New release of fuel performance codes, FRAPCON-3.5 and FRAPTRAN-1.5

New versions of the USNRC fuel performance codes, FRAPCON-3 and FRAPTRAN are available to members of the code users group. FRAPCON-3.5 and FRAPTRAN-1.5 include model improvements to various material property and behavior models such as gaseous swelling, primary creep, pellet relocation, cladding models, cladding ballooning, and ID oxidation. Various new capabilities have been added to increase the number of time steps, the axial nodes, and the radial nodes. The ability to model pellet chamfers has been added. The ability to specify variable axial node lengths and specify different enrichment, gadolinia content, and central hole size in each axial node has been added. Finally the capability to model refabrication of a rodlet following irradiation of a full length rod has been added to FRAPCON-3.5. This paper will describe the changes made in the new versions of FRAPCON-3 and FRAPTRAN. (author)