 7.4. The kinds offailures of check valves are thus grouped:

- failure to open

- failure to close

Mechanical failures like »get stuck/hang in open position» causedby binding, corrosion etc predominate »failure to close».

29

7.10 Safety valves (Pressure Relief System)

The activation of the safety valves is clearly defined as one »open»and one »close» operation. In this case the failure modes are»failure to open» and »failure to reclose». However, it may bedifficult to judge whether the failure is located in the valve itselfor in the electric operated pilot valve. It is important to separatethese two types of failures since failure in the electric operatedpilot valve not necessarily implies failed main valve function.Apart from the electric operated pilot valve there is also a redundantmechanical valve opening of the main valve when high pressure isobtained in the reactor vessel. In evaluating failure data we havetried to classify the failures among the correct categories as far aspossible. In case of uncertainties a conservative judgement hasbeen made.

Leakages in the safety valves of the pressure relief system areregarded as critical failures if occurred during full power operation,but not if discovered during the annual revision period. The reasonfor this is that leakages discovered during revision periods alsowere present during full power operation. Small, and thus un-discovered, these leakages have been regarded acceptable duringcontinued operation.

On three occasions leakages in the relief pipe between main valveand pilot valve have been observed (Oskarshamn 1 — licenseeevent reports). In the first and in the second case the plant wasshut down and in the both cases, after inspection, cracks in a weldwere discovered. The damaged/cracked pipes were replaced. About30 days later the reactor was shut down again since anotherleakage was discovered. All relief piping was replaced in order toprevent further leakage. Action was also taken to reduce the vi-bration level.Above mentioned cases of leakages have conservatively beenclassed as potential causes of failure of spurious opening of mainvalve.

A considerable number of failures observed in the main valve aredue to the fact that the valves are tested at reduced reactor pressure(approx 1.6MPa). On one occasion in Ringhals 1 (78.07.14) seven

! valves failed to open due to leakage in the pilot valves and high* counter pressure in the relief pipes. With full reactor pressure, the•• counter pressure in the relief pipes should be of no importance: and the valves would open. On another occasion in Barsebäck 1* (80.10.24) five valves failed to reclose due to binding of the

main valves.

30

In this case the valve judged as worst was tested at a higherpressure and reclosed. Incorrect testing procedures not simulatingreal conditions of full power operation may well be the cause forfailure reports.

On two occasions we have not been able to decide whether in-creased reactor pressure would make the valves to work or not.Consequently, these failures are classed among the critical failures.For the pressure relief valves the lengths of test intervals havebeen altered on several occasions. It is difficult to trace when thealterations were actually made, the reason for which we havechosen to use the longest test interval (one year) in deciding thenumber of demands as result of test.

7.11 Other safety valves

It is difficult to separate acceptable leakage from spurious openingof safety valve. We have chosen a conservative approach whereleakage generally equals spurious opening. Leakage occurred atfull power operation only has been taken into consideration.

The probability of failure to open on demand cannot be decidedupon from the basic data.

7.12 Control rods and rod drives

Evaluating control rods/rod drives of the ASEA-ATOM reactors,the fact that there are redundant insertion functions should beconsidered. One is hydraulic and the other is electromechanical.To prevent a rod from entering the core requires that either therod itself gets stuck or both rod insertion functions fail.

Simultaneous failure of both rod insertion functions has not beenregistered in any case. As to »stuck rods» one critical failure hasbeen observed.

At reactor scrams all rods but one were inserted as expected. Theone failing was about 1% only from »out-position» and somewhatlater the electric motor stopped due to protection. Later on, using therod drive motor with the motor protection temporarily switched offthe rod was inserted.

31

Examining the control rod/rod drive, damages on the top of therod drive were found. The damages derived from a loose screwhead of the top plate of a fuel element.

Other cases of loose screw heads from fuel channels have beenobserved. However, these have not led to critical failures of thehydraulic insertion of control rods. Furthermore, a few rods have beenstuck in »in-position» due to binding caused by bolts from the coregrid guide rails.

On one occasion failed hydraulic insertion function in the roddrive has been observed. A so called pipe break valve in thehydraulic pipes got stuck in closed position, that prevented thehydraulic insertion of the control rod in question. The cleaningflow through the pipe break valve had failed for a number ofcontrol rods but the hydraulic insertion function had not beenaffected.To protect the motor of the electromechanical insertion mech-anism there are thermal over load limiting protection as well astorque switches. The latter are connected to mechanical skiddingprotection which have been activated on several occasions. Themost common cause for the activation of the over load limitingprotection is rod binding when »out-operated». It also occursthat the limit switches of the rod drives does not work whichbrings the rod closer to mechanical stop and the skidding pro-tection activates.

The most common procedure regarding activated skidding pro-tection is:

1. Failure report is written

2. If the rod protection activates when inserting the rodinto the core, a Licensee Event Report is written.If the protection activates when operating the rod out ofthe core only a failure report is written.

3. The rod drive is test operated in order to restore thefunction.

4. If the rod drive is still not working, the skidding pro-tection switch is blocked ^only the thermal protectionis used). Alternatively the rod is inserted into the core.The principle is not to leave a rod in a position unaccept-able from the safety point of view. Exceptions may befound.

5. If the failure is due to the fact that the limit switch has notworked and that the rod is stopped mechanically, theredundant switch is connected. Limiting indication is loston certain ground faults and in those cases the mechanicalstop is used.

32

It is not always clear from the failure reports what caused thecritical failure. Therefore, we have chosen to class all activationsof skidding protection among critical failures (electromechanicalinsertion) unless it is clearly stated that the skidding protectionhas been activated due to mechanical stop in the out-positionor it is impossible to move the rod from in-position.

Furthermore, it should be mentioned that faulty limit indication»drive nut in» leads to biock/stop of the associated rod motor.This type of failure is included in the failure statistics of electro-mechanical rod function.

Occasionally, in Ringhals 1, the motor and the cable penetrationsbecame dump and the motor function was blocked during theperiod of drying. Nowadays, the construction has been alteredand failures have not occurred since. The failures which occurredare not typical of the present construction and consequentlyexcluded from the data base.

7.13 Instruments

Sensors, switches

In certain cases sensors may serve several limit switches. Thefailure mode »limit switch not operating on demand» given in thetables of reliability data in principle is valid for the kind of failure»failed sensor function on demand». As to »spurious sensor func-tion» the failure data suppplied are representing failure rate percomponent and demand not per limit switch.

The failure mode »other critical failure» is representing sensorfailures discovered otherwise than on demand. Examples on suchfailures: leakage, pipe clogging, etc. The failures have been judgedto be of the kind that lead to »failed sensor function» if theirfunction had been requested before repairs.

As to activation frequency caused by operational conditions datafor many objects are for obvious reasons uncertain. The statisticalbasic data in number of occurred failures are often poor or missing.In cases data are missing in the tables of reliability data the un-certain basic data have not been subject to any statistical treat-ment.

