Study on neutronics design of accelerator driven subcritical reactor as future neutron source, part 1: static characteristics

In this paper, a basic neutronics design for a future neutron source in Kyoto University Research Reactor Institute (KURRI) is presented. The neutron source is a final goal of so-called “Neutron Factory” project which is anticipated to be realized as an accelerator driven subcritical reactor (ADSR). To generate spallation neutrons, high-energy protons are injected into a target element installed at the center of the core. Spallation neutrons are multiplied in the subcritical reactor to be used as a neutron source for various research fields. The conceptual design was carried out on the basis of the current research reactor KUR in KURRI and was focused on examining its feasibility as a neutron source, for example, the neutron intensity, spectrum, neutron/gamma-ray flux ratio. The impact of the subcriticality, injected proton energy and target material on the performance of neutron source was examined through a kind of sensitivity studies. Furthermore, the power distribution inside the core was extensively investigated since a higher peaking factor in the ADSR may cause a problem in the heat removal and may restrict the usable neutron intensity. Calculations were carried out using the MCNPX code. Calculated results were compared with those of the KUR and the basic feasibility of the ADSR as a neutron source was confirmed.