Abstract: Non-Volume displacement pumps used at nuclear power plants (NPP) in reactor coolant pump sets for the primary coolant circuit of the nuclear power system. The reactor coolant pump set comprising a vertical vane-type single-stage pump with bottom arrangement of the impeller, the pump shaft is connected to the electric motor shaft by a rigid coupling, the radial-axial bearing, installed in the electric motor upper chamber, is made of two main elements: a radial bearing made in the form of a rotor metallic bushing installed on the cylindrical part of the collar and an axial bearing consisting of two stator lever-type balance arm systems with cover plates of antifriction material and rotor cover plates of antifriction material. The radial-axial bearing is cooled by water from the NPP system, pressure head whereof is increased by the screw-type pump located on the upper butt of the radial-axial bearing collar.