Complexing properties of the main organic acids used in decontamination solutions for nuclear power plants and reactions involved in their degradation or elimination Original Research Article

Deposited activity on PWR equipment and component surfaces sometimes has to be decontaminated. An appropriate method for the dissolution of contaminated chromium-rich grow-on oxides uses an alternation of oxidizing steps (generally alkaline permanganate) and a reducing step made of organic acids. These organic acids have simultaneously reducing and chelating properties. Then, chelates are destroyed on cation exchangers in the H+ form and the resulting acids are oxidized with the permanganate of the first step. Basic information on chemical properties important in these three steps has been determined: acid-base properties of the considered organic acids, stability constants of the complexes formed between these acids and the metal cations originating from the stainless steel constituents (Fe, Ni, Cr, Co), ion exchange process, oxidation of the organic acids with emphasis on various products generated before the final products (CO2, H2O).