ML18039A624

Fpra FAQ 17-0013 High Energy Arcing Fault (Heaf) Non-Suppression Probability (NSP) - Draft

ML18039A624
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Issue date:	01/18/2018
From:	Office of Nuclear Reactor Regulation
To:	Humphrey M, Meade B, Schairer M
Wu A
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ML18039A549	List: ML18039A624 ML18039A653 ML18039A661 ML18039A856 NUREG-2180, Data Collection in Support of Integrating Operating Experience Into NUREG-2180
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FAQ 17-0013
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FAQ Number 17-0013 FAQ Revision 0 (Draft BC)

FAQ Title High Energy Arcing Fault (HEAF) Non-Suppression Probability (NSP)

Plant: Various Date: March 21January 18, 20172018 Contact: Beth Meade Phone: (508) 532-7139 Mark Schairer (508) 532-7317 Mark Humphrey (508) 532-7269 Email: bah@epm-inc.com mvs@epm-inc.com msh@epm-inc.com Distribution: (NEI Internal Use)

FPRA TF BWROG PWROG Purpose of FAQ:

This FAQ provides an update to the non-suppression probability (NSP) for high energy arcing fault (HEAF) fires based on a review of additional fire event data.

Relevant NRC document(s):

NUREG/CR-6850 NUREG/CR-6850 Supplement 1 (FAQ 08-0050)

NUREG 2169 Details:

NRC document needing interpretation (include document number and title, section, paragraph, and line numbers as applicable):

See list of relevant NRC documents Circumstances requiring interpretation or new guidance:

The non-suppression probability for high energy arcing fault (HEAF) fires provided in NUREG/CR-6850 Supplement 1 (FAQ 08-0050) and NUREG 2169 are considered overly conservative based on durations that extended past the control point in the fire event. As a result, the risk associated with HEAFs in critical fire areas may be artificially high.

Detail contentious points if licensee and NRC have not reached consensus on the facts and circumstances:

FAQ Number 17-0013 FAQ Revision 0 (Draft BC)

FAQ Title High Energy Arcing Fault (HEAF) Non-Suppression Probability (NSP)

Although recent guidance has sought to provide a better estimate of non-suppression probability, in the case of HEAF fire events, the probability of non-suppression is believed to be overly conservative.

Potentially relevant existing FAQ numbers:

FAQ 08-0050, Manual Non-Suppression Probability Response Section:

Proposed resolution of FAQ and the basis for the proposal:

1. Introduction The total duration for high energy arcing fault (HEAF) fires utilized in NUREG/CR-6850 Supplement 1 (FAQ 08-0050) to develop the lambda mean value for HEAFs is 276 minutes.

Three events were used to develop this total, resulting in an average of 90 minutes per fire. In some casescases, the long suppression duration has had significant impact on the total risk of a fire area. NUREG-2169 expanded the number of reviewed events to eight (8) with a total duration of 602 minutes. The resulting change to the lambda mean was nominal, increasing from the 0.011 established in NUREG/CR-6850 Supplement 1, to 0.013. A further review to verify the suppression rate has been performed, to ensure the analyses of HEAF fires are not providing overly conservative results, and that the results are providing appropriate risk insights for the scenarios.

The fire event times for the majority of the HEAF events in NUREG-2169 are one hour (60 minutes) or longer, with several exceeding two hours (120 minutes) in duration. The probability of non-suppression is based on the average time to suppression within a specific fire bin. The times reported and utilized in NUREG-2169 are considered excessive considering that many HEAF sources are located in accessible areas provided with automatic detection and the failures due to the HEAF often initiate a signal to the control room early in the event.

Therefore, fire brigade response is expected to occur quickly after the initial HEAF. In addition, complete fire suppression is not required for an assessment of non-suppression probability. as aArresting the fire spread and development propagation eliminates additional target damage and effectively suppresses controls the fire, but and may not necessarily correspond with a fire being extinguished.

This FAQ review expanded upon the data in NUREG-2169 by obtaining reviewing Licensee Event Reports (LERs) and related documentation (where available) for several of the extended duration fires in order to assess whether the fire was in fact under control earlier in the scenario than the event duration implies. During review of the LERs, it became apparent that there are several contributors that extend the reported fire duration beyond the time required to suppress and contain control the fire spread. First, it appears that there is a lag between when the fire is under control in the field and when it is reported to the control room as extinguished. It also

FAQ Number 17-0013 FAQ Revision 0 (Draft BC)

FAQ Title High Energy Arcing Fault (HEAF) Non-Suppression Probability (NSP) appears that there is a potentially significant lag between when the fire is under control and when the fire is declared extinguished due to the need to de-energize the high energy equipment.

Both factors result in over-estimation of the fire duration in some event reports and affected fire events included in NUREG/CR-6850 Supplement 1 and NUREG-2169. For purposes of Fire PRAs, the time to control is a more appropriate time, since this is when the fire is no longer considered a challenging event. The fire events reviewed are described below. The fire event number provided represents the number assigned in the EPRI Fire Events Database (Ref. 3).

while the acronym represents an identification number based on plant and/or country of origin and date.

2. Revised Fire Event Times 2.1. Fire Event #947 (OC 19890103): This fire event was reported as having a 59 minute duration in NUREG-2169 and NUREG/CR-6850 Supplement 1 and a 46 minute duration in NUREG/CR-6850 (Ref. 2, 3, and 5). A review of the LER indicates that the fire event started at 1916 and the fire was reported to be out at 2015 (Ref. 11). However, further details indicate that the first attempt to extinguish the fire was at 1933 hours0.0224 days <br />0.537 hours <br />0.0032 weeks <br />7.355065e-4 months <br /> utilizing CO2 and dry chemical extinguishers, which were unsuccessful due to reflash (Ref. 11). Plant personnel determined that water fog was required to extinguish the fire without continued risk of reflash. At 2002 hours0.0232 days <br />0.556 hours <br />0.00331 weeks <br />7.61761e-4 months <br /> the bus was de-energized, for personnel safety, and water was applied (Ref. 11). Given this timeline, it is likely that the fire was under control between 1933 and 2002 hours0.0232 days <br />0.556 hours <br />0.00331 weeks <br />7.61761e-4 months <br />; however, the fire was definitively under control at 2002 establishing a 46- minute event duration for the purposes of calculating PNS NSP (Ref. 11).

