• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.17 no.4
• /
• pp.437-445
• /
• 2019

After the permanent shutdown of K1 in 2017, decommissioning processes have attracted great attention. According to the current decommissioning roadmap, the dismantling of the activated components of K1 may start in 2026, following the removal of its spent fuel. Since the reactor vessel (RV) and reactor vessel internal (RVI) of K1 contain massive components and are relatively highly activated, their decommissioning process should be conducted carefully in terms of radiological and industrial safety. For achieving maximum efficiency of nuclear waste management processes for K1, we present activation analysis of the segmentation process and waste classification of the RV and RVI components of K1. For RVI, the active fuel regions and some parts of the upper and lower active regions are classified as intermediate-level waste (ILW), while other components are classified as low-level waste (LLW). Due to the RVI's complex structure and high activation, we suggest various underwater segmentation techniques which are expected to reduce radiation exposure and generate approximately nine ILW and nineteen very low level waste (VLLW)/LLW packages. For RV, the active fuel region and other components are classified as LLW, VLLW, and clearance waste (CW). In this case, we suggest in-situ remote segmentation in air, which is expected to generate approximately forty-two VLLW/LLW packages.

• Journal of the Korean GEO-environmental Society
• /
• v.10 no.3
• /
• pp.21-28
• /
• 2009

As the natural aggregates such as sand and clay are getting exhausted, the quantity of utilizing geosynthetics is being increased in the solid waste landfill. Especially, the waste landfills have been constructed at the gorge in the mountainous area and reclaimed land from the sea in the Korean Peninsula. Those areas are not favorable for construction of waste landfill in geotechnical engineering aspect. In this study, the frictional characteristics of geosynthetics that used in the waste landfill were estimated. Then, the studies of the behavior of geosynthetics and stability of LDCRS (Leachate Detection, Collection, and Removal System) of side slope were conducted in the waste landfill by means of the pilot test, and numerical analysis. Geocomposite which is combined type or separated type is influenced on the strain itself, and also implicated in the stress and strain of geomembrane at the lower layer. The strain on the combined type of geocomposite is about 50% smaller than that of the separated type at the side slope. The lateral displacement and settlement of top at the slope with the separated type are three times greater than that of the combined type. In the numerical analysis, discontinuous plans in between ground and geosynthetic, geosynthetic and geosynthetic, goesynthetic and waste have been modeled with the interface element. The results gave a good agreement with the field large-scale model test. The relative displacements of geosynthetics were also investigated and hence the interface modeling of liner system is appropriate for analysis of geosynthetics liner system in the waste landfill.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.15 no.1
• /
• pp.1-14
• /
• 2017

For the removal of cesium (Cs) from high radioactive/high salt-laden liquid waste, this study synthesized a highly efficient composite adsorbent (potassium cobalt ferrocyanide (PCFC)-loaded chabazite (CHA)) and evaluated its applicability. The composite adsorbent used CHA, which could accommodate Cs as well as other molecules, as a supporting material and was synthesized by immobilizing the PCFC in the pores of CHA through stepwise impregnation/precipitation with $CoCl_2$ and $K_4Fe(CN)_6$ solutions. When CHA, with average particle size of more than $10{\mu}m$, is used in synthesizing the composite adsorbent, the PCFC particles were immobilized in a stable form. Also, the physical stability of the composite adsorbent was improved by optimizing the washing methodology to increase the purity of the composite adsorbent during the synthesis. The composite adsorbent obtained from the optimal synthesis showed a high adsorption rate of Cs in both fresh water (salt-free condition) and seawater (high-salt condition), and had a relatively high value of distribution coefficient (larger than $10^4mL{\cdot}g^{-1}$) regardless of the salt concentration. Therefore, the composite adsorbent synthesized in this study is an optimized material considering both the high selectivity of PCFC on Cs and the physical stability of CHA. It is proved that this composite adsorbent can remove rapidly Cs contained in high radioactive/high salt-laden liquid waste with high efficiency.

• Journal of the Korean Geosynthetics Society
• /
• v.11 no.1
• /
• pp.1-9
• /
• 2012

This paper describes the batch test results for application of CFW(Carbonized Foods Waste), which was produced by the process of recycling waste, in PRB system. It analyzed characteristics for individual adsorption and competitive adsorption of Cu and Zn in heavy metals. In individual adsorption, the Langmuir and Freundlich models are used to predict adsorption equilibrium. The adsorption equilibrium corresponded to the Langmuir's and the maximum adsorption amount of Cu was greater than Zn's. The removal of heavy metal is predicted that Zn was faster than Cu. The reaction rate of Zn based on Pseudo-first-order and Pseudo-second-order was faster than Cu's, and the result of competitive adsorption test confirmed that the adsorption amount of Zn is reduced under similar condition for competitive adsorption rate of Cu and Zn. When Zn solution is mixed in Cu, Cu is adsorbed 86% on CFW. However, the adsorption of Zn is 19% on the contrary condition. Therefore, the removal characteristics of separate heavy metal should be considered for efficient treatment of contaminated ground based on complex heavy metal.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.11 no.3
• /
• pp.193-198
• /
• 2013

In general, boron recovery of 40-90% could be achieved by Reverse Osmosis (RO) membranes in neutral pH condition. As an emerging technology, Forward Osmosis (FO) membrane has attracted growing interest in wastewater treatment and desalination. The objective of this study is to evaluate the possibility of the boron removal in radioactive liquid waste by FO. In this study, the performance of FO was investigated to remove boron in the simulated liquid waste as the factors such as pH, osmotic pressure, ionic strength of solution, etc. The pH of feed solution is a major operating parameter which strongly influences to the permeation of boron and more than 80% of boron content can be separated when conducted at pH values less than 7. The water flux is not influenced but the boron flux and permeation rate tends to decrease in the low salt concentration of 1,000 mg/L. The boron flux increases linearly, but the permeation ratio of reducing boron is nearly constant even with changes in the draw solution concentration.

