Bentonite for conservation of special RAW facilities (creation of external engineering safety barriers)

The main objects for creation of external barriers are solid RAW storage facilities, soil burial sites, bunker-type facilities, slurry, tailing and water reservoirs, special industrial water bodies. An external barrier (impervious screens) is a structural element constructed outside of facilities and structures using bentonite-based solutions to protect groundwater from the ingress of contaminants through filtration and migration of radionuclides.

At present this type of barrier is the most demanded. Below is the scheme of modelling of curtain fully eliminating the possible migration of radionuclides beyond the object.

In 2018-23, a number of pilot works were carried out at the facilities of the State Corporation to select the injection composition and technology. Two options were considered: slurry wall technology and jet-grouting. For nuclear power facilities, the latter was chosen because it involves the least amount of soil removal during installation.

The principle of JET-technology is based on destruction of the natural soil structure by the energy of a high-speed jet of injection solution and mixing it with the solution injected under high pressure. In this case, a soil-bentonite pile (pillar) is formed in the soil mass from its surface to the water-retaining layer. The location of piles with intersection of their contours forms a waterproofing curtain (scheme below).