D.F. Torgerson Award: Small-specimen fabrication testing for irradiated materials

THE D.F. TORGERSON DISCOVERY AWARD IS AWARDED TO:

For the small-specimen fabrication testing capability development for irradiated materials.                                          

Since 2016, CNL has significantly advanced its capabilities in fabricating and testing small-scale mechanical specimens to cater to both domestic and international commercial clients, thereby enhancing its commercial revenue. Small-scale mechanical tests involve the fabrication and testing of specimens that range from millimetre to sub-millimetre sizes.

CNL has multiple advanced fabrication capabilities, namely focused ion beam (FIB) mill, laser ablation system, which are customized to produce high-quality miniature specimens from irradiated reactor components. CNL researchers have developed a FIB-based workflow to fabricate, and test micron-sized tensile specimens of specific microstructural features of interest, to directly observe deformation within ex-service materials. The results from these experiments have provided critical information for life prediction modelling of spacers, and the fracture toughness of irradiated pressure tubes.

The CNL team utilized this technique on Accident Tolerant Fuel (ATF) claddings in a project funded by Global Nuclear Fuel (GNF)-Americas, a GE-Hitachi venture. The aim was to mechanically characterize a ceramic protective coating, only a few microns thick, and its interface with zirconiumalloy- based cladding. The results from this study were shared with the US Nuclear Regulatory Commission (US-NRC) by the customer as part of the material qualification process.Experiments on shear testing of pressure tube rolled joints have been developed to address a need of Ontario Power Generation (OPG) to assess the effect of hydrogen pick-up on the mechanical integrity of the pressure tube at the ribs of the rolled joints. CNL’s team designed a small shear specimen geometry suitable for testing sub-mm sized specimens of pressure tubes. The specimen was fabricated using precision metallography and laser ablation. CNL researchers worked closely with an international meso-scale mechanical test system supplier to customize shear testing grips for miniaturized shear test specimens. Initial OPG funded developmental work has been performed on unirradiated pressure tube material in year 2023, and irradiated material testing has been planned for years 2024-25.