1. What is a nuclear reactor? What is the fuel used in a nuclear reactor?
2. With the help of a labelled diagram, describe the working of a nuclear power plant.
3. How is the working nuclear reactor of a power plant shut down in an emergency?
4. Name five places in India where nuclear power plants are located.

(a) A nuclear reactor is a device designed to harness nuclear energy (fission energy) by controlled chain reaction producing a steady flow of neutrons generated by the fission of heavy nuclei. Uranium-235 is used as a fuel in a nuclear reactor.

(b) A labelled diagram of the working of a nuclear power plant.

In a nuclear power plant, the fission of uranium-235 is carried out in a steel vessel (V) of the reactor (R). Enriched U-235 rods (A) are inserted in a graphite core, which acts as a moderator to slows down the speed of neutrons. Boron rods (B) are inserted between the uranium rods to control the rate of the fission reaction by absorbing excess neutrons. The controlled fission of U-235 produces a large amount of heat energy, therefore liquid sodium or carbon dioxide gas is pumped continuously through the pipes embedded in the reactor by using a pump (P), to absorb the heat produced in the reactor. The extremely hot sodium is then passed into the coil of a heat exchanger (H) containing water, where the water absorbs the heat from the sodium and boils to form steam. The steam thus formed at high pressure is introduced into a turbine chamber (C) which makes the turbine rotate due to the pressure of the steam and drives the generator connected along with the shaft and produces electricity.

(c) In case of an emergency, the boron control rods are fully inserted into the reactor to shut down the working nuclear reactor of a power plant.

(d) Five places in India where nuclear power plants are located are the following.

1. Tarapur (Maharashtra)

2. Kalapakkam (Tamil Nadu)

3. Kakrapar (Gujarat)

4. Kaiga ( Karnataka )

5. Narora (Uttar Pradesh)