To achieve the goals set out in the Paris Agreement, governments and corporations are scrambling to find sustainable ways to generate power. While renewable energy sources have seen remarkable efficiency improvements, they have major drawbacks that make them unsuitable for decarbonizing some energy generation applications.

Renewable energy grew from accounting for 12% of US electricity generation in 2012 to 23% in 2022. However, renewable energy, which draws on forces of nature like sunshine and wind, can be susceptible to disruption, making it unreliable. Both the frequency and duration of blackouts in the US have increased from 2013 to 2021.

Their potential unreliability makes renewables an unsuitable source of non-fossil fuel power generation where a stable supply of electricity is essential, or in places that cannot rely on grid backup. Examples include remote communities, military bases, research centers, or post-disaster scenarios. In the past, the solution for such places was diesel electricity generators. In some areas, such as sub-Saharan Africa, diesel generators produced up to 40% of the total power supply as of 2023. An average generator, however, emits 2.2X more CO2 per unit of energy than the US grid and emits fumes that can cause major adverse health effects, including lung cancer.

At the same time, nuclear power is experiencing a renaissance, and its public support is growing. Nuclear power plants can be a stable and reliable source of energy supply. US nuclear reactors operate at full power a minimum of just over 86% of the time and a maximum of over 92%. In 2023, 57% of Americans said they support nuclear power, compared to just 43% in 2020. In 2022, $5 billion was invested into a new generation of fission power startups.

However, traditional nuclear fission has many problems which prevent it from scaling efficiently. The industry is plagued by long development cycles, delays, and cost overruns, making some projects unviable economically. For example, the construction of the Vogtle 3 and Vogtle 4 nuclear plants saw delays of over seven years and cost overruns of over $15 billion, doubling the original budget. Similar to how SpaceX changed the aerospace industry by lowering launch costs with innovation, nuclear startups have an opportunity to change this by creating more efficient methods of providing nuclear energy supply.

Radiant builds portable nuclear microreactors that are intended to replace diesel generators in “remote villages” and to provide “resilient backup power for hospitals, data centers, and military installations. The Kaleidos, Radiant’s first product, is designed to produce 1.9 MW of thermal power “for facility heating or water desalination”, and generates 1M of electric power. It is also designed to fit in a shipping container for ease of transport.

Radiant’s mission is to create clean alternatives to off-grid power solutions and replace all diesel power generators. Applications include military sites, disaster relief, and other off-grid use cases. With a unique engineering approach building on the team’s experience at SpaceX, Radiant is planning to be the first new commercial reactor to achieve a fully-fueled test in more than 50 years with the test of its development reactor at Idaho National Lab in 2026.

Radiant was founded in 2020 by Doug Bernauer (CEO) and Bob Urberger (CTO).

Bernauer studied Electrical Engineering at Case Western Reserve University and later joined SpaceX as an R&D engineer in 2007. He describes SpaceX as an experience that shaped his approach to engineering and company-building as follows:

During his 12 years at SpaceX, Bernauer worked on a variety of R&D projects, including leading avionics development for the Grasshopper, the first SpaceX rocket. Bernauer then worked on a variety of ”Elon's side-projects”, including the Hyperloop and The Boring Company. One of these projects was finding the best way to generate energy for a potential SpaceX Mars colony:

At first, Bernauer focused on investigating ways to use solar power, as it is theoretically the most cost-efficient way of generating power. But he quickly realized that generating the necessary amount of power would take about “three football fields worth of solar panels”, which was an inefficient use of space. This led him to investigate other options. A colleague suggested he should simulate powering a colony with nuclear fission. In this process, Bernauer found that small modular nuclear reactors (SMRs) were a solution that didn’t suffer many of the drawbacks of solar.

Along with a number of other SpaceX engineers, Bernauer built “a power model based on nuclear, [using] code to run a trade study.” Bernauer became obsessed with learning about nuclear technology and the dynamics of the nuclear market. He quickly realized that if efficient nuclear reactors could power Mars colonies, they could also provide abundant, reliable, and cheap power on Earth. He started to form the vision for Radiant as a result:

Bernauer recruited several colleagues from SpaceX, including Urberger, with whom he collaborated on the Grasshopper project, to learn more about the potential applications of SMRs. The duo began collaborating with top scientists at the Argonne and Idaho National Labs and they found SMRs as a cost-effective, climate-friendly alternative to diesel generators.

