Post on 24-Feb-2022
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.
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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
Indication errorExternal leakage
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.
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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 start- spurious 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
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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:
The method of estimation used is Weighted aPriori Moment Method (WPM).
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
Centrifugal pump, horisontal
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).
Physical boundary of the component
24 V 1=
.
~ \Logic / • j ControlAutomation I Equipment
for component
Clamping Device "
IIndi-cations
h•4=®
Pedestal
HF
110V1=
Feeding directly frommain supply or sub-supply depending onobject
UF2
4
rSwitchyardEquipment
ffl |
380V
Fuse
Feeder Switch Manual(norm ON)
H1Relay "> \
overload — j ComponentCable . protectionoverload j _ |
Contactor/Switch
^ r j i i i •MotorTransmissionPump
Centrifugal pump, horisontal
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.
Active repair(average)
(h)
• -
—
8
32
—
16
—
18
* No critical failures reported
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)
Physical boundary of the component
24 V t =
Logic /Automation
for component
Clamping Device
ControlEquipment
f
|
Indi-cations
-4-®
-4-®
Pedestal "1
-A-ru i
r=1*
f K l QSwitchyard - -'• -Equipment
=1 Feeding directly frommain supply or sub-supply depending onobject
n Fuse
Feeder Switch Manual(norm ON)
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.
Active repair(average)
(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
The method of estimation used is Weighted aPriori Moment Method (WPM).
Physical boundary of the component
24 V
=1
Logic /Automation
for component
ControlEquipment
Clamping Device3I
Indi-cations
—H®-4-0
Pedestal 1
r-j i
HF
110V»UF2
r
Feeding directly frommain supply or sub-supply depending onobject
SwitchyardEquipment
380V
Fuse
Feeder Switch Manual(norm ON)
HRelay
MotoroverloadCableoverload
T i Contactor/Switch
|. Component•. protection I
I i :
| '
MotorTransmissionPump
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.
Active repair(average)
(h)
—
2
8
—
—
—
4
5
* No critical failures reported
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
24 V
Logic/ •' ControlAutomation I Equipment
for component
Damping Device3I
Indi-cations
—he-4-s
Pedestal 1
i
rJr.[Ill
J Switchyard -j - J-Equipment
= | 380VFeeding directly frommain supply or sub-supply depending onobject
Fuse
Feeder Switch Manual(norm ON)
Contactor/Switch
Motor f~'overload —'.Component ICable . protection |overload (_ I •
I TMotorTransmissionPump
Centrifugal pump, horisontal and vertical
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
Active repair(average)
(h)
11
12
4
—
7
9
11
10
24
* No critical failures reported
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
Physical boundary of the component
24 V
T
Logic /Automation
for component
Gamping Device3
ControlEquipment
IIndi-cations
-4-e—e
Pedestal 1
•
Motor I"'overload — j ComponentCable — . protectionoverload [_ |
1 Feeding directly frommain supply or sub-supply depending onobject
Fuse
Feeder Switch Manual(norm ON)
Contactor/Switch
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.
*
Active repair(average)
(h)
—
—
—
—
—
8
8
32
* No critical failures reported
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
Physical boundary of the component
_S
HF
t =l
24 V 110 Vt=
=11=
Feeding directly frommain supply or sub-
'f' supply depending on^ object
Logic / •' ControlAutomation Equipment
for component I
r:±| Switchyard -'-'•-Equipment
UF2= | 380 V
Fuse
Feeder Switch Manual(norm ON)
Clamping Device3Indi-cations Pedestal 1
Relay
Motor | ' 1overload — j ComponentCable . protectionoverload I |
Contactor/Switch
zrj i I 'MotorTransmissionPump
Centrifugal pump, horisontal and vertical
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
*
Active repair(average)
(h)
—
—
—
—
—
2
—
2
—
No critical failures reported
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)
Physical boundary of the component
24 V
[TLogic /Automation
for component
Control jEquipment I
Qamping Device
iIndi-cations
h—he
Pedestal
rj i
HF=1
110 V I
ru
Feeding directly frommain supply or sub-
UF1 supply depending on— I object
UF2
SwitchyardEquipment
0(1(1
380 V
~1 Fuse
-\/-< | Feeder Switch Manual(norm ON)
HiRelay 1 Contactor/Switch
MotoroverloadCable ! protectionoverload
\ Component
I 'MotorTransmissionPump
57
Centrifugal pump, horisontal and vertical
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.
