BOT3P5.3: Code System for 2D and 3D Mesh Generation and Graphical Display of Geometry and Results for Radiation Transport Codes.

ENEA/FPN-FISNUC (Nuclear Data Centre), Bologna, Italy, through OECD Nuclear Energy Agency Data Bank, Issy-les-Moulineaux, France.

The programs GGDM, GGTM, DDM, DTM2, DTM3, RVARSCL, MKSRC, CATSM, DTET, PDTM were developed at ENEA FPN-FISNUC, I-40129 Bologna, Italy.

The programs RVARSCL, COMPARE were developed at Institut de Physique Nucleaire, F-91406 ORSAY CEDEX, France.

Fortran 77; PC Linux (P00530MNYCP02). (NEADB ID: NEA 1678/09).

BOT3P was originally conceived as a set of standard FORTRAN 77 language programs in order to give the users of the DORT and TORT deterministic transport codes some useful diagnostic tools to prepare and check their input data files. Later versions extended the possibility to produce the geometrical, material distribution and fixed neutron source data to other deterministic transport codes such as TWODANT/THREEDANT of the DANTSYS system, PARTISN and, potentially, to any transport code through BOT3P binary output files that can be easily interfaced (see, for example, the Russian two-dimensional (2D) and three-dimensional (3D) discrete ordinates neutron, photon and charged particle transport codes KASKAD-S-2.5 and KATRIN-2.0). As from Version 5.1 BOT3P contained important additions specifically addressed to radiation transport analysis for medical applications.

BOT3P-5.3 contains new pre-processing features as for neutron source input and enhanced post-processing capabilities thanks to the revised RVARSCL module.

The following programs are included in the BOT3P software package: GGDM, DDM, GGTM, DTM2, DTM3, RVARSCL, COMPARE, MKSRC, CATSM, DTET, and PDTM.

GGDM requires in input all the geometrical, material and fixed neutron source information to generate the fine mesh boundary arrays, the material density factor for each fine space mesh array, the material number for each material zone array and the distributed source distribution array for DORT/TWODANT/PARTISN (two-dimensional (2D) transport applications) for both X-Y, R-Z and R-Theta geometries. GGTM is the 'twin' code of GGDM for three-dimensional applications. It requires in input all the geometrical, material and fixed neutron source information to generate the geometrical, material and distributed source distribution arrays for TORT/THREEDANT/PARTISN for both X-Y-Z and R-Theta-Z geometries.

The main feature of GGDM and GGTM consists in de-coupling the geometrical model description, which must be prepared once and for all, and the mesh grid refinement options. If users decide to create a more or less refined mesh than the one they have got or to switch from a X-Y/X-Y-Z mesh grid to a R-Theta/R-Theta-Z mesh grid or vice versa, it is sufficient for them to change very few data entries and to run GGDM/GGTM again, without modifying the geometrical description of the model to be analyzed. Both GGDM and GGTM can also produce the data entries related to the presence of a fixed volumetric isotropic neutron source as a function of the generated mesh.

Users can define model areas/volumes with a more (or less) refined mesh grid with respect to the standard one for all the geometry. Moreover, GGDM and GGTM allow creating 'very small' geometrical zones centered about the key flux positions for edit purposes. That gives users the possibility to get the target quantity values in such locations directly from the transport code outputs as region response averages, without any need to interpolate the cell results.

CATSM reads a voxelized geometry and prepares a geometry with smaller size with respect to the original one for TORT and potentially for any other transport code that can manage CATSM output binary files. It can optionally and automatically generate tetrahedron mesh grids starting from the same voxelized geometry, even though the implemented algorithm is still rough and to be improved in future. CATSM is particularly addressed to medical applications.

DDM is graphics pre/post processor and it allows users to check the correctness of the entries generated by GGDM by plotting the geometry, the material mixture distribution or the fixed neutron source distribution, if any. DDM can work as a DORT/TWODANT (or other transport codes, through simple interfaces) post-processor also, by displaying any non-negative scalar target quantities of the transport analysis, such as, for example, the scalar neutron flux.

