Possibility to use different fuel cycles in GT-MHR

The GT-MHR reactor core is characterized by flexibility of neutronic characteristics at the given average power density and fixed geometrical dimensions of the reactor core. Such flexibility makes it possible to start the reactor operation with one fuel, and then to turn to another type of fuel without changes of main reactor elements: fuel block design, core and reflector dimensions, number control rods and their positions etc. Preliminary analysis re-indicates the commercial viability of the GT-MHR concept, part of which is due to its ability to accommodate different fuel types and cycles. This paper presents the results of studies of the neutronic characteristics of GT-MHR cores using different types of fuel (low- and highly-enriched uranium, pure weapons or civil plutonium, MOX fuel). Comparison of different fuel cycles is carried out for a three-batch refueling option with respect to following characteristics: discharged fuel burnup, reactivity change during one partial cycle of fuel burnup, consumption of fissile isotopes per unit of produced energy, power distribution, reactivity effects, control rods worth. It is shown, that the considered options of fuel loads provide the three-year core lifetime (with account for the load factor ∼0, 8) without changes of core design, number and design of control rods at transition from one fuel type to another. (authors)