IGCSE Coordinated Science (0654) Energy Resources and Radioactivity 2013

1. Natural Resources
Anything humans use from the Earth is a natural
resource.
A renewable resource is one which can be
replaced at the same rate at which it is used.
Most renewable energy comes from the sun.
In this unit we will look first at how the sun
produces its energy, and then how it is
'recycled' into renewable energy sources and
fossil fuels.

3. Where does the Sun Get Its Energy?
http://commons.wikimedia.org/wiki/File:Celestia_sun.jpg

4. What is it?

The sun has a power of 4*1026 Watts.
-- what fraction of the sun's energy is
needed to meet Japan's extra energy needs
(to replace the nuclear power)?

“The Earth receives more energy from the
sun in one hour than the world's population
uses in a year.”

Why is this misleading (but true)?

5. 1. Write nuclide + + +
symbols for
each atom.
2. How many
different
elements are + + +
shown? + + ++ ++ +
+ + +
3. How many + + + + +
isotopes of
carbon are
there? ____

6. Isotopes of Hydrogen
+ + +
Hydrogen Deuterium Tritium

7. What happened to the Electrons?
These atoms usually have electrons, and in
chemistry these electrons form and break
bonds.
+
e-
e-
+

8. What happened to the Electrons?
These atoms usually have electrons, and in
chemistry these electrons form and break
bonds.
+
e- e-
+

9. e-
+ e-
e-
+ e-
+
++ +
+ e-
+ +
+
e-
e-
e- e-
e-

10. e-
+ e-
e-
+ e-
+
++ +
+ e-
+ +
+
e - e-
e
-
e-
e-

11. Everything Reaction We See is
Around Us is Chemistry (electrons)
e-
e-
e-
e-
e-
http://en.wikipedia.org/wiki/File:2007_Sakura_of_Fukushima-e_007_rotated.jpg

12. Nuclear Physics
Nuclear physics is the study of what happens
inside atoms. Electrons orbiting the nuclei do
not matter in nuclear physics.
e-
e-
+ e-
++
++
++ +
e-
e- -
e e- e-

13. Nuclear Fusion
Nuclear fusion is the joining of atoms together into
larger atoms. It gives even more energy than
nuclear fission (used in nuclear reactors).
Nuclear fusion requires enormous heat and
pressure to occur.
Nuclear fusion powers the sun.
Unfortunately, it requires so much heat it can not
yet be controlled to produce useful energy on
Earth, but it is being developed.“Nuclear fusion
is 50 years away and always will be.”

14. Mass into Energy
In nuclear reactions matter is converted into
energy.
E = energy
m = mass lost
c = the speed of light = 3 * 10 8m/s
Calculate the energy which would be released if
one kilogram was converted to energy.

15. Animation
http://www.atomicarchive.com/Movies/Movie5.shtml

16. Nuclear Fusion
Start:
Number species Mass (individual) Mass
(total)
proton 1.672621777
×10−27 kg
End:
proton
Helium-4 6.64465675
×10−27 kg
Total mass
http://en.wikipedia.org/wiki/File:FusionintheSun.svg
alculate the percentage lost

17. Experimental Fusion Reactor
It is hoped that fusion will provide energy in the future. It
provides much more power than fission, and (apart
from the reactor itself) no nuclear waste.
There is plenty of deuterium and tritium in seawater –
enough for thousands of years. It does not cause
environmental problems extracting it (unlike mining
uranium).
It is impossible to build up the pressure that exists in the
sun, but scientists can suspend the gas in a Tokomak
and heat it to extremely high temperatures, but it
cannot be sustained for long enough (yet) to produce
power.
“Fusion power is 50 years away and always will be.”

18. http://en.wikipedia.org/wiki/File:Homemade_fusion_reactor.JPG

19. GEKKO XII laser (Osaka)
http://en.wikipedia.org/wiki/GEKKO_XII

20. Nuclear Fusion in Warfare

The temperature and pressure required for nuclear fusion have been
created momentarily by using a nuclear explosion to compress
hydrogen. This is known as a hydrogen bomb.

The first H-bomb test was “Ivy Mike”, soon followed by Castle Bravo
on Bikini Atoll. This caused the largest nuclear fallout caused by the
US, including the island's inhabitants and the Daiko Fukuryu Maru.

