Shoreham Nuclear Plant on Long Island, New York

Nuclear Share of Electrical Power

Nuclear Power in the United States

NUCLEAR ENERGY When isotopes of uranium and plutonium undergo controlled nuclear fission, the resulting heat produces steam that spins turbines to generate electricity. When isotopes of uranium and plutonium undergo controlled nuclear fission, the resulting heat produces steam that spins turbines to generate electricity. The uranium oxide consists of about 97% nonfissionable uranium-238 and 3% fissionable uranium-235. The uranium oxide consists of about 97% nonfissionable uranium-238 and 3% fissionable uranium-235. The concentration of uranium-235 is increased through an enrichment process. The concentration of uranium-235 is increased through an enrichment process.

NUCLEAR ENERGY Nuclear fusion is a nuclear change in which two isotopes are forced together. Nuclear fusion is a nuclear change in which two isotopes are forced together. No risk of meltdown or radioactive releases. No risk of meltdown or radioactive releases. May also be used to breakdown toxic material. May also be used to breakdown toxic material. Still in laboratory stages. Still in laboratory stages. There is a disagreement over whether to phase out nuclear power or keep this option open in case other alternatives do not pan out. There is a disagreement over whether to phase out nuclear power or keep this option open in case other alternatives do not pan out.

Terms and Definitions Fuel rods: rods full of U235 pellets Fuel rods: rods full of U235 pellets Moderator: fluid (water) coolant that slows down neutrons Moderator: fluid (water) coolant that slows down neutrons Control rods: moderate rate of the chain reaction by absorbing neutrons Control rods: moderate rate of the chain reaction by absorbing neutrons

A Nuclear Reactor

A Nuclear Reactor Is Designed To Sustain a continuous chain reaction. Sustain a continuous chain reaction. Prevent amplification into a nuclear explosion. Prevent amplification into a nuclear explosion. Consist of an array of fuel and control rods. Consist of an array of fuel and control rods. Make some material intensely hot. Make some material intensely hot.

A Nuclear Reactor

Fig , p. 372 Small amounts of radioactive gases Uranium fuel input (reactor core) Control rods Containment shell Heat exchanger Steam Turbine Generator Waste heat Electric power Hot coolant Useful energy 25%–30% Hot water output Pump Coolant Pump Moderator Cool water input Waste heat Shielding Pressure vessel Coolant passage Water Condenser Periodic removal and storage of radioactive wastes and spent fuel assemblies Periodic removal and storage of radioactive liquid wastes Water source (river, lake, ocean)

Fig , p. 373 Decommissioning of reactor Fuel assemblies Reactor Enrichment of UF 6 Fuel fabrication (conversion of enriched UF 6 to UO 2 and fabrication of fuel assemblies) Temporary storage of spent fuel assemblies underwater or in dry casks Conversion of U 3 O 8 to UF 6 Uranium-235 as UF 6 Plutonium-239 as PuO 2 Spent fuel reprocessing Low-level radiation with long half-life Geologic disposal of moderate & high-level radioactive wastes Open fuel cycle today “Closed” end fuel cycle

What Happened to Nuclear Power? After more than 50 years of development and enormous government subsidies, nuclear power has not lived up to its promise because: After more than 50 years of development and enormous government subsidies, nuclear power has not lived up to its promise because: Multi billion-dollar construction costs. Multi billion-dollar construction costs. Higher operation costs and more malfunctions than expected. Higher operation costs and more malfunctions than expected. Poor management. Poor management. Public concerns about safety and stricter government safety regulations. Public concerns about safety and stricter government safety regulations.

NUCLEAR ENERGY In 1995, the World Bank said nuclear power is too costly and risky. In 1995, the World Bank said nuclear power is too costly and risky. In 2006, it was found that several U.S. reactors were leaking radioactive tritium into groundwater. In 2006, it was found that several U.S. reactors were leaking radioactive tritium into groundwater. Figure 16-19

NUCLEAR ENERGY When a nuclear reactor reaches the end of its useful life, its highly radioactive materials must be kept from reaching the environment for thousands of years. When a nuclear reactor reaches the end of its useful life, its highly radioactive materials must be kept from reaching the environment for thousands of years. At least 228 large commercial reactors worldwide (20 in the U.S.) are scheduled for retirement by At least 228 large commercial reactors worldwide (20 in the U.S.) are scheduled for retirement by Many reactors are applying to extent their 40- year license to 60 years. Many reactors are applying to extent their 40- year license to 60 years. Aging reactors are subject to embrittlement and corrosion. Aging reactors are subject to embrittlement and corrosion.

NUCLEAR ENERGY Building more nuclear power plants will not lessen dependence on imported oil and will not reduce CO 2 emissions as much as other alternatives. Building more nuclear power plants will not lessen dependence on imported oil and will not reduce CO 2 emissions as much as other alternatives. The nuclear fuel cycle contributes to CO 2 emissions. The nuclear fuel cycle contributes to CO 2 emissions. Wind turbines, solar cells, geothermal energy, and hydrogen contributes much less to CO 2 emissions. Wind turbines, solar cells, geothermal energy, and hydrogen contributes much less to CO 2 emissions.

NUCLEAR ENERGY Scientists disagree about the best methods for long-term storage of high-level radioactive waste: Scientists disagree about the best methods for long-term storage of high-level radioactive waste: Bury it deep underground. Bury it deep underground. Shoot it into space. Shoot it into space. Bury it in the Antarctic ice sheet. Bury it in the Antarctic ice sheet. Bury it in the deep-ocean floor that is geologically stable. Bury it in the deep-ocean floor that is geologically stable. Change it into harmless or less harmful isotopes. Change it into harmless or less harmful isotopes.

