Development of a Novel Passive Monitoring Technique to Showcase the 3D Distribution of Tritiated Water (HTO) Vapor in Indoor Air of a Nuclear Facility

• Published in: Environmental science & technology Vol. 57; no. 48; pp. 20024 - 20033
• Main Authors: Feng, Bin, Ibesich, Martin, Hainz, Dieter, Waidhofer, Daniel, Veit-Öller, Monika, Trunner, Clemens, Stummer, Thomas, Foster, Michaela, Nemetz, Markus, Welch, Jan M, Villa, Mario, Sterba, Johannes H, Musilek, Andreas, Renz, Franz, Steinhauser, Georg
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 05.12.2023
• Subjects: Air Pollutants, Radioactive - analysis; Air Pollution, Indoor - analysis; Contaminants; Evaporation; Gases; Heterogeneity; Indoor air pollution; Indoor environments; Mass balance; Monitoring; Nuclear facilities; Nuclear reactors; Nuclear safety; Radiation Monitoring - methods; Radioactive contaminants; Radioactive contamination; Radioactive pollution; Reactors; Samplers; Sensitivity; Spatial discrimination; Spatial resolution; Tritium - analysis; Vapors; Water; indoor air pollution; tritium; passive sampler; 3D spatial distribution; environmental radioactivity; nuclear industry
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/acs.est.3c05783

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 H concentrations from 75-946 mBq m in the entire 3D matrix. The HTO release rate estimated by the mass-balance model (3199 ± 306 Bq h ) matches the theoretical calculation (2947 ± 254 Bq h ), 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.