Abstract
One of ABB Atom's methods under development, ELDECON, is an electrochemical process for decontamination of components used in nuclear power plants. ELDECON removes radioactive species while producing small amounts of waste. However, the waste sludge that is produced in the ELDECON process contains chromate (Cr 6+), which makes it a mixed waste problem (Cr 6+ and radioactivity) . According to 40 CFR 261, if a process in any step creates chromate, the final waste has to be tested in a toxicity characteristic leachate procedure. In order to pass the test, the chromate have to be reduced to chromium (Cr3+). Electrochemistry has proven to be a valuable tool. When incorporating indirect electrolysis into the ELDECON concept, the chromate (Cr6+) ions are being reduced. This is done by the use of an electrochemical cell (reactor bed). The method involves ferric nitrate as a reagent, which besides converting the chromate completely, also decreases the reaction time. The experiment showed a linear relationship to reduce varying amounts of solution. This makes the test cell feasible to scale up and use in the industry. Ion exchange was also studied as an alternative method of reducing chromate. However, the ion exchange resins investigated were not efficient enough to effectively reduce and exchange the chromate ions.
Carlsson, Charlotta Elisabeth (1995). Treatment methods for spent decontamination electrolyte produced in the ABB Atom electrochemical decontamination process ELDECON. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1995 -THESIS -C374.