The United States of America as Represented by the United States

The United States of America as Represented by the Department of Energy

The United States of America as Represented by the United States Energy

The University of Chicago

Zygmunt Tomczuk

William E Miller

Donald R Vissers

Eddie C Gay

Thomas D Kaun

Paul A Nelson

Robert K Steunenberg

James L Willit

John P Ackerman

James E Battles

Terry R Johnson

Michael F Roche

Gerald K Johnson

Allan E Martin

Theodore W Olszanski

Raymond D Wolson

David S Poa

Leslie Burris

Michael K Richmann

Karl E Anderson

Donald F Fischer

A method of producing metal chlorides is disclosed in which chlorine gas is introduced into liquid Cd. CdClsalt is floating on the liquid Cd and as more liquid CdClis formed it separates from the liquid Cd metal and dissolves in the salt. The salt with the CdCldissolved therein contacts a metal which reacts with CdClto form a metal chloride, forming a mixture of metal chloride and CdCl. After separation of bulk Cd from the salt, by gravitational means, the metal chloride is obtained by distillation which removes CdCland any Cd dissolved in the metal chloride.

Apparatus and method for making metal chloride salt product

A improved device and process for recycling spent nuclear fuels, in particular uranium metal, that facilitates the refinement and recovery of uranium metal from spent metallic nuclear fuels. The electrorefiner device comprises two anodes in predetermined spatial relation to a cathode. The anodese have separate current and voltage controls. A much higher voltage than normal for the electrorefining process is applied to the second anode, thereby facilitating oxidization of uranium (III), U, to uranium (IV), U. The current path from the second anode to the cathode is physically shorter than the similar current path from the second anode to the spent nuclear fuel contained in a first anode shaped as a basket. The resulting Uoxidizes and solubilizes rough uranium deposited on the surface of the cathode. A softer uranium metal surface is left on the cathode and is more readily removed by a scraper.

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The subject apparatus provides a means to produce UCl in large quantities without incurring corrosion of the containment vessel or associated apparatus. Gaseous Cl is injected into a lower layer of Cd where CdCl is formed. Due to is lower density, the CdCl rises through the Cd layer into a layer of molten LiCl&mdash;KCL salt where a rotatable basket containing uranium ingots is suspended. The CdCl reacts with the uranium to form UCl and Cd. Due to density differences, the Cd sinks down to the liquid Cd layer and is reused. The UCl combines with the molten salt. During production the temperature is maintained at about 600&deg; C. while after the uranium has been depleted the salt temperature is lowered, the molten salt is pressure siphoned from the vessel, and the salt product LiCl&mdash;KCl-30 mol % UCl is solidified.

Method for making a uranium chloride salt product

This is a pyroprocess for processing spent nuclear fuel. The spent nuclear fuel is chopped into pieces and placed in a basket which is lowered in to a liquid salt solution. The salt is rich in ZrF and containing alkali or alkaline earth fluorides, and in particular, the salt chosen was LiF-50 mol % ZrF with a eutectic melting point of 500&deg; C. Prior to lowering the basket, the salt is heated to a temperature of between 550&deg; C. and 700&deg; C. in order to obtain a molten solution. After dissolution the oxides of U, Th, rare earth and other like oxides, the salt bath solution is subject to hydro-fluorination to remove the oxygen and then to a fluorination step to remove U as gaseous UF . In addition, after dissolution, the basket contains PuO and undissolved parts of the fuel rods, and the basket and its contents are processed to remove the Pu.

Pyroprocess for processing spent nuclear fuel

Purified plutonium and gallium are efficiently recovered from a solid plutonium-gallium (Pu&mdash;Ga) alloy by using an electrorefining process. The solid Pu&mdash;Ga alloy is the cell anode, preferably placed in a moving basket within the electrolyte. As the surface of the Pu&mdash;Ga anode is depleted in plutonium by the electrotransport of the plutonium to a cathode, the temperature of the electrolyte is sufficient to liquify the surface, preferably at about 500&deg; C., resulting in a liquid anode layer substantially comprised of gallium. The gallium drips from the liquified surface and is collected below the anode within the electrochemical cell. The transported plutonium is collected on the cathode surface and is recovered.

