The Real Answer Is: It Depends
 

As with most things, there is no one-size-fits-all solution in nuclear energy. This is true both in terms of its applications and the technologies used to realize them. Each reactor type comes with its own advantages and tradeoffs. Choosing between them is not just a technical decision—it reflects a developer’s broader vision and deployment philosophy. If the goal is efficient fuel use and waste minimization, fast-spectrum reactors may offer a better solution. If the objective is to utilize abundant fuel resources and support long-term energy sustainability, thorium-fueled fission reactors or even fusion reactors can be appealing. If thermal efficiency is a key priority, high-temperature designs become more favorable. If the focus is on building compact, transportable systems, then improving neutron economy and simplifying the fuel cycle becomes critical. The same logic applies to coolant selection—whether the system is water-cooled, gas-cooled, metal-cooled, or salt-cooled. Coolant properties such as neutron moderation, thermal conductivity, chemical reactivity, and operating pressure all influence reactor behavior and define the tradeoffs needed to meet specific mission requirements.
 

So, which reactor technology is best? It entirely depends on the problem being solved and the performance goals being prioritized.
 

Microreactors Shift the Equation
 

In large nuclear plants, the biggest cost and schedule risks usually come from civil construction, site-specific infrastructure, and custom balance-of-plant systems—not the reactor itself, which makes up only about 7% of total cost. Microreactors flip that equation, shifting economic sensitivity away from concrete and steam pipes and closer to the reactor core. The small size and modularity of microreactors drastically reduce construction complexity and capital intensity, transforming what used to be a multi-billion-dollar megaproject into something far more agile—perhaps a kiloproject (since SMR projects are still considered megaprojects).

 

In large reactors, fuel typically accounts for 15–25% of lifecycle costs, with most spending going toward site preparation, staffing, security, and regulatory compliance. In microreactors, fuel can make up 30–40% of total costs—depending on enrichment, burnup, and supply chain maturity—making the fuel cost per MWh 3–4 times higher. The cost of water as a dual-purpose coolant and moderator in conventional reactors is negligible. In contrast, microreactors often use advanced coolants such as liquid metals, molten salts, or gases, and moderators such as graphite, beryllium, or metal hydrides, which can make up 10–20% of both capital and operational costs. While total volumes are smaller, the cost per unit volume is typically 10–100 times higher than water, and the smaller core size amplifies the impact.

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Microreactors also bring a very different safety profile to the table. Large reactors operate at high power levels and power densities to achieve economies of scale, but this leads to higher radionuclide inventories and greater decay heat, requiring complex safety systems and resulting in longer licensing timelines. Microreactors, by contrast, typically operate at much lower power levels and generate significantly less decay heat. In many cases, passive systems can handle shutdown and cooling without external power or operator action. That not only makes the safety case simpler and licensing faster—it also opens the door to standardized licensing, automation, and remote monitoring. Taken together, these features can reduce capital and operational costs by 50 percent compared to traditional reactors.
 

The key takeaway is, with microreactors, overall costs are no longer dominated by site preparation, construction, and licensing—they’re increasingly driven by the reactor design.

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The Neutronix Approach
 

Microreactors offer advantages in safety, upfront cost, and deployment speed—but they forfeit the traditional economies of scale that benefit large reactors. To offset that, achieving economies of number through scalable production is essential. Building one reactor isn’t enough—the winner will be the first to scale. With a laser focus on near-term deployment and scalability, Neutronix has designed microreactors that are buildable, licensable, and deployable today—not a decade from now. Because microreactors shift economic sensitivity from site preparation to the reactor core, the technology’s design and operational parameters become even more critical. The reactor must be intelligently designed to extract maximum value from every kilogram of fuel, every centimeter of core, and every watt of power.

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Optimizing microreactor design and performance isn’t about selecting a single feature like fuel, coolant, or geometry in isolation. It requires navigating a complex, multivariate design space with competing constraints, where fuel, moderator, coolant, core materials, and operational parameters all interact—often in nonlinear ways. That’s why it has been said, quite rightly, that nuclear reactor design is “the art of compromise.” The insight needed to design and Pareto-optimize a robust microreactor doesn’t come from theory alone—it comes from doing the hard work: hands-on design, modeling, simulation, and iteration.

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At Neutronix, that’s exactly what we’ve done—bringing deep technical rigor to every decision and minimizing unknowns to deliver a  FOAK microreactor in 4–5 years.