The molten-salt reactor in the park dissolves its fuel in the coolant. If power fails, a frozen plug melts and the fuel drains by gravity into a tank where it cannot stay critical.
In this plant the fuel is dissolved in the coolant. A hot salt with uranium in it flows through channels in a graphite block, where it goes critical, and then out to a heat exchanger.
| Fuel salt | Fluoride salt with uranium |
|---|---|
| Temperature | ≈ 650 °C at near atmospheric pressure |
| Thermal power | ≈ 30 MWt |
| Moderator | Graphite |
A pump on the vessel head moves the fuel salt around the loop. The motor sits above the salt, out of the heat, with a long shaft down to the impeller.
| Type | Vertical shaft, sump pump |
|---|---|
| Flow | ≈ 0.5 m³/s |
| Shaft seal | Inert gas |
Fuel salt on one side, a clean coolant salt on the other. Fission products stay in the primary loop. The coolant salt carries the heat to the steam plant.
| Type | Shell-and-tube |
|---|---|
| Material | Nickel alloy |
| Secondary salt | FLiBe or FLiNaK |
A small blower keeps a plug of salt frozen in the drain line. If power fails, the blower stops, the plug melts, and the fuel drains by gravity into this tank, where it cannot stay critical and cools passively.
| Plug | Frozen salt, ≈ 20 mm pipe |
|---|---|
| Drain time | Minutes |
| Tank | Flat, subcritical shape with cooling fins |
Gaseous fission products bubble out of the liquid fuel. The off-gas system pulls them into charcoal beds, holds them while they decay, and keeps the loop clean.
| Gases | Xenon, krypton, tritium |
|---|---|
| Hold-up | Charcoal beds, days to weeks |
| Carrier | Helium sweep gas |
Coolant salt boils water in the steam generator, and the steam turns the turbine-generator under the canopy. The reactor cell wall sits between here and the fuel.
| Electric output | ≈ 10 MWe |
|---|---|
| Steam | ≈ 550 °C |
| Cooling | Dry air-cooled condenser |