The Nuclear Reactor That Fits in a Shipping Container
Microreactors are nuclear fission reactors with electrical output capacities below approximately twenty megawatts, designed for factory fabrication, transport to site by standard shipping methods including truck, rail, or aircraft, and operation without the on-site operating staff, cooling water infrastructure, and safety system complexity that conventional nuclear power stations require. Their design philosophy represents a fundamental departure from the nuclear industry's historical scaling logic, which produced the gigawatt-scale nuclear plants whose economies of scale in capital and staffing cost per kilowatt-hour of electricity generated made large nuclear plants economically competitive for centralised grid electricity supply, in favour of the factory fabrication economies and distributed deployment flexibility that small, standardised nuclear units provide for the off-grid and remote applications where conventional grid electricity infrastructure does not exist and whose energy supply from diesel generation creates the high costs and logistical complexity that microreactor developers believe nuclear heat and electricity can displace at commercially competitive total system cost. The applications that microreactors are designed for, including remote mining and resource extraction operations, Arctic and island communities, military forward operating bases and installations, and the industrial heat applications whose high-temperature process heat requirements are difficult to supply from renewable sources, share the characteristic of being geographically isolated from reliable, affordable conventional energy supply in a way that makes the high capital cost of nuclear infrastructure more competitive than it would be against grid electricity.
The microreactor market is in its earliest commercial phase in 2026, with multiple technology developers having received regulatory engagement from the US Nuclear Regulatory Commission and international counterparts but with commercial deployment limited to demonstration programmes and initial small-order contracts rather than the repeat commercial orders that would signal market validation. The US Department of Defense's Project Pele programme, which demonstrated a transportable microreactor for forward operating base deployment at Idaho National Laboratory in 2024, and the Department of Energy's National Reactor Innovation Center whose support for microreactor demonstration programmes at Idaho National Laboratory creates the US government testing infrastructure that commercial microreactor demonstration is using, represent the public investment that is derisking microreactor technology ahead of the commercial deployments whose economics will determine whether microreactors find the revenue-sustaining commercial markets their developers project.
Oklo Aurora and the Licensing Milestone
Oklo is the US advanced fission company whose Aurora compact fast reactor, a liquid metal-cooled fast spectrum microreactor using high-assay low-enriched uranium fuel to generate approximately fifteen megawatt of electricity, has progressed furthest in the US NRC licensing process of any commercial microreactor developer. The NRC's combined licence application review, which integrates the construction permit and operating licence review steps that conventional reactor licensing separates, has given Oklo the regulatory engagement experience whose documentation and technical interaction the NRC has incorporated into the advanced nuclear licensing framework development that the Nuclear Energy Innovation and Modernisation Act directed. Oklo's business model, licensing nuclear power services rather than selling reactor hardware, means that Oklo retains ownership of the reactor and its used nuclear fuel while the customer purchases electricity or heat at negotiated prices over the deployment contract lifetime, reducing the customer's capital commitment and nuclear regulatory obligation to a power purchase agreement rather than a reactor ownership and operating licence requirement. Its partnerships with data centre operators and industrial customers who are evaluating microreactor power for energy-intensive computing or process heat applications represent the commercial pipeline whose conversion from evaluation to contract would establish the first commercial microreactor revenue.
Westinghouse's eVinci microreactor, a heat pipe-cooled solid-state reactor whose passive heat transport from the core to the power conversion system uses no active cooling system components and whose design provides inherent safety through the passive temperature feedback that eliminates the active safety system requirements of water-cooled reactors, has been selected by the Canadian Nuclear Safety Commission for its vendor design review and is being evaluated by Canadian remote communities and mining operations as a diesel replacement energy source. Westinghouse's eVinci partnership with Enercan, the Canadian nuclear services company, for Canadian market development creates the commercial pathway for eVinci deployment in the Canadian remote community and mining applications where diesel fuel delivery by winter road creates both the high cost and the supply reliability risk that nuclear energy's fuel-long-duration design eliminates. X-energy's Xe-100 high temperature gas-cooled reactor, while slightly larger than microreactor size at about eighty megawatts thermal per module, targets the industrial process heat market whose high-temperature steam requirements create demand for the five hundred degree Celsius process heat that the Xe-100's helium coolant outlet temperature provides.
