Text

NFPA 805 Transition Pilot Plant FAQ Process: Substantive E-Mails; April 2007
	ML071630428
Person / Time
Site:	Nuclear Energy Institute
Issue date:	04/03/2007
From:	Charles Moulton; NRC/NRR/ADRA/DRA/AFPB, Nuclear Energy Institute
To:	Jamar B; Nuclear Energy Institute
References
	Download: ML071630428 (101)
	v • d • e

Brandon, Attached is an advance e-copy of draft comments on FAQ 8 rev 3. This document will be a handout for the 4/26 public meeting. Please distribute it to the task force/writing group. This document is a summary of the comments Dan talked to you about last week.

Chuck Charles Moulton Fire Protection Engineer NRR/DRA/AFPB Phone: 415-2751 Mailstop: O11A11

Mail Envelope Properties (46125258.482 : 12 : 9706)

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NRC comments on FAQ 8 revision 3 Creation Date 4/3/2007 9:10:48 AM From: Charles Moulton Created By: CEM4@nrc.gov Recipients Action Date & Time nei.org Transferred 4/3/2007 9:10:53 AM btj (internet:btj@nei.org) nrc.gov OWGWPO02.HQGWDO01 Delivered 4/3/2007 9:10:50 AM DXF1 CC (Daniel Frumkin) Opened 4/5/2007 8:54:40 AM nrc.gov TWGWPO01.HQGWDO01 Delivered 4/3/2007 9:10:48 AM PWL CC (Paul Lain) Opened 4/17/2007 5:07:44 PM nrc.gov TWGWPO04.HQGWDO01 Delivered 4/3/2007 9:10:50 AM SDW1 CC (Sunil Weerakkody)

Post Office Delivered Route nei.org OWGWPO02.HQGWDO01 4/3/2007 9:10:50 AM nrc.gov TWGWPO01.HQGWDO01 4/3/2007 9:10:48 AM nrc.gov TWGWPO04.HQGWDO01 4/3/2007 9:10:50 AM nrc.gov Files Size Date & Time MESSAGE 962 4/3/2007 9:10:48 AM AFPB staff comments on FAQ 06-0008 Rev 3.pdf 53921 4/3/2007 9:03:36 AM Options Auto Delete: No Expiration Date: None Notify Recipients: Yes Priority: Standard

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Subject:

No Security: Standard To Be Delivered: Immediate Status Tracking: Delivered & Opened NRC Response to FAQ 06-0008, Revision 3 [DXF] {4/2/2007}

Dans comments on Rev 3:

Break down section 3.8 (similar to the way they itemized 3.11), since my reading of the chapter 4 exclusion to section 3.8 only applies to 3.8.2. I believe that the other sections of 3.8 fall under the NFPA code exclusion.

3.11.1 is not subject to the Chapter 4 exclusion.

In the table on page 6, it states at the top of the first column 50.48(c) requirement, this should be 50.48(c).2.vii requirement.

In the 1.205 table (on page 7), the statement, "once the process is added . . ." may be problematic. I don't see this as a show stopper, but the NRC staff needs to look into the implications of this not being complete. There is a cart before the horse issue here; which comes first: the RIS or the updated 04-02/RG 1.205? My thought is that we need to have the process attached to the FAQ so we can say that it is okay in the RIS. Process wise, you may not be able to have open ended statements in this type of document.

o Suggestion: I think the answer to this question on 1.205 is that an alternative method will not be used. c.2.vii does not require an alternative method. So the open ended statement could be replaced with a statement like, "an alternative method is not proposed, the existing performance-based methods will be applied, but will be applied in a very limited fashion to (nfpa codes and listings)." Do you think that this will fly?

The added tables were looked at pretty closely during an older revision, so assuming nothing has changed there, they should be okay.

Thanks you for capturing these comments. We will address these immediately.

