Introduction: The science of nuclear power

Before we go any further into the issue of nuclear power, I think it is important to make sure we are all on the same page.

The science of nuclear power can get quite technical, so I am just going to give you a broad overview. Hopefully, after this post, I should be able to discuss most aspects of nuclear science without getting too complicated, any posts in the future that delve a little bit deeper will have extra information supplied with them.

For simplicity’s sake, I will be using ‘nuclear power’ to refer to those techniques that use nuclear fission generate power, I will touch on nuclear fusion in a later blog post. All of the controversy surrounding nuclear power is related to fission, as fusion technology (while much safer and more efficicent) is yet to implemented on an actual commercial scale.

Firstly, nuclear (fission) power at it’s most basic is about generating heat. Like many of our other power generating technologies (coal, natural gas, thermal solar, geothermal), nuclear power generates electricity by turning water into pressurised steam, which is then used to spin a turbine. One of the most commonly associated images of nuclear power is of a cooling tower (just see the header image at the top of this blog), all these towers do is dissipate the heat from the water after it exits the turbines.

But what generates this heat?

Splitting unstable (or radioactive) atoms.

The Canadian Nuclear Safety Commission has a good video that explains what is going on when we talk about radioactivity, check it out:

When we take an unstable isotope of a heavy element, like uranium, and then shoot a lone neutron at it, the nucleus absobs the neutron and then splits into two smaller atoms. This splitting results in the release of an enormous amount of energy. Up to 10 million times the energy release when you burn one atom of carbon fuel(1). With this release of energy comes the release of more neutrons, which can go on to split more atoms of uranium in a chain reaction. This is the process that goes on in a nuclear reactor (1).

In a nuclear reactor, rods made of various materials like silver, hafnium or cadmium are used to control the rate of the reaction by absorbing neutrons(2). This is done so that the reactor doesn’t build up too much heat. Building up too much heat can lead to a meltdown (most famously at the Chernobyl reactor in 1986).

The heat released by the split atoms is used to heat water outside the reactor (this water doesn’t come into contact with any radiation), which is then used to drive a turbine.

The choice of reactor design and the types of atoms used have an impact on the efficicency and relative safety of the fission process. Modern nuclear reactors are much safer than those used in the past (3), and the use of different atoms (like thorium instead of uranium) produces reactions that are potentially much safer (although this is still up for debate) (4).

It may seem like this is a lot of risk for little reward, as well as the attendant risks of storage of nuclear waste. But the amount of energy that comes out of fission as compared to coal or natural gas is astronomical, and with newer technologies, nuclear power continues to be a safe and highly efficient form of energy generation (5). Add to this that there are no new greenhouse gasses released from nuclear power, and it seems like this is a resource we should be exploiting.

Everything I have discussed so far is about human produced nuclear power, but did you know that the Earth has been doing it by itself for two billion years? Check out this video about Earth’s ‘natural’ nuclear reactor ‘Oklo’

Say something controversial.

Matt

References

(1) http://nuclearinfo.net/Nuclearpower/TheScienceOfNuclearPower

(2) http://large.stanford.edu/courses/2011/ph241/grayson1/

(3) http://www.world-nuclear.org/info/Safety-and-Security/Safety-of-Plants/Safety-of-Nuclear-Power-Reactors/

(4) http://www.theguardian.com/environment/2011/jun/23/thorium-nuclear-uranium

(5) http://blogs.wsj.com/numbers/what-is-the-most-efficient-source-of-electricity-1754/

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2 responses to “Introduction: The science of nuclear power

  1. Pingback: Radiophobia | Nuclear power: a complex issue

  2. Pingback: Fusion power: will it be tainted by the history of nuclear fission? | Nuclear power: a complex issue

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