Horizon (1964–…): Season 48, Episode 6 - Fukushima: Is Nuclear Power Safe? - full transcript
Fukushima, north-east Japan.
This is as close as you can get
to the site of a partial
nuclear meltdown six months ago.
But the events still unfolding here
have consequences for us all.
Energy is the lifeblood
of our civilization.
But where it comes from
and how we get it
is something that touches
all our lives.
It's also, I think, one of the most
important questions for science.
We all need an energy supply
that's reliable,
but it also has to be safe.
Around the world,
many questions are now being asked
about nuclear power.
Some countries
are looking to abandon it,
but what lessons should we learn
from the events at Fukushima?
What I love most about Tokyo
is the night-time.
That's when the city
comes alive with such energy,
that's when it glows so brightly.
But it's not glowing
so brightly tonight.
Things just don't look
the way they normally do.
By night,
unnecessary lights are turned off.
By day, machines stand stationary.
And people resist turning on
their air conditioning.
A country for whom using energy
has become as natural
as breathing air,
suddenly, very uncomfortably,
must hold its breath.
And that's because since
the earthquake and tsunami struck
over 100 miles away,
electricity use
has been rationed here.
Here in Japan, the mood
has turned against nuclear power.
You can understand why.
But is it the right reaction?
I'm a professor of nuclear physics,
but I have no agenda,
no axe to grind.
I'm not in the pay
of the nuclear industry,
nor the environmental movement.
Let me lay my cards on the table.
I've always believed that
nuclear power is a good thing.
It provides vast amounts
of cheap and reliable energy.
But I want to see how it's running,
out in the real world.
How reliable is it?
How safe is it?
I want to leave the politics
and economics to one side
and focus only on the science.
After all, I am a scientist.
But I'm also a husband and a father,
and I want to know what's the safest
option for my family's future,
just like you.
I want to start by going to
the heart of the place
that has shattered
many people's confidence -
Fukushima.
Soon after the Tsunami struck,
news spread that the nuclear
power station had been damaged.
There was a partial meltdown in one,
and possibly three of the reactors.
The situation appeared
to be running out of control.
Very rapidly, the perception
of nuclear power began to change
and governments reacted.
The German's have said
they'll shut down
their nuclear reactors by 2022.
The Swiss announced
that none of their existing nuclear
plants would be replaced.
A referendum in Italy
rejected plans to return
to nuclear power generation.
And an explosion at
a nuclear reprocessing plant
in France two days ago
will only have stoked
these fears further.
For the past few years,
there'd been talk of
a Nuclear Renaissance.
Not any more.
I've come here
to separate fact from emotion,
to see the reality for myself.
I want answers
to a couple of questions.
Firstly, just how bad was it,
what was the human impact?
And secondly,
how lasting is the damage
really likely to be?
But first,
I'm heading to the exclusion zone,
which is as close as I can get
to the plant.
'Hours after the first explosion
at the power station,
'this evacuation zone was set up.'
Well, ahead of me
are some guards blocking the road.
They look like they mean business.
'Eventually, anyone living
within a 20km radius of the plant
'was evacuated from their homes.
'Nearly 80,000 people.'
Well, the clean-up operation
carries on at the plant
and these are returning workers...
..who are just coming out
of the exclusion zone.
And this is, essentially,
the boundary, this is the border.
Beyond it, 20km in that way,
is the Fukushima nuclear plant.
But what is striking
is that for 20km in that direction
and a further 20km down the coast,
beyond the plant,
is complete emptiness.
Apart from the nuclear workers,
no-one is allowed in,
no-one lives there any more.
That's a lot of empty space
for a country as crowded as Japan.
'But what happened to cause this?'
We can't get inside
the Fukushima Daiichi plant,
but in May this year,
an international group of
scientists
went inside
to investigate what went wrong.
There's now
a well-established story
of what happened at the Fukushima
Daiichi nuclear plant on March 11th.
First, the earthquake hit,
followed by the tsunami,
wiping out the vital power supply
needed to cool the reactors
once they shut down.
And they did shut down.
This is the moment the tsunami
struck the power station.
As the 14-metre wave hit,
it overwhelmed the sea wall,
and swamped the diesel pumps.
The resulting loss of power
shut off cooling to the reactors.
This was crucial,
because even though
the reactors were shut down,
they were still generating heat.
Heat remained within the reactors
and they slowly started to cook.
This led ultimately to the build-up
of pressure and explosions.
Not nuclear explosions,
but gas explosions.
Accompanied by them was
the release of radioactive particles
out into the atmosphere.
There was a release of steam
and radioactive material,
including isotopes
of caesium and iodine.
But there was perhaps
a less well-known part of the design
which contributed to the explosions.
To understand why,
it's helpful to understand
how a nuclear reactor works.
The science behind nuclear power
is actually quite simple.
At the heart of a nuclear plant
are pellets like these,
called fuel pellets.
They contain radioactive uranium.
Now, the way the energy is released
is when the nucleus
of a uranium atom
is hit by a neutron.
Now, this splits the uranium
nucleus in two, releasing energy.
But it also releases
two or three other neutrons,
and these fly off
and hit further uranium nuclei,
forcing them to split as well.
This process is called
a controlled chain reaction.
This all takes place
inside zirconium cylinders like this
These contain the fuel pellets.
As the chain reaction goes on
inside, releasing energy,
these fuel rods heat up.
Essentially, they act just like
the elements of a kettle.
Just like in a kettle,
they're surrounded by water,
which they heat up, turn to steam,
which is used to drive turbines
that generate electricity.
Now, it's the same
in a nuclear power plant,
just as it is in any other
type of power plant.
They're all essentially
giant kettles.
At Fukushima, when cooling was lost,
the zirconium fuel rods
began to overheat.
They reacted with steam around them
and produced hydrogen.
This was vented out
into the reactor building
where it mixed it with oxygen...
and exploded.
Now, the reason part of the design
of this particular variety of
boiling-water reactor at Fukushima
might have contributed
to the sequence of events,
is because it made it harder
to deal with the steam
building up in the reactor.
Let me explain.
In a boiling-water reactor,
the reactor is connected
to a condensation chamber
which acts as relief
for some of the steam.
Now, in an old reactor
like Fukushima's,
this condensation chamber
was probably too small.
Had it been larger in size,
it would have been able
to cope with more of the steam,
giving the safety workers crucial
time to deal with the problem.
This was an old nuclear plant,
commissioned around 40 years ago,
but even though there was
a partial meltdown here,
much of the radiation
was kept inside the plant.
The thing about the accident
that happened here
is that we can find reasons for it -
the well-told story
that the sea wall wasn't built high
enough to withstand the tsunami.
But the thing about the failure
of this nuclear plant
is that it was an old nuclear plant,
old in design, old in technology.
And where you look elsewhere
at nuclear power stations
of a similar age,
they've mostly been either
retired off or upgraded.
