Technical Evaluation of Cutting Device for Volume Reduction of High Radio-Activated Instruments

The cutting techniques and the basic design of cutting device for volume reduction of a mercury target vessel, with high radio-activation after operation and the cooling time about 30 years for decay heat, which is made of SUS316L steel used in J-PARC center was evaluated. Rotation blade cutting system is very useful to apply the cutting method of the irradiated vessel and the dry cutting device was conceptually designed. In this design the main specification was set to be dry cutting method and the suppression of elevating temperature during cutting. Thus, the rotation speed of the cutting device is to be 30 RPM and the transfer speed is set to be 1 mm/min. The material for the saw blade is selected to be Cr-Mo steel which has a higher strength because the irradiated 316L steel of the vessel has a high ultimate tensile strength. The circle saw blade is 420 mm in diameter and 2.7 mm in the thickness. Based on this design, a mock-up cutting test machine for dry condition with no water was fabricated, and the cutting tests was performed. The temperature during cutting in the mock-up vessel was lower than 50 o C. The cutting fragments after the cutting of mock-up vessel were found to be relatively large, roughly 1 mm size. It is expected that these fragment chips would be easy to collect even in remote handling in hot cell.