ML18108A210
ML18108A210 | |
Person / Time | |
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Issue date: | 04/18/2018 |
From: | Michael Cheok NRC/RES/DRA/FRB |
To: | |
G. Taylor 415-0781 | |
References | |
Download: ML18108A210 (278) | |
Text
NRC HEAF Phase II Information Sharing Workshop Michael Cheok Director Division Of Risk Analysis Office of Nuclear Regulatory Research April 18, 2018 Rockville, Maryland NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Welcome
- Welcome to the workshop
- Participants at NRC Headquarters
- Participants via Webinar
- U.S
- International
- Large amount of information to cover in 2 days
- Encourage your participation NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Expected Outcome
- Clear definition of the hazard
- Input to support Phase II testing
- Realistic
- Representative
- Input to support current stage of the Generic Issue Process NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Thank You
- Thank you for taking the time to support this important project
- Your experience and expertise are greatly valued as we move forward
- Improve safety
- NRC Licensee
- Larger Industrial Community NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
NRC HEAF Phase II Information Sharing Workshop - Introduction
& Objectives Mark Henry Salley P.E.
Chief Fire and External Hazards Analysis Division of Risk Analysis Office of Nuclear Regulatory Research April 18, 2018 Rockville Maryland NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Welcome
- Introduce Presenters
- Room Introductions
- Go To Meeting Webinar Introductions
- U.S.
- Foreign
- Email Thomas.Aird@nrc.gov
- Transcribe Workshop
- Please identify yourself when you speak
- Prepare a NUREG/CP at the end of workshop
- Document what we learn next 2 days 2
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Purpose
- Share what we have learned to date
- Solicit input from all stakeholders
- Discuss options moving forward
- Learn from each other
- Support OECD/NEA HEAF Project
- Meeting next week
- Support NRC Generic Issue Program 3
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Overview Day 1
- Review Phase I Full Scale Testing
- NRC Generic Issue Process
- Pilot Plants
- Definitions
- Small Scale Testing
- PRA Modeling Implications
- Industry Presentations
- NFPA
- EPRI
- KEMA 4
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Overview Day 2
- Discuss HEAF Phase II Test Plan
- Comments Received
- Proposed Comment Resolution
- NRC Request
- Needs and Objectives
- Test Parameters
- Equipment Selection
- Public Comment
- Wrap-up 5
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Path Forward
- Revise Test Plans
- Small Scale
- Full Scale
- OECD/NEA Phase II Agreement
- Prepare for Testing
- Obtain Equipment
- Perform Testing
- October 2018
- Summer 2019 6
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Develop Long Term, Risk-Informed, Defense-in-Depth Solution Safe Shutdown Protect & Preserve Safe Shutdown Rapid Detection & Mitigation Circuit Protection, HEAF Shields, Prevention Safe Work Practices, Maintenance, Arc-Resistant Cabinets 7
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
NRC Safety Mission
- NRC Mission Statement
- to license and regulate the civilian use of radioactive materials in the United States to protect public health and safety, promote the common defense and security, and protect the environment.
- Secondary Benefit, - Openness &
Collaboration
- Share what we have learned with the larger engineering community to promote safety 8
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Review of Phase I HEAF Research Nicholas Melly Mark Henry Salley P.E.
Office of Nuclear Regulatory Research Division of Risk Analysis April 18, 2018 Rockville , Maryland NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Purpose
- Provide High Level Overview and Identify Reference Material on NRC Fire Research Program for:
- Electrical Enclosure Fires
- Arc Flash /Arc Blast Events
- High Energy Arcing Faults (HEAF)
- Most current Information
- Changes as Program Evolves 2
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Initial Thoughts on Electrical Enclosures- Failure Modes 3
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
PRA Risk Significant Contribution
- March 15, 2018 3rd highest contributor 4
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
NUREG/CR-6850 EPRI 1011989
- Fire PRA Needs
- Bin 15 Electrical Enclosure Fires
- Bin 16 HEAF
- Lesson Learned
- Bin 15 Too Broad
- Low Voltage Controls considered same risk as Medium Voltage Switchgear https://www.nrc.gov/reading-rm/doc-
- Create Realistic Divisions for collections/nuregs/contract/cr6850/
Bin 16
- Discussion later in workshop 5
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Electrical Enclosure Fire Experiments (Bin 15)
- Heat Release Rates of Electrical Enclosure Fires (HELEN-FIRE)
- 112 Full Scale Electrical Enclosure Fires
- Developed a Series of Heat Release Rate (HRR) Profiles
- Non- Energized https://www.nrc.gov/docs/ML161
- No electrical current 1/ML16110A037.pdf 6
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Electrical Enclosure Fire Methodology
- Refining And Characterizing Heat Release Rates From Electrical Enclosures During Fire (RACHELLE-FIRE) Volume 1: Peak Heat Release Rates and Effect of Obstructed Plume, Final Report (NUREG-2178, Volume 1, EPRI 3002005578)
- NRC/EPRI Working Group
- Classification of Electrical Enclosures (function, size, content, ventilation)
- Determined HRR probability distributions for corresponding categories
- Characterization of Fire Plumes
- NIST Fire Dynamics Simulator (FDS) https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr2178/
7 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
HEAF Definition (Bin 16)
- Need for clear definitions
- Subdivide Bin 16
- Arc Flash (Bin 15)
- Arc Blast
- High Energy Arcing Fault
- Electrical Enclosure Thermal Fire (Bin 15)
- NRC working with NFPA
- Separate Discussion Later Today
- Solicit Workshop Participants Input 8
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Example of Recent Electrical Enclosure Arc Flash/Arc Blast Events Turkey Point; 2017 Brunswick; 2016 9
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Example of Recent Electrical Enclosure HEAF Experience SONGS, 2001 San Onofre; 2001 Onagawa; 2011 10 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Example of Recent Bus Duct HEAF Experience Diablo Canyon Bus Duct (OpE) Zion Bus Duct (testing) Columbia Bus Duct (OpE) 2000 2016 2009 11 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Operating Event History (OpE) -
Duration
- Operating Event history shows that breakers do not always work as expected (design vs. real world)
- HEAF events typically persist for timeframes much longer than design fault clearance times through the mechanism of breaker failures or other complicating factors Event Hold Time Cause Prairie Island; 08/03/2001 >2 seconds Breaker Failure; Ionizing gas from the breaker was the initiator Songs; 02/03/2001 2.5 Seconds Breaker Failure; Ionizing gas from the breaker was the initiator Robinson; 03/27/2010 8-12 seconds Breaker Failure; Loss of DC Control Power Diablo Canyon; 05/15/2000 11 seconds Location; Voltage Decay Columbia; 10/20/2009 5 seconds Aging Fort Calhoun; 06/07/2011 Terminated by Operators >42 seconds Design Deficiency Germany; 09/08/1989 6 seconds Undetermined Germany; 08/23/2004 >2 seconds Overcurrent degradation Germany; 05/30/1986 8.5 seconds Undetermined 12 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Safety Significance
- 10CFR 50 Appendix A General Design Criteria (GDC)
- GDC 3 Structures, systems, and components important to safety shall be designed and located to minimize, consistent with other safety requirements, the probability and effect of fires and explosions.
- GDC 17 The onsite electric power supplies, including the batteries, and the onsite electric distribution system, shall have sufficient independence, redundancy, and testability to perform their safety functions assuming a single failure.
13 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Background of the HEAF Program
- OECD Fire Incident Records Exchange Project (FIRE)
- Analysis of High Energy Arcing Fault (HEAF) Fire Events, NEA/CSNI/R(2013)6
- 48 of 415 fire events collected represent HEAF-induced fire events (over 10%)
- International Partners
- Canada, Finland, France Germany, Japan, Korea, https://www.oecd-nea.org/nsd/docs/2013/csni-r2013-6.pdf Spain, U.S.
14 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Background of the HEAF Program CSNI WGIAGE Task on High Energy Arcing Faults (2009 - 2013)
- Task Report A Review of Current Calculation Methods Used to Predict Damage from High Energy Arcing Fault (HEAF) Events, NEA/CSNI/R(2015)10
- Insights from operating experience with partly significant HEAF events http://www.oecd-nea.org/nsd/docs/2013/csni-r2015-10.pdf
- Literature study on methods for predicting HEAF consequences 15 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Realistic Quantification of Hazard
- NRC testing has been, and will continue to be, informed by Operating Experience and NPP configurations:
- LERs describe numerous three-phase arc faults with failure of an upstream breaker
- Representative plant equipment used in testing
- Voltage, current, arc duration within the bounds observed in LERs
- Damage observed comports with LERs
- Input from Todays Workshop
- Draft Test Plans placed in Federal Register for Public Comment 16 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
U.S. OpE- Three Phase Faults
- Three phase arcs generated at KEMA were initiated by means of a copper shorting wire 2.6 mm in diameter (10 AWG) as described in IEEE C37.20.7-2007 for low voltage equipment https://standards.ieee.org/findstds/standard/C37.20.7-2007.html
- Most HEAF event that we are aware of quickly progress to three phase faults. This is evident from a number of LERs:
- The Kewaunee HEAF event (LER 87-009-00) involved a phase-to-ground fault, which progressed to a phase-to-phase fault which accounted for the extensive bus damage.
- The Prairie Island HEAF event (LER 01-05-00) involved a C-phase ground arcing event, which quickly involved all phases.
- The Zion HEAF event (LER 94-005-01) states that the failure started as a single phase to ground fault which rapidly evolved into a three phase to ground fault.
17 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
U.S. Operating Event History (OpE)
Overpressurization
- Arc Flash and HEAF events can lead to overpressurization of compartments and challenge fire rated barriers even when circuit protection works as expected
- Turkey Point Event-March 18, 2017
- Fault Cleared in 35.8 cycles (or ~0.6 seconds)
- The protective relays operated as expected
- Fire Door D070-3, located 4.4m (14.5 ft.) away from the origin of the fault was damaged and the latch mechanism was deformed
- Damage was caused by the over-pressurization of the room corresponding to the increase in pressure at the onset of the arc event
- The damaged door defeated the 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> rated barrier between the 3A and 3B 4kV switchgear rooms
- NRC Reactive Inspection Report May 12, 2017 (ML17132A258) 18 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Phase I HEAF Testing
- 26 full-scale experiments carried out at KEMA high energy test facility between 2014-2016.
19 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Phase I HEAF Testing Test #3: 480 V, 35 kA, 8 seconds Copper Bus Bars 20 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Phase I HEAF Testing Test #15: 10 kV, 15 kA, 3 seconds Oil-filled breaker (oil removed), copper bus bars 21 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Phase I HEAF Testing Test #23: 480 V, 40 kA, 7 seconds Aluminum bus bars 22 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Phase I HEAF Testing Test #26: 4.16 kV, 26 kA, 3.5 seconds Bus Duct, copper bus bars, aluminum housing 23 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Phase I HEAF Testing Results
- Material Impact of Aluminum
- Potentially much larger ZOI
- Potentially greater likelihood of maintaining an arc at low voltages
- Higher risk of fire propagation 24 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Phase I HEAF Testing Results
- New Failure Mode: Test 23 Test 26 Conductive Products of Combustion
- Conductive AL byproducts coated facility
- Shorted out equipment and damaged electrical circuits
- Fort Calhoun HEAF event-June 7, 2011
- Adjacent cabinets affected by HEAF bi-products 25 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Phase I HEAF Testing Report
- Report on the Testing Phase (2014-2016) of the High Energy Arcing Fault Events (HEAF)
Project: Experimental Results from the International Energy Arcing Fault Research Program, NEA/CSNI/R(2017)7 https://www.oecd-nea.org/nsd/docs/2017/csni-r2017-7.pdf 26 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Postulated HEAF Mitigation-HEAF Shields
- Proposed shielding to limit the extent of damage from a HEAF events
- objective is to minimize damage to risk-significant targets beyond the faulted switchgear and to prevent damage and ignition overhead cable trays:
- In order for HEAF Shields to be Successful:
- What is the Design Basis?
