Episode 8 Bang Goes the Theory

Episode 8

Science series. The team examines nuclear power. Jem Stansfield climbs into a reaction chamber to show how a nuclear power station works and looks at the Fukushima radiation scare.

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Her law and welcome to the show. Sadly, the last of the series. I am


in a blustery Hinkley Point in Somerset, home to three generations


of nuclear power station. Over there, you can see Hinkley Point be,


which is currently generating power and supplying 1 million homes in


the UK. Hinkley Point Bay is being decommissioned. In that empty space


behind that is the proposed Hinkley Point C, the new nuclear power


station, get to be built, that will generate power for 5 million homes.


In March, a group -- the reported on the tsunami which hit Japan


resulting in the loss of 15,000 lives, damaging the Fukushima


nuclear reactor. It is that incident which came to dominate the


headlines. But how much of the science behind those headlines do


we understand? Tonight's show, we're going to one of Britain's


oldest nuclear sites, to get to that on the issue of what to do


with nuclear radioactive waste, Liz looks at the effect of radiation on


us for help, and GM gets to the heart of the matter by showing us


how a nuclear power station actually works. I am about to do


something almost nobody ever gets to do. Goal inside a nuclear


reactor. Built inside -- in 1978, this one is almost identical to the


Fukushima reactor, except it was never switched on. You walk into a


nuclear power plant, you cannot help but be awestruck by the size


and apparent complexity of the place. But the truth is, when you


get to the heart of the operation it is all surprisingly simple. All


of this complex machinery is here to monitor and control the nuclear


reaction that he's water and turns it into steam. Once the steam


leaves the reactor, you're in the realms of conventional power. Hawke,


high-pressure steam comes down to write like this and gets fed into a


turbine. There, the technology is not so much nuclear but Victorian -


the pressure of the steam pursues the Blades of the turbine, causing


us to rotate. That turns a generator, which produces


electricity that this plant was built for in the first place. A big


problem I find with nuclear power- station as us that this year -- the


scale of them makes them confusing. But it boils down to this. You have


a nuclear reactor here, it is like a kettle, except the water is not


heated by electricity but by nuclear fuel rods. Oil and water


produces steam. Steam comes down a pipe and impacts on a turbine,


which is essentially a bunch of spoons, on a spindle. That reduces


electricity, and you have got yourself a happy town. The thing


that makes a nuclear power station different from a conventional one


is how the water is heated to form steam. To see that, I have to go


This is the heart of a nuclear reactor. Not many people get to


stand you, because, when active, all of this would be around 300


degrees Celsius. And under a similar pressure that you would


find half-a-mile below the ocean, pushing the walls apart with the


force of 40,000 tonnes. Where does the energy come from to do that? It


These are nuclear fuel assemblies. If operational, this small space


would be packed with 100 of these. Each giving out a vast amounts of


energy in the form of heat. That is because every one of these square


metal tubes would be packed with thousands of little pellets like


this, made of uranium oxide, and uranium is very special to us,


because it is an atom that we can split. When things break apart,


they release the energy stored in whatever was holding them together.