When Bravo was detonated, it formed a fireball almost four and a half
miles (roughly 7 km) across within a second. This fireball was visible
on Kwajalein atoll over 250 miles (450 km) away. The explosion left a
crater 6,500 feet (2,000 m) in diameter and 250 feet (75 m) in depth.
The mushroom cloud reached a height of 47,000 feet (14 km) and a
diameter of 7 miles (11 km) in about a minute; it then reached a
height of 130,000 feet (40 km) and 62 miles (100 km) in diameter in
less than 10 minutes and was expanding at more than 100 m/s (360
km/h, 224 mph). As a result of the blast, the cloud contaminated
more than seven thousand square miles of the surrounding Pacific
Ocean including some of the surrounding small islands like Rongerik,
Rongelap and Utirik. - WIKIPEDIA

21. Daigo Fukuryū Maru
http://en.wikipedia.org/wiki/File:Daigo_Fukuryu_Maru.jpg

22. The Blast (from the DFM)

The sky on the west lit up like a sunrise. Eight minutes
later the sound of the explosion arrived, with fallout
several hours later. The fallout, fine white flaky dust of
calcined coral with absorbed highly radioactive fission
products, fell on the ship for three hours. The fishermen
scooped it into bags with their bare hands. The dust stuck
to surfaces, bodies and hair; after the radiation sickness
symptoms appeared, the fishermen called it shi no hai
( 死の灰 ?, death ash). The US government refused to
disclose its composition due to "national security", as the
isotopic ratios, namely percentage of uranium-237, could
reveal the nature of the bomb.
--Wikipedia

23. Wind Power
Wind is small but growing source of electricity.
Once installed, wind turbines do minimal
environmental harm. They can kill or harm birds.
Some people dislike them because they claim they
are noisy or unpleasant to look at.
Wind turbines can be placed onshore (on land) or
offshore. Offshore is more expensive, but
produces more wind.
Wind technology is growing rapidly.

24. Fukushima Wind Farm
Wikipedia

25. Solar Energy
Enough energy reaches the sun to power our energy needs. However,
converting it to electricity is difficult and expensive, but it is being
developed.
Photovoltaic solar panels means converting light energy to electricity.
The Japanese government buys electricity from solar panels at a
higher price than normal to encourage people to install them.
Rooftop installations do not require more land, but space is limited and
installation can be difficult and potentially dangerous.
http://commons.wikimedia.org/wiki/File:Solar_panels_on_a_roof.jpg

26. 
Waldpolenz Solar Park, Germany - Wikipedia

27. Solar Farms

Most solar farms use large arrays of
photovoltaic solar panels.

They produce DC, which must be converted to
AC for a national grid.

The energy is free and renewable, however the
production of solar panels is energy-intensive.

The power output is low, and inconsistent.

28. Solar Trackers

A solar tracker can be used to follow the sun
through the sky, to minimise the angle of
incidence.

The extra power output covers more than the
use of the motor (so the power per square
meter increases) but the installation costs
increase.
http://en.wikipedia.org/wiki/File:SolarTrackerRoofView300W200H.jpg

29. Concentrated Solar Power

Concentrated Solar Power uses mirrors to focus
sunlight to produce heat.

The heat usually boils water, and the steam turns
a turbine just as in a thermal power station.

The power output per square metre is lower, but it
is much cheaper to produce.
http://en.wikipedia.org/wiki/File:PS10_solar_power_tower.jpg

30. http://en.wikipedia.org/wiki/File:PS10_solar_power_tower.jpg

31. Solar Water Heating
Solar water heating is more efficient than making
electricity, and could be used much more widely in
Japan, especially in the south.
It is much more efficient to use sunlight to heat water
directly than it is to use it to produce electricity and
use that to heat water.
http://en.wikipedia.org/wiki/Solar_water_heating

32. Biomass is growing fuel to be
burned. Biomass
It is renewable, clean and safe,
however it requires a lot of
time to grow the fuel.
Biofuel is like solar energy, as
sun is needed to grow the fuel,
and the plants are like
batteries.
Increasing use of biomass is
increasing the prices of food
around the world, with
devastating consequences for
the third world – why? http://en.wikipedia.org/wiki/File:Soybeanbus.jpg
http://en.wikipedia.org/wiki/File:%C5%A0palek_na_%C5%A1t%C3%ADp%C3%A1n%C3%AD.jpg

33. Geothermal Energy
Geothermal energy uses heat from within the
Earth to produce heat or electricity.
It is a clean, renewable energy source, but is
only available in some areas. If too much is
used, it runs out of heat.
Geothermal heat comes from heat generated
when the Earth formed and radioactive decay
inside the Earth.
http://www.inforse.org/europe/dieret/Geothermal/binary.gi
f

34. Hydroelectric
Power
http://upload.wikimedia.org/wikipedia/commons/d/d8/Hoover_Dam_Nevada_Luftaufnahme.jpg

35. Hydroelectricity
Hydroelectricity is clean and renewable, and very
reliable if a good dam is built.
Building a dam usually has disastrous effects on
the local ecosystem.
Dams can run out of water if there is not enough
rain. It is also possible for them to run in reverse
and pump water uphill, making a ‘battery’.

