SPONTANEOUS combustion is not high on most people's list of worries, but when it happens to materials at one of the world's oldest and largest storage centres for weapons-grade uranium, it is a different matter.
On 22 September, the plastic wrapping around some uranium at the Y-12 National Security Complex in Oak Ridge, Tennessee, burst into flames as a technician was removing it inside a glovebox. Exposed to air, the uranium had heated up and ignited the plastic.
The fire took place in a large wooden warehouse built in 1944 to help the Manhattan Project, set up to develop nuclearweapons. The warehouse is one of the facility's main stores for its 400 tonnes of highly enriched uranium, and is now officially rated as a fire hazard, according to an assessment in 1996 by the US Department of Energy (DoE).
In this case the incident was contained, but a major fire would have catastrophic consequences. The DoE says a fire could result in uranium containers breaking open and releasing their contents in a plume of toxic, radioactive smoke. About 700,000 people live within a 160-kilometre radius of Y-12, including 174,000 in Knoxville 25 km away and 28,000 in Oak Ridge itself. In the worst case, the DoE estimates that the local population could receive radiation doses of up to 900 millisieverts, enough to cause nausea, hair loss and in some cases death.
The dangers at Y-12, revealed in a study this week, are not unique. Worldwide more than 1750 tonnes of highly enriched uranium have been produced over the last 62 years to supply bombs, submarines and research reactors. "Significant amounts are stored at dozens of sites in Russia and other countries, often inadequately accounted for, protected and controlled," says Morten Bremer Mærli, a nuclear expert from the Norwegian Institute of International Affairs in Oslo. "Many of the stores are old, some pose environmental threats and some may be at risk from terrorists. International standards are currently too weak to ensure safety and security."
But what is surprising about Y-12 is that the world's richest nation has allowed it to deteriorate to such a poor state.
It has been "festering for decades", says Robert Alvarez, a senior environmental adviser to the Clinton administration now with think tank the Institute for Policy Studies in Washington DC.
"While a considerable amount of attention has been drawn to dubious storage conditions in Russia and former Soviet states, long standing nuclear weapons material storage problems in this country pose unacceptable risks to workers and the public," he says. Alvarez is the author of the detailed study of safety at Y-12 due to appear in a forthcoming issue of the journal Science and Global Security, published by Princeton University. He reveals that the incident on 22 September is just the latest of 22 fires and explosions that have beset the Y-12 complex since 1997, a rate of about two a year.
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THIS ARTICLE APPEARS IN NEW SCIENTIST MAGAZINE ISSUE: 28 OCTOBER 2006
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