FUEL ELEMENT MANUFACTURING PROCESS Russian patent published in 2005 - IPC

FIELD: nuclear power engineering; manufacture of fuel elements for water-moderated water-cooled reactors.

SUBSTANCE: in the course of conversion of uranium hexafluoride UF₆ into uranium dioxide UO₂ hexafluoride UF₆ is supplied to combustion zone in air-hydrogen flame; then feed is changed over to new flow of gaseous hexafluoride until gaseous hexafluoride flow speed is reduced, and low-speed flow is conveyed to intermediate tank for condensation as soon as this tank is filled up (found by weighing), condensed hexafluoride is evaporated and gaseous hexafluoride flow is again conveyed to combustion zone. Fluoride is extracted from solid particles of uranium fluoride oxides by their heat treatment in hydrogen and superheated water vapor within revolving furnace at 650 - 660°C in first zone; deep extraction of fluorine from fluorine-containing uranium is effected in second zone at 660 - 665°C, and in third zone uranium dioxide powder is produced at 665 - 670°C by balling powder particles; uranium dioxide UO₂ powder obtained in the process is cooled down in nitrogen medium to 18 - 20°C, magnetically separated, sifted through screen whose maximum mesh aperture is 1.25 mm, content of 70 μm fines of homogenization in nitrogen environment being not over 15%. Measurements are made using following formula: N = No x e^-mpd, where N is number of photons recorded by detector in absence of fuel pellet; m is mass decay coefficient; p is fuel pellet density; d is thickness of fuel pellet zone under check. Fuel pellet density is found from formula p = (No/N)/md, and fuel pellets whose density is up to 10.4 and over 10.7 g/cm³ are rejected.

EFFECT: facilitated procedure.

1 cl, 1 dwg