Navigating Nuclear: Microreactors, SMRs, and Traditional Plants

When you think of nuclear power plants, you may envision massive, concrete structures that cost billions of dollars to construct and take decades to come online. However, this image of nuclear plants is evolving, giving way to alternatives such as microreactors and small modular reactors (SMRs). Understanding how these plants compare in terms of energy output, size, and resource and land requirements is essential for making informed decisions about sourcing energy for the increasing demands of industry, communities, and countries.

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Microreactors

Microreactors’ ability to deliver reliable, carbon-free baseload power via a compact design 100 to 1,000 times smaller than conventional nuclear reactors is a promising development within the nuclear landscape. Although the current definition for the number of megawatts that qualify as a microreactor varies, with some categorizing it at less than 50 megawatts of electricity (MWe), and some less than 10 MWe,  a nuclear reactor that generates less than 20 MWe is generally regarded as a microreactor. The smaller nature of a microreactor means that land requirements are minimal—typically just a few acres—as well as on-site staffing requirements. These characteristics make this option ideal for offering localized energy solutions, from industrial sites to military installations. 

Adding to the benefits of sizing down the reactor, some microreactors are also modular, meaning components are factory-fabricated and shipped to site for assembly. By simplifying building techniques, modular plants can be assembled more rapidly on-site, thus making these plants better equipped to scale, and allowing for incremental expansion and increased power output over time based on customer demand. 

Energy Output: <20 MWe
Time to Deploy: <24 months
Land Requirement: Minimal
Water Requirement: Minimal or none

‍Last Energy’s PWR-20 is a micro modular reactor with a 20 MWe output and a physical footprint of just 0.3 acres. It is fully modular, meaning every component and connection is factory-fabricated, tested under controlled conditions, and contained in standardized modules, enabling on-site assembly to take just four months. Its air-cooled design means the plant does not have to be located near a body of water for cooling, allowing the PWR-20 to be sited nearly anywhere.

Small Modular Reactors

Small modular reactors (SMRs) have been lauded as a player in the realm of nuclear innovation, offering a versatile and scalable approach to power generation. Typically featuring an energy output ranging from 20-300 MWe and requiring a footprint that varies based on the specific design (typically over 100 acres), the smaller size of SMRs can mitigate the construction challenges of large, gigawatt plant builds, while offering a larger power output than microreactors. Staffing requirements can vary, but estimates suggest an average of 1.5 person/MWe, falling within the range of 30 to 150+ individuals.

While “modular” is part of the name, the level of modularity that these plants embrace varies across designs. To be truly modular:

• All components should be factory-fabricated
• The plant should require limited on-site preparation and time to assemble
• The design should offer more flexibility regarding financing, siting, sizing, and end-use applications
• Additional modules should be able to be added incrementally as demand for energy increases

Energy Output: <300+ MWe
Time to Assemble: 3-5 years
Land Requirement: Varies, typically >100 acres
Water Requirement: Minimal to moderate

Traditional Nuclear Plant

Historically, gigawatt-scale traditional nuclear power plants have played a pivotal role in generating electricity to meet the substantial demands of large populations and regions. With energy outputs of around 1,000 MWe per plant (1 GW), these plants have a large footprint, often exceeding one square mile. Operating at this scale, the average staffing ratio is approximately 0.7 person/MWe, translating to thousands of workforce personnel per plant.

The magnitude of their scale—while offering significant power generation capabilities—has substantial environmental and infrastructure impact implications and requires rigorous regulatory assessment. A combination of these challenges, along with construction complexity, lead these large-scale builds to typically go over budget by around 200% and historically take an average of about eight years to complete.

While these plants have the advantage of producing substantial power outputs that can sustain large communities, one must consider their project development viability as new microreactor and SMR designs offer more affordable and flexible deployment opportunities.

‍Energy Output: 1+ GW
Time to Deploy: ~10  years
Land Requirement: 1+ square mile
Water Requirement: Large 

In the evolving landscape of nuclear energy, the distinct characteristics of microreactors, SMRs, and traditional gigawatt-scale plants highlight diverse avenues for meeting energy needs. Emerging as one of the most promising solutions for decarbonizing industry is the microreactor, demonstrated by Last Energy’s PWR-20. No matter the type of technology, nuclear energy, with its capacity for reliable, low-carbon power generation, remains a vital cornerstone in the necessary transition to clean energy.