Development of low-activation vanadium alloy for recycling within 10 years after use in fusion reactors

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K14284
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Nuclear fusion studies
• Research Institution: National Institute for Fusion Science
• Principal Investigator: Nagasaka Takuya 核融合科学研究所, ヘリカル研究部, 准教授 (40311203)
• Co-Investigator(Kenkyū-buntansha): 田中 照也 核融合科学研究所, ヘリカル研究部, 准教授 (30353444)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 廃炉・リサイクル技術 / 接触線量率 / 高純度化

Outline of Final Research Achievements

The present study examined (1) reduction in the amount of harmful radioactive impurities generating long half-life nuclides, (2) minimization of the concentration of the alloying element Ti, which is also one of the harmful radioactive elements, and (3) removal of noble gaseous and volatile gaseous radioactive impurities. For the topic (1), harmful radioactive impurities, Co and Mo, were successfully reduced by 50 % and 90 %, respectively, compared with the current alloys. For (2), it was revealed that the alloys maintained ductility even if Ti concentration was reduced in to 1 mass% from the current amount, 4 mass%. For (3), it was demonstrated that the concentration of the impurities, Co, Ni, Cu, Al and Mn, could be reduced by refining with electron beam melting. Ar concentration was below the detection limit, 10 mass ppm, irrespective of the refining, indicating Ar must be effectively removed by melting.

Free Research Field

低放射化材料開発