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  • Everybody who likes drain tanks, this is a drain tank.

  • The big goal of this machine here is to simulate how decay heat is removed from this design

  • when there's a shutdown.

  • That is correct.

  • In January 2015, Kirk Sorensen of Flibe Energy toured UC Berkeley's Compact Integral Effects

  • Test for Pebble and Molten Salt Fueled Reactors. Kirk also presented at UC Berkeley...

  • We're going to talk mostly about the chemical processing and a little bit about the power

  • conversion system as well.

  • ...and the University of Utah.

  • The chemical processing of this reactor...

  • Those two presentations are combined in this video.

  • We're in a situation in our country where we're retiring a lot of power generation right

  • now. This is actually happening particularly in the Eastern US where I live.

  • You can almost trace the outline of rivers like the Tennessee and the Ohio based on where

  • these retirements are taking place. Now, there are things we don't like about coal, and there

  • are things we do like about coal. We like the fact that is a reliable energy source.

  • We don't like the fact that it emits a lot of pollution, and it's not a resource that's

  • going to last forever.

  • There are also new regulations that are coming out that are accelerating this change, so

  • we've got a big job to do. We don't really have a great deal of time to do it.

  • We need a source that mimics all of the benefits of coal-fired power, and tries to eliminate

  • the drawbacks. A number of us are convinced that this energy source is going to be nuclear

  • in origin. The reason for that is, the energies of the nuclear are about two million times

  • greater than the energies of the electron cloud -- the energies of chemical energy,

  • the energies that powers a combustion digestion, all the processes we're used to.

  • Yet, out there in the universe, the universe is powered by the energies of the nucleus,

  • changing nuclear states, fusion and fission and nuclear decay. Humanity has only realized

  • this in about the last 70 or 80 years until we've taken our first steps into a nuclear-powered

  • world. I'm convinced that if we are going to be able to enjoy the industrial society

  • that we have, enjoy reliable energy and improve its cleanliness, we're going to have to make

  • this leap, too.

  • We're going to have to make the leap to nuclear energy.

  • I kind of feel bad when I hear that nuclear reactors are being retired. Even though I

  • know that they're not as efficient as they could be, they're still a whole lot better

  • for the environment than spewing dirty coal into the air. What I'd really like to see

  • is the United States building new nuclear resources to replace our reactors that are

  • being retired, the uranium style reactors, and also to be able to replace coal and fossil

  • fuels.

  • The Department of Energy has put the responsibility for these new nuclear reactors though, squarely

  • in the lap of industry. This is a big deal, because for decades in this country after

  • the war, the Atomic Energy Commission made all the decisions about what was going to

  • happen. It wasn't like industry got to say, "Oh, we want to try this, or we want to try

  • They said, "We're going to do this, or you're going to do that, and you'll submit a proposal."

  • But it was not in industry's court to go and make decisions like this, and now it is. This

  • is a relatively new development, and I think it's going to lead to entrepreneurialism because

  • they've squarely put the onus on us to say how nuclear is going to go forward.

  • Make your business case. Make your argument. If you want a nuclear power plant, say why

  • it's better.

  • What kind of nuclear energy then becomes a logical question. We are blessed on this world

  • with nuclear resources, three forms of nuclear fuel, two forms of uranium, and one of thorium.

  • Thorium is about three times more common than uranium, but the uranium we're using today

  • is only a tiny, tiny, tiny fraction of natural uranium.

  • It's what's called naturally fissile uranium, uranium-235. This is what we're consuming

  • right now for nuclear energy.

  • If you want to make nuclear energy a sustainable enterprise, then you need to go and be using

  • the remainder of these fuels. Thorium has the advantage of abundance. There is an awful

  • lot it, but it doesn't have any naturally fissile thorium. There is no little sliver

  • here that we can point to and say, "This is thorium we can use to start a nuclear reaction."

  • This is one of the reasons why thorium has not been favored for nuclear energy in the

  • early days, but now we've reached a more mature stage, where I think it is time to go ahead

  • and look at implementing thorium as a nuclear fuel. Both thorium and uranium-238 can become

  • nuclear fuels by absorbing a neutron, and this happens inside a nuclear reactor.

  • This is what Glenn Seaborg figured out right here, at Berkeley 70 years ago. Wasn't this

  • was possible? Glenn Seaborg, what a guy. Read all you can about him.

  • If thorium absorbs a neutron, becomes uranium-233, that is now a nuclear fuel. It can fission.

  • It can split, and release energy.

  • Uranium-233, when it's fissioned by a thermal neutron, will produce about 2.3 neutrons net.

  • That's important, because we need a two right here to make this happen in the first place.

  • You've got to have more than two to keep this going.

  • The same thing can happen with uranium-238, which is the common form of uranium, the abundant

  • form of uranium. If it absorbs the neutron, it becomes plutonium-239, and then that can

  • fission, and also release energy. In both ways you can turn these abundant nuclear resources

  • into energy sources. What is the advantage of thorium then? Why think about thorium?

  • Uranium-238 is converted to plutonium through a neutron, but that's thermally fissioned.

  • On that, you only get about 1.9, so you're below two. You're below that threshold. That's

  • why we can't build plutonium breeder reactors in thermal spectrum reactors, just can't do

  • it. There are not enough neutrons.

  • Really, plutonium kicks out enough neutrons. It's just plutonium has a real propensity

  • to eat neutrons, too. If we want to use plutonium efficiently, we really have to go to a fast

  • spectrum, because what happens in fast spectrum is fast neutrons have a much higher probability

  • of fissioning the plutonium without being absorbed.

