ML18233A469

Comment Disposition for High Energy Arcing Faults (Heafs) in Electrical Equipment Phase 2

ML18233A469
Person / Time
Site:	San Onofre
Issue date:	06/18/2018
From:	Nick Melly NRC/RES/DRA/FRB
To:	Southern California Edison Co
References
NRC-2017-0168
Download: ML18233A469 (34)

Text

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

Title:

Equipment Phase 2

• CLEARLY STATED AS A MATTER OF FACT (OR A SPECIFIC QUESTION)

• COMPLETE AND INCLUDE A REFERENCE TO THE AFFECTED DOCUMENT Comments shall be:

• LEGIBLE AND REPRODUCIBLE

• FOCUSED TO A SPECIFIC PROBLEM OR DEFIENCY Document Change to

1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section The HEAF event that occurred at SONGS-2/3 was the result of The cause of the SONGS event is not discussed in the draft 1 NEI No changes 4.1/1 incomplete breaker contact parting resulting in an extended arc at the test plan, and no changes to the test plan were made.

breaker contact.

The discussion states that the KEMA source is limited to 2,200 MVA The 2,250 MVA referred to the KEMA Laboratories' generator but it also states that it is insufficient to deliver the current necessary to maximum available generator power, not the power delivered simulate events at Robinson and Diablo Canyon. From a practical to the equipment. The KEMA power distribution is equipped standpoint, most medium voltage switchgears have ratings of 500 MVA with current and power-limiting components, allowing precise with some having higher ratings. The design basis calculations that are adjustment of delivered power to any level within that rating.

necessary to demonstrate compliance with the requirements of GDC The actual power delivered to the test equipment in each test Clarification in 17 must show that maximum possible fault conditions at the buses are will be documented in the test report and will not exceed the 2 NEI test plan 4.3/3 within their MVA ratings. The discussion in the test plan raises MVA rating of the equipment being tested.

Section 3 questions as to whether the fault conditions being imposed on the equipment, when analyzed using the same methods as would be required in design basis calculation shows that the MVA being delivered is within the equipment rating. The information presented in the test plan suggests that excessive fault conditions could be imposed. Exposing equipment to such conditions would result in a test that does not reflect the conditions in the US nuclear fleet.

The performance of a generator under faulted conditions is sometimes 2,250 MVA is the maximum available generator power. It is a represented in a short circuit decrement curve. This curve shows a nominal rating only. KEMA Laboratories uses a process of peak short circuit current and a decay that is a function of the machine super excitation to compensate for the decreasing rotational Addition of sub-transient and transient reactance and their associated time energy of the generator during energy delivery, thus the short decrement constants. It is unclear if 2,200 MVA that is quoted in the test plan circuit decrement curve is not the power delivered to the test curve for reflects the peak of this decrement curve or at some other point. An enclosure. This technique, routinely used at KEMA, is based medium voltage understanding of this behavior is critical to understanding and on superimposing an additional excitation source during tests will be confirming the applicability of the test of actual plant conditions. testing to boost the generated DC field. This process considered for compensates for reduction in the field by adding a 2a NEI 4.3/3 future addition supplementary source of DC power, allowing for steady to the test plan output current from the generator. The energy delivered to the (pending enclosure in phase one testing was specified by NRC staff, information recorded by KEMA's measurement equipment and reported provided by with the test results. There was no test performed at 2,250 EPRI) MVA.

Based on discussion from the HEAF Public Workshop held April 18-19, 2018 a decrement curve (to be provided by EPRI) will be considered for a future medium voltage test.

Where in the test planning process is confirmation that the test The test conditions specified in the Phase II draft test plan 2b NEI No changes General conditions - MVA, current, and decay of any asymmetrically come from two places: 1) U.S. operating experience, component is representative of the conditions in the US nuclear fleet. including review of plant electrical distribution equipment

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

Title:

Equipment Phase 2

• CLEARLY STATED AS A MATTER OF FACT (OR A SPECIFIC QUESTION)

• COMPLETE AND INCLUDE A REFERENCE TO THE AFFECTED DOCUMENT Comments shall be:

• LEGIBLE AND REPRODUCIBLE

• FOCUSED TO A SPECIFIC PROBLEM OR DEFIENCY Document Change to

1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section ratings and available fault current, and 2) the needs of the international partners participating in and contributing to the HEAF test program.

Based on discussion from the HEAF Public Workshop held April 18-19, 2018 a decrement curve (to be provided by EPRI) will be considered for a future medium voltage test.

The performance of a generator under faulted conditions as noted in In general, the performance of a generator under faulted comment 2a is dynamic. The information provided in Section 5 (40 kA conditions is dynamic; however, the KEMA Laboratories at 480 V for 8s, and 25 kA at 4.160 kV for 4s) suggests that short-circuit generator uses super excitation to compensate substantially higher fault conditions were imposed. More details for rotational speed decay. In regard to the peak asymmetrical regarding the imposed electrical conditions that are anticipated for this current, this is inherently enveloped by the laboratory power 3 NEI No changes 5 test are necessary. These parameters can be calculated consistent supply. The KEMA laboratory is also equipped with full control with that which would typically be done to demonstrate compliance with of point-on-wave current initiation, allowing precise control of GDC 17. Such a calculation should demonstrate the peak prospective peak current.

asymmetrical current (typically at half cycle) is within the equipment rating as well as the peak MVA.

The scope of test durations inherently envelopes the case where It is not disputed that operating experience shows the majority protective devices that may be available to terminate the HEAF event of arcing fault events are quickly terminated by protective have failed. It is unclear whether the scope of the test and the devices; however such events are not the subject of this test measuring and monitoring equipment will have sufficient time program. This test program is designed to evaluate the impact resolution to address the cases where protective devices are available of NUREG/CR-6850 "bin 16" events; i.e. arcing faults that are to terminate the event. not quickly interrupted by circuit protection schemes. Arcing faults that are quickly interrupted are usually classified as "arc flashes" instead of "HEAFs," and are counted in bin 15--if they are counted as challenging events at all. Only those events that see extended durations and extensive damage are 4 NEI No changes 4.4/multiple counted toward the HEAF frequency of bin 16, and it is those events that this test program seeks to quantify. The availability of protective devices is already credited in calculating the bin 16 frequency. If the deterministic ZOI were to account for the availability of circuit protection, then plants would be taking double credit--once in the exclusion of quickly-terminated events from bin 16, and once in the ZOI damage model.

This aspect of HEAF events is a current area of work through a joint EPRI/NRC Memorandum of Understanding group

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

Title:

Equipment Phase 2

• CLEARLY STATED AS A MATTER OF FACT (OR A SPECIFIC QUESTION)

• COMPLETE AND INCLUDE A REFERENCE TO THE AFFECTED DOCUMENT Comments shall be:

• LEGIBLE AND REPRODUCIBLE

• FOCUSED TO A SPECIFIC PROBLEM OR DEFIENCY Document Change to

1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section project. The definition of HEAF events and the frequency will be further refined and clarified.

It is unknown whether the results of this test will lead to the imposition Arc events which only last for 0.08 seconds do not constitute of a deterministic HEAF ZOI and does not allow any consideration of the HEAF frequency bin. The definition and appropriateness the availability of protective devices that would quickly terminate. of HEAF binning concerns an area of work being performed Depending on design details, the tripping of breakers to terminate under the EPRI/NRC MOU. Future work and refinement 4a NEI No changes 4.4/multiple HEAF event could be as fast 0.08 seconds. In some applications, given towards counting guidance for HEAF will be commensurate failure of the primary breaker, the backup breaker would trip within 2 with frequency bins, consistent with any revision to a ZOI seconds. The 2 second threshold is a typical criterion for the maximum method.

allowed delay on tripping a transformer supply breaker on a thru-fault condition.

The test plan seems to be focused on exposing the equipment to short None of the testing to be performed will subject any circuit conditions that approach (and possibly exceed their rating). It is equipment to conditions that exceed their ratings. As Change to unclear how these results can be applied to cases where the actual discussed above (See NEI Comment #2), there is a large Section 4.1- plant conditions are such that the fault conditions are margin included in the fault conditions imposed on the 4b NEI equipment 4.4/multiple substantially less than the equipment rating. For many plants, the equipment.

ratings not to be analysis of the medium voltage switchgear shows that the peak short exceeded circuit MVA occurs only when the EDG is paralleled for testing. In such cases, the short circuit during normal operating conditions is substantially less - resulting in notable margin the equipment rating.

The test plan indicates that the test enclosure will contain only a bus NRC staff agrees that there exists a high degree of variability bar and no in arcing fault scenarios. Ideally, each potential variable (bus other internal features. It is unclear how the lack of a physical breaker bar spacing, louvres, etc.) would be subject to and variability with respect to location of the actual bus bars in medium experimentation, and its effect incorporated into any physical and low voltage switchgears will influence the test results. It would model. In practice, isolating each variable is cost prohibitive.

seem the available void space within the enclosure would affect the For precisely this reason, the NRC hosted a phenomena Change to behavior of any transient conditions. The spacing of the bars identification and ranking table (PIRT) exercise in February of Section 6- themselves relative to the outer walls of the enclosure and any 2017. The NRC invited all participating OECD countries, 5 NEI 6/1 addition of ventilation opens (louvers) could introduce additional influences that EPRI, KEMA and NIST to the PIRT. The PIRT panelists breaker may reduce or exaggerate the consequences outside the enclosure. It identified the variables that are expected to have the most is not clear how these variables can or will be considered when post- significant impact on the resulting damage from a HEAF processing of the test results and developing HEAF ZOI application event. This research is documented in NUREG-2218. NRC guidance is developed. staff agrees that the presence of a physical breaker may have an impact on the results. The test program has been modified to include circuit breakers in all electrical enclosures to be tested.

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

Title:

Equipment Phase 2

• CLEARLY STATED AS A MATTER OF FACT (OR A SPECIFIC QUESTION)

• COMPLETE AND INCLUDE A REFERENCE TO THE AFFECTED DOCUMENT Comments shall be:

• LEGIBLE AND REPRODUCIBLE

• FOCUSED TO A SPECIFIC PROBLEM OR DEFIENCY Document Change to

1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section it is critical that any follow-on testing involve configurations that The April 18th- 19th public workshop provided the industry with NEI letter accurately reflect plant design and operations in order to provide a document for stakeholder feedback. This specific concern dated Test Parameter General 1 realistic insights. was raised during the workshop and changes to the test plan 05/17/201 changes Comment have been made to ensure subsequent tests are performed to 8

realistic plant conditions.

These tests should be performed using as realistic as possible fault There are several commercially available systems for arc fault conditions (e.g., fault current magnitude, duration, DC offset, decay, protection that do incorporate light intensity as part of the etc.). The NRC should consider HEAF testing to incorporate monitoring operating characteristics. However, the RES staff is currently NEI letter for parameters that are used as input for commercially available arc- not aware of any nuclear power plant (NPP) in the operating dated General 2 No changes flash protection relays. These parameters typically include light fleet that is using such a mitigation technique. The test 05/17/201 Comment intensity (sensed by point sensors or fiber optic cable) and sound program does not intend to test protective relay performance 8

pressure (by point sensors). or provide design solutions. The test program intends to test as built, as operated equipment. The durations of arc faults are informed by operating experience.

