Rapid synthesis of Pb5(VO4)3I, for the immobilisation of iodine radioisotopes, by microwave dielectric heating

13 June 2011
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Rapid synthesis of Pb5(VO4)3I, a potential immobilisation host for iodine radioisotopes, was achieved in an open container by microwave dielectric heating of a mixture of PbO, PbI2, and V2O5 at a power of 800 W for 180 s (at 2.45 GHz). The resulting ceramic bodies exhibited a zoned microstructure, differentiated by inter-granular porosity and phase assemblage, as a consequence of the inverse temperature gradient characteristic of microwave dielectric heating.

A renaissance of interest in nuclear energy has been driven by the desire to reduce dependence on fossil fuels and CO₂ emissions. However, a major expansion of nuclear energy is likely to demand innovative and cost effective improvements to the processing and disposal of spent nuclear fuel and nuclear wastes. Iodine radioisotopes constitute an important fraction of the fission product inventory arising from fission of ²³⁵U in thermal reactors. ¹²⁹I is the most important of these radioisotopes with respect to potential long term dose arising from direct disposal and reprocessing of nuclear fuels and constitutes 0.8% of the total fission product inventory. The high radiotoxicity of ¹²⁹I arises from the combination of β, γ decay (0.06 MeV β, 0.025 MeV γ), long half life (15.7 × 10⁶ y), high mobility in the environment and accumulation in the human thyroid gland leading to thyroid cancer.

This article was originally published in the Journal of Nuclear Materials (2011) doi:10.1016/j.jnucmat.2011.04.041, in press.