This fire is an example of cautious firefighting resulting in a delay to fire suppression due to a fire in high energy equipment.

2.2. Fire Event #74 (WF 19950610): This fire event was reported as having a 136 minute duration in the FEDB and NUREG-2169 (as Fire Event #74); a 57 minute duration in NUREG/CR-6850 (reported as event number 2175); and a 76 minute duration in NUREG/CR-6850 Supplement 1 (as 2175) (Ref. 2, 3, 4 and 5). A review of the LER indicates that the event initiated at 0858, which varies only slightly from the FEDB which reports the event initiating at 0857 (Ref. 2 and 10). The fire brigade responded and attempted to extinguish the fire at 0935 via Halon, CO2, and dry chemical extinguishers (Ref. 10). The fire was reported extinguished at 1022, after the local fire department applied water to the insulation above the bus at 1018 (Ref. 10). Since the fire was under control at 1018, the appropriate fire duration for the PNSNSP calculation is 80 minutes.

The extended fire duration time reported in the FEDB and NUREG-2169 coincides with the official declaration that the fire was extinguished (Ref. 10).

2.3. Fire Event #100 (DC 20000515): This fire event was reported as having a 78 minute duration in NUREG-2169 and the FEDB (Ref. 2 and 4). The event was not included in NUREG/CR-6850 or NUREG/CR-6850 Supplement 1 (Ref. 3 and 5). The event was reported to begin at 0025 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br /> on May 15, 2000. The fire was declared out at 0143 hours0.00166 days <br />0.0397 hours <br />2.364418e-4 weeks <br />5.44115e-5 months <br />, providing the 78 minute duration. However, additional details provided in the Preliminary Notification of Event or Unusual Occurrence (Ref. 7) as reported by the Region IV staff,

FAQ Number 17-0013 FAQ Revision 0 (Draft BC)

FAQ Title High Energy Arcing Fault (HEAF) Non-Suppression Probability (NSP) indicates that the fire was extinguished using carbon dioxide, by 1 a.m. Although PNO is not the official documentation of the fire event, such as the LER, the additional information agrees with the LER (Ref. 6) which states:

When the fire brigade entered the room, they quickly extinguished the fire with a CO2 extinguisher, before offsite assistance arrived. After clearing smoke from the room, the fire was declared out at 0143 PDT.

This suggests that a significant time lag may have occurred between extinguishing what is referred to as the small fire and the official declaration. A 35 minute fire duration is considered reasonable based on the available data and is a refinement on the original, conservative duration provided in the FEDB and utilized in NUREG-2169.

2.4. Fire Event #106 (SG 20010203): This fire event was reported as having a 154 minute duration in NUREG-2169 and a 156 minute duration in the FEDB (Ref. 2 and 4). The event is also cited as 141 minutes in NUREG/CR-6850 Supplement 1, which is a revision from the NUREG/CR-6850 duration of 136 minutes (Ref. 3 and 5). There is no explanation provided in NUREG-2169 or NUREG/CR-6850 Supplement 1 for the discrepancy between the documents. The LER for this event details that the event began around 1514 1513 (1514 was reported in the FEDB and is used here) and that fire responders reported the fire extinguished at 1544; it was later determined that the fire was not extinguished at that time, but flames were no longer visible (Ref. 8). The delay is attributed to extinguishing due to high energy and resistance to using water; however, the fire was under control and limited to the cubicle at the time of the report (Ref. 8). Therefore, an event duration of 31 minutes is appropriate for use in the PNSNSP curve, as this reflects the time required for the fire to be suppressed and controlled.

2.5. Fire Event #127 (VY 20040618): This fire event was reported as having a 71 minute duration in NUREG 2169 and the FEDB (Ref. 2 and 4). The event was not included in NUREG/CR-6850 or NUREG/CR-6850 Supplement 1 (Ref. 3 and 5). The FEDB reports that the fire was under control by 0717; however, the FEDB utilizes the time to extinguishment of 0751 to calculate the fire duration (Ref. 3). The LER for this event establishes that the event occurred at 0640 and that the fire brigade declared the fire under control at 0717, resulting in a 37 minute duration (Ref. 9). Therefore, an event duration of 37 minutes is appropriate for use in the NSP curve, as this reflects the time required for the fire to be controlled. The FEDB also reports that the fire was under control by 0717 but that the fire was not extinguished until 0751; use of the time to extinguishment resulted in the 71 minute duration (Ref. 3).

3. Additional Fire Events This FAQ review also identified two fire events that were originally binned as electrical fires for the calculations of non-suppression probability in NUREG-2169 but which are bin 16.1 and 16.2 HEAF fires for fire ignition frequency (Ref. 2). The fire events in this category are #922 and #792 with a fire duration of 5 minutes and 3 minutes respectively. The LER for fire event

FAQ Number 17-0013 FAQ Revision 0 (Draft BC)

FAQ Title High Energy Arcing Fault (HEAF) Non-Suppression Probability (NSP)

1. 922 was reviewed and it was determined that several of the characteristic challenges that have been shown to inhibit fire suppression in HEAF events, specifically the need to de-energize the high energy equipment and suppress secondary fires, were present in this scenario (Ref. 12).

The fire originated in a bus bar connecting the Main Auxiliary Transformers from 6160 volt busses due to a phase to ground (Ref. 12). In order to suppress the fire, the Main Auxiliary Transformer was de-energized and plant personnel manually suppressed a secondary fire caused by slag emitted from the bus (Ref. 12). Based on the characteristics of this fire, although it occurred outside of an electrical panel, the fire is considered to represent the same challenges as a typical HEAF scenario and inclusion in the HEAF non-suppression probability calculations is considered appropriate.

