Funct. Mater. 2026; 33 (2): 362-365.

In the framework of studying the evolution of the microstructure of lava-like fuel-containing materials of Unit 4 of the Chernobyl Nuclear Power Plant, the process of measuring the composition of uranium oxide mixtures during interaction with an atmosphere of humid air was modeled based on the ratio of the intensities of the peaks of incoherent IC and coherent IR scattering of X-rays. For modeling, powder samples of lead and bismuth were selected, the oxides of which are closest to uranium oxides in terms of the IC/IR ratio. The measurements were performed on a portable energy-dispersive spectrometer SPRUT with an SDD X-100 detector (Amptek) in radiation from a silver anode; the secondary target was silver, and the source power was 15 W. Kinetic curves of the change in the IC/IR ratio for powder samples of lead and bismuth during annealing in the atmosphere in the temperature range of 0-200 °C for 3 hours are presented. The sensitivity of the IC/IR ratio to changes in the atomic composition of the mixture was 0.69 (%/at%), the relative error in measuring the IC/IR was 3.5%, and the error in measuring the atomic fraction of the heavy element in the mixture was 2.5 at%. The nature of the kinetic curves corresponds to literary data on the transition from pure metal to its higher oxide. The sensitivity of the IC/IR ratio to changes in the composition of a mixture of uranium oxides during interaction with humid air and chemical compounds with an effective atomic number Z≤13, which are used in the processing of radioactive waste, was assessed. The use of portable X-ray equipment opens up prospects for remote monitoring of the conversion process of uranium oxide-based mixtures using robotics.