Basic Level 1. PSA course for analystsBasic Level 1. PSA course for analysts
Initiating Event AnalysisInitiating Event Analysis
IAEA Training in level 1 PSA and PSA applications
Initiating Event Analysis
Slide 2.
ContentContent
Initiating event selection and groupingNumerical screening of initiating eventsTransients and LOCAsSupport system initiating events
Initiating event selection and groupingInitiating event selection and groupingNumerical screening of initiating eventsNumerical screening of initiating eventsTransients and Transients and LOCAsLOCAsSupport system initiating eventsSupport system initiating events
Initiating Event Analysis
Slide 3.
DEFINITION OF INITIATING EVENTSDEFINITION OF INITIATING EVENTS
Definition:“An initiating event is an event that creates a disturbance in the plant and has a potential to lead to core damage, depending on the successful operation of the various mitigating systems of the plant.” (IAEA Safety Series No. 50-P-4)
Definition:Definition:““An initiating event is an event that creates a disturbance An initiating event is an event that creates a disturbance in the plant and has a potential to lead to core damage, in the plant and has a potential to lead to core damage, depending on the successful operation of the various depending on the successful operation of the various mitigating systems of the plant.mitigating systems of the plant.”” (IAEA Safety Series No. (IAEA Safety Series No. 5050--PP--4)4)
Initiating Event Analysis
Slide 4.
GROUPING OF INITIATING EVENTSGROUPING OF INITIATING EVENTS
Selection of initiating events based on:Scope of the PSA
Operating mode to be modelledFull powerShutdown and low power
Initiating event categoryInternal initiating eventsinternal and external hazards
Selection of initiating events based on:Selection of initiating events based on:Scope of the PSAScope of the PSA
Operating mode to be modelledOperating mode to be modelledFull powerFull powerShutdown and low powerShutdown and low power
Initiating event categoryInitiating event categoryInternal initiating eventsInternal initiating eventsinternal and external hazardsinternal and external hazards
Initiating Event Analysis
Slide 5.
GROUPING OF INITIATING EVENTSGROUPING OF INITIATING EVENTS
Selection methodsEngineering evaluationReference to previous listsDeductive analysisOperational experience
Selection methodsSelection methodsEngineering evaluationEngineering evaluationReference to previous listsReference to previous listsDeductive analysisDeductive analysisOperational experienceOperational experience
Initiating Event Analysis
Slide 6.
GROUPING OF INITIATING EVENTSGROUPING OF INITIATING EVENTS
PLANT RESPONSESUCCESS CRITERIASUPPORT SYSTEMSOPERATOR ACTIONSLEVEL 2 IMPACTS
PLANT RESPONSEPLANT RESPONSESUCCESS CRITERIASUCCESS CRITERIASUPPORT SYSTEMSSUPPORT SYSTEMSOPERATOR ACTIONSOPERATOR ACTIONSLEVEL 2 IMPACTSLEVEL 2 IMPACTS
Initiating Event Analysis
Slide 7.
NUMERICAL SCREENINGNUMERICAL SCREENING
MOST PSAs INCLUDE FAIRLY “STANDARD” SET OF INITIATING EVENTS FROM FRONTLINE SYSTEM FAILURES (TRANSIENTS, LOCAs, ETC.)
NUMERICAL ARGUMENTS TYPICALLY USED TO LIMIT SCOPE OF SUPPORT SYSTEM INITIATING EVENTS AND EXTERNAL INITIATING EVENTS
NUMERICAL CRITERIA ARE OFTEN NOT JUSTIFIED OR ARE NOT CONSISTENT WITH QUANTIFICATION OF OTHER PSA INITIATING EVENTS
MAJOR PROBLEM IN SOME REVIEWS
MOST MOST PSAsPSAs INCLUDE FAIRLY INCLUDE FAIRLY ““STANDARDSTANDARD”” SET OF SET OF INITIATING EVENTS FROM FRONTLINE SYSTEM INITIATING EVENTS FROM FRONTLINE SYSTEM FAILURES (TRANSIENTS, FAILURES (TRANSIENTS, LOCAsLOCAs, ETC.), ETC.)
NUMERICAL ARGUMENTS TYPICALLY USED TO LIMIT NUMERICAL ARGUMENTS TYPICALLY USED TO LIMIT SCOPE OF SUPPORT SYSTEM INITIATING EVENTS AND SCOPE OF SUPPORT SYSTEM INITIATING EVENTS AND EXTERNAL INITIATING EVENTSEXTERNAL INITIATING EVENTS
NUMERICAL CRITERIA ARE OFTEN NOT JUSTIFIED OR NUMERICAL CRITERIA ARE OFTEN NOT JUSTIFIED OR ARE NOT CONSISTENT WITH QUANTIFICATION OF ARE NOT CONSISTENT WITH QUANTIFICATION OF OTHER PSA INITIATING EVENTSOTHER PSA INITIATING EVENTS
MAJOR PROBLEM IN SOME REVIEWSMAJOR PROBLEM IN SOME REVIEWS
Initiating Event Analysis
Slide 8.
