 Yn gwneud y gwerthoedd o'r accidento warehau'r cyllidyddwyd, wrth gwrs ddim yn bellach gwnaeth rhyw o'r accident a'r acroball gwahanol, yn 1986, ac dros yn angen i chi deall y gwahanol yw'r ysgol, ac roedd bod'n eich taethau, yn myfio'r unrhyw yn gwneud hynny'n gwaith, wrth gwrs o'n mae'n gwylltio'r acroball gwahanol, ond arall o'n gwneud hynno yn ei wneud, Yn ymddangos y Chenoble yma, y cyfnodau ymddangos yn ymddangos. Mae'n gweithio'r cyfnodau chenoble, ac mae'r cyfnodau gyda'r cyfnodau cyfnodau a'r cyfnodau cyfnodau ac yn ymddangos y cwestiwn o ran ymddangos cyfnodau, ac yn ymddangos y ffordd mae'n gweithio Ffucashima. Mae'n gweithio'r cyfnodau a'r cyfnodau ar y cyfnodau. Ac rhywbeth eich gwasanaeth gwyddoedd nhw ddeithaswyllwyr deithaswyll yn ymddangos, ac rhywbeth eich cyfnodau gyda'r cyfnodau am y ddweud. Rhywbeth y gallu rhywbeth eich gwreithio'r cyfnodau dyma. Rhywbeth eich cyfnodau yn ymddangos y gallu wandio gyda gorau'r cyfnodau. Felly roedd yn fawr yn rhoi. Rhywbeth eich clywed ddim yn caeth ddweud yr brif familiarol oherwydd bydd gennych yr celfnodau gyfnodau ymddangos. I don't know. We're talking a lot about nuclear power because Britain wants to build 10, if we can afford it, or if the companies that want to build them can afford them, they want to build 10 new nuclear power stations. It's a big debate at the moment because of the potential environmental health effects, the accident, the big cost of nuclear power. Back in, this is an advert from the 1960s when Britain's first nuclear power stations were being built, and the idea then, that says flick, by the way, there, that doesn't say what you might think it says. Yeah. So everybody thought in the 1960s, 1970s, everybody thought that nuclear was going to be the great white hope of technology. The phrase was that it would produce electricity that was too cheap to meter. It was going to be so cheap, nuclear power of the atom, going to produce electricity that was so cheap. We wouldn't even need to have electricity in our houses because it would be more expensive to count how much we'd used than to produce it because it didn't work out that way and it didn't work out that way for various economic reasons, but also because there have been some quite high-profile accidents at nuclear power stations. I won't go through these in detail, but we had the first nuclear accident at a wind scale, which is up in the northwest, they now call it Sellafield. It was so bad they had to change the name. It was at a plutonium production plant, which was producing material for our nuclear weapons programme. The first two of these accidents, one in Kish Tim in Russia, were both associated with the Cold War development, the production of plutonium tritium for the nuclear power programme. The nuclear weapons programme in the UK and Russia. Three Mile Island was the first serious accident at a civilian nuclear power station, and it caused a partial meltdown of the reactor core. I won't go into the reasons because I'll be here all day. No radioactivity escaped from the containment, no significant radioactivity escaped from Three Mile Island into the environment, but it was the first kind of warning that this stuff could be dangerous. There was a certain complacency at the time that nuclear power was dead safe and that the risk of accidents was so small it wasn't worth worrying about. Then of course we had the Chernobyl accident in Ukraine in 1986, and I started working in about 1990 on my PhD studying the effects of Chernobyl radioactivity up in the Lake District in the northwest of England. So a very far-reaching accident. Then of course there was Fukushima in 2011. Here we go, that's Chernobyl. Here's the Chernobyl reactor. It was an explosion of steam because the nuclear reactor, for various reasons, it went out of control, superheated the steam within the reactor core and the explosion was sufficient. There's a 2,000 ton concrete lid on top of the reactor core, the explosion was sufficiently powerful to blow that concrete lid off the reactor, destroy the reactor building and send radioactivity throughout quite a large part of Europe. There we go, in case your geography isn't too good. There's Chernobyl, this is Ukraine, Belarus and Russia all the way down here. Chernobyl was on the border of Ukraine and Belarus and quite a lot of the radioactivity went to the north into this small country, the last dictatorship in Europe. About two-thirds of the radioactivity went north into Belarus, though the Chernobyl reactor itself is in Ukraine. We can see here, this is Kiev, the capital city of Ukraine, and just here you can see a reservoir system. There's a river here and a whole load of reservoirs going down to the Black Sea. That river reservoir system, the Dnipropripiat reservoir system, provided drinking water irrigation, fishing for a population of about 15 million people. When I started working on Chernobyl, there was a lot of concern about the contamination of this aquatic system and that's what we started doing a lot of work on. That's the pattern of fallout and if you followed the Fukushima accident at all, in the first few weeks, all the newspapers and TV were talking about iodine-131, which is a very short-lived radionuclide. It's only around in the environment for a first... I don't need to explain what a half-life is