:00:05. > :00:12.Her law and welcome to the show. Sadly, the last of the series. I am
:00:12. > :00:17.in a blustery Hinkley Point in Somerset, home to three generations
:00:17. > :00:21.of nuclear power station. Over there, you can see Hinkley Point be,
:00:21. > :00:27.which is currently generating power and supplying 1 million homes in
:00:27. > :00:33.the UK. Hinkley Point Bay is being decommissioned. In that empty space
:00:33. > :00:38.behind that is the proposed Hinkley Point C, the new nuclear power
:00:38. > :00:43.station, get to be built, that will generate power for 5 million homes.
:00:43. > :00:47.In March, a group -- the reported on the tsunami which hit Japan
:00:47. > :00:51.resulting in the loss of 15,000 lives, damaging the Fukushima
:00:51. > :00:56.nuclear reactor. It is that incident which came to dominate the
:00:56. > :01:02.headlines. But how much of the science behind those headlines do
:01:02. > :01:07.we understand? Tonight's show, we're going to one of Britain's
:01:07. > :01:11.oldest nuclear sites, to get to that on the issue of what to do
:01:11. > :01:15.with nuclear radioactive waste, Liz looks at the effect of radiation on
:01:15. > :01:19.us for help, and GM gets to the heart of the matter by showing us
:01:19. > :01:23.how a nuclear power station actually works. I am about to do
:01:23. > :01:32.something almost nobody ever gets to do. Goal inside a nuclear
:01:32. > :01:39.reactor. Built inside -- in 1978, this one is almost identical to the
:01:39. > :01:43.Fukushima reactor, except it was never switched on. You walk into a
:01:43. > :01:48.nuclear power plant, you cannot help but be awestruck by the size
:01:48. > :01:56.and apparent complexity of the place. But the truth is, when you
:01:57. > :02:02.get to the heart of the operation it is all surprisingly simple. All
:02:02. > :02:09.of this complex machinery is here to monitor and control the nuclear
:02:09. > :02:15.reaction that he's water and turns it into steam. Once the steam
:02:15. > :02:19.leaves the reactor, you're in the realms of conventional power. Hawke,
:02:19. > :02:24.high-pressure steam comes down to write like this and gets fed into a
:02:24. > :02:29.turbine. There, the technology is not so much nuclear but Victorian -
:02:29. > :02:33.the pressure of the steam pursues the Blades of the turbine, causing
:02:33. > :02:40.us to rotate. That turns a generator, which produces
:02:40. > :02:45.electricity that this plant was built for in the first place. A big
:02:45. > :02:50.problem I find with nuclear power- station as us that this year -- the
:02:50. > :02:56.scale of them makes them confusing. But it boils down to this. You have
:02:56. > :03:00.a nuclear reactor here, it is like a kettle, except the water is not
:03:00. > :03:06.heated by electricity but by nuclear fuel rods. Oil and water
:03:06. > :03:11.produces steam. Steam comes down a pipe and impacts on a turbine,
:03:11. > :03:15.which is essentially a bunch of spoons, on a spindle. That reduces
:03:15. > :03:19.electricity, and you have got yourself a happy town. The thing
:03:19. > :03:24.that makes a nuclear power station different from a conventional one
:03:24. > :03:34.is how the water is heated to form steam. To see that, I have to go
:03:34. > :03:36.
:03:36. > :03:41.This is the heart of a nuclear reactor. Not many people get to
:03:41. > :03:47.stand you, because, when active, all of this would be around 300
:03:47. > :03:52.degrees Celsius. And under a similar pressure that you would
:03:52. > :03:55.find half-a-mile below the ocean, pushing the walls apart with the
:03:55. > :04:05.force of 40,000 tonnes. Where does the energy come from to do that? It
:04:05. > :04:10.
