• Nuclear Engineering and Technology
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• v.55 no.2
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• pp.530-545
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• 2023

As an alternative to conventional management options for a lot of concrete waste from decommissioning of nuclear power plants, a set of scenarios for controlled recycling of decommissioning concrete waste as engineered barriers of a radioactive waste repository was proposed, and a comprehensive safety assessment model and framework covering both pre-and post-closure phases was newly developed. The new methodology was applied to a reference vault-type repository, and the ratios of derived concentration limits to unconditional clearance levels of eighteen radionuclides for controlled recycling were provided for three sets of dose criteria (0.01, 1, and 20 mSv/y for the pre-closure and 0.01 mSv/y for the post-closure phases). It turns out that decommissioning concrete waste whose concentration is much higher than the unconditional clearance level can be recycled even when the dose criterion 0.01 mSv/y is applied. Moreover, a case study on ABWR bio-shield shows that the fraction of recyclable concrete waste increases significantly by increasing the dose criterion for the radiation worker in the pre-closure phase or the duration of storage prior to recycling. The results of this study are expected to contribute to demonstrating the feasibility of controlled recycling of a lot of decommissioning concrete waste within nuclear sectors.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.20 no.3
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• pp.365-369
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• 2022

Operating and decommissioning nuclear power plants generates radioactive waste. This radioactive waste can be categorized into several different levels, for example, low, intermediate, and high, according to the regulations. Currently, low and intermediate-level waste are stored in conventional 200-liter drums to be disposed. However, in Korea, the disposal of intermediate-level radioactive waste is virtually impossible as there are no available facilities. Furthermore, large-sized intermediate-level radioactive waste, such as reactor internals from decommissioning, need to be segmented into smaller sizes so they can be adequately stored in the conventional drums. This segmentation process requires additional costs and also produces secondary waste. Therefore, this paper suggests repurposing the no-longer-used spent nuclear fuel casks. The casks are larger in size than the conventional drums, thus requiring less segmentation of waste. Furthermore, the safety requirements of the spent nuclear fuel casks are severer than those of the drums. Hence, repurposed spent nuclear fuel casks could better address potential risks such as dropping, submerging, or a fire. In addition, the spent nuclear fuel casks need to be disposed in compliance with the regulations for low level radioactive waste. This cost may be avoided by repurposing the casks.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.4
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• pp.401-409
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• 2006

Regulatory systems for decommissioning of nuclear power plants in several countries, such as Japan, United States of America, Germany, United Kingdom, France, and Republic of Korea, are surveyed. In the survey, regulatory policies, legislations, licensing process, inspection and public involvements for decommissioning are identified and compared. Afterwards, the survey results will be utilized as a reference to establish the improvement directions of domestic regulatory system.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2018.05a
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• pp.173-174
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• 2018

• Journal of Radiation Industry
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• v.18 no.2
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• pp.141-145
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• 2024

In Publication No. 66 of the International Commission on Radiological Protection, an activity median aerodynamic diameter (AMAD) of 5 ㎛ is considered in internal exposure dose assessment owing to inhalation of radionuclides in a workplace. However, analysis of aerosols generated during dismantling experiments, such as in the oxy-cutting of a reactor vessel conducted in Korea, revealed that the radioactive aerosols have AMAD ranging from 0.024 to 0.064 ㎛. Such extremely fine aerosols can induce internal exposure if inhaled. In particular, alpha radionuclides in aerosols can lead to significantly higher levels of radiation exposure than beta and gamma radionuclides, thus highlighting the need to establish appropriate internal exposure radiation protection programs and monitoring systems that specifically address alpha radionuclides when decommissioning nuclear power plants in Korea.

• Journal of Software Engineering Society
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• v.25 no.1
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• pp.11-18
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• 2012

Characteristic of decommissioning target facility investigate and understand is very important. because radioactive materials occurs in the decommissioning and dismantling, so it is difficult to use a general dismantling method. Decommissioning nuclear facilities, the characteristics of the target of research to predict the amount of decommissioning waste, decommission projects costing is largely utilized. For this purpose, we developed DEFACS(Decommissioning Facility Characterization DB System) that manage characteristic of decommissioning target facility. But nuclear facility decommissioning takes long time. so we inevitably developed system during decommissioning works, it occurs many system changes. For this reason, it is difficult to apply general development process, so we take CBD process that divide CD(Component Development) and CBSD(Component Based Software Development) for handling change of requirement. it make Component of the overall system for changes to minimize changes by strengthening the independence of components and processes due to changes in requirements were to minimize stopping of the process.

