A new route to the stable capture and final immobilization of radioactive cesium

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>Radioactive Cs released from damaged fuel materials in the event of nuclear accidents must be controlled to prevent the spreading of hazardous Cs into the environment. This study describes a simple and novel process to safely manage Cs gas by capturing it within ceramic filters and converting it into monolithic waste forms. The results of Cs trapping tests showed that CsAlSiO<SUB>4</SUB> was a reaction product of gas-solid reactions between Cs gas and our ceramic filters. Monolithic waste forms were readily prepared from the Cs-trapping filters by the addition of a glass frit followed by thermal treatment at 1000°C for 3h. Major findings revealed that the Cs-trapping filters could be added up to 50wt% to form durable monoliths. In 30–50wt% of waste fraction, CsAlSiO<SUB>4</SUB> was completely converted to pollucite (CsAlSi<SUB>2</SUB>O<SUB>6</SUB>), which is a potential phase for radioactive Cs due to its excellent thermal and chemical stability. A static leaching test for 28 d confirmed the excellent chemical resistance of the pollucite structure, with a Cs leaching rate as low as 7.21×10<SUP>−5</SUP> gm<SUP>−2</SUP>/d. This simple scheme of waste processing promises a new route for radioactive Cs immobilization by synthesizing pollucite-based monoliths.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cs gas was chemically adsorbed to the SA filter to form thermally stable CsAlSiO<SUB>4</SUB>. </LI> <LI> Monoliths were readily made from the Cs-SA filters by a simple thermal process. </LI> <LI> CsAlSiO<SUB>4</SUB> was effectively converted to pollucite during the synthesis of monoliths. </LI> <LI> The chemical resistance of pollucite was high, comparable to data of other studies. </LI> </UL> </P>