Then, in 2019, the Department of Defense issued a call for the design of a small, portable nuclear reactor for military use that could fit in a shipping container. The pair saw this as an opportunity to commercialize their efficient SMR idea, with a stable revenue and regulatory pathway from the military. Bernauer and Urberger left SpaceX and founded Radiant the same year.

Since then, Radiant recruited several key colleagues from SpaceX, as well as nuclear industry experts. The team they formed is experienced in both aerospace and nuclear engineering, leaning on their combined time at SpaceX, McMaster-Carr, and various leading US national laboratories and research facilities. The key hires included Roger Chin (Radiant’s Software Architect and a former SpaceX colleague), Ben Betzler (Director of Nuclear Engineering, previously a researcher at Oak Ridge National Laboratory), as well as, Steve Burns (board member, former NRC Comissioner).

Radiant’s flagship product is the “Kaleidos”, a portable nuclear fission microreactor capable of generating 1.9 MW of heat energy, or 1MW electric power. The reactor is still in its R&D phase, with commercialization planned for 2028.

Small Modular Reactors (SMRs)

A conventional nuclear reactor in the US generates about 1K MW of power. SMRs are smaller reactors generating up to 300MW of power, using advanced technology to optimize operation. They can be thought of as safer, easier to install, and more affordable than conventional reactors. While no SMRs are yet connected to the grid, China and Russia began building the first SMR plants in remote locations without access to the grid.

Microreactors are an even smaller type of reactor, designed for mobility and speed of deployment, in addition to efficiency.

Source: International Atomic Energy Agency

The Kaleidos

While conventional reactors are deployed at fixed locations, the Kaleidos is being built to be fully portable. As described by Bernauer, it’s designed to fit in a shipping container ”8 x 20 [feet], 9-and-a-half-feet high” that can be transported by air, ship, and road.

Bernauer has claimed that the on-site setup of the reactor will be able to be conducted overnight without relying on heavy infrastructure. Portability will therefore be the defining feature of the Kaleidos. Bernauer noted that while Radiant can build modular systems of reactors, the key to their reactor’s deployment is unprecedented mobility.

Source: Forbes

The Kaleidos will have an operating life of 20 years and will require refueling every five years. After that five-year period, the core of the reactors will be refueled at the Radiant factory, ensuring streamlined and secured nuclear waste management.

The Kaleidos is a high-temperature gas-cooled reactor (HTGR). It will use TRi-structural ISOtropic (TRISO) fuel and a helium coolant. The reactor will produce heat through a controlled fission chain reaction in a graphite-moderated core. Conventional reactor designs use a steam Rankine cycle for power conversion, using water to transfer that heat into power. Radiant opted for a CO2 closed-loop Brayton Cycle power conversion system, which will enable the use of a smaller turbine with a comparable power rating. Using helium and the Brayton cycle also eliminates the need for a constant water supply, allowing Radiant to deploy the reactor anywhere without the need for continuous maintenance.

Source: USV

Moreover, using a helium coolant reduces the risks of corrosion, building, and contamination. The helium coolant ensures heat dissipation which will prevent a meltdown even if the reactor is suddenly shut down, improving safety. To ensure safety, the cooling system will be fully fault-tolerant, meaning “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”. This is ensured by redundancy built into the system, using techniques borrowed from the team’s experience in rocket and spacecraft design.

