A Two-Group Response Function Treatment of Coupled-Core Kinetic Equations and Coupling Coefficient

A two-group, one-dimensional formulation of a coupled-core system is proposed as a revision of the one-group response function method by Shinkawa et al. The coupling coefficient of the Kyoto University Critical Assembly symmetric coupled-core loading is revised. In such a light-water-coupled system, the fast-to-fast coupling, Δ₁₁ proves the greatest, the fast-to-thermal, Δ₁₂, the second, and the thermal-to-thermal, Δ₂₂, the smallest component within the quantity; at the core distance of 10 cm, Δ₁₂ = 0.68Δ₁₁ and Δ₂₂ = 0.028Δ₁₁. Beyond 20 cm, both Δ₁₁ and Δ₁₂ decrease approximately by the fast-neutron relaxation length of water. The effectiveness of the incoming neutrons is considerably dependent on the thickness of the core that receives them.