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Nuclear Fission and Fusion
Transcript of Nuclear Fission and Fusion
Nuclear Fission and Fusion
Fission vs. Fusion
What is it?
Nuclear fission is the process of splitting atoms.
It's a process in which the nucleus of a heavy atom is broken apart into two or more smaller nuclei.
Imagine a group of marbles. Then imagine throwing one marble at the group and watching all the marbles fly out in all different directions, away from each other.
Nuclear power plants depend on the heat that occurs during nuclear fission to make steam to make electricity
For scientific research (provide a source of neutron beams)
Radioactive tracers (like magnesium-28) in geology, agriculture & medicine
Iodine-131 treats Grave's Disease
Proposed as a way to nudge the path of large asteroids and comets that would otherwise impact and kill all humans on Earth
It makes a lot of energy to use for anything we want, but the radioactive waste can't be disposed off in an environment-friendly manner
Spacecraft propulsion -- Project Orion
Proposed as a way to rapidly excavate large amounts of rock and dirt -- Operation Plowshare
Could potentially displace energy produced by coal, oil, and natural gas electric power plants, reducing the amount of CO2 and other pollutants into the air
Fission History (Brief)
The fission reaction was discovered accidentally in 1938 by two German physicists, Otto Hahn and Fritz Strassmann. (They were doing a series of experiments in where they used neutrons to bombard various elements.) Hitler had this information.
German physicist Lise Meitner (1878–1968) and her nephew Otto Frisch explained why an atom of uranium (element number 92), when struck by a neutron, broke into two much smaller elements such as krypton (element number 36) and barium.
A year into World War II (1939–45), a number of scientists had come to the conclusion that the United States would have to try building a fission bomb.
Pros and Cons
Lower carbon dioxide (and other greenhouse gases) released into the atmosphere in power generation.
Low operating costs (relatively).
Known, developed technology “ready” for market.Large power-generating capacity able to meet industrial and city needs.
Existing and future nuclear waste can be reduced through waste recycling and reprocessing.
High construction costs due to complex radiation containment systems and procedures.
High-known risks in an accident.
Long construction time.
Target for terrorism (as are all centralized power generation sources).
Waste lasts 200 – 500 thousand years.
Risk of Meltdowns. If there is a loss of coolant water in a fission reactor, the rods would overheat.
Nuclear power plants produce about 20 percent of America's power.
There are over 400 nuclear power plants worldwide.
While nuclear energy produces less waste than fossil fuels, its radioactive waste must be stored in special containers and buried beneath the earth's surface, typically in a mountain, until it is no longer hazardous.
Almost 3 million Americans live within 10 miles of an operating nuclear power plant.
Nuclear energy comes from uranium, a nonrenewable resource that must be mined.
In 2009, America produced 798.7 billion kilowatts of nuclear energy, more than twice that of any other country and over 30% of all the nuclear energy generated worldwide that year.
Every 18 to 24 months, a power plant must shut down to remove its spent uranium fuel, which has become radioactive waste.
United States power plants produce 2,000 metric tons of radioactive waste every year.
In 2008, nuclear power replaced an estimated 690 million metric tons of carbon dioxide from entering the atmosphere.
Nuclear power plants generate nearly three-fourths of America's clean-air energy.
combining of atoms
produces clean energy
products are light, stable
occurs in stars
high density, high temperatures required
energy released is 3x greater
Splitting of atoms
releases large amounts of heat/radiation
products are heavy and radio-active
doesn't naturally occur
critical mass and high-speed neutrons required
energy released is lower
both nuclei receive action
What is it?
Nuclear fusion is the fusing of two or more lighter atoms into a larger one.
It's a process where atomic nuclei of low atomic number fuse to form a heavier nucleus with the release of energy.
Fusion occurs in stars, such as the sun.
Physicist F.W. Aston discovered in highly accurate experiments that four hydrogen atoms are heavier than one helium atom
By the mid-1950s "fusion machines" were operating in the Soviet Union, the United Kingdom, the United States, France, Germany and Japan
The design of JET, the largest fusion experiment in the world, started in 1973. Construction commenced in 1979 and the experiment was put into operation in 1983
JET still holds the world record for the generation of fusion energy: in 1997, 16 megawatts were generated during 1 second.
Fusion is the energy source for the sun.
For scientific research
The main application for fusion is in making electricity
Nuclear fusion will be used as a power source. It is what the sun does to generate energy, and as a species, we are now trying to use a sun-like plasma in a controlled environment.
Pros and Cons
Inside a power plant
ITER - The Future of Nuclear Fusion
There is a lot more energy release in fusion, so it will be more profitable.
Very low cost since the fuel source is hydrogen.
Clean energy - no pollution or greenhouse gases
No chain reaction. Easier to control or stop than fission.
Little or no nuclear waste.
Virtually limitless fuel available.
Fusion will only occur at temperature of 10-15 million kelvin (K), which is currently achieved using nuclear fission.
Cold fusion is fusion at a low enough temperature to make the output energy greater than the input energy, but it is still under development.
Once ignition is achieved and the ring plasma is sustainable, it must be held away from the walls of the tokamak using magnetism.
Our sun's magnetic fields are what makes it sustainable as well. (Our design mimics our sun's, with the exception of the ring-shape.)
Nuclear fusion can also be used as a weapon. Such fusion weapons are generally referred to as thermonuclear weapons or hydrogen bombs
Nuclear Fusion Used as a Weapon - Oct. 1961
The Tsar Bomb was the biggest bomb ever, and it isn't ours. It was Russian, comrade. It was a weapon of mass destruction.
Albert Einstein warned F.D. Roosevelt that his equation (e = mc2) was being used in this way and that the atom bomb was imminent - both in Nazi Germany and in the U.S.
Your skin protects you from most background radiation (from smoke detectors, the sun & other stars, computers, TVs, etc.), but in the event of a nuclear fallout, Potassium Iodide can help!