Welcome back to Green World
Today we're talking about nuclear fission. This energy source is quite
controverial, so we're going to be looking at why.
Before we begin, just a quick side note, there are multiple forms of nuclear
power. This post is about nuclear fission. Nuclear decay is rarely used, most
notably in some space missions. Nuclear fusion is currently being researched
by scientists around the world and isn't used for commercial electricity yet.
First, let's explain how nuclear fission actually works. This involves a lot
of complicated chemistry and physics, but I'll do my best to explain it.
Before anything else we need to look at what is in an atom.
In this image, the grey represents negatively charged electrons, which circle
the nucleus (plural: nuclei) in the center. The nucleus (blue and red) is made
up of positively chargerd protons and neutrons (which are neutral). This means
that the nucleus is positive. The protons and neutrons are held together by
nuclear force. Therefore, the nucleus contains a lot of energy. Nuclear
fission is the process of breaking the nucleus up and releasing that energy.
So now that we've got the basic vocabulary covered, we can move on to the
actual process of fission. First a neutron is shot towards a nucleus at a
great speed. The energy in the neutron and the speed that it's moving deforms
the nucleus into a doubled lobed shaped (a bit like a peanut). The gap between
the two lobes grows bigger until it's too big for the nuclear force to hold
the protons and neutrons together. The nucleus breaks into smaller fragments,
consisting of only a couple protons and neutrons each. Two, sometimes three,
neutrons break apart and aren't connected to any protons at all. The
positively charged fragments (due to the protons) repel each other, which
causes the single neutrons to fly off at high speeds. These neutrons then hit
the nuclei from nearby atoms and restart the whole process. The energy
released when the neucleus breaks apart is what we then turn into electricity.
The most commonly stated problem with nuclear fission is the storage and
disposal of by-products. Nuclear waste is split into three categories based on
the level of radiation: low, intermediate and high. 90% of all fission waste
falls has a low radioactive level. 3% of fission waste has a high radioactive
level. These 3% release 95% of total the radioactivity from nulcear fission
plants. However
Harvard University states
on its website, that
".. coal power plants release more radioactive material per kWh into the
environment in the form of coals ash than does waste from a nuclear power
plant under standard shielding protocols." The fatality rates per kWh are higher in fossil feuls than in nuclear
power. This is also due to the dangers of coal mining which we covered
here. There are no CO2 emissions in nuclear power after the power plants have
been constructed, meaning that nuclear power only produces 16kg of CO2 for
every kWh of electricity that is produced, compared to the 820kg CO2 per kWh
released by coal plants.The radioactivity of nuclear waste is reduced to 0.1%
after about 50 years.
Another big problem are the nuclear disasters. Inside a nuclear power plant,
there are all sorts of protective messures such as coolers, etc. Nuclear
disasters occur when something go wrong and it leads to vast amounts of
electromagnetic radiation which has 100 000 times more energy than visible
light! Nuclear disasters often occur after natural disasters such as tsunamis
or earthquakes as these can shut down the protective messures. There is a
cancer risk connected to these disasters. 5 000 thyroid cancer cases have been
connected to the Chernobyl accident in 1986 in Ukraine which left a large
inhabitable zone and caused thousands to evactuate their homes.
We hoped you found this post interesting. It's a very complex discussion and
there are some many more points than we mentioned here. See you next week!
Your Green World Blog Teamš
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