ML14016A097

McGuire Nuclear Station, Units 1 and 2, Supplemental Information for License Amendment Request to Adopt National Fire Protection Association 805 Performance-Based Standard for Fire Protection for Light-Water Reactor Generating Plants

ML14016A097
Person / Time
Site:	McGuire, Mcguire
Issue date:	01/08/2014
From:	Capps S D Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML14016A097 (36)

Text

T DUKEý ENERGY.McGuire Nuclear StationDuke Energy12700 Hagers Ferry RoadHuntersville, NC 28078o: 980.875.4000 January 8, 2014U.S. Nuclear Regulatory Commission Attn: Document Control DeskWashington, D.C. 20555-0001

SUBJECT:

Duke Energy Carolinas (DEC), LLCMcGuire Nuclear Station (MNS), Units 1 and 2Docket Numbers 50-369 and 50-370Supplemental Information for License Amendment Request (LAR) to AdoptNational Fire Protection Association (NFPA) 805 Performance-Based Standardfor Fire Protection for Light-Water Reactor Generating PlantsBy letter dated September 26, 2013, DEC submitted a LAR to adopt the NFPA 805Performance Based Standard for Fire Protection for MNS Units 1 and 2. In an email datedDecember 18, 2013, the NRC requested DEC supplement the LAR to provide information needed to make the LAR complete.

Enclosure 1 provides the supplemental information requested by the NRC. This supplemental information required minor changes to another section of the LAR as described in Enclosure 2.Questions regarding this submittal should be directed to Jeff Robertson, McGuire Regulatory Compliance at (980) 875-4499.

I declare under penalty of perjury that the foregoing is true and correct.

Executed onJanuary 8, 2014.Steven D. CappsEnclosure www.duke-energy.com U.S. Nuclear Regulatory Commission January 8, 2014Page 2cc: Victor M. McCreeRegional Administrator U. S. Nuclear Regulatory Commission, Region IIMarquis One Tower245 Peachtree Center Ave., NE, Suite 1200Atlanta, Georgia 30303-1257 John ZeilerSenior NRC Resident Inspector U. S. Nuclear Regulatory Commission McGuire Nuclear StationJason Paige (Addressee Only)NRC Project ManagerU. S. Nuclear Regulatory Commission 11555 Rockville PikeMail Stop 0-8 G9ARockville, MD 20852-2738 ENCLOSURE 1MNS Response to the NRC December 18, 2013, Request for Supplemental Information for theMNS LAR to Adopt NFPA 805 Performance-Based Standard for Fire Protection December

18. 2013. NRC Reauest for SuDDlemental Information By letter dated September 26, 2013, Duke Energy Carolinas, LLC submitted a licenseamendment request for McGuire, Units 1 and 2. The proposed amendment would adopt a newfire protection licensing basis which complies with the requirements in Title 10 of the Code ofFederal Regulations (10 CFR), Section 50.48(a),

10 CFR 50.48(c),

and the guidance inRegulatory Guide (RG) 1.205, "Risk-Informed, Performance Based Fire Protection for ExistingLight-Water Nuclear Power Plants,"

Revision 1, dated December 2009. The purpose of thisemail is to provide the results of the U.S. Nuclear Regulatory Commission (NRC) staff'sacceptance review of this amendment request.

The acceptance review was performed todetermine if there is sufficient technical information in scope and depth to allow the NRC staff tocomplete its detailed technical review. The acceptance review is also intended to identifywhether the application has any readily apparent information insufficiencies in itscharacterization of the regulatory requirements or the licensing basis of the plant.On December 18, 2013, the NRC staff and Duke Energy held a teleconference to discuss fourdraft questions generated during the acceptance review. At the conclusion of the call, the staffdetermined that one of the four questions is necessary to enable the NRC staff to make anindependent assessment regarding the acceptability of the proposed amendment request.Below is the requested information.

In order to make the application

complete, the NRC staffrequests that Duke Energy supplement the application to address the information requested below by January 8, 2014.1. Table W-1 states that the total fire CDF is 2.70E-5/yr for Unit 1 and 3.87E-5/yr for Unit2. Please summarize the principle difference(s) between the Units that cause thedifferent risk estimates.

Please also provide a Table of the Unit 2 risk-significant scenarios such as that provide in Table W-2 for Unit 1.MNS Response to the December 18, 2013, NRC Request for Supplemental Information The difference between the risk estimates for Unit 1 and Unit 2 in Table W-1 of the MNS NFPA805 LAR dated September 26, 2013, is principally attributable to differences in each Unit's cablerouting versus distinct design differences between the Units.The remaining pages of this Enclosure provide Table W-2-1 and Table W-2-2. Table W-2-2provides the requested Unit 2 risk significant scenarios.

Table W-2-1 provides revisions to theUnit 1 risk significant scenarios provided in the original Table W-2 in the MNS NFPA 805 LARdated September 26, 2013. Table W-2-2 considers the effect of the Liquid Waste RecycleSystem (WL) modification and cabinet treatments from Table S-2 of the LAR. The Unit 1 risksignificant scenarios were revised to reflect these same considerations.

Tables W-2-1 and W-2-2 in this Enclosure replace the entire original Table W-2 in the MNSNFPA 805 LAR dated September 26, 2013.

Duke Energy Carolinas, LLCAttachment W -Fire PRA Insights ATable W-2-1 Unit I Significant Fire Initiating Events (Individually Representing

>1% of Calculated Fire Risk)% CDF / LERFScenario Description Cumulative a Risk insights CCDP IF b CDF % LERF Rank LERFICDF24_C4 MCB 3.6%/3.6%

This scenario is dominated by loss of all 8.48E-01 8.14E-04 1.44E-06 4.5% 3 0.17MC1/MC2/MC10 SSHR sequences.

The fire results in spuriousFire PORV operations on multiple SGs resulting infaulted SGs, and loss of all 3 pressurizer PORVs. Mitigation fails because feed andbleed is unsuccessful with no pressurizer PORVs. This scenario is the #3 LERFcontributor with thermally induced SGTR asthe primary containment failure mode. Someconservative bias may be present if operatoractions to manually close main steam branchlines can reduce the likelihood of a SG beingtreated as faulted.

No credit for such action istaken.19_lxs 11C10 Input'A' 3.4%/7.0%

This scenario is split between RCP seal 6.12E-02 2.21E-05 1.35E-06 4.1% 4 0.16Cabinet Fire LOCA and loss of SSHR sequences.

The fireresults in a loss of MFW, loss of seal injection due to an isolation failure of the FWST or aspurious start of containment sprays, loss ofnormal power supply to both essential busesand emergency power supply to the Aessential bus, loss of CR trip functions, loss ofthermal barrier cooling, loss of the LLI supply,loss of RN train A, failure of 1 pressurizer PORV and failure of MSIV closure.

Randomfailures of the SSF and diesels lead to anRCP seal LOCA scenarios.

Random failuresof the diesels, CA TDP and dieselcompressors lead to a loss of all SSHR. Thisscenario is the #4 LERF contributor withrandom containment failure due to loss of theigniters or a thermally induced SGTR due tothe fire faulting the SGs.Rev 0 Page W-SRev 0Page W-5 Duke Energy Carolinas, LLCAttachment W -Fire PRA Insights' Duke Energy Carolinas, LLC Attachment W -Fire PRA InsightsTable W-2-1 Unit I Significant Fire Initiating Events (Individually Representing

>1% of Calculated Fire Risk)% CDF I LERFScenario Description Cumulative a Risk insights CCDP IF b CDF % LERF Rank LERF/CDF19_17s 11C07 Input'A' 3.4% / 10.3% This scenario behaves the same as scenario 6.12E-02 2.21E-05 1.35E-06 4.1% 5 0.16Cabinet Fire 19_lxs. The scenario is split between RCPseal LOCA and loss of SSHR sequences.

The fire results in a loss of MFW, loss of sealinjection due to an isolation failure of theFWST or a spurious start of containment sprays, loss of normal power supply to bothessential buses and emergency power supplyto the A essential bus, loss of CR tripfunctions, loss of thermal barrier cooling, lossof the LLI supply, loss of RN train A, failure ofI1 pressurizer PORV and failure of MSIVclosure.

Random failures of the SSF ordiesels lead to challenging the pressurizer PORVs for the RCP seal LOCA scenarios.

