It is shown that the pressure characteristic of a pump operating as the main circulation pump unit in reactor facilities should have a stable form without a sink area. The reason for the failure of the characteristic in low-feed modes is described. The recommendations for designing the flow channel of a low-speed axial-flow pump with an increasing form of the pump characteristic are proposed on the basis of numerical studies. The methods for optimizing the geometry of the blade system were applied in the modeling process using the DesignXplorer optimization tool built in the Ansys Workbench software package. To obtain the desired form of the characteristic, it is necessary to set a variable law of the theoretical pressure distribution along the blade span, to provide a stepless and smooth flow around the leading edge of the impeller blade, to increase the blade coverage angles, and to reduce the losses in the straightening machine in low-feed mode. The paper presents the energy characteristics for the axial-flow pump, designed taking into account the recommendations developed.