Nuclear energy is the energy stored in the nucleus of an atom and released through fission, fusion and radioactivity

There are two types of nuclear energy

1. Nuclear Fission2. Nuclear Fusion

NUCLEAR FISSION

When a particle of sufficient energy is shot on to a heavier nucleus the nucleus splits and releases energy. This reaction is called NUCLEAR FISSION

When Uranium 235 nucleus is bombarded

with a neutron

0n1 + 92U235 56Ba141+36Kr92+30n1+energy

Fission of U235

When an Uranium nucleus undergoes fission, neutrons are released. These neutrons in turn split the surrounding uranium nuclei releasing neutrons in each reaction. This is called CHAIN REACTION

CHAIN REACTION

Controlled fission reaction

Example for nuclear fission

ATOM BOMB

On Aug 6 1945 a Uranium bomb was dropped on the city of Hiroshima killing 1.5 lakhs of people. Here is the picture of that bomb. Length: Approx. 3 meters (120 inches) Weight: Approx. 4 tons (9,000 lbs)  Diameter: Approx. 0.7 meters (28 inches) Element: Uranium 235

Another bomb was dropped at Nagasaki on Aug 9 killing thousands of people. Here is the picture of that bomb. Length: Approx. 3.2 meters (128 inches) Weight: Approx. 4.5 tons (10,000 pounds) Diameter: Approx. 1.5 meters (60 inches) Element: Plutonium 239

A device that is used to produce nuclear energy by controlled fission reaction is called nuclear reactors

There two types of nuclear reactors

• Pressurized Water Reactor• Boiling Water Reactor

Pressurized Water Reactor

Boiling Water Reactor

In India Pressurized Water Reactors are used.

Mentioned below are some reactors present in India

First nuclear reactor in Asia – Apsara

Tarapur India’s First nuclear Power Station

Rawatbhata India’s first commercial nuclear reactor

Kalpakkam Mini Reactor

Narora Atomic Power Station

Advanced Heavy Water Reactor

Parts Common to all reactors

• REACTOR CORE – Part of the reactor where fuel is kept

• FUELS – Commonly used fuels are Uranium (233,235), Plutonium(239)

• SOURCE OF NEUTRONS – Mixture of polonium and beryllium powder

• MODERATORS – Materials used to slow down neutronse.g. – Heavy Water (D2O), Graphite

• CONTROL RODS – Used to control the no: of neutrons in the reactorse.g. – Boron, Cadmium

• SHIELD TO PROTECT RADIATION – protect living organism from harmful rays like gamma, some shields made of thick lead and concrete are used around the core and the reactor

• COOLANTS – To reduce the heat generated as part of reaction, some fluids like high pressure water liquids, metals and gases take heat out of the core

NUCLEAR FUSION

The process of merging two or more light nuclei to form a heavier nucleus is called NUCLEAR FUSION

Deuterium is a hydrogen isotope with mass number 2.At very high temperature Deuterium nuclei with high kinetic energy fuse to form Helium nucleus

Example for nuclear fusion

Energy liberated from sun, stars etc

Figures are given below

Galaxy

Energy Liberated from Sun