Will small modular reactors create new nuclear energy?
Jody Dascalu | December 03, 2023In an increasingly interconnected and energy-dependent society, the demand for reliable, efficient and sustainable power is paramount. Traditional centralized power systems, although effective in certain contexts, exhibit limitations in scalability, resilience, and environmental impact. Decentralized power systems offer an alternative by distributing power generation closer to the point of consumption, which addresses some of these limitations. Within the scope of decentralization, microreactors emerge as a solution, offering the benefits of nuclear technology in a compact and modular form.
Microreactors, as their name suggests, are small modular reactors that generate electricity or provide heat for industrial or residential processes. Their compact size and modular design allow for quicker deployment, localized power generation and scalability to meet demand. Given their operational efficiency and potential for lower environmental impact, microreactors offer a compelling option for integration into decentralized power systems.
Traditional centralized power grids
The traditional architecture of centralized power grids is primarily based on a limited number of large-scale power generation facilities, typically employing fossil fuels or nuclear fission for electricity production. These facilities are often located at considerable distances from consumption centers, necessitating an expansive network of high-voltage transmission lines and distribution substations.
The system's primary advantage lies in its economies of scale: large-scale generation typically results in reduced per-unit costs due to optimized operational practices and longstanding technological maturity. Regulatory compliance is also simplified, given the fewer points of generation and centralized control.
However, this centralized approach is not without its drawbacks. Long-distance transmission inherently introduces electrical losses, reducing overall system efficiency. The centralized nature creates single points of failure, increasing the system's vulnerability to disruptions from various sources, be they technical malfunctions, natural disasters, or cyber-physical attacks.
The architecture and inherent limitations of traditional centralized power systems serve as a contextual foundation for exploring decentralized alternatives, such as microreactors, which promise to mitigate some of these drawbacks while offering unique advantages.
The potential of microreactor technology
Microreactors stand as a specialized category within small modular reactors, engineered to deliver outputs of up to 20 megawatts electric (MWe) or commensurate amounts of heat. Initially conceived for isolated deployments, such as remote communities or military installations, these reactors are often colloquially termed "nuclear batteries" or "fission batteries," because of their portability and focused application. They are typically factory-built and transported in cargo containers, allowing for global deployment with minimal infrastructure modifications.
One salient characteristic of microreactors is their compatibility with mini- or micro-electrical grids. Upon arrival at the target location, they can be integrated into existing electrical infrastructures with minor upgrades, offering decades-long operation with reduced maintenance and operational costs.
This deployment ease positions microreactors as potential solutions for specialized energy requirements, be it powering large cargo ships, disaster relief operations, or serving as a reliable energy source for industrial applications in developing nations with unstable electrical grids.
The design paradigms of microreactors often involve advanced materials, such as refractory metals and high-temperature ceramics, which are critical for withstanding extreme operational conditions. Additionally, their compact core size benefits passive safety through faster decay heat dissipation. Advanced control algorithms are also increasingly integrated into the reactors' control systems, enabling real-time monitoring and adjustments, making them well-suited for remote or autonomous operation.
Pioneering energy with microreactors
While commercial deployments of microreactors are still in nascent stages, pilot programs and feasibility studies demonstrate their potential for serving remote regions, military bases and specialized industrial applications where extending the traditional grid is economically challenging. Their compact, modular design is engineered for ease of transport and installation, underscoring their utility for localized energy requirements.
Research is ongoing to explore the integration of microreactors into existing power grids. Preliminary studies indicate their capability to serve as supplementary power sources, alleviating grid stress during peak demand or replacing aging infrastructure, thereby potentially enhancing grid reliability and sustainability.
Microreactors are also under consideration for rapid-deployment scenarios, such as disaster relief, where establishing a critical power supply is time-sensitive. Their modular design and quick startup capabilities make them well-suited for such applications, although this utility remains theoretical until actual deployments provide empirical evidence.
Purpose of decentralization
The move toward decentralization in power systems is driven by a confluence of factors that aim to address the inherent limitations of centralized models. One of the notable motivations is energy security. Decentralized systems, by virtue of their distributed architecture, reduce the risks associated with single points of failure. A network of localized generation sources enhances grid resiliency, thereby providing a more robust response to system failures, be they from natural calamities or cyber-physical threats.
Environmental sustainability is another compelling rationale for decentralization. Localized energy production can more readily incorporate renewable sources, such as solar and wind, thus reducing greenhouse gas emissions and other environmental pollutants. Moreover, the proximity of generation to consumption centers decreases transmission losses, contributing to overall system efficiency.
Technological feasibility has also reached a point where decentralization is possible and potentially advantageous. Advances in power electronics, control systems and energy storage solutions have matured to a stage where they can be effectively integrated into decentralized grids. These technologies facilitate real-time monitoring and dynamic load balancing, enabling more efficient and flexible operations compared to traditional centralized systems.
