A new method of decontamination of nuclear power plants

A new decontamination process was developed and applied. This process, referred to as EPRI DFD (Decontamination For Decommissioning), removes all radioactivity present in the surface layer of decommissioned nuclear power plant components so that after the treatment, the components can be handled as non-radioactive scrap. Fluoroboric acid serves as the dissolving agent and is used in controlled pH and oxidation-reduction potential conditions. The total concentration is about 1 g/l. The oxidation-reduction potential is controlled by means of potassium permanganate as an oxidizing agent, owing to which different metals can be dissolved during the process at comparable rates. The process rate can be adjusted by temperature control. The solution is purified by ion exchange. A high decontamination factor can be achieved if an appropriate solvent purification and flushing mode is used. Tests performed on BWR heat exchangers gave evidence that the process is well suited to the treatment of big facilities in the non-disassembled state. (P.A.) big facilities in the non-disassembled state. (P.A.)