Original subtitles

[music playing]

COREY JOHNSON: This might be the story of history's biggest

secret.

A hidden world of secret cities and classified

nuclear facilities built inside America.

400,000 people were part of it, though only a handful really

knew the truth.

They told us exactly what to do and not to tell anybody.

COREY JOHNSON: It took up half a million acres of land.

It saw the construction of the largest building in the world.

It cost billions of dollars.

And all these resources were focused on one goal,

bringing an end to World War II by building the world's

first atomic bomb.

Six decades on, a team of experts

return to the once classified sites where the course

of history was decided.

In green valleys and dry deserts,

they will uncover and rebuild this lost world.

The Army tore down the entire community called Happy Valley.

It's gone.

COREY JOHNSON: Using the latest in computer technology

and new evidence, the team will uncover the most complex feat

of engineering ever undertaken.

This is the lost world of the Manhattan Project.

[music playing]

Oak Ridge, Tennessee.

In 1941, this was still a remote farming area.

Within two years, according to classified plans and maps,

it was a secret city.

The government realized that this project was

gonna take many, many workers.

So they began to design a city that ultimately would hold

75,000 people.

COREY JOHNSON: It was going to be the home to the biggest

secret of World War II.

The government pretended it didn't exist because this was

part of Project X, the Manhattan Project,

the race to build the first atomic bomb.

Historian, David Bradshaw, explores modern day Oak Ridge.

He's hunting for clues to its secret wartime past.

In 1939, a group of scientists--

Albert Einstein among them-- had warned President Roosevelt

of the possibility that Hitler's Germany might

be close to producing an atomic bomb.

Roosevelt issued an order.

Whatever it took, the US had to be the first

to develop an atomic bomb.

One man, General Leslie Groves, was

given unprecedented authority and unlimited funds

to make it happen.

He would need them.

Well, theoretically, of course, a bomb

was possible in terms of, uh, the physics of it.

But, uh, engineering and all of the other many things

that had to go into making an actual combat weapon, uh,

were quite unknown.

So this was, uh, a pretty big gamble to start off on.

COREY JOHNSON: Land was the first requirement.

The engineers knew that the processes to create the bomb

would be very labor-intensive.

Groves set up facilities in New Mexico, in Washington state,

and here, at Oak Ridge, Tennessee.

David Bradshaw has been searching through the archives

to find out how the Oak Ridge facility was set up.

He's found documents showing that Groves commandeered 59,000

acres of farmland, an area roughly twice

the size of Washington, DC was about to be transformed.

DAVID BRADSHAW: Leslie Groves selected this site

to become the site for the Manhattan Project.

If you had looked out here in 1941,

you would have simply seen rolling farmland, homes, barns,

outbuilding, very rural and very much the way

it had been for hundreds years.

They picked this site because of its protection.

COREY JOHNSON: A study of the layout

shows how this land perfectly suited Groves's needs.

The ridges that surround the land

would shield what happened here from prying eyes.

And the project wasn't just secret, it was high risk.

If something went catastrophically wrong,

the ridge might protect the local population from a blast.

In September of '42, uh, the 1,000 farm owners here received

a very short letter which said, by December of 1942 you must be

off your property.

[music playing]

COREY JOHNSON: Farmers whose families had been working

the land for generations were given only a few weeks

notice to quit.

The only explanation given was that this land would

be used for the war effort.

[dramatic music]

Once the land was clear, the first priority was security.

Probably one of the first security buildings built

was this one.

And it's probably one of the last original ones

still standing.

COREY JOHNSON: These high towers were built to keep the site

under constant surveillance.

It was as heavily guarded as a high security prison.

You entered, uh, probably through a spiral staircase.

There are machine gun ports, gigantic searchlights above us.

None of the trees on this ridge would have been here,

so the ability to have 360-degree security

would have been tantamount.

And I'm sure that's why they selected this spot.

