Text

2018 HEAF Workshop Binder
	ML18108A210
Person / Time
Issue date:	04/18/2018
From:	Michael Cheok; NRC/RES/DRA/FRB
To:	;
	G. Taylor 415-0781
References
	Download: ML18108A210 (278)
	v • d • e

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

- Aluminum HEAF Pre-GI-018

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

Presentation by EPRI for the Regulatory Information Conference TH30 - Improving Realism in Fire PRA

- 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)

NUREG/CR-7197

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:

The force of the HEAF energy will be directed by vent louver

- 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

Aluminum HEAF Generic Issue

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

HEAF PIRT

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

NUREG-0933

Periodic Reports (semi-annual Generic Issue Management Control System)

GI Dashboard NRC HEAF Phase II Information Sharing Public Workshop, April 18-19, 2018

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-0004 - LOCA with Delayed LOOP

Pre GI-0005 - Electromagnetic Pulse Attack

Pre GI-0006 - Boron Precipitation following LOCA

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

<https://www.nrc.gov/sr0933/>

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

Presentation by EPRI for the Regulatory Information Conference TH30 - Improving Realism in Fire PRA

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

All HEAF scenarios were assumed to have aluminum components

- 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

Understand realistic risk associated with HEAF events involving aluminum.

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

Pilot plants should have unique HEAF scenarios modeled within their PRA

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 Flash

- 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

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.

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

OSHA

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)

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

Carl Fredericks

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.

IEEE-NFPA Collaboration Project Sponsors

Platinum

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

Gold - McSquared Electrical Consulting, LLC

- 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

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.

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.

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

Factors to be Considered

Source (Rectifier, Battery, PV, and etc.)

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.

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?

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

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.

EPRI Perspective High Energy Arcing Faults Ashley Lindeman Senior Technical Leader HEAF Information Sharing Workshop April 18, 2018

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

TogetherShaping the Future of Electricity 17

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.

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.

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.

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.

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.

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.

Equipment failures causes blackouts USA 2016 (n = 3.879)

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.

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.

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

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

Initial failure rate large power transformers > 20 MVA Number of large power transformers tested over the years (KEMA Laboratories) n=344 Average 22%

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

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]

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

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.)

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 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, ..

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.

Initial failure for power arc on insulator strings Successful tests 109 Failures 57 Failure rate 34%

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

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

Aluminum vs. Copper

- Bus Ducts

Aluminum Enclosure; Copper Conductor

Aluminum Enclosure; Aluminum Conductor

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

USA

- 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

ML18108A210

Text

Navigation menu

Search