Uranium Dioxide-Cladding Interactions. Axial Expansion of UO₂ Column in Fuel Elements

Irradiation experiments have been conducted to determine the axial expansion of UO₂ in fuel elements. The experiments included fuel segments with 304 stainless and Zircaloy-2 sheaths in self-supporting tubular geometries under boiling water conditions, as well as fuel elements with 304 stainless UO₂-supported geometries under superheated steam conditions. The relative UO₂ expansion during irradiation was measured by mechanical devices included in the fuel segments and by visual and other observations.