COREY JOHNSON: From his investigations,

David Bradshaw has been able to uncover

the details of the security placed in and around Oak Ridge.

The site was placed under guard and access-restricted.

No one entered without high-level clearance.

All traffic in and out was channeled through seven

fortified checkpoints.

Oak Ridge was cut off from the outside world.

For the next three years, no site in the United States

was more important, more closely watched, or more secret.

And yet, Groves had to bring tens of thousands of workers

here.

He had to quickly build a whole new town from scratch.

A private company was given the task.

The initial brief, as shown on these plans,

was to create homes for 13,000 people--

scientists, engineers, soldiers, construction workers, laborers.

This new community would need shops, hospitals,

schools for their kids.

At the project's peak, 75,000 people would live here.

An investigation of what remains of the secret city at Oak Ridge

today offers clues to the incredible speed with which

this community was built.

Just off the sidewalk, here, are some of the very first

houses in Oak Ridge.

E apartment buildings, probably completed in August of 1943,

built very, very quickly.

This house, this house, this house, all the foundations

would have been laid.

Then, the framers would have come in the next day

and framed maybe a dozen houses in a day.

Then, the plumbers, electricians, finally,

the finishers.

And people would have moved in, maybe one every hour

as these came off the, off the the production line.

Really built only to last for 10 years or so,

60 years later they're still with us.

[music playing]

COREY JOHNSON: This new town would be

a model of suburban uniformity.

What marked out Oak Ridge was its secret mission

to build the bomb.

The Army's next challenge was to entice workers here,

and so they produced this document.

It's really interesting.

It's, it's marketing by the Army.

They knew people didn't want to be coerced into Oak Ridge,

but attracted.

And so they, they developed this document.

Talked about what your house would look

like, transportation, stores and shops, a supermarket,

a furniture store, a moving picture theater.

The, the document is fantastic.

Then, it actually shows the different types of houses.

And it also has the rents.

A type A house was $38 per month.

That includes all utilities, garbage pickup, everything

you would, would want.

COREY JOHNSON: From this evidence,

David Bradshaw has built a picture

of what this place looked like.

In just a few months, 10,000 family homes, 90 dormitory

buildings, and over 5,000 trailers

were built to accommodate a workforce of thousands.

The first workers moved in on July 27th, 1943.

They came in their thousands from all over the US,

answering job advertisements to join the war effort.

When I was interviewed, I said, I'm interested

in, uh, some kind of war work.

And he said, well, this is vital war work.

I said, where will I be working?

He says, well, I can't tell you.

It's secret.

I said, well, what will I be doing?

He said, well, I can't tell you that.

It's secret.

COLLEEN BLACK: I remember coming here

and we had to be stopped at the gate.

They searched the car.

It was scary.

It really was.

And then, when we got into the area,

it was scarier still, because you

think you're coming to a town.

There was no town.

There were just trailers, rows and rows of trailers,

and huts, and all this temporary housing, a lot of mud.

And you weren't supposed to ask any questions.

[music playing]

COREY JOHNSON: Although they didn't know it,

these people were on the front line in a war.

Secrecy dominated their lives.

We had many, many posters up.

"What you see here, what you hear here, when you leave here,

let it stay here".

So we knew if we found out anything,

you know, don't breathe it, don't tell it.

[music playing]

COREY JOHNSON: Now, with the basic structures in place--

the security, the manpower, and the resources--

the real work could finally begin.

95% of the people who worked at Oak Ridge

had no idea of what they were involved in.

But we can now understand exactly what they achieved.

Building the bomb would require vast uranium

processing plants, which would lead to the largest

construction project that the world had ever seen.

[music playing]

As part of the Manhattan Project,

the US military built a secret base at Oak Ridge, Tennessee

during World War II.

Hidden from the world was a city for 75,000 workers

and a nuclear processing plant called Y-12.

The race was on to enrich enough uranium for the world's

first atomic bomb.

