CALCULATION OF THERMAL NEUTRON FLUX IN RADIATION SHIELDING BY PROGRAM FRIGATE WITH USING A SUBMODELLING METHOD
Using the example of calculating the thermal neutron flux density in an ionization chamber, where a methodically correct solution is required to be obtained only within a fragment of the computational model, and particle transport from the source to the studied region can be carried out in a more rough approximation, the use of DSN-DSN schemes discrete ordinate method on grids with a completely heterogeneous structure in combination with the submodeling method. The paper presents the results of calculating the thermal neutron flux density and the number of fission reactions in the sensitive part of an ionization chamber located in a concrete radiation protection shaft using the FRIGATE program (DSN method using the submodeling method) and cross-validation with the TDMCC program (Monte-Carlo method). The work continued the study, aimed at verifying the method of submodeling by spatial, angular, and energy variables, recommended for use in radiation protection calculations by deterministic codes. Cross-verification was performed using the FRIGATE DSN program and the TDMCC Monte Carlo code using the example of calculating the thermal neutron flux density and the number of fission reactions in the sensitive part of the fission ionization chamber. Verification results showed good agreement between the considered functionals (constant methodological discrepancy within 25 %). The obtained results confirm the effectiveness of using DSN programs in combination with irregular grids and the submodeling method in radiation protection calculations.