MIGHTR: Speeding Construction of New Nuclear Plants to Help Decarbonize the Economy

Nuclear Power Plant Construction

Nuclear Power Plant Construction

Waging a Two-Pronged Campaign Against Climate Change

With MIGHTR, MIT PhD student W. Robb Stewart aims to speed construction of new nuclear plants to help decarbonize the economy.

If nuclear energy is to play a pivotal role in securing a low-carbon future, researchers must not only develop a new generation of powerful and cost-efficient nuclear power plants, but provide stakeholders with the tools for making smart investment choices among these advanced reactors. W. Robb “Robbie” Stewart, a doctoral candidate in the MIT Department of Nuclear Science and Engineering (NSE), is working on both of these problems.

“Capital construction and operational costs are limiting the nuclear industry’s ability to expand at this critical moment, and if we can’t reduce these costs then nuclear doesn’t have a chance of being a big player in decarbonizing the economy,” Stewart says. “So I decided to focus my thesis research on an estimating tool that quantifies the costs of building a nuclear power plant, and which could be useful for assessing different reactor designs,” he says.

This precision cost-modeling method helps inform an ambitious project that Stewart has been pursuing alongside his dissertation work: designing and building a modular, integrated, gas high-temperature nuclear reactor, called MIGHTR, along with Enrique Velez-Lopez SM ’20. “Our entire thesis … is that we have to simplify the civil construction elements of the project,” says Stewart

Robb Stewart

Passionate about addressing climate change, W. Robb Stewart is working to build a modular, integrated, gas high-temperature nuclear reactor, called MIGHTR. “I wanted to be able to look back at the point of retirement and say I dedicated my engineering time and knowledge to this big problem,” he says. Credit: Gretchen Ertl

Costly infrastructure

Both Stewart’s doctoral research and his own reactor development are motivated to a large degree by a central concern: “Managing the construction of massive nuclear plants is extremely difficult, and too likely to result in cost overruns,” he says. “That’s because we don’t do enough of this kind of construction to be good at it.” In the United States, the key challenge to launching new commercial plants is not regulatory delay or public resistance, but inefficient construction practices, he believes.

Stewart views overcoming nuclear’s daunting building costs as paramount in the drive to bring more plants online in the near future. His modeling tool will make this more likely through precise estimations of construction risks and associated expenses — all based on actual U.S. Department of Energy data on the costs of thousands of items required in commercial reactors, from pressure vessels and fuel to containment buildings and instrumentation.

This rigorous method of quantifying costs is aimed at smoothing the way to the next generation of nuclear reactors, such as small, modular nuclear reactor (SMRs). This type of advanced nuclear reactor can be fabricated in an economically desirable assembly-line fashion, and fit into sites where larger facilities would not. Some SMRs like MIGHTR will also be able to operate at higher temperatures. This attribute makes them uniquely suited for powering industrial processes that are currently served by greenhouse-gas-emitting fossil fuel plants.

Commercial (typically light water) nuclear reactors supply nearly one-third of the world’s carbon-free electricity. But they must operate at temperatures that do not generally exceed 300 degrees Celsius (572 degrees Fahrenheit), which means they cannot generate the heat required for petrochemical manufacturing and other power-hungry industrial needs. In contrast, next-generation reactors such as MIGHTR could turn the temperature dial up to 700 °C (1,300 °F) and beyond. “Industrial process heat accounts for 10 percent of greenhouse gas emissions, so an important criterion for selecting an advanced reactor would be whether it can meet the need of decarbonizing industries,” says Stewart.

His modeling tool could help determine which advanced nuclear designs offers the best investment bet. For example, some SMRs might require 30 million work-hours to build, and others 8 million. Some facilities might involve technological uncertainties that make them too much of a gamble, no matter how much electricity or heat they purport to deliver. Investors, utilities, and policymakers must feel confident that their decision strikes the optimal balance of desired reactor attributes and applications with the reactor’s risk and price tag. “Not all SMRs are equally cost-competitive, and assessment can help distribute resources much more effectively,” he says.

Modeling new technologies

Stewart, who grew up in Dallas, Texas, gravitated early toward cutting-edge technologies with the capacity to serve society. “I knew I wanted to be an engineer from a young age, and loved reading pop culture science trying to understand what the next generation of cars or jet engines might be,” he recalls.

