- 4 months ago
is dailymotion safe
Category
🎥
Short filmTranscript
00:00FUKUSHIMA, NORTH EAST JAPAN.
00:10This is as close as you can get to the site of a partial nuclear meltdown six months ago.
00:19But the events still unfolding here have consequences for us all.
00:27Energy is the lifeblood of our civilization.
00:34But where it comes from and how we get it is something that touches all our lives.
00:40It's also, I think, one of the most important questions for science.
00:49We all need an energy supply that's reliable.
00:53But it also has to be safe.
00:56Around the world, many questions are now being asked about nuclear power.
01:06Some countries are looking to abandon it.
01:11But what lessons should we learn from the events at Fukushima?
01:16What I love most about Tokyo is the night time.
01:28That's when the city comes alive with such energy.
01:44That's when it glows so brightly.
01:46But it's not glowing so brightly tonight.
01:49Things just don't look the way they normally do.
01:52By night, unnecessary lights are turned off.
02:07By day, machines stand stationary.
02:12And people resist turning on their air conditioning.
02:18A country for whom using energy has become as natural as breathing air, suddenly, very uncomfortably, must hold its breath.
02:36And that's because, since the earthquake and tsunami struck over 100 miles away, electricity use has been rationed here.
02:51Here in Japan, the mood has turned against nuclear power.
02:57You can understand why.
02:59But is it the right reaction?
03:03I'm a professor of nuclear physics, but I have no agenda, no axe to grind.
03:13I'm not in the pay of the nuclear industry, nor the environmental movement.
03:18Let me lay my cards on the table.
03:21I've always believed that nuclear power is a good thing.
03:25It provides vast amounts of cheap and reliable energy.
03:29But I want to see how it's running out in the real world.
03:32How reliable is it?
03:34How safe is it?
03:36I want to leave the politics and economics to one side and focus only on the science.
03:42After all, I am a scientist.
03:44But I'm also a husband and a father.
03:47And I want to know what's the safest option for my family's future, just like you.
04:04I want to start by going to the heart of the place that has shattered many people's confidence, Fukushima.
04:16Soon after the tsunami struck, news spread that the nuclear power station had been damaged.
04:29There was a partial meltdown in one and possibly three of the reactors.
04:34The situation appeared to be running out of control.
04:37Very rapidly, the perception of nuclear power began to change.
04:45And governments reacted.
04:48The Germans have said they'll shut down their nuclear reactors by 2022.
04:54The Swiss announced that none of their existing nuclear plants will be replaced.
05:04A referendum in Italy rejected plans to return to nuclear power generation.
05:11And an explosion at a nuclear reprocessing plant in France two days ago will only have stoked these fears further.
05:20For the past few years, there have been talk of a nuclear renaissance.
05:26Not anymore.
05:29I've come here to separate facts from emotion, to see the reality for myself.
05:40I want answers to a couple of questions.
05:43Firstly, just how bad was it?
05:46What was the human impact?
05:47And secondly, how lasting is the damage really likely to be?
05:52But first, I'm heading to the exclusion zone, which is as close as I can get to the plant.
06:12Hours after the first explosion at the power station, this evacuation zone was set up.
06:23Well, ahead of me are some guards blocking the road.
06:28They look like they mean business.
06:31Eventually, anyone living within a 20-kilometre radius of the plant was evacuated from their homes.
06:39Nearly 80,000 people.
06:45Well, the clean-up operation carries on at the plant, and these are returning workers who are just coming out of the exclusion zone.
06:56And this is essentially the boundary. This is the border.
07:00Beyond it, 20 kilometres in that way, is the Fukushima nuclear plant.
07:07But what is striking is that for 20 kilometres in that direction,
07:12and a further 20 kilometres down the coast, beyond the plant, is complete emptiness.
07:19Apart from the nuclear workers, no one is allowed in. No one lives there anymore.
07:24That's a lot of empty space for a country as crowded as Japan.
07:28But what happened to cause this?
07:33We can't get inside the Fukushima Daiichi plant.
07:48But in May this year, an international group of scientists went inside to investigate what went wrong.
07:57There's now a well-established story of what happened at the Fukushima Daiichi nuclear plant on March 11th.
08:11First, 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.
08:22This is the moment the tsunami struck the power station.
08:29As the 14-metre wave hit, it overwhelmed the sea wall and swamped the diesel pumps.