Fire event #792 occurred in the A isolated-phase bus duct due to damaged ground straps and a deteriorated gasket (Ref. 13). Although the fire does not represent similar combustibles to that of a typical electrical cabinet, the challenges related to the fire are similar to that of a typical HEAF; specifically, that the bus ducts were required to be de-energized prior to suppression (Ref. 13). Therefore, inclusion of this fire event in the calculations for the HEAF non-suppression probability of a HEAF fire is considered more appropriate than inclusion in the electrical fire bin.

In addition, the most recent revision to the EPRI FEDB includes an additional published event that was not available for review at the time of NUREG-2169. Fire Event #162 occurred on August 5, 2009 and is reported to have a 46 minute fire duration (Ref. 4). The event was detected at 0751 hours0.00869 days <br />0.209 hours <br />0.00124 weeks <br />2.857555e-4 months <br /> when the conductor in one of the supply busses catastrophically failed, melting all three phases of the conductor (Ref. 14). The fire was declared out at 0811 hours0.00939 days <br />0.225 hours <br />0.00134 weeks <br />3.085855e-4 months <br /> (Ref. 14).

These three fire events, as well as the refined event durations above have been included in the updated calculations of HEAF non-suppression probability.

The re-binning of Fire Events #792 and #922 as HEAF fires versus electrical fires for the non-suppression probability necessarily results in a revision to the electrical fire non-suppression probability. The changes are reflected in the proposed revisions to NUREG-2169 included as part of this FAQ.

4. Comparison with International Events The scope of the previous non-suppression probability analyses has been limited to events occurring in the United States. However, the Organisation for Economic Co-operation and Development (OECD) has recently released Fire Project Topical Report No. 1 Analysis of High Energy Arching Fault (HEF) Fire Events (Ref. 1). This report identified 48 HEAF events that had been reported to the OECD from Canada, Czech Republic, Finland, France, Germany, Japan, Korea, Spain, Sweden and the United States. The database includes 11 events in the United States, although this included non bin 16 HEAFs (e.g., cable HEAFs and HEAFs occurring in the Yard transformers). The OECD report included 18 bin 16 HEAF events occurring outside of the United States. The average duration for these fires was 31.3 minutes;

FAQ Number 17-0013 FAQ Revision 0 (Draft BC)

FAQ Title High Energy Arcing Fault (HEAF) Non-Suppression Probability (NSP) while the average time for the US only events reviewed as part of this FAQ is 35 minutes. The average time for all events, both US and international, is 32.7 minutes. The use of an average time of 35 minutes for US HEAF events is, therefore, considered conservative and in agreement with the trend of HEAF fire event durations internationally.

5. Summary/Conclusion Based on the documentation review and considering the expanded data set, the mean suppression rates proposed in NUREG/CR-6850 Supplement 1 and NUREG 2169 are overly conservative. It is proposed that the mean suppression rate should be increased by approximately a factor of two (from 0.011/0.013 to 0.029) to reflect the revised average fire duration for HEAFs originating in high energy equipment in the US.

A chi squared distribution was applied, consistent with NUREG-2169, to calculate the percentiles based on the number of events and total durations presented in table 5-1.

Attachment 1 and Attachment 2 to this FAQ are provided to summarize the fire event data review and the resulting average durations and non-suppression probability that would result from expanding the data set. The unique identifier in Attachment 2 represents an identification number based on plant and/or country of origin and date.

If appropriate, provide proposed rewording of guidance for inclusion in the next Revision:

The following are proposed revisions to NUREG 2169:

FAQ Number 17-0013 FAQ Revision 0 (Draft BC)

FAQ Title High Energy Arcing Fault (HEAF) Non-Suppression Probability (NSP)

Table 5-1 Probability distribution for rate of fires suppressed per unit time, (Originally, Table P-2 from NUREG/CR-6850)

Number Total Rate of Fire Suppressed ()

Suppression Curve of Events Duration 5th 50th 95th in Curve (minutes) Mean Percent Percent Percent T/G fires 30 1167 0.026 0.019 0.025 0.034 Control room 12 37 0.324 0.187 0.315 0.492 PWR containment (AP) 3 40 0.075 0.020 0.067 0.157 Containment (LPSD) 31 299 0.104 0.075 0.103 0.136 Outdoor transformers 24 928 0.026 0.018 0.026 0.035 Flammable gas 8 234 0.034 0.017 0.033 0.056 Oil fires 50 562 0.089 0.069 0.088 0.111 Cable fires 4 29 0.138 0.047 0.127 0.267 Electrical fires 175 1807 0.097 0.085 0.097 0.109 Welding fires 52 484 0.107 0.084 0.107 0.133 Transient fires 43 386 0.111 0.085 0.111 0.141 HEAFs 11 385 0.029 0.016 0.029 0.044 All fires 443 6358 0.070 0.064 0.070 0.075

FAQ Number 17-00020013 FAQ Revision 0 (Draft BC)

FAQ Title High Energy Arcing Fault (HEAF) Non-Suppression Probability (NSP)

Table 5-2 Updated numerical results for suppression curves (Originally, Table 14-1 from NUREG/CR-6850, Supplement 1)

PWR Time T/G Outdoor Flammable Oil Electrical Transient Containment Control Cable All HEAFs containment Welding (min) fires Transformers Gas fires fires fires (LPSD) Room Fires Fires (AP) 0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 5 0.879 0.867 0.879 0.843 0.641 0.616 0.572 0.687 0.595 0.584 0.198 0.502 0.705 10 0.773 0.751 0.772 0.710 0.411 0.380 0.328 0.472 0.355 0.341 0.039 0.252 0.497 15 0.680 0.651 0.678 0.599 0.263 0.234 0.188 0.325 0.211 0.200 0.008 0.126 0.350 20 0.598 0.565 0.596 0.505 0.169 0.144 0.108 0.223 0.126 0.117 0.002 0.063 0.247 25 0.526 0.490 0.524 0.425 0.108 0.089 0.062 0.153 0.075 0.068

