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2026 Nuclear Energy Conference & Expo (NECX)
August 24–27, 2026
Dallas, TX|Hilton Anatole
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August 2026
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Copper melting behavior at extreme temperatures could inform fusion materials
Using SLAC’s electron camera, researchers recorded timestamps of solid copper atoms (orange) as they melted (yellow) after being blasted with laser heat. This graphic shows how copper atoms changed over a period of several femtoseconds (millionths of a billionth of a second), notated here as fractions of a picosecond. Instead of the predicted collapse, the researchers saw a gradual melting. (Image: Greg Stewart/SLAC National Accelerator Laboratory)
The SLAC National Accelerator Laboratory has announced researchers have conducted experiments testing how copper melts under extreme conditions, such as those it might be exposed to in a fusion machine. The results, published in Nature Communications, found that a copper thin film was more resilient to melting than models had predicted, uncovering molecular dynamics that had been missing from calculations.
“These results greatly improve the simulations we use to predict which materials have the best shot at surviving the extreme conditions of future fusion reaction chambers,” said Mianzhen Mo, the SLAC staff scientist who led the research.
Anthony G. Bowers, Jr., Subash L. Sharma, Thomas F. Fuerst
Fusion Science and Technology | Volume 82 | Number 1 | January-February 2026 | Pages 431-448
Research Article | doi.org/10.1080/15361055.2025.2549608
Articles are hosted by Taylor and Francis Online.
Tritium, a radionuclide produced through neutron capture by lithium and other elements (beryllium and fluoride) in molten salts, presents unique challenges to radionuclide release. This is true for both fusion energy breeder blankets and molten salt fission reactors. The fundamental understanding of tritium transport is crucial to the safe design and operation of these reactors.
The Molten Salt Tritium Transport Experiment (MSTTE), currently under construction at Idaho National Laboratory, aims to investigate tritium transport phenomena using a forced-convection fluoride salt loop. This loop is designed to study various transport mechanisms, such as permeation through metals and gas-liquid interactions, and is intended to support future research on tritium extraction units.
A critical aspect of the MSTTE loop design is ensuring a fully developed velocity profile before the fluid reaches the permeation test section where measurements are made. This study employs computational fluid dynamics to model the salt flow behavior within the MSTTE permeation test section. A realizable k-ε turbulent model with enhanced wall treatment is used to simulate the single-phase, vertical upward flow of molten salt FLiNaK under isothermal conditions.
The simulation results indicated flow distortion and underdeveloped profiles at all planned flow rates within the test section due to the 85-deg sharp bend. To address this issue, a reduced diameter with a reducer and expander and a flow conditioner are investigated to achieve fully developed flow. The analysis showed that the flow conditioner successfully corrected the flow profile, achieving fully developed behavior at a flow rate of 50 liters per minute (LPM). This research enhances our understanding of flow dynamics in molten salt systems and contributes to optimizing tritium transport control technologies.