Random failures of the diesels, CA TDP anddiesel compressors lead to a loss of allSSHR. This scenario is the #5 LERFcontributor with random containment failuredue to loss of the igniters or a thermally induced SGTR due to the fire faulting theSGs.TB1_D 1TC Switchgear 3.1% /13.4% This scenario is split between loss of SSHR 3.02E-03 4.08E-04 1.23E-06 1.9% 7 0.08Fire and RCP seal LOCA sequences.

The fireresults in a loss of the normal power supply toboth essential buses, loss of MFW, loss of theCR trip on RCP-C, and loss of the LLI supplyto RN train B. Random DG failures lead to aloss of all 4kV power. Failure to trip the RCPor RCP seal failures lead to seal LOCAs orTDCAP failure leads to loss of all SSHR.Mitigation is failed due to the loss of power.This scenario is the #7 LERF contributor withrandom containment failure due to loss of theigniters.

Rev 0 Page W-6Rev 0Page W-6 Duke Energy Carolinas, LLCAttachment W -Fire PRA InsightsDuke Energy Carolinas, LLC Attachment W -Fire PRA InsightsTable W-2-1 Unit 1 Significant Fire Initiating Events (Individually Representing

>1% of Calculated Fire Risk)% CDF / LERFScenario Description Cumulative a Risk insights CCDP IF b CDF % LERF Rank LERFICDF9-11_Bl Switchgear 1ETB 2.8% /16.2% This scenario is dominated by RCP seal 4.56E-03 5.34E-04 1.12E-06 1.1% 28 0.05Severe Fire LOCA sequences or stuck open pressurizer relief valves The fire results in spurious startof NV pump B, loss of ETB, spuriouspressurizer PORV operation, and failure ofthe SSF standby makeup pump. Thespurious NV pump start leads to a pressurizer SRV challenge and failure.

Random failuresof A train components (mostly maintenance) lead to a loss of seal cooling and seal failure.The top cutset is the spurious NV pump startsequence which is around 11% of the total.Note: this scenario is influenced by LC andMCC maintenance on train A which is likelyoverestimated with the screening value of 1 E-03.19_J2s 11C02 Input 'B' 2.7% / 18.9% This scenario is dominated by loss of SSHR 4.84E-02 2.21E-05 1.07E-06 11.2% 1 0.56Cabinet Fire sequences.

The fire causes a loss of MFW, aloss of normal power to the essential buses,loss of emergency power to the A essential bus, loss of thermal barrier cooling, loss of LLIfrom RN train B, and loss of several PORVs.Random failures of the diesel compressors and SG alignment lead to a loss of all SSHR.This scenario is the #1 LERF contributor withrandom containment failure due to a loss ofthe igniters.

19_14s 11C04 Input'A' 2.7%/21.5%

This scenario is dominated by RCP seal 4.83E-02 2.21E-05 1.07E-06 3.8% 6 0.19Cabinet Fire LOCAs. The fire causes a spurious operation of the NV pumps, loss of MFW, loss of sealinjection, loss of the VCT, loss of normalpower to the essential buses, loss ofemergency power to A essential bus and lossof thermal barrier cooling.

Random SSFfailures lead to a total loss of seal cooling.This scenario is the #6 LERF contributor withthe fire failing the A train of VX.Rev 0 Page W-7Rev 0Page W-7 Duke Energy Carolinas, LLCAttachment W -Fire PRA Insights "Duke Energy Carolinas, LLC Attachment W -Fire PRA InsightsTable W-2-1 Unit I Significant Fire Initiating Events (Individually Representing

>1% of Calculated Fire Risk)%CDFI LERFScenario Description Cumulative a Risk insights CCDP IF b CDF % LERF Rank LERF/CDF15-17_B4 Swgr 1 ETA 2.7% / 24.2% This scenario is dominated by loss of SSHR 9.84E-03 1.87E-04 1.07E-06 1.8% 8 0.09Severe Fire with sequences and transient induced pressurizer HEAF (1-6) SRV LOCAs. The fire results in loss of ETA,and spurious start of the 1A NV pump.Random failures of train B components leadto core damage. This scenario is the #8LERF contributor with many randomcontainment failure modes contributing.

TB1_C 1TB Switchgear 2.4% /26.6% This scenario is split between loss of SSHR 2.40E-03 4.08E-04 9.80E-07 1.5% 14 0.08Fire and RCP seal LOCA sequences.

The fireresults in a loss of the offsite power supply toboth essential buses, loss of MFW, loss of theCR trip on RCP-B, and loss of the LLI supplyto RN train B. Random DG failures lead to aloss of all 4kV power. Failure to trip the RCPor RCP seal failures lead to LOCAs orTDCAP failure leads to loss of all SSHR.Mitigation is failed due to the loss of power.This scenario ranks #14 in the LERFcontribution with random containment failuredue to loss of the igniters being the dominantcontainment failure modes.TB1_B 1TA Switchgear 2.3% / 29.0% This scenario is split between loss of SSHR 2.31 E-03 4.08E-04 9.44E-07 1.5% 15 0.09Fire and RCP seal LOCA sequences.

The fireresults in a loss of the offsite power supply toboth essential buses, loss of MFW, loss of theCR trip on RCP-A, and loss of the LLI supplyto RN train B. Random DG failures lead to aloss of all 4kV power. Failure to trip the RCPor RCP seal failures lead to LOCAs orTDCAP failure leads to loss of all SSHR.Mitigation is failed due to the loss of power.This scenario ranks #15 in the LERFcontribution with random containment failuredue to loss of the igniters being the dominantcontainment failure modes.Rev 0 Page W-8Rev 0Page W-8 Duke Energy Carolinas, LLCAttachment W -Fire PRA InsightsDueEeg aoias L tahetW iePAIsgtTable W-2-1 Unit I Significant Fire Initiating Events (Individually Representing

>1% of Calculated Fire Risk)% CDF / LERFScenario Description Cumulative a Risk insights CCDP IF b CDF % LERF Rank LERF/CDFTB1_E 1TD Switchgear 2.3% /31.3% This scenario is split between loss of SSHR 2.31 E-03 4.08E-04 9.44E-07 1.5% 16 0.09Fire and RCP seal LOCA sequences.

The fireresults in a loss of the offsite power supply toboth essential buses, loss of MFW, loss of theCR trip on RCP-D, and loss of the LLI supplyto RN train B. Random DG failures lead to aloss of all 4kV power. Failure to trip the RCPor RCP seal failures lead to LOCAs orTDCAP failure leads to loss of all SSHR.Mitigation is failed due to the loss of power.This scenario ranks #16 in the LERFcontribution with random containment failuredue to loss of the igniters being the dominantcontainment failure modes.19_J5s 11C05 Input 'B' 2.3% / 33.7% This scenario is dominated by RCP seal 4.24E-02 2.21 E-05 9.38E-07 1.0% 30 0.06Cabinet Fire LOCAs sequences.

The fire results in a lossof MFW, loss of seal injection due to anisolation failure of the FWST and failure of theVCT, loss of normal power to the essential buses, loss of CR trip function and loss ofthermal barrier cooling.

Random failures ofthe SSF lead to a loss of all seal cooling.15-17_Cl Load Center 2.2%/35.8%

This scenario is dominated by RCP seal 2.OOE-02 8.16E-05 8.64E-07 1.1% 25 0.071 ELXA Severe LOCAs. The fire results in failure of ETA, theFire SSF SMUP, and letdown isolation.

Randomfailures of train B (RN and KC) results in lossof seal cooling and failure to mitigate the sealLOCA.Rev 0 Page W-9Rev 0Page W-9 Duke Energy Carolinas, LLCAttachment W -Fire PRA Insights

'Due neg Caoins LL tahetW-iePAIsgt Table W-2-1 Unit 1 Significant Fire Initiating Events (Individually Representing

>1% of Calculated Fire Risk)% CDFI LERFScenario Description Cumulative a Risk insights CCDP IF b CDF % LERF Rank LERF/CDFSRVB 1SLXA/B/C/D 2.1% / 37.9% This scenario is split between seal LOCAs 4.31 E-03 1.97E-04 8.48E-07 1.5% 17 0.09Load Center and total loss of SSHR sequences.

The fireSevere Fire results in a loss of offsite power to bothessential switchgear, loss of MFW, loss of theCR RCP trip on RCP-C, and a loss of the LLIsupply to RN train B. Random failures of theDGs lead to an SBO condition.

VariousTDCAP failures (mostly failure to locallythrottle following a loss of IA) or SSF SMUPfailures lead to core damage.21_Bi MCC 1/2EMXA 2.1% /40.0% This scenario is dominated by RCP seal 7.97E-03 5.31E-04 8.46E-07 0.7% 39 0.04Severe Fire LOCA sequences.

