U.S. Considers How to Bury Nuclear Waste
Figuring out where to store spent radioactive fuel from nuclear power plants is a problem that won't go away for thousands of years. But countries such as the U.S. considering long-term storage have a few possible solutions.
A U.S. Department of Energy commission has been studying sites for long-term nuclear waste storage, including salt deposits, shale rock and granite rock. Each has its own pros and cons, according to New Scientist. Whether one or all end up being used, they represent necessary steps for any country that wants to existing or future nuclear power. [Nuclear Power's Next Fuel Is a Blast from the Past ]
Salt deposits up to 0.6 miles (1 km) thick can entomb nuclear waste because the salt slowly flows in to seal it off. Such storage for waste from creating nuclear weapons already exists near Carlsbad, New Mexico. The downside is that small amounts of water in the salt could move over time and carry radioactive materials with them.
Shale rock can trap radioactivity, is self-sealing and exists in many regions of the U.S. with low risks of earthquakes. Some uncertainty exists because hard, compacted shale does not self-seal, but France has plans for a shale storage site to open in 2025.
Granite rock offers strong, stable foundations, but has a brittle nature that would require metal reinforcement. Any fractures in the rock could allow nuclear waste to escape and contaminate any nearby underground water aquifers.
Still, the U.S. previously stored spent fuel in an underground lab built within granite in Nevada. Finland and Sweden have plans to open such nuclear waste storage sites in 2020, and several other countries have also begun looking into the possibility.
A more unusual storage method would use new drilling technology to create boreholes as deep as 3 miles (5 km) down. Such storage would prevent any possible contamination of water usable by humans, but remains more of a concept than tested reality.
Some countries such as France, the UK, Russia, India and Japan prefer to reuse some spent fuel by reprocessing it to obtain unused uranium and plutonium. But the same extracted plutonium can lead to nuclear weapons.
Consideration of long-term solutions for nuclear waste may get a shot of urgency in the wake of Japan's Fukushima nuclear plant disaster stemming from its recent earthquake and tsunami . Radioactive waste in temporary underwater storage at the Japanese nuclear plant was exposed once the water boiled off due to overheating nuclear reactors.