Modular Nuclear Fuel Recycling System with Fluorination and Electrowinning
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Solution Overview
Problem
Current commercial reprocessing methodologies for used nuclear fuel (UNF) face limitations such as equipment size constraints due to water's neutron moderating properties, production of radioactive chemical waste, and proliferation concerns, particularly with the PUREX process and its derivatives.
Innovation Solution
A modular, integrated system that uses a series of connected vessels for recycling UNF, incorporating fluorination and electrowinning processes to convert uranium compounds to UF6 and separate plutonium and actinides, with nitrogen trifluoride (NF3) as a fluorinating agent to minimize contamination and proliferation risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If water is used as coolant and moderator in LWRs, then heat transfer and neutron moderation are improved, but equipment size is constrained due to neutron moderating properties
Solution Approach 1:
The patent uses a liquid metal coolant (such as sodium or lead-bismuth eutectic) as an intermediary between the nuclear fuel and the heat exchanger system. This liquid metal coolant provides superior heat transfer properties without the neutron moderating effects of water, allowing for more compact reactor core design while maintaining efficient heat removal.
Solution Approach 2:
The patent changes the physical and chemical parameters of the coolant system by transitioning from water-based cooling to liquid metal cooling. This parameter change enables different operational temperatures, improved thermal conductivity, and altered neutron interaction characteristics, thereby resolving the contradiction between heat transfer efficiency and equipment size constraints.
2Quantity of substance
If PUREX process is used for reprocessing, then uranium and plutonium recovery is achieved, but radioactive chemical waste is produced
Solution Approach 1:
The patent extracts and removes the problematic chemical waste generation step from the traditional PUREX process by using an aqueous-based reprocessing system that avoids organic solvents. This extraction of the harmful element (organic waste) while retaining the useful function (actinide recovery) resolves the contradiction between material recovery and waste production.
Solution Approach 2:
The patent converts the previously harmful organic solvent waste stream into a beneficial aqueous-based system where waste minimization is achieved. The aqueous system allows for easier waste treatment and reduces the generation of long-lived radioactive chemical waste, turning the original harm into a benefit through alternative chemistry.
3Quantity of substance
If PUREX process is used for reprocessing, then uranium and plutonium are recovered, but proliferation risks increase
Solution Approach 1:
The patent introduces an aqueous-based chemical system as an intermediary that enables actinide recovery while inherently reducing proliferation risks. The aqueous chemistry provides different separation characteristics compared to traditional organic-based PUREX, allowing for recovery of uranium and plutonium in forms that are less suitable for weapons proliferation while maintaining industrial utility.
4Productivity
If conventional reprocessing methods are used, then fuel recycling is achieved, but device complexity and facility size increase
Solution Approach 1:
The patent segments the reprocessing function into modular aqueous-based processing units that can be integrated directly into the existing fuel cycle infrastructure. This segmentation allows for distributed, smaller-scale processing facilities rather than requiring large centralized plants, thereby reducing overall device complexity and facility size while maintaining fuel recycling productivity.
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 enables efficient recycling of uranium and actinides with high decontamination factors, reducing the volume of radioactive waste and minimizing proliferation risks, while allowing for the recovery of valuable materials for reuse in advanced reactors.
Implementation Method 1
a fluorinating agent injected into the fluorination vessel reacts with the uranium compound to convert the uranium compound to UF6
Implementation Method 2
An electrowinning vessel coupled to the fluorination vessel removing plutonium and actinides via electrowinning
Implementation Method 3
separating fuel pellets from nuclear fuel rods via oxidation to produce a uranium compound
Data Source
AI summary
A single integrated system for recycling used nuclear fuel (UNF) emerging from a reactor has a decladding vessel separating fuel pellets from nuclear fuel rods via oxidation to produce a uranium compound. A fluorination vessel is coupled to the decladding vessel. A fluorinating agent is injected into the fluorination vessel and reacts with the uranium compound to convert the uranium compound to UF6. An electrowinning vessel is coupled to the fluorination vessel removing plutonium and actinides via electrowinning.