Laboratory studies have indicated that pertechnetate (99TcO4-) can be reduced and captured into a solid solution of a-FeOOH, goethite (Um 2010). Goethite is a stable mineral and can significantly retard the release of technetium to the environment from the IDF. The laboratory studies were conducted using reaction times of many days, which is typical of environmental subsurface reactions that were the genesis of this new process. This study was the first step in considering adaptation of the slow laboratory steps to a larger-scale and faster process that could be conducted either within the WTP or within the effluent treatment facility (ETF). Two levels of scale-up tests were conducted (25? and 400?). The largest scale-up produced slurries of Fe-rich precipitates that contained rhenium as a nonradioactive surrogate for 99Tc. The slurries were used in melter tests at Vitreous State Laboratory (VSL) to determine whether captured rhenium was less volatile in the vitrification process than rhenium in an unmodified feed.
Revised: November 8, 2011 |
Published: October 23, 2011