Swelling of Nitride Fuel under Different Experimental Irradiation Temperatures at the Early Burnout Stages

3/18/2024 2024 - #01 Nuclear materials

Kinev E.A. Yarkov V.Yu. Isinbaev A.R. Beltyukov I.L. Tarasov B.A. Ivanov A.Yu.

https://doi.org/10.26583/npe.2024.1.07

The purpose of the work is to study the swelling characteristics of dense nuclear fuel at the initial stages of irradiation. Conditionally free diametrical and volumetric changes in mixed uranium-plutonium nitride fuel irradiated to burnups of 1, 1.5, 2.5 and 3.5% FIFA are considered at average volume temperatures of 1200, 1400 and 1500°C in the spectrum of fast neutrons in the core of the IVV-2M research nuclear reactor. The central problem of assessing the swelling of promising fast neutron reactor fuel in terms of reducing errors was solved using the same analytical equipment and techniques both before and after irradiation. Macroscopic cracking and a maximum change in the diameter of the pellets by 4.6% as well as a maximum swelling of the fuel matrix by 13.8% and the formation of an intragranular ensemble of submicron pores with an average diameter of 22 to 67 nm, and migration of nanopores to high-angle grain boundaries were revealed. In general, the dynamics of macroscopic volumetric changes during irradiation are directly proportional to the increase in burnup and temperature. At burnout 3.5% FIFA the mechanism of volumetric swelling of dense fuel reaches a new level when the flow of nanopores with an average size of 50 nm is maximum at 1500°C, and at 1200°C weakens and controls the average nanopore size at the level of 67 nm. The initial rate of radiation swelling of the studied fuel decreases from 4.8%/% FIFA at burnout 1.5% FIFA up to 2.2%/% FIFA at 3.5% FIFA.

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uranium-plutonium nitride fuel pellet burnout swelling pores microstructure

Link for citing the article: Kinev E.A., Yarkov V.Yu., Isinbaev A.R., Beltyukov I.L., Tarasov B.A., Ivanov A.Yu. Swelling of Nitride Fuel under Different Experimental Irradiation Temperatures at the Early Burnout Stages. Izvestiya vuzov. Yadernaya Energetika. 2024, no. 1, pp. 87-95; DOI: https://doi.org/10.26583/npe.2024.1.07 (in Russian).