- This ice cube floats in water, as you would expect.

This ice cube sinks.

The difference between these two ice cubes is key to understanding why companies around the world are paying $30,000 a gram for Canadian trash.

(upbeat music) I made both of these ice cubes using exactly 30 milliliters of water, but if we weigh them, we'll see that the one that sinks weighs 32.1 grams, versus the one that floats, which only weighs 30.1 grams.

That's 2 grams more than this one.

This ice cube is made of things that are like water molecules, but are not water molecules.

Instead of the usual H2O, the heavy ice cube's chemical formula is this, D2O.

So the oxygen, that is the same, but the hydrogens have been switched out for deuteriums.

Now, a hydrogen's nucleus is just this, a proton, but a deuterium's nucleus is a proton and a neutron, which weighs the same as a proton, but has no charge.

So overall, a deuterium atom weighs about twice as much as a hydrogen atom, and that means that D2O weighs about 10% more than H2O, and that means that the density of this D2O ice cube is actually higher than the density of liquid water, and that is why the ice cube sinks.

Now, D2O is expensive.

Every gram costs about $1.70, which means this ice cube is worth $51.

Pure deuterium, D2 gas, is even more expensive at $13 per gram.

But there is yet another isotope of hydrogen called tritium, which is one proton and two neutrons, and tritium is way more expensive, $30,000 per gram.

And in Canada, get this, tritium is a waste byproduct.

It's basically just trash, and until recently, it was more or less just thrown away.

But these days, companies are falling all over themselves to buy up Canada's tritium trash.

Why?

Because exit signs, radiation poisoning, and fusion power.

(bright music) Exit signs, literally just exit signs, that is reason one.

Now, most exit signs, including this one, and others like it are powered by electricity.

But some exit signs need to be installed in places where it's a pain to run electrical cable to, or they need to stay lit in case of an emergency that cuts power to the building, and you can't really use batteries because I don't know if you've noticed how many exit signs I've crossed under just by walking 15 steps in here.

I think it's 3.

Oh, no, wait, that's 4.

Can you imagine the number of batteries you would have to replace every single year in a building this size?

Come on.

This sign has no batteries.

it's not connected to electricity, and it can stay bright for up to 20 years.

20 years.

It is powered by Canada's trash, tritium.

So I decided to wander around DC and try and find a tritium exit sign to show you.

Nope, it was not as easy as I expected.

Not those either.

You can even see the power going on this one.

So more wandering.

(bright music) Nope.

You know what's easier find in DC than a tritium exit sign?

A horse's- (exciting music) Again, two more that are not it.

(exciting music) That's not it.

I even checked the Washington Monument.

(exciting music) And they just have a regular old exit sign.

I tried to find a real tritium exit sign out in the world and I just couldn't, I couldn't do it.

We ran out of time.

These little glow in the dark key chain fobs are also powered by Canada's trash.

Each one of these little ampules contains maybe a hundred micrograms or so of tritium.

That's about $3 worth.

Now, tritium is radioactive, which sounds scary and sometimes is scary, but not in the case of ampules and exit signs, because when tritium decays, it turns into helium and it releases these two things, an electron and an antineutrino, and it releases them.

This is the key point.

At relatively low energies, the electron cannot get through sheet of paper, let alone your skin.

And the antineutrino, well, this doesn't really interact with anything at all.

So that solves that problem.

On the inside of this little ampule, there is a thin phosphorescent coating.

And when the electrons from tritium decay hit that phosphorescent coating, they are absorbed and then the energy is re-released as photons of light.

And that's why this thing and tritium exit signs glow.

Now, tritium does occur naturally, but it occurs way out in our upper atmosphere.

A little too far to harvest.

Here on earth, tritium can be produced in three ways.

Way number one is to detonate a nuclear bomb.

We're not gonna do that.

Way number two is to stick lithium and boron rods into the core of a standard nuclear reactor.

This is doable, but it's very expensive and in the US, it requires approval from the NRC.

The third, and really the only economically viable way to make tritium is to not make it.

It's to harvest it from somewhere that is already making it anyway as a waste byproduct.

In this case, a very specific type of nuclear power plant that was developed in Canada.

(patriotic music) And uses deuterium and uranium.

Hence the name, CANDU.

Nuclear fission, can do.

(spatula drums on containers) This is the core of a generic nuclear reactor.

This is the fuel.

And the fuel is usually uranium.

And as you may know, when uranium splits apart, it releases neutrons.

But here is the part that most people don't know.

Those neutrons are traveling extremely fast, 3% of the speed of light.

Now counterintuitively, because they're moving so fast, they actually do not interact with uranium atoms, which means there's no nuclear chain reaction, which means this is actually not really a nuclear reactor, it's just some uranium fuel.

This core does nothing.

But if you surround the fuel with a substance that is capable of slowing the neutrons down to the more reasonable speed of a thousand meters per second, then you can get them to interact with uranium atoms and induce them to split, which releases more neutrons, which interact with other uranium atoms, et cetera, et cetera, et cetera.

And now you have a nuclear chain reaction, which produces heat in the core, which gets converted to electricity.

But all of that depends on slowing the neutrons down.

So how do you slow down a neutron?

Well, to answer that, I built my very own non-regulation sized pool table.

