To secure approval for a decommissioning plan in Korea, it is essential to evaluate contamination dispersion through groundwater during the decommissioning process. To achieve this, licensees must assess the groundwater characteristics of the facility’s site and subsequently develop a groundwater flow model. It is worth noting that Combustible Radioactive Waste Treatment Facility (CRWTF) is characterized by their simplicity and absence of liquid radioactive waste generation. Given these facility characteristics, the groundwater flow model for CRWTF utilizes data from neighboring facilities, with the feasibility of using reference data substantiated through comparative analysis involving groundwater characteristic testing and on-site modeling. To enable a comparison between the actual site’s groundwater characteristics and the referenced modeling, two types of hydraulic constant characterization tests were conducted. First, hydraulic conductivity was determined through long-term pumping and recovery tests. The ‘Theis’ and ‘Cooper-Jacob’ equations, along with the ‘Theis recovery’ equation, were applied to calculate hydraulic conductivity, and the final result adopted the average of the calculated values. Secondly, a groundwater flow test was conducted to confirm the alignment between the main flow direction of the referenced model and the groundwater flow in the CRWTF, utilizing the particle tracking technique. The evaluation of hydraulic conductivity from the hydraulic constant test revealed that the measured value at the actual site was approximately 1.84 times higher than the modeled value. This variance is considered valid, taking into consideration the modeling’s calibration range and the fact that measurements were taken during a period characterized by wet conditions. Furthermore, a close correspondence was observed between the groundwater flow direction in the reference model (ranging from 90° to 170°) and the facility’s actual flow direction (ranging from 78° to 95°). The results of reference data for the CRWTF, based on the nearby facility’s model, were validated through the hydraulic properties test. Consequently, the modeling data can be employed for the demolition plan of CRWTF. It is also anticipated that these comparative analysis methods will be instrumental in shaping the groundwater investigation plans for facilities with characteristics similar to CRWTF.

In light of recent significant seismic events in Korea and worldwide, there is an urgent need to reevaluate the adequacy of seismic assessments conducted during facility construction. This study reexamines the ongoing viability of the Safety Shutdown Earthquake (SSE) criteria assessment for the Combustible Radioactive Waste Treatment Facility (CRWTF) site at the Korea Atomic Energy Research Institute (KAERI), originally established in 1994. To validate the SSE assessment, we delineated 13 seismic structure zones within the Korean Peninsula and employed two distinct methodologies. Initially, we updated earthquake occurrence data from 1994 to the present year (2023) to assess changes in the site’s horizontal maximum earthquake acceleration (g). Subsequently, we conducted a comparative analysis using the same dataset, contrasting the outcomes derived from the existing distance attenuation equation with those from the most recent attenuation equations to evaluate the reliability of the applied attenuation model. The Safety Shutdown Earthquake (SSE) criterion of 0.2 g remains unexceeded, even when considering recent earthquake events since the original evaluation in 1994. Furthermore, when applying various assessment equations developed subsequently, the maximum value obtained from the previously utilized ‘Donvan and Bornstein’ attenuation equation is 0.1496 g, closely resembling the outcome derived from the recently employed ‘Lee’ reduction equation of 0.1451 g. The SSE criteria for CRWTF remain valid in the current context, even in light of recent seismic occurrences such as the 2016 Gyeongju earthquake. Additionally, the attenuation equation employed in the evaluation consistently yields conservative results when compared to methodologies used in recent assessments. Consequently, the existing SSE criteria remain valid at present. This study is expected to serve as a valuable reference for confirming the SSE criterion assessment of similarly constructed facilities within KAERI.