Understandably,
many countries around the world
are now examining
the safety of their reactors,
but I believe we should be careful
not to make a blanket judgment
about all nuclear power
on the basis of what happened here.
But the people here still need
to deal with the consequences.
This gym in Minamisoma
is today serving as a meeting point
for some of the people
forced from their homes.
Today is the first time
they've been into the exclusion zone
since it was created.
A route is planned
to take them home.
They must wear dose meters
and there's a strict time limit
of two hours.
How do you feel about today?
Are you excited? Are you nervous?
TRANSLATION FROM JAPANESE:
We aren't allowed into the zone,
so former resident
Kunitomo Tokuzawa
is taking a camera for us
to chart his trip back home
with his mother.
Two hours later,
everyone returns with their
carefully selected belongings.
They're allowed to bring out
just one bagful,
measuring 70cm by 70cm.
TRANSLATION FROM JAPANESE:
'Kunitomo returns with the camera
'and a glimpse
into an abandoned world.'
Good to see. OK, well,
come and tell me all about it.
No-one knows when these people
will be allowed to return
to their homes, if ever.
Many have been forced to move
to a new city in search of work.
And for a disturbing number,
their lives are still in limbo.
Nearby is Haramachi
Junior High School.
But for now, it's also serving
as an emergency evacuation centre
for those who were living
close to the nuclear plant.
Konichiwa.
I met Shizuo Konno, an evacuee
whose home is now a classroom floor.
Your home is just a few miles away.
How frustrating
must this be for you?
TRANSLATION FROM JAPANESE:
Are you angry
with the way the situation
has been dealt with,
making you leave your home?
Arigato.
Shizuo is facing up to the fact that
he may never work on his farm again.
I caught up with the director of
the evacuation centre, Iwao Hoshi.
So how many people
are actually living now
in this evacuation centre?
TRANSLATION FROM JAPANESE:
And thousands of people
still remain in temporary
and makeshift accommodation.
You know, some of the stories I've
heard today have been heartbreaking
and it's quite tragic to think
that there are tens of thousands
of other stories
just like the ones I heard.
But let's get things
into perspective.
The earthquake and tsunami
killed over 20,000 people.
No-one has died as a result of
the fall-out from the nuclear plant.
The International Atomic Energy
Agency have said that, to date,
no confirmed long-term
health effects to any person
have been reported
as a result of radiation exposure.
Around 30 workers were exposed
to high doses initially,
and for these people, there may be
a small percentage increase
in their risk of eventually
incurring some health effects.
I'm in Japan, four months after
the tsunami struck the plant.
What remains of the radiation now?
And does it justify
the exclusion zone?
This is the village of Iitate,
population usually 6,165.
But it's been completely evacuated,
even though it's outside
the exclusion zone.
That's because radioactive particles
from the Fukushima reactor
have been carried here
by the weather.
Now it's entirely abandoned.
Every house, every street...
even this school.
I've come here today to witness
something I've never seen before.
In fact, it's an event
that's only happened
a few times during my lifetime,
and that's part of
a radioactive clean-up operation.
And so, as a precautionary measure,
I'm wearing these wellington boots,
just to make sure that
I don't get any contamination
from any dust on the ground
as I walk around.
Today, scientists
from Fukushima University
will take measurements of the soil,
which is where most, or all, of the
radioactive particles will be now,
because they've fallen
from the air to the ground.
They're looking
for two toxic elements
which escaped from Fukushima.
In particular, radioactive iodine
and radioactive caesium.
But one of these elements,
radioactive iodine,
is only present for a short time.
TRANSLATION FROM JAPANESE: Right now,
because about four months has passed,
I predict the iodine
has disappeared.
And that's because
radioactive elements decay over time
eventually changing into stable,
non-radioactive forms.
It's the half-life of an element
that's a good measure
of how quickly this happens.
TRANSLATION: So, only traces
of caesium 137 and 134
are being detected.
So, there will only be
caesium in the soil.
How dangerous is this? How long
will it remain in the ground?
TRANSLATION: The half-life of caesium
is said to be close to 30 years.
So, for a long time,
caesium will be the biggest problem.
Back in the lab, they've found
high levels of radiation
in the top 2.5 centimetres
of the soil.
Other studies from nearby
found levels more than
500 times higher than normal.
Removing this topsoil here
would be an expensive option
and Iitate isn't even
in the exclusion zone.
Recently, the Japanese Government
has been monitoring
the radiation level
across 50 sites inside the zone.
They've set their safety limit
at 20 millisieverts per year,
which is the same limit
as for people working
in the nuclear industry in the UK.
What they've found is that
35 of the sites exceeded this level
and the highest reading
was 500 millisieverts.
The tests will help decide
whether these people can go home.
The government has decided
to keep the exclusion zone in place,
but that's a more complex decision
than it looks.
For perspective,
you'd get around that level,
20 millisieverts a year,
from two CT scans per year.
On one hand, setting such a limit
protects people's health
effectively,
but on the other,
that comes at a cost -
the upheaval of 78,000 lives.
So let's take stock.
Certainly, governments
around the world
are looking to Japan
to help them make a decision.
Of course, they're going to be
influenced by the fact
that tens of thousands of people
had to be evacuated,
and that the exclusion zone
carries with it an economic cost,
as well as the human one.
But it's also true
that the containment process
around the reactor largely worked.
Most of the radiation was kept in,
which is pretty remarkable
for such an old and flawed reactor.
And, most importantly, no-one died.
And there have been no associated
radiation health risks so far.
One of the questions
that Fukushima raises is this -
how do we judge what level
of radiation can be considered safe?
This question has been relevant
to one place in particular -
the site of the biggest
nuclear accident in history.
Pripyat.
A ruined and deserted city
in the former Soviet Union.
On 26th April 1986,
three kilometres away
at the Chernobyl power plant,
a reactor exploded...
releasing three tonnes
of nuclear fuel.
28 of the workers
who were first on the scene
received extremely high doses
of radiation
and died within four months.
But there's another question
I'm interested in.
What was the effect of the radiation
released on another group -
not those working at the site
or helping with the clean-up,
but the general population
living here?
Galina Chayka was among those
living in Pripyat
at the time
of the Chernobyl accident.
Today she's returning to her
home for the first time in 25 years.
TRANSLATION: Here is our entrance.
And here is the door.
Now everything is broken,
nothing is left.
Oh, my flat, meet me 25 years after!
When the accident happened,
Galina and her children
were there to witness it.
TRANSLATION: We went out
and watched it,
how the reactor was burning
like Bengal fires,
and kids climbed the roofs
and watched it,
until somebody said it was dangerous
and made us stay inside.
They weren't evacuated
for another two days.
Galina believes that the accident's
impact began soon after.
TRANSLATION: Soon after the accident
I started to have headaches,
terrible headaches.
I got high blood pressure,
heart problems,
my stomach started to hurt
because of all the nerves,
and maybe I've got some sort
of radiation.