36. Banqiao Dam
Banqiao Dam is a huge dam in China. It was built to
survive a ‘1000 year flood’.
It’s power stations produced 18GW, as much electricity as
20 nuclear reactors, or over half of Japan's loss due to
closure of its nuclear power plants.
http://en.wikipedia.org/wiki/Banqiao_Dam

37. Dam Collapse
In 1975 a ‘one in two thousand years’ flood
occurred, producing record levels of rain.
Banqiao Dam collapsed.
The flood waters were 10km wide and 3-7 high,
and wiped out an area of 55km. Official reports
say 26 000 died in the flood and 145 000 from
resulting disease and famine, but unofficial
reports claim up to 230 000.

38. Quick Review
1)How does the sun produce its energy? How is this
different to combustion of hydrogen (eg the 'pop
test'. You should explain Einstein's famous
equation and how it applies here.
2)Could the power (from Q1) be used to produce
energy on Earth? Explain.
3)Explain the difference between solar photovoltaics
and solar water heating.
4)What are biofuels and why does their increasing
use cause devastation in the third world?
5)Explain how hydropower has caused more deaths
than any other type of electricity production.

39. Wave Power

Wave power uses energy from waves to
produce electricity.

The technology is still being developed, but has
potential to generate a lot of electricity (6kW/m).

It is very weather dependent.
http://en.wikipedia.org/wiki/File:Pelamis_at_EMEC.jpg

40. Tidal Power

Tides are caused by the orbit of the moon.

Tidal power has much potential but is currently
not used much.

Tides are predictable, unlike other renewables.

Tidal stream generators are like wind turbines
under water, which are turned by flowing water.

Tidal barrages dam an enclosed area of water
(eg harbour) and capture energy of water
flowing over the dam as the water level drops.

41. http://www.weirdlyodd.com/10-renew
http://montaraventures.com/blog/20

42. Renewable Energy Sources
Energy Source How does the Energy Advantages Disadvantages
Come from the Sun?
Solar
(photovoltaic)
Concentrated
Solar Power
Wind Turbines
Hydroelectricity
Biofuel
Wave generation
Tidal power

43. The Carbon Cycle
View the animation here:
http://upload.wikimedia.org/wikipedia/commons/c/c8/Carbon_Cycle-anim
(It's a free link but slideshare cannot show it)
Note that some carbon is stored as fossil fuels and permanently
removed from the atmosphere.
This reduction continued for millions of years, until humans
discovered fossil fuels and began burning them, returning the
carbon to the atmosphere.

44. Fossil Fuels
Most organisms decay when they die, and return
their carbon to the atmosphere as carbon
dioxide.
Sometimes, dead organisms are buried before
they can decay. Then, over millions of years
they can become fossil fuels. So fossil fuels are
fuels made from dead organisms which lived
long ago.
It has taken billions of years for the Earth to build
up fossil fuels, and we have burned the best
part of them in one hundred years. This is why

45. Fossil Fuels are Life-Changing
http://photos.yis.ac.jp/HS-Sports/2011-2012-Tennis/21180559_9Rqfr4#!
i=1685411294&k=VrnsncZ

46. Coal
If a forest is covered by water or volcanic ash, it
can not decay. It is buried and becomes coal.
Coal is the most abundant fossil fuel and will
probably be the last one to run out. It is also the
worst for the environment.
Coal is often used to produce electricity because
it is the cheapest. It contains toxic heavy metals
which are harmful to the environment and
humans.

47. Petroleum is liquefied
fossil fuels. It is
Petroleum
usually deep
underground, and
pipes must be
drilled down to get
it. If this goes
wrong, it can leak
and be very bad for
the environment.
Petroleum is distilled
in refineries into
petrol/gasoline (for
cars), jet fuel, diesel http://en.wikipedia.org/wiki/File:Oiled_bird_3.jpg

48. Natural Gas
Natural gas is fossil fuels in the form of a gas. It is
mostly used for heating and generating
electricity.
Natural gas is the ‘cleanest’ of fossil fuels. It
produces less carbon dioxide (CO2) and fewer
other pollutants than coal and oil.
Natural gas is difficult to store because it requires
strong cylinders and can cause explosions if not
used safely. Natural gas will probably run out in
our lifetimes, though there is much debate about
when.

