• Title/Summary/Keyword: Disposal-Phase

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Medium Voltage Power Supply with Enhanced Ignition Characteristics for Plasma Torches

  • Jung, Kyung-Sub;Suh, Yong-Sug
    • Journal of Power Electronics
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    • v.11 no.4
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    • pp.591-598
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    • 2011
  • This paper investigates a power supply of medium voltage with enhanced ignition characteristics for plasma torches. A series resonant half-bridge topology is presented as a suitable ignition circuitry. The ignition circuitry is integrated into the main power conversion system of a multi-phase staggered three-level dc-dc converter with a diode front-end rectifier. A plasma torch rated at 3MW, 2kA and having a physical size of 1m is selected to be the high enthalpy source for a waste disposal system. The steady-state and transient operations of a plasma torch are simulated. The parameters of a Cassie-Mary arc model are calculated based on 3D magneto-hydrodynamic simulations. The circuit simulation waveform shows that the ripple of the arc current can be maintained within ${\pm}10%$ of its rated value under the presence of a load disturbance. This power conversion configuration provides a high enough ignition voltage, around 5KA, during the ignition phase and high arc stability under the existence of arc disturbance noise resulting in a high-performance plasma torch system.

NUCLEAR FUEL CYCLE COST ESTIMATION AND SENSITIVITY ANALYSIS OF UNIT COSTS ON THE BASIS OF AN EQUILIBRIUM MODEL

  • KIM, S.K.;KO, W.I.;YOUN, S.R.;GAO, R.X.
    • Nuclear Engineering and Technology
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    • v.47 no.3
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    • pp.306-314
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    • 2015
  • This paper examines the difference in the value of the nuclear fuel cycle cost calculated by the deterministic and probabilistic methods on the basis of an equilibrium model. Calculating using the deterministic method, the direct disposal cost and Pyro-SFR (sodium-cooled fast reactor) nuclear fuel cycle cost, including the reactor cost, were found to be 66.41 mills/kWh and 77.82 mills/kWh, respectively (1 mill = one thousand of a dollar, i.e., $10^{-3}$ $). This is because the cost of SFR is considerably expensive. Calculating again using the probabilistic method, however, the direct disposal cost and Pyro-SFR nuclear fuel cycle cost, excluding the reactor cost, were found be 7.47 mills/kWh and 6.40 mills/kWh, respectively, on the basis of the most likely value. This is because the nuclear fuel cycle cost is significantly affected by the standard deviation and the mean of the unit cost that includes uncertainty. Thus, it is judged that not only the deterministic method, but also the probabilistic method, would also be necessary to evaluate the nuclear fuel cycle cost. By analyzing the sensitivity of the unit cost in each phase of the nuclear fuel cycle, it was found that the uranium unit price is the most influential factor in determining nuclear fuel cycle costs.

Permanent disposal of Cs ions in the form of dense pollucite ceramics having low thermal expansion coefficient

  • Omerasevic, Mia;Lukic, Miodrag;Savic-Bisercic, Marjetka;Savic, Andrija;Matovic, Ljiljana;Bascarevic, Zvezdana;Bucevac, Dusan
    • Nuclear Engineering and Technology
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    • v.52 no.1
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    • pp.115-122
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    • 2020
  • A promising method for removal of Cs ions from water and their incorporation into stable crystal structure ready for safe and permanent disposal was described. Cs-exchanged X zeolite was hot-pressed at temperature ranging from 800 to 950 ℃ to fabricate dense pollucite ceramics. It was found that the application of external pressure reduced the pollucite formation temperature. The effect of sintering temperature on density, phase composition and mechanical properties was investigated. The highest density of 92.5 %TD and the highest compressive strength of 79 MPa were measured in pollucite hot-pressed at 950 ℃ for 3 h. Heterogeneity of samples obtained at 950 ℃ was determined using scanning electron microscopy. The pollucite hot-pressed at 950 ℃ had low linear thermal expansion coefficient of ~4.67 × 10-6 K-1 in the temperature range from 100 to 1000 ℃.

