Algorithmic features of the ECCO Cell Code for treating heterogeneous fast reactor subassemblies

Algorithmic features of the ECCO Cell Code have been improved to represent accurately the effects of self shielding and neutron streaming. Their algorithms are presented in this paper and rely on collision probability methods. Collision probabilities are calculated for explicit 2 dimensional models of fast reactor subassemblies using an improved double step method based on the ROTH approach. The method is demonstrated here on the advanced subassemblies used in the CAPRA dilution core where they account for 0.364% on the critical mass