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Discharge header design inside a reactor pool for flow stability in a research reactor
윤현기,최용석,서경우,김성훈 한국원자력학회 2020 Nuclear Engineering and Technology Vol.52 No.10
An open-pool type research reactor is designed and operated considering the accessibility around the pool top area to enhance the reactor utilization. The reactor structure assembly is placed at the bottom of the pool and filled with water as a primary coolant for the core cooling and radiation shielding. Most radioactive materials are generated from the fuel assemblies in the reactor core and circulated with the primary coolant. If the primary coolant goes up to the pool surface, the radiation level increases around the working area near the top of the pool. Hence, the hot water layer is designed and formed at the upper part of the pool to suppress the rising of the primary coolant to the pool surface. The temperature gradient is established from the hot water layer to the primary coolant. As this temperature gradient suppresses the circulation of the primary coolant at the upper region of the pool, the radioactive primary coolant rising up directly to the pool surface is minimized.Water mixing between these layers is reduced because the hot water layer is formed above the primary coolant with a higher temperature. The radiation level above the pool surface area is maintained as low as reasonably achievable since the radioactive materials in the primary coolant are trapped under the hot water layer. The key to maintaining the stable hot water layer and keeping the radiation level low on the pool surface is to have a stable flow of the primary coolant. In the research reactor with a downward core flow, the primary coolant is dumped into the reactor pool and goes to the reactor core through the flow guide structure. Flow fields of the primary coolant at the lower region of the reactor pool are largely affected by the dumped primary coolant. Simple, circular, and duct type discharge headers are designed to control the flow fields and make the primary coolant flow stable in the reactor pool. In this research, flow fields of the primary coolant and hot water layer are numerically simulated in the reactor pool. The heat transfer rate, temperature, and velocity fields are taken into consideration to determine the formation of the stable hot water layer and primary coolant flow. The bulk Richardson number is used to evaluate the stability of the flow field. A duct type discharge header is finally chosen to dump the primary coolant into the reactor pool. The bulk Richardson number should be higher than 2.7 and the temperature of the hot water layer should be 1 C higher than the temperature of the primary coolant to maintain the stability of the stratified thermal layer.
윤현기,이대겸,조창상,강성민,윤영중,전영재,전의찬 한국기후변화학회 2017 한국기후변화학회지 Vol.8 No.3
In this study, the N2O emission factor of the facility was developed by measuring the kiln type pyrolysis melting facility. This used PAS (Photoacoustic Spectroscopy) method and measured the N2O emission concentration. From March 2016 to April 2016, it was measured over a total of two times and N2O concentrations were measured continuously for 24 hours using a 24 hour continuous measuring instrument (LSE-4405). The measured N2O emission concentration of the pyrolysis melting facility was 0.263 ppm on average and the emission concentration distribution in the range of 0.013∼0.733 ppm was obtained. Therefore, the N2O emission factor of the kiln-type pyrolysis melting facility was estimated to be 0.829 gN2O/ton-Waste. As a result of comparing the N2O emission factor of the thermal kiln type pyrolysis melting facility and the previous study, previous studies were about 18 times higher. It is estimated that this is due to the difference of furnace temperature, oxygen concentration and denitrification facilities. It is considered that the study of the emission factor of pyrolysis melting facility is an important factor in improving the credibility of greenhouse gas inventory in waste incineration sector.
2P-33 Preparation and release properties of verapamil imprinted inulin-based functional biomaterials
윤현기,윤순도,이창문,김은식,김한성,최영훈 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1
The main object of this work are to prepare the high functional inulin (INL)-based films imprinted with verapamil (VPL) as the target drug. The high functional INL-based film were synthesized by casting method and UV curing process. The prepared films were characterized by scanning electron scanner (SEM) and fourier transform infrared (FT-IR). In addition, the physical properties such as tensile strength (TS), elongation at break (%E), degree of swelling (DS), solubility (S) for the prepared films was investigated. To evaluate the binding characteristics of prepared functional films added with/without the addition of VPL, the adsorption properties of the prepared films was investigated by equilibrium binding experiment. The drug release of VPL for the transdermal drug deliverly systems was examined with pH and temperature. In addition, the release of VPL was carried out by using artificial skin.