The fire results in FWSTdraining or isolation (FW27A),

loss of theVCT, and loss of thermal barrier cooling.Random failure of the SSF results in total lossof seal cooling.

Failure to trip the RCP leadsto the large seal LOCA where other sizes mayoccur if the RCPs are tripped.

Mitigation failsdue to loss of the FWST or randomrecirculation failure.TB1_0 Turbine Generator 2.1%/42.1%

This scenario is split between loss of SSHR 1.54E-03 3.18E-03 8.33E-07 1.5% 19 0.09Hydrogen Fire and RCP seal LOCA sequences.

The fireresults in a loss of the offsite power supply toboth essential buses, loss of MFW, and lossof the LLI supply to RN train B. Random DGfailure leads to loss of all power. Randomfailure of the SSF leads to seal LOCA orrandom failure of the TDCAP leads to loss ofSSHR. Mitigation fails due to the loss ofpower.Rev 0 Page W-1ORev 0Page W-10 Duke Energy Carolinas, LLCAttachment W -Fire PRA InsightsDueEeryCrliaLC tahmn Fr R IsgtTable W-2-1 Unit I Significant Fire Initiating Events (Individually Representing

>1% of Calculated Fire Risk)%CDFI LERFScenario Description Cumulative a Risk insights CCDP IF b CDF % LERF Rank LERF/CDF15-17_B5 Swgr 1ETA 2.0% /44.1% This scenario is dominated by transient 1.08E-02 1.60E-04 7.99E-07 1.4% 20 0.09Severe Fire with induced LOCAs and loss of SSHRHEAF (7-11) sequences.

The fire results in loss of ETA,loss of the normal power supply to ETB, andspurious pressurizer spray or NV pump start.Failure to mitigate excess injection flow leadsto a stuck open pressurizer SRV. Randomfailures of CA train B and the TDCAP lead toloss of SSHR. Mitigation fails due to randomfailures affecting sump recirculation.

19_K4s 11C12 Input NE 2.0% /46.1% This scenario is dominated by a loss of SSHR 3.57E-02 2.21E-05 7.89E-07 5.2% 2 0.35Cabinet Fire sequences.

The fire results in a loss of MFW,loss of seal injection due to an isolation failureof the FWST and failure of the VCT, loss ofnormal power to the essential buses, loss ofemergency power to the A essential bus, lossof thermal banier cooling, loss of the LLIsupply to RN train B, and spurious PORVoperations on multiple SGs. Random failuresof the diesels and RN supply result in a lossof all SSHR. This scenario is the #2 LERFcontributor with the fire failing A train VX.15-17_B6 Swgr 1 ETA 1.8% /47.9% This scenario is split between transient 8.37E-03 1.87E-04 7.23E-07 1.3% 22 0.10Severe Fire with induced stuck open pressurizer SRV, RCPHEAF (12-17) seal LOCAs, and loss of SSHR sequences.

The fire results in failure of ETA, spuriousstart of NV pump A, and inability to trip RCPsA and C from the CR. The spurious NV pumpstart leads to a pressurizer SRV challenge and failure.

Random failures of B traincomponents lead to failure to mitigate thetransient.

Rev 0 Page W-11Rev 0Page W-11 Duke Energy Carolinas, LLCAttachment W -Fire PRA InsightsDueEeryCrliaLC tahmn Fr R IsgtTable W-2-1 Unit 1 Significant Fire Initiating Events (Individually Representing

>1% of Calculated Fire Risk)% CDF I LERFScenario Description Cumulative a Risk insights CCDP IF b CDF % LERF Rank LERF/CDFTB1_K 1LXF Load Center 1.7% / 49.6% This scenario is split between loss of SSHR 3.82E-03 1.79E-04 6.85E-07 1.2% 24 0.09Fire and RCP seal LOCA sequences with loss ofSSHR being a somewhat larger contributor.

The fire results in a loss of the normal powersupply to both essential buses, loss of MFW,and loss of the LLI supply to RN train B.Random failures of the DGs or their supportsystems results in a loss of all power.Random failures of the SSF or the TDCAPlead to core damage.TB1_L 1 LXG Load 1.6% / 51.1% This scenario is dominated by reactor coolant 3.52E-03 1.79E-04 6.31 E-07 1.0% 29 0.09Center Fire pump seal LOCAs. The fire results in a lossof offsite power to both trains of the essential switchgear, the SSF standby makeup pump,CR trip of RCP-D, and the LLI supply to trainB of RN. Random DG failures lead to a sealLOCA with no available mitigation.

Loss ofSSHR sequences due to TDCAP failures alsomake a small contribution.

13_SA KXA Static 1.5% /52.6% This scenario is dominated by RCP seal 1.45E-01 4.42E-05 6.04E-07 1.1% 26 0.10Inverter Fire LOCAs; loss of SSHR sequences docontribute.

The fire results in loss of power to1 ETB, normal power to 1 ETA, the TDCAP,thermal barrier cooling, suction sources forthe NV pumps, and sump recirculation.

Lossof the SSF leads to seal LOCAs; randomfailures of the available CA equipment lead toloss of SSHR. Mitigation fails at sumprecirculation.

21_Y1 Transient Fire at 1.5% / 54.1% This scenario is dominated by loss of all 2.27E-01 2.62E-06 5.93E-07 1.8% 9 0.16Risers near HH- SSHR sequences.

The fire results in spurious54 PORV operations on multiple SGs resulting infaulted SGs, and loss of sump recirculation.

Mitigation fails because of the loss of sumprecirculation.

This scenario is the #9 LERFcontributor with spurious VX and thermally induced SGTR as the primary containment failure modes.Rev 0 Page W-12Rev 0Page W-12 Duke Energy Carolinas, LLCAttachment W -Fire PRA InsightsDueEeg aoias L tahetW iePAIsgtTable W-2-1 Unit 1 Significant Fire Initiating Events (Individually Representing

>1% of Calculated Fire Risk)%CDFI LERFScenario Description Cumulative a Risk insights CCDP IF b CDF % LERF Rank LERFICDF1911s 11COl Input'A' 1.4% / 55.5% This scenario is split between loss of all 2.56E-02 2.21E-05 5.67E-07 1.6% 13 0.15Cabinet Fire SSHR and RCP seal LOCAs. The fire resultsin a loss of MFW, loss of seal injection due toFWST draining or isolation, loss of VCT, lossof normal power to the essential buses andloss of emergency power to the A essential bus, loss of LLI to RN train B and loss ofthermal barrier cooling.

Random failures ofthe SSF results in total loss of seal cooling.Failure to trip the RCP leads to the large sealLOCA where other sizes may occur if theRCPs are tripped.

This scenario is the #13LERF contributor with the fire failing the A VXtrain.TB1_J 1LXE Load Center 1.4% / 56.9% This scenario is split between loss of SSHR 3.16E-03 1.79E-04 5.66E-07 0.9% 31 0.08Fire and RCP seal LOCA sequences.

The fireresults in a loss of the offsite power supply toboth essential buses, loss of MFW, loss of theCR trip on RCPs C and D, and loss of the LLIsupply to RN train B. Random DG failureslead to a loss of all 4kV power. Failure to tripthe RCP or RCP seal failures lead to LOCAsor TDCAP failure leads to loss of all SSHR.Mitigation is failed due to the loss of power.Rev 0 Page W-13Rev 0Page W-13 Duke Energy Carolinas, LLCAttachment W -Fire PRA Insights

'Duke Energy Carolinas, LLC Attachment W -Fire PRA InsightsTable W-2-1 Unit 1 Significant Fire Initiating Events (Individually Representing

>1% of Calculated Fire Risk)% CDF / LERFScenario Description Cumulative a Risk insights CCDP IF b CDF % LERF Rank LERFICDF13_Y1 Transient Fire 1.3% / 58.3% This scenario is a mix of RCP seal LOCA and 1.55E-01 3.42E-06 5.32E-07 1.7% 12 0.17near EE-56 loss of all SSHR sequences.

The fire resultsin loss of normal power to both essential busses, FWST draining, loss of the VCT, andloss of thermal barrier cooling.

Randomfailure of the SSF results in total loss of sealcooling.

Failure to trip the RCP leads to thelarge seal LOCA where other sizes may occurif the RCPs are tripped.

