The large process plant is currently implementing predictive maintenance technology to transition from the traditional Time-Based Maintenance (TBM) approach to the Condition-Based Maintenance (CBM) approach in order to improve equipment maintenance and productivity. The traditional techniques for predictive maintenance involved managing upper/lower thresholds (Set-Point) of equipment signals or identifying anomalies through control charts. Recently, with the development of techniques for big analysis, machine learning-based AAKR (Auto-Associative Kernel Regression) and deep learning-based VAE (Variation Auto-Encoder) techniques are being actively applied for predictive maintenance. However, this predictive maintenance techniques is only effective during steady-state operation of plant equipment, and it is difficult to apply them during start-up and shutdown periods when rises or falls. In addition, unlike processes such as nuclear and thermal power plants, which operate for hundreds of days after a single start-up, because the pumped power plant involves repeated start-ups and shutdowns 4-5 times a day, it is needed the prediction and alarm algorithm suitable for its characteristics. In this study, we aim to propose an approach to apply the optimal predictive alarm algorithm that is suitable for the characteristics of Pumped Storage Power Plant(PSPP) facilities to the system by analyzing the predictive maintenance techniques used in existing nuclear and coal power plants.

부추속은 수선화과에 속하며 약 1000여종에 이른다. 좀부 추는 자생 부추속에 속하며 식용이 가능하고 크기가 작아 분 화식물로 적합하다. 이에 따라 본 연구는 좀부추를 분화 소재 로서 개발하기 위하여 식물의 측지성장을 촉진하고 꽃의 품질 을 향상시키기 위해 수행되었다. 이를 위하여 좀부추의 구근 을 생장조절제(GA3, BA, 에테폰, TDZ)에 다른 시간(1, 5시 간)동안 침지처리했을 때 식물의 생장과 꽃에 어떤 영향을 주 는지 조사하였다. GA3 처리구는 엽수와 자구의 수가 증가해 증식을 촉진시키는 효과가 있었다. 게다가 GA3는 화수의 증 가와 조기개화를 유도했다. 그러나 엽폭과 화경의 폭은 감소 하였다. 에테폰은 좀부추의 초장과 초폭에서 영향을 주지 않 았으나 1h에서 자구의 수가 증가하였다. 에테폰은 화서 발생 을 억제하여 화경의 수가 감소하였다. BA는 식물의 생장과 개 화 특성에 유의적인 영향을 보이지 않았다. TDZ처리한 식물 은 왜화되고 생육상태가 불량하였으며, 식물을 고사시켰다.

The rapid synthesis techniques and interesting multidisciplinary applications make carbon nanodots (CNDs) stand out from semiconductor quantum dots. Moreover, CNDs derived from green precursors have gained more importance beyond chemically derived CNDs due to sustainable synthesis opportunities. However, the presence of molecular impurities or intermediates or fluorophores was neglected during the entire process. Herein, we illustrate the sustainable synthesis of CNDs from Hemigraphis alternata plant leaves with extended carbonization procedure (3 and 9 min) along with simultaneous ethylene glycol and diethyl ether solvent treatment method for the successful removal of interfering fluorophores. To unravel the distinction between purified CNDs (P-CNDs) and organic fluorescent carbon nanostructures (org-FCNs), we carried out photophysical, structural, and morphological studies. A quantum yield (QY) of 69 and 42% was observed for crude org-FCNs, and crude P-CNDs; however after purification, QY of 1% and absence of one component from the fluorescent decays curve suggest the removal of fluorophores. Further, HR-TEM and DLS studies showed the quasi-spherical amorphous particles having < 10 nm particle size for P-CNDs. Besides, in vitro biocompatibility investigation and cellular uptake assay (1–100 μg/mL) against the MDA-MB 468 cell lines proves the ≥ 95% cell viability and good internalization for both org-FCNs and P-CNDs. Hence, our study shows the presence of fluorophore impurities in plant-derived CNDs, the removal and resemblance in biocompatibility properties. Hence, this information can be considered during the synthesis and isolation of CNDs. Simple and effective removal of impurities to harvest pure carbon nanodots (CNDs) through solvent-based selective separation method, and revelation of the cocktail flourphores similar to biocompatible blue fluorescent CNDs were studied.