It's a situation that constantly
occupies her mind.
TRANSLATION: Now I mostly
live in fear of poor health,
disease, illnesses, death.
You live in fear every day
that today you are alive,
and tomorrow you get ill.
This is the everyday fear.
Galina is not alone.
Many more people
share the same fears.
But it's difficult, scientifically,
to show a link between
any one person's illness
and their exposure to radiation.
But, 20 years after the accident,
a large-scale international project,
the Chernobyl Forum,
set out to understand the impact
of the release of this radiation.
I've come to meet
Professor Mykola Tronko,
who is in charge of the Institute of
Endocrinology here in the Ukraine.
Initially, many doctors
expected Chernobyl
to cause different types of cancer
in hundreds of thousands of people.
But what actually happened
was very different.
TRANSLATION: Starting from 1990,
we saw the increase of thyroid
cancer incidents among children.
It certainly caused a big discussion
in the scientific world.
'Despite this wave of cases
of thyroid cancer,
'there were no confirmed increases
in any other type of cancer
'in the general population.'
TRANSLATION: We can say
that problem number one,
as far as the medical effects of
the Chernobyl accident are concerned,
is the problem of pathologies
of the thyroid gland,
particularly thyroid cancer.
How many thousands of people
have been diagnosed
as having thyroid cancer,
as a result - as far as you can
understand - of the accident itself?
TRANSLATION: For all cases
of thyroid cancer,
the institute has a register
of patients who were operated on
for thyroid cancer.
In this register, 2,000 - 2,500 refer
to radio-induced thyroid cancer.
The thyroids were removed,
studied and stored here.
They found that radioactive
iodine from the fallout
had been taken up
into the thyroid gland,
and there it had caused tumours.
It affected children more
because the rate of cell division
is faster in the thyroid
when you're young.
This might have been prevented.
Iodine tablets contain
the stable form of iodine
which your body takes up in
preference to the radioactive form,
so cancers don't start.
But, unlike Fukushima,
in Chernobyl, these tablets weren't
immediately made available.
How many deaths
has this resulted in so far?
TRANSLATION: There were
a few cases of deaths.
The number of deaths for
these patients, to be more exact,
aged 0-18 at the time
of the accident, was seven.
That's an incredible survival rate
for this type of thyroid cancer.
Yes, a high survival rate.
After five years,
we had a survival rate of 99.5%.
Once the findings of scientists
from across other contaminated areas
of Belarus and Russia were added in,
they found a total of 15 deaths
amongst 6,000 cases
of thyroid cancer,
Within a population of
some six million.
People will listen to you,
and they will say,
"Yes, of course,
he is in the Ukraine."
"He has the old Soviet mentality
of sticking to a particular line."
"Why should we believe him?"
TRANSLATION: It has
already been recognised
by the world's scientific
medical community.
WHO recognised it,
the United Nations recognised it.
These results have been published
in the most respected
scientific journals,
in particular, in Nature,
in Science, and many, many others.
At a human level, these deaths are,
of course, significant,
as are the cases of cancer.
But they are lower than
almost anyone expected.
I think a lot of people
will be really surprised
to hear what Professor Tronko
had to say.
I am pretty convinced by this work
on thyroid cancer.
The numbers are very low.
But the statistics seem solid.
The research is highly respected
and acknowledged around the world.
Of course, it remains to be seen
whether this number will grow.
But it's certainly not this figure
that's bandied around -
tens or hundreds of thousands
of cases -
that seems to be purely a myth.
The full outcome of Chernobyl
is not yet known.
But the data so far
is feeding into an ongoing debate
about the effects of
low-level radiation.
The thing is,
radioactivity is all around us.
It's in the air that we breathe,
it comes out from the ground.
It's inside our bodies.
The food that we eat is radioactive.
All living tissue, for instance,
contains radioactive carbon 14.
This banana cake contains potassium
40. As do these brazil nuts.
So, every time
I have food like this,
I'm increasing the amount
of radioactivity within my body.
There's a constant
background radiation
that does us no harm at all.
It's when the level of radiation
increases above that background
that the controversy arises.
The scientific consensus
has been that
any dose of radiation above
the background can cause damage.
And so, the picture
would look like this.
Harm, against dose,
gives a straight line.
But even low-dose levels
could be harmful.
This remains the consensus.
But there are a number
of scientists who believe
there may be a different theory.
It goes like this.
Low doses may not be harmful at all.
There's a certain threshold level
above which the harm begins to rise.
It's a quite different way of
thinking about radioactivity,
and its harmful effects.
This isn't just different,
it's highly controversial.
There's an ongoing debate
over the shape of the curve,
because it's difficult to collect
evidence at such low levels.
And it's possible that there's
a small section of the population
that may be more sensitive than
others to low-dose radiation.
While the scientific debate
continues,
the people of Pripyat must
continue to live their lives.
They've spent more than 25 years
trying to understand the impact
of radiation on their bodies.
TRANSLATION: What will it do to me?
I will die.
What else can it do to me?
Illnesses, suffering and death.
What other result?
The studies suggest that it's
unlikely that most of these people
will die, or get ill,
from the radioactive fall-out.
But instead, they live
in constant fear
of what the radiation
might have done to them.
Fear and horror. Horror and fear.
Or sadness and grief.
SHE SOBS
It's a large-scale problem, as
Dr Marino Gresko knows first-hand.
She specialises in counselling
Chernobyl evacuees.
But she's also one herself.
At the time of the accident,
she was a nine-year-old,
attending school here.
TRANSLATION: As a rule, the most
widespread are still
depressive moods, anxiety symptoms,
worry for the future,
including worry for their own health
and their children and grandchildren.
Suicidal moods and thoughts
are generally present among people
and some have
problems of alcohol abuse.
Doctor Gresko sees these
problems herself,
in large proportions of evacuees.
TRANSLATION: Out of all people who
were evacuated, about 70% suffer
from anxiety and depression.
And about 40% possibly have
alcoholism problems.
Dr Gresko's statistics refer
only to her own patients.
But there's much wider
support for this view.
The UN-backed Chernobyl Forum report
has stated that
the mental-health impact
of Chernobyl is the largest
public health problem
unleashed by the accident to date.
So what does this mean for
the people of Fukushima
who have had their lives
turned upside down by the tsunami
and then the nuclear evacuation?
It seems the greatest threat
to their health now may be
fear of radiation,
and the stress of evacuation.
But of course, the events in Japan
have a much wider importance.
We all face choices over the coming
years about how we get our energy.
It's a question that's made all
the more urgent by the issue
of climate change.
If we carry on burning
fossil fuels - coal, oil
and gas - at the rate we're doing,
then we risk changing our planet's
climate, the effects of which
could be devastating.
And, to my mind, this can never be
purely a scientific problem.
It's indisputably tied up
with economics and politics.
You'll have your views,
and I'll have mine.