08:38The resulting loss of power shut off cooling to the reactors.
08:47This was crucial, because even though the reactors were shut down, they were still generating heat.
08:57Heat remained within the reactors, and they slowly started to cook.
09:03And this led ultimately to the build-up of pressure and explosions.
09:08Not nuclear explosions, but gas explosions.
09:11Accompanied by them was the release of radioactive particles out into the atmosphere.
09:16There was a release of steam and radioactive material, including isotopes of cesium and iodine.
09:31But there was perhaps a less well-known part of the design, which contributed to the explosions.
09:37To understand why, it's helpful to understand how a nuclear reactor works.
09:48The science behind nuclear power is actually quite simple.
09:52At the heart of a nuclear plant are pellets like these, called fuel pellets.
09:57They contain radioactive uranium.
10:00Now, the way the energy is released is when the nucleus of a uranium atom is hit by a neutron.
10:10Now, this splits the uranium nucleus in two, releasing energy.
10:15But it also releases two or three other neutrons.
10:19And these fly off and hit further uranium nuclei, forcing them to split as well.
10:26This process is called a controlled chain reaction.
10:30This all takes place inside zirconium cylinders like this.
10:35These contain the fuel pellets.
10:37As the chain reaction goes on inside, releasing energy, these fuel rods heat up.
10:43Essentially, they act just like the elements of a kettle.
10:47Just like in a kettle, they're surrounded by water, which they heat up, turned to steam,
10:53which is used to drive turbines that generate electricity.
10:57Now, it's the same in a nuclear power plant, just as it is in any other type of power plant.
11:02They're all essentially giant kettles.
11:10At Fukushima, when cooling was lost, the zirconium fuel rods began to overheat.
11:16They reacted with steam around them and produced hydrogen.
11:23This was vented out into the reactor building, where it mixed with oxygen and exploded.
11:31Now, the reason part of the design of this particular variety of boiling water reactor at Fukushima
11:44might have contributed to this sequence of events
11:47is because it made it harder to deal with the steam building up in the reactor.
11:53Let me explain.
11:55In a boiling water reactor, the reactor is connected to a condensation chamber,
12:02which acts as relief for some of the steam.
12:06Now, in an old reactor like Fukushima's, this condensation chamber was probably too small.
12:12Had it been larger in size, it would have been able to cope with more of the steam,
12:18giving the safety workers crucial time to deal with the problem.
12:28This was an old nuclear plant, commissioned around 40 years ago.
12:33But even though there was a partial meltdown here,
12:37much of the radiation was kept inside the plant.
12:41The thing about the accident that happened here is that we can find reasons for it.
12:51The well-told story that the sea wall wasn't built high enough to withstand the tsunami.
12:57But the thing about the failure of this nuclear plant is that it was an old nuclear plant.
13:03Old in design, old in technology.
13:06And where you look elsewhere at nuclear power stations of a similar age,
13:11they've mostly been either retired off or upgraded.
13:18Understandably, many countries around the world are now examining the safety of their reactors.
13:24But I believe we should be careful not to make a blanket judgement about all nuclear power
13:30on the basis of what happened here.
13:43But the people here still need to deal with the consequences.
13:51This gym in Minamisoma is today serving as a meeting point
13:55for some of the people forced from their homes.
14:01Today is the first time they've been into the exclusion zone since it was created.
14:20The route is planned to take them home.
14:22They must wear dose meters, and there's a strict time limit of two hours.
14:29How do you feel about today? Are you excited? Are you nervous?
14:34We aren't allowed into the zone, so former resident Kunetomo Tokazawa is taking a camera for us.
14:39To chart his trip back home with his mother.
14:40Two hours later, everyone returns with their carefully selected belongings.
14:41They're allowed to bring out just one bag of food.
14:42They're allowed to bring out just one bag of food.
14:43They're not allowed into the zone.
14:44We aren't allowed into the zone, so former resident Kunetomo Tokazawa is taking a camera for us
14:49to chart his trip back home with his mother.
14:59Two hours later, everyone returns with their carefully selected belongings.
15:04They're allowed to bring out just one bag full, measuring 70 cm by 70 cm.
15:13of thehov stop lock than the otherção.
15:19They say I shaky.
15:26Well, I reuse it from here.
15:29Yeah, they're able to change the agreements with my mind to the owner at the time as it feels
15:31like they need to have a trip.
