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| Fig. 1: A retired nuclear reactor at the University of Washington. Micronuclear technology aims to serve the same university community with a much smaller scale reactor. (Source: Wikimedia Commons) |
Micronuclear reactors are very small nuclear reactors that operate in the 1 MWe to 10 MWe range. [1] Micronuclear reactors are capable of operating independently from the electric grid. [1] They are carbon-free and can produce electricity on- demand. Cost to generate electricity from microreactors was estimated from the Department of Defense at up to $0.41/kWh, but is projected to drop to $0.33/kWh pending further technology development. [1]
The two types of micronuclear reactor power sources include an isotope generator, which converts decay heat to electric energy, and nuclear reactor power source, which converts fission heat into electric energy. [2]
Micronuclear power excels in situations where traditional gigawatt-scale capacities are unnecessary, like remote regions industrial sites, arctic communities, mines, large companies, and college campuses. [3] Fig. 1 shows a nuclear reactor at the University of Washington campus. Micronuclear reactors will also be used to provide energy to university campuses, on a much smaller scale. The small size of micronuclear reactors reduces power house build time to less than a year. [3]
Implementation of micronuclear is projected in remote communities and also within the United States government. In Alaska, diesel and coal account for about 20% of electricity generation. [1] Alaska has about 300 rural communities that are not linked to a larger electric grid. [1] For these communities especially, access to a reliable source of clean energy is essential. The United States Department of Defense is particularly interested in micronuclear power; 90% of military installations have power need that could be met with installed nuclear power capacity less than or equal to 40MWe. [1]
Oklo in Silicon Valley is working on building micronuclear reactors. [3] Oklo's micronuclear reactor, Aurora, is expected to have a 1.5 MWe capacity. [3] Oklo will own and operate these reactors on site at large companies and college campuses. [3] Primary obstacles to Oklo's deployment, in addition to regulatory issues, include the economics of operating micronuclear reactors. [3] To decrease the costs to run each reactor, Oklo anticipates having no personel on site at each reactor, which means each reactor must be proven safe enough to operate entirely autonomously and without any security staff. [3] There is concern that many of the cost-cutting measures companies may take to make these micronuclear reactors cheaper could make them less safe. [4]
Other startups in the micronuclear space include Elysium Industries, General Atomics, HolosGen, NuGen, and X-Energy. [3] Elysium is creating nuclear reactors to operate at 4-100 MWe. [1] General Atomics is developing an autonomous mobile nuclear power supply on the order of 4-10 MWe that can last about 10 years before requiring refueling. [1] X-energy is working on a road-transportable reactor that can be run autonomously without operators on site. [1]
The United States Nuclear Regulatory Commission (NRC) was established by the Energy Reorganization Act of 1974. [5] The NRC retains authority over nuclear power plants within the US and exports from the US. [5] The Department of Energy is responsible for the development and production of US defense-related nuclear weapons and promotion of nuclear power. [5] Thus, most of the regulation associated with micronuclear startups will come from the NRC. The regulatory framework includes safety goals that specify the acceptable level of risk. [6] NRC quantitative safety goals include this: the risk to an average individual in the vicinity of a nuclear power plant as a result of reactor accidents should not exceed 0.1 percent of the sum of fatality risks resulting from other accidents that would be commonly encountered by people living in the US. [6] The NRC specifies requirements for US Nuclear Power Plants that include redundant barriers and safety systems, properly trained reactor operators, and ongoing testing and maintenance. [6] In some situations, these regulations pose a threat to the business model of micronuclear reactors. For example, Oklo's plan to have no personel on-site at the reactors is in opposition to the NRC requirement to have properly trained operators on site.
Micronuclear reactors can provide clean energy on-demand working off the central power grid. The United States Department of Defense is particularly interested in micronucelar development for deployment to supply power to various bases and in remote locations. Additionally, startups are working on implementing micronuclear for use in large companies and universities, but a plethora of economic and regulatory hurdles remain.
© Rekha Ramanathan. 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] "Cost Competitiveness of Micro-Reactors for Remote Markets," Nuclear Energy Institute, 15 Apr 19.
[2] H. Sun et al., "Reactor Core Design and Analysis for a Micronuclear Power Source," Front. Energy Res. 6, 14 (2018).
[3] C. Clifford, "Oklo Has a Plan to Make Tiny Nuclear Reactors That Run off Nuclear Waste," CNBC, 30 Jun 21.
[4] D. Michaels, "Mini Nuclear Reactors Offer Promise of Cheaper, Clean Power," The Wall Street Journal, 11 Feb 21.
[5] "Nuclear Regulatory Legislation - 112th Congress, 2nd Session," NUREG-0980, Vol. 1, No. 10, September 2013, p. 241.
[6] V. Mubayi and R. W. Youngblood III, "Re-Evaluating the Current Safety Goals," Idaho National Laboratory, INL/CON-18-52120, May 2019.
