ML13353A578

Request for Additional Information on License Amendment Request to Adopt National Fire Protection Association Standard 805 Performance-Based Standard for Fire Protection

ML13353A578
Person / Time
Site:	Saint Lucie
Issue date:	12/26/2013
From:	Audrey Klett Plant Licensing Branch II
To:	Nazar M Florida Power & Light Co
Klett A
References
TAC MF1373, TAC MF1374
Download: ML13353A578 (32)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 Mr. Mano Nazar Executive Vice President and Chief Nuclear Officer Florida Power and Light Company P. 0. Box 14000 700 Universe Boulevard Juno Beach, FL 33408-0420 December 26, 2013

SUBJECT:

ST. LUCIE PLANT UNITS 1 AND 2 REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST TO ADOPT NATIONAL FIRE PROTECTION ASSOCIATION STANDARD 805 PERFORMANCE-BASED STANDARD FOR FIRE PROTECTION (TAC NOS. MF1373 AND MF1374)

Dear Mr. Nazar:

By letter dated March 22, 2013 (Agencywide Documents and Management System (ADAMS)

Accession No. ML13088A173), as supplemented by letter dated June 14, 2013 (ADAMS Accession No. ML13170A156), Florida Power & Light Company (the licensee) submitted a license amendment request (LAR) for the St. Lucie Plant Unit Nos 1 and 2. The proposed amendment requested approval to transition the fire protection licensing basis from Title 1 0 of the Code of Federal Regulations (10 CFR), Section 50.48(b) to 10 CFR 50.48(c), National Fire Protection Association Standard 805 (NFPA 805), "Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants."

The U.S. Nuclear Regulatory Commission (NRC or the Commission) staff has reviewed the information provided by the licensee, participated in an audit at St. Lucie from November 18 - 22, 2013, and determined that it needs additional information to complete the review. The enclosed requests for additional information (RAis) are listed in the following categories.

Fire Protection Engineering (FPE)

Safe Shutdown Analysis (SSA)

Programmatic (PROG)

Fire Modeling (FM)

Radioactive Release (RR)

Probabilistic Risk Assessment (PRA)

As previously discussed with Mr. Bill Cross of the licensee's staff, the NRC is requesting responses to the RAI by the following dates (listed in days from the date of this request):

RAI Number RAI Response Due Date FPE RAI 01 -11 60 days SSA RAI 01 -14 60 days PROG RAI 01 - 02 60 days FM RAI 02,05 60 days FM RAI 03 90 days FM RAI 01, 04,06 120 days RR RAI 01 90 days PRA RAI 04, 07, 10, 12, 13, 14, 15 60 days PRA RAI 02, 03, 05, 06, 11, 16, 17 90 days PRA RAI 01, 08, 09 120 days If you have any questions, please contact me at (301) 415-0489.

Enclosure:

Request for Additional Information Docket Nos. 50-335 and 50-389 cc: Distribution via Listserv Sincerely, Audrey l. Klett, Project Manager Plant Licensing Branch 11-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

FPE RAI 01 REQUEST FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST TO ADOPT NATIONAL FIRE PROTECTION ASSOCIATION STANDARD 805 PERFORMANCE-BASED STANDARD FOR FIRE PROTECTION FOR LIGHT-WATER REACTOR GENERATING PLANTS FLORIDA POWER AND LIGHT COMPANY ST. LUCIE PLANT UNITS 1 AND 2 DOCKET NOS. 50-335 AND 50-389 Attachment A of the license amendment request (LAR) (Agencywide Documents Access and Management System ADAMS) Accession No. ML13088A173), Section 3.2.3(1), "Procedures,"

refers to LAR Attachment L for approval to establish a methodology using Electric Power Research Institute (EPRI) Technical Report No. TR1006756, "Fire Protection Equipment Surveillance Optimization and Maintenance Guide," for surveillance optimization. LAR Attachment L, Approval Request #1 describes a proposal for alternate compliance utilizing Title 10 of the Code of Federal Regulations (1 0 CFR), Section 50.48(c)(2)(vii). However, there is also a reference to using Nuclear Electric Insurance Limited (NEIL) frequency optimization for surveillance procedures as well as the EPRI Technical Report. Describe how these programs will be applied simultaneously. Provide a detailed explanation of the areas of overlap, and independence for the two methods.

FPE RAI 02 Section 3,3.1.2(6) of National Fire Protection Association (NFPA) Standard 805 (NFPA 805) requires the storage and use of flammable gases to be "in accordance with applicable NFPA standards." However, LAR Attachment A, Section 3.3.1.2(6) indicates compliance with something other than NFPA standards. Describe the requirements used and provide justification for their use in lieu of NFPA standards.

FPE RAI 03 LAR Attachment A, Section 3.3.1.3.1, "Control of Ignition Sources," identifies both "complies via Engineering Evaluation" and "Complies" as the compliance statement. Provide a description to clarify the difference, and describe how each compliance strategy is applied.

FPE RAI 04 The compliance basis for LAR Attachment A, Section 3.3.3, "Interior Finishes," states that "walls, floors and ceilings are of reinforced concrete or concrete block construction and use of interior finish materials is limited to non-combustible material or those with a flame spread, smoke and fuel contribution of 50 or less (ASTM E-84) whenever practicable." However, NFPA 805, Enclosure Section 3.3.3 requires interior wall or ceiling finish classification to be in accordance with NFPA 101, "Life Safety Code requirements for Class A materials." NFPA 101, Section 10.2.3.4 defines Class A as "Flame spread index, 0-25." Provide a justification for the apparent finish classification discrepancy.

FPE RAI 05 LAR Attachment A lists the requirement for NFPA 805, Section 3.4.4, "Firefighting Equipment."

However, radiation monitoring, personal dosimeters, and fire extinguishers are not discussed in the LAR. Provide additional details for these elements, listed in the NFPA 805, Section 3.4.4 requirement.

FPE RAI 06 LAR Attachment A, Section 3.3.5.1 identifies the need for 10 CFR 50.48{c){2){vii) approval for use of non-plenum rated cables above the suspended ceiling of the control room {CR). LAR Attachment L, Approval Request #3 indicates that "the wiring/cable may be small amounts of video/communications cable that is not listed for plenum use as required by this section of the code." Provide a more definitive description of the "limited amount" of unqualified cabling materials and quantities (either inside or outside of raceways). Include a more detailed justification for the conclusion that it "does not present a significant fire hazard." Describe whether the areas above the suspended ceilings are provided with credited fire detection and how it is identified in LAR Attachment C, Table C-2.

FPE RAI 07 LAR Attachment C, Tables C-1 and C-2 identify "enhanced transient controls" for certain areas (for example electrical penetration rooms, cable spread room, cable loft, and reactor auxiliary building corridor). Describe what those controls are, where in the plant these controls are established, and how this is managed by plant procedures. Describe how this is different than "Transient Exclusion Zones" listed in LAR Section 4.6.2.

FPE RAI 08 LAR Attachment K, identifies previously approved exemptions and deviations from 10 CFR 50, Appendix R that require transition to the NFPA 805 program. Provide clarification to the following:

a. LAR Attachment K, identifies radiant energy shields and 18 accessible fire extinguishers credited in Fire Area 1 K as an element of the exemption 1-LA-03-19850221 for Unit 1 reactor coolant pump (RCP) oil collection system. LAR Attachment C, Table C-2 identifies radiant energy shields required for risk reduction only. Justify why the radiant energy shields and fire extinguishers shouldn't also be required for "E-EEEE/LA Criteria," as indicated in LAR Section 4.8.1.

b. LAR Attachment K, identifies fire extinguishers and hose stations for Fire Areas A, J, and L as one element of the basis for the exemption 1-LA-08-19850221 for the lack of fire rated dampers. However, LAR Attachment C, Table C-2 does not identify either extinguishers or hose stations as fire protection features for the exemptions being transitioned. Justify why the fire extinguishers and hose stations shouldn't also be required for "E-EEEE/LA Criteria," as indicated in LAR Section 4.8.1.

c.

LAR Attachment K, identifies fire extinguishers and standpipe system as part of the evaluation for the exemption 1-LA-13-19870305 for the lack of 3-hour rated penetration seals. However, these features are not identified in Attachment C, Table C-2. Justify why these features shouldn't also be required for "E-EEEE/LA Criteria," as indicated in LAR Section 4.8.1.

d. LAR Attachment K, identifies fire extinguishers and hose stations as elements of the basis for the exemption 1-LA-14-19870305 for the lack of fire rated dampers. Justify why the fire extinguishers and hose stations shouldn't also be required for "E-EEEE/LA Criteria," as indicated in LAR Section 4.8.1.

e. Provide a review of the fire protection features being relied upon for any of the transitioned exemptions and deviations of LAR Attachment K. Provide justifications for any fire protection features not identified in LAR Attachment C, Table C-2.

FPE RAI 09 The compliance statement for LAR Attachment A, Table 8-1, Section 3.4.1 (c) is "complies."