15:33Kunitomo returns with the camera and a glimpse into an abandoned world.
15:40Good to see you. Okay, well, come and tell me all about it.
16:03I'm going to go to the next level.
16:10I'm going to go to the next level.
16:13I'm entering the area in the KK区.
16:20The road is in the road.
16:24There are no signs of a man's face.
16:31人の姿はありません。
16:38それでは家の中に入りたいと思います。
16:43家の中すごい暑い状態で
16:48冷蔵庫の中のものが完全に腐っている状態です。
16:54酷い悪臭です。
16:58飼っていた猫はもういなくなっていました。
17:04いつの水かもあんねん。
17:09何か月前だよ。
17:132階に登った時、自分の部屋が2階だったので、
17:17その瞬間がやっぱり一番懐かしかった。
17:28胸が苦しくなった。
17:34まあいいや。
17:36よく何か言っても持ちこたえてたね。
17:42すごい。
17:44元気。
17:45あとは。
17:46まあ家に戻ってこれ一瞬ですけど、一時ですけど。
17:52戻ってこれたのは嬉しい顔がしていました。
17:56もうここには戻ってこれないのかもしれない。
18:00もし解除になっても。
18:04ちょっと住むのはちょっとあまり。
18:10既に戻られてきた。
18:12人たちは何かに戻ってくるんだろう。
18:16または、どんな人が来るのかもしれない。
18:20ここに戻ってきた。
18:21ここへの家に戻ってくる。
18:24And for a disturbing number, their lives are still in limbo.
18:39Nearby is Haramachi Junior High School.
18:43But for now, it's also serving as an emergency evacuation centre
18:53for those who are living close to the nuclear plant.
18:58I met Shizuo Kono, an evacuee whose home is now a classroom floor.
19:05Your home is just a few miles away.
19:08How frustrated must this be for you?
19:13It's not a regret.
19:16We have to go to bed, and we have to go to bed and sleep.
19:20We have to go to bed and go to bed and walk to bed.
19:22We have to go to bed and walk to bed.
19:24It's been a while for 3 months or 3 months.
19:26Are you angry with the way the situation has been dealt with making you leave your home?
19:34It's a great anger.
19:36I have made the vegetables in the country.
19:44I have to wait for them to be removed.
19:46I have to wait for them to be removed.
19:49I don't need any of them.
19:51If you have any money, I will be bankrupt.
19:55I am a punk state.
20:00Shizuo is facing up to the fact that he may never work on his farm again.
20:05I caught up with the director of the evacuation center, Iwao Hoshi.
20:16So how many people are actually living now in this evacuation center?
20:23It's about 130 miles.
20:26This evacuation center is about 160 miles an hour.
20:30It's about 170 miles an hour.
20:33And thousands of people still remain in temporary and makeshift accommodation.
20:46You know, some of the stories I've heard today have been heartbreaking.
20:52And it's quite tragic to think that there are tens of thousands of other stories just like the ones I heard.
20:59But let's get things into perspective.
21:01The earthquake and tsunami killed over 20,000 people.
21:05No one has died as a result of the fallout from the nuclear plant.
21:10The 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.
21:27Around 30 workers were exposed to high doses initially.
21:31And for these people, there may be a small percentage increase in their risk of eventually incurring some health effects.
21:40I'm in Japan four months after the tsunami struck the plant.
21:57What remains of the radiation now?
22:02And does it justify the exclusion zone?
22:07This is the village of Itate, population usually 6,165.
22:26But it's been completely evacuated, even though it's outside the exclusion zone.
22:35That's because radioactive particles from the Fukushima reactor have been carried here by the weather.
22:44Now it's entirely abandoned.
22:48Every house, every street, even this school.
23:00I've come here today to witness something I've never seen before.
23:04In fact, it's an event that's only happened a few times during my lifetime.
23:08And that's part of a radioactive clean-up operation.
23:12And 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.
23:25Today, 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.
23:44They're looking for two toxic elements which escaped from Fukushima, in particular radioactive iodine and radioactive cesium.
23:59But one of these elements, radioactive iodine, is only present for a short time.
24:06Right now, because about four months has passed, I predict the iodine has disappeared.
24:15And that's because radioactive elements decay over time, eventually changing into stable, non-radioactive forms.
24:25It's the half-life of an element that's a good measure of how quickly this happens.