DTM2 and DTM3 allow users to check the correctness of the entries generated by GGTM by plotting the geometry, the material mixture distribution or the fixed neutron source distribution, if any, in two dimensional plots and three dimensional plots, respectively. Both DTM2 and DTM3 can work as TORT/THREEDANT (or other transport codes, through simple interfaces) post-processors also, by displaying any non-negative scalar target quantity of the transport analysis, such as, for example, the scalar neutron flux.

DTM2 makes 2D cuts of the model normal to one of the 3 coordinate directions X-Y-Z/R-Theta-Z and plots the material distribution or any non-negative target quantity on those cuts. As from BOT3P Version 5.1, DTM2 can visualize cuts of a tetrahedron mesh grid. In addition, users can overlap a tetrahedron mesh grid cut and the corresponding voxelized geometry (in input to CATSM to generate the tetrahedrons) to show how well the unstructured mesh grid matches the exact (voxelized) geometry boundaries.

DTM3 can make 3D parallel projections of a selected set of model material mixtures in a user defined model volume by reproducing the material distribution or a target quantity distribution on the visible surfaces of the selected model.

DTET can make 3D parallel views of a tetrahedron mesh grid (or of a related cut-away) on a selected set of material zones.

DDM, DTM2, DTM3 and DTET generate plots by using the RSCORS Graphics System subroutines which are included in (at least up to) the DOORS-3.3 software package together with DORT and TORT.

DDM, DTM2 and DTM3 can visualize the geometrical content (fine mesh boundaries and zone map) stored in a binary file. This feature makes it possible to easily interface them with other transport codes in order to use them as pre/post-processors not only of DORT and TORT.

RVARSCL can read a VARSCL sequential format file produced by DORT/TORT and the RTFLUX file produced by TWODANT/THREDANT/PARTISN, when the discontinuous space mesh option is not used, and can write a new binary sequential format file according to the input requirements of the post-processors DDM, DTM2, DTM3. RVARSCL gets the spatial distribution of the scalar neutron flux as the result of the sum of a selected number of energy groups. It accepts any user's non-negative weight (response) input function too, depending only on the energy group structure used in the DORT/TORT analysis, to be multiplied by the scalar neutron flux obtained in the DORT/TORT transport calculations.

COMPARE makes it possible to calculate the ratio between two positive target quantities in output from transport analyses (for example the neutron flux in output from DORT/TORT and TWODANT/THREEDANT, using the same fine mesh grid), to store it in a binary file in order to be visualized by the plot programs DDM, DTM2 and DTM3.

MKSRC makes it possible to produce a source binary file in format 'varsor' for DORT, format 'flxmom' for TORT and format 'fixsrc' for TWODANT and THREEDANT, by reading the region map and the scalar source produced by GGDM/GGTM and the spectra associated to each spatial region (up to now, only one moment different from zero can be input).

PDTM reads the matmap and mixmpl binary files generated by GGTM and can reconstruct as many mesh grids defined in partial space domains of the complete original one as the user requires. These mesh grids are at the finer possible refinement between the two refinement levels contained in GGTM output binary files.

**NEW VERSION DIFFERS FROM PREVIOUS VERSION 5.2 IN THE FOLLOWING
FEATURES**

**1. GGDM Mesh Generation Program (2D)**

Users can input a X-Y core cell grid defined in a geometrical domain larger than the one where the transport analysis will be performed. The program takes only the neutron source contributions inside the transport analysis domain into account. This is the case, for example, when a 1/8 R-THETA mesh grid model transport analysis is performed and X-Y fuel cells describing 1/4 core are input to GGDM.

