Is Small Scale Nuclear Power The Way To Go?

As much as nuclear power seems to be on the verge of a revival here in the US, there are still issues to deal with, particularly the One-Big-Plant designs favored by most of the world. But maybe that's not the best means of bring more nuclear power plants on line. Instead, smaller may be better, and in the end, less expensive.

A smaller scale, economically efficient nuclear reactor that could be mass-assembled in factories and supply power for a medium-size city or military base has been designed by Sandia National Laboratories.

"This small reactor would produce somewhere in the range of 100 to 300 megawatts of thermal power and could supply energy to remote areas and developing countries at lower costs and with a manufacturing turnaround period of two years as opposed to seven for its larger relatives," [Tom] Sanders said. "It could also be a more practical means to implement nuclear base load capacity comparable to natural gas-fired generating stations and with more manageable financial demands than a conventional power plant."

The reactor system is built around a small uranium core, submerged in a tank of liquid sodium. The liquid sodium is piped through the core to carry the heat away to a heat exchanger also submerged in the tank of sodium. In the Sandia system, the reactor heat is transferred to a very efficient supercritical CO2 turbine to produce electricity.

Because the right-sized reactors are breeder reactors -- meaning they generate their own fuel as they operate -- they are designed to have an extended operational life and only need to be refueled once every couple of decades, which helps alleviate proliferation concerns. The reactor core is replaced as a unit and "in effect is a cartridge core for which any intrusion attempt is easily monitored and detected," Sanders said. The reactor system has no need for fuel handling. Conventional nuclear power plants in the U.S. have their reactors refueled once every 18 months.

There are certainly advantages to having a number of smaller, more distributed power plants compared to the 1000MW+ big plants, particularly if the cost per megawatt-hour is comparable or less than that of the big plants. The cost of building the smaller plants is also significantly lower because many of the major systems will be built in factories and not on-site as they are today.

Since the smaller plants do not require the maintenance of the larger plants nor the more frequent refueling, the cost of operating them might be less on a per megawatt-hour basis as well. Because they use a different power cycle they will also have less of a problem with long-lived nuclear waste, unlike existing U₂₃₅ fueled reactors. (Some of the problems with spent fuel rods of this type are not technical in nature, but political. However we won't delve into that here.)

Unlike the alternative energy sources being touted as the Answer-To-It-All, these small reactors are designed to handle what is called base load. Alternative energy sources tend to be supply-driven sources, meaning they aren't available on demand, particularly if there's no wind or if it's dark out. Base load plants are demand-driven sources, meaning they can be turned up or down as the electrical demand requires.

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