because you're all physicists. It's got a half-life of about eight days, so it's not around for very long, but in that period it can have very significant radio-toxic effects. The one we're talking about at the moment at Fukushima and still at Chernobyl is cesium-137 because that has a 30-year half-life, so still more than half of the Chernobyl radio-cesium is remaining in the environment. We can see the pattern of contamination. There's a patch around the power station here, we call it the 30-kilometre zone, where 150,000 people were evacuated because of this high contamination from radioactivity directly from the explosion. There's another area here that we've worked in, which is to the northeast, and it just happened that as the cloud of radioactive gases passed to the northeast, there was a rainfall, and the rainfall washed the radioactivity out of the air and under a great patch of contamination around here in the eastern part of Belarus and the western part of Russia. This is the map of cesium in Europe. See, these are the two blobs of contamination we just saw. A contamination went north up into Scandinavia, parts of Austria, southern Germany, and we even, you can just see it here, on the northwest we got some contamination. That was again where it happened to, it rains a lot in the northwest, north Wales, southwestern part of Scotland. It washed out the radioactivity onto the land and last year they stopped sheep restrictions in the Lake District from Chernobyl radioactive contamination. So a very far-reaching accident and a very long-lived one. This is a picture of Pripyat, which is the town that was built to house the workers at Chernobyl. I don't know if you can just see it in the background. Dimly in the background, that's what we call the sarcophagus, which is the building that was put over the reactor to contain the radioactivity, and the reactor core is still in there. So this city is very, you know, three, four kilometres from the Chernobyl power station itself. That's evacuated and if you go there now and stand on one of the buildings, you see about you sort of a science fiction type scene of trees growing in the middle of the roads, you go to the sports field in Pripyat and there's a little forest in the middle of the sports field. I'll talk a little bit about this later. Nature is beginning to take over the contaminated areas. Understandably, the media reporting of the accident, like at Fukushima, there was talk of apocalypse and nuclear meltdown, very dramatic headlines, quite understandably. I looked through some of the headlines just to remind us what it was like. We had very dramatic pictures of the damaged reactor with deadly toll of Chernobyl and these dramatic pictures of people in radiation suits going around measuring things with Geiger counters, cancer danger from isotopes, some terrible pictures of the people who survived the accident, at least the people who were working in the first few days to clean up the accident. There were helicopter pilots sent in who had to hover over the destroyed reactor and drop sand, boron, lead onto the reactor core to put out the reactor fire and they were exposed to a whole nuclear reactor's worth of radiation. There were about 134 of those people got radiation sickness from the intense radioactivity there and approximately 40 of those died, some very dramatic pictures. Another thing we've seen since Chernobyl is very dramatic pictures of children with cancer and this is an issue I want to talk about because even now, every anniversary of Chernobyl, the 20th anniversary, the 25th, a BBC reporter goes to a hospital in Ukraine and finds a child with cancer and says, this is because of Chernobyl. I want to highlight a bit how the difference between physics and the media, there are differences. We try in physics to look at things statistically and use the sometimes dull and sometimes soulless statistics. The media understandably like to focus on individual cases, individual people, because that's what we like reading about. I want to draw this distinction between how the media approaches a subject and how physicists and scientists approach a subject. On a slightly lighter note, we saw headlines like Austrians told not to panic. If I was an Austrian and I woke up in the morning over breakfast, opened my newspaper and it said, don't panic, my first reaction would be, why are they telling me not to panic? There must be something wrong. The Japanese were criticised a lot for their handling of Fukushima, but I had a lot of sympathy for them because it's an extraordinarily difficult thing to manage information in the context of a major nuclear accident because whatever you say is going to be taken with mistrust because of the situation or the fear surrounding radiation. The media naturally focus on the worst-case scenario. I've seen estimates for the death toll from the Chernobyl accident, which range from 42, which is significant, but not a major, major accident, up to, well, actually 500,000 I've seen estimates. Of course, if I'm a reporter and I go with my story to the editor and say only 42 people died from Chernobyl, it doesn't really hit the headlines. The media naturally go for the worst-case scenario, paint the worst picture, whereas hopefully scientists try and get to the facts, even though, as in the case