Optimizing laboratory-based radon flux measurements for sediments. (July 2016)

• Record Type: Journal Article
• Authors: Chanyotha, Supitcha; Kranrod, Chutima; Kritsananuwat, Rawiwan; Lane-Smith, Derek; Burnett, William C.
• Is Part Of: Journal of environmental radioactivity. Volume 158/159(2016:Aug.)
• Page Start: 47
• Page End: 55
• Publication Date: 2016-07
• Subjects: Radon -- Fluxes -- Methods -- Sediments; Radioactivity -- Periodicals; Radiation, Background -- Periodicals; Radioecology -- Periodicals; Radioactive pollution -- Periodicals; Environmental Pollutants -- Periodicals; Radioactive Pollutants -- Periodicals; Radioactivity -- Periodicals; Radioécologie -- Périodiques; Pollution radioactive -- Périodiques; Fond de rayonnement -- Périodiques; 539.752
• DOI: 10.1016/j.jenvrad.2016.03.023
• Languages: English
• ISSNs: 0265-931X

Abstract

Abstract: Radon flux via diffusion from sediments and other materials may be determined in the laboratory by circulating air through the sample and a radon detector in a closed loop. However, this approach is complicated by the necessity of having to determine the total air volume in the system and accounting for any small air leaks that can arise if using extended measurement periods. We designed a simple open-loop configuration that includes a measured mass of wet sediment and water inside a gas-tight reaction flask connected to a drying system and a radon-in-air analyzer. Ambient air flows through two charcoal columns before entering the reaction vessel to eliminate incoming radon. After traveling through the reaction flask, the air passes the drier and the radon analyzer and is then vented. After some time, the radon activity will reach a steady state depending upon the airflow rate. With this approach, the radon flux via diffusion is simply the product of the steady-state radon activity (Bq/m 3 ) multiplied by the airflow rate (mL/min). We demonstrated that this setup could produce good results for materials that produce relatively high radon fluxes. We also show that a modified closed system approach, including radon removal of the incoming air by charcoal filtration in a bypass, can produce very good results including samples with very low emission rates. Highlights: We developed a simple open-loop system for laboratory evaluation of radon fluxes. Charcoal scrubbing of the incoming air improves the performance. Open loop simplifies flux calculation: (steady-state radon) × (airflow rate). A modified close loop approach useful for low flux materials.