ML19212A730
| ML19212A730 | |
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|---|---|
| Issue date: | 07/31/2019 |
| From: | Office of Nuclear Regulatory Research |
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| D. Stroup 415-1649 | |
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NRC-RES Fire PRA WorkshopModule IVAugust 5-9, 2019Rockville, MD NRC-RES/EPRI FIRE PRA METHODOLOGYTask 12 -Fire HRA Scoping Quantification Approach Fire HRA -Scoping MethodSlide 2Fire PRA Workshop 2019, Rockville, MDCourse Overview 1.Introduction to HRA 2.Overview of the EPRI/NRC Fire HRA Guidelines 3.Identification and definition of fire human failure events 4.Qualitative analysis 5.Fire HRA Application Experience 6.Quantitative analysis a)Screening b)Scoping c)Detailed EPRI approach & ATHEANA (detailed) 7.Recovery analysis 8.Dependency analysis 9.Uncertainty analysis Fire HRA -Scoping MethodSlide 3Fire PRA Workshop 2019, Rockville, MDThree General Approaches to HRA Quantification Screening: Slightly modified from NUREG/CR
-6850 (EPRI 1011989) to cover late (after fire is out) eventsScoping fire HRA quantification approach (new)
-Less conservative than screening, but designed to be slightly more conservative than detailed approaches
-Some actions may result in an HEP of 1.0Two detailed fire HRA quantification approaches, modified for application in fire scenarios
-EPRI Cause
-Based Decision Tree Method (CBDTM) & HCR/ORE; THERP
-ATHEANA Fire HRA -Scoping MethodSlide 4Fire PRA Workshop 2019, Rockville, MDPurpose of Scoping ApproachProvides less conservative but more realistic HEPs for HFEs surviving screening
-Straightforward approach
-HEPs generally more conservative than those obtained with more detailed analysis
-Limits need for detailed analysis for many HEPsRelies on feasibility assessment and time margin to account for many of the uncertainties associated with fire scenarios (e.g., per NUREG
-1852)Requires simple judgments about PSFs Fire HRA -Scoping MethodSlide 5Fire PRA Workshop 2019, Rockville, MDCategories of Actions Addressed in Scoping Flowcharts New and existing main control room (MCR) actionsNew and existing local (ex
-control room) actionsActions associated with using alternate shutdown means -due to MCR habitability issues, or
-due to difficulties in controlling the plant from the MCR because of the effects of the fire Recovery of Errors of Commission (EOCs) or Errors of Omission (EOOs) due to spurious instrumentation
-Supports addressing spurious instrument effects as described in Part 4 (Internal Fires) of ASME/ANS Combined PRA Standard (HLR
-ES-C1 and C2)
Fire HRA -Scoping MethodSlide 6Fire PRA Workshop 2019, Rockville, MDCategories of Actions NOT Addressed in Scoping Flowcharts Complex diagnosis should notbe addressed with the Scoping Method
-Simplified approach not appropriate for cognitively complex or challenging scenariosExample of cognitively complex or challenging scenarios:
-Cues directly relevant to the action being modeled do not match the procedural guidance
-Plants that implement SISBO procedures
-Actions pertaining to deciding to abandon the MCR*
-Scenarios that may include potentially distracting spurious operations*scoping approach may be used to quantify HFEs subsequent to the decision to abandon.
