TerraPower: How The Traveling Wave Nuclear Reactor Works


When Microsoft Chairman and billionaire philanthropist Bill Gates mentioned TerraPower in his speech at the exclusive tech conference TED last week, it was the first time that many had heard of the nuclear project. I was monitoring Twitter during Gates’ talk and many audience members at TED tweeted wondering why “TerraPower” was getting special attention in a speech from one of the most famous computer technologists of all time.

Well, first off TerraPower is a nuclear spinoff project from incubator Intellectual Ventures. Former Microsoft chief technology officer Nathan Myhrvold founded Intellectual Ventures, and Bill Gates is a principal owner of TerraPower. TerraPower uses a “traveling wave reactor design,” which is technology that has been researched since the 1990’s, but according to MIT Tech Review TerraPower is the first company to “develop a practical design,” for travelling wave nuclear reactors.

There’s been a lot written about TerraPower over the past few years, and the company has done a good job of explaining how travelling wave reactors work in these videos on its incubator website. TerraPower’s President John Gilleland explains the process in one video as a new type of nuclear reactor that can provide an infinite amount of power, and unlike the current reactor design that uses only enriched uranium for fuel, TerraPower’s reactor largely uses waste byproduct of that enrichment process, or waste uranium.

TerraPower uses a small amount of enriched uranium at the beginning of the process (see slides at the bottom of the post), but then the nuclear reactor runs on the waste product and can make and consume its own fuel. The benefits are that the reactor doesn’t have to be refueled or have its waste removed until the end of life of the reactor (theoretically a couple hundred years). Using waste uranium reduces the amount of waste in the overall nuclear life cycle, and extends the available supply of the world’s uranium for nuclear by many times.

Not surprisingly, with its Microsoft connection, TerraPower has leaned heavily on supercomputing to design and model the reactor and the lifecycle of the fuel. The TerraPower team is using “1,024 Xeon core processors assembled on 128 blade servers,” which is a cluster that is “over 1000 times the computational ability as a desktop computer.” On Intellectual Venture’s site, they explain the importance of computer modelling as:

Extensive computer simulations and engineering studies produced new evidence that a wave of fission moving slowly through a fuel core could generate a billion watts of electricity continuously for well over 50 to 100 years without enrichment or reprocessing. The hi-fidelity results made possible by advanced computational abilities of modern supercomputer clusters are the driving force behind one of the most active nuclear reactor design teams in the country.

How close to reality is this technology? According to this presentation by Gilleland, “operation of a traveling wave reactor can be demonstrated in less than ten years, and commercial deployment can begin in less than fifteen years.”

So, that’s what Gates was talking about.

Images courtesy of TerraPower.



Great nice to hear of that we can get other source of energy which it big help for us today we need that energy for the progress of all nations.


Looks very interesting, I’m excited to see where this goes! Hopefully it’s safe.


I understand that Secretary Chu is well aware of this. It is so incredibly refreshing to see an energy secretary that can lead from a position of knowledge.

Our last administration’s energy policy was to behave like a junky and invade the Middle East in order to secure more of a dwindling resource rather than using that same wartime investment mentality to come up with a permanent solution. VP Cheney famously said that ‘the American way of life is non-negotiable,’ basically saying that driving alone in giant SUV’s was our birthright. Well, in a world with limited oil reserves, eventually a new negotiating partner shows up: his name is reality. When that happens, you don’t even need to be in the room anymore.

Meanwhile, humanity continues sleepwalking toward converging catastrophe’s: Global Warming and Peak Oil. Both will require decades to fix, some luck and a couple of technological ‘miracles.’

We’re unlikely to avoid a chaotic transition away from oil, unfortunately, as it appears we may already have passed the global production peak of 85M bbl/day. Traveling wave, however, may help us avert some of the worst-case scenarios from Global Warming.

For the sake of my daughter due in August, I’ve got my fingers crossed.

albert the skeptic

Most of the objections to nuclear power were answered in an article, long ago, by the astrophysicist Fred Hoyle. It was written as if the dominant energy technology was nuclear fission, and it warned in horrific detail about the poisonous gases released by the proposed new coal burning plants, and the enormous quantities of solid (and even radioactive) waste for any given amount of electricity.

