United States Nuclear Regulatory Commission - Protecting People and the Environment

FIRAC User's Manual: A Computer Code to Simulate Fire Accidents in Nuclear Facilities (NUREG/CR-4561, LA-10678-M)

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Publication Information

Manuscript Completed: February 1986
Date Published:
April 1986

Prepared by:
B.D. Nichols, W.S. Gregory
Los Alamos National Laboratory
Los Alamos, New Mexico 87545

Prepared for:
Division of Fuel Cycle and Material Safety
Office of Nuclear Material Safety and Safeguards
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

NRC FIN A-7152

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This user's manual supports the fire accident analysis computer code FIRAC. FIRAC is designed to estimate radioactive and nonradioactive source terms and to predict fire-induced flows and thermal and material transport within the ventilation systems of nuclear fuel cycle facilities. FIRAC has been expanded and modified to include the capabilities of the zone-type compartment fire model computer code FIRIN developed by Battelle Pacific Northwest Laboratories. The two codes have been coupled to provide an improved simulation of a fire-induced transient within a facility. The basic material transport capability of FIRAC has, been retained and includes estimates of entrainment, convection, deposition, and filtration of material. Also, the interrelated effects of filter plugging, heat transfer, gas dynamics, material transport, and fire and radioactive source terms are simulated.

This report summarizes the physical models that describe the gas dynamic, material transport, heat transfer, and source term processes and illustrates how a typical facility is modeled using the code. The modifications required to couple the code to FIRIN also are presented. Finally, the input and code-calculated output for several sample problems that illustrate some of the capabilities of the code are described.

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