May 31, 2024 · 45m · sourcery
Radiant CEO Doug Bernauer on Portable Nuclear Microreactors & the Future of Clean Energy · Sourcery with Molly O'Shea
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gold bands on the timeline = statements, start to end. Hover to read, click to jump. CC turns on captions
In this episode of Sourcery, host Molly O'Shea interviews Radiant Founder and CEO Doug Bernauer about his company's mission to build portable, factory-manufactured 1MW nuclear microreactors. Bernauer discusses his engineering background at SpaceX, the passive safety physics of TRISO fuel, regulatory challenges, and Radiant's target to execute the first full-scale US reactor test in 50 years by 2026.
How this conversation actually went
Every chapter scored 0–10 on four independent dynamics. Hover any point for the reasoning behind the score. Molly holds 14.1% of the talking time here. How this is scored →
Molly as informed peer 2.4 Guest teaching 3.3 Guest disagreement 0.2 Molly pushing back 0.0
speaking balance: gold is Molly, purple is the guest (3 minute bins)
Sharpest disagreement ▶ 25:59 Doug reframes vertical integration assumption
Doug politely rejects Molly's premise that Radiant is vertically integrated, clarifying that their preferred strategy is off-the-shelf integration wherever parts exist.
Hardest push from Molly ▶ 22:44 Molly challenges on generational knowledge lossMolly presses Doug on whether decades of stagnation produced a systemic generational gap in technical expertise within regulatory and legislative institutions.
Biggest teaching moment ▶ 38:25 Physics of passive thermal reactor shutdownDoug provides an in-depth physics explanation of negative thermal coefficients of reactivity, showing how rising temperatures inherently shut down fission without human intervention.
Molly holds their own ▶ 25:25 Molly references hands-on digital twin testingMolly cites her direct experience operating Radiant's in-house digital twin simulator at the facility, describing specific failure parameters and thermal responses.
the scores for every segment, with the reasoning behind each
| Chapter | Topic | Molly as informed peer | Guest teaching | Guest disagreement | Molly pushing back | Why |
|---|---|---|---|---|---|---|
| Sourcery Podcast Title Sequence | 2 | 1 | 0 | 0 | Molly introduces Radiant's funding rounds and welcomes Doug, setting an open and supportive stage by asking about his extensive SpaceX background. | |
| Assembling the Engineering Team at Radiant | 2 | 2 | 0 | 0 | Molly asks about the engineering talent Doug assembled from SpaceX and elsewhere. Doug elaborates on co-founder Bob and hiring across naval and aerospace domains. | |
| Founding Radiant and the Kaleidos Microreactor Concept | 2 | 3 | 0 | 0 | Doug outlines the origins of Radiant through the DoD Pele program and Mars colonization studies, explaining the concept of factory-mass-produced 1MW portable microreactors. | |
| TRISO Fuel and High Temperature Gas Reactor Safety | 3 | 4 | 0 | 0 | Molly asks about TRISO fuel. Doug explains the physics of ceramic-coated poppy-seed-sized particles, helium cooling, and the structural impossibility of a meltdown. | |
| History and Stagnation of Nuclear Energy in the US | 2 | 5 | 0 | 0 | Doug delivers an extensive historical breakdown from Enrico Fermi to Eisenhower's Atoms for Peace, Rickover's submarine reactors, and the stagnation of US nuclear construction after the 1970s. | |
| Public Sentiment Shifts and Regulatory Modernization | 2 | 4 | 1 | 0 | Molly asks why the nuclear industry lagged behind renewed public enthusiasm. Doug explains congressional bipartisan support and reframes the NRC's role as accommodating rather than obstructive. | |
| Overcoming Manufacturing Gaps and Radiant's 2026 Fuel Test Target | 3 | 3 | 0 | 0 | Molly asks whether a generational gap in expertise exists in regulatory and legislative bodies. Doug agrees while emphasizing Radiant's commitment to a 2026 fueled test. | |
| Reactor Scaling, Supply Chain Openness, and Digital Twin Simulation | 3 | 4 | 1 | 0 | Doug gently clarifies Molly's assumption about vertical integration, distinguishing Radiant's 1MW portable design from traditional multi-hundred megawatt SMRs and detailing open industry specs. | |
| Cost Efficiency of Microreactors vs. Large Nuclear Plants | 3 | 3 | 0 | 0 | Molly asks about financial requirements and comparisons to gigawatt plants. Doug contrasts multibillion-dollar capital requirements with tens of millions for microreactors and recaps Radiant's funding. | |
| Off-Grid Applications, Alaska Deployment, and Micro-CHP Benefits | 3 | 4 | 0 | 0 | Doug details market use cases in remote Alaskan communities and mining sites, highlighting diesel replacement, micro combined heat and power, and rapid two-day deployment. | |
| Physics of Inherent Reactor Safety and Human Error Reduction | 2 | 5 | 0 | 0 | Doug breaks down the physics of negative thermal reactivity coefficients and passive shutdown mechanisms that prevent meltdowns even when operators walk away. | |
| Recruitment Strategy and Radiant's El Segundo Headquarters | 2 | 2 | 0 | 0 | Molly inquires about hiring and upcoming milestones, and Doug describes the testing cadence at their El Segundo facility leading up to 2025 assembly. |
Statements from this episode (21)
Bernauer spent 12 years at SpaceX after consecutive launch failures
“Yeah, I spent 12 years at SpaceX had joined when they had failed two rockets in a row but I thought it was just a big and beautiful mission to lower the cost of launch, to make life multi-planetary and that's why I did that for 12 years, but I worked on all so…”
Bernauer began researching nuclear power while designing SpaceX Mars systems
“But I also worked on Hyperloop and on the boring company, kind of ideas that came from that while I was there and on Mars systems, which is how I started to look at nuclear.”
