Original subtitles

Japan's most powerful earthquake ever...

triggers a monster tsunami.

Fear washes over the nation.

But that's just the beginning.

Ten nuclear reactors

at two power plants are crippled,

threatening the unimaginable.

If Tokyo needed to be evacuated,

I feared the entire nation of Japan

would be paralyzed by chaos.

It became darker and darker.

A terrifying situation.

We were fighting an invisible enemy,

out-of-control reactors.

What will it take to save the country from radiation?

Mankind has never faced

the forces of physics and the forces of nature

that those people faced.

"Nuclear Meltdown Disaster," right now on NOVA.

This is the road to nowhere,

a once-thriving place

in one of the most prosperous countries on earth...

Japan.

Radioactive Japan.

Time stood still here on March 11, 2011.

Houses that aren't homes.

Schools that are silent.

Stores shuttered.

Towns without people.

Past the checkpoints,

the scans,

and the meticulous suit-up,

layer upon layer upon layer of protection

is the place we simply know as Fukushima...

site of three nuclear reactor meltdowns.

This is called the Central Control Room.

All of the equipment at the power plant

is operated from here.

He is a nuclear plant operator.

This is where he has always worked.

He used to live nearby, but now he too cannot go home.

He and his co-workers are ashamed,

scorned by the neighbors they once had.

We've been through so much

in this control room.

It's hard to put into words.

He was here when it happened.

Now he is hoping to make amends

by helping clean up the toxic mess.

Four years ago, this room was completely dark.

We had only small fluorescent lights and flashlights.

We had given up on our own survival.

Now, talking to you with the lights on,

it seems like a lifetime ago.

This is the story of the Fukushima meltdowns.

The infamous events at Fukushima Daiichi, or number one...

told by those who were there and risked everything.

And the lesser-known story of its sister plant

seven miles away: Fukushima Daini, or number two.

It faced the same onslaught and challenges,

but thanks to a little luck and a herculean effort,

it was saved from ending up like this.

March 11, a bad day for Japan and the world,

could have been so much worse.

The inevitable came without warning at 2:46 p.m.

Two giant pieces of the earth's crust,

tectonic plates, move suddenly and violently.

One pushes down, causing the plate above it

to spring upward like a catapult along a 300-mile fault line.

In a nation all too familiar with earthquakes,

it is the largest ever recorded: magnitude nine.

Propagating outward at 9,000 miles an hour,

record-breaking seismic waves careen toward land

and the ten nuclear reactors at the two Fukushima plants,

all of them designed by General Electric,

owned and operated by the largest utility in Japan...

The Tokyo Electric Power Company...

TEPCO.

They are there to feed

the insatiable energy needs of Tokyo.

Suddenly, I heard the earth rumble,

like a fierce growl.

It was an extremely intense earthquake.

But it wasn't only strong, it was also terribly long.

An American nuclear reactor service technician,

Carl Pillitteri, is there doing some upgrades.

It was just one big hammer.

The entire building was moving.

Everything was coming down.

The lights were crashing everywhere.

And it just got worse from there, actually.

In one nanosecond, just the entire floor went black.

The shaking was like nothing I had experienced.

The operators either held onto that bar or crouched down.

That's how we endured the earthquake.

I just wondered,

"How long is this going to continue?"

It lasts six minutes.

Takeyuki Inagaki

is general manager of the maintenance department

for Units 1 through 4 at Daiichi.

He reports directly to the superintendent, Masao Yoshida.

Both men have spent their entire careers at TEPCO.

Inagaki worries about his wife and two sons.

When the earthquake hit,

I think I sent one email to my wife explaining that

I didn't think I'd be able to come home for a while.

After I sent it, we lost contact with the outside.

We couldn't even make calls.

Seismometers at nuclear plants are designed to trigger

an automatic emergency response after an earthquake.

Power plant operators routinely drill for this,

but it is still a risky, tense event.

Called a SCRAM, it is designed to put the brakes

on the nuclear chain reaction of sustained fission.

A nuclear reactor is fueled by uranium,

an element that naturally splits apart,

releasing neutrons.