But it's a debate that needs
to be informed by an assessment
of the scientific risks.
The influence of politics
and economics on nuclear power is,
of course, nothing new.
And really from the moment
scientists first started
to understand
the power bound up inside the atom,
it was inevitable that
politicians would be drawn to this
irresistible bounty of energy.
And I think these politics have had
an impact on my science.
The science of nuclear physics
and its attempts to find
the safest way to unleash
the power of the atom.
The creation of the atomic bomb
was one of the most monumental
scientific projects
of the 20th century.
It brought terrible destruction.
But it also demonstrated
the power of nuclear physics
and shortened America's
war in the Pacific.
After the Second World War,
physicists were lionised as heroes,
and there was this tremendous faith
in science to provide solutions and
answers to all the world's problems.
And as for nuclear technology, well,
the belief was that it had brought
an end to the war, and now, it will
provide us with electrical power.
The atomic age was born. A giant of
limitless power at man's command.
But in the new atomic age,
there were deep connections
between the civilian programme
for nuclear power, and earlier
military projects to build the bomb.
This is Bentwaters Park
on the Suffolk coast.
It used to be a US Air Force base
and was at the forefront
of the Cold War.
This bunker, and every one of these,
was a store for one thing -
nuclear weapons.
Each one of them was packed
full of warheads,
bombs that could have been used
against Soviet Russia
in the event of a war.
Plutonium in warheads could come
from both military reactors
and the earlier civilian reactors.
And more generally, the bomb
programme and the civilian
power programme that followed
shared the same reactor physics,
based on uranium.
But it didn't have to be that way.
And at the time there were some who
thought it shouldn't be that way.
Scientists continued to experiment
with other ways of producing
nuclear power -
not just from uranium -
and the story of what happened
with one of these alternative fuels
is a fascinating one.
It's one of the most overlooked
elements in the periodic table.
Thorium.
Some scientists have made
great claims for its potential -
it's more efficient,
it burns more completely,
and it's more abundant
than uranium -
but others see it as a difficult
element to work with.
It's harder to trigger
and sustain a nuclear reaction.
Crucially though, thorium reactors
don't produce plutonium
in a form that can be
readily used in weapons.
One extraordinary man was keen
to drive through
thorium as an alternative
nuclear fuel.
His name was Alvin Weinberg.
Now, strangely, Weinberg was
one of the architects of
the very earliest uranium nuclear
power plants in the US,
but despite his involvement
with these reactors,
Weinberg was keen to find safer
alternatives.
He became convinced that thorium
reactors were the way to go.
As head of a Government
nuclear lab from 1955,
Weinberg pushed forward
his suggestion
for what he thought was
a potentially safer way
of producing nuclear power.
This was a moment when the politicians
were faced with a choice.
They could either continue
with the thorium reactors
and explore other safer options...
..or they could stick with
the uranium-based reactors
they knew and had invested in.
They chose uranium.
Weinberg's plans were sidelined
and, after 18 years as director
of a key government nuclear lab,
he was forced out.
I'm not saying that thorium was,
in some way, the lost saviour
of nuclear power.
But Weinberg's story
was representative of
something different -
the shutting down of
scientific options.
Now, things have changed.
The Cold War is long over.
And there's a renewed interest
in finding safer ways
to approach nuclear power.
People are exploring new ideas.
And some are returning to those
which were shelved in the 1970s.
And revisiting the work of
scientists such as Alvin Weinberg.
What Weinberg had planned was
a radically different kind
of nuclear reactor.
Not only did he propose using
thorium instead of uranium as a
fuel, but to use it in liquid form.
It's quite incredible to think
that so many of Weinberg's
revolutionary ideas can be found in
this book that's over 50 years old.
And it's a real shame that when
the US government closed down
Weinberg's thorium research,
they also stopped all work
on liquid-fuel reactors.
It's perhaps too early to judge
whether thorium will realise
its potential and live up to
its promise as a nuclear fuel.
There are many technical and
scientific challenges to overcome.
But the reason it excites me,
as a nuclear physicist,
is because of the intellectual
ambition of the work.
There are already glimmers
of what might be achieved
if we do experiment.
I think one of the most
exciting prospects to
come out of recent research
is how to deal with nuclear waste.
Long-term waste remains radioactive
for tens of thousands of years.
So how to deal with it
is a very thorny issue.
At the moment,
the only accepted thing to do
is to bury it, deep underground,
in geologically sealed sites.
But there's an obvious problem
with this.
It simply sits there
as a legacy for future generations.
Here in Grenoble, in the southeast
of France, they're working on
how to transform long-term waste
into something which can be
disposed of more effectively.
Doctor Ulli Koester is in charge
of researching this process here.
It's called transmutation.
We can turn one element
into another.
So we can destroy long-lived
radioactive waste by turning it,
with this transmutation,
into short-lived isotopes
which go away quickly.
Ultimately, what happens
in any nuclear reactor
is that by splitting atomic nuclei
an element is transformed
into other different elements.
And what they do here is
rather similar, just accelerated.
They take heavy elements that are
radioactive for tens of thousands
of years and split them
into lighter ones
that are radioactive for
just tens or hundreds of years.
Transmutation is an alchemist's
dream, where people try to convert
lead into gold -
which is actually possible
with a strong accelerator - but
the gold price has to go a long way
before it becomes interesting
economically.
To perform this work they need
a specialised nuclear reactor.
They then take a small piece
of radioactive material -
in this case, americium 241 -
and load it remotely
into the reactor's core.
Once deep inside, it's bombarded
with a high flux of neutrons,
triggering fission
of as many nuclei in the waste
as possible, so burning it up
more completely.
So here we have a 50-times higher
neutron flux compared to
a power reactor, which means
we can accelerate the process
by a factor of 50.
Instead of waiting for 50
years for something to happen,
we can shorten it down to one year.
And this blue light in
the shielding water is a sign
that transmutation is happening.
It's called Cherenkov radiation
and it's created by the products
released as one element
is changed to another.
After 50 days or so in the reactor,
the americium, which had a half-life
of 430 years, has been transformed
into completely different elements.
Each peak represents a fingerprint
for an individual isotope.
If you find this peak we can look
it up and we will find it is a decay
of Krypton 87,
which has a much shorter half-life
of a couple of hours,
so it will decay away very quickly.
It's a process that can be applied
to other, more toxic waste products,
which can be radioactive
for thousands of years.
It's not yet a working solution
for our nuclear-waste problems.
But it shows what might be possible
if scientists are able to
pursue wider options.
So, there is an important question
that many of us are wrestling with -
should Fukushima really be the end
of the road for nuclear power?
And, I think, my answer would be no.
Nothing is perfect.
There are, of course,
consequences when things go wrong,
when there's an accident. But then,
of course, this is true of all
power - coal, oil, gas, renewables.
What's special about nuclear power
is our dread of radiation.