Development of a reference framework to assess stylized human intrusion scenarios using GENII Version 2 considering design features of planned near-surface disposal facility in Korea

  • Kwon, Ki Nam;Cheong, Jae Hak
    • Nuclear Engineering and Technology
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    • v.51 no.6
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    • pp.1561-1574
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    • 2019
  • A standard form of six stylized human intrusion scenarios for a near-surface disposal facility (e.g. the planned Korean repository, Gyeongju Phase II) is proposed through re-categorization of totally thirty-one past cases reported in public literature. A reference assessment framework for inadvertent human intrusion is newly developed using GENII Version 2 conforming to the ICRP Publication 60 and thereafter. Calculated dose from the assessment framework is verified by comparing with hand calculation results for simplified model equations independently derived. Results from GENII Version 2 and 1.485 show inevitable differences, which is mainly attributed to the difference in the external dose assessment model. If intake dose coefficients in GENII Version 1.485 are modified, the difference can be reduced but still exist to an extent. Through deterministic and probabilistic sensitivity analysis, most affecting four parameters are derived and uncertainties of the parameters are quantified. It is expected that the reference assessment framework together with representative stylized scenarios can be used to do a human intrusion impact assessment for a specific repository using site-specific information. Especially, the past practice of human intrusion impact assessment using GENII Version 1.485 with or without modification may be replaced with the new assessment framework developed in this study.

Development of Evaluation Criteria for Fashion Sustainability Focused on User Practice (사용자 실천 중심 의복지속가능성 평가항목 개발)

  • Kim, Ine;Ha, Jisoo
    • Fashion & Textile Research Journal
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    • v.23 no.2
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    • pp.174-185
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    • 2021
  • The purpose of the study is to establish sustainability evaluation items that can be applied to enhance clothing sustainability practice. The sustainability evaluation items related to clothing by product category, use, and disposal were derived through literature review. In order to evaluate the validity of the derived evaluation items, preliminary survey and two questionnaires were conducted for experts, and the importance and the possibility of change were measured. As a result, 39 evaluation items were constructed. Among the 39 evaluation items, 26 items related to the use and disposal were evaluated for 10 weeks in the 20s and 30s female consumers in terms of practice. The results of the study are as follows: First, items that have a high degree of importance and possibility of change are the items that can minimize resource saving, recycling, and the emission of harmful substances. Second, the participants' perceptions, attitudes, and outcomes of practicing the evaluation items of the use and disposal phase were proved to be positively affected, and the possibility of reducing resource saving and environmental impacts was proved. The clothing sustainability practice played a positive and developmental role in real life, while changing from small things to pursuing newness. The vagueness of sustainability was changed to specific perceptions and behaviors through the practice of the evaluation items.

Oyster Shell waste is alternative sources for Calcium carbonate (CaCO3) instead of Natural limestone

  • Ramakrishna, Chilakala;Thenepalli, Thriveni;Nam, Seong Young;Kim, Chunsik;Ahn, Ji Whan
    • Journal of Energy Engineering
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    • v.27 no.1
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    • pp.59-64
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    • 2018
  • In this paper, we investigated the alternative sources of limestone. Oyster shell waste originated from aquaculture that causes a major disposal landfill problem in coastal sectors in southeast Korea. Their inadequate disposal causes a significant environmental problems araised. Bio mineralization leads to the formation of oyster shells and consists $CaCO_3$ as a major phase with a small amount of organic matter. It is a good alternative material source instead of natural lime stone. The utilization of oyster shell waste for industrial applications instead of natural limestone is major advantage for conservation of natural limestone. The present work describes the limestone and oyster shells hydraulic activity and chemical composition and characteristics are most similar for utilization of oyster shell waste instead of natural limestone.

An Analysis on the Invest Determinants of CDM Project: Evidence from Waste Handling and Disposal Sector (CDM 사업부문별 투자비용 결정요인 분석: 폐기물 부문을 대상으로)

  • Kim, Jihoon;Lim, Sungsoo
    • Korean Journal of Organic Agriculture
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    • v.28 no.4
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    • pp.535-553
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    • 2020
  • In this study, the characteristics of the waste sector CDM project were analyzed through cluster analysis of the waste sector CDM project and the analysis of the CDM investment cost in waste sector using CDM project data registered with UNFCCC since 2008 when EU ETS phase 2 began. As of September 2020, 772 cases of CDM projects in waste disposal and disposal are registered. Biogas technology is the largest, followed by livestock manure processing and biomass production technology. The results of the cluster analysis are summarized as follows: First, on average, projects utilizing AWMS technology are small in size and relatively low in investment costs. This is judged to be relatively low investment costs due to previously attracted foreign investment capital. Second, the average investment cost of CDM projects considered along with waste (No.13), the energy industry (No.1) and agriculture (No.15) was higher than those involving only waste. The analysis of the factors determining the investment cost of the waste sector CDM project showed that, as with cluster analysis, the AWMS technology, which is a livestock manure treatment technology, was lower in the investment cost than those that use other technologies. As a result of multiple regression analysis, the investment cost of the CDM project was analyzed lower in the order of biomass, AWMS, LFG and biogas. Also, the higher the investment cost for CDM projects linked to waste, energy and agriculture, and the better the investment environment, the higher the investment cost. Although no statistical feasibility was obtained, the larger the annual emission reduction, the lower the CDM investment cost.

