Calculation of the spallation target neutronic parameters in Accelerator Driven Subcritical TRIGA reactor

In this paper, effect of the spallation target neutronic parameters such as beam profile, proton beam energy (Ep), target thicknesses and for different materials in an Accelerator Driven Subcritical TRIGA reactor has been investigated. Monte Carlo code MCNPX has been used to calculate neutronic parameters such as: spallation neutron yield (Yn/p), neutron spectrum, angular distribution of the spallation neutrons coming out of the target and spallation neutron production spectra in the target region for two cases of uniform and parabolic beam spatial distributions. According to the results, the relative difference of spallation neutron yield increases by 3.45% using a parabolic spatial distribution instead of a uniform spatial distribution and also this parameter increases by 7.91% using a thick target instead of a thin target, respectively. Moreover, with increasing Ep from 115 MeV up to 2 GeV, the relative difference of spallation neutron yield improves by 4813.58%. Additionally, in comparison to uniform spatial distribution of the proton beam, having parabolic spatial distribution has the advantage of more homogeneity in the spatial distribution of generated spallation neutrons as well as heat generation in the target. Also, Yn/p/Ep parameter increases with target atomic number and proton beam energy. Therefore, our results are indicative of the fact that investigating sensitivity of the target spallation neutronic parameters is necessary in order to optimally design a cost-efficient Accelerator Driven Subcritical Reactors (ADSRs).