Overview of Nuclear Energy

The main use of nuclear energy is to generate electricity. This is simply a clean and efficient way of boiling water to make steam which drives turbine generators. Except for the reactor itself, a nuclear power station works like most coal or gas-fired power stations. Nuclear energy is best applied to medium and large-scale electricity generation on a continuous basis (ie meeting "base-load" demand). The fuel for it is basically uranium.

Why use nuclear energy to make the steam? Because it is clean, safe, and usually cost-competitive. Originally it was because it was seen as more convenient and probably cheaper than alternatives, fossil fuel such as coal, gas and oil. That was when the technology was first developed for harnessing the power of the atom in a safe and controlled manner, in the 1950s. Since then the question of sustainability has emerged, giving rise to a more sophisticated rationale.

Nuclear energy has distinct environmental advantages over fossil fuels, in that virtually all its wastes are contained and managed - nuclear power stations do not cause any pollution. The fuel for nuclear power is virtually unlimited, considering both geological and technological aspects. That is to say, there is plenty of uranium in the earth's crust and furthermore, well-proven (but not yet fully economic) technology means that we can extract about 60 times as much energy from it as we do today. The safety record of nuclear energy is better than for any major industrial technology.

Nuclear energy supplies over 16% of the world's electricity, more than the world used from all sources in 1960. Today 31 countries use nuclear energy to generate up to three quarters of their electricity, and a substantial number of these depend on it for one quarter to one half of their supply. Some 10,500 reactor years of operational experience have been accumulated since the 1950s by the world's 440 nuclear power reactors (and nuclear reactors powering naval vessels have clocked up a similar amount).

Safety

From the outset, safety of nuclear reactors has been a very high priority in their design and engineering. About one third of the cost of a typical reactor is due to safety systems and structures. The Chernobyl accident in 1986 was a reminder of the importance of this, whereas the Three Mile Island accident in 1979 showed that conventional safety systems work.

At Chernobyl in Ukraine 30 people were killed (mostly by high levels of radiation) and many more injured or adversely affected. This reactor lacked the basic engineering provisions necessary for licensing in most parts of the world (other reactors of that kind still operating have been significantly modified). At Three Mile Island in the USA with a similarly serious malfunction, the effects were contained and no-one suffered any harm or injury.

Economics

Nuclear power reactors are expensive to build but relatively cheap to operate. Their competitiveness economically thus depends on keeping construction to schedule so that capital costs do not blow out, and then operating them at reasonably high capacity over many years. By way of contrast, gas-fired power plants are very cheap and quick to build, but relatively very expensive to operate due to the cost of their fuel. With rising gas prices, and the high cost of moving coal long distances, nuclear plants are generally competitive with both gas and coal in most parts of the world, and becoming more so.

Wastes

Nuclear power produces wastes which are contained and managed, with the cost of this being met by the electricity customer at the time. It does not produce any significant wastes which are dispersed to the environment. It therefore avoids contributing to increased carbon dioxide levels in the atmosphere.

The main wastes produced by "burning" uranium in a nuclear reactor are very hot and radioactive, placing them among the most unpleasant wastes from modern industry. However, these "high-level" nuclear wastes are modest in quantity. Handling and storing them safely is quite straightforward, they simply need to be shielded from human exposure, and cooled. Shielding can be by water, concrete, steel or other dense material, cooling is by air or water. For instance, when spent fuel is removed from a typical reactor, it is done under water and the spent fuel is transferred to a large storage pool where it may remain for up to 50 years.

About 30 kg of spent fuel arises each year in generating enough electricity for about 1000 people in the western world. The management and disposal of these wastes is funded from the time they are generated.

Other radioactive wastes also arise from the nuclear fuel cycle, these have greater volume but are more easily handled and disposed of. One characteristic of all radioactive wastes which distinguishes them from the very mauch larger amount of other industrial wastes is that their radioactivity progressively decays and diminishes. For instance, after 40 years, the spent fuel removed from a reactor has only one thousandth of its initial radioactivity remaining, making it very much easier to handle and dispose of.

Transport of nuclear materials.

Safety is the prime requirement with nuclear transports, particularly those of highly-radioactive spent fuel, and the record is impressive. Shielding, and the security of that shielding in any accident, is the key with any nuclear materials, especially those which are significantly radioactive. There has never been any radiation release from an accident involving such materials. For instance, spent fuel is shipped in large and extremely robust steel casks weighing over 100 tonnes, and each holding only about 6 tonnes of fuel.

Radiation.

Ionising radiation from uranium ores and nuclear wastes is part of our human environment, and always has been so. At high levels it is hazardous, but at low levels it is harmless. Considerable effort is devoted to ensuring that those working with nuclear power are not exposed to harmful levels of radiation from it, and standards for the general public are set about 20 times lower still, well below the levels normally experienced by any of us from natural sources.

Avoiding weapons proliferation.

The initial development of atomic energy during and immediately after the second world war was to produce bombs. An early concern when the atom was harnessed for controlled civil use was that this nuclear power should not enable more countries to acquire nuclear weapons. Through the United Nations, procedures were set up to ensure this, and in fact they have been perhaps the most conspicuous success of that body. No nuclear materials such as uranium from the civil nuclear fuel cycle have ever been diverted to make weapons. In fact today the whole picture is reversed in that a lot of military uranium is being brought into the civil nuclear fuel cycle to make electricity, which is widely seen as a positive development, unimaginable 40 years ago. One tenth of US electricity is made from Russian military warheads.

Other uses

Although this web site focuses on the use of nuclear energy to produce electricity, it is important to note that nuclear energy is also used to produce the radioisotopes used in many parts of our modern world, with health services, industry and even domestic safety very dependent on them. Many homes have smoke detectors which depend on a tiny amount of americium, derived from plutonium made in a nuclear reactor. In the developed countries, about one half of all people will depend on nuclear medicine at some stage of their lives.

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