Preparation and Characterization of SIMFUEL: Simulated CANDO High-Burnup Nuclear Fuel

Abstract

To better understand the behaviour of high-burnup nuclear fuel, unirradiated pellets simulating the composition and phase microstructure of 3 and 6 at% burnup UO₂ fuel (SIMFUEL) have been prepared and characterized. Eleven stable elements, representing the non-volatile fission products, were co - ground with UO₂ to a submicrometre scale, spray-dried, pressed and then sintered to achieve phase equilibrium and form high-density pellets. In this manner, specimens with negligible radioactive fields can be quickly and economically prepared for detailed studies relating to fuel performance and storage.

The resulting urania-based matrix was characterized in terms of composition and crystal unit cell size. Spherical, metallic Mo-Ru-Rh-Pd alloy precipitates were found uniformly dispersed throughout the matrix. A finely precipitated, BaZrO₃-type, cubic perovskite phase was observed decorating the matrix grain boundaries.

The results confirm the excellent replication of chemical composition and phase microstructure of high-burnup CANDU nuclear fuel by SIMFUEL specimens.