Announcements – Nov. 6, 2006

Review next Monday3rd Exam next Wednesday

No class next Friday.

History of Nuclear Development

First controlled fission—Germany 1938.

1945—U.S. dropped atomic bombs on Hiroshima and Nagasaki.

U.S. built world’s first nuclear power plant in 1951

Currently, 8.4% of U.S. energy from nuclear power

The Nature of Nuclear Energy

Nuclear Chain Reaction — Splitting nuclei release neutrons, which strike more nuclei, releasing even more neutrons….

Nuclear Fission — Occurs when neutrons impact and split the nuclei of certain atoms.

The Nature of Nuclear Energy

• Only certain kinds of atoms are suitable for development of a nuclear chain reaction.

– Uranium 235 (number of neutrons + protons = 235)– Plutonium 239 (number of neutrons + protons = 239)

• Natural Uranium ore only has 0.7% U-235– enriched to 3% to sustain chain reaction– fabricated into pellets– sealed in fuel rods– transported to nuclear power plant

Nuclear Power Plants in North America

IllinoisNumber of nuclear units: 11 Braidwood 1-2, Braidwood, Ill.Byron 1-2, Byron, Ill.Clinton, Clinton, Ill.Dresden 2-3, Morris, Ill.LaSalle 1-2, Seneca, Ill.

Quad Cities 1-2, Cordova, Ill.

Workings of A Nuclear Reactor

Generates electricity

Chain reaction produces heat

Converts water to steam

Turns a turbine

Nuclear Reactor — Device that permits a controlled fission chain reaction.

Nuclear Fuel Cycle

• As fission occurs, U235 concentration in fuel rods decreases.

• After about 3 years, fuel rods don’t have enough radioactive material left to sustain a chain reaction

• Spent fuel rods are replaced by new ones.– What to do with the spent fuel rods?

Environmental Impacts of Nuclear Power

• More than 330 underground storage tanks currently exist with high-level radioactive waste.

• 5,700 sites have wastes moving through soil.

• Clean up will take years and cost tens of billions of dollars.

– Environmental clean up single largest item in DOE budget.

Nuclear Wastes

U.S. DOE Waste Sites

Radioactive Waste Disposal

• High Level:– At this time, NO country has a permanent

storage solution for high-level waste.

– Politics of disposal are as crucial as disposal method.

– Waste Isolation Pilot Plant (WIPP) Carlsbad, NM began accepting waste in March, 1999.

Environmental Impacts of Nuclear Power

High-Level Waste• In 1982, Congress called for a high-

level radioactive disposal site to be selected by 1987, and to be completed by 1998.

• Final Site Selection Occurred in 1989.– Yucca Mountain, Nevada

Not to be completed before 2015. By that time, waste produced

by nuclear power plants will exceed the storage capacity of the site.

Low-Level Waste

Currently, U.S. produces about 800,000 m3 of low-level radioactive waste annually.

Presently buried in various scattered disposal sites.

Includes cooling water from nuclear reactors, material from decommissioned reactors, protective clothing, etc.

Prior to 1970, U.S. alone placed 50,000 barrels of low-level radioactive waste on the ocean floor. Banned in 1983.

Environmental Impacts of Nuclear Power

• In a nuclear power plant, 1/3 of heat used to generate electricity while the other 2/3 is waste heat.

– Fossil fuel plants are 50:50.

Thermal Pollution - Addition of waste heat to the environment

Dangerous to aquatic systems

Nuclear Power Concerns

• Currently, 17% of electricity consumed worldwide comes from nuclear power.

– Contamination and disposal problems.

– Accidents raised questions about safety.

– Life expectancy of reactors originally only 20 years, now extended to 40-60 years

•Three Mile Island—PA

March 28, 1979—Partial Core Melt-Down.

