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The results of investigations of the corrosion damage and short-time mechanical properties of the fuel-rod cladding and standard and experimental fuel assemblies of the BR-10 reactor with uranium mononitride fuel are presented. It is shown that after irradiation the corrosion depth in the fuel rods of the BR-10 reactor reached 75 μm for the standard and 180 μm for the experimental FA. Degradation of the mechanical properties of fuel-rod cladding also occurred. The corrosion and degradation of the mechanical properties of the cladding of BR-10 reactor fuel rods should be attributed primarily to the high level of impurities in the initial fuel.

The results of an investigation of gas release and swelling of uranium mononitride fuel after irradiation in standard and experimental fuel assemblies in the BR-10 reactor in the burnup range 3.4–8.4% h.a. are presented and analyzed. The results obtained were used to verify the fuel code DRAKON.

The results of post-reactor materials engineering studies of fuel assemblies and control-and-safety system channels, which were unsealed in the reactor of the world’s first nuclear power plant in the period from 1987 to 1998, are presented. It is established that the destruction of the fuel element, fuel-assembly tubes and a channel of the control-and-safety system was due to the formation of through transcrystallite brittle cracks and corrosion foci on the outer side of the tubes and outer cladding of the fuel elements which is in contact with the gas medium of the reactor. Chlorine was discovered on the outer surface of the outer cladding of the fuel elements in the damaged zone. The maximum chlorine concentration was observed in cracks and pits. The presence of the chlorine ion is due to corrosion fissuring and pitting corrosion.

The results of materials-technology investigations of a spent fuel assembly from a reactor at the Obninsk nuclear power plant, the first nuclear power plant in the world, before the rated burnup and after prolonged dry storage (for about 40 years) were presented. It was established that the fuel elements from the fuel assembly studied are in satisfactory condition. No appreciable damage due to the prolonged storage was found: the outer diameter remains within the technological tolerance limits and the strength and the plasticity of the jackets are high. Only surface corrosion damage to 10 μm depth was found on the fuel-element jackets. The fuel composition remained whole. 6 figures, 1 table, 3 references.