Radioactive waste stays trapped in underground rock much more effectively if it leaks through narrow, tight channels rather than wide cracks.
April 24, 2026
Original Paper
Contaminant transport in channel networks in fractured rocks-Impact on radioactive waste repositories in crystalline rocks
SSRN · 6626664
The Takeaway
Logic suggests that spreading a contaminant across a wide surface would give the rock more chances to absorb the poison. This new modeling shows the opposite is true for radioactive isotopes in crystalline rock. Concentrating the flow into narrow, high-speed channels actually increases the amount of material that gets stuck to the rock walls. The physical interaction between the waste and the stone changes when the flow is restricted. This discovery means that geological repositories for nuclear waste might be even safer than we previously estimated.
From the abstract
Groundwater flow in fractured crystalline rock is often assumed to occur over entire fracture planes. However, field observations indicate that flow is commonly concentrated in narrow channels. This geometric difference matters because radionuclides diffusing from narrow channels spread into the surrounding rock more efficiently than radionuclides diffusing from wide fractures. Using data from Swedish underground laboratories and conceptual and numerical comparisons, this paper shows that channe