Neutron Monitors of Various Geometrical Design for Detection of Nuclear Smuggling in Cargo Containe

Abstract

Neutron monitoring systems for monitoring illegal transport of nuclear material in cargo container are generally manufactured using He-3. However, due to the short supply of He-3, research of neutron monitoring system using alternative neutron detection material has been continuously performed by many research groups. Among alternative neutron detection materials, B-10 is suitable for use as an alternative neutron reactant due to its various advantages. However, due to the short path length of secondary radiation within the material, simulations of models of various designs must be performed in order to develop high-performance neutron monitors. In this study, to calculate the collected signal number of neutron monitors with various geometrical structures, neutron and secondary radiation transports in neutron monitors were simulated using the Monte Carlo method. And the signals collected in each neutron monitor were calculated using the signal detection efficiency calculated by the simulation. The neutron source used for the simulation was Cf-252(1 ng) and neutron monitor model surrounded with 1-inch-thick HDPE (High Density Polyethylene) for neutron conversion. The calculation ofthe collected signal was performed on neutron monitors of four types (planar, cylinder, rectangular, straw). Active area of all type monitor is about 61,000 cm2 and the thickness of the B-10 thin film was set to 2 um. In order to calculate