• Journal of the Korean Society of Systems Engineering
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• v.14 no.1
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• pp.63-71
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• 2018

This paper discusses decommissioning procedure requirements management using requirement engineering to systematically manage the technical requirements and criteria that are required in decontamination and decommissioning activities, and the regulatory requirements that should be complied with in a decommissioning strategy for research reactors and nuclear power plants. A schema was designed to establish the traceability and change management related to the linkage between the regulatory requirements and technical criteria after classifying the procedures into four groups during the full life-cycle of the decommissioning. The results confirmed that the designed schema was successfully traced in accordance with the regulatory requirements and technical criteria required by various fields in terms of decontamination and decommissioning activities. In addition, the changes before and after the revision of the Nuclear Safety Act were also determined. The dismantling procedure requirement management system secured through this study is expected to be a useful tool in the integrated management of radioactive waste, as well as in the dismantling of research reactor and nuclear facilities.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.1
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• pp.141-160
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• 2021

Unit 1 of the Kori Nuclear Power Plant (NPP) and Unit 1 of the Wolsong NPP are being prepared for decommissioning; their decommissioning is expected to generate large amounts of intermediate-level, low-level, and very low level Waste. Mixed waste containing both radioactive and hazardous substances is expected to be produced. Nevertheless, laws and regulations, such as the Korean Nuclear Safety Act and Waste Management Act, do not define clear regulatory guidelines for mixed waste. However, the United States has strictly enforced regulations on mixed waste, focusing on the human health and environmental effects of its hazardous components. The U.S. Nuclear Regulatory Commission and the U.S. Department of Energy regulate the radioactive components of mixed waste under the Atomic Energy Act. The U.S. Environmental Protection Agency regulates the hazardous waste component of mixed waste under the Resource Conservation and Recovery Act. In this study, the laws, regulations, and authorities pertaining to mixed waste in the United States are reviewed. Through comparison and analysis with waste management laws and regulations in Korea, a treatment direction for mixed waste is suggested. Such a treatment for mixed waste will increase the efficiency of managing mixed waste when decommissioning NPPs in the near future.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.14 no.1
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• pp.45-55
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• 2016

Decontamination is one of the most important technologies for the decommissioning of NPP. The purpose of decontamination is to reduce the Risk of exposure of the decommissioning workers, and to recycle parts of the plant components. Currently, there is a lack of data on the efficiency of the decontamination technologies for decommissioning. In most cases, the local radiation level can be lowered below a regulatory limitation by decontamination. Therefore, more efficient decontamination technology must be continuously developed. This work describes the practical experiences in the United States and the European countries for NPP decommissioning using these decontamination technologies. When the decommissioning of domestic nuclear power plant is planned and implemented, this work will be helpful as a reference of previous cases.

• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.1136-1144
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• 2022

The effects of nearby residents and the public by the residual contamination from the decommissioning of nuclear facilities should comply with the dose criteria, and whether additional remediation action is necessary from the ALARA perspective must be determined. Therefore, we analyzed the requirements of ALARA action levels and performed preliminary ALARA evaluation. The ratio of residual contamination concentration to DCGL was calculated for the basement fill and the building occupancy mode. The results showed that the additional remediation actions below DCGL are not justified. In addition, we analyzed the effect of remediation area. It was noted that the increase of the remediation area showed a positive correlation with the Conc/DCGL value in the basement fill mode. On the other hand, in the building occupancy mode, since the floor area of the building is the target of remediation and has the effect of increasing the same as the evaluation area of the building occupants, but due to the difference in the amount of increase, the Conc/DCGL showed a negative correlation. We expect the approach and method of ALARA evaluation can be utilized for concrete cost-benefit calculation during the decommissioning or at the time of remediation.