of Chernobyl, it takes about 20 years for us to get there and we still don't know at the end because we still say there are uncertainties. So I want to try and understand where the radiation risk from Chernobyl was and so that we can get this terrible accident into context. How do we know radiation is bad for us? I mean, it wasn't always known that it was bad for us. In the 1920s, when Marie Curie had just discovered radium, people used to take radium baths and I've got a great picture of some radium bath salts where people would, the instructions on them say, you put these salts in your bath, you get in your bath, you cover the bath over so you inhale the maximum amount of radioactive radon gas, you sit in your bath for 40 minutes and then you go and lie down, presumably to recover from the radiation sickness you've got from your bath. People thought initially that radiation was good for you and in some respects it is because we use it all the time in hospitals to cure cancer, to do diagnostic tests and so on. So it's not a clear picture, but we now know that radiation does pose a risk to our health and we mainly know that because people have studied the people who survived the terrible Hiroshima and Nagasaki atomic bombings. In 1950 there was an institute set up in Japan called the Radiation Effects Research Foundation and the whole job of this institute was to study the people who'd survived the terrible atomic bombings at Hiroshima and Nagasaki. What they did, they put them into groups, we call them cohorts, and they studied about 90,000 people, put them into groups and they reconstructed for each of those people the radiation dose that they received from the atomic bombs in Hiroshima and Nagasaki. They put them in groups and they followed their health for the rest of their lives and this study is still going on because there are still a few survivors of Hiroshima and Nagasaki alive today. So each five years they update with their results and they look at how many cancers there were, how many people died of heart attacks. They looked at the next generation, the children of those survivors, to see if they could see any health effects on that next generation. What did they find? This is the main thing that they found. This is a plot of the cancer deaths per 10,000 people in that group. It's a plot against the radiation dose rate that they got in millisieverts. You probably aren't familiar with that unit. It's a measure of radiation risk. When I work at Chernobyl, I get a little badge and when I get back I send it off and somebody sends me back a piece of paper which says you got 0.1 millisieverts of radiation when you were at Chernobyl. If I want to and I'm feeling a bit morbid, I can calculate what my chances of getting cancer in later life are from that radiation risk. It was always low, otherwise I wouldn't keep going there. A millisievert, a thousandth of a seevert is a measure of your radiation risk. What does this graph say? It says that radiation is bad for us. This is the number of cancer deaths per 10,000 people. I'm going to point to it because I think he's gone. The number of cancer deaths per 10,000 people as the radiation dose rate goes up. We see a straight line relationship. The more radiation, the more your risk of getting cancer in later life. This dotted line is a normal cancer incidence. About a quarter to a third of people die of cancer in most developed countries. What does it say? It says that there is an increased risk of getting cancer at significant radiation dose rates. The difficulty with this graph is that most of the radiation dose rates are around here. Most people are not exposed, fortunately, to atomic bomb-type radiation. Most of us, even when I go to Chernobyl, I get dose rates down here. It's very difficult statistically to see a difference between that and the normal cancer incidence. But we know from this graph and we can estimate what our cancer risk is. We know from Chernobyl that there were significant cancer effects. We know that 40 people died after the Chernobyl accident. The helicopter pilots, the firemen, the people that got very intense radiation, died from acute radiation sickness. In Belarus and Ukraine, children who were exposed to iodine 131 is very short-lived but very radio-toxic radio-nuclide. There were more than 4,000 cases of thyroid cancer. 15 of those have died. This is the plot of thyroid cancer in Belarus up to 2002. We can see that in the year of Chernobyl fewer than one case in 100,000, but this rose and is still going on to about six, seven, eight cases per 100,000. So a significant increase in thyroid cancer. The reason for that was that the Soviet Union didn't stop children from drinking milk, eating leafy vegetables in the news after Fukushima. You might remember that there was a big effort in Japan to stop people from eating contaminated products in those first few weeks after the accident. The Soviet Union didn't do that, and that has led to this big increase in thyroid cancer. Fortunately, thyroid cancer is a very treatable cancer. In 99% of cases it can be successfully treated, ironically by iodine 131 therapy. So we have seen health effects from Chernobyl. The other health effects that we might see, the other cancers, the breast cancer, cancer of the brain, lung cancer, we're just not going to