A study on the measurement and analysis of radioactivity concentration and the ambient dose rate in soil on the playgrounds of elementary schools in the Gwangju area

The aim of this study was to obtain nationwide basic data on the distribution of environmental radiation in normal times and to compare the characteristics and distribution in many areas. The data obtained can contribute to improve the radioactivity analysis technology, public health, and the environment in the future. Ten elementary schools in the Gwangju area were selected and soil samples were taken from the playgrounds of the selected schools for analysis. A high-purity Ge (HPGe) semiconductor detector, a multi-channel analyzer (MCA), and a FH40G dose rate detector were used to measure the radioactivity concentration of K-40 and Cs-137, and the ambient gamma dose rate. According to the measured radioactivity concentrations of ⁴⁰K and ¹³⁷Cs, the K-40 concentration (Bq/kg dry) was measured at 723.61 ± 162.72, which was higher than the minimum detection limit (MDL). The Cs-137 concentration (Bq/kg dry) measured was 0.203 ± 0.023, which was lower than the MDL. FH40G was used to measure the ambient gamma dose rate (nSv/h) in different areas. According to the measurement results, the ambient gamma dose rate was 176.73 ± 4.91. With regard to the correlation between the ambient gamma dose rate and radioactivity concentrations of ⁴⁰K and ¹³⁷Cs, ⁴⁰K showed a correlation coefficient with Cs-137 and the ambient gamma dose rate of −0.36 and 0.124, respectively. ¹³⁷Cs revealed a correlation coefficient of 0.293 with an ambient gamma dose rate of −0.210. In conclusion, the low correlation coefficient (<0.5) indicates no significant correlation between the ambient dose rate measurements of K-40 and ¹³⁷Cs.