But uranium fission can induce more fission.

When a loose neutron fires into a nearby uranium nucleus,

it becomes unstable and quickly splits.

Each time an atom splits, it generates heat.

To make fission robust enough to generate power,

uranium is enriched, shaped into pellets,

and then stacked in long tubes called fuel rods.

This ensures lots of uranium atoms

are close enough to each other

to allow a healthy chain reaction.

To manage the rate of the reaction,

control rods that absorb neutrons

are moved in and out of spaces among the fuel.

During a SCRAM, the control rods are pushed all the way in,

terminating the chain reaction.

By 3:02, operators at Daiichi confirm the three reactors

that were online have successfully SCRAM-ed.

And at Fukushima Daini,

all four reactors running full throttle

also automatically shut down safely.

Even though the nuclear chain reaction

has now abruptly stopped,

the uranium fuel rods remain very hot.

It's called decay heat.

The nuclear chain reaction was stopped within seconds,

but the decay heat continued to be a problem.

It takes approximately 20 to 24 hours

for the systems to cool the reactor down

to less than 212 degrees

and achieve what's called "cold shutdown."

At its core, a nuclear power plant

is not unlike a pressure cooker on a stove.

Water is heated to the boiling point,

creating steam.

And steam under pressure turns turbines,

generating electricity.

The complexity and cost of nuclear energy

is about keeping the radioactive genie in the bottle.

So the uranium fuel sits inside rods underwater

in a steel pressure vessel

surrounded by a concrete and steel containment structure

inside a reactor building.

All those layers of protection are there

in case the water stops flowing.

If that happens,

it quickly boils away, exposing the fuel,

and it melts, turning into radioactive magma.

Unchecked, it will melt right through the steel reactor vessel

and on to the concrete and steel containment structure

that surrounds it.

So at the Fukushima plants now, it is critical

that the electric water pumps and valves keep running

for the reactor core to safely cool down.

Power normally comes from the electric grid,

and the earthquake has caused a blackout.

But there is a plan B.

The plant is equipped with diesel electric generators

to provide power in an emergency.

They start automatically, as they're designed to do.

If it had only been the earthquake,

we wouldn't be here today.

The safety systems were doing their thing,

the reactor cores were being cooled,

and things were going pretty well.

When the sea floor suddenly moves upward

during the earthquake,

it causes the water near the epicenter to rise with it.

The giant swell is the start of a tsunami.

Forecasters issue a tsunami warning.

They predict ten-foot-high waves in Fukushima Prefecture.

The main buildings at Daiichi and Daini

are about 30 feet above sea level,

so no one worries much about a tsunami.

And then, at 3:27 p.m...

the first of seven giant waves

crashes over the seawall.

Then I saw the tsunami coming.

I was on top of that hill,

and I wondered if I was high enough.

This thing was, you know...

It was huge.

The tallest surge of water is nearly 50 feet high,

more than twice the height of the seawall.

I assumed there would be a tsunami,

but not one 50 or 55 feet high.

I couldn't even imagine a tsunami like that.

Fukushima Daiichi is inundated.

Two workers drown, trapped in the basement

of the number four turbine building.

Six generators, along with the wiring,

switches, and breakers connecting them to the plant

are located in the basements

of the turbine buildings for Units 1 through 4.

The flood waters destroy them all.

Two additional generators behind Unit 4 are high and dry,

but their switching gear is in the basement,

ruined by the seawater.

The generators would be useless.

Meanwhile, seven miles to the south

at the other Fukushima plant... Daini, or number two...

The crisis is equally dire.

The big waves roll in,

swamping key motors, wiring, pumps, and generators.

Immediately after the tsunami hit,

this room lost power.

That's when I realized something very serious had happened.

Naohiro Masuda is the plant superintendent

on that fateful day.

He began his career here at Daini,

reporting for duty in 1982 while it was still being built.

He knows it as well as anyone.

This building is 40 feet above sea level,

and since there was a power outage here,

I imagined most of the buildings near the sea

were damaged by the tsunami.

