Breakthrough Meltdown-Resistant Nuclear Fuel Is Poised To Spark A Revolution

TRISO fuel nears regulatory approval.

Inside a nuclear reactor — WikiCC

When it comes to divisive technology, it doesn’t get more crowd-splitting than nuclear power. To some, it is a dangerous, toxic and problematic energy source, no better, or possibly even worse, than fossil fuels. To others, it is the cleanest and safest form of energy we have, capable of saving planet Earth from our environmental crimes. The argument for and against nuclear power has raged for decades on every level of human society. But, a burgeoning nuclear fuel technology called TRISO is poised to swing this argument in favour of nuclear power by making it far safer, cheaper, more plentiful and even lowering its carbon footprint. What’s more, US and Canadian nuclear regulators are now one step away from giving it regulatory approval. So, are we on the cusp of a nuclear revolution?

Let’s start with what TRISO fuel actually is. TRISO stands for TRi-structural ISOtropic fuel, and it is this structure which makes them so unique. TRISO fuel comes as spheres, some tiny, about the size of a poppy seed, others rather large, about the size of a billiard ball, but they all have the same structure. At their core, there is a uranium, carbon and oxygen nuclear fuel kernel; this is the part which undergoes fission to produce energy, but there is not enough within the core to undergo fission by itself. Surrounding the core are three layers of carbon and ceramic materials that are extremely robust and able to withstand massive temperatures and pressures.

Why is this so revolutionary?

Well, compare it to regular nuclear fuel, which forms uranium into little pellets and stacks them into metal tubes to make fuel rods. This has been how nuclear fuel has been manufactured for well over 60 years, and it has one fatal flaw, meltdowns.

A nuclear meltdown is what made Chernobyl so catastrophic. You see, after the reactor failed to control its fission, a runaway nuclear reaction started to happen, heating up its core to around 1,600 degrees Celsius. At this temperature, the water coolant in the reactor boils off, exposing the now molten nuclear fuel to the air, and the now molten nuclear fuel can flow out of the reactor. This effectively causes a breach of containment, allowing highly radioactive materials to enter the wider environment. In a worst-case scenario (which thankfully didn’t happen at Chernobyl), the self-heating super-hot molten fuel will erode far enough downward to meet groundwater, which would cause cataclysmically massive explosions as subterranean water instantly vaporised, spreading even more radioactive materials into the environment, but also polluting the water table with radioactive, toxic and biologically active (as in your body absorbs them) materials.

TRISO entirely mitigates this scenario, as the carbon and ceramic coatings stay solid well above the temperatures of a nuclear meltdown. In fact, a recent test of TRISO fuel kept it at 1,800 degrees Celsius for 300 hours, and not a single one melted. So, a reactor using TRISO fuel can have a major nuclear incident with runaway uncontrollable nuclear reactions and be safe. Water coolant with still boil and away and potentially cause a massive stream-driven explosion, but no radioactive materials will be spread into the environment.

If Chernobyl or Fukushima used TRISO fuel, I doubt there would be any fears over nuclear power’s safety.

On that note, TRISO has the potential to make nuclear power the ultimate clean energy and kick-start a new nuclear renaissance by enabling SMRs and FBRs. Let me explain.

While nuclear power is divisive, the data and statistics definitely are on the “for nuclear power” side. Despite the handful of nuclear incidents over the years, nuclear power is far, far safer than almost any other form of energy. In fact, for every thousand TWh produced, only around 90 people die, whereas wind sits at 150, solar at 440, natural gas at 4,000 and coal power at a massive 1,000 people! Nuclear power also has a tiny carbon footprint, only producing 4g per kWh, the same as wind power, and less than solar emits 6g per kWh. Nuclear also emits far less radiation into the environment than you might think; in fact, coal plants emit ten times more radiation into the environment per kWh of energy, thanks to impurities in the coal.

If nuclear power is so incredible, why don’t we use it? Well, it’s more expensive per kWh than fossil fuels like coal or gas and far more than renewables. It also takes decades to build nuclear power plants, as they effectively need to be custom-built on-site to massively high safety standards.

So, nuclear power could be a game-changer; it’s just being held back by cost and build time. This is where TISO comes in, as it can not only make nuclear even safer than it already is but also makes it faster to build, cheaper and cleaner.

