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The design and development of a novel supercritical extraction experimental facility adapted for safe operation in a glove box for the recovery of radioactive elements from waste is described. The apparatus incorporates a high pressure extraction vessel, reciprocating pumps for delivering supercritical fluid and reagent, a back pressure regulator, and a collection chamber. All these components of the system have been specially designed for glove box adaptation and made modular to facilitate their replacement. Confinement of these materials must be ensured in a glove box to protect the operator and prevent contamination to the work area. Since handling of radioactive materials under high pressure (30 MPa) and temperature (up to 333 K) is involved in this process, the apparatus needs elaborate safety features in the design of the equipment, as well as modification of a standard glove box to accommodate the system. As a special safety feature to contain accidental leakage of carbon dioxide from the extraction vessel, a safety vessel has been specially designed and placed inside the glove box. The extraction vessel was enclosed in the safety vessel. The safety vessel was also incorporated with pressure sensing and controlling device.

An experimental system has been setup inside an argon atmosphere glove box to carry out studies on the actinide draw down process, an important step of the pyroprocess flow sheet. Studies have been carried out at 723 K on the extraction of uranium from LiCl-KCl eutectic salt containing 0.5% UCl 3 using lithium-0.03% cadmium alloy. In these experiments, 5 L of the molten salt and 5 L of the molten alloy are fed to a single stage extractor where 250 mL of the salt and 250 mL of the alloy come into contact. A three stage stirrer having straight as well as pitched blade turbine impellers was used to mix the molten alloy and salt phases having high interfacial tension of 450 dyne/cm. The results of the studies indicate that a U extraction efficiency of 99% could be achieved.

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