Research on approaches to automatic modeling of discrete ordinate programs based on CAD model.

• A new automatic modeling of discrete ordinate program (AMDOP) is developed to automatic convert CAD model to 3D neutronics physics shielding calculation model for the discrete ordinate program. • The linear volume-weighted homogenization method is proposed to mix the material of the mesh containing two or more materials, and obtain the high fidelity neutronics physics shielding calculation model. • The AMDOP is verified based on the Cartesian mesh model and cylindrical mesh model, and applied to the NUREG-CR-6115 benchmark. The azimuthal distribution of scalar flux above 1 MeV are calculated at five different locations in the pressure vessel, and the calculation results show that the automatic modeling method can effectively improve calculation accuracy. In view of reactor shielding calculations with complicated geometry structure, traditional manual modeling of discrete ordinate program is a very cumbersome, inefficient, and error prone. CAD visualization modeling of complicated shielding geometry is implemented based on the open source platform for numerical simulation (SALOME). The discrete ordinate program often requires millions or tens of millions discrete meshes to build a neutronics physics model for a three-dimensional complexity model, each discrete mesh needs to be assigned material. Currently, center point material mapping method is commonly used to assign the mesh material, which assign the material at the center point of the mesh to the mesh material. For the complicated geometry, the discrete meshes typically have multiple materials, which introduces modeling errors. Linear volume-weighted homogenization method is proposed to obtain the uniform mix material of the mesh containing two or more materials. Automatic modeling of discrete ordinate program (AMDOP) is developed based on the linear volume-weighted homogenization method d, which can achieve precise automatic conversion of CAD models to 3D neutronics physics shielding calculation model for the discrete ordinate program. The AMDOP is verified based on a cylindrical model and Kobayashi model, the calculation results of automatic modeling are completely consistent with those of manual modeling, and the linear volume-weighted homogenization method can effectively improve calculation accuracy for model with multiple materials in the discrete meshes. To further verify the reliability and practicality of AMDOP, the practical engineering shielding calculation benchmark problem (NUREG-CR-6115) is modeled and calculated, the results calculated by the linear volume-weighted homogenization method are in good agreement with the reference results, this indicates that the AMDOP automatic modeling process is correct and reliable. [ABSTRACT FROM AUTHOR]