1. © Copyright Pearson Prentice Hall Slide 1 of 20 Fission and Fusion of Atomic Nuclei The sun is not actually burning. If the energy given off by the sun were the product of a combustion reaction, the sun would have burned out approximately 2000 years after it was formed, long before today. You will learn how energy is produced in the sun. 25.3

2. © Copyright Pearson Prentice Hall Fission and Fusion of Atomic Nuclei > Slide 2 of 20 Nuclear Fission splitting of a nucleus into smaller fragments 25.3

3. Slide 3 of 20 © Copyright Pearson Prentice Hall Fission and Fusion of Atomic Nuclei > Nuclear Fission When the nuclei of certain isotopes are bombarded with neutrons, they undergo fission, 25.3

4. © Copyright Pearson Prentice Hall Slide 4 of 20 Fission and Fusion of Atomic Nuclei > Nuclear Fission Chain Reactions some of the neutrons produced react with other fissionable atoms, producing more neutrons which react with still more fissionable atoms. 25.3

5. © Copyright Pearson Prentice Hall Slide 5 of 20 Fission and Fusion of Atomic Nuclei > Nuclear Fission 25.3

6. Slide 6 of 20 © Copyright Pearson Prentice Hall Fission and Fusion of Atomic Nuclei > Nuclear Fission 25.3 A Nuclear Power Plant

7. Slide 7 of 20 © Copyright Pearson Prentice Hall Fission and Fusion of Atomic Nuclei > Nuclear Fission Neutron Moderation -is a process that slows down neutrons so the reactor fuel (uranium-235 or plutonium-239) captures them to continue the chain reaction. 25.3

8. Slide 8 of 20 © Copyright Pearson Prentice Hall Fission and Fusion of Atomic Nuclei > Nuclear Fission Neutron Absorption - is a process that decreases the number of slow-moving neutrons. Control rods, made of a material such a cadmium, are used to absorb neutrons. 25.3

9. © Copyright Pearson Prentice Hall Fission and Fusion of Atomic Nuclei > Slide 9 of 20 Nuclear Waste spent fuel rods from a nuclear reaction stored in water 25.3

10. Slide 10 of 20 © Copyright Pearson Prentice Hall Fission and Fusion of Atomic Nuclei > Nuclear Waste -Water cools the spent rods -also acts as a radiation shield to reduce the radiation levels. 25.3

11. © Copyright Pearson Prentice Hall Fission and Fusion of Atomic Nuclei > Slide 11 of 20 Nuclear Fusion How do fission reactions and fusion reactions differ? 25.3

12. Slide 12 of 20 © Copyright Pearson Prentice Hall Fission and Fusion of Atomic Nuclei > Nuclear Fusion Fusion- nuclei combine to produce a nucleus of greater mass. In solar fusion, hydrogen nuclei (protons) fuse to make helium nuclei and two positrons. 25.3

13. © Copyright Pearson Prentice Hall Slide 13 of 20 Fission and Fusion of Atomic Nuclei > Nuclear Fusion Fusion reactions, release much more energy than fission reactions 25.3

14. Slide 14 of 20 © Copyright Pearson Prentice Hall Fission and Fusion of Atomic Nuclei > Nuclear Fusion The use of controlled fusion as an energy source on Earth is appealing. The potential fuels are inexpensive and readily available. The problems with fusion lie in achieving the high temperatures necessary to start the reaction and in containing the reaction once it has started. 25.3

15. © Copyright Pearson Prentice Hall Slide 15 of 20 25.3 Section Quiz. 1.One of the control mechanisms for a sustainable nuclear chain reactor involves slowing down the released neutrons so they may be captured by other nuclei. This is done using

16. © Copyright Pearson Prentice Hall Slide 16 of 20 25.3 Section Quiz. 2.Spent fuel rods are stored in

17. © Copyright Pearson Prentice Hall Slide 17 of 20 25.3 Section Quiz. 3.Choose the correct words for the spaces. In solar fusion, _______ nuclei fuse to form _______ nuclei.