From small reactors in series to thorium fuel: innovation in nuclear power

BarcelonaThe debate surrounding nuclear power can create the false impression that it is an obsolete sector, one where progress has stagnated and advancements have stalled. But the reality is far from that image. The nuclear sector is one of the areas where there has been significant interest in innovation for years, particularly after accidents like Fukushima, the advance of climate change, and the apparent slowdown in the renewable energy sector.

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Although it represents a significant fraction of the electricity currently supplied, renewable energy sources such as wind, hydropower, and solar still require the support of non-renewable energy sources through combined cycle or nuclear power plants. The major advantage of nuclear fission energy over fossil fuels is that, despite not being a renewable energy source, it does not generate carbon dioxide. For this reason, many see nuclear energy as an essential element in the transition to a completely green energy system.

Amid the political turmoil, innovation in nuclear energy is seeking, on the one hand, strategies that will allow for easier and more economical deployment of this technology, and on the other, ways to ensure that nuclear energy not only supplies power to the electrical grid but also injects power directly into facilities with high energy demands. Reducing costs and increasing operational efficiency is another essential area where much of the innovation is focused. Finally, innovation in this sector also aims to accelerate research into new technologies that will enable the creation of new, more efficient materials and fuels that generate less long-lived radioactive waste.

More efficient and safer power plants

One of the essential aspects of operating a nuclear power plant is safety, particularly after the dramatic consequences of the Chernobyl and Fukushima accidents in recent decades, although their causes, effects, and scales were very different. In this regard, since the Fukushima accident in 2011, nuclear power plant safety protocols have evolved considerably. European plants have additional safety systems that protect them against extreme events not foreseen in the original design, such as floods, earthquakes, or power outages. "The philosophy is to anticipate any imaginable scenario and ensure that safety depends not exclusively on active technology but primarily on self-sufficient passive systems," explains Alfredo García, an operator at the Ascó nuclear power plant and a nuclear science communicator.

A nuclear power plant is governed by strict operating protocols established by the Nuclear Safety Council and the International Atomic Energy Agency. These protocols have been progressively updated to adapt to the specific needs and demands of the sector, as well as to emerging technologies. Currently, digital systems have largely replaced the classic analog control systems. These new systems incorporate a high degree of redundancy, ensuring proper functioning and safety in the event of a subsystem failure. Furthermore, intelligent displays help operators process and interpret the thousands of signals received from across the plant.

Operator training has also improved substantially thanks to the integration of simulators that accurately replicate control rooms. This allows operators to be trained in a wide range of operational scenarios, incidents, and accidents before they occur. As expected, artificial intelligence has also made significant inroads into predictive maintenance and the generation of alerts for potential breakdowns or malfunctions through the analysis of vibrations, temperatures, and operating patterns.

Reuse waste

Managing the waste produced by fission reactions is one of the challenges facing nuclear power plant operations. This waste is highly radioactive and is typically stored in underground repositories, awaiting the natural decline of its radioactivity over time. Therefore, this is one of the areas that has generated the most interest within the sector and where the most progress has been made. "The goal is not only to store it safely but also to convert part of the waste into a resource and reduce the long-term radioactive legacy," explains García.

Currently, high-level radioactive waste is transformed into extremely stable glass blocks that prevent the diffusion of radionuclides for millennia. However, these blocks still need to be buried deep underground in very stable environments. Meanwhile, a line of research and innovation is developing technologies for recycling spent fuel, allowing for the recovery of usable materials and the separation and transmutation of long-lived waste to reduce its toxicity and half-life. Emerging companies like Transmutex, a Swiss company using cutting-edge particle accelerator technology to transmute nuclear waste for reuse, are at the forefront of this field.

Smaller and cheaper reactors

Far from viewing nuclear power plants as large, complex facilities, many companies are investing heavily in modular reactors. These reactors are much smaller and could have significant industrial value, as they are easy to mass-produce with much shorter lead times than nuclear power plants, which can take decades to build. These reactors can be installed in modules and adapted to the specific demands of the grid or users in particular industrial applications. TerraPower, founded by Bill Gates, is one of the best-positioned startups in the small modular reactor sector.

Next-generation reactors

Large reactors have also evolved considerably over time. Currently, the first fourth-generation reactors, cooled with sodium, gas, or lead, and molten salt reactors are being commissioned. These reactors represent a step forward in safety, since, in the event of a serious incident, the system tends to shut down automatically without requiring human intervention. Another advantage of these reactors is that, beyond having higher efficiency than third-generation reactors, they use recycled fuel or even waste from conventional reactors. "Fourth-generation reactors are still in pilot phases, but they are already setting the technological course for the future of nuclear power," says García.

Thorium reactors

Thorium is an element that is replacing uranium to power nuclear reactors, particularly in China, a country that leads the way in innovation with this type of fuel. Although the idea for thorium reactors dates back to the 1950s, it is only recently that the technology has matured enough to begin proof-of-concept testing. "This type of reactor is still in the experimental phase and will require decades of testing before widespread commercial implementation," says García.

The major advantage of thorium, besides being far more abundant than uranium, is that it generates less long-lived radioactive waste. Furthermore, thorium occurs naturally in a liquid state, making it easier to handle. However, despite its greater safety and reduced waste, thorium reactors still face significant technical, regulatory, and cost-efficiency challenges.

Fusion, an energy of the future

For decades, nuclear fusion energy, in which two hydrogen atoms fuse to create a helium atom and energy without long-lived radioactive waste, has been the perennial promise that should replace fission energy with a clean, efficient, and, in practice, almost inexhaustible energy source. However, experimental fusion reactors like ITER, the international consortium in France seeking to demonstrate the viability of nuclear fusion energy, have not yet achieved a positive energy balance, although considerable and promising progress is being made. "Fusion energy has enormous potential, but it won't be commercially operational for several decades. It's the future, a technology of the future, not of the present," explains García.

The great challenge of these projects is not only to demonstrate that nuclear fusion is possible, but to demonstrate that it can provide energy continuously and that the technology behind it is capable of withstanding high temperatures and intense particle flows.

Catalonia, expert in nuclear operation and safety

The general trend in Europe is to extend the lifespan of existing nuclear power plants while developing new, smaller modular reactors and positioning itself at the forefront of fusion energy development, thanks in part to the ITER project. Catalonia stands out particularly for its high level of expertise in nuclear engineering, as well as its extensive experience in operating and training highly qualified and internationally recognized personnel, which gives the region a strong culture of nuclear safety. "Although it does not develop its own designs, Catalonia is a key player in the sector's operational excellence at the European level," concludes García.