TEDxYYC
Kirk Sorensen: Thorium, an alternative nuclear fuel
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Kirk Sorensen shows us the liquid fuel thorium reactor -- a way to produce energy that is safer, cleaner and more efficient than current nuclear power.
Kirk Sorensen - Engineer, nuclear technologist
Kirk Sorensen stumbled across thorium while doing research on how to power a lunar community. Thorium is a cleaner, safer, and more abundant nuclear fuel -- one that Kirk believes will revolutionize how we produce our energy. Full bio
Kirk Sorensen stumbled across thorium while doing research on how to power a lunar community. Thorium is a cleaner, safer, and more abundant nuclear fuel -- one that Kirk believes will revolutionize how we produce our energy. Full bio
Double-click the English transcript below to play the video.
00:06
Nearly everyone in the world
is part of some community,
is part of some community,
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whether large or small.
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And all of these communities
have similar needs.
have similar needs.
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They need light,
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they need heat
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they need air-conditioning.
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People can't function very well
when it's too hot or too cold.
when it's too hot or too cold.
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They need food to be grown or provided,
distributed and stored safely.
distributed and stored safely.
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They need waste products to be collected,
removed and processed.
removed and processed.
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People in the community need to be able
to get from one place to another
to get from one place to another
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as quickly as possible.
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And a supply of energy is the basis
for all of these activities.
for all of these activities.
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Energy in the form of electricity
provides light and air-conditioning.
provides light and air-conditioning.
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Energy in the form of heat keeps us warm.
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And energy in chemical
form provides fertilizer;
form provides fertilizer;
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it drives farm machinery
and transportation energy.
and transportation energy.
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Now, I spent 10 years working at NASA.
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In the beginning of my time there in 2000,
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I was very interested in communities.
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But this is the kind of community
I was thinking of --
I was thinking of --
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a lunar community
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It had all of the same needs
as a community on Earth would have,
as a community on Earth would have,
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but it had some very unique constraints.
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And we had to think about
how we would provide energy
how we would provide energy
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for this very unique community.
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There’s no coal on the Moon.
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There's no petroleum.
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There’s no natural gas.
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There's no atmosphere.
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There’s no wind, either.
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And solar power had a real problem:
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the Moon orbits the Earth once a month.
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For two weeks, the sun goes down,
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and your solar panels
don't make any energy.
don't make any energy.
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If you want to try to store
enough energy in batteries for two weeks,
enough energy in batteries for two weeks,
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it just simply isn't practical.
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So nuclear energy
was really the only choice.
was really the only choice.
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Now, back in 2000, I didn't really know
too much about nuclear power,
too much about nuclear power,
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so I started trying to learn.
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Almost all of the nuclear power
we use on Earth today uses water
we use on Earth today uses water
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as a basic coolant.
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This has some advantages,
but it has a lot of disadvantages.
but it has a lot of disadvantages.
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If you want to generate electricity,
you have to get the water a lot hotter
you have to get the water a lot hotter
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than you normally can.
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At normal pressures, water will boil
at 100 degrees Celsius.
at 100 degrees Celsius.
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This isn't nearly hot enough
to generate electricity effectively.
to generate electricity effectively.
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So water-cooled reactors have to run
at much higher pressures
at much higher pressures
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than atmospheric pressure.
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Some water-cooled reactors run
at over 70 atmospheres of pressure,
at over 70 atmospheres of pressure,
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and others have to run at as much as
150 atmospheres of pressure.
150 atmospheres of pressure.
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There's no getting around this;
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it's simply what you have to do
if you want to generate electricity
if you want to generate electricity
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using a water-cooled reactor.
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This means you have to build
a water-cooled reactor
a water-cooled reactor
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as a pressure vessel,
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with steel walls
over 20 centimeters thick.
over 20 centimeters thick.
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If that sounds heavy,
that's because it is.
that's because it is.
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Things get a lot worse
if you have an accident
if you have an accident
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where you lose pressure
inside the reactor.
inside the reactor.