According to attached Table 1 of the Enforcement Ordinance of the Nuclear Safety Act, the effective dose limit of transport workers shall not exceed 6 mSv per year. In addition, the enforcement ordinance defines a transport worker as a person who transports radioactive substances outside the radiation management area and does not correspond to a radiation worker. In the nuclear power plants (NPPs), substances in radiation management areas are frequently transported inside or outside the plant. During loading of substances in the radiation management area onto the vehicle, the transport workers (including driver) are located outside the radiation management area. And also the exposure dose of transport workers is managed by using Automatic Dose Reader (ADR). However, the exposure dose of transport workers managed by NPP licensee is limited to the exposure caused by the transport actions required by the plant. This means that radiation exposure caused by the transport of radioactive materials carried out separately by individual transport workers other than the plant requirements cannot be managed. Therefore, even if the NPP licensee manages the transport worker’s dose below 6 mSv, it is difficult to guarantee that the total annual exposure dose, including the transport worker’s individual transport behavior, is less than 6 mSv. Therefore, it would be appropriate to manage the dose of the transport worker by the transport worker’s agency rather than by the NPP licensee.

Kori-1 and Wolseong-1 nuclear power plants were permanently shut down in June 2017 and December 2019, and are currently in the preparation stage for decommissioning. In this regard, it is necessary to secure nuclear power plant decommissioning capacity in preparation for the domestic decommissioning marketplace. To address this, the Korea Research Institute of Decommissioning (KRID) was established to build a framework for the development of integrated nuclear decommissioning technology to support the nuclear decommissioning industry. The institute is currently under construction in the Busan-Ulsan border area, and a branch is planned to be established in the Gyeongju area. Recently, R&D projects have been launched to develop equipment for the demonstration and support verification of decommissioning technology. As part of the R&D project titled “Development and demonstration of the system for radioactivity measurement at the decommissioning site of a nuclear power plant”, we introduce the plan to develop a radioactivity measurement system at the decommissioning site and establish a demonstration system. The tasks include (1) measurement of soil radioactive contamination and classification system, (2) visualization system for massive dismantling of nuclear facilities, (3) automatic remote measurement equipment for surface contamination, and (4) bulk clearance verification equipment. The final goal is to develop a real-time measurement and classification system for contaminated soil at the decommissioning site, and to establish a demonstration system for nuclear power plant decommissioning. The KRID aims to contribute and support the technological independence and commercialization for domestic decommissioning sites remediation of nuclear power plant decommissioning site by establishing a field applicability evaluation system for the environmental remediation technology and equipment demonstration.

Among the twenty six nuclear power plants in Korea, twenty four plants are currently in operation excluding the two permanently shut-down Kori #1 and Wolsung #1 plants. The decommissioning process includes many tasks such as cutting, decontamination, disposal and treatment. Among the tasks, because cutting is one of the tasks performed close to the target structure, there is a possibility for the workers to be exposed excessively to the radiation. There are representative large structures such as steam generators, nuclear reactors, reactor coolant pump, and pressurizer, made of metals, and radioactive concrete, made of concrete. Especially, compared to the trend of research to manage the radiation exposure of steam generators that are directly connected to pressurizers, the trend of research to manage the radiation exposure of pressurizers to workers is not satisfactory. Moreover, although there have been many studies on radioactive concrete, the studies to manage the radiation exposure to workers with a systematic cutting scenario are insufficient. In this study, radioactive concrete, a representative large structure made of concrete, was selected as the target for evaluation. The conditions for evaluation were cutting speed (1~10 m2/hr) and the time for cutting (permanent shutdown~30 years after the shutdown). A cutting scenario was developed by applying the situation for abrasive decontamination beforehand and Hot-to-Cold and Cold-to-Hot, and effort was made to derive a reasonable plan. The evaluation result derived were hourly radiation dose distribution of 1.19~0.103 mSv/hour and 1.29~0.0113 mSv/hour for a scenario without abrasive decontamination (in the order of Hot to Cold, Cold to Hot), and hourly radiation dose distribution of 0.547~0.0479 mSv/hour and 0.608~0.0522 mSv/hour for a scenario with abrasive decontamination. The maximum value of collective dose derived was 1.54E+04 mSv at the cutting time of permanent shutdown with cutting speed of 1 m2/hour in the Cold to Hot scenario before abrasive decontamination, and the minimum value derived was 5.15E+01 mSv at the cutting time of 30-year after the permanent shutdown with cutting speed of 10 m2/hour in the Hot to Cold scenario after abrasive decontamination.

