The Most Important Nuclear Reactor (That You’ve Never Heard of)

by Matt Loszak , Founder and CEO of Aalo Atomics .

The MARVEL micro-reactor from Idaho National Lab (INL) is about to make history, and most people have never heard of it.?

What’s so special about this reactor?

MARVEL will be the first new advanced (non-water-based) reactor built in the US in decades. As of October 2023, it became the first reactor ever to be authorized by the DOE. Construction will be completed this year, and it may well mark the dawn of the Second Atomic Age.?

Why is MARVEL helpful? Don’t we already have lots of great nuclear reactors around the world?

Historical Context

To understand the significance, let’s rewind back to the First Atomic Age.?

In the 1950s and ’60s, 52 test reactors were built and tested at INL. All types of reactors were experimented with, involving a variety of fuels and coolants.

The result of the First Atomic Age was the 400+ nuclear power plants that we have around the world today. These plants provide clean, safe, and reliable base-load energy for millions of civilians.?

Unfortunately, nuclear fell out of favor in the 70’s and 80’s. Decarbonization was less of a priority. Nuclear energy was wrongly classified by activists as being tied to nuclear weapons. The nuclear industry lost momentum, and innovation plateaued. The number of active test reactors at INL fell to just 4, as of today.?

It’s worth elaborating on a subtle point here: People were afraid of nuclear energy before any of the 3 well-known incidents (Three Mile Island in March 1979, then Chernobyl in 1986, and Fukushima in 2011).?

As an example, the China Syndrome movie came out 12 days before the Three Mile Island incident (a wild twist of fate) and had of course been in production for a few years prior. This was an anti-nuclear movie and was largely inspired by activists who were trying to abolish all things nuclear; both the energy source and the weapon.?

We can try to understand this by putting ourselves in the shoes of people who witnessed the atomic bombs, and the understandable unwillingness to accept that nuclear energy and the weapon could be entirely different things. This was also an era of deep mistrust in scientific authority and government. Militaries globally had conducted reckless nuclear weapons testing and waste disposal. For example, in 1962 up to 140 open-air nuclear weapons tests were conducted by the US and the Soviet Union.?

Meanwhile, throughout the 60s and 70s nuclear energy had been providing reliable clean power at prices (in some places) even cheaper than coal. Moreover, the energy industry’s waste had been exceptionally safely maintained. There is no record of nuclear waste from civilian power ever harming anyone. But society still felt mistrust and uncertainty around how bad a worst-case accident could be.?

Today, we know that after 18,000 reactor years of experience, nuclear energy is statistically just as safe as solar or wind. In the past 5 years, nuclear acceptance has been rapidly improving. We now have more concern about climate change, and we’re taking a more pragmatic, clear-sighted look at the energy technologies that can make the biggest difference in the energy transition. We may finally be seeing nuclear energy for what it is: An incredible tool for decarbonization, civilizational growth, and human flourishing.?

Most of the reactors that resulted from the First Atomic Age chose pressurized water as the coolant. But there was a class of “advanced” reactors that were tested in the First Atomic Age as well. Next, we’ll explore how these reactors could hold the key to unlock a future of ubiquitous nuclear energy.?

The Promise of Advanced Reactors

Advanced reactors use coolants other than water such as liquid metals, molten salts, or high-temperature gasses. These are a little trickier to deal with, but offer several advantages in return:?

• More ”inherent” safety is achieved, improving economics. For example, many advanced reactors operate at atmospheric pressure, which significantly simplifies the safety systems. Traditional reactors generally operate at very high pressures, with complex safety systems.??
• Simplified reactor designs are more well-suited to mass manufacturing. This has never been attempted at the scale of hundreds or thousands of reactors, which could significantly reduce costs.?
• Higher temperatures can be reached, improving efficiency and helping to decarbonize industrial heat applications. While pressurized water maxes out around 300 C, advanced reactors can output 400 - 900 C.?
• Some advanced reactors can “breed” more fuel. This will effectively increase the lifespan of nuclear fuel on Earth from one hundred years to several billion.?

Why don’t we see more advanced reactors around the world today? Some people believe that water-based reactors are the most widespread for good reason. Many advanced reactors that were built in the First Atomic Age had maintenance issues (not safety related) that led to poor reliability. But proponents of advanced designs posit that these are solvable problems, and well worth the extra effort. By leveraging modern engineering approaches, we may now be able to unlock the full potential of this class of reactor.?

So, how does MARVEL fit in?

Enter, MARVEL

MARVEL is an advanced reactor, but it has several unique traits that could make it the basis of a revolution in energy infrastructure. It uses liquid metal (NaK) for cooling, and Uranium Zirconium Hydride (UZrH) for fuel. These two design decisions offer standalone advantages, but unlock extra benefits when paired together:

1. Liquid-metal-cooled reactors have the potential to be very economical, compact, and “walk-away-safe” (see EBR-II). They run at atmospheric pressure, which (as mentioned) reduces the complexity and cost of safety systems.?

1. UZrH is a fascinating fuel with a standout safety trait: The hotter it gets, the less reactive it gets, helping to prevent meltdown. This fuel is commonly used in research reactors (on university campuses!) due to its high level of safety.

You might be wondering: Why hasn’t this fuel been used in civilian nuclear power plants? It turns out that it’s too “finicky” to pair with water as a coolant at high temperature: The fuel turns itself off too easily. But liquid metal makes for a beautiful pairing because it can take the heat away quickly enough to unlock the full power of this fuel while maintaining strong inherent safety.?

This makes MARVEL a nice platform for commercialization: It achieves incredible inherent safety, to the point where it could be located right on a university campus, and yet can achieve excellent power density, leading to strong cost-reduction potential in power production.

Aalo and the Second Atomic Age

MARVEL is a small (100 kWt) government test reactor that was intended to help accelerate US nuclear companies who can leverage its data or elements of its design. Aalo is one company that is leveraging this technology base and expanding upon it. The Aalo-1 will be a scaled-up (10 MWe, 30 MWt) reactor inspired by MARVEL. It will be factory-fabricated to offer rapid, predictable, and economical deployment.?

Initial Aalo-1 customers will use its power and heat to decarbonize their data centers, chemical plants, and various processes throughout the oil and gas industry. Eventually, Aalo will scale the technology further for use at utility scale.?

Once construction finishes, MARVEL will help solve a riddle that has challenged the industry for decades: Regulators won’t license your new advanced reactor without nuclear test data, but you can’t get that test data without a licensed reactor. Aalo plans to address this by leveraging MARVEL’s nuclear test data, and combining it with data from full-scale, non-nuclear Aalo-1 prototypes.?

It is a cruel twist of fate that nuclear energy, a technology that could be playing such a large role in solving so many of today’s most pressing challenges, is a technology that was invented decades ago and has since sat on the sidelines, widely misunderstood.

Fortunately, the tides of societal perception have been changing, and nuclear acceptance is now at record highs. The Second Atomic Age may well be upon us: Immediately following MARVEL, several other advanced reactors will be scheduled for completion at INL before the end of the 2020s. These new reactors will offer a modern take on high-potential ideas first explored over 50 years ago.?

In closing, the global decarbonization challenge requires all the feasible technologies we can get our hands on. MARVEL stands at the forefront of the Second Atomic Age. With promises of enhanced efficiency, safety, economics, and prolonged fuel life, Aalo's development of the Aalo-1 will make strides to carry the torch and further advance nuclear technology. As global acceptance of nuclear power rises and progress in advanced reactors accelerates, we hope this Atomic Age is here to stay.