Alissa Tabirian
NS&D Monitor
2/5/2016

Highly enriched uranium (HEU) minimization in civilian research reactors is more difficult and progressing more slowly than previously expected, according to a study released last week by a National Academy of Sciences committee. The study said the timeline for global elimination of HEU use in civilian reactors and reactor conversions to low-enriched uranium will be “dramatically expanded” compared with time estimates from five years ago. While the National Nuclear Security Administration’s (NNSA) fiscal 2009 budget request forecast a 2018 project completion date, the study said, the latest estimates suggest the project will actually be completed in 2035.

Seventy-four research reactors worldwide currently use HEU fuel to operate. Eight of those are in the U.S. The report noted that 28 reactors have either been shut down or converted from HEU to LEU since 2009.

The study said the NNSA’s Material Management and Minimization Office of Conversion nearly doubled its program scope for conversion since 2005, and “has underestimated the challenges in developing and qualifying LEU fuels for high performance research reactors.” This has been a factor in recent years’ slow progress, the study said, noting that “the last research reactor conversion in the United States was in 2009, and the rate of conversions worldwide has decreased.” The lack of conversions in the U.S. since 2009, it said, “could call into question the level of U.S. commitment to conversion of its own reactors.”

This has been in part due to the difficulty of developing the high-density fuels needed to replace HEU in research reactors, as well as some political challenges involving Russia’s unwillingness to convert its own research reactors.

The U.S. fuel type faces an uncertain timeline due to manufacturing challenges, as the nation’s fuel development effort “requires fabrication methods qualitatively different from those used for any existing fuel,” the study said. The conversion of many high-performance research reactors requiring high-density fuels must not “significantly affect a reactor’s safety, performance, or operations,” a standard that presents technical challenges and extends the timeline for conversion, the study said.

Meanwhile, Russia has not indicated that it considers domestic research reactor conversion a national priority, despite housing over 40 percent of the world’s HEU-fueled civilian research reactors. Previous U.S.-Russian collaboration on research reactor conversion has come to an end and “only limited interaction remains,” the study found.

The study recommended development of a 50-year interagency strategy to outline options for non-HEU civilian reactor fuel sources, the continued development of high-density LEU fuel, the pursuit of an interim solution to reduce civilian use of weapon-grade material, and continued engagement between U.S. and Russian scientists on collaborative HEU minimization opportunities.