Fire HRA -Scoping MethodSlide 7Fire PRA Workshop 2019, Rockville, MDSteps for Using Scoping Fire HRA Approach 1.Ensure minimum criteria are met 2.Assess feasibility of operator actions 3.Calculate time margin 4.Assess key conditions and PSFs 5.Use flowcharts to quantify 6.Selection scheme directs to one of the following:INCR = In MCR actionsEXCR = ex-MCR actions (actions normally performed locally)ASD = Alternative Shutdown (including MCR Abandonment due to habitability or transferring command and control to outside the MCR due to an inability to control the plant) SPI = recovery of errors due to spurious instrumentation Fire HRA -Scoping MethodSlide 8Fire PRA Workshop 2019, Rockville, MDMinimum Criteria 1.Procedures
-Should match the scenario
-Should cover each operator action being modeled
-Support both diagnosis & execution of the action
-Exceptions:Execution of skill
-of-the-craft actionsRecovery of EOO or EOC in some cases related to self
-or crew-recovery for inappropriate response to spurious indications 2.Training -on the procedures and the actions 3.Availability and accessibility of equipment Fire HRA -Scoping MethodSlide 9Fire PRA Workshop 2019, Rockville, MDAssessment of Feasibility in Scoping HRA Examines information regarding the action, context, scenario and timingPrimarily based on action/scenario timing and environmental conditions (dense smoke)Refer to Qualitative Analysis presentation sections on Tools for Feasibility Assessment and conducting Talk
-and Walk-throughs, as well as NUREG
-1921 sections:
-4.3 Feasibility Assessment
-4.11 Reviews with Plant Operations Fire HRA -Scoping MethodSlide 10Fire PRA Workshop 2019, Rockville, MDFeasibility Assessment FactorsSufficient time*
-Timeline used to model operator performance
-Sources of timing information (e.g., job performance measures [JPMs], training exercises, Appendix R feasibility demonstrations)Sufficient manpower (both inside and outside control room) Primary cues available/sufficient (e.g., is there a fire impact?)Proceduralizedand trained (plus certain skill-of-the-craftactions)*See NUREG
-1921, Sections 4.3.4.1 Sufficient Time & 4.6.2 PSFs
-Timing Fire HRA -Scoping MethodSlide 11Fire PRA Workshop 2019, Rockville, MDFeasibility Assessment Factors (cont'd)Proceduralized and trained
-Plus certain skill-of-the-craftactionsAccessible location (both travel path and action location; effects of environmental and security measures must be considered)Equipment and tools available and accessible, e.g.,-Keys for locked doors
-Radios, ladders, flashlights, protective clothing, SCBA Fire HRA -Scoping MethodSlide 12Fire PRA Workshop 2019, Rockville, MDTime Margin Extra time included to account for potential fire effects and variabilities, such as:
-Uncertainties from conditions unable to be simulated in training-Potential variability in crew response times and individual differences
-Variations in fire type and related plant conditionsWithin the scoping approach, time margins are required to be calculated for all actions or set of actionsTime estimates should be as realistic as possible
-Look for "tipping points" meaning situations where time available ~ time to respondSimilar to guidance in NUREG
-1852 Fire HRA -Scoping MethodSlide 13Fire PRA Workshop 2019, Rockville, MDCalculation of Time Margin T sw T avail T exe T delay T cog Start Cue received Action complete Action no longer beneficial T 0 T reqd Crew diagnosis complete Fire HRA -Scoping MethodSlide 14Fire PRA Workshop 2019, Rockville, MDCalculation of Time Margin (continued)Some actions may involve either (or a mix of both) serial and parallel actions, with overlapping tasks
-In these cases, determination of the time margin may not be as straightforward as illustrated
-For more guidance, see Appendix A of NUREG
-1852."Tipping Points"
-a few additional minutes of estimated time results in different HEP in scoping method
-Range of times should be collected, not just a point estimate
-Initially choose conservative time estimate and refine later if HEP significantly impacts fire PRA model quantification results Fire HRA -Scoping MethodSlide 15Fire PRA Workshop 2019, Rockville, MDAssessing Key Conditions & PSFs within the Scoping Flowcharts
- Procedures (criteria for using Scoping)
-Should match the scenario
-Should be relatively easy to follow given the pattern of indications
-Serves as a proxy for diagnostic complexity
- Response action execution complexity
-Assessed as high or low
-Complexity is usually considered lowif:Requires a single stepPerformed by a single crew memberMultiple simple steps performed by single crew members working independentlyClear procedures or skill
-of-craft -Complexity is usually considered highif:Multiple steps that may be ambiguous or difficultMultiple crew members performing coordinated stepsMultiple location steps if coordination/communication requiredMultiple functions (e.g., both electrical and mechanical alignment)
Fire HRA -Scoping MethodSlide 16Fire PRA Workshop 2019, Rockville, MDTiming of cues for the action relative to expected fire suppression time.
