The energy contained in the nucleus of atoms was discovered in the first half of the 20th century. As early as the 1930s there were warnings that releasing it would be dangerous to life. During the second world war an international team headed by American and British scientists produced the first explosions based on an uncontrolled nuclear reaction. Two of these were used on Japanese cities in July and August 1945.

Following the second world war other powers acquired the means to make these bombs, first the fission bomb using Uranium or Plutonium, later the fusion bomb using Lithium and heavy hydrogen (Deuterium).

The essential substance for these weapons was plutonium which does not exist in the natural world. It can only be produced by the action of neutrons on uranium. The military powers therefore had to build industrial plants to produce plutonium for bombs. In the 1950s these were sold to the public as nuclear power stations producing electricity. It was claimed that the electricity would be "too cheap to meter" . However, the cost of electricity was in fact subsidized by the military uses of the plutonium, alleged to be a "by-product" . By the 1980s it was shown that the cost of electricity from nuclear power stations was much higher than from conventional coal and oil burning stations, especially if the cost of dismantling was taken into account. Moreover, no method of safe dismantling was actually known.

In addition there were persistent reports of higher levels of leukemia and other cancers in the areas round power stations and processing factories. A world wide rise in cancer incidence followed the testing of nuclear weapons in the atmosphere in the 1950s. These tests spread radioactivity throughout the world and increased disease incidence everywhere. A Partial Test Ban treaty did not stop testing but confined it to underground sites. Nevertheless gaseous radioactivity continues to escape from the underground tests.

Other rises in cancers and deaths of unknown causes followed nuclear accidents to power stations at Three Mile Island in Pennsylvania and Chernobyl in the Ukraine.

Several parts of the world have accumulated high levels of radioactivity such that at some time in the future they may be regarded as uninhabitable. These include:

Pacific Islands near the American atmospheric testing grounds of Eniwetok and Bikini; parts of South and Western Australia where Britain tested weapons; parts of French Polynesia where France tested weapons;

Parts of Kazakhstan near Semipalatinsk in the Soviet Union where many of the inhabitants were irradiated during tests; Novaya Zemlya where much of the former Soviet Union's nuclear navy is beached or dumped, the sea off Norway where the Komsomolets foundered with several nuclear weapons aboard in an increasingly dangerous condition.

Parts of Utah and New Mexico in the United States near testing grounds; Massachusetts Bay (where radioactive waste was disposed of for many years (1945-59));

Parts of the Urals near Kshytim and Chelyabinsk during the early work on the Soviet nuclear weapons where an explosion of nuclear waste occurred in the 1950s: this is estimated to have allowed 20 times the amount of radioactivity to escape as at the later Chernobyl. Many people are believed to have died;

the area around Chernobyl including large parts of the Ukraine, Belarus, eastern Europe and pockets of western Europe including parts of Snowdonia and the Scottish Border country, following the most serious nuclear accident in 1987 (estimated early deaths by 1991 -10,000 plus with perhaps millions to come).

A British consultancy has already recommended that the city of Kiev (3,000,000 inhabitants) be evacuated and abandoned. It is unlikely to be implemented.

Chinese testing grounds at Lop Nor in the Far West

The Cumbrian Coast and Irish Sea following uncontrolled emissions of radioactive substances including large amounts of Plutonium (estimated 500kg) into the sea from Sellafield processing plant. This affects the whole northwest coastal zone of the United Kingdom.

Some areas of Washington State near military processing plants;

Areas near India's nuclear centers and power plants;

A plane containing nuclear weapons crashed on Greenland in the 1950s scattering plutonium over a large area; the area remains radioactive, though largely uninhabited (which will be released when the ice melts); and many others

All these sites will remain dangerous for a period into the future of at least 20,000 years - equal to half the past history of conscious humanity.

The Russian designed nuclear power stations of eastern Europe, and especially the station at Kosloduy in Bulgaria are a potential danger. Others are those in Czech Republic and Bohunice in Slovakia (near Bratislava and Wien) and Poland. The UN believes all the Soviet reactors are unsafe. In Yugoslavia a war has been taking place near nuclear stations.

The collapse of the Soviet Union has released on to the clandestine world market a quantity of plutonium and Uranium 235, giving rise to fears of terrorists and others making use of it. There are also large numbers of unemployed nuclear scientists who may be tempted to work for "rogue" governments. South Africa is another source.

The earthquake and Tsunami in northern Japan in early 2011 damaged some nuclear power stations and released radioactivity into the local environment. It seems likely that the farms and cities in the area will not be inhabitable for decades.

It would seem to be sensible to build no more nuclear installations of any kind and close down the existing ones as soon as possible. (But the urgencies of Climate Change may make nuclear power a necessary component of the energy supply in order to shut down and oil and coal as fast as possible - the lesser evil)

There is no present or foreseeable technology which can put the radioactive substances back where they came from.

In the future, even when existing nuclear activities have been closed down, there will be areas of the earth's surface which will have to be evacuated. All existing nuclear sites may remain uninhabitable and unusable for agriculture. (If the loss of rent for agriculture for thousands of years from each site could be calculated and added to the cost of electricity, they would be seen to be impossibly expensive).

However, in all industrial countries there seems to be a large lobby of people irrationally attached to this dangerous technology. These people were well-funded during the nuclear arms race (not ended even now) and still advocate more nuclear power stations, though it is now impossible to get non-government finance to build them. Ordinary banks cannot finance them. The insurance cost alone is prohibitive as it would be impossible to meet the real costs of an accident.

Some countries, such as France, Czech Republic and Slovakia and the Soviet Union have become dependent on nuclear power for much of their electricity needs. These countries may need external aid if the nuclear power stations are to be closed down quickly. East German stations were closed soon after German unification; other equally dangerous nuclear stations of the same bad design remain in operation in Czech Slovakia, Hungary, Bulgaria, Yugoslavia and the Soviet Union. Germany had the resources to replace them with gas turbines and surplus capacity in the west German network; the others have no access to western technology (or can't afford it).

A similar investment in solar power using the fusion reactor that is the Sun would seem to be a more sensible solution to the shortage of energy than to increase the number of fission reactors or attempt the building of fusion reactors on earth.

It is to be hoped that there will be no further use or construction of nuclear weapons which would damage both the user and the "enemy" . Their only legitimate use might be the defense against asteroids, but non-nuclear means might well prove to be effective for this.

The Club of Rome would prefer to do without nuclear power but admit that it might be necessary to keep the possibility in case solar developments occur too late to replace fossil carbon fuels when climate changes are causing a panic (after having delayed the controls on oil and coal until climate change will already be causing serious problems).