Plasma melting technology uses electrical arc phenomena such as lightning to create hightemperature sparks of about 1,600 degrees or more to meet waste disposal requirements through treatment and reduction without distinguishing radioactive waste generated during nuclear power plant operation and dismantling according to physical characteristics. Decommissioning radioactive waste scabbed concrete occurs when polishing and cutting the contaminated structure surface to a certain depth. In this study, Scabbed concrete containing paint was confirmed for volume reduction and disposal safety using plasma treatment technology, and it is planned to be verified through continuous empirical tests.

The demand for LNG Carrier and LNG fuel ships are increasing due to global carbon neutrality declaration and ship emissions regulation of IMO, domestic shipyards pay technology fees(about 5~10% of ship price per vessel) to GTT company in France for making LNG cargo hold. Localization of LNG cargo hold is needed to reduce technology fees and engage technological competitiveness, it is important to secure the critical technology like automation process development of insulation system process. Especially, the automation rate of membrane-type insulation system is very low due to interference caused by corrugation and difficulty in securing optimal variable welding condition. In this study, to solve this problem, automatic welding is performed using developed automatic welding equipment on STS304L steel which is used in flat and corner area of membrane-type LNG cargo hold's lap joint. After welding, Cross-sectional observations and Tensile strength tests were conducted to evaluate reliability of equipment and welding condition. As a result of the test, it was confirmed that the strength of the welded zone exceeded that of base material, and secured the optimal welding condition to apply automatic welding.

In recent years, people are increasingly interested in CO2 hydrogenation to produce value-added chemicals and fuels ( CH4, CH3OH, etc.). In the quest for an efficient treatment in CO2 methanation and methanolization, several technologies have been practiced, and DBD plasma technology gain attention due to its easily handling, mild operating conditions, strong activation ability, and high product selectivity. In addition, its reaction mechanism and the effect of packing materials and reaction parameters are still controversial. To address these problems efficiently, a summary of the reaction mechanism is presented. A discussion on plasma-catalyzed CO2 hydrogenation including packing materials, reaction parameters, and optimizing methods is addressed. In this review, the overall status and recent findings in DBD plasma-catalyzed CO2 hydrogenation are presented, and the possible directions of future development are discussed.

Air conditioning facilities in nuclear power plants use pre-filters, HEPA filters, activated carbon filters, and bag filters to remove radionuclides and other harmful substances in the atmosphere. Spent filters generate more than 100 drums per year per a nuclear power plant and are stored in temporary radioactive waste storage. Plasma torch melting technology is a method that can dramatically reduce volume by burning and melting combustible, non-flammable, and mixed wastes using plasma jet heat sources of 1,600°C or higher and arc Joule heat using electric energy, which is clean energy. KHNP CRI & KPS are developing and improving waste treatment technology using MW-class plasma torch melting facilities to stably treat and reduce the volume of radioactive waste. This study aims to develop an operation process to reduce the volume of bag filter waste generated from the air conditioning system of nuclear power plants using plasma torch melting technology, and to stably treat and dispose of it. It is expected to secure stability and reduce treatment costs of regularly generated filter waste treatment, and contribute to the export of radioactive waste treatment technology by upgrading plasma torch melting technology in the future.

Plasma melting technology is a high-temperature flame of about 1,600°C or higher generated using electrical arc phenomena such as lightning, and radioactive waste generated during the operation and dismantling of nuclear power plants is not classified according to physical characteristics. It is a technology that can meet waste disposal requirements through treatment and reduction. Plasma torch melting technology was used for volume reduction and stable treatment of HVAC filters generated from nuclear power plants HVAC (Heating Ventilation and Air Conditioning). filter was treated by placing 1 to 3 EA in a drum and injecting it into a plasma melting furnace at 1,500°C, and the facility was operated without abnormal stop. A total of 132.5 kg of filter was treated, and the high-temperature melt was normally discharged four times. It was confirmed that the plasma torch melting facility operates stably at 500 LPM of nitrogen and 370-450 A of current during filter treatment. Through this study, the possibility of plasma treatment of filters generated at nuclear power plants has been confirmed, and it is expected that stable disposal will be possible in the future.