-If fire type unknown, fire suppression assumed to be 70
-minutes ("all fires")
-If fire type is known, may use the 99 th%ilevalue (yellow) from FAQ 08
-0050 (NUREG 6850 supplement 1, or NUREG
-2169)-Fire must be considered on
-going for the fire types in redAssessing Key Conditions & PSFs within the Scoping Flowcharts (continued)Time (min)T/G firesHigh energy arcing faultsOutdoor transformersFlammable gasOil firesElectrical firesTransient firesPWR containm entWeldingControl RoomCable firesAll Fires 01.01.01.01.01.01.01.01.01.01.01.01.0 50.8830.9470.8360.8810.6840.6020.5310.6870.3920.1890.4460.714 100.7800.8970.6980.7760.4680.3620.2820.4720.1530.0360.1990.510 150.6890.8500.5840.6830.3200.2180.1500.3250.0600.0070.0890.364 200.6090.8050.4880.6020.2190.1310.0800.2230.0240.0010.0400.260 250.5380.7620.4080.5300.1500.0790.0420.1530.009*0.0180.186 300.4750.7220.3410.4670.1020.0480.0230.1050.004*0.0080.133 350.4190.6840.2850.4110.0700.0290.0120.0720.001*0.0040.095 400.3700.6470.2380.3620.0480.0170.0060.050**0.0020.068 450.3270.6130.1990.3190.0330.0100.0030.034***0.048 500.2890.5810.1660.2810.0220.0060.0020.024***0.035 550.2550.5500.1390.2480.0150.004*0.016***0.025 600.2260.5210.1160.2180.0100.002*0.011***0.018 650.1990.4930.0970.1920.0070.001*0.008***0.013 700.1760.4670.0810.1690.005**0.005***0.009 750.1550.4430.0680.1490.003**0.004***0.006 800.1370.4190.0570.1310.002**0.002***0.005 850.1210.3970.0470.1160.002**0.002***0.003 900.1070.3760.0400.1020.001**0.001***0.002 950.0950.3560.0330.090*******0.002 1000.0840.3370.0280.079*******0.001 Fire HRA -Scoping MethodSlide 17Fire PRA Workshop 2019, Rockville, MDAssessing Key Conditions & PSFs within the Scoping Flowcharts (continued)Action time window
-Time from the occurrence of the cues for action until the action is no longer beneficial
-Short time window = 30 minutes or less
-Long time window = greater than 30 minutesLevel of smoke and other hazardous elements in the action areas
-Need for special equipment (e.g., SCBA)
-Impairment of vision or prevention of the execution of the actionAccessibility
-Location of action
-Travel path Fire HRA -Scoping MethodSlide 18Fire PRA Workshop 2019, Rockville, MDUse of Scoping FlowchartsHFEs quantified based on:
-Assessment of key PSFs
-Location of the actions associated with the HFE
-Condition of relevant instrumentationA Search Schemedirects the analyst to the correct flowchart for quantification:
-In-MCR action (INCR)
-Ex-MCR action (EXCR)
-Alternative Shutdown (ASD)
-Recovery of error due to spurious instrumentation (SPI)Some HFEs quantified within the Search Scheme lead to HEP = 1.0 Fire HRA -Scoping MethodSlide 19Fire PRA Workshop 2019, Rockville, MDSelection SchemeDirects analyst to correct quantification flowchart Fire HRA -Scoping MethodSlide 20Fire PRA Workshop 2019, Rockville, MDSelection SchemeDirect to ASD or SPI tree Cues are not necessary to answer yes to D1, but likely their absence will still result in HEP = 1.0 later on Fire HRA -Scoping MethodSlide 21Fire PRA Workshop 2019, Rockville, MDSelection SchemeDirects analyst to correct quantification flowchart Fire HRA -Scoping MethodSlide 22Fire PRA Workshop 2019, Rockville, MDSelection SchemeDirect to INCR or EXCR Fire HRA -Scoping MethodSlide 23Fire PRA Workshop 2019, Rockville, MD INCR -In-MCR ActionsUsed for the following HFEs:
-New HFEs identified outside the Internal Events PRA, such as for Fire
-Existing HFEs from the Internal Events that survive quantitative screeningAddresses diagnosis and execution of the action in the MCR
-Presumes no challenge to MCR habitability or functionality from fire (see ASD)
Fire HRA -Scoping MethodSlide 24Fire PRA Workshop 2019, Rockville, MDINCRScoping HRA for in MCR Actions Fire HRA -Scoping MethodSlide 25Fire PRA Workshop 2019, Rockville, MDINCRFire Suppressed?
-70 minutes from reactor trip
-Fire specific timing [FAQ 0050]-Challenging fires (e.g., turbine generator fires) assume fire has not been suppressed.