NFPA 805, Section 3.4.1(c) specifically requires the fire brigade leader and two brigade members to have sufficient training and knowledge of nuclear safety systems to understand the effects of fire and fire suppressants on nuclear safety performance criteria. The compliance basis for this element states that the brigade leader and at least two brigade members have sufficient training and knowledge of nuclear safety systems to understand the effects of fire and fire suppressants on nuclear safety performance; but it does not specify the details of the training and knowledge of these members. An approach acceptable to the Nuclear Regulatory Commission (NRC) staff for meeting this training and knowledge requirement is provided in Regulatory Guide (RG) 1.189, "Fire Protection for Nuclear Power Plants," Revision 2, Section 1.6.4.1, "Qualifications," which states:

The brigade leader and at least two brigade members should have sufficient training in or knowledge of plant systems to understand the effects of fire and fire suppressants on safe-shutdown capability. The brigade leader should be competent to assess the potential safety consequences of a fire and advise control room personnel. Such competence by the brigade leader may be evidenced by possession of an operator's license or equivalent knowledge of plant systems.

Describe how the requirements of NFPA 805, Section 3.4.1 (c) are met with regard to training and knowledge of the leader and at least two members of each fire brigade.

FPE RA110 LAR AttachmentS, Table S-1 and LAR Attachment C, Table C-1 state that incipient detection is to be installed in the cable spreading room (CSR). Provide more details regarding system design features: NFPA code(s) of record, installation, acceptance testing, set-point control, alarm response procedures and training, and routine inspection, testing, and maintenance that will be implemented to credit this new incipient detection system. Describe whether the installation and credit that will be taken will be in accordance with the method elements, limitations, and criteria of NUREG/CR-6850, Supplement 1, "Fire Probabilistic Risk Assessment Methods Enhancements,"

Chapter 13 and provide justification for any deviations.

FPE RAI11 LAR AttachmentS, Table S-1 identifies several proposed modifications to "protect" cables or signals (i.e., 1A-MR-1, 1 8-MR-01, 1 C-MR-01 through 05, 2A-VM-01, and 21-MV-02). Provide a more definitive description of this protection. If barriers or rated cabling is to be used, describe the type of rated configurations that will be installed. If cable reroutes will be used, describe what type of new cable will be used and how that will be incorporated in the design.

SSA RAI 01 LAR Attachment G, Table G-1, "Recovery Actions and Activities Occurring at the Primary Control Station(s)," provides a list of primary control stations (PCSs) for Units 1 and 2. There are approximately 25 PCSs locations identified for Unit 1 and 32 for Unit 2. The LAR defines PCS actions that contain activities such as placing specified transfer switches in their "isolate" position, selected tripping of breakers, selected removal of power to provide independence, and electrical separation from potentially damaged circuits. Many of these appear to be operator actions in locations separate from the remote shutdown panels, which may not meet the definition of PCS in RG 1.205, "Risk-Informed, Performance-Based Fire Protection for Existing light-Water Nuclear Power Plants," Revision 2. Justify each of these locations as having met the definition of PCS as defined in RG 1.205, Revision 2.

SSA RAI 02 LAR Attachment 8, Table 8-2, Section 3.2.1.2, "Fire Damage to Mechanical Components,"

assumes that damage to mechanical components (e.g., pipes and valves) subjected to a fire is not considered credible, except for"[... ] heat sensitive materials, including tubing with brazed or soldered joints[... ]."

Describe how the failure of brazed or soldered joints in a fire was considered in the NFPA 805 nuclear safety capability analysis (NSCA).

SSA RAI 03 LAR Attachment 8, Table 8-2 Section 3.2.1.2 "Fire Damage to Mechanical Components" states:

"[... ]the SSA [safe shutdown analysis] includes required actions to manually operate valves that are in the affected fire area." This appears to be in conflict with the statement made in LAR Section 4.2.1.1, Subheading, "Comparison to NEI [Nuclear Energy Institute] 00-01, Revision 2,"

that states, "There are no recovery actions on valves in the same area as the fire."

Discuss which statement is correct. If the SSA includes required actions to manually operate valves that are in the affected fire area, provide an analysis that demonstrates the operability of the valves given potential fire damage.

SSA RAI 04 LAR Attachment G, Table G-1, "Recovery Actions and Activities Occurring at the Primary Control Station(s)," indicates that some door openings for cooling are identified as PCS(s) instead of recovery actions (RAs) (e.g., Fire Area 2F, Doors RA-85 and RA-87). Provide justification why opening doors for ventilation support is considered an action at a PCS.

SSA RAI 05 LAR Attachment 8, Section 3.3.1.6, "ESFAS [engineered safety feature actuation system]

Initiation," identifies the compliance strategy as "Aligns with Intent." Provide an explanation of the portion of the guidance provided in NEI 00-01, "Guidance for Post Fire Safe Shutdown Circuit Analysis," Revision 2, Section 3.3.1.6 that is not met.

SSA RAI 06 LAR Attachment 8, Section 3.3.1. 7, "Circuit Coordination," states, "St. Lucie did not follow the methodology in NEI 00-01 but did end up with the same result." Provide more explanation with regard to the scope of circuit coordination used to satisfy NFPA 805. Include in that discussion the types of resolutions for lack of coordination and if any of these resolutions included variance from deterministic requirements (VFDRs), RAs, modifications, electrical raceway fire barrier systems, or "risk evaluation with no further action required."

SSA RAI 07 LAR Attachment 8, Section 3.3.3.2, "Interlocked Circuits whose Spurious Operation Could Affect Shutdown," identifies the compliance strategy as "Aligns with Intent." Provide an explanation of the portion of the NEI 00-01, Revision 1, Section 3.3.3.2 that is not met.

SSA RAI 08 LAR Attachment 8, Section 3.3.3.4, "Routing Cables," and 3.3.3.5, "Routing Raceway," state that

"[... ] the raceway details would only provide an additional layer of information however, this additional level of detail does not affect the end results since the location cable information is ultimately determined[... ]. The end result was several reports from the cable routing system which listed cables by fire area as well as listing cables by fire zone routes. As a result, the raceway information is not important to the results and is not captured in the SSA."

For individual fire scenarios with zones of influence (ZOis) smaller than a fire zone; explain how targets are identified and included in the analysis. Identify any assumption made for cables without routing information.

SSA RAI 09 LAR Attachment 8, Section 3.5.2.1, "Circuit Failures Due to an Open Circuit," with respect to current transformers (CTs) states that "the potential for secondary fires (especially for CT circuits on ammeters not associated with safe shutdown equipment) requires additional analysis. The licensee commits to ensuring that CT circuits with the potential for secondary fire will be protected from fire-induced open circuits as part of its implementation for NFPA 805." This appears as though future analysis or work will be required.

LAR AttachmentS, Table S-2, "Implementation Items," number 10 states, "Review NUREG/CR-7150 Vol. 2 when published to determine if conclusion that an open secondary CT is not a concern [... ]. " Provide an explanation of what work is still outstanding, and estimate the potential impact to the fire protection program (FPP) as presented in the LAR. Justify why this additional work should not be added as an Implementation Item.

SSA RAI10 LAR Section 4.2.1.1, "Compliance with NFPA 805 Section 2.4.2" states that "the only current transformers with larger turns ratio are located in the turbine building for the power feeds from the startup and auxiliary transformers and the generator output and current transformers located in the switchyard. These do not impact the NSCA (no credit for offsite power)." Clarify what is meant by "no credit for offsite power." Provide more explanation why potential secondary fires do not affect the NSCA. Describe how secondary fires due to CTs were addressed in the Fire Probabilistic Risk Assessment (FPRA).

SSA RAI11 LAR Attachment 8, Section 3.4.1.5, "Repairs," states that "St. Lucie Unit 1 does not credit any repairs for cold shutdown. St. Lucie Unit 2 takes credit for limited repairs during cold shutdown (i.e., inserting fuses that are part of the normal shutdown procedures)." Provide a more detailed explanation of those repairs. For those fire areas where repairs are necessary to achieve safe and stable, describe the location of these actions. Describe how these are procedurally controlled with parts/fuses/components pre-staged, and how is training conducted to perform this work.

Describe whether the cold shutdown repairs are included in the FPRA.

SSA RAI12 LAR Attachment 8, Table 8-2, Section 3.1, "C. Spurious Operations," indicates that spurious signals, impact on high-low pressure interfaces, multiple spurious operation (MSO), and common enclosure/power supplies were analyzed for their impact on NSCA. However the staff noted the referenced analysis does not address all of these elements. The referenced analysis does not appear to reflect additional components and power supplies that were added for NFPA 805 considerations of MSO, common enclosure/power supplies, or equipment added for the NSCA.

Describe how the additional equipment of the FPRA were added to the nuclear safety equipment list.

SSA RAI13 LAR Attachment 8, Table 8-2, Section 3.2.1.6, "Spurious Components," indicates that "the guidance related to multiple spurious operations from NEI 00-01 Revision 2 has been addressed and included in the SSA or entered into the plant corrective action program." A similar statement was made for Section 3.5.1.5, "Circuit Failure Risk Assessment." Provide more detail regarding the resolution of the identified corrective actions. Describe what FPRA equipment/power supplies are still awaiting disposition in the corrective action program and how this will affect the results of the NSCA currently presented in the LAR.

SSA RAI14 The Fire Risk Evaluations (FREs) described in LAR Attachment C, NEI 04-02, Table B-3, "Fire Area Transition," all refer to evaluating VFDRs generally as "this condition was evaluated for compliance using the performance-based approach of NFPA 805, Section 4.2.4. An FRE determined that applicable risk, defense-in-depth (DID), and safety margin criteria were satisfied without further action." However, there is no specific description of the associated criteria or any other details identified in the LAR. LAR Section 4.5.2.2 generally defines DID and safety margin as listed in NEI 04-02, "Guidance for Implementing a Risk-Informed, Performance-Based Fire Protection Program Under 10 CFR 50.48(c)," but does not describe the methodology, controls, and systems for providing DID and safety margins. Provide additional detail, specific to St. Lucie, of the methods and criteria for evaluating DID and safety margins.

