I have summarised the research into points form for better and easier understanding. Hope that everyone will have a clearer understanding of Nuclear energy, having a basic knowledge about it.

Nuclear Energy

• An energy that is trapped inside each atom. This energy can be released by splitting the large nuclei or combining small nuclei. [1]
• Nuclear energy can be produced naturally or man-made.

For instance, nuclear energy is produced naturally when the Sun and other stars make heat by nuclear reactions. [1]

Nuclear energy can also be man-made, which is what we are touching on in this project. The production requires machines, known as nuclear reactors, which are part of the nuclear power plant. [1]

• Atoms of the elements will undergo either nuclear fission or nuclear fusion.

Nuclear Fission:

• In this process, the nucleus of an atom is split, releasing the energy within it.
• The elements used are uranium, plutonium or thorium. However, uranium is the main fuel for this process as the fission of a uranium atom is able to produce 10 million times of the energy produced by the combustion of a carbon atom from coal. This is also one of the reasons why some countries prefer nuclear energy compared to the burning of coals. [2]
• Different isotopes of uranium are used in nuclear reactions to release different amount of energy, which include U-235 and U-238 isotopes.

The numbers represents the atom’s atomic mass, for instance, U-235 has an atomic mass of 235. [2]

• Between the two isotopes, U-235 is much favoured and used in nuclear fission. This is because when it absorbs a neutron in the reactor, it will split into two atoms of lighter elements and at the same time, emits neutrons. These neutrons emitted by the first reactions will then continue to split other U-235 nuclei. This results in further fission, also known as a chain reaction. Another element which works as well as U-235 is plutonium. [3]

Luckily, the reactions in the reactors are unlikely to cause an explosion. In the reactors, chain reactions occur slower than the chain reactions in a bomb. This makes it easily for the control of the reactions. Besides, certain conditions are absent in the reactors. This will not cause the reactions to turn into a bomb explosion [4]. Control rods and safety systems are also used or turned on to regulate the splitting reactions or shut down the reactors when the power level gets too high. [4]

The two fragments are emitted in a high velocity in the reactions. Once they are absorbed in a fuel rod, a lot of heat is produced. This heat produced is what that powers the power plant. [3] The heat energy is also used to boil water in the core of the reactors. The boiled water is then transported to the heat exchanger, another section of the power plant. It will heat other pipes, filled with water too, to produce steam. In turn, the steam produced will turn a turbine to generate electricity. [4]

• A kilogram of uranium fuel is able to produce as much energy as 5000 tones of burning coal. Hence, nuclear fission is more environmentally-friendly than the burning of coals. [5]
  

Nuclear Fusion:

• In this process, smaller nuclei are joined to make a large nucleus. For instance, the Sun uses nuclear fusion of hydrogen atoms into helium atoms to give off heat and light energy and other radiation. [4]
• Nuclear fusion is better than nuclear fission as it creates less radioactive material than fission. Its supply of fuel is also able to last longer. [4]
• However, this will only happen under very hot conditions.

Advantages of Nuclear Energy:

• According to John McCarthy’s site, reactors that make use of the U-235, in natural uranium, atoms are very likely last for some hundreds of years.

Bernard Cohen (Professor Emeritus of Physics at Pittsburgh University, former president of the Health Physics Society, the main scientific society concerned with radiation safety) has shown that with breeder reactors, humans are able to have plenty of energy for a few billions of year down the road. However, his argument is based on the usage of uranium atoms from the sea.

Others have also pointed out that there is more energy stored within the uranium impurity in coal than the energy that can be released from the burning of coals. Not only that, there is plenty of uranium in granite too. None of these sources is likely to be used in the next thousand years, McCarthy pointed out, as there is plenty of much more cheaply extracted uranium in conventional uranium ores. [6]

Hence, nuclear energy is able to produce electricity for a longer period than coal.

