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Won-Tak Joun,Byeong-Hak Park,Eunhye Kwon,Kyung-Woo Park 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2
Long-term climate and surface environment changes can influence the geological subsurface environment evolution. In this context, a fluid flow pathway developing and connection possibility can be increased between the near-surface zone and deep depth underground. Thus, it is necessary to identify and prepare for the overall fluid flow at the entire geological system to minimize uncertainty on the spent nuclear fuel (SNF) disposal safety. The fluid flow outside the subsurface environment is initially penetrated through the surface and then the unsaturated area. Thus, the previously proved reports, POSIVA in Finland, suggested that sequential research about the fluid infiltration experiment (INEX) and the investigation is necessary. Characterizing the unsaturated zone can help predict changes and ensure the safety of SNFs according to geological long-term evolution. For example, the INEX test was conducted at the upper part of ONKALO, about 50 to 100 m depth, to understand the geochemical evolution of the groundwater through the unsaturated zone, to evaluate the main flow of groundwater that can approach the SNF disposal reservoir, and to estimate the decreasing progress of the buffering capacity along the pathway through the deep geological disposal. In the present study, a preliminary test was performed in the UNsaturated-zone In-situ Test (UNIT) facility near the KAERI underground research tunnel to design and establish a methodology for infiltration experiments consistent with the regional characteristics. The results represented the methodological application is possible for characterizing unsaturated-zone to perform infiltration experiments. The scale of the experiment will be expanded sequentially, and continuous research will be conducted for the next application.
Joun, Won-Tak,Rossabi, Joseph,Shin, Woo-Jin,Lee, Kang-Kun Elsevier 2019 Journal of environmental management Vol.237 No.-
<P><B>Abstract</B></P> <P>Multi-level wells screened at different depths in the vadose zone were installed and used for CO<SUB>2</SUB> and carbon isotope monitoring. Well CO<SUB>2</SUB> time series data were collected along with subsurface and atmospheric parameters such as air pressure, temperature, wind speed, and moisture content. Our aim was to determine the natural factors affecting the variation of CO<SUB>2</SUB> concentration and how the influence of these factors varies with time of day and seasons of the year. We were motivated to understand the cause and extent of CO<SUB>2</SUB> natural fluctuations in vadose zone wells in order to separate natural variation from signals due to anthropogenic CO<SUB>2</SUB> leaks anticipating future monitoring using these wells. Variations of seasonal mean and variance of CO<SUB>2</SUB> concentrations at different depths seem to follow the diurnal trend of subsurface temperature changes that reflect the atmospheric temperature but with time delay and amplitude damping due to heat transport considerations. The temperature in the ground lags behind the change in the atmospheric temperature, thus, the deeper the depth, the longer the time delay and the smaller the amplitude of the change. Monitored seasonal variation as shown in Appendix A shows the temperature-dependent depth-dependent CO<SUB>2</SUB> production in the soil zone indicating higher CO<SUB>2</SUB> concentrations in the summer and fall seasons with high concentrations ranging between 10,990 and 51,600 ppm from spring to summer, and 40,100 and 17,760 ppm from fall to winter. As the temperature in the organic-rich topsoil layer changes from daytime to nighttime, the concentration of CO<SUB>2</SUB> in the soils also changes dynamically in response to chemical and biological reactions. When a screened well is installed in the vadose zone the dynamic temporal and depth difference in CO<SUB>2</SUB> production is further complicated by upward (out of the subsurface) or downward (into the subsurface) gas flow, which will amplify or attenuate the temporal and vertical biochemically produced differences. Nested wells screened at different depths in the vadose zone and wells fully screened through the vadose zone were used for comparison. In addition, experiments changing the well from open to surface air to sealed at the top were conducted. The flow rates of inhaled (downward) and exhaled (upward) gas were estimated based on multi-level monitoring data. Based on time-series monitoring data, we proposed a time-dependent conceptual model to explain the changes of CO<SUB>2</SUB> concentration in wells. The conceptual model was tested through analytical model computations. This conceptual model of natural variation of CO<SUB>2</SUB> will be helpful in utilizing the vadose zone well as a method for monitoring CO<SUB>2</SUB> leakage from subsurface storage or anthropogenic CO<SUB>2</SUB> -producing activities.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Background variations of CO<SUB>2</SUB> concentration must be accounted for to evaluate leaking from storage. </LI> <LI> Large daily swings in naturally produced gas concentration were consistently observed. </LI> <LI> Multi-level monitoring data shows gas circulation in wells due to natural causes. </LI> <LI> Must consider diurnal and weather patterns when conducting gas sampling in wells. </LI> </UL> </P>
개방형 지열시스템의 효율적 설계를 위한 영향인자에 대한 연구
박병학,전원탁,이보현,이강근,Park, Byeong-Hak,Joun, Won-Tak,Lee, Bo-Hyun,Lee, Kang-Kun 한국지하수토양환경학회 2015 지하수토양환경 Vol.20 No.4
Open-loop groundwater heat pump (GWHP) system generally has benefits such as a higher coefficient of performance (COP), lower initial cost, and flexible system size. The hydrogeological conditions in Korea have the potential to facilitate the use of the GWHP system because a large number of monitoring wells show stable groundwater temperatures, shallow water levels, and high well yields. However, few studies have been performed in Korea regarding the GWHP system and the most studies among them dealt with Standing Column Well (SCW). Because the properties of the aquifer have an influence on designing open-loop systems, it is necessary to perform studies on various hydrogeological settings. In this study, the hydrogeological and thermal properties were estimated through various tests in the riverside alluvial layer where a GWHP system was installed. Under different groundwater flow velocities and pumping and injection rates, a sensitivity analysis was performed to evaluate the effect of such properties on the design of open-loop systems. The results showed that hydraulic conductivity and thermal dispersivity of the aquifer are the most sensitive parameters in terms of performance and environmental aspects, and sensitivities of the properties depend on conditions.