:04:10. > :04:15.These are nuclear fuel assemblies. If operational, this small space
:04:15. > :04:20.would be packed with 100 of these. Each giving out a vast amounts of
:04:20. > :04:25.energy in the form of heat. That is because every one of these square
:04:25. > :04:30.metal tubes would be packed with thousands of little pellets like
:04:30. > :04:35.this, made of uranium oxide, and uranium is very special to us,
:04:36. > :04:39.because it is an atom that we can split. When things break apart,
:04:39. > :04:46.they release the energy stored in whatever was holding them together.
:04:46. > :04:53.It does not matter if that is an atom or stretched elastic band. We
:04:53. > :04:57.are going to come in, split it, and what I end up with, is two smaller,
:04:57. > :05:03.high energy elements flying off in different directions. When that is
:05:03. > :05:07.an atom, they smash into their surroundings, warming things up. No
:05:07. > :05:13.matter how small the scissors, they are not the tool for splitting an
:05:13. > :05:18.atom. To do that you need a small particle called neutrons. When this
:05:18. > :05:25.hits the centre of a uranium atom, it gets absorbed, causing the atom
:05:25. > :05:28.to become unstable, and to split. As well as releasing that energy,
:05:28. > :05:33.you release two or three more neutrons that can fly off into the
:05:33. > :05:38.surroundings, causing more trouble. That is still not really enough to
:05:38. > :05:45.sustain a nuclear reaction. Uranium atoms do not absorb neutrons that
:05:45. > :05:50.easily. Neutrons have to be going at just the right speed, and, for
:05:50. > :05:56.that, this reactor needs one more thing. Just add water. The water
:05:56. > :06:01.plays a pivotal role, because it slows down the neutrons, to a speed
:06:01. > :06:06.where they are more likely to be absorbed by a near banning uranium
:06:06. > :06:12.atoms, causing them to become unstable, releasing more energy and
:06:12. > :06:17.more neutrons in a cascade. If you can keep the sustainable, you have
:06:17. > :06:27.gone critical. Which is a good thing, because, then, you generate
:06:27. > :06:37.
:06:37. > :06:42.heat sufficiently quickly to run a So, what was it that went wrong at
:06:42. > :06:50.the Fukushima reactor? To find out, I headed back to the workshop, for
:06:50. > :06:57.some experimentation. This is pretty much what created those very
:06:57. > :07:02.dramatic explosions. An unfortunate mixture of hydrogen and oxygen
:07:02. > :07:08.coming into contact with something hot. The big difference is, there's
:07:08. > :07:14.involved about 1 million times more hydrogen, and risked splitting more
:07:14. > :07:19.than my eardrums. But, what possible cause of events could have
:07:19. > :07:25.resulted in a nuclear power station is up -- releasing one ton of
:07:25. > :07:32.hydrogen? In the case of Booker shimmer, a massive air quicks
:07:32. > :07:36.struck and all the main power went out. -- earthquake struck. These
:07:36. > :07:40.reactors are fitted with an automatic brake, and in the case of
:07:40. > :07:46.an emergency, neutron absorbing Broads are inserted between the
:07:46. > :07:50.fuel rods, shutting down the main reaction. But the bad news is, you
:07:50. > :07:56.cannot just totally switch of a nuclear reactor, because all the
:07:56. > :07:59.time it had been working, to uranium would have been producing
:07:59. > :08:04.several radioactive by-products which continues plotting and giving
:08:04. > :08:10.of heat, long after the main reaction has been shut off. This is
:08:10. > :08:16.known as decay heat. Even though it is 1.5% of the normal running power
:08:16. > :08:23.of the reactor, it's still equates to about 20 megawatts. That is the
:08:23. > :08:29.equivalent of having 10,000 kettles boiling away in there. Even 10,000
:08:29. > :08:33.kettles were up of heat is not a problem, providing you have plenty
:08:33. > :08:38.of water circulating through the reactor, taking that heat away.