Fire HRA -Scoping MethodSlide 26Fire PRA Workshop 2019, Rockville, MDINCRScoping HRA for in MCR Actions Fire HRA -Scoping MethodSlide 27Fire PRA Workshop 2019, Rockville, MDINCRFire on-goingShort time window (<30 min)
Fire HRA -Scoping MethodSlide 28Fire PRA Workshop 2019, Rockville, MDINCRScoping HRA for in MCR Actions Fire HRA -Scoping MethodSlide 29Fire PRA Workshop 2019, Rockville, MDINCRFire on-goingLong time window (>30 min)
Fire HRA -Scoping MethodSlide 30Fire PRA Workshop 2019, Rockville, MDINCR Look-up TableHEP Lookup TableTime MarginHEPHEP Label A>100%0.005 INCR2 50 -99%0.025 INCR3< 50%1.0 INCR4 B>100%0.025 INCR5 50 -99%0.125 INCR6< 50%1.0 INCR7 C>100%0.001 INCR8 50 -99%0.005 INCR9< 50%1.0 INCR10 D>100%0.005 INCR11 50 -99%0.025 INCR12< 50%1.0 INCR13 E>100%0.05 INCR14 50 -99%0.25 INCR15< 50%1.0 INCR16 F>100%0.1 INCR17 50 -99%0.5 INCR18< 50%1.0 INCR19 G>100%0.2 INCR20< 100%1.0 INCR21 H>100%0.25 INCR22< 100%1.0 INCR23 I>100%0.5 INCR24< 100%1.0 INCR25 J>100%0.01 INCR26 50 -99%0.05 INCR27< 50%1.0 INCR28 K>100%0.02 INCR29 50 -99%0.1 INCR30< 50%1.0 INCR31 L>100%0.04 INCR32 50 -99%0.2 INCR33< 50%1.0 INCR34 M>100%0.05 INCR35 50 -99%0.25 INCR36< 50%1.0 INCR37 N>100%0.1 INCR38 50 -99%0.5 INCR39< 50%1.0 INCR40 O>100%0.2 INCR41< 100%1.0 INCR42Note that some tables (e.g., G) "absorb" the 50
-99% TM into one <100% because multiplying the >100% TM by 5 already causes HEP=1 Fire HRA -Scoping MethodSlide 31Fire PRA Workshop 2019, Rockville, MD EXCR -Ex-MCR ActionsAlso addresses new and existing HFEsAddresses diagnosis and execution of the action(s)-Diagnosis within the MCR
-Execution locally (i.e., ex
-MCR)If action is require both in the MCR and locally, this tree should be used Major differences from INCR tree
-Action location accessibility?
-Presence of dense smoke or other impact to visibility?
Fire HRA -Scoping MethodSlide 32Fire PRA Workshop 2019, Rockville, MDEXCRScoping HRA for ex-MCR Actions Fire HRA -Scoping MethodSlide 33Fire PRA Workshop 2019, Rockville, MDEXCR*Fire Suppressed?
-70 minutes from reactor trip
-Fire specific timing [FAQ-08-0050]-Challenging fires (e.g., turbine generator fires) assume fire has not been suppressed.
Fire HRA -Scoping MethodSlide 34Fire PRA Workshop 2019, Rockville, MDEXCRScoping HRA for ex-MCR Actions Fire HRA -Scoping MethodSlide 35Fire PRA Workshop 2019, Rockville, MDEXCRFire on-goingShort time window (< 30 min)
Fire HRA -Scoping MethodSlide 36Fire PRA Workshop 2019, Rockville, MDEXCRScoping HRA for ex-MCR Actions Fire HRA -Scoping MethodSlide 37Fire PRA Workshop 2019, Rockville, MDEXCRFire on-goingLong time window (> 30 min)
Fire HRA -Scoping MethodSlide 38Fire PRA Workshop 2019, Rockville, MDEXCR Look-up TableHEP Lookup TableTime MarginHEPHEP Label P>100%0.01EXCR6 50 -99%0.05EXCR7< 50%1.0EXCR8 Q>100%0.05EXCR9 50 -99%0.25EXCR10< 50%1.0EXCR11 R>100%0.002EXCR12 50 -99%0.01EXCR13< 50%1.0EXCR14 S>100%0.01EXCR15 50 -99%0.05EXCR16< 50%1.0EXCR17 T>100%0.5EXCR18< 100%1.0EXCR19 U>100%0.1EXCR20 50 -99%0.5EXCR21< 50%1.0EXCR22 V>100%0.2EXCR23< 100%1.0EXCR24 W>100%0.4EXCR25< 100%1.0EXCR26 X>100%0.02EXCR27 50 -99%0.1EXCR28< 50%1.0EXCR29 Y>100%0.04EXCR30 50 -99%0.2EXCR31< 50%1.0EXCR32 Z>100%0.08EXCR33 50 -99%0.4EXCR34< 50%1.0EXCR35 AA>100%0.1EXCR36 50 -99%0.5EXCR37< 50%1.0EXCR38 AB>100%0.2EXCR39< 100%1.0EXCR40 AC>100%0.4EXCR41< 100%1.0EXCR42 Fire HRA -Scoping MethodSlide 39Fire PRA Workshop 2019, Rockville, MDASD -Alternative ShutdownApplication to 2 situations:
-Uninhabitable environment in MCR
-Transfer of command and control to outside the MCR due to an inability to control the plant (loss of MCR functionality)If the crew decides to stay in the MCR (i.e., direct the crew response and perform actions from the MCR to the extent possible), but collect some information or take some actions outside the MCR as necessary to reach safe shutdown (referred to as remote shutdown), actions should be quantified as ex
-MCR actions and the EXCR flowchart should be usedDifferences from INCR tree:
-Instruments supporting cues necessary for diagnosis protected from fire effects?
