Apparatus for subjecting a radioactive sodium borate waste solution to volume reduction and solidification

Claim 1

An apparatus for producing a vitric solid solution comprising (a) the solid content of a radioactive waste solution of sodium borate discharged from a pressurized water reactor, having a Na 2 O to B 2 O 3 molar ratio of 0.1 to 0.06 and (b) 10 to 40 mole % of ZnO or 10 to 40 mole % of ZnO plus 3 to 10 mole % of Al 2 O 3 and/or CaO so that the total content of ZnO plus Al 2 O 3 and/or CaO does not exceed 43 mole %, the apparatus comprising: (A) a waste solution feed tank equipped with a hopper for stabilizing agent in water, a stirrer for stirring the sodium borate waste solution and the stabilizing agent in water added thereto from said hopper; (B) a waste solution circulation pump for circulating a part of the resulting mixture to the waste solution feed tank and another part of the resulting mixture to an evaporator through a waste solution supply pump; (C) the evaporator for evaporating and concentrating the waste solution fed from the pump to remove water by a heating fluid so as to form an evaporator residue; (D) a heating type dehydrator for heating the evaporator residue sent from the evaporator by a heating fluid while being stirred by a stirrer, for further evaporation; (E) a powder dryer for removing the crystal water of the evaporation residue, thereby rendering said residue as a porous lump, by heating with a microwave generator through a microwave guide tube, and a stirrer for grinding the lump into a powder provided therein; (F) discharger means for forcible batch delivery of said residue to said powder dryer; (G) a melting furnace for melting into a vitric melt the dried power sent from the powder dryer by irradiation with microwaves transmitted from a microwave generator through a microwave guide tube, said melt being charged in a solid solution container; (H) a condenser for condensing the evaporated water generated from the evaporator and the heating type dehydrator; (I) a prefilter for filtering the off-gas from the powder dryer and the melting furnace to remove solids; (J) an off-gas cooler for removing the residual water of the off-gas from the waste solution feed tank, the condenser and the prefilter; (K) an off-gas treater for purifying the off-gas from the off-gas cooler to discharge it from an off-gas exhaust fan.

Claim 2

An apparatus for producing a vitric solid solution comprising (a) the solid content of a radioactive waste solution of sodium borate discharged from a pressurized water reactor, having a Na 2 O to B 2 O 3 molar ratio of 0.1 to 0.06 and (b) 10 to 40 mole % of ZnO or 10 to 40 mole % of ZnO plus 3 to 10 mole % of Al 2 O 3 and/or CaO so that the total content of ZnO plus Al 2 O 3 and/or CaO does not exceed 43 mole %, the apparatus comprising: (A) a waste solution feed tank equipped with a hopper for stabilizing agent in water, a stirrer for stirring the sodium borate waste solution and the stabilizing agent in water added thereto from said hopper; (B) a waste solution circulation pump for circulating a part of the resulting mixture to the waste solution feed tank and another part of the resulting mixture to an evaporator through a waste solution supply pump; (C) the evaporator for evaporating and concentrating the waste solution fed from the pump to remove water by a heating fluid so as to form an evaporator residue; (D) a heating type dehydrator for heating the evaporator residue sent from the evaporator by a heating fluid while being stirred by a stirrer, for further evaporation; (E) a powder dryer for removing the crystal water of the evaporation residue, thereby rendering said residue as a porous lump, by heating with a microwave generator through a microwave guide tube, and a stirrer for grinding the lump into a powder provided therein; (F) discharger means for forcible batch delivery of said residue to said powder dryer; (G) a melting furnace for melting into a vitric melt the dried power sent from the powder dryer by irradiation with microwaves transmitted from a microwave generator through a microwave guide tube, said melt being charged in a solid solution container; (H) a condenser for condensing the evaporated water generated from the evaporator and the heating type dehydrator; (I) a prefilter for filtering the off-gas from the powder dryer and the melting furnace to remove solids; (J) an off-gas cooler for removing the residual water of the off-gas from the waste solution feed tank, the condenser and the prefilter; (K) an off-gas treater for purifying the off-gas from the off-gas cooler to discharge it from an off-gas exhaust fan.