The OE doesnt support the realism of an 8 second arcing event at The Fort Calhoun was the only domestic low voltage OE this voltage level. Out of the OE that is being referenced, only the Fort where the fault duration lasted in excess of the testing Calhoun event had a long fault duration at the 480V level. That fault parameter of 8 seconds. However, there is international duration itself (42 seconds) was due to a severe design deficiency experience documented in the OECD Fire Project - Topical (misaligned stabs and zone select interface jumpers not being Report No. 1 Analysis of High Energy Arcing Faults (HEAF) disabled). This event is not representative of an actual fault event Fire Events where the fault persisted for 8.5 seconds. While where one or even two protection levels misoperate. For this reason the NRC staff agrees that these extended duration HEAF performing the 8 second test does not follow the mission for phase 2 events for low voltage cases may be less common, there is testing, which is realism. In addition, considering all the OE, the Fort no statistical basis for removing these events from analysis Calhoun event at 42 seconds is obviously an anomaly (next longest is based on the limited data available for the low voltage HEAF NEI letter 12 seconds), and thus would normally be removed from any statistical events. The incorporation of plant system design, fault dated Test Parameter General sample. protection schemes and a detailed fault timing analysis is a 3 current area of research work being undertaken by the NRC 05/17/201 changes Comment 8 In a scenario with single breaker misoperation, the protection upstream and EPRI under a Memorandum of Understanding agreement of the supply transformer will typically operate much faster than 8 to account for scenario specific arc fault timing analysis.

seconds. While it is true that upstream protection will operate in the thermal region, for high fault current levels detailed in the test plan the trip times will be closer to 4 seconds or even much shorter. Through discussions at the April 18-19 workshop the staff decided to focus the low voltage testing parameters on the 2 to 4 second range for the majority of test cases. This provides NRC representatives mentioned during the April 18-19 workshop that a better representation of the low voltage arc conditions from the longer testing, exceeding 4 seconds, could not be performed at the OE and will provide 1 to 1 comparison points between the low Medium Voltage level (MV) due to testing center limitations. Since the and medium voltage scenarios. However, the NRC staff still testing center is able to test for longer durations at LV, a longer test (8 intends to test a limited number of low voltage cases at seconds) was being done at LV. No testing should be done for sake of durations longer than 4 seconds. These extended duration

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

Title:

Equipment Phase 2

• CLEARLY STATED AS A MATTER OF FACT (OR A SPECIFIC QUESTION)

• COMPLETE AND INCLUDE A REFERENCE TO THE AFFECTED DOCUMENT Comments shall be:

• LEGIBLE AND REPRODUCIBLE

• FOCUSED TO A SPECIFIC PROBLEM OR DEFIENCY Document Change to

1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section testing without OE basis. If the test is performed at 8 seconds at LV, it low voltage tests will be used as data points to extrapolate should be categorized as experimental and not utilized to develop potential damage conditions for the medium voltage revised ZOI (Zone of Influence) and frequency for PRA. conditions where extended duration events can be postulated based on plant design. There is OE of longer duration arcing events for medium voltage events up to 11 seconds (Robinson; 3/27/2010 ~8-10 seconds, Diablo Canyon; 5/15/2000 ~11 seconds). However, it is currently well beyond the capabilities of the testing laboratory to replicate these extended duration fault conditions. The arc duration has been documented as a primary parameter of interest in both the PIRT report and through discussions at the April 18-19 workshop with industry representatives and will be essential for the creation of a dynamic zone of influence and the creation of modeling techniques which can be used to determine scenario specific HEAF damage states.

NEI letter A test at 2 seconds would be more interesting to the industry since the The National Fire Protection Association (NFPA) and the dated switchgear is designed for a 2 second fault event. Most testing is done Institute of Electrical and Electronic Engineers (IEEE) in 05/17/201 with a duration of 0.1 -1 second per IEEE C37 hence it would be a new colloabation with their research partners have performed a 8 General test and not repetitive. significant amount of testing under 2 seconds in duration.

4 No changes Comment The focus of this research is to complement that data in a region where higher energy faults are occurring and limited data exists. The NRC plans to work with NFPA and IEEE to review the short duration testing.

NEI letter Multiple licensees use a high impedance grounding system to limit the Plants utilize several grounding configurations within their dated fault current. This test plan does not specify the ground configuration, power distribution system. This topic was discussed at the 05/17/201 and so no comparison to the installed plant configuration can be made. April 18-19 workshop. An outcome of those discussions was 8 that test grounding configuration was not important General 5 No changes (unanimously ranked low by stakeholders), with the Comment exception of its influence on frequency. It was determined that the testing should use whatever grounding configuration ensures other test parameters are achieved (e.g., voltage, current, duration, etc.).

NEI letter The test methodology eliminates any component but the tested While the testing does not connect the bus bars to operating dated material/simulated bus bars. No bus bars are used in nuclear plants equipment the effect of this equipment is taken into account General 6 05/17/201 No changes that are not connected to something else - transformers, buses with when stipulating the fault conditions which will be experienced Comment 8 other components etc. Additionally, the bus bars are typically the at the point of initiation for the arc. Operating experience has strong part of the circuit, not the weak link. repeatedly shown that arcing events do occur on the bus bars

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

Title:

Equipment Phase 2

• CLEARLY STATED AS A MATTER OF FACT (OR A SPECIFIC QUESTION)

• COMPLETE AND INCLUDE A REFERENCE TO THE AFFECTED DOCUMENT Comments shall be:

• LEGIBLE AND REPRODUCIBLE

• FOCUSED TO A SPECIFIC PROBLEM OR DEFIENCY Document Change to

1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section and the frequency used in PRAs is directly linked to the operating experience in NUREG-2169 bins 15 & 16.

NEI letter The testing plan should be revised following consideration of other Through discussions at the April 18-19 workshop it was dated sources of analysis, research, design, and protection relating to HEAF, decided to work with EPRI to evaluate incorporating the Addition of 05/17/201 specifically IEEE Standard C37.20.7, IEEE Guide for Testing Metal- current decay into the current test plan. Other aspects of decrement 8 Enclosed Switchgear Rated Up to 38 kV for Internal Arcing Faults (may IEEE C37.20.7, IEEE Guide for Testing Metal-Enclosed curve for be relevant as to future test parameters - arc- duration, current decay, Switchgear Rated Up to 38 kV for Internal Arcing Faults are medium voltage DC offset, fault current, energy dissipation, etc.; may also be relevant irrelevant for the testing because the features such as tests will be as to effectiveness of energy dissipation features such as intended by directed vents, louvers, lifting panels and blowout panels are considered for General 7 provision of directed vents, louvers, lifting panels, blowout panels, etc.) not currently used in the operating NPP fleet electrical future addition Comment enclosures. The NRC RES staff is currently unaware of any to the test plan electrical switchgear enclosures which meet the guidance (pending presented in IEEE C37.20.7 in the current operating fleet. The information guide was first approved by the American National Standards provided by Institute in 2008 with a predominant focus on personnel EPRI) protection. These design requirements post-date the current fleet of operating NPPs.

NEI letter Regarding test results as reported in CNSI-R2017-7: Test 4, 5, 6 & 7 were designed to be tested for 3000 dated Test 4, 5, & 6, Westinghouse DS (480V) w/ aluminum - tests results milliseconds, 4000 milliseconds, 4000 milliseconds, and 4000 05/17/201 were not extraordinary, arc duration was 9, 300+, & 300+ milliseconds milliseconds respectively. These tests were considered failed 8 General tests due to the inability to maintain an arc for the intended 8 No changes Comment duration and do not reflect the damage states typically associated with HEAF events. Therefore there was no ability to evaluate the impact of the material properties influence on the state of damage.

NEI letter Regarding test results as reported in CNSI-R2017-7: Arc duration alone cannot explain the results from Test 23.

dated Test 23, IP-20 (480V) w/ aluminum - test result was extraordinary, The duration for Test 3 was 8128 milliseconds on copper 05/17/201 arc duration was 7000+ milliseconds. It is legitimate to question the conductors and the results vastly differed from that of Test 23 8 extraordinary test results where the arc duration was maintained for with aluminum. This comparison of test results based and the General more than a couple of seconds, specifically for Test 23, where a typical material properties of the bus bar is what led the NRC 9 No changes Comment plant design would provide electrical protection for the switchgear (e.g., research staff to question the impact of the conductive one or two upstream breakers with protective relaying, etc.). medium as an influencing factor for damage states.

Additionally, it can be seen through the video footage of the events that the involvement of the aluminum conductors occurs quickly in the respective tests.

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

Title:

Equipment Phase 2

• CLEARLY STATED AS A MATTER OF FACT (OR A SPECIFIC QUESTION)

• COMPLETE AND INCLUDE A REFERENCE TO THE AFFECTED DOCUMENT Comments shall be:

• LEGIBLE AND REPRODUCIBLE

• FOCUSED TO A SPECIFIC PROBLEM OR DEFIENCY Document Change to

1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section NEI letter Regarding test results as reported in CNSI-R2017-7: Event duration corresponds to relevant operating experience dated Test 26, copper bus bars (4160V) w/ aluminum duct - test result was at medium voltage bus bar events (See Diablo Canyon 05/17/201 extraordinary arc duration was 4000+ milliseconds. It is legitimate 05/15/2000).

8 General 10 No changes that the arc duration for Test 26 may represent actual conditions, as a Comment typical plant design may provide power to the bus bar directly from the power source (e.g., Main Generator, etc.) without any in-between electrical protection.

NEI letter Correlation of CNSI-R2017-7 (Test 23, IP-20) with the testing Unclear how this characteristic or design standard has any dated documented in KEMA 15201-B (trial 16, Finland Cabinet 1 LV impact on electrical behavior of arcing events.

05/17/201 Switchgear) is based on test date 10/16/2015, since there is no Test 8 23 identified in KEMA 15201-B, and since no specific manufacturer or model number is provided for the applicable switchgear associated with Test 23 in CNSI-R2017-7 or KEMA 15201-B. The Test 23 specimen is identified as IP-20, which represents a generic international Ingress General Protection (IP) rating, equivalent to a NEMA enclosure rating in the 11 No changes USA.

Comment IP20 signifies protection from touch by fingers and objects greater than 12 millimeters, not protection from liquids. IP20 is not waterproof or even spray proof, and may not be typical of US installations, which would likely use no less than IP22, protected from touch by fingers and objects greater than 12 millimeters; protected from water spray less than 15 degrees from vertical.

NEI letter Test 23 and Test 26 were performed in an open test cell (open to Test 26 was not performed in October. Test 26 was dated outdoor environment) in the month of October. The documentation in performed in January.

05/17/201 CNSI-R2017-7 and KEMA 15201-B does not specify how the test All test specimens were stored and prepared prior to testing in 8 specimens and/or monitoring instruments were stored or when the test an environmentally controlled storage space/workshop and rig was set up in the test cell. One must wonder if condensation might only moved into the open to outdoor environment on the day General 12 No changes have occurred on the test cell walls, the test specimens, and/or the of testing. The test cell has three walls and a roof, with only Comment monitoring instruments given the typical Pennsylvania weather in one side opening facing the control room. The test equipment October (cold nights, warm days). Furthermore, one also must wonder is located under the roof protection.

if condensation, if present, played any part in the extraordinary test results noted in Test 23 and Test 26. This may be a similar concern for future testing.

NEI letter General Test 23 and Test 26 were performed in an open test cell (open to Test 26 was not performed in October. Test 26 was 13 dated No changes outdoor environment) in the month of October. One must wonder how performed in January.