:08:38. > :08:44.Even after the earthquake, the pumps pumping the water were still
:08:44. > :08:47.working fine, running off back-up generators, but then this tsunami
:08:47. > :08:52.hit, wiping out the back-up generators, and the electrical
:08:52. > :08:58.switchgear. This meant there was no water circulating through the
:08:58. > :09:08.reactor, and, just like this cattle, it was beginning to boil dry. --
:09:08. > :09:11.
:09:11. > :09:16.this careful. -- kettle. It just gets hotter and hotter. Soon, in
:09:16. > :09:21.the reactor, the temperature reached 1200 degrees Celsius. At
:09:21. > :09:27.1300 degrees Celsius, something even more serious started to happen.
:09:27. > :09:32.Surrounding uranium fuel pellets is a metal called zirconium. And that
:09:32. > :09:37.is then temperatures, it begins to chemically react with this steam
:09:37. > :09:42.inside the reactor, producing an extremely flammable gas, hydrogen.
:09:42. > :09:46.Now you have got fuel and hydrogen building inside the reactor vessel,
:09:46. > :09:52.and the pressure is increasing dramatically, leaving the engineers
:09:52. > :09:57.with an extremely difficult dilemma. Here is a model we have made to
:09:57. > :10:04.demonstrate the problem. This is my reactor core. I am going to pot
:10:04. > :10:10.that inside my nuclear plant. Inside the model, I have put some
:10:10. > :10:15.reactive metal to simulate zirconium, and, if I add some acid,
:10:15. > :10:19.it will produce hydrogen gas, in much the same way, and I recruited
:10:19. > :10:23.their problem. Already, that is getting dangerously high, which
:10:23. > :10:28.leaves me in a similar position to the Japanese, and I've got to
:10:28. > :10:34.release the pressure now, because the worst-case scenario is, that
:10:34. > :10:38.reactor vessel burst, because of the pressure building up inside it.
:10:38. > :10:42.The workers at Fukushima avoided the worst case scenario, the huge
:10:42. > :10:47.reactor core itself bursting under pressure, spring superheated
:10:47. > :10:53.nuclear material at. But some of the gases released into the chamber
:10:53. > :10:57.flowed back into the building, and created a new danger. That gas is
:10:57. > :11:07.hydrogen, and when it mixes with air, and comes into contact with
:11:07. > :11:20.
:11:20. > :11:25.any kind of spark, you have a Ooh! Dramatic and powerful as a
:11:25. > :11:29.higher rate -- hydrogen explosion is, it is just rapidly burning gas,
:11:29. > :11:35.and it is reassuring to know that even with an horrendous natural
:11:35. > :11:37.disaster, the were enough control measures built into the plant that
:11:37. > :11:43.engineers could stop the excess pressure Breaston the reactor would
:11:43. > :11:51.sell up. The materials used in nuclear power mean that these
:11:51. > :11:55.places can never become a nuclear bombs. This is the beautiful old
:11:55. > :12:00.pink -- Hinkley Point is a control room. It is being closed than now.
