Geopolymers have garnered significant industry interest for cementation of radioactive waste due to their low viscosity during production, tolerance to problematic waste components (for typical grout formulations), chemical similarity to cement and the ability to produce them from a range of readily made raw materials.

Geopolymers have demonstrated lower leach rates of fission product surrogates than other encapsulant  alternatives  and this may be used to justify greater waste loading or disposal of boundary wastes to lower repository ratings. However, there is little information on what parameters of raw materials are critical to reliable application, under such conditions required on nuclear encapsulation plants.

This project provides greater understanding of geopolymer reaction, setting and hardening, by investigating fundamental particle interactions so that robust specifications can be developed, and geopolymer wasteform properties and performance can be predicted. It also assesses mobility of fission products and so establish chemical durability.

Specifically, it will...

1. Characterise geopolymer wasteform phase assemblage, micro- and nanostructure, and structure of the pore network,

2. investigate fundamental particle interactions so that robust specifications can be developed,

3. determine radionuclide (e.g. 90Sr and 137Cs)-cement interactions, and

4. assess radionuclide retention.

This will identify key interactions controlling phase evolution, structural evolution across micro, nano and atomic length scales, radionuclide-cement interactions mass transport mechanisms and leaching resistance, and physical and chemical stability in repository relevant conditions.