Recent improvements in modelling fission gas release and rod deformation on metallic fuel in LMR

Metallic fuel design is a key feature to assure LMR core safety goals. To d ate, a large effort has been devoted to the development of the MACSIS code for metallic fuel rod design and the evaluation of operational limits under irradiation conditions. The updated models of fission gas release, fuel co re swelling, and rod deformation are incorporated into the correspondence r outines in MACSIS MODI. The MACSIS MOD1 which is a new version of MACSIS, h as been partly benchmarked on FGR, fuel swelling and rod deformation compar ing with the results of U-Zr and U-Pu-Zr metal fuels irradiated in LMRs. Th e MACSIS MOD1 predicts, relatively well, the absolute magnitudes and trends of the gas release and rod deformations depending on burn-up, and it gives better agreement with the experimental data than the previous predictions of MACSIS and the results of the empirical model. (C) 2000 Elsevier Science Ltd. All rights reserved.