Fire Modeling Applications in FHA’s

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Fire Modeling Applications in FHAs

• Gaines E. Bruce, P.E., SFPE
• WSMS-Mid America
• 105 Mitchell Road, Suite 200
• Oak Ridge, TN 37830
• 865-425-7062
• gaines.bruce_at_wsms.com

• Washington Safety Management Solutions, LLC

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Fire Modeling Applications in FHAs

• What is a Fire Model?
• Model is a term applied to many physical and
  mathematical procedures designed to simulate
  reality.
• Fire Growth Model is mathematical procedure
  developed to estimate the change in the
  environment of a space or building caused by a
  fire in that space that varies in intensity
  and/or involvement with time.
• Typically models involve the simultaneous
  solution of two, or more, differential equations.
  Some involve many variables and can be quite
  complex.
• Basically three types of fire models
• Zone Model
• Field Model
• Hybrid Model

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Fire Modeling Applications in FHAs

• Zone Model
• Usually divide each room into spaces or zones
• Upper Zone contains hot gasses produced by fire
• Lower zone contains the source of air for
  combustion
• Zone sizes change during course of fire. Upper
  zone can expand to occupy almost entire room
  space
• Most of models that can run on PC are Zone Models

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Fire Modeling Application in FHAs

• Field Models
• Usually requires large-capacity computer work
  stations or mainframe computes.
• Divide the space into many small cells
  (frequently tens of thousands)
• Much more detail than zone models
• Solves fundamental equations of mass, momentum,
  in a space that is divided into a grid of
  small-volume cells.
• Hybrid Model
• A model that uses elements of both zone models
  and field models

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Fire Modeling Applications in FHAs

• What Fire Models are available to the general
  industry?
• More than a few, here are a few of my favorites.
• Fire Dynamics Tools (FDTs) NUREG-1805
• Preprogrammed Excel spreadsheets of basic first
  order relationships published in industry
  literature such as SFPE Handbook of Fire
  Protection Engineering.
• Cost Free, download from NRC website
• CFAST (Consolidated Fire and Smoke Transport)
• Zone Model
• Cost Free, download from NIST website
• FDS (Fire Dynamics Simulator)
• Simplified Field Model
• Cost Free, download from NIST website

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• Where does fire modeling fit into an FHA?

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Fire Modeling Applications in FHAs

• Here is part of what we think a Fire Hazard
  Analysis (FHA)
• is about
• FHAs are a thorough analysis of the fire
  potential in a facility.
• FHAs are normally performed on facilities which
  are categorized as a high industrial risk.
• Serves as the basis to support other Safety
  Analysis reports.
• Provides quantitative analysis of fire growth and
  impact.

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Fire Modeling Applications in FHAs

• Here is the FHA Outline We Use
• ACRONYMS/DEFINITIONS
• TABLE OF CONTENTS
• 1.0 INTRODUCTION
• 1.1 Purpose/Objective/Scope
• 1.2 Limitations of Assessment
• 1.3 Approach and Assumptions
• 1.4 Facility Use, Function
• 1.5 Calculations and Computations
• Ok, a model may be a calculations so maybe
  something here?
• 1.6 Document Review
• 1.7 Lessons Learned

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Fire Modeling Applications in FHAs

• Here is the first paragraph from our application
  guide for Section 1.5
• Establish the extent to which the FHA will
  include calculations and/or fire modeling. If
  special methods or calculations are utilized,
  identify them but do not provide a detailed
  description. If computer generated calculations
  and/or models are included, discuss the
  Validation and Verification of those computer
  codes.

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Fire Modeling Applications in FHAs

• 2.0 DESCRIPTION OF FACILITY, EQUIPMENT AND
  PROGRAM
• 2.1 Description of Facility
• 2.2 Minor Facilities
• 2.3 Description of Critical Process Equipment and
  Programs
• 2.4 Description of High-Value Property
• 2.5 Description of Operations
• 2.6 Fire Barriers
• 3.0 LIFE SAFETY
• 3.1 Types of Occupancy
• 3.2 Means of Egress
• 3.3 Interior Finish Materials
• 3.4 Emergency Lighting and Exit Signs
• 3.5 Security Interface
• 3.6 Occupant Notification System
• 3.7 Section Summary

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Fire Modeling Applications in FHAs

• 4.0 FIRE PROTECTION
• 4.1 Water Supply and Distribution System
• 4.2 Fire Suppression
• 4.2.1 Sprinkler System(s)
• 4.2.2 Standpipe Systems
• 4.2.3 Other Automatic Extinguishing Systems
• 4.2.4 Portable Fire Extinguishers
• 4.3 Protective Signaling Systems
• 4.3.1 Fire Detection System
• 4.3.2 Manual Fire Alarm System
• 4.4 Fire Department and Fire Brigade Response
• 4.4.1 Pre-fire Plans
• 4.4.2 Access to Facility by Fire Fighting
  Apparatus
• 4.4.3 Fire Department Description
• 4.4.4 Mutual Aid Response
• 4.4.5 Emergency Planning
• 4.5 Defense-In-Depth

