• Nuclear Engineering and Technology
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• v.55 no.11
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• pp.4252-4265
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• 2023

In the case of nuclear power plants near end of their design life, a reassessment of the performance of safetyrelated equipment may be necessary to determine whether to shut down or extend the operation of the power plant. Therefore, it is necessary to evaluate the level of performance decline due to degradation. Electrical cabinets, including MCC and switchgear, are representative safety-related equipment. Several studies have assessed the degradation and seismic performance of nuclear power plant equipment. Most of those researches are limited to individual components due to the size of safety-related equipment and test equipment. However, only a few studies assessed the degradation performance of electrical cabinets. The equipment of various nuclear power plants is anchored to concrete foundations, and crack in concrete foundations is one of the most representative of degradation that could be visually confirmed. However, it is difficult to find a study for analysis through testing the effect of cracks in concrete foundations on the response of electrical cabinet internal equipment fixed by anchors. In this study, using a simple cabinet model considering cast-in-place anchor in uncracked and cracked concretes, a tri-axial shaking table tests were performed and the seismic behavior were observed.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.10a
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• pp.186-192
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• 1999

Safety-related equipments of nuclear power plant must be seismically qualified to demonstrate their ability to function as required during and/or after the earthquake, The seismic qualification is usually achieved through analysis and testing. Analysis method is preferably adopted for structurally simple equipments which are easy to be mathematically modeled. However even for relatively complex equipments analysis method is occasionally used for computing the input motion or supporting information for the component test followed. Electrical cabinet is a typical example for which analysis method is combinedly used with test to get modal properties of the enclosing cabinet structure. Usually the structural elements and doors of the cabinet are loosely interconnected with small-size bolts or spot welding. Therefore cabinet-type equipment usually has high and complex nonlinear properties which are not easily idealized by simple practical modeling techniques. in this paper with respect to a typical cabinet-type structure(instrumentation cabinet of nuclear power plant) a comparative study has been performed between three different state-of-the -art modeling techniques: lumped mass model frame model and FEM modal. Form the study results it has been found that modal properties of the cabinet-type structure in the elastic behavior range can be reasonably computed through any type of modeling techniques in the practice with slight modification of model properties to get better accuracy. However it needs additional modeling techniques to get reasonable results up to nonlinear range.

• Nuclear Engineering and Technology
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• v.53 no.9
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• pp.3100-3111
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• 2021

Numerical modeling for the safety-related equipment used in a nuclear power plant (i.e., cabinet facilities) plays an essential role in seismic risk assessment. A full finite element model is often time-consuming for nonlinear time history analysis due to its computational modeling complexity. Thus, this study aims to generate a simplified model that can capture the nonlinear behavior of the electrical cabinet. Accordingly, the distributed plasticity approach was utilized to examine the stiffness-degradation effect caused by the local buckling of the structure. The inherent dynamic characteristics of the numerical model were validated against the experimental test. The outcomes indicate that the proposed model can adequately represent the significant behavior of the structure, and it is preferred in practice to perform the nonlinear analysis of the cabinet. Further investigations were carried out to evaluate the seismic behavior of the cabinet under the influence of the constitutive law of material models. Three available models in OpenSees (i.e., linear, bilinear, and Giuffre-Menegotto-Pinto (GMP) model) were considered to provide an enhanced understating of the seismic responses of the cabinet. It was found that the material nonlinearity, which is the function of its smoothness, is the most effective parameter for the structural analysis of the cabinet. Also, it showed that implementing nonlinear models reduces the seismic response of the cabinet considerably in comparison with the linear model.

• Earthquakes and Structures
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• v.23 no.3
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• pp.245-257
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• 2022

This study is a basic study on the seismic reinforcement method of anchors of fixed parts in order to reduce the effect of seismic motion that affects the facilities in the event of an earthquake. By applying the test method of ICC ES AC 156, a seismic simulation experiment was performed on the vibration table with three axes simultaneously using the number of connecting bolts between cabinets and channels as a parameter. In addition, the reliability of the experiment was verified using numerical analysis, and the part about the dynamic characteristics that could not be performed according to the experimental limit was investigated through numerical analysis. As a result of the experiment, it was confirmed that the natural frequency of the main body was increased due to the increase in the number of connecting bolts between the cabinet-channel. Accordingly, it was judged that the rigidity of the lower part of the cabinet was increased due to seismic reinforcement. It was analyzed that the impact delivered to the body was effectively reduced. In the future, if the reinforcement of the connection parts mentioned in this study is added to the existing seismic reinforcement of the electrical cabinets, it is expected that the damage to the electrical cabinets of the power plant equipment caused by an earthquake will be effectively reduced.

• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.926-939
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• 2022

The area of this study will cover the location-wise seismic response variation of an electrical cabinet in nuclear power point (NPP) based on classical reliability analysis. The location-based seismic ground motion (GM) selection is carried out with the help of probabilistic seismic hazard analysis using PSHRisktool, where the variation of reliability analysis can be understood from the relation between the reliability index and intensity measure. Two different approaches such as the first-order second moment method (FOSM) and Monte Carlo Simulation (MCS) are helped to evaluate and compare the reliability assessment of the cabinet. The cabinet is modeled with material uncertainty utilizing Steel01 as the material model and the fiber section modeling approach is considered to characterize the section's nonlinear reaction behavior. To verify the modal frequency, this study compares the FEM result with recorded data using Least-Squares Complex Exponential (LSCE) method from the impact hammer test. In spite of a few investigations, the main novelty of this study is to introduce the reader to check and compare the seismic reliability assessment variation in different seismic locations and for different earthquake levels. Alongside, the betterment can be found by comparing the result between two considered reliability estimation methods.

• Nuclear Engineering and Technology
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• v.52 no.6
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• pp.1318-1326
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• 2020

Structural modification in the electrical cabinet is investigated by a proposed procedure that comprises of an experimental, analytical and numerical solution. This research emphasizes the linear dynamic analysis of the cabinet that is studied under the seismic excitation to demonstrate the real behavior of the cabinets in NPP. To this end, an actual electric cabinet is experimentally tested using an impact hammer test which reveals the fundamental parameters of the cabinet. The Frequency-domain decomposition (FDD) method is used to extract the dynamic properties of the cabinet from the experiment which is then used for numerical modeling. To validate the dynamic properties of the cabinet an analytical solution is suggested. The calibrated model is analyzed under the floor response obtained from the Connecticut nuclear power plant structure excited by Tabas 1978 (Mw 7.4) earthquake. Eventually, the grouping effect of the cabinets is proposed which represents the influence on the dynamic modification. This grouping of the cabinets is described more sophisticatedly by the theoretical understating, which results in a significant change in the seismic response. Considering the grouping effects will be helpful in the assessment of the real seismic behavior, design, and performance of cabinets.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.291-292
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• 2007

This paper deals with the design of control cabinet based on safety PLC for Control Rod Control System(CRCS). The CRCS controls the operation of the CRDMs(Control Rod Drive Mechanisms). The CRDM moves the control rods which regulate the reactor power. vertically in the reactor core. The Control Cabinet in CRCS makes and conveys control signals to the power cabinet which provides power to the CRDM. We designed the Control Cabinet, based on POSAFE-Q, safety PLC. The application programs working in PLC can be programmed by pSET(POSAFE-Q Software Engineering Tool), Identified Development Environment.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1630-1631
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• 2007

This paper deals with the design of control cabinet based on safety PLC for reactor power control system(PCS). The PCS controls the operation of the CEDMs(Control Element Drive Mechanisms). The CEDM moves the CEAs(Control Element Assemblies) which regulates the reactor power, vertically in the reactor core. The Control Cabinet in PCS makes and conveys control signals to the power cabinet which provides power to the CEDM. We designed the Control Cabinet, based on POSAFE-Q, safety PLC. The application programs working in PLC can be programmed by pSET, Identified Development Environment.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.4
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• pp.123-128
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• 2010

In this paper, in order to reduce the electric disaster damage which is caused by with electric equipment of traditional markets, we developed cabinet panel and the electric safety monitoring system which is able to monitor the electrical equipments condition(over current, leakage, arc, WH, electrical fire factor etc.) at traditional markets. We constructed Test-bed for testing reliability of electric safety monitoring system and the actual condition investigation about electrical equipment of traditional market. This paper will be used with the data for an actual demonstration project after reinforcing problems which are occurred to operation of traditional market actual loads.

• Journal of the Earthquake Engineering Society of Korea
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• v.23 no.5
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• pp.279-288
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• 2019

Safety-related cabinets and their electrical parts, such as relays and switches in nuclear power plants, should maintain continuous functioning, as well as structural safety according to the nuclear regulatory guidelines. Generally, an electrical part is qualified if its functioning is maintained without abnormality during excitement by motion compatible with the test response spectrum, which is larger than its in-cabinet response spectrum (ICRS). ICRS can be determined by shake-table test or dynamic analysis. Since existing cabinets in use can hardly be stopped and moved, dynamic analysis is preferred over shake-table test in determining ICRS. The simple method, suggested by the Electric Power Research Institute (EPRI) to determine ICRS, yields conservative or non-conservative results from time to time. In order to determine that the ICRS is better than EPRI method in a simple way, Ritz method considering global and local plate behaviors was suggested by Gupta et al. In this paper, the Ritz method is modified in order to consider the rocking and frame behaviors simultaneously, and it is applied to a simple numerical example for verification. ICRS is determined by Ritz method and compared with the results by finite element method (FEM). Based on this numerical example, recommendations for using Ritz method are suggested.