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ESTS0023 COMPBRN3.

COMPBRN3, Modelling of Nuclear Power Plant Compartment Fires

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1. NAME OR DESIGNATION OF PROGRAM:  COMPBRN3.
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2. COMPUTERS
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Program name Package id Status Status date
COMPBRN3 ESTS0023/02 Tested 30-JUN-1994

Machines used:

Package ID Orig. computer Test computer
ESTS0023/02 IBM PC PC-80486
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3. DESCRIPTION OF PROGRAM OR FUNCTION

COMPBRN3 is a deterministic fire hazards program designed for use in probabilistic analysis of fire growth in a particular room. This analysis is required when assessing the risk associated with fires in nuclear power plants. An air entrainment model is included which consists of a plume entrainment model, a wall jet entrainment model, and a model for the doorway mixing effect. Output available includes the total heat release rate of the fire, the temperature and thickness of the hot gas layer formed near the compartment ceiling, the mass burning rate for individual fuel elements, the surface temperature of the elements, and the thermal heat flux at user-specified locations.
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4. METHOD OF SOLUTION

A quasi-static approach is followed to simulate the process of fire growth during the pre-flashover period in an enclosure. The compartment is modeled as two zones (or control volumes) which divide it into two distinct, homogeneous, stably-stratified regions. The hot gases accumulating under the ceiling due to fire plume entrainment and negative buoyancy are defined as the upper layer (the ceiling hot gas layer). The lower region is assumed to be thermally inert and contains relatively quiescent cool air, which remains at ambient conditions at all times. These regions are separated by a thermal interface with uniform height inside the room and a higher elevation at the doorway. At each time-step, the hot gas layer model computes the thermal interface heights, the hot gas layer temperature, and the heat fluxes to fuel elements by solving several coupled mass and heat steady-state balance equations by a Newton-Raphson iteration scheme. Correlations are used to determine the convective heat transfer in the buoyant plume of hot gases above the flames. The COMPBRN3 steady-state models and submodels are taken from the fire research literature.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM:
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6. TYPICAL RUNNING TIME

NESC executed the sample problem in 1 minute  on an IBM PC/AT with a math coprocessor.
ESTS0023/02
NEA-DB ran the test case included in this package on a
66-MHz PC/486 in about 2 seconds of clock time.
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7. UNUSUAL FEATURES OF THE PROGRAM:
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8. RELATED AND AUXILIARY PROGRAMS

COMPBRN3 supersedes the earlier COMPBRN codes. COMPBRN3 employs a different air entrainment model and better numerical scheme to solve for the properties of the ceiling hot gas layer; incorporates a number of changes to the plume heat transfer, mean plume temperature correlation, cylindrical shape factor, and vertical fuel cell calculations, and includes added error checking and user-friendly features.
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9. STATUS
Package ID Status date Status
ESTS0023/02 30-JUN-1994 Tested at NEADB
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10. REFERENCES

- COMPBRN3, NESC No. 1105, COMPBRN3 IBM PC Version Flexible Disk
  Cartridge, Description and Implementation Information,
  NESC Note 89-21 (December 7, 1988).
- N.O. Siu:
  COMPBRN - A Computer Code for Modeling Compartment Fires
  NUREG/CR03239 (UCLA-ENG-8257), (1983).
ESTS0023/02, included references:
- Vincent Ho, Nathan Siu, G. Apostolakis and G.F. Flanagan:
  COMPBRN III - A Computer Code for Modeling Compartment Fires
  NUREG/CR-4566, ORNL/TM-10005 (July 1986).
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11. MACHINE REQUIREMENTS:  234 Kbytes of memory are required on an IBM PC/AT.
ESTS0023/02
NEA-DB implemented the program on a DELL 466/L 66-MHZ 80486 with 8 MBytes of RAM. The executable generated with a Lahey compiler has a file size of 418,664 bytes. The executable generated  with Microsoft compiler has a file size of 192,648 bytes.
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
ESTS0023/02 FORTRAN-77
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13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:  DOS 3.1.
ESTS0023/02
The program was implemented under MS-DOS version 6.2. The source code was compiled both with the Lahey F77L-EM/32 Version  5.20 and the Microsoft Version 5.1 Fortran compiler.
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:
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15. NAME AND ESTABLISHMENT OF AUTHORS

         V. Ho, N.Siu, G. Apostolakis, G. Flanagan
               Oak Ridge National Lab.
               TN (United States)
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16. MATERIAL AVAILABLE
ESTS0023/02
File name File description Records
ESTS0023_02.001 Information file 101
ESTS0023_02.002 COMPBRN3 Fortran 77 source 2926
ESTS0023_02.003 COMPBRN3 Lahey executable 0
ESTS0023_02.004 COMPBRN3 Microsoft executable 0
ESTS0023_02.005 Sample problem input 22
ESTS0023_02.006 Sample problem output 2609
ESTS0023_02.007 DOS file-names 6
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17. CATEGORIES
  • G. Radiological Safety, Hazard and Accident Analysis
  • H. Heat Transfer and Fluid Flow

Keywords: fires, gases, heat transfer, nuclear facilities, probabilistic sys assessment, risk assessment, safety.