Reducing hazard in spent fuel removal using colloidal silica gel

Nuclear site decommissioning involves the retrieval and handling of radioactive waste. Waste removal from nuclear reactors and/or storage facilities, such as spent fuel pools and storage silos, represents a potential hazard in terms of radiation exposure for the workforce and the surrounding environment. This study explores the suitability of colloidal silica grouting around radioactive waste to reduce radiation exposure during retrieval operations. Previous work on colloidal silica gel has proved its potential to form low-permeability hydraulic barriers, and to inhibit the diffusion of radionuclides through the gel, making it a promising material for spent fuel recovery applications. This work provides experimental evidence that colloidal silica hydrogel can maintain its integrity upon exposure to temperatures typical of the nuclear waste stored within pools and silos, both in standard conditions (up to 60 °C), and during loss of cooling/loss of coolant accidents (>100 °C).