Assessment of contamination distribution of "Monju", 2; Assessment of activation of the under-floor transfer car

Kinoshita, Takuma*; Kishimoto, Yasufumi*; Hanaki, Shotaro  ; 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 under-floor transfer car for fuel handling unique to "Monju" transports, undergoes gas replacement and preheats fuel assemblies. Due to neutrons generated from fuel, the structural materials are activated. The radioactivity of the car 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, and a 3D analysis was conducted for validation. 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.