Nuclear Reactions:

1. Nuclear Reactions: AN INTRODUCTION TO FISSION, FUSION, AND NUCLEAR POWER

2. Nuclear reactions deal with interactions between the nuclei of atoms The focus of this presentation are the processes of nuclear fission and nuclear fusion Both fission and fusion processes deal with matter and energy Introduction

3. Matter and Energy Previous studies have taught us that “matter and energy cannot be created nor destroyed” We now need to understand that Matter and Energy are two forms of the same thing

4. Matter can be changed into Energy Einstein’s formula above tells us how the change occurs In the equation above: E = Energy m = Mass c = Speed of Light (Universal Constant) E = mc2

5. E = mc2 The equation may be read as follows: Energy (E) is equal to Mass (m) multiplied by the Speed of Light (c) squared This tells us that a small amount of mass can be converted into a very largeamount of energy because the speed of light (c) is an extremely large number

6. Fission notes Fission may be defined as the process of splitting an atomic nucleus into fission fragments The fission fragments are generally in the form of smaller atomic nuclei and neutrons Large amounts of energy are produced by the fission process

7. Fission notes Fissile nuclei are generally heavy atoms with large numbers of nucleons The nuclei of such heavy atoms are struck by neutrons initiating the fission process Fission occurs due to electrostatic repulsion created by large numbers of protons within the nuclei of heavy atoms

8. A classic example of a fission reaction is that of U-235: U-235 + 1 Neutron 2 Neutrons + Kr-92 + Ba-142 + Energy In this example, a stray neutron strikes an atom of U-235. It absorbs the neutron and becomes an unstable atom of U-236. It then undergoes fission. Notice that more neutrons are released in the reaction. These neutrons can strike other U-235 atoms to initiate their fission. Fission notes

9. Fission notes The fission process is a natural one. A French researcher found a natural uranium reactor in Gabon, West Africa; it has been estimated to be over 2 billion years old Fission produces large amounts of heat energy and it is this heat that is captured by nuclear power plants to produce electricity

10. Fusion is a nuclear reaction whereby two light atomic nuclei fuse or combine to form a single larger, heavier nucleus The fusion process generates tremendous amounts of energy; refer back to Einstein’s equation For fusion to occur, a large amount of energy is needed to overcome the electrical charges of the nuclei and fuse them together Fusion notes

11. Fusion notes Fusion reactions do not occur naturally on our planet but are the principal type of reaction found in stars The large masses, densities, and high temperatures of stars provide the initial energies needed to fuel fusion reactions The sun fuses hydrogen atoms to produce helium, subatomic particles, and vast amounts of energy

12. Mass and Energy are two forms of the same thing; neither can be created nor destroyed but mass can be converted into energy (E = mc2) Fission is a nuclear reaction in which a heavy atomic nucleus is split into lighter atomic nuclei Fusion is a nuclear reaction in which 2 light atomic nuclei are combined into a single, heavier atomic nucleus Review notes

13. Nuclear reaction notes Chain reaction occurs when a Uranium atom splits Different reactions Atomic Bomb in a split second Nuclear Power Reactor more controlled, cannot explode like a bomb

14. History of nuclear power 1938– Scientists study Uranium nucleus 1941 – Manhattan Project begins 1942 – Controlled nuclear chain reaction 1945 – U.S. uses two atomic bombs on Japan 1949 – Soviets develop atomic bomb 1952 – U.S. tests hydrogen bomb 1955 – First U.S. nuclear submarine

15. “Atoms for Peace” Program to justify nuclear technology Proposals for power, canal-building, exports First commercial power plant, England 1956

16. The energy in one pound of highly enriched Uranium is comparable to that of one million gallons of gasoline. One million times as much energy in one pound of Uranium as in one pound of coal. Economic advantagesnotes

17. Emissions Free notes Nuclear energy annually prevents 5.1 million tons of sulfur 2.4 million tons of nitrogen oxide 164 metric tons of carbon Nuclear often pitted against fossil fuels Some coal contains radioactivity Nuclear plants have released low-level radiation

18. Nuclear Power Plants

19. Nuclear power around the globe 17% of world’s electricity from nuclear power U.S. about 20% (2nd largest source) 431 nuclear plants in 31 countries 103 of them in the U.S. Built none since 1970s (Wisconsin as leader). U.S. firms have exported nukes. Push from Bush/Cheney for new nukes.

20. Countries Generating Nuclear Power

21. Technology depends on operators

23. Nuclear Reactor Process 3% enriched Uranium pellets formed into rods, which are formed into bundles Bundles submerged in water coolant inside pressure vessel, with control rods. Bundles must be SUPERCRITICAL; will overheat and melt if no control rods.Reaction converts water to steam, which powers steam turbine

25. Nuclear Reactor Structure Reactor’s pressure vessel typically housed in 8” of steel 36” concrete shielding 45” steel reinforced concrete

28. Back end: Radioactive waste Low-level wastes in commercial facilities Spent fuel in pools or “dry casks” by plants Nuclear lab wastes Hanford wastes leaked radiation into Columbia River High-level underground repository Yucca Mountain in Nevada to 2037 Wolf River Batholith in Wisconsin after 2037? Risks of cracks in bedrock, water seepage

30. Yucca Mountain

32. Radioactive Waste Recycling Disposal of radioactive waste from nuclear power plants and weapons facilities by recycling it into household products. In 1996, 15,000 tons of metal were received by the Association of Radioactive Metal Recyclers . Much was recycled into products without consumer knowledge. Depleted Uranium munitions for military.

33. Nuclear energy has no typical pollutants or greenhouse gasses Nuclear waste contains high levels of radioactive waste, which are active for hundreds of thousands of years. The controversy around nuclear energy stems from all parts of the nuclear chain. Summary notes