Optimization of minor actinides bearing blankets with industrial fuel cycle constraints

International audienceHeterogeneous minor actinides transmutation is the process of loading neptunium, americium and curiumin dedicated targets, generally located at the core periphery, in order to transmute these long-livedheavy nuclides into shorter-lived fission products. This has a positive effect on long-term radiotoxicity ofthe spent fuel and on the short to medium term decay heat of the final waste packages. However, giventheir location at the core periphery in a low flux zone, these targets are generally loaded with a high contentin minor actinides in order to maintain acceptable transmutation performances. A significant part ofthe heavy nuclides produced by capture during irradiation being energetic alpha-emitters or strong neutronemitters, this leads to a very high activity in the irradiated targets which has negative impacts on thefuel cycle. In this paper, an optimization methodology of heterogeneous minor actinides transmutation isapplied to the fuel cycle case in order to assess the constraints limiting transmutation. It appears thattransportation of the fresh assemblies is the first limiting criterion due to the high decay heat of241Am. Sodium washing at the end of irradiation is the second limiting criterion. It is shown that the geometricaldesign on the target assembly is not a concern considering the current limitations on the fuelcycle. It is also shown that using current industrial limitations and plutonium feed, it is not possible toachieve equilibrium between production of americium in the core and consumption in the blankets. Itappears then that research should focus on the removal of fuel reprocessing limitations rather than standardassembly optimization