[ Woman chanting ] -MULLER: Legends say there's a world beneath this one, where a dragon lies sleeping.

They say, "Be careful how you wake the dragon."

Around the turn of the 20th century, uranium is almost unknown.

It is basically worthless.

But then in 40 years, just a single generation, it becomes the most desirable and terrifying rock on Earth.

This is uranium.

And as a physicist, I'm fascinated by its unique scientific properties, but even more so by how this one rock has shaped the entire modern world.

Uranium changes everything.

In our last episode, we discovered how uranium is forged in the explosion of a star.

Uranium is a shape shifter.

It transforms itself.

A lump of uranium will do this all by itself.

We learned how to release the incredible energy inside uranium.

A little bit of mass can be converted into a lot of energy.

We took a rock, and we made a bomb.

On July 16, 1945, at exactly 5:29:45 in the morning, the dragon roars.

Now come with me on a journey into the atomic age...

This is a nuclear reactor.

...an age of promise and fear, where uranium offers a dream of clean, limitless power or a nightmare of a silent and poisoned Earth.

[ Device beeping rapidly ] This is the story of how a rock changed the world.

"Uranium: Twisting the Dragon's Tail" In 1945, America is at war with Japan.

The Americans drop a uranium bomb on the city of Hiroshima.

It explodes like the fiery breath of a dragon.

And then, three days after Hiroshima, another bomb is dropped on the city of Nagasaki.

To look at these pictures is to see the paradox of uranium.

The two atomic bombs have killed at least 100,000 people, but a war that killed tens of millions has ended.

These people don't know it, but they're dancing the old world away.

Tomorrow will be different.

Uranium has brought us a new age.

-NARRATOR: The atomic age was born.

There is no denying that since that moment, the shadow of the atom bomb has been across all our lives.

Wisdom demands that we take time to understand this force because here, in fact, is the answer to a dream as old as man himself, a giant of limitless power at man's command.

-Despite the rubble of Hiroshima, uranium promised a new age.

Its potential was clear.

The atomic fire that destroyed a city could be controlled.

We could harness the nuclear dragon.

No longer would we get our energy from burning coal or oil.

Instead, we would get it from manipulating the fundamental particles of the universe, from within the atom.

The future of the world, a brand-new age, would be atomic.

-NARRATOR: Today we are reaching into the core of nature itself for a source of energy so great that one ounce of matter can yield enough energy to light this 100-watt bulb for one million years.

-MULLER: Uranium promised a new world where everything would be perfect.

-♪ Push a button, turn a dial ♪ Your work is done for miles and miles ♪ ♪ When it hits, it's bound to shake ♪ ♪ Because it feels just like an earthquake ♪ -MULLER: Uranium would take us into a dreamy future of limitless energy.

-♪ It'll send you through the sky ♪ -MULLER: But that future would come at a cost.

-♪ Atomic cocktail -MULLER: After the war, the United States is the only country to possess the secret of the atom bomb.

It's an exclusive club of just one member.

But that's about to change.

In 1949, Soviet Russia tests an atomic bomb.

Two superpowers -- Russian communism and western democracy -- face off against each other.

-MAN: President Truman's dramatic announcement that Russia had the atom secret caused state departments all over the world to stir uneasily.

-MULLER: Uranium fuels a new type of conflict -- not a hot shooting war, but a cold war -- and everyone began to test bigger bombs.

-WOMAN: Here at the Atomic Energy Commission's Nevada test site, a program to test the effects of an atomic blast upon the things we use in our everyday lives.

Naturally, I was very interested in preparations for the testing of textiles and synthetic fabrics.

-MAN: ...7, 6, 5, 4, 3, 2, 1, 0.

-♪ People got worried over the land ♪ ♪ Just like the people in Japan ♪ ♪ God told Elijah he'd send down fire ♪ ♪ Send down fire from the sky ♪ ♪ Sure don't know about the rainbow sign ♪ ♪ Won't be water but fire next time ♪ ♪ You know now ♪ Everybody worried ♪ About that atom bomb ♪ No one seems worried -MULLER: Uranium forces people to confront an elemental power of the universe.

But it also forces them to confront something elemental within themselves -- fear.

-[ Screams ] -MULLER: Uranium transforms into its own unique genre of movie -- the atomic-age monster.

-There it is now, attacking the United Nations building.