NUMERICAL SCREENINGNUMERICAL SCREENING
CANNOT BE JUSTIFIED ONLY BY ESTIMATED INITIATING EVENT FREQUENCY
MUST CONSIDER RISK CONSEQUENCESLEVEL 1 MODELS / SUCCESS CRITERIAOPERATOR ACTIONSLEVEL 2 CONSEQUENCES
RISK CONTRIBUTORSHIGH FREQUENCY / LOW CONSEQUENCESMEDIUM FREQUENCY / MEDIUM CONSEQUENCESLOW FREQUENCY / HIGH CONSEQUENCES
CANNOT BE JUSTIFIED ONLY BY ESTIMATED INITIATING CANNOT BE JUSTIFIED ONLY BY ESTIMATED INITIATING EVENT FREQUENCYEVENT FREQUENCY
MUST CONSIDER RISK CONSEQUENCESMUST CONSIDER RISK CONSEQUENCESLEVEL 1 MODELS / SUCCESS CRITERIALEVEL 1 MODELS / SUCCESS CRITERIAOPERATOR ACTIONSOPERATOR ACTIONSLEVEL 2 CONSEQUENCESLEVEL 2 CONSEQUENCES
RISK CONTRIBUTORSRISK CONTRIBUTORSHIGH FREQUENCY / LOW CONSEQUENCESHIGH FREQUENCY / LOW CONSEQUENCESMEDIUM FREQUENCY / MEDIUM CONSEQUENCESMEDIUM FREQUENCY / MEDIUM CONSEQUENCESLOW FREQUENCY / HIGH CONSEQUENCESLOW FREQUENCY / HIGH CONSEQUENCES
Initiating Event Analysis
Slide 9.
NUMERICAL SCREENING NUMERICAL SCREENING LIVING PSALIVING PSA
IMPROVED MODELS AND RESULTSREFINED THERMAL / HYDRAULIC ANALYSESREFINED SUCCESS CRITERIAOPERATOR RECOVERY ACTIONSIMPROVED DATA
SCREENING BASED ON PRELIMINARY MODELS / RESULTS OFTEN NOT VALID FOR FINAL MODELS / RESULTS
MUST CONSISTENTLY REEVALUATE SCREENING CRITERIA AFTER EVERY PSA UPDATE
IMPROVED MODELS AND RESULTSIMPROVED MODELS AND RESULTSREFINED THERMAL / HYDRAULIC ANALYSESREFINED THERMAL / HYDRAULIC ANALYSESREFINED SUCCESS CRITERIAREFINED SUCCESS CRITERIAOPERATOR RECOVERY ACTIONSOPERATOR RECOVERY ACTIONSIMPROVED DATAIMPROVED DATA
SCREENING BASED ON PRELIMINARY MODELS / SCREENING BASED ON PRELIMINARY MODELS / RESULTS OFTEN NOT VALID FOR FINAL MODELS / RESULTS OFTEN NOT VALID FOR FINAL MODELS / RESULTSRESULTS
MUST CONSISTENTLY REEVALUATE SCREENING MUST CONSISTENTLY REEVALUATE SCREENING CRITERIA AFTER EVERY PSA UPDATECRITERIA AFTER EVERY PSA UPDATE
Initiating Event Analysis
Slide 10.
NUMERICAL SCREENINGNUMERICAL SCREENING
** GENERAL RULE **
QUANTIFY THE INITIATING EVENT
LET THE PSA MODELS CONFIRM ITS ACTUAL SIGNIFICANCE
** GENERAL RULE **** GENERAL RULE **
QUANTIFY THE INITIATING EVENTQUANTIFY THE INITIATING EVENT
LET THE PSA MODELS CONFIRM ITS ACTUAL LET THE PSA MODELS CONFIRM ITS ACTUAL SIGNIFICANCESIGNIFICANCE
Initiating Event Analysis
Slide 11.
CONSEQUENTIAL IMPACTSCONSEQUENTIAL IMPACTS
INITIATING EVENT STARTS SERIES OF POSSIBLE RESPONSES
EQUIPMENT SUCCESSES / FAILURESOPERATOR ACTIONS
DO NOT COMBINE INITIATOR AND CONSEQUENCES
THE FOLLOWING CONSEQUENTIAL CONDITIONS ARE NOT INITIATING EVENTS
STATION BLACKOUTATWSOVERCOOLING
INITIATING EVENT STARTS SERIES OF POSSIBLE INITIATING EVENT STARTS SERIES OF POSSIBLE RESPONSESRESPONSES
EQUIPMENT SUCCESSES / FAILURESEQUIPMENT SUCCESSES / FAILURESOPERATOR ACTIONSOPERATOR ACTIONS
DO NOT COMBINE INITIATOR AND CONSEQUENCESDO NOT COMBINE INITIATOR AND CONSEQUENCES
THE FOLLOWING CONSEQUENTIAL CONDITIONS ARE THE FOLLOWING CONSEQUENTIAL CONDITIONS ARE NOT INITIATING EVENTSNOT INITIATING EVENTS
STATION BLACKOUTSTATION BLACKOUTATWSATWSOVERCOOLINGOVERCOOLING
Initiating Event Analysis
Slide 12.
