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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.”
M. J. Ades, K. L. Peddicord
Nuclear Science and Engineering | Volume 81 | Number 4 | August 1982 | Pages 563-569
Technical Note | doi.org/10.13182/NSE82-A21448
Articles are hosted by Taylor and Francis Online.
An analytical method is presented to estimate the effective thermal conductivity of sphere-pac fuel during restructuring. This method is based on a unit cell model in which a sintering model is used to describe the extent of restructuring occurring between the fuel particles. As a result of sintering, a “neck” is formed between the fuel spheres. The effective conductivity of the sphere-pac bed can then be evaluated in terms of restructuring, i.e., as a function of temperature and necking between the fuel spheres. The effects of other relevant parameters such as the gas pressure in the sphere-pac pin and fission gas release are also included in the model Furthermore, a thermal conductivity criterion is used to determine the matching conductivity boundary, which is defined as the outer radial boundary where fuel restructuring is completed. Fuel restructuring is of particular importance in sphere-pac fuel because of its controlling effect on the temperature distribution. By knowing the effective conductivity, the temperature distribution of the fuel, both in its initial configuration and during restructuring, can be determined. Using the model, the temperature distribution as well as the extent of restructuring can be calculated. This model can be incorporated into computer codes to predict the overall thermal and mechanical performance of sphere-pac fuel pins.