-Action location accessibility & not in direct fire path?
-Presence of dense smoke or other impact to visibility?
Fire HRA -Scoping MethodSlide 40Fire PRA Workshop 2019, Rockville, MDASDScoping HRA for Alternative Shutdown Actions Fire HRA -Scoping MethodSlide 41Fire PRA Workshop 2019, Rockville, MDASDD41 refers to diagnosisD42 refers to execution Fire HRA -Scoping MethodSlide 42Fire PRA Workshop 2019, Rockville, MDASDScoping HRA for Alternative Shutdown Actions Fire HRA -Scoping MethodSlide 43Fire PRA Workshop 2019, Rockville, MDASDShort time window (< 30 min)
Fire HRA -Scoping MethodSlide 44Fire PRA Workshop 2019, Rockville, MDASDScoping HRA for Alternative Shutdown Actions Fire HRA -Scoping MethodSlide 45Fire PRA Workshop 2019, Rockville, MDASDLong time window (> 30 min)
Fire HRA -Scoping MethodSlide 46Fire PRA Workshop 2019, Rockville, MDASD Look-up TableHEP Lookup TableTime MarginHEP*HEP Label AD>100%0.2ASD9< 100%1.0ASD10 AE>100%0.4ASD11< 100%1.0ASD12 AF>100%0.8ASD13< 100%1.0ASD14 AG>100%0.04ASD15 50 -99%0.2ASD16< 50%1.0ASD17 AH>100%0.08ASD18 50 -99%0.4ASD19< 50%1.0ASD20 AI>100%0.16ASD21 50 -99%0.8ASD22< 50%1.0ASD23 AJ>100%0.2ASD24< 100%1.0ASD25 AK>100%0.4ASD26< 100%1.0ASD27 AL>100%0.8ASD28< 100%1.0ASD29 Fire HRA -Scoping MethodSlide 47Fire PRA Workshop 2019, Rockville, MDSPI -EOC or EOO Due to Spurious InstrumentationAssumes the EOC or EOO has been committed & quantifies the probability that the error would remain uncorrectedAssume an EOC or EOO if:
-Cables are routed through the fire area*
-Instrumentation not required for an Appendix R action, so cannot assume it is protected by fire barrier wrap
-Single affected instrument can lead operator to take action Don't assume an EOC or EOO if:
-Operator is suspicious of the equipment or instrument because it may be "suspect" due to location of fire
-Demonstrated redundancy and diversity *or routing is not known (exclusion approach)
Fire HRA -Scoping MethodSlide 48Fire PRA Workshop 2019, Rockville, MDSPI -Spurious InstrumentationSpurious instrumentation refers to the instrumentation necessary for the operator to diagnose the action (e.g., expected cues from the procedure)Analyst judgment required in cases of partial spurious indication (e.g., 2 out of 4 instruments fail vs. 2 out of 10 instruments fail). In these cases the analyst should consider:
-How do the instruments fail?
-Is it likely to cause the operator to fail to diagnose the problem?