Autonomous Operation

A key feature of the Kaleidos is autonomous and maintenance-free operations. This will enable Kaleidos reactors to be deployed at remote sites without continuous oversight. The reactors will be operated autonomously as a fleet by Radiant’s software platform. Operating the reactors as a fleet will allow Radiant to optimize operations through big data analytics, as Bernauer put it in a January 2023 blog post:

This approach is intended to enable operational efficiencies and streamline safety and regulatory monitoring. As of August 2023, the US had 93 operating commercial nuclear reactors at 54 nuclear power plants across the US. These lack standardization, preventing them from sharing data. Radiant hopes to drive new safety reporting standards for the whole industry, thanks to its software platform:

TRISO Fuel

The Kaleidos will use a TRi-structural ISOtropic (TRISO) particle fuel. Each of the small TRISO particles (the size of a poppy seed) is comprised of uranium, oxygen, and carbon covered by ceramic and carbon materials.

Radiant’s fuel particles are coated in multiple layers of graphite and silicon carbide, a non-porous material that keeps all fission gases inside each pellet and prevents potential breaches. In the Kaleidos, the TRISO particles are formed into large cylinders, rather than conventional rods, further decreasing the risk of a breach. TRISO fuel is a well-tested material. As explained by Bernauer in 2020:

Engineering Approach

Source: Radiant

Radiant is focused on developing one reactor design as quickly as possible. Drawing from SpaceX’s development process, a key factor in Radiant’s engineering process is proprietary digital twin technology. This is developed in-house and custom to its processes. The digital twin software, which the company calls SimEngine, fuses reactor digital twins with aerospace-derived hardware and simulators across a range of operating conditions.

This SimEngine can couple software with physical components, allowing Radiant to test how a different physical design of a component (a physical prototype) will interact with the whole reactor, as well as foresee any potential failures. The company claims this to be the “first-of-its-kind” approach in the nuclear industry.

Customer

The Kaleidos is designed to be a sustainable alternative for any customer using diesel generators. One fuel load of the Kaleidos (lasting about five years) will allow customers to eliminate the need for about four tons of diesel fuel. Consequently, each Kaleidos will offset about 22K tons of diesel fuel and associated CO2 emissions. In October 2023, Bernauer, the CEO of Radiant, explained:

One key customer of Radiant may be the US military. Remote military bases are dependent on a stable, reliable supply of power. They currently rely on diesel generators which creates major logistical challenges. Generators require constant land shipments of fuel, which adds significant operating costs and security risks.

A 2018 US Army report estimated that over nine years during the Iraqi Freedom and Enduring Freedom operations, about half of the 36K casualties occurred from hostile attacks during land-transport missions including refueling missions. Each Kaleidos could save the army over 22K tons of diesel fuel that won’t need to be transported.

After awarding Radiant a grant in 2023, the Department of Defence’s (DoD) Operational Energy Capability Improvement Fund (OECIF) also sees the potential in potential battlefield applications:

Other use cases for potential future customers of Radiant include communities, municipalities, research centers, or data centers looking for remote power, disaster relief, or micro-grids.

Remote Power Generation: Remote areas and communities separated from the electricity grid, such as research centers, face challenges similar to military bases. They also need a stable, reliable supply of power (particularly in harsh environments like Antarctica) and face the same logistical challenges as army bases with receiving constant fuel shipments in adverse circumstances

Disaster Relief: Many disasters cut large areas off from the electric grid. In case of sudden disasters like hurricanes or earthquakes, the Kaleidos’s fast set-up speed could make it a suitable replacement for diesel generators in supplying areas that have lost power. In slow-moving crises, like droughts, the Kaleidos can provide over 1.9MW of thermal power for heating or desalination in addition to generating electricity.

Micro-Grids: Long-term applications of Radiant’s technology might include modular reactor systems to power small electricity grids. The electricity grid faces significant long-distance transmission pressures from renewable energy generation. The future of the grid may be a decentralized network of small, local grids. A modular system of Kaleidos reactors could be well suited for powering such microgrids or providing backup power to complement renewables. The Kaleidos could also be well-suited for decarbonizing energy-intensive industrial and manufacturing processes, with cost-effective power.

Transport Applications: Radiant’s reactors could also see applications such as powering charging stations along highways, as well as powering propulsion systems such as spacecraft.

