The Fukushima Nuclear Tragedy. by Clifford Hampton

Transcription

1 The Fukushima Nuclear Tragedy by Clifford Hampton

2 Table of contents I. History of the Fukushima Nuclear Tragedy II. Basic technical aspects of the nuclear reactor and its history III. Safety culture of nuclear reactors in Japan IV. Ethical aspects of this tragedy with respect to its prevention, decision making by the company that owns this reactor and finally using human beings as guinea pigs to clean up the mess V. Social aspects of this tragedy with respect to nuclear power plants all around the world VI Safety and viability of nuclear power plants throughout the world, and finally VII Implications and preventable steps that we learn from this tragedy VII. Conclusion

3 I. History of the Fukushima Nuclear Tragedy The Fukushima Daiichi nuclear disaster was a series of equipment failures, nuclear meltdowns, and releases of radioactive materials at the Fukushima I Nuclear Power Plant, following the Tohoku earthquake and tsunami on 11 March The plant comprises six separate boiling water reactors originally designed by General Electric, and maintained by the Tokyo Electric Power Company. The remaining reactors shut down automatically after the earthquake, and emergency generators came online to control electronics and coolant systems. The tsunami resulted in flooding of the rooms containing the emergency generators. Consequently those generators ceased working, causing eventual power loss to the pumps that circulate coolant water in the reactor. The pumps then stopped working, causing the reactors to overheat due to the high decay heat that normally continues for a short time, even after a nuclear reactor shut down. The flooding and earthquake damage hindered external assistance. As workers struggled to cool and shut down the reactors, several hydrogen-air chemical explosions occurred. The hydrogen gas was produced by high heat in the reactors causing a hydrogen-producing reaction between the nuclear fuel metal cladding and the water surrounding them. As the water levels in the fuel rods pools dropped, they began to overheat. Fears of radioactivity releases led to a 20 km (12 mi)-radius evacuation around the plant. During the early days of the accident workers were

4 temporarily evacuated at various times for radiation safety reasons. Electrical power was slowly restored for some of the reactors, allowing for automated cooling. Japanese officials initially assessed the accident as Level 4 on the International Nuclear Event Scale despite the views of other international agencies that it should be higher. The Japanese government and TEPCO have been criticized in the foreign press for poor communication with the public and improvised cleanup efforts. The Japanese government estimates the total amount of radioactivity released into the atmosphere was approximately one-tenth as much as was released during the Chernobyl disaster. Measurements taken by the Japanese government km from the plant showed caesium-137 levels high enough to cause concern, leading the government to ban the sale of food grown in the area. There were no immediate deaths due to direct radiation exposures, but at least six workers have exceeded lifetime legal limits for radiation and more than 300 have received significant radiation doses. On July 5, 2012, the parliament appointed The Fukushima Nuclear Accident Independent Investigation Commission submitted its inquiry report to the Japanese parliament, while the government appointed Investigation Committee on the Accident at the Fukushima Nuclear Power Stations of Tokyo Electric Power Company submitted its final report to the Japanese government on July 23, ( ) II. Basic technical aspects of the nuclear reactor and its history A nuclear reactor is a large scale piece of high technology equipment that is designed to be able to generate a series of chain reactions of radioactive fissionable elements such as uranium. There are a number of things that these reactors may be used for, such as the generation of electrical power, scientific research, and producing nuclear fuel. There are many different designed for these types of reactors, and they can be found throughout the world. The process that happens inside the reactor is known as fission, which is when a heavy element absorbs a neutron and then breaks apart into two lighter elements. When this happens, the element also releases a certain amount of energy.

5 Under controlled fission, they are able to harness this energy in order to use it for many other means, and they are also able to create a chain reaction where they can get the other fissionable elements to continue to release energy. A nuclear power plant produces electricity in much the same way as other electric power plants: Water is heated to produce steam, and the steam turns turbines that turn a generator shaft to make magnetism, which is what electricity is. The difference in a nuclear power plant is how the water is heated. Most power plants today use coal or natural gas to heat the water to become steam. Nuclear power comes from a reactor where atoms are split to release their energy, which produces great amounts of heat. The design of a nuclear reactor is complex, but basically, each reactor has six main elements: (1)Fuel. Fuel is needed in all energy-producing processes, and fuel is at the heart of the reactor. (2) Control rods. The control rods are lowered or raised next to the fuel assembly to speed up or slow down the rate of the chain reaction by absorbing some of the neutrons released in fission. To speed up the chain reaction, the rods are pulled up away from the fuel assembly. To slow the reaction down, the rods are lowered next to the fuel assembly. (3)Coolant The cooling process in a nuclear reactor is similar to the way a car radiator works to cool the engine. Because the fuel assembly gets very hot during a chain reaction, a coolant, usually water, is pumped through the reactor to carry the heat away. As with most power plants, two-thirds of the energy produced by a nuclear power plant goes into waste heat, and that heat is carried away from the plant in the coolant water. (4) Moderator When a neutron causes fission, fast neutrons are released. These fast neutrons need to be slowed down to lower energy levels. Moderators are made of various materials. Water is used because the water can also serve as a coolant. Normal water, known as light water, is used in most reactors simply because it is cheap and abundant. Another commonly used moderator material is heavy water, which is chemically equivalent to normal water, but contains Hydrogen-2. (5)Shield Nuclear fission results in the release of neutrons and several other by-products such as alpha rays, beta rays, gamma rays, and fast moving neutrons. Radiation shielding is required to prevent this harmful radiation from leaving the reactor and affecting people and materials outside the reactor. (6) Reflector Fast moving neutrons are controlled with a moderator and reflectors

