Assessment of contamination distribution of "Monju", 5; Assessment of activation of the fuel washing tank

Kinoshita, Takuma*; Kawaguchi, Yotaro*; Kishimoto, Yasufumi*; Hanaki, Shotaro  ; Mashimo, Ryutaro; Hayashi, Hirokazu 

Dismantling in radiation-controlled area is planned in phase 3 of the "Monju" decommissioning program, but an assessment of contamination of the facilities is essential before starting the dismantling. The Fuel Washing Tank unique to "Monju", is used for washing and removing sodium clinging to fuel assemblies transferred from the reactor. Due to neutrons generated from fuel, the structural materials are activated. The radioactivity of the tank was assessed using the same methodology as the reactor's evaluation. The neutron flux distribution and activation levels were evaluated using a 2D RZ system. Additionally, it was confirmed that the activity of activation products is at most at L3 levels, and in most areas, it is below the clearance levels.