Modelling of a moving bed furnace for the production of uranium tetrafluoride. Part 2: Application of the model

• Published in: Chemical engineering science 2003-06, Vol.58 (12), p.2629-2642
• Main Authors: Dussoubs, B., Jourde, J., Patisson, F., Houzelot, J.-L., Ablitzer, D.
• Format: Article
• Language: English
• Subjects: Applied sciences; Energy; Exact sciences and technology; Fuels; Gas–solid reactions; Heat and mass transfer; Kinetics; Mathematical modelling; Moving bed; Nuclear fuels; Numerical simulation; Preparation and processing of nuclear fuels; Production of uranium tetrafluoride
• ISSN: 0009-2509; 1873-4405
• DOI: 10.1016/S0009-2509(03)00121-0

The French nuclear fuel making route uses, prior to enrichment, uranium tetrafluoride UF 4 obtained from the reduction, followed by hydrofluorination of uranium trioxide UO 3. These two steps are carried out in a specific reactor known as a moving bed furnace. We developed a steady-state numerical model of the moving bed furnace, described in Part 1. In the Part 2, calculation results for a reference set of operating parameters of the furnace are presented in term of temperature, reaction rates, solid and gas compositions. Results analysis enlightens the detail of the furnace behaviour in its different zones. Unknown features have been revealed, such as thermodynamic limitation of the hydrofluorination reaction in the hot core of the moving bed. A sensibility study of various operating parameters shows how some can influence the UF 4 quality and underlines the strong coupling between the different zones of the furnace. Finally, the model is applied to define an optimal temperature progression in the furnace and suggests geometrical modifications. Besides, the validity of using the law of additive reaction times for calculating the reaction rates in such a reactor model has been checked for the first time against a numerical grain model.