For several years, the United States and the Federal Republic of Germany (FRG) have engaged in a successful cooperative program to develop high temperature gas-cooled reactor (HTGR) fuel cycle technology. Recent tests in reprocessing pilot plant facilities at General Atomic Company have demonstrated the feasibility of performing HTGR head-end unit operations for both spherical (German) and block-type (American) fuel elements in a single process line. Because of an unexpected high fines generation and elutriation rate, extended fluidized bed primary burning of FRG fuel material was impossible to accomplish with the burner system and operating procedures optimized for U.S. fuel burning. Operational modification, including startup with a carbon-poor bed and reduction of the fluid-izing velocity, resulted in dramatic improvements in FRG fuel-burning behavior and allowed extended processing campaigns. Additional modifications to the fines recycle system and burner are recommended to optimize the system for processing of FRG fuels.