J. Phys. IV France
Volume 105, March 2003
Page(s) 339 - 346

J. Phys. IV France
105 (2003) 339
DOI: 10.1051/jp4:20030205

A unified model to describe the anisotropic viscoplastic behaviour of zircaloy-4 cladding tubes between 320 °C and 400 °C from an unirradiated state to high fluence and under fast neutron flux

P. Delobelle1, F. Richard1 and S. Leclercq2

1  Université de Franche-Comté, LMARC, UMR 6604 du CNRS, 24 rue de l'Épitaphe, 25000 Besançon, France
2  EDF, Centre des Renardières, Direction des Études et Recherches, Département MTC, BP. 1, Ecuelles, 77250 Moret-sur-Loing, France

This paper proposes a damaged viscoplastic model to simulate, for different isotherms (320, 350, 380, 400 and 420°C), the out-of-flux anisotropic mechanical behavior of Zircaloy-4 claddings in a stress relieved state over the fluence range 0-85.10 24 nm -2 ( $\rm E>l$MeV). The model, identified from uni and biaxial tests conducted at 350 and 4000°C, is validated from tests made at 320, 380 and 420°C. This model is able to simulate strain hardening under an internal pressure followed by a stress relaxation period, since the loading produces an interaction between the pellet and the cladding (thermal creep). Both the integration of a scalar state variable, characterizing the damage caused by a bombardment with neutrons, and the modification of the static recovery law allowed us to simulate the fast neutron flux effect (irradiation creep).

© EDP Sciences 2003