Small modular reactors and fuel for them. The reactors are a high-temp gas cooled design. Helium is used as the cooling gas. The TRISO fuel pellets (see this reference) are “no larger than” a billiard ball and contain 18,000 particles of (assuming enriched) uranium wrapped in several layers of graphite. More than 200,000 of these pellets are cycled through the reactor core. The Helium cooling gas goes through a heat exchanger to heat water to steam, which runs a turbine. Overall the design seems similar to Ultra Safe Nuclear Corporation.
They are also working on a portable version of the reactor for emergency power applications.