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If you have liquid water
at 300 degrees Celsius
at 300 degrees Celsius
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and suddenly you depressurize it,
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it doesn't stay liquid for very long;
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it flashes into steam.
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So water-cooled reactors are built
inside of big, thick concrete buildings
inside of big, thick concrete buildings
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called containment buildings,
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which are meant to hold all of the steam
that would come out of the reactor
that would come out of the reactor
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if you had an accident
where you lost pressure.
where you lost pressure.
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Steam takes up about 1,000 times
more volume than liquid water,
more volume than liquid water,
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so the containment building
ends up being very large,
ends up being very large,
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relative to the size of the reactor.
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Another bad thing happens
if you lose pressure
if you lose pressure
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and your water flashes to steam.
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If you don't get emergency coolant
to the fuel in the reactor,
to the fuel in the reactor,
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it can overheat and melt.
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The reactors we have today
use uranium oxide as a fuel.
use uranium oxide as a fuel.
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It's a ceramic material
similar in performance
similar in performance
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to the ceramics we use to make
coffee cups or cookware
coffee cups or cookware
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or the bricks we use to line fireplaces.
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They're chemically stable,
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but they're not very good
at transferring heat.
at transferring heat.
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If you lose pressure, you lose your water,
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and soon your fuel will melt down
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and release the radioactive
fission products within it.
fission products within it.
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Making solid nuclear fuel
is a complicated and expensive process.
is a complicated and expensive process.
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And we extract less than one percent
of the energy for the nuclear fuel
of the energy for the nuclear fuel
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before it can no longer
remain in the reactor.
remain in the reactor.
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Water-cooled reactors have
another additional challenge:
another additional challenge:
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they need to be near
large bodies of water,
large bodies of water,
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where the steam they generate
can be cooled and condensed.
can be cooled and condensed.
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Otherwise, they can't generate
electrical power.
electrical power.
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Now, there's no lakes
or rivers on the Moon,
or rivers on the Moon,
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so if all of this makes it sound
like water-cooled reactors
like water-cooled reactors
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aren't such a good fit
for a lunar community,
for a lunar community,
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I would tend to agree with you.
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(Laughter)
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I had the good fortune to learn about
a different form of nuclear power
a different form of nuclear power
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that doesn't have all these problems,
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for a very simple reason:
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it's not based on water-cooling,
and it doesn't use solid fuel.
and it doesn't use solid fuel.
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Surprisingly, it's based on salt.
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One day, I was at a friend's
office at work,
office at work,
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and I noticed this book on the shelf,
"Fluid Fuel Reactors."
"Fluid Fuel Reactors."
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I was interested
and asked him if I could borrow it.
and asked him if I could borrow it.
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Inside that book, I learned
about research in the United States
about research in the United States
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back in the 1950s,
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into a kind of reactor
that wasn't based on solid fuel
that wasn't based on solid fuel
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or on water-cooling.
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It didn't have the problems
of the water-cooled reactor,
of the water-cooled reactor,
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and the reason why was pretty neat.
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It used a mixture of fluoride salts
as a nuclear fuel,
as a nuclear fuel,
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specifically, the fluorides of lithium,
beryllium, uranium and thorium.
beryllium, uranium and thorium.
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Fluoride salts are remarkably
chemically stable.
chemically stable.
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They do not react with air and water.
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You have to heat them up
to about 400 degrees Celsius
to about 400 degrees Celsius
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to get them to melt.
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But that's actually perfect
for trying to generate power
for trying to generate power
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in a nuclear reactor.
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Here's the real magic:
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they don't have to operate
at high pressure.
at high pressure.
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And that makes the biggest
difference of all.
difference of all.
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This means they don't have to be
in heavy, thick steel pressure vessels,
in heavy, thick steel pressure vessels,
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they don't have to use water for coolant
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and there's nothing in the reactor
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that's going to make
a big change in density, like water.
a big change in density, like water.
