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Can Nuclear Power be Green?

March 1, 2021

Selected material taken from a lecture presented on 24 September, 2019 at San Diego City College.  7,000 words by Rob Morse

What do you know?

When we say, “I’m sure this is true.” we’re saying that we understand the contextual limits of our knowledge. I’m thinking of statements like ‘This food is good for you.’ or ‘This material is appropriate for this use.’ We live and die by knowing if statements like that are true.. except statements can be true in one context and not true in another. Here is an example that happened to me the other day.

I have a friend who I’ve trusted with my life, and I will trust her again. She is completely trustworthy most of the time, but I can not trust her to walk by a French bakery early in the morning.

I hope you have such trustworthy friends.. and that you learn to feed them.

Can she be trusted?

When people say they are arguing about “the facts” they are usually arguing the context of their claims.

Real facts are complicated. We need to know more than what the headlines tell us. In all honesty, if we only know what we are told by the news media, then we are dangerously ill-informed. I’m glad we’re having this discussion at a junior college because context should be the hallmark of education. That is profoundly true for political claims.. like saying a particular source of energy is good for society.

I’ve studied energy and nuclear power and I say that nuclear power can be good. I love that we can make people’s lives better. Let me show you the context of that claim. You should know who I am that I’d make such a statement.

A diverse career

I am an engineer. I worked on nuclear power plants. I worked on coal and natural gas power plants. I worked on the research for fusion powered nuclear plants. I worked on the edge of technology. I’ve physically touched parts that are now on other planets.

I had to be confident about what I knew, and more important than that, I had to know where my confidence stopped. So I’m asking you, where does your knowledge stop? One of the bravest things you can say is, “I don’t know. Let’s find out.” I spent my life living with that confession, that admission of ignorance.

One of the bravest things you can say is, “I don’t know. Let’s find out.”

I’m going to talk about nuclear power in a general way. We’ll use a few simple graphs, but the facts are simple enough to understand for almost anyone. Here is what we need to know.

To talk about nuclear power, we must talk about the facts of life here on earth. We only have a few sources of energy. Our energy comes from the sun, from past sunshine that was stored chemically, or stored energy from previous suns that exploded. That stellar debris was swept into our solar system. The nuclear fuels we use today are the billion-year-old legacy bequeathed to us from those dying stars that are older than our sun.

That raises all kinds of questions-

  • Is this stellar debris rare or is it common?
  • Are the results of nuclear processes dangerous and unmanageable poisons,
    or are they essential for life on earth?
  • How did the earth come to be, and what keeps it going?

A six-year-old asks those sorts of questions. The answers are straightforward, at least at their surface, and you should know them. I already gave you a hint. If these materials under our feet and in our bodies have been around for several billion years then they are extraordinarily stable.

We have to understand where we came from.

This is the periodic chart of the chemical elements you first saw in junior high school. That blue arrow points at iron. Every element that is farther along the periodic table than iron is the remains of a stellar explosion. Those heavy elements don’t come from our sun in any appreciable amount.

We’re talking about elements like iron, zinc, selenium, and iodine. These are essential for life. Your thyroid gland and every cell that reacts to the thyroid hormone needs selenium and iodine. You have iron in every blood cell and muscle cell in your body. Life on earth depends on the heavy elements that came from exploding stars.

There is an underlying claim here as well. Some of this star-stuff is radioactive. Iron is the most stable nuclear element so everything either fusions or fissions toward iron. The universe ends in rust.

In contrast, some heavy elements have an atomic weight that is about four times heavier than iron. That means they have almost four times as many protons as iron and more than four times as many neutrons. These radioactive materials make life possible. Life on earth depends on nuclear decay, but you knew that, didn’t you?

Life on earth depends on nuclear decay!

Life would never have formed if the earth weren’t radioactive. The proof is under our feet.. and in our kitchens. Common materials like granite include the naturally occurring elements uranium and thorium. These elements are both common enough and sufficiently radioactive that their nuclear decay keeps the metallic core of our planet molten. That molten core is why the earth has a magnetic field. That magnetic field keeps our atmosphere from being stripped away by the solar wind. The convection currents in the molten core of the earth also move continents across the surface of the earth. That motion recycles carbon from the deep sea floor back into the environment through volcanism.