100 pounds of uranium was required.

Its production demanded an extraordinarily complex process

that had never been attempted before.

What followed was to be the most costly and most labor-intensive

engineering program in history.

The vast Y-12 complex is still highly secret,

still an active nuclear facility.

Ray Smith, manager here for many years,

is searching what remains of the World War II

buildings for clues to tell their extraordinary story.

Thank you.

COREY JOHNSON: In 1943, General Groves, who ran the Manhattan

Project, ordered the immediate construction of nine

huge industrial buildings.

Below us is the Y-12 National Security Complex.

It was built as a major part of the Manhattan Project.

If you look, you can see three of the nine major buildings.

The cost to construct these buildings was $427 million.

They're made out of concrete and steel,

and the materials were all brought in here-- truckloads

and train loads of materials-- to build this huge facility.

COREY JOHNSON: Each of the nine buildings

averaged 300 by 500 feet in size.

They all remain standing today, and they contain evidence

of how this massive industrial plant was initially conceived.

At the beginning, when they were planning these industrial

buildings-- the nine of 'em-- they didn't really know what

the equipment would look like that needed to be in there.

But they knew that it needed to be large buildings

and that the equipment would likely be heavy.

So it was built with the huge cranes

to lift in any design that might be needed for the equipment

that would be installed to obtain the enriched uranium

for the first bombs.

COREY JOHNSON: Producing uranium for an atomic bomb

was completely uncharted territory.

Speed was of the essence, and there was no time to experiment

or test the process.

ROBERT S. NORRIS: You had to compress everything

into one phase, basically.

You were doing your research and developing a pilot phase

at the very same time you were, uh,

designing a massive building that was going to be the, uh,

industrial facility to make it on a huge scale.

COREY JOHNSON: Only one of the war era buildings still

houses its original uranium processing equipment.

It's called Beta-3, and it was used for uranium separation

right up to 1998.

Until recently, the exact details

of its processes, its location, and construction

were matters of national security.

But by exploring the secret history behind this equipment,

Ray Smith can now reveal what happened here.

RAY SMITH: This equipment, the calutrons,

were actually built by using magnets on either side

of a vacuum chamber.

These units are very heavy.

That's why the structure was built, uh, as sturdy as it

was, to hold the large single magnet that went all the way

around this rectangular shape.

COREY JOHNSON: They were to be the largest and most

expensive electromagnets ever built. To work,

they needed miles of copper wire.

But this was wartime, and all the available copper

was being used to make bullets and shells.

Groves's men hit on a drastic alternative.

Someone had the bright idea, said, why not use silver?

Well, uh, that's, that's a very good conductor,

but where were you going to get it?

Uh, well, you could go to the Treasury of the United States

and decide to get,uh, what eventually were 14,000 tons

of silver that were literally taken out of the, uh,

depository, and melted down, and turned into the wiring

for the magnets at Y-12.

COREY JOHNSON: Once Groves had borrowed the Treasury's silver,

the machinery, known as Calutrons, could be built.

We can now reveal how this equipment worked.

Uranium would be heated and fed out into the enormously

powerful magnetic field.

This force would be enough to separate tiny amounts

of weapons-grade uranium-235 from the original raw material.

38 magnets make up one set of calutrons,

and there are 36 calutrons in this building.

In total, there were 1,152 calutrons on the site.

The magnets were so large that they had to keep people away

from 'em and they couldn't use any tools that might be

attracted by the magnets.

In fact, they put a red line to warn people not

to go any closer.

If you did and you happened to have something in your pocket

that was metal, like a pocket knife,

it'd suck you right up against there.

And it would hold you there.

You couldn't get it off.

And in fact, to get it off, you'd

have to cut the material around the object to get away.

COREY JOHNSON: Evidence shows that the power consumed was

so vast, that for the duration of its wartime mission,

Project X would use 1/7 of all electricity generated

in the United States.

