Candidate Near Term Fuel Options for Conventional and Bimodal NTR Engines

Abstract

The performance requirements for a conventional nuclear thermal rocket (NTR) engine are considerab ly different than those of a bimodal engine, where the system will operate under high power for thrusting for very short periods of time and under low power for electrical generation for years. Several candidate fuel systems have been extensively develope d for either a NTR engine or a power reactor over the past four decades, however, a true bimodal fuel system has never been manufacturedor demonstrated . The NERVA/Rovernuclear rocket engine development program performed extensive testing on uranium carb ide fuels utilizing a graphite matrix. Argonne and General Electric successfully developed cermet fuel system s for lower temperature applications using uranium dioxide in a tungsten matrix. This paper reviews the potential application of these two fuel systems to a bimodal NTR and outlines the development and qualification activities required to demonstrate adequate performance under demanding bimodal operating conditions .