If we could somehow turn off all radioactivity, then the earth’s core would cool. Plants on the surface of the earth would run out of CO2, and our atmosphere would bleed away into space. Earth turns into Mars and we die.

You had classes on the environment. Did anyone tell you that the heart of our planet is powered by nuclear decay? Life isn’t a child’s cartoon. It takes more than sunshine and rainbows to make volcanic mountains.

Did anyone tell you that the heart of our planet is powered by nuclear decay?

Does electricity matter anymore?
Look at the thin habitable surface of the earth. Out here, humans lived by muscle power for millions of years. We eliminated human slavery when we made machines and chemical energy do our work for us. Today, we can live in safe, clean, and comfortable shelters because we have cheap, abundant and reliable sources of power. That’s important.

Electricity made us both more moral and more comfortable. The first time we had a billion humans on the earth was in the early 1800s. Today, we have about 7.5 billion people on the planet. Last year, we finally had fewer than a billion people who had to live without access to electric power. That is incredible progress.

Living in a hut with open fires and poor sanitation
is one of the most dangerous environments we have.

Once you have electrical power, you can work and study at night because you have light. You can store your raw food in a refrigerator and keep your cooked food from rotting overnight. You can stop stripping your local forest of the branches you need to cook your food. You can stop collecting cattle poop for fuel. You can run pumps to have clean water and your kids don’t die from the diseases in dirty water. That is awesome.

Living in a hut with open fires and poor sanitation is one of the most dangerous environments we have. People live longer and better when they have electricity. But, there is more. Electrical power also produced the greatest liberation of humanity in recorded history.

And here it is-

That picture of an old washing machine is a life-saving device. Once you have power then you can wash your clothes in a machine with hot water. If you think I’m joking, then wash your clothes by hand in a bucket for a week. Soap and water saved more lives than antibiotics have yet to save. The washing machine also doubled the intellectual capacity of the human race because women weren’t spending all day carrying water and beating our clothes with rocks at the edge of a river. That gave women time to read. Women’s liberation came out of a wall socket and a hot water faucet. My mother lived it, and it was good.

Women’s liberation came out of a wall socket and a hot water faucet.
My mother lived it, and it was good.

We might laugh, but there are still a billion people who are trying to get clean water and soap. The good news is that worldwide, we connect a few hundred thousand people a day to the power grid. That one action helps us reduce poverty on a scale that is unprecedented in human history. The word unprecedented isn’t a rhetorical flourish in a politician’s speech. It is a fact. We are improving the conditions of human life faster than we ever have. We are making the poor less poor.

I helped a little. Capitalists like me are doing it today. You should do it too. You should do it because it is good.

Should we use renewable energy?

Use it if you want. It’s not that I’m anti-solar or anti-wind, it is that I’m pro-algebra. It takes junior-high school math to figure out how many solar panels are required to power the electric cars driving down a highway. You can use your phone to look up the numbers. The longer the road, the longer the strip of solar panels running alongside it. When you have more cars and more lanes of traffic, then you need a wider strip of solar panels to provide the power for the cars on the road.

What does it take to live on renewable power? It takes over a hundred yards of solar panels for each lane of traffic. An eight-lane highway takes over half mile of solar panels to power the cars that run on it. It takes more on the coast, and less in the desert. It is obvious that you don’t have to put the panels next to the road, but they have to go somewhere close by. Look at our roads and ask if you want to cover the landscape with solar panels. You can do the algebra. Where will you put those solar panels in town and in the suburbs?

Go build and operate your electric car with solar power if you want. Only a few percent of us can afford that. Saying that everyone has to live like the elite rich people who live in Malibu, California or Fairfax, Virginia means that most of the people on our planet won’t have clean water and clean clothes. It means that more of their kids will die. That is evil.

Those pictures are Chicago at night. I remember looking out from one of those buildings at the lights of the city. It was cold outside, and I thought about what would happen if the power went off. I changed my major field of study from physics to nuclear engineering. You can see the city from space. That city needs a lot of power.

