What is a Nuclear Reactor?

A Nuclear Reactor is a systematic arrangement to convert Nuclear Energy into thermal energy and then to Electrical energy .  Nuclear Reactor uses fissile material, heavy atomic nuclei, called as Nuclear Fuel. Fissile material leads to nuclear fission when the nuclei are hit by suitable energy Neutrons.

  

Example for Fissile Material is Uranium oxide.

Fission reaction of Uranium is as follows:

The energy evolved is distributed as kinetic energy of fission fragments  and heat.

This heat energy transmitted to a coolant which leads to generation of steam that could drive turbine system for conversion of thermal energy into electrical energy.

There are different types of Nuclear Reactors operating across the world.

a)  Boiling Water Reactors

b)  Pressurized Water Reactors

c)  Pressurized heavy water Reactors

d)  Fast Breeder Reactors

Difference between Fission Fragments & Fission Products

The name “fission products” applies to all members of the decay chains— including the original fission fragments. The term fragment describes the initial flying pieces that de-excite before they come to rest as fission products. The majority of fission products have half-lives that range from fractions of a second to about 30 years.
 

The kinetic energy of the fission fragments accounts for most of the energy released in the fission reaction. The energetic fragments slow and stop in about 10-13 s, (after travelling about 10-3 mm), heating the fuel by passing their energy to the surrounding fuel atoms.

Each fission product consists of a substantial piece of the original nucleus. They are likely to have mass numbers between 70 and 160, with mass numbers near 95 and 140 the most probable. Symmetrical fission (equal fragments) is rare. Fission products are a potential radiological hazard. They also absorb neutrons that might otherwise cause fission, limiting the long-term energy output from the fuel. They have one important useful effect; reactor control would not be possible without the delayed neutrons that result from fission product decay.