A purification method that uses ion-selective ceramics to electrochemically filter waste products from a molten salt. The electrochemical method uses ion-conducting ceramics that are selective for the molten salt cations desired in the final purified melt, and selective against any contaminant ions. The method can be integrated into a slightly modified version of the electrochemical framework currently used in pyroprocessing of nuclear wastes.

A process for chemical stabilization of a uranium carbide composite material: UC.sub.x+yC with x≧1 and y>0, placed in a stabilization chamber, comprises: a rise in chamber internal temperature for oxidation of the compound based on uranium carbide between approximately 380° C. and 550° C., the chamber being fed with a neutral gas; isothermal oxidative treatment at the oxidation temperature, the chamber being placed under O.sub.2 partial pressure; controlling completion of stabilization of the compound, comprising monitoring the amount of molecular oxygen consumed and/or carbon dioxide or carbon dioxide and carbon monoxide given off, until achievement of an input set-point value for the amount of molecular oxygen, of a minimum threshold value for the amount of carbon dioxide or minimum threshold values for the carbon dioxide and carbon monoxide. A device implements the process.

A process for chemical stabilization of a uranium carbide composite material: UC.sub.x+yC with x≧1 and y>0, placed in a stabilization chamber, comprises: a rise in chamber internal temperature for oxidation of the compound based on uranium carbide between approximately 380° C. and 550° C., the chamber being fed with a neutral gas; isothermal oxidative treatment at the oxidation temperature, the chamber being placed under O.sub.2 partial pressure; controlling completion of stabilization of the compound, comprising monitoring the amount of molecular oxygen consumed and/or carbon dioxide or carbon dioxide and carbon monoxide given off, until achievement of an input set-point value for the amount of molecular oxygen, of a minimum threshold value for the amount of carbon dioxide or minimum threshold values for the carbon dioxide and carbon monoxide. A device implements the process.

Proposed are a regenerating agent for a radionuclide adsorbent containing aqueous ammonia and organic acid, a regenerating method for a radionuclide adsorbent after using the regenerating agent for the radionuclide adsorbent, a method for treating of a spent regenerating agent obtained by the regenerating method of the spent radionuclide adsorbent, and a method of improving ion exchange capability of the regenerated radionuclide adsorbent obtained by the regenerating method of the spent radionuclide adsorbent.

The invention relates to an encapsulation composition for the storage or the confinement of waste which is toxic to health and/or the environment, comprising a resin composition containing at least one epoxy resin, and a hardening composition containing at least one polyamidoamine and at least one aromatic polyamine, said encapsulation composition having an aromaticity rate which is equal to, or higher than, 35%. The invention also relates to the use of said composition for encapsulating said waste.

Steel and/or copper spherical capsules are specifically engineered and manufactured for housing uranium waste products. The uranium waste products are placed within the spherical capsules. Human-made cavern(s) and/or substantially lateral wellbore(s) are constructed for receiving the uranium waste containing spherical capsules. The human-made cavern(s) and/or the substantially lateral wellbore(s) are deeply located in specific types of geologic rock formations thousands of feet below the Earth's surface. These uranium waste containing spherical capsules are loaded from the Earth's surface into the human-made cavern(s) and/or into the substantially lateral wellbore(s). The emplaced spherical capsules are surrounded by an immersive protective medium within the given human-made cavern(s) and/or within the substantially lateral wellbore(s). The given human-made cavern(s) and/or the given substantially lateral wellbore(s), with the uranium waste containing spherical capsules, are sealed off.

The present invention relates to a constructing method for delaying corrosion of radioactive waste disposal container in concrete disposal vault and, more specifically, to a constructing method for delaying corrosion of radioactive waste disposal container in concrete disposal vault in which backfill, placed to the top, combines pH control capsules, thereby dissolving the pH control capsules in rainwater, and a pH controller, inside, is discharged, thereby preventing decrease of pH of the backfill below 8.5 and delaying corrosion in the disposal containers, upon filling in backfill after placing radioactive waste disposal containers in the concrete vault.

This invention generally concerns radioactive decontamination of deposits on components in a nuclear power plant and is specifically concerned with improved compositions, systems and methods for disrupting, dissolving, removing and reducing at ambient temperature radionuclides formed on the primary side surfaces of components in a pressurized water reactor and the internal components of a boiling water reactor. The methods include identifying the structure, taking the structure out of operational service, contacting the structure with an aqueous solution (e.g., a recirculating flow or static immersion), and adding an effective amount of elemental metal in solid form to the aqueous solution.

This invention generally concerns radioactive decontamination of deposits on components in a nuclear power plant and is specifically concerned with improved compositions, systems and methods for disrupting, dissolving, removing and reducing at ambient temperature radionuclides formed on the primary side surfaces of components in a pressurized water reactor and the internal components of a boiling water reactor. The methods include identifying the structure, taking the structure out of operational service, contacting the structure with an aqueous solution (e.g., a recirculating flow or static immersion), and adding an effective amount of elemental metal in solid form to the aqueous solution.

A method of follow-up decontamination operation for the polluted storage canister of a high activity nuclear waste storage facility, using needle and steel brushes driven by pneumatic tools for abrading the bottom and the inner wall of the storage canister to remove contaminants, a multi-level filter system for air filtration and removing pollutants in the storage canister, and a cover to be used in association with the pneumatic tools and the multi-level filtration system suitable to cap the storage canister, thus effectively block the exposure of contaminant of the storage canister to the external environment, achieving effective decontamination of the radioactive waste and reducing spreading to the environment.