The ACR-1000® fuel bundle design

The 43-element CANFLEX-ACR fuel bundle is used for the ACR-1000. This design is an evolution of the 43-element CANFLEX Mk4 fuel bundle. The bundle includes two different element sizes. The centre ring consists of one large diameter element, whereas the outer three rings consist of 42 elements with a smaller diameter. The outer three rings of fuel elements contain low enriched uranium (LEU) pellets while the central fuel element contains burnable neutron absorber (BNA) in a stabilized Zirconia matrix. The larger diameter of the centre element and the use of BNA pellets (with no fissile material) in the centre element are designed to control the coolant void reactivity during postulated accidents. The fuel bundle design is used for all stages of the life of the core, from the initial startup core through to the reference equilibrium core. During this evolution, the level of enrichment of the Uranium Dioxide pellets increases and the amount of burnable neutron poison in the central element changes. These changes are used along with a modified refuelling scheme to manage the increase in the exit burnup of the core to the equilibrium reference value. This paper will provide a description of the fuel bundle design. (author)