[en] Sodium stand S III was reconstructed at UJV Rez for the research of the effect of radial displacement of a side rod on the temperature field in a BN-600 fast reactor fuel assembly. A model was built of the BN-600 type fast reactor fuel assembly designated EK-16 containing 14 heating and 2 measuring rods. In heated rods the maximum linear heat flow of 53 W/cm² was attained on the outer rod surface. The differential equation is solved of the temperature field on a heating rod consisting of a heating coil, electric insulation and an outer tube. The course of the mean temperature is shown graphically in the rod and the coolant along the EK-16 channel at a power of 1 kW. Also shown graphically are the hydrodynamic and heat characteristics of stand S III with the EK-16 measuring section. The location of NiCr-Ni microthermocouples on measuring rods is described. Vacuum distillation was used in measuring the sodium oxide content. Technological experiments confirmed that the reconstructed stand can be used for the research of temperature fields in BN-600 type reactors with desired accuracy. (J.F.)