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Nonrenewable Energy Source: Nuclear
Nonrenewable Energy Source: Nuclear
Pages and Files
Nuclear: Science Home Page
Nuclear: Law and Gov't
ENERGY STUDY HOME
Table of Contents
History of Nuclear Energy
Extraction And Refinement
Recovery from Seawater
Nuclear Fission Process
Map of U.S. Nuclear Reactors
Pros and Cons
History of Nuclear Energy
The following time line shows the most important Nuclear Energy advances in the US until 2000. The most important one are in
Mushroom Cloud from the Nuclear Blast at Hiroshima, Japan
December 2, 1
— Dr. Enrico Fermi achieves the first controlled nuclear chain reaction with the first demonstration reactor—the Chicago Pile 1.
— The U.S. drops an atomic bomb on Hiroshima, Japan, and three days later drops another bomb on Nagasaki. World War II ends days later.
August 1, 1946
— President Harry S. Truman signs the Atomic Energy Act of 1946, putting the fledgling nuclear energy industry under civilian control, and creating the powerful Joint Congressional Committee on Atomic Energy.
The first Boiling Water Reactor BORAX III
December 20, 1951
— An experimental reactor produces the first electric power from the atom, lighting four lightbulbs.
August 30, 1954
— President Eisenhower signs the Atomic Energy Act of 1954, the first major amendment of the original Atomic Energy Act, giving the civilian nuclear energy program further access to nuclear technology.
July 17, 1955
— The first U.S. town is powered by nuclear energy—Arco, Idaho, population 1,000—by the experimental boiling water reactor BORAX III.
December 2, 1957
— The first full-scale nuclear power plant at Shippingport, Pennsylvania, goes into service. Twenty-one days later it reaches full power, generating 60 megawatts of electricity.
October 15, 1959
— Dresden-1 Nuclear Power Station in Illinois, the first U.S. plant built entirely without government funding, achieves a self-sustaining nuclear reaction.
First Nuclear Reactor to operate in Space
August 19, 1960
— The third U.S. nuclear power plant, Yankee Rowe Nuclear Power Station, achieves a self-sustaining nuclear reaction.
March 17, 1962
— President John F. Kennedy asks the Atomic Energy Commission to report on the role of nuclear energy in the economy.
December 12, 1963
— Jersey Central Power and Light Company announces its commitment for the Oyster Creek nuclear power plant, the first time a nuclear plant is ordered as an economical alternative to a fossil-fuel plant.
April 3, 1965
— First nuclear reactor operates in space.
— The Atomic Energy Commission gives the Liquid Metal Fast Breeder reactor highest priority and decides to build the Fast Flux Test Facility. The facility begins operation in April 1982.
President Carter Leaving the Three-Mile Island Facility
October 17, 1973
— The Organization of Petroleum Exporting Countries (OPEC) agrees to use oil as a foreign policy weapon, cutting exports 5 percent until Israel withdraws from Arab territory occupied during the Yom Kippur War. Days later Saudi Arabia cuts oil production by 25 percent and joins many other oil-producing nations in embargoing oil shipments to the United States.
— U.S. utilities order 41 nuclear power plants, a one-year record.
— The first 1,000-MWe nuclear plant goes into service—Commonwealth Edison's Zion 1 plant.
April 7, 1977
— President Jimmy Carter announces a new policy banning reprocessing of used nuclear fuel.
March 28, 1979
— A major accident occurs at Unit 2 of the Three Mile Island nuclear plant near Harrisburg, Pennsylvania. Damage is limited to inside the reactor, and no one is injured.
The Perry Power Plant in Ohio
— Nuclear energy generates more electricity than oil.
October 8, 1981
— President Ronald Reagan's administration lifts the ban on reprocessing used nuclear fuel and announces a policy that anticipates the need for a high-level radioactive waste storage facility.
— Nuclear energy generates more electricity than natural gas.
— The atom overtakes hydropower to become the second-largest source of electricity, after coal.
— The Perry power plant in Ohio becomes the 100th U.S. nuclear power plant in operation.
The Comanche Peak Unit 2 facility in Texas
— America's nuclear power plants set record for amount of electricity generated, surpassing the 1956 level for all fuel sources combined.
— Nuclear power plants account for about 20 percent of all electricity used in the United States.
April 6, 1993
— Another nuclear power plant—the Comanche Peak Unit 2 in Glen Rose, Texas—goes on line, providing 1,150 megawatts of electricity to U.S. consumers.
Jan. 14, 1994
— More than a half century after President Eisenhower stood before the United Nations and urged the countries of the world to take nuclear materials "out of the hands of the soldiers...[and place them] into the hands of those who will...adapt [them] to the arts of peace," the U.S. again leads the world in promoting the peaceful uses of nuclear technology by signing a contract to buy uranium from the Russian Federation that could be blended down into power plant fuel, ensuring it will never again be used for warheads.