1,152 machines ran 24 hours a day, seven days a week

for a whole year.

These machines were operated not by scientists,

but by female high school graduates.

They were called the Calutron Girls

and they had little idea of what they were involved in.

PEGGY STUART: We knew we were doing something towards the war

effort.

But it was a surprise.

And, uh, we, we were glad that we could contribute to that.

You had, uh, dials that you had to get--

maybe this dial lower and this dial higher.

The units that they were monitoring,

they actually sat in front and would

turn these knobs as needed.

They were actually rheostats that

would change the current going to the magnets in the calutrons

But they didn't know that.

All they knew was this meter needs

to stay on a certain number, and I adjust this one

or I adjust this one to make it move one way or the other.

They had no idea what they were actually doing.

Nothing was ever said.

If you talked about anything, it's, what'd you do last night?

Where'd you go?

But not about work.

All the girls was young, pretty, and very sociable.

And we enjoyed each other.

COREY JOHNSON: Ray has learned that the scientists still

weren't convinced these young high school girls were

capable of doing this crucial job.

RAY SMITH: So they set up a contest where the scientists

operated one bay of controls for the calutrons,

and the Calutron Girls operated another one.

They ran them for a week like that.

And at the end of the week, the Calutron Girls

beat the scientists hands down.

COREY JOHNSON: 2,000 Calutron girls worked

in shifts for six months.

But the process proved so inefficient

that only seven pounds of uranium-235 were produced.

Time was running out.

No matter how innovative the engineering,

to have any hope of meeting the target,

a second plant would now have to be brought online at Project X.

And this would require the construction of the biggest

building in the world.

[music playing]

This crumbling edifice was once the biggest building

in the world.

Called K-25, it was a key building in the Manhattan

Project, and it was designed to increase production

of the desperately needed uranium-235.

Today, K-25 is inaccessible.

It's highly contaminated.

But our experts will discover what this building looked like,

and find the clues to the community that

worked to build it.

1943.

American forces are engaged in a vicious battle

with the Japanese for control of the Pacific.

The need to develop the atomic bomb is as great as ever.

If they are going to produce the 100 pounds needed to build

the bomb, scientists need to find new ways

to obtain the precious U-235.

The solution was a new type of enrichment plant.

If building the town at Oak Ridge

and the vast electromagnetic separation plant

had sapped resources, this new phase

was to present the greatest challenge so far.

They authorized the construction

of a gaseous diffusion plant.

It was a much more difficult engineering problem.

It really was a bigger gamble as far as General Groves

and his people were concerned.

COREY JOHNSON: To get the job done,

they would have to construct the biggest building in the world.

They chose a site 11 miles from the secret city of Oak Ridge.

The first pour of concrete alone would cover 200,000

cubic yards, and tire companies were

requisitioned to provide the thousands of tons of materials

needed.

Thousands of construction workers were required.

Historian David Bradshaw is convinced

that they were housed near the site,

but nothing today survives of this enormous settlement.

The Army, right across the highway,

built a entire community, temporary in nature,

nicknamed Happy Valley by its residents.

But it wasn't so temporary that it didn't have things

like a school, it had theaters, a recreation hall, stores.

Essentially, when the war ended, the Army

tore down the entire community.

Some of the structures were built

on foundations and footers which we think may still exist.

So we're gonna see what we can find and see

if we can find some clues to the community called Happy Valley.

[music playing]

COREY JOHNSON: Happy Valley was built in 1943,

and David calculates that it housed 15,000 people.

It consisted of row upon row of trailers.

Despite the fact that the site is now overgrown by woodland,

clues to what this town once looked like are everywhere.

I think, right through here, is a fire hydrant in the middle

of the woods.

Of course, it wouldn't be in the middle of the woods

60 years ago, it would have been in the middle

of this bustling city which was called Happy Valley.

And really, everywhere you look, even though this is just

the woods today, you see bits and pieces of the thousands

of people who lived here.

