[en] The progress of the Reduced Enrichment for Research and Test Reactor (RERTR) program since 1978 is reviewed with special emphasis on last year's progress. New advanced fuels are being developed with uranium densities well in excess of the 4.8 g/cm³ earlier achieved by the program. Analytical studies to assess the feasibility of using LEU have been in progress during the past year for several reactors including the HFBR (U.S.), HFIR (U.S.), BMRR (U.S.), MARIA (Poland), LVR-15 (Czech Republic), VVR SM-10 (Hungary), and FRM-II (Germany). Twenty-eight reactors in seventeen countries have been or are being converted to LEU fuels. Conversions of the IAN-R1 (Colombia), SL-2 (Canada), and IEA-R1 (Brazil) were completed during the past year. Conversion of the BER-II (Germany) began. Four spent research reactor fuel shipments to the Savannah River Site, containing 822 fuel assemblies, have been completed in accordance with the new U.S. spent fuel policy. Good progress has been made in the development of LEU-based processes to produce ⁹⁹Mo, and in the Russian RERTR program. (author)