Climate Change and Nuclear Power - Nuclear Fission - 2

**This is an essay I have written as part of my Physics degree at Imperial College, London. All rights on its use are reserved.
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This is page 2 of 4. References can be found on page 4
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Nuclear Fission

Nuclear fission operates by splitting large atoms into smaller ones, and using the energy released to generate electricity. This is achieved by firing a neutron into a stable Uranium-235 nucleus to make it an unstable U-236 nucleus, causing it to decay. The amount of energy released is enormous compared with fossil fuels; according to a recent article,

"At the atomic level, the thermal energy released in a fission event is 200MeV, compared with only a few electron-volts produced each time a hydrocarbon molecule is broken down by burning carbon-based fuels. As a result, a single nuclear-reactor fuel pellet just 1cm long can produce the same amount of electricity of 1.5 tonnes of coal."[6]

The energy released by fission is so large because of the ubiquitous E = mc^2, where E is the energy released in the decay, Δm is the change in mass during the decay, and c is the speed of light. The total mass of the fission products is less than the mass of the original parent nucleus. This mass difference is what translates into energy; because of the c^2 term, a tiny mass difference releases a vast amount of energy.

Common fuels for nuclear fission reactors are enriched U-235, which consists of about 5% U-235 [7], and Plutonium-239 which is made from U-238 by neutron capture inside a reactor. [8] When undergoing fission, a U-235 atom is split into Krypton and Barium. Krypton is a noble (and therefore extremely unreactive) gas and is not radioactive, but most isotopes of Barium are. Plutonium is dangerous; the ingestion of only a small amount can increase the risk of cancer due to the emission of alpha particles [9]. The most common fuel in modern reactors is U-235.

Modern Generation III+ reactors will generate between approximately 1100 - 1600MW [10], while each modern wind turbine generates about 1.8MW [11]. At least 600 wind turbines would be required to match the output of one nuclear reactor, assuming the lower end of the predicted nuclear output is actually attained.

The Catch

nuclear power has a desperately poor reputation. Even the word itself has bad connotations, having been linked to weapons of massive destructive power and to certain disasters involving nuclear power in the past. Many arguments exist to claim that nuclear power is too great a risk and that we therefore cannot justify building more nuclear power stations. The most commonly used arguments are those that cite disasters at nuclear reactors. Since there have been so few, the examples commonly cited in the UK are Chernobyl, in the Ukraine, 1986, and Windscale in Cumbria, 1957.

The problem is that it is the opinion of the masses that matters. If the general consensus is that nuclear power is too dangerous then no amount of good intentions from any government will be able to fight the protests of those masses. Common fears of nuclear power include: nuclear material being used for a terrorist attack; people in the vicinity of nuclear power plants becoming ill; or even "another Chernobyl", amongst others.

Of course, many of them are true and do need addressing. It is true that the radiation emitted from nuclear plants can be dangerous if not treated properly. It is true that stringent legislation would be required to ensure that nuclear power stations are run properly. There need to be proper controls in place to make sure nuclear power plants are as safe as they can be, that proper shielding is in place and waste is dealt with appropriately. This is all a problem for legislators. The greatest problem facing the return of nuclear power is the opposition it faces, rather than physical limitations. Once the people start accepting the idea it will become more palatable.

Hype surrounding reactor disasters is also partly to blame. For example, now twenty years on, and despite many thorough investigations into the Chernobyl explosion, the estimated death toll is still in dispute. Greenpeace has accused the International Atomic Energy Agency (IAEA) of manipulating the data, saying

"Greenpeace, today [07/09/2005], accused the International Atomic Energy Agency of deliberately trying to down play the death toll of the Chernobyl accident as part of the nuclear industry's continued attempt to portray itself as an acceptable future energy source." [12]

Greenpeace is an organisation which "acts to change attitudes and behaviour, to protect and conserve the environment and to promote peace...". [13] As such it would seem its members have an obligation to promote technologies which would help prevent climate change, another cause they are fighting for. It is this kind of mixed message which confuses the general population. What are we, the voters of governments who pledge to change things, supposed to think? I would imagine that most simply do not care. The possibility of anything changing seems distant and is not a high priority in the world of bills, work and picking the children up from school.

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