Brandon

Original Message-----

From: Charles Moulton [1]

Sent: Tuesday, April 03, 2007 9:11 AM To: JAMAR, Brandon Cc: Daniel Frumkin; Paul Lain; Sunil Weerakkody

Subject:

NRC comments on FAQ 8 revision 3

Brandon, Attached is an advance e-copy of draft comments on FAQ 8 rev 3. This document will be a handout for the 4/26 public meeting. Please distribute it to the task force/writing group. This document is a summary of the comments Dan talked to you about last week.

Chuck Charles Moulton Fire Protection Engineer NRR/DRA/AFPB Phone: 415-2751 Mailstop: O11A11 This electronic message transmission contains information from the Nuclear Energy Institute, Inc. The information is intended solely for the use of the addressee and its use by any other person is not authorized. If you are not the intended recipient, you have received this communication in error, and any review, use, disclosure, copying or distribution of the contents of this communication is strictly prohibited. If you have received this electronic transmission in error, please notify the sender immediately by telephone or by electronic mail and permanently delete the original message.

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RE: NRC comments on FAQ 8 revision 3 Creation Date 4/3/2007 9:21:01 AM From: "JAMAR, Brandon" <btj@nei.org>

Created By: btj@nei.org Recipients nrc.gov TWGWPO01.HQGWDO01 CEM4 (Charles Moulton)

PWL CC (Paul Lain) nrc.gov OWGWPO02.HQGWDO01 DXF1 CC (Daniel Frumkin) nrc.gov TWGWPO04.HQGWDO01 SDW1 CC (Sunil Weerakkody)

Post Office Route TWGWPO01.HQGWDO01 nrc.gov OWGWPO02.HQGWDO01 nrc.gov TWGWPO04.HQGWDO01 nrc.gov Files Size Date & Time MESSAGE 1277 4/3/2007 9:21:01 AM Mime.822 3610 Options Expiration Date: None Priority: Standard ReplyRequested: No Return Notification: None Concealed

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Junk Mail handling disabled by Administrator Junk List is not enabled Junk Mail using personal address books is not enabled Block List is not enabled

Brandon, Do you have an update on the status of FAQs 16 and 18?

We are still awaiting the final revision of these two. The writing team requested that we hold off closure until we recieved the final revisions, which would fully resolve the AFPB Staff's comments. Sunil is most interested in ensuring that our resolutions are final so they can be included in the RIS.

We expected to have the new revisions by now. Unfortunately, if we can't get the new revisions prior to the telecon, the schedule will force us to go with the closure memos as they exist.

Thanks, Chuck Charles Moulton Fire Protection Engineer NRR/DRA/AFPB Phone: 415-2751 Mailstop: O11A11

Mail Envelope Properties (461CD8C4.1A9 : 12 : 9706)

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Status of FAQs 16 and 18 Creation Date 4/11/2007 8:47:00 AM From: Charles Moulton Created By: CEM4@nrc.gov Recipients Action Date & Time nei.org Transferred 4/11/2007 8:47:31 AM btj (internet:btj@nei.org) nrc.gov OWGWPO02.HQGWDO01 Delivered 4/11/2007 8:47:07 AM NXI CC (Naeem IQBAL) Opened 4/11/2007 8:53:11 AM RHG CC (Ray Gallucci) Opened 4/11/2007 8:47:13 AM nrc.gov TWGWPO01.HQGWDO01 Delivered 4/11/2007 8:47:00 AM CEM4 BC (Charles Moulton) Opened 4/11/2007 8:47:10 AM nrc.gov TWGWPO04.HQGWDO01 Delivered 4/11/2007 8:47:07 AM SDW1 CC (Sunil Weerakkody) Opened 4/11/2007 11:02:32 AM Post Office Delivered Route nei.org OWGWPO02.HQGWDO01 4/11/2007 8:47:07 AM nrc.gov TWGWPO01.HQGWDO01 4/11/2007 8:47:00 AM nrc.gov TWGWPO04.HQGWDO01 4/11/2007 8:47:07 AM nrc.gov Files Size Date & Time MESSAGE 1434 4/11/2007 8:47:00 AM Options

Auto Delete: No Expiration Date: None Notify Recipients: Yes Priority: Standard ReplyRequested: No Return Notification: None Concealed

Subject:

No Security: Standard To Be Delivered: Immediate Status Tracking: Delivered & Opened

Please find revision 1 to FAQs 06-0016 & 06-0018 which are attached for submittal. Two versions of each are provided. One shows changes and one shows changes accepted.

