FAQ on MURE package
There is no general method to obtain the geometry. The main problem
of MURE is to simplify Nodes as much as possible. This is not
a simple job but it is easier if you are using the ``put in'' operator
(>>) rather than if ``and'' (&&)
or ``or'' (||) operators.
Sometimes, it takes a lot of time to generate MCNP input files because
some cells are complex and the simplification is time consuming. Note
that complex cells also slow down MCNP run. In order to illustrate
this phenomenon, let's take a simple but significant example. We want
to put in a big water box, 3 boxes of iron, a tube of graphite and
a sphere of iron as shown in figure 1
Figure 1:
Slice in the plane y=0 of the a given geometry.
![\begin{figure}\endgraf
\begin{centering}
\includegraphics[width=10cm]{fig/faq_1}
\par
\end{centering}
\end{figure}](Timg1.gif) |
This geometry has been generated with the following code:
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The problem in this example is that the vessel cell (green part of
the figure) is quite complex ; in MCNP, each neutron in this cell
has to check all surfaces limiting the cell (i.e., all faces of the
3 cubes, all faces of the graphite tube, the sphere and the faces
of the big water box. To simplify the problem for MCNP (and also for
MURE), we need to divide the water box in smaller pieces ; such a
simplification can be achieve by: defining an individual part (box)
for each cube, and one for the tube ; then the tube is built as a
full tube of water inside a full tube of graphite. The code is the
following:
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and the geometry output is shown in figure 2
Figure 2:
Slice in the plane y=0 of a given geometry.
![\begin{figure}\endgraf
\begin{centering}
\includegraphics[width=10cm]{fig/faq_1b}
\par
\end{centering}
\end{figure}](Timg2.gif) |
The gain of running time for MCNP is about 25%. Note that the method
consisting of using universe instead of ``simple'' objects is the
worse possibility: it takes about 25% longer than the first proposed
method.
This is because the DATADIR must be set before any Material definition.
Thus you must used
-
- gMURE-> SetDATADIR();
at the beginning of the program (or use the shell environment variable
DATADIR via a setenv (csh) or export (sh)).
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-
•
mathend000# First you must say that a Material is an evolving one before any Cell
definition.
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-
•
mathend000# Be sure to use a correct BaseSummary.dat
and the corresponding AvailableReactionChart.dat
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•
mathend000# if reactions that you allowed (via a gMURE->SetReactionListInitMethod()
or via a gMURE->SetReactionThreshold()) are not taken into
account, it is probably because an old run with different parameters
has been stored in ReactionList directory. The solution is
to remove this directory.
This is probably because you did not define the Clone() method. If
your EvolutionControl class is EC, this method is then
-
- EvolutionControl* Clone(){return new EC(*this);}
You should probably have to define the appropriate copy constructor
if the EC class contains pointers.
See the section 2 ``How migrate my old MURE V1.x file to the
MURE V2.x file'' of Chapter 3 ``From MURE to SMURE : Choosing
the Monte-Carlo Transport Code'' of the user guide.