Preludium NCN K. Suchorab
MSc. Eng. Kinga Suchorab leads a PRELUDIUM 23 research project funded by NCN. The project investigates the complex degradation mechanisms of nuclear fuel claddings. Her work, entitled "Impact of stress and stoichiometry level on the oxidation kinetics of zirconium alloys", addresses critical challenges in nuclear reactor safety at a pivotal time as Poland moves forward with its Nuclear Power Programme, implementing AP1000 reactor technology to enhance energy security and reduce greenhouse gas emissions.
At the heart of this investigation lies the intricate behaviour of zirconium alloys. These materials are used for fuel claddings, serving as the second barrier against radioactive releases, effectively isolating the fuel and fission products from the coolant. Despite their suitable properties, these claddings face degradation challenges due to oxidation processes, where two oxide polymorphs form: a protective but metastable tetragonal phase and a problematic monoclinic phase that leads to accelerated oxidation. The project specifically examines how these alloys respond to oxidation under various conditions, with particular attention to the formation and stability of protective oxide layers.
The research methodology is divided into two main experimental phases. The first phase focuses on samples oxidised without external stress, while the second investigates the impact of applied stress during oxidation. In both phases, a comprehensive analytical approach is employed, starting with careful sample preparation. The analysis combines in-situ and cross-section Raman spectroscopy measurements to track phase transformations in real-time and across the oxide layers. Grazing Incidence X-Ray Diffraction provides detailed structural information about the formed oxides. The microstructural characterisation is performed using complementary microscopy techniques: Scanning Electron Microscopy (SEM) for surface and cross-sectional analysis, and Transmission Electron Microscopy (TEM) for high-resolution imaging of the metal-oxide interface and grain size determination. Additionally, Laser-Induced Breakdown Spectroscopy (LIBS) is utilised to determine stoichiometry of both oxides phases. This systematic approach, executed over a planned 24-month period, aims to unravel the intricate relationships between stress, grain size, and stoichiometry in oxide formation and stability.