**2. GGTM Mesh Generation Program (3D)**

Users can input X-Y core cell grid strata defined in a geometrical domain larger than the one where the transport analysis will be performed. The program takes only the neutron source contributions inside the transport analysis domain into account. This is the case, for example, when a 1/8 R-THETA-Z mesh grid model transport analysis is performed and X-Y fuel cell strata describing 1/4 core are input to GGTM.

**3. RVARSCL Post-processing Program**

The program can write on the standard output spectrum and/or target function values in sets of cells or positions selected by the user in the standard input.

As from version 5.0, GGTM can optionally calculate errors in volume values due to the stair-cased approximation in geometry. GGTM considers a 'very' refined uniform sub-grid for those single meshes cutting more than one material zone at zone interfaces and works in same way as previously described in the mesh attribution to zones for each single sub-mesh. This method lets users calculate the exact material zone volume values with great precision, independently of the geometry complexity and lets GGTM automatically update material zone densities to conserve mass.

As for the plot programs DDM, DTM2 and DTM3, they do not make any value interpolations among cell values to have contours, when used as post-processors or to plot any fixed neutron source distribution; they simply attribute the entire single mesh grid cell the color corresponding to the adopted value scale. This simple and fast method lets users faithfully reproduce transport results and overlap material, zone, body or mesh borders on the same plots without overcrowding them with too many lines.

The RSCORS, Sandia National Laboratory library of graphical primitives, is required to install and run BOT. RSCORS is distributed with the CCC-650/DOORS3.2 and DOORS3.2a packages. Only a continuous space mesh grid can be generated by GGDM and GGTM and input to DDM, DTM2, DTM3, RVARSCL, COMPARE and MKSRC. It must be remembered that DDM, DTM2 and DTM3, if used in combination with DORT/TORT geometrical and compositional models not coming out from GGDM/GGTM, can read only the FIDO free format with some limitations reported in the user manuals. DTM3 can generate up to ten different frames per run. However, for very large geometrical models, users are suggested not to generate more then 2 or 3 frames in the same DTM3 run in order to avoid too big metafiles and postscript files.

Central processor unit (CPU) time is roughly proportional to the number of cells the 2D/3D models created by GGDM/GGTM consist of and of the number of geometrical objects defined in the combinatorial geometry. For 3D applications, the distributed source distribution array generation may really be time consuming for the R-Theta-Z model if a core simulating neutron source is present.

Just to give an idea of the typical running time of GGTM, it is worth mentioning that the CPU times required by BOT3P Version 1.0 to produce the ENEA VENUS-3 X-Y-Z and R-Theta-Z models, distributed source distribution array included, were respectively 148 s and 293 s on a DIGITAL UNIX ALPHA 500/333 workstation. Both models were more or less one million cells large. Run time for CATSM is proportional to the dimension of the input voxelixed geometry. CPU time greatly increases if a tetrahedron mesh grid is required in output also

The author has run BOT3P Version 5.2 programs on PC under openSUSE and Red Hat Linux, but they are likely to run on all UNIX workstations.

A Fortran 77 compiler is required to compile the codes on all computers. No BOT3P executables are included in this package. BOT3P5.2 was tested by the author on the following platforms:

- OPERATING SYSTEM : openSUSE 10.2 Linux

- COMPILER : g77 version 3.3.5-38

- OPERATING SYSTEM : Red Hat Linux 7.0 and 7.1

- COMPILER : g77 Version 2.96 20000731 (FSF-g77 Ver. 0.5.26 20000731).

BOT3P Version 5.3 was not tested by the author on these platforms. However, there is no reason to believe that BOT3P Version 5.3 does not run on both DEC Alpha W.S. and IBM W.S.

Version 5.3 was tested on Lunix systems at RSICC.