From that point on, we knew we were in trouble.

Operators in the control rooms give Masuda very bad news:

Units 1, 2, and 4

no longer have any operative cooling systems.

In nuclear power, we say, "Stop, cool, and contain."

These are the three most important functions.

When I realized that we had lost cooling,

I knew the situation was extremely serious.

But what needs to be fixed?

And how?

He orders a team of about 40 workers

to go out and inspect the damage.

There were several hundred aftershocks that day.

I really hesitated to give the order

to send people out on-site.

They arrive in the rooms

housing electric motors that run the pumps

that draw seawater to cool the reactors.

Cars had been washed right up to the door,

and there were huge piles of debris.

They said, "How could you have sent us to such a place?"

Today, they have preserved some of the evidence of the flood

that wiped out the motors and their wiring.

Electrical supply systems are located in this room.

The tsunami came up to here.

Back at Daiichi,

Reactors 1 through 4 are now in total darkness,

and things are quickly spiraling out of control.

We were in the middle of dealing with the accident.

Then, all at once, the lamps went out.

All sorts of alarms were going off.

All of those went out.

Basically, a station blackout.

"Station blackout"... the two most dreaded words

in the world of nuclear power generation.

At Fukushima Daiichi,

Reactors 1 and 2 not only lose the alternating current

that powers the pumps and valves,

but also the direct current,

there to keep the instruments working.

It became darker and darker,

a terrifying situation.

And the operators weren't sure what was happening.

We couldn't even tell if there was water

in the nuclear reactors.

We were at the starting line of a race,

but we didn't know if we'd need to run 100 yards

or if we'd need to run a marathon.

The oldest reactor at the site is Unit 1.

It began operation in 1971

and is equipped with outmoded last-resort cooling systems

called isolation condensers.

The steam being produced by the hot reactor core

was routed into this large tank of water.

The water would cool the steam, convert it back into water,

and it would drain back into the reactor core

to be recycled over and over again.

It is a passive system designed to work on natural circulation

without any electrical power at all.

So, is it working?

In the darkened control room, they don't have a clue.

What they did not know at the time

is when the power fails, the isolation condenser valves

are almost completely closed,

curtailing the flow of steam and water.

When the isolation condensers failed on Unit 1,

the reactor water level just started boiling away

because it was no longer being cooled and maintained

by the isolation condensers.

If the isolation condensers are working properly,

vents on the side of the reactor building

would be releasing huge amounts of steam.

There was steam coming out of the discharge of it,

but they didn't realize it wasn't sufficient.

So they thought they had more time than they did.

Now, there is nothing to stop the meltdown.

At 3:42 p.m., 15 minutes after the tsunami waves rolled in,

TEPCO notifies the national and local governments

that there is a "special event" at the plant.

Actually, it is an emergency that has never been envisioned.

It was a situation

that hadn't been anticipated.

We couldn't use the procedure manuals.

What was happening was beyond what we trained for

on a daily basis.

Using what little information we had,

we had to decide immediately, "What can we do?

What should we do?"

It was a race against time.

They desperately need power, but from where?

TEPCO dispatches generator trucks,

but they are slowed by earthquake and tsunami wreckage.

When they finally arrive late on the 11th,

damage to the plant's electrical system

makes it all but impossible to connect them.

So they must improvise,

hoping to jury rig their dead instruments back to life

by raiding the parking lots,

grabbing as many batteries as they can from buses and cars.

It took several hours

to figure out how to connect the batteries.

They had the schematic wiring diagram,

and they were furiously examining it for several hours.

We ended up wasting a lot of time.

Meanwhile, the water is boiling away fast in Unit 1.

But how fast?

Six hours after the tsunami, at 9:19 p.m.,

they finally get the batteries

and some portable generators rigged

so the instruments can flicker on.

The gauges show the water level in Reactor 1,

normally 20 feet above the top of the uranium fuel,

is now only eight inches above it.

They pencil in a running record of the water levels

right beside the gauge.

But the pressure in the vessel is so high

it causes inaccurate instrument readings.

