Nuclear Reactions: Fission and Fusion.

1. Nuclear Reactions: Fission and Fusion.

2. Questions to consider • What is nuclear fission? • What are the advantages and disadvantages of nuclear fission? • What is nuclear fusion? • What are the advantages and disadvantages of nuclear fusion? • What are the risks involved in atomic energy? • What are the benefits of atomic energy?

3. Nuclear Reactions: Fission and Fusion. Nuclear fission of a plutonium nucleus already happens naturally ... we just help it along by allowing the reaction to proceed faster. Nuclear fusion, on the other hand, requires that the fuel nuclei be moving very fast, or be heated to very high temperatures. Scientists for the last 50 years have been trying to figure out how to do this, but so far the technology at our disposal is not equal to the task!

4. Nuclear fusion Nuclear fusion is what provides the sun and the stars with the energy to shine continuously for billions of years. Fusion reactions power the starsand produce virtually all elements in a process called nucleosynthesis.

5. Nuclear fusion Fusion is what happens when two atomic nuclei are forced together by high pressure ... high enough to overcome the strong repulsive forces of the respective protons in the nuclei. When the nuclei fuse, they form a new element and release excess energy in the form of a fast-moving neutron. The energy is “extra” because the mass of the newly formed nucleus is less than the sum of the masses of the original two nuclei. The extra mass is converted to energy according to Einstein's equation E=mc2. This energy can be used to do useful work.

6. Nuclear fusion Nuclear energy can also be released by fusion of two light elements (elements with low atomic numbers). The power that fuels the sun and the stars is nuclear fusion. In a hydrogen bomb, two isotopes of hydrogen, deuterium and tritium are fused to form a nucleus of helium and a neutron. This fusion releases 17.6 MeV of energy. Unlike nuclear fission, there is no limit on the amount of the fusion that can occur.

7. Nuclear fusion http://www.atomicarchive.com/Fusion/Fusion1.shtml

8. Nuclear Fusion For years now people have been turning to fusion as the "energy of the future." Not only does fusion appear to be an extremely effective source of energy production, it is environmentally friendly and virtually inexhaustible. Too good to be true, you say? Perhaps we should look more closely at fusion, both as a scientific theory and as what may prove to become mankind’s energy source for the 21st century and beyond.

9. What are the advantages of nuclear fusion? Fuel for fusion reactions are readily available. Deuterium and tritium are virtually inexhaustible. Unlike the burning of coal or other fossil fuels, fusion does not emit harmful toxins into the atmosphere. The combustion of most fossil fuels involves some form of the reaction C + O2(g) --> CO2(g) + heat The carbon dioxide (CO2(g)) emitted by this reaction contributes to the global warming or so-called "Greenhouse Effect" that we've all heard so much about. Fusion, however, produces only helium, a gas that is already in abundance in the atmosphere and will not contribute to global warming. A major concern with the use of fission power is the issue of nuclear waste, a dangerous material that can both directly injure people and be manufactured into weapons. Fusion has no such problems with dangerous by-products.

10. What are the disadvantages of nuclear fusion? Scientists have not yet been able to contain a fusion reaction long enough for there to be a net energy gain. Many countries are phasing out fusion research because of the failure to reach a breakthrough.

11. Nuclear Fission Fission is already an established method of energy production. Countries around the world possess fission reactors capable of powering whole cities. The benefits in energy production, however, are shadowed by disturbing accounts of harm to the environment and dangerous nuclear waste byproducts. Chernobyl, Hiroshima, and Nagasaki are frightening precedents in the field of fission development and are not to be ignored.

12. Nuclear Fission Nuclear fission is the process of splitting atoms, or fissioning them. To picture nuclear fission, imagine about 200 marbles lying on a flat surface, all jumbled together, and roughly forming a circle. What would happen if someone took another marble and threw it at them? They would fly all around in different directions and groups, right? That is a good visual of what happens in nuclear fission. The filled circle is like an atom's nucleus. The marble being thrown is like a "neutron bullet". The only differences are that the marbles are protons and neutrons and the protons and neutrons aren't in a filled circle. In the actual atom they are in the shape of a sphere. An atom is also a bit more complicated than a bunch of marbles.

13. Nuclear Fission http://en.wikipedia.org/wiki/Nuclear_fission

14. What are the advantages of nuclear fission? Relatively little fuel is needed, it is relatively inexpensive, and it is available in trace amounts around the world. Fission is not believed to contribute to global warming or other pollution effects associated with fossil fuel combustion.

15. What are the disadvantages of nuclear fission? Possibility of nuclear meltdown from an uncontrolled reaction–leads to nuclear fallout with potentially harmful effects on civilians. Waste products can be used to manufacture weapons. High initial cost because plant requires containment safeguards.

16. What are the risks involved in atomic energy? The biggest risk is the future of the by-product, which includes highly-radioactive fuel, containers, tools, decommissioned plants, and anything that comes into contact with the fuel. Since this material can be dangerous for hundreds of thousands of years after use, and since no human artifacts have been in continuous use for that span of time, it's doubtful humans will find a way to permanently store these materials.

17. What are the risks involved in atomic energy? There are acute dangers associated with atomic energy, such as the risk of reactor melt-down where control of the fissioning process is lost, the containment and safetysystems are breached, and massive amounts of radioactive material escape into the environment contaminating a large region for hundreds or thousands of years. Modern advocates of nuclear power claim that the risk of meltdown is low or nonexistent with modern designs, but it is hard for a designer to account for all the scenarios (for example: terrorist attacks, an extreme earthquake or tsunami, etc.)

18. What are the benefits of atomic energy? First, what is atomic energy? Atomic energy is energy produced by atoms. (It is used synonymously with the word “nuclear energy.”) Atomic energy offers a clean energy alternative that frees us from dependence on fossil fuels.