Pump and valve malfunctionCompounded by false readout and operator error

No Deaths

Very Little Radiation Vented

Public Relations Disaster

Chernobyl—Ukraine –April 26, 1986

Chernobyl — Ukraine

Experiments were being conducted on one reactor

Reactor Explodes

Numerous safety violations

Chernobyl—Ukraine

Increases in Thyroid cancer rate by 10x

31 deaths

116,000 people evacuated

24,000 evacuees received high doses of radiation

Fallout in Scandinavia and Europe

New York Times Store Photo: National Guard during October 15, 2004 U.S. Investigating AccidentThat Shut Down Salem Reactor On Sunday afternoon, operators shut down the Hope Creek nuclear reactor in southwestern New Jersey after a pipe ruptured, sending a cloud of radioactive steam into the building that contains the giant turbine used to generate electricity from the reactor. Federal officials said that as operators worked to shut down the reactor, a key control system malfunctioned and the employees had difficulty finally stabilizing the water that is used to cool the reactor's radioactive core. Officials at the Nuclear Regulatory Commission and at the company that owns the reactor, P.S.E.G. Nuclear L.L.C., said the incident did not pose a threat to the public

A comment on these alternative sources:

Source Energy producedHydroelectric ElectricityWind ElectricitySolar Electricity, Direct HeatingTidal ElectricityGeothermal ElectricityLake Source CoolingNuclear Electricity

But current fossil fuel use is:Transportation 26.3%Electricity 30.1%Industrial 21.8%Residential/Commercial 7.5%

Can we decrease use of fossil fuels for transportation and industrial fuel use?

>95% of Transportation energy supplied by petroleum

“In transportation uses, in contrast, there is little fuel substitution possible in the short term and only limited potential in the longer term, given current technology” – Oil Market Basics, www.eia.doe.gov

Vast majority of automobiles & trucks run on gasoline or diesel

Major infrastructure of gas stations not easily converted to other fuels

Buenos Aires, ArgentinaOver 200,000 taxis use natural gas as fuel.

Alternatives to gas-powered autos

1) Electric limited range,lack of power stations

2) Hybrid electric greatly increased MPG, becoming more popular Still uses gas, can use existing infrastructure

3) Methanol/Ethanol (biofuels) Biomass conversion (organic wastes, crops) Still uses gas; food shortages, loss of productivity

4) Fuel cells can only produce water, heat, electricity takes more energy to produce At least 10 years to commercial market

BMW sets 9 records with Hydrogen Combustion Engine. Top Speed over 300 km/h

A fundamental consideration is that the combustion properties of hydrogen are quite different from those of gasoline or diesel: While hydrogen burns faster than conventional fuels under normal air pressure, the combustion temperature is slightly lower than in the case of gasoline.

Hydrogen cars…. Only waste is water!

But, where will we get pure hydrogen (H2)?- still need to burn fossil fuels to produce H2!

Biofuels: Green energy or grim reaper?22 September 2006, Jeff McNeeley

“Biofuels could end up damaging the natural world rather than saving it from global warming. Better policies, better science and genetic modification call contribute to a greener biofuels revolution.”

Biofuels = “deforestation diesal”

Grain required to flil an SUV with ethanol could feed one person for one year.

Much of plant material imoported from Brazil where deforestation continues.

Ethanol from maize in U.S. require fossil fuels at every stage in production process.

cultivation, fertilizers, tractors, processing, transportation

Up to 30% more energy spent than gained.

Other options?

Conservation!!!• Most current energy use is highly inefficient

– Lobbying against regulated increases in automobile efficiency (MPG)

– Little development of mass transit and railroad transportation

– Most construction done with “cheaper,” energy inefficient materials

– Industrial machines and practices are energy inefficient

• $$ given as reason, but are we/they really saving money in the long run??

What you can (easily) do conserve energy:

1) Replace incandescent light bulbs with fluorescent.

2) Make sure car tires at proper air pressure and use recommended grade of gas.

3) Consider biking, walking, carpooling, taking bus or train.

4) Buy energy efficient appliances, insulate house, replace windows.

5) Consider buying hybrid electric vehicle or one with higher MPG.

Points to know

1) Why is there controversy surrounding drilling in ANWR? What are the issues?

2) Know the major uses of oil, natural gas, and coal. What current proportion of energy in the U.S. is supplied by fossil fuels, and how does that break down by area?

3) Know the pros and cons of hydroelectric, wind, solar, and nuclear power.

4) What is the main problem with most alternative sources of energy in regards to lowering our dependence on fossil fuels?

5) Why it is more difficult to use alternative energy sources for transportation? What alternatives are there?

6) What are some easy ways to conserve energy?