Back to our earlier question, is the nuclear fuel to power an electrical plant scarce or common? Is nuclear power a good idea or a bad one? An honest answer is some “yes”, and some “no”.

There are thousands of possible designs for a nuclear reactor. I built plants that ran on enriched uranium. I think that is crazy. The only reason we do that today is because, once upon a time, we built atomic bombs. We knew how to handle uranium. That is not a good reason to keep doing it.

The only reason we have the particular type of nuclear power plants that we have today is because a guy in the navy wanted nuclear powered submarines. He wanted them badly and in a hurry. There are compelling reasons to leave that design behind and move on.

I don’t like nuclear power the way we do it today.

There are other ways to make power. Thorium is a nuclear fuel. We’ve used it to power reactors as a fertile fuel. It is the 38th most common element in the earth’s crust. It is more common than tin, or zinc, boron, arsenic, bromine, iodine, or bismuth.

Do any of you think we’re going to run out of tin for tin cans, or zinc for sunscreen, or borax soap, or the bismuth in Pepto-Bismol any time soon? There is one particular mountain on the Idaho/Montana border that has enough Thorium to power the world for the next thousand years. From heating your home, to powering our electric cars, to taking carbon dioxide out of the air and converting it into jet fuel; there is enough energy to do everything you want to do.

If you come away from this talk with anything, then remember this. We have enough energy to power the world forever. If someone says we don’t, then they are trying to manipulate you.

We have enough energy to power the world forever.
If someone says we don’t, then they are trying to manipulate you.

I’m an engineer. We have closer to ten thousand years of nuclear fuel in that one mountain, but I expect our energy consumption to increase over time so I called it a thousand years. Isn’t that great that we have a special mine like that? Eh, it is just another mountain with a mine. We have other sources of thorium. It is as common as dirt.

The energy to power our high-tech air-conditioned and micro-waved life is in a ball of thorium the size of a golf ball for each of us. That provides the power you’ll need during your entire lifetime. The energy we consume is also contained in a ball of coal that is 33 feet in diameter. It’s yours and it is mine.

With thorium power, the nuclear waste each of us leaves behind is the size of a grain of rice. In 300 years it decays to the levels of background radiation. Most of it decays in about two years, but there is some nasty stuff we want to keep locked up longer.

That 33-foot mountain of coal that you and I drag around with us also has Thorium mixed into the coal ash, so it isn’t as if we are living nuclear-free today. Not really. The contaminants that come in natural gas are also mildly radioactive. I wouldn’t be able to license either a coal power plant or a natural gas power plant today if I were held to the same standards as a nuclear plant simply because those other plants emit too much radiation.

That doesn’t mean coal and gas are particularly unsafe. It means that the regulations governing a nuclear plant are extremely stringent. Why didn’t you know that?

What is the problem with nuclear power? Let’s talk about the sensational claims that you all came to hear. What about nuclear bombs and nuclear waste. But radiation is bad and turns lizards into monsters that attack Tokyo. I saw it on my phone, so it has to be true.

Nuclear energy can be bad, and it can be good. The better question to ask is.. compared to what? Compared to living without power? Compared to making power so expensive that people can’t get clean water? Compared to doing more of what we’re doing today? Let’s look at where we are and where we could be.

You say you want to save the environment? Then you should be the strongest advocate for nuclear power.

Nuclear power produces a quarter of the greenhouse gasses compared to solar energy. And that is with the old style nuclear plants, not even the efficient nuclear plants that I want to build. The nuclear plant I like puts wind to shame.

It takes a lot of energy to make solar cells. Those cells have about the same lifetime as a nuclear plant, a little shorter, but we can be generous. We do a horrible job of recycling used solar panels once the water resistant seals break down and their connections corrode. We never designed solar panels for re-use.

You say you want to save lives? Then you should be the strongest advocate for nuclear power. Nuclear power is four times safer than wind power and ten times safer than solar. Nuclear power in the US is even safer than these numbers, but I included nuclear power data from around the world. Climbing roofs to put on solar panels is about as dangerous as climbing trees for a living. People get hurt installing and maintaining solar panels. They fall and things fall on them.

