Over fifteen percent of the world’s electricity comes from nuclear power. Since its debut as an energy source in the 1950’s, atomic energy has been in and out of fashion but never far from the public consciousness.
History of nuclear power
Initially seen as the technological miracle that would produce electricity so cheaply it would be impossible to measure, faith in atomic energy waned during the 1960’s and 1970’s.
A series of major incidents, including the near melt-down at Three Mile Island, US, in March 1979 and Chernobyl in 1988, further damaged the public profile of nuclear energy. However, over the past decade several factors have combined to once again increase the interest in atomic energy.
Nuclear power an increasingly important energy source
With political acceptance of global warming came public pledges to cut green-house gas emissions. At the same time, Government has realised that much of our power generating infrastructure is old and due to go off-line, and renewable sources such as wind might struggle to fill the energy gap potentially left behind. North Sea oil and gas reserves are running down and the costs of importing these products have risen dramatically.
Nuclear power generation seems like an answer to many of these issues.
It may produce small quantities of highly toxic material (around 0.3% of total nuclear waste) but, crucially, does not produce greenhouse gases. New designs produce far less waste material than their predecessors and the widespread use of this form of power in France, which has 59 nuclear plants providing over 75% of the country’s electricity with a good safety record, suggests that the technology has matured.
Although the construction and clean-up costs are huge, and subject to massive uncertainty, once built, nuclear power may also help reduce our exposure to price hikes or supply problems with imported gas, coal and oil, assuming that supplies of Uranium ore remain available - another subject of widespread debate at the moment .
How nuclear energy works
Nuclear power stations create electricity by turning water into steam which turns a turbine – just like a conventional gas or coal-fired power station. The difference is that nuclear plants use a fairly common metal – uranium – rather than fossil fuels to create the essential heat.
Types of nuclear power plant
There are several different types of nuclear plant, such as the Pressurised water reactor, Gas Cooler Reactor, Light Water Graphite Reactor and Fast Neutron Reactor, but in essence they work in the same way.
Nuclear fission
Uranium atoms are made up of two kinds of isotope: the majority is U238, with less than 1% being the all-important U235. This is fissile – meaning its nucleus splits when bombarded by a neutron – and it this process that creates the chain reaction which is at the heart of atomic energy: splitting U235 atoms release heat and create new neutrons, which then go on to split further U235 atoms, releasing more heat and neutrons.
Controlling the rate of chain-reaction is vital and water, ‘heavy water’ or graphite are used to slow the rate at which neutrons are created. In addition, rods made of neutron absorbing metals such as cadmium, hafnium or boron slide in and out of the reactor to fine-tune the rate of reaction. Huge quantities of water are used for cooling the reactor, one reason nuclear plants are usually located on coasts, and also to create the steam necessary to drive the reactor.
Nuclear fusion - the alternative nuclear process
Scientists and engineers are currently exploring the potential from an alternative nuclear process – fusion. This involves creating very high temperatures and magnetic containment fields in order to join together two small nuclei in order to produce a larger nucleus – and heat. Supporters claim that this process is more efficient and produces less hazardous waste than the established fission method.