STATIC STRESS-STRAIN PROPERTIES INTENSION AND COMPRESSION

Britain has the largest energy resources of

any country in the European Community and

is a major producer of oil, natural gas and coal. Other primary sources of energy are

nuclear power and, to a lesser extent water. power.

Before the 1970s Britain depended on imports of oil from abroad but the discovery

of large oil and gas reserves in the North Sea changed this dramatically: by 1986 about 2.2 million barrels of oil were extracted per day, making Britain the world's fifth largest producer. There are over thirty offshore oilfields from which oil and gas are piped to the mainland. Natural gas has replaced coal gas in the public supply system.

Britain has large reserves of coal, and coal mining played a very important part in the industrial revolution of the eighteenth and nineteenth centuries. By 1913 the coal

industry employed over a million workers. Coal is still an important source of heat for both private houses and power stations, but in

Nuclear power

'The government believes that nuclear power has a vital role in helping to meet Britain's long-term energy requirements.' (Central Office of Information)

'We are in favour of a balanced energy programme for our country's future. Nuclear electricity is not the only answer - but it is a clean, reliable, economic piece of the electricity jigsaw.' (Nuclear Energy Information Group)

'Studies from many countries indicate that

all radioactive wastes can be managed and disposed of without undue risk to man or the environment.' (UK Atomic Energy Authority)

'Nuclear power is unsafe ... and there is a long history of leaks and accidents.' (State of the Nation)

recent years the industry has greatly reduced the numbers of mines and miners while increasing efficiency. There was a long and bitter industrial dispute in 1984-85 as miners reacted to the beginning of this new phase in the development of the coal industry.

(below) A coal mine

ENERGY AND THE ENVIRONMENT 59

'An accident on the scale of Chernobyl could happen here at any time.' (Greenpeace)

'We had to destroy sheep for two years after Chernobyl - here and in the Lake District. How do they know it was Chernobyl? We've got nuclear reactors on our doorsteps, and the radiation had never been measured before.' (A North Wales farmer)

Britain has fourteen nuclear power stations in operation. There are other nuclear installations too, such as reprocessing units and research centres. Since the original power stations started operations in 1956 there has been much discussion over the best design; pressurised water reactors are planned for the future and the government's eventual aim is to have 20 per cent of Britain's electricity produced by nuclear power.

All proposals for new power stations meet with public opposition, and this has increased since the disaster at Chernobyl in the Ukraine in 1986. There are fears that the reactors themselves are unsafe, and that the problems of waste, disposal have not been solved. While those in favour of nuclear power claim that it is clean, safe and efficient, opponents argue that the dangers are too great and that other sources of energy have not been sufficiently researched because of lack of government funding or interest. The privatisation of the electricity industry has also raised the

question of who should own and operate nuclear power stations.

Comprehension

Use the information on these two pages to answer the questions.

1 What are the major sources of energy in
Britain?

2 How important is North Sea oil to Britain?

3 What do the quotations tell you about the
government's viewpoint and other views of
nuclear power?

4 Why is there opposition to the use of
nuclear power?

Discussion Work in pairs.

1 What similarities and differences are there
between Britain's energy sources and those
of your own country?

2 What are the most common forms of
energy in your own country for home
heating, cooking and the production of
electricity?

STATIC STRESS-STRAIN PROPERTIES INTENSION AND COMPRESSION

(I)

Most engineers are primarily concerned with the development and design of machines, structures and products of various kinds. Since these constructions are usually subjected to internal for­ces and deformations called stresses and strains, the properties of materials under the action of these stresses and strains for various environments become an important engineering considera­tion. The macroscopic properties of materials when subjected to these stresses and strains are called the mechanical properties. The study of the macroscopic stress-strain properties of materi­als may be referred to as solid state mechanics in the same way as solid state physics refers to the atomic and molecular beha­viour of materials on the submicroscopic level. An understanding of the stress-strain properties of materials are important, since high values of stress and strain may result in the failure of a construction. Failures may lead to loss of life and costly damage when airliners or trains are wrecked or a bridge collapses. Sometimes failures do not lead to loss of life but involve need­less costly repairs, delays in operation, or replacement of parts.

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Date: 2015-01-02; view: 797