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Atomic Energy We already looked at ways energy can be expressed and transferred from one form to another Heat Light Sound Electrical Magnetic Mechanical Chemical In-fact, the above forces that we experience every day are really due to four more fundamental forces in nature that operate at the atomic level. Atomic Energy Four fundamental interactions are conventionally recognised: gravitational, electromagnetic, strong nuclear, and weak nuclear. Everyday phenomena of human experience are mediated via gravitation and electromagnetism. The strong interaction, synthesising chemical elements via nuclear fusion within stars, holds together the atom's nucleus, and is released during an atomic bomb's detonation. The weak interaction is involved in radioactive decay. Atomic Energy We get atomic energy from the interaction of ..... The weak nuclear force which causes Alpha , Beta and Gamma radiation. The strong nuclear force that sticks the Protons and neutrons together in the nucleus of the atom. Atomic Energy - Fission If you bust open the nucleus of an atom the energy that was sticking the protons and neutrons together (strong nuclear force), is released and transferred into light and heat. Lots of it! When we bust open the nucleus we call that Fission – To slit into two pieces. The bigger the nucleus the more light and heat. Atomic Energy - Fission The best atoms to use are big fat ones that have lots of Protons and Neutrons in their nucleus and are already a bit unstable. The greater the ratio of Protons to Neutrons the more unstable they are. These nuclei also give of lots of Alpha and Beta radiation. Unfortunately these elements are rare. Most of the really big fat atoms were made in the lab under conditions that you don't find in nature. There are only a couple of elements we can dig up in enough quantity to use as fuel in a nuclear reaction. Atomic Energy - Fuel Uranium 235 One of the only naturally occurring elements that is unstable enough to allow itself to be split. It's nucleus has 92 protons and 143 neutrons. It's found mixed in with Uranium 238, a more common isotope. To make nuclear fuel you have to increase the amount of U235 in the mix. This is called enrichment Atomic Energy - Fission A single neutron is captured and destabilises and already unstable nucleus. Three neutrons are released along with huge amounts of heat and light. It's almost exactly like a game of billiards Atomic energy- fission reaction The Fission Reaction. (Cannon shot) Pack very many U235 atoms in to a small space. Fire off a few random neutrons. Stand back (a long way back) and watch the fun. As each nucleus splits it fires off an additional 3 neutrons that split any U235 atoms that are close by. Lots and lots of heat is given off. Lets look at a Simulation. The Reactor In a nuclear reactor we pack a bunch of uranium metal rods in a can. Between each rod is another rod made of Graphite. They are called control rods. These graphite rods soak up Neutrons. Pull the rods out and these Neutrons that are whizzing around can then smash up the any U235 atoms close by. The reactor core gets hot (critical mass). Generating power Simple really. U235 atoms get smashed up. The core gets hot. We boil some water and turn it into high pressure steam. The high pressure steam turns a turbine wheel which is attached to a generator. Bingo electricity. We have a chain of energy conversion resulting electricity! The chain of energy conversion Nuclear fission (atomic) – High pressure steam (thermal/mechanical) – Rotating Turbine (mechanical) – Generator (mechanical) – Electricity (electromagnetic) Nuclear power plant