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Nuclear Power and the Engineering Problems that Surround It��

Since the Industrial Revolution, we have primarily relied on fossil fuels for power, but what was once the dawn of a new era could spell the end of life as we know it today. Fossil fuels are a limited resource, and, as a Stanford study from 2019 suggests, we could run out of oil by 2052, gas by 2060, and coal by 2090 (Figure 1), which is within many of our lifetimes.1��

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Perhaps more urgent than running out of fuel is the issue of global warming, which has already contributed to ice at the pole melting, leading to higher ocean levels and flooding. Extreme temperatures, wildfires, and even hurricanes are becoming more frequent and more deadly due to global warming. Continuing to burn fossil fuels and release greenhouse gases into the atmosphere will further worsen heat waves, flooding, droughts, crop yields, and coral reef die-off.2��

A Greener Alternative��

Considering the scarcity and dangers of fossil fuels, we need an alternative; nuclear energy looks promising. As John Kennedy, a U.S Senator for Louisiana, explains, “Wisdom and data suggest that America needs an all-of-the-above approach to energy, one that includes renewables, fossil fuels, and nuclear energy.”3 Using known reserves, we have enough uranium to supply 100 years of power at current demand, and future technological improvements could utilize the uranium in the world’s oceans, which could supply thousands or tens of thousands of years of energy.4 Nuclear energy also does not have CO2 as a biproduct, so it could act as a good “bridge solution” while we find ways to further develop storage solutions for renewable sources of energy. The International Energy Agency (IEA) agrees that achieving net zero emissions globally will be more difficult without nuclear power, so nuclear plays a vital role in powering the future.5��

A Necessary Biproduct��

The clean power that nuclear energy provides does not come free, however. Creating energy from nuclear fuel necessarily produces radioactive waste. The United States alone has 85,000 metric tons of nuclear waste, which is increasing at a rate of 2,000 metric tons per year.6 The most dangerous of this waste is designated high-level waste (HLW), composed of spent fuel that remains thermally hot, highly radioactive, and potentially harmful to humans and the environment for hundreds of thousands of years.7 Though we have permanent storage methods for low- and mid-level wastes, will still don’t have a permanent solution for managing HLW. As a result, HLW is left on site at nuclear power plants with nowhere to go.��

Current Disposal and Storage Methods��

The disposal of HLW requires specific care. Some ideas for permanent solutions are absurd – involving burial in ice sheets or projection into space – but the international consensus for a permanent solution is burial in an underground repository.8 These repositories contain several barriers, so they will still contain the waste should any individual barrier fail. The stable physical waste form, the waste container, and the chosen site itself each provide an additional layer of security, protecting the environment from the nuclear waste and vice versa (Figure 2).9��

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Due to its intense heat, HLW needs to be cooled in pools for at least five years before it can be transported, but these pools are reaching capacity, and the solution has just been to cram more spent fuel into pools.10 This increases the potential risk in the case of a meltdown. In Fukushima, spent fuel rods posed a risk of further damage, sitting in pools without a proper containment vessel. Luckily, the hydrogen explosions were not close enough to the pools to cause any significant damage, but overcrowded pools pose a massive risk of making a catastrophic event much worse.11��

After being cooled, HLW is moved to dry cask storage, which provides additional layers of protection: a sealed metal cylinder enclosed within a metal or concrete outer shell (Figure 3). Dry casks are designed to be able to resist earthquakes, projectiles, tornadoes, floods, temperature extremes, and other scenarios, but they were not designed nor intended to be a permanent solution.10 Now, the question remains: can dry casks stand the test of time? Corrosion poses a very real risk, especially near the sea. If corrosion sets into the weld joints of steal casks, the materials may crack and fail, and sea-salt aerosols can accelerate this process.12 Leaching additional radioactivity into the environment with failed dry casks can have devastating consequences that could be avoided entirely if nuclear waste were kept far from the sea and other additional environmental factors by storing it underground.��

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Efforts Towards a Solution��

Finland is currently on track to have the world’s first permanent HLW disposal site, where an elevator and robotic vehicles will take waste 430 meters undergrown and 420 meters below sea level.13 The United States has planned to build a repository as well, but since Congress passed the Nuclear Waste Policy act in 1982, over 40 years ago, there is not even one in construction. Yucca Mountain Nevada was selected as the site for this repository in 1987, but all plans were cancelled by the US in 2010. In 2013, since no repository was under construction, the Department of Energy was ordered to cease collecting fees for the Nuclear Waste Fund (amounting to over $30 billion) and federal funding was eliminated in 2015.14 This leaves us with no long-term plan and no funding for the storage of nuclear waste in the United States.��

