It's a slow-motion horror movie: Nuclear waste leaks from underground storage shafts and seeps toward a river, where it contaminates drinking water used by millions of people. That's exactly the scenario unfolding at the Hanford Nuclear Reservation in rural Washington State.

The solution, too, sounds like a page ripped from a Hollywood screenplay: Insert two industrial-strength electrodes deep into the ground, and melt the soil—along with everything around it—into solid glass, trapping the toxic waste for thousands of years.

The U.S.