TRANSIENTS AND LOCASTRANSIENTS AND LOCAS
TOO MUCH EMPHASIS ON LOCASSIZE, LOCATION, FREQUENCYCOMPLEX SUCCESS CRITERIA
TOO LITTLE EMPHASIS ON TRANSIENTSBROAD INITIATING EVENT GROUPSTREATMENT OF TRANSIENT-INDUCED IMPACTSSCOPE OF SUPPORT SYSTEM INITIATING EVENTS
FULL-SCOPE LEVEL 1 PSA RESULTS TYPICALLY DOMINATED BY TRANSIENTS AND SUPPORT SYSTEM FAILURES
TOO MUCH EMPHASIS ON LOCASTOO MUCH EMPHASIS ON LOCASSIZE, LOCATION, FREQUENCYSIZE, LOCATION, FREQUENCYCOMPLEX SUCCESS CRITERIACOMPLEX SUCCESS CRITERIA
TOO LITTLE EMPHASIS ON TRANSIENTSTOO LITTLE EMPHASIS ON TRANSIENTSBROAD INITIATING EVENT GROUPSBROAD INITIATING EVENT GROUPSTREATMENT OF TRANSIENTTREATMENT OF TRANSIENT--INDUCED IMPACTSINDUCED IMPACTSSCOPE OF SUPPORT SYSTEM INITIATING EVENTSSCOPE OF SUPPORT SYSTEM INITIATING EVENTS
FULLFULL--SCOPE LEVEL 1 PSA RESULTS TYPICALLY SCOPE LEVEL 1 PSA RESULTS TYPICALLY DOMINATED BY TRANSIENTS AND SUPPORT SYSTEM DOMINATED BY TRANSIENTS AND SUPPORT SYSTEM FAILURESFAILURES
Initiating Event Analysis
Slide 13.
TRANSIENTTRANSIENT--INDUCED IMPACTSINDUCED IMPACTS
PRIMARY OVERPRESSURESECONDARY OVERPRESSUREOVERCOOLINGATWSMAKEUP / LETDOWNREACTOR COOLANT PUMP SEAL FAILUREENVIRONMENTAL / PHYSICAL DAMAGECONTAINMENT
PRIMARY OVERPRESSUREPRIMARY OVERPRESSURESECONDARY OVERPRESSURESECONDARY OVERPRESSUREOVERCOOLINGOVERCOOLINGATWSATWSMAKEUP / LETDOWNMAKEUP / LETDOWNREACTOR COOLANT PUMP SEAL FAILUREREACTOR COOLANT PUMP SEAL FAILUREENVIRONMENTAL / PHYSICAL DAMAGEENVIRONMENTAL / PHYSICAL DAMAGECONTAINMENTCONTAINMENT
Initiating Event Analysis
Slide 14.
SUPPORT SYSTEM INITIATING EVENTSSUPPORT SYSTEM INITIATING EVENTS
“PARTIAL” SYSTEM FAILURES
OPERATOR ACTIONS / RECOVERY
OFFSITE POWER
VENTILATION / ROOM COOLING
““PARTIALPARTIAL”” SYSTEM FAILURESSYSTEM FAILURES
OPERATOR ACTIONS / RECOVERYOPERATOR ACTIONS / RECOVERY
OFFSITE POWEROFFSITE POWER
VENTILATION / ROOM COOLINGVENTILATION / ROOM COOLING
Initiating Event Analysis
Slide 15.
SUPPORT SYSTEM INITIATING EVENTSSUPPORT SYSTEM INITIATING EVENTS
GENERIC DATA NOT DIRECTLY RELEVANT
GENERIC EXPERIENCE USEFUL FOR “SANITY CHECK”
DEVELOP PLANT-SPECIFIC MODELS
ACCOUNT FOR OPERATOR ACTIONS
GENERIC DATA NOT DIRECTLY RELEVANTGENERIC DATA NOT DIRECTLY RELEVANT
GENERIC EXPERIENCE USEFUL FOR GENERIC EXPERIENCE USEFUL FOR ““SANITY CHECKSANITY CHECK””
DEVELOP PLANTDEVELOP PLANT--SPECIFIC MODELSSPECIFIC MODELS
ACCOUNT FOR OPERATOR ACTIONSACCOUNT FOR OPERATOR ACTIONS
Initiating Event Analysis
Slide 16.
