Comparison of characteristics of subcritical and critical reactor systems with lead-based coolant

International Pb-Bi coolant, specific features of critical and subcritical reactors with Pb-Bi coolant and target are considered. The following systems are considered: the 900 MW power critical reactor RB-EC-2 (cooled by Pb-Bi coolant); two variants of subcritical systems (SS-1 and SS-2) with the same subcriticality level, both designed on the basis of RB-EC-2 reactor installation, but with the larger core size. Results of neutron-physical calculations of characteristics for RB-EC-2, SS-1 and SS-2 reactor systems during their fuel cycle are presented. For the subcritical systems (SS-2) the change of source intensity during the fuel cycle and respective change of efficiency are studied. Magnitude of damaging dose for structural materials is evaluated, and also the analysis and comparison of neutron spectra for the considered types of systems are performed. It is shown that the choice of a ratio between size of the target and size of Pb-Bi buffer surrounding this target depends on the magnitude of neutron source intensity, nonuniformity of energy release, etc