Identification of airborne radioactive spatial patterns in Europe – Feasibility study using Beryllium-7

Abstract

The present study proposes a methodology to identify spatial patterns in airborne radioactive particles in Europe. The methodology is based on transforming the activity concentrations in the set of stations for each month (monthly index), due to the tightly spaced sampling intervals (daily to monthly), in combination with hierarchical and non-hierarchical clustering approaches, due to the lack of a priori knowledge of the number of clusters to be created. Three different hierarchical cluster methodologies are explored to set the optimal number of clusters necessary to initialize the non-hierarchical one (k-means). To evaluate this methodology, cosmogenic beryllium-7 ((7)Be) data, collected between 2007 and 2010 at 19 sampling stations in European Union (EU) countries and stored in the Radioactivity Environmental Monitoring (REM) database, are used. This methodology yields a solution with three distinguishable clusters (south, central and north), each with a different evolution of the (7)Be monthly index. Clear differences between monthly indices are shown in both intensity and time trends, following a latitudinal distribution of the sampling stations. This cluster result is evaluated performing ANOVA analysis, considering the original (7)Be activity concentrations grouped in each cluster. The statistical results (among clusters and sampling stations within clusters) confirm the spatial distribution of (7)Be in Europe, and, hence, reinforce the use of this methodology. Finally, the impact of tropopause height on this grouping is successfully tested, suggesting its influence on the spatial distribution of (7)Be in Europe. For airborne radioactive particles the analysis gave valuable results that improve knowledge of these atmospheric compounds in Europe. Hence, this work addresses a methodology to a grouping of airborne sampling stations, 1) allowing a better understanding of the distribution of (7)Be activity concentrations in the EU, and 2) serving as a basis for further investigation of the heterogeneity of airborne radioactivity concentrations in Europe.

Beryllium-7 surface concentration extremes in Europe

“…In this case, the separation line would be closer to 50 °N which arose as a dividing latitude in the comparison of the annual cycles. These results agree very well with the three regions of distinct Be-7 concentration behavior identified by Ajtić et al (2015) and Hernández-Ceballos et al (2016b). Ajtić et al (2015) investigated an association between the Be-7 surface concentration and tropopause height at 21 measurement sites across Europe, while Hernández-Ceballos et al (2016b) used cluster analysis technique on the monthly index to identify spatial patterns of similar Be-7 surface concentrations.…”

Beryllium-7 Specific Activity in Surface Air and Its Correlation With Meteorological Variables, Solar Zenith Angle, and Number of Sunspots

“…Measurements of the 7 7 Be specific activity measurements are given in [20], [21]. The 7 Be database stored in the REMdb is public until 2006, and the access to the data corresponding to the 2007-2011 period can be granted only after explicit request.…”

Integrating Functional Block Diagrams and Systems-Theoretic Process Analysis: A Case Study of a Nuclear Power Station

“…The Table 1 lists significant nuclear incidents from 1980 to 2020. The Saint-Laurent Nuclear Power Plant Incident in 1980 was a result of an increase in the reactor's thermal energy, leading to the melting of the core [12]. The Chornobyl disaster in 1986 was a nuclear accident that occurred at the No.…”