But my hope is that,
whatever we decide,
it will be based on a careful
assessment of rational science.
This is as close as you can get
to the site of a partial
nuclear meltdown six months ago.
But the events still unfolding here
have consequences for us all.
Energy is the lifeblood
of our civilization.
But where it comes from
and how we get it
is something that touches
all our lives.
It's also, I think, one of the most
important questions for science.
We all need an energy supply
that's reliable,
but it also has to be safe.
Around the world,
many questions are now being asked
about nuclear power.
Some countries
are looking to abandon it,
but what lessons should we learn
from the events at Fukushima?
What I love most about Tokyo
is the night-time.
That's when the city
comes alive with such energy,
that's when it glows so brightly.
But it's not glowing
so brightly tonight.
Things just don't look
the way they normally do.
By night,
unnecessary lights are turned off.
By day, machines stand stationary.
And people resist turning on
their air conditioning.
A country for whom using energy
has become as natural
as breathing air,
suddenly, very uncomfortably,
must hold its breath.
And that's because since
the earthquake and tsunami struck
over 100 miles away,
electricity use
has been rationed here.
Here in Japan, the mood
has turned against nuclear power.
You can understand why.
But is it the right reaction?
I'm a professor of nuclear physics,
but I have no agenda,
no axe to grind.
I'm not in the pay
of the nuclear industry,
nor the environmental movement.
Let me lay my cards on the table.
I've always believed that
nuclear power is a good thing.
It provides vast amounts
of cheap and reliable energy.
But I want to see how it's running,
out in the real world.
How reliable is it?
How safe is it?
I want to leave the politics
and economics to one side
and focus only on the science.
After all, I am a scientist.
But I'm also a husband and a father,
and I want to know what's the safest
option for my family's future,
just like you.
I want to start by going to
the heart of the place
that has shattered
many people's confidence -
Fukushima.
Soon after the Tsunami struck,
news spread that the nuclear
power station had been damaged.
There was a partial meltdown in one,
and possibly three of the reactors.
The situation appeared
to be running out of control.
Very rapidly, the perception
of nuclear power began to change
and governments reacted.
The German's have said
they'll shut down
their nuclear reactors by 2022.
The Swiss announced
that none of their existing nuclear
plants would be replaced.
A referendum in Italy
rejected plans to return
to nuclear power generation.
And an explosion at
a nuclear reprocessing plant
in France two days ago
will only have stoked
these fears further.
For the past few years,
there'd been talk of
a Nuclear Renaissance.
Not any more.
I've come here
to separate fact from emotion,
to see the reality for myself.
I want answers
to a couple of questions.
Firstly, just how bad was it,
what was the human impact?
And secondly,
how lasting is the damage
really likely to be?
But first,
I'm heading to the exclusion zone,
which is as close as I can get
to the plant.
'Hours after the first explosion
at the power station,
'this evacuation zone was set up.'
Well, ahead of me
are some guards blocking the road.
They look like they mean business.
'Eventually, anyone living
within a 20km radius of the plant
'was evacuated from their homes.
'Nearly 80,000 people.'
Well, the clean-up operation
carries on at the plant
and these are returning workers...
..who are just coming out
of the exclusion zone.
And this is, essentially,
the boundary, this is the border.
Beyond it, 20km in that way,
is the Fukushima nuclear plant.
But what is striking
is that for 20km in that direction
and a further 20km down the coast,
beyond the plant,
is complete emptiness.
Apart from the nuclear workers,
no-one is allowed in,
no-one lives there any more.
That's a lot of empty space
for a country as crowded as Japan.
'But what happened to cause this?'
We can't get inside
the Fukushima Daiichi plant,
but in May this year,
an international group of
scientists
went inside
to investigate what went wrong.
There's now
a well-established story
of what happened at the Fukushima
Daiichi nuclear plant on March 11th.
First, the earthquake hit,
followed by the tsunami,
wiping out the vital power supply
needed to cool the reactors
once they shut down.
And they did shut down.
This is the moment the tsunami
struck the power station.
As the 14-metre wave hit,
it overwhelmed the sea wall,
and swamped the diesel pumps.
The resulting loss of power
shut off cooling to the reactors.
This was crucial,
because even though
the reactors were shut down,
they were still generating heat.
Heat remained within the reactors
and they slowly started to cook.
This led ultimately to the build-up
of pressure and explosions.
Not nuclear explosions,
but gas explosions.
Accompanied by them was
the release of radioactive particles
out into the atmosphere.
There was a release of steam
and radioactive material,
including isotopes
of caesium and iodine.
But there was perhaps
a less well-known part of the design
which contributed to the explosions.
To understand why,
it's helpful to understand
how a nuclear reactor works.
The science behind nuclear power
is actually quite simple.
At the heart of a nuclear plant
are pellets like these,
called fuel pellets.
They contain radioactive uranium.
Now, the way the energy is released
is when the nucleus
of a uranium atom
is hit by a neutron.
Now, this splits the uranium
nucleus in two, releasing energy.
But it also releases
two or three other neutrons,
and these fly off
and hit further uranium nuclei,
forcing them to split as well.
This process is called
a controlled chain reaction.
This all takes place
inside zirconium cylinders like this
These contain the fuel pellets.
As the chain reaction goes on
inside, releasing energy,
these fuel rods heat up.
Essentially, they act just like
the elements of a kettle.
Just like in a kettle,
they're surrounded by water,
which they heat up, turn to steam,
which is used to drive turbines
that generate electricity.
Now, it's the same
in a nuclear power plant,
just as it is in any other
type of power plant.
They're all essentially
giant kettles.
At Fukushima, when cooling was lost,
the zirconium fuel rods
began to overheat.
They reacted with steam around them
and produced hydrogen.
This was vented out
into the reactor building
where it mixed it with oxygen...
and exploded.
Now, the reason part of the design
of this particular variety of
boiling-water reactor at Fukushima
might have contributed
to the sequence of events,
is because it made it harder
to deal with the steam
building up in the reactor.
Let me explain.
In a boiling-water reactor,
the reactor is connected
to a condensation chamber
which acts as relief
for some of the steam.
Now, in an old reactor
like Fukushima's,
this condensation chamber
was probably too small.
Had it been larger in size,
it would have been able
to cope with more of the steam,
giving the safety workers crucial
time to deal with the problem.
This was an old nuclear plant,
commissioned around 40 years ago,
but even though there was
a partial meltdown here,
much of the radiation
was kept inside the plant.
The thing about the accident
that happened here
is that we can find reasons for it -
the well-told story
that the sea wall wasn't built high
enough to withstand the tsunami.
But the thing about the failure
of this nuclear plant
is that it was an old nuclear plant,
old in design, old in technology.
And where you look elsewhere
at nuclear power stations
of a similar age,
they've mostly been either
retired off or upgraded.