Comment and if the relative humidity played any part in the extraordinary test

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

Title:

Equipment Phase 2

• CLEARLY STATED AS A MATTER OF FACT (OR A SPECIFIC QUESTION)

• COMPLETE AND INCLUDE A REFERENCE TO THE AFFECTED DOCUMENT Comments shall be:

• LEGIBLE AND REPRODUCIBLE

• FOCUSED TO A SPECIFIC PROBLEM OR DEFIENCY Document Change to

1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section 05/17/201 results noted in Test 23 and Test 26. The level of relative humidity may Humidity was recorded on each day of testing and will be 8 impact how easily an arc can be established. In plant application, the reported in the Phase 2 testing report.

test specimens such as these (switchgear and some bus bars) are There is operating experience where humidity and potentially typically located in areas where the relative humidity is maintained saltwater spray has played an initiating role in HEAF events relatively constant. The test facility is capable of allows breakdown (See Narora fire event 1993).

testing as a function of gas composition and atmospheric/surface This topic was discussed at the April 18-19 workshop. An contaminants (e.g. humidity, saltwater spray, oil vapors and other outcome of those discussions was that atmospheric atmospheric contaminants). Humidity is not specified. Is what has conditions was not important (ranked low by 10 stakeholders been seen in Phase 1 actually metal water reaction? Results may vary and medium by 1), with an additional note to the influence on widely depending on humidity or other contaminants. This may be a frequency of occurrence.

similar concern for future testing.

NEI letter The documentation in CNSI-R2017-7 and KEMA 15201-B does not All equipment was procured through donation or purchased dated specify how the test specimens were procured or maintained, their by the NRC from operating NPPs.

05/17/201 General service life, service conditions, or service history, or if and how the test All modifications to equipment conditions was documented.

14 No changes 8 Comment specimens were modified to accommodate testing. These variables Each tested piece of equipment underwent hi-pot testing to might have an influence on the extraordinary test results noted in Test ensure that the arc could be reliably initiated where intended.

23 and Test 26. This may be a similar concern for future testing.

NEI letter The documentation in CNSI-R2017-7 and KEMA 15201-B does not All HEAF tests produce EMI and EMP effects not just the dated specify if electromagnetic interference (EMI) or electromagnetic pulse ones associated with the extraordinary results.

05/17/201 (EPM) was monitored during testing. It is possible that either or both All events from operating experience in real plant conditions 8 phenomena impacted the HEAF energy release, and if either or both are also accompanied by EMI and EMP effects.

phenomena had any influence on the extraordinary test results noted EMI monitoring is under current discussion for the phase 2 of General in Test 23 and Test 26. This may be a similar concern for future testing.

15 No changes testing.

Comment The influence of EMI was evident in the pressure recording measurements and has led to alternative means of pressure investigation i.e. the use of shielding and fiber optic cables.

In plant events are also accompanied by EMI and EMP conditions.

NEI letter There exists a concern regarding plants which credit ERFBS which is

• CSNI-R2017-7 does not base its conclusions based dated located within the HEAF ZOI (copper or aluminum) as part of their fire only on 2 out of 2 tests. The report characterizes the 05/17/201 protection program, deterministic or performance based. Specifically, influence of aluminum as follows; 8 General the concern is for the impact of HEAF explosion and subsequent fire to 16 No changes ERFBS located within the ZOI. This event may cause damage to the The experiments where aluminum was consumed Comment ERFBS and may also damage (due to HEAF explosion and during the HEAF resulted in more severe physical subsequent fire) the circuits protected by the ERFBS, thereby resulting damage to equipment than those involving only copper in spurious operation or loss of required function. It does not appear and steel at any voltage level. In both experiments that this failure mode and adverse impact is considered by where aluminum was consumed during the HEAF,

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

Title:

Equipment Phase 2

• CLEARLY STATED AS A MATTER OF FACT (OR A SPECIFIC QUESTION)

• COMPLETE AND INCLUDE A REFERENCE TO THE AFFECTED DOCUMENT Comments shall be:

• LEGIBLE AND REPRODUCIBLE

• FOCUSED TO A SPECIFIC PROBLEM OR DEFIENCY Document Change to

1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section deterministic regulation (Appendix R), since Appendix R fire area measurement devices were damaged or the maximum analyses are based on an assumed worst-case whole area burn from measuring range was exceeded. These instruments a floor-based fire and the deterministic analysis does not consider were unable to measure the actual maximum HEAF explosion. Furthermore, it does not appear that this failure mode temperature and heat flux.

and adverse impact is adequately addressed in the performance-based HEAF ZOI treatment guidance (NUREG/CR-6850), since performance- Tests 4, 5, 6 & 7 were designed to be tested for 3000 based treatment guidance may only address failure of ERFBS with milliseconds, 4000 milliseconds, 4000 milliseconds, respect to fire propagation, but not failure of circuits protected by and 4000 milliseconds respectively. These tests were ERFBS thereby resulting in spurious operation or loss of required considered failed tests due to the inability to maintain function. an arc for the intended duration. Additionally, only minimal amounts of aluminum were able to be consumed during the event due to the duration of the The test results as reported in CNSI-R2017-7 are not appropriately arc.

characterized. It is not 2 of 2 tests involving aluminum that exhibited extraordinary test results. There were 5 tests involving aluminum, and The test result conclusions took into account all the 3 of these tests did not exhibit any extraordinary test results beyond available data from all of the 26 tests to reach generic the current Fire PRA treatment for HEAF ZOI in NUREG/CR-6850.

conclusions and recommendations for future testing.

Furthermore, the white haze attributed with electrical failures in the The tests involving aluminum were clear outliers to extraordinary aluminum tests has not yet been confirmed as the damage states when evaluating test cases performed actual cause of these electrical failures, nor to my knowledge is there under similar conditions (See; Test 3 vs Test 23) any experience of whitewashing the entire room with the white haze in any of the recorded plant HEAFs, although some localized aluminum

• The white haze attributed with electrical failures in the oxide, splatter, slag, etc. has been noted in the associated fire event extraordinary aluminum tests has not yet been reports. confirmed and is a current area deemed important by the PIRT panel and being evaluated as part of Pre-GI-0018 PROPOSED GENERIC ISSUE ON HIGH ENERGY FAULTS INVOLVING ALUMINUM COMPONENTS. There is operating experience which also points to the influencing effect of this conductive byproduct and coating characteristic in several events.

For example; o Fort Calhoun Station, Unit 1 - June 7, 2011 The investigation also determined that combustion products from the fire caused a fault on the island bus side of the bus-tie breaker (BT-1B4A), which resulted in an overcurrent condition through two breakers (feeder breaker 1B3A and bus tie breaker BT1B3A). (ADAMS Accession No. ML113010208), and Fort Calhoun Station - NRC Special Inspection

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

Title:

Equipment Phase 2

• CLEARLY STATED AS A MATTER OF FACT (OR A SPECIFIC QUESTION)

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1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section Report 05000285/2011014; Finding of Preliminary High Safety Significance (ADAMS Accession No. ML12072A128).

o Columbia Generating Station August 5, 2009 The faulted bus section was located above the medium voltage switchgear SM-3 and damage from the molten metal produced by the fault included another high voltage bus and other cables in the area of switchgears SH-5 and SH-

6. (ADAMS Accession No. ML092870468), and Columbia Generating Station - NRC Special Inspection Report 05000397/2009010 (ADAMS Accession No. ML093580158).

Zion Nuclear Power Station, Units 1 and 2- April 3, 1994 After the termination of the fire, the licensee performed an assessment of the damage to the main generator and associated bus ducts. The A and B phase isophase bus ducts showed signs of excessive arcing. The corners of the 90-degree turns on both phase housings were blown outward, and aluminum spatter covered the general area of the fault Samples of molten metal and fire residue obtained from the A and B phase bus ducts and the C phase lead box were analyzed. The intent of this examination was to identify the presence of any conductive foreign material which may have contributed to the flashover of the A and B phases. Nothing out of the ordinary was found in this investigation. The majority of the material examined was identified as aluminum.

The white powder found in the ducts was identified as aluminum oxide. The aluminum deposits were a result of the arcing that occurred on the A and B phases, which are fabricated from aluminum. (Legacy ADAMS Accession No.

9801210070).

NEI letter Furthermore, any future NRC discussion or presentation regarding Human Error compounding fire event occurrences is not dated General industry HEAF events should endeavor to accurately note that the long outside the scope of fire PRAs nor should it used to influence 17 05/17/201 No changes duration of the arc-fault events at Fort Calhoun and Robinson were frequency of occurrence. NUREG-2169 addresses the Comment 8 caused or compounded by human performance errors. influence of testing and maintenance on fire frequency with an established rule set to account for events caused by plant

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

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1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section personnel which are quickly discovered and suppressed.

HEAF events typically do not meet these exclusionary criteria due to the rapid development and suppression challenges associated with the immediate electrical energy release.

NEI letter Issues Related to the interpretation of test results All the topics discussed in the Issues Related to the dated interpretation of test results are areas of current work being 05/17/201 The HEAF frequencies need to be developed to reflect both the testing addressed separately from the phase 2 testing program.

8 configuration and the plant configuration. For example, large HEAF ZOI Those efforts are being performed under a Memorandum of Understanding with EPRI. The definitions and binning events only protected by a single breaker should be not be apply to associated with HEAF events was discussed at the April 18 -

HEAF events protected by two breakers. Large HEAF ZOI that have 19 public workshop and will be issued as a joint NUREG to durations of faults greater than 4 seconds should only count events capture many of the ideas listed. This work will be done in where the fault was greater than 4 seconds. It appears that the target parallel to the testing program.

fault durations were orders of magnitude greater than what industry protection schemes would allow. They were also greater than the short-circuit rating of the transformers themselves. It is not physically possible to get these faults.

The criteria for the new bin classifications needs enhancement to reduce subjectivity as much as is possible. The criteria need to bound and bin, without ambiguity, subjectivity, or debate, all relevant arc fault General events to date.

18 No changes Comment

• No damage to component itself - no fire internal, no fire external

• Damage to component itself - no fire internal, no fire external, damage to external components

• Damage to component itself - no fire internal, no fire external

• Damage to component itself - fire internal, no fire external

• Damage to component itself - fire internal, fire external

• Event compounded by human error (Fort Calhoun, Robinson)

• Others The use of energy as a metric may be one enhancement to the bin classification criteria, but this may also be misleading given that arc-fault energy is released over time. Total energy release may meet or exceed a set threshold, but the impact from this energy release will depend on the arc-fault duration and the changing arc-current.

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

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1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section For the population of plant circuit breakers that, if failed, could allow propagation of an arc-fault into a HEAF event (a challenging fire event),

presumably breaker failures within this population are already counted as fail to trip on valid demand random component failures in the Internal Events PRA. The implications of possible double counting of these failures in the Fire PRA should be addressed As previously documented, many of the HEAF events that contribute to the HEAF frequency involve one or more breaker malfunctions that fail to clear the fault - it is requested that this statement is reflected in revised frequency for PRA. It is further suggested that a revised ZOI only be documented hand-in-hand with the revised frequency for PRA.

NEI letter During the Turkey Point event, it is notable that no other mechanical Information Notice 2018-09 Electrical Arc Flash Caused by dated damage was identified within the effective radius of the pressure wave Foreign Material Damages Fire Door explains the Turkey 05/17/201 generated by the HEAF. It is likely there are several other components Point event in detail. Pressure influences are a current area of 8 General and features located within the effective radius of the pressure wave research and will be evaluated in the Phase 2 of testing.

19 No changes Comment that could possibly have been damaged (e.g., electrical penetrations, Room barrier integrity is a staple of the defense in depth junction and terminal boxes, placards and signs, etc.). It seems odd principals and is relied upon heavily in the creation of fire PRA that a fire door was the only component located outside of the scenarios.

switchgear that was adversely impacted by the pressure wave.

