Accomplishment of JT-60U disassembly work dealing with radioactive components

放射化物を伴うJT-60U解体作業の完了

池田 佳隆; JT-60チーム

Ikeda, Yoshitaka; JT-60 Team

核融合実現の早期実現を目指し、JT-60Uの改修(超伝導トカマク"JT-60SA")が進められている。JT-60SAトカマク本体がJT-60Uトカマク本体のある場所に設置されるため、JT-60Uトカマクの解体が必要であった。JT-60Uトカマクは、総量1.510個のD-T反応中性子により放射化している。総数13000点、総重量5400トンの解体機器を将来のクリアランスに向け線量当量率、重さ、材質などを記録しながら、保管場所に移動・保管した。解体機器の主な放射化物はステンレス鋼であり、真空容器から約10m離れると、線量当量率はバックグランドレベルの約0.1マイクロSv/hであった。JT-60SAの組み立ては、JT-60Uトカマクの解体終了後、2013年1月から開始した。

The upgrade of the JT-60U to the superconducting tokamak "JT-60SA" has been carried out to contribute the early realization of fusion energy. Disassembly of the JT-60U tokamak was required so as to newly install the JT-60SA torus at the same position in the torus hall. The JT-60U tokamak was featured by the radioactivation due to deuterium-deuterium (D-D) reactions of 1.510 (n) in total. About 13,000 components with a total weight of more than 5,400 tonnes were removed from the torus hall and stored safely in storage facilities with recording the data such as dose rate, weight and kind of material, so as to apply the clearance level regulation in future. It was confirmed that the main radioactive material of the disassembly components was the stainless steel and that its dose rate was almost background level (0.1 micro Sv/h) at 10m far from the vacuum vessel. The assembly of JT-60SA tokamak has started in January 2013 after this disassembly of the JT-60U tokamak.