Understandably,
many countries around the world
are now examining
the safety of their reactors,
but I believe we should be careful
not to make a blanket judgment
about all nuclear power
on the basis of what happened here.
But the people here still need
to deal with the consequences.
This gym in Minamisoma
is today serving as a meeting point
for some of the people
forced from their homes.
Today is the first time
they've been into the exclusion zone
since it was created.
A route is planned
to take them home.
They must wear dose meters
and there's a strict time limit
of two hours.
How do you feel about today?
Are you excited? Are you nervous?
TRANSLATION FROM JAPANESE:
We aren't allowed into the zone,
so former resident
Kunitomo Tokuzawa
is taking a camera for us
to chart his trip back home
with his mother.
Two hours later,
everyone returns with their
carefully selected belongings.
They're allowed to bring out
just one bagful,
measuring 70cm by 70cm.
TRANSLATION FROM JAPANESE:
'Kunitomo returns with the camera
'and a glimpse
into an abandoned world.'
Good to see. OK, well,
come and tell me all about it.
No-one knows when these people
will be allowed to return
to their homes, if ever.
Many have been forced to move
to a new city in search of work.
And for a disturbing number,
their lives are still in limbo.
Nearby is Haramachi
Junior High School.
But for now, it's also serving
as an emergency evacuation centre
for those who were living
close to the nuclear plant.
Konichiwa.
I met Shizuo Konno, an evacuee
whose home is now a classroom floor.
Your home is just a few miles away.
How frustrating
must this be for you?
TRANSLATION FROM JAPANESE:
Are you angry
with the way the situation
has been dealt with,
making you leave your home?
Arigato.
Shizuo is facing up to the fact that
he may never work on his farm again.
I caught up with the director of
the evacuation centre, Iwao Hoshi.
So how many people
are actually living now
in this evacuation centre?
TRANSLATION FROM JAPANESE:
And thousands of people
still remain in temporary
and makeshift accommodation.
You know, some of the stories I've
heard today have been heartbreaking
and it's quite tragic to think
that there are tens of thousands
of other stories
just like the ones I heard.
But let's get things
into perspective.
The earthquake and tsunami
killed over 20,000 people.
No-one has died as a result of
the fall-out from the nuclear plant.
The International Atomic Energy
Agency have said that, to date,
no confirmed long-term
health effects to any person
have been reported
as a result of radiation exposure.
Around 30 workers were exposed
to high doses initially,
and for these people, there may be
a small percentage increase
in their risk of eventually
incurring some health effects.
I'm in Japan, four months after
the tsunami struck the plant.
What remains of the radiation now?
And does it justify
the exclusion zone?
This is the village of Iitate,
population usually 6,165.
But it's been completely evacuated,
even though it's outside
the exclusion zone.
That's because radioactive particles
from the Fukushima reactor
have been carried here
by the weather.
Now it's entirely abandoned.
Every house, every street...
even this school.
I've come here today to witness
something I've never seen before.
In fact, it's an event
that's only happened
a few times during my lifetime,
and that's part of
a radioactive clean-up operation.
And so, as a precautionary measure,
I'm wearing these wellington boots,
just to make sure that
I don't get any contamination
from any dust on the ground
as I walk around.
Today, scientists
from Fukushima University
will take measurements of the soil,
which is where most, or all, of the
radioactive particles will be now,
because they've fallen
from the air to the ground.
They're looking
for two toxic elements
which escaped from Fukushima.
In particular, radioactive iodine
and radioactive caesium.
But one of these elements,
radioactive iodine,
is only present for a short time.
TRANSLATION FROM JAPANESE: Right now,
because about four months has passed,
I predict the iodine
has disappeared.
And that's because
radioactive elements decay over time
eventually changing into stable,
non-radioactive forms.
It's the half-life of an element
that's a good measure
of how quickly this happens.
TRANSLATION: So, only traces
of caesium 137 and 134
are being detected.
So, there will only be
caesium in the soil.
How dangerous is this? How long
will it remain in the ground?
TRANSLATION: The half-life of caesium
is said to be close to 30 years.
So, for a long time,
caesium will be the biggest problem.
Back in the lab, they've found
high levels of radiation
in the top 2.5 centimetres
of the soil.
Other studies from nearby
found levels more than
500 times higher than normal.
Removing this topsoil here
would be an expensive option
and Iitate isn't even
in the exclusion zone.
Recently, the Japanese Government
has been monitoring
the radiation level
across 50 sites inside the zone.
They've set their safety limit
at 20 millisieverts per year,
which is the same limit
as for people working
in the nuclear industry in the UK.
What they've found is that
35 of the sites exceeded this level
and the highest reading
was 500 millisieverts.
The tests will help decide
whether these people can go home.
The government has decided
to keep the exclusion zone in place,
but that's a more complex decision
than it looks.
For perspective,
you'd get around that level,
20 millisieverts a year,
from two CT scans per year.
On one hand, setting such a limit
protects people's health
effectively,
but on the other,
that comes at a cost -
the upheaval of 78,000 lives.
So let's take stock.
Certainly, governments
around the world
are looking to Japan
to help them make a decision.
Of course, they're going to be
influenced by the fact
that tens of thousands of people
had to be evacuated,
and that the exclusion zone
carries with it an economic cost,
as well as the human one.
But it's also true
that the containment process
around the reactor largely worked.
Most of the radiation was kept in,
which is pretty remarkable
for such an old and flawed reactor.
And, most importantly, no-one died.
And there have been no associated
radiation health risks so far.
One of the questions
that Fukushima raises is this -
how do we judge what level
of radiation can be considered safe?
This question has been relevant
to one place in particular -
the site of the biggest
nuclear accident in history.
Pripyat.
A ruined and deserted city
in the former Soviet Union.
On 26th April 1986,
three kilometres away
at the Chernobyl power plant,
a reactor exploded...
releasing three tonnes
of nuclear fuel.
28 of the workers
who were first on the scene
received extremely high doses
of radiation
and died within four months.
But there's another question
I'm interested in.
What was the effect of the radiation
released on another group -
not those working at the site
or helping with the clean-up,
but the general population
living here?
Galina Chayka was among those
living in Pripyat
at the time
of the Chernobyl accident.
Today she's returning to her
home for the first time in 25 years.
TRANSLATION: Here is our entrance.
And here is the door.
Now everything is broken,
nothing is left.
Oh, my flat, meet me 25 years after!
When the accident happened,
Galina and her children
were there to witness it.
TRANSLATION: We went out
and watched it,
how the reactor was burning
like Bengal fires,
and kids climbed the roofs
and watched it,
until somebody said it was dangerous
and made us stay inside.
They weren't evacuated
for another two days.
Galina believes that the accident's
impact began soon after.
TRANSLATION: Soon after the accident
I started to have headaches,
terrible headaches.
I got high blood pressure,
heart problems,
my stomach started to hurt
because of all the nerves,
and maybe I've got some sort
of radiation.
It's a situation that constantly
occupies her mind.
