Jim Al-Khalili uncovers the story of Sellafield. He encounters some of the most dangerous substances on Earth, reveals the nature of radiation and even attempts to split the atom.
Browse content similar to Britain's Nuclear Secrets: Inside Sellafield. Check below for episodes and series from the same categories and more!
Lying on the remote northwest coast of England
is one of the most secret places in the country.
65 years ago, it helped make Britain a world superpower.
And within its walls is material that could devastate life on
this island and beyond.
This is Sellafield.
Costing around £2 billion a year, it's the most controversial
nuclear facility in Britain.
I'm a nuclear physicist
and I've been fascinated by this place for much of my career.
I've heard the stories about the extraordinary experiments,
the jaw-dropping machinery and the incredibly costly science.
And I've also heard about the problems,
the risks and controversies, the terrifying accidents.
I got a phone call, "Pile one's on fire."
I said, "Good God, you don't mean the core?"
He said, "Yes."
Now, they're giving me and the television cameras
access to discover the real story.
We're going inside Sellafield.
We've been given access
to some of Britain's most secret buildings.
It's eerie being so close to something so deadly.
That's the first time it's been touched in, probably, 51 years.
I'll be encountering some of the most dangerous substances on Earth.
It's your dose for the year.
-That's your dose for the year in one...
OK, so we should go out of the way now.
I'll reveal the nature of radioactivity.
And I'll even attempt to split the atom.
I believe that Sellafield tells a unique and important story...
..because it reveals Britain's attempts past, present
and future, to harness the almost limitless power of the atom.
It's why I think the tale of this place is one of the most
important scientific stories of our age.
I'm just about to go through the main gate and into Sellafield.
I have to say, I'm pretty excited, but also a bit nervous, because
I've had to go through some very tight security procedures to get in.
Over the last few months, all my personal details have been
heavily vetted by the security services.
And, of course, every piece of filming equipment has had to be
very, very carefully checked and re-checked.
Now, finally, we're ready to be let in.
This intense security is a reminder of how potentially dangerous
what's stored here actually is.
In the wrong hands, much of this material would be deadly.
From hereon in, we're operating under strict national
security procedures, and some of the images on this film
are going to have to be blurred out.
We can't show building numbers or routes or security cameras.
I can already see experimental nuclear reactors, power stations
and nuclear storage facilities.
There are over 1,000 separate buildings.
In fact, this site covers over six square kilometres.
It's the most complex nuclear facility in Europe.
One of the first impressions I get is that this place is buzzing
Radioactive waste and spent nuclear fuel arrives here nearly every day.
In case of an incident, there are regular drills by the security
and emergency services.
And all with good reason, because some of the most dangerous
buildings in the world are here at Sellafield.
I'm going to start by visiting one, because in here are clues
that reveal the story of Britain's entry into the nuclear age.
This is one of the infamous Sellafield storage ponds.
The size of eight Olympic swimming pools, it's the largest open
nuclear pond in the world.
For about a decade, between the mid 1950s and 1960s, this five metre
deep water was used to store a huge range of nuclear waste,
all sorts of experimental nuclear fuels, highly radioactive
isotopes, hazardous irradiated debris and contaminated leftovers.
And, now, Sellafield is starting to clear these so-called legacy ponds.
I think go for this one.
The hundreds of tonnes of waste down here are a physical record of
the history of Sellafield.
And hidden deep within this debris is evidence of the top secret
project that started it all.
Britain's race to build an atom bomb.
In 1945, the world looked on in awe as these terrifying new
nuclear weapons were unleashed on Japan.
Their extraordinary power came from inside the atom.
And it was a German chemist, called Otto Hahn, who first stumbled
across the power inside an atom almost by accident.
In 1938, in his Berlin laboratory, Hahn was investigating
a metal called uranium.
This tiny disc is a sliver of uranium.
This is what the fuss is all about.
Now, uranium is the heaviest naturally occurring element.
Its nucleus is made up of over 200 particles, protons and neutrons.
Otto Hahn was fascinated by uranium and wondered what happens
when a single neutron hits the nucleus.
