An apparatus for continuous treatment of a nitrate solution of nuclear fuel material by heating, evaporating, concentrating and denitrating said nitrate solution to produce a denitrated powder, said apparatus comprising:
- an oven into which microwave energy is applied through waveguide means;
- an evaporation concentrator vessel disposed within said oven, said evaporation concentrator vessel including a stationary cylindrical vessel body and a tubular waveguide inserted into said cylindrical vessel body, said tubular waveguide having openings at the end and on the sides thereof, said cylindrical vessel body having a size for limiting the amount of material to be treated to less than that necessary for maintaining criticality for safety of material to be treated;
- a concentrating and denitrating vessel disposed within said oven, said concentrating and denitrating vessel including a circular vessel body supported rotatably about its center and a plurality of partition plates positioned radially inside said vessel body so as to divide the interior of said vessel body into a plurality of compartments, each of said compartments having a size for limiting the amount of material to be treated to less than that necessary for maintaining criticality for safety of material to be treated;
- a first pipe for supplying a nitrate solution of nuclear fuel material from the outside of the oven into said evaporation concentrator vessel;
- a second pipe for supplying a concentrated solution produced in said evaporation concentrator vessel into one of said compartments in said concentrating and denitrating vessel;
- a pan for receiving a denitrated powder produced from said concentrated nitrate solution in one of said compartments in said concentration and denitrating vessel, said pan being positioned adjacent to a portion of the outer periphery of said concentrating and denitrating vessel;
- means for transferring said denitrated powder from one of said compartments in said concentrating and denitrating vessel into said pan;
- and
- a gas discharging pipe for discharging gas produced during the treatment from said oven;
- said continuous treatment by heating, evaporating and concentrating the supplied nitrate solution being accomplished continuously in said evaporation concentrator vessel to form the concentrated nitrate solution and said continuous treatment by further heating, evaporating, concentrating and denitrating the concentrated nitrate solution being accomplished continuously and in sequence in each of said compartments in said concentrating and denitrating vessel during one rotation thereof to form the denitrated powder.