China builds nuclear plant that can’t meltdown

New testing at the Shidaowan plant shows that, even in a crisis, the nuclear plant can cool itself down passively. This is the first-ever demonstration of a commercial nuclear plant of this type and shows that meltdown-proof plants are becoming a reality.

TRISO fuel

We’ve written about TRISO nuclear cells before and how they can usher in a new age of nuclear power — but China has actually gone ahead and done it.

TRISO (TRi-structural ISOtropic) nuclear fuel cells are a type of advanced nuclear fuel designed to enhance the safety and efficiency of nuclear reactors. Each TRISO particle is a tiny, spherical fuel pellet encased in multiple layers of protective materials that act as a barrier. This barrier contains the radioactive fission products, preventing them from escaping even under extreme conditions. TRISO fuel is highly resistant to high temperatures and radiation, making it particularly suited for next-generation reactors.

Shidaowan’s twin 100-MW units encase the uranium capsules in graphite shells about the size of billiard balls. In this design, the nuclear fission reaction occurs slower than in conventional reactors, but the fuel can withstand higher temperatures for longer. Furthermore, the heat from the fission is dispersed, creating a passive cooling process. There’s another safety mechanism: while most reactors use large volumes of water to cool down, this system uses a small amount of helium, which can also withstand higher temperatures.

If the nuclear reactor suffers a crisis, it can’t overheat and meltdown because of the passive cooling system — at least, this was the theory. Researchers at Tsinghua University in China have now put the theory to the test, performing two safety tests by shutting off the active power supply to see if the decay heat could be removed passively.

The reactors passed with flying colors, cooling down just as expected.

“The results of the tests manifest the existence of commercial-scale inherent safety for the first time,” the researchers write in an article published in the journal Joule.

No more Fukushima

The biggest objection to deploying more nuclear power is that it nuclear reactors can have devastating meltdowns. Although nuclear energy is much safer than most people think (and definitely safer than fossil fuel energy), people still fear it. The issue is that, although isolated and rare, nuclear meltdowns are scary events. Chernobyl and Fukushima are still enough to make communities and policymakers avoid nuclear energy — even during the climate crisis.

This is why the new type of reactor can make such a big difference.

During the tests, the reactors reached a maximum temperature of just 870°C after 3.5 hours without power. That’s pretty hot, but not hot enough to melt through stainless steel and containing materials. During the Fukushima meltdown, reactors reached 2800°C. This system should be meltdown-proof.

The reactor at Shidaowan produces 200 MW of power. This is significantly less than a “conventional” nuclear reactor, which typically produces around 1000 MW. But it shows that the technology works and can be scaled up. As a ballpark, a 200 MW reactor can power 150-200,000 homes.

Safety and Sustainability

This plant is part of a global push to design better, safer nuclear power. Prototype reactors have also been used in China and Germany (although they were not large-scale plants like Shidaowan). The University of Illinois at Urbana Champaign and the Italy-based Ultra Safe Nuclear Corporation are also collaborating on a TRISO-powered microreactor to power the university campus. The USA is also working on an 80-MW gas-cooled reactor that could scale up to a four-park, reaching 320 MW.

The future of TRISO is promising, and it’s not the only contender for the future of nuclear power. Other technologies, such as molten salt reactors and fast breeder reactors, are also being explored. The future of nuclear power will likely be shaped by a combination of these innovations, driven by the need for safer, more efficient, and more sustainable energy sources.

Ultimately, more safe nuclear energy can only be good news. The world is focusing on solar and wind power as alternative energy sources, but nuclear remains a steady source in the mix — one that we should perhaps look more closely into.

The study was published in the journal Joule.