49. Climate Change
Burning fossil fuels produces CO2 , which traps in
sunlight, known as the greenhouse effect. The
greenhouse effect causes global warming,
which melts ice caps and causes the sea level
to rise.
Climate change includes increasing numbers of
typhoons, colder winters, hotter summers and
other strange patterns caused by global
warming. Some scientists now believe that
climate change also causes increases in the
number of earthquakes, as weight of the oceans
shifts from the poles to the equator (as ice
melts).

50. Which causes which?

Greenhouse effect, climate change, global
warming

51. http://www.nasa.gov/images/content/60080
http://www.wrd.org/engineering/central-we

52. http://2.bp.blogspot.com/-3zkel7qlvbw/T

53. http://globalwarmingsiren.com/wp-conten

54. Atom
The word atom means indivisible.
Indivisible means it can't be broken down into
more things. Why not?
Is this true for atoms?

55. John Dalton
John Dalton was a British schoolteacher.
He said that atoms:
1. Everything is made of atoms.
2. Atoms of the same element are exactly alike,
and atoms of different elements are different.
3. Atoms join with different atoms to make new
substances.

56. J .J . Thomson
J. J. Thomson was another British
scientist. In 1887 he discovered
electrons.
http://en.wikipedia.org/wiki/File:JJ_Thomson_exp2.png
http://en.wikipedia.org/wiki/File:J.J_Thomson.jpg

57. Plum Pudding Model
J J Thompson
suggested that
electrons were
mixed up in the
atoms like raisins
in a 'plum
pudding'.
http://en.wikipedia.org/wiki/File:Christmas_pudding.JPG

58. Earnest Rutherford
Earnest Rutherford was from Christchurch.
A good image to describe his
experiment can be found here:
http://www.daviddarling.info/encyclopedia/R/

59. Rutherford's Conclusions
1. The atom is mostly empty space.
2. There is a small, dense, nucleus at the centre of
the atom.
The illustration showed that if an atom was the size
of a sports stadium, the nucleus (protons and
neutrons) would be the size of a pinhead in the
centre, and all the rest is empty space.
The alpha particles which travelled through
undeflected showed that it is mostly empty space.
The alpha particles which were deflected or
bounced back showed that the nucleus must be
dense and charged.

60. Bohr's Model
Bohr (Danish) improved Rutherford's Model by
discovering that there are energy levels for
electrons.
Electrons can only be at set energy levels.
They are like rungs on a ladder.
A good diagram can be found here:
http://3.bp.blogspot.com/_DZbDcIFlgfo/TLz1ufvQ5iI/AA

61. Radioactivity
Most small atoms are ‘stable’. They stay together.
Sometimes forces inside large atoms ‘push each
other away’ or change their form very quickly.
This is known as radioactivity.
241
95 Am

62. Beta Radiation
Some atoms emit beta radiation. A beta particle is
an electron which comes from the nucleus. A
neutron becomes a proton and emits an
electron.

63. Beta Decay of Iodine
131 131 0
53 I −− Xe  
54 −1
1. Copy and complete the equation to show what
Carbon-14 decays to when it undergoes beta
decay.
14
6 C

64. Bananas
"Food is radioactive, Bananas more so than most foods
due to their high Potassium content. About 0.01% of
Potassium is K-40, which undergoes beta decay. Write
an equation for potassium undergoing beta decay.
What does it become and is this harmful?"
40
19 K

65. Gamma Rays
Gama rays are electromagnetic radiation with a low
wavelength/high frequency.
They are usually emitted with alpha and beta particles.
http://en.wikipedia.org/wiki/Electromagnetic_spectrum

66. http://en.wikipedia.org/wiki/Electromagnetic_spectrum

67. Ionising Radiation and DNA
Alpha particles stop at paper (or skin) so are harmless outside the body.
Beta and Gama radiation can be more harmful.
"If an alpha emitting radionuclide gets inside us (typically by breathing it
in or consuming it) it is much more dangerous than if it is outside us
because when it is inside us there is nothing to stop the alpha
particles from colliding with our DNA"
"When an alpha particle (or any other ionising radiation) strikes an atom
in our body, it knocks of some of it's electrons. That atom then
participates in a chemical reaction that normally wouldn't take place in
order to get enough electrons to be in a stable chemical configuration.
If these abnormal chemical reactions happen in DNA they can turn off
the genes that tell a cell when to stop growing, which results in
cancer."

