The Union of Concerned Scientists has proposed that safe, secure nuclear power requires smaller plants that simply cannot melt down, says Ed Lyman, a physicist and expert on nuclear plant design.

Generation III-plus includes a handful of high-tech plant designs, many of which still await regulatory approval. Others, like France-based Areva’s Evolutionary Power Reactor (EPR) and Westinghouse’s AP1000 (both are pressurized water reactors) are already under construction, and they are designed to withstand exactly the crisis the 40-year-old Japanese reactors are failing to deal with

Generation IV reactors explore advanced cooling systems and other technologies that could make nuclear plants even more productive and safer, although not for another 20 years or so.

In the meantime, engineers are experimenting with all kinds of imagined nuclear plant paradigms, from floating nuclear power stations that are immune to seismic calamity to subterranean systems that are already safely buried deep beneath the ground.