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Nuclear energy. Interesting facts about nuclear energy

In this article some interesting nuclear energy and nuclear power stations facts are represented

The nucleus of the atom consists of particles called protons and neutrons, held together by powerful attractive forces. When the nucleus is broken to pieces, these forces are released as energy in the form of heat and radiation. In 1932 Sir John Cockcroft and E. T. S. Walton 'split' atoms of lithium by 'bombarding' them with alpha particles from a lump of radium. The alpha particles, being positive electrically, were speeded up by being attracted down metal tubes which were charged negatively. At the bottom of the tubes was placed a piece of lithium metal. This apparatus was one of the first particle accelerators or 'atom smashers'.

Interesting facts about nuclear energy: The cyclotron is a particle accelerator or an atom smasher. It accelerates charged atomic particles to high speeds, and the particles are then made to bombard atoms in a target of a metal or some other substance. The reactions caused give scientists information about the structure of the atom. The particle is injected into the cyclotron at the center of the machine. Electric fields in the dees cause the particle to accelerate. A powerful magnetic field caused by electromagnets situated above and below the dees makes the particle move in a circle. As it increases in speed, it starts to spiral outwards. An electric charge in the electrodes deflects the particle from the dees to hit the target

Interesting facts about nuclear energy: A positively-charged particle is accelerated between the dees towards the negatively-charged dee (1). In the dee (2), it moves at constant speed in a circle. When it again reaches the space between the dees (3), the electric field on the dees is reversed so that the particle is accelerated towards the other dee, which is now negatively charged (4)

Interesting facts about nuclear energy: a more powerful type of accelerator for splitting atoms and studying the energy produced was invented by E. O. Lawrence during the 1930's.

His apparatus, called the cyclotron, used two hollow metal electrodes, each shaped like the letter D. These dees, as they were called, were given alternate positive and negative charges by an alternating current. This exerted a 'push and pull' effect on the particles, which whirled around and around in the dees at ever increasing speeds, finally 'bombarding' the specimen placed at the exit from the dees.

Interesting facts about nuclear energy: The synchrotron is a more powerful particle accelerator. High-energy protons are accelerated to almost the speed of light in a circular tube. The protons are first accelerated in a smaller accelerator and injected into the tube. A radio-frequency oscillator kicks the protons to higher speeds, and an increasing magnetic field produced by rows of magnets around the tube keeps them in a circular path. On the last circuit, the oscillator causes them to be ejected from the tube to hit a target placed nearby

Nuclear power stations facts: In the AGR (advanced gas-cooled reactor), the reactor is cooled by carbon dioxide gas. The hot gas goes to heat exchangers, where the heat turns water into steam. The steam drives turbines to generate electricity. The concrete biological shield protects workers from dangerous radiation

One of the most modern types of atom smashers is the synchrotron. The walls of a circular tube (which can have a diameter of 60 feet or more) are lined with powerful magnets, whose 'field of force' keeps the bombarding particles in the center of the tube. The particles are whirled around the tube at ever increasing speeds by a high frequency alternating current.

The various substances being bombarded in atom smashers give off particles of different kinds, including alpha particles and beta particles, which can then be studied using an apparatus called the bubble chamber. The particles enter a large tank of liquid hydrogen, which 'boils' into a gas along the path taken by the particles as they pass through the liquid. This path can then be seen and photographed as a thin line of hydrogen bubbles.

Interesting facts about nuclear energy:

Nuclear fission occurs when slow neutrons are captured by nuclei of uranium-235. Fast neutrons have to be slowed by a moderator, such as graphite. The nuclei of uranium-235 split to produce nuclei of fission fragments, such as barium and krypton, neutrons and vast amounts of energy as heat

The atoms of certain elements can split by themselves, without the help of bombarding particles in accelerators. The atoms of ur anium, for exam pi e, can do this. U ranium -235 is an isotope that occurs naturally with the commoner uranium-238. If a lump of uranium-235 is larger than a certain 'critical size' all its atoms will split in a fraction of a second and enormous amounts of energy will be given off as an explosion. Uranium-235 is used to make atomic bombs.

This chain reaction, as it is called, can be controlled in a nuclear reactor. A large block of graphite (the kind of carbon used as pencil lead) has holes drilled in it. In these holes are placed
a number of fuel rods which are made of uranium-238 which also contains a small proportion of the 'explosive' atoms of uranium-235. These keep on splitting and giving off energy within the uranium-238 and heat is produced in the graphite block. As the uranium-235 atoms split very fast-moving neutrons are produced. Uranium-238, unfortunately, absorbs fast neutrons, but not slow-moving neutrons. So to keep the 'reaction' going the fast neutrons are slowed down when they pass through the graphite block, which for rather obvious reasons is called a moderator. Now the uranium-238 will not absorb all the neutrons; the rest move about among the other uranium-238 atoms, bombarding them so that they will keep on splitting as a 'controlled' chain reaction.

Nuclear power stations facts: the heat energy produced by this type of reactor can be harnessed in a nuclear power station. Air or carbon dioxide is pumped around the moderator block, is heated, and then passes into a boiler, where the hot gas changes water into steam. The steam is then piped off to drive steam turbines, which in turn drive generators producing electricity. To stop the reactor working, the control rods are fully inserted in the reactor.

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