The pellet bed reactors - an alternative to existing reactor concepts

The using of the small spherical fuel particles with protective coating can be one of the ways for solving the problems connected with improvement of physical and engineering performances of nuclear reactors by increasing specific heat removal. The choice of the fuel composition materials and one of the fuel claddings depends on the kind of coolant and its parameters. The possible ways of using the such spherical fuel elements when developing the nuclear power reactors with various coolants (water, helium, nitrogen, nitric tetroxide), application of which is determined by the purpose of the reactor installation and NPP, are discussed. The refueling time can be essentially reduced. The refueling can be made by hydro or pneumatic transport without sealing, of the vessel. Moreover, if it is foreseen, it is possible unloading and loading of the fuel to be made during reactor operation. The complex of problems performed theoretically and experimentally on the creation of the pellet bed reactors at present is described. The research volume would be performed in the nearly future is estimated. (author)