Ceramics show promise for storage of nuclear waste

JOM, Oct 2000

The Department of Energy's Los Alamos National Laboratory has demonstrated that certain ceramic materials with structures similar to fluorite crystals hold up well to radiation damage. Internal radiation can cause radioactive host materials to swell or crack, making the stored waste unstable and susceptible to leaching, but the atoms of these ceramic materials can shift to accommodate defects caused by radiation damage.

"Fluorite-type ceramic materials show promise as safe, radiation-proof materials and should be further developed for containing nuclear wastes," Kurt Sickafus,head of the team developing the materials, wrote in a study published in the August 4th issue of Science.

To test their theory, researchers examined pyrochlore and fluorite structures. Pyrochlore is a brownish-black mineral found in granitic rocks and pegmatites, coarse-grained igneous rocks. Fluorite is a bluish-green mineral used in the smelting of iron and in the ceramic and chemical industries.

"Preliminary radiation damage experiments substantiate the prediction that fluorites are inherently more radiation resistant than pyrochlores. These results may permit the chemical durability and radiation tolerance of potential hosts for actinides and radioactive wastes to be tailored," the researchers wrote.

Researchers also discovered that radiation resistance increases when large metallic ions such as zirconia are included in the compound's atomic structure.