Radioactivity is the spontaneous disintegration of an unstable atom's nucleus accompanied by radioactive emissions. There are three main types of emissions: alpha particles, beta particles, and gamma rays. Radioactive elements will continue emitting emissions until their atoms become stable. Various detectors can detect different radioactive emissions, like Geiger-Muller tubes detecting beta particles and gamma rays. Radioactive decay is when an unstable nucleus changes into a more stable one by emitting radiation. Nuclear fission and fusion involve splitting or combining atomic nuclei and release energy. Nuclear power plants use controlled fission to generate electricity while producing radioactive waste that must be carefully managed.

1. RADIOACTIVITY: The spontaneous disintegration of the nucleus of an unstable atom
accompanied by radioactive emissions.
Types of radioactive
emissions that can be
emitted by the nucleus of
unstable atoms
Alpha ( ) particles Gamma ( ) rays
beta ( ) particles
Radioactive elements will continue to emit radioactive
emissions until its atoms become stable.

2.  Photographic detectors
 Geiger-Muller tube (G-M tube)
 Gold leaf electroscope

3.  Diffusion Cloud Chamber
The radioactive emissions that can be detected by the various detectors :
Detectors Radioactive emissions detected
Photographic detectors Alpha particles,beta particles,gamma rays
Geiger-Muller tube (G-M tube) Beta particles,gamma rays
Diffusion Cloud Chamber Alpha particles,beta particles,gamma rays
Spark counter Alpha particles
Gold leaf electroscope Alpha particles

4. Radioactive An -particle A -particle A -photon
emissions
Characteristics A helium High energy Electromagnetic
nucleus electron waves
Consits of 2 Very much Very high
protons and lighter than frequency and
2 neutrons alpha particle short wavelength
Very heavy
compared to
beta particle
Nuclide He e
notation
Charge Positively Negatively Do not carry any
charge charge charge
+2e -e
Number of ion
pairs per cm of 100 000 1000 10
air
Speed Moves slower than Moves at very high Moves with the speed of
beta particle, up to speed, up to 99% of light
about 10% the the speed of light
speed of light
Ionising power Highest Lower Lowest ionising
ionising ionising power
power than power than
the beta alpha particle
particle because of its
Produce the smaller mass
most ion and charge
pairs in a
medium

5. Tracks in cloud
chamber
Penetrating
power
Range in air a few centimetres
a few metres
a few hundred metres
Effect of electric
field -
+
RADIOACTIVE DECAY: A process in which unstable nucleus changes into
a more stable nucleus by emitting radiation.

6.  The mass of an atom is measured in a unit called the atomic mass unit (a.m.u)
Nuclear fision
 A process in which a heavy nucleus splits into two or more light nuclei.
Nuclear fusion
 Defined as the combining of two lighter nuclei to form a heavier nucleus.
 A very high temperature in the sun cause the light hydrogen isotopes to move at extremely
high speeds.This enables 2 hydrogen nuclei to overcome the repulsion between them an
collide.
 Thus, causing them to combine together to produce a heavier nucleus.
Chain reactions
 Is a self-sustaining reaction in which the product of a reaction can initiate another similar
reaction.
 The uranium sample must have a certain minimum mass to sustain the reaction.
 Minimum mass=Critical mass
Energy in nucler reaction
 Mass of the product of the reaction < Mass before reaction
 Loss of mass due to the mass that has converted into energy .
 Loss in mass = Mass defect
 Relationship between mass and the energy :
E=energy released,in Joules(J)
2
E=mc m= mass defect
c=speed of light

7. Generation of Electricity from Nuclear Fission
Part Funtion/Explanation
Uranium fuel rods It is split by neutron in a controlled
reaction,releasing a large amount of energy
Boron control rods Absorbs neutron to reduce the rate of fission
reaction
Graphite core Acts as a moderator to slow down the fast
neutrons to be captured by uranium
Coil and magnet The coils is rotated by the turbines.Electricity is
generated by electromagnetic induction.
Advantages and disadvantages of using nuclear energy
ADVANTAGES DISADVANTAGES
The emissions of carbon dioxide It is expensive to design a
is minimal. It does not add to nuclear power station.
greenhouse effect.
Produce waste in the form of
Does not produce which affect used fuel rods which are very
health such as sulphur hot and highly radioactive with
half-life up to thousands of years
Produce useful radioisotope to
be used in industry,medicine, Hot water that is discharged
agriculture and research from nuclear power station
causes thermal pollution
There has been a very good
safety record in the nuclear People who work in the nuclear
power production. power station and those who
live nearby may be exposed to
excessive radiation
Need less fuel
Nuclear fuel used to produce
weapons of mass destruction
MANAGEMENT OF NUCLEAR MANAGEMENT
A) LOW-LEVEL WASTE
B) INTERMEDIATE-LEVEL WASTE
C) HIGH-LEVEL WASTE
General principles in the management of radioactive waste:
Concentrate-and-contain: the waste is compacted to a smaller volume and stored in isolated place.
Dilute-and-disperse: the waste is diluted to safe levels of concentration and discharged to the
environment.
Delay-and-decay: the waste stored in a safe place and left to decay until it reaches a safe level of
radioactivity.This could take many years.