• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.9 no.3
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• pp.181-189
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• 2011

The smooth construction and operation of nuclear facilities requires understanding and support of both the local residents and the national people. It is essential that our country, which should maintain using nuclear energy for national energy security and economic growth, shall improve the social acceptance of nuclear energy. In order to identify the level of social acceptance of nuclear energy, this study investigated the perception of the local residents in Gyeongju and the public in other areas on a nuclear power plant and a low- and intermediate-level radioactive waste disposal facility through an individual interview. The subjects of the investigation were 450 persons. This study identified that perceptions of the respondents were somewhat dependent on the residential area, and derived the implications to be reflected in establishing the customized public-relation strategies.

• Nuclear Engineering and Technology
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• v.53 no.5
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• pp.1524-1533
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• 2021

The structural stability of a waste package is essential for containing radioactive waste for the long term in a repository. A silo-type disposal facility would require more severe verification for the structural integrity, because of radioactive waste packages staked with several tens of meters and overburdens of crushed rocks and shotcretes. In this study, structural safety was analyzed for a silo-type repository, located approximately 100 m below sea level in Gyeongju, Korea. Finite element simulation was performed to investigate the influence of the loads from the backfilling materials and waste package stacks on the mechanical stress of the disposed of wastes and containers. It was identified that the current design of the waste package and the compressive strength criterion for the solidified waste would not be enough to maintain structural stability. Therefore, an enhanced criterion for the compressive strength of the solidified waste and several reinforced structural designs for the disposal concrete container were proposed to prevent failure of the waste package based on the results of parametric studies.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.3
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• pp.183-190
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• 2022

The construction of an underground silo structure was the first stage of erecting the Gyeongju low-and-intermediate-level radioactive waste disposal facility. The facility, completed in 2014, has a scale of 100 000 drums and is currently in operation. The underground silo structure, 25 and 50 m in diameter and height, respectively, consists of cylindrical (for storing waste packages) and dome parts. The dome is divided into lower (connected to the operation tunnel) and upper parts. The wall of the underground silo structure is an approximately 1-m-thick reinforced concrete liner. In this study, finite element analysis was performed for each phase of the construction sequence and operation of the underground silo structure. Two-dimensional axial symmetric finite element analysis was implemented using the SMAP-3D program. Three-dimensional finite element analysis was also performed to examine the reliability of the two-dimensional axial symmetric finite element model. The structural behavior of the underground silo structure was predicted, and its structural safety was examined.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.211-220
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• 2005

The concrete structure is being considered for the main engineered barrier of low and intermediate level radwaste disposal facility. Concrete of low permeability can minimize infiltration of water and effectively prevent release of nuclide to ecosystem. But if concrete degrades, structural stability of disposal structure will decrease while permeability increase, resulting in increased possibility of nuclide release due to water infiltration. Therefore disposal concrete structure degradation shall be minimized to maintain capacity of nuclide isolation. The typical causes of concrete structure degradation are sulfide attack, reinforcement corrosion due to chloride attack, leaching of calcium hydroxide, alkali-aggregate reaction and repeated freezing-thawing. The common cause of these degradation processes is infiltration of water or adverse chemicals into concrete. Based on the study of these degradation characteristics and mechanisms of concrete structure, the methodology of design and service life evaluation of concrete structure as an engineered barrier are reviewed to ensure its long-term durability.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.4
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• pp.435-446
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• 2021

This article examines the consequences of a significant spent fuel management decision or event in the United States, South Korea and Taiwan. For the United States, it is the financial impact of the Department of Energy's inability to take possession of spent fuel from commercial nuclear power companies beginning in 1998 as directed by Congress. For South Korea, it is the potential financial and socioeconomic impact of the successful construction, licensing and operation of a low and intermediate level waste disposal facility on the siting of a spent fuel/high level waste repository. For Taiwan, it is the operational impact of the Kuosheng 1 reactor running out of space in its spent fuel pool. From these, it draws six broad lessons other countries new to, or preparing for, nuclear energy production might take from these experiences. These include conservative planning, treating the back-end of the fuel cycle holistically and building trust through a step-by-step approach to waste disposal.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.1
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• pp.57-64
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• 2012

Since a seismic exceeding design load can result in exposing radioactive material during disposal process of radioactive wastes, the repository should be designed with enough seismic margin. In this paper, a seismic fragility analysis was performed to evaluate the seismic capacity of surface facility structures. According to the analysis results, since inspection & store facility and radioactive waste facility have a rectangle geometry, the seismic capacity was differently presented about 23%~43% according to the axis of structures. The HCLPF capacity of inspection & store facility and radioactive waste facility was 0.52g and 0.93g, respectively. And it was observed that seismic capacity of radioactive waste facility was similar to that of a containment for nuclear power plants.