OPERATOR ACTION DEPENDENCIESOPERATOR ACTION DEPENDENCIES
MUST ACCOUNT FOR DEPENDENCIES WITH OPERATOR ACTIONS IN INITIATING EVENT MODELS
QUANTIFY SEPARATE INITIATING EVENTS
INITIATING EVENT CAUSED BY ONLY HARDWARE FAILURES
NO PRECEDING ERROR DEPENDENCE
INITIATING EVENT CAUSED BY COMBINATION OF HARDWARE FAILURES AND OPERATOR ERRORS
DEPENDENCE ON PRECEDING ERRORSDIFFERENT POST-INITIATOR ERROR RATES
MUST ACCOUNT FOR DEPENDENCIES WITH MUST ACCOUNT FOR DEPENDENCIES WITH OPERATOR ACTIONS IN INITIATING EVENT MODELSOPERATOR ACTIONS IN INITIATING EVENT MODELS
QUANTIFY SEPARATE INITIATING EVENTSQUANTIFY SEPARATE INITIATING EVENTS
INITIATING EVENT CAUSED BY ONLY HARDWARE INITIATING EVENT CAUSED BY ONLY HARDWARE FAILURESFAILURES
NO PRECEDING ERROR DEPENDENCENO PRECEDING ERROR DEPENDENCE
INITIATING EVENT CAUSED BY COMBINATION OF INITIATING EVENT CAUSED BY COMBINATION OF HARDWARE FAILURES AND OPERATOR ERRORSHARDWARE FAILURES AND OPERATOR ERRORS
DEPENDENCE ON PRECEDING ERRORSDEPENDENCE ON PRECEDING ERRORSDIFFERENT POSTDIFFERENT POST--INITIATOR ERROR RATESINITIATOR ERROR RATES
Initiating Event Analysis
Slide 17.
““PARTIALPARTIAL”” SYSTEM FAILURESSYSTEM FAILURES
HIGHER FREQUENCY THAN TOTAL FAILURE
CONDITIONAL CORE DAMAGE FREQUENCY MAY BE HIGH
ACCOUNT FOR ASYMMETRIES IN PLANT DESIGN
HIGHER FREQUENCY THAN TOTAL FAILUREHIGHER FREQUENCY THAN TOTAL FAILURE
CONDITIONAL CORE DAMAGE FREQUENCY MAY BE CONDITIONAL CORE DAMAGE FREQUENCY MAY BE HIGHHIGH
ACCOUNT FOR ASYMMETRIES IN PLANT DESIGNACCOUNT FOR ASYMMETRIES IN PLANT DESIGN
Initiating Event Analysis
Slide 18.
““PARTIALPARTIAL”” SYSTEM FAILURESSYSTEM FAILURES
ONE AC BUS
ONE DC BUS
OFFSITE POWER TRANSFORMERS
ONE TRAIN OF COOLING WATER
ONE TRAIN OF VENTILATION
ONE AC BUSONE AC BUS
ONE DC BUSONE DC BUS
OFFSITE POWER TRANSFORMERSOFFSITE POWER TRANSFORMERS
ONE TRAIN OF COOLING WATERONE TRAIN OF COOLING WATER
ONE TRAIN OF VENTILATIONONE TRAIN OF VENTILATION
Initiating Event Analysis
Slide 19.
ONSITE ELECTRIC POWER FAILURESONSITE ELECTRIC POWER FAILURES
IMPACTS ON PLANT RESPONSE“SAFETY-RELATED” BUSES“NON-SAFETY” BUSES
IMPACTS ON POWER RECOVERYPOWER SUPPLY TO BUSTRANSFORMER FAILUREBUSWORK FAILURE
IMPACTS ON PLANT RESPONSEIMPACTS ON PLANT RESPONSE““SAFETYSAFETY--RELATEDRELATED”” BUSESBUSES““NONNON--SAFETYSAFETY”” BUSESBUSES
IMPACTS ON POWER RECOVERYIMPACTS ON POWER RECOVERYPOWER SUPPLY TO BUSPOWER SUPPLY TO BUSTRANSFORMER FAILURETRANSFORMER FAILUREBUSWORK FAILUREBUSWORK FAILURE
Initiating Event Analysis
Slide 20.
PRECURSOR EVENTSPRECURSOR EVENTS
CONDITIONS THAT REQUIRE RAPID AUTOMATIC OR MANUAL POWER REDUCTION (MORE THAN ~30 % POWER)
AUTOMATIC / MANUAL PLANT RUNBACK
PLANT-SPECIFIC MODEL FOR INITIATING EVENT FREQUENCY
CONDITIONS THAT REQUIRE RAPID AUTOMATIC OR CONDITIONS THAT REQUIRE RAPID AUTOMATIC OR MANUAL POWER REDUCTION (MORE THAN ~30 % MANUAL POWER REDUCTION (MORE THAN ~30 % POWER)POWER)
AUTOMATIC / MANUAL PLANT RUNBACKAUTOMATIC / MANUAL PLANT RUNBACK
PLANTPLANT--SPECIFIC MODEL FOR INITIATING EVENT SPECIFIC MODEL FOR INITIATING EVENT FREQUENCYFREQUENCY
Initiating Event Analysis
Slide 21.
