The spectre of a nuclear accident like the one at Fukushima in 2011, where a failure in the cooling system triggered a core meltdown and the release of radioactive material, has haunted the nuclear industry for decades. The quest for inherently safer reactors, capable of withstanding even catastrophic cooling failures, has been a primary goal for scientists and engineers.
Against this backdrop, the news that China has successfully developed and tested a nuclear reactor that does not melt down even if its cooling system fails may represent a crucial milestone in the quest for safer and more sustainable nuclear energy.
Este avance, basado en un diseño de reactor de sales fundidas (MSR por sus siglas en inglés) conocido como «refrigeración pasiva», promete revolucionar la industria nuclear, ofreciendo una alternativa potencialmente más segura y limpia a los reactores tradicionales. A diferencia de los reactores de agua ligera convencionales, que dependen de sistemas de refrigeración activos y complejos para prevenir el sobrecalentamiento, este nuevo diseño utiliza principios físicos intrínsecos para mantener la seguridad incluso en situaciones de emergencia.
To understand the magnitude of this breakthrough, it is important to know a little about the underlying technology that makes it possible:
. Encapsulated Thorium and Uranium Fuel: Unlike conventional reactors that use enriched uranium, this new design employs a fuel composed of thorium and uranium encapsulated in graphite. Thorium, a naturally occurring radioactive element more abundant than uranium, has significant advantages in terms of safety and waste production. Encapsulating the fuel in graphite, a material with high heat resistance, provides an additional safety barrier, preventing the release of radioactive material even at extreme temperatures.
. Slower, more controllable reactions: The combination of thorium with uranium and its encapsulation in graphite allows for a slower, more controllable nuclear reaction. This means that the reactor generates heat more gradually and steadily, reducing the risk of a sudden increase in temperature that could lead to a core meltdown.
. Passive cooling: The most innovative feature of this design is its passive cooling system. Unlike active systems that rely on pumps and valves to circulate coolant, this reactor is able to self-regulate its temperature.
The tests in China were a success, and when the coolant flow was deliberately stopped in a prototype 105 MW reactor, they demonstrated the effectiveness of this passive cooling system. For the 36 hours of testing, the core temperature remained within safe limits, demonstrating the reactor's ability to self-control without human intervention or active safety systems.
This technological advance has the potential to revolutionize the nuclear industry, offering a safer, cleaner and more sustainable source of energy. However, there are still two major challenges to overcome before these reactors can be implemented on a large scale.
One is cost: The development and construction of reactors of this type present considerable technical and economic challenges. The scalability of the technology to a commercial level and the competitiveness of production costs are aspects that still need to be demonstrated.
And another is the management of radioactive waste: While thorium produces less long-lived radioactive waste than uranium, the management of this waste remains a major challenge that requires safe and sustainable solutions.
And it must also be taken into account that the negative public perception towards nuclear energy, fuelled by past accidents, remains an obstacle to its development and implementation. It is crucial to foster transparency, communication and public confidence in the safety of these new technologies.
The future remains to be seen, but the challenge of the Climate Crisis is so enormous that all the means we can get are needed to generate energy in a non-polluting way.
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