Developments to Watch
TINY CROWNS FOR A KING-SIZE CLEANUP
ENERGY DEPT. SCIENTISTS HOPE A CROWN-SHAPED molecule will help clean up 100 million gallons of highly radioactive waste left over from 50 years of nuclear weapons production and research. Much of that waste is sitting in aging tanks--some of which are now leaking.
Scientists at Pacific Northwest Laboratory in Richland, Wash., are working on a class of molecules, called crown ethers, that are made of carbon and oxygen and hold metal atoms in their centers. If crown ethers can be tailored to grab cesium and strontium ions, the most worrisome components in the stored waste, the remaining fluid could be treated and disposed of more economically as low-level waste.
Theoretical chemists David F. Feller and Mark A. Thompson are using computers to study a typical crown ether, 18-crown-6, shown here with cesium. Once they understand how 18-crown-6 holds metals, they should be able to use computer simulations to suggest crown ethers that are better suited to cesium and strontium. New parallel supercomputers, expected within a year, should shorten the time for each molecular simulation from a month to a day.EDITED BY PETER COY