[en] The isotopic enrichment of tritium in the liquid-liquid extraction system, butylammonium/crownether was investigated using water solution of butylammonium iodide and chloroform solution of dicyclohexyl-18-crown-6. Tritium was enriched in the ammonium-crown complex which was extracted into the organic phase. Both the enthalpy and entropy changes were positive for the direction of negative free energy change. The value of entropy effect (TΔS) exceeded that of enthalpy change around room temperature. Single stage isotope separation factors obtained were 12 for n-butylammonium and 50 for tert-butylammonium as guest compounds at 55⁰C. (orig./RK)

[en] A brief overview of some of the most important applications and developments of this important phenomenon is given. (authors)

[en] For production of highly enriched targets from materials in which the desired isotope is of low natural abundance, the 180⁰ Oak Ridge Sector Isotope Separator (ORSIS) has proven particularly successful. This machine, which is an exceptionally high-resolution separator, is interfaced with an on-line computer for surveillance and control. Isotopic enhancement factors of 4*10⁵ have been achieved for targets prepared in this machine. Targets are prepared by placing the host material (typically carbon, aluminum, or nickel foils) at the receiver, 1 cm above the normal straight-line beam path. The desired ion species is steered onto the target through an electrostatic beam deflection system, thereby minimizing neutral particle contamination

[en] As a contribution to the technological development of proliferation-proof Research and Test Reactor Fuel (RERTR programme), fuel elements have been developed and designed for irradiation testing of research reactor fuel with 20% enrichment. As a part of the testing procedures, cooling channel widths and channel width profiles as a function of channel height have to be determined for different burn-up values. This has been achieved by the development and manufacturing of an installation for handling these fuel assemblies and a travelling probe based on ultrasonics for measuring the cooling channel dimensions. Some details of the measurements are given, such as method; installation; signal and data processing; results; error evaluation. (Auth.)

[en] The Paducah Tiger is an overpack designed for the international shipment of ten-ton cylinders of uranium hexafluoride in enriched form above the level of low specific acitivity. This container is designed as a Type B Package and has undergone all the tests and analyses required for a U.S. Department of Transportation Permit No. 6553. The Paducah Tiger is currently being used to ship fuel material in the USA on both truck and rail modes of transportation. In many ways, the design resembles the Super Tigersup(R), but incorporates features such as ISO corners, quick opening fasteners, and interior shock isolators that provide a system approach to the high volume of fuel shipment required in the last half of the 20th century. (author)

[en] The Oak Ridge National Laboratory (ORNL) and the US Department of Energy-Nuclear Physics Program have built a high-resolution electromagnetic isotope separator (EMIS) as a prototype for reestablishing a US-based enrichment capability for stable isotopes. ORNL has over 60 years of experience providing enriched stable isotopes and related technical services to the international accelerator target community, as well as medical, research, industrial, national security, and other communities. ORNL is investigating the combined use of electromagnetic and gas centrifuge isotope separation technologies to provide research quantities (milligram to several kilogram) of enriched stable isotopes. In preparation for implementing a larger scale production facility, a 10 mA high-resolution EMIS prototype has been built and tested. Initial testing of the device has simultaneously collected greater than 98 % enriched samples of all the molybdenum isotopes from natural abundance feedstock. (author)

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No abstract available

[en] An isotopically-enriched and purified sample of the naturally-occurring nuclide ¹⁸⁴Os has been counted in an attempt to observe α instability. No activity was observed. From an analysis of the counting data, a lower limit for the α decay half-life of ¹⁸⁴Os is deduced, with 95% confidence, to be 5.6 x 10¹³ yr. This is to be compared with the theoretical value of the half-life of ¹⁸⁴Os which, because of mass uncertainties, ranges from about 5 x 10⁹ yr to 4 x 10¹⁴ yr. (author)

[en] The Asahi chemical enrichment pilot plant with four large-scale 1-mm-diam enrichment columns has been operated using the super process since June 1987. Uranium with 3.3% enrichment was recovered in April 1988, and higher efficiencies have been observed in the pilot plant than in the bench-scale plant, which has 0.1-mm-diam enrichment columns. A possible reason is that the isotopic backmixing in the pilot plant is much smaller than in the bench-scale plant. Quantitative and statistical studies imply that both the extracolumn volume ratio and wall effect contribute to the smaller backmixing