Although tempted by aerospace studies, he found his groove in mechanical engineering as an undergraduate and then master’s student at the University of Texas at Austin. His master’s thesis on heat transfer in gas turbines led directly to work with GE Global Research. After four years spent on ventures to improve cooling efficiencies inside gas turbines, and then to model and predict the life of commercial jet engines, he grew restless.

Over the years he’d felt a mounting concern about the dangers of climate change, and a growing desire to train his engineering expertise on the challenge. “I wanted to be at the forefront of a new technology, and I wanted to be able to look back at the point of retirement and say I dedicated my engineering time and knowledge to this big problem,” says Stewart. So he decided to leave his mechanical engineering career and learn a new discipline at MIT. He quickly found a mentor in Koroush Shirvan, the John Clark Hardwick (1986) Career Development Professor in NSE. “He seemed to be solving problems the nuclear industry was facing, from operational and capital costs, to new fuel and enhanced safety designs,” says Stewart. “That resonated with me.”

MIGHTR drew from the kind of multidisciplinary perspective championed by Shirvan and other members of the department. Other designs for high-temperature gas reactors envision housing components in a structure 60 meters (200 feet) tall. Stewart and his partner thought it might be simpler to lay the entire structure flat, including the reactor core and steam generator. Building height leads to great complexity and higher construction costs. The flat design leverages cost-efficient building techniques new to nuclear, such as precast concrete panels

“We took our idea to a faculty meeting, where they threw stones at it because they wanted proof we could reduce the building size five times less than other HTRs without affecting safety,” Stewart recalls. “That was the birth of MIGHTR.”

Stewart and Velez-Lopez have since launched a startup, Boston Atomics, to bring MIGHTR to life. The team’s design filed a patent last October and received a $5 million grant in December from the U.S. Department of Energy (DOE)’s Advanced Reactor Design Program. MIT is helping drive this venture forward, with Shirvan overseeing the project, which includes partners from other universities.

Stewart’s creation of the nuclear plant cost modeling tool, sponsored by the Finnish energy company Fortum, and co-invention of the MIGHTR design have already won recognition: His research is headed for publication in several journals, and last year he received NSE’s 2020 Manson Benedict Award for Academic Excellence and Professional Promise.

Today, even as he presses forward on both MIGHTR and his cost-modeling research, Stewart has broadened his portfolio. He is assisting the associate provost and Japan Steel Industry Professor Richard Lester with the MIT Climate Grand Challenges Program. “The goal is to identify a handful of powerful research ideas that can be big movers in solving the climate change problem, not just through carbon mitigation but by promoting the adaptation and resilience of cities and reducing impacts on people in zones experiencing extreme weather-related conditions, such as fires and hurricanes,” says Stewart.

After picking up his doctorate next year, Stewart plans on dedicating himself to Boston Atomics and MIGHTR. He also hopes that his modeling tool, free to the public, will help direct research and development dollars into nuclear technologies with a high potential for reducing cost, and “get people excited by new reactor designs,” he says.

9 Comments on "MIGHTR: Speeding Construction of New Nuclear Plants to Help Decarbonize the Economy"

  1. And yet… no mention of the radioactive elephant in the room.

    • For a country like France, the entire radioactive waste of the electric grid 80% powered by nuclear would fit in a soccer field and yet it can still be used as fuel in breeder reactors.

      Next door in Germany which has partially switched from nuclear to coal to power its green grid, the entire CO2 emmisions as a solid would require millions of times more space if it could even be captured, it can’t. German RE has not made a dent in their CO2 emmisions because of the shutting down of so many reactors. If they shut down the rest, the CO2 can only go up.

      The fossil fuel industry loves every anti nuclear person out there, they love renewabale energy too, because even if REs lower the demand for fossil energy a bit, the split remains strongly in fossil fuels favor something like the best case is 20% RE with 80% fossil fuel. You do know the sun only has an avg capacity factor of 14% across the US and EU, while wind is max of %30. That means the remaining 80% or so must be filled by fossil fuels, storage or nuclear.

      That is unless you solve the enrgy storage problem but you wouldn’t believe what that involves. Storing electrical energy is 1000s times the cost of storing chemical energy.

      Here is a thought experiment, a nat gas powered economy with solar and wind mixed in vs a more advance nat gas plant with no RE allowed. Which one produces more CO2, the answer is no 1 because it requires using less efficient interuptable gas burners at 40% eff while the advanced nat gas can burn at 60% eff in closed cycle systems. And in oxygen even 70% eff and we had oxygen for free, at 80% eff and the CO2 that is produced could at least be easily captured since it is never in the air stream.