Repository Controversy��

But why was this project abandoned? One major fear is potential groundwater contamination. A 1996 study discovered that water had migrated from the surface to the depth of the repository in less than 50 years, much lower than the 1000-year predicted travel time. Hydrology guidelines state that “groundwater travel time to the accessible environment of less than 1000 years shall be grounds for disqualification,” but the Nuclear Regulatory Commission, using conservative assumptions and assuming failure of multiple barriers, discovered that the estimated peak radiological dose would be 1.3 mrem (millirem, a common unit of radiation) from groundwater, a small fraction of the current background radiation dose of 600 mrem per year in the United States.14,15��

Since geological repositories have not yet stood the test of time, there is feal of potential unforeseen consequences. Radioactive waste could potentially give off much higher levels of heat or corrode barriers more quickly than expected, posing a risk to the environment, but nature already has precedents for geological disposal. Two billion years ago, in what is now Gabon in West Africa, several spontaneous nuclear reactions occurred in a vein of uranium ore, continuing for 500,000 years before finally dying away. These natural nuclear reactors produced the same high-level wastes present in manmade nuclear reactors, including over five tons of fission products and 1.5 tons of plutonium, but this all remained contained and safely decayed into non-radioactive elements without any human intervention.8 This offers evidence that nuclear waste will not continuously corrode rock and wreak havoc on the environment if kept safely underground.��

Another concern is that geological repositories, in their current form, prevent recovery of waste. France desires a “reversible” disposal process since waste could prove to be valuable if future discoveries find new uses for spent fuel. For this same reason, Switzerland, Canada, Japan, and the US require retrievability in any disposal plan, and this could be incredibly difficult if waste is sealed in a permanent repository.8 Nuclear waste may be useful in the future, but currently it only poses risks to humans and the environment, the safety of which should be our utmost priority.��

Urgency of a Solution – Our Role as Engineers��

40 years have already gone by without any significant progress in building a repository, so how can we expect to solve this problem now? The answer is engineers. Yucca Mountain may never become a geological repository, but there is room for progress in the nuclear energy field. One opportunity presents itself in the form of education grants. In a press release this February, the NRC committed to awarding 22 education grants to 16 academic institutions to support nuclear science and engineering fields, amounting to $8.2 million total.16 This is a sign of future progress in this field for engineers, which will make building a geological repository possible.��

Proper transport casks need to be developed, the physical repository needs to be designed, and additional safety measures should be added to every step of the process. Engineers can redesign casks to be more resistant to corrosion, providing us with more time to find a solution. They can also design repositories where nuclear waste could be retrieved in the future should the need for them arise, which would help repositories seem more appealing to other countries that require retrievability in any disposal plan.����

Nuclear energy appears to be on the rise again. Georgia is currently constructing the first new nuclear unit the US has seen in over 30 years.17 Many plants in Japan are coming back online after being shut down following fears from Fukushima. Coal power plants can also be converted to nuclear, another issue that requires dedicated engineers and will be better for our environment in the end.18 All of this could be an excellent opportunity to move towards greener energy, but regardless of whether nuclear is here to stay or not, it will be the responsibility of engineers to make sure we have the technology to handle our current mountain of nuclear waste.��

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Reference��

1. Kuo, Gioetta. "When Fossil Fuels Run Out, What Then." MAHB, Standford, 23 May 2019, mahb.stanford.edu/library-item/fossil-fuels-run/. Accessed 11 Mar. 2024.��

2. Simmons, Daisy. "Myth-buster: Why Two Degrees of Global Warming Is Worse than It Sounds." Yale Climate Connections, 13 Feb. 2023, yaleclimateconnections.org/2023/02/myth-why-two-degrees-of-global-warming-is-worse-than-it-sounds/. Accessed 11 Mar. 2024.��

3. Kennedy, John. "Nuclear Energy Can Help the United States Respond to Climate Change and Geopolitical Challenges." Gale Opposing Viewpoints Online Collection, Gale, 2024. Gale In Context: Opposing Viewpoints, link.gale.com/apps/doc/YYZWQQ463208523/OVIC?u=coloboulder&sid=bookmark-OVIC&xid=37d08082. Accessed 28 Feb. 2024. Originally published as "Nuclear energy is key to America's economic and geopolitical future," US Senate, Office of John Kennedy, 3 Dec. 2021.��

4. "Uranium Supply Is Not a Significant Constraint to Using Nuclear Energy for Climate Mitigation." Nuclear Innovation Alliance, 18 Jan. 2022, nuclearinnovationalliance.org/index.php/uranium-supply-not-significant-constraint-using-nuclear-energy-climate-mitigation. Accessed 11 Mar. 2024.��

5. Nuclear Power and Secure Energy Transitions. Paris, IEA, 2022. IEA, www.iea.org/reports/nuclear-power-and-secure-energy-transitions. Accessed 28 Feb. 2024.��

