Composite ATF Fuel Pellet With Double Oxidation Shielding
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Solution Overview
Problem
Current uranium dioxide (UO2) fuel pellets in nuclear reactors suffer from low thermal conductivity, leading to high temperature gradients, increased fission gas release, and mechanical-physical-chemical reactions, while high uranium density materials like carbides, nitrides, and silicides have poor oxidation resistance, risking pellet integrity in water-cooled reactors.
Innovation Solution
A high uranium density ATF nuclear fuel pellet with a double antioxidant shielding layer, comprising an inner zone of UO2, ThO2, or PuO2 mixed with UN, UC, or U3Si2, and a peripheral zone of UO2, PuO2, or UO2-ThO2 mixture, surrounded by a metal nitride isolation layer, preventing reaction with water and water vapor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high uranium density materials (carbides, nitrides, silicides) are used to reduce temperature gradients, then thermal conductivity is improved, but oxidation resistance deteriorates
Solution Approach 1:
The patent uses composite materials by combining high uranium density materials (UN, UC, or U3Si2) with oxidation-resistant materials (UO2, ThO2, or PuO2) in a mixed pellet structure. This composite approach allows the fuel to maintain high thermal conductivity from the carbide/nitride/silicide components while the oxide components provide oxidation resistance, resolving the contradiction between thermal performance and chemical stability.
Solution Approach 2:
The patent applies local quality by creating a mixed pellet where different regions contain different material compositions. The high uranium density materials are distributed within an oxidation-resistant matrix, allowing local optimization where thermal conductivity is enhanced in fuel-rich zones while oxidation resistance is maintained in oxide-rich zones, thereby resolving the temperature gradient versus oxidation resistance contradiction.
2Reliability
If conventional UO2 fuel is used to ensure oxidation resistance, then reliability is improved, but thermal conductivity deteriorates
Solution Approach 1:
The patent reverses the conventional approach by embedding high thermal conductivity materials (UN, UC, or U3Si2) within an oxidation-resistant UO2, ThO2, or PuO2 matrix. This composite structure maintains the oxidation resistance of conventional fuel while introducing materials with superior thermal conductivity properties, thereby resolving the contradiction between reliability and thermal performance.
3Productivity
If high uranium density materials are used to reduce fission gas release, then productivity is improved, but structural integrity deteriorates due to poor oxidation resistance
Solution Approach 1:
The patent uses composite materials where high uranium density materials (UN, UC, or U3Si2) are combined with oxidation-resistant oxides (UO2, ThO2, or PuO2). The oxide component forms a stable matrix that maintains pellet structural integrity and resists oxidation, while the carbide/nitride/silicide components provide high uranium density for improved burnup efficiency, resolving the contradiction between productivity and stability.
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
The double shielding layer enhances oxidation resistance and maintains pellet integrity, reducing temperature gradients and mechanical-physical-chemical reactions, making it suitable for water-cooled reactors with improved safety and performance.
Implementation Method 1
the isolation layer and the peripheral zone sequentially wrap the inner zone containing the high uranium density nuclear fuel and form a double antioxidant shielding layer
Implementation Method 2
the isolation layer and the peripheral zone sequentially wrap the inner zone containing the high uranium density nuclear fuel and form a double antioxidant shielding layer, which avoids the high uranium density nuclear fuel from reacting with the external water or water vapor
Data Source
Figure 1~2
AI summary
A high-uranium-density ATF nuclear fuel pellet and a preparation method therefor. The high-uranium-density ATF nuclear fuel pellet comprises a columnar inner region (10), an isolation layer (20) covering the outer surface of the inner region (10), and a peripheral region (30) covering the isolation layer (20), wherein the inner region (10) is prepared from a nuclear fuel that is resistant to the oxidation of water and water vapor, and a high-uranium-density nuclear fuel; the peripheral area (30) is prepared from a nuclear fuel that is resistant to the oxidation of water and water vapor; and the mass of the high-uranium-density nuclear fuel accounts for 3-50% of the total mass of the inner region (10) and the isolation layer (20). The high-uranium-density ATF nuclear fuel pellet has an increased uranium loading amount and an effectively reduced central temperature, thereby improving the economical efficiency and safety of the operation of a reactor; and the use of the high-uranium-density nuclear fuel in a water-cooled nuclear reactor is realized, and the accident-tolerant capability of the nuclear reactor is improved.