Radiant could provide safe, portable nuclear energy within the next 5 years

Former SpaceX engineer and Radiant CEO Doug Bernauer told us "execution is everything."
Chris Young
A render of the Kaleidos microreactor.Radiant Nuclear

Radiant Nuclear is developing a microreactor that they call the "world's first portable, zero-emissions power source."

The idea for the microreactor, called Kaleidos, stems from CEO Doug Bernauer's time working at SpaceX, where he was tasked with devising methods for producing enough power on Mars to allow future colonies to survive and also travel between Earth and the red planet.

Bernauer found that his work could also be applied on Earth to bring power to remote communities and military bases, and could also be used as an easily deployable fleet of reactors for populated areas.

According to Radiant, the Kaleidos — shown in the video above — will output more than 1MW, which is enough to power about 1,000 homes for up to eight years. It uses TRISO fuels and helium coolant instead of water, both of which should make the microreactor safer than traditional nuclear reactors.

Radiant recently announced it received $10 million in funding from the USV Climate Fund, a "thesis-driven venture capital firm" looking to invest in companies that aim to tackle climate change via rapid innovation. Bernauer spoke with IE on a video call about the next five years for Radiant and for the planet, as well as the role that space technology continues to have on his company. 

The following conversation has been lightly edited for clarity and flow.

Interesting Engineering: Could you tell us about potential prototype trials for Radiant's microreactors? Is there an estimated date?

Doug Bernauer: Our internal target here is we have 200 weeks. So I treat every week that's gone by as half a percent of the schedule. 

IE: Interesting, so all of your employees are working on this 200-week timeline?

We just started saying it and it's pretty exciting because if you tell scientists from an international lab we're four years away from doing it, they say okay, whatever, that sounds normal. As soon as you say it in a different way — like 200 weeks — they pay attention. It sounds pretty wild and a lot faster, right? And it's really just changing the units that does that.

IE: What companies or individuals have influenced you personally? 

At Radiant, we have the opposite of a stealth approach, and that's down to my negative reaction to Theranos and other companies like it. My experience in nuclear was that I had to quickly learn it over the course of just a couple of years after leaving SpaceX. I needed to talk to all these scientists, explain my idea and get them to teach me how nuclear technology works.

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"I treat it like my alma mater. If someone says where did you go to school, I'll jokingly say SpaceX."

And my influences are I was at SpaceX for 12 years. So I have a large number of different influences from the projects I worked on and the people I worked for within that organization. I treat it like my alma mater, right? If someone says where did you go to school, I'll jokingly say SpaceX. That's where I actually learned, right? So why not say that? 

IE: What big milestones can we expect from Radiant over the next five years? Is that a short time span for developing nuclear microreactors?

No, no, it's absolutely not. I mean, we're a hardware-focused company. And so we have milestones about every six months. Just this summer, we're going to conduct a test for a 12-ton heat sink, which will cool everything in our microreactor. We have a 50-ton system, and we have to make sure it doesn't exceed 50 tons so we can put it in an aircraft and fly it. That shows the size of our reactor and its portability.

Then, at the end of the year, we aim to have a helium compressor, which is really the heart of the system. It's the pump that drives the helium into the reactor and then extracts it, brings it back out, and then transfers it to the other equipment. It's a very cool machine. The pump is driven by a shaft that's floating on two magnetic bearings. It outputs 75 kilowatts of power and goes over 10,000 rpm.

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"Within five years we could have a first product out there."

We are also working towards building a helium loop test. We will build up the entire container here in our building. That will have a fault-tolerant control system. So you can go and rip the chords out of it while it's running and it will try to keep running and it can handle a lot of damage before it stops itself. That's part of our focus on autonomous and also maintenance-free operation. If a single sensor breaks somewhere in the system, we have designed it so that often there are two sensors helping that third sensor. So if we lose it, we have two other answers and we can pinpoint the underlying problem.

Our goal is really to be in production only a year or two after we do that fuel demo. So it's possible that within five years we could have a first product out there.

IE: Is Radiant using digital twin technology to speed up the development process?

Yes, digital twin technology is really at the heart of how we do all of our engineering. So, for example, we can simulate high-temperature, high-pressure CO2 fluid, expand it across a turbine and change the turbine spin from 40,000 to 25,000 RPM to test different parameters. In order to design any part of the system, you have to put the whole thing together in simulation. 

All of our digital twin code is fully developed in-house. We actually built a GUI on top of the system in order to use it so we call our tool Sim engine. It's made by Roger Chin and Bob Urberger, our two primary software guys.

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"Digital twin technology is really at the heart of how we do all of our engineering."

