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Chapter 11
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Nuclear Energy: Benefits and Risks
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Radioactive - _______________________ __________________________________.
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Neutrons, electrons, protons, and other larger particles are released, along with energy.
 Radioactive Half-Life - ____________ ______________________________
______________________________.
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Radiation
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Types:
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Alpha - Moving particles composed of _____________________________.
 Stopped by layer of skin.
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Beta - Consists of _____________ from nucleus.
 Stopped by layer of clothing.
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Gamma - Form of __________________ _______________.
 Can pass through several centimeters of concrete.
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Radiation
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If the radiation reaches living tissue, equivalent doses of beta and gamma radiation can
cause ________________ _____________________________.
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Alpha particles are more massive, thus can cause more damage to biological tissues.
The Nature of Nuclear Energy
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Nuclear Fission - Occurs when neutrons impact and split the nuclei of certain atoms.
 Nuclear Chain Reaction - ____________ ________________________________
________________________________ _______________________________.
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The Nature of Nuclear Energy
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Only certain kinds of atoms are suitable for development of a nuclear chain reaction.
 The two most common are ___________ and ________________.
 Requires certain quantity of nuclear fuel (critical mass).
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History of Nuclear Energy Development
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First controlled fission - ______________.
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______ - U.S. dropped atomic bombs on Hiroshima and Nagasaki.
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Following WW II, people began exploring other potential uses of nuclear energy.
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U.S. built world’s first _________________ ____________.
Dwight D. Eisenhower
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“Atoms for Peace” Speech in 1953:
 “Nuclear reactors will produce electricity so cheaply that it will not be necessary
to meter it.”
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Today’s Reality:
 Accidents have caused worldwide concern.
 Most new projects have been stopped.
 Many experts predict rebirth.
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Nuclear Fission Reactors
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Nuclear Reactor - Device that permits a __________________________.
 Nucleus of _______ atom struck by slowly moving neutron from another atom.
 Nucleus split into smaller particles.

More neutrons released.
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Strike more atoms.
Nuclear Fission Reactors
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Control Rods - _____________________ ___________________________that are
lowered into reactor to absorb neutrons.
 Withdrawn to increase rate of fission.
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Moderator - A substance that absorbs _________________________________.
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_________________________________ _________________________________
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Workings of A Nuclear Reactor
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Nuclear reactor serves same function as fossil-fuel boiler: produces heat - converts
water to steam - turns a turbine - generating electricity.
 Light Water Reactors
 _____ of current reactors
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Boiling Water Reactors (BWR)
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Pressurized Water Reactors (PWR)
 Heavy Water Reactors
 Gas Cooled Reactors
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Boiling Water Reactor
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Pressurized-Water Reactor
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Advanced Gas-Cooled Reactor
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Plans for New Reactors Worldwide
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Currently 439 nuclear power reactors in 31 countries.
 Combined capacity of 354 gigawatts.
 Provide ___% of world’s electricity.
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Currently 32 reactors under construction in 10 countries.
 Forecasting becomes uncertain after 2005.
 Most planned reactors in Asia and parts of former Soviet Union.
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Plant Life Extension
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Most nuclear power plants originally had normal design lifetime up to 40 years.
 Engineering assessments have established many plants can operate much
longer.
 Economic, regulatory, and political considerations have thus far led to
premature closure of some plants.
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Investigating Nuclear Alternatives
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Breeder Reactors - Nuclear fission reactor that ______________________________
_____________. (i.e., U238 turns into Pu239)
 Liquid Metal Fast-Breeder (LMFBR)
 Because Pu is very hazardous to humans, and can be made into nuclear
bombs, development has slowed significantly in most regions of the
world.
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Nuclear Fusion
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Nuclear Fusion - When _______________ __________________________________
______________, a large amount of energy is released. – i.e., Sun.
 Huge potential for energy, but technical difficulties of attaining necessary
conditions make this an unlikely fuel candidate for the immediate future.
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Nuclear Fuel Cycle
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Mining of low-grade Uranium ore.
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Naturally occurring Uranium contains about __________________________.
 Much be enriched to ___________to produce weapons-grade material.
 Material is fabricated into a powder and then into pellets.
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Pellets are sealed into metal rods and lowered into the reactor
(Fuel Rods).
Nuclear Fuel Cycle
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As fission occurs, U235 concentration _________________.
 After about three years of operation, fuel rods don’t have enough radioactive
material remaining to sustain a chain reaction, thus spent fuel rods are replaced
by new ones.
 Major source of radioactive waste as each step involves transport of
radioactive materials.
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High-Level Nuclear Waste
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Nuclear Fuel Cycle
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Initially, scientists proposed spent fuel rods could be reprocessed and used to
manufacture new fuel rods.
 Would reduce amount of nuclear waste.
 Extremely dangerous and expensive.
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At present, ___________________
____________________________ ____________________ as
an alternative to storing rods as waste.
Nuclear Material and Weapons Production
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Nuclear power industry is an outgrowth of weapons industry.
 _____________________________is responsible for nuclear research for both
weapons and peaceful uses.
 Research and production have typically dealt with hazardous chemicals
and low-level radioactive materials in the same manner as other waste;
dumping in ground or water.
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Nuclear Material and Weapons Production
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DOE (Formerly Atomic Energy Commission) has become steward of:
 _________________________.
 One million 55-gallon drums of waste.
 More than 330 underground storage tanks with high-level radioactive waste.
 5,700 sites with wastes moving in soil.
 Millions of cubic meters of low-level and high-level radioactive wastes.
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Nuclear Material and Weapons Production
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Clean-up will take years and cost tens of billions of dollars.
 Local residents and host states are not completely trustful.
 Clean-up is new mission for DOE.
