Fast chemical separation of Np, U, Pd and Rh from complex mixtures produced by nuclear chemical reactions

A description is given of the development and application of methods for the fast chemical separation of elements from complex mixtures of chemical nuclear reactions, elements which accumulate during heavy-ion reactions or during the splitting of heavy nuclei. The elements are separated from the product mixtures by means of liquid-liquid extraction with the centrifugal system SISAK II, which works continuously, and then examined in the liquid phase with the help of γ spectroscopy. The separation periods lie within the range of a few seconds; this specifically facilitates the study of short-lived nuclides. In the present study, the SISAK system was modified in such a way that continuous investigations of isotopes with half-lives below 1 s can also take place; this is demonstrated in test measurements with short-lived technetium isotopes. In experiments performed with the heavy-ion accelerator 'UNILAC', the methods developed were applied to the separation of neptunium and uranium from the product mixture of 136Xe + 244Pu. In experiments performed with the 'TRIGA' reactor, methods were modified or developed for the separation of palladium and rhodium. (orig./RB)