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Fire Modeling Applications in FHA’s

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Fire Modeling Applications in FHA s 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 – PowerPoint PPT presentation

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Title: Fire Modeling Applications in FHA’s


1
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

2
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

3
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

4
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

5
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

6
  • Where does fire modeling fit into an FHA?

7
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.

8
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

9
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.

10
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

11
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

12
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

13
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.

14
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

15
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.

16
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

17
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.

18
Fire Modeling Applications in FHAs
  • Results from NUREG 1824

19
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.

20
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

21
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

22
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.

23
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.

24
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.

25
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

26
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

27
Fire Modeling Applications in FHAs
  • Thank You
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