Updated 18 June 2008

What is 'half-life'?
Half-life is the time taken by a radioactive material for half of its radioactive particles to decay, and thus for it to lose half its radioactivity. Eventually all radioactive wastes decay into non-radioactive elements.

The more radioactive an isotope is, the faster it decays. Obviously, for any given amount of radiation, the faster it decays (i.e. the shorter its half-life) the higher the radiation of any nearby person or object will be in a given period.

Radionuclides with long half-life tend to emit alpha and beta radiation, whilst those with short half-lives tend to emit the much more dangerous gamma radiation.


How can you deal with the high-level waste?
Exploration and mining do not generate high-level radioactive waste. However enrichment and use in nuclear power generation does produce about 3 cubic metres of vitrified high-level waste per year for a typical large reactor.

The radioactivity of the waste falls sharply in the first 25 years to about 5% of the radiation levels it had when removed from the power plant. It is stored under water at the power plant for 50-60 years, until the radioactivity has fallen to about 1%, when it can be removed to long-term storage. Such facilities have been in use by the military for years, and are now being constructed to take waste from power plants.



There has been considerable research over the last 30 years on safe long-term storage and disposal methods for radioactive waste, from all sources including medical and power generation.


What is uranium?
Uranium is the heaviest naturally occurring element. It occurs in most rocks in concentrations of 2 to 4 parts per million and is as common in the earth's crust as tin, tungsten and molybdenum. It is 40 times more abundant than silver. It is also found in the oceans, at an average concentration of 1.3 parts per billion. As uranium decays (or radiates its energy), it breaks down to other elements, finally becoming lead. This naturally occurring radiation is what makes the Earth hot in the centre.
Uranium most commonly occurs in nature as a compound with oxygen, as U₃O₈. Like all radioactive isotopes, it decays. U²³⁸ decays very slowly, its half-life being the same as the age of the earth. This means that it is barely radioactive, less so than many other isotopes in rocks and sand.


What is uranium enrichment?
Uranium in nature occurs as several ‘isotopes’, in a fixed ratio of about 99.3% U²³⁸ and 0.7% U²³⁵, with tiny quantities of rarer isotopes. To be used in most nuclear reactors the proportion of U²³⁵ has to be increased to about 3.5 - 4%. This is done by gaseous diffusion or by centrifugal separation, relying on the slightly different physical properties of the two isotopes. In order to be used in nuclear weapons, the U²³⁵ isotope has to be concentrated to about 90%, and this can only be achieved in specialized enrichment facilities.

Most commercial uranium enrichment is carried out in USA, Canada, France, UK, Netherlands and Russia.


Why should we use nuclear power rather than wind or solar power generation?
Both wind and solar energy are seen as valuable and ongoing contributors to power generation.

However they are not viable for base load power supply for a number of reasons, including the variability of both sun and wind, and cost. They also have very large power and material 'costs' for production of the solar panels or wind turbines.


Is uranium a 'cleaner' source of power than coal?
World consumption of coal for power generation each year is reported to be about 2,500,000,000 tonnes (2.5 billion tonnes). The same amount of power can be generated using about 155,000 tonnes of U₃O₈, which would produce virtually no greenhouse gas emissions and about 750 tonnes of high-level radioactive waste.

The coal consumed to create the same amount of power would produce about 5.2 billion tonnes of carbon dioxide, and large quantities of sulphur dioxide and fly ash containing toxic elements such as arsenic, mercury and uranium.

In addition the area disturbed by mining of these quantities of coal is much larger, and the necessary transport and handling facilities consume large quantities of power and affect large areas.

These and other reasons are behind the support expressed for nuclear power over coal generated power by eminent environmentalists.


Is there a safe level of radiation?
All organisms on the planet have evolved in the presence of low levels of uranium and radiation.

It is possible that evolution itself has been partly effected by mutations caused by the continuing low levels of radiation from the natural environment.

Uranium is a common element in trace quantities in ocean water, rocks, and other materials such as coal. We experience radiation from nearby nuclear reactions such as the sun, which causes radiation burns if the skin is over-exposed.

This is not to suggest that higher levels of radiation exposure are harmless. As with other dangerous or toxic elements such as arsenic, cadmium, and lead, uranium is a natural part of the planetary environment but care must be taken to avoid increased levels.


How Much Power Does Uranium Produce?
World consumption of coal for power generation each year is reported to be about 2.5 billion tonnes. The same amount of power can be generated using about 155,000 tonnes of U₃O₈ , which would produce virtually no greenhouse gas emissions and about 750 tonnes of high-level radioactive waste.

The World Nuclear Association has stated that every 22 tonnes of uranium used saves one million tonnes of carbon dioxide discharged from burning coal.