Is there a future for small modular reactors in the West?

That question might seem far-out if not for growing public concern about global warming. After being discounted for years, nuclear power is getting a second look, as utilities consider ways to meet the increasing need for electricity with low-carbon energy sources.

Arizona’s Palo Verde nuclear plant supplies 28.8 percent of the state’s electricity, but 76.8 percent of the carbon-free electricity. It is the only clean-air source that can produce large amounts of power 24/7. As a result, air quality is far better. A study by atmospheric scientist James Hansen estimates that nuclear power has prevented more than two million deaths globally and that it will save many more lives in the years ahead.

Because few utilities can afford to build a large nuclear plant, small modular reactors have become the preferred nuclear technology under consideration in the West. These reactors — known as SMRs — range in size from 50 megawatts to 150 megawatts and can be assembled in a cluster of up to 12 units for a fraction of the cost of a conventional 1,200-megawatt power plant.

SMRs have attracted the attention of a small but growing group of entrepreneurs and investors who believe the reactors hold the promise of early commercialization and could help solve the world’s climate challenges. Arizona is one of several states in the West that would benefit from SMRs, which could be used for desalination as well as electricity production. The Department of Energy expects that SMRs will be the first new reactors in the United States to be operating, in the next decade.

SMRs would be built in factories, using standardized designs and improved quality controls that help prevent construction delays. The reactors would be shipped by barge, truck or railroad to nuclear sites. One of the appealing features of SMRs is that additional modules can be added as the need for more electricity arises.

As many as 50 nuclear companies are engaged in designing SMRs and other advanced reactor technologies. One of the companies is a start-up called NuScale, which is working on a radically different reactor design based on technology developed at Oregon State University. Its design promises a major upgrade in safety. It is much simpler than a traditional reactor and relies on a passive safety system, enabling it to shut down and self-cool indefinitely with no operator action, no backup batteries and no external water supply.

NuScale expects to apply to the Nuclear Regulatory Commission for certification of its SMR design by the end of this year. The certification process usually takes three years, after which the company will be positioned to begin building the first domestically produced SMR. China already has an SMR under construction between Beijing and Shanghai.

Some other innovative designs for advanced reactors, some small and others large, could use spent nuclear fuel to power them and utilize different cooling mechanisms for more efficient and safety-enhanced power generation. One of the SMR designs is for a so-called pebble-bed reactor, in which the fuel is contained in ceramic and graphite balls rather than long, thin rods, and is cooled by gas rather than water. In such a design, the fuel cannot melt down in an accident, enabling a reactor to be safely located closer to cities.

TerraPower, a Seattle-based start-up financed in part by Microsoft founder Bill Gates, has designed a traveling wave reactor that runs on a waste product from the uranium enrichment process. Larger than an SMR, the traveling wave reactor is designed to provide cheap, reliable zero-carbon power for Asia’s economic growth. TerraPower has teamed up with the China National Nuclear Corporation to complete the design and commercialize the reactor technology. It plans to build a 600-megawatt prototype traveling wave reactor in China, with possible start-up by 2020, followed by a larger reactor for commercial use.

The upsurge of interest in advanced nuclear technology – especially SMRs — holds great promise for building a new source of low-carbon energy. It draws on the strengths of America’s innovative economy. There is the risk that lower-cost power sources, such as natural gas from shale production, could undercut the economics of nuclear power. But the environmental gains, in terms of lower emissions of particulates, sulfur and greenhouse gases, would be profound.

Barry D. Ganapol is a professor in UA’s department of aerospace and mechanical engineering. Contact