24:31So, only traces of cesium-137 and 134 are being detected.
24:38So, there will only be cesium in the soil. How dangerous is this? How long will it remain in the ground?
24:48The half-life of cesium is set to be close to 30 years. So, for a long time, cesium will be the biggest problem.
24:56Back in the lab, they found high levels of radiation in the top two and a half centimeters of the soil.
25:06Other studies from nearby found levels more than 500 times higher than normal.
25:13Removing this topsoil here will be an expensive option, and Itate isn't even in the exclusion zone.
25:21Recently, the Japanese government has been monitoring the radiation level across 50 sites inside the zone.
25:36They've set their safety limit at 20 millisieverts per year,
25:40which is the same limit as for people working in the nuclear industry in the UK.
25:45And what they found is that 35 of the sites exceeded this level.
25:52And the highest reading was 500 millisieverts.
26:04The tests will help decide whether these people can go home.
26:08The government has decided to keep the exclusion zone in place.
26:13But that's a more complex decision than it looks.
26:17For perspective, you'd get around that level, 20 millisieverts a year, from two CT scans per year.
26:27On one hand, setting such a limit protects people's health effectively.
26:34But on the other, that comes at a cost.
26:37The upheaval of 78,000 lives.
26:41So let's take stock.
26:52Certainly, governments around the world are looking to Japan to help them make a decision.
26:57Of course, they're going to be influenced by the fact that tens of thousands of people had to be evacuated,
27:03and that the exclusion zone carries with it an economic cost, as well as the human one.
27:09But it's also true that the containment process around the reactor largely worked.
27:16Most of the radiation was kept in, which is pretty remarkable for such an old and flawed reactor.
27:23And most importantly, no one died.
27:27And there have been no associated radiation health risks so far.
27:35One of the questions that Fukushima raises is this.
27:39How do we judge what level of radiation can be considered safe?
27:44This question has been relevant to one place in particular.
27:48The site of the biggest nuclear accident in history.
27:52Let's go.
27:53Don't panic Watch.
27:54.
28:12Pretyat –
28:14A ruined and deserted city in the former Soviet Union.
28:19On the 26th of April, 1986, three kilometres away at the Chernobyl power plant, a reactor exploded,
28:32releasing three tonnes of nuclear fuel.
28:3828 of the workers who were first on the scene received extremely high doses of radiation and died within four months.
28:49But there's another question I'm interested in.
28:54What was the effect of the radiation released on another group?
28:58Not those working at the site or helping with the clean-up, but the general population living here.
29:07Galina Czajka was among those living in Pripyat at the time of the Chernobyl accident.
29:14Today, she's returning to her home for the first time in 25 years.
29:19Here's our entrance.
29:28And here's the door.
29:31Now everything is broken, nothing is left.
29:36On my flat, meet me 25 years after.
29:39When the accident happened, Galina and her children were there to witness it.
30:00We went out and watched it, how the reactor was burning like Bengal fires.
30:13And kids climbed the roofs and watched it, until somebody said it was dangerous and made us stay inside.
30:20They weren't evacuated for another two days, and Galina believes that the accident's impact began soon after.
30:30Soon after the accident, I started to have headaches, terrible headaches.
30:40I got high blood pressure, heart problems.
30:44My stomach started to hurt because of all the nerves, and maybe I've got some sort of radiation.
30:49It's a situation that constantly occupies her mind.
30:59Now I mostly live in fear of poor health, disease, illnesses, death.
31:11You live in fear every day that today you are alive, and tomorrow you get ill.
31:16This is the everyday fear.
31:17Galina is not alone.
31:28Many more people share the same fears.
31:32But it's difficult, scientifically, to show a link between any one person's illness and their exposure to radiation.
31:40But 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.
31:59I've come to meet Professor Mikola Tronko, who's in charge of the Institute of Endocrinology here in the Ukraine.
32:07Initially, many doctors expected Chernobyl to cause different types of cancer in hundreds of thousands of people.
32:18But what actually happened was very different.
32:25Starting from 1990, we saw the increase of thyroid cancer incidence among children.
32:31I must say that it certainly caused a big discussion in the scientific world.
32:37Despite this wave of cases of thyroid cancer, there were no confirmed increases in any other type of cancer in the general population.
