Recapturing Graphite-Based Fuel Element Technology for Nuclear Thermal Propulsion

ORNL is currently recapturing graphite based fuel forms for Nuclear Thermal Propulsion (NTP). This effort involves research and development on materials selection, extrusion, and coating processes to produce fuel elements representative of historical ROVER and NERVA fuel. Initially, lab scale specimens were fabricated using surrogate oxides to develop processing parameters that could be applied to full length NTP fuel elements. Progress toward understanding the effect of these processing parameters on surrogate fuel microstructure is presented. I. Introduction HE research presented in this report is a collaborative effort between Oak Ridge National Laboratory (ORNL) and NASA to recapture manufacturing technology for full length ROVER/NERVA graphite composite fuel elements. Nuclear thermal propulsion (NTP) fuel development has been intermittently ongoing since the late 1950’s and many of the original materials used in the early fuel development are no longer available. Also, the processing capability and the art associated with the production of full-length elements have been lost. The focus of the collaboration is to recapture the capability and expertise to produce representative fuel element test samples and iteratively scale up to full-length elements. To maximize efficiency, the work was separated into two tasks, extrusion development and coating development, which were conducted in parallel. At this stage in the program, the extrusion development task is focused on recreating a representative blend of materials, evaluating blending methods, and establishing an extrusion capability. The coating task is focused on developing processing conditions and equipment to establish ZrC coating capability. This report summarizes the accomplishments and progression toward these goals. It is important to note that the results and analyses presented here are in the early stages of research (TRL 3) and should be considered preliminary.