What does that mean? Look at the numbers and ask yourself this question- Why did politicians regulate and destroy nuclear power in California? It wasn’t to save the environment. It wasn’t to save lives. I gave you those numbers, so what was the reason?

Killing nuclear power in California let politicians sell a soundbite. Nuclear power died, and more people died with it, because we didn’t read past the headlines. Politics are real. We made them, and they should make us ANGRY.

Killing nuclear power in California let politicians sell a soundbite.

(It is an odd feeling when we talk about radiation to avoid being depressed by California politics.)

Let’s shine some light on radioactivity. We have to talk about radiation and radioactive decay before we can determine whether nuclear power is good or bad. Some heavy elements decay. Certain isotopes, and that means certain combinations of protons and neutrons, decay faster than others.

We’re not going to run out of potassium tomorrow, but some potassium isotopes are radioactive. Half of these isotopes will be gone in the next billion years. They decay so slowly that you’re not worried about having a bottle of low-sodium salt in your hand even though it contains radioactive potassium. In fact, potassium is an essential element. You need it in your diet.. and it is mildly radioactive.

What does it mean that some of the chemicals that our body needs are naturally radioactive? It means we can measure things that sound shocking but aren’t dangerous. We have to read past the headlines that scream, “Our food is contaminated with radiation.” We know they sell potassium chloride, low-sodium salt, in the supermarket. One of the reasons that oranges and orange juice is good for us is that they contains potassium. (So do other fruits, but I want to save them for later.)

Some nitrogen is converted into radioactive carbon in our upper atmosphere. That means our toast is slightly radioactive. Yawn. You’re also exposed to radiation when you live up in the mountains and when you fly long distances in an airplane at high altitude. So what. Things that decay very slowly are not a significant risk to us.

We need context. Yes, radiation can kill us. I’ve worked at sites where you wore monitoring badges and stayed out of hot zones. You couldn’t work there if you didn’t follow the rules. We can measure extremely low levels of radiation. That is a good thing, but it isn’t necessarily an alarming thing.

Time matters.
Let’s look at the other extreme. Some materials are so radioactive that they decay very quickly. Instead of decaying in a billion years, they decay in a few minutes. What should we do with them? Well don’t hold them in your hand and don’t eat them.

We’ve solved this problem before. We put these materials in a bottle and go home for the weekend. Their radioactivity decreases by a factor of 90-billion in a day. On Monday afternoon we can pour them out and reuse the bottle.

I worked on nuclear powerplants. The dose you got if you stood at the edge of the property boundary for a year was the same dose you got from eating one banana. Bananas contain high amounts of potassium. You know what that means?

It means we can measure and calculate meaningless things. You sat next to your friend at lunch. The two of you are both radioactive. We can calculate the radiological-health impact of you sitting next to each other for your 45 minute lunch break. Multiply that exposure by the third of a billion people in the United States, and we can calculate the number of cancers deaths we cause each year by hugging our friends. Hugs won’t give you cancer and a banana is not a public health risk due to radiation.

Hugs won’t give you cancer..
and a banana is not a public health risk due to radiation.

Context is everything.
Here is something I find amazing because of its unusual context. It is true that nuclear power will increase the short-term radiation at the property line of a nuclear power plant. It is also true that nuclear reactors burn up radioactive materials. The reactor actually decreases the possible radioactive dose that is here on earth.

As a student, I had to calculate worst-case accidents. What would happen if we took an operating nuclear reactor apart, fed it to children, and counted the damage forever. It turns out that the longer you ran the nuclear plant, the fewer people died. The point is that you get silly answers if you make silly assumptions.

That strange answer makes sense. When you’re done driving your car, there is less petroleum than when you started. You used up some of the gasoline. When we use nuclear fuel, there is less total radioactivity than when we started. Rather than decay in a billion years, we made heavy elements react today. They were going to decay anyway if we waited long enough, but we gave them a push.

