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Evaluation of Cesium Sujcotitanates as an Alternative Waste Form

Published online by Cambridge University Press:  03 September 2012

Yali Su
Affiliation:
Pacifie Northwest National Laboratory, Richland, WA 99352
M. Lou Balmer
Affiliation:
Pacifie Northwest National Laboratory, Richland, WA 99352
Bruce C. Bunker
Affiliation:
Pacifie Northwest National Laboratory, Richland, WA 99352
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Abstract

Silicotitanate ion exchangers are potential materials for the removal of radioactive Cs and Sr from tank wastes. In this paper the viability of direct thermal conversion of Cs-loaded silicotitanates to an acceptable high level waste form has been examined. Results show that in aqueous solutions, the Cs leach rates of crystalline silicotitanates (heat treated at 800°C) are 0.04, 0.18, 0.4 g/m2day for Cs loadings of 1, 5, and 20 wt%, respectively. Heating the Cs-loaded (up to 20 wt %) silicotitanates at or above 900 °C for 1 hour further reduces the Cs leach rates to approximately zero (beyond the lppm detection limits). Moreover, Cs volatilization was found to be < 0.8 wt% at temperatures as high as 1000 °C. These results suggest that thermally converted silicotitanate ion exchangers exhibit excellent chemical durability (comparable to or better than borosilicate glass) and thus, have great potential as an alternative waste form.

Type
Research Article
Copyright
Copyright © Materials Research Society 1997

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