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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.”
Vojislav Banjac, A. Sharif Heger
Nuclear Technology | Volume 108 | Number 1 | October 1994 | Pages 126-136
Technical Paper | Radiation Protection | doi.org/10.13182/NT94-A35048
Articles are hosted by Taylor and Francis Online.
A mass optimization study of the total shield mass requirementsfor gamma attenuation for a space nuclear power system is carried out. The reference system is a nuclear electric power-generating reactor with a 1016 γ/s source term and reference dimensions based on the Russian TOPAZ-II. Seven potential shield materials are analyzed, and the total gamma shield masses are presented for a desired dose equivalent of 5.0 mrem/h at the end of the shield. A three-dimensional shielding code, QAD-CGGP, is used to model the reactor and the truncated cone shield. Gamma energies of 0.5,1.0, and 2.0 MeV are analyzed, and the required shield masses are normalized to the lowest value, giving a “mass index.” Comparison of the required masses and mass indices for both direct radiation and buildup dose is presented. For all three gamma energies, depleted uranium has a mass index of 1.0 and provides the required shielding with the lowest mass requirement. Mass indices between 1.2 and 1.7 are characteristic of tungsten and lead, making them potential substitutes for depleted uranium in the case of smaller reactor power levels.