They learn later the uranium fuel

had actually been exposed for three hours.

It's becoming more like

a lava flow from a volcano.

So it overheated, melted, released radioactive contents,

and started falling into the bottom of the reactor vessel.

In Tokyo, Japan's prime minister, Naoto Kan,

worries that he might have to order a mass evacuation

from Fukushima all the way to Tokyo:

50 million people.

If Tokyo needed to be evacuated,

I feared the entire nation of Japan

would be paralyzed by chaos for quite a long time.

At 9:23 p.m., he orders everyone

living within two miles of Daiichi to evacuate immediately

so TEPCO can prepare to vent some steam...

Radioactive steam.

At this stage, radioactive iodine-131

is the isotope of greatest concern.

It is linked to thyroid cancer.

Children are most vulnerable.

We knew we had to vent,

but the question was, "How?"

There was no electricity, and the valve was pneumatic.

We needed an air compressor to open it,

but we didn't even have that.

Kan becomes increasingly frustrated and impatient.

Even though we approved it,

many hours went by and they still had not vented.

We asked them why.

A specialist from TEPCO told me, "I don't know the reason."

Much of the information he was getting

from his government and the utility

turned out not to be true,

and he had no source of independent knowledge

of what was going on in those reactors.

Kan decides the only way to know for sure is to go there,

and so early on the morning of March 12,

he flies to Fukushima Daiichi.

He passes over mile upon mile of utter devastation

from the earthquake and tsunami.

Nearly 16,000 are dead.

He lands at Daiichi just after 7:00,

about 15 hours after the tsunami.

I met with Superintendent Yoshida for 45 minutes.

While he explained the situation on-site,

I could see that he was a person who could be trusted.

The prime minister endorses the superintendent and his plan.

Yoshida vows to begin venting at 9:00 a.m.

But there is much to do and much to consider.

To go into a pitch-black reactor building

with the containment vessel pressure so high,

I don't know if I should say it,

but it felt like we were putting together a suicide squad.

To open the vent, they need to manually turn two valves:

one in the basement and another on the second floor.

At 9:04 a.m., a pair of workers makes their way

through a dark labyrinth

to the second floor of the Reactor 1 building.

It takes them 11 minutes to open the valve.

Nine minutes later

a second team heads for the valve in the basement.

They get to a point about midway

and the radiation is higher than they thought they'd get.

They basically had drawn up,

"If radiation gets to this point, we'll go back."

Well, they got to that point before they got to the valves.

They abort their mission.

In the Emergency Response Center, they realize

they must find a way to open the vent remotely.

They scramble to find an air compressor that can be attached

to the pipe that blasts the valve open.

Finally, at 2:50 p.m.,

steam starts rising from the exhaust tower

and the pressure starts dropping.

Could the worst be over?

Actually, it is just about to begin.

At Daini, where the power is still out

and the reactors are getting hotter,

there is a stroke of luck.

There is power inside the radiation waste building

behind Reactor 1.

But they need it down by the water.

Naohiro Masuda decides to lay cables,

hoping to restore cooling to the reactors.

Each of the four reactors needs three operative pump motors.

They need to lay five-and-a-half miles of cable

to connect them all.

He needs supplies urgently...

At least 50 big spools of heavy-duty cable.

Masuda orders the cable, but the shipment is delayed.

The police were busy redirecting traffic

for evacuations

and when the truck hit those detours it wound up going

in the completely wrong direction.

While they wait at Daini,

the crisis is getting much worse at Daiichi.

Uranium fuel rods are encased in zirconium.

If it gets too warm,

there's a chemical reaction between the zirconium

and the water or steam

to produce large amounts of hydrogen.

The containment structure on a boiling water reactor

is sealed with a dome-shaped top that is removed for refueling.

The pressure in Reactor 1 is now so high

that it slightly lifts the top.

The hydrogen escapes through the gap

and into the reactor building, where it mixes with air.

It would be just a matter of time

before the highly flammable gas would explode.

It is 3:36 p.m.