• Resources Recycling
• /
• v.30 no.3
• /
• pp.70-81
• /
• 2021

This study evaluated the recyclability of waste plastics in used coffee capsules disposed of as municipal waste. For recycling, a new material separation process was developed to remove the coffee grounds through primary crushing, washing, sieving, and secondary crushing, followed by corona discharge electrostatic separation. Furthermore, for the under 10 mm size fraction samples, the aluminum removal and the plastic recovery were 95.4% and 98.3%, respectively, under optimal conditions. In addition, for the 15 mm fraction samples, the aluminum removal and the plastic recovery were 91.3% and 97.2%, respectively. To evaluate the recyclability of the separated waste plastics, the samples were pelleted, and their material properties were analyzed. No hazardous substances were detected, and the results were similar to those for homo-PP. Therefore, it was confirmed tha t sufficient functiona lity existed a s recycled PP. However, owing to the da rk color of the pellets, limited applications to black or dark products are expected.

• Clean Technology
• /
• v.21 no.2
• /
• pp.108-116
• /
• 2015

Hydrogen sulfide and ammonia are one of the common malodorous compounds that can be found in emissions from many sewages treatment plants and industrial plants. Therefore, removing these harmful gases from emissions is of significance in both life and industry because they can cause health problems to human and detrimental effects on the catalysts. In this work, pyrolytic carbon blacks from waste tires were used to develop adsorbent with good adsorption capacity for removal of hydrogen and ammonia. Pellet-type adsorbents were prepared by a mixture of carbon black, metal oxide and sodium hydroxide or hydrochloric acid, and their adsorption capacities were estimated by using breakthrough curve of a continuous fixed bed adsorption column at ambient condition. The adsorbent manufactured with a mixture of carbon black, iron oxide(III) and sodium hydroxide showed the maximum working capacity of hydrogen sulfide. For ammonia, maximum working capacity was obtained by the adsorbent manufactured with a mixture of carbon black, copper oxide(II) and hydrochloric acid.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.20 no.3
• /
• pp.21-24
• /
• 2012

In this study, Anaerobic Membrane Bioreactor(AnMBR) treating food waste leachate was operated to investigate treatment efficiency of anaerobic process, operational parameters and production of biogas. AnMBR was operated under the condition of filtration type of inside-out mode. AnMBR was operated under the condition that range of permeate flux was from 15 to 20 LMH and range of transmembrane pressure was from 1 to $3 kgf/cm^2$. It was not good that AnMBR was performed under direct connection between anaerobic reactor and external UF module. so, this connection method changed to indirect connection using buffer tank was placed between anaerobic reactor and UF external module. TCOD and SCOD values were that influent were about 113 g/L, 62 g/L and effluent were 25 g/L, 12 g/L, respectively. also TCOD and SCOD removal efficiency were 77% and 81%, respectively. but after added UF process, COD and SCOD removal efficiency was increased to 93% and 86%, respectively.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.15 no.1
• /
• pp.27-34
• /
• 2017

In this study, desorption characteristics of Cs from clay according to the hydrophobic alkyl chain length of the cationic surfactant were investigated. Alkyltrimethylammonium bromide was used as a cationic surfactant, and the length of the hydrophobic alkyl chain of the cationic surfactant was varied from -octyl to -cetyl. The adsorbed amount of the cationic surfactant on montmorillonite increased with the length of the hydrophobic alkyl chain, and intercalation of the cationic surfactant into the clay interlayer increased the interlayer distances. The Cs removal efficiency was also enhanced with increasing alkyl chain length, and the cationic surfactant with the cetyl group showed a maximum Cs removal efficiency of $992{\pm}2.9%$.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.13 no.1
• /
• pp.35-43
• /
• 2015

A large amount of radioactively-contaminated gravel can be produced on the demolition/restoration of facilities related the back end of fuel cycle. However, because of the lacking in basic knowledge for decontamination of radioactive-contami-nated gravel, this study has performed the basic tests using for soil-washing. To find effective decontamination condition, several experiments were carried out for the selection of optimal decontamination agents. Washing by 0.1 M nitric acid was proved to be more effective than that by distilled water or surfactant for decontamination of uranium-contaminated gravel. In addition, crushing/grinding of uranium-contaminated gravel prior to washing was contributed to increase in of removal efficiency of uranium and reduction of decontamination time. The smaller the sizes of crushed gravel was, the more the removal efficiency increased. Also, small the sized particles improved chances for meeting the clearance requirement of the treated gravel.