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PACKAGE ID001242IBMPC00 HGSYSTEMUF6
KWIC TitleModel for Simulating Dispersion due to Atmospheric Release of UF6 
AUTHORSSteven R. Hanna; Joseph C. Chang
LIMITATION/AUDIENCE CODEUNL/UNL
COMPLETION DATE08/27/1998 
PUBLICATION DATE01/01/1997 
DESCRIPTIONHGSYSTEMUF6 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 (1) AEROPLUME/RK, used to model near-field dispersion from pressurized two-phase jet releases of UF6 and its reaction products, (2) HEGADAS/UF6 for simulating dense, ground based release of UF6, (3) PGPLUME for simulation of passive, neutrally buoyant plumes (4) UF6Mixer for modeling warm, potentially reactive, ground-level releases of UF6 from buildings, and (5) WAKE, used to model elevated and ground-level releases into building wake cavities of non-reactive plumes that are either neutrally or positively buoyant. 
PACKAGE CONTENTSMedia Directory; Software Abstract; Media Includes Source Code, Executable Modules, Sample Problem Data, Batch and PIF Files, User Guides;/ 1 CD Rom 
SOURCE CODE INCLUDED?
MEDIA QUANTITY
METHOD OF SOLUTIONThe 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. 
COMPUTERIBM PC 
OPERATING SYSTEMSWindows 95, Windows Nt and Windows 3.1, OS/2 
SOFTWARE LIMITATIONSHGSYSTEMUF6 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, HGSYSTEM, is available at no charge from the official Shell Research LTD HGSYSTEM Web site: http:;//www.users.virtual-chester.com/hgsystem or email HGSystem@OPC.shell.com". 
RELATED SOFTWAREOffical utility software included with HGSYSTEMUF6 distribution: FFMAIN, official utility used to verify the content and format of model input files; POSTHEG, official post-processing utility for HEGADAS; POSTMIX, official post-processing utility fo UF6MIXER; AMBIEN, meteorological pre-processor; APINST, an initial mixing model which assumes the reaction rate of UF6 is not limited by atmospheric turbulence. The model is used to determine the initial characteristic of the plume; PKZIP/PKKUNZIP, shareware software for compacting/uncompacting files; POETAP, post-processing utility for use with the AEROPLUME/RK model; PPOSTMIX, additional post-processing utility used in combination with UF6MIXER results for simulation of transient releases. 
UNIQUE FEATURESHGSYSTEMUF6 is designed for simulation of atmospheric releases of UF6. It contains a detailed formulation of the dispersion, chemical and thermodynamic processes associated with atmospheric transport of UF6. Furthermore, HGSYSTEMUF6 can also be used to simulate transport of generic, non-reactve heavy gases, and neutral or positively buoyant passive gases in the presence of building wakes. 
OTHER PROG/OPER SYS INFOInput/Output naming conventions: AEROPLUME/RK filename.api, filename.apr; HEGADAS/UF6 (transient mode) filename.hti, filename.htr; HEGADAS/UF6 (steady-state model) filename.hsi, filename.hsr; PGPLLUME filename.pgi, filename.pgr; UF6MIXER filename.mxi, filename.out; WAKE filename.wki, filename.out 
REFERENCESS.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. 
HARDWARE REQSMinimum: 486 microprocessor, 8MB memory, and approximately 16 MB free disk space for installation of program files. Recommended: 100 MHZ PENTIUM processor, 16 MB memory, 50 MB free disk space. 
TIME REQUIREMENTSTypical execution times vary from 1-10 minutes depending on the HGSYSTEMUF6 model component selected. 
ABSTRACT STATUSReleased AS-IS August 27, 1998. 
SPONSORDOE/ER 
RESEARCH ORGOak Ridge National Laboratory 
PACKAGE TYPEAS-IS 

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