8.1 Energy Sources Flashcards
Define specific energy
The number of joules of energy that can be released per unit mass of fuel consumed
J/kg
Define energy density
The energy liberated per unit volume of fuel consumption
J/m^3
Typical efficiency of coal
Typical efficiency of oil
Typical efficiency of natural gas
35%
38%
45%
Advantages of fossil-fuel power stations
High energy density
Easy to transport
Can be used anywhere with good transport links & water availability
Can be used directly at home
Disadvantages of fossil-fuel power stations
Byproducts include greenhouse gases, causing pollution
Extraction of fossil fuels can damage environment
Non-renewable
Need large volume to store
Why do we have to slow down neutrons in a nuclear reactor?
Lower-energy neutrons favour fission
What is the critical mass for fission reactions?
The minimum mass needed to sustain a chain reacion
What affects the chances of a neutron causing fission? [2]
Number of potential nuclei ‘in the way’
Speed of neutrons
What is the purpose of the moderator in a nuclear reactor?
To slow down neutrons for reactions to happen
What is the purpose of a control rod in a nuclear reactor?
To absorb neutrons to control the chain reaction
What is the purpose of heat exchangers in a nuclear reactor?
Seals off environment to increase efficiency
What is the process of enrichment?
Increasing the percentage composition of Uranium-235 in the fuel rods
What the process of reprocessing?
Treating depleted fuel rods to recover uranium-238 and plutonium-239
What are 2 advantages of nuclear power?
Extremely high specific energy
Large reserves of uranium available
What are 4 disadvantages of nuclear power?
Produces radioactive nuclear waste
Large risk
Non-renewable
Health & safety risks