:12:00. > :12:05.But that is not the end of the story. Ahead lie years of
:12:06. > :12:10.decommissioning. The reactor core is set to remain on site for the
:12:10. > :12:14.next 100 years. That raises the most contentious issue when we talk
:12:14. > :12:19.about nuclear power, whether it is an ordinary operation like Hinkley
:12:19. > :12:23.Point, or the result of a disaster like Fukushima or Chernobyl, what
:12:23. > :12:29.can we do with the radioactive waste? I went up to the far north
:12:29. > :12:36.of Scotland, to find out. After a tour to five years of service, doom
:12:37. > :12:43.racer that -- nuclear power station was decommissioned in 1994 --
:12:43. > :12:47.Dounreay. Nuclear reactors always produce radioactive waste. That can
:12:47. > :12:52.range from the contents of the reactor core, to anything in the
:12:52. > :12:58.plant that becomes contaminated with radiation. Current figures
:12:58. > :13:05.show that in the UK, we have well over 160,000 tonnes of the staff,
:13:05. > :13:10.and something needs to be done with it. At Boon Rae, at 2.2 billion pan
:13:10. > :13:16.clean-up was under way. But after six years, they are still dealing
:13:16. > :13:20.with the lowest level waste, contaminated paper, rags, and tools
:13:20. > :13:25.which must be steeled -- sealed into steel drums and painstakingly
:13:25. > :13:30.analysed. There is more low-level waste than anything else, and some
:13:30. > :13:36.of it is barely radioactive. Inside the reactor core itself lies a more
:13:36. > :13:42.serious challenge. Where I am walking here below my feet is the
:13:42. > :13:47.reactor. Inside the reactor core, is some very hazardous radioactive
:13:47. > :13:51.material, uranium and plutonium. The big challenge is to get it out
:13:51. > :13:57.and make it said. This final stage of the clean-up is due to start
:13:57. > :14:05.next year. Handling this waste will be so hazardous, they are
:14:05. > :14:11.installing Roberts, ready to do the job run madly. -- robots. --
:14:11. > :14:15.remotely. First, you remove the fuel from the reactor. This
:14:15. > :14:20.sophisticated mast has 14 different tools on it which can cut free the
:14:20. > :14:23.elements in the reactor. It is like a big Swiss Army knife. It is a
:14:23. > :14:29.huge Swiss Army knife that is designed to work remotely and
:14:29. > :14:33.reliably. That gets rid of all the fuel in the system. Once extracted,
:14:33. > :14:38.the pure words are put into a cell containing an automated dismantling
:14:39. > :14:48.robot. For now, the row was practising with pretend fuel rods,
:14:49. > :14:52.
:14:52. > :15:01.but once active, it will handle the It is unlike lie we will put anyone
:15:01. > :15:09.in here again. Another row Bott will transfer the fuel into stain
:15:09. > :15:14.less steel drums. These drums will go into an underground area under
:15:14. > :15:24.controlled conditions and be stored there forever. But at Dounreay the
:15:24. > :15:25.
:15:26. > :15:31.clean up isn't the only challenge. In the 1960s things didn't go to
:15:31. > :15:39.plan and in a series of accidents thousands of particles of waste
:15:39. > :15:44.were flushed into the sea. The task now is to recover as many as
:15:44. > :15:48.possible, one by one. It shouldn't have occurred. We have released
:15:48. > :15:52.radioactive material into the environment and it is now
:15:52. > :15:58.uncontrolled. The risk would be a fish ingesting a particle and
:15:58. > :16:02.getting into the food chain. That was the concern. These particle
:16:02. > :16:06.will be on the sea bed, in the sand. So the fish would have to eat the
:16:06. > :16:10.sand. However there was a possibility that they could get
:16:10. > :16:18.into the food chain and therefore some one could be exposed to it.
:16:18. > :16:24.The parms are tiny fragments 06 spent fuel -- particles. The team
:16:24. > :16:29.used a remotely operated vehicle. The challenge is to scan an area
:16:29. > :16:34.the size of 500 football pitches. As soon as they detect something it
:16:34. > :16:39.will stop and drill down. They will target it and then just drill down,
:16:40. > :16:47.suck up a mixture of sand and water. So it is base clay big vacuum
:16:47. > :16:57.cleaner. Yes. The robot returns to the surface and the canisters of
:16:57. > :17:00.
:17:00. > :17:05.sand are unloaded for screening. So he is going through all the sands.
:17:05. > :17:10.Spreading the sand out and monitoring it. You can hear from
:17:10. > :17:18.that noise that they have found something there. So we divide the
:17:18. > :17:27.sand down, and check each bit to find the particle. It is there!