NEI letter The previously-discussed test results were compared to the 2010 The cables which were sent to the NRC Office of Research dated Robinson Fire and having inspected the Robinson Fire damage. The did not include spatial reference information as to where the 05/17/201 Robinson HEAF damage was significantly less than predicted with the cables were located in relation to the HEAF initiation point as 8 current HEAF model. For example thermoplastic cables about 3 inches such the NRC letter that is referenced above (ML121070714) from the HEAF Cabinet were undamaged, but did show evidence of states some heating. These cables were sent to NRC Research, where the lack of cable damage was confirmed. The letter provided by NRC The electrical cables exposed to the Robinson HEAF event General Research stated that based upon the cables it summarized that 20 No changes which were sent to Sandia for analysis did not show the type Comment "NUREG/CR 6850 is likely overstating the damage in the zone of of damage which is proposed in Appendix M of influence". NUREG/CR6850. When tested for continuity, the cable taken from the first tray did not display insulation degradation between conductors. Appendix M of NUREG/CR-6850 denotes that any tray within 1.5 m (5) vertical distance of the top of the cabinet will be ignited and damaged at time T=0.

The first cable tray at Robinson was located 3 above the top of the cabinet. The model in Appendix M of NUREG/CR-6850

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

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1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section would over estimate the risks associated with damage to the first cable tray located within the ZOI. It should be noted that, based on the post fire analysis plant pictures, the level of damage on the cables exposed directly to the fire appears to be much greater than the sample that was shipped to SNL.

This implies that the cable shipped to SNL for analysis were not from the area of greatest heat impact. It is unclear at this point whether the cables at the greatest heat impact area would have shown the same conduit continuity. Based on the lack of specific location information to accompany the cables shipped to SNL, it is impossible to determine the applicability of this guidance in appendix M of NUREG/CR-6850.

Based on the information received the conclusions of the report document several recommendations for future efforts including (1) setting up direct communication between the laboratory, research project manager and utility site representative responsible for the event evaluation and shipment of the component(s), (2) a better understanding on what components will provided the most useful information, and (3) how to ship the component(s) to the laboratory without potentially inducing shipping damage.

NEI letter Comments Regarding the Premise of USNRC IN 2017-04: The wording of the information notice was intended to be all dated inclusive due to the limited information available based on a 05/17/201 limited number of tests performed. Suggestions contained in The information notice states:

8 information notices are not NRC requirements. Further guidance and clarification as to the aluminum components to This program has shown that HEAF tests involving aluminum resulted be considered will be developed based on the results of the in a significantly larger release of energy than HEAF tests involving Phase 2 of testing.

General copper. This aluminum involvement includes components, 21 No changes Comment subcomponents, or parts that form part of the normal current-carrying pathway (such as bus bars, breaker armatures, contacts, cable, etc.),

or components, subcomponents, or parts that could become involved in the fault current pathway as a result of a ground fault (housings, structural framework, adapters, cradles, wireways, conduits, draw-out or racking mechanisms, etc.). In addition to larger energy release during the HEAF event when aluminum is involved, RES staff also observed dispersal of electrically conductive aluminum byproducts

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

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1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section throughout the area. This byproduct was conductive and caused short circuiting and grounding of electrical equipment in the area. Through the testing program, RES staff observed that HEAF tests involving aluminum damaged test measurement and recording equipment and the electrical supply of the test facility well beyond the damage limits approximated in NUREG/CR-6850 (EPRI 1011989).

The second part of the paragraph appears to be too broadly worded and vague: or components, subcomponents, or parts that could become involved in the fault current pathway. There is no guidance provided or specific test data that points to what could become involved in the fault current pathway. It would be hard to tell which miscellaneous aluminum parts became involved in the fault current pathway from inspecting a breaker cubicle that has exploded/vaporized

- to tell if any of the miscellaneous aluminum parts vaporized/ejected due to becoming involved in the fault current pathway, or as a consequence of the resulting explosion and/or temperature rise in the cubicle.

However, the empirical test results would suggest that if aluminum components, subcomponents, or parts were contained within the representative typical switchgear that was tested containing only copper bus bars, breaker armatures, contacts, cable, then these aluminum components, subcomponents, or parts apparently did not contribute to HEAF damage beyond that which was expected (prior to test) for switchgear only containing copper bus bars, breaker armatures, contacts, cable. Thus, any such aluminum components, subcomponents, or parts should not be considered to become involved in the fault current pathway, where said items are contained within a typical switchgear containing only copper bus bars, breaker armatures, contacts, cable. The empirical test results would also suggest that any such aluminum items did not also contribute to the unexpected HEAF damage that was observed in tests of switchgear containing only aluminum bus bars, breaker armatures, contacts, cable.

Rather than the above statement from the information notice, the position based on the empirical test results presented in the body of

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

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1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section CSNI-R-2017-7 should be: If the switchgear does not contain aluminum bus bars, breaker armatures, contacts, cable, then the HEAF event should be selected for copper. The other miscellaneous components, subcomponents, or parts do not influence the HEAF damage any differently, regardless of what material the bus bars, breaker armatures, contacts, cable are constructed of We (Korea consortium) understood that one of HEAF project objectives A detailed description of the current HEAF evaluation is to modify the ZOI in NUREG/CR-6850 Chapter M with experiment methodology can be found in NUREG/CR-6850 and results. And the objective of test plan also is that the HEAF associated supplements. It is incorporated in the test plan by experimental data may be used by the NRC GIRP to determine the reference.

adequacy of existing HEAF ZOIs. But we cant find the detail The test plan methodology is to quantify and determine the description of ZOI methodology in the HEAF2 test plan. To meet the threat posed by the HEAF hazard (thermal heat flux, projectile objective, a methodology of ZOI should be formulated in before and characteristics, particle/fume dielectric characteristics, described in the HEAF2 test plan. pressure wave, etc.) When combined with the vulnerability of 1 Korea No changes 3 the targets to these threats, a ZOI could be determined. The current test plan will quantify the threats, not the vulnerabilities.

The results and data of this test program will be analyzed and a detailed methodology for HEAF damage states will be developed with EPRI under the MOU.

Member Countries of the HEAF Phase II project will serve as Peer Reviewers to the new methodology.

First phase of arcing fault is short and rapid release of electrical energy Pressure measurements from Phase 1 suffered from noise.

and it is own damage characteristics. All most same measurement Developments from KEMA and NRA/Leidos will be devices of previous HEAF test are used in HEAF2 test and Test data in incorporated into phase 2 to provide valid cabinet pressure previous HEAF test may not be shown in first phase of arcing fault measurements. The modified plate thermometers (PTs) in phenomena. Issues of previous HEAF test such as temperature, heat Phase I worked well for the initial HEAF phenomena except flux and pressure during first phase of arcing fault should be described under extreme conditions. The new thermal capacitance 2 Korea No changes 4.4 in the draft test plan. slugs are designed to capture the thermal conditions that exceed the PTs capabilities.

In addition to this, arc particle characteristics will be evaluated closely during a parallel Sandia National Laboratories small scale testing program.

Parameter In previous HEAF test, the range of voltage, current and arc duration The test matrix was designed to include experimental 3 Korea Table 3 are 480 ~ 10,000 V, 15 ~ 50 kA, and 2 ~ 9 sec. respectively. In draft comparisons at low and medium voltages and the influence of Change test plan, voltage of 480 V, 4160 V, current of 23 kA, 32 kA are aluminum. In order to have a reasonable number of

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

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1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section selected as test variables. Are there any reasons for such variable experiments, the nominal voltages needed to be limited. The selection and what is the representative of the selected test variables? NRC staff performed parameter search on a limited number of available U.S. operating nuclear power plants (NPPs) to determine appropriate parameters for voltage and current.

That sample plant data can be found at ADAMS

1. ML18081B300.

The final test plan reflects testing being performed at 480V and 6.9kV and fault currents between 25kA and 32kA.

Nuclear power plants normally adopted the electrical cabinets with The final test plan reflects testing being performed at 480V Figure 1, current range between 20 kA and 50 kA. So we suggest to change 32 and 6.9kV and fault currents between 25kA and 32kA.

4 Korea No changes Figure 2 kA into 50 kA or add 50 kA in test plan and also to change 23 kA into 32 kA related to the bus duct testing plan.

We can only participate by providing electrical cabinets to be tested The terms of participation are detailed in the Terms of 5 Korea No changes General instead of money. Reference document. In kind contribution of equipment is acceptable.

Choice of aluminum material. We fully understand the need for the As discussed at the preceding OECD/NEA HEAF working NRC to study aluminum as material, but we have several comments. In group meeting in Fall 2017, the exploration of aluminum France the majority of Bus Bars for electrical cabinets are made of cop- impact is primarily a concern for the United States. As a per or white copper. It seems to me that this should also be the case result, the test plan scope was revised to limit the number of for some other European partner. On the other hand for the Bus Duct, aluminum tests performed under the OECD/NEA umbrella, there is some aluminum bus but with only a steel enclosure and, there- and the NRC will likely supplement the test program with Scope Change fore, I agree with CRIEPI's comment No. 6. The matrix could be additional aluminum testing.

1 IRSN for OECD 4.4 simplified for the sake of representativeness for all partners and the participation global cost of the program. It could be envisaged to carry out all the tests with copper Bus Bar and to select the most penalizing in terms of ZOI to carry out tests with an aluminum bus bar. Below is an example of a test matrix with 14 tests instead of 24 for electrical cabinets.

Concerning the duct buses the same method could be applied and the following matrix defined 5 tests instead of 8.

Concerning the circuit breakers, my opinion is divided. They are not The test plan has been modified to include breakers inside necessary for the quantification of the ZOI but allow a more realistic the enclosures. See NEI comment #5 Change to configuration, as said by CRIEPI. We prefer to carry out a comparison Section 6-2 IRSN 6 test with and without circuit breaker to quantify the influence of this type addition of of equipment on the HEAF and the ZOI. If the influence is really breaker negligible we would make a substantial saving on the overall cost of the program.

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

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1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section In the case of electrical cabinets, we believe that they should be as NRC staff agrees that the homogeneity of cabinets is simple as possible but mainly all identical and with a good degree of important to increase repeatability and limit the introduction of sealing, representative of high-voltage cabinets. The fact that partners additional variability of results. However, a limited number of want to transfer some cabinets to the NRC to carry out the program is countries have indicated that their participation is contingent not necessarily a good thing, un-less of course to deliver all the upon being able to donate equipment in lieu of monetary 3 IRSN No changes 6 electrical cabinets of a campaign. contributions. In an effort to accommodate the program partners and limit cabinet variability, the agreement calls for equipment to be donated in multiples, and purchased equipment will be identical or very similar to the extent possible.

The majority of HEAFs in electrical cabinets are held with high voltage The majority of HEAF events in the US are also experienced and 380 V does not represent a real case for France. For example, two in medium voltage cabinets however the HEAF guidance tensions could be envisaged: development and application in probabilistic methods includes

• Minimum voltage but> 1kV all electrical enclosures 440 and above. Phase II of testing will 4 IRSN No changes 4.4

• Maximum usable voltage (???) collect data on the representative voltage cases and address the frequency split and potential damage state differences in follow on analysis efforts.

The test program scope does not allow itself to evaluate threshold initiation and extinction parameters.

Addtion of GRS's remark about cabinet targets with adjacent or opposite cabinets Section 8.2 has been added to address the configurations Section 8.2- is very interesting, but these configuration should increase the cost of associated with multiple cabinets in a lineup.

5 IRSN Multiple cabinet the program considerably. This option should be budget.

lineup A last comment concerning the arc duration, is 8 s should be As discussed in the response to the NEI comment regarding considered as a representative one? arc duration, the subject of this test program is arcing faults that are not quickly terminated by circuit protection devices.

Within that scope, arcing durations of several seconds are to be expected, and have been observed. Extended duration Test Matrix events have also been observed in non-US plants as well as 6 IRSN change with 4.4 phase I of HEAF testing.

explanation Based upon discussion in the April 2018 workshop it was agreed that the majority of the low voltage testing will be performed on the 2 to 4 second range cases. This provides a better representation of the low voltage arc conditions from operating experience and will provide 1 to 1 comparison points between the low and medium voltage scenarios. There

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

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1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section will be limited number of low voltage cases tested at durations longer than 4 seconds. These extended duration low voltage tests will be used as data points to extrapolate potential damage conditions for the medium voltage conditions where extended duration events can be postulated based on plant design.