Fire HRA -Scoping MethodSlide 49Fire PRA Workshop 2019, Rockville, MDSPI -Recovery of an EOC or EOORecovery prompted by either:
-Procedural guidance
-Contextual information or subsequent cues in conjunction with existing proceduresRecognition for need to recover may be either through:-Recognition of an error
-Recognition of the need for the functionRecovery possible by:
-Reversal of the action (EOC)
-Use of alternative system (EOC)
-Performance of the necessary action (EOO)
Fire HRA -Scoping MethodSlide 50Fire PRA Workshop 2019, Rockville, MD SPIScoping HRA for EOC or EOO due to spurious instrumentation Fire HRA -Scoping MethodSlide 51Fire PRA Workshop 2019, Rockville, MD SPIInitial questions Fire HRA -Scoping MethodSlide 52Fire PRA Workshop 2019, Rockville, MD SPIScoping HRA for EOC or EOO due to spurious instrumentation Fire HRA -Scoping MethodSlide 53Fire PRA Workshop 2019, Rockville, MD SPIAction completed within the MCR Fire HRA -Scoping MethodSlide 54Fire PRA Workshop 2019, Rockville, MD SPIScoping HRA for EOC or EOO due to spurious instrumentation Fire HRA -Scoping MethodSlide 55Fire PRA Workshop 2019, Rockville, MD SPIAction completed locally (ex
-MCR)
Fire HRA -Scoping MethodSlide 56Fire PRA Workshop 2019, Rockville, MDSPI Look-up Table AM>100%0.25SPI11< 100%1.0SPI12 AN>100%0.5SPI13< 100%1.0SPI14 AO>100%0.05SPI15 50 -99%0.25SPI16< 50%1.0SPI17 AP>100%0.1SPI18 50 -99%0.5SPI19< 50%1.0SPI20 AQ>100%0.2SPI21< 100%1.0SPI22 AR>100%0.25SPI23< 100%1.0SPI24 AS>100%0.5SPI25< 100%1.0SPI26 AT>100%0.1SPI27 50 -99%0.5SPI28< 50%1.0SPI29 AU>100%0.2SPI30< 100%1.0SPI31 AV>100%0.4SPI32< 100%1.0SPI33 AW>100%0.5SPI34< 100%1.0SPI35 AX>100%0.5SPI36< 100%1.0SPI37 Fire HRA -Scoping MethodSlide 57Fire PRA Workshop 2019, Rockville, MDHEP ValuesBase HEP = 1E
-3 (lowestattainable value)Within a flowchart, HEP values are based on:
-Timing of the cue for an action relative to start of fire
-Length of action time window
-Level of execution complexity
-Level of smoke (area of action & travel path)
-Accessibility of action site (area of action & travel path)
Fire HRA -Scoping MethodSlide 58Fire PRA Workshop 2019, Rockville, MDMultipliers Applied to HEPs Within FlowchartHEPs adjusted within a flowchart
-Fire effects ongoing
-significant increase
-Action time window 30 mins-moderate increase
-High execution complexity
-moderate increase
-Increases in smoke level
-slight increase
-Decrease in time margin
-moderate increaseHEPs based in part on amount of time margin (TM) available
-TM <50%-50% < TM < 100%
-TM >100%
Fire HRA -Scoping MethodSlide 59Fire PRA Workshop 2019, Rockville, MDMultipliers Applied to HEPs Across FlowchartsHEP in Base FlowchartAdjustment ValueHEP in Scoping FlowchartINCR 2EXCREXCR 2 ASDINCR for in
-MCR actions;EXCR for ex
-MCR actions 5 SPIChange in PSFScoping Approach MultipliersFire effects ongoing (i.e., < 70 minutes from the start of the fire) 10Action time window
<30 minutes 5High execution complexity 5Increases in smoke level 2Decreases in time margin:from >100% to 50%
-99%from >50% to < 50%
5Set HEP = 1.0 Fire HRA -Scoping MethodSlide 60Fire PRA Workshop 2019, Rockville, MDSummary of Scoping Quantification
- Purpose:*Offers less conservative and more realistic HEPs compared to the screening approach
- More conservative but less resource intensive than more detailed HRA methods
- Categories:
- In-MCR or local (ex
-MCR) actions
- Alternative shutdown
- Recovery of errors due to spurious instrumentation
- Quantification:
- Relies on assessment of feasibility of actions, time margin, and simple judgments about a few PSFs
- Quantification performed through use of flowcharts Fire HRA -Scoping MethodSlide 61Fire PRA Workshop 2019, Rockville, MDConclusions on Scoping AnalysisUseful to address actions for which
-Screening analysis is inadequate
-Additional resources required for detailed analysis may be unwarrantedMore detailed analyses should be pursued when
-Conditions are beyond those addressed by scoping approach
-Resulting HFEs continue to be significant contributors to riskExamples via Handouts Fire HRA -Scoping MethodSlide 62Fire PRA Workshop 2019, Rockville, MD Questions?