I have two small problems with the TWR. One is, that I don’t believe proprietary enterprise can be trusted with what, if it succeeds, will be as dominant a technology as coal was before it was ousted by oil. France has a very successful nuclear program (over 75% of their electricity) and nuclear power has unaccountably waned in Britain since the Thatcher regime privatised it.
The other problem is, that the Integral Fast Reactor project seems to me to have solved all the known and alleged problems of breeder reactors about twenty years ago. It was designed both to produce and consume plutonium, and its waste was about a thousand times more short-lived than current reactors, and a hundredth of the quantity per gigawatt-year of energy produced.
This is pretty impressive when you note that, not counting the carbon dioxide, coal produces hundreds of times as much poison per kilowatt-hour as nuclear power plants, and belches it into the air!

There is enough uranium oxide in the ash from the production of a gigawatt-year of electrical energy using coal, to provide more than a Gw-yr if it were fed to a breeder reactor. And there’s also about three times as much thorium, which can also be made fissile in such a reactor!
See my website http://skepticva.org, which has links to Frontline and to some archives at U.Cal, Berkeley.

Roy Fileger

I was amused at the description of the “Supercomputer” in the article. Equivalent to 1000 desktops. A Sony “PlayStation” is equivalent to several hundred desktops. Today’s SuperComputers are more than a 1000 times more powerful that 1000 desktops.


This design has a huge problem, they depend on uranium that is way more pure than anything that can be produced today, so…

Pat Hegarty

How would TWR be controlled once started ?

My first impression is that once it starts the heat output will be whatever evolves. Can it be shutdown if a problem developes ? While redundant systems can be added they will not be fool proof.

albert the skeptic

I thought so too, fifty years ago.er
But the technology is fiendishly difficult to develop.
I gave it up when I realized that the algebraic calculations for a simple two particle collision, done to better than a first degree ahapproximation, were near-prohibitively laborious to get right. Perhaps a computer could do it. My career has therefore been in computer science instead.

Fusion research in the USA has been essentially defunct since Tsongas left the Senate because of ill health.

By the way, do you realize that a mouse-sized volume of the Sun’s core emits far less heat (or energy) than a living mouse-sized mouse?

Please do not confuse uranium with coal and oil as a fossil fuel. It is not a product of our little star’s activity. It was part of our Solar System’s original dust cloud, and probably came from one or more supernovae.


As always, the devil is in the detail. We have private money being invested So let them get their engineers to work, take the emotion out of the equation and let’s see what they can do.


While watching Bill Gares speech on TED, I was thinking that he isn’t very familiar with renewable energy, energy efficiency and new concepts around it. His speach was very basic with no new insights. There are many visionaries and practitioners out there that are already behind the early stage of grasping the energy problem and proposing new models AND implementing them for the future.

First: Energy Efficiency can lower our energy use by 70%. House stock: Passive houses (www.passivhouse.us) use 90% less energy than a energy star rated homes (without PV). This applies also to house retrofits. Transportation: A Tesla electric car is only using 2500kWh/y. Smaller Models will use even less. Industrial Sector: I have to admit that I’m not that familiar with the industrial sector. But I think we can achieve huge reductions in the energy use of industrial processes and facilities.

Second: renewable energy CAN deliver all the energy the world needs, but only after energy efficiency was deployed. This however doesn’t mean that we have to wait to install let’s say wind already today.

Third: If Terra Power is able to deploy a working model of it’s new reactor model, fine, why not. It’s not forbidden to make money in a capital market. Everything that doesn’t produce CO2 is welcome. Some people still want to buy power from a utility.

Fourth: Thinking that storage of renewable energy isn’t possible is an error often made. Storing it in batteries is indeed a bad idea. But in germany studies have shown that combining wind-, biomass-, water- and solar-plants can provide 100% of the energy needed all the time. For more details see: http://www.unendlich-viel-energie.de/de/strom/detailansicht/article/165/the-combined-power-plant.html Solar thermal plants can store energy in molten salt storage for up to 12 hours.

