think I can save the world with nuclear power.

The slide is a little bit tongue in cheek, but not really.

So right now, the world's energy economy

is dominated by fossil fuels.

But that's untenable.

Just look at the air pollution in China.

You'd think that nuclear power would be an obvious solution

to the problem because it's a well developed technology

that produces large, scalable amounts of electricity.

But nuclear leaves us with its own very nasty problem,

which is nuclear waste, which is radioactive for hundreds

of thousands of years.

So imagine a technology that solves

both of these problems, the clean energy

production and the waste.

And this actually exists.

I have this nuclear reactor that can run entirely

on nuclear waste.

It consumes the waste reducing its radioactive lifetime

while simultaneously generating enormous amounts

of electricity.

Right now, just to put some scope on the problem,

there's 270,000 metric tons of high level nuclear waste that

exists worldwide, and no one knows what to do with it yet.

Most of this waste is just sitting

above ground in spent fuel casks like this waiting for someone

to come up with a solution.

And that's where my technology comes in.

We can take this spent nuclear fuel and extract almost all

of its remaining energy, which translates into a very, very

large amount of electricity.

To put some numbers on it, you can

take all 270,000 metric tons of spent nuclear fuel that

exists worldwide and turn it into enough electricity

to power the entire world for 72 years-- so powering

the entire world for 72 years, even

taking into account increasing demand, while simultaneously

getting rid of almost all of its nuclear waste.

So there's enormous potential here.

The reactor units are small enough

to be co-located with existing nuclear power plants.

So you can consume the waste without it ever

having to leave the site.

And this plant can also run on very low enriched fresh uranium

fuel, which let's it unlock 75 times more electricity

from a given amount of uranium than is

possible with conventional reactors.

The basis of our approach is a liquid

fueled nuclear reactor that's powered by uranium dissolved

in a molten fluoride salt.

The design is actually based on earlier work conducted

in the '50s and '60s at the Oak Ridge National Lab

in Tennessee.

That's where these images are from.

They were able to successfully build and operate

a similar plant called a molten salt reactor that

ran on fresh uranium fuel.

And they showed that it had many safety benefits.

But the project was canceled pretty quickly thereafter

because it was bulky, had a low power density,

and it couldn't be justified on its great safety grounds

because the world hadn't yet experienced Chernobyl,

Three Mile Island, or Fukushima.

So how does it work then?

It works, actually, because what we

call nuclear waste isn't actually waste at all,

because it has a tremendous amount of energy left in it.

Conventional reactors, which are shown in the figure here,

are fueled by pellets of solid uranium oxide that's

held in place by a thin metal cladding.

The metal has to be thin so that it doesn't absorb

too many neutrons, but having a thin metal cladding

means that it's readily damaged by the radiation that's

within the reactor core.

And the accumulating damage limits the amount of time

that the fuel can spend in the core

to about three or four years.

But the problem with this is that it

means you can only extract around

4% of the energy you could conceivably

get out of the nuclear fuel.

So that's, in a way, why the nuclear waste is so dangerous,

because there's so much energy that's left in it.

What we do instead in this design

is take out the spent fuel assemblies

from the conventional reactor, remove the metal cladding,

and dissolve the fuel pellets into a molten fluoride salt.

We don't have any cladding, any metal framework,

in our reactor, nothing to get damaged,

so we can leave the fuel in our reactor

for, essentially, as long as it takes

to extract all of its remaining energy.

And the cool thing is that this also

reduces our radioactive lifetime by a very large amount.

So conventional reactor waste is radioactive for hundreds

of thousands of years, but the majority

of the waste coming out of our plant

is only radioactive for a few hundred

years, which is still a long time.

But humans can build things-- structures and repositories--

that last for a few hundred years.

So that makes it solvable.

This is a very rough schematic of what the reactor looks like.

So up on the far left, you have the primary loop

that has the molten fuel salt flowing through it.

On the very far left, you have the reactor core

where the fuel salt is in a critical configuration, which

means you have a large, stable number of nuclear fission

reactions that are generating a great deal of heat.

This heat is carried from the primary loop,

through an intermediate loop, and into a power production

loop where it powers a turbine that drives a generator that

produces electricity.

So the right side of the plant is all very standard.

Now, just to recap here, the main difference

between conventional nuclear reactors and molten salt

reactors is that molten salt reactors

use a liquid fuel rather than a solid fuel.

