What is Thorium?

The Element

Thorium is element 90 on the periodic table — a silvery, slightly radioactive metal discovered in 1828 and named after Thor, the Norse god of thunder. It's found in beach sands, granite, and common minerals like monazite.

It's approximately four times more abundant in Earth's crust than uranium. Much of it is stockpiled as a byproduct of rare earth mining — already mined, waiting to be used.

The Fuel Cycle

Thorium-232 is not fissile on its own — it cannot sustain a chain reaction. But when it absorbs a neutron, it transforms through a series of steps into uranium-233, which is an excellent nuclear fuel.

Th-232 + neutron → Th-233 → Pa-233 → U-233 (fissile)

This means a thorium reactor needs a small amount of fissile material to get started, but then breeds its own fuel from thorium.

Why It Matters

• Abundant: Enough thorium to power civilization for thousands of years.
• Less long-lived waste: Thorium cycle waste is radioactive for ~300 years, not ~300,000 years for conventional spent fuel.
• Proliferation-resistant: The U-232 byproduct makes the uranium extremely difficult to weaponize.

What We Don't Have Yet

No commercial thorium reactor exists today. The technology was demonstrated at Oak Ridge National Laboratory from 1965-1969, and over a dozen companies are now racing to build the next generation. But significant engineering challenges remain: corrosion from molten salts, fuel reprocessing at scale, and regulatory frameworks designed for a different type of reactor.