ML15099A587

Duke Energy Slides for April 14 Meeting on NFPA-805 for Catawba, McGuire and Robinson

ML15099A587
Person / Time
Site:	Mcguire, Catawba, Robinson, McGuire
Issue date:	04/14/2015
From:	Duke Energy Carolinas
To:	Martin R Plant Licensing Branch II
Martin R
References
TAC MF2934, TAC MF2935, TAC MF2936, TAC MF2937
Download: ML15099A587 (36)

Text

Fleet Fire Protection Program Calculation of Risk for Fire Areas Crediting Control Room Abandonment H. B. Robinson Steam Electric Plant Catawba Nuclear Station McGuire Nuclear Station April 14, 2015

Agenda Purpose Fleet NFPA 805 Transition Status Robinson Discussion Catawba/McGuire Discussion Comparison to FAQ 08-0054 4/9/2015 2

Purpose The purpose of this presentation is to explain the analysis used to develop the delta risk estimates for the Robinson, Catawba, and McGuire Plant fire scenarios that may lead to abandonment of the control room due to loss of control.

4/9/2015 3

Duke Fleet NFPA 805 Transition Status Harris, Oconee and Brunswick: Received NFPA 805 Safety Evaluations Brunswick is in the Fire Protection Program Implementation window McGuire, Robinson, Catawba: NFPA 805 License Amendment Request (LAR) Request for Additional Information (RAI) phase LAR Audits are complete Current focus is primarily PRA 3, aggregate risk impacts Potential additional clarification requests on submitted RAI responses 4/9/2015 4

Duke Fleet NFPA 805 Transition Status NFPA 805 Processes Established Across the Duke Fleet include:

Fire Protection Change Process Fire Protection Impact Screening for Plant Design Changes NFPA 805 Monitoring Transient Combustible Control Hot Work Permits Fire Brigade Training 4/9/2015 5

Robinson 4/9/2015 6

Control Room Abandonment Calculation of Risk Robinson As part of transition to NFPA 805, the fire areas previously utilizing an exit the control room Self-Induced Station Blackout (SISBO) strategy under Appendix R were re-analyzed for a shutdown from the Main Control Room (MCR)

A3: Ground Floor Auxiliary Building Hallway A5: Auxiliary Building Second Level A13: Battery Room A14: HVAC Equipment Room for Control Room A15: Unit 2 Cable Spreading Room A16: Emergency Switchgear Room and Electrical Equipment Area A17: Rod Control Room A19: Component Cooling Water Surge Tank Room F: Containment 4/9/2015 7

Control Room Abandonment Calculation of Risk Robinson Shutdown at the Primary Control Stations (PCS) is credited in the NSCA only for Fire Area A18 This fire area includes the Control Room and the Analog Instrumentation Rack Room (Hagan Room)

Previously Evaluated as Dedicated Shutdown Area per Appendix R Under NFPA 805, Fire Area A18 will no longer utilize a SISBO strategy 4/9/2015 8

Control Room Abandonment Calculation of Risk Robinson For a fire in Fire Area A18, the VFDRs are the dedicated shutdown recovery actions These are actions taken at a plant location that do not meet the definition of a PCS For fire areas other than Fire Area A18, VFDRs were identified against a safe shutdown strategy with control from the MCR 4/9/2015 9

Calculation of Delta Risk Robinson Delta risk is the difference between the variant and compliant cases Risk reduction plant modifications are included in both the variant and compliant cases Abandonment is not credited for loss of control Actions outside the control room associated with VFDRs are identified as Recovery Actions To evaluate delta risk for the compliant case, cable VFDRs are assumed to be protected and recovery actions are assumed to be successful - maximizes the delta risk 4/9/2015

Control Room Abandonment Calculation of Risk Robinson Questions regarding the Robinson Treatment?