- What is the Acceptance/Rating/Qualification Test Method?
- How does the Installed HEAF Shield match what was Tested?
- Why should this Engineered Feature be treated any different than:
Fire Barriers (Walls/Floors), Fire Doors/Dampers Electrical Raceway Fire Barrier Systems, Penetration Seals, etc?
27 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Postulated HEAF Mitigation-Louvers / Solid Tops Misconceptions:
- Energy will only travel in direction of the vents and will prevent significant energy/mechanical damage targets located above or away from the vent path
- Solid tops on switchgears always contain the HEAF and prevent damage to targets above 28 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
- Generic Issues Program Pre-GI-018
- The NRC has performed a screening review as part of the GI process related to HEAF events involving aluminum components
- The generic issue review panel (GIRP) determined that the seven screening criteria were met in accordance with management directive 6.4 (ML14245A048) and is in the process of finalization and release of the screening phase document
- The staff has recommended a two phase approach to address the generic issue and identified both short term and long term actions
- GIRP memo issued (ML16349A027)
- Moving into next phase of Generic Issue Program
- Separate Presentation Later Today 29 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Information Notice (IN) 2017-04
- High Energy Arc Faults in Electrical Equipment Containing Aluminum Components
- OECD/NEA international test program insights
- 6 U.S. operating experience events involving aluminum components Plant Date Fort Calhoun June 7, 2011 Columbia August 5, 2009 Diablo Canyon May 15, 2000 Zion April 3, 1994 Shearon Harris October 9, 1989 Kewaunee July 10, 1987
- Issued August 21, 2017 30 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
- International Phenomena Identification and Ranking Table (PIRT) exercise held in February 2017
- Early Insights:
- Aluminum oxidation and byproducts
- Pressure effects
- Target characterization and sensitivity
- Mitigating factors (HEAF https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr2218/
shields) 31 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
International Agreement Report
- NUREG/IA-0470 Volume 1 Nuclear Regulatory Authority Experimental Program to Characterize and Understand High Energy Arcing Fault (HEAF)
Phenomena
- International Partnership with Japan Regulator
- Secretariat of Nuclear https://www.nrc.gov/reading-rm/doc-collections/nuregs/agreement/ia0470/
Regulation Authority S/NRA/R 32 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Phase II Draft Test Plan
- Public Comment Period
- OECD/NEA Phase I members for comment on June 30, 2017
- Federal Register notice (82 FR 36006) published on August 2, 2017
- Public comment period closed September 1, 2017
- 64 comments received in total + 27 EPRI comments
- Separate Discussion Tomorrow 33 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Conclusion
- Electrical Enclosure Fires, Arc Flashes, Arc Blasts and HEAFs are not unique to Nuclear Power Plants
- However, they warrant special attention by the NRC and the Nuclear Industry due to their potential impact on Reactor Safety
- NRC would like to continue to work in collaboration with U.S. and International Partners 34 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Generic Issues Program Overview Office of Nuclear Regulatory Research Division of Engineering Regulatory Guidance and Generic Issues Branch Thomas Boyce, Branch Chief Stanley Gardocki, Senior Project Manager April 2018 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Program Overview Purpose of Generic Issues Program Fundamentals of the Generic Issues Program
- Stages of Generic Issues Program
- Process Overview
- Responsible Individuals and Groups
- Responsibilities of ACRS within the Generic Issues Program Screening Criteria for Proposed Generic Issues Documentation
- Periodic Reports (semi-annual Generic Issue Management Control System)
Origins of Generic Issues Program December 1977- Section 210 of the Energy Reorganization Act of 1974 was amended by Congress directing the NRC Commission to:
- Develop a plan for specification and analysis of unresolved safety issues (USI) relating to nuclear facilities, and
- Take actions as necessary to implement corrective measures with respect to such issues As a result, the NRC staff developed a Generic Issues Program that would identify important safety issues applicable to multiple nuclear facilities NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Three Stages of Generic Issues Program NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Responsible Program Individuals Director of the Office of Nuclear Regulatory Research (RES)
- Provides overall management of the GI Program The GI Program Manager (Chief of the Regulatory Guidance and Generic Issues Branch (RGGIB), RES/Division of Engineering)
- Responsible for program administration and daily program management. The GI Program Manager facilitates timely actions for the issue by the responsible organizations.
The Responsible Project Manager (RPM) (RGGIB staff member)
- Assigned the overall lead role for managing actions in the GI Program. The RPM facilitates progression of GIs, especially in the Screening and Assessment stages.
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Responsible Program Groups/Panels Generic Issue Review Panel (GIRP):
- Composed of a chairman at the Senior Executive Service (SES) level, technical experts, the RPM, and a member of RES/DE line management.
Responsible for evaluations performed during the screening and assessment stages. Provides recommendations whether a GI should proceed forward in the GI process.
Assessment Team:
- Composed of the RPM and knowledgeable individuals of the issue. Provides technical support to assist the GIRP conclude whether the proposed GI should continue to Regulatory Office Implementation Stage.
Transition Team:
- Composed of a team lead at the SES level, the RPM, and knowledgeable individuals of the issue. Provides support until the transition team leader is satisfied that sufficient knowledge has been transferred to the receiving office staff NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Process Overview NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Screening Criteria for Proposed GIs The GI Program only addresses issues that meet all seven criteria:
- 1) The issue affects public health and safety, the common defense and security, or the environment.
- 2) The issue applies to two or more facilities, licensees, or holders of other regulatory approvals.
- 3) The issue is not being addressed using other regulatory programs and processes; not addressed by existing regulations, policies, or guidance.
- 4) The issue can be resolved by new or revised regulation, policy, or guidance.
- 5) The issues risk or safety significance can be adequately determined in a timely manner (does not require long-term study).
- 6) The issue is well defined, discrete, and technical.
- 7) Resolution of the issue may involve review, analysis, or action by the affected licensees.
Screening Criteria can be found in:
Management Directive 6.4, Generic Issues Program NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
NUREG 0933 NUREG-0933 provides the historical record of resolved generic safety issues.
It documents the screening analysis and disposition of all issues.
It is available on the NRC public website at https://www.nrc.gov/sr 0933/
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Generic Issue Dashboard The GI Dashboard provides on-line access to the detailed status of active generic issues in the Regulatory Office Implementation Stage.
GI Dashboard is available on the public NRC website:
https://www.nrc.gov/about-nrc/regulatory/gen-issues/dashboard.html
((NRC Staff: GI Dashboard is also available on the internal NRC web page. It also provides status of generic issues that are in Screening and Assessment Stages. It can be found in the Programs and Projects section of the Research Web page:
http://gid.nrc.gov/Static/SitePreview.h tml NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Recent Proposed Generic Issues Recent Generic Issues: majority closed in Screening Stage [bold still open]:
- Pre GI-0001 - Multi-Unit Core Damage Events
- Pre GI-0002 - BWR Strainer Issues
- Pre GI-0003 - Fuel Pool Criticality Issue
- Pre GI-0005 - Electromagnetic Pulse Attack
- Pre GI-0007 - Core Uncovery after Discharge Leg LOCA
- Pre GI-0008 - BWR RHR Water Hammer
- Pre GI-0009 - Flooding Following Upstream Dam Failure [Currently open in the Regulatory Office Implementation Stage as GI-204]
- Pre GI-0010 - Dispersal of Fuel Particles During LOCA
- Pre GI-0011 - Downstream Dam Failures
- Pre GI-0012 - Effects of Upstream Dam Failures on Fuel Facilities
- Pre GI-0013 - Effect of External Flooding on ISFSI
- Pre GI-0014 - Man-Made External Hazards
- Pre GI-0015 - Trapped Hydrogen and Oxygen Fire and Explosion During Fluid Transients
- Pre GI-0016 - Dependency on Electrical Power to Support Operation of AFW Turbine-Driven Pump
- Pre GI-0017 - Great Lakes Low Water Level
- Pre GI-0018 - HEAF [Currently open in the Assessment Stage]
- Pre GI-0019 - Containment Penetrations short circuit protection
- Pre GI-0020 - Inadequate Procedures for AOOs [Currently open in the Screening Stage]
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
References
- Management Directive 6.4, Generic Issues Program (ML14245A048), or on the web in the NRC Library in Document Collections
- RES Office Instruction TEC-002, Rev. 2, Procedures for Processing Generic Issues (ML11242A033)
- NRR Office Instruction LIC-504, Integrated Risk-Informed Decision-Making Process for Emergent Issues (ML14035A143)
- NUREG-0933, Resolution of Generic Safety Issues
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Generic Issue PRE-GI-018 High Energy Arc Faults Involving Aluminum April 18, 2018 Office of Nuclear Regulatory Research /
Division of Engineering /
Regulatory Guidance and Generic Issue Branch Stanley Gardocki / Senior Reactor Engineer NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
PRE-GI-018 is in Assessment Stage Issue submitted to GI Program Screening Assessment Implementation Issue exits program when issue fails to Or closed when meet screening criteria, for example: licensees actions
- Referred to other regulatory process for action completed and
- Referred for additional long-term research verified NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Process Overview NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Screening Review - Complete
- The NRC formed a Generic Issues Review Panel (GIRP) and it completed a formal screening review on August 21, 2017
- The GIRP found it met all seven screening criteria in accordance with Management Directive 6.4, Generic Issues Program
- The GIRP recommended a phased approach during the assessment stage, involving both short term and long term actions to determine if it should proceed to next stage, Regulatory Implementation Stage (ROI)
- The screening report can be found in Agency Document Access Management System (ADAMS) under accession number ML16349A207 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Short Term Actions These actions occur during the Assessment Stage:
- Task 1) Determine the extent of condition
- Task 2) Develop an interim ZOI
- Task 3) Determine electrical fault characteristics
- Task 4) Develop a risk/safety determination
- Task 5) Develop a plan for future testing
- Task 6) Develop interim guidance
- Task 7) Perform additional focused HEAF testing
- Task 8) Determine if to proceed to ROI stage NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Long Term Actions These actions commonly occur during the Regulatory Office Implementation (ROI) Stage:
- Task 1) Issue generic communications
- Information Notice 2017-04 was issued August 21, 2017
- Additional generic communications may be issued
- Task 2) Revise technical guidance
- Task 3) Assess risk through long-term performance monitoring NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Long Term Actions:
(Continued)
- Phenomenon Identification and Ranking Table (PIRT) team to review OpE and testing results
- Identify the need for and specific type of future testing
- Perform additional focused HEAF testing specifically designed to quantify the ZOI for a HEAF involving aluminum components
- Develop revised guidance based upon tests performed on aluminum components
- Assess risk NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Actions in progress or completed:
- NRC has received results of an informed Industry survey, conducted by NEI, on the extent of aluminum components currently installed in nuclear power plants
- NRC to invite personnel to potential joint industry/NRC expert elicitation process
- NRC to develop future test plans
- NRC scheduled workshop in April 2018 with Industry
- NRC staff to solicit candidates for plant assessment on the impact on risk NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Actions in progress or completed:
Continued
- NRC and Industry will conduct testing to gather more experimental data
- An experimental effort is being planned as a continuation of the OECD/NEA HEAF Experimental Project - Phase 2
- NRC to establish definitive zone of influence (ZOI) with the presence of aluminum
- NRC will calculate potential risk increase NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Summary
- Summary
- Questions
- Comments NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Pilot Plants High Energy Arc Faults Involving Aluminum Nick Melly Office of Nuclear Regulatory Research Division of Risk Analysis April 18, 2018 Rockville, Maryland NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Assessment Stage Risk Analysis Task 4: Develop a risk/safety determination Issue submitted to GI Program Screening Assessment Implementation Issue exits program when issue fails to Or closed when meet screening criteria, for example: licensees actions
- Referred to other regulatory process for action completed and
- Referred for additional long-term research verified NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018 2
Plant Fire Risk Contribution
- March 15, 2018 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018 3
HEAF Fire Risk Contribution HEAF Relative Contribution to Ttoal Fire CDF 50 45 40 35 30 25 20 15 10 5
0 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018 4
Preliminary Risk Assessment Assumptions
- Performed using information from SPAR all hazards models
- Potentially conservative, however a large number of plants did identify aluminum components as part of an informal NEI Survey. (ADAMS Accession No. ML17165A140)
- Hot Gas Layer (HGL) damage was used to evaluate the conditional core damage probability (CCDP) for each HEAF scenario
- In lieu of performing plant walkdowns and evaluating what equipment would be damaged if a larger zone of influence (ZOI) was used for aluminum components
- Conservative assumption which damages all components within the room 5 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Initial Scoping Risk Assessment Assumptions (continued)
- No credit for automatic or manual suppression systems was used, non-suppression probability (NSP) values are set to 1.
