ML19183A309

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Hazard Modeling
ML19183A309
Person / Time
Issue date: 07/02/2019
From:
Office of Nuclear Regulatory Research
To:
K. Hamburger 415-2022
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ML19183A307 List:
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Download: ML19183A309 (31)
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Public Meeting

-July 24, 2019 High Energy Arcing Faults (HEAF) Hazard ModelingGabriel Taylor P.E.Office of Nuclear Regulatory ResearchDivision of Risk Analysis July 24, 2019 Public Meeting

-July 24, 2019 *Provide overview of modeling

-History-Types-Existing models

-Comparisons to measurementPurpose Public Meeting

-July 24, 2019 Categories of Electrical EnclosureFailure Mode

-Review Public Meeting

-July 24, 2019 *Highlighted HEAF hazard

-July 24, 2019 *NUREG/CR 6850 forms the basis for nuclear power plant (NPP) Fire PRA's

-Published 2005

  • This EPRI/NRC working group was the first to explicitly model HEAF events as part of a fire PRA-The need was identified as part of accident investigation efforts for the development of 6850 & NRC's assessment of energetic faults from 1986-2001 *(ADAMS Accession No. ML021290364

)-Timely OpE-San Onofre2/3/2001Fire PRA MethodologyNUREG/CR-6850 EPRI 1011989https://www.nrc.gov/readin g-rm/doc-collections/nuregs/contract/cr6850/

Public Meeting

-July 24, 2019 *NUREG/CR-6850, Appendix M (2005)

  • Zone of Influence (ZOI) Method largely based on one well documented fire event at San Onofrein 2001*Methodology developed as an expert elicitation

-Observational data and OpEinformation only

-No test data available

-Currently this model has been used to support NFPA 805 transitions Current MethodologyElectrical Enclosures 6

Public Meeting

-July 24, 2019 HEAF OpEElectrical EnclosureSONGS, 2001San Onofre; 2001Onagawa; 2011 Public Meeting

-July 24, 2019 Current MethodologyBus Ducts*NUREG/CR-6850, Supplement 1

  • Bus duct guidance for high energy arcing faults (FAQ 07-0035) *Methodology developed as an expert elicitation

-Observational data and OpEinformation only

-No test data available

-Currently this model has been used to support NFPA 805 transitions Public Meeting

-July 24, 2019 HEAF OpEBus DuctColumbia Bus Duct (OpE)2009Diablo Canyon Bus Duct (OpE)2000Bus Duct Testing 2016 Public Meeting

-July 24, 2019 Conceptual Modeling Approaches Public Meeting

-July 24, 2019 *Bounding (Current models)

  • Enclosure, bus ducts
  • Bounding by Categories
  • By power, energy, voltage, fault current, protection scheme, material, safety class
  • Dynamic ZOI
  • Scenario dependent source
  • Target fragilityModeling Approach 11As presented at 4/18/2018 public workshop Public Meeting

-July 24, 2019 *Assumes worst case damage for all HEAF

-i.e., one size fits all

-Damage and ignition of components within ZOI

-Peak HRR*Least amount of information needed to determine ZOI

  • Least realistic for majority of cases
  • Simple to apply*Lowest costBounding ZOI(Current Model) 12As presented at 4/18/2018 public workshop Public Meeting

-July 24, 2019 *Subdivides equipment by HEAF damaged potential-Equipment type

-Energy/Power potential

-Protection scheme

-Size, Material, Design, etc.

  • More realistic
  • Requires more information to apply
  • More costly for development and applicationRefined Bounding ZOI 13As presented at 4/18/2018 public workshop Public Meeting

-July 24, 2019 *Requires detailed information on power system*Correlation from experiments and theory to model source term and incident flux as a function of distance

  • Requires knowledge of fire PRA target fragility to high heat flux short duration.
  • Potential to provide most realistic results
  • Complex*Most costlyDynamic ZOI 14As presented at 4/18/2018 public workshop Public Meeting

-July 24, 2019 *No approach has been excluded

  • Understand and evaluation existing and new hazard models
  • Needs to consider development and application efficiencies along with level of realism in a holistically manner to make informed decision on appraoch*NRC/EPRI working group advancing "PRA modeling" methodologyModeling ApproachStatus Public Meeting

-July 24, 2019 Overview of Existing Models Public Meeting

-July 24, 2019 *Simple geometric configuration

-arc modeled as sphere

  • Heat transfer to predict distance where threshold is exceeded*Used available research on human skin / clothing fragility (Stoll / Artz)*Conservative due to maximum arc power assumption

-2002 for > 15kV applicationsTheoreticalLee ModelR. Lee, The Other Electrical Hazard: Electric Arc Blast Burns, 1982 Public Meeting

-July 24, 2019 *Output-IE, incident energy (J/cm 2)*Inputs-V, system voltage (kV)

-t, arcing time (seconds)

-I bf, 3 phase bolted fault current

-D, distance from arc pointTheoreticalLee's MethodASTM slug T-cap. slugKEMA DaqPhysical MeasurementR. Lee, The Other Electrical Hazard: Electric Arc Blast Burns, 1982 Public Meeting

-July 24, 2019 Semi-Empirical Wilkins-Allison-Lang Method

  • Output-IE, incident energy
  • Input-V LL, line-line voltage

-V, system voltage

-Varc, arc voltage

-Iarc, arc current

-t, arcing time

-D, distance from arc point

-a, enclosure dimension

-g, gap-Ve, electrode voltageASTM slug T-cap. slugKEMA DaqPhysical MeasurementLiteratureR. Wilkins, M. Allison, M. Lang, Improved Method for Arc Flash Hazard Analysis, 2004 Public Meeting

