Actinide metals distillation

Nonmetallic impurities, mostly oxygen, found in actinide metals distilled under a vacuum of 0.1 mPa range from 4000 to 7000 atomic ppm. In a vacuum of 0.1 Pa the nonmetallic impurity content decreases to between 400 and 880 atomic ppm (51, 52). 

An interesting, peculiar laboratory preparative reaction may finally be mentioned. This is based on the very high stability of the intermetallic compounds of actinides (and lanthanides) with the platinum family metals. The combined reduction capability of Pt with H2 (coupled reduction, see 6.7.2 fi) can be used to obtain, from its oxide, the platinide of the actinide metal. The An-Pt intermetallic compound can then be decomposed by heating in vacuum and the actinide can be obtained by distillation. 

When the actinide products are removed from electrorefiners, the electrorefiner salts cover the metal. The cathodes are processed to distill adhering salt and to consolidate the actinide metals. These salts are recycled to the electrorefiner for further use (Westphal and Mariani, 2000 Westphal et al., 2002). In the case of the liquid cadmium cathode, the cadmium is... 

Electrorefining was envisaged by ANL in the late 1990s for the treatment of U-Al fuels [10]. However, the potential of U and A1 are too close to each other in molten chloride to reach a separation by this method. Some experimental studies on the An extraction with an immiscible and distillable metal, carried out by Atomic Energy of Canada in 1956, showed that Pu and Am, dissolved in liquid Al, can be transferred into liquid Bi after contact at 800 C [11], Bi was then successfully evaporated under vacuum at 750 C. Two major drawbacks were noticed (i) the volatility of Am that contaminates the Bi condensate and (ii) the solubility of Al in Bi which contaminates the final actinide metallic product. 

The actinide oxide is reduced with La or Th and the resulting actinide metal is distilled from the reactant-reductant mixture and collected. The vapor pressure of the reductant metal must be several orders of magnitude less than the vapor pressure of the actinide metal. 

Preparation of base metals by coupled reduction with platinum group metals. Very pure metals of the alkaline- earth, lanthanide and actinide series can be prepared from their oxides (or fluorides) through coupled reduction by pure hydrogen in presence of platinum group metals. According to a precursory paper on this subject (Berndt et al. 1974), the preparation scheme of Li, Ca, Sr, Ba, Am and Cf was described. As an example, Ca can be obtained by synthesis of a Pt compound, followed by its vacuum decomposition and recovery by distillation of the more volatile base metal ... 

Alcohols. Alcohols are among the most common solvate ligands in actinide chemistry (Table 13) historically the hydrated chloride complexes were reacted with alcohol in benzene, and the water of hydration removed by azeotropic distillation of the benzene. More recent examples result from the crystallization of anhydrous halides from alcoholic solvent. Similarly, solvates of alkoxide complexes result from rnetathesis or solvolysis reations in alcohol. The molecular structures of the halides AnCl4(Pr OH)4 (An = Th, U) have been reported,the coordination geometry about the metal is a distorted dodecahedron. 

Molten-Tin Process for Reactor Fuels (16). Liquid tin is being evaluated as a reaction medium for the processing of thorium- and uranium-based oxide, carbide, and metal fuels. The process is based on the carbothermic reduction of UO2 > nitriding of uranium and fission product elements, and a mechanical separation of the actinide nitrides from the molten tin. Volatile fission products can be removed during the head-end steps and by distilling off a small portion of the tin. The heavier actinide nitrides are expected to sink to the bottom of the tin bath. Lighter fission product nitrides should float to the top. Other fission products may remain in solution or form compounds with... 

Because both zinc and magnesium are volatile, these acceptor alloy elements are separated from the actinides by vacuum distillation. The zinc-magnesium overhead product from vacuum distillation is recycled. After the volatile solvent metals are removed, the resultant distillation bottom products (U-Pu for core fuel and U for blanket fuel) are converted to suitable oxides by reaction with oxygen. The oxide products are available for refabrication into new fuel. The FP-3 elements that follow plutonium and the... 

A fused salt-molten metal process has also been examined for separating californium [36, 37]. In principle, it may also be possible to reduce actinide oxides with thorium metal and distill away the more volatile californium metal (see Section 11.6.1). The separation of californium oxide from curium oxide using a vacuum sublimation procedure has also been reported [38]. 

The first approach to the synthesis of actinide tetracyclopentadienyls, Cp4Th (Fischer and Tribner 1962) and CP4U (Fischer and Hristidu 1962), was made by reacting the actinide tetrachlorides and KCp in benzene. These compounds, due to their low solubility, required purification by Soxhlet extraction. Some other alternative synthetic approaches to tetracyclopentadienyl derivatives included the reaction of the metal tetrafluorides with dicyclopentadienyl magnesium in the absence of solvent (Reid and Wailes 1966) and, in the case of M = U, the reaction of uranium tetradiethylamide and freshly distilled cyclopentadiene (Paolucci et al. 1985a) ... 

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