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J. M. Haschke, R. L. Bassett

Control of plutonium dioxide solubility by amorphous tetrahydroxide: A critical review of the model

Solubility data for dissolution of plutonium dioxide and tetrahydroxide in laboratory and natural waters are compared with results of modeling calculations. Evaluation shows that selection of metastable Pu(OH)₄ as the solubility-controlling solid results in predicted steady-state plutonium concentrations that are not conservative and oxidation-state distributions that are inconsistent with observation. Although only the presence of Pu(III) and Pu(IV) is predicted at measured solution potentials, Pu(V) and Pu(VI) predominate (>95%) in steady-state solutions at pH 1-9. Behavior is inconsistent with thermodynamic and kinetic constraints of the conceptual chemical model and a strong dependence of experimental equilibrium expressions on the amount of solid hydroxide in the steady-state solution suggests that dissolution of plutonium oxide is not an equilibrium process.

Radiochimica Acta, Oldenbourg Wissenschaftsverlag

Print ISSN: 0033-8230
Volume: 90, 09/2002
Pages: 505

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