Nearly 90 kilograms of high-enriched uranium (HEU) fuel has been returned to Russia from Poland's only operating research reactor, which is now running on low-enriched uranium (LEU) fuel.

A total of 27 kilograms of fresh HEU fuel and 61.9 kilograms of used HEU fuel have been shipped from Poland's Maria reactor to Russia in a secure operation under the supervision of International Atomic Energy Agency inspectors. The return of the fuel to its country of origin, and the conversion of the reactor to LEU fuel, has been carried out under the auspices of the US National Nuclear Security Administration (NNSA)'s Global Threat Reduction Initiative (GTRI).

Maria, a 30 MWt pool-type research reactor, is located at Swierk near the town of Otwock. It has operated since 1974, and carries out a variety of research functions as well as manufacturing radioisotopes for medicinal, research and industrial use. Like many of the world's research reactors, Maria - named in honour of Polish-born Marie Curie - was originally built to run on HEU fuel enriched to over 20% uranium-235. However, HEU fuel presents a possible proliferation risk, as uranium at 20% enrichment could potentially be used to make a crude nuclear weapon. The GTRI is the latest evolution of international efforts seeking to reduce this risk by converting research reactors to low enriched uranium (LEU) fuel and repatriating spent and unused HEU fuel to its country of origin - either the USA or Russia - for secure storage and ultimately disposal.

The NNSA worked with Poland's National Centre for Nuclear Research (NCBJ) to complete the conversion of Maria to LEU fuel by providing technical, analytical and licensing support. The HEU that has been returned from Poland to Russia will be downblended to LEU fuel for use in civilian nuclear power plants. LEU is not suitable for making a nuclear weapon, and so is not seen as a proliferation risk.

NNSA deputy administrator Anne Harrington described the conversion of the reactor to LEU fuel and the removal of nearly 90 kilograms of HEU as "significant achievements" in the administration's efforts to ensure HEU "cannot fall into the wrong hands."

The consignment of spent and fresh HEU fuel is the second to be returned from Poland to Russia under GTRI. Over 450 kilograms of used and fresh fuel from Maria and the shut down Ewa research reactor was returned to Russia in 2010 in a major operation involving five separate shipments.

Maria can now join NNSA's list of 82 reactors around the world that have either converted to LEU fuel or are verified as shut down.

Source: World Nuclear News