physics P1 (3)

Nuclear power

• 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 in 1956
• Some military ships and submarines have nuclear power plants for engines
• Nuclear fission makes heat to heat water to make steam to steam turns turbines to turbines turn generators to electrical power sent around country
• 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 spilt roughly in half and release energy in the form of heat
• Carbon dioxide gas is pumped through the reactor to take the heat away, and the hot gas 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
• Advantages:
• -nuclear power costs about the same as coal, so its not expensive to make
• -does not produce smoke or carbon dioxide, so it does not contribute to the greenhouse effect
• -produces small amounts of waste
• -nuclear power is reliable
• Disadvantages:
• -although not much waste is produced, it is very, very dangerous
• -it must be sealed up and buried for many years to allow the radioactivity to die away
• -nuclear power is reliable, but a lot of money has to be spent on safety- if it does go wrong, a nuclear accident can be a major disaster
• -people are increasingly concerned about this- in the 1990s nuclear power was the fastest-growing source of power in much of the world
• Now, in 2005 it’s the second slowest-growing

Wave power

• There are several methods of getting energy from waves
• One of them works like a swimming pool wave machine in reverse
• At a swimming pool, air is blown in and out of a chamber beside the pool, which makes the water outside bob up and down, causing waves
• At a wave power station, the waves arriving cause the water in the chamber to rise and fail, which means that air is forced in and out of the hole in the top of the chamber
• We place a turbine in this hole, which is turned by the air rushing in and out
• The turbine turns a generator

Hydroelectric power

• A dam is built to trap water, usually in a valley where there is an existing lake
• Water is allowed to flow through tunnels in the dam, to turn turbines and thus drive generators
• The dam is much thicker at the bottom than at the top, because the pressure of the water increases with dept
• Hydro-electric powers stations can produce a great deal of power very cheaply
• When it was first built, the huge Hoover dam, on the Colorado river, supplied much of the electricity for…