Transuranium elements Neptunium Plutonium

Especially interesting in a discussion of radionuclide speciation is the behaviour of the transuranium elements neptunium, plutonium, americium and curium. These form part of the actinide series of elements which resemble the lanthanides in that electrons are progressively added to the 5f instead of the 4f orbital electron shell. The effective shielding of these 5f electrons is less than for the 4f electrons of the lanthanides and the differences in energy between adjacent shells is also smaller, with the result that the actinide elements tend to display more complex chemical properties than the lanthanides, especially in relation to their oxidation-reduction behaviour (Bagnall, 1972). The effect is especially noticeable in the case of uranium, neptunium and plutonium, the last of which has the unique feature that four oxidation states Pum, Pu, Puv and Pu are... 

The first transuranium elements, neptunium and plutonium, were obtained in tracer amounts from bombardments of uranium by McMillan and Abelson and by Seaborg, McMillan, Kennedy, and Wahl, respectively, in 1940. Both elements are obtained in substantial quantities from the uranium fuel elements of nuclear reactors. Only plutonium is normally recovered and is used as a nuclear fuel since, like 235U, it undergoes fission its nuclear properties apparently preclude its use in hydrogen bombs. Certain isotopes of the heavier elements are made by successive neutron capture in 239Pu in high-flux nuclear reactors (> 1015 neutrons cm-2 sec- ). Others are made by the action of accelerated heavy ions of B, C, N, O or Ne on Pu, Am or Cm. 

The true stars of Seaborg s 1944 Periodic Table are the transuranium elements neptunium (Np) and plutonium (Pu) as well as elements 89 to 92 (actinium, thorium, protactinium, and uranium). Neptunium was synthesized by McMillan and Abelson at Berkeley in 1940. In late 1940 and early 1941 McMillan, Kennedy, Wahl, and Seaborg made Pu through bombardment of uranium with deuterons in early 1941, and Pu was obtained by bombarding uranium with neutrons. It was Seaborg who, m 1944, proposed a new series of compounds for the Periodic Table—the actinides—analogous to the rare earths or lanthanides. In his book The Periodic Kingdom, Atkins describes the lanthanides... 

Edwin M. McMillan and Phillip H. Abelson succeeded in synthesizing the first transuranium element, neptunium (element 93), at the University of California, Berkeley, in 1940. In 1941, Glenn T. Seaborg synthesized and identified element 94 (plutonium), and over the next several years, researchers under his direction at UC Berkeley discovered nine other transuranium elements. In 1945 Seaborg suggested that the elements heavier than element 89 (actinium) were misplaced as transition metals and should be relocated on the periodic table in a series below the transition metals... 

Planet pluto) Plutonium was the second transuranium element of the actinide series to be discovered. The isotope 238pu was produced in 1940 by Seaborg, McMillan, Kennedy, and Wahl by deuteron bombardment of uranium in the 60-inch cyclotron at Berkeley, California. Plutonium also exists in trace quantities in naturally occurring uranium ores. It is formed in much the same manner as neptunium, by irradiation of natural uranium with the neutrons which are present. 

Because of the high rate of emission of alpha particles and the element being specifically absorbed on bone the surface and collected in the liver, plutonium, as well as all of the other transuranium elements except neptunium, are radiological poisons and must be handled with very special equipment and precautions. Plutonium is a very dangerous radiological hazard. Precautions must also be taken to prevent the unintentional formulation of a critical mass. Plutonium in liquid solution is more likely to become critical than solid plutonium. The shape of the mass must also be considered where criticality is concerned. 

Plutonium is the second transuranium element after neptunium. The element was named after the planet Pluto. 

MCMILLAN, EDWIN M. (1907-1991). An American physicist who won the Nobel prize in chemistry in 1951 along with Glenn T. Seaborg lor their discoveries In the chemistry of the transuranium elements. His work included research in nuclear physics and particle accelerator development as well as microwave radar and sonar. He and his colleagues discovered neptunium and plutonium. He was the recipient of the Atoms for Peace prize in 1963. His Ph D. in Physics was awarded from Princeton University. 

Zhu, Y., Song, C. 1992. Recovery of neptunium, plutonium and americium from highly active waste. Tri-alkyl phosphine oxide extraction. In Transuranium Elements A Half Century. Morss, L.R. Fuger, J., Eds. ACS, Washington, DC, pp. 318-330. 

The actinides include another part of the periodic table called the transuranium elements, which begin with neptunium (atomic number 93) and end with roentgenium (atomic number 111) back up in Period 7. Neptunium and plutonium are the only... 

C) It has been proposed by some that transuranium elements, like neptunium and plutonium, were once present on Earth in fairly significant quantities. Explain why they are not found today. 

Zachariasen, W. H. X-Ray Diffraction Studies of Fluorides of Plutonium and Neptunium. Chemical Identity and Crystal Structure. In G. T. Seaborg, J. J. Katz, and W. M. Manning (Eds.), The Transuranium Elements, National Nuclear Energy Series, Div. IV-14B, p. 1463. New York McGraw Hill Co. 1949. 

Of special interest in the mass spectrometric determination of transuranium elements is the characterization of microparticles stemming from different radioactivity release scenarios. Such microparticles bearing radionuchdes, in particular uranium, plutonium, neptunium and americium, can enter the environment and therefore the human food chain through different processes which can be related to the nuclear fuel cycle as well as to clandestine nuclear activities. In addition, nuclear safeguards programmes seek to determine the uranium isotope abundances of individual p,m sized particles. Anomalous amounts of or may indicate that artificial isotope enrichment... 

Separation of Actinides from the Samples of Irradiated Nuclear Fuels. For the purpose of chemical measurements of burnup and other parameters such as accumulation of transuranium nuclides in irradiated nuclear fuels, an ion-exchange method has been developed to separate systematically the transuranium elements and some fission products selected for burnup monitors (16) Anion exchange was used in hydrochloric acid media to separate the groups of uranium, of neptunium and plutonium, and of the transplutonium elements. Then, cation and anion exchange are combined and applied to each of those groups for further separation and purification. Uranium, neptunium, plutonium, americium and curium can be separated quantitatively and systematically from a spent fuel specimen, as well as cesium and neodymium fission products. 

Koch/ G. "Recovery of Neptunium-237/ Plutonium-238/ and Plutonium-242"/ in Koch/ G. (ed.)/ "Transuranium Elements"/ Part A1 IIf System No. 71 of "Gmelin Handbook of Inorganic Chemistry"/ Supplement Vol. 7b/ p. 288-315/ Berlin-Heidelberg-New York 1974... 

Plutonium as well as all the other transuranium elements except neptunium are radiotoxic. In the media, plutonium is often... 

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