But what he found when he did his experiments...
made no sense at all.
Now, I know this is a cliche and I've said it many times before,
but this single experiment really did change the world for ever.
Without realising it, Otto Hahn had taken the first step
into the nuclear age.
For what we think is the very first time on television,
we're going to re-create a version of the actual experiment carried
out by Otto Hahn three-quarters of a century ago.
This accelerator will produce a beam of particles containing neutrons.
And I can drop this piece of uranium right in its path, just down here.
Now, turn on the beam.
Just like in Hahn's experiment, my uranium is being bombarded
One hour later and it's fizzing with radioactivity.
Now, with uranium, gamma ray spectroscopy always shows
these three energy peaks.
This is the unique signature of uranium.
But after bathing our sample in neutrons for an hour,
we get a different picture.
Have a look at this.
Now, in yellow, we get the same three uranium peaks
but we also get a new one.
Because this peak is the characteristic signature,
not of uranium, but of barium.
But the nucleus of a barium atom is about half the weight of uranium.
So, how can a single neutron turn heavy uranium into light barium?
The only possible explanation is if the nucleus of uranium
is splitting into two roughly equal fragments.
What we've done in this lab today is exactly what Otto Hahn
did in his experiment.
We've split the atom.
I believe Otto Hahn's accidental discovery in 1938
marks the beginning of the nuclear age.
Because his experiment showed that something even more
extraordinary had happened.
The two fragments produced by the uranium nucleus weren't just
falling apart, they were exploding apart with enough
energy from a single nucleus to move a grain of sand.
Now, that may not sound like much,
but imagine how much energy could be produced
if every one of the billion trillion uranium nuclei split in our sample.
Just think what might be possible if this experiment could be scaled up.
Within just four weeks of Hahn splitting the first uranium atom,
a scientist in Washington drew a diagram on a blackboard.
The diagram was of a new kind of weapon,
and the scientist was Robert Oppenheimer.
The creator of the atomic bomb.
Six years later, his nuclear weapons brought the Second World War
to an abrupt end.
So where did that leave Britain?
If it was to be a superpower alongside America and Russia,
it needed a bomb of its own.
So, far away from prying eyes, deep in the Cumbrian countryside, near a
hamlet called Sellafield, plans were afoot to join the nuclear arms race.
In fact, the government first built all of this as a top secret
military research facility.
It was called Windscale.
And its aim - to make plutonium for a British atom bomb.
In here is the prize the Windscale scientists were after.
This is plutonium.
Just like uranium, when atoms of plutonium split or fission,
they release a massive burst of energy.
But there's a catch.
Virtually the only way plutonium can be made is out of uranium
in a nuclear reactor.
So, for four straight years, 5,000 people toiled day and night
to build one.
The science was so new and experimental that the plans
would change almost daily.
But despite this, in October 1950, just ten days behind schedule...
..the Windscale nuclear reactor was finished.
This is the heart of it.
Otto Hahn's experiment on a massive scale.
This is the reactor itself.
Over 20 metres high...
weighing over 2,000 tonnes...
containing over 70,000 uranium rods.
Inside this reactor, the scientists hoped to turn uranium into
plutonium for their bomb.
But to do that, they needed to trigger a chain reaction.
Inside this box are 120 primed mouse traps,
each one with a ping-pong ball on top.
Let's see what happens when I drop this single ball in the top.
One ball triggers more and more mouse traps.
This is a chain reaction.
The Windscale scientists believed their reactor would trigger
a chain reaction, that, in the process,
would turn some of the uranium into plutonium.
As each uranium atom splits, it also releases neutrons.
And just like the ping-pong balls triggering the mouse traps,
these neutrons could split new uranium atoms.
So, if they got it right, the uranium would trigger a massive
nuclear chain reaction, producing enough neutrons to turn some
of the uranium into plutonium for the bomb.
Very nice. That's the genius of the chain reaction.
That was the theory, but nobody knew for sure if it would actually work.
The development work that should have been done was all cut
short by the extreme political and military pressure on them,
the very, very tight deadlines they were given.
