The shipments included spent fuel from Ewa and Maria reactors of the Atomic Energy Institute in Sverk. NNSA reports that all spent fuel of the Ewa reactor has been removed from the site. The reactor was reportedly shut down in 1995. The Maria reactor continues to operate using 36% HEU fuel supplied by Russia. According to the NNSA report, it is working with the Atomic Energy Institute to convert this reactor to LEU fuel.
Previous shipments of HEU fuel from Poland to Russia took place in August 2006 and August 2007. The August 2006 shipment in removed about 40 kg of fresh HEU fuel of the Maria reactor.
At the Nuclear Security Summit held in Washington in April 2010, Russia pledged to remove spent HEU fuel from five countries, Poland among them.