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Energy Resources:
Nuclear power

 
 

 

 

 

 

 

 

 

 

 

 

 

 

   

Nuclear power:

Energy from splitting Uranium atoms

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Introduction


Sizewell nuclear power station. (www.sxc.hu/photo/867391)


Nuclear power is generated using Uranium, which is a metal mined in various parts of the world.

The first large-scale nuclear power station opened at Calder Hall in Cumbria, England, in 1956.

Some military ships and submarines have nuclear power plants for engines.

Nuclear power produces around 11% of the world's energy needs, and produces huge amounts of energy from small amounts of fuel, without the pollution that you'd get from burning fossil fuels.


How it works:

The main bit to remember:

Nuclear power stations work in pretty much the same way as fossil fuel-burning stations, except that a "chain reaction" inside a nuclear reactor makes the heat instead.

The reactor uses Uranium rods as fuel, and the heat is generated by nuclear fission: neutrons smash into the nucleus of the uranium atoms, which split roughly in half and release energy in the form of heat.

Carbon dioxide gas or water is pumped through the reactor to take the heat away, this then heats water to make steam.

The steam drives turbines which drive generators.

Video clip: Nuclear reactor

Modern nuclear power stations use the same type of turbines and generators as conventional power stations.

In Britain, nuclear power stations are often built on the coast, and use sea water for cooling the steam ready to be pumped round again. This means that they don't have the huge "cooling towers" seen at other power stations.

The reactor is controlled with "control rods", made of boron, which absorb neutrons. When the rods are lowered into the reactor, they absorb more neutrons and the fission process slows down. To generate more power, the rods are raised and more neutrons can crash into uranium atoms.


More:

Natural uranium is only 0.7% "uranium-235", which is the type of uranium that undergoes fission in this type of reactor.

The rest is U-238, which just sits there getting in the way. Modern reactors use "enriched" uranium fuel, which has a higher proportion of U-235.

The fuel arrives encased in metal tubes, which are lowered into the reactor whilst it's running, using a special crane sealed onto the top of the reactor.

With an AGR or Magnox station, carbon dioxide gas is blown through the reactor to carry the heat away. Carbon dioxide is chosen because it is a very good coolant, able to carry a great deal of heat energy. It also helps to reduce any fire risk in the reactor (it's around 600 degrees Celsius in there) and it doesn't turn into anything nasty (well, nothing long-lived and nasty) when it's bombarded with neutrons.



You have to be very careful about the materials you use to build reactors - some materials will turn into horrible things in that environment. If a piece of metal in the reactor pressure vessel turns brittle and snaps, you're probably in trouble - once the reactor has been built and started you can't go in there to fix anything..

Uranium itself isn't particularly radioactive, so when the fuel rods arrive at the power station they can be handled using thin plastic gloves. A rod can last for several years before it needs replacing.
It's when the "spent" fuel rods are taken out of the reactor that you need the full remote-control robot arms and Homer Simpson equipment.

A fuel rod for a nuclear reactor. By the way, This is a very young Will Darvill (who did some of the graphics for this site).  Aww, bless...

Should I worry about nuclear power?

Nuclear power stations are not atomic bombs waiting to go off, and are not prone to "meltdowns".
There is a lot of U-238 in there slowing things down - you need a high concentration of U-235 to make a bomb.
If the reactor gets too hot, the control rods are lowered in and it cools down.
If that doesn't work, there are sets of emergency control rods that automatically drop in and shut the reactor down completely.


With reactors in the UK, the computers will shut the reactor down automatically if things get out of hand (unless engineers intervene within a set time). At Chernobyl, in Ukraine, they did not have such a sophisticated system, indeed they over-rode the automatic systems they did have. When they got it wrong, the reactor overheated, melted and the excessive pressure blew out the containment system before they could stop it. Then, with the coolant gone, there was a serious fire. Many people lost their lives trying to sort out the mess. A quick web search will tell you more about this, including companies who operate tours of the site.

If something does go wrong in a really big way, much of the world could be affected - some radioactive dust (called "fallout") from the Chernobyl accident landed in the UK. That's travelled a long way.

With AGR reactors (the most common type in Britain) there are additional safety systems, such as flooding the reactor with nitrogen and/or water to absorb all the neutrons - although the water option means that reactor can never be restarted.

