• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.21 no.4
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• pp.531-541
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• 2023

The Wolsong Nuclear Power Plant (NPP) operates an on-site spent fuel dry storage facility using concrete silo and vertical module systems. This facility must be safely maintained until the spent nuclear fuel (SNF) is transferred to an external interim or final disposal facility, aligning with national policies on spent nuclear fuel management. The concrete silo system, operational since 1992, requires an aging management review for its long-term operation and potential license renewal. This involves comparing aging management programs of different dry storage systems against the U.S. NRC's guidelines for license renewal of spent nuclear fuel dry storage facilities and the U.S. DOE's program for long-term storage. Based on this comparison, a specific aging management program for the silo system was developed. Furthermore, the facility's current practices-periodic checks of surface dose rate, contamination, weld integrity, leakage, surface and groundwater, cumulative dose, and concrete structure-were evaluated for their suitability in managing the silo system's aging. Based on this review, several improvements were proposed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.2
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• pp.147-154
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• 2001

The prestressed concrete containment is one of the most important structures in nuclear power plants, which is required to prevent release of radioactive or hazardous effluents to the environment even in the case of a severe accident. Numerical analyses are carried out by using the ABAQUS finite element program to assess the ultimate pressure capacity of the Y prestressed concrete containment with light water reactor at design criteria condition and aging condition considering varied properties of time-dependant materials respectively. From the results, it is verified that the structural capacity of the Y prestressed concrete containment building under the present, aging condition is still robust. In addition, the parameter studies for the reduction of the ultimate pressure capacity of containment building according to the degradation levels of the main structural materials are carried out. The results show that when the degradations of each materials are considered as individual and combined forms, the influence is large in the order of tendon, rebar and concrete degradation, and tendon-rebar, tendon-concrete and rebar-concrete degradation respectively.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.4
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• pp.523-530
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• 2019

Pavement distress and traffic accidents are caused by pot-hole. In addition, direct and indirect damages of road users are increasing, such as loss of life due to personal injury and damage to vehicles. Generally, the asphalt concrete pavements are continuously aging from the production process to the terminal performance period. Aging causes stripping due to cracks and moisture penetration and weakening the pavement structure to induce pot-hole. In this study, adhesion performance and moisture sensitivity were evaluated according to aging degree in order to investigate the effect of aging on asphalt pavement. As a result of the study, the viscosity of the asphalt binder was increased with aging and the bond strength of the aged was increased 2~3 times than that of the unaged. The results of accelerated aging test showed an increases in indirect tensile strength and the increase in the TSR (Tensile Strength Ratio) by 4.2~8.9 %. As a result, it is noted that the anti-stripping and adhesion performances of the aged asphalt concrete are improved compared to the unaged one under the aging conditions of asphalt binder coated on aggregates.

• Journal of the Korea Concrete Institute
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• v.14 no.4
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• pp.597-607
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• 2002

Electric arc furnace and converter slag are produced by about 6 millions tons in Korea at 2000 year. But compared with blast furnace slag, those are utilized only in unvalued material like landfill and road construction. There are unstable materials, like free CaO, in electric arc furnace and converter slag at steel-manufacturing process. This might cause volume expansion in concrete, if electric arc furnace and converter slag aggregates were used in concrete. This expansion may reach to crack or collapse of concrete. It is therefore settled by standard specification for concrete that electric arc furnace and converter slag aggregates have not to use in concrete. First of all, volume stability and stabilized process should be solved in electric arc furnace and converter slag aggregate to use in concrete. In this study, 6 types of aging are evaluated for effects of stabilization to reduce the expansion of electric arc furnace and converter slag. h converter slag aggregate, these types of aging are not good for volume stability for concrete aggregate, and even if converter slag aggregate is treated with aging, concrete with it has some problems that strength is reduced with curing days. But in electric arc furnace slag aggregate treated with hotwater and steam aging, the expansion of electric arc furnace slag aggregate is reduced about two times than that of converter slag aggregate, and electric arc furnace slag aggregate concrete has good results in strength compared with control concrete using crushed stone.

