Four kinds of microreactor, side by side

The four plants in the 3D model use four different ways to move heat out of a small core. Each choice sets the pressure, the temperature, the fuel form, and the kind of safety case the design can make. The table lists the values the model uses. They are typical of each class, not a specific product.

Feature	Sodium pool (main plant)	Heat pipe	Gas-cooled	Molten salt
Coolant	Liquid sodium in a pool	Sodium inside sealed heat pipes	Helium gas	Fluoride salt that also carries the fuel
Fuel	HALEU metal or oxide pins in steel cladding	TRISO compacts in a solid block	TRISO particles	Uranium dissolved in the salt
Thermal power	≈ 30 MWt	≈ 15 MWt	≈ 15 MWt	≈ 30 MWt
Electric output	≈ 10 MWe	≈ 5 MWe	≈ 5 MWe	≈ 10 MWe
Pressure	Near atmospheric	Near atmospheric	≈ 7 MPa	Near atmospheric
Core outlet temperature	≈ 550 °C	≈ 650 °C	≈ 630 °C	≈ 650 °C
Power cycle	Supercritical CO₂ Brayton	Open-air Brayton	Steam Rankine with salt storage	Steam Rankine
Refueling	Whole-core swap every 5 to 10 years	Swap the module after about 8 years	About 20 years on one core	Fuel salt adjusted on line
Moving parts in the core loop	Electromagnetic pumps, no impellers	None	One helium circulator	One fuel-salt pump
Signature safety feature	Natural-draft air cooling of the vessel	Heat leaves by conduction, no coolant to lose	Fuel coatings hold fission products above 1,600 °C	Freeze plug drains the fuel to a safe tank
Where in the model	Main plant, powering the data center	Park plot A, canister open	Park plot B, with two salt tanks	Park plot C, reactor cell

Feature

Sodium pool (main plant)

Heat pipe

Gas-cooled

Molten salt

Coolant

Liquid sodium in a pool

Sodium inside sealed heat pipes

Helium gas

Fluoride salt that also carries the fuel

Fuel

HALEU metal or oxide pins in steel cladding

TRISO compacts in a solid block

TRISO particles

Uranium dissolved in the salt

Thermal power

≈ 30 MWt

≈ 15 MWt

≈ 30 MWt

Electric output

≈ 10 MWe

≈ 5 MWe

≈ 10 MWe

Pressure

Near atmospheric

≈ 7 MPa

Near atmospheric

Core outlet temperature

≈ 550 °C

≈ 650 °C

≈ 630 °C

≈ 650 °C

Power cycle

Supercritical CO₂ Brayton

Open-air Brayton

Steam Rankine with salt storage

Steam Rankine

Refueling

Whole-core swap every 5 to 10 years

Swap the module after about 8 years

About 20 years on one core

Fuel salt adjusted on line

Moving parts in the core loop

Electromagnetic pumps, no impellers

None

One helium circulator

One fuel-salt pump

Signature safety feature

Natural-draft air cooling of the vessel

Heat leaves by conduction, no coolant to lose

Fuel coatings hold fission products above 1,600 °C

Freeze plug drains the fuel to a safe tank

Where in the model

Main plant, powering the data center

Park plot A, canister open

Park plot B, with two salt tanks

Park plot C, reactor cell

The sodium pool and the molten-salt designs run hot at low pressure, so they avoid a thick pressure vessel. The gas-cooled design accepts high pressure in return for an inert coolant that cannot boil. The heat-pipe design removes pumps and valves from the core entirely, at the cost of lower power per module.

All four reject their waste heat to air. None of them needs cooling water.

Read each design