PLANT RUNBACK MODELSPLANT RUNBACK MODELS
SUCCESSFUL RUNBACKPLANT STABILIZED AT REDUCED POWERNO PSA INITIATING EVENT
RUNBACK FAILUREPLANT TRIPPSA INITIATING EVENTMAY BE GROUPED WITH OTHER SIMILAR INITIATORS
SUCCESSFUL RUNBACKSUCCESSFUL RUNBACKPLANT STABILIZED AT REDUCED POWERPLANT STABILIZED AT REDUCED POWERNO PSA INITIATING EVENTNO PSA INITIATING EVENT
RUNBACK FAILURERUNBACK FAILUREPLANT TRIPPLANT TRIPPSA INITIATING EVENTPSA INITIATING EVENTMAY BE GROUPED WITH OTHER SIMILAR INITIATORSMAY BE GROUPED WITH OTHER SIMILAR INITIATORS
Initiating Event Analysis
Slide 22.
PLANT RUNBACK MODELS / DATAPLANT RUNBACK MODELS / DATA
AVOID DETAILED MODELS FOR RUNBACK LOGIC / SIGNALS / CIRCUITS
DERIVE FAILURE RATES FROM OBSERVED EXPERIENCE
RELIABILITY OF RUNBACK FUNCTIONACTUAL EXPERIENCE USUALLY WORSE THAN MODEL PREDICTIONSCATEGORIES OF RUNBACK CHALLENGES
AVOID DETAILED MODELS FOR RUNBACK LOGIC / AVOID DETAILED MODELS FOR RUNBACK LOGIC / SIGNALS / CIRCUITSSIGNALS / CIRCUITS
DERIVE FAILURE RATES FROM OBSERVED DERIVE FAILURE RATES FROM OBSERVED EXPERIENCEEXPERIENCE
RELIABILITY OF RUNBACK FUNCTIONRELIABILITY OF RUNBACK FUNCTIONACTUAL EXPERIENCE USUALLY WORSE THAN ACTUAL EXPERIENCE USUALLY WORSE THAN MODEL PREDICTIONSMODEL PREDICTIONSCATEGORIES OF RUNBACK CHALLENGESCATEGORIES OF RUNBACK CHALLENGES
Initiating Event Analysis
Slide 23.
LOSS OF OFFSITE POWERLOSS OF OFFSITE POWER
OFFSITE POWER RECOVERY CURVE
ELECTRIC POWER RECOVERY TIME WINDOWS
INITIATING EVENT FREQUENCIES
PSA MODEL IMPACTS
OFFSITE POWER RECOVERY CURVEOFFSITE POWER RECOVERY CURVE
ELECTRIC POWER RECOVERY TIME WINDOWSELECTRIC POWER RECOVERY TIME WINDOWS
INITIATING EVENT FREQUENCIESINITIATING EVENT FREQUENCIES
PSA MODEL IMPACTSPSA MODEL IMPACTS
Initiating Event Analysis
Slide 24.
OFFSITE POWER RECOVERY CURVESOFFSITE POWER RECOVERY CURVES
AVOID DETAILED LOGIC MODELS FOR TRANSMISSION LINES, GRID CONNECTIONS, SWITCHYARD
DETAILED MODELS TYPICALLY OPTIMISTIC, COMPARED WITH ACTUAL EXPERIENCE
PLANT-SPECIFIC EXPERIENCE TYPICALLY VERY LIMITED
DERIVE CURVES FROM REGIONAL TRANSMISSION LINE DATA
USE GENERIC EXPERIENCE FOR “SANITY CHECK”
AVOID DETAILED LOGIC MODELS FOR TRANSMISSION AVOID DETAILED LOGIC MODELS FOR TRANSMISSION LINES, GRID CONNECTIONS, SWITCHYARDLINES, GRID CONNECTIONS, SWITCHYARD
DETAILED MODELS TYPICALLY OPTIMISTIC, DETAILED MODELS TYPICALLY OPTIMISTIC, COMPARED WITH ACTUAL EXPERIENCECOMPARED WITH ACTUAL EXPERIENCE
PLANTPLANT--SPECIFIC EXPERIENCE TYPICALLY VERY SPECIFIC EXPERIENCE TYPICALLY VERY LIMITEDLIMITED
DERIVE CURVES FROM REGIONAL TRANSMISSION LINE DERIVE CURVES FROM REGIONAL TRANSMISSION LINE DATADATA
USE GENERIC EXPERIENCE FOR USE GENERIC EXPERIENCE FOR ““SANITY CHECKSANITY CHECK””
Initiating Event Analysis
Slide 25.