32:49We can say that problem number one, as far as the medical effects of the Chernobyl accident are concerned,
32:56is the problem of pathologies of the thyroid gland, particularly thyroid cancer.
33:00How many thousands of people have been diagnosed as having thyroid cancer, as a result, as far as you can understand, as a result of the accident itself?
33:12For all cases of thyroid cancer, the Institute has a register of patients who were operated on for thyroid cancer.
33:22In this register, 2,000 to 2,500 refer to radio-induced thyroid cancer.
33:35The thyroids were removed, studied and stored here.
33:39They found that radioactive iodine from the fallout had been taken up into the thyroid gland, and there it had caused tumours.
33:55It affected children more because the rate of cell division is faster in the thyroid when you're young.
34:02This might have been prevented.
34:06Iodine tablets contain the stable form of iodine, which your body takes up in preference to the radioactive form.
34:15So cancers don't start.
34:21But unlike Fukushima, in Chernobyl, these tablets weren't immediately made available.
34:26How many deaths has this resulted in so far?
34:33There were a few cases of deaths.
34:36The number of deaths for these patients, to be more exact, aged 0 to 18 at the time of the accident, was seven.
34:45That's an incredible survival rate for this type of thyroid cancer.
34:49Yes, high survival rate. After five years, we had a survival rate of 99.5%.
35:00Once the findings of scientists from across other contaminated areas of Belarus and Russia were added in,
35:07they found a total of 15 deaths amongst 6,000 cases of thyroid cancer,
35:14within a population of some 6 million.
35:23People will listen to you and they will say,
35:27yes, of course, he's in the Ukraine,
35:30he has the old, you know, the Soviet mentality of sticking to a particular line.
35:37Why should we believe him?
35:39It has already been recognized by the world's scientific medical community.
35:45WHO recognized it, the United Nations recognized it.
35:50These results have been published in the most respected scientific journals,
35:55in particular in Nature, in Science and many, many others.
35:59At a human level, these deaths are, of course, significant, as are the cases of cancer.
36:13But they're lower than almost anyone expected.
36:19You know, I think a lot of people will be really surprised to hear what Professor Trongo had to say.
36:24I'm pretty convinced by this work on thyroid cancer.
36:29The numbers are very low, but the statistics seem solid.
36:35The research is highly respected and acknowledged around the world.
36:39Of course, it remains to be seen whether this number will grow.
36:42But it's certainly not this figure that's banded around tens or hundreds of thousands of cases.
36:53That seems to be purely a myth.
36:56The full outcome of Chernobyl is not yet known.
37:08But the data so far is feeding into an ongoing debate about the effects of low-level radiation.
37:15The thing is, radioactivity is all around us.
37:23It's in the air that we breathe.
37:25It comes out from the ground.
37:27It's inside our bodies.
37:29The food that we eat is radioactive.
37:32All living tissue, for instance, contains radioactive carbon-14.
37:36This banana cake contains potassium-40, as do these Brazil nuts.
37:42So every time I have food like this, I'm increasing the amount of radioactivity within my body.
37:50There's a constant background radiation that does us no harm at all.
37:57It's when the level of radiation increases above that background that the controversy arises.
38:03The scientific consensus has been that any dose of radiation above the background can cause damage.
38:13And so the picture would look like this.
38:17Harm against dose.
38:20It was a straight line.
38:22But even low-dose levels could be harmful.
38:25This remains the consensus.
38:27But there are a number of scientists who believe there may be a different theory.
38:33It goes like this.
38:35Low doses may not be harmful at all.
38:38There's a certain threshold level above which the harm begins to rise.
38:44It's a quite different way of thinking about radioactivity and its harmful effects.
38:51This isn't just different, it's highly controversial.
38:57There's an ongoing debate over the shape of the curve,
39:01because it's difficult to collect evidence at such low levels.
39:05And it's possible that there's a small section of the population
39:10that may be more sensitive than others to low-dose radiation.
39:22While the scientific debate continues,
39:25the people of Pripyat must continue to live their lives.
39:29They've spent more than 25 years trying to understand the impact of radiation on their bodies.
39:35What will it do to me?
39:45I will die.
39:46What else can it do to me?
39:48Illnesses, suffering and death.
39:50What other result?
39:58The studies suggest that it's unlikely that most of these people will die
40:01or get ill from the radioactive fallout.
40:04But instead, they live in constant fear of what the radiation might have done to them.
40:10Fear and horror.
