Kunitoshi Kurihara

Estimation of Anisotropic Effect of Diffusion Coefficient in a Fast Critical Assembly

The effect of neutron streaming upon the neutron multiplication factor in a fast critical assembly FCA-VI is estimated by considering the anisotropy of the diffusion coefficient. In this paper, the Benoist formula is adopted to obtain the diffusion coefficient. In his original expression, many effects such as those of neutron angular distribution, multiple collision (correlation of different neutron passes) and finiteness of lattice system are included. In order to estimate these effects, the generalized first-flight collision probability method is adopted as in the previous paper, and an improvement is brought over the previous method so as to calculate the effective diffusion coefficient in a practical slab lattice cell which is asymmetric about the center of the cell. Using the method of calculation described above, the anisotropic effect of neutron streaming in the lattices TA, TB, TC and TD used in the FCA VI-1 assembly is estimated. The effect of anisotropy of the diffusion coefficient upon the mult...

Design study for an advanced liquid-metal fast breeder reactor core with high burnup

Design studies are performed for a commercial liquid-metal fast breeder reactor core that can achieve a burnup of 200 GWd/t. A plutonium-type asymmetric parfait core with two different plutonium-enriched zones in the axial direction as well as in the radial direction is studied. This core concept solves core design problems related to high burnup, and it is possible to achieve a burnup of 200 GWd/t with this concept. A core with ductless fuel assemblies suitable for high burnup is also studied. An axially heterogeneous core was selected from among various concepts. It is possible to realize a core with a burnup of 200 GWd/t, a compact size, and a lower core pressure drop than the demonstration reactor design.