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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.”
C. B. Mills, G. I. Bell
Nuclear Science and Engineering | Volume 12 | Number 4 | April 1962 | Pages 469-473
Technical Paper | doi.org/10.13182/NSE62-A26093
Articles are hosted by Taylor and Francis Online.
In this paper we present calculated critical masses of homogeneous water-moderated assemblies containing low enrichment uranium. The calculations were made using the multigroup DSN code with eighteen energy groups. Effective absorption cross sections for U238 were computed with the “infinite mass” and “narrow resonance” approximations. The calculations have been compared with various experiments and rather good agreement was found. The results are presented as a parametric survey for U235/U atom ratios from 0.014 to 0.300 and for all H/U235 ratios for which criticality is possible. The decrease in critical radius with an infinite water reflector is also shown. We find that a bare homogeneous system with U235/U < 0.010 cannot be made critical at any H/U235 ratio.