The type of radioactive waste that may occur in the process of nuclear power plant dismantling can be classified into solid, liquid, gas, and mixed waste. In addition, according to the level of radioactivity, it can be divided into high level, intermediate level, low level, and clearance level waste. In the case of solid radioactive waste, it is necessary to secure disposal suitability in order to deliver it to a disposal facility, so safe and efficient treatment of a large amount of radioactive waste generated during decommissioning is one of the most important issues. For the treatment of radioactive waste generated during decommissioning, technologies in various fields such as cutting, decontamination, melting, measurement, and packaging are required. Therefore, this study intends to present and application plan for decommissioning domestic nuclear power plants through overseas case studies for the treatment of radioactive waste expected to occur during nuclear power plant decommissioning.

The concept of clearance is to manage radioactive waste by incineration, reclamation, or recycling as non-radioactive waste, excluding those found to have a concentration of less than the allowable concentration of clearance. Among the types of waste subject to clearance, concrete is managed by recycling and landfill, metal by recycling and reuse, combustible materials by incineration, and soil by landfill. In Korea, clearance has been implemented in earnest since 2000, and the types and quantity of waste subject to clearance are increasing. For clearance, the nuclear-related operator submits its clearance plan to the regulatory body, and the regulatory body reviews the clearance plan and notifies the operator of its suitability. Since a significant amount of radioactive waste generated when decommissioning nuclear power plants is expected to be classified as clearance waste, this study will present clearance waste disposal measures for nuclear power plant through a review of overseas cases related to clearance.

Transport packages have been developed to transport the decommissioning waste from the nuclear power plant. The packages are classified with Type IP-2 package. The IAEA requirements for Type IP-2 packages include that a free drop test should be performed for normal conditions of transport. In this study, drop tests of the packages were performed to prove the structural integrity and to verify the reliability of the analysis results by comparing the test and analysis results. Half-scale models were used for the drop tests and drop position was considered as 0.3 m oblique drop on packages weighing more than 15 tons. The strain and impact acceleration data were obtained to verify the reliability of the analysis results. Before and after the drop tests, radiation shielding tests were performed to confirm that the dose rate increase was within 20% at the external surface of the package. Also, measurement of bolt torque, and visual inspection were performed to confirm the loss or dispersion of the radioactive contents. After each drop test, slight deformations occurred in some packages. However, there was no loss of pretension in the lid bolts and the shielding thickness was not reduced for metal shields. In the package with concrete shield, the surface dose rate did not increase and there was no cracks or damage to the concrete. Therefore, the transport packages met the legal requirements (no more than a 20% increase of radiation level and no loss or dispersion of radioactive contents). Safety verifications were performed using the measured strain and acceleration data from the test, and the appropriate conservatism for the analysis results and the validity of the analysis model were confirmed. Therefore, it was found that the structural integrity of the packages was maintained under the drop test conditions. The results of this study were used as design data of the transport packages, and the packages will be used in the NPP decommissioning project in the future.

Fault activity acts as the greatest risk factor in relation to the stability of the radioactive waste disposal facilities and nuclear power plant site, and for this reason, geological studies on areas with past fault activity history must precede site evaluation studies. This study aims to trace the fault activity history of large fault zones, including the Yangsan fault in the southeastern part of the Korean Peninsula, where two major earthquakes occurred, and to obtain fault activity direction information that is the basis for stability evaluation. The 3D-Shape Preferred Orientation (SPO) of particles in the fault rock created by the earthquake was investigated to analyze the direction of fault plane activity, and the age of fault activity was estimated through Illite Age Analysis (IAA) analysis. It is expected that the large-scale fault activity information in the southeastern part of the Korean Peninsula obtained through the SPO and IAA analysis can be used as basic data for safety evaluation of existing or future nuclear power plants and radioactive waste facilities.

