Fuel Element Manufacturing Technology

High-quality fuel - powering the future of small modular reactors

With growing global demand for clean energy and industrial decarbonization, Small Modular Reactors (SMRs) are emerging as a key technology. Their ability to deliver carbon-free, high-temperature process heat makes them ideal for replacing fossil fuels in a wide range of industries. At the heart of these advanced reactors lies a critical component: fuel.

NUKEM has a longstanding legacy in high-temperature reactor (HTR) fuel development and manufacturing. As early as the 1960s, we were a key contributor to the German HTR program, with responsibility for fuel specifications, fuel element design, and the development of manufacturing processes. This foundational work laid the groundwork for decades of TRISO fuel innovation.

In the 1970s and 80s, our subsidiary HOBEG produced over 1.25 million spherical fuel elements for Germany’s AVR and THTR reactors. These fuel elements, based on TRISO technology, set international standards for safety and performance - standards that continue to guide modern fuel qualification.

TRISO fuel, with its multi-layered ceramic coating and unmatched fission product retention, is the backbone of today’s HTR designs. Whether in spherical pebble form or cylindrical compacts, TRISO fuel is essential for achieving the intrinsic safety and high-temperature capabilities that distinguish HTRs.

NUKEM’s expertise spans the entire TRISO production process:

While TRISO fuel is central to HTGR designs, a broader SMR deployment requires the capability to manufacture a range of uranium-based fuel types. Many of the recent SMR designs are based on high-assay low-enriched uranium (HALEU).

NUKEM has decades of experience in uranium metal fuel fabrication, starting in the 1950s with the production of metallic fuel elements for research reactors such as the FR2 in Karlsruhe and the ECO reactor in Ispra. After these early successes, NUKEM continued to produce metallic uranium fuel including alloys (U-Al, U-Si) for various research reactors including the high-flux reactor at Institut Laue–Langevin (Grenoble, France). High enriched uranium was processed for this purpose.

Today, one of the preferred routes for producing uranium metal is based on the ammonium uranyl carbonate (AUC) deconversion process: enriched uranium hexafluoride (UF₆) is first converted to uranium dioxide (UO₂) via a wet process. The produced UO₂ is then hydrofluorinated to uranium tetrafluoride (UF₄) and reduced via a calciothermic process to metallic uranium.

This expertise has led to the design and construction of industrial production facilities, such as the plant for the Indonesian nuclear energy agency BATAN, which continued to produce 20% enriched uranium metal for test reactors. The ability to manufacture all SMR-relevant fuel types - TRISO, oxide, metal alloys, and salt-based fuels - from the same initial material is a key contribution to the flexibility and future resilience of modern nuclear fuel supply.

We’ve continuously improved our fuel manufacturing technology, incorporating advanced safety designs such as geometrically safe equipment and near-zero waste handling. Our experience in reviving and updating TRISO processes, including design work for the South African PBMR fuel plant, makes us a unique partner in supporting the deployment of modern SMR fleets.

As new reactor projects take shape around the world, NUKEM is ready to deliver the high-performance fuel they need. Our manufacturing technologies are not only proven but scalable - providing the foundation for reliable, low-carbon energy for decades to come.