Of all the schemes proposed for the disposal of radioactive wastes such as the spent fuel from nuclear power reactors, I think the best suggestion so far is to drill a deep hole, insert the waste and fill in the hole. A new company is exploring this idea.
Deep Isolation is a start-up company based in Berkley, California. The company was started to adapt new drilling technologies to make the permanent disposal of spent nuclear fuel cheaper and safer than other approaches that have been proposed.
Although deep drilling for nuclear disposal has been researched for years, DI intends to take advantage of recently developed deep drilling techniques used for fracking to create two-mile-long horizontal tunnels a mile underground for storing spent nuclear fuel rods. Other deep drilling proposals for storing spent nuclear fuel were based on drilling vertical holes up to five miles deep.
Following the cancellation of the geological repository under Yucca Mountain in Nevada in 2009, the President’s Blue Ribbon Commission on America’s Nuclear Future considered several alternate proposals for the permanent disposal of spent nuclear fuel including the idea of deep drilling holes to hold the waste. They recommended that disposal options should be tailored to the waste and the need. One of the important suggestions that the Commission made was that all the major stakeholders in and around a proposed site should consent to the storage of spent nuclear fuel in their area.
A great deal of research and development has gone into the drilling of deep holes for the purpose of fracking to release oil and gas in shale formations. Drill rigs have been developed that can drill horizontal “stringers” or shafts off in different direction from the primary hole. The horizontal shafts can extend from miles.
The DI process will be simple and based on existing drilling techniques. A shaft will be drilled a mile or more into the Earth and then the spent nuclear fuel rods will be inserted into the hole. After the fuel has been place in the shaft, the rest of the shaft is filled with crushed rock, asphalt and concrete. After the surface has been landscaped, there will be no sign that anything is buried there. It would take millions of years of geological processes to bring up anything buried miles underground.
While earlier proposals were based on drilling vertical holes to hold the waste, the DI proposal is based on horizontal shafts which are actually cheaper and easier to drill. The proposed shafts will be able to accept spent nuclear fuel assemblies that are a foot in diameter and fourteen feet long. It should be possible to drill one of the disposal shafts in a couple of weeks at most.
One major benefit of drilling deep holes for spent nuclear fuel disposal is that fact that it does not matter where they are located in the U.S. With billions of tons of rock above any such storage shafts, the type overlying rock formation don’t matter. The buried waste will be well below the water table in porous rock. Climate and human activities will have no effect on the buried waste. This means that spent nuclear fuel can be disposed of near the site of nuclear reactors no matter where they are.
The U.S. has approximately eighty thousand tons of spent nuclear fuel which would not require a large number of holes to dispose of. Three hundred DI shafts would be able to hold all the spent fuel that currently exists in the U.S. The oil and gas industry has already drilled over fifty thousand fracking wells in the U.S. so it would be easy to drill three hundred disposal shafts.
The biggest impediment to the DI proposal is the fact that current federal law prohibits the Department of Energy from employing any privately-developed geological disposal system. In order for DI to proceed, the rules and regulations for the permanent geological disposal of spent nuclear fuel will have to be changed.