Patent Number: 062185926
Section: claims

1. A method for the treatment of a radioactive evaporator concentrate containing sodium sulfate from an evaporation system of a nuclear plant, comprising: (a) separating any undissolved components from the evaporator concentrate,  (b) crystallizing the sodium sulfate contained in the evaporator concentrate as Glauber's salt (Na.sub.2 SO.sub.4.10H.sub.2 O) by deposition on an immersion cooler,  (c) dissolving and recrystallizing the Glauber's salt deposited on the immersion cooler,  (d) optionally, at least once further dissolving and recrystallizing the Glauber's salt from step (c),  (e) recovering essentially radioinactive Glauber's salt from recrystallization step (c) or (d), and  (f) recycling the evaporator concentrate, depleted in sodium sulfate, to the evaporation system. 2. The method of claim 1 where the separation step (a) comprises filtration or decantation. 3. The method of claim 1 where the crystallization step (b) is carried out at a temperature above -2.degree. C. 4. The method of claim 3 where the crystallization step (b) is carried out at a temperature of about 0.degree. C. 5. The method of claim 1 where the dissolution and recrystallization step (c) comprises recrystallization by cooling or recrystallization by evaporation. 6. The method of claim 5 where the dissolution and recrystallization step (c) comprises dissolution and recrystallization by cooling using the immersion cooler of step (b) into which a heating medium and a cooling medium are introduced alternately. 7. The method of claim 6 including further dissolution and recrystallization step (d) where the dissolution and recrystallization step (d) comprises dissolution and recrystallization by cooling using the immersion cooler of step (c) into which a heating medium and a cooling medium are introduced alternately. 8. The method of claim 1 including further dissolution and recrystallization step (d). 9. The method of claim 8 where the dissolution and recrystallization step (d) comprises dissolution and recrystallization by cooling using the immersion cooler of step (b) into which a heating medium and a cooling medium are introduced alternately. 10. The method of claim 1 where the immersion cooler comprises plate-shaped or rod-shaped heat exchange elements. 11. The method of claim 10 where the heat exchange elements have a smooth surface. 12. The method of claim 10 where the immersion cooler comprises plate-shaped heat exchange elements. 13. The method of claim 12 where the immersion cooler has five to ten plate-shaped heat exchange elements.