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A fission reactor the size of a 20-foot shipping container went critical in Idaho 150 days after the project started, makes one megawatt, ships on an ordinary truck, swaps its core every five years and runs on the same 4.95 percent fuel every US plant already burns

A fission reactor the size of a 20-foot shipping container went critical in Idaho 150 days after the project started, makes one megawatt, ships on an ordinary truck, swaps its core every five years and runs on the same 4.95 percent fuel every US plant already burns

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By: Luis Reyes

Published: Sep 4, at 3:58am ET

The 20-foot shipping container is the most standardized object in world trade. Sneakers, engine blocks, flat-pack furniture: anything that fits the box moves by truck, rail or ship without anyone redesigning a thing.

A Houston company called Deployable Energy has now built a nuclear reactor to those exact dimensions, and the reactor has already run a self-sustaining chain reaction.

The product is called the Unity Nuclear Battery, and the name undersells the physics. Each unit is a 1-megawatt-electric fission reactor, water-moderated and helium-cooled, packaged into a standard 20-foot (6-meter) box that travels on ordinary trucks, trains and ships.

On August 18, the state of Utah signed a memorandum of understanding with Deployable to work out whether and where Unity units could be sited across the state. The demonstration reactor had gone critical at Idaho National Laboratory seven weeks earlier, roughly 150 days after the project kicked off.

The “battery” is a real fission reactor

Plenty of devices get called nuclear batteries, and most of them are radioisotope generators: lumps of decaying plutonium or strontium that trickle out watts for decades, the kind NASA bolts to space probes.

Unity is not that. Unity runs a controlled chain reaction in uranium fuel, the same physics working inside every commercial power plant in the country.

The battery framing describes how Deployable wants you to use the thing. The company builds the reactor in a factory, ships it sealed, plugs it in where power is needed, and swaps cores every five years, with used fuel going to a central site off site.

A single box makes 1 megawatt. Deployable says identical modules stack into arrays of several hundred units, and the heat coming off one can go to liquid, go to air, or get taken straight off as process heat.

For scale, Aalo Atomics is packaging 10-megawatt reactors into 50-megawatt pods aimed at AI data centers. Deployable went the other way, down to 1.

The box went critical on a deadline set by executive order

Executive Order 14301, signed in May 2025, handed the Department of Energy a strange and very specific homework assignment: get at least three brand-new test reactors to criticality by July 4, 2026, the country’s 250th birthday.

Two DOE fast tracks ran under it. The Reactor Pilot Program opened in June 2025 and let companies build and test first-of-a-kind reactors on DOE authorization instead of a Nuclear Regulatory Commission license. The Nuclear Energy Launch Pad arrived in March 2026 through the National Reactor Innovation Center at Idaho National Laboratory, extending that same route to developers the first program had no room for.

The deadline held. Antares Nuclear’s Mark-0 went critical at Idaho on June 4. Valar Atomics’ Ward 250 followed at the Utah San Rafael Energy Lab on June 18. Unity sustained its chain reaction on June 30, the first criticality logged under the Launch Pad initiative, and Deployable announced it on July 1. Aalo’s Aalo-X crossed at 12:20 a.m. MT on the Fourth itself.

Four reactors made a three-reactor deadline.

“Achieving criticality in roughly 150 days is a remarkable accomplishment,” Idaho National Laboratory director John Wagner said in Deployable’s announcement.

Criticality is the point where the neutron bookkeeping balances: each generation of fissions kicks off exactly enough neutrons to start the next, no outside source required.

Unity’s first run was a zero-power demonstration on a full-scale core load, which means the chain reaction held without producing meaningful heat or a watt of electricity. The phased test campaign in Idaho still has to validate reactor physics, load following, inherent safety and full-power operations before the conversation turns to paying customers.

Output per box
1 MWe
One 20-foot (6-meter) container per unit. Deployable says identical modules stack into arrays of several hundred.
Fuel enrichment
4.95%
Uranium dioxide under the 5% commercial ceiling. Helium-cooled, water-moderated, five-year refueling cycles.
Kickoff to criticality
150 days
First self-sustaining chain reaction on June 30, 2026, at Idaho National Laboratory. Utah signed its MOU on August 18.
TARGET
Mass production
2030
Six-month delivery lead times quoted by Deployable once factory output starts. Full-power demo slated for 2027.