Influence of Iron Phases on Microbial U(VI) Reduction

  • Lee, Seung-Yeop;Baik, Min-Hoon;Lee, Min-Hee;Lee, Young-Boo;Lee, Yong-Jae
    • Journal of Soil and Groundwater Environment
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    • v.16 no.6
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    • pp.58-65
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    • 2011
  • The bacterial uranium(VI) reduction and its resultant low solubility make this process an attractive option for removing U from groundwater. An impact of aqueous suspending iron phase, which is redox sensitive and ubiquitous in subsurface groundwater, on the U(VI) bioreduction by Shewanella putrefaciens CN32 was investigated. In our batch experiment, the U(VI) concentration ($5{\times}10^5M$) gradually decreased to a non-detectable level during the microbial respiration. However, when Fe(III) phase was suspended in solution, bioreduction of U(VI) was significantly suppressed due to a preferred reduction of Fe(III) instead of U(VI). This shows that the suspending amorphous Fe(III) phase can be a strong inhibitor to the U(VI) bioreduction. On the contrary, when iron was present as a soluble Fe(II) in the solution, the U(VI) removal was largely enhanced. The microbially-catalyzed U(VI) reduction resulted in an accumulation of solid-type U particles in and around the cells. Electron elemental investigations for the precipitates show that some background cations such as Ca and P were favorably coprecipitated with U. This implies that aqueous U tends to be stabilized by complexing with Ca or P ions, which easily diffuse and coprecipitate with U in and around the microbial cell.

Behaviour of Uranyl Phosphate Containing Solid Waste During Thermal Treatment for the Purpose of Sentencing and Immobilisation: Preliminary Results

  • Foster, Richard Ian;Sung, Hyun-Hee;Kim, Kwang-Wook;Lee, Keunyoung
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.18 no.3
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    • pp.407-414
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    • 2020
  • Thermal decomposition of the uranyl phosphate mineral phase meta-ankoleite (KUO2PO4·3H2O) has been considered in relation to high temperature thermal sintering for the immobilisation of a uranyl phosphate containing waste. Meta-ankoleite thermal decomposition was studied across the temperature range 25 - 1200℃ under an inert N2 atmosphere at 1 atm. It is shown that the meta-ankoleite mineral phase undergoes a double de-hydration event at 56.90 and 125.85℃. Subsequently, synthetically produced pure meta-ankoleite remains stable until at least 1150℃ exhibiting no apparent phase changes. In contrast, when present in a mixed waste the meta-ankoleite phase is not identifiable after thermal treatment indicating incorporation within the bulk waste either as an amorphous phase and/or as uranium oxide. Visual inspection of the waste post thermal treatment showed evidence of self-sintering owing to the presence of glass former materials, namely, silica (SiO2) and antimony(V) oxide (Sb2O5). Therefore, incorporation of the uranium phase into the waste as part of waste sentencing and immobilisation via high temperature sintering for the purpose of long-term disposal is deemed feasible.

Risk Factor Analysis in the Implementation Phase of the Housing Redevelopment Project (주택재개발사업 시행단계의 위험요인 분석)

  • Ahn, Jeong-Min;Jung, In-Su;Lee, Chan-Sik
    • Korean Journal of Construction Engineering and Management
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    • v.12 no.4
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    • pp.97-105
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    • 2011
  • As many stakeholders are taking part in the Housing Redevelopment Project, their opinion mediation is considering very important issues. Thus disputes on projects are inevitable due to complexity of interest. To effectively progress the project, this paper analyze the risk factors by phase in implementation phase that the association participates in person. We identify 50 of risk factors in implementation phase by reviewing and analyzing related studies and actual cases of disputes, then we present 26 of risk factors through experts interview. Also, we calculate weights of risk factors by using AHP for quantitatively analyzing them and present final weights and priorities of risk factors by summing weights of risk factors by phase. In results, it is found that 'the inappropriateness of the Management Disposal Plan' in management disposal plan phase and 'the inappropriateness of the Project Implementation Plan' are the most significant risk factors. To maximize the utilization of risk factors analyzed, we present the checklists that can be aware of these risks in advance and prevent these risks. Based on these findings, if risk factors in implementation phase are managed actively, the housing redevelopment project will be performed more effectively.