From 7dfcc480ba1e19bd3232349fc733caef94034292 Mon Sep 17 00:00:00 2001
From: stainer_t <thomas.stainer@oecd-nea.org>
Date: Mon, 8 Sep 2025 13:48:49 +0200
Subject: Initial commit from Polytechnique Montreal

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+\subsection{The {\tt ASM:} module}\label{sect:ASMData}
+
+We will now describe the assembly modules which can be used to prepare the
+group-dependent complete collision probability or the assembly matrices required
+by the flux solution module of DRAGON.  The assembly module {\tt ASM:} is
+generally called after a tracking module; it recovers tracking lengths and
+material numbers from the sequential tracking file and then computes the
+collision probability or group--dependent system matrices under various
+normalizations. The calling specifications are:
+
+\begin{DataStructure}{Structure \dstr{ASM:}}
+\dusa{PIJNAM} \moc{:=} \moc{ASM:} $[$ \dusa{PIJNAM} $]$ \dusa{LIBNAM} 
+\dusa{TRKNAM} $[$ \dusa{TRKFIL} $]$ \moc{::} \dstr{descasm}
+\end{DataStructure}
+
+\noindent where
+\begin{ListeDeDescription}{mmmmmmmm}
+
+\item[\dusa{PIJNAM}] {\tt character*12} name of \dds{asmpij} data
+structure containing the system matrices. If \dusa{PIJNAM} appears on the RHS,
+the \dstr{descasm} information previously stored in \dusa{PIJNAM} is kept.
+
+\item[\dusa{LIBNAM}] {\tt character*12} name of the \dds{macrolib} or
+\dds{microlib} data structure that contains the
+macroscopic cross sections (see \Sectand{MACData}{LIBData}).
+
+\item[\dusa{TRKNAM}] {\tt character*12} name of the \dds{tracking} data
+structure containing the tracking (see \Sect{TRKData}).
+
+\item[\dusa{TRKFIL}] {\tt character*12} name of the sequential binary tracking
+file used to store the tracks lengths. This file is given if and only if it was
+required in the previous tracking module call (see \Sect{TRKData}).
+
+\item[\dstr{descasm}] structure containing the input data to this module (see
+\Sect{descasm}).
+
+\end{ListeDeDescription}
+
+\subsubsection{Data input for module {\tt ASM:}}\label{sect:descasm}
+
+\begin{DataStructure}{Structure \dstr{descasm}}
+$[$ \moc{EDIT} \dusa{iprint} $]$ \\
+$[$ $\{$ \moc{ARM} $|$ \\
+~~~~$\{$ \moc{PIJ} $|$ \moc{PIJK} $\}$ $[$ \moc{SKIP} $]$ \\
+~~~~$[$ $\{$ \moc{NORM} $|$ \moc{ALBS} $\}$ $]$ \\
+~~~~$[$ \moc{PNOR} $\{$ \moc{NONE} $|$ \moc{DIAG} $|$ \moc{GELB} $|$ \moc{HELI} $|$ \moc{NONL} $\}$ $]$ \\
+$\}$ $]$ \\
+$[~\{$ \moc{ECCO} $|$ \moc{HETE} $\}~]$ \\
+{\tt ;}
+\end{DataStructure}
+
+\noindent
+where
+
+\begin{ListeDeDescription}{mmmmmmmm}
+
+\item[\moc{EDIT}] keyword used to modify the print level \dusa{iprint}.
+
+\item[\dusa{iprint}] index used to control the printing of this module. The
+amount of output produced by this tracking module will vary substantially
+depending on the print level specified. 
+
+\item[\moc{ARM}] keyword to specify that an assembly calculation is carried out without
+building the full collision probability matrices. This option can only be used for a geometry
+tracked using the interface current method (with EURYDICE-2 option within \moc{SYBILT:} or
+with the multicell surfacic approximation within \moc{SALT:}), \moc{MCCGT:} or \moc{SNT:} module.
+By default, the \moc{PIJ} option is used.
