The shipment was part of Global Threat Reduction Initiative, a tri-lateral effort between Russia, the United States and the International Atomic Energy Agency to secure materials that could be vulnerable to terrorists seeking to build nuclear or radiological weapons.

Of special concern is that uranium located at research reactors throughout the world, many of which are located on university campuses or other poorly secured research locations.

Thirteen casks holding about 155 kilograms of spent fuel were moved out of the Budapest Research Reactor in late September, beginning a three-week shipment by truck, rail and ship to Russia’s nuclear material storage site at Mayak in the Southern Urals. Previous shipments had been sent to the Dmirovgrad storage and research facility east of Moscow.

“It was a big shipment, the biggest one we’ve ever done,” said Kenneth Baker of the US National Nuclear Security Administration, AP reported . ”It was basically enough to make six nuclear weapons.”

“This shipment of highly enriched uranium from Hungary is the largest shipment of HEU spent fuel under NNSA’s Global Threat Reduction Initiative,” said NNSA Administrator Thomas D’Agostino in a press release today.

“The outstanding cooperation between the United States, Hungary and Slovenia in removing and securing this dangerous nuclear material exemplifies our strong international commitment to global threat reduction and nonproliferation.”