Random failure ofthe TDCAP leads to loss of SSHR. Failure toterminate the FWST drain leads to loss of theECCS pumps and mitigation capability.

Thisscenario is the #12 LERF contributor withspurious VX and random containment failureas the primary containment failure modes.20_J4s 21C11 Input 'B' 1.2% / 59.4% This scenario is split between RCP seal 2.11E-02 2.21E-05 4.65E-07 1.3% 23 0.15Cabinet Fire LOCA and loss of SSHR sequences.

The fireresults in a loss of LLI supply to RN, loss ofSNSWP to RN train A and prevents RN frombeing recovered from the opposite unit. Theloss of RN causes the operators to start theSSF and random failures of the SSF lead to aloss of seal cooling or failing to throttle the CATDP leads to overfilling the SGs.TB1_G 1LXB Load Center 1.2% / 60.6% This scenario is split between loss of SSHR 2.58E-03 1.79E-04 4.63E-07 0.7% 35 0.08Fire and RCP seal LOCA sequences.

The fireresults in a loss of the offsite power supply toboth essential buses, loss of MFW, loss of theCR trip of multiple RCPs, and loss of the LLIsupply to RN train B. Random DG failureslead to a loss of all 4kV power. Failure to tripthe RCP or RCP seal failures following SSFSMUP failure lead to seal LOCAs. TDCAPfailure leads to loss of all SSHR. Mitigation isfailed due to the loss of power.Rev 0Page W-14 Duke Energy Carolinas, LLCAttachment W -Fire PRA InsightsTable W-2-1 Unit I Significant Fire Initiating Events (Individually Representing

>1% of Calculated Fire Risk)%CDF/ LERFScenario Description Cumulative a Risk insights CCDP IF b CDF % LERF Rank LERFICDFTB1_F 1LXA Load Center 1.1% /61.7% This scenario is split between loss of SSHR 2.53E-03 1.79E-04 4.53E-07 0.7% 36 0.08Fire and RCP seal LOCA sequences.

The fireresults in a loss of the offsite power supply toboth essential buses, loss of MFW, loss of theCR trip of multiple RCPs, and loss of the LLIsupply to RN train B. DG failures lead to aloss of all 4kV power. Failure to trip the RCPor RCP seal failures following SSF SMUPfailure lead to seal LOCAs. TDCAP failureleads to loss of all SSHR. Mitigation is faileddue to the loss of power.19_F Status Light 1.1% / 62.8% This scenario is dominated by loss of all 2.02E-02 2.21 E-05 4.47E-07 1.7% 10 0.20Cabinet Fire SSHR sequences.

The fire results in a loss ofMFW, loss of normal power to the essential buses, loss of thermal barrier cooling, loss ofthe LLI to the B RN train and failures of thevalves needed to swap to sump recirculation.

Random failures of the diesel compressors and diesels lead to a loss of all SSHR. Thisscenario is the #10 LERF contributor with thefire causing a spurious failure of the A VXtrain.19_G Annunciator 1.1% / 63.9% This scenario behaves the same as scenario 2.02E-02 2.21 E-05 4.47E-07 1.7% 11 0.20Cabinet Fire 19_F. This scenario is dominated by loss ofall SSHR sequences.

The fire results in aloss of MFW, normal power to the essential buses, loss of thermal barrier cooling, loss ofthe LLI to the B RN train and failures of thevalves needed to swap to sump recirculation.

Random failures of the diesel compressors and diesels lead to a loss of all SSHR. Thisscenario is the #11 LERF contributor with thefire causing a spurious failure of the A VXtrain.Rev 0 Page W-15Rev 0Page W-15 Duke Energy Carolinas, LLCAttachment W -Fire PRA InsightsDuke Energy Carolinas, LLC Attachment W -Fire PRA InsightsTable W-2-1 Unit I Significant Fire Initiating Events (Individually Representing

>1% of Calculated Fire Risk)% CDF I LERFScenario Description Cumulative a Risk insights CCDP IF b CDF % LERF Rank LERFICDF2_DA Aux Shutdown 1.0% /64.9% This scenario is dominated by RCP seal 3.51 E-02 1.11E-05 3.88E-07 0.3% 67 0.04Panel Fire (A LOCAs and stuck open pressurizer reliefTrain) valves. The fire results in loss of RN,spurious operation of the NV pumps. Failureto recover RN from RV and Unit 2 results incomplete loss of RN. SSF failure leads to aseal LOCA. Mitigation fails due to the loss ofRN.Notes:a. Individual contribution followed by cumulative contribution.

b. Ignition Frequency (IF) includes severity factor and probability of non-suppression, where applicable.

Rev 0 Page W-16Rev 0Page W-16 Duke Energy Carolinas, LLCAttachment W -Fire PRA InsightsDuke Energy Carolinas, LLC Attachment W -Fire PRA InsightsTable W-2-2 Unit 2 Significant Fire Initiating Events (Individually Representing

>1% of Calculated Fire Risk)% CDF I LERFScenario Description Cumulative a Risk insights CCDP IF b CDF % LERF Rank LERF/CDF20_J5s 21C05 Input 'B' 7.4% /7.4% This scenario is dominated by loss of SSHR 2.26E-01 2.21 E-05 3.84E-06 4.3% 4 0.06Severe Fire sequences.

The fire results in a loss of MFW,loss of seal injection due to an isolation failureof the FWST and failure of the VCT, loss ofRN assured source, loss of the MD CAP, lossof the PORV block valves and loss of thermalbarrier cooling.

Random failures of the dieselcompressors and failure to throttle the TDCAP result in a total loss of SSHR. Thisscenario is the #4 LERF contributor withrandom failures of the hydrogen igniters.

16-18_R RCP-2C Breaker 7.1% /14.5% This scenario is dominated by RCP seal 4.26E-02 1.26E-04 3.70E-06 2.4% 9 0.03Fire LOCA sequences.

The fire results in a loss ofMFW, loss of the SSF SMUP, loss of ETA,loss of CR trip of 1 or more RCPs and thefailure of one pressurizer PORV. Randomfailures of the B train equipment and failure toisolate the SSF letdown line lead to a loss ofseal cooling.

This scenario is the #9 LERFcontributor with random failures of thehydrogen igniters.

20_F Status Light 4.6% /19.1% This scenario is split between RCP seal 1.21E-01 2.21E-05 2.38E-06 3.5% 7 0.07Cabinet Fire LOCA, cycling relief valves, and stuck openPORV sequences.

The fire results in a loss ofMFW, loss of seal injection due to failure ofthe VCT and the fire diverting the FWSTinventory, loss of normal power to theessential buses, loss of ETA, loss of thermalbarrier cooling, loss of the LLI to RN andspurious actuation of the SG PORVs.Combinations of random and fire inducedfailures lead to the other functional failures.

This scenario is the #7 LERF contributor withthe fire failing the VQ line.Rev 0 Page W-17Rev 0Page W-17 Duke Energy Carolinas, LLCAttachment W -Fire PRA InsightsDuke Energy Carolinas, LLC Attachment W -Fire PRA InsightsTable W-2-2 Unit 2 Significant Fire Initiating Events (Individually Representing

>1% of Calculated Fire Risk)% CDF I LERFScenario Description Cumulative a Risk insights CCDP IF b CDF % LERF Rank LERFICDF20_J4s 21C11 lnput'B' 4.3%/23.4%

This scenario is split between RCP seal 1.01E-01 2.21E-05 2.24E-06 8.1% 1 0.18Cabinet Fire LOCA and loss of SSHR sequences.

The fireresults in a loss of ETA, a loss of thermalbarrier cooling, a loss of LLI supply to RN,loss of SNSWP to RN train A and preventsRN from being recovered from the oppositeunit. Random failures on train B lead to lossof seal cooling or CAMDP causing theoperators to start the SSF and randomfailures of the SSF lead to a loss of sealcooling or failing to throttle the CA TDP leadsto overfilling the SGs. This scenario is the #1LERF contributor dominated by randomcontainment failure following loss of theigniters with a small contribution from firefailing the VQ line.14_Y5 Transient Fire -2.8% /26.2% This scenario is dominated by loss of all 3.50E-01 4.16E-06 1.46E-06 3.4% 8 0.12Cable Tray SSHR sequences.

