Hydraulic Conductivity of Compact Bentonite With Penetrating Copper Pins

Copper plates are a proposed engineering solution to enhance thermal dissipation from nuclear waste canisters through the surrounding bentonite buffer. However, their long-term effect on the hydraulic integrity of this bentonite buffer is uncertain. This study experimentally investigates the impact of penetrating copper components on the hydraulic conductivity of compact bentonite. We measured the hydraulic conductivity of bentonite blocks penetrated by 0 (control), 5, and 10 copper pins, both at initial saturation and after a 293-day aging period. Initially, hydraulic conductivity decreased from 1.49 × 10⁻13 m·s−1 in the control as the number of pins increased. However, this monotonic trend did not persist; after 293 days, the relationship became non-linear, with the 5-pin block showing the lowest conductivity and the 10-pin block the highest. Crucially, our findings provide no evidence that copper penetration or subsequent corrosion systematically increases hydraulic conductivity. We conclude that the integration of copper plates for thermal management is unlikely to compromise the critical containment function of the bentonite barrier.