Reactor carries scientists' hopes / Planned French facility may be last chance for dreams of cheap power through fusion

San Francisco Chronicle
26 June 2007
Keay Davidson
Chronicle Science Writer

Construction began this year in France on one of the largest machines ever built -- a $12 billion, eight-story nuclear fusion reactor that some researchers hope will mark the beginning of the end of the world's recurrent energy crises.

The International Thermonuclear Experimental Reactor, or ITER (pronounced "eat-er"), won't be a commercial reactor plugged into an electric grid to power homes and businesses. Rather, it will be a prototype to test the feasibility of fusion as an energy source for the masses.

In March, workers finished felling trees at the ITER site at Cadarache, France, and construction of the facility is under way now.

The project is slated to be up and running before 2016.

Within its vast, doughnut-shaped interior, a superhot mist or plasma will merge or "fuse" subatomic nuclei to unleash their immense inner energies as with the sun or a hydrogen bomb. The process has been studied for decades as a potential energy source that believers say would be far cleaner than burning fossil fuels or nuclear fission, which is used in nuclear reactors but produces dangerous radioactive waste.

But after all that time and tens of billions of dollars that the United States and other nations have poured into research, fusion energy has yet to power a single toaster, TV or iPod. So there's a lot riding on the prototype reactor, which emerged from a scientific effort by the United States and six other nations.

If it fails, it will be another in a long series of fusion- research duds.Only this time, it would be such a colossal failure that it could kill all fusion research for good.

Success would be a significant step forward in science's search for a permanent and nonpolluting energy source, even if it will take a few more decades of research and development before fusion energy can be proved economically and environmentally attractive for mass production.

Critics say research of nuclear power fusion is a wasted effort. They say fusion reactors for mass production of commercial electricity will cost fortunes because of their monstrous size and complexity. They also say the claims that fusion energy is clean are false. The fusion reaction itself, they say, will make the reactor vessel radioactive, and that means it'll eventually have to be discarded, perhaps buried -- but where? At the moment that's anyone's guess, given public hostility to radioactive waste sites.

Supporters acknowledge that nuclear fusion will produce radioactive waste.But like the pollution from a Toyota Prius versus a Hummer, the radioactive waste from fusion versus fission will be at a lesser volume and intensity.

Scientists have been dreaming about fusion energy since at least the 1930s. But research didn't really take off until the 1950s, when fusion won the hearts of a small number of idealistic scientists. As they saw it, fusion energy offered a dirt-cheap source of electricity that could benefit underdeveloped nations and the impoverished.

Christine Celata, a leading fusion researcher at Lawrence Berkeley National Laboratory, said her career path was determined in part after she heard one expert call it "peaceful power for the poor."

"It's hard to find anybody in fusion who didn't want to save the planet," Celata said.

They had no idea how many decades of disappointment lay ahead. Nowadays, they've grown tired of hearing the old joke, "Fusion is the future of energy -- and always will be."

Like aging hippies who still sport weathered peace symbols, Lawrence Berkeley staffers cling to their idealistic vision. In their PowerPoint presentation about fusion, one image shows a fusion plant on a sunny coastline under the headline: "Heavy Ion Fusion -- Peaceful Power for the Poor."

Enthusiasm for fusion energy, however, is no longer shared by Congress, which agreed to fund the United States' contribution to ITER -- estimated at more than $1 billion by the time it's completed -- on one condition: that almost all other nonmilitary U.S. fusion research stop.

That upsets Celata and her colleagues at Lawrence Berkeley and other fusion labs who believe there's good reason to continue exploring alternative fusion approaches while the new project gets going.

"I'm a zealot," said Grant Logan, a veteran Lawrence Berkeley fusion researcher. "It's like trying to create conditions at the center of the sun."

Scientists have explored numerous possible routes to fusion over the decades. These range from the technically promising, such as magnetic fusion, to the dubious, like "cold" fusion, which attracted wide attention in the late 1980s but quickly proved to be pseudoscience.

The leading alternative to magnetic fusion is "inertial confinement." In this approach, a pellet of nuclear fuel (hydrogen isotopes called deuterium and tritium) are bombarded by multiple beams of energy -- either photons, laser beams composed of light particles, or heavy-ion beams of elements such as xenon. The bombardment compresses or implodes the pellet, forcing its atomic nuclei to fuse and expel energy.

For years, Celata, Logan and their colleagues at Lawrence Berkeley and Lawrence Livermore National Laboratory have researched inertial confinement.The Lawrence Berkeley team pursues the heavy- ion approach, while Livermore investigates the laser method.

Unfortunately, the Bay Area scientists face the same kind of demon -- "instabilities" -- that has long taunted magnetic fusion researchers elsewhere. Ideally, the fuel pellet must implode in a smooth, symmetrical manner -- that is, it must remain highly spherical even as it compresses. In reality, it deforms into an uneven shape that ruins the fusion process.

The need to solve the instabilities problem is one major reason for building ITER -- its size is expected to be an advantage because the bigger the reactor, the fewer the instabilities. Or so theorists hope.

Even if scientists overcome the technical issues, it will take years of research to solve fusion's other potential problems.

One, for example, is what to do about the radioactive waste fusion reaction will generate by producing neutrons that quickly turn the reactor vessel into a highly radioactive object that eventually will have to be discarded.

One of ITER's key subprojects is looking for reactor building materials that are least vulnerable to becoming radioactive. Whatever material they choose has upsides and downsides. ITER will be so hot that its own components could be damaged.

A possible solution is lining the reactor vessel wall with carbon, which readily absorbs heat. But carbon also could readily bind with tritium, and since carbon binds quickly with living organisms, it could pose an environmental threat if it escapes from the reactor.

Scientists also could line the walls with tungsten; unfortunately, its tendency to develop a strong positive charge could dispel the electrified plasma. Or they could use beryllium, but it's a dangerous poison and it melts too easily. And so on.

"ITER carries very large risks," said nuclear engineering Professor Per Peterson of UC Berkeley.

Scientists, engineers and energy experts are sharply divided over whether controlled fusion has a future.

Steve Chu, the Nobel Prize-winning physicist who heads Lawrence Berkeley, drew laughter in September when he told an audience at an energy conference at Stanford: "I'm going to skip (discussing) fusion because it will probably skip the 21st century."

Such gloomy talk doesn't dispirit the true believers at fusion labs around the world. They've heard it all before.

"Fusion would be much safer (than fission) once we get it to work, and I believe we will get it to work," Logan said.