A radioactive containment composition may be created for containing radionuclides from a radioactive material by mixing a clay mineral with water. This mixture may form an aqueous clay suspension, which in turn can be refined by filtering to remove coarse material. The aqueous clay suspension may be applied to a radioactive material, allowing the radionuclides to be exchanged with cations in the aqueous clay suspension. The resulting aqueous slurry may be collected, heated and analyzed.