Feb. 9, 1996
— The NRC grants the Tennessee Valley Authority (TVA) a full-power license for its Watts Bar 1 nuclear power plant, bringing the number of operating nuclear units in the United States to 110.
For more information about the history of Nuclear Energy, use this website!
Extraction And Refinement
There are 5 types of Uranium extraction.
Open-pit mining starts with the removal of overburden (material covering) on top of the uranium to expose the orebody. A pit is then hollowed out to access the deposit. To prevent the pit’s walls from caving in, the rock is mined in a series of benches. Holes are drilled into the rock in each bench and loaded with explosives. The explosives are then detonated to break up the rock, which would be taken to the surface by large trucks. The largest open-pit uranium mine in the world is the Rössing mine in Namibia.
If the uranium is too far below the surface for open pit mining, an underground mine might be used with tunnels and shafts dug to access and remove uranium ore. There is less waste material removed from underground mines than open pit mines, however this type of mining exposes underground workers to the highest levels of radon gas.
Once the ore body has been identified a shaft is sunk in the vicinity of the ore veins, and crosscuts are driven horizontally to the veins at various levels, usually every 100 to 150 metres. Similar tunnels, known as drifts, are driven along the ore veins from the crosscut. To extract the ore, the next step is to drive tunnels, known as raises when driven upwards and winzes when driven downwards through the deposit from level to level. Raises are subsequently used to develop the stopes where the ore is mined from the veins.
The stope, which is the workshop of the mine, is the excavation from which the ore is extracted. Two methods of stope mining are commonly used. In the "cut and fill" or open stoping method, the space remaining following removal of ore after blasting is filled with waste rock and cement. In the "shrinkage" method, only sufficient broken ore is removed via the chutes below to allow miners working from the top of the pile to drill and blast the next layer to be broken off, eventually leaving a large hole. Another method, known as room and pillar, is used for thinner, flatter ore bodies. In this method the ore body is first divided into blocks by intersecting drives, removing ore while so doing, and then systematically removing the blocks, leaving enough ore for roof support.
In some cases, uranium is extracted from low-grade ore by heap leaching. This may be done if the uranium contents is too low for the ore to be economically processed in a uranium mill. The crushed ore is placed on a leaching pad with a liner. The leaching agent (alkaline, or sulfuric acid) is introduced on the top of the pile and percolates down until it reaches the liner below the pile, where it is caught and pumped to a processing plant. After completion of the leaching process (within months to years), the leached ore is either left in place, or removed to a disposal site, and new ore is placed on the leach pad (so-called on/off scheme, or dynamic heap leaching).
During leaching, the piles present a hazard because of release of dust, radon gas and leaching liquid.
After completion of the leaching process, a longterm problem may result from naturally induced leaching, if the ore contains the mineral pyrite (FeS2), as with the uranium deposits in Thuringia, Germany, for example). Then, acces of water and air may cause continuous bacterially induced production of sulfuric acid inside the pile, which results in the leaching of uranium and other contaminants for centuries and possibly permanent contamination of ground water.
In situ leaching (ISL), also known as solution mining, or in situ recovery (ISR) in North America, involves leaving the ore where it is in the ground, and recovering the minerals from it by dissolving them and pumping the pregnant solution to the surface where the minerals can be recovered. Consequently there is little surface disturbance and no tailings or waste rock generated. However, the orebody needs to be permeable to the liquids used, and located so that they do not contaminate ground water away from the orebody.
Uranium ISL uses the native groundwater in the orebody which is fortified with a complexing agent and in most cases an oxidant. It is then pumped through the underground orebody to recover the minerals in it by leaching. Once the pregnant solution is returned to the surface, the uranium is recovered in much the same way as in any other uranium plant (mill).
Most uranium mining in the USA and Kazakhstan is now by in situ leach methods, also known as in situ recovery (ISR).
In USA ISL is seen as the most cost effective and environmentally acceptable method of mining, and Australian experience supports this.
Australia's first ISL uranium mine is Beverley, which started operation late in 2000. The proposal for Honeymoon has government approval and it is expected to be operating in 2008.
Recovery from Seawater
The uranium concentration of sea water is low, approximately 3.3 mg per
of seawater (3.3 ppb). But the quantity of this resource is gigantic and some scientists believe this resource is practically limitless with respect to world-wide demand. That is to say, if even a portion of the uranium in seawater could be used the entire world's nuclear power generation fuel could be provided over a long time period. Some anti-nuclear proponents claim this statistic is exaggerated. Although research and development for recovery of this low-concentration element by inorganic adsorbents such as titanium oxide compounds, has occurred since the 1960s in the United Kingdom, France, Germany, and Japan, this research was halted due to low recovery efficiency.
