EDN: MOUDWE
Authors & Affiliations
Suslov I.R.
Private institution of the State Atomic Energy Corporation Rosatom “Innovation and Technology Center of the Breakthrough Project”, Moscow, Russia
Suslov I.R. – Leading Expert, Cand. Sci. (Phys.-Math.). Contacts: 1, bldg. 7, office 307, pl. Akademica Dollezhal, Moscow, Russia, 107140. Tel.: +7 (903) 814-35-81; e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it..
Abstract
The kinetic code MX21 based on the method of characteristics is intended for numerical modeling of neutron and photon transfer in stationary states when substantiating the radiation safety of nuclear power facilities. The scope of application is protective compositions of fast neutron reactor installations with liquid metal coolant and fuel cycle facilities.
The stationary multigroup transport equation is solved in the discrete ordinates approximation by the method of characteristics on unstructured grids. The characteristics method is based on transforming the transport equation into a system of ordinary differential equations along trajectories. The MX21 code and the basic version of the MX_PPP pre/postprocessor allow preparing calculation models for the method of characteristics code in a semi-automatic mode.
Many reactor problems are characterized by a combination of irregular geometry in the plane with a regular structure in the Z-direction. For such problems, along with the standard scheme in the MX21 code, a transformation of the transport equation in 3D geometry to a set of transport equation systems for vertical characteristic planes (plane-tracing) is used.
Anisotropic scattering is represented by expansion in a series in associated Legendre functions up to the 3d order. It is possible to use quadratures of the product type. Rotational-reflective symmetry of any order is possible. First and last collision methods are implemented.
For preparation of macroscopic sections of calculation cells, the CONSYST program with the BNAB-RF library with a multigroup approximation of 299 neutron groups and 127 gamma-quanta groups is mainly used, but it is also possible to connect other constant libraries, in particular CASC. The use of scattering anisotropy is currently provided for up to the P3-approximation.
The OECD benchmark for the three-dimensional transport equation in void regions proposed by Kobayashi provided an opportunity to evaluate the effectiveness of the long characteristics method. Comparison of the solution obtained by the characteristics method with the reference solution showed excellent agreement of about 0.1 % with the analytical solution for a purely absorbing medium and of about 1 % with the Monte Carlo solution for the case of 50 % scattering. Thus, the program solution by the characteristics method can be considered as an independent confirmation of the reference solution.
Keywords
transport theory for neutrons and photonsв, method of characteristics, calculation of cell, core and protection
Article Text (PDF, in Russian)
References
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UDC 621.039.54(04)
Problems of Atomic Science and Technology. Series: Nuclear and Reactor Constants, 2025, no. 1, 1:8
