Abstract: Technetium-contaminated nickel is decontaminated by electrolytically dissolving nickel having a gross beta activity of at least about 74 Bq in a sulfuric acid solution having a pH between about 0.5 and 2.0. The applied voltage is from 2.0 v/cell to 5.0 v/cell for dissolving the nickel and contaminants while cathodically producing hydrogen gas. Technetium (+4) species in the acid solution is oxidized to the technetium (+7) species. The pH of the technetium-containing acid solution is adjusted to between 2.5 to 4.5. Particulates in the acid solution are filtered from the solution for reducing the gross beta activity of the acid solution to less than about 50 Bq/gm. Radioactive ions (including technetium complexes) are sorbed in an anionic exchanger and a cationic exchanger for reducing the gross beta activity of the acid solution to less than about 20 Bq/gm. After verifying the gross beta activity of the acid solution, the acid solution is either recycled or charged to a electrowinning step.

Abstract: Nickel (or other transition metal) contaminated with about 5 ppm technetium is decontaminated by dissolving the nickel and the technetium into an aqueous acid solution while introducing a graphite or activated carbon powder into the acid to immediately adsorb the dissolving technetium. The technetium-contaminated powder is separated from the aqueous acid solution and the nickel is then electrowon from the solution. The depleted acid solution is then recycled back to the dissolution step.

Abstract: Technetium is separated from nickel by electro-refining contaminated nickel. Electrorefining controls the electrolyte solution oxidation potential to selectively reduce the technetium from the metallic feedstock solution from Tc(VII) to Tc(IV) forcing it to report to the anodic slimes and thereby preventing it from reporting to the cathodic metal product. This method eliminates the need for peripheral decontamination processes such as solvent extraction to remove the technetium prior to nickel electrorefining. These methods are particularly useful for remediating nickel contaminated by radio-contaminants such as technetium and actinides.

Abstract: Two alternate, mutually exclusive, methods of removing radio contaminants from metal are taught based respectively on electrowinning or electrorefining of the base metal. The alternative using electrorefining controls the anolyte oxidation potential to selectively reduce the technetium in the metallic feedstock solution from Tc(VII) to Tc(IV) forcing it to report to the anodic slimes preventing it from reporting to the cathodic metal product. This method eliminates the need for peripheral decontamination processes such as solvent extraction and/or ion exchange to remove the technetium prior to nickel electrorefining. The other alternative method combines solvent extraction with electrowinning. By oxidizing technetium to the heptavalent state and by using mixtures of tri-n-octyalphosphine oxide and di-2-ethyl phosphoric acid in aliphatic hydrocarbon carriers to extract the radio contaminants prior to electrowinning, the background metal may be recovered for beneficial reuse.