Abstract: A nuclear fuel dissolution apparatus which comprises a perforated sloping ramp contained within a process chamber for containing solvent for the fuel, a pulsation member which in use creates pulses in solvent in the process chamber, the perforations being designed to direct pulses of solvent along and up the ramp, and a discharge point for fuel hulls disposed at an upper region of the ramp is characterised in that the ramp is made out of flat blades and the perforations of the ramp comprise inclined slits formed between the blades.

Abstract: A method of transporting solid material pieces in the liquid phase of a mass-exchanging apparatus comprises forming pneumatic pulses in the apparatus, converting said pulses into reciprocal motion of the liquid phase by applying the pulses to the liquid phase and movement of the solid material pieces upwardly along a sloping ramp. The method is characterised in that the reciprocal motion of the liquid phase is directed via slits in the ramp at an acute angle to the direction of the movement of the solid material pieces upwardly along the ramp.