• 0.032 0.174 30 0.462 0.424 0.460 0.359 0.069 0.055 0.035 0.105 0.045 0.040

• 0.016 0.123 35 0.407 0.368 0.404 0.302 0.044 0.034 0.020 0.072 0.027 0.023

• 0.008 0.087 40 0.358 0.319 0.355 0.255 0.028 0.021 0.012 0.050 0.016 0.014

• 0.004 0.061 45 0.314 0.276 0.312 0.215 0.018 0.013 0.007 0.034 0.009 0.008

• 0.002 0.043 50 0.277 0.240 0.274 0.181 0.012 0.008 0.004 0.024 0.006 0.005

• 0.001 0.030 55 0.243 0.208 0.241 0.153 0.007 0.005 0.003 0.016 0.003 0.003 *

• 0.021 60 0.214 0.180 0.212 0.129 0.005 0.003 0.002 0.011 0.002 0.002 *

• 0.015 65 0.188 0.156 0.186 0.108 0.003 0.002

• 0.008 0.001 0.001 *

• 0.011 70 0.165 0.135 0.164 0.091 0.002 0.001

• 0.005 * * *

• 0.007 75 0.145 0.117 0.144 0.077 0.001 0.001

• 0.004 * * *

• 0.005 80 0.128 0.102 0.126 0.065 * *

• 0.002 * * *

• 0.004 85 0.112 0.088 0.111 0.055 * *

• 0.002 * * *

• 0.003 90 0.099 0.076 0.098 0.046 * *

• 0.001 * * *

• 0.002 95 0.087 0.066 0.086 0.039 * * * * * * *

• 0.001 100 0.076 0.057 0.075 0.033 * * * * * * *

• 0.001 5-5

FAQ Number 17-00020013 FAQ Revision 0 (Draft BC)

FAQ Title High Energy Arcing Fault (HEAF) Non-Suppression Probability (NSP)

Formatted: Top: 0.01" Figure 5-2 Non-suppression curve plots: probability vs. time to suppression

FAQ Number 17-00020013 FAQ Revision 0 (Draft BC)

FAQ Title High Energy Arcing Fault (HEAF) Non-Suppression Probability (NSP)

References

1. NEA/CSNI/R(2013)6, Nuclear Energy Agency OECD Fire Project - Topical Report No.

1, Analysis of High Energy Arcing Fault (HEAF) Fire Events, June 25, 2013

2. NUREG 2169, Nuclear Power Plant Fire Ignition Frequency and Non-Suppression Probability Estimation Using the Updated Fire Events Database, December 2014

3. NUREG/CR-6850 Supplement 1, Fire Probabilistic Risk Assessment Methods Enhancements, September 2010

4. EPRI 1025284, The Updated Fire Events Database: Description of Content and Fire Event Classification Guidance, July 2013

5. NUREG/CR-6850, Fire PRA Methodology for Nuclear Power Facilities, September 2005

6. PG&E Letter DCL-00-115, Licensee Event Report 1-2000-004-01, Unit 1 Unusual Event Due to a 12kV Bus Fault, August 30 2000

7. Preliminary Notification of Event or Unusual Occurrence, PNO-IV-00-011, Unusual Event Because of a Fire Lasting Greater than 15 Minutes, May 15, 2000

8. Southern California Edison Docket No. 50-362, Licensee Event Report 2001-001, Fire and RPS/ESF Actuations Caused by the Failure of a Non-Safety Related 4.16kV Circuit Breaker April 2, 2001

9. Entergy Licensee Event Report 2004-003-01, Vermont Yankee Nuclear Power Station License No. DPR-28 (Docket No. 50-271) Reportable Occurrence No. LER 2004-003-01, June 14, 2005

10. Waterford Licensee Event Report 95-002-01, Accession # 9801160136, Reactor Trip and Non-Safety Related Switchgear Fire, January 13, 1998

11. Oconee Nuclear Station Unit 1 Licensee Event Report, Fire in ITA Switchgear Due to Unknown Cause, February 2, 1989

12. Kewaunee Nuclear Power Plant Licensee Event Report 87-009-00, Electrical Bus Bar Failure Causes Undervoltage on RXCP Buses and Reactor Trip, August 10, 1987

13. EPRI 1003111, Fire Events Database and Generic Ignition Frequency Model for U.S.

Nuclear Power Plants, November 2001

14. US Nuclear Regulatory Commission Region IV Report 05000397/2009010, Columbia Generating Station - NRC Special Inspection Report, November 23, 2009

FAQ Number 17-00020013 FAQ Revision 0 (Draft BC)

FAQ Title High Energy Arcing Fault (HEAF) Non-Suppression Probability (NSP)

Attachment 1: Data Summary Table

FAQ Number 17-00020013 FAQ Revision 0 (Draft BC)

FAQ Title High Energy Arcing Fault (HEAF) Non-Suppression Probability (NSP)

Mean BIN 16 HEAF Analysis # Events Total Duration AVG time/event Suppression Rate

(/min)

NUREG/CR-6850 3 239 79.67 0.013 NUREG/CR-6850 3 276 92.00 0.011 Supplement 1 NUREG 2169 8 602 75.25 0.013 International and US Fire 29 948 32.69 0.031 Events International Events Only 18 563 31.28 0.032 FAQ 17-0002 0013 Proposed Values - US 11 385 35.00 0.029 Events Only

FAQ Number 17-00020013 FAQ Revision 0 (Draft BC)

FAQ Title High Energy Arcing Fault (HEAF) Non-Suppression Probability (NSP)

Attachment 2: Fire Event Data Summary

FAQ Number 17-00020013 FAQ Revision 0 (Draft BC)

FAQ Title High Energy Arcing Fault (HEAF) Non-Suppression Probability (NSP)

Damage Reason for Voltage Limited to Extinguished Unique Outlier Time BIN *Reference FEDB # Include/Exclude Include/ Country Plant Date Event Title Component Location Fuel by (all means Duration [h:min]

Identifier (Y/N)/ Basis Level Initial Data Exclude involved)

