Studying the absorbed dose in two-layer flat samples irradiated by fast neutrons

Fast neutron passage through two-layer fine structures is considered. Absorbed doses in quartz glass layer with polymeric coating of different thickness are calculated. The computerized calculations are carried out by means of the program permitting to apply the Monte-Carlo method for simulation of 0.1-14 MeV neutron irradiation of fine samples comprising plane layers of different materials. Accountancy of elastic ad inelastic neutron scattering as well as reactions with charged paticle escape is presupposed in the program. The calculations are performed for cases of normal drop of homogeneous neutron beams on a flat compostion of quartz glass of 2.21 g/cm3 density with polymeric caprone coating of 1.14 g/cm3 density or dacron coating of 1.38 g/cm3 density. Thickness of the glass layer is 1 mm. Thickness of the coating varied in the 0-2.5 mm range. Based on the analysis of the data obtained it is concluded that the absorbed dose in the surface layer increases several times as compared with the dose calculated for pure material under irradiation of materials with polymeric coatings by neutrons of the reactor spectrum (mean energy is 2 MeV)