Topical science series. Six months after the explosions at the Fukushima nuclear plant in Japan, Professor Jim Al-Khalili sets out to discover whether nuclear power is safe.
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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
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 that 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 -
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?
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...
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.
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?
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.
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.
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,
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.
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 -
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.
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 politics 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, whatever we decide,
it will be based on a careful assessment of rational science.
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Six months after the explosions at the Fukushima nuclear plant and the release of radiation there, Professor Jim Al-Khalili sets out to discover whether nuclear power is safe.
He begins in Japan, where he meets some of the tens of thousands of people who have been evacuated from the exclusion zone. He travels to an abandoned village just outside the zone to witness a nuclear clean-up operation.
Jim draws on the latest scientific findings from Japan and from the previous explosion at Chernobyl to understand how dangerous the release of radiation is likely to be and what that means for our trust in nuclear power.