PROG RAI 01 Based on the NRC staff's review of the LAR and associated documentation, it was determined that the LAR did not provide the information needed for the NRC staff to evaluate what changes will be made to the FPP to incorporate the requirements of NFPA 805, Sections 2. 7.3.4 and 3.3.1.1.

Describe the changes that are planned to the FPP as part of the NFPA 805 transition process that are specifically associated with training. In addition, describe the positions where such training would be necessary.

PROG RAI 02 NFPA 805, Section 2. 7.3.4, "Qualification of Users," states that cognizant personnel who use and apply engineering analysis and numerical models (e.g., fire modeling techniques) shall be competent in that field and experienced in the application of these methods as they relate to nuclear power plants, nuclear power plant fire protection, and power plant operations.

Describe the qualification program that will support the NFPA 805 change evaluation process.

Include positions that will be trained and how the training will be implemented (e.g., classroom, computer-based, reading program).

FM RAI 01 NFPA 805, Section 2.4.3.3, states: "The PSA [probabilistic safety assessment] approach, methods, and data shall be acceptable to the AHJ [authority having jurisdiction] [... ]. " The NRC staff noted that fire modeling comprised the following:

The consolidated fire growth and smoke transport (CFAST) model was used to calculate control room abandonment times, and in the hot gas layer (HGL) and multi-compartment analyses (MCA).

Heskestad's plume temperature correlation was used to determine Severity Factors.

The generic fire modeling treatments (GFMTs) approach was used to determine the ZOI in all fire areas throughout plant.

FLASH-CAT for calculating fire propagation in stacks of horizontal cable trays.

HEATING 7 computer code was used in the assessment of the relative safety margins of cable damage for thermoplastic cables.

LAR Section 4.5.1.2, "Fire PRA," states that fire modeling was performed as part of the FPRA development (NFPA 805, Section 4.2.4.2). Reference is made to LAR Attachment J, "Fire Modeling V&V," for a discussion of the acceptability of the fire models that were used.

Specifically regarding the acceptability of CFAST for the main control room (MCR) abandonment time calculations:

a. The MCR abandonment analysis indicates that parts of the walls of the MCRs are covered with wood paneling. Provide technical justification for not considering fire scenarios that involve this wood paneling.

b. Provide the basis (e.g. data from fire drills) for the assumption in the MCR abandonment time calculations that the fire brigade is expected to arrive within 15 minutes. Describe the uncertainty associated with this assumption, discuss possible adverse effects of not meeting this assumption on the results of the FPRA and explain how possible adverse effects will be mitigated.

c.

Explain how the different fires (six in Unit 1 and five in Unit 2) and ventilation conditions (six in both units) were weighted in terms of their contribution to the probability and associated risk for MCR abandonment and provide technical justification for the approach that was used. In addition, for the electrical panel fire scenarios that were considered in the FPRA, provide technical justification for the location of the fire (inside or outside the MCR) in the CFAST analysis and explain up to what extent fire spread to adjacent panels was assumed.

d. For the case when cables in an adjacent electrical cabinet are in direct contact with the separating wall, NUREG/CR-6850, Appendix S recommends a fire spread time of 10 minutes. Provide technical justification for using the assumption in the MCR abandonment time calculations that fire spreads to adjacent cabinets in 15 minutes.

e. LAR Attachment H, Table H-1 indicates that frequently asked question (FAQ)-08-0052, "Transient Fires - Growth Rates and Control Room Non-Suppression" (ADAMS Accession No. ML092120501) was used in the LAR submittal. Provide justification for using transient fire growth rates in the Units 1 and 2 MCR abandonment time calculations that are different from those specified in FAQ-08-0052.

f.

Some fire model parameters that were assessed in the sensitivity analyses for the Units 1 and 2 MCR abandonment time calculations appear to have a significant effect on the abandonment times. For example, an elevated ambient temperature in the MCR may significantly reduce the abandonment time under certain conditions. Explain how the results of the sensitivity analyses were used in the FPRA.

Specifically regarding the acceptability of the GFMTs approach:

g. In GFMTs, Section 2.4 describes the critical heat flux for a target that is immersed in a thermal plume. Explain how the modification to the critical heat flux was used in the ZOI determination.

h. Provide technical justification to demonstrate that the GFMTs approach as used to determine the ZOI of fires that involve multiple burning items (e.g., an ignition source and an intervening combustible such as a cable tray) is conservative and bounding.

i.

Regarding the flame spread and fire propagation in cable trays:

i.

Describe how the flame spread and fire propagation in cable trays and the corresponding heat release rate (HRR) of cables was determined.

ii.

Provide technical justification for the assumption that the lowest cable tray in a stack located above an ignition source will not ignite unless the tray is located below the flame tip of the ignition source fire.

iii.

Explain how cables coated with Flamemastic 77 and covered cable trays were treated in these calculations.

iv.

Describe how the flame spread, fire propagation and HRR estimates affect the ZOI determination and HGL temperature calculations.

j.

Describe how transient combustibles in an actual plant setting are characterized in terms of the three fuel package groupings in the GFMTs Supplement 3 (Transient Ignition Source Strength). Identify areas, if any, where the NUREG/CR-6850 transient combustible HRR characterization (probability distribution and test data) may not encompass typical plant configurations. Finally, explain if any administrative action will be used to control the type of transient in a fire area at St. Lucie Units 1 and 2.

Regarding the FLASH-CAT model:

k.

Describe how the ignition time of the bottom tray in the stack was determined.

I.

Explain why the approach to model fire propagation in a vertical stack of two cable trays (or less) described in Supplement 2 of the GFMTs bounds the FLASH-CAT model in light of the fact that the approach assumes ignition at a single point as opposed to ignition over the characteristic length in FLASH-CAT.

Regarding the acceptability of the approach, methods, and data in general:

m. The NRC staff identified the possibility that non-cable intervening combustibles were missed in fire areas of the plant. For example, during the audit walkdown, the NRC staff observed some combustible pipe insulation in the Unit 2 CSR. Provide information on how non-cable intervening combustibles were identified and accounted for in the fire modeling analyses.

n. During the onsite audit the licensee discussed fire location factors for transient fires and stated that, due to the conservatism associated with the HRRs used and the low likelihood that a fixed ignition source is close enough to a wall or corner and orientated such as to be significantly influenced by the presence of a wall or corner, no specific increases of HRRs were incorporated in the fire modeling. Provide technical justification for not accounting for wall and corner effects in the case of transient fires, combustible liquid fires and electrical cabinet fires.

Specifically regarding the acceptability of the HGL and MCA calculations:

o. Provide the technical basis for the assumption that no HGL will develop in areas that are modified to vent to the outside atmosphere. During the onsite audit the NRC staff determined that the areas that are referred to are the 1 8 and 28 switchgear rooms.

Describe these modifications and any additional assumptions that are included in this screening method, and provide technical information to demonstrate that these modifications will prevent the development of an HGL condition.

p. Explain how high energy arcing fault (HEAF) initiated fires were addressed in the HGL analysis and provide technical justification for the approach that was used to calculate HGL timing. More specifically, provide technical justification for not using the guidance in NUREG/CR-6850, page 11-19, fourth bullet regarding the fire growth and page M-13, sixth bullet regarding delay to cable tray ignition. Also, considering the energetic nature of the HEAF event, provide justification for the HRR to be used in the HGL calculations for electrical cabinet fires following a HEAF.

FM RAI 02 American Society of Mechanical Engineers/American Nuclear Society (ASME/ANS) Standard RA-S-2008, "Standard for level1/large Early Release Frequency Probabilistic Risk Assessments for Nuclear Power Plant Applications," Part 4, requires damage thresholds be established to support the FPRA. Thermal impact(s) must be considered in determining the potential for thermal damage of structures, systems, and components (SSCs). Appropriate temperature and critical heat flux criteria must be used in the analysis. Provide the following information:

a. Describe how the installed cabling in the Units 1 and 2 power block was characterized, specifically with regard to the critical damage threshold temperatures and critical heat flux for thermoset and thermoplastic cables as described in NUREG/CR-6850.

b. The technical documentation supporting the LAR that describes the fire modeling that was performed seems to imply that IEEE [Institute of Electrical and Electronics Engineers]-383 qualified cables are assumed to be equivalent in terms of damage thresholds to "thermoset" cables as defined in Table 8-2 of NUREG/CR-6850. In addition, non-IEEE-383 qualified cables are assumed to be equivalent to "thermoplastic" cables as defined in Table 8-2 of NUREG/CR-6850. These assumptions may or may not be correct. An IEEE-383 qualified cable may or may not meet the criteria for a "thermoset cable" as defined in NUREG/CR-6850. It is also possible that a non-IEEE-383 qualified cable actually meets the NUREG/CR-6850 criteria for a "thermoset" cable. Provide clarification on the assumptions that were made in terms of damage thresholds of cables.

c.

