Book contents
- Frontmatter
- Contents
- Preface to the second edition
- Preface to the first edition
- Constants of nature, conversion factors and notation
- Glossary of some important symbols
- 1 Prologue
- 2 Leptons and the electromagnetic and weak interactions
- 3 Nucleons and the strong interaction
- 4 Nuclear sizes and nuclear masses
- 5 Ground-state properties of nuclei: the shell model
- 6 Alpha decay and spontaneous fission
- 7 Excited states of nuclei
- 8 Nuclear reactions
- 9 Power from nuclear fission
- 10 Nuclear fusion
- 11 Nucleosynthesis in stars
- 12 Beta decay and gamma decay
- 13 Neutrinos
- 14 The passage of energetic particles through matter
- 15 Radiation and life
- Appendix A Cross-sections
- Appendix B Density of states
- Appendix C Angular momentum
- Appendix D Unstable states and resonances
- Further reading
- Answers to problems
- Index
9 - Power from nuclear fission
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- Preface to the second edition
- Preface to the first edition
- Constants of nature, conversion factors and notation
- Glossary of some important symbols
- 1 Prologue
- 2 Leptons and the electromagnetic and weak interactions
- 3 Nucleons and the strong interaction
- 4 Nuclear sizes and nuclear masses
- 5 Ground-state properties of nuclei: the shell model
- 6 Alpha decay and spontaneous fission
- 7 Excited states of nuclei
- 8 Nuclear reactions
- 9 Power from nuclear fission
- 10 Nuclear fusion
- 11 Nucleosynthesis in stars
- 12 Beta decay and gamma decay
- 13 Neutrinos
- 14 The passage of energetic particles through matter
- 15 Radiation and life
- Appendix A Cross-sections
- Appendix B Density of states
- Appendix C Angular momentum
- Appendix D Unstable states and resonances
- Further reading
- Answers to problems
- Index
Summary
We saw in Chapter 4 that nuclei in the neighbourhood of 56Fe have the greatest binding energy per nucleon (Fig. 4.7). In principle therefore, nuclear potential energy can be released into kinetic energy and made available as heat by forming nuclei closer in mass to iron, either from heavy nuclei by fission or from light nuclei by fusion. This chapter is devoted to the physics of nuclear fission and its application in power reactors. There were, world-wide, some 430 nuclear power stations operating in 1997, and these generated about 17% of the global electricity supply. In the UK about 28% of all electricity generated came from nuclear fission.
Induced fission
The spontaneous fission of nuclei such as 236U was discussed in §6.3; the Coulomb barriers inhibiting spontaneous fission are in the range 5–6 MeV for nuclei with A ≈ 240. If a neutron of zero kinetic energy enters a nucleus to form a compound nucleus, the compound nucleus will have an excitation energy above its ground state equal to the neutron's binding energy in that ground state. For example, a zero-energy neutron entering 235U forms a state of 236U with an excitation energy of 6.46 MeV. This energy is above the fission barrier, and the compound nucleus quickly undergoes fission, with fission products similar to those found in the spontaneous fission of 236U. To induce fission in 238U, on the other hand, requires a neutron with a kinetic energy in excess of about 1.4 MeV.
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- Chapter
- Information
- An Introduction to Nuclear Physics , pp. 115 - 129Publisher: Cambridge University PressPrint publication year: 2001