 Additional problem of disposing of dismantled nuclear weapons.
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Nuclear Power Concerns
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Currently, 17% of electricity consumed worldwide comes from nuclear power.
 ______________ raised questions about safety.
 _________________________problems.
 Plants may be __________________.
 Spent fuel storage facilities.
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More total radioactivity than the reactor.
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Still not easy, or prime target.
Reactor Safety
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___________________- Pennsylvania
 March 28, 1979 - Partial Core Melt-Down.
 Pump and valve malfunction.
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Operator error compounded problem.
 Crippled reactor was de-fueled in 1990 at a cost of about $1 billion.
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Placed in monitored storage until its companion reactor reaches
the end of its useful life.
Reactor Safety
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_________________ - Ukraine
 April 26, 1986
 Experiments being conducted on reactor.
 Multiple serious safety violations.
 Reactor Explodes.
 31 deaths.
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116,000 people evacuated.
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24,000 evacuees received high doses of radiation.
 Increased thyroid cancer in children.
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Reactor Safety
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A consequence of both of the accidents has been a deepened public concern over
nuclear reactor safety.
 Since 1980, 10 countries have cancelled nuclear plant orders or mothballed
plants under construction.
 Increased Public Opposition:
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United Kingdom:
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Germany:
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United States:
65% - 83%
46% - 83%
67% - 78%
Exposure to Radiation
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Type and degree of damage vary with radiation form, dosage and duration of exposure,
and type of cells irradiated.
 Because mutations are permanent, radiation effects may build up over years
and only appear later in life.
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Exposure to Radiation
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Human exposure usually expressed in ____.
 Measure of biological damage to tissue.
 The higher the dose, the more observable the results.
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No human is subject to zero exposure.
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Average person exposed to 0.2 to 0.3 rems per year
from natural and medical sources.
Thermal Pollution
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Addition of waste heat to the environment.
 Especially dangerous in aquatic systems.
 In a nuclear power plant, ____ of heat used to generate electricity while
the other ____ is waste.
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Fossil fuel plants are _______.
 To reduce the effects of waste heat, utilities build cooling facilities.
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Ponds
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Towers
Decommissioning Costs
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Life expectancy of most electrical generating plants is 30-40 years.
 Unlike other plants, nuclear plants are decommissioned, not demolished.
 Involves _______________________
______________________________ ___________________________.
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Over 70 nuclear power plants in the world are awaiting
decommissioning.
Decommissioning Costs
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By 2005, 68/104 U.S. plants will be at least 20 years old.
 Nuclear Regulatory Commission may extend authorization an additional 20 yrs.
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Decommissioning Uncertainties
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Utilities Have (3) Options:
 ________________________plant ASAP.
 ______________plant for 20-100 years, allowing radiation to dissipate, then
dismantle.
 ____________ plant within concrete barrier.
 Recent experience indicates decommissioning a large plant will cost
between $200 and $400 million.
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Radioactive Waste Disposal
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Today, the U.S. has 380,000 cubic meters of highly radioactive military waste
temporarily stored at several sites.
 Waste Isolation Pilot Plant (WIPP) Carlsbad, NM began accepting waste in
March, 1999.
 ____________________- High-level radioactive waste consisting
primarily of various isotopes of plutonium.
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Radioactive Waste Disposal
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In addition to high-level waste from weapons programs, 2 million cubic meters of lowlevel radioactive military and commercial waste are buried at various sites.
 About 30,000 metric tons of highly radioactive spent fuel rods are stored in
special storage ponds at nuclear reactor sites.
 Many plants are running out of storage.
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Radioactive Waste Disposal
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High Level Radioactive Waste:
 At this time, no country has a permanent storage solution for the disposal of
high-level radioactive waste.
 Politics of disposal are as crucial as disposal method.
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Most experts feel the best solution is to bury waste in a stable
geologic formation.
High-Level Waste Storage in the United States
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In _______, Congress called for a high-level radioactive disposal site to be selected by
March _____, and to be completed by ____.
 In _____, the Secretary of Energy indicated the choice of a site at Yucca
Mountain in Nevada was based on scientifically sound and suitable science.
 Current work is primarily exploratory and is seeking to characterize the
likelihood of earthquake damage and water movement.
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High-Level Waste Storage in the United States
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If completed, the facility would hold about 70,000 metric tons of spent fuel rods and
other highly radioactive material.
 Not to be completed before ________.
 By that time, waste produced by nuclear power plants will exceed the
storage capacity of the site.
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Low-Level Radioactive Waste
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Includes __________________________ _________________________________
_________________________________.
 Prior to 1970, U.S. alone placed 90,000 barrels of low-level radioactive waste on
the ocean floor.
 Moratorium in ______, banned in ____.
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Low - Level Waste
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Currently, U.S. produces about 800,000 cubic meters of low-level radioactive waste
annually.
 Presently buried in various scattered disposal sites.
 Political limbo.
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Politics of Nuclear Power
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Nuclear power is projected to represent a shrinking share of the world’s electricity
consumption from 2004 through 2025.
 Most nuclear additions are expected to be in Asia. (China, India, Japan, S. Korea)
 Life extension and higher capacity factors will play a major role in
sustaining the U.S. nuclear industry throughout this period.
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Politics of Nuclear Power
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Nuclear power projections are subject to considerable uncertainty, both economic and
political.
 In large part, governmental support for nuclear power has waxed and waned
with the changing of government regimes.
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Review
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Nature of Nuclear Energy
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Nuclear Fuel Cycle
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History of Nuclear Energy
Development
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Nuclear Material and Weapons
Production
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Nuclear Fission Reactors
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Nuclear Power Concerns
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Investigating Nuclear
Alternatives
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Politics of Nuclear Power