OFFSITE POWER RECOVERY CURVESOFFSITE POWER RECOVERY CURVES
SIMPLIFIED MODEL FROM REGIONAL TRANSMISSION LINE DATA
FORCED OUTAGES
OMIT DURATIONS LESS THAN ~1 MINUTE
TRANSMISSION LINE CORRIDORSVOLTAGES AND ROUTING NEAR PLANTCOMMON RIGHT-OF-WAYSIMILAR DIRECTIONAL ROUTING
SIMPLIFIED MODEL FROM REGIONAL TRANSMISSION SIMPLIFIED MODEL FROM REGIONAL TRANSMISSION LINE DATALINE DATA
FORCED OUTAGESFORCED OUTAGES
OMIT DURATIONS LESS THAN ~1 MINUTEOMIT DURATIONS LESS THAN ~1 MINUTE
TRANSMISSION LINE CORRIDORSTRANSMISSION LINE CORRIDORSVOLTAGES AND ROUTING NEAR PLANTVOLTAGES AND ROUTING NEAR PLANTCOMMON RIGHTCOMMON RIGHT--OFOF--WAYWAYSIMILAR DIRECTIONAL ROUTINGSIMILAR DIRECTIONAL ROUTING
Initiating Event Analysis
Slide 26.
OFFSITE POWER RECOVERY CURVESOFFSITE POWER RECOVERY CURVES
MODEL EACH CORRIDOR AS A SINGLE LINE
DERIVE UPPER BOUND CURVE FROM “N”INDEPENDENT CORRIDORS
95TH PERCENTILE RECOVERYCONSERVATIVE IF TRUE INDEPENDENCE APPLIES
DERIVE LOWER BOUND CURVE FROM FULL CORRELATION OF ALL CORRIDORS
5TH PERCENTILE RECOVERYACCOUNTS FOR REGIONAL / GRID IMPACTS
MODEL EACH CORRIDOR AS A SINGLE LINEMODEL EACH CORRIDOR AS A SINGLE LINE
DERIVE UPPER BOUND CURVE FROM DERIVE UPPER BOUND CURVE FROM ““NN””INDEPENDENT CORRIDORSINDEPENDENT CORRIDORS
95TH PERCENTILE RECOVERY95TH PERCENTILE RECOVERYCONSERVATIVE IF TRUE INDEPENDENCE APPLIESCONSERVATIVE IF TRUE INDEPENDENCE APPLIES
DERIVE LOWER BOUND CURVE FROM FULL DERIVE LOWER BOUND CURVE FROM FULL CORRELATION OF ALL CORRIDORSCORRELATION OF ALL CORRIDORS
5TH PERCENTILE RECOVERY5TH PERCENTILE RECOVERYACCOUNTS FOR REGIONAL / GRID IMPACTSACCOUNTS FOR REGIONAL / GRID IMPACTS
Initiating Event Analysis
Slide 27.
OFFSITE POWER RECOVERY CURVESOFFSITE POWER RECOVERY CURVESRecoveryFraction 95th Percentile
Median
5th Percentile
Time
Initiating Event Analysis
Slide 28.
ELECTRIC POWER RECOVERY TIME WINDOWSELECTRIC POWER RECOVERY TIME WINDOWS
DC BATTERY LIFE
PLANT THERMAL / HYDRAULIC RESPONSESTEAM GENERATOR DRYOUTCORE UNCOVERY
PSA SCENARIOS / SUCCESS CRITERIAREACTOR COOLANT PUMP SEAL FAILUREBLEED-AND-FEED COOLINGHIGH PRESSURE / LOW PRESSURE INJECTIONCONTAINMENT COOLING
DC BATTERY LIFEDC BATTERY LIFE
PLANT THERMAL / HYDRAULIC RESPONSEPLANT THERMAL / HYDRAULIC RESPONSESTEAM GENERATOR DRYOUTSTEAM GENERATOR DRYOUTCORE UNCOVERYCORE UNCOVERY
PSA SCENARIOS / SUCCESS CRITERIAPSA SCENARIOS / SUCCESS CRITERIAREACTOR COOLANT PUMP SEAL FAILUREREACTOR COOLANT PUMP SEAL FAILUREBLEEDBLEED--ANDAND--FEED COOLINGFEED COOLINGHIGH PRESSURE / LOW PRESSURE INJECTIONHIGH PRESSURE / LOW PRESSURE INJECTIONCONTAINMENT COOLINGCONTAINMENT COOLING
Initiating Event Analysis
Slide 29.
LOSS OF OFFSITE POWER INITIATING EVENTSLOSS OF OFFSITE POWER INITIATING EVENTS
SUBDIVIDE TOTAL FREQUENCY BY EVENT DURATIONLESS THAN 30 MINUTES30 MINUTES - 1 HOUR1 HOUR - 2 HOURSMORE THAN 2 HOURS
PSA MODEL IMPACTSDIESEL GENERATOR OPERATING MISSION TIMESAVAILABLE SYSTEMSOPERATOR ACTIONS
HOUSE EVENTS IN FAULT TREES
SUBDIVIDE TOTAL FREQUENCY BY EVENT DURATIONSUBDIVIDE TOTAL FREQUENCY BY EVENT DURATIONLESS THAN 30 MINUTESLESS THAN 30 MINUTES30 MINUTES 30 MINUTES -- 1 HOUR1 HOUR1 HOUR 1 HOUR -- 2 HOURS2 HOURSMORE THAN 2 HOURSMORE THAN 2 HOURS
PSA MODEL IMPACTSPSA MODEL IMPACTSDIESEL GENERATOR OPERATING MISSION TIMESDIESEL GENERATOR OPERATING MISSION TIMESAVAILABLE SYSTEMSAVAILABLE SYSTEMSOPERATOR ACTIONSOPERATOR ACTIONS
HOUSE EVENTS IN FAULT TREESHOUSE EVENTS IN FAULT TREES
Initiating Event Analysis
Slide 30.