6. "Nuclear Waste Disposal." U.S. Government Accountability Office, www.gao.gov/nuclear-waste-disposal. Accessed 28 Feb. 2024.��

7. "Radioactive Waste." U.S. Nuclear Regulatory Commission, 5 June 2020, www.nrc.gov/waste.html. Accessed 7 Feb. 2024.��

8. "Radioactive Waste Management." World Nuclear Association, Jan. 2022, world-nuclear.org/information-library/nuclear-fuel-cycle/nuclear-wastes/radioactive-waste-management.aspx. Accessed 28 Feb. 2024.��

9. Northrup, Clyde J. Scientific Basis for Nuclear Waste Management. New York City, Springer US, 1980. Advances in Nuclear Science and Technology 0065-2989. Springer, . Accessed 7 Feb. 2024.��

10. "Backgrounder on Dry Cask Storage of Spent Nuclear Fuel." U.S. Nuclear Regulatory Commission, 12 June 2023, www.nrc.gov/reading-rm/doc-collections/fact-sheets/dry-cask-storage.html. Accessed 29 Feb. 2024.��

11. Khan, Abid Hossain, et al. "Analysis of Possible Causes of Fukushima Disaster." International Journal of Nuclear and Quantum Engineering, vol. 12, no. 2, 2018, d1wqtxts1xzle7.cloudfront.net/55958055/Analysis-of-Possible-Causes-of-Fukushima-Disaster-libre.pdf?1520128753=&response-content-disposition=inline%3B+filename%3DAnalysis_of_Possible_Causes_of_Fukushima.pdf&Expires=1709179548&Signature=foiK0KHizhE~lQVnZZ5dncQcXm-jny1YYljBmkCFuedgJ2uyLZfKLv5D7rWUG6D5H9QX1TAEHKfZdC-d~Q-cgLlE88zf7yZgrSJie6YJJPmZj9pgOWeRiritfe5ZrKStmJCqNZT81fAiscMbMhuSZJu2Pl~JTC6YDG962okZFLKuoN2tiTLlg0jK6vv0ZifzfszqfSan6qgIHe7XqUMUDhLd6uVkd6aTSFSQ4PA31tuXM5xy0Wwx6nt7uqEVPWtAW3VdfEjwEXeEuz-dsy~A7LlPSQwGd9qaWkYxq-1dngDu~EYz~OW61WWuPtBoZDbywKxguWeXHPMrh4xYNlelsQ__&Key-Pair-Id=APKAJLOHF5GGSLRBV4ZA. Accessed 29 Feb. 2024.��

12. El-Showk, Sedeer. "Final Resting Place." Science, vol. 375, no. 6583, 24 Feb. 2022, . Accessed 28 Feb. 2024.��

13. Jacoby, Mitch. "As Nuclear Waste Piles Up, Scientists Seek the Best Long-Term Storage Solutions." Chemical and Engineering News, vol. 98, no. 12, 30 Mar. 2020, cen.acs.org/environment/pollution/nuclear-waste-pilesscientists-seek-best/98/i12. Accessed 29 Feb. 2024.��

14. Koth, Philip. "Yucca Mountain." Energy: In Context, edited by Brenda Wilmoth Lerner, et al., vol. 2, Gale, 2016, pp. 934-940. In Context Series. Gale In Context: Science, link.gale.com/apps/doc/CX3627100234/SCIC?u=coloboulder&sid=bookmark-SCIC&xid=ebfd271d. Accessed 28 Feb. 2024.��

15. Office of Nuclear Material Safety and Safeguards. Supplement to the U.S. Department of Energy's Environmental Impact Statement for a Geologic Repository for the Disposal of Spent Nuclear Fuel and High-Level Radioactive Waste at Yucca Mountain, Nye County, Nevada. U.S.NRC, May 2016. U.S. Nuclear Regulatory Commission, www.nrc.gov/docs/ML1612/ML16125A032.pdf. Accessed 29 Feb. 2024.��

16. Office of Public Affairs. "NRC Anticipates Awarding $8.2 Million in Education Grants Supporting Nuclear Science and Engineering Fields." NRC, 5 Feb. 2024, www.nrc.gov/cdn/doc-collection-news/2024/24-011.pdf. Accessed 28 Feb. 2024.��

17. "Vogtle Unit 3 Goes into Operation." Georgia Power, 31 July 2023, www.georgiapower.com/company/news-center/2023-articles/vogtle-unit-3-goes-into-operation.html. Accessed 29 Feb. 2024.��

18. Office of Nuclear Energy. "DOE Report Finds Hundreds of Retiring Coal Plant Sites Could Convert to Nuclear." Department of Energy, 2022, www.energy.gov/ne/articles/doe-report-finds-hundreds-retiring-coal-plant-sites-could-convert-nuclear. Accessed 29 Feb. 2024.��