Three dimensional neutronics calculation comparison study for a fusion breeder with large channels

A tokamak reactor is characterized by a toroidal geometry with large ports and channels. The three dimensional calculation seems necessary for the prediction of the neutronics parameters of the calculation. People have been attempting to simulate the configuration by one dimensional model. Assuming that the neutronics parameters such as tritium breeding ratio depends almost only on the primary 14 MeV neutron number entering the blanket, the following approximate scheme was proposed: Α = ΣWi sm-bullet Αi, where Α represents the total value of a parameter; Αi is a partial value contributed from the i'th part of the blanket and is calculated by a 1-D cylindrical model; Wi is the fusion number entering the i'th part of the blanket through the first wall. This scheme seems reasonable for a pure fusion reactor with similar inboard and outboard blankets, since neutron flux angular distribution is strongly forward and the mutual influence between similar blankets is weak. A study on influence between inboard and outboard blankets showed a rather strong influence between blankets in a fusion breeder, where the partial blankets are quite different in neutronics characteristics. The explanation is that the neutron source from fission and n,2n reactions in the outboard blanket causes considerable neutron leakage through the inner surface when it faces an open-quote inferior close-quote inboard blanket