Describe how cable tray covers and conduits affect the damage thresholds that were used in the fire modeling analyses.

d. Explain what damage thresholds were used in the fire modeling analyses for cables coated with Flamemastic 77.

e. Describe the methodology that was used to convert damage times for thermoplastic cables in Appendix H of NUREG/CR-6850 to percent damage as a function of heat flux, and discuss the assumptions and technical basis for this methodology. In addition, explain how this methodology was applied to determine damage to targets within the horizontal ZOI.

FM RAI 03 NFPA 805, Section 2.7.3.2, "Verification and Validation," states: "Each calculational model or numerical method used shall be verified and validated through comparison to test results or comparison to other acceptable models."

LAR Section 4.5.1.2, "Fire PRA," states that fire modeling was performed as part of the fire PRA development (NFPA 805 Section 4.2.4.2). Reference is made toLAR Attachment J, "Fire Modeling V&V," for a discussion of the verification and validation (V&V) of the fire models that were used.

Furthermore LAR Section 4.7.3, "Compliance with Quality Requirements in Section 2.7.3 of NFPA 805," states, "Calculational models and numerical methods used in support of compliance with 10 CFR 50.48(c) were verified and validated as required by Section 2.7.3.2 of NFPA 805."

Regarding the V&V of fire models:

a. Provide the V&V basis for the methods and correlations used to calculate flame height, HRR, flame spread, incident heat flux to targets, etc. in the fire hazard assessment of exposure to safe shutdown raceways in Unit 1 developed in support of the licensee's request for 10 CFR 50 Appendix R K1 Exemption.

b. Provide the V&V basis for the methodology that was used to convert damage times for thermoplastic cables in Appendix H of NUREG/CR-6850 to percent damage as a function of heat flux.

c. Provide the V&V basis for the model that was used to calculate the HGL temperature in the non-suppression probability (NSP) calculations for the containment. Provide technical details to demonstrate that the model has been applied within the validated range of input parameters, or to justify the application of the model outside the validated range reported in V&V basis documents.

FM RAI 04 NFPA 805, Section 2.7.3.3, "Limitations of Use," states: "Acceptable engineering methods and numerical models shall only be used for applications to the extent these methods have been subject to verification and validation. These engineering methods shall only be applied within the scope, limitations, and assumptions prescribed for that method."

LAR Section 4.7.3, "Compliance with Quality Requirements in Section 2.7.3 of NFPA 805," states that "Engineering methods and numerical models used in support of compliance with 10 CFR 50.48(c) were applied appropriately as required by Section 2.7.3.3 of NFPA 805."

Regarding the limitations of use, identify uses, if any, of the GFMTs (including supplements) outside the limits of applicability of the method and for those cases, explain how the use of the GFMTs approach was justified.

FM RAI 05 NFPA 805, Section 2.7.3.4, "Qualification of Users," states: "Cognizant personnel who use and apply engineering analysis and numerical models (e.g., fire modeling techniques) shall be competent in that field and experienced in the application of these methods as they relate to nuclear power plants, nuclear power plant fire protection, and power plant operations."

LAR Section 4.5.1.2, "Fire PRA," states that fire modeling was performed as part of the fire PRA development (NFPA 805 Section 4.2.4.2). This requires that qualified fire modeling and PRA personnel work together. Furthermore, LAR Section 4.7.3, "Compliance with Quality Requirements in Section 2.7.3 of NFPA 805," states:

Cognizant personnel who use and apply engineering analysis and numerical methods in support of compliance with 1 0 CFR 50.48( c) are competent and experienced as required by Section 2. 7.3.4 of NFPA 805.

During the transition to 10 CFR 50.48(c), work was performed in accordance with the quality requirements of Section 2. 7.3 of NFPA 805. Personnel who used and applied engineering analysis and numerical methods (e.g., fire modeling) in support of compliance with 10 CFR 50.48(c) are competent and experienced as required by NFPA 805 Section 2.7.3.4.

Post-transition, for personnel performing fire modeling or fire PRA development and evaluation, Florida Power & Light Company will develop and maintain qualification requirements for individuals assigned various tasks. Position Specific Guides will be developed to identify and document required training and mentoring to ensure individuals are appropriately qualified per the requirements of NFPA 805, Section 2.7.3.4, to perform assigned work. See Implementation Item 15 in Table S-2 of AttachmentS. (see LAR AttachmentS).

Regarding qualifications of users of engineering analyses and numerical models (i.e., fire modeling techniques):

a. Describe the requirements to qualify personnel for performing fire modeling calculations in the NFPA 805 transition.

b. Describe the process for ensuring that the fire modeling personnel meet those qualifications, not only before the transition but also during and following the transition.

c. When fire modeling is performed in support of FPRA, describe how proper communication between the fire modeling and FPRA personnel is ensured.

FM RAI 06 NFPA 805, Section 2.7.3.5, "Uncertainty Analysis," states: "An uncertainty analysis shall be performed to provide reasonable assurance that the performance criteria have been met."

LAR Section 4.7.3, "Compliance with Quality Requirements in Section 2.7.3 of NFPA 805," states that "Uncertainty analyses were performed as required by 2.7.3.5 of NFPA 805 and the results were considered in the context of the application. This is of particular interest in fire modeling and fire PRA development."

Regarding the uncertainty analysis for fire modeling:

a. Describe how the uncertainty associated with the fire modeling input parameters was accounted for in the fire modeling analyses.

b. Describe how the "model" and "completeness" uncertainties were accounted for in the fire modeling analyses.

RR RAI 01 Where containment and confinement cannot be relied upon, describe whether an analysis been performed to demonstrate that the instantaneous release limits in the Technical Specifications or other 10 CFR 20 limits will not be exceeded.

For example, in reference to "RCA-Yard" area, the LAR states,"[... ] there are no engineering controls to prevent radioactive release [... ]." The LAR then states, "[... ]fire suppression activities

[in "RCA-Yard" areas] will not result in a radioactive release that exceeds the 10 CFR 20 limits."

The LAR states, "The evaluations performed to meet the radioactive release performance criteria are qualitative in nature." Provide additional information on either the qualitative assessment or a quantitative assessment.

PRA RAI 01 -Fire PRA Facts and Observations (F&Os)

Section 2.4.3.3 of NFPA 805 states that the probabilistic safety assessment (PSA is also referred to as PRA) approach, methods, and data shall be acceptable to the AHJ, which is the NRC.

RG 1.205 identifies NUREG/CR-6850 as documenting a methodology for conducting a FPRA and endorses, with exceptions and clarifications, NEI 04-02, Revision 2, as providing methods acceptable to the staff for adopting an FPP consistent with NFPA-805. RG 1.200, "An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities," describes a peer review process using an associated ASME/ANS standard (currently ASME/ANS-RA-Sa-2009) as one acceptable approach for determining the technical adequacy of the PRA once acceptable consensus approaches or models have been established for evaluations that could influence the regulatory decision. The primary result of a peer review are the facts and observations (F&Os) recorded by the peer review and the subsequent resolution of these F&Os.

Clarify the following dispositions to fire F&Os and Supporting Requirement (SR) assessment identified in LAR Attachment V that have the potential to impact the FPRA results and do not appear to be fully resolved:

a. F&O PP-A1-01 against SR PP-A1 The disposition to F&O PP-A 1 does not address the statement that "[e]vidence was presented to the [peer] reviewer that raceways supporting PRA equipment exist in the 'no man's land' area between unit 1 and unit 2." Explain whether PRA-credited equipment exists in this area, which, according to the F&O, is not included as part of a PRA-analyzed compartment.

b. F&O PP-C2-01 against SR PP-C2 The disposition to F&O PP-C2 regarding the exclusion of locations within the licensee-controlled area appears to only address whether locations may contain PRA-credited components. Clarify the treatment of those locations that may contain other than PRA-credited fire sources that could threaten credited equipment or cable items by virtue of a multi-compartment fire scenario.

c.

F&O PP-87-01 against SR PP-87 and F&O PP-C3-01 against SR PP-C3 The disposition identifies that a draft version of the NISYS-1251-0001, "Fire Hazards Analysis (FHA) Review/Update," was included as a reference in the Fire Ignition Frequency Development report; however, as identified in the F&O, the report appears to still require finalization. Describe the status of the draft report, and clarify what changes have been made after the peer review. Additionally, provide a basis for partitioning performed in the Unit 2 turbine building in light of the fact that Section 2.2 of the Fire Ignition Frequency Development report notes that the FHA does not provide for any separation of the Unit 2 turbine building.

d. F&O ES-C1-01 against SR ES-C1 Fire-induced instrument failure should be addressed in the fire human reliability analysis (HRA) per NUREG/CR-6850 and NUREG-1921, "EPRI/NRC-RES Fire Human Reliability Analysis Guidelines." The Human Failure Evaluation report and the disposition to F&O ES-C1 indicate that the availability of instrumentation is predicated on the Appendix R SSA; however, the FPRA credits systems and/or functions not previously analyzed by the Appendix R analysis. Additionally, Appendix R instrumentation, which is specifically indicated by bold formatting in Tables A-1 through A-4 of Human Failure Evaluation report, is not identified for all human failure events (HFEs). Current fire response procedures (e.g., 2-AOP-1 00.11) also indicate the availability of essential instrumentation on a fire-area basis; however, documentation provided by Tables A-1 through A-4 of Human Failure Evaluation report does not. A review of Human Failure Evaluation report also indicates that the availability of instrumentation associated with fire-specific HFEs (i.e.,

those not carried over from the internal events (IE) PRA) does not appear to have been evaluated. Moreover, the NFPA 805 Recovery Action Feasibility Evaluations (PSL-FPER-11-002) appear to solely list local or remote position and/or indication for the "Systems and Indications" criteria. In light of these deficiencies:

i.