The RSCORS, Sandia National Laboratory library of graphical primitives, is required to install and run BOT. RSCORS is distributed with the CCC-650/DOORS3.2 and DOORS3.2a packages. Linux and DEC versions of librscors.a are included in the distribution. This release was compiled and tested by RSICC on Linux systems:

Pentium PC running Fedora 7 with 32-bit g77 3.4.6-7

Pentium PC running Ubuntu 7.04 with g77 3.4.6-5

AMD Athlon running RedHat Linux 7.3(Valhalla) with g77 0.5.26

**a) included in
documentation:**

Roberto Orsi, *BOT3P Version
5.3: A Pre/Post-Processor System for Analysis*, FPN‑P9H6-011, ENEA/FPN-FISNUC
(Nuclear Data Centre), Bologna, Italy, through OECD Nuclear Energy Agency Data
Bank, Issy-les-Moulineaux, France (October 2008).

**b) background
information:**

W.A. Rhoades, R.L. Childs, *DOORS‑3.2a,
One, Two- and Three-Dimensional Discrete Ordinates Neutron/Photon Transport
Code System*, RSICC Computer Code Collection CCC-650, Oak Ridge National
Laboratory, Oak Ridge, TN

S.L. Thompson, *The RSCORS Graphics System*,
SAND99-XXXX Sandia National Laboratory Working Document, Sandia National
Laboratory, Albuquerque, NM (October 19, 1991).

R.E. Alcouffe, *et al.*, *DANTSYS 3.0: One-,Two-, and
Three-Dimensional, Multigroup, Discrete-Ordinate Transport Code System*,
LA-12969-M, Los Alamos National Laboratory, Los Alamos, NM USA (1995).

R. E. Alcouffe, R. S. Baker, S. A. Turner, J. A. Dahl, *PARTISN
Manual*, LA-UR-02-5633, Los Alamos National Laboratory, Los Alamos, NM, USA (2002).

*MCNP TM ‑ A General Monte Carlo N‑Particle
Transport Code. Version 4C,* LA1309M, Los Alamos National Laboratory, Los Alamos, NM USA (March 2000).

Ivo Kodeli, “NEA-1628 SUSD3D. SUSD3D, 1-, 2-, 3-Dimensional Cross Section Sensitivity and Uncertainty Code,” OECD/NEA Data Bank, Issy-les-Moulineaux, France (2000).

*Prediction of Neutron Embrittlement in the Reactor
Pressure Vessel: VENUS‑1 and VENUS‑3 Benchmarks*,
NEA/NSC/DOC(2000)5, OECD/NEA‑DATA BANK.

M. Pescarini, R. Orsi, M.G. Borgia, T. Martinelli, *ENEA
Nuclear Data Centre Neutron Transport Analysis of the VENUS-3 Shielding
Benchmark Experiment*, KT‑SCG‑00013, ENEA‑Bologna, Italy.

R. Orsi, “BOT3P: Bologna Transport Analysis Pre-Post-Processors
Version 3.0,” *Nucl. Sci. Eng.*,**146**: 248-255 (2004).

R. Orsi, “BOT3P: Bologna Radiation Transport Analysis Pre-Post-Processors
Version 4.0,” *Nucl. Sci. Eng.* **150**, 368-373 (2005).

R.Orsi, “A General Method of Conserving Mass in Complex
Geometry Simulations on Mesh Grids and its Implementation in BOT3P5.0,” *Nucl.
Sci. Eng.*, **154**, 247-259 (2006).

R. Orsi, “Potential Enhanced Performances in Radiation
Transport Analysis on Structured Mesh Grids Made Available by BOT3P,” *Nucl.
Sci. Eng.* **157**: 110-116 (2007).

The package is transmitted as a Unix tar file on a CD. The tar file contains the source files for all BOT3P5.3 programs, scripts, test cases, implementation instructions, sample problems, description of sample problems and documentation.

October 2005, revised December 2007, January 2010

**KEYWORDS:** PLOTTING; NEUTRON; GAMMA-RAY; CYLINDRICAL
GEOMETRY; COMPLEX GEOMETRY; MESH GENERATION; WORKSTATION