Sustainable Energy Systems Sustainable Energy Systems EngineeringEngineering

Peter GevorkianPeter Gevorkian

Ch 15: Nuclear EnergyCh 15: Nuclear Energy

Brevard Community CollegeBrevard Community College

EST1830EST1830

Bruce HesherBruce Hesher

IntroductionIntroduction

There are There are 22 type of nuclear reactions: type of nuclear reactions:

FissionFission: What man does in nuclear power plants. : What man does in nuclear power plants. Uses uranium 235 and steam turbines. Provides Uses uranium 235 and steam turbines. Provides about 17% of the worlds electricity. 75% in about 17% of the worlds electricity. 75% in France; 15% in the USA. France; 15% in the USA.

FusionFusion: What the sun does. Turns hydrogen into : What the sun does. Turns hydrogen into Helium. Man is yet to make a viable fusion Helium. Man is yet to make a viable fusion reaction.reaction.

International Atomic Energy International Atomic Energy Association (IAEA)Association (IAEA)

The IAEA is the world's center of cooperation in the The IAEA is the world's center of cooperation in the nuclear field. It was set up in 1957 as the world's nuclear field. It was set up in 1957 as the world's "Atoms for Peace" organization within the United "Atoms for Peace" organization within the United Nations family. The Agency works with its Member Nations family. The Agency works with its Member States and multiple partners worldwide to promote States and multiple partners worldwide to promote safe, secure and peaceful nuclear technologies.safe, secure and peaceful nuclear technologies.

See: See: http://www.iaea.org

Nuclear Power Plants WorldwideNuclear Power Plants Worldwide

Warning: Warning: There are a lot of things posted on the There are a lot of things posted on the Internet about nuclear energy. Some are posted Internet about nuclear energy. Some are posted by groups with strong opinions and agendas!by groups with strong opinions and agendas!

Status of Nuclear Energy by NationStatus of Nuclear Energy by Nation

U.S. Nuclear Power PlantsU.S. Nuclear Power Plants

See: www.insc.anl.gov/pwrmaps/map/north_america.php

FPL Fuel MixFPL Fuel Mix

See See www.fpl.com/environment/plant/power_plant_projects.shtml

Status of Nuclear Energy in United StatesStatus of Nuclear Energy in United States

Number of operable reactors: Number of operable reactors: 105105

Total capacity, (MWe net): Total capacity, (MWe net): 9599095990

Reactor-years of operation to date: Reactor-years of operation to date: 26342634

Number of units shutdown or decomissioned: Number of units shutdown or decomissioned: 2525

Properties of Uranium Properties of Uranium p333p333

Heavy elements like uranium are Heavy elements like uranium are made in super nova eventsmade in super nova events**. Uranium . Uranium has 234 to 238 orbiting electrons. Un-has 234 to 238 orbiting electrons. Un-enriched uranium (U-235) has 235. 99% enriched uranium (U-235) has 235. 99% of naturally occurring uranium is 238 of naturally occurring uranium is 238 which has a half life of 4.5 billion years.which has a half life of 4.5 billion years.

See See http://en.wikipedia.org/wiki/Uranium

P333 of text states that uranium was made P333 of text states that uranium was made in the big bang. I question this.in the big bang. I question this.

Fission reaction

Uranium OreUranium Ore

Technically not a renewable Technically not a renewable resource, there is a lot of uranium resource, there is a lot of uranium ore. ore.

EnrichmentEnrichment Enriching uranium increases the proportion of uranium atoms that can Enriching uranium increases the proportion of uranium atoms that can be "split" by fission (U-235) to release energy (usually in the form of heat) be "split" by fission (U-235) to release energy (usually in the form of heat) that can be used to produce electricity. Not all uranium atoms are the that can be used to produce electricity. Not all uranium atoms are the same. When uranium is mined, it consists of about 99.3% uranium-238 or same. When uranium is mined, it consists of about 99.3% uranium-238 or U-238 (U238), 0.7% uranium-235 or U-235 (U235), and < 0.01% uranium-U-238 (U238), 0.7% uranium-235 or U-235 (U235), and < 0.01% uranium-234 or U-234 (U234). These are the different isotopes of uranium, which 234 or U-234 (U234). These are the different isotopes of uranium, which means that while they all contain 92 protons in the atom’s center, or means that while they all contain 92 protons in the atom’s center, or nucleus (which is what makes it uranium), the U238 atoms contain 146 nucleus (which is what makes it uranium), the U238 atoms contain 146 neutrons, the U235 atoms contain 143 neutrons, and the U234 atoms neutrons, the U235 atoms contain 143 neutrons, and the U234 atoms contain only 142 neutrons. (The total number of protons plus neutrons contain only 142 neutrons. (The total number of protons plus neutrons gives the gives the atomic massatomic mass of each isotope — that is, 238, 235, or 234, of each isotope — that is, 238, 235, or 234, respectively.) respectively.)