The fire results in a loss ofAccess East MFW, loss of seal injection due to an isolation failure of the FWST and failure of the VCT,loss of ETB, spurious operation of the SGPORVs and failure of all the pressurizer PORVs. Fire induced failures in the CA andSV Systems lead to a loss of all SSHR. Thisscenario is the #8 LERF contributor dominated by thermally induced SGTR.Rev 0 Page W-18Rev 0Page W-18 Duke Energy Carolinas, LLCAttachment W -Fire PRA InsightsTable W-2-2 Unit 2 Significant Fire Initiating Events (Individually Representing

>1% of Calculated Fire Risk)% CDF / LERFScenario Description Cumulative a Risk insights CCDP IF b CDF % LERF Rank LERF/CDF24_C4 MCB 2.8% /29.0% This scenario is dominated by loss of all 8.45E-01 8.14E-04 1.44E-06 5.1% 2 0.18MC1/MC2/MC10 SSHR sequences.

The fire results in spuriousFire PORV operations on multiple SGs resulting infaulted SGs, valve impacts in the CA System,and loss of all 3 pressurizer PORVs.Mitigation fails because feed and bleed isunsuccessful with no pressurizer PORVs.This scenario is the #2 LERF contributor withthermally induced SGTR as the primarycontainment failure mode. Someconservative bias may be present if operatoractions to manually close main steam branchlines can reduce the likelihood of a SG beingtreated as faulted.

No credit for such action istaken.20_14s 21C04 Input 'A' 2.6% / 31.5% This scenario is split between loss of SSHR 6.00E-02 2.21 E-05 1.33E-06 4.0% 5 0.15Cabinet Fire and RCP seal LOCA sequences.

The firecauses a loss of MFW, loss of seal injection due to a failure of the NV supply, loss of ETA,loss of normal power to the B essential bus,loss of CA supply from the RN assuredsource, loss of CR trip function to one or moreRCPs and loss of thermal barrier cooling.Random or fire induced failures lead to loss ofall seal cooling or loss of SSHR. Mitigation fails due to random failures in the ECCS trainB and its support systems.

This scenario isthe #5 LERF contributor from a combination of thermally induced SGTR and randomcontainment failure due to loss of the igniters.

20_11s 21C01 Input'A' 2.2%/33.7%

This scenario behaves similarly to scenario 5.26E-02 2.21E-05 1.16E-06 3.5% 6 0.15Cabinet Fire 20_14s. Scenario 14s also has impacts to thesump isolation valves causing a slightly higherCCDP fir that scenario.

This scenario is the#6 LERF contributor from a combination ofthermally induced SGTR and randomcontainment failure due to loss of the igniters.

Rev 0 Page W-19Rev 0Page W-19 Duke Energy Carolinas, LLCAttachment W -Fire PRA Insights

'Duke Energy Carolinas, LLC Attachment W -Fire PRA InsightsTable W-2-2 Unit 2 Significant Fire Initiating Events (Individually Representing

>1% of Calculated Fire Risk)% CDF I LERFScenario Description Cumulative a Risk insights CCDP IF b CDF % LERF Rank LERF/CDF10-12_Bl Switchgear 2ETB 2.1% /35.9% This scenario is dominated by stuck open and 4.44E-03 5.34E-04 1.10E-06 0.8% 28 0.04Severe Fire cycling pressurizer relief valve sequences.

The fire results in spurious start of NV pumpB, loss of ETB, spurious pressurizer PORVoperation, and failure of the SSF standbymakeup pump. The spurious NV pump startleads to a pressurizer SRV challenge andfailure.

Random failures of CA train A andother independent failures leading to loss offeed and bleed lead to core damage.20_J8s 21C08 Input 'B' 2.1%/37.9%

This scenario is dominated by RCP seal 4.89E-02 2.21E-05 1.08E-06 2.4% 10 0.11Cabinet Fire LOCAs. The fire results in failure of ETB andloss of the normal power source to ETA.Random failures of train A, the SSF andactions to trip the RCPs lead to seal LOCAs.Mitigation fails as a consequence of thefailures that lead to the loss of train A sealcooling.

This scenario ranks as #10 in LERFwith containment failures due to loss of theigniters as the primary containment failuremode.Rev 0 Page W-20Rev 0Page W-20 Duke Energy Carolinas, LLCAttachment W -Fire PRA InsightsDuke Energy Carolinas, LLC Attachment W -Fire PRA InsightsTable W-2-2 Unit 2 Significant Fire Initiating Events (Individually Representing

>1% of Calculated Fire Risk)% CDF ! LERFScenario Description Cumulative a Risk insights CCDP IF b CDF % LERF Rank LERFICDF20_lxs 21C10 Input 'A' 1.9% /39.9% This scenario is split between RCP seal 4.53E-02 2.21E-05 1.OOE-06 4.7% 3 0.23Cabinet Fire LOCA and loss of SSHR sequences.

The fireresults in a loss of MFW, loss of seal injection due to an isolation failure of the FWST or aspurious start of containment sprays, loss ofnormal power supply to both essential busesand emergency power supply to the Aessential bus, loss of CR trip functions, loss ofthermal barrier cooling, loss of the LLI supply,loss of RN train A, failure of 1 pressurizer PORV and failure of MSIV closure.

Randomfailures lead to loss of seal cooling or SSHRand inability to mitigate the transient.

Thisscenario is the #3 LERF contributor withrandom containment failure due to loss of theigniters or a thermally induced SGTR due tothe fire faulting the SGs.16-18_B6 Swgr 2ETA 1.9% /41.8% This scenario is dominated by RCP seal 1.14E-02 1.87E-04 9.89E-07 1.0% 22 0.05Severe Fire with LOCAs with a contribution from stuck openHEAF (12-17) PZR relief valves. The fire results in failure ofETA, spurious start of NV pump A, andinability to trip RCPs A and C from the CR.The spurious NV pump start leads to apressurizer SRV challenge and failure.Random failures of B train components leadto loss of seal cooling and failure to mitigatethe transient.

Rev 0 Page W-21Rev 0Page W-21 Duke Energy Carolinas, LLCAttachment W -Fire PRA InsightsDuke Energy Carolinas, LLC Attachment W -Fire PRA InsightsTable W-2-2 Unit 2 Significant Fire Initiating Events (Individually Representing

>1% of Calculated Fire Risk)% CDF I LERFScenario Description Cumulative a Risk insights CCDP IF b CDF % LERF Rank LERFICDF13_SX SKX Static 1.8%/43.6%

This scenario is dominated by RCP seal 9.15E-02 4.42E-05 9.47E-07 1.1% 20 0.06Inverter Fire LOCA with a contribution from stuck openPZR relief valves. The fire results in failure ofETB and loss of the normal power source toETA, high pressure recirculation, and all sealcooling.

Random failures of the SSF andactions to trip the RCPs lead to seal LOCAs.Spurious valve operation leads touncontrolled injection challenging the PZRrelief valves. Mitigation fails as aconsequence of the loss of HPR.TB2_D 2TC Switchgear 1.8% /45.4% This scenario is split between loss of SSHR 2.29E-03 4.08E-04 9.34E-07 1.8% 14 0.09Fire and RCP seal LOCA sequences.

The fireresults in a loss of the normal power supply toboth essential buses, loss of MFW, loss of theCR trip on RCP-C, and loss of the LLI supplyto RN train B. Random DG failures lead to aloss of all 4kV power. Failure to trip the RCPor RCP seal failures lead to seal LOCAs orTDCAP failure leads to loss of all SSHR.Mitigation is failed due to the loss of power.This scenario is the #14 LERF contributor withrandom containment failure due to loss of theigniters.

16-18_Cl Load Center 1.6% /47.0% This scenario is dominated by RCP seal 1.98E-02 8.16E-05 8.52E-07 0.5% 44 0.032ELXA Severe LOCAs and loss of SSHR. The fire results inFire failure of ETA, the SSF SMUP, and letdownisolation.

Random failures of train B (RN andKC) results in loss of seal cooling and failureto mitigate the seal LOCA. Random and firefailures affecting CA lead to loss of SSHR andmitigation capability.

Rev 0 Page W-22Rev 0Page W-22 Duke Energy Carolinas, LLCAttachment W -Fire PRA InsightsTable W-2-2 Unit 2 Significant Fire Initiating Events (Individually Representing

>1% of Calculated Fire Risk)%CDF/ LERFScenario Description Cumulative a Risk insights CCDP IF b CDF % LERF Rank LERF/CDF16-18_B4 Swgr 2ETA 1.6% /48.6% This scenario is dominated by RCP seal 9.77E-03 1.87E-04 8.44E-07 0.6% 37 0.04Severe Fire with LOCAs and loss of SSHR. The fire results inHEAF (1-6) failure of ETA, the SSF SMUP, and letdownisolation.

