RADIOACTIVITY: The spontaneous disintegration of the nucleus of an unstable atom accompanied by radioactive emissions.

Radioactive elements will continue to emit radioactive emissions until its atoms become stable.

Types of radioactive emissions that can be emitted by the nucleus of unstable atoms

Alpha ( α ) particlesbeta (β ) particles

Gamma ( γ ) rays

Photographic detectors

Geiger-Muller tube (G-M tube)

Gold leaf electroscope

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

Diffusion Cloud Chamber

Radioactive emissions

Anα -particle A β-particle A γ -photon

Characteristics A helium nucleus

Consits of 2 protons and 2 neutrons

Very heavy compared to beta particle

High energy electron

Very much lighter than alpha particle

Electromagnetic waves

Very high frequency and short wavelength

Nuclide notation

He e γ

Charge Positively charge

+2e

Negatively charge

-e

Do not carry any charge

Number of ion pairs per cm of air

100 000 1000 10

Speed Moves slower than beta particle, up to about 10% the speed of light

Moves at very high speed, up to 99% of the speed of light

Moves with the speed of light

Ionising power Highest ionising power than the beta particle

Produce the most ion pairs in a medium

Lower ionising power than alpha particle because of its smaller mass and charge

Lowest ionising power

Tracks in cloud chamber

Penetrating power

Range in air α−particl e a few centimetresβ−particl e a few metresγ−ray s 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.

γ−raysβ−particleα−particle

-

+

α−particle

β−particle

γ−rays

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=mc 2E=energy released,in Joules(J)

m= mass defect

c=speed of light

Generation of Electricity from Nuclear Fission

Part Funtion/ExplanationUranium fuel rods It is split by neutron in a controlled

reaction,releasing a large amount of energyBoron control rods Absorbs neutron to reduce the rate of fission

reactionGraphite core Acts as a moderator to slow down the fast

neutrons to be captured by uraniumCoil 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

is minimal. It does not add to greenhouse effect.

Does not produce which affect health such as sulphur

Produce useful radioisotope to be used in industry,medicine, agriculture and research

There has been a very good safety record in the nuclear power production.

Need less fuel

It is expensive to design a nuclear power station.

Produce waste in the form of used fuel rods which are very hot and highly radioactive with half-life up to thousands of years

Hot water that is discharged from nuclear power station causes thermal pollution

People who work in the nuclear power station and those who live nearby may be exposed to excessive radiation

Nuclear fuel used to produce weapons of mass destruction

MANAGEMENT OF NUCLEAR MANAGEMENT

A) LOW-LEVEL WASTEB) INTERMEDIATE-LEVEL WASTEC) 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.