The fuel for nuclear reactors has to have a higher concentration of U235 The fuel for nuclear reactors has to have a higher concentration of U235 than exists in natural uranium ore. This is because U235 is "fissionable," than exists in natural uranium ore. This is because U235 is "fissionable," meaning that it starts a nuclear reaction and keeps it going. Normally, the meaning that it starts a nuclear reaction and keeps it going. Normally, the amount of the U235 isotope is enriched from 0.7% of the uranium mass to amount of the U235 isotope is enriched from 0.7% of the uranium mass to about 5%.about 5%.

Nuclear FissionNuclear Fission

Just as conventional power stations generate electricity Just as conventional power stations generate electricity by harnessing the thermal energy released from burning by harnessing the thermal energy released from burning fossil fuels, nuclear reactors convert the thermal energy fossil fuels, nuclear reactors convert the thermal energy released from nuclear fission.released from nuclear fission.

A neutron is absorbed by the nucleus A neutron is absorbed by the nucleus of a uranium-235 atom, which in turn of a uranium-235 atom, which in turn splits into fast-moving lighter elements splits into fast-moving lighter elements (fission products) and free neutrons. (fission products) and free neutrons. Though both reactors and nuclear Though both reactors and nuclear weapons rely on nuclear chain weapons rely on nuclear chain reactions, the rate of reactions in a reactions, the rate of reactions in a reactor is much slower than in a bomb reactor is much slower than in a bomb

Nuclear Fission Power PlantsNuclear Fission Power Plants

Nuclear power plants use nuclear Nuclear power plants use nuclear fission to produce energy. In nuclear fission to produce energy. In nuclear fission, the nuclei of atoms are split, fission, the nuclei of atoms are split, causing energy to be released. The causing energy to be released. The element uranium is the main fuel used element uranium is the main fuel used to undergo nuclear fission to produce to undergo nuclear fission to produce energy. energy.

A nuclear power plant, like other A nuclear power plant, like other electricity producing power plants, electricity producing power plants, simply boils water to produce steam, simply boils water to produce steam, which turns turbines which produce which turns turbines which produce electricity. The main difference is electricity. The main difference is that with nuclear fission the heat that with nuclear fission the heat generated from the fission heats the generated from the fission heats the water instead of the water being water instead of the water being heated by using oil, gas or coal. heated by using oil, gas or coal.

Nuclear Power ReactorsNuclear Power Reactors

There are many different There are many different types of power reactors. types of power reactors. What is common to them What is common to them all is that they produce all is that they produce thermal energy that can be thermal energy that can be used for its own sake or used for its own sake or converted into mechanical converted into mechanical energy and ultimately, in energy and ultimately, in the vast majority of cases, the vast majority of cases, into electrical energy.into electrical energy.

Reactor ControlReactor Control

Control rods can be lowered into the Control rods can be lowered into the reaction chamber to reduce the reaction chamber to reduce the amount of energy (heat) released from amount of energy (heat) released from the fissile uranium. Water flowing the fissile uranium. Water flowing through the reaction chamber turns to through the reaction chamber turns to steam.steam.

Pros & Cons of Nuclear PowerPros & Cons of Nuclear Power((opinions varyopinions vary))

Pros:Pros:• Readily available technologyReadily available technology• Makes a lot of electricityMakes a lot of electricity• DomesticDomestic• Low carbon foot printLow carbon foot print

Cons:Cons:• Uranium is not renewable (estimated 30-60year resource)Uranium is not renewable (estimated 30-60year resource)• Spent rods must be secured and storedSpent rods must be secured and stored• Accidents can happenAccidents can happen• Nuclear plants could be terrorist’s targets.Nuclear plants could be terrorist’s targets.

• Permitting and plant construction takes 20-30 years!Permitting and plant construction takes 20-30 years!

Fusion ReactorsFusion Reactors

The sun uses nuclear fusion The sun uses nuclear fusion to produce energy, but man to produce energy, but man is yet to make a sustainable is yet to make a sustainable fusion reaction. Scientists fusion reaction. Scientists predict that a fusion reaction predict that a fusion reaction would make more energy would make more energy than a fission reaction and than a fission reaction and would make more fuel than it would make more fuel than it would consume. This would would consume. This would make nuclear energy a make nuclear energy a renewable energy!renewable energy!

See Helium 3.See Helium 3.

They will use abundant They will use abundant sources of fuel, they will sources of fuel, they will not leak radiation above not leak radiation above normal background levels normal background levels and they will produce less and they will produce less radioactive waste than radioactive waste than current fission reactors.current fission reactors.