:17:28. > :17:33.So it is in there. You will monitor 60 hectares wrt of sand. Every
:17:33. > :17:36.grain? Yes with the ROV and any sand that comes back here that
:17:36. > :17:42.again will be monitored to make sure it is clean before it goes
:17:42. > :17:46.back to the sea. The radiation given off by these particles can
:17:46. > :17:51.penetrate human skin. But as the workers never touch it, they're
:17:51. > :17:56.safe. We know about the particles that are out at sea, is there a
:17:56. > :18:02.risk of getting particles here on the beach? In any two week survey
:18:02. > :18:07.we may find two or three. So you are talking three or three
:18:07. > :18:13.individual grains of sands from all of this sand. If somebody came into
:18:13. > :18:18.contact with a particle, on the beach. What would happen to them sh
:18:18. > :18:22.The most likely way come into contact with it is if you got it
:18:23. > :18:27.stuck on your skin. A couple of days later, you would get a
:18:27. > :18:35.reddening on the skin, like a burn and that would heal up. That would
:18:35. > :18:40.be it. But long-term it gives you a risk of developing a cancer. Not
:18:40. > :18:49.that you will, but there is a risk associated with with radiation
:18:49. > :18:53.exposure and cancer. I suppose that is what it comes down how to,
:18:53. > :18:59.however slight a link between cancer and radiation from a reactor
:18:59. > :19:09.like this might be, it is enough understand tpwhroi generate a sense
:19:09. > :19:10.
:19:10. > :19:19.of fear in all of us and of course the press. But we weren't always so
:19:19. > :19:23.nervous of radiation. Once radioactivity was positively
:19:23. > :19:33.celebrated. It was a fashionable label and radioactive water was
:19:33. > :19:51.
:19:51. > :19:56.seen as a cure for all ills. But This footage was taken during the
:19:56. > :20:01.aftermath of the atomic bomb-blast in Japan and the images are
:20:01. > :20:10.unsettling. Not only because they're a reminder of thousands who
:20:10. > :20:17.died, but also because these events started a fear of radioactivity.
:20:17. > :20:20.Since the atom bomb-blast it has been difficult to make a
:20:20. > :20:24.dispassionate assessment of the dangers. But that is what I want to
:20:24. > :20:34.do and wipe the slate clean and find out the truth about the
:20:34. > :20:35.
:20:35. > :20:41.effects of radiation. Jerry Thomas is an expert on the 1986 chorl
:20:41. > :20:47.disaster. I have asked her to put the number of deaths into
:20:47. > :20:53.perspective. -- Chernobyl. Everyone knows about the bombings in Japan.
:20:53. > :20:58.A lot of people died, but most of the population died from the blast
:20:58. > :21:03.injury. Actually only about 15 to 20% of the people who died as a
:21:03. > :21:09.result of the bombs died because of radiation. You're talking about
:21:09. > :21:13.20,000 deaths from radiation. So where do we go? Let's look at
:21:13. > :21:19.something else. This is the figure of people that were killed as a
:21:19. > :21:25.result of a dam burst in China in 1975. The dam was there to provide
:21:26. > :21:34.Hydro Electric power. Does puts it into perspective. Now something
:21:34. > :21:40.that we do to ourselves and this is cigarettes. This is the total death
:21:40. > :21:46.toll for 2009 for lung cancer or the other smoking-related diseases
:21:46. > :21:52.that result in death. Lower down the scale, Jerry says over 2,000
:21:52. > :21:59.people died in road accidents in 2009. But perhaps most surprising
:21:59. > :22:06.is her next figure. How about falling out of bed. 106 people each
:22:06. > :22:11.year fall out of bed. Seriously? Yes. 106 people each year fall out
:22:11. > :22:19.of bed and die as a result. That is desperate, I didn't mean to joke
:22:19. > :22:27.about it. It serve serves to make you paranoid about everything.
:22:27. > :22:33.that is the point, life is risky. So where does Chernobyl fit in?
:22:33. > :22:38.think I might be shocked. I think it will be less than car crashes.
:22:38. > :22:42.You're right. I think this is will be a surprise to you. Somewhere
:22:42. > :22:48.between the number of people who die falling out of bed and the
:22:48. > :22:53.number who die in car crashes. thought it would be closer to 2,000.
