In a small Wyoming coal town, a 4 billion dollar project has begun building the first new kind of US nuclear reactor in 40 years, one that stores its heat in molten salt and can surge to 500 megawatts on demand

In the high plains of southwest Wyoming sits the town of Kemmerer.

It is a small and remote place, built long ago on coal.

For years, a nearby power plant burned that coal for electricity.

Multilingual from an early age, his writing combines technical clarity with a strong interest in science and energy.

That old plant is now winding down toward the end.

But right beside it, something brand new is rising.

Crews are building a machine quite unlike any other in the country.

It promises to run in a way no reactor has before.

And the trick lies in a tank of salt.

A coal town looks ahead

Kemmerer has leaned on coal for over a century.

The mines and the power plant gave the town its jobs.

But coal plants across America are closing fast.

The local plant is set to retire in the coming years.

That could have drained the town of work and hope.

Instead, a company chose Kemmerer for a bold project.

They picked the site right next to the old coal plant.

The idea was to bring new energy jobs to the same workers.

A plant like this needs hundreds of hands to run.

Many could move straight from coal to the new plant.

Their skills in power and machinery would still be needed.

A dying industry might give way to a fresh one.

And the town could keep its future.

A reactor with a famous backer

The company behind the project is called TerraPower.

It was founded years ago with backing from Bill Gates.

Their design is a nuclear reactor named Natrium.

It is not the kind of reactor most of us picture.

Nearly every US plant today uses ordinary water to cool it.

This one is a fast reactor cooled by liquid sodium.

In 2026, regulators gave it a permit to build.

Then the first full construction work got under way.

It was the first such approval in nearly ten years.

The country had not started a plant like this in ages.

No commercial design this different had been cleared in decades.

Full construction has now truly begun.

Kemmerer sits at the leading edge.

Why sodium instead of water

The choice of sodium may sound strange at first.

Water cooled reactors must run under huge pressure.

Liquid sodium can stay cool without that intense squeeze.

It also carries heat away far more easily than water.

That lets the reactor run hotter and more efficiently.

Hotter output means more useful energy from the same fuel.

The sodium stays liquid across a wide range of heat.

Sodium reactors are not a totally new idea in science.

Engineers have studied them for many decades.

But few have ever been built at this scale for the grid.

The hot sodium is the key to the whole design.

Its heat feeds into the clever part.

And that is where the salt comes in.

The reactor that stores its heat

Here is what really makes Natrium so unusual.

According to one report, the reactor is paired with a giant molten salt heat store.

The reactor sends its heat into tanks of hot melted salt.

That salt can hold the heat like a huge thermal battery.

The plant normally makes about 345 megawatts of power.

But when demand spikes, it can tap the stored heat.

For a few hours it can surge up to 500 megawatts.

That lets it ramp up and down like a battery would.

The reactor itself keeps humming along at a steady pace.

Only the flow of stored heat rises and falls.

It can fill the gaps when wind and solar fade.

A steady reactor gains sudden flexibility.

Heat becomes a form of stored power.

What it could mean for the grid

This mix of steady power and quick surges is rare.

Most old reactors run flat out and cannot easily shift.

A flexible plant fits far better with wind and solar.

It can lean back when the sun shines and rise at night.

If it works, many more could follow across the country.

Data centers and cities are hungry for steady clean power.

A plant that bends to demand could be a strong fit.

The project still faces years of work and a big budget.

Its full cost runs into the billions of dollars.

According to one account, the plant aims to reach full power around the end of the decade.

The same push for a cleaner grid shows up elsewhere, from a solar farm fox to the seals near an offshore wind farm.

For a small and proud coal town, it is a daring bet on the future.

Where coal once burned, a reactor may soon store its backup power, one tank of salt at a time.