Nuclear+Fission+Energy

__**Nuclear Fission Energy

Introduction to Nuclear Physics**__

Nuclear Fission arises from the nucleus of an atom splitting to create two smaller nuclei. (collision of atoms with neutrons and creates thermal energy.) This process can take place spontaneously or can be induced by a variety of particles, such as neutrons, or alpha particles. It can also be induced by electromagnetic radiation in the form of gamma rays.

**__The History Behind Nuclear Fission__**

We owe the beginning of the discovery of nuclear fission to James Chadwick, in his discovery of the neutron in 1932. in 1934, workers observed that there were molecules of the same element with different atomic numbers. It was proved in 1938 that the particles were radioisotopes of elements in the periodic table. German Physicists Lise Meitner and Otto Frisch were the first people to use the term **fissi****on** in 1939**.** They used the term to describe the larger nucleus of an atom disintegrating into two smaller nuclei of a similar size. At the same time Otto Hahn (seen on the right) and Fritz Strassmann found that when low energy electrons collided with uranium, some of the low energy neutrons had been absorbed by the nuclei of the uranium atoms. T Also in 1939, Frédéric Joliot-Curie, Hans von Halban and Lew Kowarski found that, in the fission of uranium-235, several smaller neutrons were emitted. This allows a self-sustaining chain reaction. We owe the beginning of the discovery of nuclear fission to James Chadwick, in his discovery of the neutron. Eventually nuclear fission became more and more prevalent in the scientific world and began to develop, as all technology does, it led to evil, and this evil was the development of the atomic bomb. Scientists from different countries instead of sharing information became secretive to benefit their own country in war.

__**The Science Behind it:**__   To begin to understand what nuclear fission is we should first think about marbles. Yes, marbles. Imagine 200 marbles lying on a flat surface roughly forming a circle. Then imagine if someone threw a marble at this circle. What would happen? The marbles would fly in a million different directions at a fast speed. This is what happens in nuclear fission. Nuclear Fission is the division of a heavy atomic nucleus into two fragments of roughly equal mass, accompanied by the release of a large amount of energy, the binding energy of the subatomic particle. The rough circle of marbles represents an atom's nucleus, the marble that breaks the circle apart is like a "neutron bullet" and the speed at which the marbles move away from each other is the energy released from the reaction.

Although the marble analogy helps us to explain the main idea of what nuclear fission is, we know that an atom is much more complex than a collection of tiny glass spheres. Nuclear fission involves the splitting of an atom, which occurs either spontaneously or by the stimulation of the nucleus by other particles (Neutrons, Protons, desutrons, or alpha particles) or with electromagnetic radiation in the form of gamma rays. However, not just any atom can be used.Only fissionable isotopes, certain isotopes of certain elements which can be split through fission, can be used to create power through fission. Also a specific type of "bullet" must be used to trigger the fission reaction. The most likely "bullet" would be the neutron, because its lack of charge would allow it not to be repelled by the positive charges of the protons or the negative charges of the electrons. When the atom is split a large quantity of energy is released, radioactive products are formed and several neutrons are emitted. These released neutrons can induce fission in a nearby nucleus of fissionable material ( any species of atomic nucleus that can undergo the fission reaction ) and create a chain reaction in which an extremely large quantity of energy is released.

Nuclear fission also has a lot to do with structure and stability of an atom. The nucleus of an atom consists of protons and neutrons which are equal to the mass number of the atom, but not to the actual mass of the nucleus. That difference between these two masses, known as the mass defect, is the mass equivalent of the energy of the formation of the nucleus from its constituents. The conversion between this energy and the mass of a nucleus follows Einstein's equation, E=mc², where E equals equivalent of mass, m and c is the velocity of light. The mass defect is a measure of the total binding energy of the nucleus, which is released during the formation of a nucleus from the nucleons that make it and is necessary to decompose an atom into its individual nucleon components.

On the Binding curve which illustrates the binding energy per nucleon as a function of nuclear mass the largest binding energy occurs near the atomic mass 56 (iron). This means that a mass number higher than 56 would become more stable if broken apart into lighter parts with higher binding energy and the difference in binding energy would be released in the process. For example, when an atom of Uranium-235 fissions the sum of the masses of its fragments are less than the mass of its nucleus before the fission reaction took place. Since the mass of the fragments are equal to or greater than iron ( at the peak of the binding curve) the nuclear particles in these fragments will be more tightly bound than they were in the uranium nucleus. The decrease in mass is released in the form of energy.

Uranium-235 is the element that most people think of when nuclear fission is mentioned. Natural Uranium is composed of 0.72% U-235 (the fissionable isotope), 99.27% U-238, and a trace quantity 0.0055% U-234 .It is also the heaviest and largest of all naturally occurring elements( it is 18.7 times more dense than water) and therefore, would yield the highest amount of energy when split. However, to create a self-sustaining critical chain reaction in U.S. style light-water reactors, 0.72% U-235 is not sufficient, although it is used in Canadian CANDU reactors. For light-water reactors, the fuel must be enriched to 2.5-3.5% U-235.

