Lanthanides fission product

Chen, J., Jiao, R., Zhu, Y. 1997. A cross-flow hot test for separating Am from fission product lanthanide by bis(2,4,4-trimethylpentyl)dithiophosphinic acid. Radiochim. Acta 76 (3/4) 129-130. 

Zhu, Y., Chen, J., Choppin, R.G. 1996. Extraction of americium and fission product lanthanides with CYANEX 272 and CYANEX 301. Solvent Extraction and Ion Exchange 14(4) 543-553. 

Various gel- and porous-type resins have been examined for use in the cation-exchange chromatographic separation of the transplutonium elements from the fission-product lanthanides with an eluent of 11.7 M hydrochloric acid (17). In the case of gel-type resins, very fine ones such as colloidal aggregate, are needed to perform good separation. The number of theoretical plate obtained... 

The thrust of the experimental program at ICPP was to find a separation procedure that would separate plutonium, americium, and curium from high-level first-cycle raffinate (see Table I) and leave behind the cladding elements, salting agents, and the bulk of the fission products. Fission-product lanthanides, because of their similar valence and ionic size, would be expected to follow americium in nearly any simple separation scheme. Americium and curium are present in ICPP waste as trivalent ions while plutonium is most likely present as both Pu(IV) and Pu(VI). Any separation scheme must be applicable to all these ionic actinide species. 

Distribution coefficients of Am and other trivalent transplutonium elements from concentrated LiCl solutions are from 150-fold to more than 1000-fold higher than those of trivalent lanthanides [55]. This phenomenon was used by Moore [56] in various analytical applications it was also exploited at ORNL in the development of the Tramex process for plant-scale separation of americium, curium, and other transplutonium elements from fission product lanthanides [7, 57]. 

The major fission products which will limit overall decontamination (other than from the lanthanides) are Tc, Ru, and Pd. formed to evaluate the actual decontaminations which can be achieved. 

Major limitations in fission product decontamination will require tests with mixer-settlers. However, we anticipate from the distribution ratio measurements that Tc, Ru, and Pd will limit the overall decontamination from beta activity (other than from lanthanides). ... 

Citric acid and nitriloacetic acid (NTA) lanthanide complexes were used in the earliest ion exchange separations of lanthanides from fission product mixtures (Kf = 3.2 for Ce(H3 Cit.)3 and Kf = 10.8 for CeNTA2) (Sillen and Martell, 1964). More recently such polyamino-polycarboxylic acids as ethylenediaminetetraacetic acid (EDTA), 1,2-diaminocyclohexaneacetic acid (DCTA), and diethylenetriaminepentaacetic acid (DTPA) have been prepared. Their lanthanide complexes are very stable (Table 3) and have been widely used in analysis and separation of lanthanide mixtures. They have also been used experimentally to remove internally-deposited 144Ce and other radioactive lanthanide nuclides from animals and man (Foreman and Finnegan, 1957 Catsch, 1962 Balabukha et al., 1966 Palmer et al., 1968 among others). 

Cf produces two fission products that travel in opposite directions. If one projectile hits the sample, ions will be produced. These ions may then be focused and measured by TOF MS. The other projectile may be used to measure the start of the ionization process. This method has been used to study the ions produced from the ionization of metal complexes such as cadmium thiolates (33) and lanthanide phthalocyanine complexes (34). This method has also been used on metal oxides such as La203 to produce metal oxide cluster ions (35). 

Symbol Ce atomic number 58 atomic weight 140.115 a rare-earth metal a lanthanide series inner-transition /-block element metaUic radius (alpha form) 1.8247A(CN=12) atomic volume 20.696 cm /mol electronic configuration [Xe]4fi5di6s2 common valence states -i-3 and +4 four stable isotopes Ce-140 and Ce-142 are the two major ones, their percent abundances 88.48% and 11.07%, respectively. Ce—138 (0.25%) and Ce—136(0.193%) are minor isotopes several artificial radioactive isotopes including Ce-144, a major fission product (ti 284.5 days), are known. 

Promethium does not occur in metallic form in nature. Minute quantities are associated with other rare earths. It also is detected in uranium fission products. It is probably the rarest of the lanthanide elements. 

Fission products, actinides, and lanthanides that are retained in the fuel matrix ... 

G. E. Boyd J. Schubert A.W. Adamson Demonstration of the applicability of ion exchange for adsorption of fission products in trace amounts (lanthanides). 1942... 

The lanthanide elements are very difficult to separate because of their highly similar chemistry, but the earlier actinide elements have sufficiently different redox chemistry to allow easy chemical separations. This is important in the nuclear power industry, where separations have to be made of the elements produced in fuel rods of nuclear power stations as fission products, and of the products Np and Pu, which arise from the neutron bombardment of the uranium fuel. 

The quasi-simultaneous separation and determination of lanthanides and actinides by ion chromatography inductively coupled plasma mass spectrometry combined with the isotope dilution technique and the further use of ion chromatography for the determination of fission products and actinides in nuclear applications are described by Betti et ul.10 48 68... 

C.A. Arrhenius, in 1787, noted an unusual black mineral in a quarry near Ytterby. Sweden, This was identified later as containing yttrium and rare-earth oxides. With the exception of promethium, all members of the Lanthanide Series had been discovered by 1907, when lutetium was isolated. In 1947. scientists at the Atomic Energy Commission at Oak Ridge National Laboratory (Tennessee) produced atomic number 61 from uranium fission products and named it promethium. No stable isotopes of promethium have been found in the earth s crust. 

Fission products and actinides in spent nuclear fuels have also been analyzed using cation-exchange LC [98]. Chromatography was essential in order to separate fission Cs from Ba for the analysis of the lanthanides and to eliminate isobaric interferences in the separation of the actinides. Separation of fission... 

Lanthanides, which account for about one-third of the fission products, are strong neutron-absorbing elements and predominantly exist as trivalent cations in acidic aqueous solutions the solution chemistry of transplutonium elements (TPEs) thus, resembles that of lanthanides (28-31). 

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