COREY JOHNSON: The ground is still flattened where the roads

used to run.

There are remains of sewage channels and water tunnels

across the site.

I think this is a telephone pole.

It looks like it probably powered a facility.

And I think this foundation was probably it.

Looks like a, uh, perm-- definitely

a permanent structure.

This, this is part of a lavatory, I'm sure--

a toilet.

And it probably would have sat just like that, over this.

And it looks like over here, there is a, what's probably,

I imagine was the sink.

So this was probably a men's lavatory for the Hutman area.

COREY JOHNSON: Using evidence from the site, as well as

original plans, David's been able to bring back

to life the temporary settlement of Happy Valley.

[music playing]

For 24 months between 1943 and 1944, this was a thriving town.

Inhabitants were housed in trailers

and endured difficult conditions while they were constructing

the K-25 facility.

This is the building that they were working to complete.

It may be a ruin today, but exploring the site

reveals clues to K-25's top secret past.

At a cost of $512 million-- $10 billion today--

it's the size of 35 football fields built just

to produce 100 pounds of processed uranium.

BILL WILCOX: It's an absolutely fantastic structure.

The building itself is, uh, four stories

high on this side, the outside.

And rather than building a mile-long building,

they folded it into a U-shape.

And what you're looking at is one leg of this U.

This is a half-mile long.

Each of the legs is 400 feet wide.

COREY JOHNSON: The reason the K-25 had to be so enormous

was that the processes going on inside were so complex.

Gaseous diffusion works by filtering

the uranium-238 in gas form to produce the weapons

grade uranium-235.

It's so inefficient the process has to be repeated

many thousands of times.

But such was the desperate need to enrich uranium

to fuel a bomb that no obstacle was too big.

BILL WILCOX: It was, and still is,

the largest building that was built in the Manhattan Project

days.

It's the largest relic that remains.

Uh, and it is just now, as we speak, in the process of being

taken, taken down.

COREY JOHNSON: Today, K-25 is strictly off limits.

But using original plans and eyewitness testimony,

we can reveal what this building would have looked like when it

was completed in 1944.

[music playing]

Documents show that it occupied two million square feet.

It was a half-mile long by 1,000 feet wide.

It housed 758 miles of copper tubing, 3,800 miles

of electrical conductors, and the amount

of water used in its processes would have supplied

a city of five million.

When K-25 began operations, it's recorded

that it took a team of 12,000 just

to hunt for leaks in the piping, which had to be completely

airtight.

Well, my job was to find the leaks in the wells in the pipe.

And the pipes would come in from overhead

and stop at my station.

We found the leak in the pipe and we marked it,

and then the millwrights would come and take the pipe off

to be, uh, welded and sent back.

And that was just all day.

We just wondered what the pipes--

there were big pipes, little pipe pipes with elbows,

all kinds of pipes.

COREY JOHNSON: And of course, security was as tight as ever.

This is my badge that I used when I worked at K-25.

I could go to the restroom, I could go to the cafeteria,

and I could go to my work station, but no place else.

[music playing]

COREY JOHNSON: After a supreme effort,

K-25 began producing the desperately needed

enriched uranium, which would enable Project X to meet

its target in the race to build the bomb.

In July 1944, an armed guard took the first sample

of uranium on a 2,000-mile journey from Oak Ridge to New

Mexico, where some of the greatest scientists the world

has ever known were waiting to work on it.

It would be in the buildings of another secret city

that the bomb would be armed, tested, and built.

That place remains highly classified even today.

It is the laboratory at Los Alamos.

[music playing]

Deep in the heart of New Mexico is the most important site

of the Manhattan Project, Los Alamos.

This is still a top secret facility for the design

of nuclear weapons.

But in the 1940s, it was known simply

as Project Y. This was the site where the bombs that ended

World War II were designed and built.

Very little remains of the original Manhattan Project

buildings, but our team of experts

will search historic documents and crumbling ruins for clues

to reveal how this place looked.

