Heat evaluation examination of fuel assembly

Suto, Shinya; Nakabayashi, Hiroki ; Yao, Kaoru*

The cooling examination was executed by using the simulated fuel assembly to obtain the basic data of the most effective cooling system in the laser disassembling process of the spent fuel assembly of prototype fast breeder reactor "Monju". As a result, the following have been understood. (1) Before the laser disassembling (there is not any duct tube cutting), it is possible to cool enough by the amount of the wind of 20m/h or more flowing from the handling head side. (2) After the laser disassembling begins (duct tube is cut), 1kW or more of the heat generation cannot be cooled by ventilation from the handling head side. (3) Cooling by the flow across fuel pin is required during laser disassembling. The basic data of the cooling system was obtained from these examination results. However, for cooling across fuel pin during the laser disassembling, it is necessary to examine shape of the side cooling nozzle, spraying angle, and flow velocity at the nozzle exit, etc. enough.