A spokesperson for the US Department of Energy (DOE) has told Physics World that Russia’s recent decision to end an agreement between the Rosatom nuclear agency and the DOE into the feasibility of converting Russian research reactors to low-enriched uranium (LEU) will have “no practical impact” on reactor conversion.
The agreement between the two agencies, which was initially suspended in 2014, was terminated earlier this month, with the Russian government saying it had done so following the US’s decision to end civil nuclear-energy co-operation with Russia in 2014. The Russian government also blamed “other hostile steps and statements”.
The US has been seeking to eliminate highly enriched uranium (HEU) from civilian research reactors worldwide since 1978. But the DOE spokesperson says that the National Nuclear Security Administration (NNSA) does not expect any impact on work to remove highly enriched uranium from third countries, as it “is covered by a separate agreement that still has bilateral support”.
Naturally occurring uranium contains less than 1% uranium-235 – the primary fissile isotope of uranium – by mass. But the proportion can be increased by enrichment, with HEU fuel containing at least 20% of uranium-235. Research reactors, however, often rely on “weapons-grade” uranium, which contains at least 90% uranium-235, to produce beams of neutrons that are intense enough for research purposes.
The US had predicted that the 74 reactors around the globe that still use HEU fuel would switch to LEU by 2018, although a recent report by the US National Academies of Sciences, Engineering and Medicine concluded that will now take until at least 2035.
Russia is home to 32 of the research reactors that still use HEU, with the US report citing non-technical factors as the main hindrance to their conversion. It claims that conversion “is not a high national priority for Russia” and that in recent years Rosatom and the US DOE “have severed nearly all ties”, with Russia no longer willing to accept US funding for conversions and the DOE curtailing interactions between scientists.
Before relations deteriorated, in 2014 Russia and the US successfully converted one reactor – the ARGUS reactor at the Kurchatov Institute in Moscow – from HEU to LEU fuel. The two nations also concluded that it was technically and economically feasible to convert five more.
Russia and the US have also been working together to remove HEU from other countries. At the end of September they announced that they had successfully repatriated 61 kg of Russian-origin HEU from the Maria Research Reactor in Poland, which was converted to LEU two years ago. Poland is now HEU-free.
Russia says that if it decides to convert further research reactors it will now “conduct this work independently”, although the government statement makes it clear this is not a priority. “We believe that the conversion of nuclear reactors from highly enriched to low-enriched uranium fuel in [Non-Proliferation Treaty] member states is not an end in itself,” it says. “In a number of cases, including medical-isotope production, HEU is most effective, and abandoning it does not make sense from a technological and economic standpoint.”
Russia has also suspended an agreement on nuclear- and energy-related research-and-development co-operation with the US, and an agreement that commits the two countries to eliminate parts of their weapons-grade plutonium stocks. In a statement, the Russian foreign ministry says it had suspended the plutonium pact in response to “unprecedented sanctions-related pressure”, hostile steps by the US since “the reunification of Crimea with Russia” and “an active build-up of NATO’s military infrastructure”.