Importance of Neutron Moderators for Neutron Induced Reactions Placed in a Massive Spallation Target and Nuclear Fuel of ADS

Abstract This paper aims to investigate the neutron induced reactions in ADS (Accelerator Driven Systems) as a function of neutron moderators and cooling systems. The MCNP6.3 transport code is used for the calculations. The ADS contains three main parts: (1) a target where the proton beam delivers its energy; (2) nuclear fuel and a cooling system; (3) an accelerator. The irradiation of the target by a relativistic proton beam generates high energy a neutron flux in the central part of the target and a small part of the flux delivers its energy in the nuclear fuel. The Keff of the fuel is in the range of 0.9–0.95. Beryllium and lead are used to moderate (reflect) the neutron flux. The cooling system modifies the neutron flux too. Helium and liquid sodium are used as coolant in nuclear facilities. The modification of the high energy neutron flux in the target and nuclear fuel is simulated for different cooling systems and moderators.