- Large boxes of powdered caesium 137, a powerfully radioactive
substance, are lost in the former Soviet Union. In the hands of terrorists,
just one would provide enough "dirty bomb" material to badly
contaminate large urban areas, forcing their evacuation and possibly their
abandonment.
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- These caesium sources are a major reason why the US has
committed at least $25 million in 2002 to an urgent effort to track lost
radioactive sources in former Soviet states, as New Scientist reported
on Thursday.
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- Media reports that the caesium was originally spread
on fields in secret Soviet agricultural experiments are wrong, says Melissa
Fleming,spokesperson for the International Atomic Energy Agency in Vienna,
which is helping to coordinate the recovery drive. That would have given
rise to vast tracts of contaminated farmland, and probably considerable
human exposure.
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- But the truth may be worse. The ceasium was in fact enclosed
within shielded boxes, and used as a source of gamma rays to irradiate
grain, to keep it from germinating in storage, says Abel Gonzales, director
of radiation and waste safety at the IAEA. The gamma rays were also used
to induce mutations in seeds, a common method for generating improved crop
varieties.
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- Very lucrative
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- But because the caesium was used entirely as a source
of radiation, it remained enclosed within the mobile gamma sources. Hence
it is all still there, and with a half-life of 32 years, much of it is
still very radioactive.
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- The project, named "Kolos" after the Russian
for an ear of corn, was large. "We have no idea how many of these
sources there are," says Gonzales.
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- That is bad, because each of them contained 3500 Curies
of caesium. "That is very, very big," says Gonzales. By comparison,
a caesium source lost from a hospital in Goiania, Brazil in 1987, which
killed four immediately and exposed dozens more to heavy doses of radiation
held only a few hundred Curies.
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- Unlike the solid Strontium-90 in lost nuclear power sources
that have been the subject of recent searches in the former Soviet Union,
Project Kolos's caesium was powdered, so in theory it would be easy to
pack into a "dirty bomb" - or several. These bombs use conventional
explosive to scatter radioactive material.
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- The sources were housed on trucks. But since the fall
of the Soviet Union, the trucks have been diverted, so their potentially
very lucrative cargoes could be anywhere, experts fear. US participants
in the joint Russian-US-IAEA drive to recover the sources say there will
be experts in the field in the next few weeks looking for clues.
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- http://www.newscientist.com/news/news.jsp?id=ns99992445
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