• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.02a
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• pp.130-139
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• 2004

The cladding materials remaining after reprocessing process of the nuclear fuel, generally called as hulls, are classified as a high-level radioactive waste. They are usually packaged in the container for disposal after being compacted, melted, or solidified into the matrix. The efforts to fabricate a better ingot for a more favorable disposal to the environment have failed due to the technical difficulties encountered in the chemical decontamination method. In the early 1990s, the accumulation of radio-chemical data on hulls and the advent of new technology such as a laser or plasma have made the pre-treatment of the hulls more efficient. This paper summarizes the information regarding the radio-chemical analysis of the hull through a literature survey and determines the characteristics of the hull and depth profile of the radio-nuclides within the hull thickness. The feasibility study was carried out to evaluate the reduction of the radioactivity by peeling off the surface of the hull with the application of laser technology.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.101-104
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• 2003

In this study based on the mass transfer theory, experiments for the evaporation rates depending on various conditions were carried out through the operation of the existing Natural Evaporation Facility in KAERI. Evaporation media were made of the cotton and polyester. Air circulation in the facility was forced by exhausting fans. The evaporation rate and the decontamination factor were calculated by the result of experiment. The evaporation rate increased as the flow rate of air supply, the feed rate of liquid waste, and the temperature of supplied air increased. As for the humidity of supplied air, the evaporation rate was getting higher as the humidity was getting lower. As the result of this study, operation conditions of the Natural Evaporation Facility are optimized as follows : The air temperature above $8^{\circ}C$, the air humidity below 70%, the air flow rate 1.14-1.47 m/sec, and the liquid waste feed rate $4.6{\ell}/hr\cdotm^2$. The decontamination factor and the radioactivity are $5.1{\times}10^3$and $4.7{\times}10^{-13}{\mu}Ci/\textrm{m}{\ell}$ respectively, at the above mentioned optimum operation conditions. The air factor in the Dalton's equation for evaporation was determined from results of experiment on the temperature, the humidity, and the flow rate of supplied air as following : $[\textit{Eh}=(0.018 + 0.0141\textitv) {\delta}textitH]$

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.14 no.2
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• pp.157-168
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• 2016

Radioactive waste container designs should comply with the requirements for safety (i.e., transportation, storage, disposal) and other criteria such as economics and technology. These criteria are also applicable to the future management of the large amount of LLW and VLLW to arise from decontamination and decommissioning (D&D) of nuclear power plants, which have different features compared to that of wastes from operation and maintenance (O&M). This paper proposes to develop a set of standard containers of multi-purpose usage for transportation, storage and disposal. The concepts of the containers were optimized for management of D&D wastes in consideration of national system for radioactive waste management, in particular the Gyeongju Repository and associated infrastructures. A set of prototype containers were designed and built : a soft bag for VLLW, two metallic containers for VLLW/LLW (a standard IP2 container for sea transport and ISO container for road transport). Safety analyses by simulation and tests of these designs show they are in compliance with the regulatory requirements. A further development of a container with concrete is foreseen for 2016.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.2
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• pp.203-212
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• 2019

Disposal nonconformity of radioactive wastes refers to radioactive wastes that need to be treated, solidified and packaged during operation or decommissioning of NPPs, and are typically exemplified by particulate radioactive wastes with dispersion characteristics. These wastes include the dried powders of concentrated wastes generated in the process of operating NPPs, slurry and sludge, various powdered wastes generated in the decommissioning process (crushed concrete, decontamination sludge, etc.), and fine radioactive soil, which is not easy to decontaminate. As these particulate wastes must be packaged so that they become non-dispersive, they are solidified with solidification agents such as cement and polymer. If they are treated using existing solidification methods, however, the volume of the final wastes will increase. This drawback may increase the disposal cost and reduce the acceptability of disposal sites. Accordingly, to solve these problems, this study investigates the pelletization of particulate radioactive wastes in order to reduce final waste volume.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.1
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• pp.45-63
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• 2017

The oldest commercial reactor in South Korea, Kori-1 Nuclear Power Plant (NPP), will be shut down in 2017. Proper treatment for decommissioning wastes is one of the key factors to decommission a plant successfully. Particularly important is the recycling of clearance level or very low level radioactively contaminated metallic wastes, which contributes to waste minimization and the reduction of disposal volume. The aim of this study is to introduce a conceptual design of a recycle system and to evaluate the doses incurred through defined work flows. The various architecture diagrams were organized to define operational procedures and tasks. Potential exposure scenarios were selected in accordance with the recycle system, and the doses were evaluated with the RESRAD-RECYCLE computer code. By using this tool, the important scenarios and radionuclides as well as impacts of radionuclide characteristics and partitioning factors are analyzed. Moreover, dose analysis can be used to provide information on the necessary decontamination, radiation protection process, and allowable concentration limits for exposure scenarios.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2009.06a
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• pp.84-85
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• 2009