If you have any questions regarding this transmittal please give me a call.

Thank you, Brandon T. Jamar Project Manager, Engineering Nuclear Energy Institute 1776 I Street NW, Suite 400 Washington, DC 20006

<http://www.nei.org> www.nei.org P: 202-739-8043 F: 202-533-0185 E: btj@nei.org nuclear. clean air energy.

This electronic message transmission contains information from the Nuclear Energy Institute, Inc. The information is intended solely for the use of the addressee and its use by any other person is not authorized. If you are not the intended recipient, you have received this communication in error, and any review, use, disclosure, copying or distribution of the contents of this communication is strictly prohibited. If you have received this electronic transmission in error, please notify the sender immediately by telephone or by electronic mail and permanently delete the original message.

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FAQ 06-0016, FAQ 06-0018 Rev. 1 Submittals Creation Date 4/11/2007 2:29:08 PM From: "JAMAR, Brandon" <btj@nei.org>

Created By: btj@nei.org Recipients nrc.gov TWGWPO01.HQGWDO01 CEM4 (Charles Moulton) nrc.gov TWGWPO04.HQGWDO01 SDW1 (Sunil Weerakkody)

Post Office Route TWGWPO01.HQGWDO01 nrc.gov TWGWPO04.HQGWDO01 nrc.gov Files Size Date & Time MESSAGE 1123 4/11/2007 2:29:08 PM TEXT.htm 6264 FAQ 06-0016 - Rev 1 changes shown.pdf 155835 FAQ 06-0016 - Rev 1.pdf 148334 FAQ 06-0018 Rev 1 changes shown.pdf 119620 FAQ 06-0018 Rev 1.pdf 115952 Mime.822 750258 Options Expiration Date: None Priority: Standard ReplyRequested: No Return Notification: None Concealed

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No Security: Standard Junk Mail Handling Evaluation Results Message is eligible for Junk Mail handling This message was not classified as Junk Mail Junk Mail settings when this message was delivered Junk Mail handling disabled by User Junk Mail handling disabled by Administrator

Junk List is not enabled Junk Mail using personal address books is not enabled Block List is not enabled Deleted: 0b FAQ Number 06-0016, Revision 1 Plant: Harris Nuclear Plant (HNP) FAQ # 06-0016 Submittal Date: 03-22-07 Deleted: 11-6-06 Licensee

Contact:

David Miskiewicz Tele/email 919-546-7588 NRC

Contact:

Tele/email Distribution: Check all that apply (NEI Internal Use)

FPWG RIRWG NSSS OG NFPA 805 TF

Subject:

Clarification/enhancement of Ignition Source counting guidance for Electrical Cabinets in NUREG/CR-6850, supporting NFPA-805 Fire PRA application.

Interpretation of guidance? Yes Proposed new guidance not in NEI 04-02? Yes Details:

NEI 04-02 Guidance needing interpretation (include section, paragraph number, and line number):

New attachment on interpretation issues Circumstances requiring guidance interpretation or new guidance:

The guidance provided in NUREG/CR-6850 for Task 6, Fire Ignition Frequency (Section 6.5.6, Bin 15), states:

Bin 15 - Electrical Cabinets (Plant-Wide Components): Electrical cabinets represent such items as switchgears, motor control centers, DC distribution panels, relay cabinets, control and switch panels (excluding panels that are part of machinery), fire protection panels, etc. Electrical cabinets in a nuclear power plant vary significantly in size, configuration, and voltage. Size variation range from small-wall mounted units to large walk-through vertical control cabinets, which can be 20 to 30 long. The configuration can vary based on number of components that contribute to ignition, such as relays and circuit cards, and combustible loading, which also affects the fire frequency. Voltages in electrical cabinets vary from low voltage (120 V) panels to 6.9 kV switchgears. Even though it is expected that these features affect the likelihood of fire ignition, from a simple analysis of the event data involving the electrical cabinets, it was determined that the variation by cabinet type did not warrant separate frequency evaluation. Therefore, one fire frequency was estimated for the electrical cabinets.

