Experimental set up for studying temperature gradient driven cracking
Inventors
Knight, Travis • Patnaik, Sobhan • Besmann, Theodore • Roberts, Elwyn
Assignees
Publication Number
US-12288320-B2
Publication Date
2025-04-29
Expiration Date
2041-10-21
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Abstract
Described herein are systems and methods for imaging the top surface of a fuel pellet to observe the formation of radial cracks employing resistive heating to volumetrically heat the fuel pellet, but instead of passing the current axially through the pellet, electrodes were placed on the sides of a single pellet to pass the current transversely across the pellet allowing for an unobstructed view of the top surface of the pellet.
Core Innovation
The invention provides systems and methods for capturing fracture initiation and growth in fuel pellets by utilizing dual heating (inductive heating followed by direct resistance heating) and a dual imaging technique. This setup employs electrodes on at least two sides of the fuel pellet to pass electric current transversely, enabling volumetric heating and allowing unobstructed real-time imaging of crack formation on the pellet’s top surface.
The dual imaging system comprises an infrared camera for capturing the temperature gradient and an optical camera for monitoring physical crack evolution. The technology allows simultaneous, in situ measurement of both thermal profile and crack propagation. This approach enables the generation of temperature profiles via infrared thermal radiation, and the system can also use fractography to analyze the shape of cracks.
The problem addressed by the invention is the lack of experimental data for direct validation of fuel fracture models, as it is difficult to replicate the thermal conditions of reactor fuel and observe crack growth without obstructing the representative environment. Traditional experiments could not provide simultaneous, real-time, unobstructed imaging of fracture initiation and temperature distribution in single pellets. The disclosed setup overcomes these challenges by providing representative reactor-like thermal conditions and direct, simultaneous, real-time observation of crack initiation and propagation.
Claims Coverage
The patent contains one independent claim with multiple dependent claims, introducing several inventive features.
Capturing fracture initiation and growth in fuel pellets via transverse current and dual heating
A method combining inductive heating to raise the temperature of at least one fuel pellet, followed by direct resistance heating with electrodes placed on at least two sides of the pellet to pass electric current transversely across the pellet. This configuration allows imaging of the pellet surface to observe crack formation intersecting the surface, enabling the capture of both fracture initiation and growth. The method concludes by generating at least one temperature profile for the at least one fuel pellet, via receiving and measuring infrared thermal radiation generated by the heating steps. Key steps: 1. Employ inductive heating to increase the pellet temperature. 2. Apply direct resistance heating transversely using side electrodes. 3. Image the pellet surface to observe crack formation. 4. Generate temperature profiles based on measured infrared thermal radiation.
The claims are directed toward a method for observing fracture initiation and growth in fuel pellets by dual-mode heating, transverse current application, and simultaneous imaging and temperature profiling, addressing real-time characterization of cracking under laboratory-simulated conditions.
Stated Advantages
Provides simultaneous, real-time imaging of fuel pellet cracks and measurement of temperature profiles, enabling direct, in situ observation of fracture initiation and growth.
Enables collection of multiple data sets under the same conditions, improving efficiency, accuracy, and quality control by recording all data in situ without loss.
Permits more extensive instrumentation than possible in a reactor experiment, allowing accurate characterization of thermal and mechanical behaviors relevant to reactor fuel performance.
Supplies experimental data critical for validating and improving fuel fracture models in fuel performance simulation codes.
Applies to a wide range of materials, enabling measurement and study of both conductive and insulating pellets under representative thermal conditions.
Uses a dual imaging technique combining infrared and optical cameras to capture both temperature gradients and physical images of cracks simultaneously.
Documented Applications
Studying temperature-gradient-driven cracking in uranium dioxide (UO2) pellets to validate and improve fuel fracture models in reactor fuel performance codes.
Collecting experimental data for validating 2-D and 3-D cracking models used in BISON and similar fuel performance codes.
Characterizing the thermal and mechanical behavior of LWR fuel pellets during normal operations and accident scenarios, such as reactivity-initiated accidents.
Studying cracking and temperature-dependent mechanical properties of other ceramics and metals compatible with the system’s instrumentation.
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