FAST REACTOR

1299038 Reactors E I GRISHANIN V M MUROGOV V V ORLOV and L V TOCHENY 31 Aug 1971 40478/71 Heading G6C A fast nuclear reactor comprises a fertile blanket that envelops a core consisting of an outer and an inner fissile material subzone, the outer subzone being fuelled with Pu-239 and the inner subzone with U-235, the volume of the inner subzone being from about 20% to about 90% of the total volume of the reactor core. In the reactor core, the ratio of Pu-239 to U-235 is preferably in the range from 1: 2 to 5:1. It is expedient to use plutonium in the oxide form and uranium in the metallic form. The coolant is sodium. In examples described, the outer subzone is assembled from bundles of fuel rods containing Pu-239 and U-238, the inner subzone from bundles of fuel rods containing U-235 and U-238, and the blanket from bundles of fuel rods containing natural or depleted U. The coolant may be sodium. The outer subzone may surround either the side walls alone or both the end and side walls of the inner subzone.