You did feel that we were in the vanguard of being something
Everybody was on a learning curve there, really, from, you know,
ground floor to top level.
In October 1950, the Windscale reactor was finally started up.
This was the moment of truth.
Inside the reactor, the chain reaction began.
In the space of just four years, we'd gone from a basic
understanding of nuclear fission to a working nuclear reactor.
The uranium started to turn into plutonium.
But, frustratingly, the process was agonisingly slow.
It took six months in the reactor until there was enough
plutonium to begin to extract it.
I broke down the reaction vessel myself, scrambled around
amongst calcium fluoride, to see if I could find anything.
And there I found a piece of plutonium about this size, about
the size of a 50p piece, 132 grams, and that was our very first piece.
But by 1952, they'd managed to get enough to make
the first British nuclear weapon.
And it was detonated in Montebello Island
in Western Australia.
That lethal cloud, rising above Montebello,
marks the achievement of British science and industry.
At last, Britain had entered the nuclear age.
These weapons had revealed just how much energy there was
within the atom.
But for the nuclear physicists there was another realisation,
that the same science that had split the atom
and produced the bomb could also be used for the betterment of humanity.
That it also had the potential to produce almost limitless
cheap energy, energy to power our cities, light our homes
and forge a secure future for everyone.
Because as well as producing plutonium, the reactor produced
heat, and that heat could be harnessed.
The dream was that the power of the atom would come out of the
shadow of the bomb and into our living rooms...
And, once again, Sellafield was at the very heart of the story.
Here, in 1952, work began on an ambitious experiment in power
generation that would shape the modern world.
It was called Calder Hall.
And when it opened in 1956, the nation celebrated.
This new power which has proved itself to be such a terrifying
weapon of destruction is harnessed for the first time,
for the common good of our community.
This is the control room of Calder Hall Reactor One,
the nerve centre
of the world's first commercial nuclear power station.
On the 27th of August, 1956,
heat generated from a nuclear chain reaction
was used to turn water into steam,
which drove a turbine that generated electricity.
That electricity now poured into the National Grid.
Britain had become a nuclear-powered nation.
Within ten years,
eight new nuclear power stations were turned on across the country.
Puffed up with scientific zeal,
politicians announced that nuclear power was so cheap
they wouldn't even bother metering the electricity.
At its peak, Calder Hall provided enough electricity
to supply hundreds of thousands of homes.
Today, I'm being allowed inside Calder Hall.
I'm about to see something that as a theoretical physicist
I've only ever imagined,
the core of a nuclear reactor, where the uranium rods actually sit.
Well, I'm at the heart of Calder Hall Reactor One
and down here...
beneath my feet is the core itself.
'Just ten metres below me are thousands of radioactive
'uranium fuel rods.'
'I'm with the inspection team
'that's going to check the state of these fuel rods,
'and that means opening up the core itself.'
So, what exactly will we see today?
-When I take the blank off...
..and then we'll take the shield plug out,
put a spiral camera down and you'll be able to see into the reactor.
What sort of things do you hope to see with the camera?
Top of the fuel elements.
To make sure that there's no nasties in there.
That's right, yeah, there's no obstructions or anything like that.
I'm, I'm feeling the,
the usual combination of excitement and nervousness.
Right, so we should get out of the way now?
This is the protective shield plug
that sits just above the core itself.
This reactor was shut down 12 years ago,
but despite that the core is still hot,
with radioactivity, which they monitor closely.
-When the plug came out...
That's something like, I guess how much,
a dose you'd get from a C-Scan or something like that.
-That's your dose for the year.
-Your dose for a year in one...
-..full of radioactivity there.
The team also regularly monitors the physical state of the rods.
'And the only way to do that is by remote control camera.'
This is us going down through standpipe,
heading down into the reactor floor.
-It's a long way down.
-Yeah, it's 20 feet.
OK, Robert, can we stop there?
Whoa. Here are the channels.
-Those are the channels within the standpipe.
And each channel, that's where the fuel rods...
