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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Transcript


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

:00:05.:00:12.

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

:00:12.:00:17.

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

:00:17.:00:21.

which is currently generating power and supplying 1 million homes in

:00:21.:00:27.

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

:00:27.:00:33.

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

:00:33.:00:38.

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

:00:38.:00:43.

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

:00:43.:00:47.

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

:00:47.:00:51.

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

:00:51.:00:56.

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

:00:56.:01:02.

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

:01:02.:01:07.

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

:01:07.:01:11.

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

:01:11.:01:15.

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

:01:15.:01:19.

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

:01:19.:01:23.

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

:01:23.:01:32.

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

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

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

:01:43.:01:48.

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

:01:48.:01:56.

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

:01:57.:02:02.

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

:02:02.:02:09.

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

:02:09.:02:15.

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

:02:15.:02:19.

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

:02:19.:02:24.

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

:02:24.:02:29.

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

:02:29.:02:33.

us to rotate. That turns a generator, which produces

:02:33.:02:40.

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

:02:40.:02:45.

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

:02:45.:02:50.

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

:02:50.:02:56.

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

:02:56.:03:00.

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

:03:00.:03:06.

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

:03:06.:03:11.

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

:03:11.:03:15.

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

:03:15.:03:19.

that makes a nuclear power station different from a conventional one

:03:19.:03:24.

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

:03:24.:03:34.
:03:34.:03:36.

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

:03:36.:03:41.

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

:03:41.:03:47.

degrees Celsius. And under a similar pressure that you would

:03:47.:03:52.

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

:03:52.:03:55.

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

:03:55.:04:05.
:04:05.:04:10.

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

:04:10.:04:15.

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

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

:04:20.:04:25.

metal tubes would be packed with thousands of little pellets like

:04:25.:04:30.

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

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

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

:04:39.:04:46.

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

:04:46.:04:53.

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

:04:53.:04:57.

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

:04:57.:05:03.

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

:05:03.:05:07.

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

:05:07.:05:13.

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

:05:13.:05:18.

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

:05:18.:05:25.

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

:05:25.:05:28.

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

:05:28.:05:33.

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

:05:33.:05:38.

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

:05:38.:05:45.

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

:05:45.:05:50.

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

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

:05:56.:06:01.

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

:06:01.:06:06.

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

:06:06.:06:12.

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

:06:12.:06:17.

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

:06:17.:06:27.
:06:27.:06:37.

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

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

:06:42.:06:50.

some experimentation. This is pretty much what created those very

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dramatic explosions. An unfortunate mixture of hydrogen and oxygen

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

:07:02.:07:08.

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

:07:08.:07:14.

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

:07:14.:07:19.

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

:07:19.:07:25.

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

:07:25.:07:32.

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

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

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an emergency, neutron absorbing Broads are inserted between the

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

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

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

:07:56.:07:59.

several radioactive by-products which continues plotting and giving

:07:59.:08:04.

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

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

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

:08:16.:08:23.

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

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

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

:08:33.:08:38.

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

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

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

:08:47.:08:52.

switchgear. This meant there was no water circulating through the

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

:08:58.:09:08.
:09:08.:09:11.

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

:09:11.:09:16.

the reactor, the temperature reached 1200 degrees Celsius. At

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

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

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

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

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

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and the pressure is increasing dramatically, leaving the engineers

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

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

:09:57.:10:04.

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

:10:04.:10:10.

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

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

:10:15.:10:19.

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

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

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

:10:28.:10:34.

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

:10:34.:10:38.

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

:10:38.:10:42.

reactor core itself bursting under pressure, spring superheated

:10:42.:10:47.

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

:10:47.:10:53.

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

:10:53.:10:57.

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

:10:57.:11:07.
:11:07.:11:20.

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

:11:20.:11:25.

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

:11:25.:11:29.

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

:11:29.:11:35.

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

:11:35.:11:37.

engineers could stop the excess pressure Breaston the reactor would

:11:37.:11:43.

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

:11:43.:11:51.

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

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

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

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

:12:06.:12:10.

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

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

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

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

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

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

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Dounreay. Nuclear reactors always produce radioactive waste. That can

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

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plant that becomes contaminated with radiation. Current figures

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

:12:58.:13:05.

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

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

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

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

:13:20.:13:25.

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

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

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

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

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

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

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

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

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

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

:14:15.:14:20.