In general, the test plan is enough detailed and meaningful. Moreover, Once the testing has been completed and the NRC and EPRI background with the HEAF operating experience and the history of the derived new HEAF ZOI models all member countries will OECD HEAF activities are outlined in a comprehensive way deriving benefit from this information.

1 GRS No changes General the indication that further HEAF experiments are needed. However, the needs of different member countries having participated in the HEAF experimental program do not come out clearly.

The general experimental approach with arc initiation, currents and No response required.

voltages of the arcs, arc durations needed for getting ensuing fires and 2 GRS No changes 4 the measurements foreseen are clearly outlined in enough detail with good arguments.

It clearly comes out that a comparison of components with and without No response required.

Aluminum is intended as a main results from the HEAF experiments.

3 GRS No changes 4.4 The number of experiments foreseen (probably 35) is sufficient to gain insights on different phenomena as well as for performing repeating experiments.

The arc durations for cabinet tests (2 s, 4 s and 8 s) are meaningful Two bus duct tests at a third duration (5s) have been added Scope Change and correlated to the international operating experience. For the bus to the test plan, and will be conducted if resources allow.

4 GRS 4.4 for OECD bars, only two different arc durations (1 s, 3 s) have been chosen, a third arc duration (5 s or 6 s) may be useful.

Measuring equipment chosen does reflect clearly the outcome of the No response required.

first test series. Positioning of measuring devices in different distances 5 GRS No changes 4.4 from the component to be tested provides an excellent means to check if the ZOI assumed within safety assessment needs to be adapted.

Two aspects are critical from German and probably other European The test plan has been modified to test enclosures at 480V institutions view-point, in particular concerning the cabinet arcing and 6.9kV.

Parameter experiments:

6a GRS 4.4 Only components on voltage levels of 480 V and 4160 V are intended Change to be tested. These components only reflect U.S. types of cabinets and bus ducts, while in Europe and perhaps also in Asia, components with other voltage levels are installed in NPPs. Typically, the lower voltage

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

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1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section level components in Germany cover 380 V to 400 V, the higher level breaker cabinets typically are on a voltage level of 6 V to 6.7 kV. Such components were already provided during the HEAF experiments, at least by France and Korea. The voltage levels chosen so far for the tests are not representative for European components.

Although discussed differently during the PIRT exercise as well as at Section 8.2 has been added to address the configurations the last HEAF meeting in May 2017 in Helsinki, up to now no cabinet associated with multiple cabinets in a lineup.

Additon of experiments with multiple cabinets either side by side (with an air gap Section 8.2-6b GRS or directly adjacent) or opposite to each other (back to back with only a Multiple Cabinet small gap or front to front separated by a walkway) are foreseen, Lineup although these are the typical configurations in nuclear installations which need to be analyzed.

The stronger focus on bus bars in line with the U.S. interests is Section 8.2 has been added to address the configurations understandable; however, one of the PIRT reflections was the associated with multiple cabinets in a lineup.

international interest in electrical cabinet arc experiments with banks of Additon of cabinets. PIRT members mentioned that such configurations better Section 8.2 7 GRS 4.4 represent the real situation in nuclear installations. It was proposed that Multiple Cabinet in case of such cabinet tests some of the cabinets in a multiple cabinet Lineup configuration may be re-placed by dummy cabinets for saving money and being able to perform more tests. This also needs to be considered in the test program.

In conclusion, it has to be clearly stated that in the frame of an OECD The test plan has evolved from the one first reviewed by the project, the experimental program has to reflect the needs of potential OECD member countries to incorporate their needs.

partners. So far this is not yet the case. From the German viewpoint, 8 GRS No changes General for participation in the HEAF Phase 2 project, the test plan has to be changed accordingly. Moreover, the insights from the HEAF PIRT exercise need to be reflected more explicitly.

Comment: Objective of the test plan should be made clear. The test program has been modified to include circuit Opinion: NRCs proposal seems to seek the ZOI for the first phase of breakers in all electrical enclosures to be tested.

the HEAF phenomena, such as instant pressure and energy release, Change to the scattering of the vaporized conductive particles and the projectile Section 6- from the cabinet because the circuit breaker will not be installed.

1 CRIEPI 3 Addition of Nevertheless, due to the lack of the CB (Circuit Breaker), the pressure circuit breaker transfer path and maximum value will be considerably affected, and this fact will lead the uncertainty of the evaluation results from the point of view of the realistic configuration.

If NRC also consider the second phase of the HEAF phenomena, the

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1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section CB and internal structure should be considered even if we have to bear the decrease of the number of the test.

Comment: What is the corresponding HEAF scenario? The test program has been modified to include circuit Change to Opinion: If the CB will not be installed, what kind of the HEAF scenario breakers in all electrical enclosures to be tested. Arc initiation Section 6- will meet to this arc initiation condition? (Arc occurrence at the primary location will be selected when enclosures are procured to 2 CRIEPI 4.1 Addition of terminal in the cable room or at the secondary bushing in the reflect operating experience and accommodate measurement circuit breaker postulated CB?). We believe the compatibility of the real cabinet should reliability.

be assured up to some extent.

Comment: The feasibility of the measurement should be considered. Feasibility studies are being performed by NIST in a cone Opinion: According to the HEAF pahse1, the effectiveness of thermal calorimeter. Small scale testing is being performed at Sandia measurement seems to be not clear. Moreover, in the proposal, some National Laboratories in a separate NRC funded test program 3 CRIEPI No changes 4.4 challenging measurement seems to be included. So, the feasibility to characterize arc particulate.

study, such as calibration tests should be shown before installation to the test.

Comment: The 4160V condition seem to be too low. The test plan has been modified to test enclosures at 480V Parameter 4 CRIEPI Table 4 Opinion: In Japan, we have no use of 4160V cabinet. We prefer higher and 6.9kV. This will address the needs of all member Change voltage, such as 6.9kV. countries.

Comment: Test parameter should be decreased to optimize the The test data will be evaluated and discussed at subsequent number of the test. meetings to evaluate if current is a primary driver and Opinion: As key design parameter may be Arc Energy according to parameter of interest in terms of arc energy.

our findings from our HEAF tests, the value multiplied by the current and time will be the preferable parameter. So, we propose the use of one current level (such as 32kA) with the wide range of the arc duration time.

Moreover, we found the linearity between the arc energy and the value multiplied by the current and time. So, if we could see the same No changes tendency, the number of the repeatability test can be minimized.

5 CRIEPI (evaluated mid Table 4 test series)

• Right hand figure shows our test results, which had been executed under the arc current of the 20kA and 45kA. It seems that linear relationship between arc duration and arc energy were obtained, so we believe the influence of arc current will be negligible.

=> It may be caused by different test condition.(e.g. 20kA : non-seismic, 40kA : Seismic-proof, different cabinet, etc). We think that higher arc current results in higher arc energy during same arc duration. More detail data and test condition shall be provided to conclude that the influence of arc current will be negligible.

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

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Equipment Phase 2

• CLEARLY STATED AS A MATTER OF FACT (OR A SPECIFIC QUESTION)

• COMPLETE AND INCLUDE A REFERENCE TO THE AFFECTED DOCUMENT Comments shall be:

• LEGIBLE AND REPRODUCIBLE

• FOCUSED TO A SPECIFIC PROBLEM OR DEFIENCY Document Change to

1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section Comment: The use of aluminum for bus duct material will not be Initial indications from the USA indicate that bus bars very realistic. commonly use aluminum housing materials. The bus bars Scope Change 6 CRIEPI Table 5 Opinion: In Japan, we have no use of bus duct made of aluminum. So, and use of aluminum housing has been shifted primarily for OECD copper bus with Al enclosure or Al bus with Al enclosure can be towards the US only portion of the test program.

eliminated to optimize the test matrix.

Change to Comment: Use of CB is essential. See NEI comment #5 Section 6- Opinion: In Japan, all of our HEAF tests is compatible to the standard 7 CRIEPI 6 Addition of or code approved internationally. So, to assure the reliability of the test circuit breaker results, the use of CB should be important.

Comment: The feasibility of the measurement should be considered. See CRIEPI comment #3 8 CRIEPI No changes 7 Opinion: The same comment as #3.

Comment: Compartment pressure measurement will not be necessary. New pressure measurement techniques will be use for Phase Opinion: As many arc test had been executed in the closed condition II of testing. Recent U.S. operating experience has shown the 9 CRIEPI No changes 7.6 world-widely, and the empirical formula and the numerical tools have importance of room pressure build up for room integrity.

been developed, the literature works will be enough.

Change to Comment: Use of CB is essential. See NEI comment #5 Section 6- Opinion: The same comment as #7.

10 CRIEPI 8.1 Addition of circuit breaker Comment: Reconsider the test parameter The test matrix was designed to include experimental Opinion: Application of higher voltage will be preferable. By applying repeatability with the study of HEAF at low and medium unique current level, the expected arc energy should be selected as a voltages and the influence of aluminum. In order to have a dominant parameter. reasonable number of experiments, the nominal voltages needed to be limited. The NRC staff performed parameter search on a limited number of available U.S. operating Parameter 11 CRIEPI Table 8 nuclear power plants (NPPs) to determine appropriate Change parameters for voltage and current. That sample plant data can be found at ADAMS #ML18081B300.

The final test plan reflects testing being performed at 480V-6.9kV and 25kA-32kA respectively to accommodate all members.

Comment: Optimization of the test program See NEI comment #6 12 CRIEPI No changes General Opinion: In Japan, HEAF requirement was newly imposed in 8th August. So, Japanese industries are obliged to execute the good number of the HEAF tests using the high and low voltage switchgears

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

Title:

Equipment Phase 2

• CLEARLY STATED AS A MATTER OF FACT (OR A SPECIFIC QUESTION)

• COMPLETE AND INCLUDE A REFERENCE TO THE AFFECTED DOCUMENT Comments shall be:

• LEGIBLE AND REPRODUCIBLE

• FOCUSED TO A SPECIFIC PROBLEM OR DEFIENCY Document Change to

1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section to demonstrate the design base condition. From Japanese industry side, considering the financial aspect and the avoidance of the duplicable research activities, we are expecting the original outcome, especially for the appropriate methodology to setup the ZOI for 1st and 2nd HEAF phenomena under the international consensus.

Comment: Financial aspect Scope reduced for OECD members. Reflected in the test Our possibility: CRIEPI will participate as a representative of Japanese matrix.

Scope Change 13 CRIEPI General utilities. As annual payment in FYH2018 seems to be difficult due to the for OECD late negotiation with stake-folders, CRIRPI can only bear the budget by annual installment payment through FYH 2019 to 2021.

Further exploration into aluminum oxidation has been noted in the test The proposed test plan will investigate the range of credible plan without specificity. From the published test reports, significant arc faults and durations experienced from a review of aluminum oxidation was only observed in test conditions imposing operating experience. Short duration faults i.e. 2 second arcs severe arcing methods (i.e., extended duration faults beyond the rating will also be explored for the aluminum oxidation effects. All of switchgear and breakers). tests will assume the loss of the primary breaker or an alignment where no breaker protection is available allowing General This test plan should investigate the threshold at which there is for extended duration arcing events. Threshold values such 1 EPRI No Changes Comment potential for significant oxidation of aluminum to occur. For example, in as minimum voltage to sustain an arc or minimum duration to NUREG/IA-0470 only two out of seven cases had higher energy evaluate oxidation levels is currently not feasible with the release by the oxidation than by the arc, so scenarios with postulated amount of tests described in the test program to evaluate high oxidation were less common. primary parameters of interest. Particle collection and post Potential factors to consider include; rated short-time withstand current, test analysis will be explained for the full scale series.

credible arc location, loss of primary breaker, and proper operation of back up breaker.