Component Failure in the auxiliary Yes - No outside the plant, cable power supply with GER 20040823 12 1 None Exclude - BIN 12 Cable HEAF suppression Germany GER009 20040823 high voltage cable 10 kV Not switchyard, insulation No self- extinguished Unknown 0:00 consequential reactor time available other cable room materials scram on-site plant fire cable Plant trip due to cable run (self-ignited): brigade; people USA 20100328 12 1 None Exclude - BIN 12 Cable HEAF N/A USA USA027 20100328 4 kV turbine building insulation No Unknown 0:15 electrical fault power cables available in the material fire area No High energy electric auxiliary building, cable suppression circuit breaker (sub-GER 19790811 16.b 1 None Exclude N/A Germany GER027 19790811 arc at circuit breaker Unknown room for insulation Yes self- extinguished Unknown Unknown time is distribution board) and isolator ventilation materials available Event time Electrical cabinets USA 19840802 16.a 1, 2 434 Exclude N/A USA Unknown 19840802 Electrical cabinet Unknown Unknown Unknown Unknown Unknown Unknown Unknown undetermined with HEAF fixed extinguishing Fire at the cabinet cable high or medium voltage turbine building, system, manually JPN 19850831 16.b 1 None Include Bin 16 N/A Japan JPN044 19850831 containing 6.9 kV bus 6.9 kV insulation Yes Unknown 2:14 electrical cabinet switchgear room actuated; external for start-up materials fire brigade participated cable Damage of the 380 V electrical insulation busbar CR (auxiliary on-site plant fire GER 19860530 16.a 1 None Include Bin 16 N/A Germany GER011 19860530 bus bar 380 V building, cable materials; No Unknown 0:25 power supply of train brigade spreading room other

4) by a fire insulations KW 19870710 16.1 2, 4 922 Include Bin 16 N/A USA Kewaunee 19870710 Bus-duct Bus duct Unknown Unknown Unknown Unknown Unknown Unknown 0:03 Short circuit in the high or medium voltage electrical cable exciter system of an on-site plant fire GER 19870909 16.b 1 None Include Bin 16 N/A Germany GER022 19870909 electrical cabinet Unknown building, insulation Yes Unknown 0:09 emergency diesel brigade (emergency diesel) switchgear room materials generator unit Short circuit in the 220 kV/380 kV hardly on-site plant fire GER 19880419 16.b 1 None Include Bin 16 N/A Germany GER024 19880419 switchgear with high voltage switchgear 220 kV switchyard inflammabl Yes Unknown 0:46 brigade consequential loss of e liquid offsite power USA 19880715 16.2 2, 4 792 Include Bin 16 N/A USA Unknown 19880715 Iso-phase bus ducts Iso-phase bus ducts Unknown Unknown Unknown Unknown Unknown Unknown 0:05 During power escalation after startup fire brigade OC 19890103 16.b 2, 4 947 Include Bin 16 N/A USA Oconee 19890103 following a trip a Fire 6.9 KV Switchgear 6.9kV Switchgear Room Unknown Unknown (water, CO2, dry 1916-2002 0:46 occurred in the Unit 1 chemical) 6900 V switchgear Electric arc at a feeder switchgear (380 V electrical cable people available GER 19890517 16.a 1 None Include Bin 16 N/A Germany GER025 19890517 control panel in the switchgear, injection 380 V building, insulation Yes Unknown 0:12 in the fire area 380 V switchgear area) switchgear room materials

FAQ Number 17-00020013 FAQ Revision 0 (Draft BC)

FAQ Title High Energy Arcing Fault (HEAF) Non-Suppression Probability (NSP)

Damage Reason for Voltage Limited to Extinguished Unique Outlier Time BIN *Reference FEDB # Include/Exclude Include/ Country Plant Date Event Title Component Location Fuel by (all means Duration [h:min]

Identifier (Y/N)/ Basis Level Initial Data Exclude involved)

Component cable insulation Short circuit in the high voltage switchgear electrical materials; No (multiple on-site plant fire GER 19890908 16.b 1 None Include Bin 16 N/A Germany GER001 19890908 auxiliary electrical (10 kV injection cell); 10 kV building, Unknown 0:26 plastics / components) brigade system circuit breaker switchgear room polymeric materials HEAF for medium USA 19900713 16.b 2, 4 18 Include Bin 16 N/A USA Unknown 19900713 voltage electrical Electrical cabinet >1kV Unknown Unknown Unknown Unknown Unknown 0:10 cabinet (>1000V)

Loss of a 6.6 kV electrical cable high or medium voltage FRA 19901030 16.b 1 None Include Bin 16 N/A France FRA042 19901030 emergency 6.6 kV building, insulation Yes shift personnel Unknown 0:07 electrical cabinet switchboard. switchgear room materials cable electrical cabinet, high electrical insulation Fire at 6.6 kV or medium voltage No (multiple on-site plant fire FIN 19910412 16.b 1 None Include Bin 16 N/A Finland FIN001 19910412 6.6 kV building, materials, Unknown 0:37 switchgear (current transformer components) brigade switchgear room other inside cabinet) insulations HEAF - other USA 19911014 16.b 2, 4 20284 Include Bin 16 N/A USA Unknown 19911014 electrical or electronic Unknown Unknown Unknown in-situ Yes Unknown Unknown 0:02 equip Fault on lightning arrestor in the brigade (halon, switchyard, reactor 230kV/34.5k CO2 and dry trip, and then fire in a fault in 230kV/34.5kV V chem WF 19950610 16.b 2, 3, 4 74 Include Bin 16 N/A USA Waterford 19950610 4.16kV Non-safety transformer, fire in TG Building Unknown No 0858-1018 1:20 transformer extinguishers),

related bus. Damage 4.16kV Switchgear (4.16kV) fire department limited "mainly" to (water) breaker and adjoining cabinet Disconnection of a electrical cabinet cable main bus due to a auxiliary building, on-site plant fire GER 19960208 16.b 1 None Include Bin 16 N/A Germany GER017 19960208 (busbar, breaker 500 V insulation Yes Unknown 0:17 short circuit in a switchgear room brigade subassembly) materials switching module Fire of the bus-duct in shift personnel; the power supply reactor building, cable external fire JPN 19960907 16.1 1 None Include Bin 16 N/A Japan JPN029 19960907 room for the bus duct 460 V EDG switchgear insulation No Unknown 0:42 brigade emergency diesel room materials participated generator other solid material; plastics, fire brigade Unit 1 unusual event 12kV Switchgear 12kV bus, busbar/ bus solid extinguished the DC 20000515 16.1 1, 2, 4 100 Include Bin 16 N/A USA Diablo Canyon 20000515 due to a 12 kV bus 12kV room, auxiliary No 0025-0100 0:35 duct material; small fire with fault and fire building plastics/ C02 polymeric materials other diesel generator Incipient fire on insulations, high or medium voltage building, No (multiple FRA 20010119 16.b 1 None Include Bin 16 N/A France FRA008 20010119 ultimate emergency 6.6 kV plastics / self- extinguished Unknown 0:05 electrical cabinet electrical / process components) diesel generator polymeric room materials

