Betting on Better Storage
While nuclear waste would be easier to handle in 50 or 100 years, it would still require isolation for several hundred thousand years. But there is every reason to expect that storage technology will improve in the next century. When we decide to permanently dispose of the waste, either after reprocessing or without reprocessing, we may be smarter at metallurgy, geology, and geochemistry than we are now.
Today, the basic technology at Yucca is a stainless-steel material called alloy 22, covered with an umbrella of titanium – a “drip shield” against water percolating down through the tunnel roof. That could look as primitive in 100 years as the Wright brothers’ 1903 Flyer looks to us in 2004. Or it might simply be obsolete. Space-launch technology could become as reliable as jet airplanes are today, giving us a nearly foolproof way to throw waste into solar orbit. The mysteries of geochemistry might be as transparent as the human genetic code is becoming, which would mean we could say with confidence what kind of package would keep the waste encased for the next few hundred thousand years.
Or there might be easier ways to process the waste. For example, particle accelerators, routinely used to make medical isotopes, could provide a means to make the waste more benign. The principle has already been demonstrated experimentally: firing subatomic particles at high-level radioactive waste can change long-lived radioactive materials to short-lived ones. Richard A. Meserve, a former chairman of the U.S. Nuclear Regulatory Commission and now the chairman of a National Academy of Sciences panel on nuclear waste, says this technology, known as transmutation, might become more practical in 100 years. The technology of accelerators has advanced in the last few years, he says, and it is a good bet that it will continue to do so.
Some alternative storage technologies may need only a few more years of research and development. One is ceramic packaging. Ceramics have good resistance to radiation and heat, and they don’t rust. At the moment, nobody casts ceramics big enough to hold fuel assemblies, which are typically about four meters long. But there is no theoretical limit to the sizes of ceramics; there has simply been no economic incentive to make giant ones. Nor will there be, until the only likely customer for them, the Energy Department, decides that the metal it is shopping for now isn’t up to the job.
Another alternative calls for mixing waste with ceramics or minerals to form a rocklike material comprising about 20 percent waste. The waste would be chemically bound up in stable materials that are not prone to react with water. With a few decades’ grace time, engineers could build samples and test them in harsh environments. But even though the idea has been around for more than 10 years, no one has put serious research money into it, since its only possible American customer, the Energy Department, has been committed to Yucca.
That situation shows no sign of change. The Energy Department, following Congress’s orders, has so far declined to consider alternatives. Man-Sung Yim, a nuclear researcher at North Carolina State University in Raleigh, argues that some of these technologies are already mature but have been shoved aside in the Energy Department’s rush, possibly futile, to open Yucca. “My reading at this point is, people working at the Yucca Mountain project office do not really want to change the design. The more change you bring in, the more delayed the processes,” Yim says. “It’s a pity, because we could make it better.”