If radiation is bad then we want to build lots of reactors and burn up all the heavy isotopes that are out in the world decaying on their own. If radiation is bad then we’d want to fill the world with nuclear power plants that are eating up the stuff even if we throw the power away. I think we should use the power to make our lives better.

What about nuclear bombs? Isn’t that what you came to find out? Can you build a bomb?

When a physicist says you can do something it means it doesn’t break the laws of nature. There is uranium in your granite countertop at home. That means it is theoretically possible for us to build a bomb from countertops. As an engineer, it is my job to calculate how many years and how many dollars it would cost. It is both expensive and slow, but if you have enough time, money and countertops, we can do it.. eventually.

In theory, if we have enough time, money and countertops, we can build a bomb.

The Uranium isotope you need for a bomb is less than one percent of the uranium found in nature. You can’t use chemistry to concentrate the isotope you want because all uranium behaves the same way in a chemical reaction. Building a bomb is hard work.

Saying that you can build a nuclear bomb out of granite countertops is like saying you can build a chemical bomb out of bananas. The raw materials are all there, but you still have a lot of work to do. Would outlawing bananas keep us safe from terrorist building bombs?

Everything we do comes with a risk. Thank you for coming to this talk today. According to my calculations, it was dangerous for you to come here.. compared to staying at home in bed with the covers pulled over your head. Solar energy comes with a risk because we have guys falling off roofs. Leaving people in poverty is dangerous too. Real solutions are hard to find because we want answers that work in a lot of cases and in lots of places, not just in Malibu and Fairfax.

That doesn’t answer your question about bombs. Sigh. OK.

Can you use a LFTR reactor to build a bomb? You could use almost any reactor to create bomb making materials if you modify it enough and have enough money and time. This isn’t the sort of operation you whip together over the weekend in your garage using old car parts. You leave a giant industrial sized footprint and you’ll probably need the better part of a decade. We’re talking about a very large industrial complex. Think of something the size of a several football stadiums. Building a bomb is many-billions-of-dollars hard.

Building a bomb is billions of dollars hard.

Ask yourself if it is safer to leave people in sickness and poverty or to provide electric light and clean water for them? Please study it and decide which is better.

What makes one source of power better than another?
I said that there are about a thousand ways we could build a nuclear reactor. Let’s compare the design we want with the designs we have today. You might have your own list, but these are the things I want.

• Price competitive
• Inexpensive
• Stable and walk-away safe
• Very little nuclear waste or bomb-making materials.
• Small. Easy to find a site to build it.

Look at those requirements. That is a lot to ask.

  1. We want the electricity to be competitive with existing electrical power generation. We want neither subsidies nor taxes on nuclear power and the alternatives.
  2. We want it to be inexpensive to build each plant. We want many sources of power rather than one large, perfect, monument to politics. There are economic, engineering and political reasons to spread power production across the electrical grid. We want to spread power across the country and around the world.
  3. We want the plant to be stable, and self-correcting in terms of power and temperature. That means it operates is a stable manner without constant adjustment from outside. Think of the powerplant acting like a car that sits on four wheels rather than like a unicycle where you have to work all the time so it won’t fall over. That is easy to do if you design for stability from the start. Walk-away safe means that if you don’t like what the plant is doing, then you can unplug it, walk away, and it safely shuts itself down.
  4. The powerplant produces very little nuclear waste or bomb making materials. That makes sense and I’ll come back to it in a minute.
  5. Small means we don’t need square miles of land for each plant. How about the size of a few tennis courts instead of the size of a football stadium and its parking lot.
    To say it is easy to find a building site means the plant doesn’t need to be near a lake or a river.. or on a mountain top for that matter. We want to be able to put it wherever we want it.

What about nuclear waste?
I said the reactor we want will produced very little nuclear waste or bomb-making materials. We can get rid of most of it, but not all of it.

Do you know what the largest amount of waste is from an operating nuclear plant? The stuff they put in drums and bury in the dirt out in the desert is mostly paper towels. Things leak. Things drip. A small percent of the time, things don’t go as planned. Drips happen but we wipe them up.

