Chapter 13Energy from Nuclear Power

Copyright © 2008 Pearson Prentice Hall, Inc.

13.1 - Nuclear Accidents in Japan

Nuclear Energy in Perspective

Nuclear Power in the United States

Nuclear Share of Electrical Power

13.2 - 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 + 146 neutrons• U235 = 92 protons + 143 neutrons

Fission, Fusion, or Both?

• Energy is released• Begins with U235• Produces radioactive byproducts• Produces free neutrons

Both

Fission

Fission

Both

Fission, Fusion, or Both?

• Splits a larger atom into smaller atoms

• Fuses smaller atoms into one larger atom

• Begins with H2 and H3

• Produces helium

Fission

Fusion

Fusion

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

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 CO2 into the atmosphere

• Emits no CO2 into the atmosphere

C

N

C

N

Comparing Nuclear Power with Coal Power

• Emits over 300 thousand tons of SO2 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

13.3 - 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 oF, 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

Main Yankee Nuclear Power Plant

• Decommissioned in 2003• 200,000 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

13.4 - 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

Breeder

Breeder

Fusion

Both

Fusion

Fusion

13.5 - 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.