“Nuclear batteries” offer a new approach to carbon-free energy



This cutaway render of MIT’s nuclear battery concept shows important components such as the I&C module, reactor, and power module. Credit: Courtesy of the researchers

Jacopo Buongiorno and others say factory-made microreactors trucked to use sites could be a safe and efficient option to decarbonize electrical systems.

We may be on the brink of a new paradigm for nuclear power, a group of nuclear experts recently suggested. in Le Pont, the journal of the National Academy of Engineering. Just as large, expensive, centralized computers have given way to today’s widely distributed PCs, a new generation of relatively small and inexpensive factory-built reactors designed for stand-alone plug-and-play operation similar to plugging in devices. ‘an oversized battery is on the horizon, they say.

These proposed systems could provide heat for industrial processes or electricity for a military base or neighborhood, run unattended for five to 10 years, and then be trucked back to the factory for refurbishment. The Authors – Jacopo Buongiorno, TEPCO Professor of Nuclear Science and Engineering at MIT; Robert Frida, founder of GenH; Steven Aumeier of the Idaho National Laboratory; and Kevin Chilton, retired commander of US Strategic Command, have dubbed these small power plants “nuclear batteries”. Because of their simplicity of operation, they could play an important role in decarbonizing global power systems to prevent catastrophic climate change, the researchers say. MIT News asked Buongiorno to describe his group’s proposal.

Question: The idea of ​​smaller, modular nuclear reactors has been debated for several years. How is this nuclear battery proposal different?

A: The units we describe take this concept of factory manufacturing and modularity to the extreme. Previous proposals were for reactors with an electrical output of between 100 and 300 megawatts, which is a factor of 10 smaller than traditional big beasts, large nuclear reactors at the gigawatt scale. These could be assembled from factory-made components, but they still require some site assembly and a lot of site preparation work. So, this is an improvement over traditional plants, but not a huge improvement.

This concept of a nuclear battery is really different because of the physical scale of these machines – around 10 megawatts. It is so small that the whole plant is actually built in a factory and fits in a standard container. The idea is to install the entire plant, which includes a microreactor and a turbine that converts heat into electricity, in the container.

This offers several advantages from an economic point of view. You completely decouple your projects and technology from the construction site, which has been the source of all the schedule delays and possible cost overruns for nuclear projects over the past 20 years.

In this way, it becomes a kind of on-demand energy. If the customer wants heat or electricity, they can get it in a matter of months or even weeks, and then it’s plug and play. This machine arrives on site, and a few days later, you start to refuel. So it’s a product, it’s not a project. That’s how I like to characterize it.

Question: You talk about potentially having such units widely distributed, including even in residential areas to supply entire neighborhoods. How confident can people be that these plants are safe?

A: It’s exceptionally sturdy – that’s one of the selling points. First of all, the fact that it’s small is good for a variety of reasons. On the one hand, the overall amount of heat generated is proportional to the power, which is low. But more importantly, it has a high surface area to volume ratio because, again, it’s small, which makes it much easier to keep cool under all circumstances. It’s passively cooled, to a point where no one has to do anything. You don’t even have to open a valve or anything. The system takes care of itself.

It also has a very robust containment structure that surrounds it to protect it from any radiation release. Instead of the traditional large concrete dome, there are steel shells that essentially encapsulate the entire system. And when it comes to safety, at most sites we expect these would be located below ground level. This provides some protection and physical security against external attackers.

As for the other safety issues, you know, if you think of the famous nuclear accidents, Three Mile Island, Chernobyl, Fukushima, those three issues are mediated by the design of these nuclear batteries. Because they are so small, it is fundamentally impossible to get this kind of result from a sequence of events.

Question: How do we know these new types of reactors will work and what would it take for these units to become widely available?

A: NASA and the Los Alamos National Laboratory carried out a similar demonstration project, which they called a microreactor, for space applications. It only took them three years from start of design to manufacturing and testing. And it cost them $ 20 million. It was orders of magnitude smaller than traditional large nuclear power plants that easily cost over a billion and take a decade or more to build.

There are also different companies currently developing their own designs, and each is a little different. Westinghouse is already working on a version of these nuclear batteries (although they don’t use that term), and they plan to operate a demonstration unit in two years.

The next step will be to build a pilot plant in one of the national laboratories that has full equipment to test nuclear reactor systems, such as the Idaho National Laboratory. They have a number of facilities that are being modified to accommodate these microreactors, and they have additional levels of safety. Because this is a demonstration project, you want to make sure that if something happens that you didn’t expect, you won’t have any release to the environment.

Then the plant could go through an accelerated program of tests, subjecting it to more extreme conditions than those encountered during normal operation. You essentially abuse it and show through direct testing that it can withstand all of these external loads or situations without exceeding failure limits. And once this is proven under harsh conditions, large-scale commercial installations could begin fairly quickly.

These nuclear batteries are ideally suited to create resilience in very different sectors of the economy, providing a stable and reliable source of energy to support the growing dependence on intermittent renewable energy sources such as solar and wind power. And, these highly distributed systems can also help alleviate grid pressures by being located right where their output is needed. This can provide greater resilience against any network disruption and virtually eliminate the problem of transmission loss. If these become as widespread as we envision, they could make a significant contribution to reducing greenhouse gas emissions around the world.

Reference: “A Strategy to Unlock the Potential of Nuclear Energy for a New and Resilient Global Energy-Industrial Paradigm” by Jacopo Buongiorno, Robert Freda, Steven Aumeier and Kevin Chilton, June 14, 2021, The bridge.

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