As we discussed in a previous post, one of the standard solutions for getting rid of things that we do not want is to bury them. While nuclear waste depositories for the most part utilize existing exhausted mines, an alternative is to drill extremely deep holes into the earth to dispose of nuclear waste.
Another option for burial of high-level radioactive waste such as spent nuclear fuel rods is burial at sea where it would not be disturbed by geological processes or human activity.
There are hundreds of thousands of tons of depleted uranium hexafluoride in temporary storage in the United States. A very small amount has been used in the manufacture of such things as tank armor, armor piercing artillery, shields for industrial radioactive materials and other applications.
When nuclear fuel has been burned in a reactor and there is no permanent disposal site, there is an alternative to storing the spent fuel rods after they have cooled off in a pool of water for at least a year. Spent fuel rods can be stored in steel cylinders in what is called ‘dry cask’ storage.
While the United States has been struggling with the Yucca Mountain site for nuclear waste disposal, other countries have been operating or planning repositories.
Sweden has been operating a repository since 1988. Finland has one that has been in operation since 1992 and another that opened in 1998. Germany operated one that closed in 1995 and another that closed in 1998. The US has been operating a repository for transuranic wastes since 1999.
In 1957, the National Academy of Sciences of the United States recommended long term burial as the best solution for permanent disposal of nuclear wastes. Starting in 1978, the U.S. Department of Energy (DOE) has been studying Yucca Mountain in Nevada as a possible site for the first long term geological repository for U.S. The U.S.
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.
There are a number of different proposals for permanent disposal of spent nuclear fuel. Here are summaries of some possible techniques.
Nuclear reactors burn nuclear fuel to generate electricity. Most reactors burn uranium oxide in the form of ceramic pellets in long tubes. The tubes comprise the core of the reactor where the fission reaction takes place. The zirconium cladding of the fuel rod tends to migrate into the center of the pellets while the lower boiling point fission products move to the edge of the pellet. Small bubbles form in the pellet which fill with cesium-137 from decaying xenon.
I have already touched on radioactive waste in several earlier posts but I wanted to treat the subject in a more systematic and thorough way. I am going to start with a breakdown of radioactive wastes into six categories.
