• Nuclear Engineering and Technology
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• 제51권6호
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• pp.1540-1553
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• 2019

A nuclear power plant (NPP) is a highly complex system-of-systems as manifested through its internal systems interdependence. The negative impact of such interdependence was demonstrated through the 2011 Fukushima Daiichi nuclear disaster. As such, there is a critical need for new strategies to overcome the limitations of current risk assessment techniques (e.g. the use of static event and fault tree schemes), particularly through simulation of the nonlinear dynamic feedback mechanisms between the different NPP systems/components. As the first and key step towards developing an integrated NPP dynamic probabilistic risk assessment platform that can account for such feedback mechanisms, the current study adopts a system dynamics simulation approach to model the thermal dynamic processes in: the reactor core; the secondary coolant system; and the pressurized water reactor. The reactor core and secondary coolant system parameters used to develop system dynamics models are based on those of the Palo Verde Nuclear Generating Station. These three system dynamics models are subsequently validated, using results from published work, under different system perturbations including the change in reactivity, the steam valve coefficient, the primary coolant flow, and others. Moving forward, the developed system dynamics models can be integrated with other interacting processes within a NPP to form the basis of a dynamic system-level (systemic) risk assessment tool.

• Nuclear Engineering and Technology
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• 제54권8호
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• pp.3034-3042
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• 2022

The results of radioecological monitoring of the cooling pond Beloyarsk NPP (Russia) have been presented. The influence of waste technological waters of thermal and fast NPP reactors on the content of artificial radionuclides in surface waters and bottom sediments of the Beloyarsk reservoir has been studied. The long-term dynamics of the specific activity of ⁶⁰Co, ⁹⁰Sr, ¹³⁷Cs and ³H in the main components of the freshwater ecosystem at different distances from the source of radionuclide discharge has been estimated. Critical radionuclides (⁶⁰Co and ¹³⁷Cs), routes of their entry and periods of maximum discharge of radioisotopes into the cooling pond have been determined. It is shown that the technology of electricity generation at Beloyarsk NPP, based on fast reactors, has a much smaller effect on the flow of artificial radionuclides into the freshwater ecosystem of the reservoir. During the entire period of monitoring studies, the decrease in the specific activity of radionuclides from NPP origin in surface waters was 4.3-74.5 times, in bottom sediments 10-505 times. The maximum discharge of artificial radionuclides into the reservoir was noted during the period of restoration and decontamination work aimed at eliminating emergencies at the AMB thermal reactors of the first stage of the Beloyarsk NPP.

• 방사성폐기물학회지
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• 제9권1호
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• pp.23-32
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• 2011

한국형 기준 처분시스템의 공학적 방벽에서의 열-수리-역학 복합 현상을 실증하기 위한 공학적 규모 실증실험 장치인 KENTEX에서 얻은 열, 수리, 역학적 실험 데이터를 이용하여 벤토나이트의 포화공정을 해석하였다. ABAQUS를 사용한 모델계산의 함수율과 실험 결과의 비교에서 불포화 영역에서는 온도상승으로 인해 초기 수분이 감소하는 수분 재분포 공정을 모델에 포함시키지 않아 함수율의 차가 컸다. 포화 영역에서는 실험에서 초기 수분보다 낮은 함수율에서부터 지하수로 포화가 진행되지만 모델과 실험에서 얻은 함수율 값의 차이가 점점 감소해 완전포화에 도달할 때에는 두 함수율 값이 거의 비슷한 결과를 보여주였다. 포화도 약 95%에 이르는 시간은 실험결과와 계산 결과가 서로 비슷한 약 500일 정도로 예측할 수 있었다. 그리고 불포화 영역의 수분 재분포가 벤토나이트의 완전포화에 도달하는 시간에는 큰 영향을 미치지 않는 것으로 분석되었다. 따라서 본 해석기법을 사용하면 지하처분연구시설의 완충재인 벤토나이트의 포화시간을 예측할 수 있을 것으로 판단된다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2004년도 춘계 학술발표대회 개요집
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• pp.316-318
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• 2004

In recent years, plastic waste has been recognized as a worldwide environmental issue. To solve the disposal problem of the plastic waste, alternative treatment such as the use of biodegradable plastic(polybutylene succinate: PBS) is indeed highly in demand due to its merit of PBS buried in soil decomposed into carbon dioxide and water. In the present study, for the production of further functional PBS with TiO$_2$ as photocatalyst, which shows the decomposition of detrimental organic compound and pollutant under ultraviolet irradiation, we attempted to prepare photocatalytic TiO$_2$ coatings on PBS substrate by HVOF and plasma spraying techniques under various conditions using three kinds of agglomerated powders (P200: 200nm, P30: 30nm, P7: 7nm). The microstructures of coatings were characterized with SEM and XRD analysis, and the photocatalytic efficiency of coatings was evaluated through the photo degradation of gaseous acetaldehyde. Therefore, such functional TiO$_2$-Plastic composite material is expected to considerably contribute to the reduction of aggravated environmental problem.

• 한국기계가공학회지
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• 제17권5호
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• pp.52-57
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• 2018

Most current ships have adopted on-board diesel generators to produce electricity, but the overall efficiency of equipment is down to about 50% due to thermal losses from operations such as exhaust gas, jacket water cooler, scavenge air cooler, etc. Recently, fuel cells have been highlighted as a promising technology to reduce the effect on the environment and have a higher efficiency. Therefore, this paper suggested a solid oxide fuel cell (SOFC)-gas turbine (GT) using waste heat from a SOFC and SOFC-GT-steam turbine (ST) with Rankine cycle. To compare both configurations, the fuel flow rate, current density, cell voltage, electrical power, and overall efficiency were evaluated at different operating loads. The overall efficiency of both SOFC hybrid systems was higher than the conventional system.