The fuel is the genuinely clever part

Most microreactor startups designed themselves into a fuel problem. Their cores call for high-assay low-enriched uranium, HALEU, material enriched between 5% and 20% that remains scarce in the United States: Antares got its TRISO fuel fabricated on a conditional commitment of the government’s own HALEU stock.

Deployable skipped the queue. Unity runs on uranium dioxide enriched to 4.95%, per the company’s technical specifications, just under the 5% ceiling that commercial reactor fuel has sat below for decades. Every fabricator already serving America’s power plants handles that material today.

Bobby Gallagher, Deployable’s co-founder and CEO, credited the existing fuel supply chain as one of the things that made the 150-day sprint possible.

The coolant is helium, the moderator is ordinary water, and the listed materials are deliberately unexciting industrial stock rather than exotic alloys. Deployable treats unexciting as the pitch. A reactor made of parts factories already produce is a reactor that fits on an assembly line, which is the entire business model.

Unity also parts ways here with the Pentagon’s Pele microreactor, the transportable unit whose 40,000 fuel compacts have been sitting in Idaho waiting for final assembly in Virginia. Pele is a one-off Pentagon prototype built for a single demonstration. Unity is pitched as a catalog product on standard oxide fuel, drawn for a production line rather than a program office.

So what did Utah actually sign?

Utah signed a framework, and an explicitly non-binding one. The August 18 document puts Deployable and the Utah Office of Energy Development on the same side of a table, swapping information while the two of them work out whether the boxes belong in the state at all, from early research through testing and demonstration to any commercial rollout that might follow.

The paper approves no construction, licenses no reactor and obligates nobody to buy anything.

Emy Lesofski, who directs the Office of Energy Development and advises Governor Spencer Cox on energy, called the agreement “another step towards an abundant energy future that is reliable, secure and clean.” Cox met Deployable’s leadership in July, posing for the kind of group photo governors reserve for companies they intend to keep around.

Utah has been collecting nuclear paperwork at a steady clip. Governor Cox launched Operation Gigawatt in October 2024 to double the state’s power production inside ten years, with demand pressure coming from population growth and power-hungry data centers. The state signed an MOU with Idaho National Laboratory in April 2025, another with microreactor developer NuCube for a test unit at the San Rafael Energy Lab in Orangeville, and another with TerraPower.

Valar’s Ward 250 then went critical at that same San Rafael site in June, so a reactor startup has already run a chain reaction on Utah ground under this push.

Utah’s grid, through all of it, still carries zero commercial nuclear generation. The state does run the country’s only operating conventional uranium mill, and the newest reactor going up at the Idaho lab is an 85-kilowatt federal test machine nobody can buy.

The same box is getting sea legs

Deployable spent the two weeks before the Utah signing stacking up partners.

Hornbeck Offshore, which operates high-spec offshore service vessels across the Gulf and Latin America, signed its own MOU with Deployable on August 17. The two picked five maritime markets to chase: river and inland waterway traffic, offshore vessels and platforms, defense logistics and uncrewed vessels, towable power barges, and floating data centers. Hornbeck also put in money as a strategic investor, on undisclosed terms.

Solaris Energy Infrastructure, the NYSE-listed Houston outfit renting mobile turbine fleets to data centers, disclosed an equity stake of its own in August.

Deployable says it is the only commercial microreactor developer holding both an initial criticality and an Approval in Principle from a maritime classification society. Lloyd’s Register issued that approval in February, covering a hybrid nuclear-diesel arrangement on an amphibious stern landing vessel.

Hornbeck and Deployable are targeting at least a 20% cut in total cost of ownership against conventional marine diesel or grid power, per the joint announcement, with classification, licensing and engineering mapped as a phased program. A power plant that ships like cargo can, in principle, float like cargo.

