The IAEA and Serbia are preparing to remove two and a half tons of spent nuclear fuel from a shuttered research reactor site in Vinca. They will need to stabilize and repackage the radioactive material before being able to transport it to Russia.

A soft summer rain falls on a decrepit, rusting warehouse in the suburbs of Belgrade, Serbia. From the outside, all appears normal, nothing more than a shabby storehouse set against a small patch of trees. But inside, a pile of decades-old radioactive waste in deplorable condition has sat for decades, posing a threat to the health and safety of people and the environment. More than a thousand sealed radioactive sources remain inside - a half-century´s stock of radioactive refuse from the former Yugoslavia and Serbia. But the full picture of what´s inside this radioactive storehouse is a mystery, since precise records haven´t been kept.

Such is the scene at the Vinca Institute of Nuclear Sciences, a large research campus that served as the nerve center for former Yugoslavia´s nuclear research activities since the late 1940s.

Just a few kilometres from the Danube, the site has endured different periods of upheaval and influence, including varying degrees of Cold War-era intervention by the US and the Soviet Union. In 1959, the USSR supplied Vinca with the nuclear fuel and technical assistance to construct Vinca´s "RA" reactor, a 6.5 megawatt, heavy-water moderated research reactor capable of using fuel highly enriched in U235. The RA reactor was actually the second to operate at Vinca, and was preceded by the country´s first nuclear reactor, a heavy-water zero-power critical assembly (which is still in operation). There has been much speculation as to the original intentions for the facility under Yugoslavia´s then-leader Josip Broz Tito, and some research seems to indicate that a modicum of weapons research may have been conducted at Vinca in its early days.

Changes in government, the breakup of Yugoslavia, and the NATO bombing campaign in 1999 are all factors that conspired to keep Vinca´s management, direction, and focus in a constant state of flux. These dynamics brought Vinca to where it is today; and serve as a prime example of capable scientists and sophisticated equipment falling prey to political winds of change.

Concerns about Vinca on the part of the international community grew in the mid-1990s, when IAEA teams were dispatched upon Serbian request to inspect the site. These visits were instrumental in alerting the outside world about the state of the nuclear fuel on site, and the inherent risk to health and safety of those around Vinca.

As part of the IAEA and global community´s push to support reduced enrichment for research and test reactors, along with concerted efforts to return highly enriched uranium (HEU) fuel to the country of origin, an extraordinary level of international cooperation has coalesced to clean up Vinca.

The first major step in the Vinca project took place earlier this decade, when the most urgent threat to proliferation was dealt with. In 2002, an international operation to return 48 kilograms of unirradiated HEU fuel of Soviet-origin came about after protracted negotiations between then-Yugoslavia, the US, Russia, the IAEA, and other parties. The transport of the fuel was conducted amid intense security, with over 1200 armed guards ushering a convoy of trucks to the Belgrade airport for a flight to Russia, where the HEU would then be down-blended to a low-enriched form. IAEA safeguards inspectors watched over the procedure by gauging the fissile material, inspecting records, and applying seals to the shipping containers.

Since return of the unirradiated HEU, the foremost priority has been to deal with two-and-a-half tons of Russian-origin irradiated, spent nuclear fuel elements, which were initially used in the RA reactor. As the reactor last went critical in 1984, the SNF has been stored for decades in aluminium barrels in an adjoining spent fuel pool. However, the pool´s water chemistry has been poorly maintained, leading to corrosion of the fuel element´s aluminium cladding and leakage of fission products into the storage pool, though not into the environment. The water´s condition is further degraded by an accumulation of sludge, increasing the pool´s turbidity and lending it an inky black colour.

So the push is now on to repackage and repatriates the spent fuel for return to Russia, and the strong support and involvement of the Serbian Government has been instrumental in moving this project forward. An agreement between Serbia and Russia that governs the transfer of the fuel was signed this past June, and work is set to begin in autumn. Yet the task is fraught with complexities, and long lists of preparatory steps need to be taken to facilitate the fuel repacking and removal work.

IAEA Director General Mohamed ElBaradei visited the facility in early July 2009, to assess the progress at Vinca. "The unused nuclear waste is in poor condition and needs to be moved as soon as possible. The situation is under control for now, but it could be very dangerous from a safety and security point of view," he commented.

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