Radioactive waste must be stored for at least 300 years and must bear astronomical costs. In addition, unexpected potential risk factors are also a considerable burden. In the case of low-level radioactive waste, combustible and liquid low-contamination radioactive waste can be treated relatively easily through high-temperature plasma which the volume can be reduced by 1/250 and the weight by 1/30. It is possible to permanently dispose of the ash leached after plasma treatment in a more stable manner compared to the conventional methods. Types of low-level combustible radioactive waste, including paper, vinyl, clothing, filters, and resins, account for more than 30% of the total waste volume. Furthermore, high-temperature plasma treatment of low-level radioactive waste from petrochemical plants and medical institutions have many advantages, namely astronomical cost savings, securing free space in existing storage facilities, and improving the image of nuclear energy. Korea is preparing to decommission the Kori No. 1 nuclear power plant, and small and mediumsized enterprises and related organizations are conducting various studies to incinerate radioactive waste. In foreign countries, Britain began incineration technology in the 1970s, and Plasma Energy Group, LLC, headquartered in Florida, USA, physically changed the molecular structure of the material by combining plasma chambers and plasma arcs and obtained a patent application in 1992. Germany was approved for operation in 2002, and Switzerland completed a trial run of a plasma technologybased facility in 2004. Important radionuclides in terms of radioactive gas waste treatment include inert gases, radioiodine, and radioactive suspended particles. Gas waste is compressed in a compressor through a surge tank in the gas waste treatment system and filters at each stage. after that, the shortlife nuclide is naturally collapsed for 30 to 60 days in the storage or activated carbon adsorbent in the attenuation tank and released through HEPA filters. The radioactive concentration at discharge is monitored and managed using continuous monitoring equipment, and the oxygen concentration is managed in the gas waste treatment system to prevent explosion risk. The problem of radioactive waste disposal is not only a problem for people living in the present era, but also a big social issue that brings a burden to future generations While interest in plasma treatment is increasing from the decommissioning of the Kori Unit 1. in Korea, it is showed that there is a lack of systematic management and research especially in the radioactive volatile gases fields, that’s why I propose some ideas as follows. First, the government and related institutions should invest to the continuous radioactive monitoring system to produce and distribute continuous radioactive monitoring facilities with an affordable price. Second, it is recommended that radioactive waste incineration would be connected to the GRS system of the plant’s gas radwaste treatment system, and radioactive volatile materials should be monitored through continuous monitoring system. Third, radioactive volatile materials generated according to the temperatures and times during plasma incineration treatment are different. Therefore, prior classification of each expected radioactive volatile substance must be performed before incineration.

The liquid radioactive waste system of nuclear power plants treats radioactive contaminated wastes generated during the Anticipated Operational Occurrence (AOO) and normal operation using filters, ion exchange resins, centrifuges, etc. When the contaminated waste liquid is transferred to an ion exchanger filled with cation exchange resin and anion exchange resin, nuclides such as Co and Cs are removed and purified. The lifespan and replacement time of the ion exchange resin are determined by performing a performance test on the sample collected from the rear end of the ion exchanger, and waste ion exchange resin is periodically generated in nuclear power plants. In the general industry, most waste resins at the end of their lifespan are incinerated in accordance with related laws, but waste resins generated from nuclear power plants are disposed of by clearance or stored in a HIC (High Integrity Container). Plasma torch melting technology can reduce the volume of waste by using high-temperature heat (about 1,600 degrees) generated from the torch due to an electric arc phenomenon such as lightning, and secure stability suitable for disposal. Plasma torch melting technology will be used to check thermal decomposition, melting, exhaust gas characteristics, and volume reduction at high temperatures, and to ensure disposal safety. Through this research, it is expected that the stable treatment and disposal of waste resins generated from nuclear power plants will be possible.

Currently, KHNP has 24 operating nuclear power plant units with a toal combined capacity of about 23 GWe and two units are under construction. However, permanent stop of Kori unit 1 nuclear power plant was decided in 2017. Accordingly, interest in how to dispose of waste stored inside a permanently stopped nuclear power plant and waste generated as decommissioning process is increasing. KHNP CRI is conducting research on the advancement of plasma torch melting facilities for waste treatment generated during the plant decommissioning and operation period. Plasma torch melting facility is composed of various equipment such as a melting furnace (Melting chamber, Pyrolsis chamber), a torch, an exhaust system facility, a waste supply device, and other equipment. In demonstration test, concrete waste was put in a 200 L drum to check whether it can be pyrolyzed using a plasma torch melting facility. Reproducibility for waste treatment in the form of a 200 L drum and discharge of molten slag could be confirmed, the amount of concrete waste in 200 L Drum that could be treated according to power of plasma torch was confirmed. This demonstration test confirmed the field applicability and stability of plasma torch melting facility, and improved expectations for long-term operation.

In nuclear power plants, insulation is used to protect equipment and block heat. Insulation materials include asbestos, glass fiber, calcium silicate, etc. Various types and materials are used. This study aims to ensure volume reduction and disposal safety by applying plasma torch melting technology to insulation generated at operating and dismantling nuclear power plants. After the evaluation of characteristics by securing thermal insulation materials or similar materials in use at the operational and dismantling nuclear power plant. It is planned to perform pyrolysis and melting tests using the MW plasma torch melting facility owned by KHNP CRI Before the plasma test, check the thermal decomposition and melting characteristics (fluidity, etc.) of the insulation in a 1,600°C high-temperature furnace. The insulation is stored in a 200 L drum and injected into a plasma facility, and the drum and the insulation are to be pyrolyzed and melted by the high temperature inside the plasma torch melting furnace. Through this test, thermal decomposition and melting of the insulation, solidification/ stabilization method, maximum throughput, and exhaust characteristics are confirmed at a high temperature (1,600°C) of the plasma torch. Through this study, it is expected that the stable treatment and disposal of insulation generated from operating and dismantling nuclear power plants will be possible.