U Th + Energy Natural “spall-off” Masses are not quite equal on both sides. The difference is ENERGY. e = mc 2 massenergy Natural radioactive.

EPSc 116: Resources of the Earth

Lecture 14 on Ch. 6: Nuclear Energy

Focal Points

We already are producing a great deal of energy from nuclear power plants.

We need to understand how electricity is generated from nuclear fuel and

the various ramifications of that process (safety of nuclear plant and

nuclear waste)

Radiation: What is it? How is it harmful?

Nuclear fission: How does it operate? How is it controlled?

Nuclear reactors: Operation, safety, efficiency

Nuclear waste: What exactly is it? How can we safely dispose of it?

Other concerns, Japanese nuclear crisis at Fukushima

www.darvill.clara.net/altenerg/index.htm

Overview of Options for Energy Sources

3 sources of Earth’s energy:

Solar Geothermal Tidal

Early 2012 view of worldwideproduction ofenergy accordingto the source ofthe energy

The Nuclear Option: World Nuclear Energy Production

Nuclear energy = 14% world’s electricity 78% of France’s electricity 20% of United States’ electricity

>430 nuclear power plantsworldwide, in 30 countries

~ 100 nuclear power plantsoperating in the US

According to the World Nuclear Association, thesewere the top 10 nuclear-dependent nations in 2011:

France – 77.7% of its electricity from nuclear Belgium – 54.0% Slovakia – 54.0%

Ukraine – 47.2% Hungary – 43.2% Slovenia – 41.7% Switzerland – 40.8%

Sweden – 39.6% South Korea – 34.6% Armenia – 33.2%

Japan and Germany endingall nuclear power generation Based on US EIA data

Top 5 Nuclear-Energy-Producing Countries

Nuclear Power Plants Authorized to Operate in US

Data from NRC (Nuclear Regulatory Commission). Posted on Wikipedia, 2007

in Missouri

Nuclear Energy Institute

U Th

+ Energy

+ Energy

H3

1

mass

# protons =# electrons

Natural “spall-off”Masses are not quite equal on both sides. The difference is ENERGY.

e = mc2

mass energy

Natural radioactive elements constantly break down and release energy – all around us.

Fission-induced processes occur in a reactor. Controlled, imposed.

From Hinrichs, 1992, Energy.

Nuclear Reactions

Heavy hydrogen

Forms of Radiation

Meaning of Half-Life of a Radioactive Element

Slow rate of decay long half-life

Fast rate of decay short half-life

The longer the half-life of a radioactive element, the longer we have to worry about the radiation it is emitting.

From Hinrichs, 1992, Energy.

Natural disintegration vs. induced fission. Why bother with fission?

Direction in which to gain energy.

Why Energy is Released from Fission: Our Gain

Fission: Break apart into smaller pieces

Fusion: join to form larger pieces

How We Get “Nuclear Energy”

+ Energy

+ Energy

Bring in the neutrons

Get a chain reaction going

From Hinrichs, 1992, Energy.

235U vs. 238U

Why Anyone Would Want to Consider Nuclear Energy

35 tons of uranium dioxide (UO2) fuel produces 1000 MWe electricity.

This can be done with 1 nuclear fuel shipment per year compared to 1 trainload of coal per day in a power plant.

From Hinrichs, 1992, Energy.

Nuclear energy facilities have highest average capacity factor of all U.S. elec tricity sources.“Capacity factor” compares actual energy production with how much could be produced at fulloperating power. Crucial measure of reliability and a plant’s online performance.

Nuclear energy has tremendous price stability because fuel accounts for just 28% of productioncosts. Fuel costs closer to 80 or 90% when electricity produced by burning coal or natural gas.Makes electricity from fossil-fuel-powered plants highly susceptible to fluctuations in fuel prices.

Why

Consider

Nuclear

Power?

Nuclear Energy Institute

http://www.whatisnuclear.com/articles/nucreactor.html

Heat exchanger, which allows heat from the water in contactwith the reactor core to be transferred to “clean water” thatthen will become steam. No radiation is transferred.

Basics of a Nuclear ReactorThere are numerous types of nuclear reactors. Core = working part of the reactor. It contains: fuel rods (uranium oxide), a moderator (to slow theneutrons), water (for heat exchange), control rods(to shut down the nuclear reaction).

Another heat exchanger; heated water goes into river, etc.

