Plutonium kinetics

Bergeonneau, P., C. Jaonen, M. Germain, and A. Bathellier. 1979. Uranium, Neptunium, and Plutonium Kinetics of Extraction by Tributylphosphate and Trilaurylamine in a Centrifugal Contactor. Proceedings of International Solvent Extraction Conference (ISEC 77), September 9-16, 1977, Toronto, Canada, vol. 2, 612-619. 

Eyman, L. D., J. R. Trabalka, and F. N. Case. 1976. Plutonium-237 and -246 Their production and use as gamma tracers in research on plutonium kinetics in an aquatic consumer, pp. 193-203. In Environmental Toxicity of Aquatic Radionuclides Models and Mechanisms (M. W. Miller and J. N. Stannard, eds.). Ann Arbor Science Publishers, Ann Arbor. 

Other Coordination Complexes. Because carbonate and bicarbonate are commonly found under environmental conditions in water, and because carbonate complexes Pu readily in most oxidation states, Pu carbonato complexes have been studied extensively. The reduction potentials vs the standard hydrogen electrode of Pu(VI)/(V) shifts from 0.916 to 0.33 V and the Pu(IV)/(III) potential shifts from 1.48 to -0.50 V in 1 Tf carbonate. These shifts indicate strong carbonate complexation. Electrochemistry, reaction kinetics, and spectroscopy of plutonium carbonates in solution have been reviewed (113). The solubiUty of Pu(IV) in aqueous carbonate solutions has been measured, and the stabiUty constants of hydroxycarbonato complexes have been calculated (Fig. 6b) (90). 

T. W. Newton, The Kinetics of the Oxidation Reduction Reactions of Uranium, Neptunium, Plutonium, andMmericium inMqueous Solution, TlD-26506, U.S. Energy, Research, and Development Administration (ERDA) Technical Information Center, Washington, D.C., 1975. 

Wlieii very heavy nuclei, such as those of uranium and plutonium, are split into lighter nuclei having less total mass than the very heavy nuclei, energy is released. The process is called nuclear fission. In either nuclear fission or nuclear fusion, much of the convened rest energy emerges as kinetic energy, heat, and light. 

Kinetic data11 for the reaction between plutonium(VI) and uranium(IV), Eq. (2-43), carried out with stoichiometric concentrations... 

Sontag W. 1986. Multicompartment kinetic models for the metabolism of americium, plutonium and uranium in rats. Hum Toxicol 5 163-173. 

Fissile materials are defined as materials that are fissionable by nentrons with zero kinetic energy. In nuclear engineering, a fissile material is one that is capable of snstaining a chain reaction of nuclear fission Nuclear power reactors are mainly fueled with manium, the heaviest element that occurs in natnre in more than trace qnantities. The principal nuclear energy soiuces are maninm-235, plutonium-239, uranium-233 and thorium. 

PoweU BA, Duff MC, Kaplan Dl, Field RA, Newville M, Hunter BD, Bertsch PM, Coates JT, Serkiz SM, Sutton RS, Triay IR, Vaniman DT (2006) Plutonium oxidation and subsequent reduction by Mn(lV) minerals in Yucca Mountain tuff Environ Sci Technol 40 3508-3514 Power LE, Aral Y, Sparks DL (2005) Zinc adsorption effect on arsenite oxidation kinetics at the bimessite water interface. Environ Sci Technol 39 181-187 Purdue EM, Wolfe NL (1983) Prediction of buffer catalysis in field and laboratory studies. Environ Sci Technol 17 635-642... 

Since the water movement will be very slow compared with the rate at which the wastes dissolve, we are concerned first and foremost with equilibrium solubility. Also, if only to relate behaviour on the geological time scale to that on the laboratory time scale, we will need to know about the mechanisms and kinetics of dissolution and leaching. The waste forms envisaged at present are glass blocks containing separated fission products and residual actinides fused into the glass and, alternatively, the uranium dioxide matrix of the used fuel containing unseparated fission products and plutonium. In the... 

