Nuclear Reactor - Understanding how it works | Physics Elearnin

nuclear reactor in this video are going to learn about the nuclear reactor nuclear reactors are the modern-day devices extensively used for power generation as the traditional fossil fuels like coal are at the breech of extinction a nuclear reactor is the source of intense heat which is in turn used for generation of power in nuclear power stations its mechanism is similar to that of a furnace in a steam generator the steam is used to drive the turbines of the electric generator system the nuclear reactor consists of three crucial components fuel elements moderator and control rods fuel elements come usually in the shape of thin rods of about one centimeter in diameter and contain fissionable nuclei like uranium-235 or uranium 238 these rods vary a number according to the size of the reactor in large power reactors thousands of fuel elements are placed close to each other this region where these fuel elements are placed is called the reactor core these fuel elements are normally immersed in water which acts as a moderator the objective of a moderator is to slow down the energy neutrons a nuclear reactor which are produced during the nuclear fission process by the fuel elements thermal neutrons which are the neutrons with energy of about 0.04 electron volts are capable of producing fission reaction with uranium-235 during the fission reaction process new neutrons are given out which have energies of about 1 MeV this is 1 mega electron volts these neutrons typically escape from participating in another fission process as they are accompanied by enormous energy release in fact the probability of these neutrons produce another fission reaction is 500 times less than that compared to a thermal Neutron this is where a moderator is extremely useful moderators have the capability to slow down or in other words moderate the speeds of these high-energy neutrons so that they can in turn be used for a chain reaction to trigger multiple fission reactions of other uranium-235 nuclei commonly ordinary or heavy water is used as a moderator in nuclear reactors because of the deuterons present in them which are capable of slowing down the neutrons speed water molecules in the moderator are useful in slowing down the high-energy neutrons which leave the fuel element after nuclear fission these high-energy neutrons collide with water molecules thereby losing out on some energy with every collision and therefore slowing down substantially a new fission reaction can now be triggered using this slow Neutron by striking it with a fuel element the third and most prominent part of a nuclear reactor are the control rods in order to get a steady output of energy from the nuclear reactor every single fission reaction should trigger another fission reaction and ensure the availability of spare neutrons released to trigger the chain reactions by controlling the number of spare neutrons available at any given time the rate of nuclear fission chain reactions can be controlled this control on the fission reaction can be maintained using control rods the main function of the control rods is to absorb any excess or spare Neutron in the moderator in order to prevent any further fission reactions usually such control rods are made of boron or cadmium to increase the rate of fission reactions these rods can be removed from the moderator a steady output of energy can must be maintained by inserting or removing the control rods in the nuclear reactor now that we know the components of a nuclear reactor let's understand the working of a nuclear reactor it's usually enclosed in a shield made of thick concrete walls it can of a reactor core pump and heat exchanger the reactor core and pump are placed in contact with the water which is usually the heat exchanger in these reactors due to the enormous amount of heat released during the fusion reaction the surrounding water gets heated up and changes to steam which is in turn used to turn the turbines so huge heat energy gets converted into electrical energy water is continuously flown in and out of the nuclear reactor using the pump so a nuclear reactor successfully generates nuclear energy from fission reactions

Channel: Elearnin

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Id: 1U6Nzcv9Vws

Length: 4min 51sec (291 seconds)

Published: Tue Apr 23 2013