Техническое чтение для энергетиков. Бухарова Г.П. - 93 стр.

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95
through pipes or open channels to a point farther downstream where the natural
conditions make a greater head possible.
The design of machines for using water power greatly depends on the nature of
the available water supply. In some cases great quantities of water can be taken from
a large river with only a few feet head. In other cases, instead of a few feet, we may
have a head of several thousands of feet. In general, power may be developed from
water by action of its pressure, of its velocity, or by a combination of both.
A hydraulic turbine and a generator are the main equipment in a hydroelectric
power-station. Hydraulic turbines are the key machines converting the energy of
flowing water into mechanical energy. Such turbines have the following principal
parts: a runner composed of radial blades mounted on a rotating shaft and a steel
casing which houses the runner. There are two types of water turbines, namely, the
reaction turbine and the impulse turbine. The reaction turbine is the one for low heads
and a small flow. Modified forms of the above turbine are used for medium heads up
to 500-600 ft, the shaft being horizontal for the larger heads. High heads, above 500
ft, employ the impulse type turbine. It is the reaction turbine that is most used in the
USSR.
Speaking of hydraulic turbines, it is interesting to point out that in recent years
there has been a great increase in size, capacity, and output of Soviet turbines.
Hydropower engineering is developing mainly by constructing high capacity
stations integrated into river systems known as cascades. Such cascades are already in
operation on the Dnieper, the Volga and the Angara.
NUCLEAR POWER PLANT
The heart of the nuclear power plant is the reactor which contains the nuclear
fuel. The fuel usually consists of hundreds of uranium pellets placed in long thin
cartridges of stainless steel. The whole fuel cell consists of hundreds of these
cartridges. The fuel is situated in a reactor vessel filled with a fluid. The fuel heats the
fluid and the super-hot fluid goes to a heat exchanger, i. e. steam generator, where the
hot fluid converts water to steam in the heat exchanger. The fluid is highly
radioactive, but it should never come into contact with the water that is converted into
steam. Then this steam operates steam turbines in exactly the same way as in the coal
or oil fired power-plant.
A nuclear reactor has several advantages over power-plants that use coal or
natural gas. The latter produce considerable air pollution, releasing combusted gases
into atmosphere, whereas a nuclear power plant gives off almost no air pollutants. As
to nuclear fuel, it is far cleaner than any other fuel for operating a heat engine.
Furthermore our reserves of coal, oil and gas are decreasing so nuclear fuel is to
replace them. It means that coal and oil can be used for some other purposes. The
amount of nuclear fuel which the nuclear power-plant consumes is negligible while
the world's uranium and thorium resources will last for hundreds of years.
The construction of the world's first nuclear power-plant in Obninsk near
Moscow is a great historical event and the beginning of atomic energetics. Since then

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