Fission And Fusion
Overview
The nucleus of an atom stores a staggering amount of energy, roughly a million times more than any chemical bond. Two processes can unlock it: splitting a heavy nucleus apart (fission) or forcing light nuclei together (fusion). Both release energy, but they work in very different ways and under very different conditions.
You will learn how uranium-235 is split by neutron bombardment, how the resulting chain reaction is controlled inside a nuclear reactor, and why fusion, the process that powers every star, remains so difficult to reproduce on Earth. The topic also covers the advantages and limitations of nuclear power compared with fossil fuels.
Objectives
- Know that nuclear reactions, including fission, fusion and radioactive decay, can be a source of energy
- Understand how a nucleus of U-235 can be split (the process of fission) by collision with a neutron and that this process releases energy as kinetic energy of the fission products
- Know that the fission of U-235 produces two radioactive daughter nuclei and a small number of neutrons
- Describe how a chain reaction can be set up if the neutrons produced by one fission strike other U-235 nuclei
- Describe the role played by the control rods and moderator in the fission process
- Understand the role of shielding around a nuclear reactor
- Explain the difference between nuclear fusion and nuclear fission
- Describe nuclear fusion as the creation of larger nuclei resulting in a loss of mass from smaller nuclei, accompanied by a release of energy
- Know that fusion is the energy source for stars
- Explain why nuclear fusion does not happen at low temperatures and pressures, due to electrostatic repulsion of protons
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Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Fission And Fusion. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- What is nuclear fission? A) Two light nuclei joining together B) A large nucleus splitting into two smaller nuclei C) A nucleus emitting an alpha particle D) A neutron changing into a proton and an electron Answer: B
- What is the role of the moderator in a nuclear reactor? A) To absorb neutrons and stop the chain reaction B) To slow down fast neutrons so they can cause fission C) To shield workers from radiation D) To cool the reactor core Answer: B
- Which of the following is a product of the fission of U-235? A) Alpha particles B) Protons C) Two or three neutrons D) Electrons Answer: C
- Why does nuclear fusion require very high temperatures? A) To melt the fuel so it can react B) To give nuclei enough kinetic energy to overcome electrostatic repulsion C) To break chemical bonds in hydrogen molecules D) To increase the half-life of the fuel Answer: B
- Which statement correctly compares fission and fusion? A) Fission joins small nuclei; fusion splits large nuclei B) Fission produces more waste; fusion produces very little radioactive waste C) Fusion is used in power stations; fission is not yet viable D) Both require extremely high temperatures to occur Answer: B
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Recommended Books
Further learning from open sources
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Textbook section
Nuclear Fission and Fusion
Explain nuclear fission
"Physics: Nuclear Fission and Fusion" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/physics/pages/22-4-nuclear-fission-and-fusion. Access for free at https://openstax.org/books/physics/pages/1-introduction
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Textbook section
Fusion
While basking in the warmth of the summer sun, a student reads of the latest breakthrough in achieving sustained thermonuclear power and vaguely recalls hearing about the cold fusion controversy. The three are connected. The Sun’s energy is produced by nuclear fusion (see Figure 32.13 ). Thermonucle
"College Physics: Fusion" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/college-physics/pages/32-5-fusion. Access for free at https://openstax.org/books/college-physics/pages/1-introduction
Published by other organisations under open licences, credited as they ask. Links open their websites.
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