Experience and technology consolidation related to dismantling sodium equipment; Technology to reduce sodium remaining in 100m grade large tanks

Hayakawa, Masato; Shimoyama, Kazuhito ; Miyakoshi, Hiroyuki; Suzuki, Shigeaki*

At the Oarai Research and Development Institute of the Japan Atomic Energy Agency, experimental studies in various sodium environments are being conducted in connection with the research and development of sodium-cooled fast reactors such as the experimental fast reactor Joyo and the prototype fast reactor Monju. The dismantling of sodium test facilities and equipment that have achieved their purpose has been carried out sequentially, and a wealth of experience and technology has been accumulated. On the other hand, a large amount of metallic sodium used for research and testing is being reused for new testing facilities, and the large sodium tanks that contained the metallic sodium are being dismantled. In order to dismantle these tanks safely and efficiently, it is important to reduce the residual sodium inside the tanks (especially at the bottom) as much as possible before dismantling. Therefore, we have been working on the reduction of residual sodium at the bottom of several large sodium tanks of 100 m class. This report describes the technologies and experiences related to the reduction of residual sodium that have been carried out so far.