So please, don’t try to slow the deployment of renewables by repeating old ideas. I was expecting more from one of the most famous technology inventors of our century!


your final statement should just be deleted if that rationalization held true we would all still be buying model T’s and large passenger planes would still have 4-6 prop motors… and lets not forget things that have essentially been the same concept for millenia that have been refined for eons iron to steel… non corrosive alloys. fission frees up our resources to focus on the true trophy which is sustainable fusion.

folks like you were saying the same things to the wright bro’s its an “old idea that can never be achieved” thank goodness scientist/engineers dont unthink idea’s like your trying to

Thomas Jørgensen

Under a fast breeder regime (and a traveling wave reactor is a fast breeder), uranium is not a meaningful constraint – in order to use up earths uranium reserves in less than hundreds of thousands of years, we would have to use energy on such an insane scale that the crust would melt from the waste heat.


Correct me if i’m wrong but isn’t uranium a finite resource? What do we do when we’ve burnt it all up?


Fission reactors are unsafe, because they produce toxic radioactive wastes, and neutrons for breeding plutonium for production of nuclear weapons. I think the aneutronic reactor is safer, cleaner and cheaper, as it doesn’t emit neutrons, and can produce electricity efficiently.

minho seo

I’m curious as to how exactly this travelling wave reactor converts the fission reactions to outputtable energy, seeing as how they claim an ouput of a billion watts of electricity over 100-150 years and how this new model compares to the current method of energy production. I also wonder what exactly they are using for coolant and to control the rate of fission.


OH yeah i did not get my 2 bits worth in yet >>>
that people are pushing on the INTERNET where in the hell are they?
And those freaking cars that run on water ?????
If they could lower the cost of installing + cost of solar panels to 50 cents a watt i would buy the system! but NO the USA can’t do this
instead the USA is still mired in politics and bankers that get away with stealing the tax payers money (wait till you get your 39% increase in insurance costs) and your NEW CREDIT CARDS!! One Guy (ex VET)got so fed up he left for NEW ZEALAND.


Mean while why are the CHINESE investing in A 2 GIGAWATT solar farm
and other hi tech battery factories to mass produce batteries and solar
panels that WE (USA) should be doing on every freaking house that can use power for the (electrical infrastructure for the electric cars)that USA will be supposedly made by our auto companies with our $1.6 trillion tax payer dollars (congress over many past years).
DUH! same old crapola! talk is cheap! i will believe IT when my electric bill goes down at least 50%.


Chinese are also building 100 new nuclear reactors. Their power output will dwarf all the solar panels they ever produced.

C Kenny

As with all Nuclear proponents, it negates the most basic realities, the undisputable risks, and the undeniable catstrophic failures. There are no guarenteed safe locations for underground containment (earthquakes, floods, natural and man-made disasters), there are no guarenteed safe disposal methods for any waste by-products (whatever you contain the radioactive material in, eventually becomes radioactive), pumps, piping, machinery, buildings and every process that the fuel goes through to be utilized produces it’s own volume of radioactive waste. This waste is not utilized in this new process, but will continue to be ‘hazardous’ (deadly) for a 100,000 years. Can we guarentee the safety of this? Do we have the right to pass this legacy down to the future of Earth for our own ‘progress’? Why don’t we put all that money being spent into a safe renewable technology and stop throwing good money after bad.

albert the skeptic

Nuclear waste is no more deadly than the oxides of nitrogen and sulfur emitted by burning coal or even methane (gas turbines are fed by natural gas, oxygen and nitrogen) and it’s only the neutron capture products that have half lives in the tens of thousands of years. A fast neutron reactor can consume all of these, leaving only the short lived fission products.

Fast reactors ARE a renewable technology. They renew the stock of fissile nuclides!

M Paul Lloyd

I note that this harks back to a 1996 paper by Teller, Ishikawa and Wood entitled ‘Completely Automated Nuclear Reactors for Long-Term Operation’. Which described a ‘sealed for life’ reactor designed to run on thorium/depleted uranium along fast breeder reactor lines for 30 years without any external intervention.

