NUCLEAR POWER PLANT - PART:1 - COMPONENTS

 INTRODUCTION:

      Nuclear power plants are a type of power plant that use the process of nuclear fission in order to generate electricity. They do this by using nuclear reactors in combination with the Rankine cycle, where the heat generated by the reactor converts water into steam, which spins a turbine and a generator.

COMPONENTS OF NUCLEAR REACTOR:

MODERATOR:

 The moderator of a nuclear reactor is a substance that slows neutrons down.  When fast neutrons strike the hydrogen atoms in H₂O, they slow down. eg-  graphite, beryllium, Heavy water, Normal water, Helium gas.

PROPERTIES:

 1. It should have high thermal conductivity.
 2. It should have high corrosion resistance.
 3.It should lighter in weight.
 4. It should has good stability to heat and power radiation.

CONTROL RODS:

  It use to control the incidence of the neutrons and prevent the nuclear reactor from the explosions.

FUNCTION OF CONTROL RODS:

 1. To control the rate of fission.
 2. To start the nuclear chain reaction when the reactor is started from cold.
 3. To shunt down the reactor in the emergency condition.
 4. To prevent the melting of fuel rods.

CONTROL RODS SHOULD POSSES THE FOLLOWING PROPERTIES:

 1. It should have good stability under heat and radiation.
 2. It should have adequate heat transfer properties.
 3. It should have better corrosion resistance.

BORON, CADMIUM, HAFNIUM ARE MOSTLY USED AS  CONTROL RODS.

REFLECTOR:

 1. Reflector materials placed around the core to reflect back some of neutrons that they leak- out from the surface of the core.

 2. The reflected neutrons cause more fission and they improve the neutrons economy of reactor.
 3. It made as same material as moderator.

HEAVY WATER, NORMAL WATER, BERYLLIUM, GRAPHITE, HELIUM GAS.

COOLING SYSTEM:

   The coolant are used to carry away heat produced inside the reactor to the heat exchanger. From heat exchanger , heat is transferred to another working medium for further utilization of power generation.

NORMAL WATER, GASES , LIQUID METALS ARE USED.

PROPERTIES:

 1. It should have low melting point.

 2. It should have low viscosity

 3. It should be Non - Corrosiveness.

 4. It should have high density.

 5. It should have high specific heat.

BIOLOGICAL SHIELDING:

     Shielding is necessary to protect the walls of the reactor vessel from radiation damage and it protect the operation personnel from exposure to radiation.
 1. Thick layer of lead concrete or steel are provided all around the reactor.
 2. These layer absorbs the gamma rays, neutrons, etc.,

A GOOD SHIELDIG MATERIALS SHOULD HAVE THE FOLLOWING PROPERTIES:

 1. It should absorb Alpha, Beta and Gamma radiation.
 2. It should have uniform density.
 3. It should be fire resistance.

HEAT EXCHANGER:

  It is used to convert feed water into stream from heat produced in a nuclear reactor core.

STEAM TURBINE:

  A steam turbine is a device that extracts thermal energy from pressurized stream and uses it to do mechanical work on a rotating output shaft.

GENERATOR:

  A generator is a device that convert mechanical energy of the steam turbine to electrical energy.

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