Market Size

As of 2024, it’s estimated that there are around 100 million diesel generators in use around the world. The global market for diesel generators was estimated to be worth $15.8 billion in 2024 and is projected to grow to $20.5 billion by 2029, representing a 5.4% CAGR. Replacing those diesel generators is the immediate addressable market for the Kaleidos.

In the long term, Radiant’s market potential might include other power generation applications. Energy consultants Wood Mackenzie have noted that:

Global electricity demand is expected to increase by 60% between 2024 and 2040, from around 30K TWh in 2024 to around 48K TWh in 2040. The International Energy Agency estimates that over 70% of this new energy capacity, or over 12 TWh, will need to be delivered by off-grid solutions. Assuming the average price of energy in renewable energy PPEs of $50 per MWh, this would give Radiant a potential TAM of over $600 billion.

Small Modular Reactor (SMR) Developers

X-Energy: X-Energy is an SMR development company founded in 2009. X-Energy is developing a gas-cooled microreactor using TRISO fuel, using a proprietary nuclear fuel technology called TRISO-X. It is targeting industrial use cases and secured a joint development agreement with Dow, to demonstrate “the first grid-scale advanced nuclear reactor for an industrial site in North America”.

Source: X-Energy

The company has raised a total of $285.2 million in funding as of May 2024. In December 2023, it raised a $235 million Series C at an undisclosed valuation. In late 2023, the company called off a SPAC with Ares Management Corporation, which would have valued it at $2 billion.

Oklo: Oklo is a nuclear technology startup founded in 2013. As of July 2023, the company was planning to go public via a merger with AltC Acquisition Corp (SPAC) at a $850 million pre-money valuation. Oklo is pursuing two tracks towards commercialization: building modular SMR power plants (targeting a reactor size between 15 and 50MW) and nuclear fuel recycling services. The company has secured a site permit from DOE and a fuel award from INL for a commercial fission power plant in Idaho which is planned to go online in 2026 or 2027.

Source: Oklo

Seaborg Technologies: Seaborg Technologies is an off-shore SMR developer founded in 2014. Seaborg is developing low-enriched-uranium microreactors to float on off-shore barges to reduce nuclear safety risks. It’s planning a modular system connected to the electricity grid, with each barge having one SMR producing up to 800MW of electricity with a lifetime of 24 years. The company is planning to produce commercial prototypes of its reactor by 2024 with serial production in 2026 and secured a letter of intent from Norwegian national utilities to investigate using its reactors.

Source: Seaborg Technologies

Seaborg Technologies has raised total funding of $28.5 million. In 2020, it raised a Series A, estimated at around $20 million from an undisclosed group of investors at an undisclosed valuation.

Last Energy: Last Energy is an SMR developer founded in 2020. Last Energy is developing a 20MW pressurized water microreactor and is focused on efficiently “packaging” conventional nuclear technologies to offer attractive unit economics. It uses mostly off-the-shelf parts with modular construction, intended to keep engineering costs low. It had secured eight customers across three EU countries for a total of 51 microreactors as of October 2023, with the first launch planned for 2026. The company raised a total of $24 million as of July 2023 from investors such as Gigafund, David Marquardt, and Luke Nosek, and has reportedly signed nuclear power deals in Europe worth $25.6 billion.

Source: Last Energy

NuScale Power: NuScale is an SMR company founded in 2007. NuScale developed the first SMR certified by the NRC. The company is planning to begin operating a reactor in Idaho by 2030. It announced a deal to supply Standard Power with 1.8MW of power using 24 SMRs to power two data centers. However, the viability of the deal has been called into question. It is a public company with a market cap of $1.5 billion as of May 2024.

Source: Business Wire

Incumbents

Westinghouse Electric Company: Westinghouse Electric Company is owned by Brookfield Business Partners. The Canadian company is a leader in the nuclear development industry and has developed the Vogtle plant Units 3 and 4, a conventional nuclear reactor project in the US. As of April 2024, the company is developing the Westinghouse AP300 SMR and is planning to begin commercial operation in the early 2030s. Westinghouse secured an agreement with Community Nuclear Power to deploy the Westinghouse AP300 in the UK.