Current nuclear reactors are simply scaled up versions of the type developed the 1950’s for use in nuclear submarines. They are complicated but reasonably reliable and a known quantity but burdened by a rather unfortunate waste disposal problem. On the other hand this
Wave Nuclear system promises to be very much more environmentally friendly.
To reduce the risk of contamination of the biosphere even further the Travelling Wave Nuclear Reactors structure would (according to the 1996 paper) be located some 100metres underground in a purpose built concrete bunker resting in compacted earth (rock is too unstable) with heat pipes to the electrical generation on the surface and presumably at the end of its working life the reactor would be left in its subterranean tomb where it can do the least harm until all of its fuel is spent.

It all sounds rather wonderful with no moving parts within the actual reactor and an effective fail-safe operation in that reducing power demand lowers the rate of fuel reaction burn. Basically if you don’t use it it just goes into a sort of standby mode. Apparently.

I can find only one small problem with it all.
It has only ever been tested in computer simulations. No one has, as far as I am aware, actually constructed a real life working reactor based on this technology and if it really is such a very feasible concept then why has no one tried it already? After all the technology has been sitting around for nearly quarter of a century and if it works then the potential profits are really quite huge.
I wish Mr. Gates well with this venture but I do wonder if he, or indeed any of us, will ever live to see anything come of it?

H2 Dave

Thank you , Bill, for stepping up to the plate. Thanks for the courage to challenge the Energy Establishment.Nuclear energy has always been our saving grace, and the Public has been so misinformed over the years.
Makes me want to go out and buy Windows 7. Let’s get on with it!


We should invest in all technologies that look promising. And if Bill Gates is willing to use his wallet he should be applauded. We not only need technology to solve our reliance on petrochemicals, but also exportable technology. Equal, if not greater, to the challenge of reducing emissions in the US, is how to accommodate the estimated 400 million people who will enter the middle class from China and India over the next decade or so. There appetite for energy will be ravenous and create demands and strains on all natural resource productions. If you add to that the the world’s population is estimated to increase by about billion every 14 years, to about 9 billion in 2050 – we have the biggest challenge in front of us we could ever imagine. Thank goodness Gates is willing to step forward while our political leaders squabble of who to appoint to what post and have achieved near zero on sustainability policy. Someone needs to step up to the plate and layout the 50 year policy – not the 2 year policy to the next election.

Sam Taylor

Very important questions! Obvious to the developers. They will probably answer these when the time is right.

Bill mentioned something about Disclosure limitations in the interview. First and foremost Bill is a business man, if he is banking on this technology being the correctly motivated (i.e. economically) solution to the 2050 goal, then you better believe he will find a way to make it happen. I am optomistic that this technology will solve some of the problems we face, but pessimistic about solving all of them… personal transport and air transport are much harder.


One of the things invisioned with this technology is the ability to sell it to other countries. This would allow a sealed reactor to be deployed and operate in developing countries with a greatly reduced danger of sensitive nuclear technology and materials being misused.



1) what is the containment vessel made out of?

  • how does this material degrade under decades of fierce radiation;

  • does it, like stainless steel, become brittle and crack?

2) – So you produce heat from Fission;

  • how is this converted to power?

3) – how is this apparatus cooled?

4:) – A runaway fission reaction causing melt down is prevented.. How exactly ??

  • Nice nice idea, much left to be proved before mass implementation begins.

Appears to be much the same promises that were touted for nuclear fusion when it was all the fad. Nice slide show, but where is the physics behind this miracle? Waste is what the reactor has used up or can no longer viably use. So by what process is the reactor waste made viable again for use. How is the slow burned controlled so that it does not burn faster as the wave travels. How can a slow burn provide enough energy to compete with current nuclear fission reactors? Sounds like a lot of hype to me. Tens years of stock investments with no product – sounds like someone is going to make money off of the investors.


