There is a comprehensive discussion of uranium mining on the World Nuclear Association website (http://www. world-nuclear. org/), on which the following discussion is largely based. The first step in the nuclear fuel cycle is the mining of uranium ore. While high grade ores are still available, a significant pro­portion of uranium mining is now carried out by extraction of large volumes of easily accessed low grade ore (grade typically a few hundred ppm U3O8) from open cast mines. Canada, Australia, Kazakhstan, Niger, Russia and Namibia presently produce most of the World’s uranium. World uranium production has increased by almost 50% over the last decade, to over 50000 tonnes in 2009.

As well as the naturally occurring uranium isotopes, 234U, 235U and 238U, uranium ores contain a wide range of other radioisotopes, formed in situ as intermediates in the decay of uranium to stable lead isotopes. These are dominated by the decay products of 238U (see Figure 1). Uranium is extracted from crushed ore by leaching, usually with either sulfuric acid or sodium carbonate solution, then concentrated from the leachate by solvent extraction or ion exchange. Most of the decay product radionuclides (Ra and below) are left in the wastes. Especially where ore grades are low, large volumes of these wastes (‘‘tailings’’) arise and uranium mine wastes are often relatively radio­active. In total, around 940 Mt of tailings have been created.1 These wastes

require careful management to prevent the spread of contamination and associated health risks. A particularly challenging example is the Erzgebirge of eastern Germany (http://www. wise-uranium. org/uwis. html), where 216 000 tonnes of uranium were extracted between 1945 and 1990. These mining activities affected an area of about 100 km2, primarily around five mine sites and two ore processing sites. The wastes included 311 million m3 of waste rock, and a further 178 million m3 of tailings. The tailings covered a total area of almost 600 hectares, to a maximum thickness of 70 m. A 15 year remediation programme, costing around €6 billion and largely now completed, has been required to stabilise and restore the area.