May 6, 2002 Despite the bad press that nuclear reactors earned in past years, researchers writing for the latest issue of Physics Today magazine report that more and more people are reconsidering nuclear power as an alternative to fossil fuel. In fact, President George Bush's National Energy Policy explicitly supports expansion of nuclear power, in contrast to the policies of previous presidential administrations. The primary reasons for the shift in opinion stem from concerns for the environment and interest in enhancing national energy self-sufficiency.
At the moment, nuclear and hydroelectric power are the only technologies that can generate large amounts of energy without emitting copious greenhouses gases. Although dams may initially seem more appealing than nuclear reactors, hydroelectric power plants are impractical in the many regions that lack adequate sources of flowing water. That means nuclear power stands alone as a practical and environmentally friendly resource that is not tied to local geography. Although US efforts are just beginning to ramp up, a handful of modern nuclear reactors, known as Generation III devices, are being planned or built today in Japan, Taiwan, and South Korea. First generation reactors were the research devices that proved nuclear energy could work in the lab as well as on the chalkboard. Second generation reactors took the technology one step further, demonstrating that the machines were economically feasible power plants. Emerging, third generation reactors are equipped with advanced features, such as safety systems incorporating passive energy dissipation or natural processes, simplifying their design and allowing them to cope with malfunctions without the need for operator action.
Generation IV machines now in development, says Gail Marcus of the Department of Energy, will provide dramatic improvements in reactor design. "They're going to mean significant improvements in economics of their performance, in safety, and in waste minimization," Marcus explains, as well as being more resistant to attempts to divert mateial for illegal weapons manufacturing.
Some advanced design concepts include high temperature reactors that are 2-3 times more efficient than contemporary reactors, mechanically simpler machines with fewer moving parts for improved reliability, and nuclear plants that would process their own waste. Unlike earlier designs that were intended simply as electricity production facilities, the additional heat from high temperature reactors could provide hot water for nearby communities or energy for seawater desalinization. An important benefit of the reactors of tomorrow might be cleaner cars, says Marcus, because hotter, Generation IV nuclear plants could produce fuel for hydrogen-powered vehicles.
It will be another twenty-five or thirty years before fourth generation nuclear reactors come into service, but improved third generation reactors, which Marcus calls Generation III+ designs, may be in operation by the end of this decade.
"We have an initiative called Nuclear Power 2010," explains Marcus, "The goal is to have one or more new plants operating by the end of the decade. That means the commitment has to be made in the next couple of years."
Marcus and Alan Levin of the US Nuclear Regulatory Commission detail many of the near and long term options for nuclear power plants in the April 2002 issue of Physics Today (New Designs for the Nuclear Renaissance, pp. 54-60).
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