Liquid decontamination using acidic electrolyzed water for various uranium-contaminated steel surfaces in dismantled centrifuge

When dismantling centrifuges in uranium-enrichment facilities, decontamination techniques must be developed to selectively remove uranium-contaminated surfaces of dismantled parts. Dismantled uranium-contaminated parts can be disposed of as nonradioactive wastes or recycled after the decontamination appropriate for clearance. Previously, we developed a liquid-decontamination technique using acidic electrolyzed water to remove uranium-contaminated surfaces. However, further development is required for its actual application. Dismantled parts contain various uranium-contaminated surface features due to different operating conditions, inhomogeneous decontamination using iodine-heptafluoride gas, and changes in long-term storage conditions after dismantling. In this study, we performed the liquid decontamination on specimens with various uranium-contaminated surfaces cut from a centrifuge made of low-carbon steel. The results revealed that the liquid decontamination effectively removed the uranium-contaminated surfaces, and the radioactivity fell below the target value within 20 min. Although the required time also depends on the sizes and shapes of the dismantled parts in actual application, we demonstrated that the proposed method would be an effective decontamination technique for uranium-contaminated steels in dismantled centrifuges.