Apollo Atomics is taking a different approach to making nuclear power cheaper. Instead of designing an entirely new reactor, the startup is focusing on a less glamorous but important component of a nuclear power plant: the steam generator.
Founded by Assil Halimi and Drew Walker, Apollo Atomics believes the steam generator has been overlooked as an opportunity to reduce the size, complexity and cost of nuclear power systems.
The company recently raised $26 million in seed funding, including $5 million in debt, to develop a demonstration reactor based on research from MIT.
Its long-term goal is ambitious: to develop a nuclear power plant that can compete with natural gas on electricity costs.
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What Is Apollo Atomics Developing?
Apollo Atomics is developing a nuclear power system designed around a significantly smaller steam generator.
The company argues that existing nuclear power plants use large steam generators that are expensive, difficult to manufacture and often several stories tall.
Apollo’s approach is to redesign this component so that it can be produced more efficiently and assembled into a much more compact reactor system.
According to CEO Assil Halimi, the company believes the steam generator is one of the most important opportunities for reducing the physical size and cost of a nuclear plant.
The company’s strategy is therefore different from many advanced nuclear startups that are developing completely new reactor architectures.
Apollo wants to improve the conversion of thermal energy into electricity while retaining the advantages of nuclear fuel.
Why the Steam Generator Matters
A steam generator may not be the most visible part of a nuclear power plant, but it plays an essential role.
The reactor produces heat. That heat is transferred through the reactor’s coolant loop to another water loop, where steam is produced.
The steam then drives a turbine, which generates electricity.
Traditional steam generators use large tubes through which reactor coolant flows. Water surrounding those tubes is heated and converted into steam.
Apollo Atomics believes this traditional architecture leaves substantial room for improvement.
The company says conventional designs were heavily influenced by technology used in coal and natural-gas power plants.
Apollo’s founders argue that nuclear fuel has a much higher energy density than fossil fuels, meaning the equipment used to convert nuclear heat into electricity could potentially be made much smaller.
How Apollo Atomics’ Compact Design Works
Apollo Atomics plans to replace the large tube-based approach with a compact metal block containing extremely narrow channels.
The two fluid loops would pass through separate channels inside the block.
Because the channels are much smaller, the surface area available for heat transfer can increase relative to the size of the equipment.
This could allow heat to move between the two fluid systems more efficiently.
The result, according to the company, is a steam generator that is dramatically smaller than conventional designs.
Apollo says its version could be approximately the size of a person, compared with traditional steam generators that can occupy several stories of a power plant.
That reduction in size is central to the company’s strategy.
Apollo’s Reactor Could Be 40 Times Smaller
One of the most striking claims from Apollo Atomics is the potential reduction in reactor-system size.
The company says its compact steam generator has enabled a reactor design that is 40 times smaller than a reactor using a conventional steam generator.
A smaller system could create several advantages.
It could require less construction material, occupy less land and potentially be easier to transport and manufacture.
However, these advantages remain tied to Apollo’s ability to successfully demonstrate the technology and eventually scale it to commercial power generation.
The company is still developing its technology, so its long-term cost and performance targets have not yet been demonstrated at commercial scale.
Factory Manufacturing Could Change Nuclear Construction
Apollo Atomics is also betting on a different manufacturing model.
Traditional nuclear power plants are typically assembled extensively at their final sites.
Apollo wants to manufacture its reactor and steam-generator systems in factories before transporting them to their final locations.
The company believes factory production could reduce labour requirements and improve manufacturing consistency.
The smaller physical size of its system is particularly important to this strategy because large nuclear components can be difficult and expensive to manufacture, transport and assemble.
If Apollo’s approach works at commercial scale, factory manufacturing could potentially shorten construction schedules.
The company expects a future 300-megawatt power plant could be built in less than 24 months.
That is a major target, particularly because long construction periods are among the challenges that can increase the cost of nuclear energy projects.
Apollo Atomics Targets Three Reactor Sizes
Apollo Atomics plans to offer three different power-generation sizes.
The range is expected to start at 10 megawatts-electric and extend to 300 megawatts-electric.
This would allow the technology to target different applications and electricity needs.
Smaller systems could potentially serve specialised industrial or local energy applications, while the largest version could be used for larger electricity-generation projects.
The flexibility of different reactor sizes could also make the technology more adaptable to customers with different energy requirements.
However, the commercial viability of each size will depend on the company’s ability to prove that its compact steam-generator technology can operate reliably as the systems become larger.
Apollo Has Already Demonstrated the Technology
Apollo Atomics has already constructed a small 40-kilowatt reactor at MIT to demonstrate its technology.
