PURPOSE: To remove the UO3 powder from the outer surface of the filter, by installing the blowing pipe for the back washing gas and the gas discharge pipe equipped with the on-off valve, in each filter being arranged on top of the fluidized bed type thermal decomposition tower for uranyl nitrate, and by blowing the noncon densable pressured, heated gas through the blowing pipe for executing the individual back washing.
CONSTITUTION: In the fluidized bed type thermal decomposition tower 1, the uranyl nitrate solution is thermally decomposed to the UO3 particle and the waste gas including NOx, steam, etc. From each end 3 of two or more filters 2 being arranged on top of the thermal decomposition tower 1, the gas discharge pipe equipped with the on-off valve 5 and the back washing gas blowing pipe 6 equipped with the on-off valve 7 are inserted. The waste gas generated in the tower 1 flows upward carrying the UO3 particle, and is sucked into the gas discharge pipe 4 through the filter 2 and is discharged. The UO3 particle sticking on the outer surface of each filter 2 is individually back washed by closing the valve 5 to stop the discharge of gas and by opening the valve 7 to blow the pressured, heated noncondensable gas being supplied from the pipe 6, into the filter 2 through the filter end 3.
TANAKA AKIRA
NAKAI EIICHIROU
