The US National Nuclear Security Administration (NNSA) on 21 December submitted to the US Nuclear Regulatory Commission (NRC) a preliminary report on uranium-molybdenum (U-Mo) monolithic fuel that will enable the conversion of six US research reactors from highly enriched uranium (HEU) to low-enriched uranium (LEU). The report contains data on the performance of the fuel in a reactor under a variety of conditions.
The US high-performance research reactors awaiting conversion include:
- the Advanced Test Reactor and the Advanced Test Reactor Critical Assembly, both at Idaho National Laboratory;
- the High Flux Isotope Reactor at Oak Ridge National Laboratory; the Massachusetts Institute of Technology Reactor (MITR);
- the National Bureau of Standards Reactor in Maryland; and
- the University of Missouri Research Reactor.
MITR, a light-water-cooled and moderated, heavy-water reflected reactor, currently uses fuel enriched to 93%. Conversion of MITR will eliminate the transit of about 3kg of HEU fuel a year, according to NNSA. The preliminary safety analysis report submitted to the NRC shows that the MITR can safely operate using the new LEU fuel. Based on feedback from the NRC review of the report and the ongoing tests of the LEU fuel, MIT will submit a final safety analysis report. Following NRC approval, conversion of MITR to the qualified LEU fuel will begin.