Comparison of three-dimensional neutronics calculations for a fusion breeder with large channels

Neutronics calculations for the blanket of a tokamak engineering test breeder were compared. Although the agreement is quite good for one-dimensional calculations using different codes and data libraries, a discrepancy appears for three-dimensional calculations. To clarify this discrepancy, a series of calculations was done with the conclusion that for a blanket with large openings such as divertor channels, one-dimensional calculation using the toroidal cylindrical model in addition to a fusion neutron load distribution calculation will result in over-estimation of the neutronics parameters, and detailed three-dimensional calculations are necessary.