Suddenly there was an upward thrust, an impact that seemed

to push the whole building upward

and it became completely dark.

I thought it was just another aftershock,

but we all sensed something was very wrong.

Then headquarters told me

that the top of the reactor building

was completely destroyed.

When I heard that, I was shocked.

It is a devastating setback.

I think that most of us who were working at the time

didn't feel like we were going to make it out alive.

At Daini, workers are preparing to lay the heavy cables

when they get word of the explosion at Daiichi.

After the explosion, I had everyone outside come back

into the Emergency Response Room.

There were 500 to 600 people in the room.

I said, "Please trust me.

"I definitely won't do anything to harm you,

"but Fukushima Daini is still in trouble

and I need you to do your best."

The cables arrive on the morning of the 13th.

Finally, the heavy lifting to save Fukushima Daini begins.

These were large-capacity motors,

several hundred amperes, so the cables were fairly thick.

Each person had to walk

while carrying around 35 pounds of cable.

It is a race against time and physics.

Normally, If you wanted to lay that much cable,

it would take you about a month.

I didn't actually think it was possible

in the amount of time that we had.

A total of around 200 workers were involved.

We swapped people out when they got exhausted.

In the midst of this, Masuda is running out of fresh water

to cool his crippled reactors.

He asks TEPCO headquarters for a shipment.

I asked Tokyo for 4,000 tons of water,

but instead they delivered

4,000 liters of bottled drinking water.

That made me realize that we were on our own.

We couldn't count on Tokyo.

So we started looking for water.

He remembers a creek used as a water supply

during construction of the plant.

Workers repair the leaky old pipe

with a scavenged bicycle tube.

At Daiichi, events are still overtaking them.

As the dust settles at Unit 1,

they learn five workers are injured.

With freshwater reservoirs exhausted,

they scramble to inject seawater into the reactors.

By 7:04 p.m., success.

But using corrosive seawater

means the reactors will surely be destroyed.

TEPCO headquarters tells Superintendent Yoshida to stop

while they seek government approval.

Yoshida does this very dramatic thing

where on the video conference, he orders the people

to stop the seawater injection.

Before that, he'd called them over and said,

"I'm going to order you to stop the seawater injection.

"Ignore that.

"That's just for Tokyo.

You continue the seawater injections."

Personally, I think the decision

that Superintendent Yoshida made was the right one.

If we had stopped the seawater injection

at that point, I think things would have been much worse.

In the meantime, Unit 3 was becoming unstable.

Now our mission was "Don't let Unit 3 turn into Unit 1."

With no battery power,

they are unable to open the valves to begin venting Unit 3.

And there are no handles on these valves.

So they grab car batteries,

hoping to open them from the control room.

By 9:00 a.m. Sunday, March 13,

the Unit 3 reactor core is exposed and melting.

The pressure keeps rising.

Fearing another hydrogen explosion,

Yoshida orders workers to retreat

to the Emergency Response Center

early on the morning of March 14.

But the pressure plateaus and he lifts the order an hour later.

We alternated between deploying and pulling back workers

because we were afraid of another hydrogen explosion.

Unfortunately, we had close to 50 people positioned

around Unit 3 when the explosion happened.

It is 11:01, March 14.

Since there were so many people out there,

I was really afraid for their safety.

I thought to myself, "It's very possible someone was killed."

Then, one by one, people started to trickle back.

They were all very pale in the face and some were bleeding.

When Unit 3 explodes, 11 workers are injured.

Amazingly, no one is killed.

And when we finally accounted for everyone,

that's when we noticed the water level in Unit 2 was dropping.

It seems inevitable that Unit 2 will be the next to blow.

At noon on March 14, an hour after the explosion at Unit 3,

the water covering the hot radioactive fuel

begins to drop precipitously.

An hour and a half later,

the emergency backup cooling system fails.

Superintendent Yoshida quietly tells a few trusted workers

to prepare buses for an evacuation.

For now he has no choice

but to order his men back into harm's way.

After the explosion of Unit 3,

he begged us to again go to the field to save Unit 2.

It was very impressive.

