Or the site could be a technological dead end. It all depends on whether the government approves an international consortium’s proposal to build the world’s first commercial “pebble bed” reactor at Koeberg. Proponents say the reactor’s innovative design is the crucial next step toward a nuclear-powered future. They argue that pebble-bed technology is safer, more efficient and more dependable than the obsolescing “light water” reactors now in general use. Opponents, convinced there’s no such thing as safe nuclear power, have vowed to block the Koeberg project. And Maqubela–despite his undisguised eagerness to put South Africa at the forefront of energy technology–says his office has yet to decide who’s right. “It’s going to be a challenge to convince us of the safety and the economic benefits of this project,” he warns.
The Koeberg plant’s backers don’t seem worried. The pebble-bed design aced its first field tests more than a quarter-century ago. A 15-megawatt demonstration model was built in Germany in the 1960s, and it hummed along handsomely for the next 21 years. It might be going strong to this very day if it hadn’t been shut down ahead of schedule, a victim of the antinuclear panic that swept the world after the 1986 Chernobyl disaster. Too bad, pebble-bed advocates say, because their reactor’s design makes a Chernobyl-style disaster virtually impossible. The plant can’t get hot enough to cause a meltdown, even if operators do nothing to prevent it. The designers call it “walk-away safe.”
The basic design is simple enough. Like any other nuclear power plant, the pebble-bed design uses heat from a controlled nuclear chain reaction to drive an electrical turbine. There are three main differences. The first is the way the fuel is configured. In a standard light-water reactor, the heat is generated by a fixed array of several thousand metallic fuel rods. In a pebble-bed reactor, the fuel takes the form of loose graphite spheres the size of tennis balls. Each “pebble” contains thousands of tiny ceramic-coated granules of uranium dioxide. The second difference is what drives the turbines: standard nuclear-plant turbines run on steam, while the pebble-bed system uses superheated helium gas. The third difference is scale. The Koeberg reactor, if it is ever built, will be about a 10th the size and power of a typical 1,100MW light-water plant.
Advocates say the reactor’s small size is one of its biggest virtues. A pebble-bed plant can be constructed from scratch in roughly two years, about a third the time it takes to build a standard light-water plant. Pebble-bed technology would enable power companies to tailor their generating facilities to fit local needs, rather than creating massive power grids to deliver electricity across country. Best of all, small size helps make the reactors accident-proof. They dissipate heat faster than big reactors, making the risk of a major accident even more remote.
The pebble-bed reactor’s inherent safety makes elaborate backup systems unnecessary, according to its designers. In light-water plants, the fear of a meltdown forces engineers to include multiple cooling and control systems in case anything goes wrong with the primary systems. Pebble-bed technology eliminates such costly features. Proponents say the graphite and ceramics of a pebble-bed reactor are heat-resistant up to 1,600 degrees Celsius or so, and the laws of physics won’t let it get hotter than that. “There isn’t a need for high auxiliary safety systems,” says Dave Nicholls, CEO of the Pebble Bed Modular Reactor consortium. In fact, the pebble-bed design doesn’t even bother with the massive reinforced-concrete containment vessel that is standard for light-water plants.
The idea gives environmentalists the chills. “Containment is the last line of defense between the public and radiation in an accident,” says Jim Riccio, a Greenpeace nuclear-policy analyst in Washington. “There’s nothing inherently safe about this plant.” Even if the pebble-bed reactor really is as meltdown-proof as its designers claim, activists say catastrophic releases of radiation are still a threat. Suppose a breach in the reactor allows the helium to escape, says Arjun Mahijani, president of the Institute for Energy and Environmental Research in Tacoma Park, Maryland. If air gets in, what’s to prevent the graphite fuel pebbles from catching fire, releasing radioactive smoke into the atmosphere? “I don’t think this reactor is a good option for South Africa or any other country,” says Mahijani.
Nicholls is unfazed by such qualms. “The physics back me up,” he says. His consortium wants to manufacture pebble-bed reactors in South Africa for sale around the world. He says building and exporting just 10 a year would create 57,000 jobs and add nearly $700 million to South Africa’s GDP. Many South Africans are less optimistic. The consortium has already invested nearly $50 million in preliminary development, and the plant has not yet moved beyond the planning stage. Newspaper editorials grumble about the cost of the Koeberg plant when South Africa has an abundance of cheap coal to manufacture electricity.
Still, South African coal has its own drawbacks. It’s dirty and expensive to transport from the mines to the industrial centers where energy is most needed. The consortium’s South African member, the energy giant Exelon, is looking to pebble-bed technology to replace its existing 17 light-water plants when they are retired. Exelon is even talking to the U.S. Nuclear Regulatory Commission, with hopes of submitting an application to build a stateside pebble-bed plant in 2004. It’s been more than 20 years since a new atomic-power plant was commissioned on U.S. soil. Memories of Three Mile Island still haunt many Americans–and many South Africans, too. But Nicholls is sure those fears will pass. “A lot of this is a perception problem,” he says. “It’s just a matter of explaining to the public how this is going to work.” The question is whether he will get a chance to show how it works.
