On the origins and the evolution of the fuel-cladding bonding phenomenon in PWR fuel rods

Clément Ciszak (1, 2) , Lionel Desgranges (1) , Philippe Garcia (1) , Catherine Sabathier (1) , Laurent Fayette (1) , Sébastien Chevalier (2)

1 CEA - Commissariat à l'énergie atomique et aux énergies alternatives
2 ICB - Laboratoire Interdisciplinaire Carnot de Bourgogne

This study proposes a new and detailed description of the fuel-cladding bonding phenomenon occurring in PWR fuel rods. Very early and late bonding states were characterized on specimens of 35.3 GWd.tU−1 moderate burnup and of 64.5 GWd.tU−1 high burnup respectively. Results were then compared with those achieved on a re-created bonded situation obtained on a Zircaloy-4/hyper-stoichiometric UO2+x model materials diffusion couple. These results tend to indicate that a chemical adhesion is probably at the origin of the PWR fuel-cladding bonding. In addition, the progressive formation of ZrO2/UO2 interfacial circumvolutions observed with increasing burnup, which lead to the physical anchorage of ZrO2 and UO2, is likely to lead to their mechanical adhesion. Thus, the in-reactor ZrO2/UO2 bonding could be considered, since the occurrence of the first bonded situations, as an adhesion phenomenon owning two components: an initial chemical progressively strengthened by a second mechanical.

Mots clés: Spent fuel; Zircaloy; Fuel-cladding bonding; Model materials; Diffusion couple

Domaines: Matériaux

Clément Ciszak, Lionel Desgranges, Philippe Garcia, Catherine Sabathier, Laurent Fayette, et al.. On the origins and the evolution of the fuel-cladding bonding phenomenon in PWR fuel rods. Journal of Nuclear Materials, 2019, 520, pp.110-120. ⟨10.1016/j.jnucmat.2019.04.015⟩. ⟨hal-03198832⟩