This guidance infers that cabinet size is not a factor for ignition source counting. However, additional guidance states that electrical cabinets should be counted by their vertical segments .... During the presentation of Pilot Project results it was determined that differences related to the definition of segments could result in notable inconsistency between individual users of NUREG/CR-6850.

1

Deleted: 0b FAQ Number 06-0016, Revision 1 The discussion of this issue found that this issue affects only general electrical cabinets and panels. In the case of switchgears, load centers, unit substations, and motor control centers the term segment was uniformly interpreted to be equal to the individual vertical sections that define these types of components. As applied to general electrical cabinets and panels, the term segments could be interpreted to mean different metrics.

A segment could be defined as an enclosed element that is generally independent of size or volume (also referred to as a vertical section).

A segment could be defined as an individual section of an enclosure regardless of whether it was fully enclosed.

A segment could be defined based on a standard or reference sample panel size.

Depending on the metric being used, the counting of electrical cabinets would result in varying results and consequently, different fire ignition frequency values. While NUREG/CR-6850 allows the establishment of plant specific criteria for counting of electrical cabinets, additional guidance is required to achieve a consistent basis for determining the ignition frequencies.

Detail contentious points if licensee and NRC have not reached agreement This topic has impact on the NFPA-805 pilots, non-pilots and other users of NUREG/CR-6850.

Potentially relevant existing FAQ numbers:

This guidance is specific to the characterization of electrical cabinets for Bin 15 ignition frequency determination. The characterization of switchgear and load center segments for the purposes of high energy arcing faults is addressed by FAQ 06-0017.

Response Section A generalized counting criterion for general electrical cabinets and panels is proposed. This proposed criterion would involve two elements.

For switchgears, load centers, unit substations, and motor control centers the counting for the purposes of NUREG/CR-6850, Task 6, Bin 15 would be based on vertical section. This counting is illustrated in the following examples.

2

Deleted: 0b FAQ Number 06-0016, Revision 1 Medium Voltage Switchgear 9 Breakers and Sections Count = 9 for Bin 15 Load Center or Unit Substation 16 Breakers in 4 Sections Count = 4 for Bin 15 Motor Control Center 41 Breakers/Starters in 9 Sections Count = 9 for Bin 15 For general electrical cabinets and panels, counting is based on externally apparent vertical sections. No examination of the internal construction is required.

Deleted: For general electrical cabinets and panels, it is proposed that the This proposed counting for electrical cabinets and panels is to be applied for a wide range of counting be based on a physically panel sizes. However, recognizing that the ignition frequency is more a function of the enclosed element. A physically enclosed element means that that the cabinet or cabinet contents than the cabinet size, a basis is needed to address outlier conditions. It is panel is fully enclosed by 6 solid proposed that each user be required to establish criteria for identifying the outliers and the elements with the provision that a non-combustible floor or ceiling may basis for counting them. As an example, they can be counted by establishing a nominal represent the bottom or top. The term standard or reference cabinet size. The count could also be based on evaluating the solid element is not intended to mean that the element is substantially cabinet internals relative to a defined standard or reference configuration. continuous. Consequently, breeches or unsealed penetrations could still be treated as solid. The term solid is For example, a particular user may define a cabinet with any horizontal dimension more intended to prevent a panel that is divided than 8 feet as an outlier, and a standard cabinet as being nominally 4 feet in length x 3 feet by an element that is substantially open from being treated as two separate panels.¶ deep. (cabinet height is not generally an issue based on the use of vertical sections). Using this example, the following cabinet and panel examples would be counted as follows:

3

Deleted: 0b FAQ Number 06-0016, Revision 1 6 ft Cabinet is not an outlier -

Count = 1 Cabinet is same as standard Count = 1 Externally, the cabinet appears to have 6 vertical sections. The construction of internal dividers is unknown or open.

