Burnup Improvement Through Reshuffling of Fuel Bundles of the First Fuel Charge in CANDU-600

Abstract

This paper presents several fuelling strategies which can be used to increase the burnup obtained from the first fuel charge (first core load extracted) in the CANDU-PHW 600 MW(e) reactor. The fuelling schemes studied involve reshuffling the end bundles extracted from a channel on its first refuelling. Refuelling with various combinations of reshuffled end bundles and fresh fuel were tried. Each scheme was compared to the once through eight- bundle-shift bi-directional scheme which is the reference scheme at equilibrium burnup conditions. The comparison was made using a coarse mesh reactor model. For each fuelling scheme, reactor operation was simulated from zero FPD (Full Power Days) until one core load was extracted (usually around 350 FPD). The results show that it is possible to increase the average discharge burnup of the first charge by 11% whilst at the same time reducing the average fuelling machine visit rate by 8%. This increased discharge burnup results in a reduction of fuel consumption by about 500 bundles, which roughly corresponds to a saving of 1.5 million dollars.