Техническое чтение для энергетиков. Бухарова Г.П. - 8 стр.

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scattered rods of uranium through a stack of graphite blocks, which acted as a brake
for the neutrons – a 'moderator', to use the technical term. Fermi used natural
uranium, which is a mixture of the stable U-238 and the unstable U-235 in a
proportion of 140 : 1. Thus there was only slight radioactivity, i. e. breaking-up of
nuclei. In order to control it, Fermi inserted some cadmium rods into the pile; this
metal absorbs neutrons very readily, and by pushing the rods completely into the pile
he could stop the chain reaction altogether.
Fermi's assembly is still the basic blueprint of today's nuclear reactors. Their
main parts are the fuel, the moderator, the control rods, and the cooling system. But
the scientists and technicians have since developed a great many different types of
reactors – some already in everyday use, others running experimentally in atomic
research establishments or being built for special jobs and purposes of all kinds, from
producing nuclear explosives for weapons to 'cooking' stable elements' so that they
become 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 of
civilization, and why have the technologists made such great efforts to utilize the
energy of the split nucleus? For a long time the shadow of a future without sufficient
fuel loomed over mankind. Coal has been mined at a steadily increasing pace which
set in with the industrial Revolution, and some experts predicted that in Britain, for
instance, an acute shortage of cheaply mined coal would set in after 1980. Oil is still
to be found in plenty, but consumption has been increasing in leaps and bounds all
over the world.
Atomic energy is produced in a different way. It is not generated by the
chemical process of combustion. It is released when nuclei undergo fission, and
although here» too, matter is used up, the amounts are small compared with the
energy produced. A few pounds of uranium 235 can be made to supply a medium-
sized town with all the electricity it needs during a whole year. True, our reserves of
uranium are limited. But there is one reactor type, which in fact produces more
nuclear fuel than it uses! This type has a 'blanket' of thorium, one of the most com-
mon elements on earth, which is turned into the artificial radio-active element
plutonium when bombarded by neutrons. And there is good reason to hope that
before long
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we shall be able to produce energy from ordinary sea-water by another
nuclear reaction called 'fusion'.
So there is little doubt that mankind's energy problems will be solved in the
near future, if they have not been solved already in principle. All we have to do is
build nuclear reactors and supply them with atomic fuel. But how do we turn it into
usable energy?
The 'classical' solution of this question, although it may soon be regarded as an
old-fashioned one, is to conduct the heat generated by the fission process out of the
reactor, make it boil water, and let the resulting steam drive turbines which, in their
turn, drive electric generators. It is a roundabout way, but it works well, although it is
still rather expensive.
Britain's first two nuclear power stations were Calder Hall (opened in 1956)
and Chapelcross (1959), both of the same type. The reactor 'vessel' a giant steel

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