• The Journal of Engineering Geology
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• v.26 no.1
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• pp.79-85
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• 2016

A concrete silo plays an important role in subsurface low- and intermediate-level waste facilities (LILW) by limiting the release of radionuclides from the silo geosphere. However, due to several physical and chemical processes the performance of the concrete structure decreases over time and consequently the concrete loses its effectiveness as a barrier against groundwater inflow and the release of radionuclides. Although a number of processes are responsible for degradation of the silo concrete, it is determined that the main cause is corrosion of the reinforcing steel. Therefore, the time it takes for the silo concrete to fail is calculated based on two factors: the initiation time of corrosion, defined as the time it takes for chloride ions to penetrate through the concrete cover, and the propagation time of corrosion. This paper aims to estimate the time taken for concrete to fail in a LILW disposal facility. Based on the United States Department of Energy (DOE) approach, which indicates that concrete fails completely once 50% of the volume of the reinforcing steel corrodes, the corrosion propagation time is calculated to be 640 years, which is the time it takes for corrosion to penetrate 0.640 cm into the reinforcing steel. In addition to the corrosion propagation time, a diffusion equation is used to calculate the initiation time of corrosion, yielding a time of 1284 years, which post-dates the closure time of the LILW disposal facility if we also consider the 640 years of corrosion propagation. The electrochemical conditions of the passive rebar surface were modified using an acceleration method. This is a useful approach because it can reduce the test time significantly by accelerating the transport of chlorides. Using instrumental analysis, the physicochemical properties of corrosion products were determined, thereby confirming that corrosion occurred, although we did not observe significant cracks in, or expansion of, the concrete. These results are consistent with those of Smartet al., 2006 who reported that corrosion products are easily compressed, meaning that cracks cannot be discerned by eye. Therefore, it is worth noting that rebar corrosion does not strongly influence the hydraulic conductivity of the concrete.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.2
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• pp.119-131
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• 2020

A numerical model was developed using COMSOL Multiphysics to evaluate groundwater flow that causes radionuclide migration in the unsaturated zone of a near-surface disposal facility, which is considered as a domestic low and an intermediate-level radioactive waste disposal facility. Each scenario was modeled by constructing a two-dimensional domain that included the disposal vault, backfill, disposal cover, and unsaturated aquifer. A comparison of the continuous and intermittent rainfall conditions exhibited no significant difference in any of the factors considered except the wave pattern of water saturation. The input data, such as porosity and residual water content of the unsaturated aquifer, were observed to not have a significant effect on the groundwater flow. However, the hydraulic conductivity of the unsaturated aquifer was found to have a significant effect on the groundwater flow. Therefore, it is necessary to assess the hydraulic conductivity of an unsaturated aquifer to determine the extent of groundwater infiltration into the disposal vault.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.4
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• pp.279-291
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• 2005

To support the design concept and the performance assessment of the cover system for low- and intermediate-level radioactive waste(LILW) disposal facility, a pioneering study is conducted for the tomb of historical age. Research status of the art are investigated and the characteristics of tomb cover are summarized based on the preservation status of historical remains. On-site soil samples are prepared and their unsaturated hydraulic conductivities are measured by an one-step outflow method. Visiting the excavation site of historical tomb and communication with Korean archeological society are required for the further understanding and for the extension to the radioactive waste disposal research.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.4
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• pp.311-324
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• 2013

To ensure the reliability of computer programs used for the post-closure safety assessment in the Wolsong LILW Center, the results from MASCOT, SAFE-ROCK and GOLDSIM programs are compared with a problem for degradation. Advantages and disadvantages of each computer programs are individually analyzed. Effects on the individual dose are assessed with each computer programs. MASCOT and SAFE-ROCK showed similar results for $^{129}I$ and $^3H$. However, GOLDSIM represented different results for $^{129}I$ and $^3H$. It is analyzed further and compared with the fluxes in each barrier of the disposal system. Througout the benchmarking testing of the computer program, the limitation of computer program can be continuously found out for the mature post-closure safety of Korean radwaste disposal system.