BNA Pellet Material Properties Test Program in Support of ACR-1000 Fuel Design

Abstract

The ACR-1000 CANFLEX-ACR fuel bundle design is an evolution of the 43-element CANDU6 CANFLEX Mk-4 fuel bundle. The centre ring of the CANFLEX-ACR fuel bundle consists of a single large-diameter element containing pellets of BNA in a stabilized zirconia matrix (with no fissile material), and is designed to control the coolant void reactivity during postulated accidents.The material properties of zirconia have been studied extensively. However, very little is specifically known about the material properties of a composition containing zirconia, yttria, dysprosia and gadolinia. Accurate assessment of material properties is important for determining conditions and behaviour of the centre element. Therefore a test program must be developed to provide correlations and tables of empirical values for the properties of various BNA pellet compositions. While in-reactor tests are important for confirming behaviour of this new material, the material properties test program focuses on out-reactor testing to determine thermal and mechanical properties, as well as to investigate the phase stability, oxidation-resistance and leaching behaviour. This paper provides an overview of this ongoing program.