Count = 6 Deleted: Internal dividers are not solid¶ Count = 1 Internal dividers are solid Count = 6 Three independent cabinets Count = 3 12 feet, 3 ft deep Panel is an outlier, using a 4 standard cabinet -

Count = 3 9 ft long , 6 ft deep Cabinet is an outlier, no evaluation of contents, based on reference cabinet Count = 3 - due to both variation from the standard length and width..

9 ft long , 6 ft deep Cabinet is an outlier, evaluation of Walk Through Cabinet contents shows small set of ignition sources typical of the standard Deleted: low cable loading cabinet -

Count = 1 4

Deleted: 0b FAQ Number 06-0016, Revision 1 The intent is that a basis for the counting of outliers is required. A volumetric comparison is not required. Also, to prevent any appearance that this treatment is intended to be based on physical measurements, the proposed approach allows only integer counting. The assignment of fractional values would not be allowed. In addition, the proposed methodology retains the option for screening small cabinets resulting in a count of zero for them (as discussed in NUREG/CR-6850). As applied in this case, the user would be allowed to screen cabinets or panels based on defined criteria and exclude them from the overall population count. When performing detailed fire modeling, the fire should be applied to the actual cabinet footprint by vertical section, including outliers.

Basis:

The existing guidance in NUREG/CR-6850 is based on industry data which has only been provided with fidelity adequate to support plant level ignition frequencies for electrical cabinets. Although the guidance does address the broad applicability of the data, it leaves room for variability that can create issues with PRA quality. It is important that the ignition frequency results be of sufficient quality to support not only NFPA-805 transition but also the more broad scope of regulatory inspection and enforcement issues.

The guidance proposed will provide more consistency when determining plant specific electrical cabinet ignition frequencies while working within the bounds of the exiting data provided by the NUREG. This should facilitate the review and acceptability of the results.

5 FAQ Number 06-0016, Revision 1 Plant: Harris Nuclear Plant (HNP) FAQ # 06-0016 Submittal Date: 03-22-07 Licensee

Contact:

David Miskiewicz Tele/email 919-546-7588 NRC

Contact:

Tele/email Distribution: Check all that apply (NEI Internal Use)

FPWG RIRWG NSSS OG NFPA 805 TF

Subject:

Clarification/enhancement of Ignition Source counting guidance for Electrical Cabinets in NUREG/CR-6850, supporting NFPA-805 Fire PRA application.

Interpretation of guidance? Yes Proposed new guidance not in NEI 04-02? Yes Details:

NEI 04-02 Guidance needing interpretation (include section, paragraph number, and line number):

New attachment on interpretation issues Circumstances requiring guidance interpretation or new guidance:

The guidance provided in NUREG/CR-6850 for Task 6, Fire Ignition Frequency (Section 6.5.6, Bin 15), states:

Bin 15 - Electrical Cabinets (Plant-Wide Components): Electrical cabinets represent such items as switchgears, motor control centers, DC distribution panels, relay cabinets, control and switch panels (excluding panels that are part of machinery), fire protection panels, etc. Electrical cabinets in a nuclear power plant vary significantly in size, configuration, and voltage. Size variation range from small-wall mounted units to large walk-through vertical control cabinets, which can be 20 to 30 long. The configuration can vary based on number of components that contribute to ignition, such as relays and circuit cards, and combustible loading, which also affects the fire frequency. Voltages in electrical cabinets vary from low voltage (120 V) panels to 6.9 kV switchgears. Even though it is expected that these features affect the likelihood of fire ignition, from a simple analysis of the event data involving the electrical cabinets, it was determined that the variation by cabinet type did not warrant separate frequency evaluation. Therefore, one fire frequency was estimated for the electrical cabinets.

