Fuel Element Thermo-Mechanical Modeling for Breed-and-Burn Reactors
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Solution Overview
Problem
Breed-and-burn reactors face challenges with fuel element distortion and dimensional changes due to irradiation creep and swelling, which can prevent fuel shuffling and are design limiting, especially at high temperatures.
Innovation Solution
A computerized system and method for modeling reactor fuel pin and fuel design to determine thermo-mechanical performance, estimating mechanical behavior and creep/swelling behavior of fuel elements with open and closed porosity components, and combining these estimates to predict cladding behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high burn-up fuel cycle is used to reach equilibrium in breed-and-burn reactors, then fuel utilization efficiency is improved, but fuel element distortion and dimensional changes increase due to irradiation creep and swelling
Solution Approach 1:
The patent applies preliminary action by performing comprehensive thermo-mechanical performance modeling and analysis before fuel element fabrication and operation. The model predicts irradiation creep and swelling behavior under high burn-up conditions, allowing design optimization to prevent distortion before it occurs during actual reactor operation.
Solution Approach 2:
The patent segments the fuel element into distinct components (fuel pellets, cladding, end caps) and models the thermo-mechanical behavior of each segment separately. This allows for component-specific analysis of irradiation effects, enabling targeted design modifications to maintain overall fuel element integrity under high burn-up conditions.
2Duration of action of moving object
If high burn-up fuel cycle is used, then equilibrium is reached faster, but dimensional changes of fuel elements increase preventing fuel shuffling
Solution Approach 1:
The modeling system performs preliminary prediction of dimensional changes under high burn-up conditions, enabling design adjustments before operation. This allows the fuel element design to accommodate expected swelling and creep, maintaining dimensional stability throughout the extended operational period required to reach equilibrium.
Solution Approach 2:
The patent employs parameter changes by adjusting cladding thickness, material composition, and geometric dimensions based on predicted irradiation behavior. These design parameter modifications compensate for expected dimensional changes during high burn-up operation, ensuring fuel elements remain within acceptable tolerance limits for shuffling operations.
3Power
If fuel elements operate at high temperatures for extended periods, then energy production is improved, but thermal creep becomes design limiting
Solution Approach 1:
The patent applies composite materials by selecting and modeling advanced cladding materials with enhanced high-temperature creep resistance. The thermo-mechanical model evaluates the performance of composite material systems, allowing optimization of the fuel-cladding interface and selection of materials that maintain strength and dimensional stability under prolonged high-temperature operation.
Solution Approach 2:
The modeling system performs preliminary assessment of thermal creep behavior under various operating conditions, enabling selection of appropriate materials and design parameters before fabrication. This predictive approach ensures the fuel element design can sustain high power operation without thermal creep becoming the limiting factor.
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
Accurately predicts the thermo-mechanical performance of fuel elements, helping to set design values and prevent distortion, thereby ensuring stable fuel shuffling and extended operational life.
Implementation Method 1
estimate the mechanical behavior of a fuel with open porosity and closed porosity components by (a) creating separate variables for the open porosity and the closed porosity components of the fuel, (b) conducting a routine for both the open porosity and the closed porosity components that processes the current state of the fuel and updates the current state and forces of each of the open porosity and the closed porosity components
Implementation Method 2
estimate the creep and swelling behavior of a cladding
Implementation Method 3
estimate the creep and swelling behavior of a cladding
Data Source
AI summary
A computerized system for modeling reactor fuel element and fuel design to determine the thermo-mechanical performance thereof includes a processor coupled to memory, the memory configuring the processor to execute a fuel element analysis and an output configured to communicate data that describes the thermo-mechanical performance of the fuel element and fuel design based on the fuel element performance analysis. The processor is configured to estimate the mechanical behavior of a fuel by creating separate variables for the open and closed porosity components, conducting a routine for the open and closed porosity components that processes the current state of the fuel and updates the current state and forces of each of the open and closed porosity components, and combining the updates for the current state and forces according to a weighting; and estimate the creep and swelling behavior of a cladding.