Fission Fusion and Reactive Decay

• Nuclear reactions, including fission, fusion and radioactive decay can be used to generate energy.
• Fission is the splitting of a large nucleus into two smaller nuclei
• Fusion is the joining of two light nuclei into a larger nucleus
• If a neutron hits a large nucleus like U-235, it makes it unstable, and the nucleus splits into two smaller nuclei and neutrons, releasing kinetic energy
• In this way, the neutrons produced by the initial reaction with uranium and the neutron can cause a chain reaction
• Graphite is used as a moderator in fission
• The purpose of a moderator is to absorb some of the kinetic energy of the neutrons to slow them down
• Control rods are either made of boron or cadmium
• The purpose of control rods is to absorb the neutrons and completely remove them from the fission process
• Control rods help adjust the rate of nuclear fission in the reactor
• A reactor vessel is made out of steel and is surrounded by a concrete layer about 5 metres thick
• The concrete prevents any radiation escaping even neutrons
• Nuclear fusion is when isotopes of hydrogen collide at high speed, resulting in a greater mass than before
• Nuclear fusion is the source of energy for stars and our sun
• For nuclear fusion to occur, high temperatures are needed to overcome the repulsive force between the positively charged nuclei of each isotope
• High pressures are also needed to increase the chance of nuclear fusion