Despite the recent extended shutdown of ORNL's calutrons, inventories of enriched stable isotopes from previous operations enabled the Laboratory's Isotope Enrichment Facility to distribute isotope products at a normal pace. However, new contracts to supply these isotopes to a variety of customers, coupled with the growing use of radioisotopes derived from them and concern over foreign supplies, made it necessary to restart the calutrons and replenish inventories.
"We feel like the calutrons are a national resource and it's good to see them going again," said Isotope Program Manager Emory Collins, of ORNL's Chemical Technology Division. In fact, ORNL's calutrons are among the few in the world that are operational, and are the only ones in the Western World producing stable isotopes. Because of their value to research, DOE adopted a National Isotope Strategy in 1994 that promotes production of nonprofitable amounts of these rare isotopes. At the same time, Collins said, producing larger volumes of isotopes should bring down prices.
Collins said that the calutrons will produce enriched precursors to important medical radioisotopes including thallium-203, precursor to thallium-201, which is widely used for heart scans; zinc-68, the precursor to gallium-67, used for tumor imaging; and strontium-88, the source of a product, called "Metastron," that has proven effective as a therapeutic treatment for patients with cancer-induced bone pain. The active agent in Metastron, developed at ORNL and recently licensed by Amersham Corporation, is the radioisotope strontium-89 chloride, which is derived from strontium-88.
ORNL's calutrons are located at the Oak Ridge Y-12 Plant, where more than 1100 of the machines, initially designed by Nobel Laureate E. O. Lawrence, produced uranium-235 in the 1940s for the atom bomb project. The leap in technology required to design, construct, and operate the massive Oak Ridge calutron facility was comparable with that required to put a man on the moon, and it was accomplished in a fraction of the time. However, because more efficient uranium production methods were later developed, the numbers of calutrons dwindled to the 20 that now operate at Oak Ridge.
Calutrons are slow and expensive to run. Despite their drawbacks, calutrons can simultaneously produce a variety of high-quality enriched stable isotopes - 225 isotopes from 55 chemical elements - that are well-suited for irradiation to produce radioisotopes. Products of these enriched stable isotope are used for purposes ranging from medicine to materials research to quality inspection.
ORNL, one of DOE's multiprogram research laboratories, is managed by Martin Marietta Energy Systems, a Lockheed Martin company, which also manages the Oak Ridge Y-12 Plant and the Oak Ridge K-25 Site.