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So the containment building
around the reactor
around the reactor
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can be much smaller and close-fitting.
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Unlike the solid fuels that can melt down
if you stop cooling them,
if you stop cooling them,
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these liquid fluoride fuels
are already melted,
are already melted,
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at a much, much lower temperature.
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In normal operation,
you have a little plug here
you have a little plug here
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at the bottom of the reactor vessel.
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This plug is made
out of a piece of frozen salt
out of a piece of frozen salt
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that you've kept frozen
by blowing cool gas
by blowing cool gas
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over the outside of the pipe.
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If there's an emergency
and you lose all the power
and you lose all the power
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to your nuclear power plant,
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the little blower stops blowing,
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the frozen plug of salt melts,
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and the liquid fluoride fuel
inside the reactor
inside the reactor
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drains out of the vessel, through the line
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and into another vessel
called a drain tank.
called a drain tank.
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Inside the drain tank, it's all configured
to maximize the transfer of heat,
to maximize the transfer of heat,
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so as to keep the salt passively cooled
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as its heat load drops over time.
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In water-cooled reactors,
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you generally have to provide
power to the plant
power to the plant
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to keep the water circulating
and to prevent a meltdown,
and to prevent a meltdown,
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as we saw in Japan.
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But in this reactor,
if you lose the power to the reactor,
if you lose the power to the reactor,
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it shuts itself down all by itself,
without human intervention,
without human intervention,
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and puts itself in a safe
and controlled configuration.
and controlled configuration.
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Now, this was sounding pretty good to me,
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and I was excited about the potential
of using a liquid fluoride reactor
of using a liquid fluoride reactor
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to power a lunar community.
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But then I learned about thorium,
and the story got even better.
and the story got even better.
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Thorium is a naturally
occurring nuclear fuel
occurring nuclear fuel
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that is four times more common
in the Earth's crust than uranium.
in the Earth's crust than uranium.
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It can be used in liquid fluoride
thorium reactors
thorium reactors
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to produce electrical energy, heat
and other valuable products.
and other valuable products.
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It's so energy-dense that you could hold
a lifetime supply of thorium energy
a lifetime supply of thorium energy
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in the palm of your hand.
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Thorium is also common on the Moon
and easy to find.
and easy to find.
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Here's an actual map of where
the lunar thorium is located.
the lunar thorium is located.
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Thorium has an electromagnetic signature
that makes it easy to find,
that makes it easy to find,
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even from a spacecraft.
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With the energy generated
from a liquid fluoride thorium reactor,
from a liquid fluoride thorium reactor,
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we could recycle all of the air,
water and waste products
water and waste products
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within the lunar community.
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In fact, doing so would be
an absolute requirement for success.
an absolute requirement for success.
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We could grow the crops needed
to feed the members of the community
to feed the members of the community
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even during the two-week lunar night,
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using light and power from the reactor.
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It seemed like the liquid fluoride
thorium reactor, or LFTR,
thorium reactor, or LFTR,
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could be the power source that could make
a self-sustainable lunar colony
a self-sustainable lunar colony
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a reality.
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But I had a simple question:
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If it was such a great thing
for a community on the Moon,
for a community on the Moon,
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why not a community on the Earth,
a community of the future,
a community of the future,
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self-sustaining and energy-independent?
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The same energy generation
and recycling techniques
and recycling techniques
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that could have a powerful impact
on surviving on the Moon
on surviving on the Moon
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could also have a powerful impact
on surviving on the Earth.
on surviving on the Earth.
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Right now, we're burning fossil fuels
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because they're easy to find
and because we can.
and because we can.
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Unfortunately, they're making some parts
of our planet look like the Moon.
of our planet look like the Moon.
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Using fossil fuels
entangles us in conflict
entangles us in conflict
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in unstable regions of the world
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and costs money and lives.
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Things could be very different
if we were using thorium.
if we were using thorium.
