Determination of the hoop fracture properties of unirradiated hydrogen-charged nuclear fuel cladding from ring compression tests

Resumen

In this work, a new methodology is devised to obtain the fracture properties of nuclear fuel cladding in
the hoop direction. The proposed method combines ring compression tests and a finite element method
that includes a damage model based on cohesive crack theory, applied to unirradiated hydrogen-charged
ZIRLOTM nuclear fuel cladding. Samples with hydrogen concentrations from 0 to 2000 ppm were tested at
20 �C. Agreement between the finite element simulations and the experimental results is excellent in all
cases. The parameters of the cohesive crack model are obtained from the simulations, with the fracture
energy and fracture toughness being calculated in turn. The evolution of fracture toughness in the hoop
direction with the hydrogen concentration (up to 2000 ppm) is reported for the first time for ZIRLOTM
cladding. Additionally, the fracture micromechanisms are examined as a function of the hydrogen concentration.
In the as-received samples, the micromechanism is the nucleation, growth and coalescence
of voids, whereas in the samples with 2000 ppm, a combination of cuasicleavage and plastic deformation,
along with secondary microcracking is observed.