-MULLER: But the real horror is that with uranium, we now have the power to destroy all life on Earth.

-♪ We will all burn together when we burn ♪ ♪ There'll be no need to stand and wait your turn ♪ ♪ When it's time for the fallout ♪ ♪ And St. Peter calls us all out ♪ ♪ We'll just drop our agendas and adjourn ♪ ♪ We will all go together when we go ♪ ♪ Every Hottentot and every Eskimo ♪ ♪ When the air becomes "uranious" ♪ ♪ We will all go simultaneous ♪ Yes, we all will go together ♪ When we all go together ♪ Yes, we all will go together when we go ♪ [ Applause ] -Deep underground beneath my feet is the closest you might come to a certain type of hell, a place where the end of the world begins.

-MAN: Hey, Derek.

-MULLER: How you doing?

-MAN: Good.

Welcome to 1-7.

-MULLER: This is a nice ride you got here.

-MAN: Yeah, I'll get it up here for you and we'll have you hop onboard, and we'll take a look around.

-MULLER: Thank you very much.

-MAN: You're welcome.

-MULLER: This facility was operational from 1963 until 1982, and it was built to house a terror weapon from the Cold War deep in an underground silo.

-Well, Derek, this is level 2 of the silo.

We're down some 10 meters below the surface now.

And this...is the launch duct.

And that is Titan II, the largest and most powerful missile weapons system ever deployed by the United States.

It's a 9-megaton weapon.

-MULLER: Compared to Hiroshima?

-Oh, call it 650 times.

An enormously powerful weapon.

The idea behind Titan II was to instill enough fear in the mind of the enemy to cause them to think twice about launching an attack against us, knowing that 10 meters below the desert in our fortified concrete bunker, we can ride out their first strike and live to retaliate.

If we're forced to do that, the consequences for the enemy would be so unspeakably horrible that maybe they would prefer not to get into it with us in the first place.

That's the essence of deterrence.

-MULLER: With the breakup of the Soviet Union and the end of the Cold War, we think that the threat of nuclear annihilation has gone away, but there are still more than 16,000 nuclear weapons in the world today, enough to destroy all of us many times over.

It's easy to fear these terrifying missiles of the atomic age.

But it's also easy to forget that minus their bombs, they carried us into the new world of space.

Neil Armstrong first lifted off atop one of these missiles.

And in 1977, it was a Titan that launched the Voyager {end-italic} spacecraft.

Almost 40 years later, Voyager {end-italic} has left our solar system.

It's still traveling, still sending data.

Its battery is nuclear.

The slow release of its radiation creates heat, which is converted into electricity.

Solar wouldn't work out here, and normal batteries don't last.

These images come to us courtesy of uranium.

Uranium has taken us on an incredible journey.

My journey has brought me to an ancient land that has some of the richest deposits of uranium on Earth, where ancient stories warn that a powerful creation spirit sleeps underground.

Here I met Jeffrey Lee, the traditional owner of this country.

-MULLER: Jeffrey's people believe that disturbing the powerful spirit beneath this land will unleash disaster.

Jeffrey refused a share of $5 billion to mine here.

-MULLER: In the age of uranium, we learned to live uneasily with the dragon.

Then on April 26, 1986, far away from here, at the Chernobyl nuclear reactor, there's a catastrophic accident.

-There has been a nuclear accident in the Soviet Union, and the Soviets have admitted that it happened.

One of the atomic reactors at the Chernobyl atomic power plant in the city of Kiev was damaged.

-MULLER: In 1986, the uranium-fueled nuclear reactor at Chernobyl suffers a catastrophic failure.

Radiation is released across Europe.

-MAN: A radioactive cloud headed north across Poland today and into Denmark, where radiation levels were five times normal, to Finland, six times normal, to Norway... -MULLER: Soldiers are ordered to smother the reactor, and, to limit their exposure to the intense radiation, they're allowed to work for short periods only before they must be replaced by others.

The first responders to the accident in the early hours of that morning were the Chernobyl firemen.

They charged with incredible courage into a massive level of radiation.

They put out the fires, and then they were taken to hospital, where they began to die.

In the nearby city of Pripyat, people are asked to pack a few small personal belongings.

They are to be temporarily evacuated.

But they have never returned.

High levels of radiation mean the city and the countryside around the reactor remain an abandoned exclusion zone... ...the Chernobyl Exclusion Zone.

