Russia has removed highly-enriched irradiated liquid nuclear fuel from Uzbekistan’s IIN-3M research reactor. Moscow-based Sosny, which develops technologies for the preparation of used nuclear fuel for reprocessing or storage, said the shipment was completed on 24 September.

The fuel comprises 4.2kg of U-235 in a solution of 90% highly enriched uranium (HEU). The IIN-3M solution reactor operated as part of the Foton radiation-technological complex in Tashkent. Russian regulator Rostechnadzor issued a licence for the acceptance of the equipment and the reprocessing of the liquid HEU fuel at the the Mayak Production Association in the Chelyabinsk region, Sosny said.

The IIN-3M is an unusual research reactor in which the fuel and the moderator are mixed together to form a homogenous liquid. It could operate in both steady-state power level or pulsed to different peak power levels, offering a wide range of possibilities for researchers. It has been used for the testing of semiconductors and other devices since its start-up in 1975.

It was shut down in June 2013 after Uzbekistan, in agreement with the US Department of Energy’s National Nuclear Security Administration, asked the IAEA to assist in developing a decommissioning plan. The Uzbek government then decided to decommission the reactor along with the rest of the Radiation and Technological Complex and approved the strategy of "immediate dismantling with subsequent unrestricted use of the site". In July, the IAEA signed two contracts with international consortia led by the Institute of Nuclear Physics in Tashkent for the removal of disused radioactive sources and for decommissioning of the site. The work is expected to take about 32 months with the support of Uzbekistan and international donors.

Removal of Russian-made highly-enriched uranium fuel from foreign research reactors takes place under the Russian Research Reactor Fuel Return (RRRFR) Programme, which is supported by the USA and the International Atomic Energy Agency (IAEA). The programme was launched in 2001 and is expected to run until 2024. It covers Belarus, Bulgaria, Hungary, Vietnam, Germany, Kazakhstan, Latvia, Libya, Poland, Romania, Serbia, Uzbekistan, Ukraine and the Czech Republic. Russia and Uzbekistan signed an intergovernmental agreement in 2014 specifying that Russia would import used research reactor fuel for reprocessing. The output from the reprocessing, including plutonium and uranium, will remain in Russia, which will use, store or dispose of the materials.

The shipment was "the first removal operation of irradiated liquid HEU fuel, and represents a historic milestone for the RRRFR programme, which has facilitated the transfer of nearly 2160kg of former USSR-supplied HEU from 14 countries to Russia in 61 shipments," IAEA said. Sosny said some 27 litres of liquid used nuclear fuel was transferred to a TUK-145/C package containing a Skoda VPVR/M cask inserted in an energy-absorbing container. It was delivered to Russia by an An-124 cargo plane. All operations related to the certification and arrangement of shipment, were performed under the control of the Department for Nuclear and Radiation Safety and the Organization of Licensing and Approval Activities, part of Russian state nuclear corporation Rosatom.

Photo: The truck carrying the package with the container of liquid high enriched uranium (HEU) fuel l from the IIN-3M Foton research reactor, Uzbekistan is now HEU-free. (Photo: S. Tozser/IAEA)