Sr/TRU removal from Hanford high level waste

The originally proposed removal process for strontium and transuranic speci es from 241-AN-102 and 241-AN-107 Hanford waste tank supernates was a co-pr ecipitation method. In initial testing, the slurry formed during the stront ium and ferric nitrate co-precipitant additions was not filterable. A serie s of statistically designed tests were performed to evaluate the variables responsible for this poor filterability. These tests also explored strategi es to improve the associated decontamination efficiency of the treatment pr ocess. These tests revealed that filterability is negatively influenced by ferric ion added to co-precipitate actinide and lanthanide species. The con centrations of sodium and organic complexants were observed to influence de contamination of the supernate. Furthermore, the amount of at least one org anic complexant was correlated to the poor filterability. The americium dec ontamination factors measured following the maximum iron nitrate addition w ere marginal at levels of precipitant addition that are of practical intere st. Based on these results, alternative precipitation schemes were investig ated. Reported here is the chosen replacement process, a permanganate preci pitation process. A statistically designed series of experiments examined t he relationship between three responses and five precipitation parameters. The three responses are precipitate filterability, strontium decontaminatio n, and plutonium decontamination. The parameters varied were the initial so dium and hydroxide concentrations of the waste, and the amount of calcium, strontium, and permanganate introduced. The results reveal an optimum set o f conditions for decontamination of strontium and plutonium as well as impr oved filterability.