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PL.Sriram

Nuclear reaction

Nuclear Fission

Chain reaction

Controlled

reaction

Uncontrolled

rection

Nuclear fusion

Reaction

Physical reaction

Involves a change in the nucleus of an atom

Two types –Fission and fusion.

Source – Mass of the nucleus

Released mainly in the form of heat energy

Known as atomic energy

17Cl35 + 0n1 15P32 + 2He4 + High energy

When Uranium 235 atoms are bombarded with slow moving neutrons,the heavy uranium nucleus breaks up to produce two medium-weight atoms ,neutrons and a tremendous amount of energy.

92U235 + 0n1

56Ba139 +

36Kr94 + 30n1 + High energy

E =Mc2

FISSION AND FUSION

German scientist otto hann and strassman discovered that when a 92U235 nucleus is bombarded by thermal neutrons,it splits up into two smalller nuclei of barium and Krypton along with the release of three neutrons

Nuclear fission Fission means ‘to split’

The process in which the heavy nucleus of a radioactive atom (such as uranium,thorium and plutonium) splits up into smaller nuclei when bombarded with low energy neutrons is known as nuclear fission.

The sum of masses of the smaller nuclei formed in a fission reaction is a little less than that of the mass of the original heavy nucleus

So,there is a small loss of mass in the nuclear fission process.

Nuclear fission

This energy is used for generating electricity.

Neutrons may:1 - Cause another fission by colliding with a U235 nucleus

Each split (fission) is accompanied by a large quantity of E-N-E-R-G-Y

• Creates two smaller nuclides and free neutrons• The free neutrons potentially collide with nearby U235 nuclei• May cause the nuclide to split as well

Chain reaction

When the neutrons in the fission reaction continuously bombard with heavy nuclei then , a continuous self sustaining nuclear chain reaction happens.

Sometimes,I t becomes uncontrolllable and that is the atom bomb.

To control it boron rods are used because boron has the property to absorb neutrons.

Chain reaction

U.S. Electrical Power Production by Source

Review

Nuclear fission:

A large nucleus splits into several small nuclei when impacted by a neutron, and energy is released in this process

Nuclear fusion:

Several small nuclei fuse together and release energy.

Advantages

Produces tremendous energy from a small amount of nuclear fuel.

Once the nuclear fuel is filled,the plant can go for years together.

Does not produce greenhouse gases like CO2

Difficult to dispose the radioactive waste from the nuclear fission reaction.

Risk of accidents in Nuclear reactors

High cost of installation of nuclear power plants and limited availability of uranium.

Disadvantages

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