TRANSLATION: Now I mostly
live in fear of poor health,
disease, illnesses, death.
You live in fear every day
that today you are alive,
and tomorrow you get ill.
This is the everyday fear.
Galina is not alone.
Many more people
share the same fears.
But it's difficult, scientifically,
to show a link between
any one person's illness
and their exposure to radiation.
But, 20 years after the accident,
a large-scale international project,
the Chernobyl Forum,
set out to understand the impact
of the release of this radiation.
I've come to meet
Professor Mykola Tronko,
who is in charge of the Institute of
Endocrinology here in the Ukraine.
Initially, many doctors
expected Chernobyl
to cause different types of cancer
in hundreds of thousands of people.
But what actually happened
was very different.
TRANSLATION: Starting from 1990,
we saw the increase of thyroid
cancer incidents among children.
It certainly caused a big discussion
in the scientific world.
'Despite this wave of cases
of thyroid cancer,
'there were no confirmed increases
in any other type of cancer
'in the general population.'
TRANSLATION: We can say
that problem number one,
as far as the medical effects of
the Chernobyl accident are concerned,
is the problem of pathologies
of the thyroid gland,
particularly thyroid cancer.
How many thousands of people
have been diagnosed
as having thyroid cancer,
as a result - as far as you can
understand - of the accident itself?
TRANSLATION: For all cases
of thyroid cancer,
the institute has a register
of patients who were operated on
for thyroid cancer.
In this register, 2,000 - 2,500 refer
to radio-induced thyroid cancer.
The thyroids were removed,
studied and stored here.
They found that radioactive
iodine from the fallout
had been taken up
into the thyroid gland,
and there it had caused tumours.
It affected children more
because the rate of cell division
is faster in the thyroid
when you're young.
This might have been prevented.
Iodine tablets contain
the stable form of iodine
which your body takes up in
preference to the radioactive form,
so cancers don't start.
But, unlike Fukushima,
in Chernobyl, these tablets weren't
immediately made available.
How many deaths
has this resulted in so far?
TRANSLATION: There were
a few cases of deaths.
The number of deaths for
these patients, to be more exact,
aged 0-18 at the time
of the accident, was seven.
That's an incredible survival rate
for this type of thyroid cancer.
Yes, a high survival rate.
After five years,
we had a survival rate of 99.5%.
Once the findings of scientists
from across other contaminated areas
of Belarus and Russia were added in,
they found a total of 15 deaths
amongst 6,000 cases
of thyroid cancer,
Within a population of
some six million.
People will listen to you,
and they will say,
"Yes, of course,
he is in the Ukraine."
"He has the old Soviet mentality
of sticking to a particular line."
"Why should we believe him?"
TRANSLATION: It has
already been recognised
by the world's scientific
medical community.
WHO recognised it,
the United Nations recognised it.
These results have been published
in the most respected
scientific journals,
in particular, in Nature,
in Science, and many, many others.
At a human level, these deaths are,
of course, significant,
as are the cases of cancer.
But they are lower than
almost anyone expected.
I think a lot of people
will be really surprised
to hear what Professor Tronko
had to say.
I am pretty convinced by this work
on thyroid cancer.
The numbers are very low.
But the statistics seem solid.
The research is highly respected
and acknowledged around the world.
Of course, it remains to be seen
whether this number will grow.
But it's certainly not this figure
that's bandied around -
tens or hundreds of thousands
of cases -
that seems to be purely a myth.
The full outcome of Chernobyl
is not yet known.
But the data so far
is feeding into an ongoing debate
about the effects of
low-level radiation.
The thing is,
radioactivity is all around us.
It's in the air that we breathe,
it comes out from the ground.
It's inside our bodies.
The food that we eat is radioactive.
All living tissue, for instance,
contains radioactive carbon 14.
This banana cake contains potassium
40. As do these brazil nuts.
So, every time
I have food like this,
I'm increasing the amount
of radioactivity within my body.
There's a constant
background radiation
that does us no harm at all.
It's when the level of radiation
increases above that background
that the controversy arises.
The scientific consensus
has been that
any dose of radiation above
the background can cause damage.
And so, the picture
would look like this.
Harm, against dose,
gives a straight line.
But even low-dose levels
could be harmful.
This remains the consensus.
But there are a number
of scientists who believe
there may be a different theory.
It goes like this.
Low doses may not be harmful at all.
There's a certain threshold level
above which the harm begins to rise.
It's a quite different way of
thinking about radioactivity,
and its harmful effects.
This isn't just different,
it's highly controversial.
There's an ongoing debate
over the shape of the curve,
because it's difficult to collect
evidence at such low levels.
And it's possible that there's
a small section of the population
that may be more sensitive than
others to low-dose radiation.
While the scientific debate
continues,
the people of Pripyat must
continue to live their lives.
They've spent more than 25 years
trying to understand the impact
of radiation on their bodies.
TRANSLATION: What will it do to me?
I will die.
What else can it do to me?
Illnesses, suffering and death.
What other result?
The studies suggest that it's
unlikely that most of these people
will die, or get ill,
from the radioactive fall-out.
But instead, they live
in constant fear
of what the radiation
might have done to them.
Fear and horror. Horror and fear.
Or sadness and grief.
SHE SOBS
It's a large-scale problem, as
Dr Marino Gresko knows first-hand.
She specialises in counselling
Chernobyl evacuees.
But she's also one herself.
At the time of the accident,
she was a nine-year-old,
attending school here.
TRANSLATION: As a rule, the most
widespread are still
depressive moods, anxiety symptoms,
worry for the future,
including worry for their own health
and their children and grandchildren.
Suicidal moods and thoughts
are generally present among people
and some have
problems of alcohol abuse.
Doctor Gresko sees these
problems herself,
in large proportions of evacuees.
TRANSLATION: Out of all people who
were evacuated, about 70% suffer
from anxiety and depression.
And about 40% possibly have
alcoholism problems.
Dr Gresko's statistics refer
only to her own patients.
But there's much wider
support for this view.
The UN-backed Chernobyl Forum report
has stated that
the mental-health impact
of Chernobyl is the largest
public health problem
unleashed by the accident to date.
So what does this mean for
the people of Fukushima
who have had their lives
turned upside down by the tsunami
and then the nuclear evacuation?
It seems the greatest threat
to their health now may be
fear of radiation,
and the stress of evacuation.
But of course, the events in Japan
have a much wider importance.
We all face choices over the coming
years about how we get our energy.
It's a question that's made all
the more urgent by the issue
of climate change.
If we carry on burning
fossil fuels - coal, oil
and gas - at the rate we're doing,
then we risk changing our planet's
climate, the effects of which
could be devastating.
And, to my mind, this can never be
purely a scientific problem.
It's indisputably tied up
with economics and politics.
You'll have your views,
and I'll have mine.
But it's a debate that needs
to be informed by an assessment
of the scientific risks.
