Diffusion of actinides in glasses containing simulated radioactive wastes

Abstract

Diffusion coefficients of radionuclides²³⁷Np,²³⁹Pu and²⁴¹Am in simulated alumina phosphate and alumina borosilicate glasses at temperatures lower than their transformation temperature were determined. Actinides are known to be the least mobile elements. In particular, the diffusion coefficients of actinides in alumina phosphate glasses at 673 K are about 10⁻¹⁸ m²·s⁻¹, and in alumina borosilicate at 773 K about 10⁻¹⁹ m²·s⁻¹. It is shown that crystallization of glasses leads to increasing²³⁷Np diffusion mobility. It is also shown that a rather small quantity of water absorbed by a crystallized alumina phosphate glass in tensifies low-temperature migration of²³⁷Np.