ML19183A312

From kanterella
Revision as of 13:28, 11 July 2019 by StriderTol (talk | contribs) (Created page by program invented by StriderTol)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to navigation Jump to search
Working Group Activities
ML19183A312
Person / Time
Issue date: 07/02/2019
From:
Office of Nuclear Regulatory Research
To:
K. Hamburger 415-2022
Shared Package
ML19183A307 List:
References
Download: ML19183A312 (25)
v • d • e


Text

Public Meeting

-July 24, 2019High Energy Arcing Faults (HEAF) Working Group Status UpdateNicholas MellyNuclear Regulatory Commission Office of Nuclear Regulatory ResearchMarko RandelovicElectrical Power Research Institute Senior Technical Leader Public Meeting

-July 24, 2019*Provide overview of NRC/EPRI working group (WG) activities and progress

-WG Mission

-PRA modeling approach / update

-Lessons learned from operational experience review

-Testing approach

-Project Plan Purpose 2 Public Meeting

-July 24, 2019NRC / EPRI Working Group (WG)Charter*Mission Statement

-To improve understanding of risk from electrical arcing fault hazards in nuclear power plants (NPPs

).*Goals-Better understand key factors contributing to:

  • Occurrence
  • Severity-Advance HEAF fire PRA modeling
  • Based on experimental data, operating experience, and engineering judgement*Ignition frequency
  • Zone of influence (ZOI)

-Analyze plant impact and risk implications

  • Weekly Meetings Public Meeting

-July 24, 2019*Ken Fleischer (Fleischer Consultants)

  • Dane Lovelace (Jensen Hughes)
  • Shannon Lovvern(TVA)*Tom Short (EPRI)
  • Nicholas Melly (NRC)
  • Kenn Miller (NRC)
  • Gabriel Taylor (NRC)

Public Meeting

-July 24, 2019*EPRI/NRC HEAF Methodology Report

-Extensive OpEreview *Fault Duration

  • Fault Location

-HEAF Fire Ignition Frequency

  • 1E vs. Non

-1E investigation

-HEAF redefinition to fit OpEand modeling uses

-Risk Model Development

  • Event Trees
  • HEAF Non-Suppression Curve
  • HEAF modeling guidance
  • Data Analysis NRC/EPRI WGActivities Public Meeting

-July 24, 2019*Research and test durations are based on operating experience

  • Millisecond fault occurrences are notpart of the HEAF frequency bins
  • OpEReview identified additional generator fed faults than previously known NRC/EPRI WG ActivitiesOperating History (OpEreview)PlantEventEvent classificationEvent DurationPalo Verde (MVoltage)7/6/1988Arc Blast0.75 sec (actual duration)DC Cook (MVoltage)7/13/1990HEAFLikely Waterford (MVoltage)6/10/1995HEAF 4-8 sec (estimated:generator fed)SONGS (MVoltage)2/3/2001HEAF 4-8 sec (estimated:generator fed)Prairie Island (MVoltage)8/3/2001HEAF 4-8 sec (estimated:generator fed)Robinson (MVoltage)3/28/2010HEAF1st Event: 20 sec (actual HEAF duration)Robinson (MVoltage)3/28/2010HEAF2nd Event: 3 Min high impedance fault followed by unknown duration HEAF event Palo Verde (MVoltage)7/3/2013HEAFEstimated < 2 seconds(however, photo evidence that protection may have operated much faster)Brunswick (M Voltage)2/7/2016Arc Blast0.15 sec (estimated duration)Yankee Rowe (L Voltage)8/2/1984HEAFUnknownFort Calhoun (L Voltage)6/7/2011HEAF42 sec (actual duration)River Bend (L Voltage)2/12/2011 HEAF 12 Sec Public Meeting

-July 24, 2019Fault CharacteristicsFault Duration 0 2 4 6 8 10 12Unknown0.5 1 2 4 12 20 50Number of EventsDuration of Fault (seconds)Actual DurationEstimated Duration

  • Investigation of OpEevent duration to ensure testing and modeling efforts representative Public Meeting

-July 24, 2019*Low voltage cabinets were procured using input and recommendations from the WG

  • Testing parameters will be adjusted accordingly to mimic faults from OpE-Current WG activity to investigate typical protective device setpointsEvaluation of the US OELow VoltagePlantEventEvent classificationEvent DurationGermany (L Voltage)5/30/1986HEAF8.5 SecYankee Rowe (L Voltage)8/2/1984HEAFUnknownFort Calhoun (L Voltage)6/7/2011HEAF42 sec (actual duration)River Bend (L Voltage)2/12/2011 HEAF 12 Sec Ref. Westinghouse I.B. 33