RESEARCHER: Column and footing.

COREY JOHNSON: Archaeologist John Isaacson

has studied the Los Alamos site to understand why Groves

and his scientific director, J. Robert Oppenheimer,

chose this location.

JOHN ISAACSON: We, we're at the site of the, uh,

original main gate to the laboratory that was established

in 1943.

They were looking for a place that was remote--

and in those days, this was very remote--

and that also did not, uh, have any security vulnerabilities

because of the terrain.

It provided the best suite of characteristics

that they were looking for to put a laboratory here.

COREY JOHNSON: When Groves and Oppenheimer came here

for the first time, this site was home to the elite Ranch

School.

The boys were rushed through their graduation,

the land was requisitioned, and the engineers moved in.

The main school hall, Fuller Lodge, remains standing today.

And this really became, sort of,

the social center of the Manhattan Project.

A lot of social events took place here.

COREY JOHNSON: As with Oak Ridge,

Los Alamos was built very quickly.

Its accommodation consisted of temporary homes and trailers.

Oppenheimer would later become known as the father

of the atomic bomb.

He was tasked with gathering some of the finest

brains in America to work with him in this isolated location.

You've just come from a prestigious university

on the East Coast of the United States or perhaps from Europe.

You're recruited to work on a secret project,

you don't even know where.

Then, you're told to report to a train station in Lamy, New

Mexico.

First thing you ask is, where's Lamy?

You're taken on a day-long journey over rutted muddy roads

into this encampment that basically looks like it comes

out of the middle of nowhere.

You're now told, here's where you're

going to conduct one of the most innovative and creative

scientific endeavors in the history of mankind.

You might have thought that you were absolutely crazy

and had gone nuts, but that was the reality of those days.

COREY JOHNSON: It's clear that the conditions in which

this elite group of scientists worked were very basic.

JOE MARTZ: This was a site that was built very rapidly

by the Army.

They used whatever materials were available.

They brought in lumber and they erected shanties and shacks

in which they conduct experiments that

were to revolutionize mankind.

COREY JOHNSON: Over the course of three years, over 600

technical buildings were constructed.

Now, only 30 of them remain.

In amongst the modern buildings of today's laboratory,

John Isaacson and Ellen McGehee are focusing on the site

where engineers created the weapon to detonate

the first atomic bomb.

Structures are down, but that's where the--

COREY JOHNSON: It takes detective work

to piece together the details of what this building looked like

and exactly what happened here.

We're at a building called the gun site,

or also known as the periscope bunker.

And it's the site where the uranium gun device, the uranium

gun weapon was designed.

COREY JOHNSON: The theory was simple,

shoot one piece of uranium down a barrel

to collide with another.

The two pieces would fuse together.

A nuclear detonation would result.

But in practice, the explosion had to be perfectly timed.

This building was where scientific theory became

an engineering reality.

That's the best part [inaudible]..

What was done here was working out

the ballistics, muzzle velocities,

of these projectiles inside the bomb that were shooting

into each other to see if they could get sufficient speed

to have the weapon successfully assemble before it exploded.

[inaudible]

COREY JOHNSON: By studying the plans,

our experts have discovered that this structure supported

a tower that served as a periscope.

This device would have enabled the scientists

to observe and record each shot while they were protected

from shrapnel in the building below.

We're pretty sure that the, the inside

of this periscope tower, uh, it was light tight,

so that they would have probably been using it to,

um, take photographs of the actual tests that

were happening right above.

COREY JOHNSON: The presence of these bolts

indicates where powerful naval guns were anchored

to the ground and shells were fired

in full view of the periscope.

This is an area where we think that the, uh,

naval guns, uh, were situated.

You would have been able to have a clear shot between the guns

mounted here and the periscope structure that is just

a, a little bit to the north.

[music playing]

COREY JOHNSON: Using their findings,

the experts can now bring this lost world to life.