-July 24, 2019 Semi-empiricalGammon SimplifiedT. Gammon, J. Matthews, The IEEE 1584

-2002 Arc Modeling Debate and Simple Incident Energy Equations for Low-Voltage Systems, 2006*Output-IE, incident energy

  • Input-MVAsc, short-circuit MVA

-t, arcing time

-D, distance from arc point

-X, configuration factor (IEEE)

-IEratio UB, Incident energy rate ratio upper bound (configuration based 0.758

-2.098)ASTM slug T-cap. slugKEMA DaqPhysical MeasurementLiterature Public Meeting

-July 24, 2019 *Output-E MA ,E MB, Max. Incident Energy

  • Input-F, 3-phase short

-circuit current

-t A , t B, arc duration

-D A ,D B, distanceEmpirical

-StatisticalDoughty -Neal -FloydASTM slug T-cap. slugKEMA DaqPhysical MeasurementR. Doughty, T. Neal, H Floyd, Predicting Incident Energy to Better Manage the Electric Arc Hazard on 600

-V Power Distribution System, 2000 Public Meeting

-July 24, 2019 *Guide for performing arc flashcalculations

  • Model for incident energy calculations
  • Empirically derived model from 300 tests
  • Methodology focused on personal protection

-Arc flash boundary is only applicable to human fragility-Arc fault current and incident energy are independent of targetEmpirical

-StatisticalIEEE 1584

-2002IEEE 1584-2002, Guide for Performing Arc

-Flash Hazard Calculation, 2002 Public Meeting

-July 24, 2019 Empirical

-StatisticalIEEE 1584

-2002*Output-IE, Incident Energy

  • Input-V, system voltage

-I a, arc current

-t, arc duration

-G, conductor gap

-D, distance

-x, distance exponent

-Configuration (open / box)ASTM slug T-cap. slugKEMA DaqPhysical MeasurementLiteratureIEEE 1584-2002, Guide for Performing Arc

-Flash Hazard Calculation, 2002 Public Meeting

-July 24, 2019 *Guide for performing arc flashcalculations

  • Significantly changed from 2002 edition
  • Model for incident energy calculations
  • Empirically derived model from 2,160 tests
  • Five configurations

-VCB, VCBB, HCB, VOA, HOAEmpirical

-StatisticalIEEE 1584

-2018IEEE 1584-2018, Guide for Performing Arc

-Flash Hazard Calculation, 2018 Public Meeting

-July 24, 2019 *System voltage: 208 to 15,000 Volts

  • Frequency: 50 or 60 Hz
  • Bolted fault current:

-Low Voltage: 500 to 106,000 A

-Med Voltage: 200 to 65,000 A

  • Conductor Gaps:

-Low Voltage: 0.25 to 3 inches

-Med Voltage: 0.75 to 10 inches

-2018Range of model Public Meeting

-July 24, 2019 *Output-IE, Incident Energy

  • Input-I bf, Bolted fault current

-V oc, System voltage

-T, Duration

-D, Distance

-G, Conductor gap

-Enclosure Dimensions

-Equip ConfigurationEmpirical

-StatisticalIEEE 1584-2018ASTM slug T-cap. slugKEMA DaqPhysical MeasurementLiterature Public Meeting

-July 24, 2019 *ASTM slug calorimeter (copper)

-Model overpredict max measured incident energy*Maximum overprediction : ~11x

-550 kJ/m 2measured vs. 6,100 kJ/m 2calculated

  • Minimum overprediction : ~2x

-3.4MJ/m 2measured vs. 6.3MJ/m 2-Note: 2 instruments damaged due to HEAF damagelikely higher heat flux at damaged sensors and better agreement with modelModel ComparisonIEEE 1584

-2018 vs MV Alum Public Meeting

-July 24, 2019 *ASTM slug calorimeter (copper)

-Model overpredict max measured incident energy*Maximum overprediction : ~17x

-550 kJ/m 2measured vs. 9,100 kJ/m 2calculated

  • Minimum overprediction : ~3x

-3.4MJ/m 2measured vs. 9.4MJ/m 2calculated

-Note: 2 instruments damaged due to HEAF damagelikely higher heat flux at damaged sensors and better agreement with modelModel ComparisonLEE vs MV Alum Public Meeting

-July 24, 2019 *T-cap slug calorimeter (tungsten)

-Model overpredict max measured incident energy*Maximum overprediction : ~26x

-236 kJ/m 2measured vs. 6,100 kJ/m 2calculated

  • Minimum overprediction : agreement

-6.0MJ/m 2measured vs. 6.3MJ/m 2Model ComparisonIEEE 1584

-2018 vs MV Alum Public Meeting

-July 24, 2019 *T-cap slug calorimeter (tungsten)

-Model overpredict max measured incident energy*Maximum overprediction : ~39x

-236 kJ/m 2measured vs. 9,100 kJ/m 2calculated

  • Minimum overprediction : ~1.6x

-6.0MJ/m 2measured vs. 9.4MJ/m 2Model ComparisonLEE vs MV Alum Public Meeting

-July 24, 2019 *Follow similar form

-Inverse power relationship with distance to target

  • Supporting test configurations not directly applicable

-Open air or box w/opening

  • Fragility different (human vs equipment)
  • Existing models may be adapted to make representative and realistic.

Wrap-upExisting Models

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