Zero Unity units have been sold, sited or licensed for commercial operation anywhere. The Utah MOU binds nobody, the Hornbeck program starts with feasibility studies rather than shipyards, and the Idaho test campaign still has full-power operations ahead of it.

Nuclear Engineering International reports that a full-power demonstration of Unity is slated at Idaho National Laboratory in 2027, and Deployable’s own spec sheet quotes six-month delivery lead times starting in 2030.

The National Reactor Innovation Center picked Deployable for two more Launch Pad demonstrations on August 28: the full-power run in Idaho, and a maritime one with Hornbeck. The box went critical on June 30, 2026. Utah’s signature is dated August 18.

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31 comments

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@brucejaworski ROOKIE6 days ago
Why don't they say how much each unit costs and is there a price break at 100?
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hanswolfgangsch DRIVER6 days ago
Yeah, not all journalism is that level. But the hint was its supposed to be cheaper by 25%, assuming nothing was left off the invoice.
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@andythreadnanny ROOKIE5 days ago
What happens when a Nepal like disaster strikes and the container is damaged. Do we have another catastrophe on hand ?
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@ryangreen ROOKIE6 days ago
What does the size of the reactor matter if you still need 5-10 acres of building infrastructure and another 20-30 acres for grid infrastructure and fencing? They may be smaller than conventional nuclear plants but they make a lot less power (this 1 Mw is 1000x to 1600x less than a modern full size plant) and aren't nearly as portable as the constant headlines only mentioning the reactor size make them sound.
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hanswolfgangsch DRIVER6 days ago
Agreed, smr don't yet explicitly list what is required to support them. Probably lots of water and a cooling tower and a turbine as a minimum.
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@rogeroakes ROOKIE6 days ago
The micro sized vs small sized difference is being overlooked here. Kind of like the difference between computer size differences were underappreciated in the 1950-2000-2020s where we went from room size to bookcase to desktop to handheld computers now called "phones" please don't make that mistake in downsizing and upgrading the benefits of nuclear energy at the same time. Nowhere does the article mention any limitations in Max or min terms for grid or building infrastructures. I think too many "boxes" exist in the conversation that needs to be widened by more in depth information and mind and culture constraints erased.
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@jordanloveless ROOKIE6 days ago
I'm thinking they're going to power the floating data centers and maritime hideaways for the rich and powerful. They're going to start wars and then run away to their floating fortresses where the raging plebs can't get to them.
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@bellington007 ROOKIE6 days ago
Good article. Misleading jargon "went critical" in the headline may give laymen the impression the reactor failed, when in fact it became operational. Please consider changing the headline.
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@davidroberts ROOKIE6 days ago
Yes, industry jargon should be avoided if possible in public forums. Perhaps something like 'demonstrated a self sustaining reaction ' would be better.
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hanswolfgangsch DRIVER6 days ago
Critical is the half century old word for operational, as enough neutrons have to join the race to generate a sustainable reaction.
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@fromdavewood ROOKIE6 days ago
That's what I thought. It failed.
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@jordanloveless ROOKIE6 days ago
Yeah, I thought it meant it went boom boom at first, but after reading the article, I deduced that it meant gained functionality.
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@frankk ROOKIE6 days ago
You are confusing it with SUPERcritical, which admittedly would be bad. Going critical is a steady thate that is required for operation.
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@allenmorgan ROOKIE5 days ago
Going critical does not imply or mean its producing any electrical power...that's just testing the nuclear fuel configuration/loading and control of it. They'll be doing that for at least weeks if not months. And as others have noted, hook up to grid, maintenance facilities,and cooling may not be complete themselves... And this brings up another question...do you have to have nuclear operator(s) on site and monitoring 24 x 7? What about security...Nuke plants require 24 x 7 armed perimeter security.
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@jasonadams ROOKIE6 days ago
Should have used thorium
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@davidroberts ROOKIE6 days ago
If this article is intended for laymen, how many will relate to 1MWe? One could, for scale say about enough power to supply 800 households.
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@generussel ROOKIE5 days ago
