Actinides nuclides, preparation

In recognition of these needs, a list of recommended half-life values for a number of actinide nuclides useful as standards for nuclear-data measurements was prepared several years ago [VAN83]. This list included both total and partial half-life data for 11 such nuclides - the important isotopes of U, Np and Pu, as well as 252Cf. Subsequently, these data were revised [REI85a] to incorporate the results of new measurements, some of them from the work of the CRP. These data are given in a recent paper [REI85b], as well as in the final report of the IAEA CRP. 

The separation of actinides has been studied for various purposes in Japan Atomic Energy Research Institute (JAERI). The works which have been carried out so far, are classified into four categories preparation studies of actinides nuclides, separation chemistry for chemical analysis, separation of actinides from radioactive waste, and studies on reprocessing of spent nuclear fuels. The present work is to review studies of actinide separation performed in JAERI, emphasizing the need of the separation for the main purpose of individual. Concern is focussed on the separation of transuranium elements and studies on thorium and uranium are put aside. 

Since 1958, more than 20 nuclides of actinides ranging from neptunium to einsteinium were identified and prepared for tracer studies. From neutron-irradiated uranium samples 2 9Np was adjusted to the pentavalent state and separated by TBP extraction from perchloric acid media. Plutonium-239 was separated by TBP extraction from nitric acid solution followed by anion exchange in a system of Dowex-1 resin and nitric acid. Neptunium-237 was separated from a spent fuel solution of JRR-1 (Japan Research Reactor -1) using anion exchange and TBP extraction. The TBP extraction in the hydrochloric acid medium is a simple and effective technique to purify neptunium from plutonium contamination. On the other hand, both anion exchange and solvent extraction with HDEHP could be used to separate tracer scale plutonium from irradiated neptunium targets. 

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