Treatment method of the process waste from the chemical decontamination of nuclear facilities by using redox and precipitation reaction

摘要

The present invention can be easily applied to a chemical decontamination process of a nuclear power facility, particularly a primary cooling system of a pressurized light water reactor type nuclear power plant, and by precipitating and removing metal oxides of process wastes as sediments using redox and precipitation reactions, And to a method for treating chemical waste chemical decontamination waste using a redox reaction and a precipitation reaction capable of enhancing the water solubility of waste. Manganese acid of HMnO ₄ or KMnO _{4 as} an oxidizer salt or inorganic acid as an acidity modifier is added to a metal waste having a metal corrosion oxide film formed in a system containing a radionuclide so that chromium oxide is converted into HCrO ₄^- Of chromium ions and dissolving it in the decontamination waste solution; A second step of reducing the unreacted permanganic acid and chromium ions by a redox reaction and a precipitation reaction, and removing the precipitate as a first precipitate by filtration and filtration by introducing a first reducing agent salt into the decontamination waste solution in which the chromium ion is dissolved; An organic acid including oxalic acid as a second reducing agent salt is added to the decontamination waste solution that has been subjected to the second step, and the metal oxide film is subjected to reduction dissolution, acidic dissolution and dissolution in complex formation, A third step of dissolving the MnO ₂ precipitate into Mn ²⁺ ions while removing some metal ions with a cation exchange resin; A fourth step of decomposing the second reducing agent salt in the decontamination waste solution; And a carbonic acid ion precursor is added to the carbonic acid gas generated in the decomposition of the decontamination waste liquid to control the pH of the decontamination waste solution in real time and the decomposition products of carbon dioxide and carbonate ion precursor and the metal And a fifth step of precipitating a second precipitate formed by the reaction of the ions.