That's where the fuel rod is
and there's either five or six fuel elements in each channel.
The flashes on the picture
are the effects of the powerful radiation on the camera.
that's the glimmer of the top of a fuel element you can just see there.
Just about see them shining.
Eventually, all these uranium fuel rods will be removed.
Not many people get to look down into a reactor core
staring at a fuel rod.
Calder Hall has, without doubt, been a scientific success story.
It proved that nuclear power really worked.
But just over a year after it opened,
this age of optimism came to an end.
The nuclear forces that Otto Hahn unleashed back in 1938
had unexpected consequences.
Inside the Pandora's box of the atomic nucleus,
along with the hope of unlimited energy,
-was a dark secret...
..that these forces were hard to control.
And this became terrifyingly apparent
in the Windscale fire of 1957.
Monday, 7th of October,
the Windscale reactor was shut down for routine maintenance.
But then, something strange happened.
Instead of cooling, the temperature inside started to rise.
My grandfather was part of the team working here. Um...
the evidence and the information that was being relayed to them
indicated something was amiss.
I walked up on to the top of the pile
and I saw a monitor up there
and he said, "It's too hot. There's too much radiation."
Eventually, someone peered into the core itself
from a hole at the top of the reactor just here.
They saw something no-one had ever considered possible.
The core itself was on fire.
I got a phone call from the General Manager.
He said, "Tom, Pile One's on fire."
I said, "Good God, you don't mean the core?"
He said, "Yes."
And we didn't know what we could do to stop it.
The fire raged for three days.
Workers risked terrible radiation burns trying to push the fuel
out of the reactor, using anything they could lay their hands on.
But despite this, the fire continued to burn.
So, they came up with a new plan...
they'd flood the core
and turn off the cooling fans.
It was a huge risk.
If you look at the size of the reactor face,
each one of these tubes has fuel in,
so the risk of setting them all on fire is immense.
If they were wrong, the whole reactor might explode.
You've got this blazing inferno
with these flames belting out and hitting the back wall.
Mankind had not faced anything like this ever before.
-They had no alternative.
They hit the switch.
The air goes off and psst...
just like that.
The fire was finally out.
But a new danger became apparent.
Flames had melted the casing surrounding the nuclear fuel
and some of the elements had burst.
Radioactive material escaped out and up the chimney.
A cloud of smoke began to fall over the area.
As the wind blew it eastwards, it seemed catastrophic.
Thousands of square miles might be contaminated.
Hundreds of people could die.
But it didn't happen.
Thanks to one man.
I'm now in the lift, climbing the 120-metre high chimney
that was built to release the air
used to cool the nuclear pile down below.
Now, at the time, no-one imagined that releasing this air
out into the atmosphere was in any way hazardous.
Well, almost no-one.
Seven years earlier, the Windscale Project had been masterminded
by a physicist called John Cockcroft.
He'd made his name in 1932,
when he'd knocked together the world's first atomic accelerator.
It was made out of packing cases and tinfoil
and eventually won him the Nobel Prize.
After this chimney was built, Cockcroft had a moment of doubt.
What if the cooling air became contaminated?
Now, no-one on his team believed this could actually happen,
but Cockcroft was intransigent.
He demanded that his engineers build a filter here
at the very top of the 120-metre chimney.
They laughingly called his idea "Cockcroft's Folly."
Of course, he got his way.
You can still see where the filters were slotted in
across the top of the open chimney.
As the cloud from the fire below belched out of the chimney,
Cockcroft's Folly trapped almost all of the radioactivity.
Designed by a maverick genius, built on a whim, this basic filter
saved the North West and beyond from a terrible fate.
This was the world's first nuclear accident
and it served as a powerful warning that harvesting nuclear energy
could lead to some unexpected and potentially lethal consequences.
In the decades that have followed,
there have been other more serious incidents at nuclear plants
around the world.
Three Mile Island,
Now, terms like contamination and radioactive leak
are for ever etched in the public consciousness.
I think what haunts us about radioactivity
is that it's invisible,
and sometimes deadly.