The Korea government decided to shut down Kori-1 and Wolsung-1 nuclear power plants (NPPs) in 2017 and 2019, respectively, and their decommissioning plans are underway. Decommissioning of a NPP generates various types of radioactive wastes such as concrete, metal, liquid, plastic, paper, and clothe. Among the various radioactive wastes, we focused on radioactive-combustible waste due to its large amount (10,000–40,000 drums/NPP) and environmental issues. Incineration has been the traditional way to minimize volume of combustible waste, however, it is no longer available for this amount of waste. Accordingly, an alternative technique is required which can accomplish both high volume reduction and low emission of carbon dioxide. Recently, KAERI proposed a new decontamination process for volume reduction of radioactivecombustible waste generated during operation and decommissioning of NPPs. This thermochemical process operates via serial steps of carbonization-chlorination-solidification. The key function of the thermochemical decontamination process is to selectively recover and solidify radioactive metals so that radioactivity of the decontaminated carbon meets the release criteria. In this work, a preliminary version of mass flow diagram of the thermochemical decontamination process was established for representative wastes. Mass balance of each step was calculated based on physical and chemical properties of each constituent atoms. The mass flow diagram provides a platform to organize experimental results leading to key information of the process such as the final decontamination factor and radioactivity of each product.

In KHNP CRI, the 100 kW PTM (plasma torch melting) system was designed for the treatment and disposal technology of various radioactive wastes including the metal, concrete, liquid waste and insulator. The facility consists of melting chamber, thermal decomposition chamber, waste feeding system and off-gas treatment system. In this study, to evaluate the applicability of the PTM system, demonstration test was conducted using the radiation hazmat suit as combustible waste. The plasma melting chamber is pre-heated by 2nd combustion device and plasma torch for 5 hours. The temperature inside the plasma melting chamber is approximately 1,600°C. The combustible waste was put into the melting chamber by the pusher feeding device with the throughput of maximum 50 kg/hour. During the test, the power of plasma torch is 60–96 kW on the transferred mod. It was evaluated in terms of long-term integrity of PTM system on operation according to the waste throughput ratio.

생활계에서 배출되는 폐기물은 주로 소각처리 또는 소각처리 후 매립 등의 방법이 주로 사용되고 있으며, 소각 또는 매립처리의 경우 2차 환경오염을 유발하는 등의 환경영향을 주는 것으로 보고되고 있다. 생활계에서 발생하는 폐기물의 소각 및 매립처리 등으로 인하여 발생하는 2차 환경오염 문제를 해결하기 위하여 다양한 방법의 적정처리 기술에 대한 연구가 진행되어 왔으며, 국내의 경우 10여년 전부터 생활계 폐기물 중 다량으로 함유되어 있는 가연성 폐기물을 최대한 선별/회수하여 재활용하기 위한 생활계 폐기물 전처리 기술이 도입되어 현재 국내에서 약 20여기가 가동 중에 있다. 대부분의 생활계 폐기물 전처리 설비는 가연성 폐기물을 기계적 선별, 건조 공정 및 성형공정을 통하여 에너지를 생산하고 있으며, 반입되는 폐기물의 성상 특히, 수분함량의 영향으로 일부 시설의 경우 운영상에 문제점을 야기시키는 실정이다. 본 연구에서는 국내에서 운영되고 있는 생활계 폐기물 전처리 시설 중 성형 고형연료(SRF)를 생산하는 대표적인 폐기물 종합처리시설을 선정하여 운영 현황 등을 분석하였다. 폐기물 종합처리시설의 운영 현황 등의 분석을 통하여 성형 고형연료(SRF) 생산시설에서 발생할 수 있는 문제점 등을 파악하고, 보다 효율적인 처리시설의 운영 및 고형연료(SRF)의 생산을 위한 개선 방향을 모색하여 향후 생활계 폐기물 종합처리시설의 설치 및 운영 등에 자료로 활용하고자 한다.

The purpose of this study is to investigate the regional waste discharge and characteristics in Incheon Metropolitan City, and to evaluate the potential energy recovery for combustible wastes being discharged from Incheon province as well as currently being landfilled in the Sudokwon Landfill Site. Approximately, 2,466 ton and 0.879 kg/(capita·day) were estimated for annual average discharge of domestic wastes and daily domestic waste discharge rate per person in Incheon during the period from 2007 to 2013. The least squares methodology indicates those values to decrease to 1,120 ton and 0.347 kg/(capita·day), respectively in year 2021. The assessment of potential energy recovery for the landfilled household solid wastes indicated that total energy of 1.00 × 107 GJ and 212 billion Won of electric charges could be recovered and saved each year. For the construction wastes, recoverable annual energy and electric charges were 1.04 × 107 GJ and 269 billion Won, respectively.

