An improved annular centrifugal contactor has been developed for solvent extraction reprocessing of spent nuclear reactor fuel. The design is an extension of a contactor developed several years ago at Argonne National Laboratory. Its distinguishing features are high throughput, high stage efficiency and the ability to handle a broad range of aqueous-to-organic phase flow ratios and density ratios. Direct coupling of the mixing and separating rotor to a motorized spindle simplifies the design and makes the contactor particularly suitable for remote maintenance. A unit that is critically safe by geometry is under test and a larger unit is being fabricated. Multi-stage miniature contactors operating on the annular mixing principle are being used for laboratory flow sheet studies. 8 figures.

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The rising cost, uncertain future supply, and environmental problems associated with energy sources have resulted in serious investigation of energy sources that have not previously been considered economically and technically feasible. One such source involves low-head hydroelectric generation. The Department of Energy has funded several feasibility studies for the installation of hydroelectric generators at existing low-head dams. Such a feasibility study for the Archusa Creek Dam near Quitman, Mississippi, is described. The study indicates that there are no apparent technical dificulties to prevent such a project and that a suitable turbine-generator could be obtained. The study further indicates that the project should be economically feasible for the Pat Harrison Waterway District (owners of the dam and lake) to construct if arrangements could be completed for interconnecting with the local utility and selling the energy to the utility. The utility (Mississippi Power Company) has expressed interest in such an arrangement.

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A study was conducted to determine the seismic effects on the containment structure of a proposed underground reactor facility. Simplified and often inadequate building code equivalent static design procedures frequently used for conventional reactor systems are not adequate for partially buried or fully buried reactor systems. A sophisticated dynamic analysis which can consider soilstructure interaction effects resulting from both seismic displacements and forces must be employed. One such approach would be to use the finite element method. The results of using such an approach to consider both the static overburden and dynamic earthquake effects on the containment structure of the proposed underground reactor facility are presented. (auth)

The purpose of the project described is to study fission product decay heating rates, with emphasis on short decay times. Isothermal calorimetry is used to perform benchmark experiments for decay times between 20 seconds and 2000 seconds with an absolute accuracy of better than 5 percent. Experiments are being done with $sup 235$U and will be done eventually with $sup 239$Pu. Thermal neutron spectra are used for the irradiations. The project was initiated in July 1974. Final results for $sup 235$U are expected by 6-30-76, and for $sup 239$Pu by 1-1-77. Final reports for each task will follow the final data by 3 months. The work done to date is described together with the status of the final experimental configuration.