Kernforschungszentrum Karlsruhe Gmbh

Kernforschungszentrum Kalrsuhe Gmbh

Klaus Ebert

Helmut Schmieder

Edmund Henrich

Willi Roesch

Reinhold Huefner

Ulrich Bauder

Zdenek Kolarik

Hans J Bleyl

Process for the batch purification of uranium recovered in a reprocessing process, after a first separation of impurities, in which for each batch an aqueous, nitric acid uranyl-nitrate solution (UNH original solution), which still contains residual amounts of impurities, is cooled to crystallize out purified UO.sub.2 (NO.sub.3).sub.2 .multidot.6H.sub.2 O (UNH) from the solution and the resulting crystals are separated out of their mother liquor and washed. The original solution is adjusted to a specified uranium concentration and the adjusted solution is cooled to below 0.degree. C. to bring about the crystallization. The duration between starting and ending the crystallization is held between 0.1 and 10 hours. The amount of the UNH crystals which is crystallized out corresponds to at least about 80 weight % of the uranium content introduced. The ratio of the volume of the crystals formed to the volume of the remaining mother liquor is not larger than 0.5. A final concentration of nitric acid is estabilished in the mother liquor between 6 and 12 mol/l HNO.sub.3 at room temperature. A joint crystallizing out of UNH with water as ice and/or with nitric acid trihydrate (HNO.sub.3 .multidot. 3H.sub.2 O) is avoided. The resulting mother liquor is separated from the crystals and then recycled. The separated crystals are washed at least one time with an HNO.sub.3 solution having a similar acid content and similar temperature to that of the separated mother liquor at the end of the crystallization procedure. A batch process for purifying plutonium or plutonium and uranium is also disclosed.

Process for the batch fine purification of uranium or plutonium

A process for the separation of substances hindering the recovery of the fissionable materials uranium and plutonium and for the separation of the fissionable materials to be recovered in a reprocessing process for spent, irradiated nuclear fuel- and/or fertile materials. A second and a third wash of the organic phase is performed for residual ruthenium separation and residual zirconium separation, and there is a repetition of the Pu stripping step with simultaneous electrolytic reduction of Pu(IV) to Pu(III). The second and third wash solutions or the aqueous phase employed for the repetition of plutonium stripping, respectively, each contains a high concentration of product uranyl nitrate. The aqueous run-off from the second and third washes and from the repetition of the Pu stripping step is indirectly fed back into the aqueous fuel solution employed in the first extraction step of the reprocessing method by first feeding these run-offs to an intermediate treatment.

Process for the improved separation of substances hindering the recovery

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Heidelberg, Germany

Klaus Ebert