Bernauer: Making life multi-planetary requires nuclear technology to succeed
“The mission of making life multi-planetary It needs to have nuclear technology for that to really blossom and to succeed”
Bernauer: Microreactors can be factory-built at 50 units per year
“You can make a one megawatt reactor that is factory constructed, 50 units a year, so a reactor every week coming off the line, and then you can transport that by land, sea, or air to any place in the world.”
Radiant microreactor contains 120 million poppy seed-sized ceramic fuel kernels
“What we're doing is these tiny poppy seed size kernels of fuel. There are about a hundred and twenty million of them. For a hundred kilograms of uranium and this is all in a core that's, you know, only four feet in diameter.”
Ceramic-coated TRISO nuclear fuel cannot melt down up to 1600°C
“The temperature limit of the fuel becomes this extremely high value, and you can go to about 1600 Celsius before there's an appreciable failure rate of the ceramic coated fuel. So what it means is you can't melt down the fuel.”
Helium gas coolant cannot absorb neutrons or become radioactive
“We use helium gas because it can't become radioactive either. And it's a gas. It can't actually absorb a neutron, which is what makes something radioactive when it starts out not being radioactive.”
US gigawatt-scale nuclear reactors are derived from a 1950s design
“And that's why today we have, I think the number is about 93 operating gigawatt scale light water reactors. They're all based on that one design from that moment in time, way back when.”
No new nuclear reactor design has been fueled in 50 years
“There's no new nuclear design that has been fueled in the U S in the last 50 years.”
Bernauer: The Nuclear Regulatory Commission is not blocking nuclear innovation
“The way I see it, the NRC are not really blocking things.”
Bernauer predicts multiple nuclear entities will conduct fuel tests in 2026
“And I think others are going to do that same thing in that same year. So it won't even be just us. It'll be several different entities.”
Radiant microreactors meet NRC radiation limits outside a 35-foot perimeter
“We are down at one megawatt, so enough power for 1000 homes. And we can mass produce these in a factory, deliver them to a site, and with no infrastructure just outside of a 35 foot fence line, you can operate them and be at the NRC public dose limit for a rea…”
Radiant will publicly release nuclear-grade graphite test results to qualify suppliers
“So we are testing nuclear grade graphite right now. We actually will make the results of that available to everyone. So it will just qualify a U S domestic American made nuclear grade graphite supplier to a higher degree”
Radiant microreactors cost tens of millions versus billions for conventional reactors
“So the, I mean, the really big ones that we have now are on the order of a few billion dollars for reactor. A tiny little one that I'm working on is on the order of tens of millions of dollars, but you know, everyone's design is quite a bit different, but it's…”
Radiant has raised about $60 million from a16z and USV
“And then we raised a series A with Union Square Ventures in 20, 22. And then a little over a year ago, we did a series B with Andreessen and raised a forty-five million dollar round. So when you add all that up, we've raised about sixty million in total ventur…”
Radiant has won seven government contracts totaling approximately $8.7 million
“We have also won, I want to say it's seven government contracts at this point. And that totals about 8.7 million. And no other forms of financing.”
Radiant's Kaleidos microreactor can become operational within two days on site
“With a reactor like this, that can be quickly moved and doesn't need a lot of infrastructure. You can be operating it in about two days after getting it on a site, which means you can use it for disaster relief.”
Uranium's negative thermal coefficient automatically shuts microreactors down if cooling fails
“If that helium pump fails, the system will start to heat up. And as it heats up, it doesn't even need to heat up very much. It heats up a little bit. The reactor goes subcritical and shuts itself off. And this is
this is true for most reactor technologies bec…”
German operators proved safety by leaving overheating nuclear reactor unmonitored overnight
“There's a HTGR reactor in Germany, AVR, where the operators would actually just leave the operating room, And allow the system to overheat and they would leave it and leave it overnight in that state and then come back and then start operating the next day.”
Radiant plans to fundraise in summer 2024 before first reactor test
“We are going to fundraise again pretty soon this summer. It'll be the last time to invest before the first reactor in 50 years gets fueled and tested”
Bernauer predicts Radiant will complete and ship a reactor in 2025
“Twenty-twenty-four will be the last year that we're playing around with the analysis paralysis and the design and answering all the questions, the regulator and simulating things in the twin. And twenty-twenty-five is going to be actually building the thing up…”