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Tritiated water (HTO), a ubiquitous byproduct of the nuclear industry, is a radioactive contaminant of major concern for environmental authorities. Although understanding spatiotemporal heterogeneity of airborne HTO vapor holds great importance for radiological safety as well as diagnosing a reactor’s status, comprehensive HTO distribution dynamics inside nuclear facilities has not been studied routinely yet due to a lack of appropriate monitoring techniques. For current systems, it is difficult to simultaneously achieve high representativeness, sensitivity, and spatial resolution. Here, we developed a passive monitoring scheme, including a newly designed passive sampler and a tailored analytical protocol for the first comprehensive 3D distribution characterization of HTO inside a nuclear reactor facility. The technique enables linear sampling in any environment at a one-day resolution and simultaneous preparation of hundreds of samples within 1 day. Validation experiments confirmed the method’s good metrological properties and sensitivity to the HTO’s spatial dynamics. The air in TU Wien’s reactor hall exhibits a range of 3H concentrations from 75-946 mBq m-3 in the entire 3D matrix. The HTO release rate estimated by the mass-balance model (3199 ± 306 Bq h-1) matches the theoretical calculation (2947 ± 254 Bq h-1), suggesting evaporation as the dominant HTO source in the hall. The proposed method provides reliable and quality-controlled 3D monitoring at low cost, which can be adopted not only for HTO and may also inspire monitoring schemes of other indoor pollutants.

In 1910, Carl Auer von Welsbach noted that he had made an observation of a radioactive substance inducing radioactivity to an inactive substance. From today's point of view, this could have been the first observation of neutron activation. Herein, we present new insights into our investigation of this ‘mysterious observation’ as Auer von Welsbach termed it. We believe that one of the activated objects was a platinum–iridium crucible. The dominating activation product of the crucible could have been iridium-194. We have discovered several platinum crucibles from Auer's heritage and investigated them by gamma-spectrometry and, one of them, by SEM/EDX. In the EDX investigations, however, no iridium was found in the most promising crucible. Hence this particular crucible was probably not the activated object. In any case, gamma-ray spectrometry revealed very low but detectable amounts of natural radionuclides. This indicated that these crucibles were used by Auer von Welsbach for his radioactive work and that these crucibles were bought prior to World War I. Hence Auer von Welsbach somehow managed to save these crucibles from the noble metal collections during the war. Auer's 1910 publication carried the suffix ‘Part I’, however, Part II was thought to be lost. In our recent work, however, we rediscovered a hand-written manuscript of Part II, in which the peculiar observation is mentioned vaguely. Lastly, we converted Auer's uranium standard into becquerels. Based on this conversion, we estimated that Auer von Welsbach observed an 194Ir activity of the crucible of 500 kBq. It is further estimated that a (thermal) neutron flux density of approximately 8E+4 cm−2 s−1 was needed to activate the crucible in a way to meet Auer's description. This is an Accepted Manuscript of an article published by Taylor & Francis in Interdisciplinary Science Reviews on 2017-01-09, available online: http://www.tandfonline.com/doi/full/10.1080/03080188.2016.1251731.