Three-dimensional neutronics study for ARIES-ST power plant

The ARIES team is presently studying a fusion power plant based on the spherical tokamak (ST) concept. This paper addresses the key nuclear issues for spherical tokamaks and illustrates the impact of the neutronics factors on the ARIES-ST design. A three-dimensional analysis was carried out for an interim design to determine the key nuclear parameters. Preceding the 3-D analysis, a series of parametric I-D analyses were performed to guide the design toward the final configuration. Comparing the I-D and 3-D results, important differences were identified and attributed mainly to the angular distribution of the incident source neutrons on the first wall. Those differences are unique to spherical tokamaks.