Nucleotidings

         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.

          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.

          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.

          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.