The gun site and periscope were built into the landscape,

and the bunker was covered with a protective three-foot layer

of earth.

The naval cannon on top of the bunker

would have fired the ordnance.

High-speed movie cameras mounted in the periscope

would have allowed the scientists

to calibrate the speed and power of the explosion.

And they would fire these weapons,

and they would understand with great precision and detail

the speed of the projectiles, the time it took

from the ignition of the charge until the projectile began

moving.

Those minor details were very important in ensuring that they

could assemble the critical mass necessary to sustain

the nuclear reaction.

COREY JOHNSON: The tests at the gun site

gave the engineers the data they needed to build a bomb they

were confident would work.

But then, a new scientific breakthrough

indicated that it might now be possible to build a bomb

from a new substance, plutonium, which would prove even more

destructive than the uranium device.

And this bomb would require the building of a totally new test

site, and would present the engineers

at Los Alamos with their biggest challenge yet.

[music playing]

This is the V-site at Los Alamos--

a collection of ramshackle sheds abandoned for years.

Our investigators are here because it

was in these buildings that some of the most dangerous

experiments of the Manhattan Project took place.

By studying new evidence, it's possible to understand

what this lost world looked like and what happened here.

By 1944, a uranium-fueled nuclear bomb

was near completion.

But scientists at Los Alamos have been presented

with another possibility--

to make an even more destructive bomb

from a different kind of fuel.

This totally new material that was discovered,

and that is plutonium, uh, and the scientists had actually

been able to do enough calculations to try

to understand that plutonium would probably be a better

bomb than uranium.

COREY JOHNSON: So a new race was underway.

A whole complex of buildings was constructed at Los Alamos.

ELLEN MCGEHEE: This area is called V site.

But during the war, this was actually

called technical area 25.

They, they came out here and used this little area

as a special, sort of, um, high security secret area

for working on the implosion device.

COREY JOHNSON: The engineers were

entering uncharted territory.

But they knew that what they were going to attempt

was highly dangerous and would require a new type

of explosives research.

The idea is to start with a sphere of plutonium

and to compress it using high explosives to a point where now

it could sustain a critical reaction.

This was a challenge for explosive development.

Normally with explosives we would blow things up, not

try to blow them inward.

And so the implosion concept was created.

COREY JOHNSON: The military needed this work done fast,

so no time was lost in building the explosives workshops.

JOHN ISAACSON: A lot of this stuff

was salvaged from other construction--

Absolutely.

--projects, because when they decided to build this area,

it was just like, come on, we gotta get a place to put this

together.

Grab some stuff from other places around the la, uh,

around the laboratory, and throw it together,

and get us a building as quick as you can.

COREY JOHNSON: The designers knew that the people working

at the V site would be handling powerful, often

unstable, high explosives.

The experts have been able to identify a series of safety

precautions which were built.

This is part of a, uh, a surface that

was around the buildings in this whole area.

And this is uh, a spark, uh, suppressant material that

was on the ground because they're

working with high explosives.

COREY JOHNSON: There wasn't just the threat of sparks.

[thunder booming]

There was also New Mexico's freak weather to contend with.

This is one of the highest lightning strike

areas in the United States.

So during the summer, during the monsoon period,

we get lots of lightning.

And so lightning is a major issue

in this whole high explosives area.

COREY JOHNSON: The engineers' role at the V site

was to pack the explosive tightly around the plutonium

core, and to verify that there wasn't even the smallest

gap, as this might disrupt the critical detonation

process which had to be totally uniform.

The big fear was that in such high-risk operations,

an accident might ignite the many tons of TNT stored

in the huts.

And so key buildings were surrounded

by protective outer walls called berms.

Now, this is the berm back here behind us, of course, that

was, that was built as a protective device

for the high explosives.

JOHN ISAACSON: And these berms really

were designed, uh, during the project

to protect people and buildings behind it, so that if there--

it would limit the damage if there was an accident.