Defence and the Strategic Application
The US military's strategic interest in microreactor nuclear power for forward operating base energy supply reflects the vulnerability that diesel fuel supply logistics creates for military operations in contested or remote environments, where the fuel convoy that supplies the generator sets powering the base creates the casualty risk, logistical burden, and operational constraint that the Project Pele transportable microreactor programme sought to address. A forward operating base whose energy supply comes from an on-site nuclear reactor that operates for years without fuel resupply eliminates both the convoy logistics burden and the tactical vulnerability that fuel storage creates, providing the energy security and operational independence that the military values independently of the commercial cost comparison with diesel generation that drives the civilian remote energy applications.
Top 10 Companies in Microreactor Nuclear Technology Globally
- Oklo: US advanced fission company with Aurora compact fast reactor and NRC combined licence application engagement; its nuclear power services business model and its data centre and industrial customer pipeline create the most commercially advanced US microreactor developer whose licensing progress and partnership portfolio define the commercial timeline for first deployment.
- Westinghouse Electric (eVinci): US nuclear technology company with eVinci heat pipe microreactor in Canadian nuclear safety commission review; its passive safety heat pipe cooling and its Enercan Canadian partnership create the established nuclear company's microreactor product whose inherent safety design and commercial partnership development target the Canadian remote community and mining markets.
- X-energy: US high temperature gas reactor developer with Xe-100 TRISO-fuelled reactor for industrial heat and power; its TRISO fuel manufacturing subsidiary Triso-X and its industrial process heat application development create the advanced reactor company whose high-temperature output addresses the industrial heat decarbonisation market that other microreactor designs do not serve at sufficient temperature.
- Ultra Safe Nuclear Corporation: US-Canadian microreactor company with Micro Modular Reactor using TRISO fuel and heat pipe cooling; its University of Illinois deployment programme and its heat pipe passive safety create the TRISO-fuelled microreactor whose university campus deployment demonstrates the non-utility, distributed deployment concept that microreactors target.
- NuScale Power: US small modular reactor company with NuScale SMR and VOYGR power plant modules; its larger scale than microreactors but its modular factory-fabricated design philosophy and its NRC Design Certification create the small modular reactor commercial position that bridges the gap between microreactors and conventional nuclear plants.
- Kairos Power: US fluoride salt-cooled high temperature reactor developer with Hermes demonstration reactor at Oak Ridge; its molten fluoride salt coolant and its TRISO fuel create the advanced reactor design for high-temperature industrial heat whose Hermes demonstration programme at the DOE's Tennessee Valley site is building the operational experience that commercial microreactor licensing requires.
- Terrestrial Energy: Canadian molten salt reactor company with Integral Molten Salt Reactor for industrial process heat and power; its Canadian Nuclear Safety Commission pre-licensing review and its industrial heat application development create the molten salt reactor company whose passive safety and high-temperature output target the industrial decarbonisation market in Canada and the United States.
- Denver Atomics: US microreactor startup developing ultra-compact fission systems for remote power applications; its early-stage development and its focus on the smallest power class of nuclear systems create the emerging microreactor developer whose technology development reflects the diversity of approaches that the microreactor market is exploring before consolidation around commercially proven designs.
- BWX Technologies: US nuclear manufacturing and services company with microreactor design and fuel fabrication for Project Pele and commercial applications; its established nuclear manufacturing capability and its Project Pele transportable reactor design create the nuclear manufacturer's microreactor commercial position whose manufacturing expertise complements the technology developer companies whose fabrication they depend on.
- Rolls-Royce SMR: UK advanced reactor company with small modular reactor programme backed by UK government investment; its UK factory-fabricated SMR design and its UK nuclear manufacturing heritage create the European small modular reactor developer whose government-backed programme targets the UK and export market for factory-built nuclear power modules.