-790-1E Public Meeting

-July 24, 2019NRC/EPRI WG Activities Testing-Supply vs. Load

  • Fall 2018 testing followed IEEE guidance with respect to arc wire location and size
  • Working group review of OE on medium voltage switchgear revealed

-majority of the medium voltage switchgear events occurred in the supply switchgear configuration and involved main bus work

  • Configuration and equipment type has been identified as parameters of interest
  • Working group is currently discussing options to most accurately reflect realism in a testing environment Public Meeting

-July 24, 2019*Event Frequency classification

  • Need for clear definitions

-Subdivide Bin 16 (NUREG/CR

-6850)-Arc Fault Class 1 (Arc Flash)

-Arc Fault Class 2 (Arc Blast)

-Arc Fault Class 3 (HEAF)

  • NRC working with NFPA/IEEE & EPRI Working Group

-Continued discussion to finalize definitions for arc fault events

  • Updated frequencies for HEAF events to be developed by the NRC/EPRI HEAF WG to coincide with the ZOI methodology and event tree modeling approach NRC/EPRI WG ActivitiesFrequency Review Public Meeting

-July 24, 2019Arc Fault Classifications 11 Public Meeting

-July 24, 2019*Approach being developed by the WG to incorporate plant design with ZOI and HEAF susceptibility

  • More accurate reflection of realism*Major improvement over a one size fits all model
  • Currently in the developmental stage with WGNRC/EPRI WG ActivitiesPRA Risk Model Development Public Meeting

-July 24, 2019NRC/EPRI WG ActivitiesRisk Model DevelopmentGeneric Frequency xIgnition Source Weighting FactorLocationSWGR Breaker AvailableSourceDesignGenerator Circuit BreakerDurationZOIEnd Sequence(Zone 2)End Sequence(Zone 1 & 5)

< 2ZOI 1 A 2N/A(Zone 2)GCB Works< 4ZOI 2 B 2 A 1SupplyGCB Fails4 - 8 ZOI 3 C 2 B 14 - 8ZOI 3 D 2 C 1 (Zone 1)< 4ZOI 2 E 2 A 5g*W is< 2ZOI 1 F 2N/A(Zone 2)GCB Works< 4ZOI 2 G 2N/ALoadGCB Fails4 - 8 ZOI 3 H 2N/A4 - 8ZOI 3 I 2N/A (Zone 1)< 4ZOI 2 J 2N/ASWGR Breaker Unavailable/FailsUnit Auxiliary Transformer Site Auxiliary TransformerUnit Auxiliary Transformer Site Auxiliary TransformerGenerator Circuit BreakerNo Generator Circuit BreakerNo Generator Circuit BreakerGenerator Circuit BreakerSWGR Breaker Available AND FunctionsSWGR Breaker Available AND FunctionsSWGR Breaker Unavailable/Fails Public Meeting

-July 24, 2019*Temperature and Heat Flux

-Both parameters will be modeled at multiple distances away from the arc locatio n-Will aid in a dynamic ZOI creation

-Link to SNL Fragility criteria testing (to be discussed in the afternoon)

  • Pressure (improved measurement techniques developed)

-Potential to measure impact on room pressure currently being explored *Damage Zone

  • Furthest extent of damage

-Thermal (i.e. ensuing fire damage / smoke damage)

-Physical ( i.e. thrown cabinet door, shrapnel)

  • Conductivity

-SNL Measurements

-Other OptionsHEAF Phase II TestingMeasurement Public Meeting

-July 24, 2019*Mass of Material Vaporized

-Measurements pre

-and post-testing to validate computer models and theory equations of vaporized material

-Potential to develop approximate energy release models from classical energy conversion models

  • Cable Sample Material

-Cable samples placed at varying distances away from enclosure

  • Byproduct Testing

-Samples*Carbon Tape & Aerogel used in 2018

  • Carbon Tape & Silicon/Quartz in 2019

-Conductivity measurements for aluminum deposited on surfaces

-Spectroscopy

  • Heat Release Rate (HRR) measurement is impraticalbased on lessons learned in phase I testingHEAF Phase II TestingMeasurement (continued)

Public Meeting

-July 24, 2019*SNL has experience with this type of measurement

  • Surface conductivity

-Passive measurements

-Interdigitated resistivity measurement structures

  • Parallel conductive traces
  • Evaluate voltage holdoff/surface flashover properties

-Concentric ring surface resistance measurement (ASTM D257)-This instrumentation will address the potential for failure of electronic equipment exposed to the arc ejecta or smoke generated by the HEAF eventHEAF Phase II TestingSurface Conductivity Measurements Public Meeting

-July 24, 2019*Conductivity sensor

-Active measurement

-Mesh design for EMI rejection-Air conductance measured as voltage in circuitHEAF Phase II TestingAir Conductivity Measurements Public Meeting

-July 24, 2019*Purpose of the Mock Switchgear Test Unit (MSTU) is to verify if liberal amounts of aluminum combustion cloud byproduct/debris is sufficient to cause collateral damage (flashover) in nearby/adjacent medium voltage.

