A nuclear power plant shares many similarities with conventional fossil fuel based power plants with little differences between the two. Both types of plants use energy to heat water to form steam, which then drives turbines to produce electricity. The major difference is the source of that energy. Nuclear plants use fuel called uranium. Uranium is a naturally occurring radioactive element. It is considered a non-renewable resource but, due to its commonality and abundance (it is more common than silver) and the small amount needed to generate electricity, there is little concern about it running out any time soon. Uranium in nature is made up of three isotopes 238U, 235U and 234U. It is 235U that is used for nuclear fission in power plants …show more content…
In 235U atoms, the nucleus, which is composed of protons and neutrons, is unstable. As the nuclei break up, they release neutrons. During nuclear fission, a neutron collides with a 235U atom causing the atom to split into smaller atoms while releasing heat, radiation and more neutrons. These neutrons continue to hit other 235U atoms so that fission continues to occur. This is called a chain reaction. The heat released from the reaction is used to heat water into steam, which in turn is used to generate electricity. The chain reaction occurs inside a controlled environment called a reactor core. A nuclear reactor core is the portion of a nuclear reactor containing the nuclear fuel components where the nuclear reactions take place and the heat is generated. As we mentioned, the fuel is uranium contained in thousands of individual fuel pins. The core also contains structural components, the means to both moderate the neutrons and control the reaction, and the means to transfer the heat from the fuel to where it is required, outside the core. A general diagram of a nuclear reactor is seen …show more content…
What is common to them all is that they produce thermal energy that can be used for its own sake or converted into mechanical energy and ultimately, in the vast majority of cases, into electrical energy. The two most commonly used reactors are a Pressurized Water Reactor, and a Boiling Water Reactor. A Pressurized Water Reactors (also known as PWRs) keep water under pressure so that it heats, but does not boil. This heated water is circulated through tubes in steam generators, allowing the water in the steam generators to turn to steam, which then turns the turbine generator. Water from the reactor and the water that is turned into steam are in separate systems and do not mix. The model for a Pressurized Water Reactor is seen below, We clearly witness in the diagram above that the heated water is circulated through tubes in steam generators, allowing the water in the steam generators to turn to steam, which then turns the turbine generator. But, in a Boiling Water Reactors (also known as BWRs), the water heated by fission actually boils and turns into steam to turn the turbine generator. Nevertheless, in both PWRs and BWRs, the steam is turned back into water and can be used again in the process. This is seen in the diagram