This study aims to select eggplant cultivars adaptive to the hot temperature period greenhouse climate by water consumption, and growth performance of plants and fruits of different European eggplant cultivars, including ‘Bartok (BA)’, ‘Bowie (BO)’, ‘Black Pearl (BP)’, ‘Ishbilia (I)’, ‘Mabel (M)’, ‘Vestale (VE)’ and ‘Velia (VL)’, in substrate hydroponic cultivation under hot and humid greenhouse conditions. On the 118 DAT, the leaf number and stem dry weight were highest in ‘VL’, followed by ‘M’, and there was no significant difference in leaf dry weight among cultivars. The marketable fruit number per plant was 16.4 for ‘M’, which was higher than other cultivars, and ‘VE’ and ‘VL’ were 8.5 and 8.8, respectively. The weight per fruit was low for ‘M’ at 136 g, and the highest in ‘VE’ and ‘VL’ at 332 and 281 g, respectively. There was no significant difference in fruit production per plant. In this study, ‘M’, which has high water use efficiency and a large number of fruits, and ‘VL’, which required less quantity to water consumption for producing 200 g of fruit and had a high product weight, will have excellent adaptability in the UAE greenhouse condition.

This study was aimed to determine the effects of grow media on the mineral contents of the leaves and growth characteristics of strawberry grown under aquaponics system in a plant factory. For aquaculture, 12 fish (Cyprinus carpio) (total weight, 2.0 kg) were raised in an aquaponics tank (W 0.7 m × L 1.5 m × H 0.45 m, 472.5 L) filled with 367.5 L of water at a density of 5.44 kg·m-3 and total 34 of strawberry seedlings were transplanted in the pots filed with 200 g of orchid stone, hydroball or polyurethane sponge in the growing bed (W 0.7 m × L 1.5 m × H 0.22 m) laid out with holly acrylic sheet (140×60 mm, Ø80) on the top of the system. The pH and EC of the aquaponic solution was ranged from 7.6 to 4.9 and 0.24－0.91 dS·m-1, respectively. The concentration of NO3-N was about 28% lower than that of the hydroponic standard solution, and K, Fe and B were 10, 27 and 3.8 times lower, respectively; however, the mineral contents of strawberry leaves were in the appropriate ranges with lower contents in the leaves grown with sponge media. The organic content (OM), nitrogen (N), phosphorus (P), and potassium (K) of the sludge were 61.5, 5.72, 8.92, and 0.24%, respectively. The leaf area, leaf number, and dry and fresh weights of shoot at 81 DAT were significantly higher in the hydroball, and the average number of fruits per plant was significantly higher in both the orchid stone and hydroball. There was no significant difference in the fresh and dry weights of fruits. Integrated all the results suggest that the orchid stone and hydroball media are more effective to utilize nutrients in solid particles of aquaponic solution, compared to the polyurethane sponge.

The emergence of micropollutants in natural water sources due to the overuse of anthropogenic chemicals in industry and households has threatened the production of clean and safe tap water in drinking water treatment plants. Conventional physicochemical processes such as coagulation/flocculation followed by sand filtration are not effective for the control of micropollutants, whereas chemical oxidation processes (applying chlorine, permanganate, ozone, etc.) are known to be promising alternatives. Determining the optimum oxidant dose is important issue related to the production of disinfection by-products as well as unnecessary operating cost, and is made possible by simulations of target-micropollutant abatement based on kinetic model equation consisting of second-order rate constant (between the oxidant and the target) and oxidant exposure. However, the difficulty in determining oxidant exposure as a function of complex water quality parameters limits the field application of kinetic model equation. With respect to representative oxidants used in drinking water treatment plants, this article reviews two main approaches for determining oxidant exposure: i) direct measurement in situ and ii) prediction by empirical models based on key water quality parameters. In addition, we discussed research requirements to improve the predictive accuracy of the empirical models for oxidant exposure and to develop a rational algorithm to determine optimal oxidant dose by considering the priority of the target pollutants to be treated.