• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.18 no.spc
• /
• pp.37-50
• /
• 2020

In this paper, an overview of the scoping calculation results is provided with respect to criticality and radiation shielding of two KBS-3V type PWR SNF disposal systems and one NWMO-type CANDU SNF disposal system of the improved KAERI reference disposal system for SNFs (KRS⁺). The results confirmed that the calculated effective multiplication factors (k_eff) of each disposal system comply with the design criteria (< 0.95). Based on a sensitivity study, the bounding conditions for criticality assumed a flooded container, actinide-only fuel composition, and a decay time of tens of thousands of years. The necessity of mixed loading for some PWR SNFs with high enrichment and low discharge burnup was identified from the evaluated preliminary possible loading area. Furthermore, the absorbed dose rate in the bentonite region was confirmed to be considerably lower than the design criterion (< 1 Gy·hr^-1). Entire PWR SNFs with various enrichment and discharge burnup can be deposited in the KRS⁺ system without any shielding issues. The container thickness applied to the current KRS⁺ design was clarified as sufficient considering the minimum thickness of the container to satisfy the shielding criterion. In conclusion, the current KRS⁺ design is suitable in terms of nuclear criticality and radiation shielding.

• Composites Research
• /
• v.28 no.3
• /
• pp.118-123
• /
• 2015

In the current study explain about the bio-based composites made by groundnut shell as reinforcement with polyester resin matrix. Groundnut shell is an abundantly available natural waste byproduct and poly ester resin is widely used to fabricate of composites for good balance of mechanical properties because it is relatively low price and ease of handling. Evaluate the mechanical properties of manufactured groundnut shell/polyester composites by varying the amounts (wt %) of groundnut shell. Particulate shell reinforced polyester composites incorporating varying amounts of groundnut shell (5, 10, 15 and 20%) were characterized for their tensile strength, flexural strength, and impact strength. The mechanical properties improved with increasing particle loading up to 15% and decreased thereafter. Increasing in strength with increased particle shell loading was attributed to increase in surface area which enhanced load transfer between the polyester matrix and ground shall particulates. Scanning electron microscopic studies have been carried out to study the morphology of the composite. Thermal studies and water absorption properties of the composites also studied in this paper.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.19 no.1
• /
• pp.39-49
• /
• 2021

The behaviors of various desorption agents were investigated during the desorption of cesium (Cs) from samples of clay minerals and actual soil. Results showed that polymeric cation exchange agents (polyethyleneimine (PEI)) efficiently desorbed Cs from expandable montmorillonite, whereas acidic desorption solutions containing HCl or PEI removed considerable Cs from hydrobiotite. However, most desorption agents could desorb only 54% of Cs from illite because of Cs's specific adsorption to selective adsorption sites. Cs desorption from an actual soil sample containing Cs-selective clay mineral illite (< 200 ㎛) and extracted from near South Korea's Kori Nuclear Power Plant was also investigated. Considerable adsorbed 137Cs was expected to be located at Cs-selective sites when the 137Cs loading was much lower than the sample's cation exchange capacity. At this low 137Cs loading, the total Cs amount desorbed by repeated washing varied by desorption agent in the order HCl > PEI > NH4+, and the highest Cs desorption amount achieved using HCl was 83%. Unlike other desorption agents with only cation exchange capabilities, HCl can attack minerals and induce dissolution of metallic elements. HCl's ability to both alter minerals and induce H+/Cs+ ion exchange is expected to promote Cs desorption from actual soil samples.

• Steel and Composite Structures
• /
• v.44 no.2
• /
• pp.283-294
• /
• 2022

In this study, a new seismic retrofit scheme of building structures is developed by combining a steel moment frame and steel slit plates to be installed inside of an existing reinforced concrete frame. This device has the energy dissipation capability of slit dampers with slight loss of stiffness compared to the conventional steel frame reinforcement method. In order to investigate the seismic performance of the retrofit system, it was installed inside of a reinforced concrete frame and tested under cyclic loading. Finite element analysis was carried out for validation of the test results, and it was observed that the analysis and the test results match well. An analytical model was developed to apply the retrofit system to a commercial software to be used for seismic retrofit design of an example structure. The effectiveness of the retrofit scheme was investigated through nonlinear time-history response analysis (NLTHA). The cyclic loading test showed that the steel frame with slit dampers provides significant increase in strength and ductility to the bare structure. According to the analysis results of a case study building, the proposed system turned out to be effective in decreasing the seismic response of the model structure below the given target limit state.

• Steel and Composite Structures
• /
• v.50 no.5
• /
• pp.549-562
• /
• 2024

In this study a steel moment frame system to be installed on the exterior surface of an existing structure is proposed as a seismic retrofit device. The seismic performance of the retrofit system was investigated by installing it on the exterior of a single story single bay reinforced concrete frame and testing it under cyclic loading. The cyclic loading test results indicated that the steel frame significantly enhanced the strength and ductility of the bare structure. Finite element analysis was carried out to validate the test results, and it was observed that there was good agreement between the two results. An analytical model was developed in order to apply the retrofit system to an example structure subjected to seven mainshock-aftershock sequential earthquake records. It was observed that the model structure was severely damaged due to the mainshock earthquakes, and the seismic response of the model structure increased significantly due to the subsequent aftershock earthquakes. The seismic retrofit of the model structure using the proposed steel frame turned out to be effective in decreasing the seismic response below the given limit state.

