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[en] Natural plutonium is exclusively the product of uranium neutron capture. The rate of natural plutonium production is a function of the uranium concentration and the fluence and energy spectrum of neutrons in the rock. In natural systems that have been closed to the loss and/or gain of plutonium and uranium for several half-lives of the radioactive product 239Pu - about 105 years - the two actinide elements attain a state of secular equilibrium. In such a state the Pu/U ratio is proportional to the plutonium production rate
[en] The specific activities of the naturally occurring radionuclides 238U, 232Th, and 40K were measured in rock samples from the Hetaunda area, central Nepal, using gamma spectrometry. The specific activities were found to be in the range of 17-95 Bq kg-1 for 238U, 24-260 Bq kg-1 for 232Th and 32-541 Bq kg-1 for 40K. From these data absorbed dose rates in air and annual effective doses were calculated and compared with respective data from the UNSCEAR compilation. The results from our study open the door to the safe applicability of most of the investigated materials as a cheep building material. (author)
[en] In this article is placed new scientific information about biology, ecology and spreading of Lycodine striatum bicolor within the territory of Tajikistan. Finding available in this article concerning spreading of flus snake are considered to be new. This scarce snake was discovered for the first time in Northern part of Tajikistan. This new information will enrich our notions about Reptile fauna of Tajikistan
[en] Published geochemical data from groundwater and surface water throughout the world has been compiled in order to compare the concentration of naturally occurring dissolved uranium to lithology, sampling depth, pH, Eh, HCO3, SO4 and PO4 concentrations. The sole criterion used for the selection of data from the review articles was that each article contain raw data on naturally occurring uranium concentrations relative to other groundwater chemical components. A total of 1286 chemical data entries were used in the statistical comparisons. Although this database is not exhaustive, it is likely that the ranges of uranium concentrations in the data set are representative of the ranges occurring in nature. Finally, the observed uranium concentration distributions were compared with published results of model calculations and of used nuclear fuel leach tests. Models tend to predict a wider range of concentrations than observed (particularly the high values), and the leach test concentrations tend to fall within the upper half of the observations
[en] I have compiled all of the data on isotopic abundance measurements and their variation in nature for the time period since the last General Assembly. Most of the data deals with the variations in the abundances as given by per mil deviations from some standard. As such, they are not of major interest to the Atomic Weights Commission. However, there were some measurements which are of general interest in this list
[en] Radioactivity is often a topic of intense debate; discussions mostly revolve around the benefits and dangers of nuclear energy. However, the topic reaches further - both in terms of natural occurrences and the multiple applications of radioactivity. After a summary of the history of its discovery, the first part describes its physical and biological laws. The second part deals with radioactivity as a natural phenomenon. Beginning with the question of its origin in stars long before our solar system existed, Michael Wiescher discusses the role of radioactivity in the formation of the planetary system and our Earth. He describes how the internal radioactivity of our planet determines its dynamics and makes the existence of life on the surface possible. He further describes the external and internal radioactivity to which humans are exposed and the possible effects on human development.
[de]Radioaktivität ist ein oftmals heiß debattiertes Thema; die Diskussionen drehen sich zumeist um Nutzen und Gefahren der Kernenergie. Das Thema greift jedoch weiter - sowohl in Bezug auf natürliche Vorkommen als auch die vielfachen Anwendungen von Radioaktivität. Nach summarischer Darstellung ihrer Entdeckungsgeschichte folgt im ersten Teil eine Darstellung ihrer physikalischen und biologischen Gesetzmäßigkeiten. Der zweite Teil befasst sich mit Radioaktivität als natürlicher Erscheinung. Beginnend mit der Frage nach ihrem Ursprung in Sternen lange bevor es unser Sonnensystem gab, diskutiert Michael Wiescher die Rolle der Radioaktivität bei Bildung des Planetensystems und unserer Erde. Er beschreibt, wie die innere Radioaktivität unseres Planeten seine Dynamik bestimmt und die Existenz von Leben an der Oberfläche möglich macht. Weiterhin beschreibt er die externe und interne Radioaktivität, der Menschen ausgesetzt sind und die möglichen Auswirkungen auf die menschliche Entwicklung.