First, TIRSO can make SMRs (Small Modular Reactors) possible. These reactors are far smaller than regular reactors; most have only a fifth of the output. This tiny size means that they can be almost entirely manufactured off-site and safely shipped to the power plant location. This power plant will use multiple of these reactors to build a modular nuclear power plant. Why would you do all of this? You can use economies of scale at the factory to make reactor production far quicker and cheaper; moreover, on-site construction will only take a year or two rather than well over a decade. This will make nuclear energy cheaper per kWh and allow the nuclear industry to grow rapidly with minimal delay.

There is just one problem with SMRs. The square cube law (read more here) dramatically affects them, significantly reducing their power output. To make up for this, they use higher enriched fuel (which has a higher percentage of uranium 235) or higher temperatures within the reactor. Both of these compensations can lead to an increased risk of meltdowns. As such, TRISO is an essential fuel to many SMR designs, as it helps them meet regulatory safety standards.

But TRISO can also help us recycle nuclear waste. The vast bulk of nuclear waste is uranium 238, which doesn’t undergo fission in a regular reactor. But uranium 238 can turn into viable nuclear fuel if you bombard it with “fast neutrons.” This turns it into plutonium 239, which can undergo fission just like uranium 235, except its fission products are far less radioactive and toxic.

FBRs (Fast Breeder Reactors) use massively high temperatures of up to 600 degrees Celsius to create fast neutrons, allowing them to “breed” their own nuclear fuel from uranium 238. In this way, FBRs can actually run off nuclear waste. Now, the US already has 90,000 tonnes of nuclear waste, which means using FBRs, they can entirely power themselves for a century off their current nuclear waste stockpiles.

But, keeping nuclear fuel stable at these high temperatures is incredibly difficult, which makes FBRs far more expensive and difficult to maintain than regular reactors. But using TRISO fuel (or TRISO with uranium 238 cores) can massively help with this, making FBRs a viable option.

So TRISO fuel can help us recycle nuclear waste, which in turn can reduce the carbon footprint and environment of nuclear fuel mining and manufacturing, making nuclear power even kinder to the planet than it already is.

Finally, TRISO can make nuclear waste management far easier. Once spent nuclear fuel comes out of a reactor, it needs to be processed and turned into a more stable form, then encased in nearly indestructible caskets before being safely buried away. Well, TRISO fuel is already in a stable form and in nearly indestructible caskets. As such, managing nuclear waste from TRISO fuel has the potential to be safer, better for the environment and cheaper.

So TRISO seems to be able to solve all of nuclear power’s shortcomings and even subdue any unfounded fears of nuclear incidents.

There is only one problem with TRISO fuel; it doesn’t have regulatory approval yet. This isn’t from any safety concerns but more the fact that this technology is relatively new, and regulators haven’t set out the standards for which TRISO fuels, and the processes around using them, need to meet.

But that is about to change. The US and Canadian nuclear regulators recently released a joint report establishing a common regulatory position on TRISO fuel. This gives TRISO developers a pathway to get their revolutionary fuel into the market.

This is especially good news for US-based X-energy, which the NRC (US nuclear regulatory body) has selected to deliver a commercial TRISO fuel fabrication facility and a TRISO-fueled SMR nuclear power plant by 2027. This report allows them to finalise their design and procedures with just enough time left for them to test, build and deliver on this breakthrough project.

So, by the end of the decade, TRISo nuclear fuel, TRISO-fueled SMRs, and possibly even nuclear waste TRISO-fueled FBRs could kick-start a new era of nuclear power. One where the cost per kWh is on par with some renewables, where deployment time is measured in years, not decades, with sky-high safety standards, the ability to recycle spent nuclear fuel and where the environmental impact of nuclear power is even smaller than it is today. If TRISO can deliver on this promise, then it can help revive the planet-saving nuclear industry, bat back the nuclear naysayers and help us reach net-zero.

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Sources: World Nuclear News, NRC, Energy.gov, ZME Science, X-energy, CNBC, Will Lockett, Will Lockett, Study.com, Fairewinds, Carbon Brief, Visual Capitalist, World Nuclear Association