Updated Method for Modelling Concrete Cracking Due to Reinforcement Bar Corrosion

Abstract NPPs and nuclear research reactors built during the mid-20th century often have incomplete material characteristics for their concrete structures. This lack of quality records frequently leads to challenges when attempting to demonstrate safety during life extension projects or when specific finite element analysis (FEA) modelling is necessary when design regulations are updated with new or revised requirements. In the framework of long-term operation, there is limited knowledge about ageing and the structural integrity of concrete structures. In order to increase the knowledge in the field of civil structures, this paper focuses on investigating the ageing mechanisms of civil structures at NRG, Petten. It uses the previously calibrated chloride ingress model (PVP2023-105650) to determine expected internal pressure generation due to rebar corrosion within an FEA to predict concrete cracking. In the most recent paper, PVP2024-122236, an investigation into the modelling of concrete cracking due to internal rebar corrosion was conducted. Using FEA, the paper illustrated that although the cracking was relatively localised, it would accurately predict how the cracks would appear. This is important when considering the long-term operations, as concrete cracking can be caused by several mechanisms. One of the limits of the model developed in PVP2024-122236 is that it requires recalibration for each time period investigated. Given this required recalibration, the model would have limited applicability to other concrete structures. In order to change this, this paper investigates using a different method for simulating the internal pressure generation. This method would not require recalibration for each time period and would provide a continuous picture of the crack generation. The new model was compared to the original results in order to draw conclusions on the accuracy of the revised model. The new model is still limited by the information available on the concrete and the chloride ingress data.