Silver-phosphate glass matrix for iodine conditioning: From sorbent design to vitrification

Abstract

A new route for the synthesis of silver-phosphate based sorbent beads as precursors of final iodine waste form is proposed here. This sorbent is used to entrap gaseous iodine produced during the reprocessing of spent nuclear fuels and to be directly transformed into materials composed of a silver phosphate glass phase considered as high efficient iodine containment matrix for long-term storage in deep geological repository. Using sacrificial organic template method (alginate) and well controlled calcination of the obtained silver phosphate grains materials, this innovative synthesis makes in-situ formation of metallic silver inside them. Ag0 then can easily entrap iodine when in contact with gaseous iodine. The obtained sorbent were tested for iodine trapping in static conditions. They showed great performances with a catch rate of 480 mg.g−1. The iodine-loaded sorbent were finally heat treated at 650 °C with an iodine loss lower than 3% wt. The resulted materials shows the presence of the expected silver phosphate glass matrix with a great iodine incorporation of 9% mol.