At Sellafield itself, it's something of an obsession.
Every time I leave a building,
I'm checked and re-checked for any signs of radioactive contamination.
But what exactly is radioactivity?
Radioactivity is, in fact, three different processes,
each one dangerous in its own particular way.
They're called alpha, beta and gamma.
Let me show you with this radioactive source.
Now, this is a mineral called pitch blend
which emits all three types of radioactivity.
The first type is alpha radiation.
Now, these are the emission of tiny lumps of nuclear matter
made up of two protons and two neutrons called alpha particles.
They're spat out from a nucleus, like uranium.
Now, alpha radiation is very short-ranged
so I have to bring this detector very close to the source
to pick them up.
And even a thin sheet of paper will stop them almost completely.
Of course, alpha radiation is still dangerous
when it comes into contact with skin
or if you breathe it in or ingest it.
The second type of radioactivity is called beta radiation.
Now, these are tiny particles, electrons,
or their cousins, the positrons,
that are spat out of a nucleus at very high speed.
When I switch my detector to beta radiation,
we see that these particles are more penetrating,
passing straight through paper...
..but a sheet of aluminium blocks them.
But beta radiation is also very dangerous -
in fact, if exposed to it, it can burn the skin.
Beta particles can even penetrate the skin
and burn the tissue beneath.
The third type is gamma radioactivity.
Now, this is the emission not of particles of matter at all,
but tiny lumps of light -
high energy photons that fly out from the nucleus.
Now when I look for gamma radiation,
I see it passes easily through the aluminium,
but a sheet of dense metal like lead effectively blocks them.
To show you just how damaging gamma radioactivity can be,
I've got these two plants.
Now, one I'm going to place safely out here
and the other inside this radiation furnace.
This will blast the plant with a huge radiation dose -
about the same as that given off by a spent nuclear fuel rod.
Within minutes, the powerful radiation starts to affect the plant
and our camera.
The white snow is due to the radiation striking the camera's sensor.
After an hour, the plant is transformed.
Look at that -
the leaves are hanging limply, some of the flowers have fallen off.
Compared with the healthy specimen, that looks a real mess.
Under the microscope,
we can see the damage done to the irradiated sample.
Now, this is what a healthy sample should look like -
beautiful, clearly defined cells, nice clean cell walls.
And here is our irradiated sample -
the cells are burnt, the cell walls have been damaged...
and all this from just radioactivity.
It explodes as energy...
In the 1960s and '70s,
public understanding about the effects of radioactivity grew...
..and so, too, did their unease with the nuclear industry itself.
The cosy, optimistic, clean image of the '50s had changed.
Hey, hold it!
But the government kept faith with the nuclear programme
and pushed ahead.
Here at Sellafield, they built the Windscale Advanced Gas Reactor
and, across the country, there were others -
By the mid-'70s, over a dozen nuclear power stations
were producing a quarter of Britain's electricity...
..but they were also producing huge amounts of radioactive material.
Virtually all of it was sent here, to Sellafield, for storage.
And as we now know, this is nasty stuff.
So, what on earth were they going to do with it?
Back then, some of it was simply stored deep underwater
in these vast open-air storage ponds.
Hundreds of tonnes of spent fuel rods and radioactive waste
were effectively dumped.
Worryingly, there wasn't a long-term plan for any of it.
By the 1980s,
one of the defining issues for opponents of the nuclear industry
was radioactive waste.
Low-level waste should be the easiest to dispose of.
In fact, it's simply dumped,
left to the rain to leach it away, perhaps into local streams.
Opposition to the nuclear industry grew
over fears about the amounts of radioactive material
they felt was being moved around the country.
By the early '80s,
there was a battle for the hearts and minds of public opinion.
Nuclear power is not safe, not economic, not needed
and certainly not worth the risk.
The focus of the argument was the disposal of nuclear material.
The environmentalists on one side,
trying to stop its movement around the country...
..the nuclear industry on the other...
The flask wasn't significantly damaged...
If they distrust us, we've said, "All right, well, we'll show them."
