Colloid-facilitated transport of Pu, U and Cs through fractured chalk: Laboratory experiments, modelling, and implications for nuclear waste disposal.

The influence of montmorillonite colloids on the mobility of Pu, U and Cs through a chalk fracture was investigated to assess the transport potential for radioactive waste. Radioisotopes of each element, along with the conservative tracer tritium, were injected in the presence and absence of montmorillonite colloids into a naturally fractured chalk core. In parallel, batch experiments were conducted to obtain experimental sorption coefficients (K, mL/g) for both montmorillonite colloids and the chalk fracture material.

Radionuclide transport in brackish water through chalk fractures.

Mobility of radionuclides originating from geological repositories in the subsurface has been shown to be facilitated by clay colloids. In brackish water, however, colloids may flocculate and act to immobilize radionuclides associated with them. Furthermore, little research has been conducted on radionuclide interactions with carbonate rocks.