Chapter 13 Energy from Nuclear Power Copyright © 2008 Pearson Prentice Hall, Inc.

Nuclear Accidents in Japan

Nuclear Energy in Perspective

Nuclear Power in the United States

Nuclear Share of Electrical Power

Terms and Definitions Fission: a large atom of one element is split to produce two different smaller elements Fusion: two small atoms combine to form a larger atom of a different element Isotope: different (mass number) forms of the same element

Two Forms of Uranium U238 = 92 protons neutrons U235 = 92 protons neutrons

Fission, Fusion, or Both? Energy is released Begins with U235 Produces radioactive byproducts Produces free neutrons Both Fission Both

Fission, Fusion, or Both? Splits a larger atom into smaller atoms Fuses smaller atoms into one larger atom Begins with H 2 and H 3 Produces helium Fission Fusion

Terms and Definitions Fuel rods: rods full of U235 pellets Moderator: fluid (water) coolant that slows down 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. Prevent amplification into a nuclear explosion. Consist of an array of fuel and control rods. Make some material intensely hot.

A Nuclear Reactor

A Nuclear Power Plant

A Nuclear Power Plant Is Designed To Use steam to drive turbo generators Convert steam into electricity Produce super-heated water in a reactor vessel Prevent meltdown

Comparing Nuclear Power with Coal Power

Requires 3.5 million tons of raw fuel Requires 30 tons of raw material Emits over 7 million tons of CO 2 into the atmosphere Emits no CO 2 into the atmosphere C N C N

Comparing Nuclear Power with Coal Power Emits over 300 thousand tons of SO 2 into the atmosphere Emits no acid forming pollutants Produces about 100 thousand tons of ash Produces 250 tons of radioactive waste Possible meltdown C N N N C

Terms and Definitions Radioisotopes: unstable isotopes of the elements resulting from the fission process

Terms and Definitions Radioactive emissions: subatomic particles (neutrons) and high-energy radiation (alpha, beta, and gamma rays) Radioactive wastes: materials that become radioactive by absorbing neutrons from the fission process

Radioactive Emissions and Wastes

Consequences of Radiation Exposure High Dose – results in death quickly Block cell division Radiation sickness Low Dose – may or may not result in death; slower Damage biological tissues and DNA Cancer Birth defects

Disposal of Radioactive Wastes (200 Thousand Tons) Finding long-term containment sites Transport of highly toxic radioactive wastes across the United States The lack of any resolution to the radioactive waste problem Environmental racism 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! Implications of this in terms of disposal of radioactive wastes. Yucca mountain in southwestern Nevada = the nation’s nuclear waste repository

Yucca Mountain, Nevada

Nuclear Power Accidents Three Mile Island 1979 Harrisburg, PA Loss of coolant in reactor vessel Damage so bad, reactor shut down permanently Unknown amount of radioactive waste released into atmosphere.

Chernobyl, Russia

How Chernobyl Blew Up 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.

Safety and Nuclear Power Passive rather than active safety features New generations of reactors Terrorism and nuclear power: dirty bombs or outright attacks.

Advanced Boiling-water Reactor

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

Main Yankee Nuclear Power Plant

Decommissioned in ,000 tons of solid waste removed by rail, truck, and barge Site now consists of 200 acres of conservation land 400 acres for economic development 12 acres of secured storage for spent nuclear fuel

More Advanced Reactors Breeder reactors Fusion reactors

Laser Fusion

Breeder, Fusion, or Both Creates more fuel than it consumes Raw material is U238 Splits atoms Fuses atoms Releases energy Raw material is deuterium and tritium Source of unprecedented thermal pollution Breeder Fusion Both Fusion

The Future of Nuclear Power Opposition Rebirth of Nuclear Power

Opposition General distrust of technology Skepticism of management Doubt overall safety claims about nuclear power plants Nuclear power plants are prime targets to terrorist attacks Nuclear waste disposal problems

Rebirth? Need to address public concerns listed in the opposition section. Waste dilemma must be resolved. Strong political leadership capable of analyzing the full spectrum of problems associated with the future of nuclear power is needed.