Beneath a Wyoming coal town’s last smokestack, 345 megawatts of liquid metal just broke ground, and the tank buried beside the reactor is the reason every grid manager in America took notice

Something unusual is rising in a small Wyoming coal town, and at first glance it looks like every industrial project that came before it.

There are concrete foundations being poured.

There are steel frameworks going up against a pale sky.

The grid infrastructure was already in place, the skilled workforce was already here, and a community that understood energy work would not need years of convincing.

The hills around Kemmerer have absorbed the noise of heavy industry for more than a century, and the crews working the site have not changed much either.

But what is being built here has never been built anywhere in America before.

And the number that will define it is only half the story.

A coal town that knew what was coming

Kemmerer, Wyoming has lived on energy work for generations.

Its workforce learned boilers, turbines, and high voltage lines before most of them finished high school.

When the Naughton coal plant next door began its wind down, the town did not panic.

It had been through transitions before.

What nobody expected was the specific thing that would arrive to replace it.

The grid infrastructure was already in place, the skilled workforce was already here, and a community that understood energy work would not need years of convincing.

The permit that took fifty years to arrive

Before a single foundation could be poured for the reactor itself, a piece of paper had to exist that had never existed before.

In March 2026, the NRC issued a construction permit for the project, the first ever granted by the commission for a commercial non light water reactor.

Every commercial reactor operating in the United States today runs on ordinary pressurized water.

Approving something fundamentally different meant the regulator had to build an entirely new review framework from scratch.

The NRC review finished in 18 months, nine months ahead of schedule.

Then, on April 23, 2026, construction officially began.

The metal that melts like butter and runs hotter than a furnace

Most reactors you have ever heard of use water, but water has a problem.

To stop it from turning to steam inside the core, engineers must keep it under crushing pressure, roughly 155 times the air pressure at sea level.

This reactor circulates liquid sodium coolant through its core, where the sodium absorbs heat generated by nuclear fission in the fuel assemblies.

Liquid sodium runs near normal air pressure and can carry enormous heat without the thick walled pressure vessel that makes conventional plants so costly.

The reactor’s heat output exceeds 500 degrees Celsius.

That is hot enough to do something conventional plants cannot quite manage, something grid operators across the country have been waiting a long time to see.

The tank that turns a reactor into a battery

Here is what the project is really about.

The plant pairs a 345 MW sodium cooled fast reactor with an integrated molten salt energy storage system, and on April 23, 2026, construction began in earnest.

When electricity demand is low, surplus heat from the reactor is pumped into a massive tank of molten salt, a mineral mixture that holds heat the way a cast iron skillet holds warmth long after the burner goes off.

When demand spikes, that stored heat is released back through the turbines.

The storage system can boost output to anywhere between 100 and 500 megawatts for more than 5.5 hours, ramping at 10 percent per minute.

At its 500 megawatt peak, that covers something close to 400,000 homes.

A nuclear plant that can sprint when the grid screams for power, then settle back to a steady baseload hum, is something no architect of the American grid ever had available before.

For Wyoming’s coal communities, the arrival of a technology this flexible carries its own particular weight.

What comes next, and what could still go wrong

The energy storage island is proceeding ahead of the nuclear island, with construction completion expected in early 2031.

That sequencing is deliberate: the two halves are designed to be built and licensed on independent schedules, reducing the risk of one delay cascading into the whole project.

The total project cost is close to four billion dollars, with roughly half coming from the Department of Energy’s Advanced Reactor Demonstration Program.

HALEU supply, the specialized high assay low enriched uranium the reactor requires, remains the program’s principal watch item.

The NRC’s transportation rules will also shape how quickly the fuel supply chain can be assembled.

Around 1,600 construction workers will be mobilized at peak building activity, with about 250 permanent jobs expected once the plant is operational.

Many of those roles match the exact skills a coal or gas crew already carries.

On the Wyoming plateau where a coal plant’s final years are ticking down, the concrete is already setting.

It is being built, right now, on the same road they have always driven to work.