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Okuda, Eiji; Ito, Hiromichi; Yoshihara, Shizuya
UTNL-R-0486, p.6_1 - 6_10, 2014/03
An accident occurred in experimental fast reactor "Joyo" in 2007 which is obstruction of fuel change equipment caused by contacting rotating plug and MARICO-2. In addition, we confirmed two happenings in the reactor vessel that (1) Deformation of MARICO-2 subassembly on the in vessel storage rack together with a transfer pot, (2) Deformation of the Upper core structure of "Joyo" caused by contacting MARICO-2 subassembly and the UCS. We do the restoration work for restoring it. This time, we describe current status of Replacement work of the UCS.
Yoshihara, Shizuya; Okawa, Toshikatsu; Inoue, Setsunari
no journal, ,
no abstracts in English
Ota, Katsu; Ito, Hiromichi; Ushiki, Hiroshi; Yoshihara, Shizuya; Tobita, Shigeharu; Kawahara, Hirotaka; Hara, Masahide*; Okazaki, Hiroyoshi*; Tanaka, Junya*; Tatsuno, Takahiro*
no journal, ,
no abstracts in English
Shimizu, Shunji; Izawa, Osamu; Ishizaki, Kazuhiko; Takeishi, Tsuyoshi; Owada, Ryohei; Yoshihara, Shizuya; Michino, Masanobu
no journal, ,
no abstracts in English
Ashida, Takashi; Takamatsu, Misao; Ito, Hideaki; Okawa, Toshikatsu; Yoshihara, Shizuya
no journal, ,
In the experimental fast reactor Joyo, it was confirmed that the top of the irradiation test sub-assembly (S/A) of MARICO-2 (material testing rig with temperature control) had been broken and bent onto the in-vessel storage rack as an obstacle and had damaged the upper core structure (UCS). This incident necessitated the replacement of the UCS and the retrieval of the MARICO-2 sub-assembly for Joyo restoration. This paper describes the summary of Joyo restoration works. In-vessel repair techniques for sodium cooled fast reactors (SFRs) are important in confirming safety and integrity of SFRs. However, the demonstrated techniques under the actual reactor environment with high temperature, high radiation dose and remaining sodium are not enough to secure the reliability of these techniques. The experience and knowledge accumulated in the UCS replacement provides valuable insights into further improvements for in-vessel repair techniques in SFRs.