Rolls-Royce: Rolls-Royce has an SMR division which is part of a Rolls-Royce conglomerate. It secured a collaboration to develop nuclear reactors in the Netherlands and is on track to receive approvals from the UK regulator.

As of May 2024, Radiant is still in its R&D phase, with a commercial launch planned around 2028. The company is most likely to use the price-purchase agreement (PPE) model used by most other SMR developers, as well as most renewable energy projects. PPEs are contractual commitments from customers to purchase a certain amount of electricity at a certain price.

Last Energy, a Radiant competitor that uses a PPE model, is estimated to charge its customers between $130 to $200 per megawatt-hour of generated energy for its most lucrative agreements. This is more than most renewable energy sources, with solar PPE rates often as low as $50 per megawatt-hour. Nuclear costs, however, are expected to come down rapidly as the technology matures.

As of May 2024, Radiant is still in its R&D phase and has not achieved any commercial traction yet. However, it follows an “anti-stealth” philosophy and the team is very transparent with the roadmap and milestones towards commercialization.

Radiant’s main target is a fully-fueled reactor test at Idaho National Laboratory’s (INL) new Demonstration of Microreactor Experiments (DOME) facility by 2026. Bernauer estimates that the first commercial reactor will be available within two years of that test, aiming for commercialization in 2028. In October 2023, Radiant secured that testing timeline with the Department of Energy (DOE), which chose Radiant as one of three microreactor developers that will design the first experiments at INL’s DOME facility, foreseen for 2026. As explained by Bernauer in October 2023:

Bernauer elaborated that the test will produce data “with real rather than simulated fuel, and proof of operations of all safety-critical components, allowing for reduced uncertainty in licensing for commercial units.”

Radiant also secured a number of collaborations with research and government agencies. In 2023, the company received a voucher from DOE’s ANL Laboratory. This award will give Radiant access to research capabilities and expertise at ANL, including work on numerical modeling of heat production and removal.

In 2023, the company received a Small Business Innovation Research award from the DoD. As a part of that partnership, Radiant will develop base modeling and simulation capabilities for key energy resilience scenarios at Hill Air Force Base. Radiant and Hill AFB will simulate how Kaleidos reactors would provide critical heat and power alongside the base’s system of existing generators, proving the viability of its reactors for the military. The program will culminate in a demonstration of base energy management simulation planned for 2025.

As of May 2024, Radiant has raised a total of $53.8 million from investors including Andreessen Horowitz, Founders Fund, Decisive Point, McKinley Alaska, Draper Associates, Cantos, and BoostVC. In April 2023, it raised $40 million Series B at an undisclosed valuation. The company will use the funds to establish its microreactor factory and build its first five microreactors.

Radiant also received an estimated $2.3 million in government grants, as well as a $3.8 million award from the Office of the Under Secretary of Defense’s Operational Energy Capability Improvement Fund (OECIF). Radiant’s work with the OECIF includes delivering a compact CO2 cycle turbine-alternator-compressor, to shrink the footprint of of battlefield power solutions.

For comparison, NuScale, a publicly-traded SMR developer, was trading at around 42x revenue multiple as of April 2024.

Source: Koyfin

Grid Outages

Grid outages are becoming increasingly frequent, and blackouts are longer lasting. Between 2013 and 2021 the number of minutes of grid outage per customer in the US increased from about 210 minutes to over 400 minutes on average.

Source: Scientific American

Radiant’s microreactor design is specifically designed for deployment as a backup, emergency power system during a grid outage or natural disaster. Its rapid deployment, portability, and modularity make it perfectly suited to address such crises, as a reliable replacement to traditional backup generators. The increasing number of extreme weather events will likely increase the demand for a reliable power solution like the Kaleidos.

Military Modernisation

The US military is increasingly recognizing a need to adapt technology to increase innovation and resilience. Geopolitical tensions and conflicts have highlighted the importance of modern technology in military applications and companies like Anduril are paving the way for military cooperation with innovative startups. The value of military contracts awarded to startups has increased by about $4 billion between 2010 and 2023. VC investment into US defense-technology startups has also increased from $30 billion in 2016 to over $100 billion in 2023, showing the potential of the sector.