The demonstration is an important step toward the company’s larger commercial ambitions.
The startup now plans to build a demonstration reactor ahead of a targeted commercial deployment in 2028.
The recently announced $26 million seed round is intended to support this next stage of development.
The funding was led by FCVC, with participation from several investors including Telesoft Partners, Y Combinator, Alumni Ventures, Robinhood Ventures, Nucleation Capital, Pelion VC, Duke Capital Partners, New Era Ventures, Orange Collective, Stanford University, E14 Fund and Neutron Power Ventures.
Apollo Atomics was also part of Y Combinator’s Spring 2026 batch. Y Combinator’s Apollo Atomics profile
The Company Has an Ambitious Cost Target
Apollo Atomics CEO Assil Halimi has said the company is targeting an electricity-generation cost of approximately 3 cents per kilowatt-hour.
The startup wants to compete directly with natural gas.
That is an ambitious objective because nuclear projects have historically faced high construction costs, long development timelines and complex regulatory requirements.
Apollo’s argument is that shrinking one of the largest components of the system could address several of these challenges simultaneously.
A smaller steam generator could reduce material requirements.
Factory manufacturing could reduce construction labour.
A smaller reactor could potentially simplify transportation and installation.
Together, those changes could potentially lower the overall cost of a nuclear power plant.
Why Smaller Nuclear Reactors Are Attracting Attention
The broader nuclear industry is experiencing renewed interest as governments and companies look for reliable sources of low-carbon electricity.
Advanced nuclear startups are developing technologies intended to improve safety, efficiency and affordability.
Small modular reactors are particularly interesting because they can potentially be manufactured in standardised facilities rather than constructed entirely on site.
Apollo Atomics fits into this broader movement, but its strategy focuses heavily on the balance-of-plant technology surrounding the reactor rather than simply redesigning the reactor core.
That distinction is central to the company’s pitch.
Apollo’s Approach Is Different From a Conventional Reactor Redesign
Many nuclear startups are trying to develop new reactor concepts.
Apollo Atomics is instead asking whether existing nuclear technology can become significantly cheaper if the equipment around the reactor is redesigned.
The steam generator is therefore the centre of the company’s strategy.
The startup believes that improving heat transfer and dramatically reducing the generator’s physical size could make the entire nuclear system more compact.
The approach could also make factory production more practical.
If the technology can be demonstrated successfully, Apollo’s concept could offer another route toward reducing nuclear construction costs.
What Challenges Remain?
Apollo Atomics still faces significant challenges before its technology can become a commercial power source.
The first challenge is proving that the compact steam generator can operate reliably under the demanding conditions associated with nuclear power.
Scaling is another major issue.
A technology that works at 40 kilowatts must demonstrate consistent performance when scaled toward a 300-megawatt commercial plant.
Regulatory approval will also be essential before any commercial nuclear deployment can proceed.
Manufacturing at scale presents another challenge. Apollo’s cost assumptions depend partly on factory production, meaning the company will need to demonstrate that its components can actually be manufactured repeatedly and economically.
These challenges do not invalidate the company’s approach, but they highlight the gap between an attractive engineering concept and a commercially deployed nuclear power plant.
What Comes Next for Apollo Atomics?
The immediate priority is developing the planned demonstration reactor.
Apollo Atomics is targeting commercial deployment in 2028, although that timeline will depend on successful technical development, testing, manufacturing and regulatory progress.
The company’s new funding provides capital to continue that development.
If Apollo can demonstrate that its compact steam generator delivers the expected efficiency and reliability, it could strengthen the case for a smaller and more factory-oriented model of nuclear power construction.
The company’s next major milestones will therefore be closely watched by investors and the wider nuclear industry.
Final Takeaway
Apollo Atomics is taking an unusual route toward cheaper nuclear power.
Rather than focusing entirely on a new reactor design, the startup is targeting the steam generator, an essential component responsible for transferring heat and producing the steam that ultimately drives a turbine.
Its compact design uses narrow channels inside a metal block to improve heat transfer while dramatically reducing the component’s physical size.
Apollo believes the approach could make nuclear plants smaller, easier to manufacture in factories and substantially cheaper to build.
The company has already demonstrated the technology at a small scale and is now working toward a larger demonstration reactor.
Its ambitions are significant, with plans for systems ranging from 10 MW to 300 MW and a target electricity cost of around 3 cents per kilowatt-hour.
Whether those targets can be achieved remains to be demonstrated. But if Apollo Atomics succeeds, its focus on an overlooked part of the nuclear power system could provide an interesting new path toward more affordable nuclear energy.
