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A number of techniques are being considered that will be able to strip out 80% to 95% of the caesium from contaminated soil and other materials efficiently and without destroying the organic material in the soil. The caesium precipitated with ferric ferricyanide (Prussian blue) would be the only waste requiring special burial sites.
The aim is to get annual exposure from the contaminated environment down to 1 millisievert (m Sv) above background.
The most contaminated area where radiation doses are greater than 50 m Sv/year must remain off limits, but some areas that are currently less than 5 m Sv/year may be decontaminated, allowing 22,000 residents to return.
Caesium-137 in the environment is substantially anthropogenic (human-made).
By observing the characteristic gamma rays emitted by this isotope, one can determine whether the contents of a given sealed container were made before or after the first atomic bomb explosion (Trinity test, 16 July 1945), which spread some of it into the atmosphere, quickly distributing trace amounts of it around the globe.
This procedure has been used by researchers to check the authenticity of certain rare wines, most notably the purported "Jefferson bottles".
85.1% of metastable barium then decays to ground state by emission of gamma rays having energy 0.6617 Me V .
The salts of caesium are also soluble in water, and this complicates the safe handling of caesium. Test explosions "Simon" and "Harry" were both from Operation Upshot–Knothole in 1953, while the test explosions "George" and "How" were from Operation Tumbler–Snapper in 1952 Caesium-134 and caesium-137 were released into the environment during nearly all nuclear weapon tests and some nuclear accidents, most notably the Chernobyl disaster and the Fukushima Daiichi disaster.
Cobalt-60, , is preferred for radiography, since it is chemically a rather nonreactive metal and produces higher energy gamma-ray photons. As of 2005 and for the next few hundred years, caesium-137 is the principal source of radiation in the zone of alienation around the Chernobyl nuclear power plant.
This caused some caesium-137 from a measuring instrument to be included with eight truckloads of scrap metal on its way to a steel mill, where the radioactive caesium was melted down into the steel.
In March 2015, the Norwegian University of Tromsø lost 8 radioactive samples including samples of caesium-137, Am-241 and strontium-90.