Taylor Wilson: My radical plan for small nuclear fission reactors

1,238,313 views ・ 2013-04-30

TED


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Translator: Joseph Geni Reviewer: Morton Bast
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Well, I have a big announcement to make today,
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and I'm really excited about this.
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And this may be a little bit of a surprise
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to many of you who know my research
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and what I've done well.
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I've really tried to solve some big problems:
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counterterrorism, nuclear terrorism,
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and health care and diagnosing and treating cancer,
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but I started thinking about all these problems,
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and I realized that the really biggest problem we face,
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what all these other problems come down to,
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is energy, is electricity, the flow of electrons.
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And I decided that I was going to set out
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to try to solve this problem.
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And this probably is not what you're expecting.
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You're probably expecting me to come up here
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and talk about fusion,
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because that's what I've done most of my life.
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But this is actually a talk about, okay --
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(Laughter) —
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but this is actually a talk about fission.
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It's about perfecting something old,
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and bringing something old into the 21st century.
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Let's talk a little bit about how nuclear fission works.
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In a nuclear power plant, you have
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a big pot of water that's under high pressure,
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and you have some fuel rods,
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and these fuel rods are encased in zirconium,
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and they're little pellets of uranium dioxide fuel,
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and a fission reaction is controlled and maintained at a proper level,
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and that reaction heats up water,
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the water turns to steam, steam turns the turbine,
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and you produce electricity from it.
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This is the same way we've been producing electricity,
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the steam turbine idea, for 100 years,
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and nuclear was a really big advancement
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in a way to heat the water,
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but you still boil water and that turns to steam and turns the turbine.
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And I thought, you know, is this the best way to do it?
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Is fission kind of played out,
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or is there something left to innovate here?
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And I realized that I had hit upon something
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that I think has this huge potential to change the world.
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And this is what it is.
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This is a small modular reactor.
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So it's not as big as the reactor you see in the diagram here.
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This is between 50 and 100 megawatts.
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But that's a ton of power.
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That's between, say at an average use,
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that's maybe 25,000 to 100,000 homes could run off that.
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Now the really interesting thing about these reactors
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is they're built in a factory.
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So they're modular reactors that are built
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essentially on an assembly line,
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and they're trucked anywhere in the world,
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you plop them down, and they produce electricity.
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This region right here is the reactor.
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And this is buried below ground, which is really important.
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For someone who's done a lot of counterterrorism work,
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I can't extol to you
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how great having something buried below the ground is
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for proliferation and security concerns.
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And inside this reactor is a molten salt,
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so anybody who's a fan of thorium,
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they're going to be really excited about this,
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because these reactors happen to be really good
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at breeding and burning the thorium fuel cycle,
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uranium-233.
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But I'm not really concerned about the fuel.
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You can run these off -- they're really hungry,
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they really like down-blended weapons pits,
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so that's highly enriched uranium and weapons-grade plutonium
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that's been down-blended.
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It's made into a grade where it's not usable for a nuclear weapon,
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but they love this stuff.
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And we have a lot of it sitting around,
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because this is a big problem.
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You know, in the Cold War, we built up this huge arsenal
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of nuclear weapons, and that was great,
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and we don't need them anymore,
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and what are we doing with all the waste, essentially?
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What are we doing with all the pits of those nuclear weapons?
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Well, we're securing them, and it would be great
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if we could burn them, eat them up,
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and this reactor loves this stuff.
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So it's a molten salt reactor. It has a core,
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and it has a heat exchanger from the hot salt,
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the radioactive salt, to a cold salt which isn't radioactive.
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It's still thermally hot but it's not radioactive.
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And then that's a heat exchanger
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to what makes this design really, really interesting,
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and that's a heat exchanger to a gas.
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So going back to what I was saying before about all power
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being produced -- well, other than photovoltaic --
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being produced by this boiling of steam and turning a turbine,
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that's actually not that efficient, and in fact,
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in a nuclear power plant like this,
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it's only roughly 30 to 35 percent efficient.
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That's how much thermal energy the reactor's putting out
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to how much electricity it's producing.
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And the reason the efficiencies are so low is these reactors
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operate at pretty low temperature.
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They operate anywhere from, you know,
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maybe 200 to 300 degrees Celsius.
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And these reactors run at 600 to 700 degrees Celsius,
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which means the higher the temperature you go to,
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thermodynamics tells you that you will have higher efficiencies.
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And this reactor doesn't use water. It uses gas,
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so supercritical CO2 or helium,
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and that goes into a turbine,
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and this is called the Brayton cycle.
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This is the thermodynamic cycle that produces electricity,
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and this makes this almost 50 percent efficient,
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between 45 and 50 percent efficiency.
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And I'm really excited about this,
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because it's a very compact core.
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Molten salt reactors are very compact by nature,
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but what's also great is you get a lot more electricity out
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for how much uranium you're fissioning,
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not to mention the fact that these burn up.
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Their burn-up is much higher.
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So for a given amount of fuel you put in the reactor,
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a lot more of it's being used.
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And the problem with a traditional nuclear power plant like this
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is, you've got these rods that are clad in zirconium,
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and inside them are uranium dioxide fuel pellets.
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Well, uranium dioxide's a ceramic,
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and ceramic doesn't like releasing what's inside of it.
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So you have what's called the xenon pit,
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and so some of these fission products love neutrons.
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They love the neutrons that are going on
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and helping this reaction take place.
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And they eat them up, which means that, combined with
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the fact that the cladding doesn't last very long,
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you can only run one of these reactors
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for roughly, say, 18 months without refueling it.