It does not matter if that is an atom or stretched elastic band. We


are going to come in, split it, and what I end up with, is two smaller,


high energy elements flying off in different directions. When that is


an atom, they smash into their surroundings, warming things up. No


matter how small the scissors, they are not the tool for splitting an


atom. To do that you need a small particle called neutrons. When this


hits the centre of a uranium atom, it gets absorbed, causing the atom


to become unstable, and to split. As well as releasing that energy,


you release two or three more neutrons that can fly off into the


surroundings, causing more trouble. That is still not really enough to


sustain a nuclear reaction. Uranium atoms do not absorb neutrons that


easily. Neutrons have to be going at just the right speed, and, for


that, this reactor needs one more thing. Just add water. The water


plays a pivotal role, because it slows down the neutrons, to a speed


where they are more likely to be absorbed by a near banning uranium


atoms, causing them to become unstable, releasing more energy and


more neutrons in a cascade. If you can keep the sustainable, you have


gone critical. Which is a good thing, because, then, you generate


heat sufficiently quickly to run a So, what was it that went wrong at


the Fukushima reactor? To find out, I headed back to the workshop, for


some experimentation. This is pretty much what created those very


dramatic explosions. An unfortunate mixture of hydrogen and oxygen


coming into contact with something hot. The big difference is, there's


involved about 1 million times more hydrogen, and risked splitting more


than my eardrums. But, what possible cause of events could have


resulted in a nuclear power station is up -- releasing one ton of


hydrogen? In the case of Booker shimmer, a massive air quicks


struck and all the main power went out. -- earthquake struck. These


reactors are fitted with an automatic brake, and in the case of


an emergency, neutron absorbing Broads are inserted between the


fuel rods, shutting down the main reaction. But the bad news is, you


cannot just totally switch of a nuclear reactor, because all the


time it had been working, to uranium would have been producing


several radioactive by-products which continues plotting and giving


of heat, long after the main reaction has been shut off. This is


known as decay heat. Even though it is 1.5% of the normal running power


of the reactor, it's still equates to about 20 megawatts. That is the


equivalent of having 10,000 kettles boiling away in there. Even 10,000


kettles were up of heat is not a problem, providing you have plenty


of water circulating through the reactor, taking that heat away.


Even after the earthquake, the pumps pumping the water were still


working fine, running off back-up generators, but then this tsunami


hit, wiping out the back-up generators, and the electrical


switchgear. This meant there was no water circulating through the


reactor, and, just like this cattle, it was beginning to boil dry. --


this careful. -- kettle. It just gets hotter and hotter. Soon, in


the reactor, the temperature reached 1200 degrees Celsius. At


1300 degrees Celsius, something even more serious started to happen.


Surrounding uranium fuel pellets is a metal called zirconium. And that


is then temperatures, it begins to chemically react with this steam


inside the reactor, producing an extremely flammable gas, hydrogen.


Now you have got fuel and hydrogen building inside the reactor vessel,


and the pressure is increasing dramatically, leaving the engineers


with an extremely difficult dilemma. Here is a model we have made to


demonstrate the problem. This is my reactor core. I am going to pot


that inside my nuclear plant. Inside the model, I have put some


reactive metal to simulate zirconium, and, if I add some acid,


it will produce hydrogen gas, in much the same way, and I recruited


their problem. Already, that is getting dangerously high, which


leaves me in a similar position to the Japanese, and I've got to


release the pressure now, because the worst-case scenario is, that


reactor vessel burst, because of the pressure building up inside it.


The workers at Fukushima avoided the worst case scenario, the huge


reactor core itself bursting under pressure, spring superheated


nuclear material at. But some of the gases released into the chamber


flowed back into the building, and created a new danger. That gas is


hydrogen, and when it mixes with air, and comes into contact with


any kind of spark, you have a Ooh! Dramatic and powerful as a


higher rate -- hydrogen explosion is, it is just rapidly burning gas,


and it is reassuring to know that even with an horrendous natural


disaster, the were enough control measures built into the plant that


engineers could stop the excess pressure Breaston the reactor would


sell up. The materials used in nuclear power mean that these


places can never become a nuclear bombs. This is the beautiful old


pink -- Hinkley Point is a control room. It is being closed than now.