• Journal of the Korean Ceramic Society
• /
• v.51 no.2
• /
• pp.97-102
• /
• 2014

In order to improve the refresh rate of old newspaper(ONP), PCC shape-controlling experiments were carried out. The effect of a PCC polymorph on improving the quality of old newspaper was studied for a transformation from waste paper to eco-friendly paper. The synthesis of PCC consists of an in-situ process and a loading process to enhance the refresh rate of old newspaper. The characteristics between the in-situ process and the loading process could be analysed by SEM analyses of coated fiber surfaces. The retention rate ranges from 65 to 67% after the application of the in-situ process, and that after the loading process ranges from 55 to 58%. The retention rates thus show a difference of about 7-10%. In addition, the whiteness and ERIC characteristics of the in-situ process gave more efficient results than those of the loading process.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.44 no.5
• /
• pp.136-146
• /
• 2002

Land application of manure compost is considered one of the widely-used animal waste management practices. Many livestock farms adopt composting for their animal waste disposal and apply the compost to crop fields. While standard rates have been established based on researches with respect to land application of manure compost recently, there have been few discussions on water quality impact of the application. Water quality impact should be taken into account in land applications of manure compost. In this study, management practices were proposed based on the investigation of water quality of leachate from manure compost under rainfall simulation, field studies, and monitoring runoff water quality from farm fields after land application of animal waste. The concentrations of major water quality parameters of the leachate were significantly high, whereas those of runoff from soils after tillage for soil incorporation, were not affected by the application based on a series of experiments. Runoff water from farm fields after land application also showed high concentrations of pollutants. Appropriate management practices should be employed to minimize pollutant loading from manure applied fields. Proposed major management practices include 1) application of recommended amounts, 2) proper tillage for complete soil and manure incorporation, 3) field management to prevent excessive soil erosion, 4) complete diversion of inflow into the field from outside, 5) implementation of vegetative buffer strips near boundaries, and 6) prevention of direct discharge of runoff water front fields Into streams.

• Nuclear Engineering and Technology
• /
• v.50 no.2
• /
• pp.313-317
• /
• 2018

Licenses for the storage of spent nuclear fuel (SNF) and vitrified highly active waste in casks under dry conditions are limited to 40 years and have to be renewed for prolonged storage periods. If such a license renewal has to be expected since as in accordance with the new site selection procedure a final repository for spent fuel in Germany will not be available before the year 2050. For transport and possible unloading and loading in new casks for final storage, the integrity and the maintenance of the geometry of the cask's inventory is essential because the SNF rod cladding and the cladding of the vitrified highly active waste are stipulated as a barrier in the storage concept. For SNF, the cladding integrity is ensured currently by limiting the hoop stress and hoop strain as well as the maximum temperature to certain values for a 40-year storage period. For a prolonged storage period, other cladding degradation mechanisms such as inner and outer oxide layer formation, hydrogen pick up, irradiation damages in cladding material crystal structure, helium production from alpha decay, and long-term fission gas release may become leading effects driving degradation mechanisms that have to be discussed.

• Journal of Korean Society on Water Environment
• /
• v.22 no.4
• /
• pp.599-604
• /
• 2006

Nitrogen removal with the combined SHARON (Single reactor system for high ammonium removal over nitrite)ANAMMOX (Anaerobic ammonium oxidation) process using the effluent of ADEPT (Anaerobic digestion elutriated phased treatment) slurry reactor with very low C/N ratio for piggery waste treatment was investigated. For the preceding SHARON reactor, ammonium nitrogen loading and removal rate were $0.97kg\;NH_4-N/m^3_{reactor}/day$ and $0.68kg\;NH_4-N/m^3_{reactor}/day$ respectively. In steady state, bicarbonate alkalinity consumption for ammonium nitrogen converted to $NO_2-N$ or $NO_3-N$ was 8.4 gram per gram ammonium nitrogen. The successive ANAMMOX reactor was fed with the effluent from SHARON reactor. The loading and removal rate of the soluble nitrogen defined as the sum total of $NH_4-N$, $NO_2-N$ and $NO_3-N$ in ANAMMOX reactor were $1.36kg\;soluble\;N/m^3_{reactor}/day$ and $0.7kg\;soluble\;N/m^3_{reactor}/day$, respectively. The average $NO_2-N/NH_4-N$ removal ratio by ANAMMOX was 2.41. Fluorescence in situ hybridization (FISH) analysis verified that Candidatus Kuenenia stuttgartiensis were dominate, which means that they played an important role of nitrogen removal in ANAMMOX reactor.

• Land and Housing Review
• /
• v.2 no.1
• /
• pp.87-92
• /
• 2011

The anaerobic digestion of food waste effluent through single- and two-phase process was estimated and compared in this study. The treatment efficiencies for total solid(TS), volatile solid(VS), tCOD(total COD) and sCOD(soluble COD) were invariably higher in the single-phase process, which was accounted for by the fact that the treatment efficiency of organic wastes usually showed an inverse relationship with organic loading rate in the anaerobic digestion. In fact, the organic loading rate was lower for single-phase process. The concentration of tCOD were significantly lower in two-phase process but much more biogas was produced, compared to single-phase anaerobic digestion process, which might be explained partly by the relatively higher stability of two-phase process resulting from the separation of acid phase from methane phase.