Describe how instrumentation that is relied on for credited operator actions was identified and verified as available to a level of detail commensurate with the risk importance and quantification of all human error probabilities (HEPs).

ii.

Discuss the extent to which cues and indications have been addressed for fire-specific HFEs.

iii. Discuss the degree to which the post-transition fire response procedures are credited to support the FPRA HRA (e.g., to provide procedure-based cues for actions, to identify available or impacted instrumentation).

iv. Describe how fire-induced instrument failures (including no readings, off-scale readings, and incorrect/misleading readings) are addressed by the FPRA model and HRA. Include discussion of the success criteria assumed for this modeling.

e. F&O ES-C2-01 against SR ES-C2 There appears to be no documented process for systematically identifying and defining HFEs that may result in an undesired operator response (i.e., error of omission or commission) to spurious or absent cues and indication as recommended in Section 3.4.1 of NUREG-1921. Describe and further justify the process utilized to identify and model such actions on a fire scenario basis.

f.

F&O CS-A11-01 against SRs CS-C3 and CS-A11 as well as F&O FSS-E4-01 against SR FSS-E4 The disposition to this F&O indicates that exclusions based on assumptions of routing were eliminated; however, the disposition does not address how the specific scenarios referenced by the F&O were resolved or provide reference to an updated basis for exclusions that were maintained. Address the following:

i.

Clarify that all cables are either fully routed to a level of detail commensurate with the fire scenario analysis or assumed to impact associated components.

ii.

If any exclusion originally based on assumed cable routing is maintained in the FPRA, describe the scope of additional analysis performed to support the continued exclusion, and identify where this effort is documented.

iii. Clarify the reconciliation performed between the Appendix R methodology and that used in NFPA 805, including verification that all exclusions based on "Appendix R component disposition codes", as discussed in Section 12.0 of the Fire Scenario Report, remain valid.

g. F&O FSS-A1-01 against SR FSS-A1 The disposition to this F&O does not appear sufficient to fully address the deficiencies identified by the peer review. As a result,

i.

Identify the locations in which hydrogen piping is routed, and provide technical justification for excluding miscellaneous hydrogen fires in each location.

ii.

Provide technical justification for excluding any flammable liquid fire scenarios for fixed fire sources (e.g., pumps, diesel generators, main station transformers, and turbine generators) that may contain combustible liquids (e.g., as fuel or for lubrication).

h. F&O HRA-A2-01 against SR HRA-A2 As noted by the peer review report, there appears to be no documented process for the identification of fire-specific manual actions. Describe the process utilized to identify fire-related human actions relevant to each fire scenario in the FPRA plant response model (including but not limited to NFPA 805 recovery actions).

i.

F&Os FQ-C1-03 against SR FQ-C1 F&O FQ-C1-03 indicates that a minimum value was not utilized for the joint probability of multiple HFEs. Section 6.2 of NUREG-1921 addresses the need to consider a minimum value for the joint probability of multiple HFEs. Considering this guidance, confirm that joint HEP values that appear in FPRA cutsets are appropriate.

j.

F&Os UNC-A 1-03 against SR UNC-A 1 A review of the FPRA Summary report indicates that the parametric uncertainties were propagated to obtain a distribution for fire-induced core damage frequency (CDF) and large early release frequency (LERF); however, the state-of-knowledge correlation (SOKC) does not appear to have been taken into account. Discuss how the SOKC was evaluated for fire CDF and LERF, identifying the fire-PRA-specific parameters (e.g., hot short probabilities, fire frequencies) that can appear in FPRA cutsets and how they were correlated.

k.

F&O FSS-09-01 against SR FSS-09 This F&O indicates that the FPRA did not postulate failures due to smoke damage.

Explain how the effect of smoke on equipment was evaluated (e.g., by using the guidance provided in Appendix T of NUREG/CR-6850).

I.

F&O HRA-A2-01 against SR HRA-A2 According to this F&O, the fire-related manual actions were not included as basic events in the FPRA model but rather "were incorporated into the model by altering the failure probability of a related equipment failure basic event" through use of the FRANC (a fire PSA model) Altered Events file. Section 4.1 of the Human Failure Evaluation report further states that "for logic in which multiple basic events (BEs) are correlated to a fire failure and in which these events are input to an "OR" gate (directly or indirectly), [one of]

the events is set to the screening [HEP] value while the others are set to their random failure probability to eliminate the potential for non-minimal cutsets." Clarify this statement, and describe the process for applying screening HEPs, including any modeling manipulations made to the PRA logic (e.g., setting other basic events to their nominal random failure probability). Additionally, qualitatively discuss the impact of any logic manipulations on total fire risk and delta risk.

m. F&O FSS-H1-01 against SR FSS-H1 and F&O FSS-H8-01 against SR FSS-H8 As noted in the disposition to this F&O, the electrical panel factor approach was eliminated from the FPRA; however, in its place, a target-distance-based methodology that is documented in Appendix E of the Fire Scenario Report is applied. Additionally, as noted in the disposition to F&O FSS-H8-01, HGL analysis and MCA has been revised. A review of the HGL and MCA report indicates significant enhancements to the treatment of HGL since the peer review, particularly in the development of HGL scenarios and the fire modeling used to support the calculation of the time to HGL, and the removal of MCA screening criteria. In light of these modeling updates, address the following:

i.

In Appendices A, E and J of the HGL and MCA report, non-suppression probabilities (NSPs) associated with the target-distance-based methodology split fractions and those associated with suppression of the fire prior to HGL formation appear to be multiplied together. Given that these NSPs do not appear to be independent, the resulting NSP values applied to scenarios associated with a particular ignition source would appear to be underestimated. In addition, given the manner in which NSP values are being applied, it is unclear if the resultant NSP value for each scenario is below 0.001, the NUREG/CR-6850-recommended lower bound. As a result, describe and justify how NSP values for scenarios associated with a particular ignition are calculated such that any dependencies between fire scenario development branch points are appropriately taken into account, and confirm that for any scenario, the resulting NSP applied is no less than 0.001.

ii.

Section 4.2.1.1 of the HGL and MCA report states that if automatic detection is present, the time for suppression begins at time = 0, and if not, 15 minutes is assumed. However, there appears to be no discussion of detector reliability and unavailability. A review of Appendix E of the Fire Scenario Report and Appendix L of the HGL and MCA report appears to indicate that the target-distance-based methodology used to develop non-suppression probabilities does not account for detector reliability. Describe how detection system reliability is addressed by the FPRA. If detection system reliability is not included in the analysis, provide justification of this exclusion, and evaluate its impact on risk results.

iii. Section 4.2.2.1 of the HGL and MCA report states that the electrical fire suppression curve is used for all non-transient fires and is considered bounding; however, per guidance in Supplement 1 to NUREG/CR-6850, this is not always the case (e.g.,

HEAFs, oil fires, etc.). For instance, the more challenging nature of a fire that follows a HEAF should be represented by the HEAF suppression curve from NUREG/CR-6850, Appendix P or FAQ 08-0050 in lieu of the electrical fire suppression curve. Provide further justification for this assumption.

n. F&O FSS-A1-02 against SR FSS-A1 As indicated by this F&O, only manual suppression was credited in the FPRA at the time of the peer review; however, following the peer review, credit has been taken for automatic suppression systems. As a result, address the following:

i.

Explain how automatic suppression is credited in the analysis.

ii.

Provide additional justification that generic estimates reflect actual system unreliability and unavailability. Section 4.2.1.2 of the HGL and MCA report indicates that generic estimates of suppression system unreliability from NUREG/CR-6850 were utilized; however, it appears that no review of plant records was performed to determine if the generic unavailability credit is consistent with actual system unavailability. Additionally, F&O FSS-D7-01 indicates that such a review for outlier behavior was not performed.

iii. Describe the dependencies that exist amongst credited suppression paths, and discuss how they were evaluated and modeled.

iv. Provide a technical justification for the methodology used to determine or calculate sprinkler activation time (in any fire area). If sprinkler activation time was not calculated, provide a technical justification for not having to determine this time quantitatively. Section 4.2.1.2 states that automatic suppression is credited to prevent the formation of a HGL; however, there appears to be no fire detection analysis conducted in support of the activation of fixed suppression systems.

Section 4.2.1.1 of the HGL and MCA report also appears to indicate that automatic suppression is assumed to occur at time = 0.

o. F&O HRA-83-01 against SR HRA-83 and F&O HRA-A2-01 against SR HRA-A2 HRA modeling performed to support the FPRA does not appear to have been sufficiently well documented to support peer review. For example, F&O HRA-83-01 states that fire-specific HFEs are in the model "with limited documentation and no characterization," further noting that "the definition of these HFEs is not complete and provides no scenario specific information beyond the fire scenario ID in the [FRANC] Altered Events file."

F&O HRA-A2-01 states that "[the] documentation is not sufficient to support FPRA peer review and future use."

Furthermore, the HRA screening analysis does not follow the guidance in NUREG/CR-6850 or NUREG-1921.

i.