But by 6:22 p.m., the water is gone.

The uranium fuel is completely uncovered and melting.

Again they try to use car batteries to open the vents

and relieve some pressure.

No luck.

From the 14th

until early in the morning on the 15th,

it was really... how can I describe it?

It was like being in hell.

As day breaks on the morning of March 15,

they hear a loud explosion.

But it is not what they dread.

It is a complete surprise.

There has been an explosion in Unit 4.

But this reactor was shut down for maintenance

when the tsunami hit.

What could have happened there?

And what saved Unit 2 from blowing up?

The investigation will have to wait.

Superintendent Yoshida orders an immediate evacuation

of 650 workers.

He and nearly 70 supervisors would stay.

In the confusion, they become known as the "Fukushima 50."

We were fighting an invisible enemy, out-of-control reactors.

It was like fighting a war.

It is midnight on the 13th.

In the Daini control room, operators are girding

for what seems inevitable:

venting radioactive steam into the environment.

Then the cables and the motors finally start falling

into place, and the mood shifts dramatically.

When we got word

that they were finished running the cable, there was applause.

Then they tested the motors

and reported, "The motors are working!"

And there was more applause.

When the pumps were finally working

for units one, two, and four,

there were three bursts of applause, one for each.

It was such a rush!

I can't believe they did it.

What a team they are.

They pulled off something incredible.

I thought, "They did it!"

The pressure in Unit 1 had risen

to just under the containment vessel's pressure limit.

We had about two hours to spare.

I'd say we made it by the skin of our teeth.

At Daiichi, Superintendent Yoshida has now lifted

the evacuation order,

and workers that had fled start to return.

Things had bottomed out

and for the first time we were able to catch our breath.

Then we started to worry about cooling the fuel pools.

The pools are high up in the reactor buildings,

there to store both spent and new uranium fuel.

There are more than 3,100 fuel bundles,

millions of uranium pellets,

in the pools for units one through four.

They are not inside the containment vessels,

and there are no emergency pumps to keep them full.

Should the pools go dry,

the rods could overheat and catch fire in the open air,

releasing a huge amount of radiation.

This is the worst-case scenario

that has haunted Prime Minister Kan.

It could force him to order a mandatory evacuation

of everyone for 150 miles or more.

Tokyo uninhabitable...

maybe for decades.

It is hard to fathom.

Nuclear plant operator Chuck Casto, then an NRC executive,

arrives at Fukushima Daiichi

in the midst of this turmoil and uncertainty.

The biggest challenge right away,

as soon as I stepped foot on the ground, was,

"Should people take lethal doses to stop this accident?"

The situation was desperate...

Concerns we had never faced before...

And we were trying to work our way through them

the best we could.

It is time for desperate measures.

On the morning of March 17,

Self Defense Forces helicopters fly four daring missions,

hoping to dump seawater onto the Unit 3 spent fuel pool,

which appears to be boiling away.

Radiation forces them to fly high above the plant... too high.

In reality, barely any of the water got into the pool.

And tensions were still running high.

So they turn to an elite rescue squad

from the Tokyo fire department.

They plan to use equipment

designed to fight high-rise fires.

They arrive at the plant late the next night.

They are led by Deputy Chief Yukio Takayama,

a 35-year veteran.

The plan was to get water into Unit 3 by any means necessary.

It needed to be dead on, not like when you put out a fire

and spray the water anywhere you want.

Two thoughts kept running through my mind:

"Please be over soon"

and "What will I do if this place explodes?"

I had never felt

that kind of fear before.

I thought, "This is what it feels like

to really be in trouble."

They get the job done in 20 minutes.

Day breaks.

The water is now flowing.

The fuel in storage is never exposed to the air

and the feared radiation is not released.

Tokyo is saved.

Little by little,

in a small way, we started to have some hope.

Up until then, we were spiraling further down

and now we were dangling there.

We weren't falling anymore.

For the first time in days, Takeyuki Inagaki finds the time,

and a working phone, to call home.

My wife asked me, are you okay?

I could tell she was very emotional from her voice.