FAQ Number 17-00020013 FAQ Revision 0 (Draft BC)

FAQ Title High Energy Arcing Fault (HEAF) Non-Suppression Probability (NSP)

Damage Reason for Voltage Limited to Extinguished Unique Outlier Time BIN *Reference FEDB # Include/Exclude Include/ Country Plant Date Event Title Component Location Fuel by (all means Duration [h:min]

Identifier (Y/N)/ Basis Level Initial Data Exclude involved)

Component This event occurs on the same day and Fire and RPS/ESF No second at the same cable actuations caused by breaker in same time as FEDB turbine switchgear insulation, SG 20010203 16.b 1, 4 437 Exclude Duplicate USA SONGS 20010203 the failure of a Non- 4.16kV bus 3A07 4.16kV bus failed & fire brigade 1514-1544 0:31 event 106. room solid safety related 4.16 kV arced due to FEDB event materials circuit breaker smoke 437 was not included in NUREG 2169.

There are two The event was caused entries in the when breaker x faulted FEDB for the on-site plant fire which caused arcing, HEAF medium voltage same day and circuit brigade, external SG 20010203 16.b 2, 3, 4 106 Include Bin 16 SG SONGS 20010203 localized overheating electrical cabinet 4kV Auxiliary building No 1514-1544 0:31 time (106 and breaker fire brigade and started a fire (>1kV) 437). .NUREG participated within the breaker 2169 cites only cubicle.

event 106 During startup, operators transferring power, closed breaker and breaker failed initiating a fire in bus cubicle. It was a "c-phase to ground arcing Pr Isl 20010803 16.b 2, 4 112 Include Bin 16 N/A USA Prairie Island 20010803 4 kV Bus 4 kV Bus 12 fire brigade Unknown 1:30 event, which quickly involved all phases.

The arcing led to actuation of the protective relaying, which resulted in a turbine/reactor trip" hardly Loss of 400 kV power inflammab shift personnel; supply following a fire electrical high or medium voltage le liquid, No (multiple external fire FRA 20010918 16.b 1 None Include Bin 16 N/A France FRA022 20010918 in the 6.6 kV AC 6.6 kV building, Unknown 1:11 electrical cabinet plastics / components) brigade Normal distribution switchgear room polymeric participated system cubicle materials Fire in the 500 V independent cable switchgear of one train emergency on-site plant fire GER 20020811 16.b 1 None Include Bin 16 N/A Germany GER017 20020811 switchgear 500 V insulation No Unknown 1:25 of the independent building, brigade materials emergency system switchgear room HEAF with electrical consequential fire cable building, room for GER 20021030 16.b 1 None Include Bin 16 N/A Germany GER009 20021030 occurred by exchange switchgear 400 V insulation No self- extinguished Unknown < 00:03 electrical control of a 0.4 kV switchgear materials equipment subassembly auto suppression, flammable Iso-phase bus duct fire brigade turbine building liquid, Vermont two- phase electrical extinguished VY 20040618 16.2 1, 2, 4 127 Include Bin 16 N/A USA 20040618 22kV iso-phase bus 22kV and yard (main hydrogen; No 0640-0717 0:37 Yankee fault and fire with using hose stream xfmr) other solid secondary fires and nearby material hydrant

FAQ Number 17-00020013 FAQ Revision 0 (Draft BC)

FAQ Title High Energy Arcing Fault (HEAF) Non-Suppression Probability (NSP)

Damage Reason for Voltage Limited to Extinguished Unique Outlier Time BIN *Reference FEDB # Include/Exclude Include/ Country Plant Date Event Title Component Location Fuel by (all means Duration [h:min]

Identifier (Y/N)/ Basis Level Initial Data Exclude involved)

Component electrical cable Electrical arc resulting low voltage electrical on-site plant fire CAN 20051015 16.a 1 None Include Bin 16 N/A Canada CAN004 20051015 600 V building, insulation Yes Unknown < 00:05 in injury cabinet brigade switchgear room materials Fire in a circuit electrical plastics /

