Abstract: Taking martensitic stainless steel and austenitic stainless steel, the main materials of charging pumps in nuclear power plants, as study objects, we respectively tested the effects of solution concentration, reaction temperature and time on corrosion in the oxidation and reduction stages of a REDOX decontamination process. The corrosion of both materials in the whole process was then evaluated. A practical decontamination operation on a charging pump was also carried out in a nuclear power plant. With 0.25% potassium permanganate + 0.25% sodium hydroxide solution as the oxidant and 0.25% oxalic acid + 0.25% citric acid mixture as the reductant, under the effect of ultrasonic, we had them reacted at 70 ℃ for 4 h and 2 h respectively. It showes the steel sample surface is mainly of uniform corrosion, with an average corrosion amount of less than 1.5 g/m², which meets the requirements of relevant standards. At the same time, the radioactivity on the surface of the charging pump can be effectively removed. The formula and process can be applied to the decontamination of charging pumps in nuclear power plants.

Key words: Charging pump, Redox decontamination, Safety effect