• 한국응용과학기술학회지
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• 제36권4호
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• pp.1427-1433
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• 2019

본 연구에서는 합성가스의 에너지화를 위한 가스엔진 성능 평가를 수행하였다. 회전수 1800 rpm 조건에서 공기과잉률이 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6 증가에 따른 엔진출력(kW_m)과 열효율(%)을 평가한 결과, 공기과잉률 λ 1.4에서 엔진출력 34 kW_m를 나타냈으며, 공기과잉률이 증가할수록 엔진 열효율은 전반적으로 감소하는 경향을 보였다. 엔진출력 34 kW_m 조건에서 공기과잉률이 1, 1.1, 1.2, 1.3, 1.4 증가시 열효율이 34.2%, 36.9%, 37.2%, 37.4%, 38.1%로 증가하였고, 발전출력을 통한 종합효율은 발전출력 30 kWe 부하조건에서 38.7 kg/h의 연료를 소모하여 32.1%의 발전효율과 냉각수와 배기가스에서의 열회수를 통해 57.3 kW의 폐열을 회수하여 53.8%의 열을 회수하여 총 85.8%의 종합효율을 보이는 것으로 나타났다.

• Membrane and Water Treatment
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• 제15권3호
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• pp.107-115
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• 2024

This study proposes the recycling of MVS as a value-added product for the removal of phosphate from aqueous solutions. By comparing the phosphate adsorption capacity of each calcined adsorbent at each temperature of MVS, it was determined that the optimal heat treatment temperature of MVS to improve the phosphate adsorption capacity was 800 ℃. MVS-800 suggests an adsorption mechanism through calcium phosphate precipitation. Subsequent kinetic studies with MVS-800 showed that the PFO model was more appropriate than the PSO model. In the equilibrium adsorption experiment, through the analysis of Langmuir and Freundlich models, Langmuir can provide a more appropriate explanation for the phosphate adsorption of MVS-800. This means that the adsorption of phosphate by MVS-800 is uniform over all surfaces and the adsorption consists of a single layer. Thermodynamic analysis of thermally activated MVS-800 shows that phosphate adsorption is an endothermic and involuntary reaction. MVS-800 has the highest phosphate adsorption capacity under low pH conditions. The presence of anions in phosphate adsorption reduces the phosphate adsorption capacity of MVS-800 in the order of CO 3 2-, SO 4 2-, NO 3- and Cl-. Based on experimental data to date, MVS-800 is an environmentally friendly adsorbent for recycling waste resources and is considered to be an adsorbent with high adsorption capacity for removing phosphates from aqueous solutions. This paper combines the advantages of gray predictor and AI fuzzy. The gray predictor can be used to predict whether the bear point exceeds the allowable deviation range, and then perform appropriate control corrections to accelerate the bear point to return to the boundary layer and achieve.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.1347-1352
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• 2008

The SCW ground heat pump system releases ground energy from the ground water of ground heat exchanger. In other word, ground water is used to heating through releases ground energy which oneself has. But the thermal efficiency of system is going to down because repetitive process of ground water will lost ground energy in standing column well system and if heating load is continually increase, energy of ground water may be frozen or there are no benefits to use ground energy as it owes just little energy. To solve these problems, there are need to exchange water to the ground heat exchanger then the way will be used to maintain Efficiency continually as the way of to be supplied with fresh ground water into ground heat exchanger. However, this type causes waste of ground water. Therefore it is essential to discharge water to outside timely on a heat exchanger. Therefor through a study, find out the best time to discharge water to outside and exchange water to ground heat exchanger, and propose to the DB of design of the ground heat exchanger.

• 멤브레인
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• 제14권3호
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• pp.185-191
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• 2004

원자력 발전의 고온 가스로(high temperature gas-cooled reactor, HTGR)의 냉각제로 사용되는 He가스의 열에너지를 이용하여 물을 분해해서 수소를 생산하는 "열화학적 수소제조 IS프로세스"에 대해 설명하였다. 특히, 분리막 기술의 이용에 관한 연구를 중점으로 정리하였다. 고온 원자력 열에너지를 이용한 열화학적 수소 제조법은 실현 가능한 단계까지 왔다고 생각되며, 아직 연구 개발 과제가 많이 남아 있지만, 미래의 청정에너지 중의 하나인 수소를 대량 생산할 수 있는 가능성을 갖고 있다.

• Asian-Australasian Journal of Animal Sciences
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• 제25권11호
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• pp.1627-1633
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• 2012

This study was to evaluate the feasibility of recycling the solids separated from swine wastewater treatment process as a fuel source for heat production and to provide a data set on the gas emissions and combustion properties. Also, in this study, the heavy metals in ash content were analyzed for its possible use as a fertilizer. Proximate analysis of the solid recovered from the swine wastewater after flocculation with organic polymer showed high calorific (5,330.50 kcal/kg) and low moisture (15.38%) content, indicating that the solid separated from swine wastewater can be used as an alternative fuel source. CO and NOx emissions were found to increase with increasing temperature. Combustion efficiency of the solids was found to be stable (95 to 98%) with varied temperatures. Thermogravimetry (TG) and differential thermal analysis (DTA) showed five thermal effects (four exothermic and one endothermic), and these effects were distinguished in three stages, water evaporation, heterogeneous combustion of hydrocarbons and decomposition reaction. Based on the calorific value and combustion stability results, solid separated from swine manure can be used as an alternative source of fuel, however further research is still warranted regarding regulation of CO and NOx emissions. Furthermore, the heavy metal content in ash was below the legal limits required for its usage as fertilizer.