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Fire Modeling Applications in FHAs

• 5.0 FIRE HAZARDS
• 5.1 Discussion of Fire Hazards
• 5.1.1 Limits on Combustibles
• 5.1.2 Control of Ignition Sources
• 5.2 Impact of Natural Hazards on Fire Safety
• 5.2.1 Earthquake
• 5.2.2 Flood
• 5.2.3 Lighting
• 5.2.4 Windstorm
• 5.2.5 Wildland Fires
• 5.3 Analysis of Potential Fire Scenarios
• OK, determining fire impact and bounding
  condition may be a good application for fire
  modeling.
• 5.4 Exposure Fire Potential
• 5.5 Potential for a Toxic, Biological, or
  Radiation Incident
• 5.5.1 Criticality, Radioactive Materials, and
  Contamination
• 5.5.2 Chemical, Corrosive Agents, and Other
  Special Hazards
• 5.5.3 Recovery Potential

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Fire Modeling Applications in FHAs

• Here is what our application guide says about
  Section 5.3
• Reference the facility fire areas and
  locations, as defined in the facility
  description, for property damage limitation.
  Develop the likely fire accident scenarios for
  each fire area. Potential fire scenarios will be
  used to determine flame spread, the consequence
  of a fire, and the effects of environmental and
  radiological releases. Review the scenarios
  described in other SB documentation to assure
  there are no conflicting descriptions. If
  conditions have changed or SB documentation
  scenario descriptions are unrealistic, describe
  the discrepancy and why the current evaluation is
  valid.

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Fire Modeling Applications in FHAs

• 6.0 FACILITY DAMAGE POTENTIAL
• 6.1 Maximum Credible Fire Loss (MCFL)
• 6.2 Maximum Possible Fire Loss (MPFL)
• 7.0 PROGRAMMATIC REVIEW
• 7.1 Evaluation of Administrative Controls in Use
  and Compensatory Measures
• 7.2 Status of Findings From Previous FHAs
• 7.3 Exemptions and Equivalencies
• 8.0 SUMMARY OF IDENTIFIED DEFICIENCIES
• 8.1 Findings and Recommendations
• 8.2 Requirements
• 8.3 Improvements/Observations (Best Practices)
• 9.0 SUMMARY/CONCLUSION
• 9.1 Summary
• 9.2 Conclusions
• 10.0 REFERENCES

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Fire Modeling Applications in FHAs

• Conclusions
• Fire modeling can best be use within an FHA to
  help define the bounds of a fire scenario and add
  some degree of realistic evaluation.
• A well defined fire scenario can be of assistance
  to the DSA team in the development of accident
  scenarios for evaluation.

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Fire Modeling Applications in FHAs

• In section 1.5 of our FHAs we must address
  fire model validation if we use any fire modeling
  within the FHA.
• Question What existing VV is available for
  our fire models?
• Answer I never though Id say this, but
  thank heaven for the Nuclear Regulatory
  Commission.
• NUREG-1824

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Fire Modeling Applications in FHAs

• Citation for NUREG 1824
• Verification and Validation of Selected Fire
  Models for Nuclear Power Plant Applications,
  Volume 1 Main Report, U.S. Nuclear Regulatory
  Commission, Office of Nuclear Regulatory Research
  (RES), Rockville, MD 2005 and Electric Power
  Research Institute (EPRI), Palo Alto, CA.
  NUREG-1824 and EPRI 1011999.
• (Note Seven Volumes in All)
• This NUREG is the first effort to document the
  verification and validation (VV) of five fire
  models that are commonly used in Nuclear Power
  Plant applications. The NUREG was developed in
  accordance with the guidelines that the American
  Society for Testing and Materials (ASTM) set
  forth in Standard E1355-04, Evaluating the
  Predictive Capability of Deterministic Fire
  Models. The results of the NUREG VV are
  reported in the form of ranges of accuracies for
  the fire model predictions.

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Fire Modeling Applications in FHAs

• Results from NUREG 1824

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Fire Modeling Applications in FHAs

• So What is the bottom line?
• Our approach is to use as simplistic a model as
  possible to help assess the magnitude of selected
  fire parameters. So in general, we use nothing
  more sophisticated than the NUREG 1805 FDTs
  spreadsheets.
• The spreadsheets are easier to defend since they
  are basically equations taken from industry
  literature that can be referenced.
• If uncomfortable with using the spreadsheets, the
  preliminary assessments can be performed with
  then and then a formal hand process can be
  documented with less effort.