33

Transmitters

As to transmitters (electronic limit switches excluded) the failuremode »failed high/low signal» (failure per hour) is accounted for.The failure mode comprises critical failures where the function ofthe transmitter has been lost. Consequently, cases of incorrectmeasuring value where the deviation is of no importance to theoperation are not accounted for.

Failures caused by incorrect calibration or other obviously humanmistakes are not included in the statistics.

Electronic limit switches

As to the failure mode »unjustified change of position» most ofthe critical failures are caused by »drifting of the limit valueor the electronics». The probability of failed change of positionon demand cannot be defined from the basic data. (See above:Sensors).

Indicating instruments

Failures occurred in the indicating instruments are mainly mechan-ical failures (pointer hung up) or loose contact in the instrument.Failures caused by human mistakes like »zero not adjusted»,are not included in the statistics.

7.14 Diesel generatorsAll plants have diesel generators. Oskarshamn 1 and 2 and Barse-bäck 1 and 2 have two diesel generators each and others have

' four diesel generators.

| Forthcoming the failure modes:

'I »failure to start» (failure per demand)j »unjustified stop» (failure per hour)

i Start refers to the complete sequency as from the physical startup to the diesel generator being ready to supply its objects. The

; number of demands has been defined as the number of tests plus, automatic starts. The time of operation has been calculated as! the product of load tests carried out during the period statisticallyI covered times the normal running time during each load test.

34

Examples of critical failure deriving from the failure mode»failure to start»:

- immediate failure to start caused by overload protectionincorrectly adjusted

- harsh stop mechanism preventing restart

- failure preventing the diesel generator to load

Examples of critical failure deriving from »unjustified stop»:

- spurious trip on long start up time or high voltage causedby failed or incorrectly adjusted relays

Examples of non-critical failures:

- lubrication pump fails to start

- ground leaks

- standby heaters out of order

- indication faults

7.15 BatteriesNormally, batteries are connected to their respective DC nets.These nets usually are powered from rectifiers, batteries areclassed among the standby components.

Failures in batteries seldom appear. Eventually forthcomingfailures are:

- short circuit in battery cell

— ground leaks

- acid leaks

— cracked pole connections

Uncomplicated ground leaks usually are not critical failures.Short circuit in a separate cell normally does not result in criticalfailures. Acid leak may result in critical failures if enduring (forsome time). Sometimes cracked pole connections may result incritical failures.

In certain cases, the batteries themselves are not failing. Too lowcharging voltage can be the cause for failure.

35

The failure mode chosen is »failed effective output on demand».The number of demands has been defined as the number of annualrefueling outages during the time statistically covered. Batteriesare tested during the refueling periods. During electrical outageinterruption (even short ones) the condition of the batteries maybe controlled. Alarm on low voltage indicates that the batteryshould be replaced.

7.16 Static rectifiers

There are static rectifiers in all plants. The failure mode chosenis »loss of effective output» (failure per hour). Generally, thesefailures are few in number, from Barsebäck 1 and Barsebäck 2there is no such failure reports at all.

Critical failures have been burned connections, failed fans, un-stable electronics.

Examples of non-critical failures:

- failed air cooling

- condensator faults

N.B. cooling fan failures may be critical as well as latent (non-critical). The determining factor is whether the rectifier is ableto supply without ventilator of whether there are redundantventilators.

7.17 Static inverters

Except for Oskarshamn 1, Forsmark 1 and Forsmark 2 there arestatic invertes in all plants. Their task is to supply the objectswithout interruption. The failure mode chosen is »loss of effectiveoutput» (failure per hour). Failures are reported from Barsebäck 1and Ringhals only.

Reported failures from Barsebäck 1:

failed component in electronic voltage supply and consider-able frequency variations respectively.

These failures must be regarded as critical for the inverter.

36

The failure in Ringhals 1 was a broken fan. In this case, the failureis regarded as not critical since the inverter was cooled temporarilyusing a vacuum cleaner.

Based on the plant specific basic data in the Ringhals 2 SafetyStudy, two critical failures have been observed in Ringhals 2.

7.18 Rotating converters

Rotating converters are divided into two groups:

1. Rotating converters for speed and regulation of thereactors main coolant pumps. They have no safetyfunction.

2. Rotating converters supplying battery secured AC nets.

The former type is not represented in Forsmark 1 or 2 since they havestatic converters. The failure mode used is »loss of effective output»(failure per hour).

Examples on critical failures:

- tachometer faults

- failure in excitation

- incorrect regulation, generally

- slip rings and brushes completely worn out

Latent failures usually have been:

- slip rings and brushes »somewhat» worn out

Hydraulic clutch failure in a reactor coolant pump motor couldin fact be a critical failure in respect of regulation. However, if areactor coolant pump work at constant speed only, the otherpumps adjust their capacity accordingly so that the plant operationcontinues at requested power.

37

7.19 TransformersExamples on forthcoming critical failures:

- puncture on isolation, isolation faults

- leak current due to pollutioned oil

- loss of oil caused by leakage

- penetration insulator faults

- unjustified turn off caused by failures in the protectionequipment and (for low voltage transformers) cableconnection faults on low current side

At one occasion leakage of oil was reported as well as one occasionof unjustified turn off. However, the most frequent failures arecooling fan failures. These failures are not critical failures of thetransformer unless failures occur in too many fans at the sametime. There is a certain over capacity in the ventilation system.

Reported cooling ventilator failures usually are bearings worn out.

7.20 BusbarsBus bars normally are objects in operation. Their failure modes areground contact, short circuit and interruption.

Failures in the actual bus bars is rare. Such failures may be causedby e.g. bolts not tightened. Loose contact may cause arc that leadsto flash over if the short circuit capacity is not sufficient.

' In case the zero-point of the transformer is directly grounded,ground leaks are critical failures for the bus bar. Ground leaksusually appear outside the switchyard but are indicated by theswitchyard monitoring equipment. These external failures are not

) included in the failure rates of the switchyard.

I

| 7.21 Circuit switching unitsThe circuit switching unit shall control switching between start

1 net and auxiliary net. The circuit switching unit consists of rapidI circuit switching unit and circuit switching unit. Analysed failureI modes are »unjustified switch» (failure per hour) and »failure toI switch» (failure per demand). No critical failures under full powerI operation have been reported.

38

7.22 Generator breakersExcept of Oskarshamn 1 and 2 there are generator breakers in allplants. Analysed failure modes are »unjustified switch off» and»failure to switch off». Generally the generator breakers arereliable components from the operational point of view. Occurredfailures have or should have led to failure to switch off.

Reported failures are leaks in pneumatic valves, compressed airhose faults or burned relay connections. Unjustified switch offhas not been reported.