지하수 히트펌프 시스템의 지중 환경관리를 위한 시추 슬라임의 원핵생물 유전자 다양성
김희정 ( Heejung Kim ),이시원 ( Siwon Lee ),박정희 ( Junghee Park ),전원탁 ( Won-tak Joun ),김재연 ( Jaeyeon Kim ),김홍현 ( Honghyun Kim ),이강근 ( Kang-kun Lee ) 한국미생물생명공학회(구 한국산업미생물학회) 2016 한국미생물·생명공학회지 Vol.44 No.4
지하수의 열을 이용한 히트펌프 시스템에서는 열 효율 유지를 위한 클로깅 현상이 고려되어야 한다. 클로깅 현상은 토양·지하수 환경에서 이화학적 요인 외에도 미생물학적 요인으로 발생한다. 이번 연구에서는 안정적인 지하수 열원 냉난방 시스템 운영을 위하여, 대수층 수위강하의 영향을 받지 않는 지하 10 미터 지점에서 불교란 시추 슬라임의 초기상태 원핵생물 다양성을 조사하였다. 세균은 문 수준에서 Proteobacteria (20.8%), Acidobacteria (18.8%), Chloroflexi (16.9%) 및 Firmicutes (10.2%) 등으로 나타났고, 속 수준에서는 Koribacter속 등 144개속이 분석되었다. 고세균은 문 수준에서 Thaumarchaeota (42.8%), Crenarchaeota (36.9%) 및 Euryarchaeota (17.4%)이 나타났으며, 강 수준에서 약 69.4% 비율로 Miscellaneous Crenarchaeota Group (MCG), Finnish Forest Soil Type B (FFSB) 및 Thermoplasmata가 분석되었다. Operational taxonomic units (OTUs)는 세균 3,565 및 고세균 836 OTUs로 나타났고, 세균이 고세균에 비해 풍부하며 우점도가 낮게 나타났다. 또한, 관정 막힘 현상을 유발할 가능성 있는 세균 후보군 135개(1.9%) reads가 분석되었으며, 향후 클로깅 현상에 대한 연구에 자료로 활용할 수 있을 것으로 기대된다. Groundwater heat pump (GWHP) systems must consider phenomena such as clogging to improve system efficiency and maintenance. In this study, we evaluated the prokaryotic diversity in a boring slime sample obtained at a depth of 10 m, which represented an undisturbed sample not affected by aquifer drawdown. Bacteria belonging to the phyla Proteobacteria (20.8%), Acidobacteria (18.8%), Chloroflexi (16.9%), and Firmicutes (10.2%) were found. Additionally, 144 species were identified as belonging to the genus Koribacter. Archaeal phyla were detected including Thaumarchaeota (42.8%), Crenarchaeota (36.9%), and Euryarchaeota (17.4%) and the class level comprised the miscellaneous Crenarchaeota group (MCG), Finnish forest soil type B (FFSB), and Thermoplasmata, which collectively accounted for approximately 69.4% of the detected Archaea. Operational taxonomic units (OTUs) were analyzed to reveal 3,565 bacterial and 836 archaeal OTUs, with abundances of 7.81 and 6.68, and richnesses of 5.96E-4 and 2.86E-3, respectively. The distribution of the groundwater microbial community in the study area showed a higher proportion of non-classified or unidentified groups compared to typical communities in surface water and air. In addition, 135 (approx. 1.9%) reads were assigned to a bacterial candidate associated with clogging.