APPLICATION OF NON-ANALOG MONTE CARLO MODELING IN SHIELDING CALCULATIONS OF FAST REACTORS

Abstract

In the design and operation of nuclear power plants, one of the most important tasks is to assess the radiation protection of the reactor. Currently, the most widespread are deterministic (method of discrete ordinates) and stochastic computational methods for evaluating functionals. At large attenuations of the neutron flux (by 5-15 orders of magnitude) the deep penetration problems require large computational costs. The most accurate simulation of radiation transfer is achieved by using precision programs that implement the Monte Carlo method with a continuous energy dependence of the cross sections. A detailed description of the geometry and the use of continuous cross sections for particle interactions in calculations lead to high computational costs. To improve computational efficiency, there are variance reduction techniques (non-analog modeling). In this paper the possibility of using non-analog modeling in MCU-FR program by calculating the protection of the fast reactor full-scale model with a lead coolant is considered. The volume-integral neutron fluxes were estimated at points located in a long distance from the center of the reactor core. Analysis results were shown the significant reduction of the variance in the reactor shielding by using the non-analog Monte Carlo method.