This isn’t a surprise. The coffee machine at home drips as we clean it. We wipe up the spills. We want practical solutions that work on bad days. Don’t hold me to absolute perfection. Require that the design makes progress from where we are today.

Those requirements I listed are a revolution ahead of anything we have now. It might not be possible to create a power source that meets those specifications. How long do you think it would take us to come up with that reactor design? A few years? A decade? A century?

We did it. We tried it. It works. So why aren’t we doing it now?

You know the joke about medical regulations? I’m sorry, ma’am. We tried to save your grandmother but the paperwork was insurmountable.

This reactor we’re talking about wasn’t like the design that powered the first nuclear submarines. It wasn’t like the designs that were first used in nuclear generating plants. The people who licensed existing plants didn’t know how to license this new design.

The paperwork was insurmountable.

It is your duty to educate yourself.
Today we’ve added politics and media sensationalism to the energy problem. A second’s worth of lies can take a minute to answer. Unfortunately, we’re off to the next topic in the news after a 15 second sound bite.

We are the antidote to that. We have to be more informed and dedicated to the truth than the politicians and journalists who manipulate us. Please turn off your TV. Step off Facebook. Read until you understand. It is our duty to educate ourselves.

Some people will tell you that a new design for a nuclear plant is too expensive for commercial consideration. It isn’t.

I live in a county where we have about 55 billion dollars of plant-investment this year. We have about a hundred billion dollars planned through the next three years. About a third of the capital investment in the entire USA is on the southern edge of the Louisiana-Texas border. This region by itself would be richer than the gross domestic product of over 100 countries.

That shows we can tolerate cost and risk. What investors won’t stand for is political uncertainty. They can’t afford that a politician will walk in and tax and regulate everything they do and bleed them into bankruptcy. That is precisely what we did to the nuclear industry.

You’ve seen that happen before. That is why your electricity and gasoline are so expensive here in California.. and why your unemployment is so high.

But what about nuclear waste?
The nuclear design I like is called LFTR (lifter). That stands for Liquid Fluoride Thorium Reactor. In the nuclear reactors we use today, we consume about one-half of one percent of the fuel we put into them. The rest of the fuel becomes radioactive waste. We consume an isotope of uranium that is about as rare and hard to find as platinum. The isotope in the fuel is also so energy-dense that we consume a few pounds of it a year as we make a half-million dollars of electricity a day.. for day after day.

You can hold a pellet of natural uranium-oxide in your hand. It won’t burn you. It isn’t even hot to the touch. It isn’t a radiation hazard until you put it in a nuclear reactor. Then it becomes bad news.

We have to deal with the 90 percent of the fuel that we didn’t consume in the nuclear reaction. We took tons of a heavy element like uranium and we bombarded it in a nuclear reactor for a few years. That is the stuff you have to hide in the ground for thousands of years.. maybe.

With that statement, I gave away the secret of how we reduced the amount of nuclear waste in the LFTR reactor by a factor of at least 200 compared to the nuclear plants we have today. In the LFTR design, we consume a ton of fuel and generate about 100 grams of transuranic waste. That is that ratio of a golf ball to that grain of rice I showed you earlier.

We’re able to do that because nature gave us a gift. Naturally occurring thorium is isotopically pure. That means that the thorium we find in dirt has a constant number of protons and neutrons. We convert that one isotope of thorium into an isotope of uranium inside the reactor. We only put in the exact materials we want to make power.. and we don’t put in anything else.

We can design a plant that doesn’t have the problem of nuclear waste in the first place.

Compared to the reactors we have today, we don’t put junk in and we don’t get radioactive junk out. That is important progress. It is possible for us to design a nuclear plant so it doesn’t have the problem of nuclear waste in the first place.

We did. Been there. Done that.

We form our intuition based on our experience. In the chemical world where you and I live, we expect that if we want a faster chemical reaction then we add heat and pressure. That intuition fails us in the nuclear world.

Can you have an industrial process that runs at over a thousand degrees Fahrenheit and at atmospheric pressure? We run a nuclear reactor with a coolant temperature of over 1100 C. That is close to 2 thousand degrees Fahrenheit.