68. Half Life
http://www.avon-chemistry.com/nuclear_lec.
After one half life:
1. Half the remaining atoms will have decayed.
2. The 'activity' (number decaying per second) will
halve.
Americium-241 has a half life of 432 years.
Potassium-40 has a half life of 1.3 billion years.
Iodine-131 has a half life of 8 days.
http://www.avon-

69. Use the first two simulations
and answer the following: Half Life
1.What percentage of the
original atoms of carbon-14
or uranium-238 are left after
one half life? Two half lives?
Three half lives?
2. “God does not play dice” -
Albert Einstein.Was he
correct?
3. Why is the computer game
called “Half-life” and what
does the term refer to in the
game?
http://phet.colorado.edu/en/simulation/radioactive

70. Penetration
http://en.wikipedia.org/wiki/File:Alfa_beta_gamma_radiation_penetration.svg

71. Penetration

Alpha particles can only travel a few centimetres
in air, then they ionise the air and stop. They can
be stopped by a piece of paper or skin.

Beta particles can travel through paper but are
stopped by a thin sheet of aluminium.

Gamma rays are very penetrating, but their
intensity can be reduced by thick concrete or
lead.

72. Background Radiation
We naturally receive a small amount of radiation.
Air, water, soil and food all naturally contain
radioactive isotopes. We also receive radiation
from the sun.
The level of background radiation is different for
different parts of the world. More radiation is
received closer to the north and south pole.
Radiation in Tokyo is still much lower than in
many other cities around the world. Why?

73. Detection of Radiation
A Geiger-Muller tube can detect nuclear radiation. It can be
connected to:

A ratemeter, which tells the number of 'counts' per second.
This may be converted to more 'user-friendly' units.

An electronic counter, which counts the total number of
particles detected by the tube.

An amplifier and a loudspeaker, which makes a sound each
time it detects a burst of radiation.

The “Air counter - S” is a device for sale locally (~6000 Yen
at Yodobashi and pharmacies). It gives counts in
microsieverts per hour.

74. Air Counter - S
http://blogs.dion.ne.jp/nonki/arch

75. Contaminated Food & Water
Spinach, milk and other foods from around Fukushima were found to
contain 7.5 times the safety limit for Iodine-131. Iodine 131 has a
half life of 8 days.
1) How long will it take for the radiation levels to drop to the
allowed limit? EITHER give an approximate answer, or use logs.
2) What does Iodine-131 decay to? Is this safe to eat/drink?
3) Is it possible to 'save' the spinach? How about the milk? How?
4) Cesium-137 has a half life of 30 years. Is it possible to 'save'
food contaminated with Cesium?
5) Traces of Iodine were found in Tokyo's drinking water, above the
limit for babies. Why was it not necessary for residents to buy
many months worth of bottled water (assuming the nuclear plant
stopped leaking Iiodine-131)?

76. Bookwork

Pages 185, 187, 189, 193 and 195. For
question 3 on page 193, draw it to the
standards expected by IGCSE Paper 6 exams.

77. Irradiation of Food
Food can be irradiated with gamma rays, though the
process is controversial.

The food is not radioactive.

Microorganisms are killed, so the food lasts longer and
is less likely to cause food poisoning.

Seeds are killed, so they will not germinate during
storage.

It may change some complex chemicals in the food
and destroy important vitamins in the it.

78. Radioactive Tracers

If doctors need to measure how or how quickly
a certain liquid passes through the body (eg
how quickly iodine is moved to the thyroid
gland) a gamma emitter is chosen (why?) and
introduced into the body.

Its movement in the body can be followed by
measuring the number of gamma rays emitted
from different parts of the body (eg the thyroid).

Radioactive isotopes with short half-lives are
used for these purposes – why?

79. Osteoperosis
diagnosis using a
radioactive tracer
http://www.flickr.com/photos/58103504@N05/5837026120/sizes/m/in/photostream/

80. Radiotherapy

Radiotherapy is the use of
gamma rays to penetrate
into the body to kill cancer
cells.

