ML13078A255

03/19/2013-03/21/2013 Licensee Meeting Slides Re Joseph M. Farley Nuclear Plant NFPA 805 Fire Modeling LAR Submittal - Session 10

ML13078A255
Person / Time
Site:	Farley
Issue date:	03/19/2013
From:	Southern Nuclear Operating Co
To:	Ellen Brown Plant Licensing Branch II
Brown E
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ML13078A284	List: ML13078A245 ML13078A246 ML13078A247 ML13078A248 ML13078A250 ML13078A251 ML13078A252 ML13078A253 ML13078A255
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Text

FNP Fire Modeling LAR Submittal O

Overview i

March 19, 2012 Fire Modeling Overview

Fire Modeling Topics The purpose of this presentation is to describe the fire modeling applications at FNC that are used to support th NFPA 805 licensing the li i basis.

b i Fire Fi modeling d li iis performed in one of three general areas:

• Generic Fire Modeling Treatments

- Original report (2008)

- Supplements S l t 1 1, 2 2, and d3

• Main Control Room Abandonment Calculation

• MG Set S t Motor M t ZOI Calculation C l l ti FM Overview Slide 2 of 20

Generic Fire Modeling Treatments

• Purpose

- QQuantify/tabulate antif /tab late the ZOI dimensions aro aroundnd plant ignition sources

• NUREG/CR-6850 ignition sources (bins)

• Combustible C b tibl liquid li id spill ill fifires

- Quantify/tabulate the time to reach threshold HGL temperatures

• ZOI Concept

- ZOI is defined by one or more lateral dimensions and a vertical dimension

- The e ZOI O iss associated assoc ated with t a steady state dadamage age tthreshold es o d heat flux

• 5.7 kW/m² (thermoplastic/non-IEEE-383 qualified cables

• 11.4 kW/m² (thermoset/IEEE-383 qualified cables FM Overview Slide 3 of 20

Generic Fire Modeling Treatments

• ZOI Calculation

- Uses empirical plume models and steady state damage thresholds

• Includes same models used in NUREG-1805; selects most adverse among g all models used

- Variable fire diameter/area (via heat release rate per area)

• Ignition Sources

- Fi Five NUREG/CR-6850 NUREG/CR 6850 electrical l t i l panelsl cases (fift (fifteen HRR bi bins each)

- Transient (fifteen HRR bins)

- Unconfined/confined liquid fire

- Cable tray stacks (applicable to thermoplastic cables only)

FM Overview Slide 4 of 20

Generic Fire Modeling Treatments Transient ZOI Dimensions Panel ZOI Dimensions FM Overview Slide 5 of 20

Generic Fire Modeling Treatments

• ZOI Implementation p

- 98th percentile ZOI dimensions assembled in walkdown form

- Largest horizontal ZOI dimension used when there are multiple dimensions (panels)

- Vertical ZOI dimension used if no secondary combustibles in ZOI

- Ceiling height used do define vertical ZOI dimension if secondary combustibles are in ZOI

- Vertical ZOI dimension is relative to:

• The fire base (transient and combustible liquid fires)

• The Th flfloor ((panell fifires))

• The lowest tray in stack (cable tray fires)

FM Overview Slide 6 of 20

Generic Fire Modeling Treatments

• Key ZOI Limitations (Original Document)

- No secondary combustibles (see Supplement 2)

- No hot gas layer effects

- Open fire configuration

• Hot Gas Layer Effects on ZOI Dimensions

- A modified critical heat flux is used to establish reasonable maximum temperature p and to extend ZOI applicability pp y

• 80°C alters critical heat flux by about 1 kW/m² and is considered the maximum value beyond which non-conservative results could be generated

• Not a required limitation for plume and heat flux models in NUREG-1805 (same methods), but model bias is low due to HGL effects

- Used to extend ZOI for some target classes FM Overview Slide 7 of 20

Generic Fire Modeling Treatments 12 2 1.0 IEEE-383 Cable Thermoset cable Thermoplastic Cable non-IEEE-383 cable 10 combustible Class ClassAAcombustible 0.8 8

0.6 6

0.4 4

0.2 Modified Critica al Heat Flux (kW W/m2) 2 Modified Critical Heat Flux (Btu//s-ft )

0.0 0 0 50 100 150 200 250 300 350 Immersion Temperature (°C)

Temperature range for 100 200 300 400 500 600 thermoset cable target ZOI Immersion Temperature (°F)

( F)

Temperature range for thermoset cable target ZOI characterized using thermoplastic target ZOI FM Overview Slide 8 of 20

Generic Fire Modeling Treatments

• Wall and Corner Configurations

- Within 2 ft of a wall or corner boundary

- Image Method used

• Changeg entrainment characteristics of model p plume to account for corner or wall:

- Model HRR - 2 or 4 X Bin HRR (wall or corner)

- Model fire diameter is 21/2 or 2 X Bin fire diameter ((wall or corner) to maintain constant Q/A

• Change enclosure characteristics to accommodate virtual portions of model fire plume:

- Wall and ceiling area doubled/quadrupled

- Natural and forced ventilation flow paths/volumes doubled/quadrupled FM Overview Slide 9 of 20