40:15Horror and fear.
40:17Or sadness and grief.
40:19It's a large-scale problem, as Dr Marina Gresko knows first-hand.
40:38She specialises in counselling Chernobyl evacuees, but she's also one herself.
40:44At the time of the accident, she was a nine-year-old attending school here.
40:53As a rule, the most widespread are still depressive moods, anxiety symptoms, worry for the future,
41:02including worry for their own health and their children and grandchildren.
41:05Suicidal moods and thoughts are generally present among people, and some have problems of alcohol abuse.
41:19Dr Gresko sees these problems herself in large proportions of evacuees.
41:24Out of all people who were evacuated, about 70% suffer from anxiety and depression, and about 40% possibly have alcoholism problems.
41:37Dr Gresko's statistics refer only to her own patients, but there's much wider support for this view.
41:51The UN-backed Chernobyl Forum report has stated that the mental health impacts of Chernobyl
41:57is the largest public health problem unleashed by the accident to date.
42:02So what does this mean for the people of Fukushima, who've had their lives turned upside down by the tsunami and then the nuclear evacuation?
42:25It seems the greatest threat to their health now may be fear of radiation and the stress of evacuation.
42:46But of course, the events in Japan have a much wider importance.
42:50We all face choices over the coming years about how we get our energy.
42:58It's a question that's made all the more urgent by the issue of climate change.
43:08If we carry on burning fossil fuels, coal, oil and gas at the rate we're doing,
43:14then we risk changing our planet's climate, the effects of which could be devastating.
43:21And to my mind, this can never be purely a scientific problem.
43:26It's indisputably tied up with economics and politics.
43:31You'll have your views, and I'll have mine.
43:34But it's a debate that needs to be informed by an assessment of the scientific risks.
43:39The influence of politics and economics on nuclear power is, of course, nothing new.
43:50And really, from the moment scientists first started to understand the power bound up inside the atom,
43:56it was inevitable that politicians will be drawn to this irresistible bounty of energy.
44:01And I think these politics have had an impact on my science, the science of nuclear physics,
44:11and its attempts to find the safest way to unleash the power of the atom.
44:16The creation of the atomic bomb was one of the most monumental scientific projects of the 20th century.
44:34It brought terrible destruction, but it also demonstrated the power of nuclear physics,
44:52and shortened America's war in the Pacific.
44:58After the Second World War, physicists were lionised as heroes.
45:04And there was this tremendous faith in science to provide solutions and answers to all the world's problems.
45:12And as for nuclear technology, well, the belief was that it had brought an end to the war,
45:17and now it would provide us with electrical power.
45:25The atomic age was born.
45:28A giant of limitless power at man's command.
45:32But in the new atomic age, there were deep connections between the civilian program for nuclear power
45:39and earlier military projects to build the bomb.
45:47This is Bentwaters Park on the Suffolk coast.
46:04It used to be a US Air Force base, and was at the forefront of the Cold War.
46:08This bunker, and every one of these, was a store for one thing.
46:16Nuclear weapons.
46:21Each one of them was packed full of warheads,
46:24bombs that could have been used against Soviet Russia in the event of a war.
46:27Plutonium in warheads could come from both military reactors and the early civilian reactors.
46:46And more generally, the bomb program and the civilian power program that followed
46:51shared the same reactor physics, based on uranium.
47:04But it didn't have to be that way.
47:07And at the time, there were some who thought it shouldn't be that way.
47:12Scientists continued to experiment with other ways of producing nuclear power,
47:17not just from uranium.
47:20And the story of what happened with one of these alternative fuels is a fascinating one.
47:27It's one of the most overlooked elements in the periodic table.
47:31Thorium.
47:33Some scientists have made great claims for its potential.
47:37It's more efficient.
47:39It burns more completely.
47:41And it's more abundant than uranium.
47:43But others see it as a difficult element to work with.
47:47It's harder to trigger and sustain a nuclear reaction.
47:50Crucially though, thorium reactors don't produce plutonium in a form that can be readily used in weapons.
47:58One extraordinary man was keen to drive through thorium as an alternative nuclear fuel.
48:05His name was Elvin Weinberg.
48:06Now, strangely, Weinberg was one of the architects of the very earliest uranium nuclear power plants in the US.
48:14But despite his involvement with these reactors, Weinberg was keen to find safer alternatives.
