PENELOPE 2003 - OECD Nuclear Energy Agency

5.4. Geometry definition file 163
1
5 6
8
5
1 2 7 4
7
4
2
3
3
8
6
9
9
Figure 5.3: Planar cut of a geometry example, showing modules (number labels in circles)
and bodies (number labels in squares), and the associated genealogical tree. Notice that a
module can always be defined as a body limited by their submodules and daughter bodies,
but this affects the structure of the genealogical tree and, therefore, the efficiency (speed) of
the geometry operations.
5.4 Geometry definition file
The geometry is defined from the input file (UNIT=IRD). In principle, this permits the
simulation of different geometries by using the same main program. The input file consists
of a series of data sets, which define the different elements (surfaces, bodies and
modules). A data set consists of a number of strictly formatted text lines; it starts and
ends with a separation line filled with zeros. The first line after each separation line must
start with one of the defining 8-character strings “SURFACE-”, “BODY----”, “MODULE--”,
“END-----” or “INCLUDE-” (here, blank characters are denoted by “-”; they are essential!).
Informative text (as many lines as desired) can be written at the beginning of the
file, before the first separation line. A line starting with the string “END-----” after a
separation line discontinues the reading of geometry data. Each element is identified by
its type (surface, body or module) and a three-digit integer label. Although the element
label can be given an arbitrary value (−99 to 999) in the input file, pengeom redefines
it so that elements of a given kind are numbered consecutively, according to their input
order. Notice that bodies and modules are considered as elements of the same kind (i.e.
assigning the same label to a body and to a module will cause an error of the reading
routine).
In the input file, numerical quantities must be written within the parentheses in the
specified format. All lengths are in cm; angles can be given in either degrees (DEG) or
radians (RAD). When angles are in degrees, it is not necessary to specify the unit. The
parameters in each data set can be entered in any order. They can even be defined
several times, in which case, only the last input value is accepted. This is useful, e.g.