Now take names and keep a list of all the Luddites that will line up to oppose this remarkable initiative–The World Trade Organization, the petroleum industry, the coal industry, and, oh, all the politicians, lawyers, accountants and banks that support their interests. Good idea, it just doesn’t stand a snowball’s chance in hell if it really is as effective as Gates believes it to be.


Honestly the oil and gas industry has little to fear from power plant technology.
Who is going to fit that in your car to go to work (those that remember the electric car with all its hopes may also remember that it would only drive about 60 miles the nissan leaf and ford focus electric are estimating 100 miles a charge and the chevy volt is currently posting 40). Though 100 miles on a charge is viable for many commuters, the lack of an infrastucture to re-charge away from your own home greatly limits possibilities. How many people honestly plan every stop of their day prior to leaving the house and have the will to postpone a side trip out with a friend or colleague to avoid being stranded and calling a tow truck to get the last 5-10 miles home.
Airlines cannot function without petroleum. Lets all cancel those vacations and trips to visit family on the holidays if they are not within 40 miles of the house.


I think there are more electric plugs around then there are gas stations. Just bring around an extension cable, you’ll be fine.

David Rubin

I suggest you take a look at the zinc-air “battery” or fuel cell concept. A fuel cell operates using a slurry of zinc, converting it to zinc oxide. The system can be refueled at a station similar to a gasoline station. The spent slurry is extracted and recycled while fresh slurry is supplied. The whole process is not much more complex than the current gasoline refueling process. Lawrence Livermore labs operated a bus with this technology. Toyota is working on it and projects a vehicle by 2020. No hazardous or flammable materials are involved. I believe there may be some real potential for an electric vehicle using this technology.

David Rubin

I guess you would call me a Luddite because I believe in free markets. Since any nuclear power plant operates under the umbrella of protection provided by the Price Anderson Act, it has an effective subsidy that may be very large. Note, the Price Anderson Act allows nuclear power plants to operate without catastrophic liability insurance.


Atleast give a defn of this technology [in the first 2 para] rather than giving links to others who does. But thanks for telling about it.


So, a pilot operation should be put in place by those who can afford it. Meanwhile, the alternatives including 3rd Gen nuclear power [or 4th] should proceed. Other experiments should be supported as well – including all 3 prime fusion experiments.

Most of the world already recycles 95% of spent fuel rods. Only the U.S. dodders along with overpriced storage systems leftover from overpriced boondoggles in the first place.

Bill can afford it.

Alexander V

Yes, yes! Another Perpetual Motion Machine. Because designers will digest the money perpetualy for another hundred years or Gate dies.
The history repeats once again.
Here in Russia some guys develop another idea of the same scale – nuclear reactor with led coolant.
Nobody knows where to find enought led to fill the first circuit and what value the prime cost of kWt will come to.

Jim B

This concept was originally designed by Teller and Lowell Wood at Lawrence Livermore. Brilliant stuff. Note that this is almost as powerful a technology as Fusion energy…it is on that scale of importance. However unlike Fusion, this is really quite feasible.

Kudos to Gates and Mryvold for identifying this and bringing their massive resources to bear.

Could this save the world? Yes.


an we ly have to hold our breath for 10 or 15 years?
line up !!
meanwhile??? Thorium Fluoride might be here by then. Nuke power on a mesh grid is its added benefit due to plant scale.

Whatever can replace oil and coal (nuke dirty coal!!) should get all the support possible.

Hold breath, pray…..


Amazing! with such longevity, and outpout on the scales of “billion watts of electricity continuously for well over 50 to 100 ” Does this mean that this could very well solve our energy problems? Solve as opposed to improve… Simply amazing.


TWR’s are the key to making the earth sustainable at 8 billion people. Fusion is the key to moving out to the moon and mars……

two major milestones in the history of man

Fusion isnt practical now however a reactor of vital importance is being planned and developed at the moment in europe. its also a reactor that has been heavily modeled thru super computer simulations. and in the simulations that have gone on in the last 12 months its a sustainable reaction. which is incredible.

The sooner we can leave the uranium coal and oil in the ground and start sucking our energy out of the vast oceans of water we have the better for the whole of civilization

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