Inspection and repair techniques in reactor vessel of the experimental fast reactor JOYO; Investigation and design for retrieval device of bent MARICO-2 test subassembly

Ashida, Takashi ; Miyamoto, Kazuyuki; Okazaki, Yoshihiro*; Ito, Hideaki

In the experimental fast reactor Joyo, failure of disconnecting the irradiation test subassembly MARICO-2 (Material Testing Irradiation Rig with Temperature Control) was occurred and top of the MARICO-2 test subassembly was bent onto the in-vessel storage rack. As a result of this incident, the operation area of rotating plug for the fuel exchange in Joyo is limited. The replacement of the damaged UCS and retrieving the bent MARICO-2 are required to Joyo restoration. This report describes about investigations and some tests to know the status of MARICO-2 test subassembly and the optimized detail design of retrieval device reflecting those results.