I'm traveling with a physicist who works in nuclear medicine.

She prefers to be called "Bionerd."

She's been here several times before, studying radiation.

[ Device beeping rapidly ] -BIONERD: So, you can see all these radiation warnings.

-MULLER: Oh, hang on.

I'm getting a rise in levels here.

Okay, we're up over 5 microsieverts an hour.

Whoa.

Up over 8, 9 microsieverts an hour.

The alarm's going off on my Geiger counter.

-BIONERD: The thing is screaming, yeah?

-Yeah, 11 microsieverts an hour.

It's like 100 times natural background.

Natural background is the level of radiation naturally occurring on Earth.

On average, it's around 0.2 microsieverts per hour.

But this place isn't going to be natural.

Bionerd and I are going into the site of the world's worst nuclear accident.

We are going into the city of Pripyat, where the warm forest slowly claims the city.

Visitors are allowed in here, but only for brief periods and never overnight.

This was a model city.

About 50,000 people lived here, mostly workers at the nuclear power plant and their families.

This is what the world looks like without people.

Nuclear reactors like the Chernobyl reactor split uranium atoms.

They smash them into fragments.

And that releases heat, which is how they generate electricity.

When uranium atoms smash, they break into smaller fragments.

And when the Chernobyl reactor blew, it spread those fragments across the city like dust.

[ Devices beeping rapidly ] The light dusting of invisible smashed uranium atoms, still radioactive, is what our Geiger counters are picking up.

The radiation level is about 20 times average background.

That's not too dangerous for this place because the radiation released from the reactor coated the city unevenly, so there's hot spots that are really dangerous, even lethal.

A lot of people are afraid of radiation, but you're not.

Why not?

-What are the biological effects of getting exposed to radiation?

-The most insidious thing about radiation is how invisible it is.

You can't feel it.

You can't smell it or see it.

This could be pristine wilderness.

But it's not.

And even the effects of radiation are almost invisible.

It may make you sick, but perhaps not today or this year.

Maybe you'll find out in 10 years' time that you have a certain form of leukemia.

Was that caused by your exposure to radiation, or were you gonna get it anyway?

And that's the problem with radiation.

That's why people fear it, I think, so much.

I'm about to go into the hospital at Pripyat.

And this is where the firemen were taken after they fought the fires at the Chernobyl reactor.

That is the door to the emergency room at the Pripyat hospital.

This is where the firemen were brought after fighting the blaze over at the Chernobyl reactor.

Their clothing is actually still in the basement, but I want to go down there to see how contaminated that clothing is.

And I want to understand what those firemen went through.

Bionerd says the radiation down there might be 10,000 times higher than natural background, and that's dangerous.

So we need protection.

You don't want to ingest or breathe in this stuff.

And I think this is the time when I get a real sense of the danger of radiation.

It's right here.

[ Device beeping rapidly ] The main radiation down here is from one particular fragment of split uranium atoms.

It's called caesium-137.

And the radiation it's releasing is what you can hear.

[ Beeping continues ] One microsievert per hour -- That's five times natural background.

[ Beeping intensifies ] -BIONERD: [ Speaks indistinctly ] -MULLER: On the floor up ahead, what we have come to see -- a boot from one of the Chernobyl firemen.

-BIONERD: Yeah.

-MULLER: That's 10,000 times natural background radiation.

And then we found a room with a pile of the firemen's gear -- tunics, boots, and helmets heaped on the floor.

That's 2,500 times higher than natural background radiation, and I was happy to stay outside, but then Bionerd went in.

-BIONERD: Yeah.

-MULLER: We had been down there just four minutes, but that was enough.

We had seen the clothing of the firemen of Chernobyl.

Whoa!

That was intense.

Now, to put that in perspective, if you were down there for an hour, that would be what you'd normally receive in a year.

And also, you know, if you receive your dose all at once, that's much worse than having it spread out throughout the year because over that time, your body has time to repair any damage.

But, you know, if you get higher doses all at once, that's when it becomes dangerous.

To understand why this place is still so toxic, we need to understand half-life -- the rate at which radioactive atoms decay.

Imagine this soccer ball is an atom of caesium-137.

It is unstable, and at some point in the future, it will spit out particles, decaying into something that is no longer dangerous, but I cannot tell you when it will do that.

It could be today or next week or even 100 years from now.

