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diff --git a/doc/IGE335/Section5.03.tex b/doc/IGE335/Section5.03.tex new file mode 100644 index 0000000..e811ad2 --- /dev/null +++ b/doc/IGE335/Section5.03.tex @@ -0,0 +1,83 @@ +\subsection{MATXS7A microscopic cross-section examples}\label{sect:ExMATXS} + +The test cases we will consider here use the \moc{LIB:} module to specify that +the cross sections will be taken from a MATXS7A 69 groups microscopic +cross-sections library. We will assume that this library is located in file +\moc{MATXS7A}. + +\subsubsection{\tst(TCXA01) -- The Mosteller benchmark.} + +The typical input data required to analyze this +benchmark\cite{Mostel} with DRAGON is of the form: + +\listing{TCXA01.x2m} + +\vskip 0.3cm + +The input deck begins with declarations for the linked lists and the interface +files and the various modules used for this DRAGON execution. Any word not declared is considered as +a keyword. + +The {\tt LIB:} module is used to interpolate the microscopic cross sections +in absolute temperature and dilution and to produce group-ordered macroscopic +cross sections. We use the MATXS format 69 groups microscopic cross +section library named {\tt 'MATXS7A'}.\cite{MATXS7A}. +Each mixture at a given absolute temperature (in Kelvin) is defined in terms +of MATXS isotope names ({\tt U235, U238, O16,} etc.). In this case, the +number density (in $10^{24}$ particules per cubic centimeter) for each isotope is +provided. Resonant region indices and the type of thermal scattering +approximation used with the 42 thermal groups (free gas or H$_2$O molecular +model) is also specified. Only MATXS type libraries require the thermalization +model to be set. + + +The {\tt GEO:} module is used to define the geometry. Here two types of geometry are considered, +\moc{MOSTELA} a 1--D annular geometry and \moc{MOSTELC} a 2--D Cartesian geometry. These geometries +are defined before knowing the type of discretization or numerical treatment that will follow. +For \moc{MOSTELA} the first line indicates that the geometry has circular boundaries and that it +contains three concentric annular subregions. The boundary conditions (reflection), the annular +radii and the mixture index corresponding to each region of the cell are +given successively. For \moc{MOSTELC} the first line indicates that this geometry has 2--D +Cartesian boundaries containing three subregions, two of which are annular. The boundary conditions +(reflection on each side), the annular radii, the external side widths and the mixture index +corresponding to each region of the cell are given successively. + +Four cases are then considered. First we will analyse the annular geometry using the \moc{SYBILT:} module for flux +calculation. The \moc{DISCR} and dds{tracking} structures are thereby +generated. The {\tt SHI:} module uses microscopic cross section data contained in the +\moc{LIBRARY} and tracking information contained in {\tt 'DISCR'} and {\tt 'TRACKS'} in order to +compute the actual dilution of each resonant isotope ({\tt U235} and {\tt U238}) and to perform a +new interpolation in the MATXS file. Dilutions are only computed for the energy groups with resonance data present on the library; the other groups are assumed to stay at infinite dilution. + +For the second case we will analyse the Cartesian geometry using the again the +\moc{SYBILT:} tracking module for self shielding calculations and the \moc{SYBILT:} module for +flux calculation. The \moc{DISCR} and \dds{tracking} structures are thereby generated. + +Four cases are then considered. First we will analyse the annular geometry using the {\tt SYBILT:} +tracking module allows the geometry named {\tt 'MOSTEL'} to be discretized by the full CP tracking +algorithm. A new tracking file (sequential binary) is created and named {\tt 'TRACKS'}, together +with a +\dds{tracking}l structure named {\tt 'DISCR'}. A periodic tracking (with 12 +angles and 20.0 tracks per cm) is considered here. + +The {\tt ASM:} module uses macroscopic cross section data contained in the +embedded \dds{macrolib} of {\tt 'LIBRARY'} and tracking information contained +in {\tt 'DISCR'} and {\tt 'TRACKS'} in order to compute the reduced and +scattering modified collision probability matrices for each of the 69 energy +groups. We have not used the important capability of DRAGON to use a different +tracking to perform self-shielding and flux calculations. + + +The {\tt FLU:} module uses macroscopic cross section data contained in {\tt +'LIBRARY'} (recovered from the dependency tree) and CPs contained in {\tt +'CP'} in order to compute the neutron flux for each of the 69 energy groups. The +transport equation is solved for the effective multiplication factor +without buckling or leakage model. + + +Next, the {\tt EDI:} module performs spatial homogenization (the cross sections +are smeared over the complete cell) and coarse energy group condensation. The +first coarse energy group contains the micro-groups 1 to 27; the second coarse +energy group contains the remaining micro-groups. + +\eject |
