The U.'s Chase Peterson offered this caution: "I admit we could be wrong. The science is good. It (the fusion experiment) is being repeated, we're told, in labs in the U.S. and overseas. But there could be a hangup, a glitch, that we don't know about.

It's possible a reactor could prove unsafe, for reasons not now foreseen, or that the energy produced could be so costly as to be economically infeasible. If the commercial research comes to such a roadblock, work will stop, Peterson promised, and no more money will be spent.