..going to extreme lengths to try to prove how safe it was
when it was being moved.
But dropping the flask wasn't enough.
It had remained intact and totally safe for the public
had it contained actual radioactive materials.
And all the time, radioactive waste and spent uranium fuel rods
were still arriving at one place -
It was gaining a reputation as Britain's nuclear dustbin.
Then, on the 18th of November 1983,
something happened here that damaged Sellafield's reputation irrevocably,
so badly, in fact, that many people questioned
whether the plant should be closed down altogether.
That morning, scientists at Sellafield looked out to sea
and saw an inky black slick.
It was a slick of waste pouring out of Sellafield.
Something had gone wrong.
Highly radioactive waste went into this tank by mistake
and much of it was discharged to the sea.
Now, it's easy to point the finger in retrospect
but, without doubt, a certain complacency had set in at Sellafield -
a day-to-day lack of forethought and safety.
Due to basic miscommunication,
stored radioactive water was accidentally released out into the sea.
Suddenly, more than ever before,
their safety record was a matter of public concern.
Greenpeace had been monitoring the discharges when the slick appeared.
They sent the dinghy
to the Government's Radiation Protection Board for tests...
The local environmental pressure group wants Sellafield closed.
This incident appeared to confirm the environmentalists' worst fears -
accidents like this were bound to happen.
The future of Sellafield appeared to hang in the balance.
But, actually, plans were already in place to change the way
they dealt with radioactive waste and the spent fuel rods.
The most ambitious of all...
was this -
the Thermal Oxide Reprocessing Plant, Thorp.
Costing more than £2 billion, it opened in 1994.
It's one of the world's largest nuclear reprocessing plants,
designed to deal with spent fuel rods safely...
..and to commercially extract the uranium from them to be used again.
In the '70s and '80s, when uranium was thought to be scarce,
this was a huge idea
because this uranium can then go back into nuclear power stations.
Reprocessing had been done at Sellafield before
but nothing like on this scale.
This is the receipt pond.
It's here that the spent fuel canisters arrive
from power stations all around the world.
It's in this pond that they're first opened up
and the spent fuel rods removed and then taken to the storage pond.
Then, the empty flasks are lifted up, taken away
and washed to be used again.
Meanwhile, the spent fuel is moved here -
a massive storage pond.
The water acts as a shield,
blocking the radioactivity while it cools down...
..a process that can take up to five years.
Once the fuel rods have cooled down underwater,
they're ready for the reprocessing to take place.
Now, first of all, they have to be monitored because we have
to make sure that they contain what they say on the tin.
These rods come from reactors from all round the world.
Once that's done, they can be taken up through that entry there
into what's called the sheer cave.
Once they're in there,
they're behind two metres-thick concrete walls
and they're beyond any human contact.
Through metre-thick glass,
you can see the machinery used to cut up the rods
before being dissolved into boiling nitric acid.
The next stage is to extract the pure uranium.
Each one of these machines is an agitator
and it just has a stirrer on the bottom
which mixes up the nitric acid feed with the solvent.
In my plant, the uranium is contacted with solvent
and we get just pure uranium.
The entirety of my system happens behind two metres of concrete.
I can never touch or never go anywhere near the vessels in my system.
The actual equipment attached to this motor is metres beneath me,
in a tank that, until we decommission the plant,
no-one will ever see again.
Thorp reclaims the uranium as well as plutonium
from the spent fuel, so that it can be used again.
This isn't disposal - it's reprocessing.
Thorp gave a much-needed boost to Sellafield.
Attitudes to safety appeared very different from the '70s and '80s.
It seemed to be taking waste management seriously.
But although 97% of the spent nuclear fuel is recycled
here at Sellafield, that still leaves 3% as waste...
..and that 3% is a problem
because it's very, very toxic.
When Otto Hahn carried out his experiment in 1938,
his fissioned uranium famously produced barium,
but there were other products, too -
krypton, strontium, caesium, iodine, xenon
and exotic heavy metals like americium, berkelium and curium.
Some of these are powerfully radioactive,
others have half-lives of thousands or hundreds of thousands of years.