- No evaluation was done to evaluate the potential impact on of a HEAF on the suppression systems.
- No evaluation of bus duct contribution
- Scenarios were not provided NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018 6
SPAR Model Results HEAF ZOI as COMPARTMENT DESCRIPTION Plant Fire CDF HGL CDF 1 B Switchgear Room 1.37E-05 2.70E-05 4 Turbine Building 2.47E-06 7.12E-05 5 A Switchgear Room 2.16E-06 6.40E-05 9 A Reactor Aux Building 1.38E-07 2.07E-05 Total Plant Fire CDF Increased HEAF ZOI CDF SUM 3.06E-05 1.95E-04 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018 7
Need for Pilot Plants
- Leverage existing plant probabilistic risk assessment (PRA) models and use pilot plants
- Technical office instruction TEC-002, Procedure for Processing Generic Issues and Section 3 of NUREG/BR-0058, Rev. 4, Regulatory Analysis Guidelines of the U.S.
Nuclear Regulatory Commission, NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018 8
Pilot Plant Features
- Volunteer pilot plants will be selected that have identified aluminum components
- NEI Survey ADAMS Accession No. ML17165A140
- Identified ZOI used to model target damage following
- NUREG/CR-6850, Appendix M
- BUS DUCT (COUNTING) GUIDANCE FOR HIGH-ENERGY ARCING FAULTS (FAQ 07-0035)
- Plants that mapped HEAF scenarios to HGL conditions are not ideal candidates for evaluation
- Plant walkdowns and NRC interaction will be decided on an as needed basis NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018 9
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018 10
Arc Flash/Blast HEAF Definitions Kenn Miller Office of Nuclear Regulatory Research Division of Engineering April 18, 2018 Rockville , Maryland NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Purpose
- Collectively develop/document clear definitions to insure common understanding:
- Arc/Electric Arc
- Arc Blast
- High Energy Arcing Fault (HEAF)
- Electrical Enclosure Thermal Fire 2
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Purpose (Cont.)
- Proposed Arc Fault Severity Classifications:
- Arc Fault Class 1 (Arc Flash)
- Arc Fault Class 2 (Arc/Blast/HEAF)
- Arc Fault Class 3 (Arc Blast/HEAF)
- Proposed definitions and collect input to finalize
- Build on established definitions for development, execution and documentation of research 3
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Arc/Electric Arc
- Arc/Electric Arc - An arc is a high-temperature luminous electric discharge across a gap or through a medium such as charred insulation.
- Based on NFPA 921 definition 3.3.8 4
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
- Arc Flash - An arc flash is a release of energy caused by an electric arc characterized by a rapid release of thermal energy due to the vaporization and ionization of materials by the arc.
- Developed from NFPA 70E definition of Arc Flash Hazard
- When electrical protective systems work as designed, the arcing event is typically limited to an arc flash on the order of cycles rather than seconds depending upon breaker set points
- Arc Flash events typically are associated with self-extinguishing fire events 5
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Arc Blast
- Arc Blast - An arc blast is a rapid release of thermal, mechanical and acoustical energy) caused by the rapid heating and vaporization and ionization of materials resulting from a sufficiently energetic arc flash. Arc Blasts are more energetic than Arc Flash events depending on the electrical characteristics of the system during the initiation of the event; such as the phase angle, current, and voltage characteristics.
- Developed from NFPA 70E definition of Arc Flash Hazard
- Arc blasts can cause room over-pressurization effects and have the potential to lead to missile damage effects from thrown equipment or enclosure material
- All arc blasts are associated with arc flashes, but not all arc flashes lead to arc blasts
- Arc Blast events can still occur when electrical protective systems work as designed 6
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
High Energy Arching Fault (HEAF)
- High Energy Arcing Fault (HEAF) - A high energy arcing fault is a type of arc flash that persists for an extended duration (duration indicative of a level of circuit protection failure and/or protection design flaw)
- High Energy Arcing Faults are typically associated with events contingent with a failure (or lack) of circuit protection or adequate circuit protection coordination
- All high energy arcing faults are associated with arc flashes, but not all arc flashes are high energy arcing faults
- High energy arcing faults may produce varied levels of arc blasts 7
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Arc Fault Class 1 (Arc Flash)
- Arc Fault Class 1 (Arc Flash) - Damage is contained in within the general confines of the component of origin.
- These events are associated with minor damage and minimal bus bar degradation from melting/vaporization.
8 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Arc Fault Class 2 (Arc Blast/HEAF)
- Arc Fault Class 2 (Arc Blast/HEAF) -
Damage is contained in within the general confines of the component of origin. However, arc blast effects have the potential to damage surrounding equipment through pressure rise effects (i.e. severe equipment deformation, thrown doors, degraded fire barriers).
- Typically do not create ensuing fires
- Typically associated with designed electrical coordination and breaker performance
- Pressure effects are highly dependent on room configuration and electrical characteristics of the event 9
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Arc Fault Class 3 (Arc Blast/HEAF)
- Arc Fault Class 3 (Arc Blast/HEAF) - Damage includes the component of origin as well as spread to surrounding equipment within the fire zone. This damage includes pressure rise effects (i.e. severe equipment deformation, thrown doors, degraded fire barriers) which potentially can effect equipment in other fire zone(s).
- These events are typically contingent with ensuing fire conditions
- Typically indicative of a level of circuit protection failure and/or design flaw allowing for extended duration arc events
- Pressure effects are highly dependent on room configuration and electrical characteristics of the event 10 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Arc Fault Classifications 11 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Electrical Enclosure Thermal fire
- Electrical Enclosure Thermal fire - A thermal fire is an electrical enclosure fire in which electrical energy does not significantly contribute to the heat release rate of the fire; rather, the heat release rate (HRR) is determined solely by the chemical energy released by combustion of cabinets contents and classical fire dynamics.
- This does not preclude a fire ignited by electricity, as long as the electricity does not significantly contribute to the ensuing heat release rate.
12 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Small-scale testing Gabriel Taylor, P.E.
Office of Nuclear Regulatory Research Division of Risk Analysis April 18, 2018 Rockville, MD NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Why small scale?
2 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
What do we expect to learn?
- Arc ejecta characteristics
- Particle size distribution
- Rates of production
- Particle composition
- Particle trajectory
- Mass loss of conductors
- Net energy contribution 3
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
How is it being accomplished?
- Sandia National Laboratories (SNL) lightning simulator
- Single phase to ground arcing between two vertical bus bars
- Particle collection and post test analysis
- High speed videography 4
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Testing apparatus 5
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Experimental Variables
- Voltage
- 0.48kV, 4.16kV, 6.9kV, 10kV
- Current
- 0.35kA to 29kA
- Duration
- 4 to 8 ms
- 100 ms may be possible
- Bus bar material
- Copper
- Aluminum 6
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Test Matrix 7
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Measurements
- Videography
- High-speed infrared (IR) imaging
- Trajectory
- Particle collection
- Aerogel plates (99.999% SiO2)
- Carbon tape
- Particle Analysis
- Energy dispersive x-ray analysis (EDXA)
- Electron energy loss spectroscopy (EELS)
- Scanning electron microscopy (SEM)
- Raman spectroscopy
- X-ray photoelectron spectroscopy 8
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Scanning Electron Microscopy Collected via aerogel substrate or carbon microscopy tape 9
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Modeling of Aluminum contribution
- Information will be used to support development of a fundamental energy balance modeling technique to account for contribution of aluminum
- Collaboration with the University of Maryland, College Park 10 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Small-scale benefits and limitations Advantages Limitations
- Measurement
- Duration proximity to arc
- Single Phase
- Cost
- Measurement
- Control of variables 11 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Federal Register
- Draft test plan issued for public comment
- www.regulations.gov
- Docket ID #: NRC-2018-0040
- Comment period closed April 4, 2018
- April 2: Magnetic field monitoring / effect of insulated bus /
parameter significance
- April 3: NEI sent a request to extend for additional 45 days
- Any comments sent to Gabriel.Taylor@nrc.gov by May 4, 2018 will be placed into ADAMS and assessed by the NRC/SNL team.
- Testing planned to start June 25th 12 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Test Matrix 13 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
14 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
PRA Modeling Implications Gabriel Taylor, P.E.
Office of Nuclear Regulatory Research Division of Risk Analysis April 18, 2018 Rockville, MD NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Existing Models NUREG/CR-6850, EPRI 1011989
- Electrical enclosure HEAF event
- Assume functional failure and physical damage
- Zone of Influence (ZOI)
- 1.5m (5 ft) vertical
- 0.9m (3 ft) horizontal
- Enduring fire
- Modeled constant with detailed fire modeling procedure (Appendix E and G) 2 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Existing Models NUREG/CR-6850, EPRI 1011989
- Segmented Bus Duct HEAF Event
- Functional failure and physical damage
- 0.46m (1.5 ft) sphere at fault location
- 30° downward cone (15° from vertical) up to max diameter of 6.1m (20 ft), i.e., 11.3m (37 ft) below fault Bus Duct 3
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Modeling Approach
- 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 4
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Bounding ZOI (Current Model)
- 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
- Lowest cost 5
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Refined Bounding ZOI
- 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 6
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Dynamic ZOI
- 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 7
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
What do we need?
