Effect of composition of three-layer barriers on the transmission characteristics of reactor neutrons

The effects of composition and structure of three-layer barriers (steel-polyethylene-steel, aluminium-polyethylene aluminium) on the transmission of reactor neutrons and accompanying secondary gamma radiation have been experimentally and theoretically studied. The calculations were carried out by the Monte Carlo method using the 26-group ARAMAKO data library taking into account the resonance and heterogeneous effects. The experiments were performed at a research zero power reactor, the ratio of neutron-to-gamma dose in the initial beam being 10:1. The dependences of the neutron and gamma dose transmission coefficients for steel and aluminium stacks (110 and 115 mm thick respectively) on the location of a 10 mm thick polyethylene sheet along the stacks are presented. The dependences are of an extremum character for the steel compositions, and of a monotonous one for the aluminium compositions. Maximum discrepancies between the measured and calculated values do not exceed 2-3% for the whole set of different compositions