A preliminary study on streaming effect through the gap of blanket modules for a K-DEMO fusion reactor

Abstract

It is known that the blanket module in the fusion reactor is designed for slowing and absorbing neutrons, breeding tritium, and limiting radiation damage to other structures. These blankets are installed remotely at individual positions. In this process, gaps between the blanket modules can occur and the streaming effect through gaps has an effect on the performance of the fusion reactor. The streaming effect affects two aspects in the neutron transport problem: (1) activation of the fusion reactor structures and (2) radiation shielding. It is noted that the shape of the gap is locally different due to the specific shape of the fusion reactor. Also, the mechanical difference of the blanket modules changes the gap size. In this study, the streaming effect caused by different shape and size of the gap are evaluated for a K-DEMO fusion reactor. The blanket modules of the fusion reactor, which are the blanket, vacuum vessel, and water channel, were simply simulated. In each module, the neutron streaming effects were assessed by changing the gap size and shapes. The MCNP5 code was used for the evaluations with ENDF/B-VI cross-section library and SAB2002 thermal cross section library. It was noticed that the neutron flux was significantly changed due to the streaming effect. This study can give guidelines for the simplification of blanket modeling in radiation transport problems.