- Reasonably accurate model to assess risk impact of HEAFs on plant safety Realism 8
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
IEEE/NFPA Arc Flash Collaborative Research Project Presented to the Nuclear Regulatory Commission HEAF Workshop Mark W. Earley, P.E.
Chief Electrical Engineer National Fire Protection Association Wei-Jen Lee, PhD, PE, IEEE Fellow University of Texas at Arlington ITS A BIG WORLD. LETS PROTECT IT TOGETHER.TM NFPA.ORG l © National Fire Protection Association. All rights reserved.
IEEE/NFPA Arc Flash Collaborative Research Project Presented to the Nuclear Regulatory Commission HEAF Workshop Mark W. Earley, P.E.
Chief Electrical Engineer National Fire Protection Association Wei-Jen Lee, PhD, PE, IEEE Fellow University of Texas at Arlington NFPA.ORG l © National Fire Protection Association. All rights reserved.
Who we are
- The National Fire Protection Association (NFPA) is a global nonprofit organization, established in 1896, devoted to eliminating death, injury, property and economic loss due to fire, electrical and related hazards.
- The world's leading advocate of fire prevention and an authoritative source on public safety, NFPA develops, publishes, and disseminates more than 300 consensus codes and standards intended to minimize the possibility and effects of fire and other risks.
- NFPA membership totals more than 50,000 individuals around the world.
NFPA.ORG l © National Fire Protection Association. All rights reserved.
The National Electrical Code
- Providing safety from hazards arising from the of electricity since 1897.
- First committee meeting held in 1896.
- IEEE representatives were present
- NFPA has been the sponsor since 1911 NFPA.ORG l © National Fire Protection Association. All rights reserved.
- First electrical safety standard recognized by OSHA was the 1971 National Electrical Code.
- OSHA with IEEE member support asked NFPA to consolidate electrical safety rules that affected workers into a new stand alone document that did not include all of the installation rules.
- The result was NFPA70E-Electrical Safety Requirement for Employee Workplaces (later renamed Electrical Safety in the Workplace)
NFPA.ORG l © National Fire Protection Association. All rights reserved.
NFPA70E-Electrical Safety in the Workplace
- Evolved into 4 parts (eventually reduced to three parts)
- As arc flash phenomena was introduced into NFPA70E, IEEE formed a new working group to provide a method to quantify the phenomena. This working group developed IEEE 1584
Arc Flash Research
- There were some differences of opinion between members of the IEEE committee and the NFPA committee on how to determine the hazard and how to protect workers NFPA.ORG l © National Fire Protection Association. All rights reserved.
Arc Flash Research
- Both Committees became concerned about the technical basis for arc flash analysis
- Both committees decided to separately pursue arc flash research projects
- Each committee recognized that a considerable amount of money would be needed to do a proper job
- NFPA would pursue project through the Fire Protection Research Foundation NFPA.ORG l © National Fire Protection Association. All rights reserved.
Arc Flash Research
- Both organizations were likely to seek support from the same sponsors
- It was unlikely that any sponsor would support both projects
- It was unlikely that either organization would receive enough contributions necessary to complete research
- Sue Vogel approached Mark Earley about collaboration NFPA.ORG l © National Fire Protection Association. All rights reserved.
Arc Flash Research
- The whole would be greater than the sum of the parts
- A partnership of the two organizations would be a powerful combination
- For both organizations, it was all about protecting people
- We recognized the conflicting viewpoints of committee members
- Asked Michael Callanan, Executive Director of NJATC (now the Electrical Training Alliance) to chair RTPC NFPA.ORG l © National Fire Protection Association. All rights reserved.
RTPC
- Members were told Check your guns at the door!
- RTPC membership represented various constituencies from IEEE and NFPA committees
- Developed a research plan, which formed the basis of the research project
- We had strong consensus for the research plan NFPA.ORG l © National Fire Protection Association. All rights reserved.
Accomplishments vs. Initial Plans The Research and Testing Planning Committee Members
- Mike Callanan, Chair
- George Gregory
- Daleep Mohla, Vice Chair
- Ray Jones
- Allen Bingham
- Mike Lang
- Jim Cawley
- Bruce McClung
- David Dini
- David Pace
- Dan Doan
- Vince Saporita
- Paul Dobrowski
- David Wallis
- Mike Doherty
- Craig Wellman
- Dick Doughty
- Kathy Wilmer
- Jim White
Project Goal
- Primary objective was to work together collaboratively so that we could obtain the maximum synergies of our diverse constituencies with the goal of protecting people.
NFPA.ORG l © National Fire Protection Association. All rights reserved.
IEEE-NFPA Collaboration Project Sponsors
- Silver (contd)
- Bruce Power - Cadick Corporation
- Cooper Bussmann/Eaton - DCM Electrical Consulting Services
- Ferraz Shawmut (Mersen) - Duke Energy Foundation
- Square D/Schneider Electric - e-Hazard
- Underwriters Laboratories - Inter-National Electrical Testing Association
- Hydro One - NFPA
- Procter & Gamble, Inc - Powell Electric
- Salisbury
- Silver - SKM System Analysis, Inc.
- ArcFlashForum.com
- Arc Wear
- Brainfiller.com 14
Historical Perspective
- Formation of Collaboration (2003-2006)
- Circumstances (Challenges to the status quo)
- Goals
- RTPC
- Fundraising
- Initial Research period (2007-2008)
- Gammons Research and PKs Work
- Testing period and initial model (2008-2012)
- Lee and His teams Work
- Model handoff & refinements (2013-2016)
- Lee and P1584 Task Groups Work NFPA.ORG l © National Fire Protection Association. All rights reserved.
Accomplishments vs. Initial Plans Priorities: IEEE/NFPA Test Procedures and Protocols (TPP) Ad Hoc Committee 2/2/2006 Report
- TPP recommended
- Hiring of a Test Program Project Manager
- Contracting with a Research Manager
- Establishment of a Test Program Advisory Committee (TPAC).
- List of Tests
- Over 2000 test set-ups that were integrated from RTPC task groups
- LV & MV AC tests and DC tests
- Tests with protective devices that were omitted in the RTPC Report
- Cost projections - $6.5M
- 500 laboratory testing days at $5000 per day $2.5M
- Personnel costs including travel $1.7M
- Equipment costs $0.7M
- Other
- Test program 2-1/2 years - complete by 2009
- Engineering based model by 2012
- Program to get used equipment NFPA.ORG l © National Fire Protection Association. All rights reserved.
NFPA.ORG l © National Fire Protection Association. All rights reserved.
Accomplishments vs. Initial Plans Summary of the Tests Voltage Current Gap Number Enclosure (H x W x D) kV kA Mm (Inch) of Tests mm x mm x mm (in x in x in) 0.208 2.5 - 20 6.35 (0.25) - 19.05 67 355.6 x 304.8 x 203.2 (14 x12 x 8)
(0.75) 203.2 x 152.4 x 152.4 (8 x 6 x 6) 0.24 20 - 41 12.7 (0.50) - 25.4 (1.0) 25 355.6 x 304.8 x 203.2 (14 x12 x 8) 0.3 20 - 60 25.4 (1.0) - 38.1 (1.5) 24 355.6 x 304.8 x 203.2 (14 x12 x 8) 0.311 17 - 26 6.35 (0.25) - 12.7 (0.5) 11 355.6 x 304.8 x 203.2 (14 x12 x 8) 0.48 0.5 - 80.2 10 (0.4) - 50.8 (2.0) 369 508 x 508 x 508 (20 x 20 x 20) 0.575 40 25.4 (1.0) - 38.1 (1.5) 21 508 x 508 x 508 (20 x 20 x 20) 0.60 0.5 - 37 12.7 (0.5) - 101.6 (4.0) 375 508 x 508 x 508 (20 x 20 x 20) 2.7 0.5 - 33 38.1 (1.5) - 114.3 (4.5) 293 660.4 x 660.4 x 660.4 (26 x 26 x 26) 2.97 37 - 40 38.1 (1.5) 32 660.4 x 660.4 x 660.4 (26 x 26 x 26) 914.4 x 914.4 x 914.4 (36 x 36 x 36) 3.90 60 - 65 38.1 (1.5) 18 660.4 x 660.4 x 660.4 (26 x 26 x 26) 914.4 x 914.4 x 914.4 (36 x 36 x 36) 4.16 20 - 63 38.1 (1.5) - 76.2 (3.0) 184 660.4 x 660.4 x 660.4 (26 x 26 x 26) 14.3 0.5 - 42 76.2 (3.0) - 152.4 (6.0) 274 914.4 x 914.4 x 914.4(36 x 36 x 36) 0.253 (1-Ph) 5.0 - 23 6.35 (0.25) - 19.05 41 Faraday Cage (0.75) 12 2.3 - 9.1 254 (10) 136 Real Equipment 0.6 1.6 - 33 22 Real Equipment NFPA.ORG l © National Fire Protection Association. All rights reserved.
Publications during Project
- Arc Flash Visible Light Intensity as Viewed from Human Eyes, Shiuan-Hau Rau, Zhenyuan Zhang, Wei-Jen Lee, and David A. Dini, IEEE Transactions on Industry Applications. September/October 2017
- 3D Magnetohydrodynamic Modeling of DC Arc in Power System, Shiuan-Hau Rau, Zhenyuan Zhang, and Wei-Jen Lee, IEEE Transactions on Industry Applications. Volume: 52, No. 6, November/December 2016
- DC Arc Model Based on 3D DC Arc Simulation, Shiuan-Hau Rau, Wei-Jen Lee, IEEE Transactions on Industry Applications. November/December 2016.
- Arc Flash Pressure Measurement System Design, Zhenyuan Zhang, Shiuan-Hau Rau, Wei-Jen Lee, Tammy Gammon, and Ben Johnson, IEEE Transactions on Industry Applications. November/December 2016
- Arc Flash Light Intensity Measurement System Design, Wei-Jen Lee, Zhenyuan Zhang, Shiuan-Hau Rau, Tammy Gammon, Ben Johnson, and James Beyreis, IEEE Transactions on Industry Applications. September/October 2015.
- Grounding and Isolation of Sensitive Measurement Equipment for Arc Flash Testing at High Power Lab, Zhenyuan Zhang, Wei-Jen Lee, and David A. Dini, IEEE Transactions on Industry Applications. November/December 2015.
- Arc Flash Hazards, Incident Energy, PPE Ratings and Thermal Burn Injury - A Deeper Look, Tammy Gammon, Wei-Jen Lee, Zhenyuan Zhang, Ben Johnson. IEEE Transactions on Industry Applications. September/October 2015.
- Electrical Safety, Electrical Hazards & the 2018 NFPA 70E: Time to Update Annex K?, Tammy Gammon, Wei-Jen Lee, Zhenyuan Zhang, and Ben Johnson, IEEE Transactions on Industry Applications. July/August 2015.
- "Arc Flash and Electrical Safety," Wei-Jen Lee, Tammy Gammon, Zhenyuan Zhang, Ben Johnson, James Beyreis. 2013 Protective Relay Engineers Conference.
NFPA.ORG l © National Fire Protection Association. All rights reserved.
Publications during Project
- Redeveloping the 2018 NFPA 70E Annex K and Contemplating Beyond, Tammy Gammon, Wei-Jen Lee, Zhenyuan Zhang, Ben Johnson, James Beyreis. 2015 ESW.
