Improvement of Tone's method with two-term rational approximation

Yamamoto, Akio*; Endo, Tomohiro*; Chiba, Go

An improvement of Tone's method, which is a resonance calculation method based on the equivalence theory, is proposed. In order to increase calculation accuracy the two-term rational approximation is incorporated for the representation of neutron flux. Furthermore, some theoretical aspects of Tone's method, i.e., its inherent approximation and choice of adequate multi-group cross section for collision probability estimation, are also discussed. The validity of the improved Tone method is confirmed through a verification calculation in a irregular lattice geometry, which represents part of a LWR fuel assembly. The calculation result clarifies the validity of the present method.