RSICC Home Page H GSYSTEMUF6

RSICC CODE PACKAGE CCC-832

1. NAME AND TITLE

HGSYSTEMUF6, Model for Simulating Dispersion due to Atmospheric Release of UF6.

 

AUXILIARY PROGRAMS

FFMAIN-Fixes format from HGSYSTEM, contributed by the OECD NEADB (M021MNYCP00/ESTS0545/01)

2. CONTRIBUTOR

Oak Ridge National Laboratory, Oak Ridge, TN, USA, through the Energy Science and Technology Software Center (ESTSC), Oak Ridge, TN USA

3. CODING LANGUAGE AND COMPUTER

Package includes source directories for Linux and MacOS and Windows systems. FORTRAN. (RSICC ID C0082MNYCP00) Source for FFMAIN available through HGSYSTEM M021MNYCP00/OECD NEADB ID: ESTS0545/01).

4. NATURE OF PROBLEM SOLVED

HGSYSTEMUF6 is a suite of models designed for use in estimating consequences associated with accidental, atmospheric release of Uranium Hexafluoride (UF6) and its reaction products, namely Hydrogen Fluoride (HF), and other non-reactive contaminants which are either negatively, neutrally, or positively buoyant. It is based on HGSYSTEM Version 3.0 of Shell Research LTD., and contains specific algorithms for the treatment of UF6 chemistry and thermodynamics. HGSYSTEMUF6 contains algorithms for the treatment of dense gases, dry and wet deposition, effects due to the presence of buildings (canyon and wake), plume lift-off, and the effects of complex terrain. The models components of the suite include:
AEROPLUME/RK, used to model near-field dispersion from pressurized two-phase jet releases of UF6 and its reaction products,
HEGADAS/UF6 for simulating dense, ground based release of UF6,
PGPLUME for simulation of passive, neutrally buoyant plumes
UF6Mixer for modeling warm, potentially reactive, ground-level releases of UF6 from buildings, and
WAKE, used to model elevated and ground-level releases into building wake cavities of non-reactive plumes that are either neutrally or positively buoyant.

5. METHOD OF SOLUTION

The atmospheric release and transport of UF6 is a complicated process involving the interaction between dispersion, chemical, and thermodynamic processes. This process is characterized by four separate stages (flash, sublimation, chemical reaction entrainment, and passive dispersion) in which one or more of these processes dominate. The various models contained in the suite are applicable to one or more of these stage. For Example, for modeling reactive, multiphase releases of UF6, the AEROPLUME/RK component employs a process-splitting scheme which numerically integrates the differential equations governing dispersion, UF6 chemistry, and thermodynamics. This algorithm is based on the assumption that, for a given time step, the equations governing the processes of dispersion, chemical reaction, and thermodynamics can be solved sequentially and independently. Here, a Runge-Kutta solver is employed to solve the equations governing dispersion, a simple, first-order forward finite difference scheme is used to solve the rate equations for the consumption and production of reactants, while the proprietary nonlinear algebraic equation solver NAESOL, developed by Shell Research LTD. is used to solve equations governing thermodynamic balances of molar fraction, enthalpy and molar flow rate of HF. Conversely, for simulating downwind dispersion of a passive, ideal gas, the WAKE component employs equations based on advanced empirical formulations of wind tunnel data in conjunction with the standard gaussian plume model formation.

 

6. RESTRICTIONS OR LIMITATIONS

HGSYSTEMUF6 is designed for a single user on a single personal computer. Array dimensions have been initially set to reflect realistic, limiting values. By modification of these limits the user may create executable versions of model files that are limited only by the hardware configuration of their machine. HGSYSTEMUF6 is designed specifically for the simulation of atmospheric releases of Uranium Hexafluoride and its reaction products. For other simulations which involve the dispersion of vapour from gas, liquid or two-phase releases including multi-component mixtures.

7. TYPICAL RUNNING TIME

Run times will vary, based on inputs.

8. COMPUTER HARDWARE REQUIREMENTS

Supported platforms are Linux and MacOS and Windows systems.

9. COMPUTER SOFTWARE REQUIREMENTS

Linux, MacOS and Windows Operating systems. To compile user must have working FORTRAN compiler.

10. REFERENCES

Documentation included in package:

S.R. Hanna, J.C. Chang, and J.X. Chang, Technical Documentation of HGSYSTEM/UF6 Model, K/SUB/93-XJ947/1, January 1996;

Steven R. Hanna and Joseph C. Chang, HGSYSTEM/UF6 Model Enhancements for Plume Rise and Dispersion Around Buildings, Lift-off of Buoyant Plumes, and Robustness of Numerical Solver, K/SUB/93-XJ947/2R1, January 1997;

M.W. Yambert, D.A. Lombardi, W.D. goode, Jr and S.G. Bloom, A Summary of Recent Refinements to the WAKE Dispersion Model, a Component of the HGSYSTEM/UF6 Model Suite, ORNL/TM-13666, August 1998.

11. CONTENTS OF CODE PACKAGE

Included on CD are source files for Linux,MacOS and Windows, test cases and documentation.

12. DATE OF ABSTRACT

September 2015

KEYWORDS:September 2015