We also want the reaction to slow down as the reactor heats up. In fact, let’s make that part of the design requirements for the plant we want. We’ll require that the reactor operates at low pressure and be chemically stable at high temperatures. While we’re at it, design this powerplant so that if we picked it up and cracked it like an egg, then it wouldn’t burn or explode. That sounds impossible, but it isn’t.

That rocket is where our intuition goes when we think of high-powered chemical reactions. I want us to think again.

These are red-hot steel parts coming out of a pot of molten salt. You can expose the salt to the air and nothing happens. You can pour the salt on the floor, and after the floor paint blisters and the concrete stops steaming, the salt lies there as it cools. When it solidifies back into solid salt, we can pick it up with a shovel. We can pour water on it and there isn’t a chemical reaction. We use molten salts for high temperature heat transfer every day.

This isn’t your grandpa’s locomotive. High temperature water is dangerous, so don’t use it. We use a molten salt as a heat transfer fluid because it is extremely chemically stable at high temperatures and the salt shrugs off radiation.

Don’t confuse molten salts with salt water. Molten salts don’t degrade and they don’t attack the materials around them. That means we can run the reactor at low pressure. We’re talking about the pressure inside a soccer ball, probably less than the pressure inside the water pipes in your house. We know how to make very safe equipment that operates at those low pressures and high temperatures.

Molten Fluoride Salt

In the LFTR design, the fuel is liquid and the moderator is solid. That is the opposite design approach that we use in old nuclear reactors.

A moderator is the catalyst that makes nuclear fuel react. You can take all the fuel-salt you want, push it into a pile, and it won’t sustain a nuclear chain reaction. It is as if the gasoline in your car could only burn inside the engine, but not anywhere else. That would be a nice safety feature to have in your car, and we have it in a LFTR powerplant.

Let me turn around that question about cars. Would you want to drive a car that had to carry a years’ worth of fuel? How about a year’s worth of exhaust! That is the way we build nuclear plants today, but we shouldn’t. The LFTR design adds fuel and can take out the nuclear waste a little at a time. That makes sense since the original LFTR was designed by a chemical engineer. Continuous fueling and cleanup also makes the reactor safer.

What is walk away safe?
You might have heard about the nuclear plants we have today where an accident melted the core of the reactor. That’s bad. The LFTR has a liquid fuel and coolant. When you want to shut the plant down and go home for the weekend, you simply drain the fuel out of the reactor tank. That leaves the moderator sitting there all by itself.

The guys who first designed this reactor put a fan, an air blower, next to the drain line under the reactor. That fan cooled the drain pipe and froze a plug of salt in the pipe. If they lost power at the test site, then the cooling fan stopped turning. The drainpipe heated up and the fuel drained down into a storage tank. The nuclear reaction stopped and the fuel cooled off. The guys running that test reactor shut it down that way every Friday afternoon for years. Come Monday morning, they had to heat the fuel back up so they could pump it back into the reactor.

It is nice to have a safety system powered by gravity. Every one of the proposed LFTR designs I’ve seen has kept that original passive safety feature of an air-cooled plug of frozen salt.

What is this Thorium-Uranium slight-of-hand?
I talked about both thorium and uranium. This is getting a little geeky, so I don’t want to spend a lot of time on it. Thorium and uranium are two different elements. The reactor uses uranium to make power. It also uses uranium to convert more thorium into uranium. That is an interesting trick called a unity breeding.

This process isn’t pure. Chemical and nuclear processes have side reactions. There are small traces of other uranium isotopes in the mix. We didn’t design the process to be slightly contaminated that way, but it happens about 1 percent of the time. That turns out to be a good thing. The contaminant is radioactive. That is the reason you don’t want to make a bomb using a LFTR reactor.

A touch of reality is worth a pound of theory when it comes to nuclear power. There are less radioactive ways to build a bomb. That is crucial.

A nuclear bomb isn’t very radioactive before it explodes. Adding even a little bit of radioactivity means the bomb is much harder to design and build. If you add much radioactivity at all, then building a bomb from that material becomes impossible. I didn’t say it was harder. I said the bomb won’t work because the materials are significantly radioactive and you can’t get the reaction you need for a bomb. It is important to know what you know, and what you don’t know.