But what I can tell you is that if you have a whole bunch of these atoms, then in 30 years, exactly half of them will have decayed -- emitted their radiation and become no longer dangerous.

That is the half-life of caesium-137.

It's 30 years.

Now, it's been about 30 years since the Chernobyl accident, and in that time, half of the caesium-137 that was released has decayed.

And the other half of it is still here, still releasing radiation.

That is why the firemen's clothing is still dangerous.

It's also why people won't live here again for hundreds of years.

Uranium has ensured the people of Pripyat will never return.

Some fragments of split uranium atoms have half-lives of just seconds.

But others, like caesium-137, last for decades.

High above the city, out on the horizon, the Chernobyl reactor itself, and the most astounding half-life of them all -- uranium.

That is the damaged Chernobyl nuclear reactor.

In 1986, after the accident, it was encased in the sarcophagus that you can see now, but it's weathering and cracking and needs to be replaced, so they're building a new confinement structure over here.

They can't build it above the old sarcophagus because the levels of radiation are still too high.

So they'll have to slide the whole structure across.

It'll cost billions of dollars, and this structure will last 100 years.

And that is only a temporary solution because the half-life of uranium-238 is 4.5 billion years.

It's the same as the lifetime of the Earth.

So, in 5 billion years, when all life has ceased on this planet and the Sun is engulfing the Earth, only half of the uranium which is still in that sarcophagus will have decayed away.

But there are other dangerous radioactive fission fragments in there with much shorter half-lives.

And the astounding thing is some of these can be used to save lives.

In this unremarkable building, they take what makes Chernobyl so dangerous, and they make a life-saving medicine.

All right, I am all set, suited up, and ready to go into Australia's one and only nuclear reactor.

This is not a power reactor.

It is a research reactor, and here they create medicine and technology.

The medicine they make here is called technetium-99m.

-COMPUTER: Please enter and pause until counting has finished.

-MULLER: But what's really exciting is where they make it.

-Okay.

Please proceed.

-This is a nuclear reactor.

It's actually an open-pool reactor, which means that the core is visible 12 meters underneath that water.

You can see a blue glow down there, which is actually called Cherenkov radiation, and what that is is electrons moving through the water faster than light can move through the water.

And that creates what's kind of like an optical sonic boom.

That's the blue glow of light which forms a cone behind every electron.

Down there, they are splitting uranium atoms into fragments.

It's the first step in making the medicine technetium-99m.

Technetium-99m has a half-life of just six hours.

It's a crucial medicine used to detect cancer.

Here I met up with Jason.

-MAN: It was actually 2001, and I was playing Australian rules football, and it was a pain in my leg, and it just got worse and worse, and I assumed I had a hip injury and saw an orthopedic surgeon, expecting a hip operation, and he said, "You've got a tumor about that long in your leg."

There's a few key tests, but this one is the key test.

-MULLER: So, what do you reckon?

Should you be radioactive?

-BATSON: [ Chuckles ] You're gonna tell me.

[ Device beeping slowly ] -MULLER: You don't seem very radioactive.

That reading is about the same as everywhere around this hospital.

And now the highly radioactive technetium-99m is injected into Jason.

[ Device beeping rapidly ] I'm getting an alarm off that.

This is the kind of level of radiation we saw in Chernobyl.

-MAN: Injecting now.

-MULLER: And what they're injecting you with is actually fragments of uranium.

-There you go.

-MULLER: [ Laughs ] Doesn't freak you out?

[ Chuckles ] -My eyes are open, and I'm breathing.

-MULLER: [ Laughs ] [ Device beeping rapidly ] As you can hear from my Geiger counter, I'm getting close to a radioactive source.

In this case, it's Jason.

He is actually emitting lots of gamma rays right now.

And in the same way that my Geiger counter picks up these gamma rays, this machine is actually detecting those gamma rays and making a picture out of them, because technetium gathers at the site of fast-growing cancers.

And that allows us to determine if there are any tumors in Jason's body because they'll be glowing quite brightly.

So this allows us to spot cancer earlier and treat it better.

But what about Jason, who's now full of radioactive technetium-99m?

Well, that's where the six-hour half-life kicks in.

[ Device ringing ] -268.

-MULLER: Yeah, 240, 300!

Look at that!

That bit of you is going off.

-Wow.

