PEER Electrorefiner Solid Cathode Codeposition
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Solution Overview
Problem
Existing electrorefining processes, such as the Mk-V high throughput electrorefiner, face inefficiencies in scraping off cathode deposits and require extensive hot cell operations to recover uranium products, whereas the Planar Electrode ElectroRefiner (PEER) design addresses these issues with a solid cathode and optimized anode-to-cathode area ratios for codeposition of uranium and transuranics, enhancing separation and proliferation resistance.
Innovation Solution
The PEER design employs multiple planar anode baskets with interleaved linear cathode arrays to achieve a high anode-to-cathode surface area ratio, allowing for codeposition of uranium and transuranics on a solid cathode, enabling efficient removal and separation, and preventing anode basket oxidation through controlled current densities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the entire electrorefiner unit is removed for product recovery in the Mk-V design, then the product can be collected, but the process takes up to 12 hours in a hot cell and the unit cannot operate during this time
Solution Approach 1:
The electrorefiner is divided into separate functional modules: the electrorefining cell and the product collection basket are independent components. The basket can be detached from the cell, allowing the cell to remain in place and continue operation while the basket is removed for product recovery in a hot cell. This segmentation enables parallel operations where product collection does not interrupt the electrorefining process.
Solution Approach 2:
The product collection basket is extracted as a separate removable component from the electrorefiner cell. This allows the basket containing the cathode deposit to be taken out for product recovery while the cell remains operational. The extraction of the collection function from the refining function eliminates the need to shut down the entire unit for product recovery.
2Quantity of substance
If a liquid cadmium cathode is used for codeposition of U and TRUs, then codeposition can be achieved, but the engineering challenges of operating a liquid metal cathode and inability to achieve complete separation from rare earths persist
Solution Approach 1:
The cathode material is changed from liquid cadmium to solid metal (such as stainless steel or other suitable solids). This parameter change fundamentally alters the operating characteristics: the solid cathode eliminates the engineering challenges of containing and controlling liquid metal, while still enabling codeposition of uranium and transuranics through controlled electrochemical reduction at appropriate potentials.
3Quantity of substance
If the anode area greatly exceeds the cathode area to achieve high current density for codeposition, then U and TRUs can codeposit on solid cathode, but the anode-to-cathode area ratio must be precisely controlled
Solution Approach 1:
The electrorefiner is designed with adjustable cathode positioning mechanisms that allow the cathode area to be dynamically adjusted relative to the anode. This enables optimization of the anode-to-cathode area ratio during operation to achieve the desired high current density for codeposition, while providing flexibility to adapt to different operating conditions and fuel types without requiring precise fixed dimensions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in nearly 100% refinement efficiency, improved separation of transuranics from rare earths, and a strong nuclear proliferation-resistance aspect by ensuring uranium is always present with transuranics, eliminating the use of liquid cadmium and reducing hot cell handling time significantly.
Implementation Method 1
the actinides, TRU's and active metal fission products are oxidized at the anode and dissolve in the molten salt electrolyte as metal cations
Implementation Method 2
electrorefining as a compact process for recovery of uranium from spent metallic reactor fuel
Implementation Method 3
uranium and transuranics will codeposit on the cathode
Implementation Method 4
Under normal operating conditions, only uranium is deposited on the cathode
Data Source
AI summary
The present invention provides a method of simultaneously removing uranium and transuranics from metallic nuclear fuel in an electrorefiner. In the method, a potential difference is established between an anode basket containing the fuel and a solid cathode of the electrorefiner, thereby creating a diffusion layer of uranium and transuranic ions at the solid cathode, a first current density at the anode basket, and a second current density at the solid cathode. The ratio of anode basket area to solid cathode area is selected based on the total concentration of uranium and transuranic metals in a molten halide electrolyte in the electrorefiner and the effective thickness of the diffusion layer at the solid cathode, such that the established first and second current densities result in both codeposition of uranium and transuranic metals on the solid cathode and oxidation of the metallic nuclear fuel in the anode basket.