Experimental Investigation of Desiccation Behavior in Inorganic Microfiber-Reinforced Engineered Barrier Materials (IMEBM) for Geological Repository of Nuclear Spent Fuel

Secure storage of nuclear spent fuel is of great concern for protecting public health and safety. The standard long-term solution for nuclear waste disposal is containment in geological repositories. Nuclear spent fuel, stored in canisters, is placed deep underground with one or more Engineered Barrier Materials (EBM) forming a buffer between the waste containers and the natural rock. Bentonite clay is commonly used as an EBM for its low cost, long-term stability, low hydraulic permeability in a saturated state, high thermal resistance, high radionuclide retardation capacity, high swelling pressure, and “self-healing” capability. However, bentonite clay subjected to heating from nuclear waste decay may undergo desiccation cracking. In this study, inorganic microfiber reinforcement was evaluated as a method of reducing desiccation cracking in EBM. A restrained ring test method for soils coupled with digital image correlation (DIC) was employed to capture free shrinkage and desiccation cracking. Reinforcement of bentonite clay with 1.0 % wt. basalt fibers was shown to be effective in reducing crack propagation and separation.