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Fire Modeling Applications in FHAs

• Here are a few examples
• From the K-25/K-27 Facility FHAs Scenario
  forklift fuel pool fire impacts MAR stored on
  wooden pallets
• 20-gallon spill is assumed capacity of forklift
  tanks
• 53 ft2 (about 7 1/4 ft square) in order for a
  fire to last for at least 5 minutes
• About 0.64 in (a little over 5/8 in) pool depth
• Need cooperative building to confine to this
  depth and expose pallet of MAR
• the fire from the hydrocarbon fluid alone would
  be about 7.3 MW
• If the pallet is ignited, an additional 750 kW
  would be added (single pallet on floor) best
  guess from Hanford pool test and SFPE handbook

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Fire Modeling Applications in FHAs

• if there is pallet to pallet contact), fire
  propagation along a pallet row could be expected
• If the MAR units are separated from each other by
  a short distance (less than 1 ft), fire
  propagation along the pallet row would not be
  expected
• With the major fire contribution coming from the
  hydrocarbon fluid spill, the pallets contribution
  is very minor.
• Wood pallets will require a radiant heat flux in
  excess of 15 kW/m2 in order to ignite.
• A typical evaluation fire for the K-25 and K-27
  Bldgs is 5270 kW over 32 ft2 (4 by 8 by 4
  combustible package). The radiant heat flux at
  the floor from this fire is 7 kW/m2 at 10 ft from
  the fire

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Fire Modeling Applications in FHAs

• One more example from the K-25/K-27 FHA
• Scenario hydraulic fluid fire in foaming trailer
  unit
• The hydraulic system reservoirs contain
  approximately 34 gal of hydraulic fluid (e.g.,
  Mobile DTE 24 or 25 hydraulic fluids).
• The recommended operating temperature for the
  hydraulic system is 48?C (120?F) while the
  maximum operating temperature is 71?C (160?F).
• The Mobile DTE 24 fluid has a flash point of
  220?C (428?F) and the Mobile DTE 25 fluid has a
  flash point of 232C (450?F).
• A significant leak in the hydraulic system could
  result in a hydraulic pool spill within the
  center compartment of the trailer. If the total
  34 gal of the hydraulic fluid were to be spilled
  over the center compartment of the foam trailer,
  the pool depth would be approximately ¾ in.
• If this spill pool could be ignited and
  sufficient air could be provided to the fire,
  this would result in an approximately 10 MW fire
  that would last just over 6.2 minutes.

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Fire Modeling Applications in FHAs

• Example from WIPP FHA
• Scenario Diesel fuel fire from vehicle remote
  refueling
• WIPP operating procedures only allow a 5-gal
  portable container of diesel fuel to be
  transported to the out-of-fuel vehicle for
  refueling to provide a sufficient quantity to
  restart the vehicle and allow it to proceed to
  the underground refueling station to complete
  refueling.
• Provides a possible fuel spill fire event of
  5-gal of fuel at any location in the mined area.
• A 5-gal diesel fire from a spill covering 20 ft2
  can result in a 3.6 MW fire lasting about 3½
  minutes after achieving full pool involvement.
• Should the fire ignite the exposed vehicle, the
  fire size could be larger.

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Fire Modeling Applications in FHAs

• And finally an example for an FHA for the West
  Valley Site (may not be published yet)
• Scenario Hydraulic device used for DD of
  facility
• The hydraulic reservoir size of the various
  hydraulically assisted devices is typically 40
  gal or less in total capacity.
• Highly protected industrial risk guidance such as
  from FM Global Data Sheet 7-98 would not require
  special fire protection measures (such as
  automatic sprinklers) unless several small
  systems closely located (i.e., within 20-ft)
  contained a total aggregate of 100 gal or more of
  combustible hydraulic fluid.
• Even though the hydraulic fluid, if leaked, is
  not expected to become involved in a fire due to
  the minimal and low energy ignition sources
  normally present, a fire, should it occur, would
  involve no more than 40 gal of hydraulic fluid.
• Should this fluid ignite over a 100-ft2 area
  (0.64-in. deep spill), the resultant fire would
  be limited to approximately 15.1 MW in size and
  last slightly more than 5 minutes.

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Fire Modeling Applications in FHAs

• A fire of this size and type would be readily
  noticeable by operators but due to the short
  duration, the fire would be expected to self
  extinguish (i.e. run out of fuel) before
  operators could adequately respond with fire
  suppression actions.
• Should this fire occur in one of the MPP cells,
  the substantial concrete construction and heavy
  construction features that confine radiological
  areas would be expected to confine the fire such
  that no significant building damage or release of
  radiological material would result.
• To help prevent events of this nature, the use of
  high fire point hydraulic fluids are usually
  employed and as mitigative and preventative
  measures, open flame cutting, grinding and
  cutting wheel activities are conducted under
  hotwork controls with a posted fire watch

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Fire Modeling Applications in FHAs

• Conclusions
• Fire modeling can help evaluated a fire scenarios
  and keep in bounds
• Several good fire models are available for no
  cost
• Validation of some of the models for certain fire
  parameters have been published
• The model does not have to be too complex to be
  of value.
• Have yet to use CFAST except in the office
• FDS is fun but takes a lot of computer time, were
  working on improvements
• Selection of the fire model to use depends on
  hove complex the fire scenario is
• Have yet to exceed the ability of FDTs
  spreadsheets
• Prepared to go deeper
• Our philosophy is to keep everything as simple as
  possible

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Fire Modeling Applications in FHAs

• Thank You