7.23 BreakersBreakers, contactors and disconnectors are defined as breaker». Inthe reliability data tables these are accounted for under »Breakers»and grouped as follows:

-breaker 6kV < U < lOkV

— breakers, contactors U< 660V

There is a great number of breakers. In our failure analysis we haveincluded failures of all breakers that are reported failing. Further-more, is stated the number of breakers of various types in systemin the 600-serie of each plant.

The failure mode is »failure to faction» which means failed orunjustified manoeuvre caused by e.g. circuit break, defectingcontact, binding, burnt coil or burnt contact plates and groundleaks in contactor.

7.24 Static convertersStatic converters are used instead of rotating converters inForsmark 1 and 2. Consequently, in analysing failures, comparisonshould be considered.

The failure mode used is »Loss of effective output» (failure perhour). In principle static converters consist of a rectifier,continuous voltage equipment and an inverter. The output voltageof the inverter and the frequency of the converter output voltagecan be controlled in order to keep voltage/frequency constant.

39

Critical failures are short circuit in control pulse circuit, contactorfailures, incorrectly adjusted potentiometers, relay faults and fanfailures.

Latent failures are condensator faults. Thus the condensatorsbeing numerous and equipped with fuses there is redundance.

40

8 REFERENCES

1. T-boken (Swedish)Reliability data for component in Swedish nuclear power plantsRKS 1982-07

2. Tillförlitlighetsboken Slutrapport (swedish)Reliability data book Final reportG Ericsson, S Björe ASEA-ATOM PMKPA 82-191

3. Bidrag till tillförlitlighetsdatabok, instrumentdelen (swedish)Reliability data book, Instrument partN Kjellbert, O Johansson, K Pörn, Studsvik Nr 82/137

4. Reliability of diesel generators in finnish and Swedish nuclear power plantsTMankamoetal VTT SÄH 7/82

5. Ringhals 2 Safety StudyNUS Corp, May 1983

6. Systematisk erfarenhetsåterföring av driftstörningar på blocknivå isvenska kärnkraftverk (swedish)Experience feed back for failures in swedish nuclear power plantsK Laakso ASEA-ATOM PM KPA 82-114

7. Tillförlitlighetsdata för elektriska komponenter i svenska kokvatten-reaktorers prefererade/favoriserade hjälpkraftsystem (swedish)Reliability C 'ta for electrical components in swedish BWRsN Kjellbert, O Johansson, K Pörn, H Tuxen-Meyer, Studsvik Nr 82/217

8. Arbetsmaterial för »Studsvik Nr 82/217» and »Studsvik Nr 82/137»Basic data for »Studsvik Nr 82/217» and »Studsvik Nr 82/137»

9. Arbetsmaterial - underlag för »Ringhals 2 Safety Study»Basic data for »Ringhals 2 Safety Study»

10. Use of non-Conjugate Prior Distributions in Compared Failure ModelsJ K Shultis, NUREG/CR-2374, Dec 1981

11. Properties of parameter Estimation Techniques for a Beta-BinomalFailure ModelJ K Shultis et al, NUREG/CR-2372, Dec 1981

12. Robustness and estimation of prior distributions for the analysis ofreliability dataK Pörn, O Åkerlund (to be published)

41

9 RELIABILITY DATATABLES

42

Centrifugal pump, horisontalBackground data

Failure mode: Spurious stopNumber of components: 14Number of demands: 28.8 E4 (per operational time)Number of failures 8Value of Alfa: 0.0527Value of Beta: 19000

The method of estimation used is Weighted aPriori Moment Method (WPM).

RINGHALS 2

Failure mode: Spurious stopNumber of components: 2Number of demands: 4.32 E4 (per operational time)Number of failures: 3Value of Alfa:Value of Beta:


Physical boundary of the component

See page 44

Centrifugal pump, horisontal

43

Table 1

Flow rate:

Developed head:

Operational mode:

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

Ringhals 2

Mean value

40-60 kg/s

0,5-0,7 MPa

in operation

Spuriousstop

(lO^/h)

25.

1.6 *

20.

2.1 *

0.98 *

21.

34.

28.

110.

69.

Active repair(average)

(h)

10

—

40

—

—

3

8

11

3

* No critical failures reported

44


Background data

Failure mode:Number of components:Number of demands:Number of failures:Value of Alfa:Value of Beta:

Spurious stop1618.1 E4 (per operational time)50.31513800

Method of estimation used is Weighted aPriori Moment Method (WPM).


24 V 1=

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UF2

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rSwitchyardEquipment

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380V

Fuse

Feeder Switch Manual(norm ON)

H1Relay "> \

overload — j ComponentCable . protectionoverload j _ |

Contactor/Switch

^ r j i i i •MotorTransmissionPump


45

Table 2

t

Flow rate:

Developed head:

Operational mode:

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

130-200 kg/s

0,7 MPa

in operation

Spuriousstop

(lO^/h)

9.8 *

11. *

23.

26.

—

54.

9.7 •

23.

100.


(h)

• -

—

8

32

—

16

—

18


46

Centrifugal pump, wet

Background data

Failure mode:Number of components:Number of demands:Number of failures:Value of Alfa:Value of Beta:Method of estimation:

Spurious stop1427.2 E4 (per operational time)191.9324900Maximun Likelihood Method (ML)

RINGHALS 2

Failure mode:Number of components:Number of demands:Number of failures:Method of estimation:

Spurious stop22.56 E4 (per operational time)3Weighted aPriori Moment Method (WPM)


24 V t =

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n Fuse


Relay J Contactor/Switch

Motor r 'overload — j ComponentCable . protectionoverload

IMotorTransmission

Pump

Centrifugal pump, wet

47

Table 3

Flow rate:

Developed head:

Operational mode:

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

Ringhals 2

Mean value

75-150 kg/s

l,3-l,8MPa

in operation

Spuriousstop

(10'6/h)

93.

94.

87.

93.

33. *

98.

48.

78.

190.

117.


(h)

18

30

no data

4

—

8

32

18

24

å

No critical failures reported

48

Centrifugal pump, (reactor coolant pump)Background data

Failure mode:Number of components:Number of demands:Number of failures:Value of Alfa:Value of Beta:

Spurious stop38112.E4 (per operational time)30.067125100



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MotoroverloadCableoverload

T i Contactor/Switch

|. Component•. protection I

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Centrifugal pump (Reactor coolant pump)

49

Table 4

Flow rate:

Developed head:

Operational mode:

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

1306-2347 kg/s

0,3-0,4 MPa

in operation

Spuriousstop

(10"6/h)

1.1 *

5.8

4.8

1.9 *

0.82 *

0.90 *

3.6

2.7

15.