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So these reactors run for 30 years without refueling,
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which is, in my opinion, very, very amazing,
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because it means it's a sealed system.
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No refueling means you can seal them up
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and they're not going to be a proliferation risk,
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and they're not going to have
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either nuclear material or radiological material
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proliferated from their cores.
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But let's go back to safety, because everybody
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after Fukushima had to reassess the safety of nuclear,
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and one of the things when I set out to design a power reactor
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was it had to be passively and intrinsically safe,
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and I'm really excited about this reactor
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for essentially two reasons.
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One, it doesn't operate at high pressure.
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So traditional reactors like a pressurized water reactor
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or boiling water reactor, they're very, very hot water
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at very high pressures, and this means, essentially,
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in the event of an accident, if you had any kind of breach
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of this stainless steel pressure vessel,
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the coolant would leave the core.
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These reactors operate at essentially atmospheric pressure,
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so there's no inclination for the fission products
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to leave the reactor in the event of an accident.
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Also, they operate at high temperatures,
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and the fuel is molten, so they can't melt down,
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but in the event that the reactor ever went out of tolerances,
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or you lost off-site power in the case
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of something like Fukushima, there's a dump tank.
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Because your fuel is liquid, and it's combined with your coolant,
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you could actually just drain the core
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into what's called a sub-critical setting,
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basically a tank underneath the reactor
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that has some neutrons absorbers.
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And this is really important, because the reaction stops.
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In this kind of reactor, you can't do that.
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The fuel, like I said, is ceramic inside zirconium fuel rods,
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and in the event of an accident in one of these type of reactors,
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Fukushima and Three Mile Island --
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looking back at Three Mile Island, we didn't really see this for a while —
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but these zirconium claddings on these fuel rods,
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what happens is, when they see high pressure water,
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steam, in an oxidizing environment,
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they'll actually produce hydrogen,
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and that hydrogen has this explosive capability
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to release fission products.
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So the core of this reactor, since it's not under pressure
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and it doesn't have this chemical reactivity,
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means that there's no inclination for the fission products
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to leave this reactor.
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So even in the event of an accident,
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yeah, the reactor may be toast, which is, you know,
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sorry for the power company,
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but we're not going to contaminate large quantities of land.
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So I really think that in the, say,
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20 years it's going to take us to get fusion
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and make fusion a reality,
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this could be the source of energy
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that provides carbon-free electricity.
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Carbon-free electricity.
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And it's an amazing technology because
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not only does it combat climate change,
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but it's an innovation.
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It's a way to bring power to the developing world,
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because it's produced in a factory and it's cheap.
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You can put them anywhere in the world you want to.
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And maybe something else.
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As a kid, I was obsessed with space.
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Well, I was obsessed with nuclear science too, to a point,
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but before that I was obsessed with space,
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and I was really excited about, you know,
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being an astronaut and designing rockets,
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which was something that was always exciting to me.
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But I think I get to come back to this,
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because imagine having a compact reactor in a rocket
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that produces 50 to 100 megawatts.
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That is the rocket designer's dream.
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That's someone who is designing a habitat on another planet's dream.
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Not only do you have 50 to 100 megawatts
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to power whatever you want to provide propulsion to get you there,
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but you have power once you get there.
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You know, rocket designers who use solar panels
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or fuel cells, I mean a few watts or kilowatts --
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wow, that's a lot of power.
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I mean, now we're talking about 100 megawatts.
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That's a ton of power.
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That could power a Martian community.
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That could power a rocket there.
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And so I hope that
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maybe I'll have an opportunity to kind of explore
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my rocketry passion at the same time that I explore my nuclear passion.
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And people say, "Oh, well, you've launched this thing,
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and it's radioactive, into space, and what about accidents?"
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But we launch plutonium batteries all the time.
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Everybody was really excited about Curiosity,
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and that had this big plutonium battery on board
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that has plutonium-238,
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which actually has a higher specific activity
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than the low-enriched uranium fuel of these molten salt reactors,
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which means that the effects would be negligible,
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because you launch it cold,
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and when it gets into space is where you actually activate this reactor.
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So I'm really excited.
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I think that I've designed this reactor here
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that can be an innovative source of energy,
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provide power for all kinds of neat scientific applications,
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and I'm really prepared to do this.
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I graduated high school in May, and --
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(Laughter) (Applause) —
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I graduated high school in May,
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and I decided that I was going to start up a company
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to commercialize these technologies that I've developed,
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these revolutionary detectors for scanning cargo containers
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and these systems to produce medical isotopes,
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but I want to do this, and I've slowly been building up
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a team of some of the most incredible people
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I've ever had the chance to work with,
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and I'm really prepared to make this a reality.
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And I think, I think, that looking at the technology,
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this will be cheaper than or the same price as natural gas,
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and you don't have to refuel it for 30 years,
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which is an advantage for the developing world.
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And I'll just say one more maybe philosophical thing
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to end with, which is weird for a scientist.
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But I think there's something really poetic
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about using nuclear power to propel us to the stars,
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because the stars are giant fusion reactors.
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They're giant nuclear cauldrons in the sky.
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The energy that I'm able to talk to you today,
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while it was converted to chemical energy in my food,
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originally came from a nuclear reaction,
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and so there's something poetic about, in my opinion,
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perfecting nuclear fission
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and using it as a future source of innovative energy.
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So thank you guys.
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(Applause)
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