4/9/2015 11

Catawba and McGuire 4/9/2015 12

Standby Shutdown System Compliance Strategy Catawba and McGuire Fire Areas where Control Room Abandonment/Alternate Shutdown is credited (other than postulated control room fire)

Catawba (CNS) McGuire (CNS) 1: ND & NS Pump Room 522 1: Aux Bldg Common 695 and Pipe 2: U2 CA Pump Room 543 2: U1 MD Aux Feed Pump Room 3: U1 CA Pump Room 543 3: U2 MD Aux Feed Pump Room 4: Aux Bldg Gen Area & NV Pump 543 4: Aux Bldg. Common 716 9: U2 Battery Room 554 13: Battery Rooms Common 10: U1 Battery Room 554 14: Aux Bldg Common 733 11: Aux Bldg Gen Area & U1 KC Pump Room 560 19: U1 Cable Room 16: U2 Cable Room 574 20: U2 Cable Room 17: U1 Cable Room 574 21: Aux Bldg Common 750' 18: Aux Bldg Gen Area & U2 KC Pump Room 577 25: Aux Bldg Common 768 22: Aux Bldg Gen Area 594 4/9/2015 13

Standby Shutdown Facility (SSF)

Catawba and McGuire Alternate Safe Shutdown method at CNS and MNS SSF is essentially a third train Miniature Control Room located away from the TB, AB and RB This is the reason why a large number of fire areas at CNS and MNS are designated as SSF fire areas Features:

Full HVAC Emergency diesel generator as well as off site power feed Batteries for I&C support Plant wide communications setup Functions include:

Establish Reactor Coolant Pump Seal Injection Control Reactor Coolant System pressure and volume Remove decay heat via the steam generators Monitoring key plant parameters 4/9/2015 14

Alternate Safe Shutdown Design Catawba and McGuire The SSF design addresses potential fire impacts Before Leaving MCR Reactor, Turbine, Feedwater Pumps, and Reactor Coolant Pumps tripped select actions based on the unique station design MCC containing needed SSF components is swapped to SSF power aligns many valves to SSF position or transfers control of valves to separate SSF circuitry operated from the SSF TDCAP control power is transferred to SSF power The SSF AOVs are put in their failed position by the use of Transfer Plugs (valves automatically position contrary to hot shorts)

Normal charging pumps and Motor Driven Aux Feedwater pumps are tripped Since SSF design disables MCR fire affected circuits (MSOs, manipulation of MCR controls), MCR actions/circuits cannot impact 4/9/2015 SSF activation/operation 15

Alternate Safe Shutdown Design Catawba and McGuire Once SSF transfer actions are complete, the plant is separated from fire spurious operation SSF operators have positive plant control SSF design presents an ultimate means of mitigating the fire effects on plant equipment Provides operators with positive means of maintaining NFPA 805 Performance Goals This is why a large number of fire areas at CNS and MNS are designated as SSF fire areas 4/9/2015 16

Alternate Safe Shutdown Operation Catawba and McGuire Plant Response Overview Fire reported and Brigade dispatched Operators use AP/45 as a reference with OPs, APs, and EPs APs and EPs are designed to use A and/or B Train plant equipment to maintain the Performance Goals Operating crew makes decision to enter AP/17 (CNS) or AP/24 (MNS) to activate SSF An operator will perform the MCR actions while typically another operator would be dispatched to the SSF to activate it Once AP/17(24) is entered, operators complete the procedure establishing control of the plant at the SSF The only true abandonment of the MCR is when operators cannot physically be in the MCR 4/9/2015 17

MCR/SSF Fire Response Operation Catawba and McGuire Summary of SSF Operations SSF provides a conservative response to fires, providing the ultimate protection in SSF fire areas For a fire, operations will maintain plant control from the MCR for as long as they can.