- Electrical Safety, Electrical Hazards & the 2018 NFPA 70E, Time to Update Annex K? Tammy Gammon, Wei-Jen Lee, Zhenyuan Zhang, Ben Johnson. IEEE Transactions on Industry Applications. July/August 2015..
- Addressing Arc Flash Problems in Low Voltage Switchboards: A Case Study in Arc Fault Protection, Bruce Land, Tammy Gammon. 2014 ICPS.
- IEEE / NFPA Collaboration on Arc Flash Phenomena Research Project, Wei-Jen Lee, Tammy Gammon, Zhenyuan Zhang, Ben Johnson, Sue Vogel. 2012 PES Trans. & Distrib. Expo.
- Comparative Study of Arc Modeling and Arc Flash Incident Energy Exposures Ravel Ammerman, Tammy Gammon, P.
K. Sen, John Nelson. 2008 PCIC.
- IEEE 1584-2002 Arc Modeling Debate, Tammy Gammon, John Matthews. 2008 IAS Magazine.
- Modeling High-Current Electrical Arcs: A Volt-Ampere Characteristic Perspective for AC and DC Systems, Ravel Ammerman, P. K. Sen. 2007 North American Power Symposium.
- Arc Flash Hazard Incident Energy Calculations a Historical Perspective and Comparative Study of the Standards:
IEEE 1584 and NFPA 70E, Ravel Ammerman, P. K. Sen, John Nelson. 2007 PCIC.
NFPA.ORG l © National Fire Protection Association. All rights reserved. 20
DC Work To Date
- Bruce Power Test Results
- IEEE papers documenting research into DC arcs.
- 3D Magnetohydrodynamic Modeling of DC Arc in Power System, Shiuan-Hau Rau, Zhenyuan Zhang, and Wei-Jen Lee, IEEE Transactions on Industry Applications. Nov/Dec 2016
- DC Arc Model Based on 3D DC Arc Simulation, Shiuan-Hau Rau, Wei-Jen Lee, IEEE Transactions on Industry Applications. Volume: 52, No. 6, November/December 2016.
- A Review of Commonly Used DC Arc Models, Tammy Gammon, Wei-Jen Lee, Zhenyuan Zhang, Ben Johnson. 2014 PPIC.
- DC Arc Models and Incident Energy Calculations Ravel Ammerman, Tammy Gammon, P. K. Sen, John Nelson, 2009 PCIC
- Theoretical DC Simulation Model Development NFPA.ORG l © National Fire Protection Association. All rights reserved.
Steering Committee Members -2018
- Mark Earley NFPA
- Mike Lang Mersen
- John Kovacik Underwriters Lab
- Sam Sciacca IEEE-SA
- Alan Manche Schneider-Electric
- Daleep Mohla DCM Consulting
- Tom Domitrovich Eaton
- Jim Phillips Brainfiller
- Wei-Jen Lee University of Texas at Arlington 22 22
23 Moving Forward for a Comprehensive DC Arc Flash Model Development NFPA.ORG l © National Fire Protection Association. All rights reserved.
Factors to be Considered
- Voltage and Current Ranges
- Configurations (In-line or parallel)
- Gaps
- Materials NFPA.ORG l © National Fire Protection Association. All rights reserved. 24
Hypothesis and Proposed Approaches
- Hypothesis
- Incident energy is proportional to the arc energy during the arc flash event
- It is possible to establish the relationship and use AC arc flash model for DC incident energy and arcing current estimation
- Scouting Test
- Based upon the input from steering committee, design a 3-4 days scouting test.
- If possible, it will be great to run both AC and DC arc flash test with the identical configurations.
NFPA.ORG l © National Fire Protection Association. All rights reserved. 25
Proposed Approaches
- Preliminary Study
- According to the test configurations, perform computer simulations to obtain estimated arcing current, arcing voltage, and arc energy
- Comparison among DC, AC and computer simulation results
- Does the hypothesis hold and computer simulation yield reasonable results?
- Can we establish the relationship between DC arc flash test results and its AC counterpart?
NFPA.ORG l © National Fire Protection Association. All rights reserved. 26
Proposed Approaches
- Based Upon the Findings of the Preliminary Study
- If the Preliminary Study shows positive results
- Design additional DC laboratory testing
- Perform DC simulations
- Establish the relationship and use AC arc flash model for DC incident energy and arcing current estimation
- Develop DC incident energy and arcing current estimation models
- If the Preliminary Study is unable to establish the link to the AC arc flash model NFPA.ORG l © National Fire Protection Association. All rights reserved. 27
Accomplishments vs. Initial Plans Deliverables and Accomplishments
- 10 AC Models integrated into 1
- 5 electrode test configurations
- LV and MV AC
- Tests and report on arc sustainability at 208V
- Tests and report on arc flash in real equipment
- Development of Instrumentation for
- Thermal
- Light
- Pressure
- Sound
- Portable Instrumentation Unit
- Several IEEE Papers
Conclusion
- The mission of the collaboration was to develop ONE model that ensures worker safety that can be consistently used across the electrical industry.
- We have a working ac model.
- We need to explore the lower boundary
- The next step is correlation of the dc model with the ac model.
NFPA.ORG l © National Fire Protection Association. All rights reserved.
EPRI Perspective High Energy Arcing Faults Ashley Lindeman Senior Technical Leader HEAF Information Sharing Workshop April 18, 2018
© 2018 Electric Power Research Institute, Inc. All rights reserved.
White Papers on HEAF 3002011922 - Characterization of Testing and Event Experience for High-Energy Arcing Fault Events 3002011923 - Nuclear Station Electrical Distribution Systems and High-Energy Arcing Fault Events White papers are publicly available at epri.com 2
© 2018 Electric Power Research Institute, Inc. All rights reserved.
Electrical System Distribution System Configurations Identified 7 common EDS configurations and relative generator-fed HEAF risk
- Ranked designs most vulnerable to least vulnerable
- Reviewed 19 U.S. NPP sites 14 of 19 sites have low risk (designs 5 through 7) 3
© 2018 Electric Power Research Institute, Inc. All rights reserved.
Unit-Connected Designs Power system downstream of the main generator is worthy of special attention Refers to the operational configuration of the (1) main generator, (2) GSU transformer, (3) generator output switchyard breakers, (4) AT, and (5) associated buses and connections, with no generator circuit breaker and no thus backup circuit breaker(s) to isolate a generator-fed fault if the (1) AT secondary side breaker failed to open (that is, is stuck) or is slow to open or (2) a fault exists between the generator and GSU transformer, or anywhere in the auxiliary transformer to the first low-voltage side circuit breakers.
4
© 2018 Electric Power Research Institute, Inc. All rights reserved.
Unit-Connected Designs OPEX has revealed that a main generator can feed a HEAF for several seconds following a unit trip if a fault originates in the unit-connected design
- Some plant have a generator breaker that can isolate the energy source (main generator) from the fault during generator coast-down before the voltage collapses The events impacted only non-Class 1E equipment in non-Class 1E locations in the medium-voltage range
- Post-event fire occurred in all instances
- In 8 of 9 events damage was observed outside equipment of origin
- Events caused significant damage and were challenging 5
© 2018 Electric Power Research Institute, Inc. All rights reserved.
EPRI Characterization of Testing and Experience Performed detailed review of HEAF events at U.S. NPPs
- 1980 through 2017 Event review indicates:
- HEAF events represent ~2% of fires within the U.S. NPP fleet
- Wide variety in severity of events Not all HEAFs result in post-event fire Most HEAF events damage only the equipment suffering failure
- Several notable influence factors
- Metrics indicate refinements to both HEAF frequencies and HEAF zones of influence are appropriate and defensible based on objective data 6
© 2018 Electric Power Research Institute, Inc. All rights reserved.
Key Influence Factors Greater than 90% of documented HEAFs occurred on non-safety related equipment Less than 15% of HEAFs occurred at equipment operating at less than 1,000 volts 7
© 2018 Electric Power Research Institute, Inc. All rights reserved.
Key Influence Factors 2/3 of HEAF events did not impact equipment beyond equipment of origin About 2/3 of HEAF events resulted in a post-event fire 8
© 2018 Electric Power Research Institute, Inc. All rights reserved.
Key Influence Factors Contrary to conventional wisdom, no one equipment type is a dominant source of HEAF events 65% (or more) of HEAFs involved preventable shortcomings (human error, maintenance, design, installation/construction) 9
© 2018 Electric Power Research Institute, Inc. All rights reserved.
Key Influence Factors Nearly 1/3 of HEAF events are associated with Unit Connected designs
- Main generator is not immediately isolated from faulted equipment
- Fault allowed to persist for extended time while generator coasts down and excitation field decays 10
© 2018 Electric Power Research Institute, Inc. All rights reserved.
Characterization of HEAF Events Experimental insights
- Tests assumed that overcurrent protection is absent or failed In the absence of protection, electrical faults may persist for several seconds, resulting in violent energy release
- Testing characterized the most severe consequences for extended-duration three-phase faults
- OPEX confirms that most HEAF events will be interrupted by overcurrent protection and thus the fault energies would be lower 11
© 2018 Electric Power Research Institute, Inc. All rights reserved.
Characterization of HEAF Events - Experimental Insights Low-voltage testing
- Arcs did not always sustain
- Tests with durations shorter than 2 seconds did not result in fires
- The threshold arc energy to ignite cables was ~28 MJ Medium-voltage testing
- Energy threshold higher than low-voltage
- Once initiated, arcs sustained themselves for a longer time
- Variety of damage observed External ruptures Breaches between compartments 12
© 2018 Electric Power Research Institute, Inc. All rights reserved.
Involvement of Aluminum NUREG/IA-0470 and NEA/CSNI/R(2017)7 highlight aluminum oxidation phenomena as a significant contributor to total energy released for test in which reaction present
- In the most severe NUREG/IA-0470 test, the researchers estimated the energy release from the oxidation was 2.6 times the energy release by the arc
- The estimated ratio of oxidation to arc energy varies between 0.34 - 2.6, so scenarios with high oxidation were less common Aluminum oxidation phenomena not considered in standards such as IEEE 1584, IEEE C37.20.7-2007, NFPA 70E
- May not have included aluminum electrodes, test of shorter duration (<0.5s) result in less melting of conductors The threshold at which the aluminum oxidation occurs is undefined
- Phenomena not observed in all tests with aluminum components
- Aluminum oxidation observed in test conditions imposing severe arcing methods (i.e.,
extended duration faults beyond the rating of switchgear and breakers) 13
© 2018 Electric Power Research Institute, Inc. All rights reserved.
Fire PRA Treatment Refine HEAF ignition frequencies / scenario definition
- Update ignition frequencies for Bins16.a, 16.b, 16.1, and 16.2
- Create new bins or sub-divide existing ignition frequency bins based on new data analysis:
Sub-groups Split fractions
- Data supports numerous sub-groups Safety-related vs. non-safety related Low voltage vs. medium/high voltage (existing)
Damage limited to enclosure vs. consequential damage Post-event fire vs. no fire Design vulnerabilities (e.g., unit-connected designs, protection schemes) 14
© 2018 Electric Power Research Institute, Inc. All rights reserved.
