Sunday, June 10, 2012

Safe and Cheap Energy?


                In “The Avengers,” Tony Stark’s Arc Reactor served as the energy source that kept him alive, powered the all-powerful Ironman suits, and ran the Stark Tower. More importantly, the Arc Reactor was a small, green, efficient, safe, and essentially infinite source of energy; the Arc Reactor would be the perfect, sole solution to all of human civilization’s energy problems. Unfortunately, Tony Stark is only a fictional character played by Robert Downey Jr. and the Arc Reactor does not really exist (yet!); sadly, the problem of energy still plagues society today. Instead, the closest technology to an Arc Reactor we currently have access to and wield is nuclear energy. While efficient and relatively cheap, nuclear energy is very dangerous and can be quite harmful to humans if harnessed improperly. As a result of the risky potential, several countries, such as Italy, completely avoid the use of nuclear energy and many others limit its use. In Italy, a near unanimous majority of the population are completely against the use of nuclear power because of its threat to human health and the environment, which has been simply heightened after several disasters in nuclear energy history. However, past nuclear disasters and dangerousness has only arisen as a result of misuse, failure to take precautions, and design flaws. On the contrary, if exploited and devised correctly, nuclear power would be a very useful and efficient source of energy. Even better, instead of the traditional method of nuclear energy, new and improved approaches to nuclear power are much safer and even further limitless.


                In order to fully grasp the potential yet danger of nuclear power, a comprehensive understanding of how traditional nuclear energy works must be obtained. The basis behind conventional nuclear energy follows the standard idea behind practically all power: turning a turbine. More specifically, for nuclear energy, a water coolant usually is heated up to an extremely high temperature and the resulting high pressured steam is used to drive a turbine connected to a generator, which in turn produces power; this is called a thermal power station. This heating of the water involves several different factors that must be monitored and controlled properly. As the core and most precious component of the system, the required heat is generated by the nuclear fission process of a nuclear fuel, currently primarily uranium-238. Nuclear fission is essentially the chemical reaction, or more specifically the radioactive decay, by which the nucleus of a single radioactive atom splits into smaller parts, often releasing free and energized protons and/or neutrons. This type of induced reaction is usually very much exothermic as the fragmented products are both kinetically energized and electromagnetically radioactive, resulting in the production of the desired heat. More specifically, in the case of nuclear power, the fission reaction occurring is considered to be “controlled” and often self-sustaining. After the initial fission neutron strikes the nuclear fuel, more energized neutrons are emitted and have the ability to continually maintain the reaction by acting once again as the initiating fission neutron, hence self-sustaining and releasing controlled amounts of energy to heat the water. In addition to the fission reaction, another major factor of nuclear power concerns the heated coolant, or the water, taking the produced heat energy away from the nuclear reaction and the reactor core. Since liquid water normally has a relatively low tolerance of energy before changing states, the boiling point must be raised in order to absorb an adequate amount of heat energy from the nuclear reaction before evaporating to pressurized steam for the turbine. In order to raise the boiling point of water, the current most common method is to pressurize the chamber containing the circulating water. By increasing to and maintaining an extremely high pressure, the water will have a much higher boiling point that will be able to absorb great amounts of heat before changing to steam. The resulting steam simply runs through a turbine, which turns a generator for electrical power.


                Although this process seems relatively simple, which it actually is, several concerns and problems may arise throughout the entire process, which could result in nuclear disasters. Throughout history, many of the difficulties and worries of nuclear energy have occurred in a few crises, such as the Chernobyl disaster, the Three-Mile Island accident, and the very recent Fukushima Daiichi nuclear disaster. These instances of disaster have been the result of one factor malfunctioning, then a catastrophic chain of events leading to massive destruction. Since the nuclear reactor component of the system has continually ongoing nuclear activity, any exposure or release of the internal reactor components to the surrounding environment will undoubtedly be harmful and dangerous to all living things in the area. Luckily, reactor buildings are often contained very well and built in thick layers of concrete, which would contain the radiation during normal operation; however, the containment is not indestructible. The problem comes in with the water aspect of the nuclear power system. In the case there is loss of power, such as in Japan a few years ago, the water system will steadily lose pressure and the boiling point will continually drop, causing a tremendous buildup of pressurized steam due to the continued absorbance of heat. Eventually, the containment building would not be able to withstand the pressure, leading to an explosion and the release/exposure of radioactive materials to the surroundings. Furthermore, the loss of power would cause the circulation of coolant, or water, to stop completely. The lack of coolant removing heat from the nuclear reactor would cause the nuclear fuel to heat up and exceed its melting point, hence causing a nuclear meltdown. At the point of the fuel meltdown, the designed containment would already have been penetrated, allowing the melted fuel and fission products to leak into the coolant and pollute the surrounding environment with radioactive materials. Such a nuclear disaster is very dangerous and harmful to the surroundings, but they are often avoidable and result from human error; better design, more safety precautions, and intensive testing would be able to better avoid these catastrophes.


                Moreover, instead of traditional nuclear energy, an alternative approach that is currently gaining momentum involves the use of nuclear salts, specifically thorium, instead of uranium and water. This revolutionary approach to nuclear power is much safer and more reliable than the traditional strategy of harnessing a nuclear reactor. Rather than using solid nuclear fuels like uranium, this new approach uses a better nuclear fuel, thorium, and liquid fluoride salts (lithium, beryllium, uranium, and thorium). In these new, developmental liquid fluoride thorium reactors (LFTR), the thorium-based liquid fluoride fuel works better and more efficiently than conventional uranium because of thorium’s radioactive properties; in the nuclear reaction, thorium emits more neutrons under one collision than uranium, hence with more neutrons per collision, more energy is produced, less fuel is consumed to obtain the same amount of energy output, and less radioactive byproduct is produced. Additionally, one additional ingenious and crucial property of thorium contributes significantly to the safety of nuclear power: thorium is soluble in hot liquid fluoride salts. By dissolving thorium in liquid fluoride salts, the nuclear fuel would already be in a “melted,” liquid form, thereby completely eliminating the risk of a nuclear meltdown. Additionally, in the case of power loss, a drain at the bottom of the reactor vessel can be activated simply by melting a plug. Under normal operation, this drain would be filled with a freeze plug kept cool and frozen by an externally power coolant. When there is a loss of power, the coolant would stop and the plug would melt, allowing the hot, radioactive nuclear fuel to drain down to a separate containment that would isolate and allow the fuel to cool and settle safely without exposure to the environment. Using thorium in liquid fluoride salts as the nuclear fuel is clearly an alternative approach to nuclear power that is much safer and more efficient than the traditional method; not only that, but it corrects and accounts for much of the dangers and risks of traditionally using uranium-based nuclear reactors.


                Until we engineer and develop our own Arc Reactor, nuclear energy is one of the safest and most efficient methods to harness energy and produce power for society, assuming design flaws are resolved and more stringent safety policies are taken. Moreover, liquid fluoride thorium reactors are definitely a more viable and much better strategy to harnessing nuclear energy as it addresses and corrects for the drawbacks of uranium-based nuclear reactors. As a matter of fact, many nations, such as India, China, Japan, Australia, and even the UK, are working towards fully developing and using this revolutionary idea and technology. (Maybe Italy next?)

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