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 atomsAlpha ( ) particles Gamma ( ) rays beta ( ) particles Radioactive elements will continue to emit radioactive emissions until its atoms become stable.
Diffusion Cloud ChamberThe radioactive emissions that can be detected by the various detectors :Detectors Radioactive emissions detectedPhotographic detectors Alpha particles,beta particles,gamma raysGeiger-Muller tube (G-M tube) Beta particles,gamma raysDiffusion Cloud Chamber Alpha particles,beta particles,gamma raysSpark counter Alpha particlesGold leaf electroscope Alpha particles
Radioactive An -particle A -particle A -photonemissionsCharacteristics 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 particleNuclide He enotationCharge Positively Negatively Do not carry any charge charge charge +2e -eNumber of ionpairs per cm of 100 000 1000 10airSpeed 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 lightIonising 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
Tracks in cloudchamberPenetratingpowerRange in air a few centimetres a few metres a few hundred metresEffect of electricfield - + RADIOACTIVE DECAY: A process in which unstable nucleus changes into a more stable nucleus by emitting radiation.
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 massEnergy 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
Generation of Electricity from Nuclear FissionPart 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 energyADVANTAGES 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 destructionMANAGEMENT OF NUCLEAR MANAGEMENT A) LOW-LEVEL WASTE B) INTERMEDIATE-LEVEL WASTE C) HIGH-LEVEL WASTEGeneral 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.