Fire PRA Treatment Sensitivity of Fire PRA results to aluminum oxidation
- Sensitivity of CDF and LERF will be plant and configuration dependent
- Plants with safety-related switchgear in separate rooms will show lower impact Sample sensitivity study was conducted
- Sample plant had safety-related switchgear in separate rooms
- Impact was minimal Assumed aluminum oxidation failure mode rendered all equipment in room non-functional Current fire modelling of switchgear rooms most always involves a HGL HGL typically impacts all (or most) equipment in the room HGL and aluminum failures produce similar functional impact for the room Plant configurations with multiple trains of equipment in same room was not included in sample sensitivity study 15
© 2018 Electric Power Research Institute, Inc. All rights reserved.
Summary HEAFs are both a safety and economic consideration
- Severe HEAF event could easily keep a plant off-line for months Testing highlights the importance of optimizing overcurrent protection such that HEAF events are rapidly detected and cleared Proper maintenance is prevention
- Strong PM and test program is important element in preventing HEAF events
- 3002011923 identifies several preventative maintenance, refurbishment, testing, and walkdowns to ensure proper operation of equipment / electrical distribution system 16
© 2018 Electric Power Research Institute, Inc. All rights reserved.
TogetherShaping the Future of Electricity 17
© 2018 Electric Power Research Institute, Inc. All rights reserved.
ENERGY Physical Testing & Failure Rates NRC HEAF Phase II Information Sharing Workshop, April 18 & 19 Bas Verhoeven Director Global Business Development and Innovation - KEMA Laboratories 1 DNV GL © 2015 17 April 2018 SAFER, SMARTER, GREENER
Table of content Introduction KEMA Laboratories Certification, the global approach Statistics on failure rate during type testing Summary and takeaways Disclaimer: All photographs/pictures used by KEMA Laboratories in this presentation are for illustrative purposes solely. The pictures/photographs do not in any way relate to the (failure of) component, products and/or manufacturer shown on the pictures/photographs.
2 DNV GL © 2015
Introduction in KEMA Laboratories 3 DNV GL © 2015
DNV GL, A global quality assurance and risk management company 4 DNV GL © 2015
Industry consolidation 5 DNV GL © 2015
Global reach - local competence 150+ 100+ 100,000+ 12,500 years countries customers employees 6 DNV GL © 2015
Our vision: global impact for a safe and sustainable future MARITIME OIL & GAS ENERGY BUSINESS DIGITAL ASSURANCE SOLUTIONS TECHNOLOGY & RESEARCH 7 DNV GL © 2015
KEMA Laboratories Prague, CZ Arnhem, Netherlands Chalfont, USA 8 DNV GL © 2015
High Power Laboratory - Operating Principle 9 DNV GL © 2015
Power rating of KEMA Laboratories Location Generators Can be Max. Power Accreditation grouped Arnhem, NL 6 x 2,500 MVA Yes 15,000 MVA ISO/IEC 17025 by RvA Chalfont, US 1 x 2,250 MVA No 2,250 MVA ISO/IEC 17025 by A2LA 1 x 1,000 MVA Prague, CZ 2 x 2,500 MVA Yes 5,000 MVA ISO/IEC 17025 by CAI Required power for testing depends on components and type of test:
- Power Transformers, high power
- Circuit breakers, medium power (synthetic testing)
- (Internal) Arc, low to medium power 10 DNV GL © 2015
KEMA Laboratories - Beyond the Standards Commercial Grade Dedication
- KEMA Laboratories are accredited by A2LA in accordance with international standard ISO/ IEC 17025:2005. Our quality program, our accreditation and the NRCs endorsement of NEI14-05 simplifies the commercial grade dedication process.
- NRCs Expectations
- Licensees and vendors must follow their commercial grade dedication process when using the International Laboratory Accreditation Cooperation (ILAC) accreditation alternative for procurement of commercial calibration and testing services.
- Licensees and vendors may use the alternative method in lieu of performing a commercial grade survey as part of the dedication process.
U.S. NRC, Safety Evaluation Report (SER), NRC conditions and expectations.
11 DNV GL © 2015
Certification, the Global Approach 12 DNV GL © 2015
Risk mitigation through equipment certification Ensures performance criteria are met Equipment Ensures highest level of service reliability certification Minimizes liability issues Best Independent laboratory (STL) outside country practice in of equipment manufacturer certification Quality starts early in the process and must be written in the specifications.
FAT and SAT to check quality with initially type tested object.
13 DNV GL © 2015
Short Circuit Test Liaison (STL)
GENERAL The Short-Circuit Testing Liaison (STL) provides a forum for voluntary international collaboration between testing organizations.
The basic aim is the harmonized application of IEC and Regional Standards for the type testing of electrical power equipment.
Note: STL is concerned with high voltage electrical transmission and distribution power equipment (i.e. above 1000Vac and 1200Vdc) for which the type tests specified in Standards include short-circuit and dielectric verification tests.
www.Stl-liaison.org 14 DNV GL © 2015
STL Members 15 DNV GL © 2015
Certification - how the majority of the world sees it Independent type test and certification of the functional performance of a T&D component based on an international accepted standard. Standards normally have a section of clauses for Type or Design Tests. Other sections are for production tests; Routine and Sample.
Utilities require a Certificate upfront at tendering process and/or during delivery to ensure that the component has proven that it meets the functional requirements.
Certification = Mitigation of risk by levelling the procurement playing field Note; liability of the component tested (certified) remains at the manufacturer and is not transferred to the certifying body.
16 DNV GL © 2015
Can computer modelling replace testing?
Models are well accepted in the design phase of equipment for the calculation of stresses for example electrical, mechanical, pressure, thermal etc.
CIGRE has investigated the possibility to replace testing by modelling and concluded that withstand of stresses cannot be predicted by models.
The CIGRE survey showed that, from all LPT having failed in service due to a short circuit, one third passed a design review successfully. None underwent a real test.
17 DNV GL © 2015
Power System Reliability and Failures 18 DNV GL © 2015
Equipment failures causes blackouts USA 2016 (n = 3.879)
Most avoidable outages are equipment related Source: Eaton Corporation, Blackout Tracker USA Annual Report 2016 19 DNV GL © 2015
Number of outages increase over the years Number of outages in Equipment failure / human (Eaton Corp.)
Interconnection of power networks improves network performance but increases short circuit current level.
Increase of switching actions for dealing with all network conditions and occurring events.
Networks have higher loading profile with more dynamics.
Source: Eaton Corporation, Blackout Tracker USA Annual Reports 20 DNV GL © 2015
Cigre Organization Founded in 1921, CIGRE, the Council on Large Electric Systems, is an international non-profit Association for promoting collaboration with experts from all around the world by sharing knowledge and joining forces to improve electric power systems of today and tomorrow.
www.cigre.org 21 DNV GL © 2015
Large Power Transformers 2015 CIGRE study 1 out of 200 transformers runs into a major failure per year Available for free at https://e-cigre.org/publication/642-transformer-reliability-survey 22 DNV GL © 2015
Large Power Transformers 2015 CIGRE study 11,62% of failures are caused by external short-circuit 23 DNV GL © 2015
EPRI (USA) database of > 20.000 power transformers (start 2006) inadequate short-circuit strength 24 DNV GL © 2015
How Often do Faults Occur?
Number of faults per 100 km overhead line per year CIGRE 13.08 Study:
- 900.000 circuit breaker years 20
- 70.000 km overhead lines 18 average 90percentile 16 14 Wide regional variations: 12
- Global average: 1.7 faults per year 10 on an overhead line 8
- 90th percentile: 3.3 faults per year 6
on an overhead line 4
- Lower voltage systems suffer 2
more faults
- 90% of faults happen in overhead lines 0
< 100 100-200 200-300 300-500 500-700 700 or cable system voltage class 25 DNV GL © 2015
Statistics on Failure Rate during Type Testing 26 DNV GL © 2015
Around 25% of test-objects initially fail to pass type-tests Line trap Disconnector Switchgear panel Broken bushing Line trap Distribution transformer Oil spill 27 DNV GL © 2015
Initial failure rate large power transformers > 20 MVA Number of large power transformers tested over the years (KEMA Laboratories) n=344 Average 22%
28 DNV GL © 2015
29 DNV GL © 2015 Forces between conductors Axial and radial force arises because current carrying conductors are inside a magnetic field i1 i2 i1 F
i2 i1 F
Lorentz-force: =
2 a F F x i2 Equal polarity: attraction Opposite polarity: repulsion Fr For windings i2= i1, so forces depend quadratically on current amplitude(!) Fr Fa i
30 DNV GL © 2015
Relationship between current and force in a transformer 20 10 Current [pu]
Irated 0
-10 Short-circuit at Isc sym voltage
-20 maximum
-40 -20 0 20 40 60 80 100 400 F - Isc asym pulsating force!
Force [pu]
300 200 F - Isc sym 100 F - Irated 0
-40 -20 0 20 40 60 80 100 Time [ms]
31 DNV GL © 2015
Short-circuit forces on a winding transposition between layers video Vibrations caused by dynamic stresses Axial & radial forces on reactor are huge, especially at transposition between layers Pulsating forces at 100 Hz cause severe stresses to windings of transformers and reactors 32 DNV GL © 2015
Can design review replace short-circuit testing?
Calculation methods are only based on static forces and do not cover all parts of the transformer. Following aspects are not/cannot be addressed fully:
- cross overs of turns (inside the winding)
- transpositions of parallel conductors (inside the winding)
- exit leads of the windings (fixation to prevent movement and friction (wear of insulation) of exit lead)
- support of cleats and leads
- connections to OLTC
- support of leads to bushings
- stability of the radial support of windings (for example spacers used during winding the coil (untreated, dried, dried and oil impregnated)
- effect of varying densities of the different windings due to axial compressing forces
- dynamic pressure build up and movement of the oil Types of failures in the laboratory prove that calculation/modelling are inadequate 33 DNV GL © 2015
IEC 60076 and IEEE Std C57.12.90
- IEC allows the ability to withstand the dynamic effects of short circuit to be tested or calculated.
- The revised versions of IEEE and IEC standards only allow testing, no calculations anymore. To be published 2019
- Short circuit tests do not harm or age a transformer. (In normal applications, a transformer sees 10 to 15 short-circuits per year with 80 % or more currents.)
34 DNV GL © 2015
Large power transformers Large power Produced as a Several utilities in Verification by transformers are single component or the world require design review or unique for a specific in small batches short circuit testing calculation is not application in a of large power sufficient and network transformers statistics prove why 35 DNV GL © 2015
Initial failure rate distribution transformers Distribution transformers per power rating (KEMA Laboratories) 36 DNV GL © 2015
Initial failure rate cast resin transformers Cast resin transformers (KEMA Laboratories) 37 DNV GL © 2015
Initial failure rate cable and accessories Medium and High Voltage cables and accessories (KEMA Laboratories) 904 samples tested between 1993 and 2017 38 DNV GL © 2015
Examples of cable accessory failures Mechanical deformation Tracking and erosion insulator shed 39 DNV GL © 2015
Initial failure rate cables and accessories Medium Voltage (KEMA Laboratories) High Voltage (KEMA Laboratories) 40 DNV GL © 2015
Initial failure rate circuit breakers - PRELIMANARY RESULTS HV switchgear (KEMA Laboratories) n = 1.268 samples 2013-2015, 145 kV / 40 kA 454 test series, 115 failed (25%)
Failure rate (72.5 - 800 kV) is 28%
Issues: population size, few poor designs shall not dominate, ..