Method for plutonium-gallium separation by anodic dissolution of a solid plutonium-gallium alloy

A method of removing Li.sub.2 O present in an electrolyte predominantly of LiCl and KCl. The electrolyte is heated to a temperature not less than about 500.degree. C. and then Al is introduced into the electrolyte in an amount in excess of the stoichiometric amount needed to convert the Li.sub.2 O to a Li-Al alloy and lithium aluminate salt. The salt and aluminum are maintained in contact with agitation for a time sufficient to convert the Li.sub.2 O.

Method for treating electrolyte to remove Li.sub.2 O

A combination anode and cathode for an electrorefiner which includes a hollow cathode and an anode positioned inside the hollow cathode such that a portion of the anode is near the cathode. A retaining member is positioned at the bottom of the cathode. Mechanism is included for providing relative movement between the anode and the cathode during deposition of metal on the inside surface of the cathode during operation of the electrorefiner to refine spent nuclear fuel. A method is also disclosed which includes electrical power means selectively connectable to the anode and the hollow cathode for providing electrical power to the cell components, electrically transferring uranium values and plutonium values from the anode to the electrolyte, and electrolytically depositing substantially pure uranium on the hollow cathode. Uranium and plutonium are deposited at a liquid cathode together after the PuCl.sub.3 to UCl.sub.3 ratio is greater than 2:1. Slots in the hollow cathode provides close anode access for the liquid pool in the liquid cathode.

Advanced electrorefiner design

An apparatus capable of functioning as a solid cathode and for removing crystalline structure from the upper surface of a liquid cathode, includes a metallic support vertically disposed with respect to an electrically insulating container capable of holding a liquid metal cathode. A piston of electrically insulating material mounted on the drive tube, surrounding the current lead, for vertical and rotational movement with respect thereto including a downwardly extending collar portion surrounding the metallic current lead. At least one portion of the piston remote from the metallic current lead being removed. Mechanism for lowering the piston to the surface of the liquid cathode and raising the piston from the surface along with mechanism for rotating the piston around its longitudinal axis.

Electrorefiner

A process for converting PuO.sub.2 and UO.sub.2 present in an electrorefiner to the chlorides, by contacting the PuO.sub.2 and UO.sub.2 with Li metal in the presence of an alkali metal chloride salt substantially free of rare earth and actinide chlorides for a time and at a temperature sufficient to convert the UO.sub.2 and PuO.sub.2 to metals while converting Li metal to Li.sub.2 O. Li.sub.2 O is removed either by reducing with rare earth metals or by providing an oxygen electrode for transporting O.sub.2 out of the electrorefiner and a cathode, and thereafter applying an emf to the electrorefiner electrodes sufficient to cause the Li.sub.2 O to disassociate to O.sub.2 and Li metal but insufficient to decompose the alkali metal chloride salt. The U and Pu and excess lithium are then converted to chlorides by reaction with CdCl.sub.2.

Recovery of UO.sub.2 /Pu O.sub.2 in IFR electrorefining process

A new electrolytic process and apparatus are provided using sodium, cerium or a similar metal in alloy or within a sodium beta or beta'-alumina sodium ion conductor to electrolytically displace each of the spent fuel metals except for cesium and strontium on a selective basis from the electrolyte to an inert metal cathode. Each of the metals can be deposited separately. An electrolytic transfer of spent fuel into the electrolyte includes a sodium or cerium salt in the electrolyte with sodium or cerium alloy being deposited on the cathode during the transfer of the metals from the spent fuel. The cathode with the deposit of sodium or cerium alloy is then chanted to an anode and the reverse transfer is carried out on a selective basis with each metal being deposited separately at the cathode. The result is that the sodium or cerium needed for the process is regenerated in the first step and no additional source of these reactants is required.

