Reprinted from Frontiers 2000.

Sweden’s R-2 Reactor was converted to low-enrichment uranium fuel.

A new nuclear fuel that will soon allow almost every research reactor in the world to convert to proliferation-resistant fuel is being developed by Argonne’s Reduced Enrichment for Research and Test Reactor (RERTR) program.

Approximately 250 nuclear research and test reactors in 57 nations play a vital role in medicine, agriculture and industry. For example, they provide neutrons for cancer therapy, medical isotope production and improved pharmaceuticals. They also produce tracer elements for pollution and waste migration studies. Through neutron radiography, these reactors help diagnose defects in metals and engines; through neutron scattering they assist the development of new magnetic and superconducting materials. The reactors also allow reactor fuels and materials testing, and training for reactor operators and international inspectors. Unfortunately, about half of these reactors are powered by fuels that contain highly enriched uranium; that is, uranium with a uranium-235 content of 20 percent or more that can be directly used to make nuclear weapons.

Argonne’s RERTR program is concentrating on developing a new, low-enrichment-uranium (LEU) fuel suitable for almost all the world’s research reactors. LEU fuel contains less than 20 percent uranium-235 and provides an isotopic barrier to weapons usability by rogue nations and terrorists. The new fuel is a dispersion of uranium-molybdenum (U-Mo) alloy in aluminum. Argonne is testing it in research reactors in the United States and in Europe.

By the end of 2005, we expect to qualify a very dense LEU fuel based on uranium-molybdenum alloy, said Armando Travelli, who manages the RERTR program. This fuel should meet all the main non-proliferation goals of the RERTR program with favorable implications for the reactors’ performance and research productivity. This new U-Mo fuel will enable the LEU conversion of reactors that cannot be converted today, he said. It will also ensure better efficiency and performance for all LEU research reactors and will allow the design of more efficient and powerful new advanced LEU research reactors.

The RERTR program plans to qualify the U-Mo dispersion fuel with an intermediate uranium density by the end of 2003. The future of several foreign research reactors that currently use LEU silicide fuel depends on reaching this intermediate goal. In 2006, the United States will no longer accept spent fuel from foreign research reactors. The spent fuel would then be sent to the COGEMA fuel-processing facility in France, but COGEMA does not process silicide fuel. LEU U-Mo fuel is acceptable to COGEMA and, if qualified by 2003, will give the reactor operators sufficient time to gain regulatory approval and to complete irradiation of their current fuel before the 2006 deadline.

The U.S. Department of Energy started the RERTR program in 1978 under Argonne leadership. The department was motivated by concerns that international traffic in highly enriched uranium fuel could provide opportunities for terrorists or rogue nations to divert some of this material to weapons use. Under the RERTR program’s guidance, 36 reactors in 22 countries have converted or are converting to RERTR-developed LEU fuel, and 21 new research reactors have been built or planned that use this fuel. In addition, six nations, including the United States, can now fabricate and supply research reactors with LEU fuels developed by the RERTR program, and three more nations are developing this capability.