Nuclear EnergyNuclear Energy

Possible Exam QuestionsPossible Exam Questions

1.1. Compare the environmental effects of coal combustion Compare the environmental effects of coal combustion and conventional nuclear fission for the generation of and conventional nuclear fission for the generation of electricity.electricity.

2. Are you in favor of the United States developing you in favor of the United States developing additional nuclear power plants to provide us with additional nuclear power plants to provide us with electricity in the 21st century? Include arguments on electricity in the 21st century? Include arguments on

the economic and environmental costs/risksthe economic and environmental costs/risks

Possible Exam QuestionsPossible Exam Questions

3.3. If your local utility company were going to build new If your local utility company were going to build new power plant, would you prefer a coal-powered or power plant, would you prefer a coal-powered or nuclear-powered energy plant. Defend your point of nuclear-powered energy plant. Defend your point of view, while also acknowledging concerns of your view, while also acknowledging concerns of your viewpoint.viewpoint.

4. Relate the pros and cons of permanent storage of high-the pros and cons of permanent storage of high-

level radioactive wastes at Yucca Mountain.level radioactive wastes at Yucca Mountain.

Fossil Fuels Projections

Basic TerminologyBasic Terminology

CombustionCombustion - the breaking of carbon-carbon bonds, - the breaking of carbon-carbon bonds, causing the release of energy. Elements do not change causing the release of energy. Elements do not change form, it is form, it is just the rearrangement of electrons.just the rearrangement of electrons.

FissionFission - the - the splitting of atomssplitting of atoms of an element into two of an element into two smaller atoms.smaller atoms.

IsotopesIsotopes - differing forms (# neutrons) of the same - differing forms (# neutrons) of the same element.element.

RadioactiveRadioactive - isotopes which are unstable; they emit - isotopes which are unstable; they emit high levels of energy (radiation) and form new elementshigh levels of energy (radiation) and form new elements

Energy Consumption by FuelEnergy Consumption by Fuel

Fusion ReactionsFusion Reactions

Fusing one kilogram of Fusing one kilogram of hydrogen into helium hydrogen into helium releases 650 trillion releases 650 trillion Joules of energy. Joules of energy.

This is over 4 million This is over 4 million times the energy times the energy released by burning the released by burning the same amount of same amount of hydrogen. hydrogen.

Fusion ReactionsFusion Reactions

Overcoming the electric repulsion between hydrogen Overcoming the electric repulsion between hydrogen nuclei requires high random velocities (T > 10,000,000 nuclei requires high random velocities (T > 10,000,000 degrees Kelvin). Even at these high temperatures, fusion degrees Kelvin). Even at these high temperatures, fusion is inefficient; only a minuscule fraction of collisions is inefficient; only a minuscule fraction of collisions between nuclei result in fusion. To compensate for the between nuclei result in fusion. To compensate for the low efficiency of fusion, you need high densities of low efficiency of fusion, you need high densities of hydrogen.hydrogen.

These hot, dense conditions occur in the centers of stars.These hot, dense conditions occur in the centers of stars.

Fusion ReactionsFusion Reactions

If the Sun were initially madeIf the Sun were initially made entirely of hydrogen, fusing that entirely of hydrogen, fusing that hydrogen into helium would hydrogen into helium would provide enough energy to provide enough energy to power the Sun for 100 billion power the Sun for 100 billion years (a time comfortably long years (a time comfortably long compared to the Sun's current compared to the Sun's current age of approximately 5 billion age of approximately 5 billion

years).years).

Fission ReactionsFission Reactions

Conventional Nuclear FissionU-235U-235 is the isotope used by conventional nuclear reactors. is the isotope used by conventional nuclear reactors. It is found in ores in a concentration of It is found in ores in a concentration of 0.7%.0.7%.

U235 is refined, or U235 is refined, or enrichedenriched, to a concentration of , to a concentration of 3%3% for use.for use.

Pellets are put into Pellets are put into fuel rodsfuel rods (hollow tubes), and fuel rods (hollow tubes), and fuel rods are grouped into are grouped into fuel assembliesfuel assemblies..

Above a fuel assembly areAbove a fuel assembly are control rods control rods made of a special made of a special alloy which absorbs neutrons.alloy which absorbs neutrons.

