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| Fig. 1: Small Modular Reactor - Courtesy of the U.S. Government Accountability Office. [7] (Source: Wikimedia Commons) |
Small Modular Reactors, like the one in Fig. 1, are classified as nuclear power plants that have a capacity of 300 megawatt capacity or less, a fraction of the size of traditional nuclear power plants. [1] They have gained much attention as a potential renewable energy source that could help the transition away from fossil fuels. However, there are significant challenges confronting SMRs and whether they will be able to take on a sizable portion of the grid is in question.
There are some speculated advantages over larger nuclear power plants including being more transportable, requiring less uranium fuel (which could reduce risk of nuclear meltdowns), and initial capital expenditures being more affordable. [1] SMRs also have the ability to load follow, ramping up or down to match electricity demand throughout the day. [2] With the rise of solar power which goes offline at night, having this flexibility is incredibly valuable to grid operators. Currently, natural gas power plants are used most often as the load following electricity source; however, their greenhouse gas emissions are significant. If SMRs are able to load follow at scale, taking a portion of this responsibility from natural gas could lead to a lower carbon energy future.
Another advantage of SMRs is that they can operate independently of the civilian grid, reducing their susceptibility to grid outages. Because of that, SMRs could still play an important role in powering critical operations like military bases. Currently, domestic military bases receive 99% of their power from the civilian grid, which poses national security risk in the event of an outage due to extreme weather or a coordinated attack. SMRs 300 MW capacity is enough to power most military installations in the US, making these isolated bases a good use case. [3] However, a major concern with SMRs and nuclear power in general is the radioactive nature of the fission products that pervade the fuel rod after it is spent. Given that this poses a very real terrorism and proliferation threat, deploying SMRs on military bases is a risk. Furthermore, there are alternatives to the SMRs that could also serve the same purpose of removing reliance on the civilian grid. These include an independent natural gas power plant or backup diesel generators in case of grid failure. Regardless, the Department of Defense stated that at least one SMR will be built on a domestic base by 2027, but no forward operating base, meaning a base located on foreign territory has any such plans. [3] The Department of Defense's Strategic Capability Office has since instituted "Project Pele" which will dedicate over $40 million to small-modular reactor Research and Development efforts. [4] This makes it clear that SMRs are a strategic priority for the military but actual on-the ground implementation is still far off.
Most traditional nuclear power plants are slowly being phased out, and very few new ones are being built. This is largely due to the fact that construction takes upwards of 10-15 years and costs associated with building large-scale facilities are tremendous. Advocates for SMRs state that they are economically efficient and would take less construction time than bigger facilities because SMRs are primarily composed of production line modules that are made in factories. However, the only large scale domestic nuclear project currently in construction, Plant Vogtle, similarly employed this modularized construction model within their AP1000 program. [5] Unfortunately, Plant Vogtle is over 6 years behind schedule in construction and total cost is currently over $27 billion, more than two times initial estimates. [6] This proves that the modularization strategy is not refined enough to provide economic benefits in the construction stage.
Furthermore, once construction is completed, SMRs still do not provide any economic incentive to shift away from the incumbent natural gas power plants. Even the most advanced reactors, like TerraPower's 345-megawatt Natrium reactor, have a levelized cost of electricity (LCOE) that is estimated to be $50-60 per megawatt-hour. In comparison, new combined-cycle natural-gas plants range from $44-73 per megawatt-hour. [2] LCOE numbers are complicated in nature, and because Terrapower has not deployed an SMR, there is no concrete evidence that they will be able to be cost competitive. For utility providers to switch to SMRs, proven LCOE will likely have to be lower than natural gas, as has become the case with renewables. Until then, there will be headwinds when it comes to adoption of SMRs.
In conclusion, there is still a ways to go for SMR technology and their economics to have a meaningful impact on the grid at scale. There are certainly potential use cases like military bases where they could be more immediately utilized. For advocates of SMRs, the good news is the U.S. Energy Department is investing over $3 billion over the next 7 years to support the advancement of cleaner technologies. [2] In the meantime, the United States should look elsewhere to help decarbonize the electricity grid.
© Samuel Beskind. 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] S. Harber, "Small Nuclear Reactors: Background, Potential Applications, and Challenges," Physics 241, Stanford University, Winter 2017.
[2] E. Shao, "Utilities Eye Mini Nuclear Reactors as Climate Concerns Grow," Wall Street Journal, 2 Aug 21.
[3] T. Rogers, "Nuclear Power for U.S. Military Installations," Physics 241, Stanford University, Winter 2018.
[4] K. Tubb and P.-J. Geller, "The Pele Program: An Exemplar of Government Nuclear Research and Development," The Heritage Foundation, Issue Brief No. 5054, April 2020.
[5] R. Gold, "Vogtle Nuclear Plant in Georgia Faces More Construction Delays," Wall Street Journal, 8 Jun 21.
[6] W. E. Cummins, M. M. Corletti, and T. L. Schulz, "Westinghouse AP1000 Advanced Passive Plant," Westinghouse Electric LLC, Proc. Int. Congress on Advances in Nuclear Power Plants (ICAPP '03), American Nuclear Society, 2003.
[7] "Nuclear Reactors: Status and Challenges in Development of New Commercial Concepts", U.S. Government Accountability Office, GAO-15-652, July 2015.
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