How does nuclear energy work?

Hint: Nuclear energy works in nuclear power plants to generate electricity. Nuclear reactors are called the heart of a nuclear power plant. Without Nuclear reactors, nuclear power plants are not able to work. Nuclear power plants use controlled nuclear chain reactions that produce heat through a physical process called fission. That heat produced in nuclear reactors is used to make steam that spins a turbine to create electricity.

Complete answer:
In nuclear reaction there is a collision between a target nucleus “A” and bombarding particle “a” produces another nucleus “B” and an elementary particle “b” or gamma ray. This reaction may be represented as: -
\[A+a\to B+b+Q\]
The factor Q represents the energy absorbed or released in the nuclear reaction. This is called Q-value or nuclear reaction energy. This nuclear reaction energy is the difference between the sum of masses of reacting particles and the sum of rest mass of product particles.
If initial rest mass is greater than final rest mass, then the Q-value of the reaction is positive. Such a nuclear reaction is called an exothermic reaction .The energy released in the reaction is called nuclear energy. This energy appears in the form of kinetic energy of product particles.
If initial rest mass is less than final rest mass, then the Q-value of the reaction is negative. Such a nuclear reaction is called an endothermic reaction.
The energy released or absorbed in a nuclear reaction can be calculated by from Einstein’s mass energy relation:- \[E=\Delta m{{c}^{2}}\]
The energy released during a nuclear reaction is called nuclear energy. Nuclear energy plays an important role in nuclear reactors which produce electricity. Nuclear reactor is a device in which a nuclear chain reaction is initiated, maintained and controlled. Nuclear Reactor works on the principle of controlled chain reaction and provides energy at constant rate.
The controlled chain reaction produces the energy from nuclear fission, this energy then turns water into steam and this steam creates a large pressure and the due to that pressure shaft of generator rotates which ultimately turns a generator, which produces electricity. So energy produced in nuclear power plants is used for various useful purposes.

Note:
Reactors generally use uranium for nuclear fuel. These fuels are taken in the form of rods, tightly sealed in aluminium containers called fuel rods. Typically more than 200 of these rods are bundled together to form a fuel assembly.
These fuel rods are immersed in water which acts as both a coolant and moderator. The moderator helps slow down the neutrons produced by fission to sustain the chain reaction. Control rods can then be inserted into the reactor core to reduce the reaction rate. The heat created by fission turns the water into steam, which spins a turbine to produce carbon-free electricity.