Investigation of polonium removal systems for lead-bismuth cooled fast reactors using a tellurium surrogate

The alkaline extraction method is being investigated as a method to remove polonium from a lead-bismuth cooled reactor. Tellurium was used as a surrogate for these preliminary experiments to determine if migration from the lead-bismuth to the molten alkaline (NaOH) could be measured. Experiments provided direct evidence that molten NaOH can effectively remove tellurium from lead or lead-bismuth, as a reduction of three to four orders of magnitude in the tellurium concentration in the metals was observed during the experiments. The experiments also showed a higher than expected concentration of NaOH in the lead or lead-bismuth. Graphite, alumina, nickel and nickel-chromium were found unsatisfactory as crucible materials, while zirconium was found to be compatible at the conditions of interest. (author)