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You see, in a LFTR, we could use thorium
about 200 times more efficiently
about 200 times more efficiently
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than we're using uranium now.
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And because the LFTR is capable
of almost completely releasing
of almost completely releasing
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the energy in thorium,
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this reduces the waste generated
over uranium by factors of hundreds,
over uranium by factors of hundreds,
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and by factors of millions
over fossil fuels.
over fossil fuels.
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We're still going to need liquid fuels
for vehicles and machinery,
for vehicles and machinery,
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but we could generate these liquid fuels
from the carbon dioxide in the atmosphere
from the carbon dioxide in the atmosphere
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and from water, much like nature does.
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We could generate hydrogen
by splitting water
by splitting water
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and combining it with carbon
harvested from CO2 in the atmosphere,
harvested from CO2 in the atmosphere,
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making fuels like methanol,
ammonia, and dimethyl ether,
ammonia, and dimethyl ether,
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which could be a direct replacement
for diesel fuels.
for diesel fuels.
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Imagine carbon-neutral
gasoline and diesel,
gasoline and diesel,
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sustainable and self-produced.
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Do we have enough thorium?
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Yes, we do.
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In fact, in the United States, we have
over 3,200 metric tons of thorium
over 3,200 metric tons of thorium
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that was stockpiled 50 years ago
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and is currently buried
in a shallow trench in Nevada.
in a shallow trench in Nevada.
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This thorium, if used in LFTRs,
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could produce almost as much energy
as the United States uses in three years.
as the United States uses in three years.
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And thorium is not
a rare substance, either.
a rare substance, either.
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There are many sites
like this one in Idaho,
like this one in Idaho,
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where an area the size of a football field
would produce enough thorium each year
would produce enough thorium each year
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to power the entire world.
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Using liquid fluoride thorium technology,
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we could move away from
expensive and difficult aspects
expensive and difficult aspects
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of current water-cooled, solid-fueled
uranium nuclear power.
uranium nuclear power.
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We wouldn't need large,
high-pressure nuclear reactors
high-pressure nuclear reactors
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and big containment buildings
that they go in.
that they go in.
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We wouldn't need large,
low-efficiency steam turbines.
low-efficiency steam turbines.
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We wouldn't need to have
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as many long-distance power
transmission infrastructure,
transmission infrastructure,
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because thorium is
a very portable energy source
a very portable energy source
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that can be located
near to where it is needed.
near to where it is needed.
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A liquid fluoride thorium reactor
would be a compact facility,
would be a compact facility,
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very energy-efficient and safe,
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that would produce the energy
we need day and night,
we need day and night,
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and without respect to weather conditions.
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In 2007, we used
five billion tons of coal,
five billion tons of coal,
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31 billion barrels of oil
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and five trillion cubic meters
of natural gas,
of natural gas,
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along with 65,000 tons of uranium
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to produce the world's energy.
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With thorium, we could do the same thing
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with 7,000 tons of thorium
that could be mined at a single site.
that could be mined at a single site.
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If all this sounds interesting to you,
I invite you to visit our website,
I invite you to visit our website,
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where a growing and enthusiastic
online community of thorium advocates
online community of thorium advocates
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is working to tell the world
about how we can realize a clean, safe
about how we can realize a clean, safe
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and sustainable energy future,
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based on the energies of thorium.
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Thank you very much.
(Applause)
(Applause)
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ABOUT THE SPEAKER
Kirk Sorensen - Engineer, nuclear technologistKirk Sorensen stumbled across thorium while doing research on how to power a lunar community. Thorium is a cleaner, safer, and more abundant nuclear fuel -- one that Kirk believes will revolutionize how we produce our energy.
Why you should listen
Kirk Sorensen began his work with thorium while working as an aerospace engineer at NASA. In 2010, he left NASA to work as the chief nuclear technologist at Teledyne Brown Engineering. In 2011, he founded Flibe, a company focused on developing modular thorium reactors.
Kirk Sorensen | Speaker | TED.com