6 to keep them inside the reactor core so that a sustained and controlled chain reaction takes place. ( ) III. Safety culture of nuclear reactors in Japan / Safety and viability of nuclear power plants throughout the world Prime concern for those working in the nuclear plants are taken. People wear device the monitor how much radiation they have come in contact with. This device is for that person only. Other means of protection are physical shielding and limiting time spent around the radiation. One mandated safety indicator is the calculated probable frequency of degraded core or core melt accidents. IV. Ethical aspects of this tragedy with respect to its prevention, decision making by the company that owns this reactor and finally using human beings as guinea pigs to clean up the mess During an investigation by the Fukushima Nuclear Accident Independent Investigation Commission (NAIIC), they identified a long list of technical failures that contributed to the disaster, laying the blame on the energy utilities, regulators and the government. They concluded that the accident was clearly manmade. The Atlantic wires states that " The plant had problems galore and the approach taken with them was piecemeal. Most of the critical work: construction work, inspection work, and welding were entrusted to sub-contracted employees with little technical background or knowledge of nuclear radiation. I can t remember there ever being a disaster drill. The TEPCO employees never got their hands dirty. " ( VII.Implications and preventable steps that we learn from this tragedy

7 Issues leading up to the Fukushima Nuclear Tragedy could have been prevented by protecting emergency power supplies, including the diesel generators and batteries by moving them to higher ground or by placing them in watertight bunkers. Watertight connections between emergency power supplies and key safety systems could have been established. Enhancing the protection of seawater pumps (which are used to transfer heat from the plant to the ocean and to cool diesel generators) and/or constructing a backup means to dissipate heat. The plans that the industry of Japan is trying to incorporate is the reduction and eventually eliminating its dependence on nuclear energy. In August 2011, the Japanese Government passed a bill to subsidize electricity from renewable energy sources. ( I believe this will help decrease the problems related to using nuclear energy. The elimination of radiation such as what was released during this tragedy will cease to exist. Renewable energy is derived from natural processes that are replenished constantly. In its various forms, it derives directly from the sun, or from heat generated deep within the earth. Included in the definition is electricity and heat generated from solar, wind, ocean, hydropower, biomass, geothermal resources, and biofuels and hydrogen derived from renewable resources. ( This type of energy is more effective and safe for our atmosphere and for the health of people. It would be more cost effective as the use of renewable energy becomes more efficient, cutting the costs for people to use electricity. From the end of 2004, worldwide renewable energy capacity grew at rates of 10 60% annually for many technologies. I believe the production of more renewable energy will be beneficial and eventually the use of nuclear energy will be lessened. The table below shows the increases of various renewable energies, with grid-connected PV having the fastest growth. Selected global indicators

8 Selected global indicators Wind power capacity (existing) (GWe) Solar PV capacity (grid-connected) (GWe) Solar hot water capacity (existing) (GWth) Renewables power capacity (existing) (GWe) 1,140 1,230 1,320 1,360 Investment in new renewable capacity (annual) (10 9 USD) Hydropower capacity (existing) (GWe) Ethanol production (annual) (10 9 litres) Countries with policy targets for renewable energy use Biodiesel production (annual) (10 9 litres) VII. Conclusion They have been three incidents like this in the last two decades. The Fukushima accident is the worst in history. There has been reports stating that this could have been prevented. Although people in Japan take pride in themselves and the people that are in charge they should have pointed out what needs to be fixed. By stopping the short cut method like many people do we could have a better world to live in. Today the Fukushima nuclear plant is not operational due to the fact no one need the electric. There is no one living in the area. As we try to look into the future to find way to prevent disaster like this from happening, there is no way we can predict what effect we might have on earth. One thing

9 for sure is that we don't have to take short cut when it comes to the lives of so many people. If you look at the way thing are being down today, we look for the cheapest bidder. With this we get that kind of work. What we should get is the same work as professional get. The price doesn't have to go up.

10 References Acton, J. M., & Hibbs, M. (2012, March). Why Fukushima Was Preventable. Retrieved October 11, 2012, from Why Fukushima Was Preventable website: why-fukushima-was-preventable# Renewable energy commercialization. (2012, October 8). Retrieved October 10, 2012, from Renewable Energy website: Wikipedia. (2012, September 25). Retrieved October 10, 2012, from Japanese reaction to Fukushima Daiichi nuclear disaster website: Japanese_reaction_to_Fukushima_Daiichi_nuclear_disaster Reactors & Power Plants. (n.d.). Retrieved October 11, 2012, from US Department of Energy website: Safety of Nuclear Power Reactors. (2012, October). Retrieved October 11, 2012, from Fukushima Disaster Blame Belongs with Top Leaders at Utilities, Government and Regulators. (n.d.).retrieved October 11, 2012, from article.cfm?id=fukushima-blame-utilities-goverment-leaders-regulators Fukushima Accident (2012, September 17). Retrieved October 11, 2012, from Fukushima Daiichi nuclear disaster. (2012, October 11). Retrieved October 11, 2012, from

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