see those cases, because we can't statistically tell the difference between the small additional risk that people had from Chernobyl compared to the natural incidence of cancer between a quarter and a third of people dying of cancer. So far there's no clear evidence of increases in leukemia, although we would expect to see an increase. We can make an estimate based on what we know from Hiroshima and Nagasaki of about 8,000 additional future cancers in the most affected populations. So that's the people who were evacuated, the people living in the areas around Chernobyl. Why will we never see it? We'll probably never see it because the number of natural cancers in that population is 470,000. So that's what we would expect people to get in that population of about 2 to 3 million people. So we're not going to see an increase, or it's going to be very, very difficult to see an increase of 8,000 against that background of about half a million. If we try and make an estimate, and we're using models and our hypothetical knowledge, we try and make an estimate for the world population. So that means we add up all the radiation doses that people got in the UK, in Germany, in Japan from Chernobyl, and if we add up all those tiny doses and then calculate for the enormous population, then we can estimate about 30,000 early deaths, so very significant. We have to try and put that risk into context, though. In the UK, people got about an additional 0.1 millisievert of radiation from Chernobyl. On average, in the UK, everybody gets about 2.2 millisieverts of radiation from cosmic rays, from the natural radioactivity and building materials in roads, in houses. So in the UK, we could estimate that 50 or 60 people would die of cancer from Chernobyl amongst a massive number of tens of thousands who would die from other forms of radioactivity in the environment. Natural radiation, when you go on an aeroplane, you get an extra radiation dose. So we're talking about an additional risk, but a relatively small additional risk to the individual. I want to think about, I want to try and put this in context, by thinking about what would happen if a terrorist exploded a dirty bomb, a cesium contaminated bomb in London, and we all, in this room, got a radiation dose of 100 millisieverts, which is a typical radiation dose you might get from a dirty bomb exposure. To put that in context, the workers at Fukushima, who stayed around, they call them the Fukushima 50, who stayed around to try and get the reactor under control, they got about 250 millisieverts of radiation. So it's quite a big radiation dose. So if we all, in this room, got 100 millisieverts of radiation, what would we die of? It's a bit morbid. We're trying to understand risk. You probably don't think about it, but when you get in your 40s like I am, you start thinking, what am I going to die of? I can see some of the teachers smiling, smiling nervously. So I want to start. Can all the smokers in the room please stand up? That's just amazing. I'm very happy to see. I'm very happy to see. There are no smokers in this room. That's fabulous. In an average group of 16 to 19-year-olds, about 20% of people smoke. So we'll just imagine that you're an average group of 16 to 19-year-olds. So this section of the audience, can you all stand up please? Just pretend you're the smokers. Actually, half of you can sit down again. That's it about that lot. You've died of a smoking-related illness. Half of people die of smoking. So that's the smokers out the way. What are the rest of us going to die of? You're the cardiovascular disease, people. You all stand up. 40% diseases of the heart, of the lungs and so on. Cancers. About this lot, you lot stand up. In the UK, 23% of people die of cancer. Respiratory diseases. A few people at the front, you're respiratory diseases. You stand up. Accidents. We'll have the smokers here. You can stand up from the accident. Various other causes. The rest of everybody else stand up. OK. Now that everybody's awake, this is what we've all had. We've all had 100 millisieverts of radiation. We've all been exposed to half the radiation dose that the Fukushima 50 got. How many people are going to die of that? Obviously, it's the people with the tennis balls. Who got the tennis ball? You can all sit down now. Who had the tennis balls? Who else had a tennis ball? There you go. The basic point is that we tend to worry quite a lot. Especially when it's radiation. We're scared of radiation. We worry about radiation quite a lot because it's something that we can't see. We don't know the risks. It's associated with nuclear accidents and so on. Really, we should be worrying about the other things in our lives. Especially the smokers. A friend of mine is a... I'm not particularly anti-smoky. If people want to smoke, they can. But a friend of mine in Ukraine is a Chernobyl liquidator. He's one of the people who went in the first months after the accident to do science in the exclusion zone. He's officially a Chernobyl emergency worker and he gets a little card which gives him free bus and tube travel in Kiev. That's about it as compensation. Anyway, he was smoking a few years ago and I said, well, it's not very good for you. Why do you smoke? He said, well, I'm a Chernobyl liquidator. I'm going to die of cancer anyway. Well, he did