Thorium thermodynamic properties

Americium. The low solubilities and high sorption affinity of thorium and americium severely limit their mobility under environmental conditions. However, because each exists in a single oxidation state—Th(IV) and Am(III)— under environmentally relevant conditions, they are relatively easy to study. In addition, their chemical behaviors provide valuable information about the thermodynamic properties of trivalent and tetravalent species of uranium, neptunium, and plutonium. 

Amorphous thorium oxyhydroxides with varying chemical composition, water content and particle size have also different thermodynamic properties. This may reflect the differences between reported solubility data. Typical examples of discrepancies between solubility data measured at the same ionic strength are shown in Figure VII-14. 

There is a large corpus of data on the phase relationships and stabihty of the thorium caibides. Unfortunately, much of this information is conflicting, and it is still not possible to give many precise values for the thermodynamic properties of the carbides. These discrepancies may be due in part to the great difficulty encountered in preventing oxygen contamination of these materials. 

This is a study of the thermodynamic properties of solutions of the actinides and some fission products in liquid bismuth. For dissolution of thorium, the cell... 

ARO] Aronson, S., Thermodynamic properties of thorium carbides from... 

Cater, E. D., Thom, R. J., Walters, R. R., Thermodynamic properties of uranium and thorium monosulfide, IMD Special Report Series, Report 10, (1964). Cited on pages 271, 481. 

Arorrson, S., Sadofsky, J., Thermodynamic properties of non-stoichiometric thorium monocarbide, J. Inorg. Nucl. Chem., 27, (1965), 1769-1778. Cited on pages 339, 342, 343,488. 

WES/TAK2] Westrum Jr., E. F., Takahashi, Y., Stout, N. D., The heat capacity and thermodynamic properties of hypostoichiometric thorium dicarbide from 5 to 350 K, J. Phys. Chem., 69, (1965), 1520-1524. Cited on pages 340, 493. 

SAT2] Satow, T., Thermodynamic properties and nonstoichiometiy of thorium monocarbide, J. Nucl. Mater., 21, (1967), 255-262. Cited on pages 339,342, 343. 

Flotow, H. E., Osborne, D. W., Walters, R. R., Thorium monosulfide heat capacity and thermodynamic properties from 1-350 K. Re-evaluation of the magnetic entropy of manium monosuffide, J. Chem. Phys., 55, (1971), 880-886. Cited on pages 269,270, 550. 

F., Raspopin, S. P., Thermodynamic properties of thorium-antimony alloys, At. Energ., 37, (1974), 418, in Russian. Cited on page 333. 

Ackemiann, R. J., Tetenbaum, M., High-temperature thermodynamic properties of the thorium-oxygen system, High Temp. Sci., 13,... 

Most of the recent experimental work on the detailed thermodynamic properties of thorium compounds has been on solubilities and aqueous solutions. The large number of hydroxide complexes of Th(IV) and the propensity to form colloidal solutions, makes the interpretation of these studies a challenging task. As noted in previous reviews, the development of laser-based spectroscopic techniques has been a useful tool in our increased understanding of these phenomena, and it is gratifying that... 

This volume provides the first detailed, well-documented and comprehensive review of the thermodynamic properties of thorium, its compounds and aqueous species, supplementing the earlier, less-detailed reviews noted in the Introduction (Chapter I). 

D6. Wagman, D.D. W.H. Evans V.B. Parker R.H. Schumm B.L. Nuttall Selected Values of Chemical Thermodynamic Properties Corapounda of Uranium, Protactinium, Thorium. Actinium, and the Alkali Metals. NBS Tech Note 270-8 (1981)... 

The thermodynamic data, Gibbs energies, enthalpies and entropies of formation of intermetallic compounds have been obtained from a literature search. We have also consulted the handbook Selected values of thermodynamic properties of binary alloys by Hultgren et al. (1973a) and a compilation of thermodynamic data on transition metal based alloys done by de Boer et al. in 1988. For the actinide-based alloys a literature search and a critical analysis of the data was done by Rand and Kubaschewski (1963) for uranium compounds, by Rand et al. (1966) for plutonium alloys, by Rand et al. (1975) for thorium alloys, and more recently by Chiotti et al. (1981) for binary actinide alloys. We have included in our review the data obtained from the original publications and also the assessed data of Chiotti et al. (1981) when they were different. 

The last chapter (134) in this volume is an extensive review by Colinet and Pasturel of the thermodynamic properties of landianide and actinide metallic systems. In addition to compiling useful theiTnodynamic data, such as enthalpies, entropies, and free eneigies of formation and of mixing, the authors have made an extensive comparative analysis of the thermodynamic behavior of the rare earths and actinides when alloyed with metallic elements. They note that when alloyed with non-transition metals, the enthalpies of formation of uranium alloys are less negative than those of the rare earths while those of thorium and plutonium are about the same as the latter. For transition metal alloys the formation enthalpies of thorium and uranium are more negative than diose of the rare earths and plutonium (the latter two are about the same). The anomalous behaviors of cerium, europium and ytterbium in various compounds and alloys are also discussed along with the effect of valence state changes found in uranium and plutonium alloys. 

Critical efforts to compile and to assess actinide thermodynamic properties have improved in more recent years. Krestov [10] prepared an extensive compilation of rare-earth and actinide thermochemical properties. Rand [11] comprehensively and critically reviewed thorium thermodynamics, and the thermodynamics group of the US National Bureau of Standards [12] published the final volume of the Technical Note 270 series, which included the elements actinium through uranium. At nearly the same time the parallel compendium of Glushko et al. [13] was published in the USSR. The most contemporary and thoroughly annotated compilation is the fourteen-part series issued under the auspices of the International Atomic Energy Agency, 7%e Chemical Thermodynamics of Actinide Elements and Compounds, of which nine volumes [14-21, 354] have been published as of the time of writing. 

Table 17.14 represents a listing of all actinide compounds and other species for which measured or estimated thermodynamic properties are available. The sequence of species is by actinide element, with subordinate elements following the US National Bureau of Standards standard order of arrangement. Original literature references have been cited, unless there is an authoritative review or assessment. Error limits are given wherever possible. This tabulation attempts to be self-consistent with the CODATA [128] thermodynamic compilations, and in general accepts IAEA assessments [14-21], which are consistent with CODATA-IUPAC selected data. In many cases for thorium and uranium compounds the NBS [12] tabulations were accepted it should be pointed out that the NBS compilation is self-consistent but not always contemporary and not in exact agreement with CODATA key values. Estimated values of thermodynamic properties are shown in parentheses. 

Belle, J. (1984) Thermodynamic and thermochemical properties of ThO and ThOj-UOj, Chapter 5, in Thorium Dioxide Properties and Nudear Applications, DOE/NE-0060 (eds J. Belle and R.M. Berman), Naval Reactors Office, US Department of Energy. 

Many experimental and theoretical studies of thermochemical and thermophysical properties of thorium, uranium, and plutonium species were undertaken by Manhattan Project investigators. Some of these reports appeared in the National Nuclear Energy Series [1]. These papers, and others in the literature through 1956, formed the basis for Table 11.11 Summary of thermodynamic data for the actinide elements of the first edition of this book. That table, completed by J. D. Axe and E. F. Westrum Jr, listed 126 species, of which the properties of 40 were estimates. A fair measure of the progress in actinide thermodynamics is the number of subsequent research papers and reviews another measure is the 731 species included in Table 17.14 of this chapter, few of which are estimates. 

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