Fission products systems using

Assume that one wants to sqjarate uranium from the fission product lanthanum using the two-phase system aqueous 1 M HNO3, the organic adduct former tributyl phosphate, TBP (100%, i.e. undiluted). In this system Dyj = 20 for U(VI), u le for lanthanum Z> = 0.07. If one extracts with a phase ratio of 0.5, then = 0.909 (Ejj = l(X) y = 90.9%) and. 034 ( j, 3.4%). This may be unsatisfactory with respect to both uranium... 

The Model 412 PWR uses several control mechanisms. The first is the control cluster, consisting of a set of 25 hafnium metal rods coimected by a spider and inserted in the vacant spaces of 53 of the fuel assembhes (see Fig. 6). The clusters can be moved up and down, or released to shut down the reactor quickly. The rods are also used to (/) provide positive reactivity for the startup of the reactor from cold conditions, (2) make adjustments in power that fit the load demand on the system, (J) help shape the core power distribution to assure favorable fuel consumption and avoid hot spots on fuel cladding, and (4) compensate for the production and consumption of the strongly neutron-absorbing fission product xenon-135. Other PWRs use an alloy of cadmium, indium, and silver, all strong neutron absorbers, as control material. 

Goishi and Libby have investigated the extraction of pertechnetate from alkali solutions with pyridine. Later work showed that a better extraction is obtained using a mixture of sodium hydroxide and sodium carbonate as the aqueous phase. Since the uranyl carbonate complex is not extracted into pyridine, this system may be used for the separation of technetium from uranium. Distribution coefficients of fission products in pyridine are given in Table 4. Substituted pyridine such as 2,4-dimethylpyridine or 4-(5-nonyl)pyridine ) are useful for separating technetium from solutions containing appreciable amounts of aluminum nitrate. 

In following sections, the selected key recent results from our research group on the separation of fission products (Sr + and Cs ) are outlined. For readers who are interested in IL-based extraction systems for ofher metal ions, several excellent reviews are very helpful. Rogers and coworkers [44] have written an excellent review on use of ILs for extraction of lanfhanides and actinides. 

These results are the basis for optimism concerning the calculated distribution of fission products in fallout using the described method. A further test will be the application of the DELFIC particle distribution calculational system (3) using the calculated particle fission product inventories and comparing calculated and experimental radiation fields. 

FIG U RE 9.4 Extraction chromatographic separation of "Tc(VII) from other fission products in the sample using a sequential injection separation system with a TEVA-Resin column. The signal for the "Tc is shown in the vertically expanded trace in the inset. (Reproduced from Egorov, O. B., O Hara, M. J., Ruzicka, J., and Grate, J. W., Anal. Chem., 70, 977-984, 1998. With permission.)... 

To define more accurately the boundaries of the mass regions that could be accessed with the proposed He-jet coupled mass separator system, production cross sections for both neutron-deficient and neutron-rich nuclei far from stability have been estimated for 800-MeV proton reactions. The spallation-product cross sections were estimated through use of the Rudstam systemstics [RUD66]. For estimation of the fission-product cross sections, however, there is no established, similar approach. Thus, an empirical approach was taken in... 

We report on a number of on-line chemical procedures which were developed for the study of short-lived fission products and products from heavy-ion interactions. These techniques combine gas-jet recoil-transport systems with I) multistage solvent extraction methods using high-speed centrifuges for rapid phase separation and II) thermochromatographic columns. The formation of volatile species between recoil atoms and reactive gases is another alternative. We have also coupled a gas-jet transport system to a mass separator equipped with a hollow cathode- or a high temperature ion source. Typical applications of these methods for studies of short-lived nuclides are described. 

Stainless steel contains iron and nickel—important materials in nuclear power reactors and possible constituents of the materials used to construct nuclear test devices or their supporting structures.8 9 During nuclear weapons tests, stable Fe and Ni isotopes are neutron activated, giving rise to radioactive Fe and Ni along with fission products. In nuclear power plants, moreover, stable Fe and Ni isotopes are released from stainless steel through corrosion, become activated, and are transported to different parts of the reactor system. 

Although ICP-MS has been used for analysis of nuclear materials, often the entire instrument must be in an enclosed hot enclosure [350]. Sample preparation equipment, inlets to sample introduction systems, vacuum pump exhaust, and instrument ventilation must be properly isolated. Many of the materials used in the nuclear industry must be of very high purity, so the low detection limits provided by ICP-MS are essential. The fission products and actinide elements have been measured by using isotope dilution ICP-MS [351]. Because isotope ratios are not predictable, isobaric and molecular oxide ion spectral overlaps cannot be corrected mathematically, so chemical separation is required. 

The n.m.r. characteristics of the isopropylidene acetals of the four possible types of ring A primary, secondary 1,3-glycol systems, exemplified by serratriol (178), lycoclavanol (179), methyl hederagenate (180), and methyl 3-epihederagenate (181), have been tabulated, and provide a useful means of differentiation.132 The reactions of the primary monotosylates of these four types provide further confirmation of stereochemistry.133 With potassium t-butoxide the cis types (178) and (181) afforded oxetans whereas the trans types (179) and (180) were converted into A-seco-aldehydes (182). Appreciable amounts of alkyl oxygen fission products were obtained on lithium aluminium hydride reduction of the monotosylates of (178), (180), and (181), presumably via participation of the 3-hydroxy-group, e.g. (183). 

Surface analytical techniques. A variety of spectroscopic methods have been used to characterize the nature of adsorbed species at the solid-water interface in natural and experimental systems (Brown et al, 1999). Surface spectroscopy techniques such as extended X-ray absorption fine structure spectroscopy (EXAFS) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) have been used to characterize complexes of fission products, thorium, uranium, plutonium, and uranium sorbed onto silicates, goethite, clays, and microbes (Chisholm-Brause et al, 1992, 1994 Dent et al, 1992 Combes et al, 1992 Bargar et al, 2000 Brown and Sturchio, 2002). A recent overview of the theory and applications of synchrotron radiation to the analysis of the surfaces of soils, amorphous materials, rocks, and organic matter in low-temperature geochemistry and environmental science can be found in Fenter et al (2002). 

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