• Although nuclear power plants also need fuel to function, it needs lesser fuel than the plants which burns fossil fuels [1]. A kilogram of uranium fuel is able to produce as much energy as 5000 tones of burning coal. Therefore, it is more effective than the burning of coal. [5]
• Coal burning plants pollute the air by releasing large amount of carbon dioxide into the environment. This further worsens the global warming situation. On the other hand, well-operated nuclear power plants do not release contaminants into the environment. [1]
• Nuclear energy’s technology is also readily available as it does not have to be developed first before it is put to use. [7]
• Nuclear energy produces small amounts of waste, which is considered to be more compact than other sources of producing energy for electrical power. [9]
• Comparing the costs, nuclear energy is cheaper than coal [10],
• Comparing the amount of space needed to accommodate a nuclear plant, it is considerably smaller than other electrical plants on a basis of comparison of the same output of energy. [10]

With all the above advantages, nuclear energy is definitely a better choice than coal burning. It is definitely “greener” than coal burning. However, nuclear energy does have its own negative sides.

Disadvantages of Nuclear Energy:

• However, despite the low cost of nuclear energy, maintaining a nuclear power plant requires large capital cost. This is because a nuclear reactor has to be maintained with great care. The waste products also had be treated carefully before disposal as they are radioactive, posing great harm and danger to the environment if they leak out before being treated carefully. The capital cost also includes containment of the uranium reactions and waste, radioactive waste management, storage systems [9] and safety inspections. The main features of a safety inspection further include the design, construction, operation of a reactor and accident prevention features. [10] According to D. Swain’s article on Associated Content’s website, “nuclear plants cost up to 5 billion dollars, just to build”. [11]
• Although the output of waste is relatively small, it will release harmful radiation when it decays. Besides, there are no methods to get rid of the harmful radiation produced or to speed up the rate of decay to lower the amount of radiation produced.

Hence, the waste has to be disposed carefully, sealed and buried in a safe environment to prevent it from being contaminated by its surroundings or humans. [11]

• One of the serious problems with nuclear reactors is the occurrence of accidents. These accidents are due to the overheating of the core, causing it to meltdown and release harmful radiation out into the environment. Not only does it pollute the environment, it also causes great danger to humans’ health. [11]
• Nuclear reactors can only last for about 40-50 years only. [12]

References:

[1] ThinkQuest (--) Nuclear energy [on-line] http://library.thinkquest.org/3471/nuclear_
energy.html (03-06-08)

[2] John McCarthy (2008) Nuclear Energy is the most certain future source [on-line] http://www-formal.stanford.edu/jmc/progress
/nuclear-faq.html (03-06-08)

[3] John McCarthy (2002) Relevant Very Elementary Physics [on-line] http://www-formal.stanford.edu/jmc/progress
/physics.html (03-06-08)

[4] California Energy Commission (2002) The Energy Story - Chapter 13: Nuclear Energy - Fission and Fusion [on-line] http://www.energyquest.ca.gov/story/chapter
13.html (03-06-08)

[5] Chris Oxlade (2004) 21^st Century Science Energy.
London: Franklin Watts

[6] John McCarthy (2007) Facts from Cohen [on-line]
http://www-formal.stanford.edu/jmc/progress/
cohen.html#cohen (03-06-08)

[7] Time for change (--) Cons and pros of nuclear power | Time for change [on-line] http://timeforchange.org/pros-and-cons-of-
nuclear-power-and-sustainability (04-06-08)

[8] Andy Danill (2008) Energy Resources: Nuclear power [on-line] http://home.clara.net/darvill/altenerg/nuclear.htm (04-06-08)

[9] The Virtual Nuclear Tourist (2005) Why Nuclear Power - Comparisons of Various Energy Sources [on-line]
http://www.nucleartourist.com/basics/why.htm (04-06-08)

[10] Yale-New Haven Teachers Institute (2008) 81.05.02: Nuclear Energy [on-line] http://www.yale.edu/ynhti/curriculum/units/
1981/5/81.05.02.x.html#c (04-06-08)

[11] D. Swain (2007) Disadvantages of Nuclear Energy – Associated Content [on-line] http://www.associatedcontent.com/article/
302902/disadvantages_of_nuclear_energy.html (04-06-08)

[12] Celina Treviño & Omar Alatorre (--)Advantages & Disadvantages of Nuclear Energy [on-line] http://gvctemp18.virtualclassroom.org
/Nenergy/adva.htm (04-06-08)

Kaiqing (7) Harry potter fan!!! :P