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The first time nuclear energy was used as a power plant was for the submarine USS Nautilus (Launched 1954), also the worlds first nuclear powered vessel.
Further development by Westinghouse made nuclear power plants usable for domestic power generation by the early 1960's.
Advantages
Advantages
- It's powerful, efficient, and reliable. About 28 gram of uranium releases as much energy as produced from 100 metric tons of coal.
- It's cheaper and has a lower fuel cost compared to other sources. The cost of Uranium as a fuel is quite low.
- They produce no carbon or methane emissions, and rarely need to be shut down for maintenance.
Drawbacks
Drawbacks
- Waste is radioactive and difficult to dispose of.
- Large scale accidents, though highly unlikely, can be catastrophic.
- Costs of building, and safely decommissioning are very high.
History
History
Uranium was discovered in 1789 by Martin Klaproth, a German chemist, and named after the planet Uranus. Ionizing radiation was discovered by Wilhelm Rontgen in 1895, by passing an electric current through an evacuated glass tube and producing continuous X-rays. Then in 1896 Henri Becquerel found that pitchblende (an ore containing radium and uranium) caused a photographic plate to darken.
He went on to demonstrate that this was due to beta radiation (electrons) and alpha particles (helium nuclei) being emitted. Paul Villard found a third type of radiation from pitchblende: gamma rays, which were much the same as X-rays. That same year, Pierre and Marie Curie gave the name 'radioactivity' to this phenomenon, and in 1898 isolated polonium and radium from the pitchblende.
There were many more important discoveries after these ones, but these are the basics. In 1932 Cockcroft and Walton produced nuclear transformations, by bombarding an atom with accelerating neutrons. In 1938, Enrico Fermi experiments with atom bombardment, and produces heavier elements from his targets, but also, with uranium, some much lighter ones.
Lise Meitner then explained this by suggesting that the neutron was captured by the nucleus, causing severe vibration leading to the nucleus splitting into two not quite equal parts, releasing lots of energy. This process is known as fission. In 1939, Francis Perrin introduced the concept using the critical mass of uranium to produce a self-sustaining release of energy.
Perrin's group in Paris continued their studies and demonstrated that a chain reaction could be sustained in a uranium-water mixture (the water being used to slow down the neutrons). They also demonstrated the idea of introducing neutron-absorbing material to limit the multiplication of neutrons to control the nuclear reaction. This is the basis for the operation of a nuclear power station.
How it works
How it works
Basically, the splitting of an atom creates a lot of heat. The uranium water mixture stated above, starts to heat. When there's a large amount of reactions occurring, there's enough heat to make superheated steam. The Uranium-water mixture is sealed in a vessel. The control rods, which are a neutron absorbing material, are inserted in the top of this vessel.
The hot Uranium water goes to another vessel, which is filled with water tubes. The Uranium water doesn't directly contact the water in these tubes, but this water is affected by the radiation. The massive amount of heat is transferred, turning the water into superheated steam. The Uranium water goes back to the reactor and is reused. This superheated steam operates the turbine, generating electricity.
The steam exiting the turbine transfers its heat to water in another vessel, and condenses down to be reused. The water from the condenser is now steam, but not affected by radiation, so it can be condensed using the atmosphere. This is where a cooling tower is used. Different types of cooling towers are used in coal and natural gas applications as well, because the turbine bed needs to be cool in order to operate safely and correctly.
The above image details the cooling ports on a turbine bed. It's easy to forget how important cooling systems are in power generation, and even every day life. Steam boilers contain water that is above boiling temperature, but it remains water because it's under pressure.
The fire in the furnace of a power plant boiler is hot enough to melt the boiler, but it doesn't, because the heat energy is being transferred to the water within it. The same goes for nuclear energy, except there is no burning of fuel. When this steam is applied to a massive turbine, it's sure to be destroyed if there is no way to keep it cool. This is where cooling towers come into play.
The steam first goes through a condenser and is turned into water, but it's still very hot. The water is sprayed into the air near the bottom of the cooling tower structure. It's built to allow for a convection like process, cool air coming in at the bottom, removing the heat from the water which rises out the top. This creates a draft within the structure, which cools the water even better. The cold water falls into a basin at the bottom of the structure, and it goes to a holding pond to be reused.
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