Topic 7 - Nuclear Fission and Fusion Flashcards
what is nuclear fission?
the splitting of an atom, releasing energy
what happens when a slow-moving neutron is absorbed by a uranium-235 nucleus?
the nucleus can split, producing a small number of neutrons and two daughter nuclei lighter than uranium
why does nuclear power produce nuclear waste?
the daughter nuclei are usually radioactive
how does nuclear energy drive a turbine?
nucleus splitting gives out a lot of energy
how are neutrons slowed down to be absorbed by uranium nuceli?
the moderator
what do control rods do?
limit rate of fission by absorbing excess neutrons
why is shielding used in nuclear reactors?
the high energy neutrons and gamma rays released are ionising
what is nuclear fusion?
two light nuclei colliding to create a larger, heavier nucleus
does the heavier nucleus formed in fusion have as much mass as the 2 light nuclei?
no - some mass is converted to energy and released
how much energy is released in fusion?
a lot, more than fission
what conditions does fusion need?
very high pressures and temperatures, because the positively charged nuclei need to get very close so need to overcome the electrostatic repulsion