• Journal of the Korea Concrete Institute
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• v.25 no.2
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• pp.137-144
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• 2013

The use of fiber-reinforced polymer (FRP) reinforcing bars in concrete structures has been increased as an alternative of steel reinforcement which has shown greater vulnerability to corrosion problem. However, the long-term performance of concrete members with FRP reinforcement is still questioned in comparison to the used of steel reinforcement. This study presents the results of an experimental study on the long-term behaviors of GFRP (glass fiber reinforced polymer) bar reinforced concrete beams after exposed to accelerated aging in an environmental chamber with temperature of $46^{\circ}C$ ($115^{\circ}F$) and 80% of relative humidity up to 300 days. The objectives of this research was to compare strength degradation and change of ductility between GFRP reinforced concrete beams and steel reinforcement beams after accelerated aging. Two types (wrapped and sand-coated surface) of GFRP bars and steel were reinforced. in concrete beams. Test results show that the failure modes of GFRP bar reinforced concrete beams are very similar with traditional RC beams, and the change of load-carrying capacity of steel reinforcing concrete beam is greater than that of GFRP bar reinforcing concrete beam under the accelerated aging. Test result also shows that the use of GFRP reinforcing in concrete could be introduced more brittle failure than that of steel reinforcing for practical application. The deformability factor up to compression failures indicates no significant variation before and after exposure of accelerated aging.

• Geomechanics and Engineering
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• v.14 no.3
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• pp.241-246
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• 2018

The displacement monitoring data series reconstruction method was developed under equal water level effects based on displacement monitoring data of concrete dams. A dam displacement variation equation was set up under the action of temperature and aging factors by optimized analysis techniques and then the dam displacement hydraulic pressure components can be separated. Through the dynamic adjustment of temperature and aging effect factors, the aging component isolation method of dam displacement was developed. Utilizing the isolated dam displacement aging components, the dam stability model was established. Then, the dam stability criterion was put forward based on convergence and divergence of dam displacement aging components and catastrophe theory. The validity of the proposed method was finally verified combined with the case study.

• Earthquakes and Structures
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• v.3 no.5
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• pp.649-673
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• 2012

Recent studies have highlighted the importance of accounting for aging and deterioration of bridges when estimating their seismic vulnerability. Effects of structural degradation of multiple bridge components, variations in bridge geometry, and comparison of different environmental exposure conditions have traditionally been ignored in the development of seismic fragility curves for aging concrete highway bridges. This study focuses on the degradation of multiple bridge components of a geometrically varying bridge class, as opposed to a single bridge sample, to arrive at time-dependent seismic bridge fragility curves. The effects of different exposure conditions are also explored to assess the impact of severity of the environment on bridge seismic vulnerability. The proposed methodology is demonstrated on a representative class of aging multi-span reinforced concrete girder bridges typical of the Central and Southeastern United States. The results reveal the importance of considering multiple deterioration mechanisms, including the significance of degrading elastomeric bearings along with the corroding reinforced concrete columns, in fragility modeling of aging bridge classes. Additionally, assessment of the relative severity of exposure to marine atmospheric, marine sea-splash and deicing salts, and shows 5%, 9% and 44% reduction, respectively, in the median value bridge fragility for the complete damage state relative to the as-built pristine structure.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.65-68
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• 1997

In this study, we investigate the difference between natural aggregate and electric arc furnace (EAF) slag one in order to use EAF slag aggregate as coarse aggregate in concrete. We find the physical and chemical properties of EAF slag aggregate according to the different aging processes. We consider the properties of the concrete made with EAF slag aggregate on these bases.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.546-550
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• 1996

The personal-computer software program named SAMS(Structural Aging Management System) was developed for the concrete structure of NPP(Nuclear Power Plant). SAMS is constituted of three part, detabase system containing various inspection data, operation program for standard input/output of the inspection data, and application program for efficient operation of database system. Using the SAMS, the field engineers can easily acquire the information about the various inspection data, repair and accidental histories of NPP structures. SAMS will contribute to the effcient maintenance of NPP structures.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.3
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• pp.230-234
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• 2009

As concrete ages, the surrounding environment is expected to have growing influences on the concrete. As all the impacts of the environment cannot be considered in the strength-estimating model of a nondestructive concrete test, the increase in concrete age leads to growing uncertainty in the strength-estimating model. Therefore, the variation of the model error increases. It is necessary to include those impacts in the probability model of concrete strength attained from the nondestructive tests so as to build a more accurate reliability model for structural performance evaluation. This paper reviews and categorizes the existing strength-estimating statistical models of nondestructive concrete test, and suggests a new form of the strength-estimating statistical models to properly reflect the model uncertainty due to aging of the concrete. This new form of the statistical models will lay foundation for more accurate structural performance evaluation.