The present research examined the technological trends in optimizing the gasification of waste. Generally, when the percentage of impurities in waste is high, the energy density is low. High-temperature and high-pressure steam is difficult to obtain during energy recovery in incineration. Therefore, the energy recovery rate is low. However, if reaction conditions were optimized in gasification technology, it would be possible to produce synthetic gas with a high percentage of CO and H2. With regard to synthetic gas, there are many different types of energy recovery (steam turbines, gas turbines, gas engines) other than incineration, and it is possible to improve the recovery ratio through gas cleaning. Technologies that have the potential to optimize gasification in each phase were studied. With regard to domestic industry, optimization technology should be applied when planning and operating waste gasification.

In Korea, two decommissioning projects have been carried out due to retire of nuclear research facilities such as Korean research reactors (KRR-1 & KRR-2) and a uranium conversion plant (UCP). The decommissioning of the KRR-2 and a uranium conversion plant (UCP) at KAERI were finished completely by 2011, whereas the decommissioning of KRR-1 is currently underway. The large quantity of radioactive waste was generated during the decommissioning the KRR and UCF such as concrete waste, soil, combustible and non combustible waste. The volume reduction of the combustible wastes through the incineration technologies has merits from the view point of decrease in the amount of waste to be disposed of resulting in a reduction of the disposal cost. Incineration is generally accepted as a method of reducing the volume of radioactive waste. The incineration technology is effective treatment method that contains hazardous chemical as well as radioactive contamination. Incinerator burns waste at high temperatures. Incineration of a mixture of chemically hazardous and radioactive materials, known as“mixed waste,”has two principal goals: to reduce the volume and total chemical toxicity of the waste. Incineration itself does not destroy the metals or reduce the radioactivity of the waste. A proven melting technology is currently used for low-level waste (LLW) at several facilities worldwide. These facilities use melting as a means of processing LLW for unrestricted release of the metal or for recycling within the nuclear sector. Fig. 1 shows the schematic diagram of the oxygen-enriched incineration (OEI) and melting facility. The oxygen-enriched incinerator located at the KAERI. The system consists of a waste preparation system, incineration system, off-gas cooling system, and off-gas treatment system. Demonstration incineration facility took over the responsibilities of KHNP for decommissioned combustible waste. After taking over the demonstration incineration facility from KHNP, the facility was modified, and work toward the licensing procedure, and an extension of the object waste including alpha-bearing waste and increase incineration capacity, began in June 2011. The melt decontamination technology is the most effective treatment method for decommissioned metal waste. Melting for size reduction would require no prior surface decontamination and very little sorting of the waste material. Also, the recycling or volume reduction of the metallic wastes through the melt decontamination technologies has merits from the view point of an increase in resource recycling as well as a decrease in the amount of waste to be disposed of resulting in a reduction of the disposal cost and an enhancement of the disposal safety. Melt facility consist of four system such as preparation system, melting system, ingot treatment, and off-gas treatment system. The decommissioned combustible waste has been incineration by incinerator from last year. In case of metal waste, metal waste will be melt for self-disposal and volume reduction by induction furnace. Combustible wastes were treated by incinerator and ash dispose permanently site. In case of metal wastes is treated by induction furnace and slag dispose permanently site and ingot will be reuse.

In this study, a gasification process has been investigated systematically by numerical method, in order to obtain design and operational concept for the gasification of RPF. A commercial scale of the facility of up-draft fixed bed gasifier was considered with the ignition by plasma torch. Turbulent reacting flow was calculated with the incorporation of the appropriate flow model for the turbulence in free space and inertial resistance for the porous region of waste loading. Further a detailed thermochemical model was employed for estimating the syngas composition by gasification. This study, focused on the S/C (steam/carbon mole ratio) and ER (Equivalence ratio) to show effective gasification process. Results show that better solution of the combined combustion and gasification process strongly and in a delicate manner depends on both equivalence ratio (ER) and steam and carbon mole ratio (S/C). This optimization of the gasifier is evaluated for the following ER (0.25, 0.35, 0.45), S/C (0.0, 2.2, 3). In this study, the gasification efficiency is the best at ER 0.35 and S/C 2.2.