Page 8, The PIRT list was ordered by priority (high importance/low state of Limited amounts of damage information was obtained by Section 1: knowledge). The first scenario, which is presumably one of the most mock cable tray arrangements in the first phase of testing. No Background important scenarios is HEAF occurring in an electrical enclosure with a cable trays will be added to the test plan. It was decided to

[2nd cable tray passing over the enclosure. This scenario is not addressed measure more scientific Heat Flux information will be paragraph] in the test plan. collected at various locations around the electrical enclosure 2 EPRI No Changes to collect exposure data which will then be applied to different The test plan should be modified to include testing of electrical target fragility information. Cable coupons will be positioned enclosures with overhead cable trays. Sufficient testing of this on the instrumentation test racks.

equipment could provide valuable information concerning the potential ZOI validation.

Page 8, Arc mitigation - The test plan does not acknowledge protective See NEI Comment #4 3 EPRI No Changes Section 1: devices (e.g., circuit breakers) as arcing mitigation devices. Circuit breakers are acknowledged by IEEE Std. C37.20-2007 as arc duration

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

Title:

Equipment Phase 2

• CLEARLY STATED AS A MATTER OF FACT (OR A SPECIFIC QUESTION)

• COMPLETE AND INCLUDE A REFERENCE TO THE AFFECTED DOCUMENT Comments shall be:

• LEGIBLE AND REPRODUCIBLE

• FOCUSED TO A SPECIFIC PROBLEM OR DEFIENCY Document Change to

1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section Background limiting devices with some tests utilizing the breaker to control the arc

[3rd bullet] duration.

The test plan should include a discussion on why protective devices are not considered in the test plan for arc duration control.

Page 9, The test plan should investigate if medium-voltage switchgear No tests will be performed at durations below 2 seconds. The Section 4: (equipped with either a copper or aluminum bus bar) can tolerate a purpose of the tests is not to validate performance according Experiment HEAF per IEEE Std. C37.20-2007 guidance. to the EEE Std. C37.20-2007 guidance.

al Approach The test plan should be modified to include two control specimens; one 4 EPRI No Changes medium-voltage switchgear containing copper bus bars and one containing aluminum bus bars, respectively, to be tested per IEEE Std. C37.20-2007 using a protective device (circuit breaker) or other IEEE acceptable method to limit the arc duration to 0.5 seconds using 24 AWG arcing wire.

Page 9, It is important to understand the phenomenological causes and impacts The tests will be performed as close to identical as possible in Section 4: of differences between copper and aluminum oxidation in HEAF an attempt to limit variability for comparative purposes.

Experiment scenarios.

al Approach 5 EPRI No Changes It should be confirmed in the test plan that the electrical cabinets containing aluminum bus bars and copper bus bars will be identical with respect to design, dimension, etc. with the exception of the bus bar material used (i.e. aluminum bus or copper bus). This is critical to the investigation of the aluminum oxidation phenomena.

Page 9, IEEE Std. C37.20.7-2007 & Corrigendum 1, Clause 5.3 states the arc Medium voltage arcs (>1000V) will be initiated using a 0.51 Section shall be initiated by a 24 AWG copper wire for medium voltage gear. mm diameter (24 AWG) stranded copper wire, strung across 4.1: Arc The test plan specifies the use of 10 AWG copper wire for medium the three phases of power within the electrical cabinet, at the Change to Initiation/Lo voltage gear, and yet references IEEE Std. desired initial arc location per the IEEE guide for Testing 6 EPRI Section 4.1- cation C37.20.7-2007. Metal-Enclosed Switchgear Wire Size [1st paragraph] The test plan should address the change in wire size and basis (or justification). Corrigendum 1 also states the wire should be ASTM Class K fine strand.

Page 9, The test plan states operating experience from HEAF events will be The NRC used the guide as the basis for the initiation of the 7 EPRI No Changes Section used to select representative arc locations within the enclosure. This arcing events but the investigation differs from the goals of 4.1: Arc departs from IEEE Std. C37.20.7-2007 Section 5.3 that states the point the IEEE guide. The NRC testing is attempting to replicate Initiation/Lo of initiation shall be located at the furthest accessible point from the OpE events and has different goals than the IEEE guide. All

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

Title:

Equipment Phase 2

• CLEARLY STATED AS A MATTER OF FACT (OR A SPECIFIC QUESTION)

• COMPLETE AND INCLUDE A REFERENCE TO THE AFFECTED DOCUMENT Comments shall be:

• LEGIBLE AND REPRODUCIBLE

• FOCUSED TO A SPECIFIC PROBLEM OR DEFIENCY Document Change to

1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section cation supply within the compartment under test. What is the basis for the cabinets tested will be representative of a credible scenario

[1st deviation from the standard? The concern with this approach is with limited modifications. The NUREG/IA-0470 series tests paragraph] allowing electrical enclosure modifications (similar to the MCC Tests 1, were performed by JNRA and contractors with a specific 2, and 3 in NUREG/ IA-0470 that removed up to 24 inches of arc phenomena under investigation. Minimal cabinet chute to achieve the targeted arc duration). modifications will take place and all will be documented in the test report.

Test plan should require for every change in arc initiation location as to which OE event is based off, of or if it is intended to be exploratory and not representative of a credible scenario (e.g., enclosure modification).

Additionally, the test plan should include documentation of enclosure modifications. This would include an assessment if the modified gear remains representative of a typical, actual plant installation. For example, in NUREG/IA-0470 Section 3.3 MCC Tests 2 and 3, removed 24 of arc chute to allow the arc to continue for the full duration of 2 seconds. This is an example where this modification is not representative of actual installation.

Page 10, Additional parameters of the KEMA power source should be captured All KEMA power source parameters will be documented and Section to determine IEEE fault parameters. This data can be used to correlate reported in the final test report.

4.2: to actual station short-circuit behavior.

Arc Current/Volt The test plan should model the capability and expectations of the age Page KEMA Laboratory power source (not just current amplitude and 8 EPRI No Changes 11, Section duration) so IEEE fault parameters can be determined (e.g., 1/2 - cycle, 4.3 5-cycle, and 30-cycle currents, voltage profile, and X/R for the test Duration configuration).

Page 16, Section 5 Experiment al Facility Page 10, In regards to the OE statement that protective devices have not The test duration parameters are based on OpE both US and Section always worked as designed. That is a credible failure scenario. international. There is one international operating experience 4.3: However, it should be acknowledged that the backup protection (e.g. event documented in the OECD FIRE Project - Topical Report Change to Duration next upstream breaker in a selectively coordinated system or breaker No. 1 (http://www.oecd-nea.org/nsd/docs/2013/csni-r2013-9 EPRI Section 4.3-Test [1st & 2nd failure scheme) is expected to operate to clear the fault (which the 6.pdf) that experienced and 8 second fault duration. The Durations paragraphs] design factors in the additional clearing time when selecting equipment backup protection device timing will be associated with the ratings). According to the durations proposed (and also tested in Phase fault current and resistance which is largely an unknown 1), the testing makes an implicit assumption that both primary and parameter.

backup breaker protection has failed. From EPRIs review of operating

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

Title:

Equipment Phase 2

• CLEARLY STATED AS A MATTER OF FACT (OR A SPECIFIC QUESTION)

• COMPLETE AND INCLUDE A REFERENCE TO THE AFFECTED DOCUMENT Comments shall be:

• LEGIBLE AND REPRODUCIBLE

• FOCUSED TO A SPECIFIC PROBLEM OR DEFIENCY Document Change to

1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section experience, the majority of long duration faults are due to generator Based on the April 18 -19, 2018 NRC public workshop the coast down. There have been limited instances (2-3 events) in the test plan has been modified to reflect that the majority of the operating history in which primary and backup protection have failed, low voltage testing will be performed on the 2 to 4 second representing multiple failed barriers. Characterizing all HEAFs in this range cases. This provides a better representation of the low manner (all protection has failed) is bounding, but is excessive voltage arc conditions from operating experience and will considering all HEAF events. provide 1 to 1 comparison points between the low and medium voltage scenarios. There will be limited number of The use of bounding data in probabilistic risk assessment is low voltage cases tested at durations longer than 4 seconds.

troublesome as the testing is set up to represent the less likely / higher These extended duration low voltage tests will be used as consequence scenarios. The testing should represent the range of data points to extrapolate potential damage conditions for the expected outcomes and not the most severe. medium voltage conditions where extended duration events Aside from the Fort Calhoun event (which may be described as a can be postulated based on plant design. The arc duration sputtering fault), what is the basis for the extensive durations in the 480 has been documented as a primary parameter of interest in V tests? Are the durations chosen based on operating experience or both the PIRT report and through extensive discussions at the capabilities of the laboratory power source? April 18 -19, 2018 NRC public workshop and will support Recommend that the duration parameter for the 480 V tests be re- improvements to modeling techniques which can be used to examined to better cover the range of scenarios expected. determine scenario specific HEAF damage states.

Page 11, The draft test plan proposes arc duration of up to 8 seconds for low See HEAF definition- The NRC is not attempting to replicate Section voltage enclosure testing, up to 4 seconds for medium voltage industry qualification tests. All test information will be used to 4.3 enclosure testing, and up to 3 seconds for bus duct testing. These create a methodology that can be applied to durations of Figure 1 proposed arc durations exceed typical switchgear and circuit breaker various lengths of time. The full spectrum from 1-8 seconds Figure 2 short-time current withstand ratings and IEEE C37.20.7- 2007 test will be investigated in order to develop a comprehensive guidance as follows: HEAF methodology.

• Switchgear short-time current withstand rating is typically 2 seconds

• Circuit breaker short-time current withstand rating is typically 3 seconds.

10 EPRI No Changes

• IEEE Std. C37.20.7-2007, Section 4.3 states preferred arc duration of 0.5 seconds. Test durations greater than 1.0 seconds is considered unnecessary.

Test results may not be meaningful and applied if they exceed both equipment ratings and IEEE arc testing guidance.

Similar to the comment for page 9, Section 4 Experimental Approach.

The test plan should be modified to include two control specimens; one medium-voltage switchgear containing copper bus bars and one containing aluminum bus bars, respectively, to be tested per IEEE Std. C37.20-2007 using a protective device (circuit breaker) or other IEEE

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

Title:

Equipment Phase 2

• CLEARLY STATED AS A MATTER OF FACT (OR A SPECIFIC QUESTION)

• COMPLETE AND INCLUDE A REFERENCE TO THE AFFECTED DOCUMENT Comments shall be:

• LEGIBLE AND REPRODUCIBLE

• FOCUSED TO A SPECIFIC PROBLEM OR DEFIENCY Document Change to

1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section acceptable method to limit the arc duration to 0.5 seconds using 24 AWG arcing wire.

Page 11, Strength: The use of a wide variety of M&TE to record and monitor the No response required Table 2: HEAF event. This is a significant improvement over the IEEE Std. 11 EPRI No Changes Metrology C37.02-2007, Section 5.4 Indicators (for observing the thermal effects of gases).

Page 12 Test plan, nor Table 3 include the short-time current withstand rating of All tests will be performed within the electrical cabinet regarding electrical cabinets and bus ducts selected to be tested. Therefore, it equipment ratings, and the equipment ratings will be reported Change to possible cannot be ascertained if the arc exposure (magnitude and duration) are in the final test report.

Section 4.1 - variations in within the equipment ratings.

12 EPRI equipment equipment ratings not to be and Include short-time current withstand rating of electrical cabinets and exceeded Table 3 bus ducts to verify that the test current amplitude is within equipment ratings, or if not within the equipment rating, provide basis/reason for exceedance.