This website has an excellent description of these techniques.
What Is Enriched Uranium?
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Fission is the process of splitting atoms apart. It involves using neutron "bullets" to make isotopes of uranium unstable and therefore split apart, releasing more neutrons and heat energy. A nuclear power plant can convert this released energy into electricity.
Nuclear Fission Process
Mined uranium is enriched to increase its U-235 count, the uranium isotope best suited for fission. Generally when uranium is mined, it has a high concentration of the nonfissible isotope U-238. The uranium can be enriched using many different methods varying from lasers, centrifuges, and diffusion. (Fig.1)
Fig. 1: Enriched uranium, ready to be processed into fuel pellets.
Fig. 2: These fuel rods are the fuel source for the fission reaction.
The uranium is formed into pellets and placed into fuel rod assemblies.
Many of these fuel rods are placed into the core of a nuclear power station. (Fig.2)
Fission reactions are maintained by neutron-capturing fuel rods called control rods. Using these rods, which are attached to machines above, workers can increase or decrease the amount of fusion reactions that take place in the core. When fission does occur, energy and more neutrons are released and the reaction grows exponentially. (Fig.3)
Fig. 3: This diagram shows a fission reaction at the atomic level. This reaction is the key for nuclear power.
This fission reaction released heat energy, which is used to heat the coolant water. The steam created is used to turn a turbine, which then creates electricity. (Fig.4)
Fig. 4: This is a basic diagram of a nuclear power station. Note the fuel rods located in the containment building. This is where fission takes place.
This video show how a nuclear reactor works with more focus on the mechanics of the plant.
Map of U.S. Nuclear Reactors
Fig.5: Map showing existing nuclear reactors in the U.S. Note the reactors located in SE Georgia.
Breeder reactors solve a major problem with the fuel source of nuclear power. The most common isotope of uranium found in nature is U-238. Although very common, it cannot be used in conventional nuclear reactions, and therefore must be enriched to become U-235, which makes up only 1% of naturally found uranium. Scientists discovered a way to use U-238 as a fuel source with minimal refinement of U-238. The breeder reactor is the fruit of their work.
Fig.6: A breeder reactor schematic. Note the uranium-plutonium core, and the U-238 blanket inside the core.
In order for this reaction to take place, plutonium is also needed. To begin the reaction, Pu-239 is encased by a layer of U-238. The unstable plutonium naturally fissions, releasing neutrons taht collide with the uranium layer. When this occurs, the uranium atoms change into the same plutonium isotope Pu-239, hence the name "breeder" reactor as it is creating new fuel to use. This reaction releases heat energy which in turn heats up liquid sodium, which then in a separate system heats up water. The water wil lturn to steam, which will turn the turbine and create electricity. When all of the U-238 turns into Pu-239, it is replaced with fresh fuel.
There are several hazards with the breeder reactor however. For one, Pu-239 is extremely toxic and must be handled very carefully. The remains from the reaction are also high in radiation, with half-lives of 24,00 years. These waste will have to be handeled very carefully to avoid disaster. The behavior of the reaction also eliminates water as a coolant. Liquid sodium is instead used, which when mixing with air or water will cause a violent reaction. The breeder reactor solves some problems, but it has its own flaws that need to be fixed.
Fusion is a new and promising source of nuclear energy. It is clean, the fuel for it can be made readily available, and it creates immense amounts of energy. Although it is still in the test and research phase, we already have a great understanding of how it works.
Fig.7: Diagram of a fusion reaction. Note the magnets required to contain the reaction.
The basis of the reaction relys on two fuel sources: tritium and deuterium. Deuterium is naturally found in our ocean's salt water, and tritium can be manufactured from lithium isotopes. Similar to how energy is created when the atom splits, it creates even greater energy when they combine together. In this case the two fuel sources combine to make hydrogen. The most common fusion reactor type is the Tokamak reactor, first discovered in Russia, as it is the best suited for containing the reaction. When tritium and duterium is injected into the chamber, it quickly reacts due to the intense heat caused by plasma. Plasma is an intense mix of electrons traveling at high speeds, which can create immeasurable amounts of heat. This reaction must be contained by magnets to prevent the plasma from touching the surrounding material, and said material must be highly resistant to heat. Fusion proposes to be the best solution to the worlds power crisis and hopefully will soon help lessen our dependence on coal and natural gas.
The following video explains in detail how a team based in Germany is tackling the fusion question.
