nuclear fission and dusion Flashcards
(17 cards)
explain the process of nuclear fission
- uranium nucleus absorbs a neutron
- the nnucleus becomes unstable and splits into 2 daughter nuclei, several neutrons and releases energy.
explain the process of nuclear fusion
- two light nuclei join together/combine
- to form a heavier nucleus, releasing energy in the process
what r the conditions neessary for nuclear fusion to occur
extremely high temp and hioigh pressure
why r these conditions needed for fusion to occur
-nuclei r positively charged and the high temperature and pressure is needed to overceom the electrostatic repulsion between the nuclei
why is nuclear fusion more desirable than nuclear fission
- there is more energy released per kg of fuel
- the produce of fission are radioactive and need careful disposal/ product of fusion are not radioactivd
what is the moderator made from
water(or graphite)
what does the mdoerator do?
The moderator slows down neutrons so they can be absorbed by the uranium nucleus more easily, sustaining the chain reaction.( increase chance of absorption)
what are control rods made of
boron/cadmium
they absroeb neutrons, helping to control the rate of nuclear fission reaction.
what is the role of the shielding
to absorb harmful radiation released by the radioactive products of fission
what are fuel rods?
they contain the radioactive material, usually uranium235 or plutonium239 which undergoes nuclear fission to release energy.
what is the shielding made of
concrete
what is the role of the contorl rod
to absorb excess neutrons and contol rate of fission
how is radioactive waste disposed of and the potential concerns? (4)
- strong containers than cant rust (but rust-proof containers are difficult and expensive to manufacture)
-in waste sites (not veery secure) - sea water - dilution
- stored underground/away from people
what are advantages of using nuclear fission power stations compared to coal-firred pwoer stations
- no greenhouse gases produced
- large amount of energy is released from a small amount of fuel
- low fuel costs compared to fossil fuel power plants
what are disadvantages of using nuclear fission power stations comapred to coal-fired power stations
-risk of nuclear accidents
- nuclear fission power stations produce radioactive asteroids
- nuclear poswer stationns are expensive to build
why is there a thick concrete shielding
- radioactive products release gamma radiation which i sharmful
- shielding absorbs teh gamma radiation
- needs to be thick concrete as gamma is highly penetrating
what are 2 disadvantages of using nuclear fission power stations?
- nuclear fission power stations produce radioactive waste
-risk of nuclear accidents/meltdown
-nuclear pwoer stations are expensive to build