Challenges and criticisms
While microreactors offer numerous advantages, they are not devoid of technical challenges. Issues such as material degradation under high neutron flux or complexities in waste management require further research and engineering solutions.
The integration of nuclear technology into decentralized systems can face public resistance due to misconceptions or concerns about safety and radioactive waste. Public perception remains a significant barrier to the widespread adoption of microreactors.
Microreactors are in competition with other technologies such as advanced batteries, fuel cells and smaller-scale renewable energy installations. A comparative analysis in terms of efficiency, cost and environmental impact is needed to determine the viability of microreactors in a diversified energy landscape.
While microreactors offer promising features for decentralized power systems, their adoption is accompanied by technical, perceptual, and competitive challenges that need to be critically addressed.
Future outlook
Ongoing research in materials science and advanced manufacturing is expected to enhance microreactor longevity and efficiency. Further work on passive safety and control algorithms will contribute to broader applicability.
Changes in energy policies favoring low-carbon technologies can accelerate microreactor integration into decentralized systems. Standardized licensing procedures could reduce deployment barriers. International collaborations aim to harmonize regulatory practices.
The focus on sustainability in energy systems is likely to increase demand for microreactors. Early adoption in remote or critical infrastructure will influence broader industry trends. The potential for coupling with renewable sources or cogeneration applications provides diversified revenue streams.
Author byline
Jody Dascalu is a freelance writer in the technology and engineering niche. She studied in Canada and earned a Bachelor of Engineering. As an avid reader, she enjoys researching upcoming technologies and is an expert on a variety of topics.
References
Black, G., Shropshire, D., Araújo, K., & Van Heek, A. (2022). Prospects for Nuclear Microreactors: A review of the technology, economics, and regulatory considerations. Nuclear Technology, 209(sup1), S1–S20.
Lovering, J. R. (2023). A Techno-Economic evaluation of microreactors for Off-Grid and Microgrid applications. Sustainable Cities and Society, 95, 104620.
This article fails to recognize the many problems that microreactors face:
1. They don't exist. They are still in the conceptual or development phase. We need alternative energy last decade, not next decade. The nuclear industry was already challenged to ramp up the number of reactors to substitute for fossil fuel. Huge government grants were offered and environmental and safety requirements were relaxed. The few reactors that resulted were way over budget and way late. Microreactor proponents are expecting the same grants and relaxed safety regulations for these new unproven designs, and have no examples to show that they will be more successful. Don't take my word for it, ask Greg Jaczko, previous Chair of the NRC. Climate change is upon us. We need to deploy known solutions now.
2. There is still no solution for long-term storage of the radioactive waste. Proposed novel fuel cycles are actually not novel, and come with additional known risks that have been avoided until now. Leaving a 10,000 year HLRW problem for future generations is irresponsible.
3. They're expensive. We need to devote our limited resourced to alternatives that are proven and ready, not divert significant fractions of it toward this wishful thinking.
We need serious solutions, and Microreactor proposals fall far short.
In reply to #1
The 70's era demonisation of Nuclear Energy has resulted in large nuclear stations being imposibly expensive and subject to intolerable delays. Any quantitative analysis will show that without Nuclear as a substantial part of the mix, low carbon energy production is simply not possible. SMR's and novel fuel cycles drastically reduce the delays, the costs and the waste issues around deploying nuclear. These machines are all "inherently" or "walk-away" safe. They mostly require "exclusion zones" of 100 ft or less. The waste issue is also qualitatively different; even for "traditional" cycles, the amount of waste is far less. There is also the fact that MSR's offer the opportunity to actually use the "spent" fuel from traditional cycles as feed. This would reduce the amount, the lethality and the half-life of those residues by, again, orders of magnitude. Then there is Thorium which offers even more advantages. The bottom line is that Nuclear, no matter the flavour, kills and injurs fewer humans that ANY other method of making electricity already and the new technologies will make it even safer. Wind, Solar, Wave, Hydro & Geothermal all have roles to play but at the end of the day the economics of dispatchable 2/7/365 safe power dictate that Nuclear, in all it's forms, must be a large part of our future energy mix. Do the math, the renewables alone will not meet demand and humankind will not acdept reduced energy availability. So it is either fossil fuels or Nuclear and the inertial of Gigawatt sized BWR stations is simply too large.
"Microreactors are in competition with other technologies such as advanced batteries, fuel cells"
Batteries and fuel cells are not sources of energy generation. Batteries are a storage medium and fuel cells are a conversion engine. Both require upstream energy generation.
Whichever way you look at it, we need to increase all forms of zero-carbon energy *generation* massively to simply maintain our current standards of living if we are going to shut down fossil fuels.