(h)

—

2

8

—

—

—

4

5


50

Centrifugal pump, horisontal and vertical

Background data

Failure mode:Number of components:Number of demands:Number of failures:Value of Alfa:Value of Beta:Method of estimation:

Spurious stop6678.60 E4 (per operational time)130.21012700Weighted aPriori Moment Method (WPM)

RINGHALS 2

Failure mode:Number of components:Number of demands:Number of failures:Method of estimation:

Spurious stop108.67 E4 (per operational time)7Maximum Likelihood Method (ML)

Physical boundary of the component A

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Motor f~'overload —'.Component ICable . protection |overload (_ I •

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51

Table 5

Flow rate:

Developed head:

Operational mode:

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

Ringhals 2

Mean value

75-250 kg/s

0,3-0,9 MPa

intermittent

Spuriousstop

(lO^/h)

16.

26.

19.

14. *

14.

11.

20.

17.

84.

81.

Failure tostart

(1(T3 /demand)

3.8

6.8

3.5

2.8 *

2.2

2.3

8.1

3.9

21.

1.4


(h)

11

12

4

—

7

9

11

10

24


52

Screw pump

Background data

Number of components:Failure modes:Number of demands(per operational time)Number of failures:Value of Alfa:Value of Beta:Method of estimation:

RINGHALS 2

Number of components:Failure modes:Number of demands(per operational time):Number of failures:Method of estimation:

7Spurious stop

12.0E40———

6Spurious stop

12.97 E44WPM

Failure to start

39910.16465.2WPM

Failure to start

3540


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MotorTransmission

Pump

Screw pump

53

Table 6

Flow rate:

Developed head:

Operational mode:

750kg/s;550kg/s

0,2 MPa; 0,3 MPa

intermittent

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

Ringhals 2

Mean value

Spuriousstop

(10-6/h)

-

—

-

—

—

*

*

31.

Failure tostart

(10~3/demand)

-

-

-

—

-

2.5

2.5

14.

*


(h)

—

—

—

—

—

8

8

32


54

Centrifugal pump, horisontal and verticalBackground data

Number of components:Failure mode:Number of demands:Number of failures:Value of Alfa:Value of Beta:Method of estimation:

RINGHALS 2

Number of components:Failure mode:Number of demands:Number of failures:

12Failure to start696 (per operational time)10.11680.3Weighted aPriori Moment Method (WPM)

Failure to start60 (per operational time)0


_S

HF

t =l

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Clamping Device3Indi-cations Pedestal 1

Relay

Motor | ' 1overload — j ComponentCable . protectionoverload I |

Contactor/Switch

zrj i I 'MotorTransmissionPump


55

Table 7

Flow rate:

Developed head:

Operational mode:

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

Ringhals 2

Mean value

30 kg/s

2,2-6,7 MPa

standby

Failureto start

(lO"3/demand)

0.86 *

0.90 *

-

-

—

2.4

-

1.4

8.3

*


(h)

—

—

—

—

—

2

—

2

—


56

Centrifugal pump, horisontal and verticalBackgrond data

Number of components:Failure mode:Number of demands:Number of failures:Value of Alfa:Value of Beta:Method of estimation:

18Failure to start784 (per operational time)40.38775.4Weighted aPriori Moment Method (WPM)


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380 V

~1 Fuse

-\/-< | Feeder Switch Manual(norm ON)

HiRelay 1 Contactor/Switch

MotoroverloadCable ! protectionoverload

\ Component

I 'MotorTransmissionPump

57


Table 8

Flow rate:

Developed head:

Operational mode:

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

AH BWR plants

Mean value

95%

120 -240 kg/s

1,2-1,8 MPa

standby

Failureto start

(lO"3/demand)

7.0

3.3 *

4.0 *

4.3 *

11.

2.6 *

2.8 *

5.1

21.


(h)

5

—

—

-

2

—

-

3

• No critical failures reported

58

Centrifugal pump, turbine drivenBackground data


RINGHALS 2


Failure to start171 (per operational time)0

1Failure to start30 (per operational time)1

Centrifugal pump, turbine driven **

59

Table 9

Flow rate:

Developed head:

Operational mode:

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

Ringhals 2

Mean value

40 kg/s; 240 kg/s

8MPa;l,8MPa

standby

Failureto start

(10-3/d)

—

—

—

—

—

—

*

*

33.


(h)

—

—

—

—

—

—

—

—

8


** Auxiliary equipment not included

60

Reciprocating pumpBackground data

Number of components:Failure mode:Number of demands:(per operational time)Number of failures:Value of Alfa:Value of Beta:Method of estimation:

22Failure to start

123850.18646.0Weighted aPriori Moment Method (WPM)


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Reciprocating pump

61

Table 10

Flow rate:

Developed head:

Operational mode:

2,5-3,9 kg/s; 22,5 kg/s

8,7 MPa; 8,5 MPa

standby

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

Failureto start

(10"3/d)

2.0 *

2.1 *

1.5 *

3.9

9.2

1.6 *

11.

4.0

21.


(h)

—

—

—

9

4

—

8

7


62

AM-isolation valve, motor operatedBackground data

Number of components:

Failure mode:Number of demands:(per operational time)Number of failures:Value of Alfa:Value of Beta:Method of estimation:

71Failure to change position

2512180.30738.5Maximum Likelihood Method (ML)

RINGHALS 2

Number of components:Failure mode:Number of demands:(per operational time)Number of failures:Method of estimation:


9835Maximum Likelihood Method (ML)

Physical boundary of the component 380 V

24 V

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1 Equipment

o^V>

open

1 Feeding directly frommain supply or sub-supply depending onohject

Fuse

Feeder switch manualNormally On

Contactors

Torque switch Component J• protections

L.close -oS>—• j I

.J

Motor

AM-isolation valve, motor operated

Table 11

63

Pipe dimension:

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

Ringhals 2

Mean value

DN < 100 mm

Failure tochange position

(10-3/demand)

9.8

9.7

7.6

5.8 *

10.

5.3

5.1

7.9

36.

5.3


(h)

3

4

7

-

2

6

3

4

3


64





RINGHALS 2



6001Weighted aPriori Moment Method (WPM)

Physical boundary of the component380 V

24 V

automationfor comp.

Indications

Clamping j I• device |

TedestaT ~jopen -oN>_

stop - o N i _

close -oS>—

(If "Tmi 1

Equipment

SwitchyardEquipment

open I

' close?

I rniT

rv<


Fuse


ipnt I

Contactors

Torque switch ! Component |I protections

J ^ - • - —i

i i l .JM

" _ J i IMotor

I Valve

65

Table 12AM-isolation valve, motor operated

Pipe dimension: 100<DN<200 mm

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

Ringhals 2

Mean value


(10-3/demand)

4.3

7.8

3.6

6.7

11.

2.9

1.4 *

6.3

37.

