• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.238-247
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• 2023

The present work represents a technical guideline for decommissioning a disused teletherapy machine model Theratron-780 and contains category one ⁶⁰Co radioactive source. The first section predicts the dose rate from the source in case of normal and radiological emergency situations via FLUKA-MC simulation code. Moreover, the dose assessment for the occupational during the whole process is calculated and compared to the measured values. A suggested cordoned area for safety and security in a radiological emergency is simulated. The second section lists the whole process's technical procedures, including (preview, dismantle, securing, transport and storage) of the disused teletherapy machine. Results show that the maximum obtained accumulated dose for occupational were found to be 24.5 ± 4.9 μSv in the dismantle and securing process in addition to 3.5 ± 1.8 μSv during loading on the transport vehicle and unloading at the storage facility. It was found that the measured accumulated dose for workers is in good agreement with the estimated one by uncertainty not exceeding 5% in normal operating conditions.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.3
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• pp.237-247
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• 2005

It is necessary to forecast the various dismantling activities prior to dismantling nuclear facilities by using various software instead of a physical mock-up system because the dismantling in a contaminated with radioactivity cause the results of an unexpected situation. The component that needs to develop a dismantling mock-up system was examined. There are many component systems such as a decommissioning database system,3D dosimetric mapping that represents a distribution of a radionuclide contamination, a component of modeling for nuclear facility and devices include the decontamination and decommissioning. The research of software architecture about these components was carried out because these component systems that have been independently doesn't describe not only to visual an activities of Decontamination and Decommissioning(D&D) but also to evaluate it. The result was established an architecture that consist of an visualization module which could be visualized an D&D activities and a simulation module which can be evaluated a dismantling schedule and decommissioning cost.

• Nuclear Engineering and Technology
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• v.55 no.8
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• pp.3010-3016
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• 2023

In recent years, the development of radioactive waste containers for nuclear facility decommissioning and dismantling is a critical issue because the Taiwan domestic boiling water reactor nuclear power plant is going to be decommissioned. The main purpose of this research is to design a metal container that meets the structural requirements of related regulations. At first, the shielding analysis was performed by varying dimensions of radioactive waste to determine the storage efficiency of the container. Then, a series of structural analyses for operational and accidental conditions of the container with full load were conducted, such as lifting, stacking, and drop impact conditions. On the other hand, the field drop impact tests were carried out to ensure structural integrity. The present research demonstrates the structural safety of the developed container for decommissioned nuclear facilities in Taiwan.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.2
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• pp.337-342
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• 2018

Spent fuel is moved from the reactor into the spent fuel pool when nuclear power plant permanently shutdown. The sole function of a permanently defueled facility is to store spent fuel in a quiescent state. The function of electric system and loads are reduced. It is necessary to establish an operating strategy of electric system in the permanent shutdown nuclear plant. This paper reviews required loads and design criteria considering transition to permanent shutdown. An operating strategy of onsite electric system is proposed considering decommissioning strategy and stage of defueled condition.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.1
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• pp.91-102
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• 2020

According to the Korea Radioactive Waste Agency's (KORAD's) medium and low level radioactive waste management implementation plan, the Domestic 3rd Step Landfill Disposal Facility has planned to accept a total of 104,000 drums (2 trenches) of very low level radioactive waste (VLLW), from the decommissioning site from April 2019 - February 2026 (total budget: 224.6 billion Won). Subsequently, 260,000 drums (5 trenches) will be disposed in a 34,076 ㎡. Accordingly, KORAD is preparing a waste acceptance criteria (WAC) for this facility. Every disposal facility for VLLW in other countries such as France and Spain, operate their WAC for each VLLW facility with a reasonable application approach, This, paper focuses on analyzing the WAC conditions in VLLW sites in the USA and discusses whether these can be met in domestic VLLW WAC. It also helps in the preparation of WAC for the 3rd Step Landfill Disposal Site in Gyeongju, since the USA has prior experience on decommissioning nuclear waste.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.20 no.4
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• pp.489-500
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• 2022

The decommissioning of nuclear facilities produces various types of radiologically contaminated waste. In addition, dismantlement activities, including cutting, packing, and clean-up at the facility site, result in secondary radioactive waste such as filters, resin, plastic, and clothing. Determining of the radionuclide content of this waste is an important step for the determination of a suitable management strategy including classification and disposal. In this work, we radiochemically characterized the radionuclide activities of filters used during the decommissioning of Korea Research Reactors (KRRs) 1 and 2. The results indicate that the filter samples contained mainly ³H (500-3,600 Bq·g^-1), ¹⁴C (7.5-29 Bq·g^-1), ⁵⁵Fe (1.1- 7.1 Bq·g^-1), ⁵⁹Ni (0.60-1.0 Bq·g^-1), ⁶⁰Co (0.74-70 Bq·g^-1), ⁶³Ni (0.60-94 Bq·g^-1), ⁹⁰Sr (0.25-5.0 Bq·g^-1), ¹³⁷Cs (0.64-8.7 Bq·g^-1), and ¹⁵²Eu (0.19-2.9) Bq·g^-1. In addition, the gross alpha radioactivity of the samples was measured to be between 0.32-1.1 Bq·g^-1. The radionuclide concentrations were below the concentration limit stated in the low- and intermediatelevel waste acceptance criteria of the Nuclear Safety and Security Commission, and used for the disposal of the KRRs waste drums to a repository site.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.37-38
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• 2018