breaker and switch-off high voltage circuit on-site plant fire GER 20080314 16.b 1 None Include Bin 16 N/A Germany GER003 20080314 660 V building, polymeric Yes Unknown 0:34 of the emergency breaker brigade switchgear room materials busbar FB No suppression Indeterminate HEAF for segmented HEAF for segmented USA 20080727 16.1 2, 4 10584 Exclude USA Unknown 20080727 Unknown Unknown Unknown Unknown Unknown Unknown Unknown time is Supp Time bus duct bus duct available event duration Non-safety related confined to CO 20090805 16.b 2, 4 162 Include Bin 16 Not well USA Columbia 20090805 Cable tray HEAF? 7KV Turbine Building Insulation self-extinguished 0750-0811 0:46 6.9kV feed bus floor of origin established electrical cable Czech Fire at 0.4 kV on-site plant fire CZE 20100217 16.a 1 None Include Bin 16 N/A CZE003 20100217 switchgear 0.4 kV building, insulation Yes Unknown 0:05 Republic switchgear brigade switchgear room materials Seismic event initiates the Yes - duration Seismic induced HEAF and is significantly arcing fault in Non- cable may explain high or medium voltage turbine building, on-site fire JPN 20110311 16.b 1 None Consider Excluding greater than all Japan JPN022 20110311 emergency metal clad 6.9 kV insulation No Unknown 7:58 the significant electrical cabinet switchgear room brigade other reported (M/C) switchgear materials duration time events cabinet compared to other events A condensate Electrical Failure pump is the (overheating, spark, electric motor driven USA 20050825 21 2, 4 135 Exclude N/A USA Unknown 20050825 7KV Turbine Building in-situ Yes fire brigade 1125-1317 initiating HEAF) Contained to pumps component the object of origin Fire in a 6 kV electrical cabinet in room D2.21, cabinet turbine building, other solid on-site plant fire SWD 20060915 21 1 None Exclude Pump N/A Sweden SWD007 20060915 feed power to the electrically driven pump 6 kV No Unknown 1:05 process room material brigade pump 725 P1. A breaker in the cabinet is burning The circ water Automatic reactor trip capacitor, pump is the due to circulating intake building, on-site plant fire USA 20061212 21 1, 4 1 Exclude N/A USA USA066 20061212 electrically driven pump 12 kV insulation Yes 0025-0100 0:34 initiating water pump surge process room brigade material component, capacitor failure The fault HEAF - other originated in a USA 20070925 21 4 10472 Exclude N/A USA Unknown 20070925 electrical or electronic Unknown Unknown Unknown in-situ Yes Unknown Unknown Unknown circ water equip pump Fire in transformer A transformer supplying the 6 kV on-site plant fire hardly is the on-site electrical medium or low voltage outside plant brigade; external SWD 20061114 23 1 None Exclude N/A Sweden SWD010 20061114 6 kV / 20 kV inflammabl No Unknown 2:40:00 originating systems train A and C transformer - oil filled buildings fire brigade e liquid component from the generator 20 participated kV busbar c

FAQ Number 17-00020013 FAQ Revision 0 (Draft BC)

FAQ Title High Energy Arcing Fault (HEAF) Non-Suppression Probability (NSP)

Damage Reason for Voltage Limited to Extinguished Unique Outlier Time BIN *Reference FEDB # Include/Exclude Include/ Country Plant Date Event Title Component Location Fuel by (all means Duration [h:min]

Identifier (Y/N)/ Basis Level Initial Data Exclude involved)

Component fixed Reactor trip caused by extinguishing a temporary loss of system, The main station service supply other building / flammable automatically transformer is high voltage transformer GER 20070628 23 1 None Exclude N/A Germany GER014 20070628 due to a short circuit 400 kV area, other type of liquid, Yes actuated; on-site Unknown 6:58 the initiating (main transformer) with a subsequent fire room paper, wood plant fire brigade; component in a generator external fire transformer brigade participated Trip of main transformer, followed fixed The main by fire in phase "S" extinguishing outside plant hardly transformer is due to manufacturing high voltage transformer 20 kV /400 system, actuated; SPN 19880622 27 1 None Exclude N/A Spain SPN001 19880622 buildings (Not inflammabl Yes Unknown 0:58 the initiating defect. Subsequently, (main transformer) kV on- site plant fire switchyard) e liquid component turbine trip and, with brigade; shift permissive P- 7, personnel reactor trip Trip of main transformer, followed fixed The main by fire in phase "S" extinguishing outside plant hardly transformer is due to manufacturing high voltage transformer 20 kV / system, actuated; SPN 19880820 27 1 None Exclude N/A Spain SPN001 19880820 buildings (Not inflammabl Yes Unknown 0:15 the initiating defect. Subsequently, (main transformer) 400kV on- site plant fire switchyard) e liquid component turbine trip and, with brigade; shift permissive P- 7, personnel reactor trip fixed The main extinguishing Main transformer outside plant hardly transformer is high voltage transformer 20 kV /400 system, actuated; SPN 19881202 27 1 None Exclude N/A Spain SPN001 19881202 tripped, followed by buildings (Not inflammabl Yes Unknown Unknown the initiating (main transformer) kV on- site plant fire fire in phase "R" switchyard) e liquid component brigade; shift personnel Fire of the station service load outside the plant, A transformer transformer 3BT02 Not switchyard, is the Czech caused by a defect on medium and low voltage 15.75 kV/ 6 voltage flammable on-site plant fire CZE 19940203 27 1 None exclude N/A CZE003 19940203 No Unknown 0:16 originating Republic the power part of the transformer - oil filled kV transformers near liquid brigade component branch lines switch to main followed by an transformer explosion Binned as HEAF - other "Transformer automatic USA 20000524 27 2, 4 50701 Exclude N/A USA Unknown 20000524 electrical or electronic XFMR Unknown Yard in-situ Yes Unknown Unknown Yard" in suppression equipment NUREG 2169 High energy arcing The main fault on phase B of transformer is high voltage transformer outside plant insulation KOR 20010130 27 1 None Exclude N/A Korea KOR010 20010130 the main transformer 22/345kV Yes self- extinguished Unknown 0:00 the initiating (main transformer) buildings material which led to the component reactor trip fixed The main Fire on the main extinguishing transformer is high voltage transformer flammable KOR 20020422 27 1 None Exclude N/A Korea KOR001 20020422 transformer leading to > 50 kV outside Yes system, Unknown 0:13 the initiating (main transformer) liquid a generator trip automatically component actuated,

FAQ Number 17-00020013 FAQ Revision 0 (Draft BC)

FAQ Title High Energy Arcing Fault (HEAF) Non-Suppression Probability (NSP)

Damage Reason for Voltage Limited to Extinguished Unique Outlier Time BIN *Reference FEDB # Include/Exclude Include/ Country Plant Date Event Title Component Location Fuel by (all means Duration [h:min]

Identifier (Y/N)/ Basis Level Initial Data Exclude involved)

