Ballooning experiments with VVER cladding

The results of single-rod and bundle ballooning tests with VVER (E110 type) cladding are presented. The comparative study of E110 and Zircaloy-4 showed a significant difference in behavior at 800 to 1000 degrees C. The local maximum of mechanical strength was observed at a low oxidation rate. The pressurization rate played a considerable role in the burst conditions. The rate of the temperature increase and the iodine pretreatment did not significantly influence the mechanical behavior of the fuel rods under accident conditions in the investigated range of parameters. The maximum blockage rate observed in the bundle tests remained below 80%. The experimental data were collected into a database for model development and code validation purposes.