PNNL

Abstract

Data from radioactive tank waste samples from the Hanford site were analyzed to assess whether the trace metals present in these samples appeared to be incorporated into the bulk boehmite matrix, or whether they were simply intermingled with the bulk material and to what extent this incorporation impacted the dissolution rate of the boehmite. These results suggest that chromium is primarily blended into the bulk boehmite with a small fraction present on the surface of the solids. However, increasing the level of chromium incorporation 30-fold only resulted in an 8 % decrease in the dissolution rate of bohemite, suggesting the incorporation of chromium into these radioactive tank waste samples had a minimal impact on the rate of dissolution of boehmite. Iron was also found to incorporate into the tank waste boehmite solids, however the impact on the boehmite dissolution rate is indeterminant at this time, while silicon appears to be simply intermingled, and not blended into the boehmite crystals.