September 7, 2011


Japanese Institute Develops Material to Immobilize Radioactive Cesium

Keywords: Chemicals Ecosystems / Biodiversity University / Research institute 

The National Institute for Materials Science (NIMS) of Japan announced on May 18, 2011, that it has developed a new material that enables long-term immobilization of highly concentrated cesium. The development is expected to contribute to progress in the technology for treating radioactive cesium isotopes.

Cesium 137, a radioactive cesium isotope, has a long half-life of 30 years and is highly soluble in water. In order to prevent its diffusion into the environment, it would be effective to trap it in a thermally- and chemically-stable solidified compound and bury it deep underground. Researchers, therefore, have been seeking a solid compound that is compact, can trap cesium in high concentrations, and immobilize it in a stable form for a prolonged period.

A research group of NIMS has achieved containment of highly concentrated cesium in titanate crystals prepared under ordinary pressure from titanium oxide, which has thermal and chemical stability. Furthermore, they have proved that titanate crystals excel in confining cesium due to their particular structure that effectively inhibits the cesium from leaching.

High-level radioactive waste contains strontium 90 and many toxic radioactive elements. It has been revealed that strontium can also be contained and disposed of in thermally- and chemically-stable titanate monocrystals, similarly to the treatment of cesium. Further utilization of the study is expected.

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The National Institute for Materials Science (NIMS) official website