Page 35 - Curriculum Visions Dynamic Book

Breeder reactor
It is possible for a nuclear reactor to be designed to make more fuel than it uses, considerably cutting down fuel costs.
Breeder reactors consist of many stainless steel tubes containing uranium oxide and plutonium oxide, surrounded by tubes containing uranium oxide. As the fuel in the central rods undergoes fission, it releases neutrons that are absorbed by the uranium in the outer rods. These convert the uranium in the outer rods into plutonium. The better use of uranium makes the fuel last up to fifty times as long as in ordinary reactors.
Normally the heat produced by the fission of uranium and plutonium in the core is used to heat water, which is then taken away to drive steam turbines and make electricity. But the water also soaks up neutrons. To allow the neutrons to escape from the core and produce new plutonium, a different material has to be used. In fast breeder reactors the water is replaced with liquid sodium.
alloy: a mixture of a metal and various other elements.
fission: the breakdown of the structure of an atom, popularly called “splitting the atom”.
Using uranium in
nuclear reactors
The element uranium is most widely used as the fuel of a nuclear reactor. In a nuclear reactor the fission process is started by spontaneous decay because of so much fuel being contained together. This sets up a chain reaction that can be controlled so that new reactions occur all the time. The rate of the reactions determines the amount of heat released and thus eventually the amount
of electricity that the power stations can produce.
 A diagram of a nuclear reactor.
Reinforced concrete containment building
Fuel rods loaded with pellets of uranium oxide, the fuel
Graphite core moderator
Concrete shield absorbs radiation
Steel vessel
A coolant fluid, frequently liquid water or a gas under pressure, circulates through the reactor carrying heat to the steam generator.
Control rods absorb some of the neutrons and regulate the rate of fission.
Pressuriser
Steam
Heated fluid, used to boil water in the steam generator.
Steam from steam generator is transferred to the steam turbine to generate electricity.
Pump circulates coolant
Condenser (steam from the turbine is condensed by water in the cooling towers)
Generator
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