  • To the extent practical, the MSTU is to represent typical switchgear with respect to voltage, bus bar spacing and standoff insulators to ground
  • MSTUs are portable, re

-usable and do not require excessive power

  • Provides prototypical configuration to evaluate flashoverMock Switchgear Test UnitEvaluate flashover (arc

-over)

Public Meeting

-July 24, 2019*Design of the MSTU is based on a bounding approach to which type electrical distribution system (EDS) is most vulnerable to a flashover or tracking phenomenon out of:

-Wye system (solidly grounded)

-Wye system (resistance grounded)

-Wye (ungrounded neutral)

-Delta (ungrounded)

-Uninsulated bus bars Mock Switchgear Test UnitEvaluate flashover (arc

-over)

Public Meeting

-July 24, 2019HEAF Phase II TestingConductivity

-Benefits and Limitations TypeBenefit LimitationSurface ConductivityKnown Measurement TechniqueCan measures hold off / break down in addition to surface resistancePassive designDoes not measure air conductivityRequires failure criteria of components which may require additional testing or engineering judgmentAir ConductivityActive instrumentation Limited number to deployMock Switchgear Close simulation of plant equipment Bounding result (Exclusionary)

Public Meeting

-July 24, 2019Aug/Sept '19Phase II TestsElectrical EnclosuresLegend OECD/NEA HEAF Phase 2 Tests U.S. NRC specific supplemental testing driven by generic issue aluminum HEAF program Uncommitted tests to explore unanticipated results/enhance repetition if necessaryEnclosure Testing Aluminum Bus Bars Copper Bus Bars 6900 Volt 480 Volt 6900 Volt 25 kA 15 kA 35 kA 25 kA 4 s 2-2 35 kA 480 Volt 25 kA 15 kA 25 kA 4 s 2-5 4 s 2-8 4 s 2-9 4 s 2-11 4 s 2-12 4 s 2-14 4 s 2-17 4 s 2-20 2 s 2-22 4 s 2-23 2 s 2-1 2 s 2-4 2 s 2-7 2 s 2-10 4 s 2-24 X

  • X *8 s 2-6 8 s 2-3 2 s 2-13 8 s 2-15 2 s 2-16 8 s 2-18 4 s 2-21 2 s 2-19*

Public Meeting

-July 24, 2019Legend OECD/NEA HEAF Phase 2 Tests U.S. NRC specific supplemental testing driven by generic issue aluminum HEAF programUncommitted tests to explore unanticipated results/enhance repetition if necessary

  • Aluminum Bus Steel Enclosure Copper BusAluminum Enclosure Aluminum BusAluminum Enclosure Copper BusSteel Enclosure4s 2-262s 2-25 2s 2-274s 2-284s 2-304s 2-322s 2-31Bus Duct Testing 4160 Volt /25 kA 2s 2-295s 2-33*5s 2-34*Phase II Tests Bus DuctsAug/Sept '19 Public Meeting

-July 24, 2019*New information used as identified to re-evaluate objectives of test plan

  • Changes being proposed to focus on

-Configuration

  • Arc location
  • Equipment design

-Decrement-Arc Current

-DurationPhase IITest plan re

-evaluation Public Meeting

-July 24, 2019Phase II Tests Electrical Enclosures

-Spring 2020Enclosure TestingMV Supply Side Config.AluminumHorizontal Draw

-out Breakers 2x-4 4sVertical Lift Breakers 2x-3 4 s 2x-2Decrement Curve*CopperVertical Lift Breakers 2x-1Decrement Curve**Focus of decrement curve testing is to be representative of NPP OpEand generator characteristics to determine appropriate testing conditions

  • Decrement tests
  • 2x-1*2x-2*Confirmatory tests
  • 2x-3*2x-4**Working Group recommendations for both equipment procurement, test design conditions and applicability to plant realism has been incorporated into the upcoming Summer 2019 and Spring 2020 and test series and will continue to be actively incorporated into future testing Public Meeting

-July 24, 2019*Project plan is being developed to capture all components of the HEAF research program and how they fit together

-History-Scoping/Literature Studies

-Phase I Testing

-Small Scale Testing

-Phase II Testing

-Modeling and Analytical Work

  • NRC webpage will be hosted for easy reference and tracking-This will be in addition to the Generic Issues Dashboard site Project Plan
Retrieved from "https://kanterella.com/w/index.php?title=ML19183A312&oldid=1791580"