48:21He became convinced that thorium reactors were the way to go.
48:26As 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.
48:40This was a moment when the politicians were faced with a choice.
48:44They could either continue with the thorium reactors and explore other, safer options.
48:55Or they could stick with the uranium-based reactors they knew and had invested in.
49:01They chose uranium.
49:06Weinberg's plans were sidelined, and after 18 years as director of a key government nuclear lab, he was forced out.
49:24I am not saying that thorium was in some way the lost saviour of nuclear power.
49:30But Weinberg's story was representative of something different, the shutting down of scientific options.
49:41Now, things have changed.
49:47The Cold War is long over.
49:51And there's a renewed interest in finding safer ways to approach nuclear power.
50:03People are exploring new ideas, and some are returning to those which were shelved in the 1970s,
50:11and revisiting the work of scientists such as Alvin Weinberg.
50:15What Weinberg had planned was a radically different kind of nuclear reactor.
50:22Not only did he propose using thorium instead of uranium as a fuel, but also to use it in liquid form.
50:29It'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.
50:36And 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.
50:57It's perhaps too early to judge whether thorium will realise its potential and live up to its promise as a nuclear fuel.
51:04There are many technical and scientific challenges to overcome.
51:14But the reason it excites me, as a nuclear physicist, is because of the intellectual ambition of the work.
51:21There are already glimmers of what might be achieved if we do experiment.
51:34I think one of the most exciting prospects to come out of recent research is how to deal with nuclear waste.
51:39You see, long-term waste remains radioactive for tens of thousands of years, so how to deal with it is obviously a very thorny issue.
51:53At the moment, the only accepted thing to do is to bury it deep underground in geologically sealed sites.
51:59But there's an obvious problem with this. It simply sits there as a legacy for future generations.
52:10Here 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.
52:20Dr. Uli Kurster is in charge of researching this process here. It's called transmutation.
52:34So we can turn one element to another, so we can destroy long-lived radioactive waste by turning it with this transmutation into short-lived isotopes which go away quickly.
52:49Ultimately, what happens in any nuclear reactor is that by splitting atomic nuclei, an element is transformed into other, different elements.
53:02And what they do here is rather similar, just accelerated.
53:07They 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.
53:19Transmutation 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.
53:36To perform this work, they need a specialised nuclear reactor.
53:40They then take a small piece of radioactive material, in this case, americium-241, and load it remotely into the reactor's core.
53:55Once 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.
54:19So 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.
54:31Instead of waiting for 50 years for something to happen, we can shorten it down to one year.
54:36And this blue light in the shielding water is a sign that transmutation is happening.
54:45It's called Cherenkov radiation, and it's created by the products released as one element is changed into another.
54:53After 50 days or so in the reactor, the americium, which had a half-life of 430 years, has been transformed into completely different elements.
55:06Each peak represents a fingerprint for an individual isotope.
55:13If 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.
55:27It's a process that can be applied to other, more toxic waste products, which can be radioactive for thousands of years.
55:34It'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.
55:44So, there's an important question that many of us are wrestling with.
56:00Should Fukushima really be the end of the road for nuclear power?
56:04And I think my answer will be no, nothing is perfect.
56:12There are, of course, consequences when things go wrong, when there's an accident.
56:17But then, of course, this is true for all types of power, coal, oil, gas, renewables.
56:23What's so special about nuclear power is our dread of radiation.
56:27But my hope is that whatever we decide, it will be based on a careful assessment of rational science.
56:37What's so special about nuclear power?
56:38What's so special about nuclear power?
56:39What's so special about nuclear power?
56:40What's so special about nuclear power?
56:41What's so special about nuclear power?
56:42What's so special about nuclear power?
56:43What's so special about nuclear power?
56:44What's so special about nuclear power?
56:45What's nuclear power?
56:46What's nuclear power?
56:47What's nuclear power?
56:48What's nuclear power?
56:49What's nuclear power?
56:50What's nuclear power?
56:51What's nuclear power?
56:52What's nuclear power?
56:53What's nuclear power?
56:54What's nuclear power?
56:55What's nuclear power?
56:56What's nuclear power?
56:57What's nuclear power?
56:58What's nuclear power?
57:00What's nuclear power?
57:01What's nuclear power?
57:02What's nuclear power?
57:03What's nuclear power?
57:04What's nuclear power?
Be the first to comment