This cocktail is the most toxic end product
of the entire nuclear industry.
This nuclear waste is so dangerous
that exposure to it would kill you within hours.
In the '90s, Sellafield designed a process that -
while it wouldn't render it harmless -
would at least lock it away.
Currently, this is the end of the road
for this foul and dangerous stuff.
To render it safe and stable, it's vitrified,
which means it's encased in glass,
and that process takes place in here...
..albeit behind a metre of lead glass
that shields me from the intense radiation.
The process is simple enough -
the highly radioactive waste is first dried to a powder.
It looks a bit like this, strangely like coffee granules.
Then, glass granules are added to the mixture
and it's heated to about 1,100 degrees.
It melts and is poured into those containers in there.
Now, the important thing about vitrification
is that it then solidifies as it cools
so there's no chance of leakage.
It looks a little bit like this.
So, the radioactive waste is now not encased in the glass,
it becomes part of the glass itself.
Those containers are then sealed, they're decontaminated
and taken away for storage.
And this is where the containers of vitrified waste are brought.
Under this floor, they're stacked up to ten deep.
They're air-cooled and monitored 24 hours a day.
The radiation produced by the waste down below is so intense,
it produces heat that I can feel up here on the surface,
even though I'm shielded by over two metres of concrete.
This is where several thousand tonnes of the most toxic waste in the world is stored,
and here is where it'll currently remain.
But, ultimately, what makes this nuclear waste so deadly
is not just the high level of radioactivity,
but the length of time it remains that way.
Every isotope is different -
some are active for just seconds,
others remain radioactive for millions of years.
This facet of their character
is captured by something called the half-life.
To show you what I mean, I've set up an experiment.
I'm bombarding a sample of quartz with a proton beam.
This will make it radioactive.
It's produced an isotope of nitrogen that is radioactive.
It's producing beta particles
and these are counted by this device here.
Now, to give you an idea of what a half-life means,
I'm going to record the activity every minute for half an hour.
OK, so it's now showing that 1,400 beta particles per second
are being emitted.
So, that's 1,150 counts after one minute.
Dropping right down.
Now down to just under 700 after five minutes.
So, here's what my graph tells me.
My sample started off with a count rate of 1,400 per second.
After eight or nine minutes, that had dropped by a half
and then by a further half after another nine minutes.
This period of time over which the count rate drops by a half
is called the half-life.
And this is important because, unlike my sample -
which has a half-life of nine minutes -
some of the material at Sellafield
has a half-life of hundreds of thousands of years.
In other words, it won't be safe for thousands of generations.
And this means that much of the work here is now about finding ways
to store this material safely for a very long time.
In the early days, they built nuclear reactors
with little thought of what to do when they came to the end of their working lives.
For instance, this experimental reactor built here at Sellafield in the '60s
was finally shut down in 1981.
Sellafield decommissioned this core by building a giant robotic arm
that reached inside and cut it up into fragments.
It then put all those dangerous radioactive pieces
into large steel reinforced concrete boxes.
And those boxes are stored here at Sellafield,
in this air-conditioned warehouse.
This, then, is the decommissioned core of a nuclear reactor.
It's very unnerving hearing the radiation detector
making so much noise.
In fact, these levels are completely safe -
still, it's eerie being so close to something so deadly.
These concrete blocks will contain the radioactivity
until it's relatively harmless, some 100 years from now.
But just across the road
is one of the most controversial problems facing Sellafield today -
cleaning up the waste from the legacy ponds.
This is the First Generation Magnox Storage Pond,
acknowledged by Sellafield themselves
as one of the most dangerous buildings in Western Europe.
And that's because the ponds that nuclear waste was dumped in
for decades are deteriorating.
Contaminated water is seeping through the internal walls.
Sellafield's current plan is to remove the waste
from these ageing ponds, mix it with concrete
and then store it in steel containers.
They're already using a remote-controlled vehicle
to start that process.
You can see some of the components have come apart.
What sort of stuff is down here?
We have a significant amount of spent nuclear fuel.
