<p style="margin: 0mm -0.05pt 0pt 0mm">Condition-based maintenance (CBM) is maintenance performed on the basis of the condition of the equipment. CBM reduces the cost of maintenance and the risk of trouble caused by unnecessary overhaul, since it is only performed at the most favorable time when indicators show signs of decreasing performance or upcoming failure. To apply CBM to industrial systems, it is important to determine condition of equipment appropriately, and a large amount of data (especially in abnormal conditions) is needed. In nuclear power plant, however, it is quite difficult to obtain it. For this reason, simulation is expected to be an effective approach to evaluate conditions of equipment instead of data acquisition. By simulating abnormal conditions of equipment in advance, it is possible to identify abnormal behavior quantitatively and consider countermeasures against it. In this study, we focused on and built a model for the equipment such as motor operated valve (MOV), since the inspection cost is generally high due to the amount of the equipment used in a nuclear power plant.</p><p style="margin: 0mm -0.05pt 0pt 0mm; text-indent: 5pt">The MOV which we consider here is a gate valve which opens and closes by a drive unit consisting of a motor and gear box. Diagnosis of equipment is generally implemented by monitoring the behavior of measurement values during its driving. In the case of the MOV, the load of its drive unit is evaluated through the measurement of the current value of a motor, the torque spring displacement, the stem thrust and so on. In abnormal condition, these measurement value could be deviated away from normal condition value. In order to appropriately determine condition of the MOV, it is necessary to identify the characteristic deviation for abnormal conditions respectively. Therefore, we perform the simulation analysis to evaluate the transient of measurement value in normal and abnormal conditions during valve moving. Our analytical results successfully reproduced its feature for each condition.</p>

Simulation for Predicting Condition of Plant Equipment

Paper Proceedings: https://asmedigitalcollection.asme.org/ICONE/ICONE28/volume/85246

2021 28th International Conference on Nuclear Engineering (ICONE28)

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