• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3949-3956
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• 2022

Kori Unit 1 is planning a system decontamination project to reduce radiation exposure of decommissioning workers, prevent the spread of contamination and down-grade the level of classification of radioactive waste. The system decontamination range for Kori Unit 1 will be the entire primary system, including RCS, CVCS and RHRS. Some system design modifications are required for the system decontamination operation. In this paper, major system design modifications were evaluated based on the conditions that system restoration is needed after completion of system decontamination. The major system design modifications are CIDF connection location to system, system decontamination operating pressure control, RCP seal water injection and formation of letdown flow. It was evaluated that there was no negative effect on the system due to the system design modifications. However, as the RCP seal water is injected into the system in the oxidation process, the concentration of the oxidizing agent is diluted. Therefore, the oxidizing agent injection and system decontamination operation procedures should be developed to address the dilution effect of the oxidizing agent. The system design modifications dealt in this paper will be finally confirmed through on-site investigation in the future, and if necessary, the system design modifications will be re-evaluated.

• Textile Coloration and Finishing
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• v.32 no.1
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• pp.51-56
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• 2020

This study aims to pursue the multi-functional textile finishing method to detoxify chemical warfare agent by simply treating the well-known antimicrobial agent, chitosan, to cotton fabric. For this purpose, DFP(diisopropylfluorophosphate) was sele cted as a chemical warfare agent simulant and cotton fabric was treated with 0.5, 1.0, and 2wt% chitosan solution in 1wt% acetic acid. DFP decontamination properties of the chitosan treated cotton fabrics were evaluated and compared with the untreated cotton fabric. The chitosan treated cotton fabrics showed better DFP decontamination than the untreated cotton. Decontamination properties of the chitosan treated cotton fabrics improved with the increased chitosan solution used. Especially, the cotton fabrics treated with 2wt% chitosan solution showed 5 times more DFP decontamina tion than the untreated cotton fabrics. This suggested that the chitosan treated fabric has potential to be used as a material for protective clothing with chemical warfare agent detoxifying and antimicrobial properties.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.1
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• pp.15-28
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• 2019

In accordance with the decommissioning plan for the Kori Unit 1 NPP, the reactor coolant system will be chemically decontaminated as soon as possible after permanent shutdown. This study developed the chemical decontamination process though the development project of decontamination technology of reactor coolant system and dismantled equipment for NPP decommissioning, which has been carried out since 2014. In this study, Oxidation/reduction process was conducted using system decontamination process development equipment of lab scale and was divided into unit and continuous processes. The optimal process time was derived from the unit process, and decontamination agent and the number of process were derived through the continuous processes. Through the unit process, the oxidation process took 5 hours and the reduction process took 4 hours. As optimum decontamination agent, the oxidizing agent was $200mg{\cdot}L^{-1}$ Permanganic acid + $200mg{\cdot}L^{-1}$ Nitric acid and the reducing agent was $2000mg{\cdot}L^{-1}$ Oxalic acid. In the case of the number of processes, all oxide films were removed during the two-cycle chemical decontamination process of STS304 and SA508. In the case of Alloy600, all oxide films were removed when chemical decontamination was performed for three cycles or more.

• Korean Chemical Engineering Research
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• v.52 no.3
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• pp.360-365
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• 2014

Vapor-phase hydrogen peroxide(VPHP) has been used as a sterilant in the field of medical and pharmaceutical application due to low corrosive than chlorine contained sterilant. In addition, it is well known that VPHP is effective for decontamination of chemical warfare agents by adding ammonia gas. In this study, the decontamination efficiency was confirmed about CEPS, DFP and dimethoate as simulants of HD, GD and VX using VPHP respectively. For this purpose, VPHP generated from self configured device was injected into decontamination chamber and maintained for reaction time. After the decontamination, the residues are analyzed by GC/MS and decontamination efficiency was calculated. Through by-product for each simulants, the similarities in reaction mechanism of chemical warfare agents were confirmed. CEPS was completely decontaminated at 30% relative humidity within 60 min. By adding ammonia gas, DFP and dimethoate were completely decontaminated within 30 and 150 min respectively.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.470.2-470
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• 2001

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.4
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• pp.560-565
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• 2013

Biological decontamination means the removal of microorganisms from the inanimate object such as building or equipment. In this study, hydrogen peroxide vapor efficacy test using VHP 1000ED system(Steris LifeSciences) were conducted for G. stearothermophilus spore with agent materials(aluminum, stainless steel, poly-carbonate, viton, silicone, kapton and glass). Total recovered spores exposed to hydrogen peroxide vapor(1.0 g/min) during 7, 15, 30, 60 min were calculated. As a result, all agent materials were totally decontaminated within 60 min at 1.0 g/min concentration with 35% hydrogen peroxide vapor. Finally, we could confirmed that hydrogen peroxide vapor possess sporicidal capacity of G. stearothermophilus and found the optimum decontamination conditions with VHP1000ED system.

• Textile Coloration and Finishing
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• v.32 no.2
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• pp.73-79
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• 2020

Pursuing the fabric materials for military chemical warfare protective clothing with the improved detoxification properties, this study investigated the simple and effective cotton treatment method using pad-dry-cure process and 3-aminopropyltrimethox ysilane(APTMS) solution for surface amination. Detoxification properties of the untreated and treated cotton fabrics were evaluated via decontamination of chemical warfare agent simulant, DFP(diisopropylfluorophosphate). The surface aminated cotton fabric increased the rate of the hydrolysis of DFP by the factor of 3 and the decontamination ratio reached 88.2% after 24h. Therefore, the surface amination of the cotton fabric with APTMS can be an effective pathway to prepare the material for protective clothing against chemical warfare agents.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.4
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• pp.429-435
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• 2019

Decontamination wastewater generated from the HyBRID decontamination process of the primary system in a nuclear power plant contains impurities such as sulfate ions, metal ions containing radioactive nuclides, and hydrazine (carcinogenic agent). For this reason, it is necessary to develop a technology to remove these impurities from the wastewater to a safe level. In this study, it has been conducted to remove the impurities using a decontamination wastewater surrogate, and a treatment process of the HyBRID decontamination wastewater has been established. The performance and applicability of the treatment process have been verified through 1 L scale of replicates and a pilot scale (300 L/batch) test.

• Proceedings of the Korean Nuclear Society Conference
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• 2002.05a
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• pp.321.1-321
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• 2002

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.1
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• pp.41-47
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• 2018

Radioactive substances, especially $^{137}Cs$ discharged in the course of Nuclear Power Plant Accident or maintenance of power plants, cause contamination of the soil. For habitation of residents and reuse of industrial land, it is inevitably necessary to decontaminate the soil. This study examines a soil washing process that has actually been used for washing of radioactive-contaminated soil. The soil washing process uses a washing agent to weaken surface tension of the soil and cesium, separating cesium from the soil. In this study, in order to raise the efficiency of the process, a flocculating agent was added to the washing water to remove fine soil and cesium. The cesium concentrations before and after applying the flocculating agent to cesium solution were measured through ICP-OES. When using 0.1 g of J-AF flocculating agent in the experiment, the maximum Cs removal performance was approximately 88%; the minimum value was 67%. Species combinations between cesium and soil were predicted using Visual MINTEQ Code; the ability to reuse the washing water or not, and the removal rate of the fine soil, determined via measurement of the turbidity after applying the flocculating agent, were determined.