Active repair(average)
(h)
5
—
—
-
2
—
-
3
• No critical failures reported
58
Centrifugal pump, turbine drivenBackground data
Number of components:Failure mode:Number of demands:Number of failures:
RINGHALS 2
Number of components:Failure mode:Number of demands:Number of failures:
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.
Active repair(average)
(h)
—
—
—
—
—
—
—
—
8
* No critical failures reported
** 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)
Physical boundary of the component
24 V
Logic / •' ControlAutomation I Equipment
for component
'"'.IClamping Device
IIndi-cations
-4-Ö
Pedestal '1
~ J I
HF
Feeding directly frommain supply or sub-
u f ) supply depending on• object
rSwitchyardEquipment
11(1
UF2= | 380 V
Fuse
Feeder Switch Manual(norm ON)
HiRelay "> V ~
Motor | 1overload — j ComponentCable . protectionoverload I i
I T
Contactor/Switch
MotorTransmissionPump
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.
Active repair(average)
(h)
—
—
—
9
4
—
8
7
* No critical failures reported
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:
22Failure to change position
9835Maximum Likelihood Method (ML)
Physical boundary of the component 380 V
24 V
Logic andautomationfor comp.
Fuse blown 24VWrong positionSwitchgear errorReleased relay
L:Clampingdevice
Indications Pedestal ~1
open —oV>—
stop - o S > _
I rjV"1 ' Switchgear
ControlEquipment
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
Active repair(average)
(h)
3
4
7
-
2
6
3
4
3
* No critical failures reported
64
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:
180Failure to change position
6181300.11418.0Weighted aPriori Moment Method (WPM)
RINGHALS 2
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:Method of estimation:
12Failure to change position
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<
Feeding directly frommain supply or sub-supply depending onobject
Fuse
Feeder switch manualNormally On
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
Failure tochange position
(10-3/demand)
4.3
7.8
3.6
6.7
11.
2.9
1.4 *
6.3
37.
1.7
Active repair(average)
<h)
4
4
8
4
3
3
—
4
No data
No critical failures reported
66
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:
95Failure to change position
3059220.11015.2Weighted aPriori Moment Method (WPM)
RINGHALS 2
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:Method of estimation:
23Failure to change position
14865Maximum Likelihood Method (ML)
Physical boundary of the component
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
Feeder switch manualNormally On
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
Failure tochange position
(10~3/demand)
7.0
9.9
3.5 *
4.0 *
3.2 *
4.6
9.0
7.2
42.
3.3
Active repair(average)
(h)
4
2
—
—
—
5
5
5
8
* No critical failures reported
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%
Failure tochange position
(1(T3/demand)
29.
20.
15. *
22.
—
30.
34.
25.
77.
Active repair(average)
(h)
2
No data
—
2
-
4
4
4
* No critical failures reported
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
The method of estimation used is the Weighted aPriori Moment Method (WPM).
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%
Failure tochange position
(10~3/demand)
1.5 *
1.8 *
1.7 *
2.0 *
-
1.4 *
11.
3.2
19.
Active repair(average)
(h)
—
—
—
—
—
—
No data
No data
* No critical failures reported
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
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:Method of estimation:
86Failure to change position
2366140.12921.7Weighted aPriori Moment Method (WPM)
33Failure to change position
12368Weighted aPriori Moment Method (WPM)
Physical boundary of the component
>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
Failure tochange position
(10"3/demand)
6.7
2.8 *
2.9 *
7.2 *
11.
5.5
5.2
5.9
34.
6.5
Active repair(average)
(h)
10
—
—
3
3
7
9
6
5
* No critical failures reported
74
AP-isolation valve, pneumatic(Hydraulic Scram System)
Background data
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:Value of Alfa:Value of Beta:Method of estimation:
278Failure to change position
2781640.0203141.Weighted aPriori Moment Method (WPM)
Physical boundary of the component
>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
Active repair(average)
(h)
—
—
—
—
4
—
—
4
* No critical failures reported
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
—
—
Active repair(average)
(h)
—
12
—
—
—
—
—
12
—
No critical failures reported
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.
