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Cesium Release From Tungstate and Titanate Waste Form Materials in Simulated Canister Corrosion Product‐Containing Solutions
Author(s) -
Luca Vittorio,
Zhang Yingjie,
Drabarek Elizabeth,
Chronis Harriet
Publication year - 2007
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2007.01750.x
Subject(s) - hollandite , leaching (pedology) , hematite , inorganic chemistry , ceramic , materials science , tungsten , oxide , tungstate , zirconolite , ilmenite , redox , corrosion , chemistry , metallurgy , nuclear chemistry , mineralogy , pyrochlore , environmental science , phase (matter) , organic chemistry , soil science , soil water
The leaching of two potential 137 Cs waste form ceramics (Cs‐containing hexagonal tungsten bronze (HTB) and hollandite) has been investigated in Fe(NO 3 ) 3 solutions of increasing concentration at 150°C over a period of 4 days. These ceramics contain within their structures reduced Mo 5+ /W 5+ and Ti 3+ species for the HTB and hollandite, respectively, which therefore might render them susceptible to oxidation‐induced leaching. Elucidation of the extent and the mechanism of leaching of the Cs from these ceramics in the REDOX active iron nitrate medium has been investigated. Cesium (Cs) leached severely from both the Cs‐loaded HTB and hollandite materials in iron nitrate solutions with virtually all of the immobilized Cs being extracted from both waste form materials in a period of 4 days at 150°C. In the case of hollandite, conversion to ilmenite and hematite was observed at low concentrations and was virtually complete in 0.5 mol/L Fe(NO 3 ) 3 over 4 days. In the case of the HTB, all of the Cs was extracted presumably by an ion‐exchange mechanism because the structure of this oxide remained intact and iron was found in the composition. Iron oxide with a hematite structure was also easily observed in the reacted sample at high solution iron concentrations. It is shown that the leach resistance of the Cs‐containing HTB can be improved by substitution of up to 20% Ti for W.