a simulation study on neutronic behavior of non-fissionable and fissionable materials of different geometries as spallation targets in ads

Spallation process is the most significant process for neutron generation in industry and medicine. this process has been used in the subcritical reactor core. in this research, we study the neutronic behavior of non-fissionable and fissionable spallation targets consists of u-238, th-232, lead bismuth eutectic (lbe) and w-184 materials in cylindrical and conic shapes using mcnpx code. neutronic parameters consist of spallation neutron yield, deposition energy, and angular spectrum of the neutron output. the gas production rate and residual mass spectrum were investigated. the results of this research indicate that the shape of the target must be selected based on target material and operational purposes. the number of neutrons per energy unit is stable at energies higher than 1 gev, and the rate of change in neutron generation has been reduced after that. furthermore, hydrogen is the principal factor in swelling of spallation target and consists of about 88% of gas production. it was found that a target of lbe provides the most favorite parameters for both neutronic and physical properties.