Our software also makes it so that, if you have hundreds of reactors and you deploy them all over the world, you can stream all that data back to a centralized location, produce a really giant data set, and then use machine learning on that to tell you what reactors are having issues. That could be a massive game-changer. So, in the U.S. we have over 90 operating reactors and they're all custom and unique, and they don't share data and they definitely don't do it in a manner where you could actually use big data.

So the NRC already has an amazing safety record, but you could beat that by using live fleet monitoring that tells your team of nuclear engineers exactly where they need to look. And that information could also be passed on to regulators.

IE: How is Radiant's microreactor safer than traditional nuclear reactors?

A traditional reactor uses water for coolant and that water becomes radioactive. We're using helium, which is extremely safe compared to water because it does the same thing without becoming radioactive. It is the only element that doesn't become radioactive because it is atomically stable. You can just hit it with neutrons endlessly and it will stay helium, but anything else that you hit with neutrons continuously, you're going to turn it into something else.

Another point is that traditional reactor fuel is in rods, and there are pellets of fuel in that rod. If the rod has a breach, that whole rod section will release its fission products, which are these radioactive gases that build up and the reason you have them sealed in a tube. Instead of doing this, we have tiny pellets the size of a poppy seed that are coated in multiple layers of graphite and a layer of silicon carbide. Silicon carbide is non-porous so it keeps all the fission gases down inside each pellet. 

IE: How will Radiant help to cut global carbon emissions?

One fuel load [for Radiant's microreactor] replaces about four tons worth of diesel fuel that would otherwise be used by power generators each day. One of our systems can have four cores loaded in it before we decommissioned the whole thing. Looking at it from that perspective, it would offset 22,000 tons of diesel fuel for every single reactor.

Right now, we are super focused on building our product, which I think is critically important. There are a lot of nuclear startups out there that have more than one reactor design they're working on, but they haven't built anything. So I don't think that's a healthy way to run a company. You have to have everybody focused and achieve something as soon as possible. 

That's maybe why you mentioned before that five years sounds like a short time span when it comes to microreactors. But it's not really, it can be done much faster. How fast did we make Chicago Pile-1, for example, the world's first [artificial] nuclear reactor? It was less than a year. Blue Origin's been around for 22 years, and it was only about five years ago it started flying. So that's the usual slow type of timeline we think about. But SpaceX was 4 years to rocket on [the] pad. So execution is everything.

IE: Speaking of SpaceX, how did your work towards delivering energy in space influence Radiant?

It influenced it completely. Without looking at or thinking about power in space, I never would have looked at nuclear power. Before then, I knew nothing about it and had to start at level zero.

At SpaceX, I was tasked with looking at how could you get enough power on Mars if you're going to create a colony and also give it the capacity to refuel ships allowing passengers to travel back to Earth on the next close orbit of the two planets.

I looked at doing that with solar and it's untenable. There are a bunch of miracles you need. It's a huge amount of mass that's required. A colleague of mine then mentioned that we should be looking at nuclear power, not just solar for this and I asked them to bring me a model. I upgraded my code to see how it solves the equation of how much power we need and it was just game-changing and eye-opening.

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"I think nuclear technology is required to... make a real vibrant frontier for civilization in space"

I joined SpaceX a long time ago, I was there for 12 years. I joined as a person committed to making life multi-planetary and I think that nuclear technology is required to do that successfully and create not just a little off-world colony or a base but a real vibrant frontier for civilization. One that you can travel to and back again without problem.

IE: Are there any other interesting space technologies that you believe can benefit people here on Earth?

Generally, I see it the other way around — technologies that are beneficial for Earth can also be used to unlock the potential of space. I think a lot of potential for space is in the extremely long term though after we've breached that next frontier.

So if you think about the advantages of, for example, having a colony on Mars. Mars has 1/200 of the atmosphere of Earth. So what advantages does that give us? That's very low pressure. It means that, for example, Hyperloop — which is a challenging project on Earth because you have to vacuum out all the air to remove friction — could operate much more easily on Mars. The economics would be much more favorable for that project on Mars. There are a lot of other examples of technologies developed on Earth that would work better in space.

IE: Could you tell me a recent lesson you've learned while working on Radiant's technology?

I think it's important to have a healthy level of skepticism about technology that has already been developed. I would also say pride is the way most companies fail. A very intelligent person, or group of people, can lose if they think that they've got everything going on. Hubris and pride are really dangerous and, from my experience, I would just caution people to be humble and skeptical.

Editor’s Note: This is a part of our special INTERESTING ENGINEERS ISSUE, where IE explores the greatest minds using ideas on the small scale to reshape the world on the big scale.

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