Minimization of the commerce in civilian HEU and its use in research reactors worldwide, together with the return of research reactor spent nuclear fuel and HEU waste from isotope production to safe and secure facilities in their countries of origin, will help to reduce proliferation risks. The committee finds that the GTRI has made substantial contributions to these minimization and return goals: The period 1978–2004 was marked by slow but steady progress, whereas progress accelerated during the period 2004 to the present. The committee recommends that the GTRI be continued until research and test reactors worldwide have converted fuel and targets to LEU or permanently shut down and their HEU fuel has been returned to the country from which it originated.

Despite these successes, the committee finds that the program faces several challenges. First, the startup and continued operation of the HEU-fueled FRM II reactor in Germany sets an unfortunate precedent for possible future construction of HEU-fueled research reactors. Second, there are 78 HEU-fueled research and test reactors operating throughout the world that are out of scope of GTRI. The majority of these are old and by the end of the current GTRI program their numbers are likely to be much fewer. Nevertheless, from a purely technical perspective, it is difficult to understand why most of these reactors cannot be converted. The committee recommends that DOE-NNSA, in cooperation with IAEA, make an effort to maintain an up-to-date and comprehensive database of the research and test reactors of the world, including large pulse reactors, critical facilities, and reactors with a defense-orientated mission.²⁸ The committee also recommends that these reactors should be investigated to determine if it is feasible to convert them to LEU; if so, they should become in-scope for the program.

Finally, the committee finds that converting Mo-99 production worldwide to LEU will continue to be a major challenge for the reasons described in detail elsewhere in this report. Chapter 10 lists some actions that DOE and other parties can take to accelerate the conversion to LEU-based Mo-99 production. The committee recommends that the RERTR increase its focus on eliminating the HEU wastes from Mo-99 production from U.S.-origin HEU, by examining options for downblending this waste or encouraging its return to the United States.