PURPOSE: To make a heating body small, to reduce heating energy, to perform the flow-down recovery of waste uranium within a short time and to enhance separation efficiency, by providing such a structure that a recovery plate can move between a collection area having a special structure and a metal isotope liquefying discharge area.

CONSTITUTION: A waste uranium recovery plate 104 is rotated to the peripheral direction thereof and waste uranium is collected and solidified in the collection area 109 of said recovery plate 104 to be melted in a heating zone 107. Molten waste uranium flows down by the of gravity and is solidified in the area below the heating zone 107. Next, the recovery plate 104 is moved upwardly so as to melt solidified waste uranium. The above mentioned operation is continuously performed and waste uranium is made to flow in a recovery flow passage 108 from the end part of the recovery plate 104. Then, by continuously moving the recovery plate 104 left and right at a low speed, the continuous recovery of waste uranium is enabled. The recovery plate 104 issues from the heating zone 107 to be cooled to temp. equal to or less than the m.p. of uranium by heat dissipation or forcible cooling.