If not successful, plant control can be regained from the SSF anytime into the event for SSF fire areas CNS and MNS are designed such that the MCR and SSF can be manned at the same time in the event of a fire Command and Control for PCS as described in RG-1.205 is moved from the MCR to the SSF as AP/17 (CNS) / AP/24 (MNS) is executed 4/9/2015 18

Alternate Safe Shutdown Analysis Catawba and McGuire Success Path Determination Deterministic Analysis is performed, different success paths are analyzed In most SSF Fire Areas, there were a significant number of locations where Train A and Train B components were encountered Due to plant design, there were a minimal number of locations where the SSF components/cables were encountered This was the success path that was selected This presented an elegant solution for the SSF fire areas to achieve the NFPA 805 Performance Goals 4/9/2015 19

PRA Discussion Overview Catawba and McGuire SSF Modeling in Fire PRA Calculation of Variant Case CDF/LERF Calculation of Compliant Case CDF/LERF Delta Risk Calculation CNS PRA RAI 12 and MNS PRA RAI 13 4/9/2015 20

Modeling SSF in the PRA Catawba and McGuire The SSF is modeled directly in the FPRA SSF functions are included in FPRA fault tree logic HRA for SSF operator actions SSF equipment failures FPRA logic is consistent with plant design and operating procedures 4/9/2015 21

Comparison of Variant Case to Compliant Case Catawba and McGuire Variant Case Compliant Case Base FPRA (as built as Base FPRA (same as variant CCDP/CLERP operated, NFPA 805 projected) case) with VFDRs removed Ignition EPRI Frequency (same as EPRI Frequency Frequency variant case)

Scenario specific (same as NSP/SF Scenario specific variant case)

Functions explicitly modeled SSF Functions explicitly modeled (same as variant case)

Committed NFPA 805 Mods Modifications Committed NFPA 805 Mods (same as variant case)

Removes impact of VFDR from VFDR Impact Includes impact of VFDR model 4/9/2015 22

Calculation of Variant Case CDF/LERF Catawba and McGuire Total variant case CDF/LERF calculated for each fire area Fire PRA includes variant conditions directly in the model Fire impacts are mapped to cables which are mapped to components CCDPs are calculated directly from the FPRA model 4/9/2015 23

Calculation of Compliant Case CDF/LERF Catawba and McGuire The FPRA shows most fires have multiple success paths available These success paths are included in both the compliant and variant cases This eliminates over-stating the compliant case risk and under-stating delta risk Total compliant case CDF/LERF calculated for each fire area Fire impacts on the components which create the VFDR are removed from the model (Basic Event Toggling) 4/9/2015 24

Calculation of Delta Risk Catawba and McGuire Delta risk is calculated on a fire area basis The change in risk estimates are reasonable; no underestimation of delta risk since all conditions are the same except the VFDR impacts No additional equipment is assumed failed in the compliant case Risk reductions modifications accounted for in both cases Same ignition frequencies and NSPs in both cases Credit for SSF is the same in both cases 4/9/2015 25

Treatment of Risk in PRA RAIs CNS-12 & MNS-13 Catawba and McGuire RAI Response Summary:

Request:

Provide the risk of ex-control room* actions performed at the PCS while command and control is maintained in the control room.

Response

Determined the risk of ex-control room actions contained in the PRA that mitigate fire induced failures.

Evaluation Process:

For SSF Fire Areas (excluding MCR)

Identified sequences containing ex-control room actions Excluded sequences associated with actions previously contained in the LAR Removed sequences that contain random failures 4/9/2015

• Actions taken external to control room 26

Treatment of Risk in PRA RAIs CNS-12 & MNS-13 (Continued) Catawba and McGuire Evaluation Process Continued:

Examples of ex-control room operator actions include recover main feedwater start SSF SBMUP start diesel driven instrument air compressor The total CDF associated with these sequences is in the low E-7 range (per unit)

Using the total sequence risk maximizes the estimate of the ex-control room action risk 4/9/2015 27

Control Room Abandonment Calculation of Risk Catawba and McGuire Questions regarding the Catawba/McGuire Treatments?

4/9/2015 28

Comparison to FAQ 08-0054 Robinson, Catawba and McGuire Duke Energy meets the guidance in FAQ 08-0054 B.2.2.4.2.a Variant vs. Compliant Condition Cases are defined per the FAQ guidance B.2.2.4.2.b Fire Risk Evaluation This analysis compares the risk of the variant case with the complaint case per the guidance in the FAQ B.2.2.4.2c Review of Acceptance Criteria Evaluation of the VFDRs meets the acceptance criteria 4/9/2015 29

Closing The treatment of the variant and compliant case with the resulting delta risk calculation for control room abandonment fire scenarios relating to possible loss of control provides a reasonable estimate of the delta risk for transition to NFPA 805 and meets the guidance in FAQ 08-0054.

