Abstract: A method for solidifying a radioactive iodine-containing waste, in which volatilization of radioactive iodine outward can be suppressed during solidification, and a solidified waste having a high level of confinement of radioactive iodine and a long term stability can be obtained. The method comprised mixing a granular waste containing radioactive iodine, e.g. a granular iodine adsorbent having radioactive iodine adsorbed and collected thereon, with a metal powder, e.g. a copper powder, having a corrosion resistance in an environment of solidified waste disposal, filling the resulting mixture in a metal capsule, and subjecting the whole to hot isostatic pressing to effect solidification. In the resulting solidified waste, particles of the radioactive iodine-containing adsorbents are dispersed and retained in the sintered matrix of the metal powder formed through the isostatic pressing.

Abstract: A method of extracting metal species from a metal species containing medium which comprises contacting the medium with an extractant solvent which comprises a supercritical fluid and a complexant for solubilizing metal species in the said medium and also a conditioning agent for changing the oxidation state of the metal species.

Abstract: The invention relates to the dissolving of plutonium and/or other radioactive elements in an aqueous solution by microwave heating.According to the invention, solid or liquid products containing plutonium and/or other radioactive elements are introduced into a container (7) containing an acid solution, comprising hydrofluoric acid and nitric solution, followed by the microwave heating of the solution containing these products using a chamber or tank (5) placed in a tight enclosure (1), which is supplied with microwaves by means of a coaxial cable or a waveguide (11) connected to the generator (9) located outside the enclosure.The solid products can be plutonium dioxide PuO.sub.2 or organic or mineral radioactive waste materials such as gloves, cellulose products, ion exchange resins, etc. The liquid products can be contaminated organic solvents such as tributyl phosphate in dodecane.

Abstract: A cementitious surface contaminated with a radioactive substance is decontaminated by applying a micro-organism to the surface to degrade the surface. The residue which contains the radioactive substance is then removed by suction, scraping, brushing or abrasion blasting. The micro-organism might comprise an aerobic sulphur oxidising bacteria, or an anaerobic sulphate reducing bacteria, or a mixture thereof. Action of the micro-organism can be stopped as necessary by heating, or by depriving the micro-organism of nutrients.

Abstract: A process for aqueous biphasic extraction of metallic oxides and the like from substances containing silica. Control of media pH enables efficient and effective partition of mixture components. The inventive method may be employed to remove excess silica from kaolin clay.