In previous work (l.> > ) it was found that the kinetics of sorption was an important parameter affecting the migration of nuclides in geologic media. For example, in experiments designed to measure the kinetics of reaction for radionuclides in solution with tablets of rock, it was found that periods from several minutes to several hours were required for the radionuclides to reach steady state concentrations on the rock tablets and in the solutions. Figure 1 shows the reaction curves found for the sorption of plutonium and americium from solution by a tablet of granite. The reaction rates for the sorption of plutonium and americium from solution are not the same, and both require a number of hours to reach steady state concentrations. 

The redox chemistry of the actinide elements, especially plutonium, is complex (Katz et al., 1980). Disproportionation reactions are especially important for the +4 and +5 oxidation states. Some of the equilibria are kinetically slow and irreversible. All transuranium elements undergo extensive hydrolysis with the +4 cations reacting most readily due to their large charge/radius ratio. Pu (IV) hydrolyzes extensively in acid solution and forms polymers. The polymers are of colloidal dimensions and are a serious problem in nuclear fuel reprocessing. 

The small number of atoms involved in some radiochemical procedures can alter the expected behavior. Although time-dependent processes obeying first-order kinetics are not changed by changes in concentration, the same is not true of second-order kinetics. For example, at 10-2 M, isotopic exchange between U(IV) and U(VI) has a lifetime of 2h, whereas at 10-10M, the same lifetime is 400 d. Another example is Np(V), which is unstable with respect to disproportionation and yet jjrCi / L solutions of NpOj are stable. The extreme dilution in some solutions can mean that equilibrium is not reached due to kinetic limitations. Fallout plutonium, present in the aqueous environment at concentrations of 10 18-10 17 M, has not reached equilibrium in over 40 y. 

Tin and americium were so extensively sorbed under all conditions that isotherm data could not be obtained. These elements are not significantly mobile in the Mabton Interbed aquifer. Values of Freundlich constants for technetium, radium, uranium, neptunium, and plutonium are given in Table IV. The Freundlich equation did not fit the selenium sorption data very well probably because of slow sorption kinetics or precipitation. Precipitation was also observed for technetium at 23°C for concentrations above 10 7M. This is about the same solubility observed for technetium in the sandstone isotherm measurements. Linear isotherms were observed only in the case of radium sorption. In general, sorption on the Mabton Interbed was greater than on the Rattlesnake Ridge sandstone. This is probably due to the greater clay content of the Mabton standard. 

Gray, L. W., "The Kinetics of the Ambient Temperature Dissolution of Plutonium Metal in Sulfamic Acid," USDOE Report DP-1484, E. I. du Pont de Nemours Co., Savannah River Laboratory, Aiken, S.C., 1978. 

Our basic assumption of the intercorrelation of the migration coefficients and surface absorption coefficients to the migration through fissures is verified. However, a great deal of effort must be spent studying the effects of other solute species, the chemical nature of the plutonium itself, and the kinetics of the absorption process before any understanding of the macroscopic characteristics of the transport of plutonium can be reached. 

Hydroxylamine salts were found to be good reductants of plutonium, under certain conditions ( 5). Interest in these reducing agents stemmed from the desire to avoid the introduction of metallic cations in the separated plutonium product. Hydroxylamine sulfate was used on a large scale at the Savannah River Plant (j>). While partitioning was satisfactory, the objectionable presence of sulfate ions led to the adoption of hydroxylamine nitrate (HAN). The reaction mechanism and kinetics of the HAN reduction of plutonium have been studied extensively The... 

Conventional solvent extraction contactors, mixer-settlers or pulsed columns, have been used exclusively until now for the Pu-U partitioning step. Centrifugal contactors have been considered, but there has been some concern about the compatibility of short residence time with the kinetics of plutonium reduction. 

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