The large engineering and construction firm Fluor has taken a majority stake in NuScale Power, a startup that has been developing small, modular nuclear reactors. The investment effectively rescues NuScale, which had been near financial collapse after its biggest investor was indicted by the U.S. Securities and Exchange Commission for violating regulations.

The deal with Fluor will allow NuScale to continue its efforts to license its power plant design with the U.S. Nuclear Regulatory Commission, with the goal of having the first one up and running by 2020. Fluor’s engineers will help with the certification work, and the company eventually plans to engineer and build NuScale’s power plants.

The investment by Fluor is a vote of confidence in small modular nuclear reactors. These reactors generate 300 megawatts or less, about a third of what conventional nuclear reactors generate, and are designed to be safer and easier to manufacture. The technology has been gaining attention in recent years as high costs and safety concerns, such as those kindled by the nuclear accident at Fukushima, have hurt the prospects of large, conventional nuclear power plants. At the same time, organizations such as the International Atomic Energy Agency are anticipating a large market for small nuclear reactors in poor countries and in rural areas that don’t have the infrastructure or demand to accommodate conventional large reactors.

Other major engineering and construction companies in the nuclear industry have recently shown support for small modular reactors, including Bechtel and Babcock & Wilcox, which this summer announced a partnership with the Tennessee Valley Authority to work toward building six of Babcock and Wilcox’s small mPower reactors. Worldwide, dozens of designs being developed, including efforts in Japan, Korea, China, Russia, and Argentina.  U.S. Energy Secretary Steven Chu has made development and licensing of small modular reactors a focus for the U.S. Department of Energy.

The NuScale reactor design is based on technology developed by the DOE and Oregon State University, which was involved in the design and certification of the new Westinghouse AP1000 power plants that are being built now in China and at two locations in the United States. The reactor is a type of light water reactor, one of the most common types of reactors in use today. NuScale has completed a detailed preliminary design, and intends to submit a design certification application to the NRC next year.

NuScale’s reactors are designed to generate 40 megawatts each, compared to over 1,000 megawatts for conventional reactors. They can be linked together on site to generate larger amounts of electricity. Traditionally, nuclear power plants have been built large to take advantage of economies of scale. But the large size of the projects leads to long construction times, and delays and cost overruns are common, heightening the risk for investors and increasing financing costs.

Smaller reactors, which can be built in factories rather than assembled on site, could be faster to build, lowering financing costs. The designs can also be simpler, and thus cheaper than conventional nuclear power plants, since the smaller reactors require lower pressures, for example, and their small size makes it practical to combine multiple elements into one containment vessel. Some experts have calculated that costs per megawatt could be comparable to large nuclear reactors, but no one really knows because no small, modular commercial nuclear power plants have been built yet.

Even if costs per megawatt prove higher than with conventional plants, their small size might make them attractive in areas that lack the power lines and other infrastructure needed to distribute power from a large reactor, and that may not immediately have demand for the full power output of a large reactor. The modular design could allow utilities to gradually add more reactors as demand increases. Several rural electric cooperatives in the United States have expressed interest in using NuScale’s small nuclear reactors to replace aging coal plants—the small size of the plants would eliminate the need to upgrade existing transmission lines.

Critics of small nuclear reactors, such as the Union of Concerned Scientists, say that large numbers of small reactors could be more difficult to manage during an accident, and could pose greater risk of nuclear materials falling into the hands of terrorists or rogue states.