Page 12, Gauge of electrical cabinet is not mentioned in the test plan. Electrical enclosures will be procured based on regarding recommendations from the April 18 -19, 2018 NRC public possible Gauge of electrical cabinet should be addressed in the test plan and workshop and are intended to be representative of the current 13 EPRI No Changes variations in selected to be representative of the entire line (e.g. thinnest gauge). NPP operating fleet. Electrical enclosure specifications will be equipment shared with EPRI under the NRC MOU prior to testing and all and parameters will be documented in the final report.

Table 3 Page 12, Table 3 is not specific to the combination of delta & wye systems and Power system configuration and grounding configuration were Table 3: grounded vs. ungrounded (floating). It should be confirmed that the determined to be a minor parameter of importance at the April Potential intended the test power connections will represent typical plant 18 -19, 2018 NRC public workshop. The final report will experiment configurations. Ungrounded delta systems are used in nuclear power document the specific power supply configurations and al variables plants; however, unground wye systems are uncommon. grounding methods used in each test series.

14 EPRI No Changes The test plan should be updated to clearly define the specific power supply configurations and grounding methods to be used (including cabinet grounding). IEEE Std. C37.20-2007 Sections 5.1.1.d, 5.1.5.d, and 5.2.6 provide additional guidance on grounding connections.

Page 13, Figure 1 provides two current levels for the 480 V tests. The higher All tests will be performed within the electrical cabinet Test Figure 1: current outlined in tests D, E, F, P, Q, and R are listed as 32kA. equipment ratings. The low voltage test will be tested at 15kA 15 EPRI Parameters Electrical and 25 kA based on the NRC staff parameter search on a Change cabinet Test plan should confirm that 32kA does not exceed the switchgear limited number of available U.S. operating nuclear power experiment withstand rating for the device under test (DUT).

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

Title:

Equipment Phase 2

• CLEARLY STATED AS A MATTER OF FACT (OR A SPECIFIC QUESTION)

• COMPLETE AND INCLUDE A REFERENCE TO THE AFFECTED DOCUMENT Comments shall be:

• LEGIBLE AND REPRODUCIBLE

• FOCUSED TO A SPECIFIC PROBLEM OR DEFIENCY Document Change to

1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section al plants (NPPs). That sample plant data can be found at conditions ADAMS #ML18081B300.

Page 16, The test plan indicates that cabinet/electrical enclosure will be devoid See NEI comment #5 Section 6: of breakers:

Electrical IEEE Std. C37.20-2007, Clause 5.1.1 Considerations for all Change to Cabinets equipment recommends minimizing the free volume.

Section 6- The absence of a breaker in the cubicle is unrepresentative of actual 16 EPRI Addition of equipment configuration. This also presents an increase in free Circuit Breakers volume.

Test plan should consider using a mock circuit breaker in the cubicle with the arc, even if the breaker is not used for arc interruption.

Page 16, The test plan allows relocation of the arc wire if arc is not sustained for The test plan and report will acknowledge rational for moving Section 6: the desired duration (the arc wire may be moved to another location). the arc location. The NRC tests do not intend to replicate the Electrical Per IEEE Std. C37.20-2007, Clause 5.3, the point of initiation shall be IEEE guide.

Cabinets located at the furthest accessible point from the supply within the

[2nd compartment under test.

17 EPRI No Changes paragraph]

The test plan should acknowledge this departure from the IEEE standard along with the basis. Arc re-location should address if the location is considered a credible fault initiation location (e.g. exposed metal surface in insulation transition points).

Page 17, There were many M&TE failures in previous HEAF tests (NUREG/IA- This is currently being taken into consideration by the NIST Section 7: 0470 and NEA/CSNI/R(2017)7). technical lead. The importance of reliable data measurement Instrumenta is a primary focus for Phase II of testing.

tion and It should be confirmed that the M&TE lessons learned from:

DAQ 1. NUREG/IA-0470, Nuclear Regulatory Authority Experimental 18 EPRI No Changes Program to Characterize and Understand High Energy Arcing Fault (HEAF) Phenomena.

2. NEA/CSNI/R(2017)7, Report on the Testing Phase (2014-2016) of the High Energy Arcing Fault Events (HEAF) Project have been incorporated in this Phase 2 test plan to ensure preventable sensor failures.

Change to Page 18, The mesh size of the instrument rack does not appear to meet the The test series will not replicate IEEE Std. C37.20-2007 for 19 EPRI Instrument Rack Section guidance of IEEE Std. C37.20-2007, Section 5.4.3, which is the indicator mounting racks. The instrument racks are being Design 7.2, Figure approximately 3 x 3. The intent is sufficient area to allow gases to designed to allow for maximum pass through while pass freely through the instrument rack. Figure 8 appears to cause maintaining a sufficient amount of instrumentation. The

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

Title:

Equipment Phase 2

• CLEARLY STATED AS A MATTER OF FACT (OR A SPECIFIC QUESTION)

• COMPLETE AND INCLUDE A REFERENCE TO THE AFFECTED DOCUMENT Comments shall be:

• LEGIBLE AND REPRODUCIBLE

• FOCUSED TO A SPECIFIC PROBLEM OR DEFIENCY Document Change to

1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section 8: Slug unnecessary restriction. instrumentation racks will use cross bars to mount Calorimeter instrumentation rather than a mesh design.

It is recommended to follow IEEE Std. C37.20-2007 for the indicator mounting racks. It eliminates one more variable to be accounted for in attempting to correlate results from the testing to IEEE Std. C37.20-2007.

Page 20, The attempt to collect pressure measurement within sealed The test plan internal pressure measurements will be used to Section compartments deviates from the other objectives of the test plan evaluate possible room pressure increases like that 7.6: (determination of escaping plasma and gases from the electrical documented at Turkey Point Information Notice 2018-09 Compartme cabinet and the conditions resulting in ensuing fires). validate existing pressure models. The use of a sealed 20 EPRI No Changes nt Pressure compartment is currently outside the scope of the current test Measureme If the proposed test is included, the test plan should state the purpose plan and will be evaluated further based on the results of the nt of the sealed compartment pressure monitoring as it relates to the internal pressure monitoring.

other objectives of Phase 2 HEAF testing.

Page 20, The NRC draft test plan does not include black cotton cloth targets as The NRC tests do not intend to replicate the IEEE standard.

Section recommended by IEEE Std. C37.20-2007, Clause 5.4 Indicators (for The cloth targets are primarily used as indicators for PPE 7.8: Targets observing the effects of thermal gases) as a comparison. concerns such as protective clothing. While comparisons may be able to be made very little information as to the ZOI will be It is recommended to include black cotton cloth targets as able to be gleaned from the IEEE cloth targets.

21 EPRI No Changes recommended by IEEE Std. C37.20-2007, Clause 5.4 Indicators (for observing the effects of thermal gases) for evaluation against IEEE Std. C37.20-2007 acceptance criteria. This provides an opportunity to observe the materials response to the more severe tests, while also providing an opportunity to directly compare to the control specimens subjected to the IEEE Std. guidelines.

Page 23, First paragraph and Figure 15: It is not clear how the cable samples Cable sample material and preparation will be fully Section are prepared. documented in the final test report. Candidate cable coupon 8.1: materials can be found in Table 3.1 and Table 3.2 of NUREG-22 EPRI No Changes Electrical The size, orientation, mass, cable jacket material, cable insulation 7197.

Cabinet material, and fire retardancy should be specified in the test plan.

Setup Page 25, The non-segregated bus bar gap should be defined. Electrical enclosures will be procured based on Figure 18: recommendations from the April 18 -19, 2018 NRC public Bus Duct Recommend specifying the bus bar gap dimension so that test results workshop and are intended to be representative of the current 23 EPRI No Changes Illustration - can be correlated to similar designs. NPP operating fleet. Electrical enclosure specifications will be Continuity shared with EPRI under the NRC MOU prior to testing and all Break parameters will be documented in the final report.

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

Title:

Equipment Phase 2

• CLEARLY STATED AS A MATTER OF FACT (OR A SPECIFIC QUESTION)

• COMPLETE AND INCLUDE A REFERENCE TO THE AFFECTED DOCUMENT Comments shall be:

• LEGIBLE AND REPRODUCIBLE

• FOCUSED TO A SPECIFIC PROBLEM OR DEFIENCY Document Change to

1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section Page 25, Mass (weight & dimension) of the copper and aluminum bus bars Pre and post test measurements are currently planned for this Section 9: should be captured prior to the experiments for post-test weight and test program to capture the weight and dimension of the bus Experiment dimension for accurately calculating the lost material due to oxidation. bar material.

s This will enable accurate oxidation calculation/assessments (e.g.,

Aluminum oxidation rate (30.9kJ/g of A2lO3).

Note: Even if the test cabinets are already assembled, bus bar 24 EPRI No Changes dimensions and weight could be obtained from the factory.

Note: Post-test should also subtract any separated material that was not oxidized (e.g., melted splatter, separated fragments, etc.).

Capture weight and dimension of the copper and aluminum bus bars pre and post-test to accurately calculate lost material due to oxidation.

Page 28: NUREG/SR-XXXX An International Phenomena Identification and An International Phenomena Identification and Ranking Table References Ranking Table (PIRT) Expert Elicitation Exercise for High Energy Arc (PIRT) Expert Elicitation Exercise for High Energy Arcing Faults (HEAFs) DRAFT has not been published. Faults (HEAFs) (NUREG-2218) was published in January 25 EPRI No Changes 2018 and can be found at https://www.nrc.gov/reading-Due to its importance in the creation of the HEAF Phase 2 test plan, it rm/doc-collections/nuregs/staff/sr2218/index.html should be published as soon as practical.

General Draft test plan does not provide the detail if any current transformers Any CT's within the test enclosure will be shorted on the Comment (CT) will be included as part of the electrical cabinets undergoing secondary or removed.

testing. Open circuit of CTs are problematic.

26 EPRI No Changes If any current transformers (CT) are included in the mock test equipment, there should a requirement to short the CT secondary if they are in the primary current path.

General Draft test plan does not specify recording ambient temperature prior to All relevant ambient conditions will be monitored and reported Comment test. in the Phase II test series including but not limited to ambient 27 EPRI No Changes temperature, humidity, and pressure.

Consider recording ambient temperature prior to test.

General Items of concern-The first was inclusion of the Shearon Harris This test program does not plan to specifically look at testing Comment isophase event in the justification for the study. The concern is that the iso-phase HEAF events. However, operating experience event did not involve a phase-to-phase fault (both phases that failed, shows that HEAF events in iso-phase systems are credible failed to ground). While probably not the authors intent, associating events.

28 EPRI isophase (a non-safety related system) with a regulatory issue may NUREG/CR-6850 Supplement 1 documents information cause concern on a licensee or outside observer that this design is including frequency, zone of influence and guidance subject to HEAFs. This is not the case as the isophase design and that concerning iso-phase bus ducts.

of the connecting components and relaying scheme preclude this from

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

Title:

Equipment Phase 2

• CLEARLY STATED AS A MATTER OF FACT (OR A SPECIFIC QUESTION)

• COMPLETE AND INCLUDE A REFERENCE TO THE AFFECTED DOCUMENT Comments shall be:

• LEGIBLE AND REPRODUCIBLE

• FOCUSED TO A SPECIFIC PROBLEM OR DEFIENCY Document Change to

1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section such an event. Additionally, the isophase bus, in my experience, is not While many iso-phase systems are located in locations which located in an area that a failure would impact any safety-related would not impact safety-related equipment that is not equipment and thus should not be considered as being able to prevent universally true and should be considered as part of the PRA.

a safety function to be fulfilled.

