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Nuclear energy is widely known for its very high efficiency and its ability to create a large amount of energy from relatively fewer fuel compared to other methods such as fossil fuels. However, it has some major environmental risks. Nuclear plants produce radioactive gases and if these gases are released in to the environment it can cause major health hazards. The recent disaster at Fukushima-Daiichi has captured the attention of the world about nuclear power safety. A highly developed nation like Japan who is so well prepared for disasters that end up in such a situation has questioned the ability of preventing disasters in nuclear facilities. World has now started thinking about the serious nature of radiation from nuclear power plants and how can it affect the future generation. In this paper we will be discussing about the impacts and future use of Nuclear energy.
What is Nuclear Power?
Nuclear energy is best applied to medium and large-scale electricity generation. Nuclear technology was introduced in 1939 when nuclear fission was discovered. The fuel used for nuclear power generation is uranium. Nuclear energy can be released from atoms in two different ways: nuclear fusion and nuclear fission. In Nuclear fusion, very high energy is released when the atoms are combined together to form a larger atom and in nuclear fission, very high energy will be released when atoms are split in to smaller parts of atoms. Released energy then can be harvested as steam power to drive turbines and generate energy in power plants. Nuclear power plants are considered as clean and efficient energy source. However, it has some major environmental risks. Nuclear plants produce radioactive gases and if these gases are released in to the environment it can cause major health hazards.
Leaders in Nuclear power
In June 1954, world's first nuclear power plant to generate electricity was opened in Obninsk, Moscow(Long, 2012).Global nuclear capacity has shown a high growth from 1960 to 1980s .In 1986, the share of nuclear power reached 16% in global electricity generation(McDonald, 2006). When looking at the world at a glance, nuclear power generation has spread throughout the world. As of July 2012, there are 435 nuclear power plants in 31 countries worldwide. They provide approximately 13.5% of the world's electricity requirements as continuous, reliable base-load power, and their efficiency is increasing (Nuclear Power in the World Today, 2012). USA has the most with 104 and is the largest producer of nuclear power, generating 31% of the total global nuclear generation. France is next with 59 followed by Japan with 55 and Russia with 31(McDonald, 2006).
Figure 1: Number of reactors in operation, worldwide, 2012-07-02 (Nuclear power plants, world-wide, 2012)
Fukushima Daiichi Incident
In March 11, 2011, an earthquake with magnitude of 9.0 Richter scale and tsunami hit the northeast coast of Japan. That in turn made the Fukushima Daiichi power plant famous as the site of one of the worst nuclear accidents that the world has ever known. Although the accident was triggered by an earthquake and tsunami, it cannot be categorized as a natural disaster. It was clearly a manmade disaster which could have been predicted and prevented. At the time of the accident eleven reactors at four nuclear power plants in Fukushima Daiichi plant were operating and all of them were automatically shut down when the earthquake hit the area. Tokyo Electric Power Company's Fukushima Daiichi 1, 2, 3, and Fukushima Daini 1, 2, 3, 4, Tohoku's Onagawa 1, 2, 3, and Japco's Tokai operation units were shut down during the accident. Unit 4, 5 and 6 at Fukushima Daiichi were not operating at the time but later identified as affected. After the accident main focus was centered on Fukushima Daiichi units 1, 2, 3 and 4(Fukushima Accident 2011, 2011).Fukushima Daiichi plants used Boiling Water Reactors (BWR). It generates electricity by boiling water using nuclear fuel, and steam that produced was used to drive turbines. The reactor operates at about 285 °C. Heat generation was accomplished by nuclear fission mechanism. One disadvantage of using BWR in nuclear reactors is that even if the nuclear reaction is stopped the extremely strong radiation generated in the nuclear fuel get heated and the generation of heat cannot be stopped immediately. It lasts for a long period and this is named as "decay heat". "Decay heat" was found to be the major cause for the Fukushima Nuclear accident (Tateno, 2011). Cooling system in the power plant was nonfunctional because of the power outage. As a result, temperature of the reactors continued to rise, the cladding tubes became oxidized, shattered, and melted. This resulted a massive leak of radioactive gases, including iodine-131, cesium-134 and cesium-137(Maugh, 2012). Figure 2: Satellite images of Fukushima Daiichi Nuclear plant, Japan, shows damage after the March 11 earthquake and tsunami (Methods for Estimating Radiation Release from Fukushima Daiichi, 2012)
After the incident, due to the large quantities of radioactivity release into the environment, more than three hundred thousand residents were removed from the surrounding areas of the Fukushima Daiichi plant. About 600 of them died from exhaustion and depression.
Figure 2: Possible spread of contaminated clouds from Pacific Ocean towards Hawaii and US west coast (Hookway & Sainsbury, 2011)
Later investigations predicted that contaminated clouds can travel through winds from the Fukushima Daiichi nuclear plant out into the Pacific Ocean towards Hawaii and the US west coast. Radiation release was spread through several hundreds of kilometers around the Fukushima Daiichi plant, and later analysis found that low levels of radioactive materials were present even in North America and Europe.