Nuclear waste is a by-product of nuclear power. These hazards are stored in secure areas that can absorb radiation and keep it separate from the rest of the environment. This generally involves transporting the waste across large distances to disposal sites in specially designed containers. There are many advanced disposal systems being developed, however. They range from launching the waste into space and recycling waste for further use.
FIg.1: Spent fuel rods contained in a pool of water, which prevents radiation from escaping.
Nuclear waste is highly radioactive due to it becoming unstable as a part of the fission reaction. When the fuel rods have become spent, they are carefully removed from the reactor core and are replaced with fresh ones. The rods can be stored temporarily at the nuclear power plant in a variety of different ways: enclosed, steel-lined concrete pools filled with water, (Fig.1), or in steel or reinforced concrete containers with steel inner canisters. Both water and concrete are excellent barriers of the harmful radiation. The waste can be stored here for about 120 years.
When it is necessary to move nuclear waste to a more suitable location for permanent storage, it generally requires the waste to be moved over long distances to the disposal site. The United States has had a very safe record for transporting waste, and all routes are carefully planned and guarded in secret. The rods are placed into specially designed containers that have the ability to contain the radiation from the waste. For example, for every ton of waste there is generally 3 tons of shielding. These loads are then placed on trains or trucks, (Fig.2), and transported over predetermined routes, which generally avoid large cities. The United States has had a very safe record for transporting waste, and all shipments are generally well guarded.
Fig.2: Nuclear waste being transported to a holding area.
Nuclear waste from the United States generally meets its final resting place at Yucca Mountain, Nevada (Fig.3). It is our primary repository for nuclear solid wastes, and the wastes brought here can be stored for hundreds of years. It uses very carefully planned mined tunnels and reinforced shielding to prevent radiation from escaping the facility. It includes ceramics, dirt, and many tons of concrete (Fig.4). The spent fuel can stay here for the duration of its half life and stay separate from society.
This video details how nuclear waste is dealt with in Ontario, Canada.
Yucca Mountain, Nevada is the main U.S. disposal site of our nuclear waste. It was chosen mostly due to the mountains buildup of volcanic material, which is very effective in blocking radiation. The total cost of the project has been capped at $190 million dollars. The facility is able to take in tremendous amounts of nuclear waste that would instead be in dry storage at nuclear plants. This repository would provide a safe, separate, and secure location for all of our nuclear waste.
Fig.3: Yucca Mountain is the United States chief repository for nuclear waste.
2. SOLID AND HAZARDOUS WASTE
a. What type of hazardous waste is generated in the mining, refining, production, and use of your energy source?
Radioactive materiel is the main waste product of nuclear energy. When there is not enough uranium to continue the reaction, it is removed from the reactor and replaced. The spent fuel rods are still highly radioactive, andh can harm humans and the environment.
b. What types and amounts of solid waste is generated in the mining, refining, production, and use of your energy source?
Silt and waste rock is created from any form of mining. The refining process of uranium will require energy, which must come from an existing plant. The end product of nuclear power is of course nuclear waste and the decomissioned power plant.
c. Can any of these wastes be reused? Recycled? Reduced? Explain each example.
Spent nuclear fuel can in general not be reused except in research and weapons. Some fuel can however be reprocessed and used again in new reactors. The power plants themselves must be encased in concrete, therefore making then non-reusable.
d. WHERE and HOW are the wastes outlined in parts a and b deposited? What type of landfill is used?
The nuclear waste must be stored in specially created hazardous waste dumps. One example of these for spent nuclear fuel is Yucca Mountain, Nevada. It consists of a very large tunnel, specially made to contin radiation and other harmful effects the waste has on the environment.
3. National Policies:
a. What are some National Policies that have been enacted that positively impact your resource?
b. What are some National Policies that have been enacted that negatively impact your resource?
Pros and Cons
Low damage to environment
Medium land use
Produces 1/6th as much CO2 as coal
Minimal risk of accidents
High costs even with goverment subsidies
Low net energy yield
Serious accidents will be destructive
National Security Risks
Radiation and nuclear waste
In case of accidents, can have major environmental impact
Nuclear energy has long been under a stigmatism in America. When we think of nuclear we generally think of the mushroom clouds over Hiroshima and nuclear war. These views are severely undercutting the potentials nuclear energy has. We have the ability to create near clean energy in a safe manner. With the rising need to protect the enviorment, nuclear energy should be one of our focuses for our future power needs.
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Fromm, James. "The Breeder Reactor."
The Breeder Reactor
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"Nuclear Waste Disposal."
Nuclear Energy Institute
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Pros and Cons
Living In The Environment
. 1st ed. Belmont, CA: Brooks/ Cole, 2009. 391. Print.
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