So should I worry? I think the answer is "so long as things are being done properly, I don't need to worry too much. The bit that does worry me is the small amount of high-level nuclear waste from power stations. Although there's not much of it, it's very, very dangerous and we have no way to deal with it apart from bury it and wait for a few thousand years...

 Our class at Hinkley Point nuclear power station

There are many different opinions about nuclear power, and it strikes me that most of the people who protest about it don't have any idea what they're talking about. But please make up your own mind, find out as much as you can, and if someone tries to get you to believe their opinion ask yourself "what's in it for them?"


Advantages
  • Nuclear power costs about the same as coal, so it's not expensive to make.

  • Does not produce smoke or carbon dioxide, so it does not contribute to the greenhouse effect.

  • Produces huge amounts of energy from small amounts of fuel.

  • Produces small amounts of waste.

  • Nuclear power is reliable.


Disadvantages
  • Although not much waste is produced, it is very, very dangerous.
    It must be sealed up and buried for many thousands of years to allow the radioactivity to die away.
    For all that time it must be kept safe from earthquakes, flooding, terrorists and everything else. This is difficult.

  • Nuclear power is reliable, but a lot of money has to be spent on safety - if it does go wrong, a nuclear accident can be a major disaster.
    People are increasingly concerned about this - in the 1990's nuclear power was the fastest-growing source of power in much of the world. In 2005 it was the second slowest-growing.

Is it renewable?
Nuclear energy from Uranium is not renewable.
Once we've dug up all the Earth's uranium and used it,
there isn't any more.

Actually, it's not that simple - we can use "fast breeder" reactors to convert uranium into other nuclear fuels whilst also getting the energy from it. There are two types of breeder reactors - ones that make weapons-grade plutonium and ones that are for energy production.

Find out more about breeder reactors...


What about investing in nuclear power?

Written by guest contributor Jennifer Gorton from Forex Traders, July 2010

The rise of global warming concerns throughout the world over the last ten years have led to a renewed interest in what was once considered a dead market—nuclear energy. After the Cold War, nuclear energy development was largely forgotten for many years until this renewed desire among developed nations for alternative energy sources once again thrust the idea of nuclear power into mainstream consciousness. As the price of oil and global warming concerns both continue to rise steadily, a renewed interest in the clean-burning properties of nuclear power are becoming much more attractive.
The nuclear energy market is expected to grow substantially over the next 20 years. In fact, the Department of Energy expects the amount of electricity the U.S. uses to rise 50% by 2030, and worldwide electricity consumption is expected to double by 2030.
This very bullish outlook for the nuclear energy market means there will be increased demand for nuclear energy and this increased demand coincides with a rather weak amount of supply. And of course, basic economics tells us that price increased and decreases in relation to the dynamics of supply and demand. As emerging economies develop over the next 20 years, there will be an enormous spike of demand for low-cost, environmentally-friendly alternative energy sources, and nuclear power is expected to satisfy this demand. Brewin Dolphin is a private client investment manager, and one of their analysts, Nik Stanojevic, recently reported, “Many parts of the developing world are structurally short of power and building large numbers of nuclear power stations; this will lift uranium demand.”
Until the last few years, it has been difficult for the average investor to invest in the nuclear energy market as most investment opportunities were offshore. However, this has changed and now there are several options for the average investors.

1. In 2007, the New York Mercantile Exchange (NYMEX) launched its first futures contract for uranium. This allows investors to speculate in the future movement of uranium. Prices were skyrocketing before the 2008 Global Credit Crisis and uranium was trading in the $140’s/pound, but today price sits in the $40/pound area.

2. Investors can also expose part of their portfolio to potential growth in uranium by investing in companies that are not currently producing uranium, but are, in fact, mining in it. Oftentimes these companies have very low share costs, and if an investor does adequate research and finds a company with competent management that does indeed find uranium deposits, the share prices will inevitably rise sharply.

3. Investors can also invest in companies that do have existing uranium operations such as BHP Billiton and Cameco. These are both very large companies that are proven leaders in the industry. Many smaller companies in uranium-rich countries are investment opportunities as well, but an investor would have to purchase shares on a foreign exchange in order to take advantage of investing in these companies.

4. Investors may consider speaking with a Forex broker on whether the currency of uranium-rich countries are expected to increase.


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