ANN ARBOR---An international research team, led by University of Michigan scientists, has found that gadolinium zirconate is much more resistant to radiation than the ceramic currently being considered for disposal of plutonium from dismantled nuclear weapons in the United States. This highly durable material---a zirconate pyrochlore---is calculated to resist radiation damage for up to 30 million years.
The research team performed a systematic study of the radiation resistance of gadolinium titanate, the ceramic currently proposed for plutonium immobilization, and zirconate compositions. Results indicate that the titanate will be damaged by radiation in less than 1,000 years. The zirconate will not sustain damage for periods up to 30 million years. Considering that plutonium is an environmental contaminant with a radioactive half-life of 24,500 years, the multi-million-year calculation of the zirconate's durability makes it a leading candidate for the immobilization of plutonium.
"This is a significant scientific discovery with major environmental impact for future generations," said Dr. Yok Chen, Program Manager in the Office of Basic Energy Sciences at the U.S. Department of Energy, which funded this research at the University of Michigan and Pacific Northwest National Laboratory (PNNL).
Rodney Ewing, professor of nuclear engineering and radiological sciences at the U-M College of Engineering, and William Weber, a senior staff scientist at PNNL, led the team of researchers that included scientists at the Australian Nuclear Science and Technology Organization and the Indira Gandhi Centre for Atomic Research in India.
The team's findings were first published in the December 1999 Journal of Materials Research (JMR). This past week, another international team of researchers at Los Alamos National Laboratory, working independently from the U-M team, announced similar results with an erbium zirconate ceramic.