The facility behind the production of Nuclear energy into electric energy is a Nuclear Power Plant, within the power plant there are nuclear reactors. A nuclear reactor is a device that facilitates the release of energy through controlled nuclear fission reactions. In a nuclear reactor the uranium fuel is assembled so that a controlled fission chain reaction can occur. The heat created from this reaction (splitting the U-235 atoms) is then used to make steam which spins a turbine to drive a generator, producing electricity. A nuclear reactor is able to produce about 23 million kilowatt-hours of heat energy per kilogram (51 million kw-hours per lb) of U-235 fission.The process by which the energy is produced is similar to that of nuclear bombs. the main difference is that because the reactions occur in a controlled setting, the explosive properties of the reactions are controlled into a steady, non explosive flow of heat energy.

The chain reaction that takes place in the core of a nuclear reactor is controlled by rods which absorb neutrons ( changing the rate if the reaction) and which can be inserted or withdrawn to set the reactor at the required power level. To allow a steady chain of energy to be created a substance called a moderator is used to slow the speed of the emitted neutrons and allow the chain reaction to continue. Different types of moderators are used in different types of reactors. Some examples of these moderators are Water, graphite and heavy water.

The video below simplifies the actions of nuclear fission. The splitting makes energy.

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The advantages to Nuclear Fission is that they can be produced without using fossil fuels when they become scarce. It also utilizes less fuels than that of extracting fossil fuels. As well if Nuclear Power Plants are well operated they do not immediately produce pollutants in the air like fossil fuels do. As well, Nuclear Power plants are generally efficient and can produce a lot of energy, much more than that of other energy sources. Not to mention that the fuel is inexpensive and easy to transport.====== The Manhattan Project is a detrimental effect of the technology of Nuclear Fission. The Manhattan Project was the secret name for the project in the development of nuclear bomb by nuclear fission. It was a race between different nations (including Russia) to create the most powerful nuclear bomb. The effects a bomb of that size could be very detrimental to human society. Fortunately, the effects of the Manhattan project was stopped due to the efforts of the Pugwash Peace Movement which included many scientists including Albert Einstein (one of his last wishes) and earned Canada one of their two Nobel Peace Prizes. (Pugwash Lecture, July 2009) Other effects of Nuclear Fission are the rising costs of constructing power plants, security, health and environmental effects. (Tesar, J. 2010). Nuclear Energy. Health concerns arisen from Nuclear Fission include radiation effects and the increase probability of cancer. This is because radiation disrupts cell's chemical processes, which increase the probability of developing cancer. Moreover when genetic material in reproductive cells get damaged (by radiation) mutations may cause abnormalities like Down syndrome. (Tesar J). Nuclear waste storage is also becoming a problem as they remain radioactive for a long period of time afterword. Following that, at plants there have been Nuclear accidents which pose a serious threat on human society. (Tesar J).
 * __Disadvantages__**

Overall Nuclear fission is a process that though poses serious harm on society (and even more if used for wrong), it is an up and coming technology that handles the problem of the scarce amounts of fossil fuels left due to its efficiency. The health concerns are only the small issues that arise from nuclear fission. Storing that magnitude of radioactive waste will eventually haunt us in the future and since it is hidden (when placed underground), humans will soon forget about it until it poses a serious harm on human health, which by then would be too late to stop. Naturally there is always the 'not in my backyard' issue that arises with the storage of radioactive waste. Being a selfish species, there is much debate as to where the waste should go. However the real dangers are not just those simple dangers, but rather the danger that it could end humanity as we know it. Yes, nuclear fission does not pollute the Earth's water and air, but it does pollute one thing. The only pollutant nuclear fission feeds is the evil thoughts of the human mind.
 * __Analysis__ **

Basic Nuclear Fission. Web. 12 May 2010.< [] > Binding Curve Photo: [] Nave, R. "Nuclear Fission." Web. 13 May 2010.< []> Otto Hahn Photo: [] "New Book of Popular Science". Web. 11 May 2010  "Nuclear Energy." //Encyclopedia.// //Today’s Science//. Facts On File News Services, Web. 11 May 2010. . "Nuclear Energy". Web. 12 May 2010.< []> "Nuclear Fission". Encylopedia Britannica.Web. 6 May 2010. ([]) Nuclear Fission photo: [] Nuclear Reactor photo: [] Tesar, J "Nuclear Energy." //Encyclopedia Americana//. 2010. Grolier Online. 11 May. 2010 []. Various. (2009, July 8). Pugwash Movement. //Canadian Social Movements//. Lecture conducted from Shad Valley, Halifax. "Why Nuclear Power - Comparisons of Various Energy Sources". 12 Apr. 2009. Web. 20 May 2010. <[].> World Nuclear Association. Uranium for Nuclear Power. Web. 20 May 2010. <[]>
 * __Bibliography__**

Written by: Salena Barry, Christine Lam and Cecile Ritchie