Monday, 29 October 2012
Just like any other technology, nuclear plant designs are improved and advanced to ensure that they meet the required safety standards. Current plant designs feature reliable and diverse safety systems and strong physical barriers to prevent incidents that could pose a threat to public health and safety. The same features that safeguard the public and the environment from a radiation release also defend the reactor from outside interference.
The reactor is typically protected by about four feet of steel-reinforced concrete with a thick steel liner, and the reactor vessel is made of steel about 6 inches thick. Steel-reinforced concrete containment structures are designed to withstand the impact of many natural disasters, including hurricanes, tornadoes, earthquakes and floods, as well as airborne objects with a substantial force.
An independent study confirms that the primary structures of a nuclear plant would withstand the impact of a wide-bodied commercial airliner. The Electric Power Research Institute (EPRI) conducted a state-of-the-art computer modeling study on the impact of a Boeing 767 crash. EPRI concluded that typical nuclear plant containment structures—as well as used fuel storage pools and steel and concrete fuel storage containers—would withstand the impact forces and shield the fuel. Multiple layers of physical security, together with high levels of operational performance, protect plant workers, the public and the environment
Wednesday, 24 October 2012
Nuclear power is generated using Uranium, which is a metal mined in various parts of the world.
The first large-scale nuclear power station opened at Calder Hall in Cumbria, England, in 1956. Some military ships and submarines have nuclear power plants for engines. Nuclear power produces around 11% of the world's energy needs, and produces huge amounts of energy from small amounts of fuel, without the pollution that you'd get from burning fossil fuels. Nuclear power stations work in pretty much the same way as fossil fuel-burning stations, except that a "chain reaction" inside a nuclear reactor makes the heat instead. The reactor uses Uranium rods as fuel, and the heat is generated by nuclear fission: neutrons smash into the nucleus of the uranium atoms, which split roughly in half and release energy in the form of heat.
Carbon dioxide gas or water is pumped through the reactor to take the heat away, this then heats water to make steam. The steam drives turbines which drive generators. Modern nuclear power stations use the same type of turbines and generators as conventional power stations.
In Britain, nuclear power stations are often built on the coast, and use sea water for cooling the steam ready to be pumped round again. This means that they don't have the huge "cooling towers" seen at other power stations.
The reactor is controlled with "control rods", made of boron, which absorb neutrons. When the rods are lowered into the reactor, they absorb more neutrons and the fission process slows down. To generate more power, the rods are raised and more neutrons can crash into uranium atoms.