Coupled Radiation-Thermal Degradation of Polymeric Systems in Nuclear Plants: Data-driven Tools to Predict Damage Accumulation & Early Failures

Life-time prediction and reliability of materials performance under combined radiation-thermal environments is of significant interest in nuclear industry. By developing a modular platform for systematic coupling of different damage models, the project aim to develop customizable physics-based predictive tools to describe damage accumulation and eventually damage capacity in elastomers that are concurrently exposed to a combination of mechanical and environmental stressors in high radiation dose. In our proposed framework, our goal is to predict the static fatigue through accumulation of the mechanical damages and environmental damages induced by concurrent thermal and radiation aging. In view of the complexity of defining mapping space for such coupled damage mechanisms, no model exists that can even consider two of those phenomena concurrently and that's the main advantage of our proposed technology. Using the NetP modular platform developed by MSU, this project provides software to describe and couples the effects of decay due to coupled thermal-radiation loads on elastomers. Deriving the environmental-mechanical damage as the static fatigue, we will bridge our model to a failure model to calculate the remaining damage capacity of the matrix in terms of cyclic fatigue variables, such as time-to-failure or cycles to failure. The coupling of the NetP platform and failure model will be carried out in our Nord2 framework software which will be eventually released into the MOOSE multi-physics solver developed by DOE. The objective is to develop two predictive tools to describe damage accumulation and failure in elastomer systems exposed to coupled thermal-radiation aging. To show the feasibility of such platform, we implement models of the mechanical, thermal and radiation damages into the Netp platform in Phase I, couple the platform to a failure model to develop the Nord2 framework, and validate it against experiment published by Sandia National lab. The proposed hybrid framework is a more rigorous, history-dependent, extensible based on location and environment, implementable based on continuum mechanics approach and portends a transformational change in damage predictive approaches. In view of the modular design of the proposed platform, other essential damage behaviors such as diffusion limited oxidation can be later integrated into this platform, and used concurrently in simulation of the elastomer behavior under thermomechanical boundary conditions. Model used in the platform can be updated/modified or replaced for any compound, and only onetime training is needed once the platform is assembled.