Attraction and separation – nuclear fusion and fission

My dearest friends,

The energy debate is becoming more and more heated. Gear up on knowledge and join the debate!

Here is nuclear fission and fusion explained:

Nuclear fission is the splitting of an atom. An atom is made up of a nucleus, which itself contains positively charged particles called protons and neutral neutrons. Around this “lump” circles negatively charged electrons.

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Fig 1: The atom: The red and blue dots are the neutrons and protons in the nucleus and the gray cloud is where the electrons swirl around.

During induced nuclear fission, the nucleus is split by “shooting” a neutron straight into it. The nucleus then splits into fast moving elements (they differ depending on what starting material you use) that in turn also release neutrons that split other nuclei (plural of nucleus).

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Fig. 2: Nuclear fission of uranium-235

As you see, this results in the famous nuclear-chain-reaction. When the nuclear fuel Uranium-235 (235U) is bombarded with neutrons, gamma radiation is an unfortunate side-product. This is a type of radioactivity that can only be stopped with lead walls.

As the cooling systems function, the reaction-process is controlled and contained. In Fukushima, the cooling-systems failed.

A large amount of energy is also produced and this is the reason why we have nuclear power-plants. The energy heats water that is then through turbines converted to electrical power which can then be used in society. This is why it is completely safe to swim in the hot water outside of reactors. This water was never in contact with any radioactive material at all and is ultra-super-mega-clean.

Unfortunately, it is hard to turn the electricity production up and down, which results in too much energy being produced at night-time since the energy demand is low. This is why it sometimes is sensible for companies with a high electricity demand, such as aluminum plants, to have peak-production at night time.

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Fig. 3: A sad human chapter – the atom bomb.

In nuclear bombs, this process is uncontrolled and is allowed to run its path whatever it may be. In a bomb however, no neutrons is “shot” into the nucleus, but spontaneous fission is used. This happens when a critical mass is reached. In short: when enough of the stuff is there, the fission process starts spontaneously and…. KABOOOOOM!

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Fig. 4: Nuclear fusion on the sun. You might feel the energy on your skin right now. This is power!

Nuclear fusion does not produce radioactive waste and there is no nuclear-chain-reaction that can get out of hand. It would be a clean, good source of energy. So why is it not up and running?
Nuclear fusion is the process that makes the sun shine: hydrogen nuclei and helium is combined to a gigantic KABOOOOOOM! For the process to even start here on Earth, you need a starting-temperature that is hotter than the sun. It is very hard to make two atomic nuclei fuse.
This is why you probably have heard the term “cold fusion”. It is the hope that one day we will be able to use fusion on Earth at low temperatures. It has largely been written off as pseudoscience.

A crazy idea: Why not use the nuclear fusion energy that we already have access to? – The Sun. Perhaps, we should spend that research money on that? Just a thought…

Just a final nerdy comment that is just so cool:
What the outcome the fusion accomplishes has to do with the masses of the nuclei involved: fusion of light nuclei releases energy and the fusion of two heavy nuclei absorbs energy (the opposite holds true for the fission process). Isn’t this just completely über-cool!? Obviously, there are exceptions to this for example during supernovae, but let’s just call them “special circumstances”.

Science Safely!

Dr. Anna of The Imaginarium

Thinks nuclear physics is very exciting

G. Arora and M. Singh (1994). Nuclear Chemistry. Anmol Publications. ISBN81-261-1763-X.
Shultis, J.K. and Faw, R.E. (2002). Fundamentals of nuclear science and engineering. CRC Press. p. 151. ISBN 0-8247-0834-2.”What is Nuclear Fusion?”. NuclearFiles.org. S. Atzeni, J. Meyer-ter-Vehn (2004). “Nuclear fusion reactions”. The Physics of Inertial Fusion (PDF). University of Oxford Press. ISBN 978-0-19-856264-1
Fig. 1: Yzmo (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/)], via Wikimedia Commons; Fig. 3: By Cpl. McCauhey [Public domain], via Wikimedia Commons; Fig. 4: http://commons.wikimedia.org/wiki/File:FusionintheSun.png#filelinks

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