Enhanced reactor core design and safety evaluation for the final cycles of Belgian nuclear power plants

Abstract

The Belgian nuclear power plants, owned and operated by Electrabel, are approaching the end of their operational lifespan, as per their initial design. Tractebel, as the Owner’s Engineer in charge of fuel management for these units, has maximized the energy use of the existing fuel assemblies, either in the core or in the storage pool, to minimize the need for introducing fresh fuel assemblies in the final cycles. Tractebel’s in-house Loading Pattern Optimizer (LPO) helped in determining the optimum core reloads incorporating sufficient safety margins. The safety evaluation of these cores showed some distinctive features compared to prior reloads containing normal batches of fresh assemblies. Therefore, complementary safety evaluations in addition to the standard cycle specific evaluation were performed and approved by the Belgian Safety Authorities. This paper introduces Tractebel’s improved core design tools and processes, outlining the approach to optimize the reactor core design and providing insights into the safety evaluation methodology employed for the final cycles while avoiding the use of fresh fuel assemblies.