—
Active repair(average)
(h)
3
23
—
—
14
3
12
9
—
* No critical failures reported
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).
Physical boundary of the component
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
Feeder switch manualNormally On
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
Failure tochange position
(10~3/demand)
9.2
23.
17. *
17. *
23.
3.4
13.
25.
160.
Active repair(average)
(h)
3
6
—
—
1
1
5
4
* No critical failures reported
82
SV- safety valve
Background data
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:Value of Alfa:Value of Beta:
139Spurious opening
404.E470.10250300.
The method of estimation used is the Maximum Likelihood Method (ML).
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.
Active repair(average)
(h)
—
3
4
5
4
—
—
4
* No critical failures reported
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
No critical failures reported
86
Solenoid valve, normally avtivated
Background data
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:Value of Alfa:Value of Beta:
513Failure to function
2260.E4160.048768600.
The method of estimation used is the Weighted aPriori Moment Method (WPM).
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
Active repair(average)
(h)
—
—
—
—
2
—
4
3
* No critical failures reported
88
Solenoid valve, normally not activatedBackground data
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:
102Failure to change position
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
Failure tochange position
(10~3/demand)
*
*
*
*
—
*
—
failures reported
Active repair(average)
(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
The method of estimation used is the Weighted aPriori Moment Method (WPM).
Physical boundary of the component
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
* No critical failures reported
4 demand
92
Pressure sensorBackground data
Number of components:Failure modes:
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
Physical boundary of the component
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
Active repair(average)
<h)
2
2
4
4
1
1
3
2
2
No critical failures reported
94
Pressure transmitter
Background data
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:Value of Alfa:Value of Beta:
203Signal failure
820.E4150.055830500.
The method of estimation used is the Weighted aPriori Moment Method (WPM).
RINGHALS 2
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:
12Signal failure
39.91 E41
The method of estimation used is the Weighted aPriori Moment Method (WPM).
Physical boundary of the component
When steam condensate f'drain tank is added ^
Pressure transmitter
LPSPT
i
j
•—-—1i
Pipe or tank
r Valve closed underk operation (black)
95
Pressure transmitter
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
Active repair(average)
(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
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:Method of estimation:
Failure to function
19810.21642.6WPM
12Spurious function
39.91 E41WPM
206Spurious function
313.E410.0046714600.WPM
Physical boundary of the component
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
Active repair(average)
<h)
—
—
2
—
—
—
3
3
2
Ho critical failure reported
98
Pressure difference transmitter/cellBackground data
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:Value of Alfa:Value of Beta:
132Signal failure
558.E480.094266200.
The method of estimation used is the Maximum Likelihood Method (ML).
RINGHALS 2
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:
72Signal
239.52
failure
E4
The method of estimation used is the Weighted aPriori Moment Method (WPM).
Physical boundary of the component
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
Active repair(average)
(h)
—
4
—
—
2
1
3
3
2
No critical failure reported
100
Flow sensorBackground data
Number of components:Failure modes:
Number of demands:(per operational time)Number of failures:Values of Alfa :Values of Beta:Method of estimation:
RINGHALS 2
Number of components:Failure modes:
Number of demands:(per operational time)Number of failures:
34Failure tofunction
99010.01925.83ML
14Spuriousfunction
46.6 E40
134Spuriousfunction
500.E4220.18041900.ML
14Other spuriousfaults
46.6 E40
134Other spuriousfaults
500.E420.014837000.WPM
Physical boundary of the component
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.
*
Other spuriousfaults
(lO^/h)
0.21 *
1.0
0 29 *
0.31 *
0.18 *
0.74
0.19 *
0.40
0.49
*
Active repair(average)
(h)
—
3
2
—
1
1
2
2
—
* No critical failure reported
102
Flow transmitterBackground data
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:Value of Alfa:Value of Beta:
97Signal failure
358.E4120.10130200
The method of estimation used is the Weighted aPriori Moment Method (WPM).
Physical boundary of the component
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.
