Hostname: page-component-8448b6f56d-qsmjn Total loading time: 0 Render date: 2024-04-23T10:16:42.230Z Has data issue: false hasContentIssue false
  • English
  • Français

Plutonium Solubility and Speciation to be Applied to the Separation of Hydrothermal Waste Treatment Effluent

Published online by Cambridge University Press:  03 September 2012

M. P. Neu ,
S. D. Reilly  and
W. H. Runde
M. P. Neu
Affiliation:
Chemical Science and Technology Division, Mail Stop G739, Los Alamos National Laboratory, Los Alamos, NM 87545, mneu@lanl.gov
S. D. Reilly
Affiliation:
Chemical Science and Technology Division, Mail Stop G739, Los Alamos National Laboratory, Los Alamos, NM 87545, mneu@lanl.gov
W. H. Runde
Affiliation:
Chemical Science and Technology Division, Mail Stop G739, Los Alamos National Laboratory, Los Alamos, NM 87545, mneu@lanl.gov
Get access

Abstract

One of the most complex problems concerning nuclear waste management and the restoration of plutonium production sites is the treatment and disposition of mixed and TRU wastes. Hydrothermal oxidation, which has been shown to be effective in oxidizing a wide variety of organic material to CO2, water, salts and other nonhazardous oxides, is a promising new technology for the treatment and volume reduction of actinide-containing waste. Information on the speciation and solubility of plutonium under process effluent conditions will facilitate the development of separation techniques for removing it from the treated solutions. Such a strongly oxidizing environment will generate plutonium(VT); and upon the destruction of organics, hydrothermal reactor solutions will contain carbonate. We are investigating the solubility and speciation of the plutonium(VI) carbonate system as a function of ionic strength (0.1 to 5.0 M). Formation constants for the tris- and biscarbonato complexes of plutonium(IV) were determined to be, log β130 = 17.7 and log β120 = 13.6, respectively, by spectrophotometry. These formation constants indicate that PuO2CO3(aq) is the plutonium (VI) carbonate solution species with the largest relevant stability range. We prepared and characterized the corresponding solid using XRD, EXAFS, and diffuse reflectance, and initiated solubility experiments in 0.1, 0.2, 0.5, 1,2, and 5 M NaCl at 22±1°C under 100% CO2. Data collected thus far yield the solubility products, log Ksp mol2/kg2 = -12.9 (0.1 m NaCl), -12.4 (0.2 m NaCl), -12.5 (0.5 m NaCl), -12.3 (1 m NaCl), -12.2 (2 m NaCl), -12.3 (5 m NaCl).

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 465: Symposium II – Scienfific Basis for Nuclear Waste Management XX , 1996 , 759
Copyright
Copyright © Materials Research Society 1997

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

[1] a. Modell, M., in Standard Handbook of Hazardous Waste Treatment and Disposal edited by Freeman, H.M., (McGraw Hill, New York, 1989) pp. 8. 153–8. 168.Google Scholar
b. Tester, J.W., Holgate, H.R., Armellini, F.J., Webley, P.A., Killilea, W.R., Hong, G.T., Barer, H.E., in Supercritical Water Oxidation Technology: Process Development and Fundamental Research,” ACS Symp. Ser. 518 35 (1993).Google Scholar
[2] Robinson, J.M., Foy, B.R., Dell'Orco, P.C., Anderson, G., Archuleta, F., Atencio, J., Breshears, D., Brewer, R., Eaton, H., McFarland, R., Mclnroy, R., Reynolds, T., Seillo, M., Wilmanns, E., Buelow, S.J., in Technology and Programs for Radioactive Waste Management and Environmental Restoration. Vol. 1, (Waste Management Symposia, Tucson, AZ, March 1993) p. 709–716.Google Scholar
[3] Clark, D.L., Hobart, D.E., Neu, M.P., Chem. Rev. 95, 25 (1995) and references therein.Google Scholar
[4] Details to be published in a forthcoming paper.Google Scholar
[5] NONLIN 94.05.13b developed by A.R. Felmy, Pacific Northwest National Laboratory; a chemical equilibrium program based on the Gibbs free energy minimization procedure by Harvie, et al. Geochim. Cosmochim. Acta 48, 723 (1984).Google Scholar
[6] Robouch, P., Vitorge, P., Inorg. Chim. Acta 140, 239 (1987).Google Scholar
[7] Grenthe, I., Fuger, J., Donigs, R.J.M., Lemire, R.J., Muller, A.B., Nguyen-Trung, C., Wanner, H., Chemical Thermodynamics of Uranium; Elsevier Science Publishing Company, Inc.: North-Holland, 1992; Vol. 1.Google Scholar
[8] Navratil, J.D., Bramlet, H.L., J. Inorg. Nucl. Chem. 35, 157 (1973).Google Scholar
[9] Runde, W.H., Lierse, Ch., Eichhorn, B., to be published in Geochim. Cosmochim. Acta.Google Scholar
[10] Pahalidis, I., Runde, W., Kim, J.I., Radiochim. Acta 61, 141 (1993).Google Scholar
[11] Gel'man, A.D., Moskvin, A.I., Zaitseva, V.P., Radiochim. Acta 4, 154 (1962).Google Scholar