Nuclear fuel shaped like butterfly wings could triple heat efficiency

Scientists at Idaho National Laboratory have borrowed a design trick from nature: the intricate lattice patterns found in butterfly wings, sea urchin shells, and bone marrow. They're now using these structures to reimagine how nuclear fuel works.

The catch is that these patterns — called triply periodic minimal surfaces, or TPMS — are mathematically perfect at doing one thing: moving heat around efficiently. When researchers applied this geometry to nuclear fuel design, the results were striking. In laboratory tests, a prototype fuel lattice transferred heat roughly three times more efficiently than the solid cylindrical fuel rods used in reactors today.

The Geometry Behind Better Fuel

Traditional nuclear fuel sits in long, solid rods. Coolant flows around them, absorbing heat. It's functional, but it's also limited by the rod's smooth surface and the physics of how liquid or gas can move past it.

The INL team, working with researchers at the University of Wisconsin, designed something called INFLUX — the Intertwined Nuclear Fuel Lattice for Uprated heat eXchange. Instead of a solid rod, it's a repeating lattice structure with gaps and channels woven throughout. The coolant doesn't flow around it; it flows through it. More surface area, more contact points, better heat removal.

To test the concept, they 3D-printed an electrically conductive model and ran heat through it using both gas and liquid coolants. The results held up: the TPMS design outperformed conventional geometry by a factor of three.

Making this work at scale meant solving a manufacturing problem. The lattice is intricate — not something you can simply cast or machine. The team developed a hybrid approach combining advanced 3D printing with hot-isostatic pressing, a technique that uses heat and pressure to fuse metal and ceramic components. They've already fabricated working prototypes.

Why This Matters for Reactors

Better heat transfer means you can run a reactor cooler and safer. Thinner fuel, lower operating temperatures, less thermal stress on materials — these add up to a design that's harder to break and easier to manage in an emergency. The lattice geometry also affects how neutrons move through the fuel, potentially reducing the number that escape without contributing to the chain reaction.

The researchers see particular promise for microreactors and gas-cooled systems, where efficiency gains matter most. The next phase is identifying which reactor types would benefit most from this design and moving toward real-world testing.

Nature has been optimizing heat transfer for millions of years. It took mathematicians and engineers to recognize the pattern and ask: what if we used that in a nuclear reactor. The answer, so far, looks like it could make nuclear power safer and more efficient.