General items of concern- The second area of concern is that three-phase The KEMA power delivery system includes configurable Comment bolted bus faults that were performed in Phase 1 and planned for impedances. While this may not represent all individual plant Phase 2 do not appear to take in to account the impedance of the designs this information will be documented in the test report.

connected loads at the source or the termination. The energy of a zero This item was discussed in the April 18th-19th public workshop impedance fault that is a concern would be limited by the to deliver representative system currents, voltages and 29 EPRI configurations impedance and is not really representative of actual durations.

plant conditions. My suggestion is that a reasonable impedance should be estimated and included in the test configuration to properly quantify the energy created by the experiment.

Comment Since bus bar spacing is dependent on the gear that is available for For the large scale test program all bus bar spacing Generated testing, and can vary from what is installed at nuclear plants in the measurements, weights, and initial cabinet design from Small US, when the test results and PRA frequencies are documented the specifications will be fully documented and reported in the Scale deviation in bus bar spacing with respect to those in IEEE 1584 and in test results. The cabinet procurement will be discussed with Testing the industry should be documented and evaluated. EPRI prior to full scale testing with the goal of being 1 NEI No Changes representative of equipment represented in NPPs.

FRN SAND2018-0706 O, DRAFT 0002 Comment The plan states that the test setup will be in an enclosure. Several Comment resolved in small-scale comment resolution.

Generated figures depict the dimensions. If these figures are accurate, the from Small enclosure is snugged up to the bus bar and will reflect the blast back Scale on the bus bar, effectively doubling it.

Testing 2 NEI No Changes FRN SAND2018-0706 O, DRAFT 0002

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

Title:

Equipment Phase 2

• CLEARLY STATED AS A MATTER OF FACT (OR A SPECIFIC QUESTION)

• COMPLETE AND INCLUDE A REFERENCE TO THE AFFECTED DOCUMENT Comments shall be:

• LEGIBLE AND REPRODUCIBLE

• FOCUSED TO A SPECIFIC PROBLEM OR DEFIENCY Document Change to

1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section Comment No artificial enclosures should be used on end of buses. If the bus Per the discussions during the April workshop, the bus ducts Generated does not terminate in a cabinet, then do not cap the ends. The buses will be terminated into a cabinet or follow a configuration at the plants are generally long runs with no blanked off ends. similar to recent industry bus duct testing.

from Small Scale Testing 3 NEI No Changes FRN SAND2018-0706 O, DRAFT 0002 Addition of Comment The fault current profile utilized for testing at MV should resemble For the large scale test program a decrement curve (to be decrement Generated a typical generator behavior (ie. decrement curve). Typically MV provided by EPRI) will be evaluated for future tests.

gears have grounding transformers or grounding resistors on the curve for from Small neutral. This limits the phase to ground fault current to lower medium voltage Scale levels. Since NRC is performing phase to phase testing and the tests will be Testing ground resistors only limit the phase to ground current, the considered for FRN testing procedure is not impacted by the presence of the ground 4 NEI future addition SAND2018- resistor. However, presence of these phase-to-ground current to the test plan 0706 O, limiting devices should be used to lower the probability of an (pending DRAFT arcing event at the MV voltage level information 0002 provided by EPRI)

Comment Consider matching the location of the instrument racks being used to For the large scale test program the material coupons to be Generated monitor the HEAF to match the existing ZOIs that were used in 6850 used consist of aerogel, carbon tape and cable samples.

from Small and FAQ 35. The material coupons on the instrument rack should There is no current plan to have or evaluate the material Scale include both steel and aluminum. properties of steel or aluminum subjected to HEAF energy Testing on the instrumentation stands. It is unclear from the 5 NEI No Changes comment what the intended purpose and outcome of such FRN SAND2018- proposed effort. Rack location will be approximately in 3-foot 0706 O, increments extending from the side of the enclosure.

DRAFT 0002

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

Title:

Equipment Phase 2

• CLEARLY STATED AS A MATTER OF FACT (OR A SPECIFIC QUESTION)

• COMPLETE AND INCLUDE A REFERENCE TO THE AFFECTED DOCUMENT Comments shall be:

• LEGIBLE AND REPRODUCIBLE

• FOCUSED TO A SPECIFIC PROBLEM OR DEFIENCY Document Change to

1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section Comment Regarding the tests exceeding equipment ratings, it seems the The proposed arcing duration for the large scale test Generated duration of fault currents would exceed the equipment ratings. program does not intend to demonstrate equipment Provide more specifics for this statement and the ratings discussed. ratings. The durations were selected based on operating from Small Change to experience. The April 2018 workshop led to a test plan Scale change to reduce the number of low voltage tests to be Section 4.1 -

Testing performed at 8 seconds.

6 NEI equipment FRN ratings not to be SAND2018-exceeded 0706 O, DRAFT 0002 Comment Provide specifics on the type of cables that will be tested, i.e., Candidate cable coupon materials can be found in Table 3.1 Generated thermoset, thermoplastic, IEEE 383 or not, etc. Alternatively, include and Table 3.2 of NUREG-7197 and will be fully documented in the test plan the requirement to document the relevant properties of in the test report.

from Small the cable(s) that were tested.

Scale Testing 7 NEI No Changes FRN SAND2018-0706 O, DRAFT 0002 Comment In the overall general context of HEAF, prior industry experience has Based on operating experience three the testing will be Generated indicated that single phase arcing faults are much mote difficult to performed by initiating a three phase arcing fault per IEEE from Small sustain than three-phase arcing faults. Experimental results in this area Std. C37.20-2007. Threshold values and arc fault progression Scale have indicated that arcing line to ground faults are characterized as a are not feasible with the current scope and number of tests.

Testing discontinuous sinusoidal waveform. Additionally, these tests have The goal of the test program is to evaluate the damage FRN confirmed that single-phase arcing faults pass through a current zero phenomena associated with the longer duration HEAF events Beaver SAND2018- twice a cycle during which time they produce no ionized arc plasma, which show progression to three phase faults.

0706 O, which is required to maintain the arc current flowing. Comparatively, Valley DRAFT three-phase arcing faults, produce a constant source of arc plasma that 1 Nuclear No Changes 0002 can more easily maintain the arcing fault. However, evolving faults Power have been shown to manifest themselves originally as single-phase Station faults which subsequently . develop into multiple-phase faults. Based upon known evidence of fault evolution that involves different combinations of faulted phases, it is proposed that test sequence objectives be reviewed in the context of ultimately applying the results, or findings, to help identify what steps the industry should pursue that would improve methods to limit the energy of the postulated HEAF at its origination.

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

Title:

Equipment Phase 2

• CLEARLY STATED AS A MATTER OF FACT (OR A SPECIFIC QUESTION)

• COMPLETE AND INCLUDE A REFERENCE TO THE AFFECTED DOCUMENT Comments shall be:

• LEGIBLE AND REPRODUCIBLE

• FOCUSED TO A SPECIFIC PROBLEM OR DEFIENCY Document Change to

1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section Comment Another dynamic that is an extremely important aspect of HEAF Magnetic field monitoring instrumentation is a current area of Generated involves magnetic forces created by induced currents. These magnetic additional instrumentation being evaluated with the potential from Small forces have been demonstrated to have impelled wires upstream of the of addition into the test plan.

Scale HEAF with enough force to damage insulation or tear the conductors Testing from their terminations, creating additional short circuits. This sequence FRN has been SAND2018- proven by means of stage fault testing in the industry which utilized 0706 O, high-speed film recording *technologies* that captured the progression.

Beaver Therefore, a correlation is desired to be quantified based on, HEAF Additional DRAFT Valley 0002 experimentation objectives with respect to these magnetic forces and Instrumentation 2 Nuclear resultant ejected particle emission and physical movement. The Zone being Power Of influence implications involving induced current magnetics is sought considered Station to be more formally addressed by means of HEAF test experimentation, which would capture and record these magnetic field forces (magnitudes and direction over time) with additional monitoring of consequential multiple short circuit events as a likely or credible manifestation, throughout the conduct of the testing. It is proposed that magnetic field monitoring instrumentation would thereby enable a more precise identification of specific switchgear design attributes that can be enhanced to address subsequent fault occurrences due to an originating HEAF.

Comment Historically there has been considerable experimental verification of Insulation material impacts towards the relationships between Generated only a minimal rise in conductor temperature with respect to HEAFs voltage level, insulation type, and construction where bus from Small involving bare copper bus as correlated with the monitored arc travel insulation may help extinguish or sustain an arc once Scale rate. Moreover, with regards to prior insulated bus testing, the voltage established is not in the current scope of testing. The KEMA Testing gradients are well within the dielectric withstand capability of the bus's facility pre establishes a duration for the purpose of testing.

FRN insulation system. It is desired that HEAF experimentations be Investigation of extinguishment factors is not currently Beaver SAND2018- designed that would deliver results to the industry that more precisely feasible within the test matrix.

0706 O, characterizes the performance insofar as the manner in which Valley DRAFT insulated bus structures extinguish the arc and therefore possibly 3 Nuclear No Changes 0002 minimize damage. That is, in the design of the HEAF test Power experimentation, it is desired that results afford more specific Station determination of the relationships between voltage level, insulation type, and construction where bus insulation may help extinguish or sustain an arc once established. At present, as applied specifically to the scenario of an arc "blast," (nomenclature borrowed from page 2 of SAND2018-0706 0) versus an arching "fault," there is an opportunity to expand present-day industry knowledge and understanding as to the degree that existing insulated bus in the 600- Volt class of equipment

REVIEW / COMMENT DOCUMENTATION High Energy Arcing Faults (HEAFs) in Electrical Document # Rev: NRC-2017-0168 Date: 6/18/2018

Title:

Equipment Phase 2

• CLEARLY STATED AS A MATTER OF FACT (OR A SPECIFIC QUESTION)

• COMPLETE AND INCLUDE A REFERENCE TO THE AFFECTED DOCUMENT Comments shall be:

• LEGIBLE AND REPRODUCIBLE

• FOCUSED TO A SPECIFIC PROBLEM OR DEFIENCY Document Change to

1. Commenter Document Number/ Review Comments (Print)/Basis for Comment Comment Disposition / Resolution Section appears to provide significant safety advantages over non-insulated bus.

Comment A more detailed elaboration or description of specific individual key test The current test plan was developed to highlight the Generated plan parameters should be itemized in the test plan in an organized parameters of interest based upon previous testing insights from Small format. Information is desired as to the HEAF parameter significance to as well as information obtained during the International Scale be addressed as part of the overall test plan. For each HEAF Phenomena Identification and Ranking Table (PIRT) Expert Testing parameter categorized in terms of its significance, there should be Elicitation Exercise for High Energy Arcing Faults (HEAFs)

FRN established the documented test plan steps to address each of the (NUREG-2218). Section 8.1 reflects the testing orientation to SAND2018- individual HEAF parameters. Such an identified HEAF parameter- address the parameters of interest. Further explanation and 0706 O, specific significance or ranking would focus more directly upon the an evaluation of the test results will be documented in multiple DRAFT importance of the correlation between each of the separate test follow-on NUREG publications to analyze the data obtained Beaver 0002 parameters (i.e., measured quantities, monitored components, etc.) and implement new method development.

with respect to the overall stated objective of the test plan. Along with Valley this, and in association with each of the parameters identified by 4 Nuclear No Changes significance, a summary of test plan steps designed to address each of Power the parameters individually would then establish the effectiveness of Station how thorough the test configurations and actions would be in contributing to support the final test plan results or findings.

Therefore, .supplementary HEAF test plan information and data would be broken down in an itemized format addressing stated test objectives in terms of the specific HEAF test parameter identification, and in association with this, the HEAF test parameter significr;1nce (or ranking in terms of its importance). Further insight would then be advantageous if test sequences are correlated and then summarized for each of the identified and ranked HEAF test parameters.