COREY JOHNSON: Using original plans and new evidence

from the site, our experts now understand

how this protective technique worked.

[music playing]

Next to each workshop, a 12-foot berm

was erected, held in place by shock absorbing metal rods

and backfilled with earth.

In the event of an explosion, there

would be no saving the people inside.

The purpose of the berm was to protect the surrounding area.

The ordnance engineers who were sent into the workshops

to assemble the high-explosive charges

were aware of the dangers they faced.

One of them was George Kistiakowsky.

Kistiakowsky was asked by, uh, someone, you know,

weren't you afraid of, you know, drilling

into these high explosives and pouring

in this molten high explosives that they would explode?

And he said, well, you know, if it exploded,

I would never know.

So he was pretty blasé about the whole thing.

And I think they had an attitude that a certain level of risk

was acceptable because, because it was wartime.

COREY JOHNSON: By May 1945, two implosion bombs had

successfully been built. The engineers

persuaded the military to let them test one

of these precious new devices.

But there was great concern.

Should the test fail, the plutonium might all be wasted.

Ellen McGehee has been studying this strange concrete bowl,

which she reveals was a device to salvage

the precious plutonium.

They were worried that when they did the test, that, um,

that basically the conventional explosives would detonate,

but they wouldn't have an exothermic reaction.

And that the world's, or close to the world supply

of plutonium, would just basically

get scattered to the winds.

[music playing]

COREY JOHNSON: The engineers' solution

was to build this huge bowl, over 220 yards in diameter.

If the plutonium didn't detonate,

the exploding TNT would simply scatter it into this pool.

The water would be filtered and the plutonium collected.

But with time running out, this approach was abandoned.

The engineers decided to proceed with the test

without attempting to recover the plutonium if it failed.

The world's first test of a nuclear bomb

was set for the 16th of July, 1945,

to take place in a huge area of desert

200 miles South of Los Alamos called Alamogordo.

Before this first detonation, the engineers

feared that the bomb might not be powerful enough, or worse

that they had created something that

was entirely uncontrollable.

JOE MARTZ: So one of the great uncertainties associated

with the first test was how much energy that the test would

produced, what would be the yield of the weapon?

Indeed, scientists took a number of wagers as to

whether or not the ignition of that device

might cause a reaction between the nitrogen and the oxygen

in the atmosphere, and thus ignite the atmosphere

and cause a total conflagration.

COREY JOHNSON: 27 months of work, vast human and material

resources mobilized in secret at a cost of over $2 billion.

It all culminated here, with the detonation

of the first atomic bomb.

The local population reported a blinding white flash

visible for a radius of 150 miles,

and audible for 200 miles around.

ROBERT S. NORRIS: A press release was prepared ahead

of time saying that an ammunition dump had exploded,

and that was what caused the, um, bright light to occur

on the dawn of July 16.

And, uh, lo and behold, that was printed in the paper,

and, uh, people, I suppose, said,

well, I guess that was an ammunition dump,

and, uh, took the newspaper at its word.

COREY JOHNSON: Few witnesses realized

they had seen something which would define history.

The greatest force for destruction that the world had

ever seen, borne from the largest construction project

ever undertaken.

SIG HECKER: Uh, the logistics are mind boggling.

I mean, it takes 27 months these days

to do an environmental impact statement.

Uh, and these gentlemen were able to put everything together

in that time frame.

COREY JOHNSON: Three weeks after the test,

the first uranium bomb would explode over the Japanese city

of Hiroshima, and the plutonium bomb would destroy Nagasaki

three days after that.

With war over, these buildings were

allowed to fade and crumble.

They were hidden behind razor wire fences and a wall

of secrecy.

Communities like Happy Valley disappeared from sight forever,

but their legacy lives on in a new generation

of technological secrets born out of the lost

world of the Manhattan Project.

[music playing]