Evaluate the impact on risk results of using approaches in NUREG/CR-6850 and/or NUREG-1921, particularly where this would employ higher HEPs than in the HRA method.

ii.

Summarize the impact of applying the criteria discussed in Section 4.3 of NUREG-1921 in assessing the feasibility of operator actions in lieu of making the assumption that all actions are feasible.

iii. Discuss the steps that will be taken to peer review this HRA method to support post-transition change evaluations.

p. F&O FSS-H1-01 against SR FSS-H1 This F&O notes that in several cases, the FPRA implemented methods beyond those available in accepted guidance documents (e.g., NUREG/CR-6850 and its supplement).

Identify and describe all deviations from accepted methods and approaches. In addition, clarify whether guidance from the letter from NRC to NEI, "Recent FPRA Methods Review Panel Decisions and EPRI 1022993, 'Evaluation of Peak Heat Release Rates in Electrical Cabinets Fires"' dated June 21, 2012 (ADAMS Accession No. ML12171A583) was used in applying related methods. For any identified deviation from accepted methods and approaches, evaluate the impact on risk results as part of the aggregate change-in-risk analysis.

PRA RAI 02 - In-Panel Detection LAR AttachmentS, Table S-1 identifies several modifications (i.e., 1 8-MR-02, 28-MR-01 and 28-MR-02) to provide in-panel detection of fires. Address the following:

a. The risk-informed characterization column of Modification 28-MR-01 in LAR Attachment S, Table S-1 indicates that incipient detection is used to support detection of a fire well in advance of significant damage. Clarify whether this credit is consistent with FAQ 08-0046.

Additionally, provide confirmation that incipient detection is not credited to limit the extent of internal fire damage within monitored panels.

b. The risk-informed characterization column of Modifications 1 8-MR-02 and 28-MR-02 in LAR AttachmentS, Table S-1 indicates that in-panel detection is used to provide early warning of fire to reduce manual non-suppression probability. During the audit, the licensee indicated that in-cabinet ionization smoke detectors are credited to limit the extent of internal fire damage within monitored panels. With the exception of Appendix L, NUREG/CR-6850 only allows credit to increase the time to damage of targets external to the panel by 5 minutes. In light of this, evaluate the impact on risk results, following this guidance.

PRA RAI 03-Counting and Treatment of Bin 15 Electrical Cabinets Section 2.4.3.3 of NFPA 805 states that the PRA approach, methods, and data shall be acceptable to the NRC. RG 1.205 identifies NUREG/CR-6850 as documenting a methodology for conducting a FPRA and endorses, with exceptions and clarifications, NEI 04-02, Revision 2, as providing methods acceptable to the staff for adopting an FPP consistent with NFPA 805. In letter dated July 12, 2006, to NEI {ADAMS Accession No. ML061660105}, the NRC established the ongoing FAQ process where official agency positions regarding acceptable methods can be documented until they can be included in revisions to RG 1.205 or NEI 04-02. Methods that have not been determined to be acceptable by the NRC staff require additional justification to allow the NRC staff to complete its review of the proposed method.

Section 7.1. 1 of Fire Scenario report appears to indicate that fires within some Bin 15 cabinets above 440V {e.g., motor control centers (MCCs)), are not assumed to propagate outside of the cabinet. Additionally, a review of walkdown sheets documented Attachment D of the Fire Ignition Frequency Development report does not appear to sufficiently document whether cabinets are well sealed and robustly secured, including for those credited as such in the HGL and MCA report.

As a result, relative to the counting and treatment of Bin 15 electrical cabinets, address the following:

a. Per Section 6.5.6 of NUREG/CR-6850, fires originating from within "well-sealed electrical cabinets that have robustly secured doors (and/or access panels) and that house only circuits below 440V" do not meet the definition of potentially challenging fires and, therefore should be excluded from the counting process for Bin 15. By counting these cabinets as ignition sources within Bin 15 the frequencies applied to other cabinets are inappropriately diluted. Clarify that this guidance is being applied. If not, provide justification for the inclusion of such cabinets in the Bin 15 count, and evaluate the impact on risk results of excluding them.

b. In addition, all cabinets having circuits of 440V or greater should be counted for purposes of Bin 15 frequency apportionment based on the guidance in Section 6.5.6 of NUREG/CR-6850. Clarify that this guidance is being applied. If not, provide justification for the exclusion of such cabinets in the Bin 15 count, and evaluate the impact on risk results of including them.

c.

Per NUREG/CR-6850, cabinets below 440V that are not well sealed and robustly secured as well all cabinets above 440V should be assumed to propagate outside the cabinet. Clarify that this guidance is being applied. If not, provide justification for not considering propagation outside of such cabinets, and evaluate the impact on risk results, considering propagation to secondary targets.

PRA RAI 04-Reduced Transient Heat Release Rates LAR Attachment V,Section V.3 indicates that a reduction in 98th-percentile HRR of NUREG/CR-6850 for transient fires is credited (i.e., from 317 kilowatts (kW) to 69 kW) for certain fire zones; however, no basis is provided to support this reduction. Address the following:

a. Identify all plant analysis units (PAUs) for which a reduction in the HRR from 317 kW to 69 kW (or other lower HRRs) for transient fires is credited.

b. For these PAUs, address the location-specific attributes and considerations, plant administrative controls, the results of a review of records related to violations of the transient combustible and hot work controls, and any other key factors used to demonstrate the adequacy of a reduced HRR per the guidance endorsed by the NRC Letter from Joseph Giitter to Biff Bradley, NEI, "Recent Fire PRA Methods Review Panel Decisions and EPRI 1022993, Evaluation of Peak Heat Release Rates in Electrical Cabinet Fires," June 21, 2012 (ADAMS Accession No. ML12171A583). In the response, address the full range of types and quantities of combustibles that are expected to be in each location and how administrative controls will enforce this range to preclude a peak HRR greater than 69 kW.

c. Perform and document a review of past transient fire experience as well as a review of records related to any violations of the transient combustible controls that may include both internal plant records (e.g., condition reports) and NRC inspection records (e.g., by residents or during triennials), and discuss how this review informs the development of administrative controls credited, in part, to justify an HRR lower than 317 kW.

PRA RAI 05 -Transient Fire Influencing Factors Section 2.4.3.3 of NFPA 805 states that the PRA approach, methods, and data shall be acceptable to the NRC. RG 1.205 identifies NUREG/CR-6850 as documenting a methodology for conducting a FPRA and endorses, with exceptions and clarifications, NEI 04-02, Revision 2, as providing methods acceptable to the staff for adopting an FPP consistent with NFPA-805. In letter dated July 12, 2006, to NEI (ADAMS Accession No. ML061660105), the NRC established the ongoing FAQ process where official agency positions regarding acceptable methods can be documented until they can be included in revisions to RG 1.205 or NEI 04-02. Methods that have not been determined to be acceptable by the NRC staff require additional justification to allow the NRC staff to complete its review of the proposed method.

Section 3.3 of the Fire Ignition Frequency Development report utilizes an approach to apportion transient and cable fire frequencies associated with hot work by using a separate hot work influence factor, which deviates from NUREG/CR-6850; however, a review of LAR Attachment H and the Fire Ignition Frequency Development report indicates that FAQ 12-0064, which defines such an influence factor, is not referenced. Additionally, a review of Table 3-4 indicates that no very high influencing factors (50) were applied and that only low (1) and medium (3) values were applied to the hot work influencing factors. Furthermore, Section 8.4 of the Fire Scenario report notes that an additional 0. 1 adjustment factor has been applied to reduce transient frequencies in Unit 2 fire zone 51 X. In light of these observations, clarify whether influencing factors were developed per the guidance in NUREG/CR 6850 and FAQ 12-0064, and justify why the full range of influencing factors was not implemented. If any frequency-adjustment factors deviating from the guidance presented in NUREG/CR-6850 and FAQ 12-0064 (e.g., the use of 0.1 in Unit 2 fire zone 51 X) are used, justify their use, and evaluate their impact on risk results.

PRA RAI 06-Treatment of Junction Boxes Section 2.4.3.3 of NFPA 805 states that the PRA approach, methods, and data shall be acceptable to the NRC. RG 1.205 identifies NUREG/CR-6850 as documenting a methodology for conducting a FPRA and endorses, with exceptions and clarifications, NEI 04-02, Revision 2, as providing methods acceptable to the staff for adopting an FPP consistent with NFPA-805. In letter dated July 12, 2006, to NEI (ADAMS Accession No. ML061660105), the NRC established the ongoing FAQ process where official agency positions regarding acceptable methods can be documented until they can be included in revisions to RG 1.205 or NEI 04-02. Methods that have not been determined to be acceptable by the NRC staff require additional justification to allow the NRC staff to complete its review of the proposed method.

Section 3.3 of the Fire Ignition Frequency Development report states that the potential for junction box fires is included in the fire ignition frequencies for Unit 1 ; however, this section appears to indicate that junction box fires were not considered for Unit 2. Describe the treatment of junction boxes in the FPRA as ignition sources, and clarify whether this treatment is consistent with guidance in NUREG/CR-6850. If not, evaluate the risk impact of considering junction box fires for Unit 2. Note that draft FAQ 13-0006 (ADAMS Accession No. ML13212A378) offers a complete technical path related to junction boxes.

