Flashcards in 8.2 Nuclear Power Deck (11):
How much energy is produced from nuclear fuels?
What is a nuclear reactor?
A machine which nuclear reactions take place producing energy. The fuel of the reactor is typically uranium 235.
What is a chain reaction?
The fast neutrons produced in the fission of U235 are then slowed down when they collide with other U235 nuclei in the reactor producing more fission, energy and neutrons. The reaction is thus self sustaining.
What is the critical mass?
The minimum mass of U 235 for a chain reaction to sustain itself, with a lower mass many neutrons escape without causing further reactions.
What is uranium enrichment?
The uranium commonly mined us U238 which contains small traces of U235 enrichment is the process of increasing the contraption of the useful U235 in uranium samples. For nuclear power plants the concentration is increased to 5%.
What are fuel rods?
Rods containing the nuclear fuel in pellet or powder firms. In the case of uranium the fuel rods contain a mixture of fissionable U235 and non fissionable U238.
What are control rods?
These rods can be inserted to absorb excess neutrons in order to control the rate of the fission reaction.
What is a moderator?
The neutrons produced in the fission reaction must be slowed down if they are to be used to cause further fissions. This is achieved through collisions of the neutrons with atoms of the moderator, the material surrounding the fuel rods.
What is a heat exchanger?
The kinetic energy of the reaction products is converted to thermal energy in the moderator. A coolant passing through the moderator can extract this thermal energy and use it to turn to steam at high temperature and pressure. This can be used to turn the turbines of a power station producing electricity.
What are advantages of energy production by nuclear fission?
High power output (high energy density)
Large available reserves of nuclear fuel]
No greenhouse gas emissions