Random failures of train B (RN andKC) results in loss of seal cooling and failureto mitigate the seal LOCA. Random and firefailures affecting CA lead to loss of SSHR andmitigation capability.

20_17s 21C07 Input 'A' 1.6% / 50.3% This scenario is split between RCP seal 3.80E-02 2.21E-05 8.40E-07 1.9% 12 0.11Cabinet Fire LOCA and loss of SSHR sequences.

The fireresults in a loss of MFW or a spurious start ofcontainment sprays, loss of normal powersupply to both essential buses andemergency power supply to the A essential bus, loss of CR trip functions, loss of thermalbarrier cooling, loss of the LLI supply, loss ofRN train A, failure of 1 pressurizer PORV andfailure of MSIV closure.

Random failures ofthe SSF and diesels lead to an RCP sealLOCA scenarios.

Random failures of thediesels, CA, TDP and diesel compressors lead to a loss of all SSHR. This scenario isthe #12 LERF contributor with randomcontainment failure due to loss of the ignitersor a thermally induced SGTR.21_BI MCC 1/2EMXA 1.6% / 51.9% This scenario is dominated by RCP seal 7.86E-03 5.31 E-04 8.34E-07 0.7% 35 0.04Severe Fire LOCA sequences.

The fire results in FWSTdraining or isolation (FW27A),

loss of theVCT, and loss of thermal barrier cooling.Random failure of the SSF results in total lossof seal cooling.

Failure to trip the RCP leadsto the large seal LOCA where other sizes mayoccur if the RCPs are tripped.

Mitigation failsdue to loss of the FWST or randomrecirculation failure.Rev 0 Page W-23Rev 0Page W-23 Duke Energy Carolinas, LLCAttachment W -Fire PRA InsightsTable W-2-2 Unit 2 Significant Fire Initiating Events (Individually Representing

>1% of Calculated Fire Risk)% CDF / LERFScenario Description Cumulative a Risk insights CCDP IF b CDF % LERF Rank LERF/CDF13_CD Battery Charger 1.6% / 53.5% This scenario is dominated by RCP seal 3.23E-02 1.29E-04 8.33E-07 0.4% 52 0.03EVCD Severe Fire LOCAs with some contribution from stuckopen pressurizer relief valve sequences.

Thefire results in failure of ETB, high pressurerecirculation, spurious NV pump starts,pressurizer heater operation, and loss ofnormal seal injection.

Random failures of theSSF and actions to trip the RCPs lead to sealLOCAs. Random relief valve failures canlead to relief valve LOCAs. Mitigation fails asa consequence of the loss of HPR.16-18_B5 Swgr 2ETA 1.6% /55.0% This scenario is dominated by RCP seal 1.10E-02 1.60E-04 8.13E-07 0.9% 26 0.05Severe Fire with LOCAs with some contribution from transient HEAF (7-11) induced LOCAs. The fire results in loss ofETA, loss of the normal power supply to ETB,and spurious pressurizer spray or NV pumpstart. Random failure to mitigate excessinjection flow leads to a stuck openpressurizer SRV. Random failures of train Band the SSF leads to loss of seal cooling.Mitigation fails due to random failuresaffecting sump recirculation.

TB2_C 2TB Switchgear 1.4% /56.5% This scenario is split between loss of SSHR 1.81E-03 4.08E-04 7.39E-07 1.5% 15 0.10Fire and RCP seal LOCA sequences.

The fireresults in a loss of the normal power supply toboth essential buses, loss of MFW, loss of theCR trip on RCP-B, and loss of the LLI supplyto RN train B. Random DG failures lead to aloss of all 4kV power. Failure to trip the RCPor RCP seal failures lead to LOCAs orTDCAP failure leads to loss of all SSHR.Mitigation is failed due to the loss of power.This scenario ranks #15 in the LERFcontribution with random containment failuredue to loss of the igniters.

Rev 0Page W-24 Duke Energy Carolinas, LLCAttachment W -Fire PRA Insights

-Duke Energy Carolinas, LLC Attachment W -Fire PRA InsightsTable W-2-2 Unit 2 Significant Fire Initiating Events (Individually Representing

>1% of Calculated Fire Risk)% CDF b LERFScenario Description Cumulative a Risk insights CCDP IF b CDF % LERF Rank LERF/CDFTB2_B 2TA Switchgear 1.3% / 57.7% This scenario is split between loss of SSHR 1.76E-03 3.77E-04 6.64E-07 1.4% 18 0.10Fire and RCP seal LOCA sequences.

The fireresults in a loss of the normal power supply toboth essential buses, loss of MFW, loss of theCR trip on RCP-A, and loss of the LLI supplyto RN train B. Random DG failures lead to aloss of all 4kV power. Failure to trip the RCPor RCP seal failures lead to LOCAs orTDCAP failure leads to loss of all SSHR.Mitigation is failed due to the loss of power.This scenario ranks #18 in the LERFcontribution with random containment failuredue to loss of the igniters.

TB2_E 2TD Switchgear 1.3% /59.0% This scenario is split between loss of SSHR 1.76E-03 3.77E-04 6.64E-07 1.4% 19 0.10Fire and RCP seal LOCA sequences.

The fireresults in a loss of the normal power supply toboth essential buses, loss of MFW, loss of theCR trip on RCP-D, and loss of the LLI supplyto RN train B. Random DG failures lead to aloss of all 4kV power. Failure to trip the RCPor RCP seal failures lead to LOCAs orTDCAP failure leads to loss of all SSHR.Mitigation is failed due to the loss of power.This scenario ranks #19 in the LERFcontribution with random containment failuredue to loss of the igniters.

Rev 0 Page W-25Rev 0Page W-25 Duke Energy Carolinas, LLCAttachment W -Fire PRA Insights "Table W-2-2 Unit 2 Significant Fire Initiating Events (Individually Representing

>1% of Calculated Fire Risk)Scenario20_K3sDescription 21C03 Input NECabinet Fire%CDF/Cumulative aRisk insightsCCDPIF bCDF% LERFLERFRankLERFICDFTabl W--4Ui 2 infcn ieIiitn vns Idvdal ersnig>%o CacltdFr ik1.2% /60.2%This scenario is dominated by RCP sealLOCAs, stuck open and cycling pressurizer relief valves, and loss of SSHR. The fireresults in loss of MFW, loss of ETA, loss ofthe offsite power supply to the B trainessential bus, loss of thermal barrier coolingand a spurious ADV. Independent failures ofthe SSF, aligning offsite power from Unit 1and B diesel lead to RCP seal LOCAs.Spurious injection challenges relief valves,and random CA failures lead to loss of SSHR.Mitigation fails due to random failures (mostlypower). This scenario ranks #13 in the LERFcontribution with random containment failuredue to loss of the igniters being the dominantcontainment failure mode.2.80E-022.21E-05 16.18E-07 1.8%130.143_DA Aux Shutdown 1.2% / 61.4% This scenario is dominated by RCP seal 5.52E-02 1.11E-05 6.10E-07 0.4% 54 0.03Panel Fire (A LOCAs and stuck open pressurizer reliefTrain) valves. The fire results in loss of RN,spurious operation of the NV pumps. Failureto recover RN from RV and Unit 1 results incomplete loss of RN. SSF failure leads to aseal LOCA. Mitigation fails due to the loss ofRN.Rev 0 Page W-26Rev 0Page W-26 Duke Energy Carolinas, LLCAttachment W -Fire PRA InsightsDuke Energy Carolinas, LLC Attachment W -Fire PRA InsightsTable W-2-2 Unit 2 Significant Fire Initiating Events (Individually Representing

>1% of Calculated Fire Risk)% CDF I LERFScenario Description Cumulative a Risk insights CCDP IF b CDF % LERF Rank LERF/CDF13_CC Battery Charger 1.2% / 62.5% This scenario is dominated by RCP seal 2.32E-02 1.29E-04 5.99E-07 0.4% 62 0.03EVCC Severe Fire LOCAs with some contribution from stuckopen pressurizer relief valves. The fire resultsin loss of MFW, normal seal injection, Train AMD CA pump, high pressure ECCS injection, thermal barrier cooling, Train B RN, failure ofthe pressurizer PORVs to open and Train Bdiesel. Failure of the SSF to provide sealcooling leads to a seal LOCA. Failure tothrottle ECCS leads to a stuck open reliefvalve. Mitigation fails due to a combination ofrandom and fire induced failures of therecirculation function.