-MULLER: I saw something similar when I was a few hundred meters from the Chernobyl reactor that blew up.

[ Laughs ] -It's amazing.

-MULLER: Have you heard about half-life?

Have you heard that term before?

-No.

-Half-life means how long it takes for half of the stuff they've put in you to decay.

So, when it's reading right now around 200 microsieverts an hour, the half-life of the substance that they put in you is about six hours.

So, in six hours, this should be reading 100.

-Yeah.

-In another six hours, it'll read 50, and then 25 and so on.

So it cuts in half every six hours.

-Every six hours.

Yeah.

[ Children playing ] -MULLER: The uranium fragments that fell over Chernobyl had a longer half-life than just six hours, and I wanted to know what happened to the people who lived here.

I've come to London to meet someone who knows a lot about Chernobyl -- chair of molecular pathology of cancer at Imperial College London, Professor Geraldine Thomas.

-Hello, Derek.

How are you?

-MULLER: Geraldine has been studying the health effects of Chernobyl through a collection of tissue samples gathered for almost 20 years.

-In the early 1990s, it became apparent fairly quickly that there was an increase in thyroid cancer in those who were very young at the time of the accident.

Thyroid cancer in children, particularly those under about 14, 16, is very, very rare, and it was obvious that more and more children were starting to present with thyroid cancer.

In the case of Chernobyl, there was an awful lot of iodine that was released, and that iodine was shot up into the atmosphere and then came back to Earth very quickly when it rained and was deposited on the ground.

The cows eat the grass, and the iodine becomes concentrated in the cows' milk, which the children then drink.

So, quite a lot of the iodine that's taken in that's radioactive will release its radiation while it's inside the thyroid.

Hence, you get an increase in thyroid cancer.

Iodine is very short-lived in the environment.

It has a short half-life of eight days.

So, within three months of there being a release of radioactive iodine, it has disappeared from the environment.

-MULLER: What I wanted to know from Geraldine was what happened to the people of Chernobyl.

-THOMAS: There were 28 people who were exposed to very high amounts of radiation -- the firefighters who were trying to put out the fire, who died of acute radiation syndrome.

And to date, there have been about 15 deaths from thyroid cancer.

That's all.

More people die from falling out of bed in the U.K. every year than have died from the effects of Chernobyl.

-MULLER: The toll of Chernobyl is controversial.

A United Nations report acknowledges those 15 fatal cases of thyroid cancer and to date, no persuasive evidence of any other health effect that can be attributed to radiation.

The important part, though, is those two words -- "to date" -- because some cancers take decades to develop.

How long do you think Chernobyl won't be inhabitable for?

-Chernobyl is not uninhabitable.

And there are quite a lot of people who live in that area.

They're mainly old people.

People whose land that has been for generations often move back and stay there.

-MULLER: I met Ivan and Maria, who, despite the radiation, have moved back to their village.

You were living here 30 years ago?

Do you enjoy it?

[ Chickens clucking ] [ Speaking Ukrainian ] [ Grunting ] -This couple lives completely off the grid.

They're self-reliant.

They get their own water from a well, use a scythe to cut down their weeds.

They grow their own crops.

I will keep going.

I will.

I'll keep going.

All it took for this to happen was the biggest nuclear accident in the history of life on Earth.

This area is to the south of the reactor, and because the wind was blowing the other way when the accident happened, most of this land is not contaminated at all.

We're reading about 0.15 microsieverts an hour, which is probably very similar to the level of radiation where you are right now.

No one doubts high levels of radiation are dangerous.

What is less clear is how much low-level radiation is dangerous.

-THOMAS: Radiation is a bit like sun exposure.

We know there's a relationship between exposure to the sun and development of skin cancer -- melanoma, in particular.

Now, we all accept that, and we aren't asking somebody to say, "This is a safe dose for sun exposure."

Yet, for radiation, it's exactly the same.

The principles are the same.

A small amount of exposure is perfectly okay.

A large amount of high-dose exposure, as with alcohol, is extremely dangerous.

We're a very long-lived species, so our bodies must have found ways, over our evolution, to be able to cope with low-dose radiation.

It may even be that low-dose radiation is responsible for evolution, because we know it causes mutations, and evolution is related to mutation events in our DNA.

So you can argue that we are extremely well adapted to a low-dose radiation environment.

-MULLER: Life evolved on a radioactive Earth.