actually say that. Well, what's the risk? He has got an enhanced risk and it's not insignificant. But if he keeps smoking, he's given up now actually. His risk is 50-50. The things that we do in our lives very often our diet, our behaviour smoking, our risk taking behaviour can have a much bigger impact on our health than some of the things we hear about in the newspapers like free radicals and eating broccoli and stuff like that that we're always on about. I've talked a bit about health effects. I want to talk about the ecological effects. What's Chernobyl done to the ecology of the area? Does Blinky live near Chernobyl? I don't know if people remember an episode of The Simpsons where Bart Simpson catches a three-eyed fish from the cooling pond of his local nuclear power station. We've spent a lot of time studying the aquatic systems at Chernobyl so my question is, does Blinky live near Chernobyl? We know that in the immediate aftermath of the accident there were very severe effects on a small area of forest about four square kilometres of forest near the power station. It's called the Red Forest and if you go there your Geiger counter just about goes off the scale and in the first days and weeks after the accident this area of forest got very, very high doses of radiation and many of the trees there died and the trees were chopped down and buried and there's now a new forest growing in its place. So we're very severe ecosystem effects. Understandably at the time people were more concerned about getting the people out than studying the animals in the area but some Ukrainian scientists took some cattle who had been left in the exclusion zone and some of them died because of the intense radioactive iodine damage to the thyroid in this very contaminated area and the ones that had survived they took out of the exclusion zone and they bred them to see if they had presumably to see if they had two heads or the next generation had two heads or five legs. The report of this ISO said the second generation were normal which presumably means they had the right number of heads and legs and so on. There were a lot of stories after the accident and the same is true of Fukushima, a lot of stories of mutant animals. It's possible, it's possible that there were but probably quite unlikely. But we know that there were severe impacts on the ecosystem from this very intense radiation during the first days and weeks after the accident. What happened in the longer term? Well we've been studying lakes at Chernobyl so this is the 30 kilometre zone. This is a lake called Glabokki Lake which is probably the most contaminated lake in the world at least it wasn't till the Fukushima accident. So we studied lakes at different levels of contamination from near to background radiation up to this very, very contaminated lake. We even looked at the cooling pond. This is a reservoir 22 square kilometres. There's the Chernobyl plant itself. The village of the town of Pripyat is just there to the northwest. So we looked at the cooling pond. What's growing in the Chernobyl cooling pond? We looked at the biodiversity of aquatic invertebrates. My biologist colleagues tell me I shouldn't call them invertebrates insects I should call them invertebrates but the little creepy crawly things that live in the very contaminated sediments of these lakes. And we studied the things that we expect or biologists expect to be related to the biodiversity of insects in lakes things like the size of the lake, the conductivity, the pH, the phosphate and we also looked at the load of radioactive cesium the radiation dose that these insects were getting. This is us standing. This is me. Try to pretend I know what I'm doing. I didn't do the nitty-gritty bit of this which was identifying all the insects, studying them. My biologist colleagues did that. So we collected lots of insects from lots of different lakes to try and see if we could see an effect of the radiation on the aquatic ecosystem. And we couldn't. This is a measure of the species richness. So the number of species in these different lakes and this is increasing radioactive contamination. And what did we see? No significant relationship between the radiation and the diversity or abundance of aquatic invertebrates. Indeed, our most contaminated lake, Glabokie Lake, had the most diversity of aquatic insects. We looked at fish. This again is the number of species of fish and this is increasing radioactive contamination of different lakes. What do we see? No correlation. What we see is what biologists always see, which is that in big aquatic ecosystems like the Kiev Reservoir, we've got lots of habitats, lots of fish diversity, big aquatic ecosystems like the Cooling Pond, which had, at least until the year 2000, it had the additional advantage of nice warm water coming in from the power station, a very high diversity of fish species and three red data book rare species. So no impact as far as we could see of radiation on the aquatic ecosystem. What happens if we look more in detail, and there have been a lot of studies since the Chernobyl accident about the symmetry of organisms, is there some effect of the development of organisms of the radiation. Some studies say yes, some studies say no. There's some evidence of increased mutation rates of certain genes in the