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ANS Student Conference 2025
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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.”
Dermott E. Cullen
Nuclear Science and Engineering | Volume 53 | Number 1 | January 1974 | Pages 93-106
Technical Paper | doi.org/10.13182/NSE74-A23332
Articles are hosted by Taylor and Francis Online.
An iterative method is proposed for solving the homogeneous (i.e., critical) or inhomogeneous (i.e., source) linear integral Boltzmann equation for general geometry. By using successive approximations, these two classes of problems are shown to be mathematically equivalent. For the homogeneous problem, constraints on the algorithm regarding the existence of eigenvalues and the initial approximation are investigated. The algorithm is applied to isotropically scattering slabs and spheres and is compared to previously published results as well as to an independent extrapolation method., For the inhomogeneous problem, an improvement over the normal successive collision method via the use of a Neumann series expansion is used to allow economic parametric studies. Constraints on the algorithm and methods of efficiently terminating the infinite Neumann series are investigated. The solution via the proposed method as applied to isotropically scattering slabs and spheres is provided in a compact form for a range of multiplication factors and optical dimensions. The shape of the scalar flux distribution is explained., Extensions of the method to more complex problems are outlined; in particular, the solution to an energy-dependent problem in general geometry is obtained and the implications of the results are discussed.