New approaches for detecting, preventing and remedying environmental damage are important for protection of the environment. Procedures must be developed and implemented to reduce the amount of waste produced in chemical processes, to detect the presence and/or concentration of contaminants and decontaminate fouled environments. Contamination can be classified into three general types: airborne, surface and structural. The most dangerous type is airborne contamination, because of the opportunity for inhalation and ingestion. The second most dangerous type is surface contamination. Surface contamination can be transferred to workers by casual contact and if disturbed can easily be made airborne. The decontamination of the surface in the nuclear facilities has been widely studied with particular emphasis on small and large surfaces. The amount of wastes being produced during decommissioning of nuclear facilities is much higher than the total wastes cumulated during operation. And, the process of decommissioning has a strong possibility of personal's exposure and emission to environment of the radioactive contaminants, requiring through monitoring and estimation of radiation and radioactivity. So, it is important to monitor the radioactive contamination level of the nuclear facilities for the determination of the decontamination method, the establishment of the decommissioning planning, and the worker's safety. But it is very difficult to measure the surface contamination of the floor and wall in the highly contaminated facilities. In this study, the poly(styrene-ethyl acrylate) [poly(St-EA)] core-shell composite polymer for measurement of the radioactive contamination was synthesized by the method of emulsion polymerization. The morphology of the poly(St-EA) composite emulsion particle was core-shell structure, with polystyrene (PS)as the core and poly(ethyl acrylate) (PEA) as the shell. Core-shell polymers of styrene (St)/ethyl acrylate (EA) pair were prepared by sequential emulsion polymerization in the presence of sodium dodecyl sulfate (SOS) as an emulsifier using ammonium persulfate (APS) as an initiator. The polymer was made by impregnating organic scintillators, 2,5-diphenyloxazole (PPO) and 1,4-bis[5-phenyl-2-oxazol]benzene (POPOP). Related tests and analysis confirmed the success in synthesis of composite polymer. The products are characterized by IT-IR spectroscopy, TGA that were used, respectively, to show the structure, the thermal stability of the prepared polymer. Two-phase particles with a core-shell structure were obtained in experiments where the estimated glass transition temperature and the morphologies of emulsion particles. Radiation pollution level the detection about under using examined the beta rays. The morphology of the poly(St-EA) composite polymer synthesized by the method of emulsion polymerization was a core-shell structure, as shown in Fig. 1. Core-shell materials consist of a core structural domain covered by a shell domain. Clearly, the entire surface of PS core was covered by PEA. The inner region was a PS core and the outer region was a PEA shell. The particle size distribution showed similar in the range 350-360 nm.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.11b
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• pp.258-268
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• 2005

A new approach has been adopted to remove the hot particulates from nuclear facilities, KAERI, South Korea, by using the new compact cyclone train, made of steel ness steel, with optional vortex finder length. Flow rate results showed a dramatic change in removal efficiency, performance was changed with the change of exit tube length. The 15 m/s flow rate was found suitable one for new equipment with the 49 mm optimum exit tube length for 76 mm cyclone body diameter. Results shows the removal efficiency for $1\;{\mu}m$ was more than $65\%$ and for $10\;{\mu}m$ was seen ${\~}97\%$. Over 15 m/s flow rate, was not shown much different in removal efficiency. The removal efficiency increased with the flow rate, and pressure drop. Cut size diameter decrease with the inlet flow rate. Cut size diameter found lowest with 49 mm exit tube length and 15 m/s flow rate. For filters the performance decreased with the inlet velocity increased.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.650-654
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• 2003

A major problem of nuclear energy is the production of radioactive wastes. Needs for more environmentally favorable method to decontaminate radioactive contaminants make the use of liqui $d^ercritical $CO_2$ as a solvent medium. In removing radioactive metallic contaminants under $CO_2$ solvent, two methods - use of chelating ligands and that of water in $CO_2$ emulsion-are possible. In the chelating ligand method, a combination of ligands that can make synergistic effects seems important. We discuss about the properties of microemulsion formed by F-AOT and that by non-ionic surfactant. By adding acid in water core, decontamination of metallic parts, soils were possible. The rate of metal surface dissolution to the microemulsion solution was measured by QCM. The possibility of recovering the surfactants after use is also mentioned.ed.

• Membrane Journal
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• v.25 no.6
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• pp.478-487
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• 2015

This review article indicated accident examples in the past and discussed dangerousness according to these examples. In addition, the ways to remove radioactive ions in radioactive waste, they were divided broadly and enumerated experimental case. These were many results of the experiment and patents used various ways complexly, but domestic technology prowess lower than foreign technology prowess. Even in case of accidents that could happen afterwards, it is essential for growth and competitiveness of domestic technology. Through this article, it considered today's technology for removing radioactive ions and was trying to find out about the possibility of development.

• Nuclear Engineering and Technology
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• v.49 no.3
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• pp.556-561
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• 2017

Serving as an excellent adsorbent and inorganic ion exchanger in the water purification field, zeolite 4A has in this work presented a strong capability for purifying radioactive waste, such as $Sr^{2+}$, $Cs^+$, and $Co^{2+}$ in water. During the processes of decontamination and decommissioning of suspended solids and organics in low-level radioactive wastewater, the purification performance of zeolite 4A has been studied. Under ambient temperature and neutral condition, zeolite 4A absorbed simulated radionuclides such as $Sr^{2+}$, $Cs^+$, and $Co^{2+}$ with an absorption rate of almost 90%. Additionally, in alkaline condition, the adsorption percentage even approached 98.7%. After conducting research on suspended solids and organics of zeolite 4A for the treatment of radionuclides, it was found that the suspended clay was conducive to absorption, whereas the absorption of organics in solution was determined by the species of radionuclides and organics. Therefore, zeolite 4A has considerable potential in the treatment of radioactive wastewater.