A standard human way of dealing with something that you want to get rid of is to dig a hole and bury it. This has been a popular proposal of disposing of spent nuclear fuel and many countries that use nuclear power either have or are working on such repositories. The authorities in these countries claim that such repositories can be safe, economical and protect the environment but a large part of the public remains highly skeptical.
Proposed repositories are general one thousand feet deep or deeper. The rock should be solid and dense. Stability is one of the most important factors. That means that there should not be any nearby volcanism. There should not be any geological faults in the area. A second very important factor is that there should be very limited movement of ground water through the rock strata to prevent threats to the water table. Finally, the repository should be as far from human habitation and land use as possible.
Once the repository site has been selected and the tunnels dug, there will likely be additional preparation in the form of additional sealing of the walls of the tunnels. Salt mines have been a popular choice for conversion to nuclear fuel repositories because many tunnels and large areas have been excavated. Locations with a granite matrix are also popular choices.
Concrete cylinders containing spent nuclear fuel rods would be transported to the repository site from the spent fuel pools, a process that has its own problems. The cylinders would be lowered into the repositories and arranged in a configuration that leaves room between the cylinders for heat dissipation. Eventually, when the repository is full, the access tunnel would be sealed. There have been discussions about how to leave a maker that would be comprehensible for thousands of years so that future societies would know that the site was dangerous.
Belgium, Canada, Finland, France, Japan, Korea, Sweden, Switzerland, and the USA have created major underground laboratories to test the feasibility of deep geological repositories for spent nuclear fuel. Argentina, Belgium, Canada, China, Finland, France, Germany, Japan, Korea, Sweden, Switzerland, United Kingdom and the USA all have repositories filled and closed, currently operating, being planned or canceled.
Whenever such a repository is proposed, after the serious effort to verify that all the technical details have been reviewed and all technical concerns have been satisfied, the hard work of selling the location to the public begins. Politics becomes the most important factor. On the positive side, there may be commercial interests who play down or even try to hide any potential problems. On the negative side, there may be environmental groups who over emphasize potential problems.
Unfortunately, we do not have the luxury of kicking this can down the road. Current estimates are that the world’s spent nuclear fuel pools will all be full of spent fuel within 5 years at the current rate of nuclear fuel use. Deep repositories are the most realistic of the proposals for permanent disposal, despite technical and political problems. Time is running out to implement a disposal solution.
Planned repository in Finland:
