Modelling of breakaway swelling in intermetallic fuels during low-temperature irradiation

• Published in: Journal of nuclear materials 2022-01, Vol.558, p.153362, Article 153362
• Main Authors: Polovnikov, P.V., Tarasov, V.I., Veshchunov, M.S.
• Format: Article
• Language: English
• Subjects: Coalescence; Coalescing; Collisions; Exact solutions; Fuels; Growth rate; Intermetallic compounds; Irradiation; Low temperature; Nuclear fuels; Pores; Qualitative analysis; Swelling
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2021.153362

A new interpretation of the breakaway swelling observed in high-density dispersion fuels (U6Fe, U3Si, etc.) under irradiation in research reactors is proposed on the base of Mansur's pore coalescence mechanism for randomly distributed immobile pores owing to their growth and pair impingement. This mechanism was further developed in the previous papers of the authors by considering triple and multiple collisions and was modified in the current paper in application to equilibrium gas-filled pores (bubbles). New analytical solutions in the mean-field approximation for the case of pair and triple collisions of equilibrium pores at the early stage of irradiation (with the swelling less than 50–60%) are presented. For higher swellings it is necessary to use a more accurate statistical approach, based on kinetic Monte Carlo calculations and considering multiple collisions of growing pores.  It is shown that at high burnups, a sharp increase in the growth rate of the fuel swelling begins at a relatively high value of the fuel swelling (about 60%), in a qualitative agreement with observations for various intermetallic compounds.