Inside the Earth, uranium decay helps keep the Earth hot and fluid.

Our continents slide slowly about the surface like a moving crust, and the movement causes earthquakes, like the one on March 11, 2011, a Friday afternoon, off the coast of Japan.

-WOMAN: [ Speaking Japanese {end-italic} ] -[ Speaking Japanese {end-italic} ] -WOMAN: With just 10 minutes' warning, after the quake came the tsunami -- a seven-meter wave relentless in its power.

[ Alarms wailing {end-italic} ] -MAN: The huge white cloud bursting across the horizon is the number-one reactor shed of the Fukushima Daiichi nuclear power plant.

-WOMAN: Japan has declared an atomic emergency, and there are fears of radioactive leaks from a nuclear reactor in the disaster zone.

[ Device beeping rapidly ] -MULLER: This is the town of Okuma, which has been abandoned for over three years now.

[ Bird caws ] And the level of radiation here is, well, around 5 or 6 microsieverts an hour.

It's a lot higher than natural background, like 50 times higher.

So, people aren't allowed to come in here.

The mask is probably overkill.

It's just to stop radioactive dust from getting into my lungs.

This is definitely one of the most radioactive places where I've been on this trip.

Even though the release of radioactive material was less than Chernobyl, only about 10%, because it's much fresher, there's still much more of it here.

Much less of it has decayed.

[ Device beeping rapidly ] There was another deeply surprising impact of Fukushima.

About 150,000 people were evacuated from around the Fukushima reactor, families compelled to leave their homes.

Many have no choice but to live in portable housing like this.

[ Doorbell rings ] I've come here to meet the Togawa family.

They were evacuated in 2011 and have been here ever since.

Konnichi wa.

-Konnichi wa.

-[ Chuckles ] [ Speaks Japanese ] [ Conversation in Japanese ] -The Togawas are not allowed to return to their family home, but they can visit.

So, leaving the kids behind, Mr. Togawa, his wife, Yuka, and I set off to visit their home.

[ Alarm ringing ] That's my first alarm, which is set around 5.

That was just a little hot spot.

There is an exclusion zone around the Fukushima reactor, just like at Chernobyl.

Access is generally limited to people who used to live in the zone, provided their town is declared safe to visit.

Mm-hmm.

Mrs. Togawa is getting suited up, but it's not because of the levels of radiation.

It's actually just because of all the weeds.

The yard is so overgrown, and there's a lot of little prickly things, little burrs.

The level of radiation here at the house is about 2 microsieverts an hour.

It may get a little higher as we walk into the yard, but I think it should be fairly safe for us to go in there.

We're inside the Togawas' old house.

And when they left three years ago, they thought they wouldn't be away for long, so most of their stuff is still here.

Their kids' old school uniforms.

I just met these kids this morning.

They've definitely outgrown these uniforms.

-MULLER: The hidden cost of the disaster was psychological -- depression, illness, and suicide.

-THOMAS: I hope we have a lot better understanding of what moving people in response to a radiation accident like that does to them psychologically.

And I think the most important studies will be those on the mental effects of disaggregating a community.

And I hope we learn our lesson.

We didn't learn it from Chernobyl.

I really hope we learn it from Fukushima.

-MULLER: Over 16,000 people died in the earthquake and tsunami.

The number who died from radiation in the nuclear accident is, so far, none.

Not one.

[ Sirens wailing, horns honking ] After Fukushima, Japan shuts down all nuclear reactors.

Germany starts doing the same.

And it seems that uranium may be finished as a source of energy.

But our hunger for energy hasn't diminished.

There are now 7 billion of us on this planet.

And from now until 2050, we will use more energy than in all of human history combined.

And uranium, the rock forged in the explosion of a star, crackles with an energy too tempting to ignore.

There are over 400 nuclear power plants in 30 countries and another 70 under construction.

Nuclear power isn't going away.

Billowing out of that chimney is not smoke, but water vapor.

And it's not radioactive at all.

In fact, the reading on my Geiger counter is, well, the lowest I've seen it anywhere in the world.

Now, this nuclear power plant emits no carbon emissions at all.

So, would you consider it green?

Well, only if you overlook a very important problem.

The way most nuclear power plants operate today, they use only about 5% of their uranium fuel.

The other 95% is highly radioactive waste.