But then-- this is what the next two slides

will describe-- what makes my company's design

different from the other earlier molten

salt reactors, the ones that were

abandoned in the '60s and '70s?

The main two changes we make are to modify the materials used

in the moderator and the fuel cell.

A moderator is used to slow down neutrons to the right energy

level so that they're more likely to induce fission.

The early molten salt reactors used graphite

as a moderator, which worked.

It was able to go critical.

But it made the cores very large and bulky, low power

density, expensive.

We came up with the idea of, instead,

using zirconium hydride as a moderator, which

is much more effective at slowing down neutrons

and lets our core be a lot more compact, power dense,

and cheaper.

The other thing we changed was the salt.

So the early molten salt reactors

used what's called Flibe salt, which

is a mixture of lithium fluoride and beryllium fluoride.

But using this salt meant that you

had to enrich the uranium 235 up to 33% to 93% uranium 235

is what your uranium enrichment had to be,

which is not commercially available because it's

very close to weapons grade.

And they also couldn't run on the spent nuclear fuel.

So what we did instead was switch it

to a different type of salt, lithium fluoride and uranium

fluoride, that lets us run on the very

low enriched fresh fuel or the spent nuclear fuel.

And you can see as well that we get a really big increase

in our power density at the same time.

Now, this one is by far the most technical slide here,

but it's worth it.

It's good.

So with our two new materials, the moderator and the fuel

salt, it's pretty simple substitutions,

but it enables a world of difference in the design.

So this is what's called the neutron energy

spectrum within the core.

Transatomic is the big blue line on this graph.

Because we're able to slow down neutrons

much more quickly from the fast region to the thermal region,

they're able to transition more quickly,

so we avoid this epithermal region in the middle.

Our line is much lower down there.

And that's good, because in the epithermal region,

you have a lot of neutrons lost where they're absorbed

by the wrong isotopes, they exit the system,

they're captured by things you don't

want them to be captured by.

So you want to avoid the epithermal region.

Which is good.

We do that.

We also, therefore, have more neutrons on the fast end

of the spectrum for breaking down the long lived

components of the waste and more on the thermal end

of the spectrum for power production.

So this is exactly the sort of dumbbell shaped spectrum

that you want here.

I talked before about the safety benefits of this type of plant,

and this is enabled by the liquid fuel.

This is one of the really crucial things about it

that they proved out at the Oak Ridge National

Lab 50 years ago.

In a conventional nuclear reactor,

you need a constant supply of electric power

to pump water over the core to keep it

from heating up catastrophically.

That's what happened at Fukushima.

But in a liquid fueled reactor, you don't need that at all.

What we have instead is what's called a freeze valve that's

at the bottom of the primary loop of the plant.

And the freeze valve contains a plug

of salt electrically cooled so that it's frozen solid.

If you lose electricity, through an accident say,

you lose cooling to the freeze valve, it melts.

And all the salt from the primary loop

drains into an auxiliary containment.

When it's in the auxiliary containment,

it's not near any moderator.

And also just based on its geometry,

it's no longer critical.

So it's not generating nearly as much heat.

And the small amount of heat that it does produce

can be sunk by natural convection loops that

don't require electricity.

And then over the course of a few hours--

this is the crucial bit-- it freezes solid.

So when it fails, it fails into a frozen mode

not like a liquid mode.

And this is that our reactor is what's called walk away safe.

So if you lose electric power, and even

if there aren't any operators on site, it'll coast to a stop

and stay that way indefinitely.

Here's another rendering of the design.

So the technology is great, but to get

these built, it also has to be cheap, of course.

And luckily, we have that going for us too.

If we use current construction techniques,

it's about 2/3 the cost of conventional nuclear power

right now.

And even more importantly, we can be cheaper than coal.

And these numbers will improve as we

move towards a more modular design and other more advanced

construction techniques that are being developed

in parallel in other parts of the industry.

We've raised significant funding so far,

in addition to money from the US Department of Energy,

filed patents on our design, and gotten a thumbs

up on the technology from our great advisory board that

includes the former chief technology

officer of Westinghouse and the head of MIT's

nuclear engineering department.

So just to wrap it up super quickly, because I'm

pretty close to out of time, what the world needs right now

is a cheap, carbon free alternative to fossil fuels

to feed its growing energy demand.

And this technology makes that possible.

So with this design, we've solved nuclear safety and waste

problems, we've beaten coal, and we've

made this safe, clean, and affordable answer