02 · Generation IVSix reactor concepts,
Six reactor concepts,
one comparative view.
The Generation IV International Forum has selected six reactor technologies for further development. Switch between concepts and compare their engineering trade-offs on the radar.
Schematic
Very High Temperature Reactor
VHTR · How it works
HTR-PM pebble-bed reference — TRISO fuel, graphite moderator, helium coolant, 250 → 750 °C, 7 MPa. Commercial operation Dec 2023 at Shidao Bay.
01 / 08
Helium flows through a pebble-bed core of ~420,000 graphite spheres moderated by graphite reflectors.
Conceptual schematic — not to scale. Depicts HTR-PM (Shidao Bay, China). HTTR and prismatic-block VHTR variants share the same principles with different core geometry.
Sources
- Gen IV International Forum · VHTR →
- World Nuclear Association · Small Nuclear Power Reactors (HTR-PM) →
- IAEA · Gas-Cooled Reactors (HTGR) →
- Zhang et al. · HTR-PM (Nucl. Eng. & Design 2009) →
- US DOE NE · TRISO — The Most Robust Nuclear Fuel on Earth →
- INL · Advanced Reactor Technologies (NGNP·HTGR) →
- JAEA · HTTR (950 °C demonstration) →
Specifications
VHTRVery High Temperature Reactor
CoolantHelium
Outlet Temp.750–950°C
Power200–600 MWt
FuelTRISO (UO₂/UCO)
Key Features
- Mass hydrogen production capability
- Very-high-temperature process heat for industry
- Passive safety — core melt inherently prevented
Current Status
China HTR-PM in commercial operation (750°C, 2023). 950°C is the hydrogen-production design target.
Comparative scoring
Engineering trade-offs across five dimensions