PRA RAJ 07 - Exclusion of Transient Fire Scenarios The ASME/ANS RA-Sa-2009 standard states that an ignition frequency greater than zero is to be assigned to every plant physical analysis unit (e.g., manholes). Considering guidance for the exclusion of transients provided in FAQ 12-0064 (e.g., manholes are welded shut, space too small to allow personnel access under any conditions, etc.), identify locations where transient fire scenarios are not postulated, and provide justification for their exclusion.

PRA RAI 08 - Sensitive Electronics Section 2.4.3.3 of NFPA 805 states that the PRA approach, methods, and data shall be acceptable to the NRC. RG 1.205 identifies NUREG/CR-6850 as documenting a methodology for conducting a FPRA and endorses, with exceptions and clarifications, NEI 04-02, Revision 2, as providing methods acceptable to the staff for adopting an FPP consistent with NFPA-805. In letter dated July 12, 2006, to NEI (ADAMS Accession No. ML061660105), the NRC established the ongoing FAQ process where official agency positions regarding acceptable methods can be documented until they can be included in revisions to RG 1.205 or NEI 04-02. Methods that have not been determined to be acceptable by the NRC staff or acceptable methods that appear to have been applied differently than described require additional justification to allow the NRC staff to complete its review of the proposed method.

Discuss how sensitive electronics are identified and treated. Include in this discussion a description of the damage criteria that are used for sensitive electronics inside and outside (i.e.,

exposed) of cabinets, and provide justification for these thresholds. Additionally, indicate whether this treatment is consistent with guidance in NUREG/CR-6850. Note that draft FAQ 13-0004 discusses the treatment of sensitive electronics only within an enclosure.

PRA RAI 09 - Main Control Room (MCR) Quantification Section 2.4.3.3 of NFPA 805 states that the PRA approach, methods, and data shall be acceptable to the NRC. RG 1.205 identifies NUREG/CR-6850 as documenting a methodology for conducting a FPRA and endorses, with exceptions and clarifications, NEI 04-02, Revision 2, as providing methods acceptable to the staff for adopting an FPP consistent with NFPA-805. In letter dated July 12, 2006, to NEI (ADAMS Accession No. ML061660105), the NRC established the ongoing FAQ process where official agency positions regarding acceptable methods can be documented until they can be included in revisions to RG 1.205 or NEI 04-02. Methods that have not been determined to be acceptable by the NRC staff or acceptable methods that appear to have been applied differently than described require additional justification to allow the NRC staff to complete its review of the proposed method.

In regard to the treatment of MCR quantification, address the following:

a. According to Supplement 1 to NUREG/CR-6850, back panels housing items such as balance-of-plant and off-site power controls and indicators should be excluded from the main control board (MCB) and treated as general electrical panels. In light of the audit walkdown observation that the MCB forms the front face of a sub-enclosure that is shared with a row of back panels separated by a distance of greater than about 3 feet, provide justification that the back panels are part of the MCB in terms of frequency apportionment.

Additionally, evaluate the impact on risk results of treating these back panels as general electrical panels in terms of frequency apportionment and fire scenario development, including propagation to the MCB panels.

b. Clarify whether NSP values lower than 0.001, the NUREG/CR-6850-recommended lower bound, were utilized in the MCR abandonment analysis.

PRA RAI 10 - Calculation of MCR Abandonment CCDP and CLERP Attachment V indicates that "bounding" abandonment conditional core damage probabilities (CCDPs) of 0.1, 0.2 and 1.0 were utilized rather than detailed human error analyses and that abandonment conditional large early release probabilities (CLERPs) were obtained by multiplying a scenario's corresponding abandonment CCDP by the ratio of the FRANC-calculated CLERP to CCDP; however, there appears to be no justifiable basis to assume that these values are bounding. Provide the following:

a. An identification of the fire areas/compartments that credit MCR abandonment due to loss of habitability and/or loss of control or function.

b. For those areas in which abandonment is credited on loss of control or function, a description of the criteria used for making the determination to abandon, and clarify how these criteria will be addressed by the going-forward fire procedures. In particular, justify the assumption that MCR abandonment due to fires in the cable spreading room is only assumed to occur for HGL scenarios.

c.

Explanation of the range of probabilities for properly shutting down the plant, and discussion of how they were applied in the scenario analysis. In doing so, provide examples over the full range of values utilized, a characterization of the scenarios to which these values are applied, and a summary of how each value is developed. This information should include explanations of how the following scenarios are addressed:

i.

Scenarios where the fire fails few functions aside from MCR habitability and successful shutdown is straightforward.

ii.

Scenarios where the fire could cause some recoverable functional failures or spurious operations that complicate the shutdown but successful shutdown is likely.

iii.

Scenarios where the fire induced failures cause great difficulty for shutdown by failing multiple functions and/or causing complex spurious operations that make successful shutdown unlikely.

d. Explanation of the timing considerations (i.e., total time available, time until cues are reached, manipulation time, and time for decisionmaking) made to characterize scenarios in Part (c). Include in the explanation the basis for any assumptions made about timing.

e. Discussion of how the probability associated with failure to transfer control to the alternate shutdown panel is taken into account in Part (c).

f.

Description of how the feasibility of the operator actions supporting the alternate shutdown pathway was considered by the scenario characterization performed in Part (c).

PRA RAI 11 - Calculation of Delta (L\\)CDF and L\\LERF LAR Attachment W provides the 6COF and 6LERF for the variance from deterministic requirements (VFDRs) and the additional risk of recovery actions for each of the fire areas, but the LAR does not describe, in detail, how 6CDF and 6LERF or the additional risk of recovery actions were calculated. Describe the method(s) used to determine the changes in risk reported in Tables W-6 and W-7 of Attachment W. The description should include:

a. A detailed definition of both the post-transition and compliant plants used to calculate the reported changes in risk and additional risk of recovery actions.

b. A description of how the reported changes in risk and the additional risk of recovery actions were calculated. Include in this description a discussion of PRA modeling mechanisms used to determine the reported changes in risk (e.g., altering the probabilities of basic events and modeled recovery actions). Clarify whether FAQ 08-0054 guidance was used.

c. A discussion of any exceptions to normal modeling mechanisms discussed in (b),

including those cases for which the PRA model lacks sufficient resolution to model the VFDR or those that utilize surrogate basic events or HFEs to estimate/bound the change in risk in lieu of manipulating components or actions directly associated with the VFDR.

d. A description of any modeling manipulations that use data or methods not included in the FPRA peer review.

e. Bases for not modeling VFDRs in the FPRA (e.g., as indicated in LAR Attachment C).

f.

A separate description specific to how the ~CDF and ~LERF and additional risk of recovery actions were calculated for the MCR and any other fire area that results in MCR abandonment due to loss of habitability or credits MCR abandonment on loss of control or function (e.g., cable spreading room).

g. An explanation of the following anomalies identified in Tables W-6 and W-7 of Attachment W:

i.

Note 1 of Tables W-6 and W-7 acknowledges that the additional risk of Recovery Actions (RAs) is "conservatively assumed to be equal to the total delta risk,"

however, Fire Areas 1A and 1C present values that do not conform to this approach.

ii.

Furthermore, a review of Table S-1 of AttachmentS and Table C-1 of Attachment C indicates that risk-reduction modifications (i.e., those not associated with resolution of a VFDR, are credited in the FPRA). Equating the additional risk of RAs to the fire area delta risk is non-conservative for those fire areas that credit risk-reduction modifications because the risk reduction from the non-VFDR-related modifications credited in such a fire area will offset the additional risk of RAs for that same fire area.

iii.

The ~CDF and ~LERF values reported for Fire Areas 1 A and 1 C have opposite signs; however, the basis for this asymmetry is not apparent.

PRA RAJ 12 - Negative ~CDF and ~LERF without Risk-Reduction Modifications A review of LAR Attachment W, Table W-7 indicates that for Fire Areas 2J and 2M, a value of "O.OOE+OO" is reported for both LlCDF and ~LERF. The risk summaries provided for Fire Areas 2J and 2M in LAR Attachment C, Table C-1 state that "[a] negative delta risk results from the summation of cutsets for the system/components made available in the compliant case [that]

exceed the risk associated with the failure of the system," further noting that "this is typically due to conservative estimates of risk associated with operator action dependencies". It is further stated that delta risk values for Fire Areas 2J and 2M are set to zero to preclude the resulting negative delta risk from offsetting the risk associated with other fire areas or scenarios. The risk summary provided for Fire Area 1 C contains a similar discussion; however, non-zero values are reported to give credit to an identified risk-reduction modification. It is unclear how negative delta risk values could be obtained, particularly noting that Fire Areas 2J and 2M do not appear to credit risk-reduction modifications, and to what extent the LlCDF and ~LERF values for other fire areas reported in Tables W-6 and W-7 are systematically underestimated. Explain this modeling anomaly, and evaluate its impact on risk results.

PRA RAI 13 - Calculation of Total Plant COF and LERF The seismic CDF (9.19E-8/yr) reported in LAR Attachment W Table W-1 and used to estimate the total plant CDF appears to be low compared to the seismic CDF estimate (4.6E-5/yr) presented for in a memorandum from NRC staff dated September 2010 providing updated results for Generic Issue 199 (memo titled: "Safety/Risk Assessment Results for Generic Issue 199, Implication for Updated Probabilistic Seismic Hazard Estimates in Central and Eastern United states on Existing Plants"). The total CDF, if higher CDF values for seismic events were used, exceeds RG 1.17 4 risk acceptance guidelines. As a result, provide the basis and corresponding technical justification for the seismic events CDF and LERF presented in the LAR. Additionally, considering deficiencies identified by F&O SF-A 1-01, provide further justification that seismic/fire interactions are adequately evaluated in light of the new seismic hazard data from the United States Geological Survey 2008.