+
+\item[\moc{PIJ}] keyword to specify that the standard scattering-reduced collision
+probabilities must be computed. This option cannot be used with the \moc{MCCGT:} and \moc{SNT:}
+modules. This is the default option.
+
+\item[\moc{PIJK}] keyword to specify that both the directional and standard
+scattering-reduced collision probabilities must be computed. Moreover, the additional directional
+collision probability matrix can only be used if \moc{HETE} is activated in
+\Sect{FLUData}. Finally, the \moc{PIJK}
+option is only available for 2--D geometries analyzed with the operator
+\moc{EXCELT:} with collision probability option. By default, the \moc{PIJ}
+option is used.
+
+\item[\moc{SKIP}] keyword to specify that only the reduced collision
+probability matrix $p^{g}_{ij}$ is to be computed. In general, the scattering
+modified collision probability matrix $p^{g}_{s,ij}$ is also computed using:
+  $$
+p^{g}_{s,ij}=\left[ I-p^{g}_{ij} \Sigma^{g\to g}_{s0} \right] ^{-1}
+p^{g}_{ij}
+  $$
+where $\Sigma^{g\to g}_{s0}$ is the within group isotropic scattering cross
+section. When available, $p^{g}_{s,ij}$ is used in the flux solution module in
+such a way that for the groups where there is no up-scattering, the thermal
+iteration is automatically deactivated. In the case where the \moc{SKIP} option
+is activated, the $p^{g}_{ij}$ matrix is used and thermal iterations are
+required in every energy group. Consequently, the total number of inner
+iterations is greatly increased.
+
+\item[\moc{NORM}] keyword to specify that the scattering-reduced collision probability matrix is
+to be normalized in such a way as to eliminate all neutron loss (even if the
+region under consideration has external albedo boundary conditions which should
+result in neutron loss). When used with a void boundary condition (zero reentrant
+current), this option is equivalent to imposing  {\it a posteriori} a uniform
+reentrant current.
+
+\item[\moc{ALBS}] keyword to specify that a consistent Selengut normalization
+of the scattering-reduced collision probability matrix is to be used both for the flux solution
+module (see \Sect{FLUData}) and in the equivalence calculation (see
+\Sect{EDIData}). This keyword results in storing the scattering-reduced escape probabilities
+$W_{iS}$ in the record named {\tt 'DRAGON-WIS'}. For all the cases where this option is used, it is necessary to
+define a geometry with \moc{VOID} external boundary conditions (see
+\Sect{GEOData}).
+
+\item[\moc{PNOR}] keyword to specify that the collision, leakage and escape
+probability matrices are to be normalized in such a way as to satisfy explicitly
+the neutron conservation laws. This option compensates for the errors which will
+arise in the numerical evaluation of these probabilities and may result in
+non-conservative collision probability matrices. The default option is now \moc{HELI} while it was
+formerly \moc{GELB} ({\bf Revision 3.03}).
+
+\item[\moc{NONE}] keyword to specify that the probability matrices are not to
+be renormalized.
+
+\item[\moc{DIAG}] keyword to specify that only the diagonal element of the
+probability matrices will be modified in order to insure the validity of the
+conservation laws.
+
+\item[\moc{GELB}] keyword to specify that the Gelbard algorithm will be used
+to normalize the collision probability matrices.\cite{RENOR} 
+
+\item[\moc{HELI}] keyword to specify that the Helios algorithm will be used
+to normalize the collision probability matrices.\cite{Helios} 
+
+\item[\moc{NONL}] keyword to specify that a non-linear multiplicative
+algorithm will be used to normalize the collision probability
+matrices.\cite{RENOR} 
+
+\item[\moc{ECCO}] keyword used to compute the $P_1$--scattering reduced
+collision probability or system matrices required by the ECCO isotropic
+streaming model. By default, this information is not calculated.
+
+\item[\moc{HETE}] keyword used to compute the information required by a
+method of characteristics (MOC) solution of the TIBERE anisotropic
+streaming model. By default, this information is not calculated.
+
+\end{ListeDeDescription}
+\eject
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