New information about the U/Th sediment contamination provided by the neutron-induced fission activation analysis

Abstract

The possibility to obtain new information about the U/Th contamination using the patterns of the fission track micromapping is put into evidence. For the investigated samples, bed load sediments sampled from Danube river and Delta, fission track micromappings were obtained using the neutron-induced fission of the U and Th elements and the track registration of their fission fragments in muscovite track detectors. Utilising the optical microscopy, these micromappings were used both for U and Th content measurements and for studies of U/Th atom distributions. Considering the “track micromapping pattern” as a characteristic of the U/Th atom distribution in the analysed sample, and basing on the micromapping patterns that were previously obtained for the samples contaminated in the specific conditions, the authors were able to establish: (1) the presence of the contamination of the sediments in spite of the fact that the U/Th concentration values did not exceed the natural background values, (2) the solubility of the U/Th chemical compounds in the initial waste and (3) the presence of a succession of U/Th contaminations as well as the presence of the transported contamination.