Are Small Modular Reactors the Future of Nuclear Power?

By: Hannah Pell

Nuclear power is an important aspect of our diverse energy infrastructure. According to the U.S. Energy Information Administration, nuclear power plants produced 19.6% of the total electricity generated in the U.S. in 2019. Over the last several years, however, there has been a decline in the number of operating nuclear power plants. Many plants have reached or are nearing the end of their license periods (which last about 38 years on average) and are being decommissioned or shut down permanently. 22 reactors are currently undergoing the decommissioning process across the country (96 total operating plants at the end of 2019).

The decommissioning of nuclear power plants has been reported as a nationwide trend with little sign of reversing. If conventional nuclear power plants continue to be shuttered, then how will we replace this energy source? There are several ways — natural gas plants are a common example — but one stands out as a potentially viable path for the future of the nuclear industry itself: small modular reactors (SMRs).

What are Small Modular Reactors?
“Small” refers not only to their relative size but the amount of energy they can produce, specifically less than 300 MW (“megawatts”) as defined by the International Atomic Energy Agency, compared to the 800-1200 MW approximate range of energy production for commercial nuclear reactors. “Modular” means that they are scalable and could be produced in factory settings, an important characteristic discussed further below.

SMRs run on nuclear fission, the process in which an unstable atom (often Uranium 235) absorbs an extra neutron, splits, and releases energy in the form of heat and radiation. These chain reactions heat up the coolant (usually water), making steam drive the turbine and produce electricity. Nuclear reactors are, effectively, costly boilers. 

Image Credit: Office of Nuclear Energy at the U.S. Department of Energy.
Although small reactor technologies have existed for decades — nuclear-powered submarines being a prominent example — the rise of SMRs could still have important implications on our current commercial nuclear power infrastructure. So what are some of the potential advantages and disadvantages of this technology?

Pros and Cons
One major advantage of SMRs is their size, roughly one-third that of a typical nuclear plant. Because SMRs could be produced piece-wise in factories according to a standardized design, proponents argue that SMRs would mitigate cost overrun and high financial risk that have often accompanied traditional nuclear power plants’ construction and operation.

However, it would take mass production of SMRs to offset scale economies, which dictates that bigger scales means cheaper costs. So SMRs could be built faster, cheaper, and more efficiently, but only if produced in high numbers, like cars. (In fact, the UK automobile company Rolls Royce has plans to produce SMRs).

Another important advantage due to their size is location flexibility. Because they produce significantly less power than a traditional reactor, SMRs would be particularly suitable to more rural regions or even countries with smaller electricity grids. One SMR alone could power an entire remote Alaskan fishing village. Due to their smaller scale and passive safety features, SMRs would also require far less staffing to operate. “People had laughed at me when I said I could run this plant with six people,” NuScale Power operations engineer Ross Snuggerud told Science Magazine in 2019. 

A mock SMR control room. Image Credit: NuScale Power, LLC.
One of the biggest challenges SMRs currently face is licensing. The Nuclear Regulatory Commission (NRC)’s regulatory guidelines have historically applied to large commercial reactors. Because SMRs are a relatively new approach to commercial reactor design, licensing them necessarily involves a lengthier and more costly process.

SMRs, nuclear’s future?

The future of SMRs seems bright. The Department of Energy is currently working with NuScale Power and the Utah Associated Municipal Power Systems (UAMPS) to develop SMR technologies over the next decade. In December 2019, the NRC approved the first SMR site license to the Tennessee Valley Authority, valid for 20 years. The NRC is currently reviewing applications for SMR designs from various applicants; NuScale Power is on track to receive full approval by August 2021.
Image Credit: NuScale Power, LLC.

While the debate about nuclear power is contentious, one thing remains clear: it remains a critical part of our energy infrastructure. The continued development of SMR technologies may be an important and beneficial upgrade to commercial nuclear energy production. As we continue to invest in clean, low-carbon energy sources, SMRs could prove to be a viable option for our clean energy future.

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