1.7


<h)

4

4

8

4

3

3

—

4

No data


66





RINGHALS 2



14865Maximum Likelihood Method (ML)


2«V |=

Logic and

Clam pingdevice

Indications

I ucvite

Pedestal

open

stop —o

1

}

1

Controlautomation Equipmentfor com p.

ofo—

close - o V - i j I

380 V Feeding directly frommain supply ot sub-supply depending onobject

Fuse


Contactors

Torque switch Component j

MotorValve

AM-isolation valye, motor operated

67

Table 13

Pipe dimension:

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

AU BWR plants

Mean value

95%

Ringhals 2

Mean value

DN > 200 mm


(10~3/demand)

7.0

9.9

3.5 *

4.0 *

3.2 *

4.6

9.0

7.2

42.

3.3


(h)

4

2

—

—

—

5

5

5

8


68

AM -self pressure operated valve(Main steam system)Background data

jnents:Failure to change position

Number of components:Failure mode:Number of demands:(Per operational time)Number of failures:Value of Alfa:Value of Beta:

24Failui

632160.93736.1

The method of estimation used is the Weighted aPriori Moment Method (WPM).

69

Table 14

AM - self pressure operated valve (Main Steam System)

(redundant closure)

Pipe dimension: DN500,DN600 mm

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%


(1(T3/demand)

29.

20.

15. *

22.

—

30.

34.

25.

77.


(h)

2

No data

—

2

-

4

4

4


70

A-self pressure operated valve(Main steam system)Background data

Number of components:Failure mode:Number of demands:(Per operational time)Number of failures:Value of Alfa:Value of Beta:

24Failure

63220.090028.3


71

Table 15

A - self pressure operated valve (Main Steam System)

Pipe dimension: DN500,DN600 mm

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%


(10~3/demand)

1.5 *

1.8 *

1.7 *

2.0 *

-

1.4 *

11.

3.2

19.


(h)

—

—

—

—

—

—

No data

No data


72

AP-isolation valve, pneumaticBackground data

Number of components:Failure mode:Number of demands(per operational time)Number of failures:Value of Alfa:Value of Beta:Method of estimation:

RINGHALS 2





12368Weighted aPriori Moment Method (WPM)


>A

24V t

rLogic and il Controlautomation for Equipmentcomponent

Gam pingdevice

Indications Pedestal 1

openclose-

I

110V t

i r

Feeding directly from_j main supply or sub-

supply depending onobject

Feeder switch

Relay; 1

I

- -At - Contactor

gas underpressure

Valve

73

AP - isolation valve, pneumatic

Table 16

Pipe dimension:

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

Ringhals 2

Mean value

DN < 100 mm


(10"3/demand)

6.7

2.8 *

2.9 *

7.2 *

11.

5.5

5.2

5.9

34.

6.5


(h)

10

—

—

3

3

7

9

6

5


74

AP-isolation valve, pneumatic(Hydraulic Scram System)

Background data



2781640.0203141.Weighted aPriori Moment Method (WPM)


>A

0

24 V t

r

Camping• device

IIndications Pedestal |

openj close -o^-

[]

Logic and i| Controlautomation for Equipmentcomponent

I

HFFeeding directly frommain supply or sub-supply depending onobject

110 V t

I]

( ] Fuse

i r

UF2

Feeder switch

Relays

I

- - V - Contactor

gas underpressure

Valve

AP - isolation valve, pneumatic

(Hydraulic scram system)

75

Table 17

Pipe dimension:

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

DN < 100 mm

Failure toopen

(KT3/demand)

0.068 *

0.082 *

0.11 *

0.12 *

0.33

0.061 *

0.11 *

0.14

0.33


(h)

—

—

—

—

4

—

—

4


76

BV- check valveBackground data

Number of components:Failure modes:Number of demands:(per operational time)Number of failures

417Failure to open

36280

Failure to close

36282

Value of Alfa:

Value of Beta:0.0129

23.3

RINGHALS 2

Number of components:Failure mode:Number of demands(per operational time)Number of failures:

18Failure to open

6580

BV - Check valve

77

Table 18

Pipe dimension: DN<100 mm

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

Ringhals 2

Mean value

Failure toopen

(10-3/demand)

*

*

*

*

*

*

Failure toclose

(10-3/demand)

0.25 *

3.9

0.38 *

0.43 *

0.27 *

0.19 *

0.23 *

0.55

—

—


(h)

—

12

—

—

—

—

—

12

—


78

BV-check valveBackground data

Number of components:Failure modes:Number of demands:(per operational time)Number of failures:Value of Alfa:Value of Beta:Method of estimation:

RINGHALS 2

Number of components:Failure mode:Number of demands(per operational time)Number of failures:

168Failure to open

321110.0071011.2ML

33Failure to open

18440

Failure to close

3211110.056816.5WPM

BV - Check valve

Table 19

79

Pipe dimension: DN> 100 mm

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

Ringhals 2

Mean value

Failure toopen

(10~3/demand)

0.16 *

0.22 *

0.31 *

0.35 *

2.7

0 12 *

0.12 *

0.63

—

*

Failure toclose

(10~3/demand)

5.1

4.1

2.0 *

2.2 *

4.1

3.1

2.0

3.4

19.

—


(h)

3

23

—

—

14

3

12

9

—


RM- control valve, motor operatedBackground data

Number of components:Failure mode:Number of demands:(per operational time)Number of failures:Value of Alfa:Value of Beta:

69Failure

2012220.09713.75

The method of estimation used is the Maximum Likelihood Method (ML).


2«V

Logic andautomationfor com p.

LCampingdevice

indications Pedestal ~ |

ControlEquipment

o f t > ^

" _ J i I

MOV

i r, Switchyard

Equipment

r~* L-f—• i

A UF2 Feeding directly frommain supply or sub-supply depending onobject

Fuse


Contactors

Torque switch ^Component!i protections

1 * - i

RM - Control valve, motor operated

81

Table 20

Pipe dimension:

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

various


(10~3/demand)

9.2

23.

17. *

17. *

23.

3.4

13.

25.

160.


(h)

3

6

—

—

1

1

5

4


82

SV- safety valve

Background data


139Spurious opening

404.E470.10250300.


SV-Safety valve

83

Table 21

Pipe dimension: various

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

Spuriousopening

(lO^/h)

1.2 *

3.2

2.1

2.9

2.0

1.0 *

. 1.1 *

2.0

12.


(h)

—

3

4

5

4

—

—

4


84

SV- safety valve(Pressure Relief System)

Background data

Number of components: 126 (main valve)Failure modes: Fail to open Fail to closeNumber of demands:(per operational time) 1281 1281Number of failures: 1 2Value of Alfa 0.0167 0.0232Value of Beta 21.4 9.67Method of estimation: WPM ML

55 (pilot valve)Fail to open

84570.13015.6

WPM

Fail to close

84510.068457.7WPM

85

Table 22

SV - Safety valve, ind pilot valve (Pressure Relief System)

Pipe dimension: DN 125, DN 150, DN 300 mm

Power plant Spurious Failure to open Failure to redose Active repairopening main valve pilot valve main valve pilot valve (average)

/h) (10"3/d) (10"3/d) (10"3/d) (10'3/d) (h)

Barsebäck 1

Barsebäck 2

Forsmark 1

-oremark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

Ml BWR plants

Aean value

•5%

2.0

0.87 *

1.0 *

1.1 *

1.9

0.70 *

0.74 *

1.3

7.5

2.5

0,57 *

0.52 *

0.66 *

0.27 *

0.45 *

0.59 *

0.78

1.4

7.2

4.9 *

20.

