fission fusion

• what is radioactive contamination

  the presence of unwanted radioactive nuclei on materials
• what is irradiation

  the process of exposing a material to radiation , the material does not become radioactive
• what is nuclear fission

  the splitting of large unstable nuclei to form smaller , more stable nuclei (+ the emission of neutron
• what usually needs to happen to induce fission

  the unstable nuclei must absorb a neutron , spontaneous fission is rare
• alongisde 2 smaller nuclei , what else is emitted in a fission reaction

  2 or 3 neutrons , gamma rays , energy
• name a common fissile nucleus

  uranium 235
• what are the three components of the core of a nuclear reactor

  fuel rods , control rods , moderator
• what takes place during a chain reaction in a nuclear reactor

  an unstable nucleus absorbs a neutron , the nucleus undergoes fission and releases 2 or 3 more neutrons , these induce more fission , which results in a chain reaction
• what is the consequence of an uncontrolled chain reaction

  the rate of fission events become too high and result in the production of more energy , this can lead to a nuclear explosion
• how is the chain reaction in a fission reactor kept under control

  control rods are positioned in between the fuel rods , the rate of fission is controlled by moving these rods up and down , the lower the rods are inserted , the slower the rate of fission
• what is the role of the moderator in a nuclear reaction

  to slow down the neutrons so they are travelling at speeds which allow them to be absorbed by fissile nuclei and cause fission
• how is electricity produced in a nuclear power station

  thermal energy released due to fission , thermal energy used to heat water and produce steam , the steam is then used to a turn a turbine which starts a generator
• what is nuclear fusion

  when 2 light nuclei join to produce a heavier nucleus and release energy
• name two isotopes of hydrogen which are commonly used in nuclear fusion

  deuterium and tritium
• which releases more energy , nuclear fission or fusion

  nuclar fusion
• explain the difficulty generating energy through nuclear fusion

  fusion requires very high temperature which in itself require large quantities of energy , currently the use of fusion results in a net loss of energy
• give an example of when fusion occurs

  in the sun , stars use fusion as their energy source
• why does nuclear fusion require so much energy

  this is because both nuclei are positive therefore a lot of energy is required to overcome the electrosatic repulsion between the 2 positive nuclei
• how do control rods work

  the further they move down , the more neutrons they block slowing down the rate of nuclear fission as less neutrons will be absorbed