3D Assessments for Design and Performance Analysis of UO2 Pellets

Abstract

The geometry of a fuel pellet is a compromise among the intention to maximize UO₂ content and minimize the temperature profile taking into account the thermo-mechanical behavior, the economy and the safety of the fuel management during and after irradiation. 'Dishings', 'shoulders', 'chamfers' and/or 'a central hole' on a cylinder with an improved l/d relation (length of the pellet / diameter) are introduced in order to optimize the shape of the pellet. The coupling of the BACO code and the MECOM tools constitutes a complete system for the 3D analysis of the stress-strain state of the pellet under irradiation. CANDU and PHWR MOX fuel will be used to illustrate the qualitative agreement between experimental data and calculations.