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| Fig. 1: Pressurized Water Reactor. (Source: Wikimedia Commons). |
In 1903 at McGill University, Rutherford and his colleague Frederick Soddy introduced their disintegration theory of radioactivity, which claimed radioactive energy was emitted from within an atom. [1] Thirty-eight years later, on the morning of December 2, 1942, physicist Enrico Fermi and a group of other scientists constructed the worlds first nuclear reactor. After this breakthrough, it was almost a decade until the first electricity was produced from nuclear energy on December 20, 1951. In the early years after the discovery of nuclear fission, most the applications of nuclear energy were aimed towards building effective weaponry for combat. After World War II, the Atomic Energy Commission(AEC) was created in 1946 to look into the peaceful use of nuclear energy. The commission later authorized the construction of Experimental Breeder Reactor I in Arco, Idaho. This reactor produced the first electricity from nuclear energy, lighting four light bulbs.
Today, nuclear energy is considered to be a sustainable alternative energy source to fossil fuels due to its clean nature. This is manifested in the global electricity production with nuclear power from various reactor designsapproximately 13.5%. [2] However, there has been a long-standing debate about how clean this source of energy actually is. Proponents of nuclear energy mention the zero emission from the nuclear fission reaction. Also, even though some stages of the nuclear power cycle, like uranium mining and milling, fuel reprocessing, nuclear waste disposal, etc., generate greenhouse gases, the overall life-cycle emissions for nuclear power are likely to be lower than for fossil fuels. On the other hand, opponents allude to the health risks of the radioactive waste produced from nuclear reactors and the conundrum surrounding its storage. Nuclear waste can be classified into several categories depending on radioactive content. Experts claim that the majority of waste produced by nuclear power production can be classified as Lower Level Waste (LLW). [3] This means that the waste contains small amounts of mostly short-lived radioactivity and does not require shielding during handling and transport. This doesnt settle the debate because electricity production from nuclear energy still produces High Level Wastes (HLW), which have high contents of radioactivity and pose high danger to the public if not handled or stored properly.
The process of using nuclear energy to produce electricity has similar principles to coal or natural gas power plants. The only difference is the source of energy that is used to generate the steam to power the turbines. A Pressurized Water Reactor (Fig. 1) consists of three circuits: two circuits (primary and secondary) which are both closed and one circuit which is opened to the surrounding. The energy production process begins with the fission of Uranium atoms inside the reactor core. This reaction takes place in the fuel tubes which are packed with enriched uranium pellets. The heat from the chemical reaction is transferred through the tube walls to the primary circuit water by contact. The chain reaction is controlled by control rods which are lowered into or withdrawn from the core to decrease or increase the heat generated by the reaction. The closed pressurized primary water circuit uses the heat received from the reactor core to heat up water. This water is then transferred to the secondary water circuit. The secondary water circuit uses the heated water from the primary circuit to generate steam by boiling water above its boiling point. This steam is then used to power a turbine, which in turn powers a generator to produce electricity. The steam is later cooled off by an open cooling water circuit. The source of this water is usually large water bodies.
Whichever way you choose to look at it the prospect of generating energy from atoms has proven to be an intriguing prospect. As with most technological innovations, we must be able to address the "curses" that come with these "blessings." As of May 2016, the majority of the countrys 99 nuclear reactors were more than 30 years old and were opened before deregulation. [4] If we are to harness the maximum potential of nuclear energy while securing our planet, we need to put more effort into research and development in order to improve plant efficiencies and enhance the safe effective disposal of nuclear waste.
© Kofi Owusu Agyeman. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] M. Kumar, "The Man Who Went Nuclear: How Ernest Rutherford Ushered in the Atomic Age," Independent, 3 Mar 11.
[2] I. Pioro and R. Duffey, "Nuclear Power as a Basis for Future Electricity Generation," ASME J. Nucl Rad. Sci. 1, 011011 (2015).
[3] D. G. Brookins, Geochemical Aspects of Radioactive Waste Disposal (Springer, 1984), p. 157.
[4] D. Cardwell, "Nuclear Plants, Despite Safety Concerns, Gain Support as Clean Energy Sources," New York Times, 31 May 16.
