Mechanical Characterization of Unirradiated PCA-2b Zircaloy Cladding

As part of the national PHOENIX project dedicated to the medium- and long-term management of Belgian spent nuclear fuel, SCK CEN is developing a comprehensive database of material properties representative of the Belgian fuel inventory. Nuclear fuel cladding, acting as the primary barrier against radioactive release during storage, plays a critical role in ensuring safety and integrity of spent fuel.

Among the Zircaloy grades used in Belgian reactors, PCA-2b—originally fabricated by Siemens (now Framatome)—is particularly noteworthy due to the scarcity of publicly available data. In the coming years, several spent fuel rods with PCA-2b cladding will undergo extensive testing at SCK CEN. To support this future work, it is essential to establish the mechanical behavior of the unirradiated material.

Recently, pristine PCA-2b cladding samples were acquired from Framatome and are now ready for detailed analysis. This master thesis offers a unique opportunity to perform an in-depth mechanical characterization of this material. Due to their tubular shape and anisotropic mechanical properties inherited from the manufacturing process, several non-standardized test specimen geometries (for axial and hoop stress orientation) will have to be defined following the best practices in the field, together with the appropriate fixtures for the mechanical testing machines.  Optimal parametrization for the tensile/compression tests will be performed in collaboration with SCK CEN technical staff. Key mechanical properties such as yield strength, ultimate tensile strength, and ductility should be extracted from the test results. Interpretation should be supported by finite element modeling performed in ANSYS for the different geometries tested.

The work will be complementary to a related master thesis topic that will mostly focus on the microstructural and chemical analysis of the same material. Synergies between the two theses that will run in parallel should allow for a more complete characterization of this zircaloy grade and form a reference database for PCA-2b cladding, enabling comparisons with irradiated material and serve as input for the Transuranus fuel performance code, aiding predictive modeling of fuel behavior.