Active repair(average)
(h)
3
3
—
—
2
4
7
3
104
Level sensorBackground data
Number of components:Failure modes:
Number of demands:(per operational time)Number of failures:Values of Alfa:Values of Beta:Method of estimation:
RINGHALS 2
Number of components:Failure modes:
Number of demands:(per operational time)Number of failures:
552Failure tofunction
3890440.001919.24WMM
27Spuriousfunction
89.8 E40
478Spuriousfunction
150O.E4130.064879400.ML
27Other spuriousfaults
89.8 E40
571Other spuriousfaults
1940.E4130.020530600.WPM
Physical boundary of the component
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
*
Other spuriousfaults
(lO^/h)
0.58
0.94
0.45 *
0.50 *
0.48
0.53
0.88
0.67
1.6
*
Active repair(average)
»i»
5
1
—
—
2
2
3
3
—
No critical failure reported
106
Level transmitterBackground data
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:Value of Alfa:Value of Beta:
72Signal failure
289.E4110.18849500.
The method of estimation used is the Weighted aPriori Moment Method (WPM).
Physical boundary of the component
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
Active repair(average)
(h)
2
2
—
—
1
1
4
2
2
j t
108
TemperatureBackground data
Number of componentsFailure modes:
Number of demands:(per operational time)Number of failures:Values of Alfa:Values of Beta:Method of estimation:
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
*
Active repair(average)
<h)
2
1
-
4
1
4
4
3
—
* No critical failure reported
110
Temperature transmitterBackground data
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:Value of Alfa:Value of Beta:
132Signal failure
289.E480.057920900.
The method of estimation used is the Weighted aPriori Moment Method (WPM).
RINGHALS 2
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:
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.
*
Active repair(average)
(h)
1
4
4
2
—
—
3
3
—
* No critical failure reported
112
Electronic limit switchBackground data
Number of components:Failure modes:
Number of demands:(per operational time)Number of failures:Values of Alfa:Values of Beta:Method of estimation:
249Failure tooperate
125500——
249Spuriousoperation
816. E470.048162700.ML
Physical boundary of the component
Transmitter
Indicating instrument
.H1.L1.L2Electroniclimit switch
113
Electronic limit switch
No critical failure reported
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
Active repair(average)
(h)
—
—
—
—
1
1
4
2
114
Electronic indicating instruments
Background data
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:Value of Alfa:Value of Beta:
280Faulty measurement
1040.E480.031541100.
The method of estimation used is the Weighted aPriori Moment Method (WPM).
Physical boundary of the component
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
Active repair(average)
(h)
1
2
—
—
2
1
3
2
No critical failures reported
116
Diesel generator
Background data
Number of components:Failure modes:
Number of demands:(per operational time)Number of failures:Values of Alfa:Values of Beta:Method of estimation:
RINGHALS 2
Number of components:Failure modes:
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_
Physical boundary of the component
24 V
I110V
>1r
Logic and '. J Controlautomation Equipmentfor compon.
SwitchgearEquipment
Fuel
Compressed air
Coolant water
LubricantGeneratorBreaker
117
Diesel generator
Operational mode: standby
No critical failure reported
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.
*
Active repair(average)
(h)
12
27
24
11
28
10
25
20
8
118
BatteryBackground data
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:Value of Alfa:Value of Beta:
129Failed effective output
53170.03462.59
The method of estimation used is the Weighted aPriori Moment Method (WPM).
RINGHALS 2
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:
12Failed effective output
600
Physical boundary of the component
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.
*
Active repair(average)
(h)
—
No data
2
—
—
—
—
2
—
* No critical failures reported
120
RectifierBackground data
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:Value of Alfa:Value of Beta:
140Loss of effective output
427.E460.032423000.
The method of estimation used is the Weighted aPriori Moment Method (WPM).
Physical boundary of the component
380 V
Batteries
[]
Battery powered bar
Rectifier
121
Table 42
Power plant Loss of effectiveoutput
Active repair(average)
(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
* No critical failure reported
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.
The method of estimation used is the Weighted aPriori Moment Method (WPM).
RINGHALS 2
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:
Loss of effective output
17.29 E42
The method of estimation used is the Weighted aPriori Moment Method (WPM).