Component The main Electric fault on the cable transformer is main transformer high voltage transformer FRA 20040929 27 1 None Exclude N/A France FRA035 20040929 > 50 kV other building insulation Yes shift personnel Unknown 0:20 the initiating leading to a reactor (main transformer) materials component trip The main Transformer oil -

transformer is 13kV or Main Transformer USA 20080816 27 4 127 Exclude N/A USA Unknown 20080816 HEAF confined to Main bank transformer XFMR oil Yes Unknown 2357-0202 2:05 the initiating greater or Switch Yard object of origin component The main Transformer oil -

transformer is 13kV or Main Transformer USA 20090201 27 4 157 Exclude N/A USA Unknown 20090201 HEAF confined to Main transformer XFMR oil Yes Unknown 2156-2227 0:31 the initiating greater or Switch Yard object of origin component fixed Automatic shutdown extinguishing of the reactor system, The main hardly following an switchyard automatically transformer is high voltage transformer inflammabl FRA 20100725 27 1 N/A Exclude N/A France FRA012 20100725 explosion and a 225 kV (transformer room No actuated; on- site Unknown 2:45 the initiating (main transformer) e liquid, consequential fire on / bunker) plant fire brigade; component cable the main power external fire transformer brigade participated A transformer hardly fixed is the Failure of start-up USA 20021003 28 1, 2, 4 116 Exclude N/A USA USA095 20021003 high voltage transformer > 50 kV transformer yard inflammabl Yes extinguishing 1513-1738 < 00:10 originating transformer ST 20 e liquid system component A yard outside the plant fixed Reactor trip due to hardly transformer is building (Not extinguishing USA 20051029 28 1, 2, 4 137 Exclude N/A USA USA064 20051029 main transformer fault high voltage transformer > 50 kV inflammabl Yes Unknown 0:28 the originating switchyard), main system; on-site and fire e liquid component transformer plant fire brigade Automatic reactor trip due to a turbine A yard generator trip caused hardly transformer is on-site plant fire USA 20070406 28 1, 2, 4 148 Exclude N/A USA USA043 20070406 by a fault on the 31 high voltage transformer 34.5 kV transformer yard inflammabl Yes Unknown 0:12 the originating brigade main transformer e liquid component phase B high voltage bushing A yard Under voltage cable transformer is actuation due to a loss outside turbine connector / on-site plant fire USA 19991009 29 1, 2, 4 7 Exclude N/A USA USA039 19991009 busbar 4.16 kV Yes Unknown 0:09 the originating of reserve station building insulation brigade component service transformer materials fixed extinguishing Explosion of an oil-A transformer system, manually filled current hardly is the high voltage transformer 6.6 kV / 400 actuated; shift FRA 20030830 29 1 None Exclude N/A France FRA024 20030830 transformer leading to switchyard inflammabl No Unknown 0:48 originating (current transformer) kV personnel; a fire in the 400 kV e liquid component external fire platform brigade participated flammable fixed A transformer liquid extinguishing is the Unit 6 forced outage switchyard, CAN 20050415 29 1 None Exclude N/A Canada CAN002 20050415 high voltage transformer 500 kV (transforme Yes system, Unknown < 00:08 originating due to M.O.T. failure switchgear room r insulating automatically component oil) actuated

FAQ Number 17-00020013 FAQ Revision 0 (Draft BC)

FAQ Title High Energy Arcing Fault (HEAF) Non-Suppression Probability (NSP)

Damage Reason for Voltage Limited to Extinguished Unique Outlier Time BIN *Reference FEDB # Include/Exclude Include/ Country Plant Date Event Title Component Location Fuel by (all means Duration [h:min]

Identifier (Y/N)/ Basis Level Initial Data Exclude involved)

Component outside the plant hardly A transformer Voltage transformer (Not switch yard), on-site plant fire inflammabl is the fire due to human medium or low voltage voltage No (multiple brigade (one fire);

FIN 20060927 29 1 None Exclude N/A Finland FIN002 20060927 15.1 kV e liquid,; Unknown 0:05 originating error during transformer - oil filled transformers near components) self- extinguished other component maintenance outage to main (another fire) insulations transformer fixed A transformer House transformer fire extinguishing is the induced by the medium or low voltage 19 kV /6.9 flammable system, manually JPN 20070716 29 1 None Exclude N/A Japan JPN047 20070716 outside Yes Unknown 1:55 originating Niigata- Chuetsu-Oki transformer - oil filled kV liquid actuated; external component earthquake fire brigade participated Auto fire alarm about other solid The rectifier is on-site plant fire an arc event in a material; part of the turbine building, No (multiple brigade; external SWD 20021030 33 1 None Exclude N/A Sweden SWD007 20021030 rectifier. The failure rectifier 600 V plastics / Unknown 2:31 exciter for the process room components) fire brigade led to stop of one polymeric turbine. participated turbine. materials Fire originated in the primary power HEAF - other USA 20011026 9999 4 10624 Exclude distribution N/A USA Unknown 20011026 electrical or electronic Unknown Unknown Unknown in-situ No Unknown Unknown Unknown pole that feeds equip the HEEC transformer.

basket contacts HEAF - other 13kV or 0930-USA 20080917 9999 4 50566 Exclude power line N/A USA Unknown 20080917 electrical or electronic Unknown Unknown in-situ Yes self-extinguished <0:05 greater unknown causing equip explosion Fire in the reactor containment: Arc in an plastics /

Vacuum SWD 20110510 9999 1 None Exclude N/A Sweden SWD008 20110510 electrical part in the vacuum cleaner Unknown containment polymeric No self - extinguished Unknown Unknown Cleaner portable vacuum materials cleaner "Special bin, Not FPRA Switchyard fire in Yes, special flammable on-site plant fire USA 20020612 SB4 1, 2, 4 113 Exclude applicable" USA USA059 20020612 34.5 kV circuit high voltage breaker 34.5 kV switchyard Yes Unknown Unknown Bin liquid brigade per NUREG breaker 2169

• Reference 1: NEA/CSNI/R(2013)6, Nuclear Energy Agency OECD Fire Project - Topical Report No. 1, Analysis of High Energy Arcing Fault (HEAF) Fire Events, June 25, 2013

• Reference 2: NUREG 2169, Nuclear Power Plant Fire Ignition Frequency and Non-Suppression Probability Estimation Using the Updated Fire Events Database, December 2014

• Reference 3: NUREG/CR-6850 Supplement 1, Fire Probabilistic Risk Assessment Methods Enhancements, September 2010

• Reference 4: EPRI 1025284, The Updated Fire Events Database: Description of Content and Fire Event Classification Guidance, July 2013