Nuclear Power Station Md. Farid Ahmed

Bsc in Electircal & Electronics Engineering

IntroductioA generating station is known which nuclear energy is convert into electrical energy is known as a nuclear power station.In nuclear power station, heavy elements such as Uranium (235U92) or Thorium (232U) are subjected to nuclear fission in a special aparatus known as a reactor. A huge amount of heat released is utilized in rising steam at high temperature and pressure. The steam runs the steam turbine which converts steam enerty ito mechanical energy. The turbine drives the alternators which converts mechanical energy into electrical energy.

Advantages & Disadvantages

2Advantages Disadvantages

The amount of fuel required is quite small. Therefore, there is a considerable saving in the cost of fuel transportation.

A nuclear power plant requires less spaces as compared to any other type of the same size.

There are large deposits of nuclear fuels available all over the world. Therefore, such plants can ensure continued supply of electrical energy for thousands of years.

The fuel used is expensive and is difficult to recover.

The erection and commissioning of the plant requires greater technical know-how.

The fission by-products are generally radioactive and may cause a dangerous amount fo radioactive pollution.

Chain Reaction

3

protonneutron

U-235 nucleus

Neutrons released in fissionNeutrons released in fission trigger the fissions of other nuclei

Chain Reaction

4

Uranium exists as an isotope in the form of U235 which is unstable.

When the nucleus of an atom of Uranium is split, the neutrons released hit other atoms

and split them in turn. More energy is released each time another atom splits. This is called

a chain reaction.

schematic arrangement of nuclear power station

5control rods

fuel rods

reactor pressure vessel

water (cool)

water (hot)

water (high pressure)

water (low pressure)

coolant out

coolant insteam condenser

steam (low pressure)

turbine

electric power

steam generator

steam (high pressure)

pump

primary loop secondary loop

reactorcore

pump

generator

Reactor

6 235U fissions by absorbing a neutron and producing 2 to 3 neutrons, which

initiate on average one more fission to make a controlled chain reaction Normal water is used as a moderator to slow the neutrons since slow

neutrons take longer to pass by a U nucleus and have more time to be absorbed

The protons in the hydrogen in the water have the same mass as the neutron and stop them by a billiard ball effect

The extra neutrons are taken up by protons to form deuterons 235U is enriched from its 0.7% in nature to about 3% to produce the reaction,

and is contained in rods in the water Boron control rods are inserted to absorb neutrons when it is time to shut

down the reactor The hot water is boiled or sent through a heat exchanger to produce steam.

The steam then powers turbines.

Selection of site for nuclear power station

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a) Availability of water:

b) Disposal of waste:

c) Distance form population area:

d) Transportation facilities: