Inner side visual inspection of JMTR reactor pressure vessel

Ide, Hiroshi  ; Kimura, Akihiro ; Miura, Hiroshi; Hori, Naohiko ; Nagao, Yoshiharu  

Visual inspection of inner side of a reactor pressure vessel was carried out using a underwater camera before the JMTR refurbishment work from the view point of its long term utilization because the reactor pressure vessel of the JMTR will be used continuously after restart of the JMTR. As a result, adhesion materials which can be easily removed using the gauze were observed around nozzles in a top head of the reactor pressure vessel. A major component of the adhesion materials is an iron as a result of the componential analysis. However, no significant problem affecting the integrity of the reactor pressure vessel was observed, and thus the integrity of the reactor pressure vessel was confirmed. As for the view point of the aged effect, it became clear that the reactor pressure vessel of the JMTR can be used for more than 20 years. The visual inspection by the underwater camera is to be carried out periodically to confirm the integrity of the reactor pressure vessel.