Some technological problems of fusion materials management

核融合炉材料の取扱いに関する技術課題

Kolbasov, B. N.*; El-Guebaly, L.*; Khripunov, V. I.*; 染谷 洋二; 飛田 健次; Zucchetti, M.*

Kolbasov, B. N.*; El-Guebaly, L.*; Khripunov, V. I.*; Someya, Yoji; Tobita, Kenji; Zucchetti, M.*

環境安全性経済性執行委員会(IEA: International Energy Agency)の枠組みの中で核融合廃棄物を材料サイクルの観点で検討を進めている。本研究では、放射化した機器に対してクリアランスを妨げる核種を特定し、不純物制御の影響を評価した。論文では、特に重要核種であるC-14について、IAEAのクリアランスレベルに関する考察とC-14を生成する不純物である窒素濃度について検討した結果を報告する。

Within the framework of the International Energy Agency Program on Environmental, Safety and Economic Aspects of Fusion Power, an international collaborative study on management of fusion radioactive materials has been carried out to examine the back-end of the materials cycle. The strategy for handling fusion activated materials calls for three potential schemes: clearance, recycling and disposal. There is a growing international effort to avoid geologic disposal, for fusion in particular. Plasma facing components (divertor and blanket) normally contain high radioactivity and are not clearable. As clearance of sizeable components (such as biological shield, cryostat vessel, vacuum vessel, and some constituents of magnets) is highly desirable, we identified the source of radioisotopes that hinder the clearance of these components and investigated the impact of impurity control. Another study assessed radioactivity build up under repeated use of the divertor made of W-LaO alloy. Effect of impurities on activated materials management is illustrated by the example of carbon-14 generation. Other studies examined impurities activation in concrete of biological shield and the impact of a specific activated materials scenario on the hot cell design and waste storage requirements.