PRA RAI 14 - Implementation Item Impact on Risk Estimates Implementation Item 18 of AttachmentS, Table S-2 does not commit to verifying the validity of the reported risk results following completion of other implementation items that may impact the FPRA. Revise this implementation item to verify the validity of the reported change in risk subsequent to completion of all PRA-credited modifications and implementation items.

PRA RAI 15 - Model Changes and Focused Scope Reviews since Full Peer Review Section 2.4.3.3 of NFPA 805 states that the PRA approach, methods, and data shall be acceptable to the NRC. RG 1.205 identifies NUREG/CR-6850 as documenting a methodology for conducting a FPRA and endorses, with exceptions and clarifications, NEI 04-02, Revision 2, as providing methods acceptable to the staff for adopting an FPP consistent with NFPA-805. In letter dated July 12, 2006, to NEI (ADAMS Accession No. ML061660105), the NRC established the ongoing FAQ process where official agency positions regarding acceptable methods can be documented until they can be included in revisions to RG 1.205 or NEI 04-02. Methods that have not been determined to be acceptable by the NRC staff or acceptable methods that appear to have been applied differently than described require additional justification to allow the NRC staff to complete its review of the proposed method.

Identify any changes made to the lEPRA or FPRA since the last full-scope peer review of each of these PRA models that are consistent with the definition of a "PRA upgrade" in ASME/ANS-RA-Sa-2009, "Standard for Level 1/Large Early Release Frequency for Nuclear Power Plant Applications," as endorsed by RG 1.200. Also, address the following:

a. Clarify why the SRs in LAR Attachment V Table V-1 were found to be not applicable (N/A) by the peer review team. Identify what the supporting requirements are not applicable to, for example, the type of reactor. If there are specific and multiple reasons that the supporting requirements are determined to be N/A, identify the reason for each SR, grouping them as appropriate. In general, SRs that are not deemed applicable to an application require application specific justification; so, all reasons provided should include a discussion of the NFPA 805 application characteristics.

b. If any changes are characterized as a PRA upgrade, indicate if a focused-scope peer review was performed for these changes consistent with the guidance in ASME/ANS-RA-Sa-2009, as endorsed by Regulatory Guide 1.200, and describe any findings from that focused-scope peer review and the resolution of these findings. If a focused-scope peer review has not been performed for changes characterized as a PRA upgrade, describe what actions will be implemented to address this review deficiency.

c.

The NRC staff notes that, several"updates" made to the fire scenario selection and analysis after the peer review appear to qualify as PRA "upgrades", including, but not necessarily limited to:

Replacement of a unreviewed analysis method (i.e., panel factors, with a target-distance-based and time-dependent methodology),

Significant enhancements made to the HGL analysis (e.g., new fire modeling to address secondary combustibles),

Incorporation of new cable spread methodology (i.e., FLASH-CAT),

Significant enhancements made to the MCA, including transition from a two-tiered quantitative screening approach that screened all such scenarios as a very small fraction of the fire CDF at the time of the peer review to one that fully quantifies scenarios and identifies them as significant fire initiating event contributors to both CDF and LERF in LAR Attachment W, and Credit for automatic suppression systems when the original peer-reviewed analysis only credited manual suppression.

Provide justification for why each of these model updates are not considered PRA upgrades in accordance with the PRA Standard ASME/ANS-RA-Sa-2009, as endorsed by RG 1.200 (Revision 2). If considered a PRA upgrade, provide the information requested by Part (b).

PRA RAI 16 - Internal Events PRA (lEPRA) Review against RG 1.200, Revision 2 As documented in LAR Attachment U, the peer review of the lEPRA was performed using the criteria in NEI 00-02, and as a result, a self-assessment is required according to the guidance within RG 1.200 (Revision 2) to demonstrate that the technical adequacy of the PRA is of sufficient quality to support the application. Additional self-assessment subsequent to the July 2002 NEI 00-02 peer review has been performed; however, they do not appear to be sufficient to demonstrate the technical adequacy of the PRA in accordance with the guidance in RG 1.200 (Revision 2). In particular, Focused-scope peer reviews have only been performed on select technical elements of the ASME/ANS PRA standard (i.e., large early release frequency (LERF) evaluation (LE),

human reliability analysis (HRA), internal flooding (IF), and data analysis (DA) as well as supporting requirement (SR) related to common cause failure). Also, the July 2009 LERF focused-scope peer review was not performed against the latest version of the standard as endorsed by RG 1.200, Revision 2.

A December 2005 independent review of the PRA was performed using a dated version of the standard (i.e., ASME RA-Sa-2003 "to guide future PRA enhancement activities"). This "basic assessment" does not appear to qualify as a self-assessment. No formal process or review criteria were cited as being used to judge the adequacy of PRA against SRs. Additionally, the exact scope of SRs and PRA documentation reviewed is unclear and is acknowledged by the review team as being limited.

An October 2007 assessment of the PRA was performed to addresses deficiencies raised by the December 2005 independent review and F&Os from the July 2002 NEI 00-02 peer review; however, this assessment does not appear to follow the self-assessment process outlined in Appendix 8 of RG 1.200. Additionally, the results are not documented in such a manner that it is clear why each requirement is considered to have been met. Although self-identified action items to comply with RG 1.200, Revision 1 are briefly summarized, they are not tied to specific SRs.

Explain how the 2002 peer review and these subsequent focused-scope peer reviews and assessments are consistent with or equivalent to the peer review and self-assessment process in NEI 00-02, Revision 1, as endorsed by RG 1.200, Revision 2, with clarifications and qualifications, for demonstrating the technical adequacy of the lEPRA for the NFPA 805 application.

In addition, provide the deficiencies (or "gaps") identified by the latest gap assessment in a manner analogous to the format in which F&Os are presented and dispositioned in LAR Attachment U, including an assessment of each identified gap's impact on the FPRA.

PRA RAI 17-Internal Events PRA F&Os Section 2.4.3.3 of NFPA 805 states that the PRA approach, methods, and data shall be acceptable to the NRC. RG 1.205 identifies NUREG/CR-6850 as documenting a methodology for conducting a FPRA and endorses, with exceptions and clarifications, NEI 04-02, Revision 2, as providing methods acceptable to the staff for adopting an FPP consistent with FPA-805.

RG 1.200 describes a peer review process utilizing an associated ASME/ANS standard (currently ASME/ANS-RA-Sa-2009) as one acceptable approach for determining the technical adequacy of the PRA once acceptable consensus approaches or models have been established. The primary results of a peer review are the F&Os recorded by the peer review and the subsequent resolution of these F&Os.

Clarify the following dispositions to fire F&Os and SR assessment identified in LAR Attachment U that have the potential to impact the FPRA results and do not appear to be fully resolved:

a. AS-6 (From CEOG 2003 against HR-F1, HR-F2, SC-A3, SC-A6, SY-A2, SY-A22, QU-A 1)

The F&O recommends including credit for Low Pressure Feed from the condensate pumps for certain accident sequences. The F&O disposition explains that in response certain initiating events were combined and recovery actions were added. It is not clear how this modification addresses the F&O. Explain how apparent current lEPRA conservatism associated with modeling Low Pressure Feed affects the FPRA risk estimates.

b. HR-G6 (From PWROG 2011 against HR-G6)

The F&O cites a lack of reasonableness check of dependency analysis results and very low joint HEPs (e.g., between 1E-10 to 1E-16). Section 6.2 of NUREG-1921 addresses the need to consider a minimum value for the joint probability of multiple HFEs.

Considering this guidance, confirm that joint HEP values that appear in PRA cutsets are appropriate.

As previously discussed with Mr. Bill Cross of the licensee's staff, the NRC is requesting responses to the RAI by the following dates (listed in days from the date of this request):

RAI Number RAI Response Due Date FPE RAI 01 -11 60 dats SSA RAI 01 -14 60 dats PROG RAI 01 - 02 60 days FM RAI 02,05 60 days FM RAI 03 90 days FM RAI 01, 04, 06 120 days RR RAI 01 90 days PRA RAI 04, 07, 10, 12, 13, 14, 15 60 days PRA RAI 02, 03, 05, 06, 11, 16, 17 90 days PRA RAI 01, 08, 09 120 days If you have any questions, please contact me at (301) 415-0489.

Enclosure:

Request for Additional Information Docket Nos. 50-335 and 50-389 cc: Distribution via Listserv DISTRIBUTION:

Public LPL2-2 r/f RidsNrrDraApla RidsNrrDraAhpbl Sincerely, Ira/

Audrey L. Klett, Project Manager Plant Licensing Branch 11-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation RidsNrrDorllpl2-2 RidsNrrPMStlucie RidsN rrLABCiayton RidsRgn2MaiiCenter RidsAcrsAcnw _MaiiCTR RidsNrrDraAfpb ADAMS A ccess1on N ML13353A578 o.:

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DATE 12/20/13 12/20/13 11/25/2013 12/20/13 12/26/13 OFFICIAL RECORD COPY