With the recent boom in data center development, grids are struggling to keep up with energy demand. This has started conversations around alternative means to meet the power requirements for training the latest A.I. models. A couple of the predominant alternatives being discussed are Small Modular Reactors (SMRs) and Micro Nuclear Reactors (Microreactors), miniaturized versions of traditional nuclear reactors for localized power production. While these reactors would seem to remedy the bottleneck for prime power production, there is a lot of confusion as to when these solutions would be fully realized and how they will impact the backup power requirements, specifically diesel fuel dependence.
In this article we will discuss:
- What are Small Modular Reactors and Micro Nuclear Microreactors?
- When Will Nuclear Start Powering Data Centers
- How Nuclear Will Impact Backup Power Requirements
- Why Diesel Backup Power is Here to Stay
What are Small Modular Reactors and Micro Nuclear Reactors?
Nuclear power has long been a key source of clean, reliable electricity, but traditional reactors are enormous and complex. Enter Small Modular Reactors (SMRs) and Micro Nuclear Reactors (Microreactors) —groundbreaking technologies that promise to miniaturize and democratize nuclear energy.
SMRs and microreactors are essentially smaller nuclear fission reactors. SMRs are permanent but modular installations with higher power outputs (Up to 300 MWe) while microreactors are more mobile with lower but still substantial power output (1-20 MWe).
Despite their differences, SMRs and microreactors are both being explored as viable prime power alternatives for data centers. SMRs are being eyed for large, hyperscale data centers that require massive and consistent power for heavy workloads like AI and machine learning while microreactors are deemed better suited for smaller, edge, or remote data centers where grid connection is not feasible or desirable.
In addition to their power output potential, both of these technologies have several differences making them more suitable for the different use cases described above. SMRs, due to their larger size, take longer to deploy but can produce more persistent power at a lower cost. On the other hand, microreactors can be deployed relatively quickly with some designs allowing them to be easily transported by truck. These benefits do yield trade offs as micro nuclear reactors have lower power outputs and higher operational costs when compared to SMRs.
When Will Nuclear Start Powering Data Centers?
TLDR: Soon.
While large-scale adoption of nuclear for data centers is still a few years out, the initial deployments are expected to begin in the late 2020s, with significant commercial projects coming online in the early 2030s.
Google has announced an agreement to potentially deploy up to seven of Kairos Power's Small Modular Reactors (SMRs), aiming for the first unit to be operational by 2030. This project could provide up to 500 MWe of power.
Amazon is collaborating with X-Energy on a project involving their Xe-100 SMR technology. Their stated goal is to bring over 5 GW of new power projects online by 2039, with an early focus on supporting a 320MW four-unit deployment.
Microsoft is actively investing in nuclear technologies, posting job roles for a "Principal Program Manager, Nuclear Technology" to spearhead its global SMR and microreactor strategy for its cloud and AI infrastructure. The company is also involved in agreements, like a 20-year power purchase agreement to restart a retired reactor (Three Mile Island Unit 1) to support its data center operations.
In summary, the journey to nuclear-powered data centers is already underway. While full realization of the vision—where nuclear energy is a major source of data center power—is a 2030s prospect, the pilot projects and significant power purchase agreements are setting the stage for deployment to begin in the next few years.
How Nuclear Will Impact Backup Power Requirements
To effectively answer this question we must first look at the reliability of SMRs and microreactors, particularly the frequency and potential for planned and unplanned downtime respectively.
The Frequency of Planned Nuclear Downtime
Planned downtime for an SMR is primarily for refueling and scheduled maintenance. The key difference from traditional nuclear plants is the SMR's smaller, modular design, which dramatically improves capacity availability.
Many SMR designs are engineered for longer operating cycles. Conventional Nuclear typically refuels every 18 to 24 months. SMR designs are aiming to refuel every 3 to 7 years while some microreactor designs are are intended to run for up to 30 years without a fuel change. This significantly reduces the frequency of planned outages.
To address the reality of inevitable refueling events, some campuses are looking to adopt multi-module SMRs (e.g., six 50 MW modules). This will allow operators to stagger the refueling schedules; Shutting one module down while the other five continue to run, minimizing the total capacity loss to the data center.
In addition to multi-modal configurations, new SMR designs are embracing advanced refueling methods (like replacing the entire core vessel in some designs). This is predicted to reduce actual downtime for maintenance and refueling compared to the multi-week outages common for large reactors.
The Potential for Unplanned Nuclear Downtime
Unplanned downtime are those resulting from equipment failure, operational error, or external events. Nuclear power plants, in general, are known for having the lowest forced outage rates among all conventional power sources, and SMR designs are intended to maintain this high record of reliability.
A major design feature of SMRs is the heavy reliance on passive safety systems that use natural forces (like gravity or convection) to safely shut down and cool the reactor without relying on human intervention, external power, or active components. This design philosophy is expected to lower the risk of equipment-related unplanned shutdowns.
The ultimate measure of reliability is the Capacity Factor (CF), which measures the amount of energy a plant produces compared to its maximum potential. Traditional nuclear consistently achieves a CF above 92%. SMR designs aim to match or even slightly exceed this industry-leading figure due to their modularity, simplified systems, and reduced maintenance cycles.
In the context of a data center, the risk from an SMR forced outage is managed by the fact that if a multi-module facility loses one module, the remaining modules can continue to operate, ensuring a very high level of overall power reliability.
What Does this Mean for Diesel Backup Power?
Localized nuclear energy is expected to significantly increase prime power reliability for data centers leaving some to speculate if the grid itself will become the main source of backup power or if mobile microreactors could replace diesel generators.
Currently, neither of these scenarios seem likely and no major player has announced a potential shift in their current approach to backup power.
Grid reliability is not expected to improve significantly and will remain outside the bounds of data center control. Grid output capacity may also slow in terms of growth should data centers begin embracing SMRs and microreactors, relieving currentcurrent pressures for gridss to rapidly expand.
Regarding microreactors replacing diesel generators, a cold startup on an idle microreactor can take several days, a length of time far too long for an uninterruptible power source (UPSs) to bridge. Even if the plan was to keep a series of microreactors running in case of a downtime event, facilities would have to send the excess power these reactors continually produce back to the grid, potentially creating logistical issues that could negatively affect grid stability.
Why Diesel Backup Power Is Here to Stay
As the arms race for Artificial General Intelligence (AGI) heats up and the world becomes more and more reliant on digital infrastructure, data center operators continue to acknowledge that redundancy is paramount. The potential for unplanned downtime for SMRs and microreactors are slim, but not zero. That point alone justifies the continued existence of backup power solutions like diesel generators.
While other alternatives power sources to diesel exist, they are not seen as true replacements. Grid reliability and power capacity will remain outside control of data centers. Mobile microreactors take far too long to deploy assuming they are not already running. Battery technology is improving but is expected to remain sequestered to Uniterruptible Power Supplies (UPSs). “Green” fuel alternatives have been explored but continue to face an uphill battle in matching the cost and wide availability of diesel fuel.
The practicality and reliability of diesel generators for sustained, independent backup power make them the default and most dependable choice for data centers. Until a backup power solution emerges that can justify the switch from a legacy backup power solution, diesel fuel will remain the last line of defense in keeping the digital world up and running.
