Abstract
The digital rod control system (DRCS) is an important component in nuclear power plants. Thus, the structural integrity of the isolation cabinet of the DRCS should be verified, considering the seismic loading and cooling performance of the heating source of electric equipment. In general, the structural safety and functionality of the DRCS are verified through ground excitation and flow experiments. Numerical structural analysis and CFD analysis provide preliminary assessments of dynamic behavior and temperature distribution of the cabinet in order to establish guidelines for designing experiments. This also reduces time, cost, and design cycles involved in the experimentation. Response spectrum analysis was adopted in ANSYS for seismic analysis, which gives the peak response of the structure. The analysis was performed based on required response spectra (RRS), which envelop the floor response spectra (FRS). The maximum stresses are less than the allowable stresses, and the deflections meet the requirements. Electric equipment should operate within a limited temperature range for acceptable reliability. In the direct heat removal approach, six fans are installed as heat sink and air is forced through the heat sink by the fan. The cabinet and internal modules should be designed such that adequate ventilation with the fans is provided to maintain the temperature difference between the inside and outside within 5°C. Flow and thermal analyses were carried out by a CFD program, Icepak. As a result of this analysis, the number and the capacity were determined to meet the design requirement.
Highlights
According to a report of the Korea Energy Information Culture Agency, as of 2018, 449 nuclear reactors are under operation in 37 countries around the world.[1]
The structures of nuclear power plants need to be more conservatively designed than other power plants so that they can be controlled during accidents
If the digital rod control system (DRCS) does not operate normally, a serious accident may occur because the heat generated from the nuclear fuel in the nuclear power plant is not controlled
Summary
According to a report of the Korea Energy Information Culture Agency, as of 2018, 449 nuclear reactors are under operation in 37 countries around the world.[1]. Each nuclear power plant is required to operate normally without outer-wall cracks or structural damage under seismic loads.[4,5]. If the DRCS does not operate normally, a serious accident may occur because the heat generated from the nuclear fuel in the nuclear power plant is not controlled. It is necessary to evaluate the structural integrity of the isolation cabinet controlling the DRCS under seismic and high-temperature conditions. The cooling performance of the cabinet was analyzed by using ICEPAK, ANSYS CFD, which are commercial programs.[10,11] ICEPAK is an analysis program for analyzing electric devices and utilizes the finite-volume method (FVM). The structures with lumped mass, such as the electric devices installed inside the cabinet, as well as the cables and the duct, which is irrelevant to the structural integrity, were expressed by mass elements (Figure 6)
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