환경방사능 측정을 통한 전남·북 산림지역의 안정성 분석

Analysis of the Stability of the Forest Area in Jeollanamdo and Jeollabukdo through Environmental Radioactivity Measurement

This study is intended to provide radiation stability information to the local residents through measurements and analyses of the environmental radiation levels in the natural environments of Jeollanamdo and Jeollabukdo. Three environmental samples, including water, tree leaves, and soil, were collected in seven popular recreational forests, selected from forests in Jeollanamdo and Jeollabukdo including national parks. The control group was determined after referring to the emission concentration of activity in other regions and the environmental radioactivity concentration data released by KINS in 2012 and in conformity with Nuclear Safety Law and Recommendations of UNSCEAR and ICRP. The collected samples underwent air drying preprocess before removing organic matters (tree branches, fallen leaves, and gravels) out of them, and the pretreated samples were dried using a vacuum oven, followed by the gamma detection using High Purity Germanium Detector (HPGe) and Multi-Channel Pulse Height Analyzer (MCA) after conducting measurement per sample for a period of 80,000 seconds. As results, the level of environmental radiation was $^{40}K\;0.36Bq{\cdot}kg^{-1}$ that did not exceed the reported environmental radiation levels detected at tree leaves by KINS in 2012, $^{137}Cs\;71.5Bq{\cdot}g^{-1}$ and $^{40}K\;66.792Bq{\cdot}kg^{-1}$, while $^{137}Cs$ was not detected. In case of surface soil sample, $^{137}Cs\;13.3{\pm}0.4Bq{\cdot}kg^{-1}$ and $^{40}K\;810Bq{\cdot}kg^{-1}$ were confirmed in the study in comparison with the reported average radiation emission on the surface soil by KINS in the same year, $^{137}Cs\;10.815Bq{\cdot}kg^{-1}$ and $^{40}K\;835.66{\pm}184.9Bq{\cdot}kg^{-1}$, which $^{137}Cs$ exceeded the KINS data while $^{40}K$ was lower than the data. For the collected deep soil, $^{137}Cs\;14.7Bq{\cdot}kg^{-1}$, $^{40}K\;946Bq{\cdot}kg^{-1}$ were resulted, comparing them to $^{137}Cs\;21.5Bq{\cdot}kg^{-1}$ and $^{40}K\;670{\pm}16Bq{\cdot}kg^{-1}$, showing higher concentration of $^{137}Cs$ and lower concentration of $^{40}K$ than those in KINS data. When analyzing the entire soil samples including surface and deep soils, $^{137}Cs$ was confirmed to have less radiation level as the depth of soil increased, implying $^{40}K$ was not affected by the depth of soil. When the radiation emission concentration was measured in-situ in the recreational forests, surface soil samples showed higher levels than the reported emission levels of environmental radioactivity by KINS in 2012 for $^{137}Cs$ while the deep soil exhibited lower level than the reported one. The radiation level was lower than the minimum acceptable level recommended by ICRP, UNSCEAR, and Nuclear Power Act. When the radiation level data from other regions were adopted as the control group, $^{137}Cs$ showed relatively higher level in the study area. The results of this study are expected to be used as the basic public health data for visitors to the forests in Jeollanamdo and Jeollabukdo as well as for local residents in the future.