APPLICATION OF THE FIRST AND LAST COLLISION METHODS IN ODETTA CODE FOR RADIATION SHIELDING CALCULATIONS

The research is devoted to the features of radiation shieldind calculations by the deterministic program ODETTA, which is intended for numerical simulation of the neutron and photon transport in shielding compositions of the nuclear facilities and based on the discrete ordinates method and finite element method on unstructured tetrahedral meshes. The article describes the methods of the uncollided radiation component calculations implemented in the ODETTA program for “ray” effect elimination which is typical for discrete ordinates method in weakly scattering media with localized radiation sources. In addition, the first collision method allows to correctly simulating point sources, and the last collision method allows calculating the required functionals at the detection points located outside the computational domain. The implemented methods have been tested on computational benchmarks and experiments, a brief description of which is given in the article. The results obtained were compared with analytical and experimental data, as well as with the results of calculations by the Monte Carlo method within the Scale 6.2.3 software package. The analysis of the influence of the calculated parameters is carried out and conclusions are drawn about the effectiveness of the implemented methods.