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Ha, Jaechul,Son, Yuhwa,Cho, Chunhyung Korean Radioactive Waste Society 2020 방사성폐기물학회지 Vol.18 No.4
Numerical model was developed that simulates radionuclide (3H and 14C) transport modeling at the 2nd phase facility at the Wolsong LILW Disposal Center. Four scenarios were simulated with different assumptions about the integrity of the components of the barrier system. For the design case, the multi-barrier system was shown to be effective in diverting infiltration water around the vaults containing radioactive waste. Nevertheless, the volatile radionuclide 14C migrates outside the containment system and through the unsaturated zone, driven by gas diffusion. 3H is largely contained within the vaults where it decays, with small amounts being flushed out in the liquid state. Various scenarios were examined in which the integrity of the cover barrier system or that of the concrete were compromised. In the absence of any engineered barriers, 3H is washed out to the water table within the first 20 years. The release of 14C by gas diffusion is suppressed if percolation fluxes through the facility are high after a cover failure. However, the high fluxes lead to advective transport of 14C dissolved in the liquid state. The concrete container is an effective barrier, with approximately the same effectiveness as the cover.
Yuwhwa Son,Jachul Ha,Chunhyung Cho,Hyunchul Kwon 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.2
Gyeongju radioactive waste repository has been operated to dispose low and intermediate level radioactive waste in Korea since 2016. Currently, only deep geological disposal facility (1st) is in operation, surface disposal facility (2nd) is scheduled to operate from 2024. As a result, the annual amount of radioactive waste that can be disposed of at deep geological disposal facilities and surface disposal facilities is almost determined. According to this result, it was possible to derive the total annual disposal amount to dispose of all radioactive waste at the Gyeongju repository after landfill disposal facility (3rd) construction. To evaluate it, a predictive model has been designed and radioactive waste generation, storage, and disposal data were input. The predictive model is based on system dynamics, which is useful to analyze the correlation between input variables. As a result of analysis, radioactive waste generation amount and maximum annual radioactive waste disposal were predicted to reach 741,615 drum and 17,030 drum per year respectively. From these results, it seems that the expansion of radioactive waste acceptance system or temporary storage is necessary.
Proposal for the Composition of the Waste Profile (Draft) for Large Package of Decommissioning Waste
Hoseog Dho,Hyungoo Kang,Yeseul Cho,Chunhyung Cho 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.2
The decommissioning waste generated during the dismantling of a nuclear power plant has various types and radioactivity levels and is characterized by being generated in a large amount in a short time. For the safe and efficient management of decommissioning waste with these characteristics, the Korea Radioactive waste Agency (KORAD) is developing a large container for decommissioning waste. And the Waste Certification Program (WCP) requirement was developed for the development of a Waste certification program for nuclear power plant operators that can prove whether the transfer/ acceptance criteria are satisfied at the step of generation of decommissioning waste packages. The radioactive waste profile, which is a waste quality certification document required by the WCP requirements, allows the KORAD to confirm that the disposition suitability evaluation was performed for each process of decommissioning waste and radiological characteristic data were evaluated appropriately. Therefore in this study, in order to propose a draft of a radioactive waste profile for large packages of decommissioning waste, overseas cases and the draft radioactive waste profile of the WCP requirements was analyzed. In addition, it was attempted to increase the utility of the derived waste profile by clearly suggesting the treatment methods for each waste stream considering the physical and radioactive characteristics evaluation methods of large decommissioning waste packages. The proposed large decommissioning waste profile can be used in the future development of a nuclear power plant operator’s decommissioning waste certification program, as well as KORAD’s a disposal facility safety evaluation and improvement of the waste tracking management system (WTS).
Desing and Development of Monitoring System for Near-surface Disposal Facility Engineering Barrier
Seho Choi,Hyungoo Kang,Mijin Kwon,Chunhyung Cho 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.1
The disposing method of the low-intermediate-level radioactive waste, near-surface disposal facilities are generally used. This disposal method refers to a method of constructing a concrete structure on the surface of the ground, putting radioactive waste in it, and covering it with an engineered barrier to isolate human life. Among these, engineered barriers mean covering multiple layers of heterogeneous materials such as sand, clay, and gravel. Engineering barriers have the purpose of delaying the release of radioactive materials into the natural environment as much as possible, and maintaining the isolation of radioactive waste and human life for as long as possible. In this study, the design and construction method of the facility to demonstrate the performance of the engineered barrier that isolates the surface disposal facility from nature was described. In addition, the design and construction method of monitoring technology that can monitor the safety of engineered barriers by measuring information such as moisture, temperature, and slope safety in real time was also explained.
A Study on the Performance Improvement and Analysis Method of the LILW Disposal Container Cover
Hyungoo Kang,Hoseog Dho,Hyeonwoo Oh,Jungwoo Jo,Yeseul Cho,Chunhyung Cho 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.1
Radioactive waste disposal facility in Korea, radioactive waste packaged in 200 L drums is placed in a concrete disposal container and disposed of at an underground silo type (cave) disposal facility. At this time, the disposal container cover is seated on the top of the disposal container, and if the disposal container and the cover are not completely combined, the container cover is raised up from the top of the disposal container, so safety problems may occur when stacking the disposal container. Therefore, various methods exist to secure a margin for the pure height inside the disposal container. The disposal container cover only covers the upper surface of the container to shield radiation, and structural performance is not required. Therefore, the method of processing the cover, such as a method of making the cover of the disposal container thin, is the easiest method to apply. In this study, a method to reduce the thickness of the cover of a concrete disposal container was devised, and structural performance under usability conditions such as lifting and seating was analyzed. In addition, the disposal container cover has a reinforced concrete form in which dissimilar materials (concrete and steel) are combined, an integrated analysis was performed to secure the reliability of the analysis results for this, and the analysis results were described. It was found that the proposed disposal container cover structure can improve usability by reducing the stress concentration phenomenon.