Please enable JavaScript.
Coggle requires JavaScript to display documents.
p6 (chain reaction (nuclear fission of uranium can happen if a slow moving…
p6
chain reaction
-
addition of a neutron makes the nucleus unstable, causes a split
each time a uranium nucleus splits, it spits out two or three neutrons, some of which might be absorbed by other nuclei, causing them to split too, causing a chain reaction
nuclear power stations generate electricity from chain reactions, using uranium or plutonium as fuel
the energy which is released in the chain reaction is used to heat water to make steam, which is used to drive a steam turbin connected to an electricity generator
the main problem with nuclear power is the disposal of waste, products left over after fission are highly radioactive and have long half lives
-
nuclear fuel is cheap, overall cost of nuclear power is high due to the cost of the power plant and the final decommissioning, dismantling a nuclear power plant safely takes decades
-
nuclear fusion
two light nuclei can join to create a larger nucleus, eg two hydrogen nuclei can fuse to form a helium nucleus
releases a lot of energy, more than fission, all the energy released in stars comes from fusion
energy is due to a difference in mass between the original nuclei and the new nucleus, eg total mass of the hydrogen nuclei is greater than the total mass of the helium nucleus
extra mass converted into the energy and carried away by radiation, mass of the nuclei before fusion will always be larger than the mass of the nucleus after fusion
doesn't create radioactive waste, plenty of hydrogen knocking about to use as fuel, people trying to develop fusion reactor to generate electricity
only happens at really high temps, about 10 000 000 degrees celsius, and high pressures, to keep hydrogen in these conditions, need an extremely strong magnetic field
few experimental reactors, none generating electricity yet
nuclear fission
type of nuclear reaction that releases energy from large and unstable nuclei eg uranium and plutonium, by splitting them into smaller nuclei
-
-
when a large nucleus splits it forms two new smaller nuclei, usually radioactive, and possibly a few neutrons
nucleus splitting gives out a lot of energy, some transferred to the kinetic energy stores of the fission products
-
cancer internally
implants containing beta emitters placed next to or inside the tumour, the beta particles damage the cells in the tumour, but have a short enough range that the damage to healthy tissue is limited
an implant with a long half life should be removed to stop the radiation killing healthy cells once the cancerous cells have been killed
is the half life is short enough, the implant can be left in
alpha emitters can be injected into a tumour, alpha particles are strongly ionising, so they do lots of damage to the cancer cells
have a short range, damage to normal tissue is limited