Improved methods for nuclear waste disposal are crucial for the long term storage and safety of high level radioactive waste (HLW) products. To withstand the harsh effects of gamma irradiation, a material must be able to accommodate numerous radiation damage effects. A proposed method to treating that waste is to encapsulate it in a matrix made of complex oxide materials, such as pyrochlores with a general forumula of A2B2O7. The rare-earth hafnate pyrochlores have the potential to advance the current methods of HLW disposal due to their robust chemical stability in radioactive environments, their high thermal stability, and their natural structural compatibility with radionuclide species. In this study, based on a combined co-precipitation and molten-salt synthesis method: nanoparticles of yttrium, lanthanum, praseodymium, gadolinium, erbium and lutetium hafnates were synthesized at 650°C. Of the compositions irradiated with different doses of γ-rays, yttrium, praseodymium, gadolinium and erbium hafnates proved to be the most chemically stable samples, maintaing their initial crystal structure throughout the irradiation process even to the highest expsoure, i.e. 12800 Gy. While further investigation is still undergoing, e.g. on the particle size effects, these rare-earth hafnate nanocrystals have shown the potential to advance the current methods of HLW disposal due to their robust chemical stability in radioactive environments, their high thermal stability, and their natural structural compatibility with radionuclide species.

Investigating the impact of gamma radiation on rare-earth hafnate nanocrystals

255th National Meeting (2018)

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