ML19183A309
| ML19183A309 | |
| Person / Time | |
|---|---|
| Issue date: | 07/02/2019 |
| From: | Office of Nuclear Regulatory Research |
| To: | |
| K. Hamburger 415-2022 | |
| Shared Package | |
| ML19183A307 | List: |
| References | |
| Download: ML19183A309 (31) | |
Text
Public Meeting - July 24, 2019 High Energy Arcing Faults (HEAF)
Hazard Modeling Gabriel Taylor P.E.
Office of Nuclear Regulatory Research Division of Risk Analysis July 24, 2019
Public Meeting - July 24, 2019
- Provide overview of modeling
- History
- Types
- Existing models
- Comparisons to measurement Purpose
Public Meeting - July 24, 2019 Categories of Electrical Enclosure Failure Mode - Review
Public Meeting - July 24, 2019 Highlighted HEAF hazard NRC INFORMATION NOTICE 2002-27 RECENT FIRES AT COMMERCIAL NUCLEAR POWER PLANTS IN THE UNITED STATES https://www.nrc.gov/docs/ML0226/ML022630147.pdf Operating Experience San Onofre Nuclear Generating Station, 2001
Public Meeting - July 24, 2019 NUREG/CR 6850 forms the basis for nuclear power plant (NPP) Fire PRAs
- 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 & NRCs assessment of energetic faults from 1986-2001
- (ADAMS Accession No. ML021290364)
- Timely OpE-San Onofre 2/3/2001 Fire PRA Methodology NUREG/CR-6850 EPRI 1011989 https://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 Onofre in 2001 Methodology developed as an expert elicitation
- Observational data and OpE information only
- No test data available
- Currently this model has been used to support NFPA 805 transitions Current Methodology Electrical Enclosures 6
Public Meeting - July 24, 2019 HEAF OpE Electrical Enclosure SONGS, 2001 San Onofre; 2001 Onagawa; 2011
Public Meeting - July 24, 2019 Current Methodology Bus 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 OpE information only
- No test data available
- Currently this model has been used to support NFPA 805 transitions
Public Meeting - July 24, 2019 HEAF OpE Bus Duct Columbia Bus Duct (OpE) 2009 Diablo Canyon Bus Duct (OpE) 2000 Bus 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 fragility Modeling Approach 11 As 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 cost Bounding ZOI (Current Model) 12 As 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 application Refined Bounding ZOI 13 As 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 costly Dynamic ZOI 14 As 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 methodology Modeling Approach Status
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
- Used in IEEE 1584-2002 for > 15kV applications Theoretical Lee Model R. Lee, The Other Electrical Hazard: Electric Arc Blast Burns, 1982
Public Meeting - July 24, 2019
- Output
- IE, incident energy (J/cm2)
- Inputs
- V, system voltage (kV)
- t, arcing time (seconds)
- Ibf, 3 phase bolted fault current
- D, distance from arc point Theoretical Lees Method ASTM slug T-cap. slug KEMA Daq Physical Measurement R. 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 VLL, 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 voltage ASTM slug T-cap. slug KEMA Daq Physical Measurement Literature R. Wilkins, M. Allison, M. Lang, Improved Method for Arc Flash Hazard Analysis, 2004
Public Meeting - July 24, 2019 Semi-empirical Gammon Simplified T. 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)
IEratioUB, Incident energy rate ratio upper bound (configuration based 0.758 - 2.098)
ASTM slug T-cap. slug KEMA Daq Physical Measurement Literature
Public Meeting - July 24, 2019
- Output
- EMA,EMB, Max. Incident Energy
- Input
- F, 3-phase short-circuit current
- tA, tB, arc duration
- DA,DB, distance Empirical - Statistical Doughty - Neal - Floyd ASTM slug T-cap. slug KEMA Daq Physical Measurement R. 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 flash calculations
- 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 target Empirical - Statistical IEEE 1584 - 2002 IEEE 1584-2002, Guide for Performing Arc-Flash Hazard Calculation, 2002
Public Meeting - July 24, 2019 Empirical - Statistical IEEE 1584 - 2002
- Output
- IE, Incident Energy
- Input
- V, system voltage
- Ia, arc current
- t, arc duration
- G, conductor gap
- D, distance
- x, distance exponent
- Configuration (open / box)
ASTM slug T-cap. slug KEMA Daq Physical Measurement Literature IEEE 1584-2002, Guide for Performing Arc-Flash Hazard Calculation, 2002
Public Meeting - July 24, 2019
- Guide for performing arc flash calculations
- Significantly changed from 2002 edition
- Model for incident energy calculations
- Empirically derived model from 2,160 tests
- Five configurations
- VCB, VCBB, HCB, VOA, HOA Empirical - Statistical IEEE 1584 - 2018 IEEE 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
- Target Distances: 12 inches
- Fault clearing time: no limit IEEE 1584 - 2018 Range of model
Public Meeting - July 24, 2019 Output
- IE, Incident Energy Input
- Ibf, Bolted fault current
- Voc, System voltage
- T, Duration
- D, Distance
- G, Conductor gap
- Enclosure Dimensions
- Equip Configuration Empirical - Statistical IEEE 1584-2018 ASTM slug T-cap. slug KEMA Daq Physical Measurement Literature
Public Meeting - July 24, 2019
- Model overpredict max measured incident energy
- Maximum overprediction : ~11x
- 550 kJ/m2 measured vs. 6,100 kJ/m2 calculated
- Minimum overprediction : ~2x
- 3.4MJ/m2 measured vs. 6.3MJ/m2
- Note: 2 instruments damaged due to HEAF damage likely higher heat flux at damaged sensors and better agreement with model Model Comparison IEEE 1584 - 2018 vs MV Alum
Public Meeting - July 24, 2019
- Model overpredict max measured incident energy
- Maximum overprediction : ~17x
- 550 kJ/m2 measured vs. 9,100 kJ/m2 calculated
- Minimum overprediction : ~3x
- 3.4MJ/m2 measured vs. 9.4MJ/m2 calculated
- Note: 2 instruments damaged due to HEAF damage likely higher heat flux at damaged sensors and better agreement with model Model Comparison LEE vs MV Alum
Public Meeting - July 24, 2019
- T-cap slug calorimeter (tungsten)
- Model overpredict max measured incident energy
- Maximum overprediction : ~26x
- 236 kJ/m2 measured vs. 6,100 kJ/m2 calculated
- Minimum overprediction : agreement
- 6.0MJ/m2 measured vs. 6.3MJ/m2 Model Comparison IEEE 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/m2 measured vs. 9,100 kJ/m2 calculated
- Minimum overprediction : ~1.6x
- 6.0MJ/m2 measured vs. 9.4MJ/m2 Model Comparison LEE 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-up Existing Models