Currently, the United States has 72,000 tons of nuclear waste, mostly stored in containers like these.

Some of this waste must be stored for at least 100,000 years.

The safety and security of this waste remains the responsibility of a company -- a board of directors and shareholders -- who will take responsibility for 100,000 years.

But what if there was a way to use this waste?

Dr. Leslie Dewan is one of a new generation of nuclear engineers designing the next generation of nuclear reactor.

-Most nuclear waste lasts for hundreds of thousands of years, and my reactor is able to take that long-lived waste and break it down and extract almost all of its remaining energy.

And if you take all of that waste and put it into these reactors, you could power the entire world for about 72 years, even taking into account increasing demand.

-How is your reactor design different?

-It uses a liquid fluoride salt as fuel.

So, if you have an accident, it's able to shut itself down safely.

Our reactor can run entirely on nuclear waste.

It can't melt down, and it's cheaper than coal.

I think that Fukushima gave us this renewed sense of focus, almost, that we really need to work to improve these nuclear reactors.

We know that there are so many benefits to the technology for making cheap, carbon-free electricity, but it made us more aware of all the work that needs to be done to bring all of the plants into the future.

-MULLER: Leslie thinks her reactor is less than a decade away.

But I wanted to know what it felt like living with one of the current reactors in your front yard.

-MAN: For me, there's measured risk with being next to a power plant.

There's measured risk with, you know, being next to any factory -- chemical factory, right?

Obviously, if there's something catastrophic that happens at a place like this, you know, this place would be a dead zone for 50 years.

-MULLER: Rob and Shannon moved here in 2011, just after the Fukushima accident.

So, tell me about the siren.

What's the idea with it?

-It goes off every first Wednesday of every month.

And it just goes for a while, and then it shuts off.

They tell us it's just to make sure it's still working.

-Yeah, they're just testing-- -Testing it.

-Have you ever heard it go off not on its schedule?

-SHANNON: Yeah, the kids and I have heard it.

We all just kind of stopped, and they looked at me and...

It's just that fear of if it blows, what's gonna happen to us?

Or if there's a leak, what's gonna happen to us?

So, just kind of panicked a little.

-From what I understand, it's one of the cleanest forms of power that we have, and there's no pollutants.

That's the upside.

I guess the downside is if it does it, the two examples would be Chernobyl and Fukushima.

But, like I said, it's a measured risk.

-MULLER: Rob and Shannon might be right.

The entire story of uranium is perhaps one of measured risk.

When I began this journey to understand uranium, I had to wear this badge everywhere I went.

It measures my cumulative exposure to radiation.

I've worn it here amongst some of the largest uranium deposits on Earth, where uranium is actually woven into the creation stories of a people who have lived here for thousands of years.

And I've worn this badge into places where people may never live for hundreds of years.

I discovered how we took uranium, and one morning, 70 years ago in the New Mexico desert, We unleashed the power of the dragon.

We launched ourselves into the nuclear age.

-Men being what they are, wouldn't it really have been better if this thing hadn't been invented?

-Of course you're right, Mr. Vincent.

The energy in the atom is the most destructive force the world has ever seen.

It can also be one of the greatest blessings God has ever given us.

Which is it to be?

Because on that depends the future of mankind.

-So, what should we do with uranium?

As a physicist, I'm tempted to say it's such a great source of power.

It has such incredible energy density and has so many benefits that way.

How can you ignore it?

But after studying it, after searching the world and following the story of uranium, the feeling that I'm left with is that it's not ready to take over.

And seeing how far renewable energy has come, that suggests to me that there are alternatives these days and that we don't need to go with uranium.

We don't need to risk another place like this.

And yet every year, uranium treats disease and every year saves more lives than it has ever destroyed, even including the atomic bombs.

And just imagine a world where next-generation reactors could produce massive amounts of clean, safe energy.

We live in an age where the nuclear dragon has been unleashed.

And where that leads us remains to be seen.

But there is no such thing as a future without uranium.

[ Woman chanting ] Uranium had one last surprise for me.

After all the radioactive places I had been, what was the reading on my radiation monitor?

Well, from natural background radiation, we all get an average of 2,000 microsieverts a year.

And my reading was just 280 more.

For me, the journey was worth the risk.

"Uranium: Twisting the Dragon's Tail" is available on DVD.

To order visit shoppbs.org or call 1-800-PLAY-PBS.