Our concept

Inertial fusion is a pulsed process, like an internal combustion engine. Each target releases a large amount of energy; the power output is the energy per shot multiplied by the frequency. A pulsed approach gives great design flexibility, trading off energy per shot and frequency. Our aim is the lowest risk plant design possible. High energy per shot reduces physics risk, and slower frequency and small overall plant size reduce the engineering risk.

The target will simply be dropped into the reaction chamber from above, falling under gravity. The projectile is launched downwards on top of the target and catches it up in the centre of the chamber. The impact is focused by the target and a pulse of fusion energy* is released. That energy is absorbed by the lithium flowing inside the vessel, heating it up. Finally, a heat exchanger transfers the heat of the lithium to water, generating steam that turns a turbine and produces electricity.

* we had a vote and decided that neutrons are purple

This plant design avoids the three biggest engineering challenges of fusion: preventing neutron damage, producing tritium, and managing extreme heat flux. Lithium is used to produce tritium, one of the two fusion fuels. Our design allows tritium self-sufficiency with pure lithium in the natural isotope balance. This is a major advantage as the only by-product is helium, and there is an established supply chain for normal lithium.

The thick liquid lithium also blocks the neutrons from reaching the vessel, meaning that it will last for the lifetime of the plant. The liquid first wall also addresses the issue of very high heat flux. Some of the lithium will be vapourised by the energy release, but it simply recondenses.

There is a large amount of existing engineering that can be reused to realise this plant design. Fast breeder reactors, a type of nuclear plant, use liquid metal as the coolant, typically sodium or sodium-potassium mixture. The engineering from these plants can be ported over to lithium. After the lithium heat exchanger, the plant is identical to many other already working facilities. Most of the cost is low risk engineering.

We are aiming for a power plant producing ~150 MW of electricity, firing once every 30 seconds, and costing less than $1 bn.