The influence of politics
and economics on nuclear power is,
of course, nothing new.
And really from the moment
scientists first started
to understand
the power bound up inside the atom,
it was inevitable that
politicians would be drawn to this
irresistible bounty of energy.
And I think these politics have had
an impact on my science.
The science of nuclear physics
and its attempts to find
the safest way to unleash
the power of the atom.
The creation of the atomic bomb
was one of the most monumental
scientific projects
of the 20th century.
It brought terrible destruction.
But it also demonstrated
the power of nuclear physics
and shortened America's
war in the Pacific.
After the Second World War,
physicists were lionised as heroes,
and there was this tremendous faith
in science to provide solutions and
answers to all the world's problems.
And as for nuclear technology, well,
the belief was that it had brought
an end to the war, and now, it will
provide us with electrical power.
The atomic age was born. A giant of
limitless power at man's command.
But in the new atomic age,
there were deep connections
between the civilian programme
for nuclear power, and earlier
military projects to build the bomb.
This is Bentwaters Park
on the Suffolk coast.
It used to be a US Air Force base
and was at the forefront
of the Cold War.
This bunker, and every one of these,
was a store for one thing -
nuclear weapons.
Each one of them was packed
full of warheads,
bombs that could have been used
against Soviet Russia
in the event of a war.
Plutonium in warheads could come
from both military reactors
and the earlier civilian reactors.
And more generally, the bomb
programme and the civilian
power programme that followed
shared the same reactor physics,
based on uranium.
But it didn't have to be that way.
And at the time there were some who
thought it shouldn't be that way.
Scientists continued to experiment
with other ways of producing
nuclear power -
not just from uranium -
and the story of what happened
with one of these alternative fuels
is a fascinating one.
It's one of the most overlooked
elements in the periodic table.
Thorium.
Some scientists have made
great claims for its potential -
it's more efficient,
it burns more completely,
and it's more abundant
than uranium -
but others see it as a difficult
element to work with.
It's harder to trigger
and sustain a nuclear reaction.
Crucially though, thorium reactors
don't produce plutonium
in a form that can be
readily used in weapons.
One extraordinary man was keen
to drive through
thorium as an alternative
nuclear fuel.
His name was Alvin Weinberg.
Now, strangely, Weinberg was
one of the architects of
the very earliest uranium nuclear
power plants in the US,
but despite his involvement
with these reactors,
Weinberg was keen to find safer
alternatives.
He became convinced that thorium
reactors were the way to go.
As head of a Government
nuclear lab from 1955,
Weinberg pushed forward
his suggestion
for what he thought was
a potentially safer way
of producing nuclear power.
This was a moment when the politicians
were faced with a choice.
They could either continue
with the thorium reactors
and explore other safer options...
..or they could stick with
the uranium-based reactors
they knew and had invested in.
They chose uranium.
Weinberg's plans were sidelined
and, after 18 years as director
of a key government nuclear lab,
he was forced out.
I'm not saying that thorium was,
in some way, the lost saviour
of nuclear power.
But Weinberg's story
was representative of
something different -
the shutting down of
scientific options.
Now, things have changed.
The Cold War is long over.
And there's a renewed interest
in finding safer ways
to approach nuclear power.
People are exploring new ideas.
And some are returning to those
which were shelved in the 1970s.
And revisiting the work of
scientists such as Alvin Weinberg.
What Weinberg had planned was
a radically different kind
of nuclear reactor.
Not only did he propose using
thorium instead of uranium as a
fuel, but to use it in liquid form.
It's quite incredible to think
that so many of Weinberg's
revolutionary ideas can be found in
this book that's over 50 years old.
And it's a real shame that when
the US government closed down
Weinberg's thorium research,
they also stopped all work
on liquid-fuel reactors.
It's perhaps too early to judge
whether thorium will realise
its potential and live up to
its promise as a nuclear fuel.
There are many technical and
scientific challenges to overcome.
But the reason it excites me,
as a nuclear physicist,
is because of the intellectual
ambition of the work.
There are already glimmers
of what might be achieved
if we do experiment.
I think one of the most
exciting prospects to
come out of recent research
is how to deal with nuclear waste.
Long-term waste remains radioactive
for tens of thousands of years.
So how to deal with it
is a very thorny issue.
At the moment,
the only accepted thing to do
is to bury it, deep underground,
in geologically sealed sites.
But there's an obvious problem
with this.
It simply sits there
as a legacy for future generations.
Here in Grenoble, in the southeast
of France, they're working on
how to transform long-term waste
into something which can be
disposed of more effectively.
Doctor Ulli Koester is in charge
of researching this process here.
It's called transmutation.
We can turn one element
into another.
So we can destroy long-lived
radioactive waste by turning it,
with this transmutation,
into short-lived isotopes
which go away quickly.
Ultimately, what happens
in any nuclear reactor
is that by splitting atomic nuclei
an element is transformed
into other different elements.
And what they do here is
rather similar, just accelerated.
They take heavy elements that are
radioactive for tens of thousands
of years and split them
into lighter ones
that are radioactive for
just tens or hundreds of years.
Transmutation is an alchemist's
dream, where people try to convert
lead into gold -
which is actually possible
with a strong accelerator - but
the gold price has to go a long way
before it becomes interesting
economically.
To perform this work they need
a specialised nuclear reactor.
They then take a small piece
of radioactive material -
in this case, americium 241 -
and load it remotely
into the reactor's core.
Once deep inside, it's bombarded
with a high flux of neutrons,
triggering fission
of as many nuclei in the waste
as possible, so burning it up
more completely.
So here we have a 50-times higher
neutron flux compared to
a power reactor, which means
we can accelerate the process
by a factor of 50.
Instead of waiting for 50
years for something to happen,
we can shorten it down to one year.
And this blue light in
the shielding water is a sign
that transmutation is happening.
It's called Cherenkov radiation
and it's created by the products
released as one element
is changed to another.
After 50 days or so in the reactor,
the americium, which had a half-life
of 430 years, has been transformed
into completely different elements.
Each peak represents a fingerprint
for an individual isotope.
If you find this peak we can look
it up and we will find it is a decay
of Krypton 87,
which has a much shorter half-life
of a couple of hours,
so it will decay away very quickly.
It's a process that can be applied
to other, more toxic waste products,
which can be radioactive
for thousands of years.
It's not yet a working solution
for our nuclear-waste problems.
But it shows what might be possible
if scientists are able to
pursue wider options.
So, there is an important question
that many of us are wrestling with -
should Fukushima really be the end
of the road for nuclear power?
And, I think, my answer would be no.
Nothing is perfect.
There are, of course,
consequences when things go wrong,
when there's an accident. But then,
of course, this is true of all
power - coal, oil, gas, renewables.
What's special about nuclear power
is our dread of radiation.
But my hope is that,
whatever we decide,
it will be based on a careful
assessment of rational science.