Uranium-cerium mixed oxides

Hofrnaim first formulated the concept of mixed oxidation states for Prussian blue and other iron-containing mixed valence species. The electronic origin of the color, of course, remained obscure until the development of quantum mechanics. Another concept, described as valence oscillation , was used by Hofinaim and Hoschele following the realization that organic dyes were often found to be unsaturated species with valence resonance an example is cerium-uranium blue (3). 

In general, release of actinide isotopes from failed fuel rods and their subsequent behavior in the primary circuit is very similar to that of certain fission products, e. g. of cerium isotopes. For this reason, the y-emitting cerium isotopes which can easily be measured in the coolant by y spectrometry, can serve as a suitable indicator for early recognition of higher releases of actinides to the coolant. The release behavior of the actinides from failed mixed-oxide fuel rods to the coolant is almost identical to that from uranium fuel rods. This means that in both cases the U Pu... 

The possibility of dissolving the mixed hydroxide in HNOs and obtaining direct extraction of thorium (and uranium) from the nitrate solution has been studied [155,156], but does not seem to be too promising, possibly due to the partial oxidation of tripositive cerium to the tetrapositive state. Kraitzer [157] was able to separate thorium from the mixed hydroxide cake by extracting the cake with sodium carbonate buffer at pH 9.5—10. Thorium was found to form a soluble carbonate complex and a recovery of better than 99% of thorium was claimed after only four extractions. 

Before the separation of the lanthanoids, thorium and uranium have to be removed. From an acidic solution of mixed Ln ions, cerium is first removed based on the existence of the Ce oxidation state and the higher basicity of Ln(OH)3 than CeO. ... 

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