Let's say this cue ball is a neutron.

If I were to roll it into something very heavy like this cement wall, it just bounces off at basically the same speed.

That is not helpful.

And if I roll it into something that is a lot lighter, like let's say this ping pong ball, well, it just keeps going as if the ping pong ball wasn't even there.

That's not helpful either.

But if I roll it into something that's about the same weight, like let's say another billard ball, it could lose almost all its energy in a single collision.

So basically, to really slow down a fast neutron, you need a stationary neutron or a proton.

Regular old water, which nuclear scientists call light water has a ton of stationary protons.

Remember that a hydrogen nucleus is just a proton.

So, plain old water is actually fantastic at slowing neutrons down, but it also has a problem, a problem that we cannot talk about by returning to the eight ball.

And that problem is this.

When a neutron slams into one of these protons, it can bounce off like we talked about before, but it can also fuse with the proton forming a new deuterium nucleus.

And now that neutron is just stuck here.

It's stuck on this water molecule.

It cannot participate in continuing the nuclear chain reaction.

Now it turns out that light water actually absorbs a lot of neutrons, so many, that you need decompensate by making more neutrons in your fuel, which means increasing the uranium 235 concentration in your fuel.

Now, there is a name for this.

You've probably heard of it.

It's called enriching your uranium.

It is very expensive and it is also the first step to producing a nuclear weapon.

But what if you're Canadian?

(patriotic music) And you have the idea to use heavy water instead of regular light water to slow down your neutrons?

Well, heavy water is way less likely than light water is to absorb a neutron because its deuterium atoms are already kind of full.

So, you don't even need to enrich uranium, which is great if you're not interested in a nuclear weapons program.

And it also saves you a bunch money.

But there is a downside to using heavy water.

Because these deuterium nuclei are roughly double the weight of a speeding neutron, heavy water is way less good at slowing neutrons down than regular old light water is.

And that means you need more of it between fuel bundles, which means your core needs to be bigger.

And as we already know from my $51 ice cube that is currently melting at an alarming rate, heavy water is more expensive than light water.

Anyway, Canada went all in on this approach, and now they have a bunch of reactors that use heavy water.

Now, very, very occasionally, a speeding neutron will slam into a D2O molecule, and instead of bouncing off will fuse with one of the deuterium atoms forming TDO, tritium, deuterium, oxygen.

Now, this is extremely rare, exceedingly rare, but there are a lot of D2O molecules in a single CANDU reactor, and there are 19 CANDU reactors across Canada.

So it all adds up to kind of a surprising amount of tritium.

We'll get back to exactly how much later.

Remember earlier when I said that tritium being radioactive was nothing to worry about?

Well, that is true when it comes to ampules and exit signs.

It is somewhat less true when it comes to CANDU reactors because at some point the tritiated heavy water flowing through a CANDU reactor, well, that can leak.

And if it does, you are dealing with the leak of a radioactive substance.

Now the electrons coming out of that radioactive substance cannot get through your skin.

That part is still true, but unfortunately water evaporates.

And now if you're breathing in this radioactive water vapor, the electrons coming off those tritium atoms don't need to pass through your skin.

They have direct access to your internal organs and they can cause significant damage.

But as with any poison, it is the dose that matters.

The people who are most at risk from radioactive water vapor poisoning are not the people down the street from a CANDU reactor.

They're the people who work in the CANDU reactor, especially if their job is to, let's say, fix water leaks.

And don't worry, this is not radioactive water.

I'm not poisoning myself.

Plus we didn't have the budget for it.

So to prevent the heavy water from getting too radioactive over time, it is regularly de-tritiated via this extremely complicated-looking process.

Now what you're looking at here is basically removing the TDO from the D2O and converting it into T2, tritium gas.

Now, once you have that tritium gas, you could just let it sit around, get less and less radioactive over time.

This is what happens with regular nuclear waste.

Or, you could sell it.

Now, there used to be not that many people interested in buying tritium because how many exit signs and ampules can you really sell?

But that all changed because fusion.

Fusion is the process by which two nuclei come together and fuse to form a larger, heavier nucleus.

And this happens in stars all the time and it produces a ton of energy.

But, it can be difficult to get the reaction going because you need temperatures in the millions of degrees.

Stars, they're hot.

This reaction is one of the easiest fusion reactions to get going.

Fusing deuterium and tritium to make helium and a neutron.

And when I say easiest, I mean least ridiculously difficult because you still need a hundred million degrees to get this thing going.

Stars are hot.

For some reason, fusion energy has become the hot new thing for startups to start up.

I mean, like look at this graph of fusion startups over time.

It's honestly kind of amazing.

Anyway, because deuterium tritium fusion is one of the easier fusion reactions to get going, a lot of these companies are specifically interested in it, and that means the demand for tritium has gone way, way up.

So, how much tritium are all these companies competing for?

Well, the entire global supply is expected to peak in the year 2030 at around 27 kilograms, maybe 28.

That's it, 27 kilograms in the entire world.

And remember, tritium decays, it goes bad constantly.

You cannot just hoard that stuff.

Now, this is not an economics channel, but when you have a very expensive to produce product that is produced in minute quantities, sold by only one country, and desired by everyone, the price is gonna be high.