Место издания:Издательство РХТУ им. Д.И. Менделеева Москва
Первая страница:75
Последняя страница:92
Аннотация:The review of the works performed at FSUE "PO Mayak" on the problems behavior of technetium in the Purex process from the 1980s to the present. The results of studies of the interaction of Tc, hydrazine and complexones with respect to the operation of reductive extraction of plutonium, the distribution of Тс on streams of an extraction scheme of factory РТ-1 and factors of clearing target products from Tc, ways to improve cleaning, as well as management work the extraction-chemical behavior of Tc in the Purex scheme.
At present, the improvement of nuclear power is considered to be an important direction in the innovative development of the Russian economy. In this area, the most important aspects are safety
and the efficiency of the work of both the nuclear power plants themselves and the plants reprocessing SNF. When working out the processes of fuel regeneration, not only various aspects of the behavior of the main valuable macro components of SNF - uranium and plutonium, but also the properties of the fission products of uranium - should be taken into account. For processes of extraction processing of SNF, the behavior of one of the extracted fission products, technetium-99, is of decisive importance. In view of this, in the research work carried out at FSUE "PO Mayak", considerable attention was paid to the research of the role of technetium in Purex process, adopted at the RT-1 plant, and, in particular, the interaction of technetium with one of the reductants widely used in the reprocessing of SNF - hydrazine. Necessity Such work was largely due to the influence of technetium on the key operation of reductive extraction of plutonium within the first extraction cycle of the Purex scheme (Fig. 1).
The reduction of plutonium to separate it into a separate stream in this operation is achieved under the action of tetravalent uranium, and the stabilizer is hydrazine-nitrate. In addition to reextraction of neptunium and stabilization of the reduced forms of elements, a strong complexone - DTPA - is introduced into the composition of the reextraction solution. In this system in the presence of hydrazine and U (IV), technetium is reduced to the tetravalent state, but then again oxidized under the action of the medium, bypassing a series of intermediate valence forms. This process has a complex cyclic and autocatalytic character and can lead to an undesirable change in the valence forms of the target components.