Download - chapter 6 nuclear energy.pptx
*Production of Nuclear Energy
• Energy produced from the changes in an
unstable nucleus
• Large amount of nuclear energy can be produced
through nuclear fission and nuclear fusion.
• Nuclear energy is converted into heat energy that can be used to generate electricity
Nuclear Energy
1) NUCLEAR FISSION分裂
• Process in which an unstable and heavy nucleus is bombarded 冲击 with a neutron
• Cause it to split into
2 Lighter nuclei- Release of neutrons &
energy
Only occur in some types of
heavy and unstable nuclei
Ex: uranium-235/plutonium-
239
• The neutron produced will bombard more uranium-235
• Process repeated and result in a chain reaction
• in nuclear reactor, chain reaction is controlled by
using boron rod to absorb neutron
• The speed o f neutrons slowed down by graphite core
2) NUCLEAR FUSION
• Process in which two light nuclei combine to form a heavier, more stable nucleus together with release of a large amount of energy
• However, it produces more nuclear energy than nuclear fission
• Used to make hydrogen bomb
The heat and light energy from Sun is due to fusion of hydrogen atoms at high temperature and pressure
(Hydrogen-2)
(Hydrogen-3)
ADVANTAGES & DISADVANTAGES
Advantage DisadvantageIt produces more nuclear energy
The rate cannot be controlled
Produce less radioactive radiation
Occurs at very high temperature and pressure
*Uses of nuclear energy
*Nuclear energy is used to produce electricity in a nuclear power station.
* Is used to:Generate electrical energy propel submarine operate satellites
*ADVANTAGES OF NUCLEAR ENERGY
Not emit poisonous gas
Cheaper compared to fossil fuel
Small quantities required
Not produce lots of wastes
*DISADVANTAGES OF NUCLEAR
ENERGY
Can damage living cells
Higher maintain cost
Produce radioactive wastes
People may abuse the use of nuclear energy
EFFECTS OF RADIOACTIVE RADIATION ON LIVING THINGS
SHORT TERM
• Radiation sickness
• Bone marrow suppression
• Internal bleeding, infertility
LONG TERM
• Kill body cells• Cause mutation• Foetal
deformation• Lead to cancer• Pollution
CORRECT WAY OF HANDLING
Never handle radioactive substances with bare hands
Workers who handle radioactive
substances should wear dosimeterFrequent checking for radiation leakageRadioactive wastes are stored in
thick concrete 固结成地 or thick lead container
Radioactive wastes•Small amount of short-lived radioactivity from hospitals, research institution
Low level
•Contain higher amount of radioactivity•radioisotopes
Intermediate level
•Highly radioactive and large amount of long-lived radioactivity
High level
*Effects of radioactive rays
*Irresponsible radioactive waste disposal will pollute the environment
Exposed over short period can cause nausea and vomiting / diarrhoea
Exposed over long period can destroy body cells, causes cancer and mutation as well as abnormalities in foetus
*Proper handling of radioactive substances &
radioactive waste
1. Radioactive substances are commonly kept in thick lead containers surrounded by thick concrete.
2. The storeroom where radioactive substances are kept must be labelled with the radioactive warning symbol.
3. Radioactive waste must be kept in a lead container that is sealed tightly.
Workers in a nuclear power station must wear protective clothings and dosimeters or film badges.
*The relevant authorities must enforce existing laws to ensure that the disposal of radioactive waste is done properly.