Are There Any Small Modular Reactors in Operation Today?

So, you’re wondering if small modular reactors, or SMRs, are actually up and running somewhere right now. Well, SMRs are basically smaller versions of regular nuclear reactors that are designed to be built in factories and assembled on-site. This makes them potentially cheaper and easier to install compared to big nuclear plants. As of today, there are a few pilot and demonstration SMR projects in progress around the world, but fully commercial SMRs are still pretty rare. Some countries, like Russia and China, have started operating smaller reactors that fit this category, mostly for remote areas or specific industrial uses. The main idea is that SMRs could provide clean energy to places that don’t need or can’t support large nuclear plants. However, many SMRs are still going through testing and regulatory approval, so it might take a little while before they become common sights. It’s an exciting step toward more flexible nuclear energy, but we’re not quite there on a big scale yet.

Small modular reactors (SMRs) represent an emerging class of nuclear reactors characterized by their reduced size and modular design, allowing for factory fabrication and scalable deployment. These reactors typically produce up to 300 megawatts of electric power, significantly less than traditional large-scale nuclear plants, which often exceed 1,000 megawatts. The key attributes of SMRs include enhanced safety features, passive cooling systems, and simplified construction processes, which collectively contribute to potentially lower capital costs and reduced onsite construction times. Unlike conventional reactors, SMRs often utilize advanced designs such as integral pressurized water reactors or molten salt reactors, enabling them to operate with greater efficiency and improved safety margins.

Currently, operational examples of SMRs are limited but notable. Russia’s Akademik Lomonosov is the world’s first floating nuclear power plant equipped with two SMRs, providing power to remote Arctic regions. This demonstration highlights the practical advantages of SMRs in delivering reliable electricity to isolated or hard-to-reach locations where large reactors are impractical. Additionally, China has made progress with the deployment of small reactors aimed at both power generation and district heating applications. These projects serve as proof of concept for the broader commercialization of SMR technology.

The modular nature allows these reactors to be produced in series, which can reduce costs through mass production techniques. However, regulatory frameworks and market acceptance remain hurdles before widespread adoption. The ability of SMRs to integrate into grids with variable demands or to provide heat for industrial processes further exemplifies their versatility in modern energy systems. As research continues and more pilot plants come online, SMRs may play a critical role in diversifying and decarbonizing energy portfolios worldwide.

At present, while small modular reactors (SMRs) are a highly promising and rapidly developing area in the nuclear energy sector, there are still a limited number of them in full - scale commercial operation globally. SMRs are defined by their relatively small power output compared to traditional large - scale nuclear reactors, typically with a capacity of up to 300 megawatts electric.

From a physical and engineering perspective, SMRs operate on the same fundamental principle of nuclear fission as larger reactors. Heavy atomic nuclei, such as uranium - 235, absorb neutrons, become unstable, and split, releasing a large amount of energy in the form of heat. This heat is then used to generate steam, which drives a turbine to produce electricity. Their smaller size offers several unique characteristics, including enhanced safety features due to passive safety systems that rely on natural physical phenomena like gravity and convection to cool the reactor in case of an emergency.

In terms of chemistry, the fuel and coolant materials in SMRs are optimized for their specific design and operating conditions. For example, some SMRs use advanced fuel forms that can improve fuel utilization and reduce waste generation.

In daily life, once more SMRs are in operation, they could provide a decentralized and reliable source of electricity, especially in remote areas or regions with limited access to the traditional power grid. Industrially, they can offer a stable energy supply for factories and manufacturing plants, reducing their dependence on volatile fossil fuel markets. Although not directly involved in most medical applications, the stable power from SMRs can ensure the uninterrupted operation of medical facilities. The development and deployment of SMRs represent a significant step forward in the evolution of nuclear energy technology, with the potential to reshape the global energy landscape.

Yes, there are small modular reactors (SMRs) in operation, though their deployment remains limited compared to traditional large-scale nuclear reactors. SMRs are defined by their smaller power output (typically 300 MWe or less) and modular construction, where key components are factory-built and transported to the site for assembly—distinct from large reactors, which are mostly constructed on-site. This design aligns with principles of industrial scalability, reducing construction time and adapting to variable energy demands.

One operational example is Russia’s Akademik Lomonosov, a floating nuclear power plant with two 35 MWe SMRs based on pressurized water reactor (PWR) technology. These units use enriched uranium fuel and rely on passive safety systems, where coolant circulation is driven by natural convection rather than pumps, enhancing safety by reducing reliance on active mechanical components. The plant, operational since 2020, provides power to remote Arctic communities, demonstrating SMRs’ ability to serve off-grid locations—unlike large reactors, which require extensive infrastructure and are tied to centralized grids.

Another example is the U.S. Army’s SM-1A, a 1.4 MWe reactor in Alaska, though it operates at low power for research. These SMRs differ from large reactors in their fuel cycle and footprint: they often use longer-lived fuel assemblies, reducing refueling frequency, and their compact size minimizes land use, a critical factor in urban or remote settings.

A key distinction lies in their modularity. Unlike large reactors, which are custom-designed for specific sites, SMRs leverage standardized components, enabling mass production and cost savings through economies of scale—a principle borrowed from manufacturing engineering, where repeatable processes reduce per-unit costs. This contrasts with the bespoke nature of traditional reactors, which suffer from cost overruns due to on-site construction delays.

Common misconceptions include equating SMRs to “miniature large reactors.” In reality, their design often incorporates advanced coolants (e.g., molten salt or helium) and passive safety features that simplify operation, addressing concerns about accident risk. Another misunderstanding is assuming SMRs are unproven; while widespread deployment is nascent, their core technologies (PWRs, boiling water reactors) are mature, with modifications to enhance modularity and safety.

SMRs are significant for decarbonization, offering flexible, low-carbon power for grids with high renewable penetration, as their smaller size allows incremental deployment to match demand growth. They also support industrial applications like hydrogen production, where steady heat output is critical. Their operation underscores the evolution of nuclear engineering toward adaptable, scalable systems, bridging the gap between large-scale baseload power and distributed energy needs.