Possibility of developing low-power reactors with a pebble-bed core

The possibilities of a two-section pebble-bed core with coolant delivered along the radial direction are examined for a water-cooled water-moderated 100-400 MW(t) reactor with 4 mm in diameter fuel pebbles. The construction of the two-section core includes two ring-shaped fuel layers (inner and outer) separated by a ring-shaped channel for coolant delivery. Water filters through the inner fuel layer from the periphery toward the center and through the outer layer from the center toward the periphery. The basic characteristics of such a reactor are determined. It is shown that the power density of such a core with 4 mm in diameter fuel pellets is two times higher than that in a VVER-1000 reactor, and there is a substantial margin with respect to the average specific heat flux. Thermohydraulic and neutron-physical calculations showed that two-section pebble-bed cores in low-power nuclear power reactors are promising.