Abstract

For shielding properties improvement, different percentages of boronated compound for two low and high densities were analyzed and the dose-rate in soft tissue have been calculated to decrease the risk for the operators and nearby peoples. The calculations have been performed by means of GEANT4 and MCNPX Monte Carlo codes for two different densities and two different percentages of B-10 and compared to boron-free compound. The parameters such as density, B-10 weight fractions, radiative captures and secondary gamma-ray generation have been analyzed to determine the critical items in these kinds of problems. The secondary gamma-ray from neutron radiative capture as an important side effect in neutron shielding design have been included and discussed in this study utilizing the Geant4 outputs for detail information. The GEANT4 results also were used as evaluation and confirmation of MCNP results.The dose rate of 100 μSv/h at 3 m distance from DENA come from experimental value of neutron yield of 108 neutron per pulse which is much higher than back ground value. The calculations were performed to investigate the optimized compound and thickness to reduce the equivalent dose rate in tissue to the permitted level, 0.1 μSv/h. The dose-rate calculations were obtained by two methods for confirmation as well, the deposited energies of neutron and gamma in soft tissue and transferring them to dose values and also, using the flux-to-dose conversion coefficients from ANSI/ANS standards.