Effects of random geometry on post-closure repository criticality safety

核分裂性物質の分布の不規則性が処分後の臨界安全性に及ぼす影響に関する検討

Liu, X.*; Fratoni, M.*; Ahn, J.*; 平野 史生 

Liu, X.*; Fratoni, M.*; Ahn, J.*; Hirano, Fumio

The present work aims to study the effect of random geometry on the long-term criticality safety. Preliminary considerations on uranium depositions in randomly fractured rocks have been obtained through an approximated analytical solution to calculate spherical fuel lumps with random locations. With stochastic and heterogeneous conditions applied, the present work examines the conservatives of the neutronic models for repository criticality safety assessment, and provides deeper understandings of the system. The major finding is that, when parameters are chosen to optimized the criticality, effective multiplication factor for systems with the random geometries can be well-bounded by the average case.