Three-dimensional neutronics study for ARIES-ST power plant

The ARIES team is presently studying a fusion power plant based on the sphe rical 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 i nterim design to determine the key nuclear parameters. Preceding the 3-D an alysis, a series of parametric I-D analyses were performed to guide the des ign toward the final configuration. Comparing the I-D and 3-D results, impo rtant differences were identified and attributed mainly to the angular dist ribution of the incident source neutrons on the first wall. Those differenc es are unique to spherical tokamaks.