Radioactive Decay Half life = the time for half the amount of a radioactive isotope to decay.

Half-life Molybdenum-99 (half-life = 2.8 days) Molybdenum-99 (half-life = 2.8 days) Xenon-133 (half-life = 5.3 days) Xenon-133 (half-life = 5.3 days) Krypton-85 (half-life = 10.7 years) Krypton-85 (half-life = 10.7 years) Cesium-137 (half-life = 30.0 years) Cesium-137 (half-life = 30.0 years) Plutonium-239 (half-life = 24,000 years) Plutonium-239 (half-life = 24,000 years)

Half life = the time for half the amount of a radioactive isotope to decay. This is an exponential graph. This is an exponential graph. When else have we seen this type of graph? When else have we seen this type of graph? Do the math, the waste will never be totally gone. Do the math, the waste will never be totally gone. Some Uranium’s half life can be up to 700 million years. Some Uranium’s half life can be up to 700 million years.

NUCLEAR ENERGY After three or four years in a reactor, spent fuel rods are removed and stored in a deep pool of water contained in a steel-lined concrete container. After three or four years in a reactor, spent fuel rods are removed and stored in a deep pool of water contained in a steel-lined concrete container. Figure 16-17

NUCLEAR ENERGY After spent fuel rods are cooled considerably, they are sometimes moved to dry-storage containers made of steel or concrete. After spent fuel rods are cooled considerably, they are sometimes moved to dry-storage containers made of steel or concrete. Figure 16-17

Disposal of Radioactive Wastes (200 Thousand Tons) Finding long-term containment sites Finding long-term containment sites Transport of highly toxic radioactive wastes across the United States Transport of highly toxic radioactive wastes across the United States The lack of any resolution to the radioactive waste problem The lack of any resolution to the radioactive waste problem Environmental protests Environmental protests Cost ($60 billion to 1.5 trillion) Cost ($60 billion to 1.5 trillion)

Disposal of Radioactive Wastes To be safe, plutonium-239 would require 240,000 years (10 half-lives) of containment! To be safe, plutonium-239 would require 240,000 years (10 half-lives) of containment! Discuss the implications of this in terms of disposal of radioactive wastes. Discuss the implications of this in terms of disposal of radioactive wastes. Yucca mountain in southwestern Nevada = the nation’s nuclear waste repository Yucca mountain in southwestern Nevada = the nation’s nuclear waste repository

Yucca Mountain, Nevada

Nuclear Power Accidents Three Mile Island Three Mile Island Harrisburg, PA Harrisburg, PA Loss of coolant in reactor vessel Loss of coolant in reactor vessel Damage so bad, reactor shut down permanently Damage so bad, reactor shut down permanently Unknown amount of radioactive waste released into atmosphere. Unknown amount of radioactive waste released into atmosphere.

Case Study: The Chernobyl Nuclear Power Plant Accident The world’s worst nuclear power plant accident occurred in 1986 in Ukraine. The world’s worst nuclear power plant accident occurred in 1986 in Ukraine. The disaster was caused by poor reactor design and human error. The disaster was caused by poor reactor design and human error. By 2005, 56 people had died from radiation released. By 2005, 56 people had died from radiation released. 4,000 more are expected from thyroid cancer and leukemia. 4,000 more are expected from thyroid cancer and leukemia.

Chernobyl, Russia Loss of water coolant perhaps triggered the accident. When the water- circulation system failed, the temperature in the reactor core increased to over 5,000 o F, causing the uranium fuel to begin melting and producing steam that reacted with the zirconium alloy cladding of the fuel rod to produce hydrogen gas. Loss of water coolant perhaps triggered the accident. When the water- circulation system failed, the temperature in the reactor core increased to over 5,000 o F, causing the uranium fuel to begin melting and producing steam that reacted with the zirconium alloy cladding of the fuel rod to produce hydrogen gas.

How Chernobyl Blew Up A second reaction between steam and graphite produced free hydrogen and carbon oxides. When this gas combined with oxygen, a blast blew off the top of the building, igniting the graphite. The burning graphite threw a dense cloud of radioactive fission products into the air. A second reaction between steam and graphite produced free hydrogen and carbon oxides. When this gas combined with oxygen, a blast blew off the top of the building, igniting the graphite. The burning graphite threw a dense cloud of radioactive fission products into the air.

Consequences of Radiation Exposure Block cell division Block cell division Damage biological tissues and DNA Damage biological tissues and DNA Death Death Cancer Cancer Birth defects Birth defects

Economic Problems with Nuclear Power Energy demand estimates were unrealistic. Energy demand estimates were unrealistic. Costs increase (5X) to comply with new safety standards. Costs increase (5X) to comply with new safety standards. Withdrawal of government subsidies to nuclear industry. Withdrawal of government subsidies to nuclear industry. Public protests delayed construction. Public protests delayed construction. Any accident financially ruins the utility. Any accident financially ruins the utility.

Comparing Nuclear Power with Coal Power

NUCLEAR ENERGY A 1,000 megawatt (MW) nuclear plant is refueled once a year, whereas a coal plant requires 80 rail cars a day. A 1,000 megawatt (MW) nuclear plant is refueled once a year, whereas a coal plant requires 80 rail cars a day. Figure 16-20