Predicting the physical characteristics of future fast reactor core designs on the basis of analyses performed with critical assemblies and standard calculation models

The features of a computing system for reactor calculations are considered and the results of trial calculations with different two-dimensional programmes described. The characteristics of the nuclear data sets used in reactor design calculations and in problems linked with transactinides are presented. The authors describe a method of taking critical assembly experiments routinely into account when defining the physical parameters of projected plants, a method based on calculations of two-dimensional sensitivity factors. This approach is illustrated by an estimate of the errors and variations in the criticality and breeding parameters of a large breeder based on experiments in plutonium assemblies. The results obtained with experimental one- and two-dimensional reactor models using the BNAB-70 and BNAB-78 data libraries are compared with calculations in other countries. The final section contains the results of optimization calculations which provide pointers to possible ways of improving the characteristics of breeders when switching to new types of fuel. (author)