Economic and safety improvement of nuclear fuel cycle by using nuclear fuel codes - 5033

The BaCo code was developed at CNEA for simulating nuclear fuel rods behaviour under irradiation The development of BaCo is focused on PHWR fuels, as Candu and Atucha ones, under irradiation and during storage conditions. It also keeps a good compatibility with advanced fuel materials, such as for example uranium nitride and carbide at least for illustrative and comparative purpose. The BaCo modelling of UO₂ pellets includes elastic deformation, thermal expansion, creep, swelling, densification, restructuring, relocation, cracks and fission gas release. For the Zry cladding, the code models elastic deformation, thermal expansion, anisotropic plastic deformation, creep and growth under irradiation. The structure and the modularity of the BaCo code allow the implementation of new models of material behaviour under irradiation. A special technique called 'multi-scale modelling of materials' has been implemented to deal with advanced materials and design. The validation of the code is being made through comparisons with experimental data from IAEA programs like CRP FUMEX I, II or FUMAC and with the results of other codes