I said, "I'm alive for now and I have all my limbs.

Please take care."

In the days and weeks ahead,

the nightmare does not end, but at least it gets no worse.

Concrete pump trucks unleash steady torrents of seawater

onto the fuel pools.

Power is fully restored to the plant, finally, on March 21.

By June, they install a complex filtration system

to remove cesium

from the water washing through the radioactive debris

and flowing into the Pacific.

And slowly the answers start trickling in.

Why did Unit 4 explode?

It used the same vent stack as Unit 3.

When hydrogen built up there,

it seeped into Unit 4 via a shared duct.

Why didn't Unit 2 blow up as they feared?

They realize the explosion at Unit 1 knocked out a door

near the top of the Unit 2 reactor building.

It allowed hydrogen and radiation to escape Unit 2.

While it was venting, the wind shifted toward land,

sending the highest concentrations of cesium

to the northwest.

The fallout will linger for decades.

Eight months after the earthquake and tsunami,

reporters tour Fukushima Daiichi.

Superintendent Masao Yoshida tries to downplay the worry.

The plant is stable enough

for local residents to have peace of mind.

However, it's still very difficult to work

under the current conditions.

Yoshida had been reprimanded by his TEPCO superiors

for disobeying orders and injecting seawater

during the worst of the crisis.

What about his workers?

Six that ventured into the reactor buildings

trying to open the vent valves got the worst doses...

As much as 678 millisieverts of radiation.

5,000 millisieverts is considered lethal,

and 250 is the maximum normally allowed

for nuclear plant workers in an emergency.

The cancer risk for those six Daiichi workers

is undoubtedly greater in the long run.

But during that fateful week,

they all believed there was no long run for them.

To be blunt, there were a number of times

that I thought I would probably die.

We couldn't predict anything.

The worst-case scenario for the meltdown

was that it would get out of control.

I felt that this was possible.

And so I thought, "Maybe this is the end."

One month later,

the hot melted cores finally drop

below the boiling point of water.

Cold shutdown.

By then, Yoshida is gone.

He has cancer, unrelated to his job.

He dies in July of 2013.

Yeah, he was always keeping his head.

Always encouraging people.

He was a good leader.

You might even say he was superhuman.

Not just because of the quality of his decisions,

but how quickly he made them.

Without him,

I could not have...

Yeah, I could not be here.

Fukushima, four years later.

What was once one of the largest nuclear power plants

in the world

is now the center of the most complex, expensive,

expansive cleanup ever attempted.

It could take as long as 40 years.

It will rely on technology not yet invented

and the determination of people not yet born.

The man in charge of it all is the hero of Fukushima Daini.

Naohiro Masuda is now TEPCO's chief decommissioning officer.

It is a very different challenge

than what he faced in March 2011.

This is the first time

anyone has attempted this kind of decommissioning.

No one in the world has this experience.

So when we try to set a goal to work towards,

I can't even give clear instructions

because we're still figuring out what it is we're trying to do.

This is not Chernobyl,

hastily abandoned,

encased in a tomb and encircled by a fence.

This is Japan, where land is precious

and they have a history of rising from ruin.

Here, they hope to erase the painful past

and maybe one day return to their homes.

I was born and raised in this area,

the same area where we are decommissioning.

It's not possible to live here now,

but we all have a strong desire to make it habitable again.

I think that's what keeps us working.

It is a disaster with deep roots at high levels,

bad design decisions,

technological hubris, a broken safety culture.

But in Japan, the sins of the company

are the sins of its workers,

so they are considered culprits as well as victims.

We did what we had to do.

I strongly regret

the inexcusable situation that unfolded.

Mankind has never faced the forces of physics

and the forces of nature that those people faced.

The system may have failed,

but those operators did the best they could with what they had.

In my mind, they were absolute heroes.

There's nothing to be proud of.

Most of the plant workers were born and raised here.

They wanted to protect their hometown,

protect their families.

The reality is,

tens of thousands of people are still under evacuation...

and we're the ones that caused that.

By no means are we heroes.