Development of compact underwater chipping device for demolishing the fuel debris in the reactor containment vessel

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K06053
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Design engineering/Machine functional elements/Tribology
• Research Institution: Niigata Institute of Technology
• Principal Investigator: kobayashi yoshikazu 新潟工科大学, 工学部, 准教授 (60277390)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 廃炉 / 加工 / ハツリ

Outline of Final Research Achievements

The compact underwater chipping device was developed to demolish the fuel debris accumulated in the reactor containment vessel. This chipping device draws in the water around the fuel debris by feed pump and the fuel debris is crushed by vibrating tool mounted on this chipping device. This vibration is invented by this water flow. In this study, prototype chipping device was developed and improve to obtain the high frequency and rotation torque of tool. As a result, the number of rotations of impeller which connects with a tool are 1,800rpm at unloaded and 600rpm, which means tool frequency is 600Hz, at light loaded.
However, when the tool was forced on a specimen at high load to machining, the rotation of impeller was stopped. The further improvement of this chipping device to obtain the high rotation toque is necessary.

Free Research Field

生産システム

Academic Significance and Societal Importance of the Research Achievements

福島第一原発の廃炉におけるロードマップには、切削装置によりデブリを小さく加工しロボットハンドで取り出す構想が記載されている。原子炉格納容器内の詳細な状況は現在不明であるが、原子炉容器内の様々な構成部材が溶解し固まった複雑な構成材料がデブリとなっていると考えられる。したがって、デブリの効率的な回収を考えた場合、デブリの材質、大きさ及び形状を考え、様々な加工機械を用い、その加工法に合った加工条件のもとで加工を行う必要がある。また、加工環境は高い放射線のため電子回路を伴う制御装置を設置することは難しいと考えられるため、機械要素のみで構成される新しい加工装置の開発を行った。