LOSS OF VENTILATION / ROOM COOLINGLOSS OF VENTILATION / ROOM COOLING
USUALLY MOST IMPORTANT FOR ELECTRICAL / ELECTRONICS EQUIPMENT
SWITCHGEAR ROOMSCONTROL / LOGIC CABINET ROOMSMAIN CONTROL ROOM
MECHANICAL EQUIPMENT IN SMALL ENCLOSED ROOMS
VERY IMPORTANT FOR SOLID-STATE EQUIPMENTENCLOSED CABINETSENCLOSED ROOMS FOR FIRE / FLOODINGUPGRADE / BACKFIT DESIGNS
USUALLY MOST IMPORTANT FOR ELECTRICAL / USUALLY MOST IMPORTANT FOR ELECTRICAL / ELECTRONICS EQUIPMENTELECTRONICS EQUIPMENT
SWITCHGEAR ROOMSSWITCHGEAR ROOMSCONTROL / LOGIC CABINET ROOMSCONTROL / LOGIC CABINET ROOMSMAIN CONTROL ROOMMAIN CONTROL ROOM
MECHANICAL EQUIPMENT IN SMALL ENCLOSED MECHANICAL EQUIPMENT IN SMALL ENCLOSED ROOMSROOMS
VERY IMPORTANT FOR SOLIDVERY IMPORTANT FOR SOLID--STATE EQUIPMENTSTATE EQUIPMENTENCLOSED CABINETSENCLOSED CABINETSENCLOSED ROOMS FOR FIRE / FLOODINGENCLOSED ROOMS FOR FIRE / FLOODINGUPGRADE / BACKFIT DESIGNSUPGRADE / BACKFIT DESIGNS
Initiating Event Analysis
Slide 31.
LOSS OF VENTILATION / ROOM COOLINGLOSS OF VENTILATION / ROOM COOLING
ROOM HEATUP ANALYSES
EQUIPMENT THERMAL FRAGILITY ANALYSES
RECOVERY TIME WINDOWS
RECOVERY SUCCESS CRITERIA
PSA MODEL IMPACTS
ROOM HEATUP ANALYSESROOM HEATUP ANALYSES
EQUIPMENT THERMAL FRAGILITY ANALYSESEQUIPMENT THERMAL FRAGILITY ANALYSES
RECOVERY TIME WINDOWSRECOVERY TIME WINDOWS
RECOVERY SUCCESS CRITERIARECOVERY SUCCESS CRITERIA
PSA MODEL IMPACTSPSA MODEL IMPACTS
Initiating Event Analysis
Slide 32.
ROOM HEATUP ANALYSESROOM HEATUP ANALYSES
REALISTIC ANALYSES OFTEN NOT AVAILABLE
DESIGN-BASIS CALCULATIONSCONSERVATIVE HEAT LOADSASSUMPTIONS ABOUT RECOVERY
PSA MODELS REQUIRE TEMPERATURE VS. TIME AFTER LOSS OF VENTILATION
SIMPLIFIED CALCULATIONS PROVIDE REASONABLE ESTIMATES
ACTUAL TESTS
REALISTIC ANALYSES OFTEN NOT AVAILABLEREALISTIC ANALYSES OFTEN NOT AVAILABLE
DESIGNDESIGN--BASIS CALCULATIONSBASIS CALCULATIONSCONSERVATIVE HEAT LOADSCONSERVATIVE HEAT LOADSASSUMPTIONS ABOUT RECOVERYASSUMPTIONS ABOUT RECOVERY
PSA MODELS REQUIRE TEMPERATURE VS. TIME AFTER PSA MODELS REQUIRE TEMPERATURE VS. TIME AFTER LOSS OF VENTILATIONLOSS OF VENTILATION
SIMPLIFIED CALCULATIONS PROVIDE REASONABLE SIMPLIFIED CALCULATIONS PROVIDE REASONABLE ESTIMATESESTIMATES
ACTUAL TESTSACTUAL TESTS
Initiating Event Analysis
Slide 33.
