Uranyl nitrate factors

Siddall and his co-workers (46) have examined the barriers to rotation of a series of 2,6-disubstituted anilides. Af-Ethyl-A/-(2,6-xylyl)formamide (9) was recrystallized as a uranyl nitrate complex, and one isomer, which at equilibrium was favored by a factor of 3 1, was enriched up to a 30 1 ratio. The kinetics of rotation were examined at 0 to 29°C. The Arrhenius activation energy was 26 3 kcal/mol and log A was 18.5 2.4 hr-1. Siddall and Gamer (47) were able to obtain an almost pure isomer (which also predominated at equilibrium 1.3 1 for the ethyl compound and 1.1 1 for the methyl compound) of Ar-alkyl- V-(2-methyl-4,6-dibromophenyl)-l-naphthamide (10). The half-lives of... 

Solvent Extraction. The yellow cake is dissolved in nitric acid and extracted from this aqueous phase by 5 percent tributyl phosphate (TBP) in a hydrocarbon diluent. The diluent reduces the density and viscosity of the TBP, enhancing the aqueous/solvent phase separation. The extraction is very specific for uranium, with separation factors of 103 to 105. The product thus obtained is an aqueous uranyl nitrate solution (Fig. 21.14). 

Although Peligot observed in 1842 that uranyl nitrate is soluble in ether, it was not until materials of high purity were needed for nuclear reactors that extensive applications and developments, both industrial and analytical, were made. The literature on applications of liquid-liquid extraction (solvent extraction) is extensive for details of the various procedures the reader is referred to the original papers and to compilations. " This chapter examines separations involving distribution of a solute between two immiscible phases and chemical equilibria of significance to the distribution ratio. Batch, countercurrent, and continuous liquid-liquid extractions are described in turn, followed by consideration of the factors governing the distribution ratio and finally by some illustrative applications. 

Tetravalent neptunium. Srinivasan et al. [S18, S19] measured distribution coefficients of tetravalent and hexavalent neptunium and hexavalent uranium as functions of nitric acid and uranyl nitrate concentrations. At 45 and 60°C, the ratio of the observed [S19] separation factor for tetravalent neptunium to that of hexavalent uranium can be correlated within an average deviation of 6 percent by Eq. (10.25),... 

Mixtures with U. When U is mixed with U, the subcritical limit for a cylinder or slab of UO2F2 solution given by Fig. 10.33 may be increased by the factor given in Fig. 10.36. These factors may also be applied to uniform slurries of water and UO2 provided that the enrichment is greater than 6 w/o or the particle sizes are smaller than 127 im. With enrichment below 6 w/o and larger particles, the factors are smaller than given in Fig. 10.36 because of reduced absorption by The factors are conservative for aqueous solutions of uranyl nitrate because of neutron absorption by nitrogen. 

After filtration of insoluble rest products, the solution containing the remaining fission products, uranyl nitrate, and plutonium nitrate is submitted to an extraction cycle with a solution of 30% of tri-n-butyl-phosphate in kerosene. Uranium and plutonium pass to the organic phase and the fission products remain in the aqueous solution. Since a high decontamination factor of 10 has to be realized for fission products in the U/Pu fraction, the extraction steps are repeated many times using some miser-settler units or some countercurrent extraction columns (Choppin and Rydberg 1980 Pickert and Zech 1981). 

Values of the Effective Multiplication Factor, keff, and Neutron Age to Thermal Energy, r, for Uranyl Nitrate Assemblies... 

Once a sample is collected, the isotopic composition of uranium must be determined as the content is one of the main factors that determine the price of the product. Several mass spectrometric techniques have been developed for direct isotope analysis of gaseous UFg and for indirect analysis (usually after hydrolysis) of liquid and gaseous UFg samples. The use of a thermal ionization mass spectrometer (TIMS), nowadays equipped with several detectors (i.e., multicollector TIMS), has been the method of choice for many years, but the sample must be hydrolyzed to liquid form (uranyl fluoride or uranyl nitrate solutions) and the uranium must be purified (usually not a problem for UFg samples), as mentioned, for example, by ASTM (C1413 2011). The method is used for hydrolyzed samples of UFg (UOjFj (uranyl fluoride)) or for... 

The chemical process leading from the uranyl nitrate solution to the UFe to be delivered to the enrichment process results in a decontamination factor for alpha activity of about 100 beta and gamma activities are reduced to a lower proportion, i. e. by a factor of 2 to 4 (Beck, 1985). From the onset of spent fuel reprocessing, enriched natural uranium has also been contaminated in some instances with traces of Tc, and plutonium isotopes. 

Mn(N03)4] , [Fe(N03)4] and [Sn(N03)4], which feature dodecahedral coordination about the metal [Ce(N03)5] in which the 5 bidentate nitrate groups define a trigonal bipyramid leading to tenfold coordination of cerium (Fig. 11.17b) [Ce(N03)6] and [Th(N03)6] , which feature nearly regular icosahedral (p. 141) coordination of the metal by 12 O atoms and many lanthanide and uranyl [U02] complexes. It seems, therefore, that the size of the metal centre is not necessarily a dominant factor. 

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