Nuclear fission       Nuclear fission occurs when the nucleus of an unstable uranium absorbs a slow moving        neutron and splits into two smaller nuclei, roughly equal in size and 2 or 3 neutrons.      The two smaller released nuclei are radioactive.      The amount of energy released during nuclear fission is about a million times bigger than          the energy released in a chemical reaction.                                            Nuclear Power Stations        Electricity is generated in nuclear power stations by using the process of fission.      Neutrons are fired at fuel rods that contain uranium-235.      The process of nuclear fission takes place and new neutrons are released.      The neutrons released create a chain reaction, they are absorbed by uranium and the process         repeats itself as long as there are enough uranium atoms.      The way to control the rate of fission reactions is by using control rods that absorb released         neutrons.      The energy released from nuclear fissions is transferred as heat to a coolant (water or          carbon dioxide).      The hot coolant turns water into steam.    Nuclear waste    Nuclear waste is radioactive.     The three types of nuclear waste are categorised as low level, intermediate level and high level.    Disposal methods of nuclear waste depend on their level: Low level Intermediate level High level  Packed in drums  and dumped in a   lined landfill site.  Mixed with  concrete and  stored in stainless  steel containers.  Very difficult to  store as the  radiation damages  the container.