Physical boundary of the component
Aux supply Battery bar
rReversing switch
Inverter incl reversing switch
"1Alarm
..J
Inverter
123
Table 43
Power plant Loss of effectiveoutput
(lO^/h)
Active repair(average)
(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
* No critical failures reported
124
Rotating converterBackground data
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:Value of Alfa:Value of Beta:
42Loss of
147. E4310.71133700.
The method of estimation used is the Weighted aPriori Moment Method (WPM).
Physical boundary of the component
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.
Active repair(average)
<h)
15
11
—
24
16
14
13
14
* No critical failures reported
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.
The method of estimation used is the Weighted aPriori Moment Method (WPM).
Physical boundary of the component
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)
Active repair(average)
(h)
All BWR plants
Mean value
95%
3.5
18.
38
128
Start- and Auxiliary transformer130/6kV, 70/6kV, 20/6kVBackground data
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:Value of Alfa:Value of Beta:
17Interruption
51.2 E410.10151800.
The method of estimation used is the Weighted aPriori Moment Method (WPM).
Physical boundary of the component
Value beeing fromVoltage regulator
110V DC
rRelayprotection
SupervisionProtectionMonitors
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
Power plant Interruption
All BVYR plants
Mean value
95%
2.0
11.
Active repair(average)
(h)
130
Transformer U<6kV
Background data
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:Value of Alfa:Value of Beta:
129Interruption
379.E430.034543600.
The method of estimation used is the Weighted aPriori Moment Method (WPM).
Physical boundary of the component
110V DC
rRelayprotection
SupervisionProtectionMonitors
Value beeing fromVoltage regulator
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
No critical failure reported
(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
Physical boundary of the component
r< • < • < •
Measurement
110V
X Output breaker
I
133
Table 48Bus bar U > 20 kV
Power plant Interruption Shortcircuit
(K)"6/!!) (lO^/h)
Groundcontact
Active repair(average)
(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
Number of components:Failure modes:Number of demands:(per operational time)Number of failures:
Short circuit Ground contact
17.3 E40
17.3 E40
Physical boundary of the component
r
Measurement
_l110V
X Output breaker
135
Table 49
Busbar6kV<U<20kV
Power plant Interruption
(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)
*
*
Active repair(average)
(h)
—
—
—
—
—
—
-
—
No critical failure reported
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
Number of components:Failure modes:Number of demands:(per operational time)Number of failures:
22Short circuit
95.0 E40
22Ground contact
95.0 E40
Physical boundary of the component
r
Measurement
_l110V
X Output breaker
137
Table 50
Bus bar U < 500 V
Power plant Interruption
(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)
*
*
Active repair(average)
(h)
—
—
—
12
3
—
—
8
—
* No critical failure reported
138
Generator breaker U= 20 kV
Background data
Number of components:Failure mode:Number of demands:(per operational time)Number of failures:Value of Alfa:Value of Beta:Method of estimation:
8Failure to open
29530.70065.0ML
8Spurious opening
19.4 E40——
Physical boundary of the component
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)
Active repair(average)
(h)
All BWR plants
Mean value 11.
95% 36.
No critical failure reported
15
140
Breaker 6kV<U<10kVBackground data
Number of components:Failure modes:
Number of demands:(per operational time)Number of failures:Values of Alfa:Values of Beta:Method of estimation:
278Failure tochangeposition
176030.020812.2WPM
278Spurious changeof position
932. E430.014545200.WPM
Physical boundary of the component
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%
Failure tochange position
(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
Active repair(average)
(h)
—
—
—
12
6
3
2
6
* No critical failure reported
142
Breaker U<660VBackground data
Number of components:Failure modes:
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
Physical boundary of the component
Auto signalsSynchronizingRelay protectionCircuit switchingunit
Manual order
LogicControlEquipment
Switchyard
Grounding
Grounding interlocks
Interlocks 24 V 110 V 220 V
143
* No critical failure reported
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
Failure tochange position
(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
—
Active repair(average)
(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.
The method of estimation used is the Weighted aPriori Moment Method (WPM).
Physical boundary of the component
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.
Active repair(average)
<h)
—
—
32
25
—
—
—
28