Conventional Conventional Nuclear Nuclear FissionFission

UU235235 is bombarded is bombarded with neutrons.with neutrons.

A chain reaction occurs (UA chain reaction occurs (U235235 splits, releasing more splits, releasing more neutrons.)neutrons.)

Control rods regulate the reaction (boron, cadmium, Control rods regulate the reaction (boron, cadmium, or graphite absorb neutrons).or graphite absorb neutrons).

Reaction produces heat, which transforms water into Reaction produces heat, which transforms water into steam used to generate electricity.steam used to generate electricity.

Pressurized water nuclear reactorPressurized water nuclear reactor

primary water circuit - in containment structure; HOTsecondary water circuit - heated by primary; turns turbinetertiary water circuit - the heat sink, condenses water.

HOT (radioactive) water outside of the containment HOT (radioactive) water outside of the containment structure. structure.

Meltdown - when nuclear fuel is so hot it forms a molten Meltdown - when nuclear fuel is so hot it forms a molten mass and breaches the containment structuremass and breaches the containment structure.

Percent of Percent of Electricity Electricity

From Nuclear From Nuclear ReactorsReactors

Percent of Electricity From Nuclear Percent of Electricity From Nuclear ReactorsReactors

USA Nuclear Power

World Nuclear Power

European Nuclear Power

Sources of Human Exposure to RadiationSources of Human Exposure to Radiation

Health Risks of RadioactivityHealth Risks of Radioactivity

Time Frame Time Frame for Problems for Problems with with RadioactivityRadioactivity

Problems Problems Associated Associated with with Nuclear Nuclear PowerPower

Safety in nuclear Safety in nuclear power plants -power plants -

Three Mile Island Three Mile Island andand

ChernobylChernobyl

Chernobyl Chernobyl April 1986April 1986

31 died immediately31 died immediately

>350 died during >350 died during clean-upclean-up

>24,000 received >24,000 received serious radiation serious radiation exposuresexposures

Three Mile IslandThree Mile Island

Three Mile IslandThree Mile Island

Three Mile Island

In the U.S.A., nuclear reactors were being phased out In the U.S.A., nuclear reactors were being phased out due to: Rapidly increasing construction costs; due to: Rapidly increasing construction costs; decreasing costs of alternative energy sources; public decreasing costs of alternative energy sources; public opposition.opposition.

The average time to The average time to construct a new plant construct a new plant was 6.3 years in the was 6.3 years in the U.S. in 1971. U.S. in 1971.

In 1991 the time was: In 1991 the time was: 14 years in the U.S.A. 14 years in the U.S.A. 7 years in Japan7 years in Japan 5 years in France 5 years in France

In the U.S. no plant ordered between In the U.S. no plant ordered between 1974 and 1978 is still under 1974 and 1978 is still under construction. There have been no new construction. There have been no new USA orders since 1978.USA orders since 1978.

Problems Associated with Nuclear PowerProblems Associated with Nuclear Power

Radioactive waste disposal - Radioactive waste disposal - Mines and mills produce Mines and mills produce radioactive wastes and pollute the environment.radioactive wastes and pollute the environment.

Problems Associated with Nuclear Problems Associated with Nuclear PowerPower

TerrorismTerrorism

Nuclear wastesNuclear wastes - long half life, so long term disposal long half life, so long term disposal must be for 10’s of thousands of years. Enrichment must be for 10’s of thousands of years. Enrichment produces radioactive wastes, and spent fuel has to be produces radioactive wastes, and spent fuel has to be disposed.disposed.

Economic Costs Economic Costs -- decommissioning nuclear power decommissioning nuclear power plants and deconstruction can cost 10X construction. plants and deconstruction can cost 10X construction. Also, Also, costs for storage (see above)

Horrible disposal practices by the Soviet Union.

Broken Broken Arrows Arrows Indicating Indicating What is not What is not HappeningHappening

High Level Waste High Level Waste Repository Planned Repository Planned on Desert Ridge on Desert Ridge near Yucca near Yucca Mountain, Nevada.Mountain, Nevada.

Benefits?Benefits?

Risks/Costs?Risks/Costs?