Global Health Impacts of the Fukushima Nuclear Disaster
This accident was considered as the worst atomic disaster since the 1986 Chernobyl disaster. Most of the radioactive was dumped to the Pacific Ocean and only 19% of the released materials were deposited over land, which made the exposed population relatively small (which minimized the exposure of the population) (Global Health Impacts of the Fukushima Nuclear Disaster, 2012).
According to a research carried out at the Stanford University by Mark Z. Jacobson and John E. Ten Hoeve, the radiation probably will cause between 15 and 1,300 cancer deaths, with the most likely number being 130. It also will cause between 24 and 2,500 cancer cases, with the most likely number being about 180(Maugh, 2012).
Future Concerns of Nuclear energy
Fukushima Daiichi Nuclear accident has made world aware about nuclear disasters. Research shows that if an identical nuclear accident happened at the Diablo Canyon Power Plant, near San Luis Obispo, California the projected health effects percentage is 25% larger than the Fukushima Daiichi Nuclear accident (Global Health Impacts of the Fukushima Nuclear Disaster, 2012). Therefore, studying and preventing such nuclear accidents in future is crucial for the future sustainability of nuclear power.
Future of Nuclear power plants depends on "Safety", "Economical factors" and "Environmental factors".
After Japan's Fukushima accident, many countries have started to reject nuclear energy because of its risks that are too high for a modern society to tolerate. For an example, Germany has already implemented plans to shut down all its nuclear power plant reactors by 2022(Tucker, 2012).
Meanwhile, some other countries have already taken action to study the Fukushima incident closely to identify possible preventing methods. Countries like U.S., China, U.K., France, and South Korea have restated their commitment to the safe and secure development of nuclear energy (Buongiorno, 2012).
After the Fukushima incident, International Atomic Energy Agency (IAEA) has implemented a new Nuclear Safety Action Plan which sets out a proposal for national and international action in 12 major areas (One Year After Fukushima, Nuclear Safety Is Stronger, 2012). Some of the proposed action items are as follows:
IAEA implemented a new approach for evaluating the safety vulnerabilities of nuclear power plants.
The IAEA's Safety Standards, which provide the basis for a high level of safety, have been systematically reviewed and proposals have been made to reinforce them, with particular emphasis on a strong regulatory framework and safe siting, design and operation of plants.
The IAEA has stepped up its peer review services, incorporating lessons of Fukushima to help Member States to assess and reinforce nuclear safety, and has taken steps to improve coordination with operators.
Expanded IAEA's communication role in response to nuclear emergencies, including provision of analysis and possible predictions.
On March 2012, United States Nuclear Regulatory Commission (NRC) has issued the first regulatory requirements for the 104 operating reactors in USA based on the lessons learned at Fukushima Daiichi. NRC ensures that appropriate safety enhancements are implemented at nuclear plants in USA. For example, NRC has approved the AP1000 project that has being built in Georgia which specifically designed with a "passive" cooling system that relies on natural convection currents rather than electric pumps so the reactors can cool themselves for several days while waiting for power to be restored (Tucker, 2012).
From the lessons learned from Fukushima Nuclear accident, all of the above standards are designed to ensure that all nuclear power plants are designed to tolerate severe environmental events such as earthquakes, hurricanes and tsunamis.
Cost of operation and maintenance, demand for electric power, speed and capital investment of new plant construction, and the cost of alternate power sources are considered as the main "Economical factors" which defines the future of nuclear power.
Nuclear power plants have high initial capital cost. Additional capital investments are included when upgrading these plants to improve safety according to the above standards. These "additional capital investments" are included in the power production costs. Therefore, nuclear power cost is predicted to increase with the new standard implementations (Natelson, 2011).
World electricity demand is estimated to grow at an annual rate of 2.4% between 2000 and 2030.Table 1 shows that demand for Nuclear energy will be the same between 2000 and 2030 and the annual growth rate is predicted 0.1%.However, renewable energy sources shows the highest growth rate of 5.6% annually. Number of renewable energy technologies have been introduced recently and improved to provide electricity at a lower cost.
Table 1:Electricity Balance, Worldwide 2000- 2030 (Birol, 2011)
Nuclear waste disposal is considered as one of the main "Environmental factors" which will influence the future of nuclear energy as it has unresolved challenges in long-term management of radioactive wastes. The United States and other countries have yet to implement final disposition of spent fuel or high level radioactive waste streams created at various stages of the nuclear fuel cycle. Since these radioactive wastes present some danger to present and future generations, technology advancements on reprocessing spent fuel, extracting usable materials and reducing the amount of highly radioactive waste that should be placed in a geologically isolated repository should be promoted for the sustainability of nuclear power.
The nuclear accident at the Fukushima Daiichi site has raised questions about the future sustainability of nuclear energy as a source of electrical power. As recovery proceeds and lessons are learned, the safety of nuclear power will be verified in the future. World total nuclear generating capacity has remained approximately steady for the past 20 years. Many of these plants are approaching the end of their operating lifespan and it will be difficult to get lifespan extensions after the Fukushima disaster. Meanwhile, renewable sources like hydropower, wind, solar, and biofuels has shown a tremendous growth over the same period.