Radiation damage to a transmutation system based on a proton accelerator

We discuss radiation damage to a transmutation system driven by a proton accelerator. The transmuter is composed of a lead target, beam window, structural wall, subcritical core, and reflector. Because of its subcritical condition, neutrons are supplied by the spallation reaction generated by high-energy protons. The spallation neutrons, as well as the fission neutrons, cause the radiation damage. We calculated the atomic displacement, the production rates of hydrogen and helium, and energy deposition, varying the effective multiplication factor (keff) and fuel of the transmuter. To vary keff, the thickness of the core was changed. Two types of fuel were investigated. One was He-cooled particle fuel that contains minor actinides (MAs), and the other was Na-cooled mixed-oxide (MOX) fuel. The lead target and the beam window incurred large damages. The structural wall near the beam window also had a large atomic displacement.