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First astatine-labeled compound shipped in the U.S.
The Department of Energy’s National Isotope Development Center (NIDC) on March 31 announced the successful long-distance shipment in the United States of a biologically active compound labeled with the medical radioisotope astatine-211 (At-211). Because previous shipments have included only the “bare” isotope, the NIDC has described the development as “unleashing medical innovation.”
Tzou-Shin Ueng, William J. O’Connell
Nuclear Technology | Volume 108 | Number 1 | October 1994 | Pages 80-89
Technical Paper | Radioactive Waste Management | doi.org/10.13182/NT94-A35044
Articles are hosted by Taylor and Francis Online.
For a nuclear waste package emplacement in a potential repository in partially saturated rock, a rock rubble or backfill zone may act more as a barrier than as a pathway for diffusive release of radionuclides. We approximate the diffusive transport process using one-dimensional, one-and two-barrier geometries. The one-barrier model suffices when the effective diffusion coefficient in the first zone, the rubble, is substantially lower than that in the second zone, the host rock. For more generality, such as two zones of comparable diffusivities, or for an additional barrier zone, we model two barrier zones both of finite extent. We present solutions for three types of radionuclide mobilization at the source: a pulse transient input, a steady input rate, and a constant concentration. The algebraic series form of the solutions aids analysis of sensitivity of breakthrough times and peak release rates. For the one-zone case, dimensionless parameters allow plotting of the family of transient solutions on a single graph. Comparisons between results of one- and two-zone models and with published results for different geometries and solution methods support verification of the solutions in this study.