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NESC9952 EVENT.

EVENT, Explosive Transients in Flow Networks

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1. NAME OR DESIGNATION OF PROGRAM:  EVENT.
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2. COMPUTERS
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Program name Package id Status Status date
EVENT/84 NESC9952/03 Tested 19-NOV-1985

Machines used:

Package ID Orig. computer Test computer
NESC9952/03 CDC 7600 CDC CYBER 740
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3. DESCRIPTION OF PROBLEM OR FUNCTION

A major concern of the chemical, nuclear, and mining industries is the occurrence of an explosion in one part of a facility and subsequent transmission of explosive effects through the ventilation system. An explosive event can cause performance degradation of the ventilation system or even  structural failures. A more serious consequence is the release of hazardous materials to the environment if vital protective devices such as air filters, are damaged. EVENT was developed to investigate the effects of explosive transients through fluid-flow networks.

Using the principles of fluid mechanics and thermodynamics, governing equations for the conservation of mass, energy, and momentum are formulated. These equations are applied to the complete network subdivided into two general components: nodes and branches.  The nodes represent boundaries and internal junctions where the conservation of mass and energy applies. The branches can be ducts,  valves, blowers, or filters. Since in EVENT the effect of the explosion, not the characteristics of the explosion itself, is of interest, the transient is simulated in the simplest possible way. A rapid addition of mass and energy to the system at certain locations is used. This representation is adequate for all of the network except the region where the explosion actually occurs.

EVENT84 is a modification of EVENT which includes a new explosion chamber model subroutine based on the NOL BLAST program developed at the Naval Ordnance Laboratory, Silver Spring, Maryland. This subroutine calculates the confined explosion near-field parameters and supplies the time functions of energy and mass injection. Solid-phase or TNT-equivalent explosions (which simulate "point source" explosions in nuclear facilities) as well as explosions in gas-air mixtures can be simulated. The four types of explosions EVENT84 simulates are TNT, hydrogen in air, acetylene in air, and tributyl phosphate (TBP or "red oil").
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4. METHOD OF SOLUTION

The complexity of the problem requires a numerical solution. The governing equations are ordinary differential equations in time with pressure, density (nodes), and mass flow rate (branches) as the basic unknowns. The mass flow is expressed as the sum of an estimated value and two correction terms  that are proportional to the variations of nodal pressure and density. The pressure and density variations are calculated from the mass and energy balances at each node, and the new nodal quantities are updated by summing the variations and the previous values. Convergence is reached when the variation is less than a given convergence factor.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM:
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6. TYPICAL RUNNING TIME:  18 CPU seconds for test case execution.
NESC9952/03
NEA-DB executed the test case included in this package  on CDC CYBER 740 in 259 seconds of CPU time.
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7. UNUSUAL FEATURES OF THE PROGRAM:
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8. RELATED AND AUXILIARY PROGRAMS

Graphical output from EVENT and EVENT84 is provided by the EXPLOT and EVPLOT postprocessor programs, respectively. Both programs require the ISSCO proprietary DISSPLA graphics software systems.
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9. STATUS
Package ID Status date Status
NESC9952/03 19-NOV-1985 Tested at NEADB
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10. REFERENCES:
NESC9952/03, included references:
- P.K. Tang et al.:
  Analysis of Ventilation Systems Subjected to Explosive Transients.
  Far-Field Analysis.  LA-9094-MS  (November 1981)
- P.K. Tang:
  A New Numerical Method for the Transient Gas-Dynamic Code EVENT.
  LA-9594-MS  (December 1982)
- P.K. Tang et al.:
  EVENT User's Manual - A Computer Code for Analyzing Explosion
  Induced Gas-Dynamic Transients in Flow Networks.
  LA-9624-M  (January 1983)
- R.A. Martin and T.L. Wilson:
  EVENT84 User's Manual - A Computer Code for Analyzing Explosion
  Induced Gas-Dynamic Transients in Flow Networks.
  LA-10312-M (December 1984)
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11. MACHINE REQUIREMENTS:  112,600 octal words on CDC 7600.
NESC9952/03
165,600 (octal) words of CDC CYBER 740 main storage.
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
NESC9952/03 FORTRAN-IV
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13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:  SCOPE 2.1.
NESC9952/03
NOS 1.4 531 (CDC CYBER 740).
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:
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15. NAME AND ESTABLISHMENT OF AUTHOR

         R.W. Andrae, P.K. Tang, J.W. Bolstad, W.S. Gregory*
         Los Alamos National Laboratory
         P.O. Box 1663
         Los Alamos, New Mexico 87545
         U. S. A.

* Contact
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16. MATERIAL AVAILABLE
NESC9952/03
File name File description Records
NESC9952_03.003 INFORMATION FILE 50
NESC9952_03.004 EVENT/84 JOB CONTROL LANGUAGE 13
NESC9952_03.005 EVENT/84 SOURCE PROGRAM (FORTRAN) 7283
NESC9952_03.006 EVENT/84 SAMPLE PROBLEM INPUT DATA 103
NESC9952_03.007 EVPLOT SOURCE PROGRAM (FORTRAN) 221
NESC9952_03.008 EVENT/84 SAMPLE PROBLEM PRINTED OUTPUT 1997
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17. CATEGORIES
  • H. Heat Transfer and Fluid Flow

Keywords: accidents, compressible flow, nuclear facilities, safety, systems analysis, thermal analysis, ventilation systems.