ABSTRACT – Core sub-criticality can play an important role if the safety enhancement of a nuclear system is necessary, in particular, when minor actinides submitted for transmutation cause an essential degradation of the reactivity feedback effects or/and a significant reduction of the delayed neutron fraction. The present work shows that that a core sub-criticality to-gether with a thermo-hydraulics optimization can compensate the possible degradation of the Doppler-effect and the reduction of the delayed neutron fraction. The particular dependence of the spallation neutron yield allows the creation of a supplementary negative feedback ef-fect in case of accelerator coupled hybrid systems. A number of quantitative examples are provided in this context. |
