Partial replacement of JMTR beryllium frame

Kaminaga, Katsuo; Tsuboi, Kazuaki; Kusunoki, Hidehiko ; Asano, Norikazu; Yanai, Tomohiro

The sixth replacement of beryllium frame has been accomplished for the west and north frame, while the old east frame of fifth generation is preserved for use. JMTR achieved its first criticality in 1968 and has been in operation until today, with an integrated thermal output of 141.454.5 MWd. During that period replacement was carried out 4 times for all the frames, east, west and north. This time, differently from the previous replacement, west and north frames only were manufactured and installed, when the old east frame was left for continuous use, based on the past experience. Such a strategy contributed to reduction of budget and the waste associated.