I would wager that most people who understand an article like this well enough to keep reading are capable of doing some cursory research on things they do not understand. Besides, the power quantity is somewhat irrelevant to anyone who isnt trying to buy power. The point is that a breakthrough in small scale able nuclear has happened and appears to be ready to deploy at scale without hiccups in fuel sources which have been issues for other companies. The rest is researchable.
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richardmercer ROOKIE6 days ago
And a BESS battery storage unit the size of a shipping container could store 5MW of it
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@generussel ROOKIE5 days ago
Bess requires power, it doesnt produce power. When grid is taxed or a site requires power that isnt available a battery only does good for so long.
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@rogeroakes ROOKIE6 days ago
The cooling system is in need of more emphasis as all nuclear accidents of whatever size we're always due to failed water based coolants. Here they mention water based moderators but helium as a coolant? Helium is much more rare and expensive than water and the loss of coolant caused all accidents.
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@generussel ROOKIE5 days ago
That’s not really how nuclear accidents work. Cooling failures can be a problem, but saying every nuclear accident was caused by losing water coolant is just wrong. Chernobyl, for example, was mainly caused by a badly designed reactor and a runaway power surge, not the cooling water failing. Helium is also used on purpose in some newer reactor designs because it doesn’t boil, doesn’t react chemically with the reactor, and can operate at much higher temperatures. Yes, helium costs more than water, but coolant cost is a tiny issue compared with whether the reactor is safer and easier to keep cool. Also, a moderator and a coolant do different jobs, so using water for one and helium for the other is completely normal.
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@madmick ROOKIE6 days ago
Its a failure, helium being such a finite resource we are running out of does not make it scalable.
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@generussel ROOKIE5 days ago
Reactor helium is a closed loop system and not considered a consumable. Currently we habe about 8.5 billion cubic meters of recoverable helium in the us reservoirs alone, I dont think that is generally going to be an issue for production of this size of reactor. Helium has been used as a coolant for a long time. Fort St. Vrain in Colorado, a commercial 330 reactor that used helium as its primary coolant was online for 20 years and China's newest reactors also use helium as a coolant..its just more efficient in a closed loop and doesnt create pressure since it doesnt boil.. you are right that it is a finite resource but given in these cases it is also not a consumable I dont think this will be problematic.
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@allenmorgan ROOKIE5 days ago
This is more of an advertisement then journalism. Ok, how long does it produce 1Mw power before it begins to run down...say to 90%? 90 Days...180? What? Also, when does it get refueled...also, how does it get refuled and at what cost, and how long does it take to get refuled...what happens to the old fuel? Who recycles that, and at what cost, at what danger to immediate and long term? What increased likely hood of terroist use of a higher grade uranium is there...will it make a better dirty bomb?
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@jscottburge ROOKIE4 days ago
The article says it gets refueled every 5 years.
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@dimangel ROOKIE5 days ago
So a whole new nuclear waste stream to manage
One that needs servicing every five years and which scales up with every box they lease/sell
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@nicolasmartin ROOKIE5 days ago
If only this had been written well.
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@jamesvanzandt ROOKIE4 days ago
I wonder how many towns in Alaska could use one of these to replace diesel generators? They could get district heating too. Maybe use "ice road truckers" to deliver that shipping container?
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@markswallow ROOKIE4 days ago
What about the waste? How are we going to keep this material out of the hands of terrorists? So many safety questions...
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@paulwortley ROOKIE21 minutes ago
Great article. Pity about the comments.
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@karlneblett ROOKIE6 days ago
Privatized nuclear reactors marketed to data centers that have already displayed gross apathy for public problems they create. What could go wrong?
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Luis Reyes

Luis Reyes

With more than 14 years covering the automotive industry, Luis Reyes is a seasoned voice in the field. A law graduate, he channels his curiosity and expertise into the detailed analysis of national and international regulations that shape the automotive world. At Autonocion.com, Luis combines his strong legal background with a deep passion for vehicles — especially those that have left a mark on automotive history. His experience writing for multiple brands across the industry has established him as a trusted authority. Luis is committed to sharing his expertise and enthusiasm with enthusiasts and industry professionals alike, with a firm belief in the continuous evolution and innovation driving the auto industry forward.
Contact: info@autonocion.com
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