6.6 *

5.4

6.1

8.3

47.

3.8

1.3 *

1.1 *

1.7 *

0.47 *

0.90 *

3.4

2.4

7.2

0.86 *

0.99 *

0.99 *

1.1 *

2.8

0.86 *

1.0 *

1.2

6.8

9

—

4

—

No data

No data

16

9


86

Solenoid valve, normally avtivated

Background data


513Failure to function

2260.E4160.048768600.


Solenoid valve, normally activated

87

Table 23

Pipe dimension:

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

various

Failure tofunction

(10-6/h)

0.43 •

0.48 *

0.59 *

0.62 *

1.6

0.38 *

0.65

0.71

3.7


(h)

—

—

—

—

2

—

4

3


88

Solenoid valve, normally not activatedBackground data

Number of components:Failure mode:Number of demands:(per operational time)Number of failures:


89610

Solenoid valve, normally not activated

Pipe dimension: various

Table 24

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

* No critical


(10~3/demand)

*

*

*

*

—

*

—

failures reported


(h)

—

—

—

—

—

—

—

Table 25

Tabulation of indication failures for valves

Type of valve

AM-isolationvalve,motoroperated

AP-isolationvalve, pneumati-cally operated

BV-check valve

Failed/incorrect indication

No. offailures

7

24

28

No. ofdemands

8000

29000

846

0(10-3/d)

0.9

0.8

33

Spurious/incorrect indication

No. offailures

7

7

34

Operationaltime(h)

7528000

11411000

1451000

X(lO^/h)

0.9

0.6

23

90

Control rods / rod drivesBackground data

Number of components:Failure modes:

Number of demands:(per operational time)Number of failures:Values of Alfa:Values of Beta:

918Hydraulic scramfunction(rod drives)

3609110.0016760.1

Mechanicalinsertionfunction(rod drives)

126453840.0791119.

Control rods

3609110.0012846.1



Logic andautomationfor compon,

ndications

-t-®HS

4-8

Pedestal ~~|

In Out

I I

24 V 110 V . 380 V

I f f Microswitchcs

i rControlEquipment

opo—

Drive nutIN

Drive nutI OUT

! Skiddingprotection

Control Rod

Hiph pressure water (354)

Rod drive

Piston pipe

Drive mil

Motor

91

Table 26

Control rods/rod drives

Power plant Hydraulic Mechanical inser- Scram and inser- Controlscram func tion function tion function rods(rod drives) (rod drives) (rod drives)

4 * (10-4/d) (10-4/d) (10"4/d)

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

0.9

0.2 *

0.22 *

0.26 *

0.09 *

0.16 *

0.i7 *

0.28

_

7.6

6.5

5.8

6.7

7.0

5.4

7.2

6.6

39.

0.12 *

0.18 *

0.21 *

0.26 *

0.08 *

1.1

0.16 *

0.28


4 demand

92

Pressure sensorBackground data


Number of demands.(per operational <;ir.)Number of fai' > s:Values of A'..Values of * .a :Me t h e • / estimation

RINGHALS 2

Number of components:Failure modes:Number of demands:(per operational time)Number of failures:Method of estimation:

.' ailure tolUnction

1430560.012417.8WMM

34Spurious function

113.1 E41WPM

720Spuriousfunction

2750.E4240.021524600.WPM

Other

113.11WPM

720Other spuriousfaults

2750.E450.0059532700.WPM

spurious faults

E4


When steam condensate £"drain tank is added V

Pressure transmitter

LPSPT

i

j

• —t

Pipe or tank

r Valve closed underk operation (black)

Pressure sensor

93

Table 28

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

AH BWR plants

Mean value

95%

Ringhals 2

Mean value

Failure tofunction

(10-3/demand)

0.74

0.039 *

0.38 *

0.50 *

0.49

0.23

0.84

0.7

—

—

Spuriousfunction

(lO^/h)

1.2

0.59

1.8

1.3

0.53

0.84

1.3

0.87

2.2

0.88

Other spuriousfaults

(lO^/h)

0.088 *

0.095 *

0.66

0.14 •

0.21

0.24

0.082 *

0.18

—

0.88


<h)

2

2

4

4

1

1

3

2

2


94


Background data


203Signal failure

820.E4150.055830500.


RINGHALS 2


12Signal failure

39.91 E41



When steam condensate f'drain tank is added ^


LPSPT

i

j

•—-—1i

Pipe or tank

r Valve closed underk operation (black)

95


Table 29

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

Ringhals 2

Mean value

Signalfailure

(lO^/h)

1.6

1.3

—

—

3.6

1.2

1.3

1.8

10.

2.5


(h)

2

1

—

—

2

1

1

2

5

96

Pressure difference sensorBackground data

Number of components:Failure modes:Number of demand:(per operational time)Number of failures:Values of Alfa:Values of Beta:Method of estimation

RINGHALS 2


Failure to function

19810.21642.6WPM

12Spurious function

39.91 E41WPM

206Spurious function

313.E410.0046714600.WPM


Pressure difference sensor

97

Table 30

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

AH BWR plants

Mean value

95%

Ringhals 2

Mean value

Failure tofunction

(10~3/demand)

—

—

—

—

1.6 *

—

7.0

5.1

26.

—

Spuriousfunction

(lO^/h)

0.094 *

0.11 *

0.53

0.19 *

0.076 *

0.076 *

0.085 *

0.32

—

2.5


<h)

—

—

2

—

—

—

3

3

2

Ho critical failure reported

98

Pressure difference transmitter/cellBackground data


132Signal failure

558.E480.094266200.


RINGHALS 2


72Signal

239.52

failure

E4



99

Pressure difference transmitter/cell

Table 31

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

Ringhals 2

Mean value

Signalfailure

(lO^/h)

0.93 *

1.8

—

—

1.4

1.3

1.7

1.4

8.3

0.84


(h)

—

4

—

—

2

1

3

3

2

No critical failure reported

100

Flow sensorBackground data


Number of demands:(per operational time)Number of failures:Values of Alfa :Values of Beta:Method of estimation:

RINGHALS 2


Number of demands:(per operational time)Number of failures:

34Failure tofunction

99010.01925.83ML

14Spuriousfunction

46.6 E40

134Spuriousfunction

500.E4220.18041900.ML


46.6 E40


500.E420.014837000.WPM


Process piping

Flow elementType: restriction or

venturi tube

101

Table 32Flow sensor

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

AH BWR plants

Mean value

95%

Ringhals 2

Mean value

Failure tofunction

(l(T3/demand)

—

—

—

-

0.40 *

0.26 *

11.