Radiant’s microreactor technology is well-suited for military applications, such as remote bases or military vehicles, to increase energy security and resilience. The Kaleidos’s 20-year operating lifespan and maintenance-free operations make it an attractive alternative to diesel generators in sensitive applications. Radiant received an SBIR award from the Department of Defense and is actively working to demonstrate the potential of its technology for applications with the Air Force. It’s also collaborating with OECIF, to develop a power conversion system for operational military applications. Representatives from the OECIF have recognized the potential of Radiant’s technology to be applied on the battlefield.

Regulatory Catalysts

In 2023, 57% of Americans say they support nuclear power, compared to 43% in 2020. This shift in public opinion has been reflected in government policy. The Inflation Reduction Act (IRA) created a number of incentives for nuclear companies. This includes tax credits for nuclear power companies as zero-carbon energy sources.

In February 2024, Congress also approved bipartisan legislation to speed up environmental reviews of nuclear reactors, limit liability for accidents, and streamline the licensing process. The NRC is also recognizing the need for nuclear innovation and taking steps to significantly simplify the licensing of SMRs. The regulator created dedicated review teams for advanced reactors and “engaged with the nuclear industry to develop a technology-inclusive, risk-informed, and performance-based approach for assessing advanced reactor applications."

These changes could make it significantly easier for advanced nuclear companies, like Radiant, to gain necessary regulatory approvals and find suitable financing schemes for developing commercial projects.

Regulatory Obstacles

While Radiant has entered pre-application with the NRC as of May 2024, there is a risk that Radiant’s regulatory approval process might delay its commercialization timeline or fail altogether. The average review process for new reactors necessitates between three and eight years from the start of the review to the beginning of construction. Any regulatory delays or hurdles could put Radiant’s commercialization timeline at risk.

However, the safety risks of Radiant’s reactor designs have been estimated to be relatively low for a new, advanced reactor design. Todd Allen, from the University of Michigan, has compared the safety risk of Radiant’s design to the risk of the miniature reactors used by universities across the US for teaching and research purposes.

Radiant’s team also developed a novel reporting mechanism that could help streamline its approval process thanks to additional transparency measures. Using its fleet-management software, the company will be able to collect detailed data and continuously report the performance of its microreactors to the regulators. Such novel safety monitoring capabilities could give the NRC more confidence to approve Radiant’s designs on its tight commercialization timeline.

Technological Risks

As Radiant is developing an advanced reactor design, there are inherent technological risks involved. The company has not yet tested its reactor designs using nuclear fuel. However, the technological risks could be mitigated by relying on proven technology and a transparent development process. As explained by Bernauer, Radiant works in “anti-stealth” as a reaction to the stories of hardware companies like Theranos. Both the HTGR reactor type and the TRISO used by Radiant have been operational in reactors for over 50 years. Its digital-twin engineering approach should also make the company’s design predictable in silico.

Nevertheless, a risk of Radiant not delivering on its ambitious development timeline remains. There are also risks of the Kaleidos not delivering the desired unit economics, making commercialization unviable. Last Energy, one of Radiant’s competitors developing advanced reactors, estimated the cost of its energy at $130 to $200 per megawatt-hour. This is significantly more than the cost of solar power, the most cost-efficient option, which can be as little as $50 per megawatt-hour. An inability to deliver the planned efficiency savings could compromise the commercialization of Radiant’s technology.

An increase in nuclear power generation could be essential to meeting growing global demands for energy. While becoming cost-effective, renewable energy sources have drawbacks, such as lack of reliability, that make them unsuitable for some applications. Founded by ex-SpaceX engineers, Radiant is developing a portable microreactor that can be rapidly deployed in remote locations, or in disaster areas. Although Radiant is in the R&D phase, it aims to achieve a fully-fueled demonstration of its reactor by 2026 and commercialize the technology by 2028. The success of its technology will depend on the company’s ability to gain regulatory approvals, deliver on its development milestones, and maintain cost efficiency.