  • Now, because they have a higher probability of doing that though, they don't have a higher

  • probability of the fission happening in the first place. This is what plutonium looks

  • like to a slowed downed neutron. The blue is the probability that it will fission, and

  • the red is the probability that it will simply absorb the neutron.

  • Each one of these guys is what plutonium looks like to a fast neutron. Every one of those

  • is a better quality hit. You're not going to get an absorption, but you need a lot of

  • it. If you want to have the same amount of cross-section probability, and fast as thermal,

  • you've got to have a lot of fuel, a lot of fuel.

  • This is an advantage of thermal spectrum, because you need a lot less fuel, but because

  • you can't breed in thermal spectrum, the interest has always been for plutonium breeding to

  • go to the fast spectrum. I bring this up because thorium doesn't have this issue. Thorium can

  • go ahead and be used as a nuclear fuel in a reactor with slowed down neutrons.

  • It's called thermalized neutrons. There are a few steps thorium goes through on this way.

  • It first absorbs the neutron and becomes thorium-233, going from 232 to 233. See, the math is not

  • so hard, just plus one. Then that thorium-233 will decay over a period of about a half-an-hour

  • into another element.

  • Protactinium-233. Protactinium is a naturally occurring material. It's part of the decay

  • chain of uranium-235, but protactinium-231, it's got something like, a 172,000-year half-life.

  • This stuff, protactinium-233, has a much shorter half-life, about 30 days. Still, in terms

  • of reactors, that's pretty long. It drives a lot of what I'm going to talk about today

  • with the chemical processing.

  • But ultimately it will decay to uranium-233, as long as it doesn't absorb a neutron, and

  • it has a very quality fission. About 91 percent of the time, it's going to fission rather

  • than absorb, and that makes U-233 the best fuel in the thermal spectrum. It outperforms

  • everything else, and it's one of the reasons we really get a kick out of thorium.

  • There are three options. We can keep bringing U-235, and without getting into issues about

  • seawater uranium, it's just we're using a very small amount, and we're not using a whole

  • bunch of uranium. We can go with the fast freezers I saw yesterday at INL with EVR2,

  • or we can potentially take this tack of a thermal breeder with thorium.

  • The path that we want to go is the thorium, because of its abundance, and because of the

  • fact that we can use it with slowed down neutrons. That makes the reactor design simpler, and

  • quite possibly safer. If you can operate a thorium reactor without any uranium-238 present

  • in the fuel, then you can really reduce the amount of transuranic waste you're going to

  • generate.

  • The reason for that is the thorium absorbing the neutron. Each one of these vertical steps

  • is a neutron absorption. The thorium absorbing the neutron, 90 percent of the time, will

  • be fissioned by the next neutron. At 10 percent of the time, it will go to U-234, which will

  • absorb another neutron, go into U-235. Think of these as like off-ramps off the freeway.

  • If 90 percent of the cars exit the freeway on the first off-ramp, and 85 percent of the

  • cars that are leftover exit the freeway on the next off-ramp, how many are there to make

  • your first transuranic? It's only one-and-a-half percent. With the thorium cycle, you could

  • potentially get down to one-and-a-half percent of the long-lived wastes production of the

  • uranium cycle, and that's a big advantage.

  • On the other hand, when you've got a fuel, like a uranium reactor, it's got a lot of

  • U-238 in it, then it's only one neutron away from its first transuranic. The reason I bring

  • up transuranics is they govern, in large part, our waste disposition strategy. In fact, actinides

  • in general, govern our waste disposition strategy, because they have long half-lives.

  • They have complicated K chains. Our waste disposition strategy is in great part about

  • actinides. Got one of the members of the Blue Ribbon Commission here, so stop me at any

  • time if I screw up here. Here's what we're doing now. This is the red line on a log-log

  • chart. Any line on a log-log chart, tread lightly.

  • This is how long it takes our spent fuel to reach the same rate activities as natural

  • uranium. It's about 300,000 years. If you can keep all the actinides out of the waste

  • stream, then you can really shorten that to about 300 years. One of the goals in the chemical

  • processing system we're going to talk about today is how to keep the actinides out of

  • the waste stream.

  • I hate to even call this stuff that is made by the thorium cycle, waste. Neptunian-237

  • is actually used to produce the material that NASA uses for batteries in their deep space

  • probes. Have you ever heard of the Curiosity Rover on Mars? Anybody heard of that or followed

  • it? That's being powered by plutonium-238, which comes from this neptunium.

  • Anybody following the New Horizons' mission to Pluto, keeping track of that? That's also

  • powered by this stuff, so even our waste, so to speak isn't even really waste. It's

  • something that we could go and make very useful products out of. Like I said, I was at NASA,

  • so I'm really into this kind of stuff.

  • By the way, 2015 is going to be a really exciting year for NASA, because we're going to see

  • Pluto for the first time, and we're going to see the largest asteroid in the solar system,

  • Ceres, for the first time. Cool stuff coming up this year. If you use thorium with this

  • kind of efficiency, something really amazing becomes possible.

  • This was realized almost immediately by Glenn Seaborg. He thought every cubic meter of the

  • Earth has got a certain amount of uranium and thorium in it. It's about two cubic centimeters

  • of thorium and half a cubic centimeter of uranium. If you can use thorium to the kind

  • of efficiencies that we're talking about today, the energy equivalent of these two cubic centimeters,

  • so imagine two little sugar cubes.

  • Think of two little sugar cubes of thorium metal. Milan, can you hold that in your hand,

  • two cc's of thorium? Is that going to hurt you?