3.3

7.6

—

Spuriousfunction

OO^/h)

2.3 *

2.5 *

6.7

3.5 *

3.7

6.8

8.3

4.3

23.

*


(lO^/h)

0.21 *

1.0

0 29 *

0.31 *

0.18 *

0.74

0.19 *

0.40

0.49

*


(h)

—

3

2

—

1

1

2

2

—

* No critical failure reported

102

Flow transmitterBackground data


97Signal failure

358.E4120.10130200



Process piping

Flow elementType: restriction or

venturi tube

103

Flow transmitter

Table 33

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

Signalfailure

(10^/h)

2.9

3.4

—

—

6.2

5.6

2.3

3.4

19.


(h)

3

3

—

—

2

4

7

3

104

Level sensorBackground data


Number of demands:(per operational time)Number of failures:Values of Alfa:Values of Beta:Method of estimation:

RINGHALS 2


Number of demands:(per operational time)Number of failures:

552Failure tofunction

3890440.001919.24WMM

27Spuriousfunction

89.8 E40

478Spuriousfunction

150O.E4130.064879400.ML


89.8 E40


1940.E4130.020530600.WPM


Level sensor

105

Table 34

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

Ringhals 2

Mean value

Failure tofunction

(10~3/demand)

0.17

0.007 *

0.044 *

0.065 *

0.24

0.010 *

0.099

0.21

—

—

Spuriousfunction

(lO^/h)

0.57 *

0.76

0.69 *

0.72 *

0.64

14.

0.84

0.82

4.6

*


(lO^/h)

0.58

0.94

0.45 *

0.50 *

0.48

0.53

0.88

0.67

1.6

*


»i»

5

1

—

—

2

2

3

3

—


106

Level transmitterBackground data


72Signal failure

289.E4110.18849500.



107

Level transmitter

Table 35

Powei plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

Ringhals 2

Mean value

Signalfailure

(lO^/h)

3.0

3.2

—

—

3.7

4.0

5.8

3.8

20.

7.5


(h)

2

2

—

—

1

1

4

2

2

j t

108

TemperatureBackground data

Number of componentsFailure modes:


RINGHALS 2

Number of componentsFailure mode:Number of demands:(per operational time)Number of failures:

sensor

: 57Failure tofunction

216040.061032.9WPM

: 7

728Spuriousfunction

2250.E4160.021029500.WPM

Spurious function

23.3 E40

109

Temperature sensor

Table 36

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

Ringhals 2

Mean value

Failure tofunction

(10;3/demand)

0.76 *

0.87 *

—

—

0.40 *

0.97 •

2.6

1.9

11.

—

Spuriousfunction

(lO^/h)

0.79

0.83

0.48 *

0.76

0.51

0.43

0.93

0.71

1.8

*


<h)

2

1

-

4

1

4

4

3

—


110

Temperature transmitterBackground data


132Signal failure

289.E480.057920900.


RINGHALS 2


3Signal failure

9.97 E40

Temperature transmitter

111

Table 37

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

Ringhals 2

Mean value

Signalfailure

(10-6/h)

1.7

2.0

2.4

3.6

—

0.85 *

6.4

2.8

15.

*


(h)

1

4

4

2

—

—

3

3

—


112

Electronic limit switchBackground data



249Failure tooperate

125500——

249Spuriousoperation

816. E470.048162700.ML


Transmitter

Indicating instrument

.H1.L1.L2Electroniclimit switch

113

Electronic limit switch


Table 38

Power plant Failure tooperate on demand

(10"3/demand)

Barsebäck 1 *

Barsebäck 2 *

Forsmark 1 *

Forsmark 2 *

Oskarshamn 1 *

Oskarshamn 2 *

Ringhals 1 *

AH BWR plants

Mean value *

95%

Spuriousoperation

(10-6/h)

0.49 *

0.52 *

0.62 *

0.66 *

2.8

0.63

1.0

0.77

4.0


(h)

—

—

—

—

1

1

4

2

114

Electronic indicating instruments

Background data


280Faulty measurement

1040.E480.031541100.



Indicating instrument

Transmitter

.H1.D.L2Electroniclimit switch

L2

Electronic indicating instrument

115

Table 39

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

Faultymeasurement

(10-6/h)

0.69

0.74

0.57 *

0.62 *

0.72

0.59

1.2

0.77

3.1


(h)

1

2

—

—

2

1

3

2


116

Diesel generator

Background data



RINGHALS 2


Number of demands:(per operational time)Number of failures:Method of estimation:

20Failure tostart

2090160.52267.7WPM

4Failure tostart

4926WPM

20Spuriousstop

0.144 E480.33860.8WPM

4Spuriousstop

1640_


24 V

I110V

>1r

Logic and '. J Controlautomation Equipmentfor compon.

SwitchgearEquipment

Fuel

Compressed air

Coolant water

LubricantGeneratorBreaker

117

Diesel generator

Operational mode: standby


Table 40

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

AH BWR plants

Mean value

95%

Ringhals 2

Mean value

Failure tostart

(lO"3/demand)

5.8

3.4 *

4.4

13.

12.

7.5

6.7

7.7

29.

12.

Spuriousstop

(10~6/h)

5200.

6000.

4200. *

8000.

10000.

1800. *

4800.

5500.

24000.

*


(h)

12

27

24

11

28

10

25

20

8

118

BatteryBackground data


129Failed effective output

53170.03462.59


RINGHALS 2


12Failed effective output

600


Battery

Fuses [ ]

Taps

Battery powered bar

L-qr

0

i

LJ— Alarm

Battery incl battery bar

Battery

119

Table 41

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

Ringhals 2

Mean value

Failed effectiveoutput on demand

(10"3/demand)

4.5 *

48.

18.

9.5 *

4.0 *

4.0 *

4.0 *

13.

68.

*


(h)

—

No data

2

—

—

—

—

2

—


120

RectifierBackground data


140Loss of effective output

427.E460.032423000.



380 V

Batteries

[]

Battery powered bar

Rectifier

121

Table 42

Power plant Loss of effectiveoutput


(10"6/h) (h)

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

0.56 *

0.61 *

3.3

0.98 *

3.0

0.46 *

1.3

1.4

5.8

28

16


122

InverterBackground data

Number of components:Failure mode:Number od demands:(per operational time)Number of failures:Value of Alfa:Value of Beta:

10Loss of

38.5 E420.22443100.


RINGHALS 2


Loss of effective output

17.29 E42



Aux supply Battery bar

rReversing switch

Inverter incl reversing switch

"1Alarm

..J

Inverter

123

Table 43

Power plant Loss of effectiveoutput

(lO^/h)


(h)

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

16.

3.1 *

—

—

—

2.5 *

2.7 *

5.2

26.