This guidance infers that cabinet size is not a factor for ignition source counting. However, additional guidance states that electrical cabinets should be counted by their vertical segments .... During the presentation of Pilot Project results it was determined that differences related to the definition of segments could result in notable inconsistency between individual users of NUREG/CR-6850.

1

FAQ Number 06-0016, Revision 1 The discussion of this issue found that this issue affects only general electrical cabinets and panels. In the case of switchgears, load centers, unit substations, and motor control centers the term segment was uniformly interpreted to be equal to the individual vertical sections that define these types of components. As applied to general electrical cabinets and panels, the term segments could be interpreted to mean different metrics.

A segment could be defined as an enclosed element that is generally independent of size or volume (also referred to as a vertical section).

A segment could be defined as an individual section of an enclosure regardless of whether it was fully enclosed.

A segment could be defined based on a standard or reference sample panel size.

Depending on the metric being used, the counting of electrical cabinets would result in varying results and consequently, different fire ignition frequency values. While NUREG/CR-6850 allows the establishment of plant specific criteria for counting of electrical cabinets, additional guidance is required to achieve a consistent basis for determining the ignition frequencies.

Detail contentious points if licensee and NRC have not reached agreement This topic has impact on the NFPA-805 pilots, non-pilots and other users of NUREG/CR-6850.

Potentially relevant existing FAQ numbers:

This guidance is specific to the characterization of electrical cabinets for Bin 15 ignition frequency determination. The characterization of switchgear and load center segments for the purposes of high energy arcing faults is addressed by FAQ 06-0017.

Response Section A generalized counting criterion for general electrical cabinets and panels is proposed. This proposed criterion would involve two elements.

For switchgears, load centers, unit substations, and motor control centers the counting for the purposes of NUREG/CR-6850, Task 6, Bin 15 would be based on vertical section. This counting is illustrated in the following examples.

2

FAQ Number 06-0016, Revision 1 Medium Voltage Switchgear 9 Breakers and Sections Count = 9 for Bin 15 Load Center or Unit Substation 16 Breakers in 4 Sections Count = 4 for Bin 15 Motor Control Center 41 Breakers/Starters in 9 Sections Count = 9 for Bin 15 For general electrical cabinets and panels, counting is based on externally apparent vertical sections. No examination of the internal construction is required.

This proposed counting for electrical cabinets and panels is to be applied for a wide range of panel sizes. However, recognizing that the ignition frequency is more a function of the cabinet contents than the cabinet size, a basis is needed to address outlier conditions. It is proposed that each user be required to establish criteria for identifying the outliers and the basis for counting them. As an example, they can be counted by establishing a nominal standard or reference cabinet size. The count could also be based on evaluating the cabinet internals relative to a defined standard or reference configuration.

For example, a particular user may define a cabinet with any horizontal dimension more than 8 feet as an outlier, and a standard cabinet as being nominally 4 feet in length x 3 feet deep. (cabinet height is not generally an issue based on the use of vertical sections). Using this example, the following cabinet and panel examples would be counted as follows:

3

FAQ Number 06-0016, Revision 1 6 ft Cabinet is not an outlier -

Count = 1 Cabinet is same as standard Count = 1 Externally, the cabinet appears to have 6 vertical sections. The construction of internal dividers is unknown or open.

Count = 6 Internal dividers are solid Count = 6 Three independent cabinets Count = 3 12 feet, 3 ft deep Panel is an outlier, using a 4 standard cabinet -

Count = 3 9 ft long , 6 ft deep Cabinet is an outlier, no evaluation of contents, based on reference cabinet Count = 3 - due to both variation from the standard length and width..

