March 18, 2014
Shale Formations Could Be Used To Safely Store Nuclear Waste
redOrbit Staff & Wire Reports - Your Universe Online
The same type of clay-rich sedimentary rocks that are responsible for the current natural gas boom in the US could also be used to dispose of radioactive waste originating from nuclear power plants, according to new research presented during a scientific conference on Monday.
Speaking at the 247th National Meeting & Exposition of the American Chemical Society (ACS), Dr. Chris Neuzil of the US Geological Survey (USGS) explained that the unique properties of shale makes it ideal for storing the potentially hazardous spent fuel for several thousands of years.
According to Neuzil, approximately 77,000 tons of spent nuclear fuel are currently being kept in above-ground storage facilities, and it will pose a threat for tens to hundreds of thousands of years, if not longer. However, shale rock formations are nearly impermeable, making them an ideal long-term solution for nuclear waste storage since water will not flow through them and become contaminated by the accumulated waste.
“Surface storage for that length of time requires maintenance and security. Hoping for stable societies that can continue to provide those things for millennia is not a good idea,” he explained in a statement, adding that above-ground facilities can be threatened by natural disasters such as the 2011 tsunami that damaged cooling pumps in the Fukushima Daiichi nuclear power plant.
Neuzil has emphasized the importance of finding a long-term nuclear waste storage solution since the American government abandoned plans to build a facility at Nevada’s Yucca Mountain back in 2009. Such a site is necessary because nuclear fuel still produces heat and radiation, even after its usefulness has come to an end.
In a nuclear power plant, the heat produced as radioactive elements such as plutonium and uranium decay is typically used to make steam and spinning turbines to generate electricity. In temporary pool storages, water absorbs heat and radiation, and after spent fuel is cooled in pools over the course of several years, it can then be relocated to dry storage in a sealed metal cask where radiation is blocked by concrete and steel.
However, this is a temporary solution, whereas shale could provide a long-term answer to the problem. Belgium, France and Switzerland have already devised plants to store nuclear waste using shale repositories. Neuzil has proposed that the US also explore the possibility of storing these hazardous materials underground in layers of clay-rich rock. In fact, US and Canadian officials are reportedly exploring a possible site located in Ontario.
The types of shale formations being investigated by Neuzil and his colleagues are said to be far more watertight than those where a road cuts into a hillside, and experiments have demonstrated that water moves extremely slowly through them, if at all. In addition, he said that future glaciations are unlikely to threaten the waste storage locations, as most of the candidate shale formations have already emerged unscathed from such events.