But that is not the end of the story. Ahead lie years of


decommissioning. The reactor core is set to remain on site for the


next 100 years. That raises the most contentious issue when we talk


about nuclear power, whether it is an ordinary operation like Hinkley


Point, or the result of a disaster like Fukushima or Chernobyl, what


can we do with the radioactive waste? I went up to the far north


of Scotland, to find out. After a tour to five years of service, doom


racer that -- nuclear power station was decommissioned in 1994 --


Dounreay. Nuclear reactors always produce radioactive waste. That can


range from the contents of the reactor core, to anything in the


plant that becomes contaminated with radiation. Current figures


show that in the UK, we have well over 160,000 tonnes of the staff,


and something needs to be done with it. At Boon Rae, at 2.2 billion pan


clean-up was under way. But after six years, they are still dealing


with the lowest level waste, contaminated paper, rags, and tools


which must be steeled -- sealed into steel drums and painstakingly


analysed. There is more low-level waste than anything else, and some


of it is barely radioactive. Inside the reactor core itself lies a more


serious challenge. Where I am walking here below my feet is the


reactor. Inside the reactor core, is some very hazardous radioactive


material, uranium and plutonium. The big challenge is to get it out


and make it said. This final stage of the clean-up is due to start


next year. Handling this waste will be so hazardous, they are


installing Roberts, ready to do the job run madly. -- robots. --


remotely. First, you remove the fuel from the reactor. This


sophisticated mast has 14 different tools on it which can cut free the


elements in the reactor. It is like a big Swiss Army knife. It is a


huge Swiss Army knife that is designed to work remotely and


reliably. That gets rid of all the fuel in the system. Once extracted,


the pure words are put into a cell containing an automated dismantling


robot. For now, the row was practising with pretend fuel rods,


but once active, it will handle the It is unlike lie we will put anyone


in here again. Another row Bott will transfer the fuel into stain


less steel drums. These drums will go into an underground area under


controlled conditions and be stored there forever. But at Dounreay the


clean up isn't the only challenge. In the 1960s things didn't go to


plan and in a series of accidents thousands of particles of waste


were flushed into the sea. The task now is to recover as many as


possible, one by one. It shouldn't have occurred. We have released


radioactive material into the environment and it is now


uncontrolled. The risk would be a fish ingesting a particle and


getting into the food chain. That was the concern. These particle


will be on the sea bed, in the sand. So the fish would have to eat the


sand. However there was a possibility that they could get


into the food chain and therefore some one could be exposed to it.


The parms are tiny fragments 06 spent fuel -- particles. The team


used a remotely operated vehicle. The challenge is to scan an area


the size of 500 football pitches. As soon as they detect something it


will stop and drill down. They will target it and then just drill down,


suck up a mixture of sand and water. So it is base clay big vacuum


cleaner. Yes. The robot returns to the surface and the canisters of


sand are unloaded for screening. So he is going through all the sands.


Spreading the sand out and monitoring it. You can hear from


that noise that they have found something there. So we divide the


sand down, and check each bit to find the particle. It is there!


So it is in there. You will monitor 60 hectares wrt of sand. Every


grain? Yes with the ROV and any sand that comes back here that


again will be monitored to make sure it is clean before it goes


back to the sea. The radiation given off by these particles can


penetrate human skin. But as the workers never touch it, they're


safe. We know about the particles that are out at sea, is there a


risk of getting particles here on the beach? In any two week survey


we may find two or three. So you are talking three or three


individual grains of sands from all of this sand. If somebody came into


contact with a particle, on the beach. What would happen to them sh


The most likely way come into contact with it is if you got it


stuck on your skin. A couple of days later, you would get a


reddening on the skin, like a burn and that would heal up. That would


be it. But long-term it gives you a risk of developing a cancer. Not


that you will, but there is a risk associated with with radiation


exposure and cancer. I suppose that is what it comes down how to,


however slight a link between cancer and radiation from a reactor


like this might be, it is enough understand tpwhroi generate a sense


of fear in all of us and of course the press. But we weren't always so


nervous of radiation. Once radioactivity was positively


celebrated. It was a fashionable label and radioactive water was


seen as a cure for all ills. But This footage was taken during the


aftermath of the atomic bomb-blast in Japan and the images are


unsettling. Not only because they're a reminder of thousands who


died, but also because these events started a fear of radioactivity.


Since the atom bomb-blast it has been difficult to make a


dispassionate assessment of the dangers. But that is what I want to


do and wipe the slate clean and find out the truth about the


effects of radiation. Jerry Thomas is an expert on the 1986 chorl


disaster. I have asked her to put the number of deaths into


perspective. -- Chernobyl. Everyone knows about the bombings in Japan.


