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| Fig. 1: Radioactive Waste Leaking from Damaged Drum (Source: Wikimedia Commons) |
All current energy sources have their benefits and drawbacks across many facets including access, transportation, storage, and pollution. Nuclear energy is no different, but in regards to pollution the conversation is a bit more difficult. By first examining other energy sources pollutant by-products and the extent to which certain sources of energy are used, one can analyze the strengths and weaknesses of nuclear energy with respect to pollution. First the types of pollution that will specifically compared across these sources include air, soil, and water pollution. The impact of pollution on both of these could be catastrophic for obvious reasons like the necessity to breathe clean air and drink clean water, but also for their role in climate change and other pressing issues.
The primary source of energy in the world is fossil fuels like coal, natural gas, and oil, which make up 65% of the electricity generated on Earth. [1] While it is not the most readily available source of energy on the planet it is the most consumed. The heavy reliance on fossil fuels is tied to many factors like its ease of transport, existing infrastructure, and heavy economic and political ties. This reliance however has become a major talking point amongst policy makers and scientists due to its seemingly heavy impact on climate change. When burned fossil fuels emit greenhouse gases (GHGs) that do exactly what their name suggests, create a greenhouse effect in our atmosphere. This effect occurs when GHGs like carbon dioxide, the canonical chemical mentioned in climate conversations, are introduced to the atmosphere, which then retains the blackbody radiation that Earth would normally emit back into space. This retention in heat, also known as global warming, is leading to many adverse impacts such as human health, agriculture, and the environment at large. Carbon dioxide emissions themselves, in concert with its global warming effect, are also linked to ocean acidification and warming, threatening coral reefs, which are a major planetary ecosystem. [1]
Moreover, the waste produced from collecting, refining, and combusting fossil fuel is full of pollutants. For instance, coal mining results in waste that is full of toxic, heavy metals like Lead. A study done in the Shandong province in China found that the concentrations of these heavy metals in farmland soil near coal mines are far higher than average, and that "the total risk from exposure to the multiple metals in vegetables exceeded the acceptable levels for both adults and children" by 2-8 times in some cases. [2] It is clear that pollution of this nature not only hurts the environment, but also offers a very clear risk in terms of people's health. This type of pollution illustrates one of many, harmful side effects of our reliance on fossil fuels.
Since nuclear energy is often seen as an alternative to fossil fuels it is important to analyze its contribution to pollution. Firstly, it is important to note that compared to fossil fuel plants, "nuclear plants produce virtually no greenhouse gas emissions or air pollutants during power generation". [3] This is a significant difference because of its health impact. When nuclear was replaced by coal as the primary energy in the Tennessee Valley Authority after the Three Mile Island accident, the additional coal burning lead to a 10 μg m-3 increase in total suspended particulate (TSP), which is a measure of particle pollution. [3] This case study demonstrates a major benefit of nuclear energy compared to one of the current leading sources in energy. It is clear that that due to the nature of nuclear plants there are little to no GHG emissions which means cleaner air and little to no climate change contribution.
However, while the benefits in regards to emissions are promising, there are some issues with regards to the waste from nuclear power plants being introduced to the nearby environment through a large scale accident or leakage (see Fig. 1). Waste from nuclear fission include by-products such as radioactive cesium must be disposed of properly due to its ~30 year half-life and possible environmental contamination in the case of an accident. [4] While the radionuclides mixed into other substances may have relatively shorter half-lives, there are other products of fission that remain in damaged fuel and can remain dangerous for a very long time. [5] Much like the short term effects of radioactivity due to nuclear waste are problematic, so too are their long term effects. Cs-137 radioactivity is 200,000 Ci/MTIHM a decade after fuel discharge. [6] By converting this to Becquerels we get:
This means that the amount of γ-ray emission, which is known to damage cells during division, by this waste in 1 second is 7.4 × 1015. This, coupled with the fact that a far less radioactive by- product like Zr-93, an isotope of zirconium, may stay in the environment for over a million years, is concerning when considering potential long-term abandonment of areas in the wake of an accident. [6] Historical events of compromised nuclear plants indicate the scale to which dangerous substances can pollute and endanger the environment and people, and this is where nuclear energy falls short of other power sources in regard to pollution potential. While a nuclear power plant may not always be emitting or introducing pollutants to the environment like a coal plant does, there is always the possibility of an accident, akin to those that happened in Fukushima and Chernobyl, or a human launched attack, to cause incredibly, long term environmental problems. The severity and longevity of these consequences seem to indicate that nuclear energy may not be a suitable alternative to coal from a pollution perspective.
Since there are such catastrophic consequences on the line, there is a lot of research in the best ways to process and store this waste to prevent contamination outside of the plant. For instance, there is a study attempting to convert these nuclear wastes into an inorganic, stable crystal, a process that only takes 10-20 hours. [4] It is through research endeavors such as this one that nuclear energy make continue to become a feasible, trusted source of energy, while reducing the possibility of an environmental disaster due to radioactive contamination.
© Zen Simone. 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] D. Bogdanov et al., "Radical Transformation Pathway towards Sustainable Electricity via Evolutionary Steps," Nat. Commun. 10, 1077 (2019).
[2] F. Li et al., "Impact of the Coal Mining on the Spatial Distribution of Potentially Toxic Metals in Farmland Tillage Soil," Sci. Rep. 8, 14925 (2018).
[3] E. Severnini, "Impacts of Nuclear Plant Shutdown on Coal-Fired Power Generation and Infant Health in the Tennessee Valley in the 1980s," Nat. Energy 2, 17051 (2017).
[4] N. D. Quang, "Versatile Chemical Handling to Confine Radioactive Cesium as Stable Inorganic Crystal," Sci. Rep. 8, 15051 (2018).
[5] P. C. Burns, R. C. Ewing, and A. Navrotsky, "Nuclear Fuel in a Reactor Accident," Science 335, 1184 (2012).
[6] A. G. Croff, M. S. Liberman and G. W. Morrison, "Graphical and Tabular Summaries of Decay Characteristics for Once-Through PWR, LMFBR and FFTF Fuel Cycle Materials," Oak Ridge National Laboratory, ORNL/TM-8061, January 1982.