animals, but there's no evidence of serious effects on the physiology, on the reproductive capability of different organisms. What the Ukrainian and Belarusian scientists who work in the exclusion zone have found is that after the accident there was a dramatic decrease in animals associated with humans, pigeons, rats, sparrows, animals that like to live where humans live, a dramatic increase in the biodiversity and abundance of wild species. So now in the exclusion zone there are 200 species of birds, 55 species of mammals including wolves, the Belarusians have reintroduced the rare European bison into their sector of the exclusion zone and the population is doing very well. 8 species of reptiles, amphibians, lots of fish species. It doesn't say that radiation is good for animals, it just says that human habitation of an ecosystem is much, much worse than the biggest nuclear accident in history. What we do to ecosystems, hunting, fishing, chopping down trees, agriculture, does much more harm to an ecosystem than even a very serious nuclear accident. So when the people were moved out of this area, there was a big increase in the abundance and diversity of wild species. I want to talk a bit about Fukushima, because I can't not, and I have to say that I spent 20 years studying Chernobyl and the whole point of my research was that we would better be able to predict the consequences of another nuclear accident, but really in my heart of hearts I never believed we'd have another nuclear accident. Fukushima has shaken my faith in nuclear power and in the kind of ability of organisations to see the big obvious thing that they've been ignoring this whole time. The big obvious thing with hindsight at Fukushima is that they didn't plan for the 1 in 1,000 earthquake and tsunami. We probably know the history, but there was a magnitude 9 earthquake at one in a 1,000 year event. There was a tsunami of height 10 metres at Fukushima and the sea wall at Fukushima was only 6 metres. So in response to the earthquake, the nuclear power station shut down as it should do. It was automatic shut down of all the reactors, but what they didn't reckon on was the tsunami overwhelming the sea defences and destroying the backup diesel generators. Nuclear power stations, they need continual cooling even after they've been shut down. If you don't do that cooling, we get the terrible consequences you see here of the explosion. It wasn't an explosion, it was an explosion of hydrogen gas that came from the heating of the reactor core itself. With hindsight, it was an obvious accident. Indeed, there were several reports prior to Fukushima which said that this sort of plant in this area of high earthquake frequency is at risk and that the sea defences or the backup safety systems should have been designed with this one-in-a-thousand-year earthquake in mind. The knowledge was there that just wasn't the willingness or the kind of corporate ability to take on that knowledge and do something about it until too late, which is very often the case with human endeavours. The earthquake did 15,000 deaths, more than 15,000 deaths, more than 125,000 buildings damaged or destroyed. The actual consequence of the earthquake and tsunami were enormous. I want to try and put the radioactive contamination from Fukushima in context. This is our Chernobyl map. If you want to try and compare, this is the Fukushima map on the same scale as the Chernobyl map. If you want to compare that yellow area of contamination, again, it's radioactive cesium contamination, you compare it with these dark bits here, these dark spots here. If you add it all up, it comes to about a fifth of the area contaminated. The Fukushima wasn't as significant as Chernobyl in terms of area of land contaminated, about a fifth of the area, but in terms of the levels of contamination, some areas greater than three megabeckerels per square metre, which is pretty hot. In terms of the level of contamination, just as significant as Chernobyl, and these areas are still evacuated to this day. I was, well, I'm in Portsmouth, so I was trying to put this in Portsmouth context. It's a significant area of land. If the Fukushima had happened in Portsmouth, the wind was blowing over, this would be that area of really high contamination where people were evacuated. In terms of the UK, it's not a massive area, the same is true of Japan, but it is a very significant area and a very large amount of contaminated land. In Fukushima, about 80,000 people have still not returned to their homes. I was asked to do an opinion in just two weeks after Fukushima was published in early April 2011 about what would happen based on our experience of Chernobyl and I said then, and I think it's still true, that there'll be long-term evacuation and long-term, that means decades of contamination of foodstuffs in many of the contaminated areas. It's an interesting question, what's going to happen to that land? It's going to be like Chernobyl and I believe it will be. If the Japanese leave it, in other words they don't try and do the massive clean-up job that they've promised to do, it's an enormous job to try and clean up that sort of area, 400 square kilometres of land. If they leave it then it will probably become a nature reserve. Another issue which I've tried to allude to is the social and