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3.3 Uranium production and economics

Table 3 lists the major uranium-producing countries. Currently, Canada (with 29% of global supply in 2003) is the world's largest producer of uranium, followed by Australia (21%), both having increased production since about 1980, whereas production from the USA, France, and South Africa has declined (
Author(s): The Open University

3.2 Uranium occurrence and ore deposits

In igneous rocks, uranium is more abundant in granites (~3.5 ppm) than in basalts (~1 ppm). The large size of the uranium atom prevents it from easily entering the structures of common rock-forming minerals, so it is an incompatible element that tends to remain in magmas until a late stage of crystallisation, when it enters minor minerals, or even the uranium oxide, uraninite (UO2). In suitable circumstances, following fractional crystallisation of uranium-rich granitic magm
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3.1 Introduction

Just how readily available are uranium resources, and do their distribution and cost impose restrictions on nuclear power generation? Compared to a coal-fired power station a nuclear power station requires far less fuel in terms of mass. You have seen that a 1 GW burner reactor requires 5000 t of natural uranium over 30 years, whereas a comparable modern coal-fired power station needs 10 000 t of coal every day. However, uranium does not occur naturally in metallic form, nor in the concentrat
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2.5 The growth, decline and future of nuclear power

The Calder Hall Magnox reactor near Sellafield fired the UK's first commercial nuclear power station in 1956, and launched an early UK lead in global nuclear developments. By 1960 six commercial reactors were operating, and Magnox technology had been exported to Italy and Japan. The UK Magnox building programme was complete in 1971 with eleven stations, each producing between 245 MW and 840 MW. Author(s): The Open University

2.3.2 Fast breeder reactors

If fast neutrons produced in the chain reactions are not moderated or absorbed, the rate of conversion of uranium-238 into plutonium-239 (Equation 3) can exceed the fission rate of plutonium-239. Reactors that use fast neutrons in this way are called fast breeder reactors.

Their main fuel is
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2.3 Nuclear reactors

A critical mass of uranium is necessary for nuclear chain reactions (Equations 1 to 3) to occur. A smaller concentration of ura
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2.2 Nuclear fission

Every atom has a nucleus consisting of positively charged protons and electrically neutral neutrons. Protons and neutrons have virtually identical mass and the total number of protons and neutrons defines the mass number of a particular atom. The number of protons in the nucleus is the atomic number and this quantity is always the same for each particular chemical element. However, some elements have several isotopes, each with different numbers of ne
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1 Nuclear energy

The transformation of radioactive uranium and, in some instances, thorium isotopes provides vastly more energy per unit mass of fuel than any other energy source, except nuclear fusion, and therein lies its greatest attraction. The key to that remarkable fact is the conversion of matter (with mass, m) into energy (E), according to Einstein's famous equation E = mc2, where c is the speed of light (3×108 m s−1 ).

The p
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Learning outcomes

By the end of this unit you should be able to:

  • distinguish between energy produced by nuclear fission and radioactive decay;

  • describe the principles behind nuclear 'burner' and nuclear 'breeder' reactors;

  • understand the geoscientific principles underlying the enrichment of uranium in ore deposits;

  • summarise and explain the hazards associated with nuclear wastes and their safe disposal;

  • summarise the fluctuating fortunes
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Introduction

The transformation of radioactive uranium and, in some instances, thorium isotopes provides vastly more energy per unit mass of fuel than any other energy source, except nuclear fusion, and therein lies its greatest attraction.

The potential of nuclear fuels for energy production became a reality when the first experimental atomic pile, built by Enrico Fermi and Léo Szilárd at the University of Chicago, began functioning in December 1942. That led to the manufacture of fissionable mat
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Acknowledgements

Grateful acknowledgement is made to the following sources for permission to reproduce material in this unit:

Except for third party materials and otherwise stated (see terms and conditions), this content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Licence

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6 Summary

  1. Waterlogged organic matter accumulates in deltaic, coastal barrier or raised mires to form peat. Coal forms by the compaction and decomposition of peat. Chemical changes imposed by increasing temperature and pressure over time determine the coal rank.

  2. Coalfields can be classified as either exposed or concealed, depending on whether or not the coal-bearing rocks are hidden by younger strata. In most coalfields, mining commenced in the shallower
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5 Coal production in the UK early in the 21st century

This section examines the UK's coal industry in a little more detail, to see how the complex interplay of location, economics and politics has led to the rapid demise of an industry that was once at the heart of the UK's economy.

Figure 38 shows production and consumption figures for coal mined in the UK since 1945 a
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4.6 Global coal reserves and their life expectancy

In 2003, global proven coal reserves were estimated at 984.5 × 109 t, of which slightly over half (52.7%) was anthracite and bituminous coal and the rest (47.3%) was sub-bituminous coal and lignite.

Figure 37 shows the breakdown of global reserves by continental regions. North America has 26% of total g
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4.5 Global distribution of coal

Figure 35 shows the global distribution of coal deposits. The major areas are principally in the Northern Hemisphere; with the exception of Australia, the southern continents are relatively deficient in coal deposits.

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4.4 Coal in the European Union

The EU's coal reserves in 2004, after enlargement to 25 member states, stood at 100 × 109 t. Table 3 shows the eight European Union Member States with the most significant reserves ranked in order of greatest tonnage. With a little over 100 × 10 9 t of coal of all ranks, the EU possesses approxima
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4.3 The UK's coal reserves

Production of large quantities of coal in the UK during the 19th and 20th centuries led to the progressive depletion of reserves. In 2005 underground mining was limited to the Carboniferous coalfields of Yorkshire and the East Midlands, with only one underground mine operating in South Wales. However, surface mining sites still work coal in most of the coalfields (Author(s): The Open University

4.2 Coal distribution in the UK and Europe

The UK and Europe were fortunate in having extensive coalfields that powered the Industrial Revolution. Figure 33 shows the distribution of the major Carboniferous mires which became coal-bearing rocks across Europe, either outcropping at the surface or buried beneath younger rocks. The first thing that is evident from t
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3.3.1 Mining subsidence

Subsidence is an inevitable hazard wherever underground mining is carried out.

The major factors affecting the extent of subsidence are seam thickness and its depth beneath the surface.

The amount of subsidence can be calculated roughly by using the formula:

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