BIM(Building Information Modeling) in the architecture, VDC(Virtual Design and Construction) defined CIFE(Center for Integrated Facility Engineering) of Stanford university in USA, and Data-driven design definition issued by TECDOC-1284 of IAEA are doing data-level design generated by 3D CAD technology, integrating and managing related information based on the 3D model, and Using 3D models effectively during nuclear power plant life cycle. 3D model of domestic nuclear power industry is using interference review between design fields, 4D system linked 3D construction model and schedule activity, but the 3D model generated in the design phase is effectively not utilized during the construction, operation, decommissioning. therefore, This study is aimed to suggest 3D model LOD(Level of Detail) advancement method through the analysis of existing literature, 2D drawings, and 3D models throughout nuclear power plant lifecycle.

• Nuclear Engineering and Technology
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• v.52 no.11
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• pp.2660-2666
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• 2020

Korea successfully achieved energy independence in the shortest period of time from being the poorest country in terms of energy 50 years ago through steady development of nuclear technology. In the past, the nuclear industry has been driven through government-centered policy development, public institution-based research, and industrial facility and infrastructure construction. Consequently, South Korea became a nuclear energy powerhouse exporting nuclear power plants to the UAE, surpassing the level of domestic technological independence. However, in recent years, the nuclear industry in Korea has experienced a decline in new plant construction since the Fukushima accident in Japan, which caused changes in public perspectives regarding nuclear power plant operation, more stringent safety standards on the operation of nuclear power plants, and a shift in governmental energy policy. These changes are expected to change the domestic nuclear industry ecosystem. Therefore, in this study, we investigate the priority of technology development investment from the perspective of experts in private nuclear power companies, shifting the focus from government-led nuclear R&D policies. To establish a direction in nuclear technology development, a survey was conducted by applying an analytic hierarchy analysis to experts who have worked in nuclear power plants for more than 15 years. The analysis items of focus were the 3 attributes of strategic importance, urgency, and business feasibility of four major fields related to nuclear energy: nuclear safety, decommissioning, radioactive waste management, and strengthening industrial competitiveness.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.3
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• pp.377-387
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• 2018

Korea's first commercial nuclear power plant, Kori Unit 1, was permanently shut down on June 18, 2017, after 40 years of successful operation. Kori Unit 1 plans to construct a waste treatment facility in the turbine building prior to commencement of dismantling in earnest. Various radioactive wastes are decontaminated, disassembled, cut and melted in the waste treatment facility and sent to the radioactive waste repository. The proportion of metal radioactive waste in dismantled waste is about 70%, of which large metal radioactive waste is mainly generated in the primary circuit and has high radioactivity, so radiation exposure must be managed during disassembly. In this study, the steam generators are selected as large metal radioactive waste, the exposure doses of the dismantling workers are calculated using RESRAD-RECYCLE code and the methods for reducing the exposure doses are suggested.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.2_spc
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• pp.317-325
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• 2020

The Korea Radioactive Waste Agency plans to expand the storage capacity of radioactive waste by constructing a radioactive waste inspecting building to solve the problem of the lack of inspection space and drum-handling space in the radioactive waste receipt and storage building for the first-stage disposal facility. In this study, the exposure doses of radiation workers that handle new disposal containers for decommissioning waste in the storage areas of the radioactive waste inspecting building were calculated using the Monte Carlo N-particle transport code. The annual collective dose was calculated as a total of 84.8 man-mSv for 304 new disposal containers and an estimated annual 306 working hours for the radiation work. When the 304 new disposal containers (small/medium type) were stored in the storage areas, it was found that 25 radiation workers should be involved in acceptance/disposal inspection, and the estimated exposure dose per worker was calculated as an average annual value of 3.39 mSv. When the radiation workers handle the small containers in high-radiation dose areas, the small containers should be shielded further by increasing the concrete liner thickness to improve the work efficiency and radiation safety of the radiation workers. The results of this study will be useful in establishing the optimal radiation working conditions for radiation workers using the source term and characteristics of decommissioning waste based on actual measurements.