[en] The essential factor limiting the operability of fuel elements is the force interaction of the fuel kernel and shell. To predict the amount of stress-caused deformation and the service life of the fuel element in interaction of the fuel kernel and shell, it is necessary to have data on creep of fuel in operational conditions. The radiation creep of standard technology fuel was investigated in detail, however the results of modified uranium dioxide with a large grain size necessary to support next-generation fuel elements of water-water energetic reactor, are currently unavailable. The purpose of this work was research of creep of coarse-grained dioxide of uranium in the process of reactor irradiation. Using developed methods and experimental means to measure reactor conditions at the division density of 1.2.10¹³ div/cm³s three cycles of study were carried out as to the radiation creep of modified uranium dioxide with a grain size of 25 μm or less. Diagrams of radiation creep at a stress range of 10–40 MPa were attained at three different temperatures. At the temperature of 747°C, results coincide with data of radiation creep of standard technology uranium dioxide. At this temperature, the deformation is controlled by radiation creep which is confirmed by its linear relationships with stress. Creep speed values obtained at temperatures of 927 and 1028°C are above those of standard dioxide. The dependence of creep speed on stress at these temperatures can be represented with power law or a combination of linear and exponential functions. These results can be used to support of operability of fuel elements with next-generation modified fuel