More work is needed 41 DNV GL © 2015
Internal arc test on MV switchgear Deflector plate Diversion channel Internal arc test on low and medium voltage switchgear is important for safety of workers.
High attention internationally due to (serious) injuries to workers and potential liability for utilities.
IEEE and IEC for test on internal arc protection wide used.
Statistical data from KEMA not yet available. Indication, is again a 25%
initial failure rate.
42 DNV GL © 2015
Carrying out the test Cotton indicators mimic workers clothing exhaust room simulation front indicators lateral indicators 43 DNV GL © 2015
Successful 63 kA test 44 DNV GL © 2015
Failed3 kA test 45 DNV GL © 2015
Passed 46 DNV GL © 2015
Initial failure rate HV disconnector and earthing switch HV Disconnectors and Earthing Switch (KEMA Laboratories) 47 DNV GL © 2015
Initial failure for power arc on insulator strings Successful tests 109 Failures 57 Failure rate 34%
48 DNV GL © 2015
Takeaways Initial failure rate of type testing is 25% for all T&D components. Failure rate stays stable over the years, despite better materials, knowledge, modelling and production techniques. Business tendencies that drive this are:
Build more compactly Reduce usage of materials Market competition and price pressure Statistics and experience in testing shows that nothing can replace physical testing. Modelling and calculation is an important designer tool not a conclusive verification tool Physical testing to a certain pre-defined standard or to a specific customer situation, is the only true test 49 DNV GL © 2015
Disclaimer: All photographs/pictures used by KEMA Laboratories in this presentation are for illustrative purposes only. The pictures/photographs do not in any way relate to the (failure of) component, products and/or manufacturer shown on the pictures/photographs.
Bas Verhoeven bas.verhoeven@dnvgl.com
+31 6 15 06 03 55 www.dnvgl.com SAFER, SMARTER, GREENER 50 DNV GL © 2015
Review of Phase II Draft Test Plan High Energy Arc Faults Involving Aluminum Nick Melly Office of Nuclear Regulatory Research Division of Risk Analysis April 19, 2018 Rockville, Maryland NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Objectives
- Phenomena Identification and Ranking Table (PIRT)
Result
- Experimental variables
- Measurement
- Phase 2 OECD Members
- Test Structure
- Experimental Approach
- Phase 2 Timeline NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018 2
PIRT Phenomena of High Importance
- Cabinet-to-cabinet fire spread and secondary arcs in cabinet lineups
- Thermal damage criteria and target sensitivity for short, high heat exposures
- Likelihood and severity of secondary fires
- Performance of HEAF shields
- Likelihood and severity of damage from arc ejecta on electronic equipment
- Metal oxidation
- Arc electrical characterization NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018 3
HEAF Phase 2 Focused Variable changes
- Arc current
- Arc current was identified as a primary impact to total energy released
- Two currents will be selected for both low and medium voltage enclosures; this current will be selected based upon feedback from needs and objectives document of typical system electrical line-ups and fault capacities (focus of later discussion)
- Arc Duration
- Arc duration was identified as a primary impact to total energy released
- Two durations will be selected for both low and medium voltage enclosures; the durations will be selected to make 1 to 1 comparisons between tests; nominally 2, 4 and 8 seconds
- Bus ducts- 1,3,5 seconds
- These values correspond with the KEMA electrical capabilities (focus of later discussion)
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018 4
HEAF Phase 2 Focused Variable changes
- Material Property
- Electrical Enclosure Conductor Material
- Bus Ducts
- Steel Enclosure; Copper Conductor
- Steel Enclosure; Aluminum Conductor NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018 5
HEAF Phase 2 Focused Variable changes Potential Variable Potential Values Equipment Type Cabinet, Bus Duct Bus bar material Aluminum, Copper Bus duct material Steel, Aluminum Voltage 480 V, 4160V, 6900 V (workshop discussion)
Current I1, I2 (workshop discussion)
Frequency 60 Hz Power configuration Delta, Wye (workshop discussion)
Equipment grounding Grounded, Ungrounded (Floating)
Arc duration 100 ms to 8s (workshop discussion)
Arc Energy Dependent on other variables Arc location (workshop discussion)
Bus bar insulation Insulated, Uninsulated Bus bar spacing (arc length) (workshop discussion)
Bus bar size (workshop discussion)
Bus bar thickness (workshop discussion)
Enclosure thickness (workshop discussion)
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018 6
HEAF Phase 2 Measurement
- Measured Parameters
- Temperature and Heat Flux
- Both parameters will be modeled at multiple distances away from the arc point
- Will aid in a dynamic ZOI creation
- 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)
- 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 (to be tested for damage and electrical continuity)
- Byproduct Testing
- Conductivity measurements for aluminum deposited on surfaces
- Spectroscopy
- Heat Release Rate (HRR) will not be measured during experiments based on lessons learned in phase 1 testing NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018 7
HEAF Phase 2 Measurement Measurement Device Temperature Thermocouple (TC), Plate Thermometer (PT), IR imaging Heat flux (time-varying) Plate Thermometer (PT)
Heat flux (average) Plate Thermometer (PT), Thermal Capacitance Slug (Tcap Slug)
Incident energy Slug calorimeter (slug)
Cabinet internal pressure Piezoelectric pressure transducer Compartment internal Piezoelectric pressure transducer pressure Arc plume / fire Videography, IR filter videography, IR imaging dimensions Surface deposit analysis Energy dispersive spectroscopy, electron backscatter diffraction NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018 8
OECD -Phase II HEAF Expected Members
- Belgium-
- Japan
- The Federal Agency for
- Central Research Institute of Nuclear Control (FANC)
Electric Power (CRIEPI)
- Canada-
- Japan
- Canadian Nuclear Safety
- Japan Nuclear Regulatory Authority Commission (CNSC)
(NRA)
- Czech Republic
- Netherlands
- State Office for Nuclear Safety
- The Authority for Nuclear Safety (SÚJB) and Radiation Protection (ANVS)
- France
- Spain
- The Institut de Radioprotection
- Consejo de Seguridad Nuclear et de Sûreté Nucléaire (IRSN)
(CSN)
- France
- Electricité de France (EDF)
- United States Nuclear Regulatory
- Germany Commission (USNRC)
- Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) mbH
- Korea (Republic of)
- Institute of Nuclear Safety (KINS)
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018 9
HEAF Phase 2 Test Structure-Enclosures Enclosure Testing Copper Bus Bars Aluminum Bus Bars 480 Volt 6900 Volt 480 Volt 6900 Volt 15kA 25kA 25kA 35kA 15kA 25kA 25 kA 35 kA 4s 4s 8s 4s 4s 8s 2s 4s 4s 2s 4s 4s 4s 4s 8s 4s 4s 8s 2s 4s 4s 2s 4s 4s 2s 2s A B C D E F G H I J K L M N O P Q R S T U V W X *
- Legend OECD Test Contribution U.S. Specific Supplemental Testing driven by GI Program Undetermined Tests to explore unanticipated results/enhance repetition NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018 10
HEAF Phase 2 Test Structure- Bus Ducts Bus Duct Testing 4160 Volt /
25 kA Copper Bus Copper Bus Aluminum Bus Aluminum Bus Steel Enclosure Aluminum Enclosure Steel Enclosure Aluminum Enclosure 1s 3s 1s 3s 1s 3s 1s 3s 5s 5s A B C D E F G H *
- Legend OECD Test Contribution U.S. Specific Supplemental Testing driven by GI Program Undetermined Tests to explore unanticipated results/enhance repetition NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018 11
HEAF Phase 2 Experimental Approach
- Limit Test variables to understand the importance of specific variables on the severity of the HEAFs
- create a dynamic model based on scenario specific factors
- Repeatable arc location and plasma ejection direction
- repeatable tests using the same enclosure configurations
- Instrumentation will be the primary means of data collection at multiple distances from the HEAF origin
- No cable trays or external combustibles will be used
- No testing to be performed will subject any equipment to conditions that exceed equipment ratings.
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018 12
HEAF Phase 2 Experimental Approach Enclosures Bus Ducts NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018 13
Timeline of NRC Phase II actions
- Public Comment Period Closes................................................ September 2, 2017 (Completed)
- OECD Comment Period...................................... August 31 / September 15, 2017 (Completed)
- OECD HEAF Meeting................................................................. October 12, 2017 (Completed)
- HEAD Workshop ......................................................................... April 18-19, 2018 (On Going)
- OECD HEAF Meeting....................................................................... April 23, 2018
- Comment Resolution ....................................................................... May 11, 2018
- Final Test Plan.................................................................................. May 11, 2018
- Signed International Agreement ..............................Summer 2018 (Target)
- Equipment Delivery...................................................................................Fall 2018
- Initial Test Series............................................................................... October 2018
- Second Series of Tests (To correspond w/ International OECD Meeting)................................. Spring 2019
- Remaining Tests................................................................................... 2019/ 2020 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018 14
15 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Review of Phase II Draft Test Plan Comments High Energy Arc Faults Involving Aluminum Nick Melly Office of Nuclear Regulatory Research Division of Risk Analysis April 19, 2018 Rockville, Maryland NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Phase II Draft Test Plan
- Official Public Comment Period
- Organisation for Economic Co-operation and Development (OECD) and Nuclear Energy Agency (NEA) Phase I members for comment on June 30, 2017
- Federal Register notice (82 FR 36006) published on August 2, 2017
- Public comment period closed September 1, 2017
- Additional comments received from EPRI on January 12, 2018
- 91 comments received in total
- International and U.S. Industry 2
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Industry Comment Categories
- Generator capabilities and applicability for HEAF testing
- Protective relaying and the duration of testing
- Equipment ratings/Equipment selection
- Test conditions
- Equipment setup, combustible load, cable trays
- Test Parameters
- Voltage, current, grounding scheme
- Comparisons to IEEE Guide for Metal-Enclosed Low-Voltage Power Circuit Breaker Switchgear IEEE C37.20-2007 3
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Generator capabilities and applicability for HEAF testing
- The 2,250 MVA limitation on KEMA Laboratories' generator is the maximum available generator power, not the power delivered to the equipment.
- KEMA is equipped with current and power-limiting components, allowing precise adjustment of delivered power to any level within that rating.
