Integrated Computational Modeling of Water Side Corrosion in Zirconium Metal Clad Under Nominal LWR Operating Conditions

Abstract

A mesoscopic chemical reaction kinetics model to predict the formation of zirconium oxide and hydride accumulation light-water reactor (LWR) fuel clad is presented. The model is designed to include thermodynamic information from ab initio electronic structure methods as well as parametric information in terms of diffusion coefficients, thermal conductivities and reaction constants. In contrast to approaches where the experimentally observed time exponents are captured by the models by design, our approach is designed to be predictive and to provide an improved understanding of the corrosion process. We calculate the time evolution of the oxide/metal interface and evaluate the order of the chemical reactions that are conducive to a t 1/3 dependence. We also show calculations of hydrogen cluster accumulation as a function of temperature and depth using spatially dependent cluster dynamics. Strategies to further cohesively integrate the different elements of the model are provided.

Structure, Kinetics, and Thermodynamics of Water and Its Ions at the Interface with Monoclinic ZrO2 Resolved via Ab Initio Molecular Dynamics

“…For the purpose of comparison, the same simulations are also performed for bulk water of 256 water molecules with no ZrO 2 surface with a density of 0.98 g/cm 3 . For the bulk water calculation, one configuration is used for neutral, H + , and OH − calculations, respectively.…”

“…Understanding water properties at oxide interfaces is fundamentally important for a wide range of electrochemical applications such as in corrosion, − photochemical water splitting, − and heterogeneous catalysis. − Interfacial water structure is distinct from that of bulk, and the dissociative configurations of water at the oxide surface determine the energetic barrier of various reactions of interest, such as proton incorporation, oxygen evolution reaction, and hydrogen evolution reaction − and at oxide/water interfaces including the oxides CeO 2 , ZnO, TiO 2 , , Fe 2 O 3 , MgO, Co 3 O 4 , Al 2 O 3 , and cubic ZrO 2 .…”

Kinetic Model of Incipient Hydride Formation in Zr Clad under Dynamic Oxide Growth Conditions

“…Here, we assume a capillary approximation for e b [55,56]: e b (n) = e s − 0.44 n 2 3 − (n − 1) 2 3 with e s being the heat of solution of H in the α-Zr matrix. This parameter has been found to be approximately 0.45 eV in electronic structure calculations [95,96], compared to 0.66 eV in experiments [97].…”

“…Models based on hydrogen supersaturation of the α-Zr metal [52][53][54] assume a binary partition of hydrogen in the clad, either as solid solution or as part of precipitates without specification of their size, number, or orientation. Detailed cluster dynamics (CD) modeling offers a more accurate alternative to obtain hydride size distributions and number densities by solving the complete set of differential balance equations with one-dimensional spatial resolution [55,56]. Phase field methods can capture extra detail by furnishing the shape and orientation of hydrides in addition to concentrations and sizes [27,57,58].…”

Initial Verification and Validation Assessment for VERA

“…The most current PCI CP Implementation plan does not include any V&V requirements and the phenomenological requirements are substantially similar to those presented in Table 21. [25] discusses a handful of lower-length-scale simulations and hypothesizes that these could be used to inform continuum level modeling for PCI. The authors believe that these type of upscaling techniques are still in the research realm and are excluded from the current description of requirements.…”