Adam Smalley. Describe how neutrons produced in a fission reaction may be used to initiate further...
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Transcript of Adam Smalley. Describe how neutrons produced in a fission reaction may be used to initiate further...
NUCLEAR ENERGY
Adam Smalley
Objectives
Describe how neutrons produced in a fission reaction may be used to initiate further fission reactions (chain reactions)
Distinguish between controlled nuclear fission (power production) and uncontrolled nuclear fission (nuclear weapons)
Describe what is meant by fuel enrichment Describe the main energy transformations that
take place in a nuclear power station Discuss the role of the moderator and the control
rods in the production of controlled fission in a thermal fission reactor
Objectives (Cont)
Discuss how neutron capture by a nucleus of uranium-238 (238U) results in the production of a nucleus of plutonium-239 (239Pu)
Describe the importance of plutonium-239 (239Pu) as a nuclear fuel
Discuss safety issues and risks associated with the production of nuclear power
Outline the problems associated with producing nuclear power using nuclear fusion
Solve problems on the production of nuclear power
Nuclear Fission
CONTROLLED UNCONTROLLED
Fuel Enrichment
Fuel needed: uranium-235 Most abundant isotope: uranium-238 Solution: Induced fission!
Chain Reactions
https://www.youtube.com/watch?v=vjqIJW_Qr3c
Energy Transformations- Water is heated by heat energy created through nuclear fission- Energy is lost to surroundings- Steam turns a turbine (heat energy transformed into kinetic energy)- Energy is lost to friction- Turbine powers a generator- Energy is lost to friction- Energy is transformed into electrical energy
Moderator & Control Rods
Moderator surrounds the fuel rods
Usually graphite or water.
Helps slow down the neutrons by having them collide with the atoms of the moderator
Control rods absorb excess neutrons
Can be removed/added as needed
Plutonium
Fast neutrons produced in a fission reaction may be used to bombard uranium-238 and produce plutonium-239
This isotope does not occur naturally
Plutonium (Cont)
Importance of these reactions is that non-fissionable material (uranium-238) is being converted to fissionable material (plutonium-239) as the reactor operates.
The plutonium-239 can be used as nuclear fuel in other reactors (or in nuclear weapons)
Problems with Nuclear Reactors
Radioactive waste hard to dispose of Major public health hazard should
‘something go wrong’ Problems associated with uranium mining
(radioactive dust particles) Possibility of producing materials for
nuclear weapons
Nuclear Fusion
It’s not yet possible to get more energy than is initially put into a fusion reaction.
Also at the high temperatures, plasma develops and must be kept in a magnetic chamber.
Problems
13 a, b