👍 (ТулГУ / Обновлённый сайт) Иностранный язык (английский) / 001 / Направление: Электроэнергетика и электротехника / Тема: Атомная энергия (Перевод / Оценка - 86 баллов)

Тема:

АТОМНАЯ ЭНЕРГИЯ

Направление:

Электроэнергетика и электротехника

Источник:

Техническое чтение для энергетиков: Методическое пособие по английскому языку для студентов 1, 2 курсов энергетических специальностей дневной и заочной форм обучения / сост. Г. П. Бухарова. – Ульяновск: УлГТУ, 2004. – 112 с.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

ККР зачтена на отлично - 86 баллов (скрин в демо-файлах)

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Если нужна помощь с другими тестами - пишите в личку.

https://studwork.org/info/86802

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Английский текст - ниже:

THE NATURE OF THE ATOM

All the prime movers, natural and man-made, which, humanity has harnessed toease its burden of labour and raise its standard of living are, in fact, attempts atutilizing the energy of the sun: it sustains organic life on earth with its light and heat,it makes the water circulate between the heavens and the sea, it creates the wind, andit has filled for us a vast storehouse of coal and oil, the mineral deposits from oldages of vegetation. What our inventors did when they built power-producing engineswas to change one form of energy–such as the heat of burning coal – into another, themechanical energy of rotating wheels or the light of an electric lamp. They could notcreate energy from nothing; they could only release it by some chemical process.This means that although the molecules, or combinations of atoms, may break up andform new combinations, the atoms themselves remain intact and unchanged.There is one source of energy, however, which owes nothing to the heat andlight of the sun; nor can it be harnessed by a chemical process. It is the energy of theatomic nucleus.

The term 'atom', coined by the Greek philosopher Democritus about 2,500years ago, is rather misleading. It means 'the indivisible', and it is a relic from thetimes when people believed that all matter consisted of very small particles whichwere Unchangeable and indivisible, and that each element had its own special kindof particles. Only the medieval alchemists hoped that they could, by some magic,change the particles of one element into those of another – lead, for instance, intogold.

Today we know that atoms are neither unchangeable nor indivisable. The storyof research into the nature of the atom has been told many times. It may be sufficientto recall that Marie and Pierre Curie, by their discovery of radium, in 1898, made thewhole theory of the indivisible atom crumble, because here was an element whichdisintegrated and sent out rays, consisting of particles much smaller than the atom.

Another discovery, made three years earlier, seemed to point in the samedirection: that of the X-rays by Professor Wilhelm Konrad Rontgen at the Universityof Bavaria. Using a cathode-ray tube, he found that the radiation emanating from itwas able to penetrate thin matter like wood and human flesh, but was stopped bythicker objects such as pieces of metal and bones. It was only later that the nature ofthese mysterious rays was discovered: particles of negative electricity, calledelectrons, turn into electro-magnetic waves, of the same kind as light but of shorterwave-length and therefore invisible, when they strike a material object such as ametal shield in the cathode-ray tube.

These and other phenomena and discoveries around the turn of the centurywere deeply disturbing for the physicists, and they saw that the whole traditionalconcept of the structure of matter had to be completely revised More than that: theborderline between matter and energy seemed to disappear. When, as early as 1905,Albert Einstein published his Special Theory of Relativity, in which he declared thatmatter could be converted into energy– very little matter into very great energy –there was a storm of protest in the scientific world. But little by little the evidencethat he was right accumulated, and within a few years an entirely new picture of theatom emerged from the studies and laboratories of scientists in many countries. Fromthat evidence Lord Rutherford, the New Zealand-born scientist, and his young Danishassistant, Niels Bohr, developed by 1911 their revolutionary theory of what the atomwas really like.

That picture of the atom has since been elaborated and filled in with moredetails. It is not yet complete; but its essential features are known to be correct –otherwise there would be no atomic bombs, which few people would regret, ornuclear power stations.

Broadly speaking, the atom is a miniature solar system, with a 'sun', thenucleus, and a number of 'planets', the electrons, revolving around it. All the matter ofthe atom is concentrated in the nucleus: there are protons, particles with a positiveelectric charge, neutrons, particles without a charge, and some other particles whoserole and nature is still being investigated. The electrons, which have next to no massand weight, are negatively charged; in fact, they are the carriers of electricity in allour electric wires and appliances.

Normally there are as many positive protons in the nucleus as there areelectrons revolving around it, so that their charges cancel each other out and the atomas a whole is electrically neutral. But if for some reason an atom loses a proton or anelectron or two, its electrical balance is disturbed, it becomes negatively or positivelycharged and is called an ion.

The atoms of all the elements contain the same kind of particles; whatdistinguishes them from each other is merely the number of particles – of protons inthe nucleus and of electrons revolving around it. Hydrogen, for instance, being thelightest and simplest element, has only one of each; uranium, the heaviest elementoccurring in Nature, has 92. So all you have to do to change one element into anotheris either to knock some protons and a corresponding number of electrons off eachatom, or add them; in fact, this process is going on in Nature all the time.

Theoretically, we could change lead into gold, as the alchemists dreamed of doing, byremoving three protons and electrons from a few billion lead atoms, which have 82 ofeach, then we would get gold atoms with 79 protons and electron each. However, theknocking-off process would be much more expensive than the gold we would get.

The neutrons, which are present in the atoms of many elements, are ofparticular importance in the utilization of atomic energy. Most elements are mixturesof ordinary atoms and so-called isotopes: the isotope atoms have more, or fewer,neutrons than the ordinary atoms. An isotope differs from the ordinary form of theelement only in weight, but chemically it behaves in exactly the same way. Water, forinstance, is a mixture of ordinary molecules of hydrogen and oxygen atoms and of'heavy' ones. The heavy hydrogen atom has an extra neutron in its nucleus.

