1. Fission and Fusion Nuclear power And you

2. YOU Have heard of nuclear reactions – but what are they???????????? Nuclear bombs Nuclear reactors The Sun

3. As you suspect: Nuclear reactions deal with the nucleus of the atom. Recall in our studies of radioactivity, that the nucleus of atoms can change Neutrons can change into protons Protons can change into neutrons α, β,, particles/radiation can be released!

4. Deal with more significant changes in the nucleus of the atom When these changes happen… VERY large amounts of energy are released ???? What kinds of reactions are you talking about here mister????? There are 2 types we will study here today. Nuclear Reactions

5. 1. Fission Fission = break apart a nuclei into smaller nuclei

6. How do you do it?? Start with a very large nucleus (like that of Uranium – 235. Then smack it with a n O 235 92 U + n O  236 92 U  142 56 Ba + 91 36 Kr + 3 n O Show fission video clip here…

7. The released neutrons go on to bombard other Uranium nuclei in the area. This results in a chain reaction The reaction is sustainable (critical) if the n O used to sustain reaction = n O produced ex: nuclear power plant No explosions here!

8. What if n O produced > than those needed to just sustain the reaction? Supercritical = when n O produced is great enough to sustain geometric progression. 1n O  3n O  9n O  27n O  …

9. Well just how much Energy is released? Show video clip Little boy, Nagasaki, nuclear bombs here

10. So where does all this energy come from??? Briefly – some mass from the atom is converted to Energy during this process – We will discuss this in more detail later The idea comes from this famous equation: E = mc 2

11. 2. Fusion Fusion = 2 small nuclei fuse to make one larger nuclei.

12. The Sun 4 1 1 H  4 2 α + 2 0 +1 e + Energy Protons  alpha particle + positron Advantage: less waste, less dangerous than fission Disadvantage: requires very high temps. to get going

13. More bombs… 2 1 1 H  4 2 He + 1 0 n + Energy High temps required to start process – use of small fission bomb to detonate fusion bomb!!!! Rocky Flats “triggers” Show Tsar bomb video here.