- KEMA Laboratories uses a process of super excitation to compensate for the decreasing rotational energy of the generator during energy delivery, thus the short circuit decrement curve is not what the tested enclosure actually sees 4
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Equipment ratings and Equipment selection
- No testing will be performed on equipment with conditions that exceed the equipment ratings
- The magnitude of the fault conditions for the apparent power of a three-phase electrical system is given by SQU(3)*Voltage*Current
- At the selected test parameters the apparent power rating is within the industry average e based on a review of available plant information Phase II Apparent Power Range Industry Sample Averages Votage (V) Votage (V) 4160 6900 4160 6900 13800 Current (A) 25,000 180 MVA 300 MVA 320 MVA 430 MVA 690 MVA 35,000 252 MVA 418 MVA 5
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Protective relaying and the duration of testing
- Majority of arcing fault events are quickly terminated by protective devices; however such events are not the subject of this test program
- These are typically encompassed in the NUREG/CR-6850 bin 15 frequency as ignition sources for electrical enclosure fires
- not HEAF or *not fires i.e. self extinguished
- This test program is designed to evaluate the impact of "bin 16" events; i.e. arcing faults that are not quickly interrupted by circuit protection schemes
- The frequency of HEAF events is a current area of work previously discussed and will be captured though a joint EPRI/NRC program 6
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Protective relaying and the duration of testing Plant Name Date Arc Duration
- Duration of tests is based on Robinson 03/27/2010 8 s to 10 s operating experience of bin 16 Diablo Canyon 05/15/2000 11 s events Prairie Island 08/03/2001 >2 s San Onofre 02/03/2001 >2 s
- Plant specific circuit protection Fort Calhoun 06/07/2011 42 s(required operator schemes will be an area of intervention) discussion for the joint EPRI/NRC HEAF project to begin in Q4 of 2018 7
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Protective relaying and the duration of testing (Low Voltage)
- Several low voltage events have exhibited the ability to hold in for extended durations from both U.S. OpE and International experience
- Fort Calhoun- 42 seconds (interrupted by control room action)
- German Event 17 - 8.5 seconds; Analysis of High Energy Arcing Fault (HEAF)
Fire Events, NEA/CSNI/R(2013)6 Switch Yard G
4160 V 1-2 MVA 480V NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018 8
Test conditions Equipment setup, combustible load, cable trays
- The test program has been modified to include circuit breakers in all electrical enclosures
- No cable trays will be used in this test program
- Tests will focus on data collection systems arranged around the enclosure to collect relevant information
- All internal combustible load arrangements will be documented
- size, orientation, mass, cable jacket material, cable insulation material 9
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Comparisons to IEEE Guide for Metal-Enclosed Low-Voltage Power Circuit Breaker Switchgear -
IEEE C37.20-2007
- The NRC tests do not intend to replicate the IEEE guide.
- The NRC is NOT attempting to qualify arc resistant equipment per the guide but attempting to obtain information to aid in the development of advancing the HEAF methodology for use in the context for NPP PRA use in a dynamic manner
- The guide will be followed for the extent practicable for the needs of this research
- Wire Size #10 AWG (Class K Stranded) vs #24 AWG
- Arc Location, Arc initiation phase angle 10 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Test Parameters (Topics to be discussed collaboratively in the next session)
- Duration
- Bus spacing
- Voltage
- Enclosure
- Current configuration
- Grounding
- Arc Location Configuration
- Arc initiation
- X/R phase angle 11 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
12 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
NRC Test Parameters and Equipment Gabriel Taylor, P.E. Kenn Miller Division of Risk Assessment Division of Engineering Office of Nuclear Regulatory Research April 19, 2018 Rockville, MD NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Session Objective
- Solicit discussion and feedback for Phase II test parameters
- Understand range of operating conditions
- Identify equipment configurations and types for testing 2
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Needs and Objectives
- Provides high level overview of hazard, data, and models
- Identifies research goals and objectives
- Identifies informational needs to ensure testing representative of event potential 3
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
The Hazard Ref. UAW Electrical Safety in the Workplace 4
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Goals
- Provide data to refine and improve HEAF damage estimation methodology
- Refine existing model
- Modify refined model to account for Aluminum 5
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Objective In order to reach the stated goal the following objectives have been determined to be important
- Identification of realistic test conditions, based on:
- typical nuclear power plant electrical distribution system design and protection
- operating experience
- Optimize test parameter variants
- Development and application of measurement devices
- Collect measurement data to characterize HEAF environment
- Analyze data to determine extent of damage and understand extent of hazard
- Revise existing models 6
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Test Parameters
- Duration
- Bus spacing
- Voltage
- Enclosure
- Current configuration
- Grounding
- Arc Location Configuration
- Arc initiation
- X/R phase angle 7
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Thermal Energy
- Thermal energy released from HEAF will be a function of primary parameters
- Arc voltage (Varc)
- Arc current (Iarc)
- Duration of arc (t)
- Heat transfer efficiency (k) 8 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Electrical Enclosure Test Matrix Test Type Material Voltage (kV) Current (kA) Duration (seconds) Gap Energy
- Cabinet Bus Duct Cu Al 0.48 4.16 6.9 15 25 35 1 2 3 4 5 8 (mm) (J/cm2)
A X X X X X B X X X X X C X X X X X D X X X X X E X X X X X F X X X X X M X X X X X N X X X X X O X X X X X P X X X X X Q X X X X X R X X X X X G X X X1 X X H X X X1 X X I X X X X X J X X X1 X X K X X X1 X X L X X X X X S X X X X X T X X X X X U X X X X X V X X X X X W X X X X X X X X X X X Sp1 X Sp2 X 9
NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Bus Duct Test Matrix Test Bus Material Duct Material Voltage (kV) Current (kA) Duration Energy
- (seconds) Gap (mm)
(J/cm2)
Cu Al Steel Al 4.16 25 1 3 5 BD_A X X X X X BD_B X X X X X BD_C X X X X X BD_D X X X X X BD_E X X X X X BD_F X X X X X BD_G X X X X X BD_H X X X X X Sp1 X X Sp2 X X 10 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Test Parameters
- Arcing Time (Duration)
- Electrical protection clearing times for primary and secondary protection
- Worst case bolted fault conditions may not produce bounding incident energy
- Should also evaluate clearing times for arc conditions with limiting source
- With and without considering failure of 1st upstream circuit protection 11 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Proposed Testing Arc Durations
- Electrical Enclosures
- Low Voltage
- 4 and 8 seconds
- Medium Voltage
- 2 and 4 seconds
- Bus Bar Duct
- Medium Voltage
- 1, 3, 5 seconds 12 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Durations from Operating Experience Plant Name Date Arc Duration (seconds)
Robinson 03/2010 8 - 10 Diablo Canyon 05/2000 11 Prairie Island 08/2001 >2 San Onofre 02/2001 >2 Fort Calhoun 06/2011 42 13 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Why long durations?
- Short arc flashes lack sufficient energy to cause thermal damage to other equipment
- Total energy (thermal source term) dependent on duration
- Long durations and their damage footprint are showing up in operating experience
- Arc flash vs HEAF 14 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Discussion Arcing Duration 15 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Test Parameters (cont.)
- Voltage level
- Low voltage
- 480Vac
- Medium Voltage
- 6.9kVac
- Exception
>> if donated equipment is not rated for 6.9kV then it will be tested to its rated voltage (i.e., 4.16kV, 2.4kV, etc.)
16 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
System voltage versus Arc voltage (Phase 1) 17 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Enclosure Bus Bar Spacing for Phase 1 18 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Arc voltage vs bus bar spacing (phase 1 results) 19 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Bus Spacing versus Arc Voltage for Phase 1 results Error (-39%, 84%)
Avg. Over predict 12% (approx.)
20 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Discussion 21 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Test Parameters (cont.)
- Current
- Bolted fault current
- A short circuit or electrical contact between two conductors at different potentials in which the impedance or resistance between the conductors is essentially zero
- Arcing fault current
- A fault current flowing through an electrical arc plasma Ref. IEEE 1584 22 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Proposed test fault current levels
- 480Vac - Low voltage
- 15kA
- 25kA
- 6.9kVac - Medium Voltage
- 25kA
- 35kA 23 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Fault Mean Median Low voltage Current Bolted (kA) 27.3 (kA) 24.6 460-480 Vac Arcing 14.4 13.3 Sample from US plants Fault Current 480V Sample (n=18) 14 12 10 8
Count 6
4 2
0 0-10 10-20 20-30 30-40 40-50 50-60 Current (kA)
Bolted Fault Arcing Fault Test Levels: 15kA and 25kA 24 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Fault Mean Median Medium Voltage Current Bolted (kA) 31.0 (kA) 30.8 4.16kVac Arcing 29.5 29.3 Fault Current 4.16kV Sample (n=23) Sample from US plants 10 9
8 7
6 Count 5 4
3 2
1 0
0-10 10-20 20-30 30-40 40-50 50-60 60-70 Current (kA)
Bolted Fault Arcing Fault Test Levels: 25kA and 35kA 25 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Fault Mean Median Medium Voltage Current Bolted (kA) 32.8 (kA) 33.6 6.9kVac Arcing 31.2 31.9 Fault Current 6.9kV Sample (n=9) Sample from US plants 6
5 4
Count 3 2
1 0
10-20 20-30 30-40 40-50 50-60 Current (kA)
Bolted Fault Arcing Fault Test Levels: 25kA and 35kA 26 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Discussion Fault Current 27 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
System connection
- Wye vs Delta
- Majority of past testing has been performed in Delta configuration
- Wye connections are available at KEMA 28 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Grounding
- Wye connected system grounding
- Solid
- Resistive
- Reactive
- Ungrounded 29 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Arc Location LV Switchgear
- Back 30 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Arc Location LV Switchgear
- Front 31 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Arc Location MV MC Switchgear
- Side 32 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Arc Location MV MC Switchgear
- Side 33 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Bus Bar Spacing
- Standards dont specify requirement,
- manufacture determines spacing to ensure equipment will pass performance tests
- Typical spacing Class IEEE 1584 Web 15kV switchgear 152 mm (6.0 in) 152 mm (6.0 in) 5kV switchgear 104 mm (4.1 in) 89 mm (3.5 in)
LV switchgear 32 mm (1.3 in) 25 mm (1 in) 34 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Bus Insulation
- Insulating material used to cover primary voltage conductors except where that conductor is a cable or wire. Bus joint insulation is excluded from this category and is treated separately.
- The primary functions of bus insulation are to impede arc movement and to allow closer spacing of conductors than would be possible with bare conductors.
- Bus insulation may also serve a secondary function as an element of the bus support insulation system IEEE C37.20.2 35 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Pressure influences Phase A
- Arc Power
- DC time constant
- Asymmetric current Phase B
- Volume
- Area of opening Phase C 36 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Equipment
- Germany and Korea plan on donating equipment to program
- All other equipment will be procured
- Input is requested to ensure applicability
- US Utility Donation?
37 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Planned Equipment Donation 38 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Equipment Procurement Medium Voltage
- Magne Blast AM
- Allis Chalmers MA-250
- Westinghouse DB-50
- ITE 5KH-350
- ABB 39 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Equipment Procurement Low Voltage
- Westinghouse DS-5
- General Electric AKD-10 40 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Enclosure Thickness
- Electrical Enclosures
- Enclosure
- Steel, min. thickness MSG No. 14 (1.9mm)
- Partition between each primary circuits
- Steel, min. thickness MSG No. 11 (3mm)
- Aluminum thickness based on equivalent strength and deflection
- Annex B of IEEE C37.20.1 & 20.2 have enclosure requirements IEEE C37.20.1, Standard for Metal Enclosed Low-Voltage Power Circuit Breaker Switchgear IEEE C37.20.2, Standard for Metal-Clad Switchgear 41 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Enclosure Ventilation
- Important variable for pressure
- Any specific concerns 42 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018
Bus Duct Tests
- Configuration
- Bus bars Config.
- Al Bus / Al Duct - Square hollow
- Al Bus / Steel - Rectangular Duct - Circular
- Cu Bus / Al Duct
- Size / Rating
- Cu Bus / Steel - 1600A Duct
- 3200A
-?
43 NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018