Effect of Cellular Lattices, Heat-Exchange Intensifiers, and Coolant Mixing on the Critical Power of VVER FA

Abstract

The results of one stage in the development of methods for increasing the critical power of water-cooled nuclear reactors – the capacity of a reactor installation with sharp degradation of the heat exchange characteristics of the coolant (crisis of heat exchange) – are presented. This stage included experimental determination of the effect on the crisis of heat exchange of arranging heat-exchange intensifiers in FA and transverse mixing of the coolant flow, for which lattices assembled from properly shaped cellular elements where used. The FA models consisted of an assembly of 19 fuel-element simulators with a non-uniform distribution of heat emission along the length. Freon-12 was used as the coolant. The models of the FA differed by the type of intensifier lattices and the number of FA arranged along the length. The efficacy of the influence of lattices on the critical power as a result of the intensification of heat exchange and transverse mixing of the coolant was determined separately. The optimal rigging of FA with lattices was determined experimentally.