Generic Fire Modeling Treatments

• Hot Gas Layer Tables

- List time the HGL reaches threshold value in generic enclosure

- Tabulated by:

• Fire size

• Enclosure volume

• Leakage fraction

- For a g given fire size and enclosure volume,, the minimum time among all leakage fractions is selected

- Generic enclosure derived from sensitivity runs:

• Minimizes surface area

• Adiabatic floor

• Three potential vent combinations for each scenario FM Overview Slide 10 of 20

Generic Fire Modeling Treatments We x Le x He = V A1 = A2 = A3 He=0.63V1/3 A3 We or Le A1 He We or Le Le=1.26V1/3 A2 We=1.26V1/3 Vent Orientation 1 Vent Orientation 2 Vent Orientation 3 Generic Space Vent Orientations FM Overview Slide 11 of 20

Generic Fire Modeling Treatments

• Verification

- Independent review of all calculations performed using Excel

• Validation

- Most applications include at least one fire scenario that falls within ithi the th NUREG NUREG-1824 1824 non-dimensional di i l parameter t space

- Additional basis is provided in LAR Attachment J for plume and heat flux applications that fall outside the NUREG-1824 non-di dimensional i l parameter t space

- CFAST simulations include a geometry that by definition conforms with NUREG-1824 validation range. At least one scenarioi hhas an equivalence i l ration ti th thatt ffalls ll within ithi th the NUREG NUREG-1824 validation range.

FM Overview Slide 12 of 20

Generic Fire Modeling Treatments

• Supplement 1: Closed Panel HRR Estimates

- U Uses ventilation il i and d lleakage k area ffractions i with i h mass and d energy balance to determine maximum internal HRR

- Results compared with available test data (verification) and shown h tto be b conservativeti when h no external t lb burning i iis observed b d or the door does not fail

• Supplement 2: Expanded HGL Tables

- Original Generic Fire modeling treatment approach expanded to include:

• Time-dependent p fires

• Secondary combustibles (two side-by-side, 18 inch wide cable trays Ignited at five minutes at a point above a panel; lateral flame spread per NUREG/CR-6850 recommended rates)

FM Overview Slide 13 of 20

Generic Fire Modeling Treatments

• Supplement 3: Transient Ignition Source Characteristics (T h i l R (Technical Report) t)

- Characterizes ZOI sensitivity to assumed fire diameter or area

- Determines fire area/diameter range for transients based on NUREG/CR-6850 test data

- Identifies special case of 98th percentile transient

- Identifies 98th p percentile transient fire duration based on energy gy content

- Provides revised ZOI dimensions based on 98th fire area and fire duration

- Uses same methods as original Generic Fire Modeling Treatments report to generate revised ZOIs FM Overview Slide 14 of 20

Main Control Room Abandonment Calculation

• Purposep

- Tabulate the abandonment time for ignition sources present in the MCR

- Provide a sensitivity study of the abandonment times to parameter uncertainty

• Method

- CFAST, Version 6.1.1 used

- NUREG/CR NUREG/CR-68506850 Optical Density (OD) and temperature criteria used to define abandonment FM Overview Slide 15 of 20

Main Control Room Abandonment Calculation

• NUREG/CR-6850 Fire Scenarios (15 HRR Bins Each)

- Panel (closed, (closed single/multiple bundle bundle, non-IEEE-383 non IEEE 383 qualified)

- Panel fire that propagates to adjacent panels (open, non-IEEE-383 qualified cables)

- Transient

• Multiple Geometric/Boundary Configurations

- Normal HVAC/no HVAC/purge mode

- Boundary door open/closed/open at 15 minutes

- Operating area/equipment area

• 1080 Base Simulations (4 fires X 15 bins X 9 Geometries X 2 Locations)

FM Overview Slide 16 of 20

Main Control Room Abandonment Calculation Computer Rooms MCR Plan (same HVAC Zone)

FM Overview Slide 17 of 20

Main Control Room Abandonment Calculation

• Sensitivity Analysis (Appendix B)

- Nine parameters assessed for each ignition source (Bin 14 fires)

- Low sensitivity observed in most computed abandonment times (typically +/ 2 minutes or less)

• Some parameters conservatively biased

• Some parameter are not conservatively biased

- Sensitivity is not expected to affect the order of magnitude of risk

• AAppendix di D P Provides id Di Discussion i off V Verification ifi ti andd Validation/Benchmark Installation

- Includes comparison p against g NUREG 4527, Vol. 2 test cases (validation)

- Includes comparison against NUREG 1824 simulations

((verification and validation))

FM Overview Slide 18 of 20

MG Set Motor ZOI Calculation

• NUREG 1805 Computation p

- Thermal plume temperature (vertical ZOI dimension)

- Thermal radiation model (horizontal ZOI dimension)

- Enclosure hot gas layer sensitivity analysis (Appendix B)

• Analysis Follows NUREG-1934 Process

• Verification Provided by NUREG-1824

• Applications Outside of NUREG-1824 Validation Range

- Results are used with conservative bias

- LAR Attachment J provides additional basis for application FM Overview Slide 19 of 20

FNC Fire Modeling Overview Questions?

FM Overview Slide 20 of 20