A lot of people died, but most of the population died from the blast


injury. Actually only about 15 to 20% of the people who died as a


result of the bombs died because of radiation. You're talking about


20,000 deaths from radiation. So where do we go? Let's look at


something else. This is the figure of people that were killed as a


result of a dam burst in China in 1975. The dam was there to provide


Hydro Electric power. Does puts it into perspective. Now something


that we do to ourselves and this is cigarettes. This is the total death


toll for 2009 for lung cancer or the other smoking-related diseases


that result in death. Lower down the scale, Jerry says over 2,000


people died in road accidents in 2009. But perhaps most surprising


is her next figure. How about falling out of bed. 106 people each


year fall out of bed. Seriously? Yes. 106 people each year fall out


of bed and die as a result. That is desperate, I didn't mean to joke


about it. It serve serves to make you paranoid about everything.


that is the point, life is risky. So where does Chernobyl fit in?


think I might be shocked. I think it will be less than car crashes.


You're right. I think this is will be a surprise to you. Somewhere


between the number of people who die falling out of bed and the


number who die in car crashes. thought it would be closer to 2,000.


It is remarkable how much lower the death toll from radiation at


Chernobyl is than that in Japan. According to Jerry, that figure


includes both the short-term effects of acute radiation sickness


and most cancers. So the main thing is not to make the mistake of


associate Agnew clear accident to something like an atom bok. The


numbers illustrate. Figures suggest that radiation from accidents like


Chernobyl is not as worrying as a lot of the media coverage would


have us believe. But it can and does kill. And I want to understand


how. I'm meeting Dr Susan short to show me who radiation can do. Here


they grow human tissue cells and expose them to X-rays. This is the


machine. This is the X-ray machine. The beam has energy to irrate yaid


-- irradiate the cells. We switch the machine on for various lengths


of time. Using sum pls, Susan investigates how radiation damages


cells. We have got cells that we were growing in a dish and we have


two sets. This is a group of cells that have not had any radiation.


Each of the dots is a surviving group of cells. That is a group of


cells. Cells growing well. Yes. This is the same cells that have


had a dose of X-rays. Just one dose. It is a marked difference. A lot of


cells died. The reason X-rays can kill cells, because like the


radiation from a power plant, they cause a process called ir


yonisation. That is -- Ionisation. That is a lot of energy and it


producing electrons and free radicals that can damage other


proteins. And it can make its different for the cell to function


The X-ray beam comes out of the head 069 -- of the machine.


machine limits damage to healthy cells. All cells they touch are


affected. But because the machine rotates, healthy cells get just a


brief dose and the tumour is repeatedly exposed. So you build up


the dose and avoid that? Mind yourself. Chris is incredible. The


work of radiotherapists means we're learning more about the effects of


radiation on our health. And already lessons learned from


Chernobyl have had an astonishing effect on the human cost of Japan's


nuclear accident. In Fukushima, what was the death toll? There


won't be a death toll from radiation in Fukushima. Because


they have done all the right things, they read the book and acted as


they should have done. There won't be a death toll in Fukushima and I


would be surprised if anybody loses their life as a result of exposure


to anything from Fukushima. So I hope we have given you some food


for thought. But the bottom line is there are no real easy answers when


it comes to discussing nuclear energy. We have all got strong


opinions the Government is releasing a report into the future


of the UK policy in the next few weeks. We have come to tends of the


show and the series. Before we go, look online. Dr Yang has done a


film about carbon dates. There a lot about nuclear power and


Fukushima. Also the BBC is looking for amateur scientists. Look at


that competition. That is its for this series and thank you for


joining us. It has been fantastic. A treats before you go. If you're


one of the people who haven't seen Bang live, we record a show that we


In the aftermath of the Fukushima radiation scare, the team turns its attention to nuclear power. Jem climbs into a reaction chamber to explain how a nuclear power station works and what happened in Japan. Meanwhile, Dallas investigates the clean-up operation for radioactive waste, and Liz looks at what radiation does to the human body.

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