13_SB KXB Static 1.0% / 63.6% This scenario is split between cycling 1.31 E-01 4.42E-05 5.43E-07 1.9% 11 0.18Inverter Fire pressurizer relief valves and RCP sealLOCAs. The fire results in a loss of normalseal injection, loss of normal power to Train Aessential bus, loss of ETB, loss of TD and MDTrain B CA pumps, loss of thermal barriercooling, loss of all ECCS injection, loss ofTrain B RN and failure of the pressurizer PORVs to open. Failures of the A diesel andSSF lead to a seal LOCA. Failure of the Atrain MD CA pump leads to a loss of SSHR.Mitigation fails mostly due to loss of powerfollowing DG failure.

This scenario ranks #11in the LERF contribution with thermally induced SGTR or loss of the igniters being thedominant containment failure modes.Notes:a. Individual contribution followed by cumulative contribution.

b. Ignition Frequency (IF) includes severity factor and probability of non-suppression, where applicable.

Rev 0 Page W-27Rev 0Page W-27 ENCLOSURE 2Changes Needed to Other Information in the September 26, 2013, MNS NFPA 805 LAR asIdentified During Development of the Response to the NRC Supplemental Information Request.

The supplemental information provided in Enclosure 1 of this submittal required minor changesto Section W.1 on page W-2 of the September 26, 2013, MNS NFPA 805 LAR. The original textin Section W.1 of the LAR discussed Unit 1 results, and because the Unit 2 results were similar,it indicated a table specific to Unit 2 was not provided in the LAR. Revision of this Section W.1text is required since the Unit 2 results are now being provided as part of this supplemental information request.

The revised page W-2 of the LAR incorporating the changes to SectionW.1 is included in this Enclosure

2. The revised page W-2 replaces the original page W-2 in theSeptember 26, 2013, MNS NFPA 805 LAR.The new Tables W-2-1 and W-2-2 provided in Enclosure 1 of this submittal require new pagenumbers be assigned to the September 26, 2013, MNS NFPA 805 LAR pages containing Tables W-3 and W-4. The revised pages containing these Tables are provided in this Enclosure 2 and replace the original Table W-3 and Table W-4 pages in the September 26, 2013, MNSNFPA 805 LAR. Note, the only changes to the Table W-3 and Table W-4 pages are the pagenumbers.

Duke Energy Carolinas, LLC Attachment W -Fire PRA InsightsWA1 Fire PRA Overall Risk InsightsRisk insights were documented as part of the development of the Fire PRA. The totalplant fire CDF/LERF was derived using the NUREG/CR-6850 methodology for Fire PRAdevelopment and is useful in identifying the areas of the plant where fire risk is greatest.

The risk insights generated were useful in identifying areas where specific contributors might be mitigated via modification.

A detailed description of significant risk sequences associated with the fire initiating events that represent a 1 % contribution of thecalculated fire risk for the plant was prepared for the purposes of gaining these insightsand an understanding of the risk significance of MSO combinations.

These insights areprovided in Table W-2-1 and Table W-2-2 for Unit 1 and Unit 2 respectively.

W.2 Risk Change Due to NFPA 805 Transition In accordance with the guidance in Regulatory Position 2.2.4.2 of RG 1.205 Revision 1:"The total increase or decrease in risk associated with the implementation ofNFPA 805 for the overall plant should be calculated by summing the riskincreases and decreases for each fire area (including any risk increases resulting from previously approved recovery actions).

The total risk increase should beconsistent with the acceptance guidelines in Regulatory Guide 1.174. Note thatthe acceptance guidelines of Regulatory Guide 1.174 may require the total CDF,LERF, or both, to evaluate changes where the risk impact exceeds specificguidelines.

If the additional risk associated with previously approved recoveryactions is greater than the acceptance guidelines in Regulatory Guide 1.174,then the net change in total plant risk incurred by any proposed alternatives tothe deterministic criteria in NFPA 805, Chapter 4 (other than the previously approved recovery actions),

should be risk-neutral or represent a risk decrease."

W.2.1 Methods Used to Determine Changes in RiskThe methods and data used to develop the Fire PRA models of the post-transition plantand the compliant plant are consistent with those that underwent the Fire PRA peerreview.The variances from deterministic requirements (VFDRs) are categorized into pre-transition OMAs, separation issues or degraded fire protection systems or features.

MNS VFDR's are only pre-transition OMAs or separation issues. To calculate the deltarisk of a given VFDR, the Fire PRA relies on the list of fire-damaged cables andequipment identified during the VFDR identification phase to model the compliant plant.These cables and equipment are, therefore, at the origin of a delta risk between thepost-transition plant and the compliant plant.The variant case represents the post-transition condition and includes a risk-informed strategy that utilizes failure probabilities for recovery

actions, plant modifications, or acombination, to mitigate the risk of the VFDRs. The variant condition represents the'post-transition' plant configuration, not the currently existing as-built as-operated plantconfiguration.

The variant condition includes the proposed modifications, which includemodifications that reduce plant risk, but are not directly related to any particular VFDR.Rev 0Page W-2 Duke Energy Carolinas, LLCAttachment W -Fire PRA Insights

.Table W-3 MNS Unit 1 Fire Area Risk SummaryFire Area Description NFPA Fire Area Fire Area VFDR RAs Fire Risk Eval Fire Risk Eval Additional Risk Offset RiskArea 805 CDF LERF (Yes/No)

(Yes/No)

A CDF5 A LERF5 of RAs (WL Mod)Basis A LERF122A456Auxiliary BuildingCommon El 695Unit 1 Motor DrivenCA Pump RoomUnit 1 Turbine DrivenCA Pump RoomAuxiliary BuildingCommon El 716Unit 1 Train A DieselGenerator RoomUnit 1 Train B DieselGenerator Room4.2.4.24.2.4.24.2.4.24.2.4.24.2.4.24.2.4.22.17E-097.84E-074.73E-072.88E-075.42E-085.84E-082.01 E-093.13E-081.24E-081.22E-081.58E-081.65E-08YesYesYesYesYesYesNoNoNoYesNoNo2.17E-092.37E-072.53E-071.00E-090.OOE+000.OOE+002.01 E-095.60E-096.67E-091.OOE-100.OOE+000.OOE+00N/AN/AN/A1.00E-09/1.00E-10 N/AN/A0.OOE+002.00E-102.OOE-101.20E-092.1 OE-094.90E-09Unit 1 Train B9-11 Electrical Penetration 4.2.4.2 1.63E-06 8.92E-08 Yes No 1.55E-06 2.72E-08 N/A 4.48E-08& Switchgear Rooms13 Battery Rooms 4.2.4.2 2.98E-06 3.98E-07 Yes Yes 6.30E-07 1.06E-07 6.30E-07/1.06E-07 6.1OE-08Common14 Auxiliary Building 4.2.4.2 2.67E-07 1.99E-08 Yes Yes 0.00E+00 0.00E+00 0.00E+00/0.OOE+00 6.OOE-10Common El 733Unit 1 Train A15-17 Electrical Penetration 4.2.4.2 6.12E-06 5.08E-07 Yes No 2.90E-07 1.00E-08 N/A 1.24E-07& Switchgear RoomsUnit 1 Train A17A Switchgear HVAC 4.2.4.2 1.90E-07 1.04E-08 Yes No 1.90E-07 1.04E-08 N/A 4.80E-09Room5 When used in the context of delta risk, 0.OOE+00 is defined as negligible.

