Bite-Size Nuclear Reactors: More Than We Can Chew?

Miniature nuclear reactors have been powering nuclear submarines for decades. But is this bite size technology ready for the main stream?

In their recent white paper “Small Modular Reactors—Key to Future Nuclear Power in the US,” Robert Rosner of the Energy Policy Institute at Chicago and Steven Goldberg of Argonne National Laboratory argue that America’s history with Small Modular Light Water Nuclear Reactors (SMRs), the growing demand for carbon-free energy sources, and a potential cost advantage make SMRs ready for prime time: the U.S. nuclear energy market.

While each module generates only 300 megawatts or less of power – a typical nuclear reactor generates approximately one gigawatt (1000 megawatts) – deploying a system of SMRs could have a dramatic effect on the domestic energy portfolio.

Light water SMRs are governed by the same physical principles as the aging fleet of traditional reactors. Atomic reactions generate heat that boils water into steam, which in turn drives electricity-generating steam turbines. However, the smaller size of SMRs allows these power plants to be placed underground, situated in more diverse geographical locations, and, potentially, manufactured in a standard, cost-effective way.

There are two major design advantages of a smaller size. First, SMRs are less susceptible to potential attack. When they are placed underground, SMRs have an additional layer of protection that intruders must penetrate before gaining access to the site. Underground modules are also more difficult to target from the air. Second, because SMRs are submerged underwater, they are better protected from natural disasters — especially earthquakes — because the water can absorb seismic forces and shaking. The authors argue that SMRs would not suffer the catastrophic safety failures that occurred at the Fukushima Dai-ichi Plant in March of 2011.

But can these SMRs compete economically with alternative green technologies and with low natural gas prices? Rosner and Goldberg assert that they can, but only under particular economic and regulatory conditions.

SMR plants have two major cost advantages over alternative energies: they can be built one module at a time, thereby reducing up-front capital costs, and they can take advantage of existing nuclear infrastructure such as component and equipment facilities.

Large-scale reactors are constructed on-site from scratch. As a result, each site requires expensive capital investments and is staffed by a novice local workforce that must learn by doing; costly delays are common due to small errors. In contrast, production of SMRs in a manufacturing facility would benefit from an experienced workforce and machine-controlled precision and could create economies of scale. Under these conditions, SMRs would not only be competitive with carbon-based energy, but would have lower unit-energy prices than other alternative energy options, such as wind, solar photovoltaic, solar thermal, and geothermal, which are less efficient and less reliable and suffer from high capital costs.

However, alternative energies do not face the same regulatory challenges as nuclear power. In order to further decrease the costs of SMRs to a competitive level, the Nuclear Regulatory Commission (NRC) would have to rule in favor of changing license requirements. One such change would be a reduction in the number of onsite staff required at nuclear facilities, which would decrease operating and infrastructure costs.

Rosner and Goldberg also outline a variety of ways that the government should support the nascent SMR industry, including cost incentives and market transition strategies to help limit the uncertainty and risk that often deter private investors.

The authors map out a five-step business plan beginning with a first-of-a-kind pilot plant and ending with fully developed facilities that have achieved economies of scale. But there is much to do before their plan is realized. While the paper mainly examines SMRs based on economic and manufacturing factors, the regulatory challenges that small reactors face are significant. Despite the country’s history with SMRs, this difficult regulatory environment and anti-nuclear sentiment after the events at Fukushima Dai’ichi will make deploying small modular reactors on the scale the authors imagine a challenge.