:22:53. > :22:57.It is remarkable how much lower the death toll from radiation at
:22:57. > :23:02.Chernobyl is than that in Japan. According to Jerry, that figure
:23:03. > :23:07.includes both the short-term effects of acute radiation sickness
:23:07. > :23:15.and most cancers. So the main thing is not to make the mistake of
:23:15. > :23:18.associate Agnew clear accident to something like an atom bok. The
:23:18. > :23:23.numbers illustrate. Figures suggest that radiation from accidents like
:23:23. > :23:30.Chernobyl is not as worrying as a lot of the media coverage would
:23:30. > :23:40.have us believe. But it can and does kill. And I want to understand
:23:40. > :23:42.
:23:42. > :23:52.how. I'm meeting Dr Susan short to show me who radiation can do. Here
:23:52. > :23:54.
:23:54. > :24:02.they grow human tissue cells and expose them to X-rays. This is the
:24:02. > :24:09.machine. This is the X-ray machine. The beam has energy to irrate yaid
:24:09. > :24:16.-- irradiate the cells. We switch the machine on for various lengths
:24:16. > :24:25.of time. Using sum pls, Susan investigates how radiation damages
:24:25. > :24:33.cells. We have got cells that we were growing in a dish and we have
:24:33. > :24:39.two sets. This is a group of cells that have not had any radiation.
:24:39. > :24:48.Each of the dots is a surviving group of cells. That is a group of
:24:48. > :24:56.cells. Cells growing well. Yes. This is the same cells that have
:24:56. > :25:00.had a dose of X-rays. Just one dose. It is a marked difference. A lot of
:25:00. > :25:07.cells died. The reason X-rays can kill cells, because like the
:25:07. > :25:15.radiation from a power plant, they cause a process called ir
:25:15. > :25:19.yonisation. That is -- Ionisation. That is a lot of energy and it
:25:19. > :25:27.producing electrons and free radicals that can damage other
:25:27. > :25:37.proteins. And it can make its different for the cell to function
:25:37. > :26:13.
:26:13. > :26:18.The X-ray beam comes out of the head 069 -- of the machine.
:26:18. > :26:24.machine limits damage to healthy cells. All cells they touch are
:26:24. > :26:29.affected. But because the machine rotates, healthy cells get just a
:26:29. > :26:36.brief dose and the tumour is repeatedly exposed. So you build up
:26:37. > :26:43.the dose and avoid that? Mind yourself. Chris is incredible. The
:26:43. > :26:47.work of radiotherapists means we're learning more about the effects of
:26:47. > :26:53.radiation on our health. And already lessons learned from
:26:53. > :26:59.Chernobyl have had an astonishing effect on the human cost of Japan's
:26:59. > :27:01.nuclear accident. In Fukushima, what was the death toll? There
:27:01. > :27:06.won't be a death toll from radiation in Fukushima. Because
:27:06. > :27:10.they have done all the right things, they read the book and acted as
:27:10. > :27:15.they should have done. There won't be a death toll in Fukushima and I
:27:15. > :27:24.would be surprised if anybody loses their life as a result of exposure
:27:24. > :27:29.to anything from Fukushima. So I hope we have given you some food
:27:29. > :27:33.for thought. But the bottom line is there are no real easy answers when
:27:33. > :27:36.it comes to discussing nuclear energy. We have all got strong
:27:36. > :27:41.opinions the Government is releasing a report into the future
:27:41. > :27:50.of the UK policy in the next few weeks. We have come to tends of the
:27:50. > :27:54.show and the series. Before we go, look online. Dr Yang has done a
:27:54. > :28:04.film about carbon dates. There a lot about nuclear power and
:28:04. > :28:10.Fukushima. Also the BBC is looking for amateur scientists. Look at
:28:10. > :28:15.that competition. That is its for this series and thank you for
:28:15. > :28:20.joining us. It has been fantastic. A treats before you go. If you're
:28:20. > :28:26.one of the people who haven't seen Bang live, we record a show that we