3

1

2

4

Atomic Mass Unit

Energy in Nuclear Reaction

Nuclear Fission

Nuclear Power Plant Utilisation

5

Nuclear Fusion

6

Electricity Generation from Chain Reaction

a.m.u is usually used to quantify the mass of subatomic particles like protons, neutrons and electrons.

1 a.m.u is equal to 1/12 of the mass of carbon-12 atom.

a.m.u can also be written as u.

1 u = 1/12 x mass of one carbon-12 atom= 1/12 x 1.99265 x 10-26 kg= 1.66 x 10-27 kg

Useful in computation of energy released in nuclear reaction.

Splitting of a heavy nucleus into two lighter

nuclei

neutrontarget

nucleus

neutron

neutron

neutron

fission product

fission product

Release enormous amount of

energy

A few hundred million times the energy released in an equivalent chemical reaction.

kinetic fragments

n

n n

nn

n

n

Combining of two lighter nuclei to form a heavier nucleus Initially, under an applied force, 2 lighter nuclei fuse together to form a heavier nucleus and energy. At a critical level, the energy released can self sustain the fusion reaction. Neutron

Deuterium Helium

Tritium

Energy

Energy released in nuclear fusion is very much more than in nuclear fission

Appear as kinetic energy of heavier nucleus and energy of neutron, proton or gamma rays

10 g

4 g

5.9999 g

ENERGY

Mass and energy are not conserved separately.

The total “mass-energy” before and after the exchange is conserved.

They can be exchanged from one form to the other.

E= mc2

energy released (J)

speed of light= 3.00 x 108 ms-1

loss of mass or mass defect (kg)

Example

Mass defect, m = 226.025406 u – (222.017574 u + 4.002603 u)= 0.005229 u= 0.005229 x 1.66 x 10-27 kg= 8.68 x 10-30 kg

Therefore, energy released, E = mc2

= 8.68 x 10-30 x (3.00 x 108)2

= 7.81 x 10-13 J

226Ra

88

222 4Rn + He

86 2Ra = 226.025406 u, Rn = 222.017574 u,

He = 4.002603 u, 1 u =1.66 x 10-27 kgc = 3.00 x 108 ms-1

222226

4

2

88 86

Trigger chain reaction

Release enormous energy

Energy conversion in reactor

Electricity generation

Water reactors Generation III reactors

Boiling water reactors

Gas-cooled reactors

Pressurised water reactors

Pressurised heavy-water reactors

Light water reactors

Heavy water reactors

High temperature gas-cooled reactors

Fast neutron reactors

Boiling water reactor

Pressurised water reactor

Pressurised Heavy-Water Reactor

Light-water graphite-moderated reactor

Liquid-Metal-Cooled Fast-Breeder Reactor (LMFBR)

Heavy Water Reactor

High Temperature Gas-Cooled Reactors

Fast neutron reactor

nuclei split by

neutrons, releasing

large amount of

energy Prevent radiation

leakage from reactor core

rotated by flow of

steam under high

pressure

absorb neutrons. Reduce rate of fission

reactionmoderator slow down neutrons

produced by fission

coils rotated by turbines. Electricity

generated by electromagnetic

induction

Boil water into

steam

GCR: Function

Layout of GCR

Fission of uranium-235 nuclei produces energy in the form of heat

Gas passing through the reactor core is heated up

Heat energy from the hot gas boils the water into steam

Flow of steam drives the turbines

Turbines turn the coils in the generator to produce electricity

Cold gas goes back to the reactor core to be heated again

Steam condenses back to water

GCR: Process flow

Nuclear energy from fission

Heat energy carried by the hot gas

Kinetic energy of the steam

Kinetic energy of the turbines

Electrical energy

Energy conversions in GCR

More than 400 nuclear power stations, producing 17% of the world’s electricity

East & South Asia, more than 100 nuclear power reactors in operation

29% 38%

Exposure to excessive radiation

Expensive Misused as

weapons of mass destruction

Minimal carbon dioxide emission

More stable price compared to fossil fuel

Need less fuel

Advantages Disadvantages