For this table, negligible includes cases where the results are below the truncation limit or where the VFDRs were notmodeled due to their insignificant contribution to risk.Rev 0 Page W-28 Duke Energy Carolinas, LLCAttachment W -Fire PRA InsightsTable W-3 MNS Unit I Fire Area Risk SummaryFire Area Description NFPA Fire Area Fire Area VFDR RAs Fire Risk Eval Fire Risk Eval Additional Risk Offset RiskArea 805 CDF LERF (Yes/No)

(Yes/No)

A CDF5 A LERF5 of RAs (WL Mod)Basis A LERF19 Unit 1 Cable Room 4.2.4.2 9.21E-06 1.96E-06 Yes Yes 2.10E-06 6.30E-07 2.10E-06

/ 6.30E- 418E070721 Auxiliary Building 4.2.4.2 1.56E-06 1.43E-07 Yes Yes 7.00E-08 1.40E-08 7.00E-08/1.40E-08 3.00E-09Common El 750Unit 1 Electrical 22 Penetration Room 4.2.4.2 9.79E-09 9.51 E-09 Yes No 0.00E+00 0.00E+00 0.00E+00/0.00E+00 0.00E+00(MG Set) El 767242526283032DISITSSRVSSFTB1Control RoomCommonAuxiliary BuildingCommon El 767Unit 1 Fuel PoolBuildingUnit 1 InteriorDoghouseUnit 1 ExteriorDoghouseUnit 1 ReactorBuildingDischarge Structure Intake Structure Service BuildingStandby ShutdownFacilityUnit 1 TurbineBuilding4.2.4.2 3.25E-06 4.24E-07 Yes Yes 1.48E-06 2.46E-074.2.4.24.2.4.24.2.4.24.2.4.24.2.4.24.2.4.24.2.4.24.2.4.24.2.4.24.2.4.29.92E-076.58E-101.73E-076.19E-091.52E-072.13E-084.28E-081.15E-065.24E-097.27E-061.53E-076.39E-108.94E-094.82E-104.79E-081.54E-083.11 E-081.20E-073.47E-097.52E-07YesYesYesYesYesYesYesYesYesYesNoNoNoNoNoNoNoNoNoNo0.00E+000.OOE+000.00E+001 .95E-092.50E-080.00E+000.OOE+000.00E+000.OOE+000.00E+000.OOE+000.00E+000.00E+009.70E-1 14.90E-090.OOE+000.00E+000.00E+000.OOE+000.00E+001.48E-06/2.46E-07 N/AN/AN/AN/AN/AN/AN/AN/AN/AN/A9.60E-080.00E+000.00E+007.00E-1 11.00E-121.20E-090.00E+000.00E+005.90E-087.00E-1 16.18E-07YRD Yard Area 4.2.3.2 7.56E-08 7.31 E-08 No N/A 0.00E+00 0.00E+00 N/A 0.00E+00Rev 0Page W-29 Duke Energy Carolinas, LLCAttachment W -Fire PRA Insights

.Duke Energy Carolinas, LLC Attachment W -Fire PRA InsightsFire AreaFire Area Description NFPAArea 805BasisTotalFire AreaCDF3.68E-05Table W-3 MNS Unit 1 Fire Area Risk SummaryFire Area VFDR RAs Fire Risk Eval Fire Risk Eval Additional Risk Offset RiskLERF (Yes/No)

(Yes/No)

A CDF5 A LERF5 of RAs (WL Mod)A LERF4.86E-06 6.83E-06 1.06E-06 1.44E-06Rev 0 Page W-30Rev 0Page W-30 Duke Energy Carolinas, LLCAttachment W -Fire PRA InsightsTable W-4 MNS Unit 2 Fire Area Risk SummaryFire Area Description NFPA Fire Area Fire Area VFDR RAs Fire Risk Eval Fire Risk Eval Additional Risk Offset RiskArea 805 CDF LERF (Yes/No)

(Yes/NO)

A CDF6 A LERF6 of RAs (WL mod)Basis A LERF133A478Auxiliary BuildingCommon El 695Unit 2 Motor DrivenCA Pump RoomUnit 2 Turbine DrivenCA Pump RoomAuxiliary BuildingCommon El 716Unit 2 Train A DieselGenerator RoomUnit 2 Train B DieselGenerator Room4.2.4.24.2.4.24.2.4.24.2.4.24.2.4.24.2.4.22.16E-091.14E-063.95E-071.40E-074.91 E-083.44E-082.01 E-094.OOE-089.02E-098.60E-091.74E-081.55E-08YesYesYesYesYesYesNoNoNoYesNoNo2.16E-096.OOE-088.70E-080.OOE+000.OOE+000.OOE+002.01 E-091.90E-091.58E-090.OOE+000.OOE+000.OOE+00N/AN/AN/A0.OOE+00/0.OOE+00 N/AN/A0.00E+002.OOE-108.OOE-1 11.OOE-1 12.10E-092.1OE-09Unit 2 Train B10-12 Electrical Penetration 4.2.4.2 1.62E-06 6.85E-08 Yes No 6.OOE-08 1.40E-09 N/A 1.04E-08& Switchgear Rooms13 Battery Rooms 4.2.4.2 4.90E-06 4.23E-07 Yes Yes 8.30E-07 1.65E-07 8.30E-07/1.65E-07 6.20E-08Common14 Auxiliary Building 4.2.4.2 1.87E-06 1.91 E-07 Yes Yes 1.13E-06 1.56E-07 1.13E-06/1.56E-07 3.OOE-09Common El 733Unit 2 Train A16-18 Electrical Penetration 4.2.4.2 9.48E-06 3.91 E-07 Yes No 8.60E-07 3.90E-08 N/A 1.33E-07& Switchgear Rooms6 When used in the context of delta risk, O.OOE+00 is defined as negligible.

For this table, negligible includes cases where the results are below the truncation limit or where the VFDRs were notmodeled due to their insignificant contribution to risk.Rev 0 Page W-31 Duke Energy Carolinas, LLCAttachment W -Fire PRA InsightsTable W-4 MNS Unit 2 Fire Area Risk SummaryFire Area Description NFPA Fire Area Fire Area VFDR RAs Fire Risk Eval Fire Risk Eval Additional Risk Offset RiskArea 805 CDF LERF (Yes/No)

(Yes/NO)

A CDF6 A LERF6 of RAs (WL mod)Basis A LERFUnit 2 Train A18A Switchgear HVAC 4.2.4.2 1.47E-07 9.31 E-09 Yes No 1.47E-07 9.31 E-09 N/A 2.19E-09Room20 Unit 2 Cable Room 4.2.4.2 1.61 E-05 1.89E-06 Yes Yes 1.90E-06 2.40E-07 190 I 2.40E- 3.64E-060721 Auxiliary Building 4.2.4.2 1.12E-06 5.06E-08 Yes Yes 1.00E-08 6.00E-10 1.00E-08/6.00E-10 3.10E-09Common El 750Unit 2 Electrical 23 Penetration Room 4.2.4.2 9.71 E-09 9.41 E-09 Yes No 0.00E+00 0.00E+00 N/A 0.00E+00(MG Set) El 767242527293133DISITSSRVSSFTB2Control RoomCommonAuxiliary BuildingCommon El 767Unit 2 Fuel PoolBuildingUnit 2 InteriorDoghouseUnit 2 ExteriorDoghouseUnit 2 ReactorBuildingDischarge Structure Intake Structure Service BuildingStandby ShutdownFacilityUnit 2 TurbineBuilding4.2.4.2 3.38E-06 5.10E-07 Yes Yes 1.47E-06 2.98E-074.2.4.24.2.4.24.2.4.24.2.4.24.2.4.24.2.4.24.2.4.24.2.4.24.2.4.24.2.4.28.64E-076.05E-103.73E-076.16E-096.89E-082.12E-084.28E-084.30E-075.24E-095.92E-061.98E-075.89E-101.68E-084.80E-1 04.03E-081.54E-083.11E-084.36E-083.47E-096.27E-07YesYesYesYesYesYesYesYesYesYesNoNoNoNoNoNoNoNoNoNo0.00E+000.00E+000.OOE+001 .93E-092.85E-080.00E+000.00E+000.OOE+000.OOE+000.00E+000.OOE+000.OOE+000.00E+009.60E-1 11.74E-080.00E+000.00E+000.OOE+000.00E+000.OOE+001.47E-06/2.98E-07 N/AN/AN/AN/AN/AN/AN/AN/AN/AN/A1.15E-070.OOE+000.OOE+001.00E-101.OOE-120.OOE+000.00E+000.00E+003.1OE-087.OOE-1 15.02E-07Rev 0 Page W-32Rev 0Page W-32 Duke Energy Carolinas, LLCAttachment W -Fire PRA InsightsITable W-4 MNS Unit 2 Fire Area Risk SummaryFire Area Description NFPA Fire Area Fire Area VFDR RAs Fire Risk Eval Fire Risk Eval Additional Risk Offset RiskArea 805 CDF LERF (Yes/No)

(Yes/NO)

A CDF6 A LERF6 of RAs (WL mod)Basis A LERFYRD Yard Area 4.2.3.2 7.56E-08 7.31 E-08 No N/A O.OOE+00 O.OOE+00 N/A O.OOE+00Total 4.82E-05 4.69E-06 6.59E-06 9.32E-07 4.51 E-06Rev 0 Page W-33Rev 0Page W-33