EQUIPMENT THERMAL FRAGILITY ANALYSESEQUIPMENT THERMAL FRAGILITY ANALYSES
FAILURE LIKELIHOOD AS A FUNCTION OF TEMPERATURE
TYPICALLY NOT AVAILABLE FROM MANUFACTURER
POSSIBLE INFORMATIONQUALIFICATION TEMPERATURERATED OPERATING TEMPERATUREMAXIMUM PERMISSIBLE OPERATING TEMPERATURE
CONSTRUCT FRAGILITY CURVES FROM AVAILABLE INFORMATION
FAILURE LIKELIHOOD AS A FUNCTION OF FAILURE LIKELIHOOD AS A FUNCTION OF TEMPERATURETEMPERATURE
TYPICALLY NOT AVAILABLE FROM MANUFACTURERTYPICALLY NOT AVAILABLE FROM MANUFACTURER
POSSIBLE INFORMATIONPOSSIBLE INFORMATIONQUALIFICATION TEMPERATUREQUALIFICATION TEMPERATURERATED OPERATING TEMPERATURERATED OPERATING TEMPERATUREMAXIMUM PERMISSIBLE OPERATING TEMPERATUREMAXIMUM PERMISSIBLE OPERATING TEMPERATURE
CONSTRUCT FRAGILITY CURVES FROM AVAILABLE CONSTRUCT FRAGILITY CURVES FROM AVAILABLE INFORMATIONINFORMATION
Initiating Event Analysis
Slide 34.
VENTILATION RECOVERY SUCCESS CRITERIAVENTILATION RECOVERY SUCCESS CRITERIA
EXTENSION OF ROOM HEATUP ANALYSES
RECOVERY OPTIONSOPEN DOORSPORTABLE FANSALTERNATE CHILLED WATER / FORCED COOLING
SIMPLE LOCAL ACTIONS MAY NOT BE ADEQUATE IF ALL COOLING IS FAILED FOR THE WHOLE BUILDING
EXTENSION OF ROOM HEATUP ANALYSESEXTENSION OF ROOM HEATUP ANALYSES
RECOVERY OPTIONSRECOVERY OPTIONSOPEN DOORSOPEN DOORSPORTABLE FANSPORTABLE FANSALTERNATE CHILLED WATER / FORCED COOLINGALTERNATE CHILLED WATER / FORCED COOLING
SIMPLE LOCAL ACTIONS MAY NOT BE ADEQUATE IF SIMPLE LOCAL ACTIONS MAY NOT BE ADEQUATE IF ALL COOLING IS FAILED FOR THE WHOLE BUILDINGALL COOLING IS FAILED FOR THE WHOLE BUILDING
Initiating Event Analysis
Slide 35.
VENTILATION RECOVERY TIME WINDOWSVENTILATION RECOVERY TIME WINDOWS
PROBABILITY DISTRIBUTION FOR TIME UNTIL EQUIPMENT FAILURE
ROOM HEATUP CURVESEQUIPMENT THERMAL FRAGILITY CURVES
TIME WINDOWS FOR OPERATOR ACTIONS
SEQUENTIAL IMPACTS AS ROOMS HEAT UPPSA EQUIPMENT0PERATOR ACTION DEPENDENCIES
PROBABILITY DISTRIBUTION FOR TIME UNTIL PROBABILITY DISTRIBUTION FOR TIME UNTIL EQUIPMENT FAILUREEQUIPMENT FAILURE
ROOM HEATUP CURVESROOM HEATUP CURVESEQUIPMENT THERMAL FRAGILITY CURVESEQUIPMENT THERMAL FRAGILITY CURVES
TIME WINDOWS FOR OPERATOR ACTIONSTIME WINDOWS FOR OPERATOR ACTIONS
SEQUENTIAL IMPACTS AS ROOMS HEAT UPSEQUENTIAL IMPACTS AS ROOMS HEAT UPPSA EQUIPMENTPSA EQUIPMENT0PERATOR ACTION DEPENDENCIES0PERATOR ACTION DEPENDENCIES
Initiating Event Analysis
Slide 36.
ReferencesReferences
IAEA-Safety Series 50-P-4 Procedures for Conducting Probabilistic Safety Assessments of Nuclear Power Plants (Level 1)IAEA-TECDOC-719 Defining initiating events for the purposes of probabilistic safety assessmentIAEA-TECDOC-749 Generic initiating events for PSA for WWER reactorsIAEA-TECDOC-1144 Probabilistic safety assessments of nuclear power plants for low power and shutdown modes
IAEAIAEA--Safety Series 50Safety Series 50--PP--4 Procedures for Conducting Probabilistic Safety 4 Procedures for Conducting Probabilistic Safety Assessments of Nuclear Power Plants (Level 1)Assessments of Nuclear Power Plants (Level 1)IAEAIAEA--TECDOCTECDOC--719 Defining initiating events for the purposes of probabilisti719 Defining initiating events for the purposes of probabilistic c safety assessmentsafety assessmentIAEAIAEA--TECDOCTECDOC--749 Generic initiating events for PSA for WWER reactors749 Generic initiating events for PSA for WWER reactorsIAEAIAEA--TECDOCTECDOC--1144 Probabilistic safety assessments of nuclear power plants fo1144 Probabilistic safety assessments of nuclear power plants for r low power and shutdown modeslow power and shutdown modes
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