      Ever noticed who puts up the RE adverts for wind and solar in prime time news, BP or British Petroleum, they love all the RE business they can get. It makes them look good, but they never tell the viewer that in a wind farm, 72% of the energy is gas powered, it even says so on the website for ridgement wind.

      So yea remember the fossil fuel industry thanks you for all your excellent work keeping them in business.

  2. stephen schaffer | July 16, 2021 at 8:11 am | Reply

    Great puff piece from a sympathetic publisher. sure, let’s make it more cost effective to poison everyone on the planet. currently, we can’t even recycle 90% of our waste – what about radioactive “waste?”

  3. Geoffrey Cole | July 16, 2021 at 9:09 am | Reply

    As for radioactive elephant, the difference is between the possibility of a nuclear accident vs the certainty of global warming. The equivalent of playing Russian roulette with 1 bullet in the magazine vs playing with a full one.

  4. Ridiculous uninformed article ego massaging this guy. With the recent breakthroughs and development nuclear fusion is the only nuclear energy worth talking about and investing in, fission reactors are outdated and already obsolete, unreliable and not safe.

    • Its amazing that people can love fusion but loath fission, they must be quite ignorent of the basic physics involved in both.

      The fundamental physics underlying both is quite similar, both involve beta decay either negative or positive. For fission reactors that breed uranium 238 into plutonium, neutrons must decay into protons ejecting an electron from the nucleus, which allows for the plutonium to fission. For stellar fusion, protons must decay into neutrons so that helium can be made from hydrogen ie protons, which means they incorporate an electron and eject an antimatter electron or positron, then the newly made deuterons can fuse into helium 3 then 4. The math is almost the same but negative signs.

      Also most fusion reactors are going to create large amounts of neutron radiation which will irradiate the reactor chambers containing the plasma, there is no way to easily build fusion systems that don’t do that. A lithium blanket will have to be added that will help produce tritium for fuel.

      If I had a $T to build as many fission or fusion reactors as possible, the fission reactors using molten salt could be built today quicky and farely priced, we have known how to do this for 50 years. For fusion, its always stuck in the 50 years future. The ITER project in the south of France will cost well over $20B and will not even be remotely net energy return. Fusion will work fine when it is already far to late for climate change. In a 1000 years or so we will start to run out of uranium/thorium, only then will we have to switch to deuterium which should last till the earth gets fried by the sun.

      The engineering problems with fusion are several orders more challenging than fission, achieving 100,000,000C vs 700C is always going to require the talent of thousands of scientis vs a relatively small team.

      The irony is that both are just devices to make heat, the ideal coolant for both is the molten salt loops storing heat in tanks for thermal industrial use or electric generation. For MSR, its only neccesary to add fission material to the inner salt loop in a fuel rid. For fusion generating plasmas and the containment is a whole other game of science with cryo magnetics, plasma chambers, it never ends.

      I have only studied both for 50 years or so as an observer, but I’d pick fission to solve climate change today and invest in fusion research on the side.

  5. Once a chain reaction occurs, the decay of matter cannot be stopped! The radioactive decay of millions of tons of high activity (level) IS HEATING THE PLANET, and will be for millions of years! Fukushima was TEN reactors, 30 or more if you count the huge WASTE POOLS AND THEIR CONTENTS BOILED AWAY INTO THE ATMOSPHERE. In one year we built the equivalent of 300 reactors as renewable energy! Nuclear energy is dead, as dead as the greatest food source on earth, the Pacific ocean. Several hundreds of tons of plutonium were released from Fukushima,according to a Jap nuclear expert. The 4th horseman has poured out his vial. Invisible death stalks the earth, while the reactors hemorrhage into the environment!

    • And everything you just said was a load of utter codswallup.

      Why not read an actual book on energy, like say “Without the hot air” by Dr David Mackay, a physicist that explains everything about energy in terms an educated person should be able to understand. It’s free to download as a PDF, and explains the difficulties and facts of all energy systems.

  6. It does seem as though MIT gets away with a lot of these friendly puff pieces, shame. I’d rather hear about this fellow in 20 years time after he has had a major impact on the industry he wants to serve.

    It brings to mind another MIT started reactor company that eventually folded called the WAMSA. Proposed by 2 more very young physicists who also got lots of puff pieces but could never actually build anything with a nuclear reaction in it because that is essentially illegal in the US.

    Most of the giants in physics & science don’t get written up until well after their deaths.

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