Programs at the Idaho National laboratory (INL) seek to develop nuclear ceramic fuels for salt cooled reactors, modular reactors, and as replacements for current commercial reactor designs. Fuel and cladding irradiation tests are performed at the INL’s Advanced Test Rector (ATR). The basic experimental assembly, referred to as a rodlet, consists of fuel pellets seal welded into a clad tube with solid endcaps using a laser welder.
Stainless steels and other heat resistant carbon steel alloys are attractive as cladding materials for these experiments. While these alloys have been shown to have high weldability, the unique geometry of the rodlet, usually a solid endcap welded to a thin-walled tube, can lead to defects in the welds. Laser welding methods, parameters, and challenges will be presented in the context of better understanding small geometry welding for these novel cladding materials.