What does a liquid fluoride thorium reactor look like?
These pictures are pieces of a molten salt reactor. On the left, those long strips of graphite running up and down are the moderator that causes the nuclear reaction. The graphite slows the neutrons down in the reactor and that makes the neutrons thousands of times more reactive with the uranium in the liquid fuel. They produced about ten thousand horsepower from a core that was four-and-a-half feet in diameter and about six feet long.

They needed to cool this test reactor so they ran hot salt through some cooling coils. The image on the right is the cooling coils glowing orange-hot as a fan blows air across them.

Here is the old design and the contemporary design that I like. I like small plants where you build the pieces of the powerplant in a factory. You ship pre-assembled pieces by truck to a worksite where you bolt the modules together. That is more like the way we build a modular home. That also means we can pick up most of the reactor and take it with us if the state or county changes the contract we had. What do you think would happen if a utility could take back their powerplant when the government raised taxes?

We’ll give you power, but we’ll take the powerplant back if you break your side of the bargain. That is one reason that government officials hate the idea of small power plants. They won’t license them because they can’t hold them hostage.

Turbine designers get excited when you tell them you have a source of heat at over 1500 degrees Fahrenheit. That high temperature lets power-engineers achieve high thermal efficiency. These nuclear plants can rival the efficiency of the best powerplants we run today. The power turbine gets to be about a meter in length, and that is amazing to me.

What does the future hold for modern nuclear plants?
The US Department of Energy was created by President Jimmy Carter to make the United States energy independent. It failed, but a bunch of guys in west Texas made the USA energy independent with fracking. Biden just put a regulatory hold on energy exploration and fracking.

Now, we have to get the US DoE out of the way. Rather than bring us solutions, the Department of Energy tells us what we can’t do. A prototype LFTR reactor can’t be over 1300 horsepower. It turns out that the optimal size for a prototype is about twice that size. Sorry, but that does not compute if you’re a government bureaucrat.

Other countries are exploring these new reactors. China has a very aggressive program to build a LFTR, in particular the China Academy of Sciences. We gave China every government document we had and Chinese scientists had open access to the people who built the molten salt reactor at Oak Ridge National Lab in Tennessee. Chinese scientists designed their own Thorium molten salt reactor. We don’t know if they are building sub-scale parts, sub-assemblies, or full-scale prototypes.

Why is China interested? China starts a new coal power plant every four days. They have a pollution problem and they want electric cars. They don’t want to pay other countries for coal.

There is also LFTR research reactor in Holland and some research underway in Canada. These are subscale tests to refine the fuel processing cycle.

We have designs ready for prototyping here in the US, but you can’t license the LFTR without paying the government so it understands how to regulate the design. That is a very risky investment since the political administration in this country changes every four years or so.

For political reasons, we will watch from the sidelines until another country shows us that modern designs work and are safe.

For a review, here are some of the points we covered today-

  • Are you clear about what you know?
  • Is an expansive and confident statement more trustworthy than a qualified claim?
  • Are you radioactive?
  • When are most nuclear fuels safe and when are they dangerous?
  • Where does the energy we use today come from?
  • Are the materials in your body common in our sun?
  • Do we have “enough” energy to run the world?
  • Does industrial society save lives, or is pre-industrial society safer?
  • Is nuclear power safe for the environment when compared to other sources of energy?
  • Do politicians make fully informed decisions in the public interest?
  • Based on the evidence presented, do you care about the future of our society more than politicians care?

Hint- Simple yes/no answers are almost always wrong because they don’t define the conditions under which the answer is accurate.

I gave you 7000 words. If you found them interesting, then please share them with a friend. RM

4 Comments leave one →
  1. March 1, 2021 2:39 pm

    Reblogged this on The zombie apocalypse survival homestead.


  2. March 1, 2021 5:45 pm

    Does that eliminate the forever ponds?


  3. June 6, 2021 12:30 pm

    Here is a video where I presented this article to high school students.


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