Addressing the Safety Issuein Nuclear Power Plants

Different design for the fuel – better controllable and contained

Smaller power plants – lower output, less nuclear fuel, smaller core

Pebble-bed Reactor

http://www.euronuclear.org/info/encyclopedia/p/pebble.htm

Concept of “passive safety”

http://www.world-nuclear.org/info/inf03.html

Start here

The Issue of Nuclear Waste

Radon -- colorless, odorless, radioactive gas (undergoes radioactive decay)

Radon occurs naturally as an intermediate breakdown product as naturaluranium and thorium undergo radioactive decay

Special health concerns:

Gas – quite mobile, can be inhaled

Radioactive, half-life of 3.8 days

Produces alpha particles: lung cancer

Accounts for greatest amount of radiation an individual encounters

Can become concentrated in soils and groundwaters

Mitigation measures in homes (basements)

The Radon Issue

http://www.radon.com/radon/radon_EPA.html

RADON ENTERS HOMES THROUGH:Cracks in solid floors; soil Construction joints Cracks in walls Gaps in suspended floors Gaps around service pipes Cavities inside walls The water supply http://www.epa.gov/radon/pubs/citguide.html

CVS4, Fig. 4.C

Radon gas forms in soil through radioactive decay of naturally occurring uranium and thorium

Radon Problems and Mitigation

A suction-based removal system can be installed to vent radon before it enters a home’s basement.

Mobility: some elements are called mobile, because they like tostay dissolved in water (remaining mobile). Others are not verysoluble (rather, precipitating out as part of a mineral), makingthem immobile.

U4+ (immobile) vs. U6+ (mobile):

Uranium is less soluble (forms a mineral) in reducing conditions, as in swamps, coal deposits.

Uranium concentration naturally enhanced in types of rock whoseminerals "accept" uranium, e.g., granites (feldspars, micas),phosphorites (phosphate-rich sedimentary rocks)

US is moderately well off in terms of uranium reserves andresources

Geology of Uranium Ore Deposits

CVS4, Fig. 6.15 “Roll-type” uranium

Reducing Oxidizing

Text, Fig. 6.14

Sources of Uranium in the US

Chemical affinity of uranium for certain geologic environments and certain other elements causes its selective enrichment.

x

http://www.chemistry.mcmaster.ca/emslie/20%20emslie%20Th%20U%20info%20v2.htm

Concerns about Nuclear Power Plant Safety

Three Mile Island, near Harrisburg, PA, 1979:

Meltdown, but hardly any release of radioactivity

Huge loss in public confidence, however

Chernobyl, Ukraine, 1986 (Box 6.2, Fig. 6.9):

Meltdown. 10% of core’s material lofted into atmosphere

Terrible impact all over Europe and beyond (see Fig. 6.9 map)

Fukushima, Japan (March, 2011):

Earthquake hit; reactors shut down

Tsunami interrupted electrical power and thus, cooling;

caused reactors to overheat

3 reactors ultimately underwent meltdown

Fukushima Daiichi Nuclear Disaster in Japan in March, 2011

Boiling water reactors

Earthquake hit; reactors shut down

Tsunami interrupted electricity for cooling; caused reactors to overheat

3 reactors ultimately underwent meltdown

http://www.radon.com/radon/radon_EPA.html

Concerns about Radiation

See opinion pieces: 2011 Scientific American, 2012 Wall Street Journal

Where are we with Nuclear Energy?

Problems with Nuclear Energy

Reactor safety; fear of: leakage, melt-down and huge release, terrorismNuclear waste is very dangerous; needs containment for many thousand yearsWaste disposal: transport of wastes to disposal sites has risks (breaches, terrorists)

Waste storage must be secure from corrosion, earthquakes, tsunamis, terrorists Mining and processing of uranium have health and disposal issuesDecommissioning of nuclear power plants: proper shutdown and "disposal"

Advantages (over alternative sources) of Nuclear Energy

No: greenhouse gases, dust/ash, other pollutants typically emitted to air (Hg, SO2, CO2)

Less radiation typically released than from a coal-fired power plantLarge reserves of uranium in US and worldwideElectricity generated costs about same as from coal-fired power plantsProduces very large amounts of electricity from a small amount of fuelProduces little waste for a given amount of electricity producedVery reliable and on-demand, unlike many/most alternative energy sources

For more than 20 years, Electric Utility Consultants, Inc. has led the way in producing the highest-quality conferences, seminars, workshops, and courses designed exclusively for the energy industry. We offer solutions, not just vacuous information, and seek to help industry professionals make informed, intelligent decisions to strategically improve their position in today's challenging business environment.

EUCI’s Course:

Nuclear Power Fundamentals

Steps in the

Radioactive Decay

of Uranium to Lead

From http://en.wikipedia.org/wiki/Radon

Uranium

Decay Series

Radon

http://world-nuclear.org/info/inf02.html

Why Consider Nuclear Power?

Nuclear Energy Institute

Recent (2011-2014) closures of nuclear power plants in Japan, Europe, and the US haveproduced a rise in carbon emissions in most cases.

Source: Energy Information Administration, Annual Energy Outlook 2013,http://www.eia.gov/forecasts/aeo/er/pdf/appa.pdf and http://www.eia.gov/forecasts/aeo/er/pdf/tbla17.pdf

Energy Consumption Fuel Shares, 2011 and 2040Note: NOT Electricity Production