Small

• Explain why the process of nuclear fusion is so difficult to achieve.

  Nuclei need to get very close for nuclear fusion to occur. This means strong electrostatic repulsion results in positive charges repelling 
• Define what is meant by ‘chain reaction’

  Neutrons released from fission reaction, absorbed by more uranium nuclei that also undergo fission, more than one neutron released per fission reaction, more and more fission reaction. This leads to an explosion 
• The unstable isotope undergoes fission by absorbing a neutron.
• Explain what is meant by a medical tracer and how it is used.

  A medical tracer is a radioactive solution

  that contains a gamma-emitting radioisotope. It is injected into the patient and is then absorbed by the organ being examined. A special camera detects the gamma radiation emitted by the solution. The detected waves are used to build up an image of where the radioisotope is located in the organ.
• Why are radioactive samples handled with tongs?

  So they can be held as far away as possible, and point away from anyone.
• 3 precautions taken to reduce the the risk of cell damage for people who come into contact with ionising radiation:

  1. Wear gloves/lead apron
  2. Limit distance of isotope to person
  3. Limit time spent near isotope
  4. Store the radioactive material in a concrete box
• External contamination:

  Holding or touching a radioactive source, eg soil
• Describe why the siren sounds when a smoke gets into the smoke alarm

  The smoke the alpha particles, which lose their charge and this means that they are not detected and the bell sounds.
• A beta particle is when…

  A high energy electron is emitted from the nucleus (after a neutron turns into a proton)
• Explain why the use of dense shielding materials could reduce ionisation in the body by radioactive particles and waves.

  When there is a collision with the radioactive particles, they lose their energy, and ionise the shielding atoms instead of the body atoms. Denser shielding means there is a greater chance of collision, so there is a reduction of energy through harmful radiation.
• When talking about radioactivity I always forget to talk about….

  CHARGE
• Four ways atoms become ions:

  Ionisation, electrolysis, reactions, friction
• • A plastic lid is a good insulator for a flask‘s cap because it stops evaporation.
  • Conduction and convection require a medium
  • A silver lining won’t emit radiation
• Advantages of biogas on farm:

  Renewable, non-weather dependant (reliable), concentrated energy source, short payback time, no transport cost
• Advantages of gas instead coal:


  No particulates, no sulphur dioxide, gas mining is less destructive
• Disadvantages of nuclear power stations:

  Radioactive remains for a long time, it must be buried and the fuel is non-renewable
• Why are gasses easy to compress?

  There are large gaps between the particles, so they are easy to push together.
• In a solid, the strong intermolecular forces of attraction hold the particles close together.
• 1GW = 1 x 10^ 9 W
• Proton mass = 0.0005

  Typical radius of an atom = 10 x 10 ^ -10 m

  The radius of the nucleus is 10,000 smaller
• How the atomic model has changed over time:

  • 1800: Dalton proposed atoms as tiny spheres
  • 1897: JJ Thomson discovered the electron, forming the Plum Pudding Model
  • 1911: Rutherford realized most of the atom was empty space
  • 1913: Rutherford Model with a positive nucleus and negative electrons in a cloud
  • 1913: Bohr produced the final model of the atom
  • 20 years later, James Chadwick provided evidence for the existence of neutrons
• Americum is used in smoke detecors
• net decline = (initial number - number of X half lives) / initial number
• Contamination lasts for an extended period. The radiation source is transferred to an object, resulting in the unwanted presence of radioactive atoms on materials. This radioactive contamination becomes hazardous as the decay of contaminated atoms releases radiation. For instance, when radioactive dust settles on your skin, it leads to skin contamination.
• Irradiation is short. The radiation source emits radiation, reaching an object and exposing it to nuclear radiation without making it radioactive. For example, when radioactive dust emits beta radiation, it "irradiates" the skin. Medical items are sometimes irradiated to kill bacteria on their surface without making the tools themselves radioactive.
• The measurement of radiation dose is quantified in Sieverts (Sv).
• • Count-rate is the number of decays recorded each second by a detector (eg Geiger-Muller tube).
• 1000 millisieverts (mSv) = 1 sievert (Sv)
• fission

  A) Moveable control rod

  B) Concrete shield

  C) Nuclear fuel

  D) Graphite core

  E) Reactor vessel

  
• It's hard to connect houses that are far away to the natioanl grid because

  • There's a high cost to install
  • The long cables needed are expensive
• Nuclear waste remains dangerous for a long time. It must be buried. Nuclear fuel in non-renewable.
• A short start-up time allows for surges in demand and energy can be stored for a later use.
• Energy = charge x voltage