Electrolytic recovery of reactor metal fuel

An electrochemical process and electrochemical cell for reducing a metal oxide are provided. First the oxide is separated as oxygen gas using, for example, a ZrO.sub.2 oxygen ion conductor anode and the metal ions from the reduction salt are reduced and deposited on an ion conductor cathode, for example, sodium ion reduced on a .beta.-alumina sodium ion conductor cathode. The generation of and separation of oxygen gas avoids the problem with chemical back reaction of oxygen with active metals in the cell. The method also is characterized by a sequence of two steps where an inert cathode electrode is inserted into the electrochemical cell in the second step and the metallic component in the ion conductor is then used as the anode to cause electrochemical reduction of the metal ions formed in the first step from the metal oxide where oxygen gas formed at the anode. The use of ion conductors serves to isolate the active components from chemically reacting with certain chemicals in the cell. While applicable to a variety of metal oxides, the invention has special importance for reducing CaO to Ca.degree. used for reducing UO.sub.2 and PuO.sub.2 to U and Pu.

Use of ion conductors in the pyrochemical reduction of oxides

An electrochemical process and apparatus for the recovery of uranium and plutonium from spent metal clad fuel pins is disclosed. The process uses secondary reactions between U.sup.+4 cations and elemental uranium at the anode to increase reaction rates and improve anodic efficiency compared to prior art processes. In another embodiment of the process, secondary reactions between Cd.sup.+2 cations and elemental uranium to form uranium cations and elemental cadmium also assists in oxidizing the uranium at the anode.

Process and apparatus for recovery of fissionable materials from spent

An apparatus and process for reducing uranium and/or plutonium oxides to produce a solid, high-purity metal. The apparatus is an electrolyte cell consisting of a first container, and a smaller second container within the first container. An electrolyte fills both containers, the level of the electrolyte in the first container being above the top of the second container so that the electrolyte can be circulated between the containers. The anode is positioned in the first container while the cathode is located in the second container. Means are provided for passing an inert gas into the electrolyte near the lower end of the anode to sparge the electrolyte and to remove gases which form on the anode during the reduction operation. Means are also provided for mixing and stirring the electrolyte in the first container to solubilize the metal oxide in the electrolyte and to transport the electrolyte containing dissolved oxide into contact with the cathode in the second container. The cell is operated at a temperature below the melting temperature of the metal product so that the metal forms as a solid on the cathode.

Apparatus and process for the electrolytic reduction of uranium and

A process for removing transuranic elements from a waste chloride electrolytic salt containing transuranic elements in addition to rare earth and other fission product elements so the salt waste may be disposed of more easily and the valuable transuranic elements may be recovered for reuse. The salt is contacted with a cadmium-uranium alloy which selectively extracts the transuranic elements from the salt. The waste salt is generated during the reprocessing of nuclear fuel associated with the Integral Fast Reactor (IFR).

Process to separate transuranic elements from nuclear waste

A method of preparing an electrochemical cell including a metal sulfide as the positive electrode reactant and lithium alloy as the negative electrochemical reactant with an alkali metal, molten salt electrolyte is disclosed which permits the assembly to be accomplished in air. The electrode reactants are introduced in the most part as a sulfide of lithium and the positive electrode metal in a single-phase compound. For instance, Li.sub.2 FeS.sub.2 is a single-phase compound that is produced by the reaction of Li.sub.2 S and FeS. This compound is an intermediate in the positive electrode cycle from FeS.sub.2 to Fe and Li.sub.2 S. Its use minimizes volumetric changes from the assembled to the charged and discharged conditions of the electrode and minimizes electrode material interaction with air and moisture during assembly.

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Lockport, IL, United States of America

Zygmunt Tomczuk