One unresolved problem with the Fukushima Daiichi disaster is the radioactive particles contamination worldwide, and especially in Japan. Dispersed low level contamination poses a particular challenge to those charged with its remediation.
Many techniques are not efficient below certain concentration thresholds or entail more severe impacts on certain environmental compartments than the contamination itself. In such cases justification for remediation may not be given on radiation protection grounds, but remediation may still be demanded by the public.
A Japanese research group says they have succeeded in developing a building material that could filter most radioactive cesium from contaminated water by using zeolite powder instead of sand.
Zeolites are microporous, aluminosilicate minerals commonly used as commercial adsorbents.” It has a negatively charged tridimensional framework because the silicon is replaced by aluminum in the tetrahedrons, and that is compensated by cations (positively charged ions) in the cavities of the structure (K, Na, Ca, Ba, Li…).
Since ionizing radiations, notably X and gamma rays are electromagnetic fields, it’s easy to understand how zeolite can positively interfere with ionic exchange mechanisms.
A research group at Kinki University’s Faculty of Engineering in Hiroshima Prefecture applied a method using plaster called “Shikkui” found in traditional Japanese architecture.
The traditional material usually mixes lime with sand, but the group used zeolite instead of sand. Researchers say that during tests that filtered cesium dissolved in water, the material absorbed over 99-percent of the cesium.
The group says the material could be used to safely store debris and soil contaminated by radiation by preventing radioactive substances from seeping out.
Researcher Atsushi Taga says the result was unexpected. He says he hopes the material will be used to store contaminated debris from the accident at the Fukushima Daiichi nuclear plant.
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