• Proceedings of the Korean Radioactive Waste Society Conference
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• 2017.05a
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• pp.317-318
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• 2017

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.3
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• pp.213-227
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• 2013

It is essential to prepare the decommissioning plan for a nuclear power plant (NPP) for the safe decommissioning of the NPP, minimization of the generation of decommissioning wastes, and protection of human beings and environment. Although Kori unit 1 and Wolsong unit 1 will be destined to their decommissioning in Korea in the near future. there is no provisons about preparing the decommissioning plan. In this paper, therefore, the draft guidelines of the decommissioning plan for a NPP were developed by considering the domestic situation, based on the comparative analyses of the regulatory guidelines of the decommissioning plan in U.S., U.K. and France. The draft guidelines are expected to play an important role to modify the domestic laws and regulations on the decommissioning of the NPP, and to give a license holder in charge of decommissioning the detailed instructions for preparing it in advance.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.2
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• pp.181-189
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• 2017

The purpose of this paper is to evaluate several leading options for the management of radioactive metallic waste against a set of general criteria including safety, cost effectiveness, radiological dose to workers and volume reduction. Several options for managing metallic waste generated from decommissioning are evaluated in this paper. These options include free release, controlled reuse, and direct disposal of radioactive metallic waste. Each of these options may involve treatment of the metal waste for volume reduction by physical cutting or melting. A multi-criteria decision analysis was performed using the Analytic Hierarchy Process (AHP) to rank the options. Melting radioactive metallic waste to produce metal ingots with controlled reuse or free release is found to be the most effective option.

• 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.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.1100-1107
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• 2024

The nuclear waste attributes of near-term deployable SMRs were assessed using established nuclear waste metrics, which are the DU mass, SNF mass, volume, activity, decay heat, radiotoxicity, and decommissioning LLW volumes. Metrics normalized per unit electricity generation were compared to a reference large PWR. Three SMRs, VOYGR, Natrium, and Xe-100, were selected because they represent a range of reactor and fuel technologies and are active designs deployable by the decade's end. The SMR nuclear waste attributes show both some similarities to the PWR and some significant differences caused by reactor-specific design features. The DU mass is equivalent to or slightly higher than the PWR. Back-end waste attributes for SNF disposition vary, but the differences have a limited impact on long-term repository isolation. SMR designs can vary significantly in SNF volume (and thus heat generation density). However, these differences are amenable to design optimization for handling, storage, transportation, and disposal technologies. Nuclear waste attributes from decommissioning vary depending on design and decommissioning technology choices. Given the analysis results in this study and assuming appropriate waste management system and operational optimization, there appear to be no major challenges to managing SMR nuclear wastes compared to the reference PWR.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.4
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• pp.355-367
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• 2017

The decommissioning of Kori unit 1, which was permanently shut down in June of 2017, will be the first instance of the dismantling of a commercial nuclear power plant in Korea. The disposal of waste during the dismantling process accounts for a large part of the total decommissioning cost. Therefore, structures consisting of activated and contaminated concrete must be economically and safely dismantled by establishing a proper dismantling strategy. This study focuses on optimized dismantling and disposal scenarios pertaining to a biological shield. Several dismantling cases, regulations and technologies related to waste treatment as these practices pertain to nuclear power plants are analyzed. To minimize the amount of waste from the biological shield dismantling process, an optimized dismantling scenario is presented and disposal alternatives for dismantled concrete waste are proposed.

• Journal of Radiation Protection and Research
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• v.38 no.2
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• pp.91-99
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• 2013

There are many reasons for decommissioning of cyclotron such as not only age-related deficiency, any serious wear or damage but also relocation, upgrade and changing mission. Decommission of cyclotron in USA and EU give rise to a lot of low-level radioactive waste and costs. Various research on decommissioning of particle accelerator have been carried to reduce the cost of decommissioning in USA and EU. In USA, the NRC require DFP (Decommissioning Funding Plan) to authorized licenser by 10 CFR Part 30.35. To resolve radioactive waste problem and reduce the estimated cost of cyclotron decommissioning, we should consider technical aspects (decommissioning procedures, decontamination techniques, etc.) and safety aspects(residual radioactivity, the expected dose, etc) for decommissioning. In this study, we analyzed practical information on the decommissioning of cyclotron in ANL (Argonne National Laboratory) and Belgium (EU). And we investigated the experience on the cyclotron relocation from SNUH (Seoul National University Hospital) to SKKU (Sungkyunkwan University). From these results, we provide the basic data for establishing of relevant standards on domestic cyclotron decommissioning. It is necessary to adopt the DFP for safe and economic decommissioning and waste recycling. These result could be utilized for the establishment on the standards and useful requirements.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.20 no.1
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• pp.99-110
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• 2022

In decommissioning a nuclear power plant, numerous concrete structures need to be demolished and decontaminated. Although concrete decontamination technologies have been developed globally, concrete cutting remains problematic due to the secondary waste production and dispersion risk from concrete scabbling. To minimize workers' radiation exposure and secondary waste in dismantling and decontaminating concrete structures, the following conceptual designs were developed. A micro-blast type scabbling technology using explosive materials and a multi-dimensional contamination measurement and artificial intelligence (AI) mapping technology capable of identifying the contamination status of concrete surfaces. Trials revealed that this technology has several merits, including nuclide identification of more than 5 nuclides, radioactivity measurement capability of 0.1-10⁷ Bq·g^-1, 1.5 kg robot weight for easy handling, 10 cm robot self-running capability, 100% detonator performance, decontamination factor (DF) of 100 and 8,000 cm²·hr^-1 decontamination speed, better than that of TWI (7,500 cm²·hr^-1). Hence, the micro-blast type scabbling technology is a suitable method for concrete decontamination. As the Korean explosives industry is well developed and robot and mapping systems are supported by government research and development, this scabbling technology can efficiently aid the Korean decommissioning industry.

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.52-62
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• 2023

Various decontamination technologies have been developed for removing contaminated areas in industries. Although it is important to consider parameters such as safety, cost, and time when selecting the decontamination technology, till date their comparative study is missing. Furthermore, different decontamination technologies influence the decontamination effects in different ways. Therefore, this study compares different decontamination techniques for the steam generator using a multicriteria decision-making method. A steam generator is a large device comprising both low- and very low-level waste (LLW, VLLW) and reflects the difference in weights of the standards according to the classification of the waste. For LLW and VLLW decontaminations, chemical oxidizing reduction decontamination (CORD) and decontamination grit blasting were used as the preferred techniques, respectively, considering the purpose of decontamination differs based on the initial state of waste. An expert survey revealed that safety in LLW and waste minimization in VLLW exhibited high preference. This evaluation method can be applied not only to the comparison between each process, but also to the creation of process scenarios. Therefore, determining the decontamination approach using logical decision-making methods may improve the safety and economic feasibility of each step in the decommissioning process and ensure a public acceptance.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2018.05a
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• pp.321-322
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• 2018