Hyun Koo Kim

Study on The Gross Alpha Analysis Method with LSC

In order to study gross alpha analysis method using LSC, the efficiency tests with uranium standard materials were performed and then compared with the GPC method (US EPA 900.0 method) using 15 groundwater samples. For 15 groundwater samples, the average efficiencies of the GPC and LSC method were 7~11% and 90%, respectively. The average precisions of the GPC and LSC method were 16.16% and 6.00%, respectively. Also, The average standard deviations for 15 samples were 7.38 pCi/L and 2.95 pCi/L, respectively. The determination coefficient of the tested results by two methods was 0.9948. As a result, the LSC method tested in this study was applicable for the screening of the gross alpha and showed the advantages in the gross alpha measurement due to the simple measurement procedures.

Environmental Characteristics of Natural Radionuclides in Groundwaters in Volcanic Rock Areas: Korea

We analyzed natural radionuclides in 80 wells in volcanic rock areas and investigated environmental characteristics. Uranium and radon concentrations ranged from ND to (median value: 0.21) , 38~29,222 pCi/L (median value: 579), respectively. In case of gross-, 26 samples exceeded MDA (minimum detectable activity, ) and gross- (15 pCi/L). But Rn concentrations in 4 samples exceeded USEPA AMCL (Alternative maximum contaminant level, 4,000 pci/L) and one of them showed a significantly higher value (29,222 pCi/L) than the others. The levels of uranium concentrations in volcanic rock aquifer regions were detected in order of andesite, miscellaneous volcanic rocks, rhyolite, basalt aquifer regions. Radon, however, was detected in order of miscellaneous volcanic rocks, rhyolite, andesite, basalt aquifer regions. The correlation coefficient between uranium and radon was r

QA/QC for 222 Rn analysis in groundwater

concentrations in the groundwater samples without standard material due to the short half-life (3.82 day) were measured through the establishment of the counting efficiency of LSC (Liquid Scintillation Counter) using a standard source of . This study for Quality Assurance/Quality Control (QA/QC) of analysis was performed to analyze blank samples, duplicate samples, samples of groundwater sampling before and after. In-situ blank samples collected were in the range of 0.44~6.28 pCi/L and laboratory samples were in the range of 1.66~4.95 pCi/L. Their correlation coefficient was 0.9691 and the source contamination from sampling, migration and keeping of samples were not identified. The correlation coefficient between original and duplicate samples from 65 areas was 0.9987. Because radon is an inert gas, in case of groundwater sampling, it is considered to affect the radon concentration. We analyzed samples separately by groundwater sampling before and after using distilled water, but there is no significant difference for concentrations in distilled waters of two types.

Natural radon reduction rate of the community groundwater system in South Korea

Tank waters from 13 Community Groundwater Systems (CGS) showed average radon reduction rate of 26.5% (varying from -17.9% to 63.3%). When applying the reduction rate of 26.5% to the nationwide CGS, the percentage of CGS having radon level above 100Bq/L decreases from 28.8% to 22.0%. The natural radon reduction method would be applied to the CGS having radon level slightly exceeding guideline of WHO, as an alternative for aeration or GAC.

Hydrochemistry and Occurrences of Natural Radioactive Materials from Groundwater in Various Geological Environment

화강암, 화강편마암, 변성퇴적암류와 같이 다양한 지질환경에서 지하수내 자연방사성물질인 우라늄과 Rn-222의 산출특성에 대한 지하수의 수리화학적 영향, 지질과의 상관성, 단층대의 영향 등에 대해서 알아보고자 하였다. 이 연구를 위하여 영동지역 을 대상으로 2차례에 걸쳐 지하수 49점, 지표수 4점을 채취하였다. 지하수내 우라늄과 지표 암석과의 상관성을 알아보기 위해 감마스펙트로메트리를 이용하여 40지점에서 지표방사능을 측정하였다. 지하수 화학적 유형은 Ca-HCO3, Na-HCO3,, Ca-HCO3 (SO4+NO3)등 3가지 유형을 보인다. 환경부 권고치인 우라늄 30 μg/L를 초과하는 지하수는 총 49지점 중 2점이며, Rn-222의 경 우 미국 EPA 기준치인 148 Bq/L를 초과하는 지하수는 총 40지점중 11점이다. 초과하는 지하수는 주로 화강편마암과 흑운모편 마암 지질과 지질경계부에 분포한다. 지표방사능 세기와 지하수내 우라늄함량과는 뚜렷한 상관관계를 보여지 않는다. 아울러 N45°E 방향의 주향이동단층인 영동단층은 82°의 고경도로 상반에 해당되는 화강암 및 화강편마암지역에서 고함량의 우라늄과 Rn-222가 산출되며, 하반에 해당되는 퇴적암지역에는 고함량의 지하수가 확인되지 않는데, 이와 같은 뚜렷한 차이는 지질의 영 향과 더불어 단층대가 방사성물질의 이동 및 확산을 차단시키는 역할에도 원인이 있을 것으로 추정된다.

Study on Temporal Decay Characteristics of Naturally Occurring Radionuclides in Groudwater in Two Mica Granite Area

To figure out the decay characteristics of naturally occurring radionuclides, eight sampled groundwaters from a monitoring borehole having high levels of uranium and radon concentrations in a two mica granitic area have analyzed by liquid scintillation counters (LSC) for over 1 year. In December 2011, three groundwater samples (DJ1, DJ2, DJ3) were obtained from each aquifer system located at -20 m, -40 m, -60 m of the monitoring borehole below the ground surface, respectively. Five samples (DJ4, DJ5, DJ6, DJ7, DJ8) were additionally gained from each aquifer positioned -20 m, -40 m, -60 m, -100 m, -105 m of the borehole in February 2012, respectively. Temporal variation characteristics of uranium and radon concentrations have showed over maximum 2.1 times and 1.4 times fluctuations of the values in the same sampling intervals over time, respectively. The intervals of -40 m and -105 m in the borehole have the highest values of uranium and radon concentrations, respectively. This may imply that the concentrations of naturally occurring radionuclides such as uranium and radon in groundwater have been changed over time and indicate that the qualities of groundwaters from the aquifers developed at each interval in the borehole are different each other. This discrepancy, moreover, could be caused by behaviour differences between uranium which is in ionic status having a half life of 4.6 billion years and is transported along with the flowing groundwater, and radon which is in gaseous status having a 3.82 day`s half life in the aquifer systems. Physicochemical characteristics of groundwaters from the aquifer systems could be identified by the results of the on-situ measuring items such as pH and Eh, and the major ionic contents. The CPM values of eight groundwater samples analysed by LSC over one year have shown not to follow the theoretical decay curve of the radon. The CPM values of the samples have ranged from 2 to 7.5 after it had passed two months when the theoretical CPM values of the radon started zero since the initial analysis. Alpha and beta particle spectrums have shown the peaks of radium-226, however they have not revealed any peaks of radon and it`s daughter products such as polonium-218 and 214, bismuth-214 for the late stage of the analysis. This implies that the groundwater from the borehole may contain radium-226 having a half life of 1,600 years which decays continuously.