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Nuclear energy. Ch. 11. Nuclear fission process. Splitting atom, releases heat Uncontrolled: explosion Controlled: make heat to produce steam that turns generator to produce electricity. Electricity production.
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Nuclear energy Ch. 11
Nuclear fission process • Splitting atom, releases heat • Uncontrolled: explosion • Controlled: make heat to produce steam that turns generator to produce electricity
Electricity production • US produces most energy, but France produces highest percentage of countries electricity (78%), and Japan • Potential energy 10 million times more than ff • 1960s-1980s – many plants built • Concerns – safety, cost, nuclear waste • Current renewed interest • Electricity shortages, ff prices, global warming
THE BIG PICTURE PROS CONS • 1/6 CO2 as fossil fuels • Less land disruption = less habitat loss • Decrease foreign oil dependence • No other air pollution • Difficult to store radioactive waste • Safety issue • Expensive to build • Tie to nuclear weapons • Use CO2 when mining uranium • Thermal water pollution
Storing radioactive wastes • Biggest issue (US stored on site) • Ideas: deep underground, aboveground mausoleums, ocean disposal prohibited • Needs: • Isolation • Geological stability • Little/no water • Issues: NIMBY • Yucca Mountain • Nuclear Waste Policy Act – burden on federal government • Transporting nightmares
Environmental advantages disadvantages • No air pollutants • Little CO2 • Little water pollution • Land disruption minimal • Nuclear wastes take thousands of years to degrade; how to store them • Safety and malfunction issue
The half-life of polonium-210 is 138.4 days. How many milligrams of polonium-210 remain after 415.2 days if you start with 2.0 mg of the isotope? The half-life of polonium-210 is 138.4 days. How many milligrams of polonium-210 remain after 415.2 days if you start with 2.0 mg of the isotope? The half-life of polonium-210 is 138.4 days. How many milligrams of polonium-210 remain after 415.2 days if you start with 2.0 mg of the isotope? The half-life of polonium-210 is 138.4 days. How many milligrams of polonium-210 remain after 415.2 days if you start with 2.0 mg of the isotope? Radioactive decay • Radioactive half life: time it takes for ½ the amount to change into different substance • Nucleus goes from unstable to stable • Ex: U-235 lead • The half-life of polonium-210 is 138.4 days. How many milligrams of polonium-210 remain after 415.2 days if you start with 2.0 mg of the isotope? p. 252 #15
BOILING WATER REACTOR (2 WATER LOOPS) Boiling Water Reactor Schematic: 1. Reactor pressure vessel (RPV) 2. Nuclear fuel element 3. Control rods 4. Circulation pumps 5. Engine control rods 6. Steam 7. Feedwater 8. High pressure turbine (HPT) 9. Low pressure turbine 10. Generator 11. Exciter 12. Condenser 13. Coolant 14. Pre-heater 15. Feedwater pump 16. Cold water pump 17. Concrete enclosure 18. Mains connection
Nuclear fusion • Future??? • Fuel = isotopes of hydrogen; waste is helium • (deuterium and tritium)