Fusion

The main problem with fission is there's lots of horrid radioactive mess to clean up afterwards. This is why scientists have been looking into producing energy the same way stars do - through fusion!

Debate: What are the pros of Nuclear Power? [5]
- Fossil fuels (coal, oil and gas) all release Carbon Dioxide when they're burnt. Nuclear power does not release carbon dioxide.
- - What is so bad about this? [1]
    - This adds to the greenhouse effect and global warming.
- Burning coal and oil also releases sulfur compounds. Nuclear power does not release sulfur compounds.
- - What can this cause? [1]
    - Acid rain
- There are a few safe ways to dispose of radioactive nuclear waste.
- - Such as? [1]
    - One way is to pack the waste into thick metal containers, put the containers in a very deep hole, then fill the hole with concrete
- Building a nuclear power plant can have a very positive impact on the local area. Both the plant itself and the support industries that sprin up around it
- - How does this benefit the local area? [1]
    - This brings lots of skilled jobs to rural areas
- Nuclear fuel (i.e. the Uranium) is cheap and it can last a couple of years before running out
- - Can you re-use or recycle the fuel rod after its been depleted? [1]
    - Yes! Because its radioactive, some nuclear waste is used in hospitals (medical tracers, sterilisation, etc)
Debate: What are the cons of Nuclear Power? [3]
- The main environmental problem is with the disposal of waste.
- - Why can't you just throw it away like other rubbish? [1]
    - The products left over after nuclear fission are generally radioactive, so they can't just be thrown away.
      - How long does this waste stay dangerously radioactive? [1]
        
        For hundreds of years - and some people worry that materials could leak out of the storage facilities over time
- Nuclear power always carries the risk of leaks from the plant or major catastrophe
- - But the chances of this are so rare! When has this ever happened before? [1]
    - Chernobyl
- The overall cost of nuclear power is high
- - Why? I thought the fuel is cheap? [1]
    - Yes - but the cost of the power plant buing built safely and final decommissioning is costly. (Dismantling a nuclear plant safely takes decades)
What is fusion? [1]
- Two light nuclei (e.g. hydrogen) "joining" to create a larger nucleus (the exact opposite of fission)
  - Why would you want to do this? [1]
    - Fusion releases a lot of energy. more than fission "pound for pound" (for the same mass of fuel)
      - How is it possible for nuclei to "release" energy by fusing together? [1]
        
        It's to do with Einstein's equation; E = m c²
        
        This tells us that mass can be changed into Energy (and vice versa)
        
        In fact, a small amount of mass is converted into a huge amount of energy!
        
        The funny thing is that when the nucleons (protons + neutrons) are separate, they weigh more (have more mass) than when they are fused together in a nucleus! - As they fuse, some mass is lost! And this is what's released as energy
  - Does fusion create a lot of radioactive waste? [1]
    - None - the products of two Hydrogen nuclei fusing together is ordinary Helium (and there's no shortage of finding Hydrogen for fuel)
  - So if fusion is so much better than fission, why don't we just use fusion reactors in power plants? [1]
    - Fusion can only happen at really high temperatures - (over 10 million ºC). No material can stand that kind of temperature without being vaporised. So fusion reactors are really hard to build
      - So how can you build them without the walls vaporising? [1]
        
        You have to contain the hot hydrogen fuel in a magnetic field instead of a physical container
        
        So what's the problem? [1]
        
        The power required to heat up the hydrogen and run the magnetic field is more than what is released from the fusion reaction
Controversial Cold Fusion - What is it? [1]
- Nuclear fusion which occurs at room temperature!
  - Who discovered it? [2]
    - In 1989 two scientists, Stanly Pons and Martin Fleischmann claimed to have released energy from cold fusion using a simple experiment
  - Why did this discovery cause a lot of excitement? [1]
    - Cold fusion would make it possible to generate lots of electricity, easily and cheaply.
  - Why are many scientists sceptical of cold fusion? [1]
    - The results have never been repeated reliably enough to be accepted by the scientific community
  - Is Cold fusion a hoax? [1]
    - Not all scientists have given up on Cold fusion. There's still lots of research into this field, even to this day...

Classwork
- 1) What is the main environmental problem associated with nuclear power?
- 2) What is nuclear fusion?
- 3) Why is it difficult to construct a working fusion reactor?
- 4) What is cold fusion?
- 5) Research cold fusion further and produce a newspaper article on it. Include three unique facts you have discovered and address the following: (what's the difference between cold fusion and fusion? why are so many scientists skeptical towards cold fusion? what would the future be like if cold fusion was readily available in every house?)
Homework
- 1) Radioactive waste left over from nuclear fission is very difficult to dispose of
  - Why is the waste produced by nuclear power stations such a long-term problem?
  - Describe one way of disposing of high-level radioactive waste
- 2) Indicate whether the following statements are true or false. Write out the correct versions of any false statements
  - Nuclear fusion involves small nuclei joining together
  - A nuclear fission reaction releases more energy than a nuclear fusion reaction
  - Fusion reactors produce lots of radioactive waste
  - Only a few experimental fusion reactors are generating electricity
- 3) The energy released in stars comes from fusion
  - Write down one condition needed for fusion to take place
  - Fusion reactors are extremely hard to build. Why can the 'fuel' used not be held in a physical container?
  - How are fusion reactors built to get around this problem?
  - Explain in terms of energy input and output why fusion reactors aren't in widespread use yet
  - In 1989 two scientists claimed to have released energy through cold fusion. Suggest why the report caused such excitement

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Fusion

The main problem with fission is there's lots of horrid radioactive mess to clean up afterwards. This is why scientists have been looking into producing energy the same way stars do - through fusion!

Debate: What are the pros of Nuclear Power? [5]

Debate: What are the cons of Nuclear Power? [3]

What is fusion? [1]

Controversial Cold Fusion - What is it? [1]

Classwork

Homework