Wet chemical processing for nuclear waste glass to retrieve radionuclides.

Here, we show unexpected and significant elution behavior of various elements from simulated nuclear waste glass (NWG) in ∼10° mol dm acidic solutions below 100 °C, where a borosilicate-based glass matrix has been believed to be chemically durable. Most elements like glass main components (Li, B, Na, Ca, Al, and Zn, but except for Si) and simulated radionuclides (Rb, Cs, Sr, Ba, Se, Te, Mn, Pd, Mo, rare earths, Cr, Fe, and Ni) were remarkably eluted from the simulated NWG in ∼10° M HNO aq with Cl at 90 °C. Especially, the elution of Pd is governed by its coordination chemistry including a redox reaction, because Pd(0) present in the simulated NWG has to be oxidized to Pd which forms [PdCl] for its dissolution. While Zr in simulated NWG is sparingly eluted even in this treatment, its elution actually proceeds in 1-3 M HSO aq at 90 °C thanks to strong coordination of Zr(IV) with SO. Through design and optimization of the leaching conditions, a protocol of the wet chemical process to retrieve the radionuclides from simulated NWG has been proposed and demonstrated.