Uranium, on the other hand, has anjsotope whose nucleus contains fewer neutronsthan the ordinary element. This isotope – atomic weight: 235; atomic weight ofordinary uranium: 238 – has a very special significance in nuclear physics because itis, like many other heavy-element isotopes, 'unstable'.What does this mean? Nothing else but the phenomenon which the Curiesdiscovered in radium. An unstable nucleus is one that is likely to break up into thenucleus of another element. Professor Otto Hahn found in Berlin in 1938 that whenuranium atoms are bombarded with neutrons they split up in a process which hecalled 'fission' (a term used in biology for the way in which some cells divide to formnew ones). The 92 protons of the uranium nucleus split up into barium, which has 56,and krypton, a gas with 26 protons. Frederic Joliot-Curie, the son-in-law of MarieCurie, proved some months later that in this fission process some neutrons from theuranium nucleus were liberated; they flew off, and some struck other nuclei, which inturn broke up, liberating still more neutrons. Enrico Fermi, an Italian who had gone toAmerica to escape life under fascism, developed the theory of what would happen if asufficiently large piece of unstable uranium broke up in this way – there would be a'chain reaction': the free neutrons would be bombarding the nuclei with such intensitythat in no time at all the whole lump of uranium would disintegrate.But it would nut just turn quietly into barium and krypton as in Berlinlaboratory experiment. There were now two smaller nuclei, no longer held together asbefore but pushed apart by electric repulsion, and flying off at great speed, withneutrons shooting about in all directions. And such sudden display of energy–formovement is energy – would, according to Einstein's famous Mass-Energy equation,correspond to some loss of mass. If the two parts of a nucleus which has undergonefission could be put together again, their combined mass would be smaller than thatof the original nucleus. What has become of the missing bits? They have turned intopure energy – into movement, into heat.

This was the theory that led, within the short space of four years, to the firstatom bombs. On Monday, 6 August 1945, while cheerful crowds in England enjoyedtheir first holiday after the end of the war in Europe, one such bomb was dropped onthe town of Hiroshima in Japan. It killed or injured nearly 200,000 people. Threedays later another bomb was dropped on Nagasaki, with 65,000 victims. The centresof both cities were completely destroyed.

PEACEFUL ATOM

When the world had recovered from the shock of this unimaginable horror,people everywhere asked the scientists how soon they could apply the immensepower of the fissioned nucleus to peaceful purposes. But this took much longer. Itwas considerably easier to use the nuclear chain reaction for distruction than for theproduction of usable energy for homes and factories–to control it and release it insmall doses. Many problems had to be solved; the main one was that of 'braking' thereleased neutrons efficiently so that the chain reaction would not get out of hand.The first atomic 'pile' or 'reactor', as the apparatus for the utilization of atomicenergy is now called, had been Set up by Enrico Fermi on the football ground of theUniversity of Chicago in 1942. It was a somewhat crude assembly, whose mainpurpose was to get experimental proof for the theory of chain reaction. Fermiscattered rods of uranium through a stack of graphite blocks, which acted as a brakefor the neutrons – a 'moderator', to use the technical term. Fermi used naturaluranium, which is a mixture of the stable U-238 and the unstable U-235 in aproportion of 140 : 1. Thus there was only slight radioactivity, i. e. breaking-up ofnuclei. In order to control it, Fermi inserted some cadmium rods into the pile; thismetal absorbs neutrons very readily, and by pushing the rods completely into the pilehe could stop the chain reaction altogether.

Fermi's assembly is still the basic blueprint of today's nuclear reactors. Theirmain parts are the fuel, the moderator, the control rods, and the cooling system. Butthe scientists and technicians have since developed a great many different types ofreactors – some already in everyday use, others running experimentally in atomicresearch establishments or being built for special jobs and purposes of all kinds, fromproducing nuclear explosives for weapons to 'cooking' stable elements' so that theybecome unstable isotopes for use in medicine, industry, agriculture, and research.Why do we speak of the atomic age as a new chapter in the history ofcivilization, and why have the technologists made such great efforts to utilize theenergy of the split nucleus? For a long time the shadow of a future without sufficientfuel loomed over mankind. Coal has been mined at a steadily increasing pace whichset in with the industrial Revolution, and some experts predicted that in Britain, forinstance, an acute shortage of cheaply mined coal would set in after 1980. Oil is stillto be found in plenty, but consumption has been increasing in leaps and bounds allover the world.

Atomic energy is produced in a different way. It is not generated by thechemical process of combustion. It is released when nuclei undergo fission, andalthough here» too, matter is used up, the amounts are small compared with theenergy produced. A few pounds of uranium 235 can be made to supply a mediumsizedtown with all the electricity it needs during a whole year. True, our reserves ofuranium are limited. But there is one reactor type, which in fact produces morenuclear fuel than it uses! This type has a 'blanket' of thorium, one of the most commonelements on earth, which is turned into the artificial radio-active elementplutonium when bombarded by neutrons. And there is good reason to hope thatbefore long1 we shall be able to produce energy from ordinary sea-water by anothernuclear reaction called 'fusion'.

So there is little doubt that mankind's energy problems will be solved in thenear future, if they have not been solved already in principle. All we have to do isbuild nuclear reactors and supply them with atomic fuel. But how do we turn it intousable energy?

The 'classical' solution of this question, although it may soon be regarded as anold-fashioned one, is to conduct the heat generated by the fission process out of thereactor, make it boil water, and let the resulting steam drive turbines which, in theirturn, drive electric generators. It is a roundabout way, but it works well, although it isstill rather expensive.