There are quite a lot of reactor components and isotope cartridges.
Do you want to try and lift that one up, Helen?
How long has that component been in the pond?
Erm, that's the first time it's been touched in probably 51 years.
It seems a whole range of different things are there -
why were they all put in the pond together like this?
The pond was there supporting the effort towards getting us a bomb together.
It was rushed,
We had to get that bomb ready for the early '50s
to prove that we had it, and, once we had the bomb,
I guess things got forgotten about.
Right. Well, now that you've sort of made me somewhat nervous,
I still would like to have a go.
Give it to me when you know I can't do any harm!
-So can I look inside what's in here?
This one has got isotope cans that have corroded.
-So all of that is...
-It's started to bow and overflow.
the nastiest kind of buried treasure you could imagine!
How dangerous is this stuff?
In situ, as it stands with a five-metre water covering,
it's less dangerous than you would imagine.
The dose rates coming off it are minimal.
However, if some of the material were allowed to dry out,
that would be a different matter -
it could cause a major contamination hazard.
The fact that this stuff is down there and is so nasty -
for many people, this is an argument against nuclear power,
"Look, this is the sort of mess that it creates."
This is certainly an argument against the way things were dealt with 50, 60 years ago,
but we have a duty to clean it up.
We can't just leave the hazard for yet another generation.
And yet, in some way, I can't help feeling we are still leaving it
for another generation, just in safer stores.
The waste from the ponds will be stored in steel containers.
The dead reactors are just stored in concrete blocks.
And the most radioactive material of all,
the vitrified high-level waste,
is still in a warehouse on site here at Sellafield.
I think we do need long-term options for this waste.
Can we store it safely in places like this for 100 generations?
The current long-term plan is to bury it deep underground,
locking it away for ever...
..but this plan continues to divide opinion.
Personally, I believe that if we do bury it,
we have to have the option of being able to retrieve it
at some point in the future
because if we're to have a nuclear industry -
and I think we should -
we need to deal with this waste permanently.
And one possible option that fascinates me
is to find a way to transmute it -
bombard it with a high energy, high intensity beam of neutrons
that smashes it up into far less harmful fragments.
I think this is an option worth exploring
because I believe nuclear power, alongside renewables,
is crucial for our future energy needs.
The story of Sellafield is the story of the British nuclear age.
Sellafield began as a headlong rush to develop nuclear weapons and nuclear power
with little thought to the future.
It appeared to be a success...
..then the cracks started to show -
leaks and the fire released deadly radioactivity
out into the air and sea.
And successive governments and, indeed, the public themselves
demanded that the nuclear industry clean up its act.
With massive investment,
Sellafield seemed to enter a more responsible phase
in managing nuclear waste.
And, as we deal with the issues of climate change,
it seems we might be on the cusp of a new nuclear age.
Where I'm walking now is a proposed site
for the next generation of nuclear power stations,
just a few hundred metres from Sellafield -
so in the shadow of the very first.
This seems a poignant place
to ponder the lessons we can take from Sellafield.
We've understood, slowly and not without mistakes,
that if we are to have a nuclear industry,
then we have to think in the long term -
not just for the quick buck or because of political pressure,
but in terms of the many decades, even centuries,
it takes from conception all the way through to the end of clean-up.
And this is an important lesson, not just for the nuclear industry,
but for any of mankind's more ambitious projects -
be they scientific, engineering, political -
we must take the long view.
Otherwise, well, we have learnt nothing.
Lying on the remote north west coast of England is one of the most secret places in the country - Sellafield, the most controversial nuclear facility in Britain. Now, Sellafield are letting nuclear physicist Professor Jim Al-Khalili and the television cameras in, to discover the real story. Inside, Jim encounters some of the most dangerous substances on Earth, reveals the nature of radiation and even attempts to split the atom. He sees inside a nuclear reactor, glimpses one of the rarest elements in the world - radioactive plutonium - and even subjects living tissue to deadly radiation. Ultimately, the film reveals Britain's attempts - past, present and future - to harness the almost limitless power of the atom.