9 ft long , 6 ft deep Cabinet is an outlier, evaluation of Walk Through Cabinet contents shows small set of ignition sources typical of the standard cabinet -

Count = 1 4

FAQ Number 06-0016, Revision 1 The intent is that a basis for the counting of outliers is required. A volumetric comparison is not required. Also, to prevent any appearance that this treatment is intended to be based on physical measurements, the proposed approach allows only integer counting. The assignment of fractional values would not be allowed. In addition, the proposed methodology retains the option for screening small cabinets resulting in a count of zero for them (as discussed in NUREG/CR-6850). As applied in this case, the user would be allowed to screen cabinets or panels based on defined criteria and exclude them from the overall population count. When performing detailed fire modeling, the fire should be applied to the actual cabinet footprint by vertical section, including outliers.

Basis:

The existing guidance in NUREG/CR-6850 is based on industry data which has only been provided with fidelity adequate to support plant level ignition frequencies for electrical cabinets. Although the guidance does address the broad applicability of the data, it leaves room for variability that can create issues with PRA quality. It is important that the ignition frequency results be of sufficient quality to support not only NFPA-805 transition but also the more broad scope of regulatory inspection and enforcement issues.

The guidance proposed will provide more consistency when determining plant specific electrical cabinet ignition frequencies while working within the bounds of the exiting data provided by the NUREG. This should facilitate the review and acceptability of the results.

5 Deleted: 0b FAQ Number 06-0018, Revision 1 Plant: Harris Nuclear Plant (HNP) FAQ # 06-0018 Submittal Date: 3-22-07 Deleted: 11-6-06 Licensee

Contact:

David Miskiewicz Tele/email 919-546-7588 NRC

Contact:

Tele/email Distribution: Check all that apply (NEI Internal Use) 1

FPWG RIRWG NSSS OG NFPA 805 TF

Subject:

Clarification/enhancement of Ignition Source counting guidance for Main Control Board (MCB) in NUREG/CR-6850, supporting NFPA-805 Fire PRA application.

Interpretation of guidance? Yes Proposed new guidance not in NEI 04-02? Yes Details:

NEI 04-02 Guidance needing interpretation (include section, paragraph number, and line number):

New attachment on interpretation issues Circumstances requiring guidance interpretation or new guidance:

NUREG/CR-6850, Section 6.5.6 The guidance provided in NUREG/CR-6850 for Task 6, Fire Ignition Frequency, is subject to application inconsistency in the treatment of Main Control Board (Bin 4). The guidance for Task 6 does not provide any specific definition or characterization of what constitutes a Main Control Board (MCB) other than a reference to it being the central element of the room. A discussion amongst the Pilot Plants that included consideration of other plants in their respective fleets found wide variability in the configuration of the main control room. There was a concern that inconsistent treatment of this bin would unnecessarily challenge the completion and review of the Fire PRA. This challenge would be manifested by a notable change in the fire frequency assigned to an individual panel depending on whether it was counted as Bin 4 or Bin 15.

Further review of NUREG/CR-6850 found that a definition of MCB is provided in Appendix L.

However, this Appendix develops a fire modeling treatment of fire behavior within a panel enclosure. There was a concern that absent documented agreement, there could be a future challenge to the use of the definition in Appendix L for the purposes of Task 6, Bin 4 counting.

Detail contentious points if licensee and NRC have not reached agreement This topic has impact on the NFPA-805 pilots, non-pilots and other users of NUREG/CR-6850.

Deleted: 0b FAQ Number 06-0018, Revision 1 Potentially relevant existing FAQ numbers:

This guidance is specific to the characterization of Main Control Board for Bin 4 determination.

The characterization and counting of electrical cabinets for Bin 15 determination is addressed by FAQ 06-0016.

Response Section It is proposed that the definition of Main Control Board provided in NUREG/CR-6850, Appendix L be accepted as also being applicable for Task 6, Bin 4 counting. Any panel that is detached from the main horseshoe would generally be excluded from this definition of the main control board with few exceptions.

Basis:

The guidance proposed will provide more consistency when determining plant specific control room ignition frequencies while working within the bounds of the exiting data provided by the NUREG. This should facilitate the review and acceptability of the results.

3 FAQ Number 06-0018, Revision 1 Plant: Harris Nuclear Plant (HNP) FAQ # 06-0018 Submittal Date: 3-22-07 Licensee