How a high-temperature gas reactor works
Xe-100: 200 MWt · 80 MWe · ~220,000 fuel pebbles · helium 260 → 750 °C · steam 565 °C
Helium blows down through a bed of tennis-ball-sized fuel pebbles and comes out hot enough for industrial steam. Pebbles cycle through the core while it runs. Follow the helium, the pebbles and the steam. Every number comes from one model.
Sources: X-energy, Xe-100 reactor overview (200 MWt, 80 MWe, 750 °C outlet); arXiv 2504.02599, “Technical overview of recent developments in small modular reactors in the United States” (≈224,000 pebbles, ~175 new pebbles a day, steam 565 °C and 16.5 MPa); helium inlet 260 °C and ~6 MPa from X-energy's NRC pre-application material. Pebble cycling pace and the timeline are illustrative. Others on this approach: Valar Atomics, Radiant.