psychological impacts of nuclear accidents. Because of this fear that we have of radiation, the impacts of a nuclear accident are possibly worse in terms of their mental health, economic and social impacts than the direct impacts of radiation. I was involved in the UN Chernobyl Forum report and I was involved in the environment part of that report, the health section of the report, and in conclusion, the mental health impact of Chernobyl is the largest public health problem unleashed by the accident to date. I believe that's true. Because radiation holds such fear for people, it's very difficult to get across information about radiation, what in people's individual risk is, the fear, the dislocation of people from their homes, their inability to return to their homes, causes enormous social and psychological impacts in itself. Already, this is a recent nature editorial, fall out of fear. Already, after Fukushima, we're seeing mental health social impacts on the evacuation. I want to put up a picture. I often put this guy on my lectures. He's called Grigory Maminin. We were doing a lot of work on a contaminated lake in Belarus. It was an evacuated area. We were studying the fish to see how contaminated they were, to see if there were any radiation effects on the fish. He was there with his fishing rod, catching the fish for his tea. He'd refused to move from the evacuated area. He said, I'm not going to move from my house, I'm going to live the way I want to live. He was growing all his own vegetables in the contaminated soil. He took his water from a well. He got quite... I have to say he's dead now. But he lived to 75, which in Belarus, this was in the 1990s, in Belarus at the time, life expectancy in men was down to 60. Not because of radiation, but because of alcoholism, smoking, poor diet, unemployment. All these factors have a much bigger impact. I think we thought he was mad, but thinking more about it, I think he made the right decision. A lot of risk is about how we perceive it, whether we think it's going to bother us, or whether we're just going to get on with our lives and not worry about it. I'm just going to finish for five minutes. After all that, talking about the worst nuclear accidents in history, do we need to build nuclear power stations? Well, I don't know. Let's have a look. We're all familiar with these graphs, probably. This is the global fossil carbon emissions since the Industrial Revolution. How much carbon we're putting, how much carbon dioxide we're putting into the atmosphere from petrol, coal, natural gas, cement production, going up massively following the Industrial Revolution, corresponding increase in global temperatures. We're all familiar with that story. This is world energy use. This is the US Energy Information Administration. This is how many joules of energy we need in the world to do all the things we want to do, like drive cars and do PowerPoint presentations and all that business. This is the historical, up to the year 2002, increasing energy demand, projected almost another 50% again during your lifetimes and probably doubling of energy demand during your lifetimes. How are we going to square the circle? How are we going to provide the energy that the world needs without producing more CO2? The fact is that there's Roman Abramovich. I always put him there because I don't like him. I shouldn't say that. I'm a lead united supporter. Until we get in a Roman Abramovich, I'm not happy. In this room, relative to the rest of the world population, we're rich. Everybody in the world says, we want to be rich as well. People in the developing world say, why can't we use as much energy as you do? The question is how do we reduce our CO2 emissions and at the same time maintain the standard of living we want and improve the standard of living of poor people around the world? Almost half the world's population live on less than a pound a day. This is the problem. The carbon content of fuels, gas, oil, coal, both nuclear and renewables, it's not true to say that they're carbon free because in order to build a wind farm, in order to build a nuclear power station, you need lots of concrete which produces CO2, but in their use, they don't produce any CO2. This is the problem we have specifically in the UK. This is UK electricity mix. So a lot of gas, a lot of coal, about 23% of electricity, at least in 2005, was generated by nuclear, but by 2020, eight of our nuclear power stations will have closed down and will only have one left, so the share of nuclear generated electricity is going to drop to 4%. So the question is, how do we make up that energy gap? Are we willing to put up with a small, and I think it is a small risk to our own health in order to protect the environment? And I would remind you that the world's worst nuclear accident, as far as we can tell, has had no significant impact on the ecosystem. We do more damage to things that we do to an ecosystem than a nuclear accident does. So I think we have to think about our perspectives, and if we're making a choice for or against nuclear, we have to bear in mind that nuclear doesn't do any damage to the environment. What it does is pose a risk to our own health, but I think it's probably a small one, but I'm not going to answer the question. Well, I think that's it. Thank you very much.