New Research (I) - Nuclear Power

What is nuclear power?

Nuclear energy is energy in the nucleus of an atom. Atoms are tiny particles that make up every object in the universe. There is enormous energy in the bonds that hold atoms together. Nuclear energy can be used to make electricity. But first the energy must be released. It can be released from atoms in two ways: nuclear fusion and nuclear fission.

In nuclear fission, atoms are split apart to form smaller atoms, releasing energy. Nuclear power plants use nuclear fission to produce electricity. The energy is both heat and light energy. Einstein said that a very small amount of matter contains a very LARGE amount of energy. This energy, when let out slowly, can be harnessed to generate electricity.

A nuclear power plant uses uranium as a "fuel." Uranium is an element that is dug out of the ground many places around the world. It is processed into tiny pellets that are loaded into very long rods that are put into the power plant's reactor.The reaction also creates radioactive material that could hurt people if released, so it is kept in a solid form. This chain reaction gives off heat energy which is used to boil water in the core of the reactor. So, instead of burning a fuel, nuclear power plants use the chain reaction of atoms splitting to change the energy of atoms into heat energy.

In nuclear fusion, energy is released when atoms are combined or fused together to form a larger atom. This is how the sun produces energy. Fusion means joining smaller nuclei (the plural of nucleus) to make a larger nucleus. The sun uses nuclear fusion of hydrogen atoms into helium atoms. This gives off heat and light and other radiation.In the picture to the right, two types of hydrogen atoms, deuterium and tritium, combine to make a helium atom and an extra particle called a neutron.What's better about nuclear fusion is that it creates less radioactive material than fission, and its supply of fuel can last longer than the sun.

How is the heat energy converted into electricity?

Nuclear reactors control the chain reaction and harness the heat. Two main types of nuclear reactor are used to generate electricity:

• heavy water reactors
• light water reactors

Heavy water reactors are fueled by natural uranium encased in fuel channels that run horizontally through a tank containing the heavy water moderator. The moderator slows the neutrons down thereby increasing the chances of fission. The coolant, a separate stream of pressurized heavy water, is pumped through the fuel channels to absorb the heat created by the uranium undergoing fission in the tubes. Once heated to about 300 degrees, the heavy water circulates through a boiler, transferring the heat to ordinary water in a separate circuit. The ordinary water is converted to a flow of high-pressure stream that turns the turbines and generates electricity.

Light-water reactors are power reactors that are cooled and moderated with ordinary water. There are two basic types: the pressurized-water reactor and the boiling-water reactor.

• In pressurized water reactors, high-pressure, high-temperature water removes heat from the core and is then passed to a steam generator. Here the heat is transferred to a stream of water in the generator, causing the water to boil. The steam powers a steam turbine.

• In a boiling-water reactor, water passing through the core boils, and the steam from the reactor is used directly in the power cycle.

The advantages of nuclear power plants include lower fuel costs and the absence of air pollution. In short, nuclear power is energy which is produced with the use of a controlled nuclear reaction.

Links:

1) What is Nuclear Power?

2) Nuclear Energy - Fusion and Fission