FCM Fuel Reactivity via TRISO Kernel and SiC Matrix
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Solution Overview
Problem
Fully ceramic micro-encapsulated (FCM) fuel assemblies for CANDU reactors face challenges in achieving reactivity characteristics comparable to standard reference fuels, particularly due to lower heavy metal and fissile mass content, which affects burnup rates and operational safety.
Innovation Solution
The use of TRISO particles compacted in a Silicon Carbide (SiC) matrix with a mixture of short- and long-acting burnable poisons, such as Gadolinium and Erbium, to regulate reactivity and extend burnup, while maintaining compatibility with standard reactor designs through a strong SiC matrix structure that prevents particle contact and enhances fission product retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TRISO particles are used to form FCM fuel, then fission product retention and safety are improved, but heavy metal mass and fissile mass are reduced
Solution Approach 1:
The patent increases the kernel diameter of TRISO particles from conventional sizes to 400-800 μm, and increases the packing fraction of TRISO particles in the fuel pellet. These parameter changes allow significantly more heavy metal and fissile mass to be contained within the FCM fuel pellet while maintaining the safety benefits of the TRISO particle structure.
2Quantity of substance
If kernel diameter of TRISO particles is increased to increase heavy metal mass, then fissile mass is improved, but particle density and packing efficiency may be affected
Solution Approach 1:
The patent specifies a kernel diameter range of 400-800 μm and a packing fraction range of 30-40%, optimizing these parameters to achieve adequate fissile mass while maintaining manufacturability and particle uniformity. This balanced approach resolves the contradiction between increasing fissile mass and maintaining manufacturing precision.
3Adaptability or versatility
If FCM fuel assemblies are designed to match conventional fuel dimensions, then reactor compatibility is improved, but heavy metal mass is limited
Solution Approach 1:
The patent increases the packing fraction of TRISO particles to 30-40% and uses larger kernel diameters (400-800 μm), which allows FCM fuel pellets to contain adequate heavy metal mass while maintaining the same external dimensions as conventional fuel pellets, thus ensuring reactor compatibility.
4Reliability
If burnable poisons are added to regulate reactivity, then reactivity control is improved, but manufacturing complexity increases
Solution Approach 1:
The patent incorporates burnable poisons directly into the SiC matrix material that surrounds the TRISO particles. This merging of the burnable poison function with the existing matrix structure simplifies the overall fuel fabrication process compared to adding separate poison components, while still achieving adequate reactivity control throughout the fuel cycle.
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 achieves comparable reactivity profiles and extended burnup rates, ensuring safer operations and reduced waste production, while maintaining compatibility with existing reactor systems.
Implementation Method 1
a strong SiC matrix structure that prevents particle contact and enhances fission product retention
Implementation Method 2
a mixture of short- and long-acting burnable poisons, such as Gadolinium and Erbium, to regulate reactivity and extend burnup
Implementation Method 3
Nuclear fuel undergoes fission to produce energy in a nuclear reactor
Data Source
AI summary
A fuel pellet for a nuclear reactor includes a plurality of tristructural-isotropic fuel particles embedded in a structural silicon carbide matrix. A method of manufacturing a fuel pellet includes the steps of coating a plurality of tristructural-isotropic fuel particles with a coating slurry including silicon carbide powder to form a plurality of coated fuel particles; compacting the plurality of fuel particles; and sintering the compacted plurality of fuel particles to form the fuel pellet.