Teschler on Topic

Always 10 years away

When I was a college freshman I had the opportunity to take a guided tour of KMS Fusion. KMS was one of the first private companies that tried to build a fusion reactor. That tour was a bit more than 50 years ago, and I don’t recall much about it. My only remaining memories are of a room filled with capacitors that took about a day to charge up, and of our tour guide—one of the Ph. D.s who worked there—mentioning it would take about ten years before they were able to achieve a sustainable fusion reaction.

Of course, that prediction turned out to be a bit optimistic. But I suspect the KMS Ph. D.s would have scoffed back then if someone had told them they would all reach retirement age without ever seeing a sustainable fusion reaction,

Fusion reactor proponents have long displayed the same kind of optimism as the KMS Ph. D.s. Atomic Energy Commission fusion program director Robert L. Hirsch in 1971 told Congress that vigorous funding would make it possible to build a demonstration fusion reactor by 1995. That enthusiasm is present today. Two years ago, a project called the Spherical Tokamak for Energy Production began in the U.K., and proponents claim it could be operating by 2040. ITER (initially the International Thermonuclear Experimental Reactor) is under construction in France with operation planned for 2035. And researchers at a demonstration reactor in Japan claim a fusion generator there should be feasible no later than the 2050s.

No question that a fusion reactor is a major engineering undertaking. But history chronicles numerous engineering projects that were massive yet successful and completed within a reasonable time frame. So you might wonder why that hasn’t been the case when it comes to fusion reactors.

Insight into this question comes from L.J. Reinders, a Ph. D. who worked in high-energy physics for 12 years and who now, among other things, writes about fusion. He points out that unlike other areas of physics, investigations of fusion reactors became politicized relatively early. In the 1960s, independent research labs themselves decided what fusion research problems to pursue. But in the 1970s, the Atomic Energy Commission steered the fusion community away from fundamental research and toward the creation of commercial energy from fusion.

It was just too soon to think about commercializing fusion, Reinders argues, because numerous fundamental issues in plasma physics had yet to be resolved. And in fact, that’s still the case today. To cite just one example, consider the rationale for building the ITER. The temperature of the plasma in which fusion must take place has to be about ten times as hot as the core of the sun. ITER uses magnetic fields to confine the plasma and keep it away from the walls of the containment vessel; if it touches the walls it loses energy and cools off. The point of building the huge ITER reactor is to move the container walls farther from the plasma so it takes longer for energy to leak away—increase the plasma radius by a factor of two and confinement times should improve fourfold—or so scientists think.

But this factor-of-two/fourfold relationship is based strictly on observations in smaller reactors. Scientists are basically relying on a scaling law to predict what will happen in ITER. As Reinders points out, the trouble is that scaling laws, being just experimentally observed patterns or regularities, do not always work out, or the scaling just stops at a certain point.

We won’t find out whether ITER actually works until the $20 billion reactor starts operating. But don’t be surprised if a kid who is a college freshman today writes a column similar to this one 50 years from now. DW

Leland Teschler • Executive Editor lteschler@wtwhmedia.com

On Twitter @ DW_LeeTeschler