Some features of smaller reactors can further offset the economies-of-scale advantage of large ones. They can be assembled in factories rather than custom-assembled on-site. .
Babcock & Wilcox has supplied small reactors for ships, but reactors at this scale haven’t been used commercially to generate electricity on land. A few companies have recently designed small land-based reactors that would generate just 10 percent of the power of a conventional one but could be linked together to generate power comparable to the output of a conventional plant. Some of these use advanced nuclear reactor designs that haven’t been tested extensively. B&W’s reactor, however, is very similar to conventional pressurized water reactors, the predominant type used in Western countries, so it is likely to be comparatively simple to get permitted and built. One difference is that conventional reactors can have multiple expensive pressure vessels linked by 75-centimeter-diameter pipes, but the new design requires only one pressure vessel, eliminating the need for such large pipes. The large pipes are a source of vulnerability in a conventional reactor—if they break, the reactor can lose coolant very quickly, so expensive backup cooling systems are required.
Only after the plants are operating will it become clear what the electricity they generate actually costs. Many costs are fixed no matter the size of the reactor—a small plant will still require the same number of guards, for example, says Michael Golay, a professor of nuclear engineering at MIT. It’s also not clear how much simpler, if at all, the containment structure and other safety systems can be, he says. “If it were my money, I wouldn’t invest in them,” he says.