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

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huge Swiss Army knife that is designed to work remotely and

:14:23.:14:29.

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

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

:14:33.:14:38.

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

:14:39.:14:48.
:14:49.:14:52.

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

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

:15:01.:15:09.

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

:15:09.:15:14.

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

:15:14.:15:24.
:15:24.:15:25.

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

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

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

:15:39.:15:44.

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

:15:44.:15:48.

radioactive material into the environment and it is now

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

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

:15:58.:16:02.

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

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sand. However there was a possibility that they could get

:16:06.:16:10.

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

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

:16:18.:16:24.

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

:16:24.:16:29.

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

:16:29.:16:34.

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

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

:16:40.:16:47.

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

:16:47.:16:57.
:16:57.:17:00.

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

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

:17:05.:17:10.

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

:17:10.:17:18.

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

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

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

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

:17:36.:17:42.

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

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

:17:46.:17:51.

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

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

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

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

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

:18:13.:18:18.

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

:18:18.:18:22.

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

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

:18:27.:18:35.

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

:18:35.:18:40.

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

:18:40.:18:49.

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

:18:49.:18:53.

however slight a link between cancer and radiation from a reactor

:18:53.:18:59.

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

:18:59.:19:09.
:19:09.:19:10.

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

:19:10.:19:19.

nervous of radiation. Once radioactivity was positively

:19:19.:19:23.

celebrated. It was a fashionable label and radioactive water was

:19:23.:19:33.
:19:33.:19:51.

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

:19:51.:19:56.

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

:19:56.:20:01.

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

:20:01.:20:10.

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

:20:10.:20:17.

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

:20:17.:20:20.

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

:20:20.:20:24.

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

:20:24.:20:34.
:20:34.:20:35.

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

:20:35.:20:41.

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

:20:41.:20:47.

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

:20:47.:20:53.

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

:20:53.:20:58.

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

:20:58.:21:03.

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

:21:03.:21:09.

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

:21:09.:21:13.

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

:21:13.:21:19.

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

:21:19.:21:25.

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

:21:26.:21:34.

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

:21:34.:21:40.

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

:21:40.:21:46.

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

:21:46.:21:52.

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

:21:52.:21:59.

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

:21:59.:22:06.

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

:22:06.:22:11.

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

:22:11.:22:19.

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

:22:19.:22:27.

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

:22:27.:22:33.

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

:22:33.:22:38.

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

:22:38.:22:42.

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

:22:42.:22:48.

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

:22:48.:22:53.

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

:22:53.:22:57.

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

:22:57.:23:02.

includes both the short-term effects of acute radiation sickness

:23:03.:23:07.

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

:23:07.:23:15.

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

:23:15.:23:18.

numbers illustrate. Figures suggest that radiation from accidents like

:23:18.:23:23.

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

:23:23.:23:30.

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

:23:30.:23:40.
:23:40.:23:42.

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

:23:42.:23:52.
:23:52.:23:54.

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

:23:54.:24:02.

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

:24:02.:24:09.

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

:24:09.:24:16.

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

:24:16.:24:25.

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

:24:25.:24:33.

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

:24:33.:24:39.

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

:24:39.:24:48.

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

:24:48.:24:56.

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

:24:56.:25:00.

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

:25:00.:25:07.

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

:25:07.:25:15.

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

:25:15.:25:19.

producing electrons and free radicals that can damage other

:25:19.:25:27.

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

:25:27.:25:37.
:25:37.:26:13.

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

:26:13.:26:18.

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

:26:18.:26:24.

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

:26:24.:26:29.

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

:26:29.:26:36.

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

:26:37.:26:43.

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

:26:43.:26:47.

radiation on our health. And already lessons learned from

:26:47.:26:53.

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

:26:53.:26:59.

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

:26:59.:27:01.

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

:27:01.:27:06.

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

:27:06.:27:10.

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

:27:10.:27:15.

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

:27:15.:27:24.

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

:27:24.:27:29.

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

:27:29.:27:33.

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

:27:33.:27:36.

opinions the Government is releasing a report into the future

:27:36.:27:41.

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

:27:41.:27:50.

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

:27:50.:27:54.

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

:27:54.:28:04.

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

:28:04.:28:10.

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

:28:10.:28:15.

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

:28:15.:28:20.

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

:28:20.:28:26.

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.