Uranium Dioxide Solid Solution Powder via Single-Step Combustion

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Solution Overview

Problem

Current methods for preparing mixed oxides of uranium and other actinide/lanthanide elements require multiple steps, including precipitation and calcination, making it difficult to achieve a single-step process for forming solid solutions with varying proportions of uranium and other elements.

Innovation Solution

A method involving the combustion of a solution containing uranyl nitrate and another actinide/lanthanide nitrate with an over-stoichiometric amount of nitrogen-containing fuel, determined by specific combustion equations, to form a solid solution of uranium dioxide and another actinide/lanthanide element in a single step.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If co-conversion methods (precipitation-calcination) are used to prepare mixed oxides, then homogeneous distribution of elements is achieved, but multiple steps (precipitation, separation, calcination) are required

Engineering Contradiction:

Improvehomogeneity of element distributionVSAvoidnumber of process steps

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent combines the precipitation and calcination steps into a single combustion process. The nitrate solution containing uranyl and actinide/lanthanide ions is directly combusted with a fuel to form the mixed oxide powder in one operation, eliminating the need for separate precipitation, filtration, and calcination steps while maintaining homogeneous element distribution.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent performs preliminary mixing of the nitrate solutions containing uranyl and actinide/lanthanide ions before combustion. This ensures homogeneous distribution of elements in the solution phase, which is then preserved in the final mixed oxide powder through the combustion process, achieving the desired homogeneity without subsequent processing steps.

Inventive Principle:

Principle #10Preliminary action

2Ease of manufacture

If mechanical mixing of simple oxide powders is used for MOX fuels, then protective steps against proliferation are reduced, but homogeneous mixture of elements is difficult to obtain

Engineering Contradiction:

Improvesafety against proliferationVSAvoidhomogeneity of element distribution

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent performs preliminary mixing of the nitrate solutions containing uranyl and actinide/lanthanide ions at the molecular level before combustion. This ensures homogeneous distribution of elements in the solution phase, which is then preserved in the final mixed oxide powder through the combustion process, achieving the desired homogeneity without subsequent processing steps.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces the mechanical mixing of solid oxide powders with a chemical combustion process. Instead of mechanically mixing UO2 and PuO2 powders, the method uses combustion of a nitrate solution to directly form the mixed oxide powder, eliminating the need for reinforced protective steps while achieving homogeneous element distribution.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If solution combustion is used to prepare mixed oxides, then a single step process is achieved, but solid solution formation is not guaranteed for varying proportions

Engineering Contradiction:

Improvesingle step process efficiencyVSAvoidsolid solution formation

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent optimizes the combustion parameters, including the type and amount of fuel, combustion temperature, and atmosphere, to ensure solid solution formation for varying proportions of uranyl and actinide/lanthanide elements. By controlling these parameters, the method achieves both single-step processing and reliable solid solution formation across different compositions.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent adjusts the local composition and combustion conditions to accommodate varying proportions of elements. By optimizing the fuel-to-nitrate ratio and combustion parameters for specific composition ranges, the method ensures solid solution formation regardless of the initial element proportions in the nitrate solution.

Inventive Principle:

Principle #3Local quality

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 method allows for the efficient production of solid solution powders of uranium dioxide and other actinide/lanthanide elements in a single step, overcoming the complexity of multi-step processes and achieving homogeneity suitable for nuclear fuel applications.

Implementation Method 1

combustion of a solution containing uranyl nitrate and another actinide/lanthanide nitrate with an over-stoichiometric amount of nitrogen-containing fuel

Methodology Applied

Scientific EffectCombustion: Combustion

Data Source

PatentUS10005676B2Process for preparing a powder comprising a solid solution of uranium dioxide and of a dioxide of at least one other actinide and/or lanthanide element

Publication Date: 2018.06.26 ORANO RECYCLAGE

AI summary

A method for preparing a powder of a solid solution of dioxide of uranium and of at least one other actinide and/or lanthanide element comprising combusting a solution that comprises uranyl nitrate and at least one nitrate of the other actinide and/or lanthanide element and glycine, with the glycine being used in a predetermined amount so as to form, at the end of the combustion, the solid solution.