Adam Smalley

 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

 Discuss how neutron capture by a nucleus of uranium-238 ( 238 U) results in the production of a nucleus of plutonium-239 ( 239 Pu)  Describe the importance of plutonium-239 ( 239 Pu) 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

CONTROLLEDUNCONTROLLED

 Fuel needed: uranium-235  Most abundant isotope: uranium-238  Solution: Induced fission!

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- 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 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

 Fast neutrons produced in a fission reaction may be used to bombard uranium-238 and produce plutonium-239  This isotope does not occur naturally

 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)

 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

 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.

 13 a, b