Dissolved ozone coupled permanganate based process for chemical decontamination of stainless steel surfaces

Abstract

Removal of passive/corrosion oxide film comprising radioactive nuclides from the alloy surfaces forms a decisive step during the chemical decontamination process development in the nuclear industry. Conventionally, permanganate based methods are used for stainless steel surface decontamination. We have modified this MnO4− method by coupling with dissolved ozone (DOz). In DOz coupled MnO4− method, DOz is used for the regeneration of permanganate from MnO2 formed during the oxidation of chromium. For the DOz coupled MnO4− process, parameters like DOz and MnO4− concentration and solution temperature were optimized. Optimized parameters exhibited a reduction in the chemical requirement for simulated corrosion product oxide dissolution while maintaining the same dissolution efficiency. The process also helps in the release of iron, cobalt, and nickel to the solution from the oxide layer, thereby lowering the number of steps involved in the decontamination process as compared to the conventional MnO4− process. The process effectively shrinks the radioactive waste volume generation, an essential factor in decontamination process development in the nuclear industry.