The gamma rays can be
focussed very precisely to
target the cancer cells,
however some other
(healthy) tissue will also
be affected, and this may
cause further cancer in
future. http://en.wikipedia.org/wiki/File:Radiation_therapy.jpg

81. Fission and Radioactivity
We went over these fission reactions as practice at balancing
nuclear equations.
Please note that you are not expected to remember any of
these, but it is important to be able to balance the equation
and use the atomic numbers to determine unknown elements
in the reactions.
http://physics.nayland.school.nz/VisualPhysics/NZ-physics%20HTML

82. Strontium-90

Strontium-90 is a common product of the fission of Uranium-
235, and is very dangerous if released into the environment.
It was found on a rooftop in Yokohama shortly after 3-11.

This process releases three neutrons. Write a nuclear
equation for this process.

Write a nuclear equation for the beta decay of Strontium-90.
http://i1088.photobucket.com/albums/i332/jarphys/Urani

83. Nuclear Fission
Nuclear fission is breaking apart large atoms into
small atoms. It occurs in nuclear reactors and
nuclear bombs.
The smaller atoms created are radioactive,
meaning the give off radiation.
Nuclear energy releases enormous amounts of
energy: one kilogram of uranium yields as much
energy as 2000 Tonnes of coal.

84. Nuclear Fission
Some large atoms can be broken up into smaller
atoms if a neutron hits them. This releases more
neutrons which can cause more atoms to split,
making a chain reaction.

85. Density
Normally, the density of atoms is too small so the
neutrons just escape and no nuclear reaction
occurs.

86. Simulation
http://www.atomicarchive.com/Movies/index.shtml

87. http://clubtroppo.com.au/files/2011/03/GE

88. In a nuclear power plant, a moderator is used to slow
down the neutrons so that they can make more atoms
split. The more moderator there is, the faster the
reaction.
"Control rods absorb neutrons to slow or stop the nuclear
reaction. If the control rods are in too far, more neutrons
are absorbed than are released and the reaction slows.
If the control rods are out too far, the reaction builds
exponentially as more and more neutrons are released
than are absorbed - in old reactors, this can cause the
reactor to overheat which can lead to a "meltdown" and
or a steam explosion.

89. Example
Try This:
http://phet.colorado.edu/en/simulation/nuclear-fission
And then play this:
http://esa21.kennesaw.edu/activities/nukeenergy/nuke.htm
Try to get as much power generated as possible.

90. Chernobyl Accident
Chernobyl is an abandoned city
in the Ukraine, formerly Russia.
The Chernobyl nuclear power
station suffered a steam
explosion (which blew the top of
the reactor and the roof off of
the building) which was
followed a few seconds later by
a second explosion of
approximately 40 GJ.
http://en.wikipedia.org/wiki/File:Chernobyl_Disaster.jpg

91. The Effects of Chernobyl

"The Chernobyl nuclear accident resulted in
under 100 direct deaths – mostly workers at the
plant and "liquidators" – but about 4000 extra
cancer deaths can be expected over time due
to the radioactive contamination of the
environment. Many of these could have been
prevented if the government had given people
stable iodine and promptly evacuated them
from the contaminated area."

92. The Fukushima Nuclear Power Plants
Modern nuclear power plants are designed to automatically shut down in
an earthquake.
Many fission products are still radioactive, so they give out heat even
after the reactor has been shut down. This heat must be removed
from the fuel rods with cooling water otherwise they will melt down.
Electricity is required to pump the water.
The power station was stuck by a tsunami stronger than designed for.
This cut off external power and drowned the backup generators. The
emergency battery power supply was able to keep the cooling water
pumps running for 8 hours but unfortunately another source of
electricity was not made available before the batteries were
completely discharged.
Some new nuclear reactors are designed to use passive means like
convection, conduction and infra-red radiation to remove decay heat
from fuel rods without the need for electricity to run cooling water
pumps.

93. CNN Animation
http://www.youtube.com/watch?v=BdbitRlbLDc

94. Why Fukushima Isn't Chernobyl
The Chernobyl reactor was being used at the time it
exploded, so much more radiation was being produced
and released during the explosion.
The Chernobyl reactor exploded. The Fukushima reactor
(like all in the developed world) has a “containment
vessel” around it which should keep most of the
dangerous radionuclides inside it.
The Japanese government is testing food and telling
everyone what has happened. The Russian didn't want to
admit what had happened, so they didn't do necessary
safety measures. Thousands of cases of thyroid cancer
could have been prevented by giving out iodine.

95. IGCSE Requirements