13

13

Ringhals 2

Mean value 12. 11


124

Rotating converterBackground data


42Loss of

147. E4310.71133700.



440V DC

aux supply(with interference)

II

Rotationregulator

Convertersecured net

125

Rotating converter

Table 44

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

Loss of effectiveoutput

(10-6/h)

15.

27.

15. *

22.

20.

31.

16.

21.

72.


<h)

15

11

—

24

16

14

13

14


126

Main transformer U=400kV, 130kVBackground data

Number of components:Failure mode:Number of demands:(per operational time)Number of failures:Value of Alfa;Value of Beta:

10Interruption

28.8 E410.19556200.



Value beeing fromVoltage regulator

Relayprotection

Tap changegear

Big oil cooled transformer

110V DC

SupervisionProtectionMonitors

Cooler Cooler

380V 110V 380V 110V

Main transfonner U=400 kV, 130 kV

127

Table 45

Power plant Interruption

(lO^/h)


(h)

All BWR plants

Mean value

95%

3.5

18.

38

128

Start- and Auxiliary transformer130/6kV, 70/6kV, 20/6kVBackground data


17Interruption

51.2 E410.10151800.




110V DC

rRelayprotection


Tap changegear

Cooler Cooler

Big oil cooled transformer VrYr380V 110V 380V 110V

k

f

129

Table 46

Start- and AuxiUary transformer 130/6 kV, 70/6 kV, 20/6 kV


All BVYR plants

Mean value

95%

2.0

11.


(h)

130

Transformer U<6kV

Background data


129Interruption

379.E430.034543600.



110V DC

rRelayprotection



Tap changegear

Cooler Cooler

Big oil cooled transformer VrV380V 110V 380V 110V

Transformer U < 6 kV

131

Table 47

Power plant Interruption Active repair(average)

(10"6/h)

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

0.44 *

0.47 *

0.59 *

0.64 *

0.99

0.38 *

1.4

0.79

3.5


(h)

12

10

I

132

Busbar U>20kVBackground data

Number of components: 8Failure modes:Number of demands:(per operational time) 37.0E4Number of failures: 0

8

37.0E40

8Interruption Short circuit Ground contact

37.0 E40


r< • < • < •

Measurement

110V

X Output breaker

I

133

Table 48Bus bar U > 20 kV

Power plant Interruption Shortcircuit

(K)"6/!!) (lO^/h)

Groundcontact


(h)

All plants

* No failures occurred

134

Busbar 6kV<U<20kVBackground data

Number of components:Failure modes:Number of demands:(per operational time)Number of failures:

54Interruption

173. E40

54Short circuit

173. E40

54Ground contact

173. E40

RINGHALS 2


Short circuit Ground contact

17.3 E40

17.3 E40


r

Measurement

_l110V

X Output breaker

135

Table 49

Busbar6kV<U<20kV


(10-6/h)

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

AH BWR plants

Mean value *

95%

Ringhals 2

Mean value -

Shortcircuit

(lO^/h)

*

*

Groundcontact

<10-6/h)

*

*


(h)

—

—

—

—

—

—

-

—


136

Busbar U<500VBackground data

Number of components:Failure modes:Number of demands:(per operational time)Number of failures:Values of Alfa:Values of Beta:

254Interruption

748. E40—

254Short circuit

748. E420.0095229400.

254Ground contact

748. E40

The method of estimation used is the Weighted Marginal Moment Method (WMM).

RINGHALS 2


22Short circuit

95.0 E40

22Ground contact

95.0 E40


r

Measurement

_l110V

X Output breaker

137

Table 50

Bus bar U < 500 V


(10-6/h)

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value *

95%

Ringhals 2

Mean value -

Sho.tcircuit

(lO^/h)

0.15 *

0.16 *

0.22 *

0.79

0.55

0.12 *

0.14 *

0.32

—

Groundcontact

(10'6/h)

*

*


(h)

—

—

—

12

3

—

—

8

—


138

Generator breaker U= 20 kV

Background data


8Failure to open

29530.70065.0ML

8Spurious opening

19.4 E40——


Auto signalsRelay protectionSynchronizingTurbineGroundingInterlocks

Manual order signal

C Interlocks

CentralControlEquipment

LocalControlEquipment J^

SurroundingEquipment

1

24 V 110 V Cooling Compressedwater air

139

Table 51

Generator breaker U=20 kV

Power plant Failure toopen

(10"3/demand)

Spuriousopening

(10-6/h)


(h)

All BWR plants

Mean value 11.

95% 36.


15

140

Breaker 6kV<U<10kVBackground data



278Failure tochangeposition

176030.020812.2WPM

278Spurious changeof position

932. E430.014545200.WPM


Auto signals .SynchronizingRelay protectionCircuit switchingunit

Manual order

LogicControlEquipment Control

Grounding

Grounding interlocks

Q Interlocks j 24 V 110 V 220 V

141

Table 52Breaker 6 k V < U < 1 0 k V

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%


(10"3/demand)

0.82 *

0.90 *

1.3 *

3.6

2.2

2.1

0.98 *

1.7

4.3

Spurious changeof position

(10-6/h)

0.18 *

0.19 *

0.24 *

0.26 *

0.40

0.36

0.40

0.32

0.38


(h)

—

—

—

12

6

3

2

6


142

Breaker U<660VBackground data


Number of demands:(per operational time)Number of failures:Values of Alfa:Values of Beta:Method o f estimation:

730Failure tochangeposition

11471210.029916.3WPM

730Spurious changeof position

2250. E480.011732900.WPM


Auto signalsSynchronizingRelay protectionCircuit switchingunit

Manual order

LogicControlEquipment

Switchyard

Grounding

Grounding interlocks

Interlocks 24 V 110 V 220 V

143


Table 53

Breaker U < 660

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

All BWR plants

Mean value

95%

V


(10~3/demand)

2.4

3.1

1.6 *

1.6 *

1.6

2.0

1.3

1.8

7.3

Spuriousoperation

(10"6/h)

0.82

0.19 *

0.42

0.27 *

0.37

0.30

0.16 *

0.36

—


(h)

4

3

9

-

4

3

1

4

144

Static converterBackground data

Number of components:Failure mode:Number of demands:(per operational time)Number of failures:Value of Alfa :Value of Beta:

16Loss of

19.7 E480.67016500.



10 kVReactor powerset point

Transformer

Set of bars-*-

Coolant air

Reactormaincoolantpump

145

Static converter

Table 54

Power plant

Barsebäck 1

Barsebäck 2

Forsmark 1

Forsmark 2

Oskarshamn 1

Oskarshamn 2

Ringhals 1

AH BWR plants

Mean value

95%

Failed effectiveoutput

(lO-ö/h)

—

—

38.

44.

—

—

—

41.

140.


<h)

—

—

32

25

—

—

—

28

reliability data book

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