Questions?

4/9/2015 30

Appendix Related RAI Responses Previously Submitted - RNP Some aspects addressed in this presentation are discussed in greater detail in the Robinson RAI responses for:

PRA 01.f - MCR abandonment is only credited for loss of habitability in the FPRA PRA 23 - Determination of the change-in-risk and the additional risk of recovery actions associated with VFDRs PRA 24.01 - Clarification of actions taken at the remote shutdown locations not associated with MCR abandonment that are credited in the FPRA 4/9/2015 31

Appendix Related RAI Responses Previously Submitted - CNS Some aspects addressed in this presentation are discussed in greater detail in the Catawba RAI responses for:

PRA 11 - Control Room Abandonment for Main Control Room fires PRA 12 - Operator Actions at the PCS when Command and Control is at the MCR PRA 13 - Methods used to determine the change in risk values reported in LAR Tables W-3 and W-4 4/9/2015 32

Appendix Related RAI Responses Previously Submitted - MNS Some aspects addressed in this presentation are discussed in greater detail in the McGuire RAI responses for:

PRA 12 - Control Room Abandonment for Main Control Room fires PRA 13 - Operator Actions at the PCS when Command and Control is at the MCR PRA 14 - Methods used to determine the change in risk values reported in LAR Tables W-3 and W-4 4/9/2015 33

Acronyms AB - Auxiliary Building NFPA - National Fire Protection Association AP - Abnormal Procedure NRC - Nuclear Regulatory Commission CCDP - Conditional Core Damage Probability NSCA - Nuclear Safety Capability Assessment CDF - Core Damage Frequency NSP - Non-Suppression Probabilities CLERP - Combined Large Early Release OP - Operational Procedure Probability PCS - Primary Control Station CNS - Catawba Nuclear Station PRA - Probabilistic Risk Assessment EP - Emergency Procedure RAI - Request for Additional Information EPRI - Electric Power Research Institute RB - Reactor Building FAQ - Frequently Asked Question RG - Regulatory Guide FPRA - Fire Probabilistic Risk Assessment RNP - Robinson Nuclear Plant HRA - Human Reliability Analysis SBMUP - Standby Makeup Pump HVAC - Heating Ventilation Air Conditioning SISBO - Self-Induced Station Blackout I&C - Instrumentation and Control SSA - Safe Shutdown Analysis LAR - License Amendment Request SF - Severity Factor LERF - Large Early Release Frequency SSF - Standby Shutdown Facility MCC - Motor Control Center TDCAP - Turbine Driven Auxiliary Feedwater Pump MCR - Main Control Room TB - Turbine Building MNS - McGuire Nuclear Station U1/U2 - Unit 1/Unit 2 MSO - Multiple Spurious Operations VFDR - Variance From Deterministic Requirements 4/9/2015 34

Duke Energy Participants Jeffery Ertman - Mgr, Nuclear Engineering, NFPA 805/Fleet Fire Protection David Goforth - NFPA 805 Technical Manager Brandi Weaver - Sr Nuclear Engineer, PRA Plant Support Cathy Chan - Nuclear Engineer, NFPA 805/Fire Protection Harold Stiles - Lead Nuclear Engineer, Probabilistic Safety Assessment Stephen Kimbrough- Lead Nuclear Engineer, Probabilistic Safety Assessment Bryan Carroll - Mgr, Nuclear Engineering, PRA Plant Support Bruce Morgen - Mgr, Nuclear Engineering, Probabilistic Safety Assessment Kelly Lavin - Site Fire Protection Program Transition Project Lead (Robinson)

Jeffrey Robertson - Mgr, Nuclear Regulatory Affairs (McGuire)

Arthur Zaremba - Mgr, Nuclear Fleet Licensing Regulatory Affairs 4/9/2015 35

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