Pre-Transient Characterization of MLOF-1 Test Pin

This study focuses on the pre-transient characterization of U-10Zr test and sibling fuel pins for the THOR-M-LOF test series. Using neutron radiography, element contact profilometry (ECP), precise gamma scan (PGS), and gas assay, sampling, and recharge (GASR) analysis, it was confirmed that the fuel pins were intact and suitable for testing. Key fuel behaviors quantified include axial elongation, diametral strain, fluff structure geometry, axial isotope distribution, and fission gas release. Any deviations from historically expected behaviors were investigated and attributed to factors other than the irradiation behavior of the fuel pin. These pre-transient measurements establish a baseline for future post-transient analysis, which will be used to inform fuel performance models and safety criteria for sodium-cooled fast reactors (SFRs). The results will enhance understanding of transient fuel behavior and expand limited data on LOF scenarios.. Authors: Probert, Allison Roberts [Idaho National Laboratory]; Jensen, Colby B [Idaho National Laboratory] (ORCID:0000000189257758); Schulthess, Jason L [Idaho National Laboratory] (ORCID:0000000242897528). DOE Contract: AC07-05ID14517. Subjects: 11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS ; Element Contact Profilometry; Loss of Flow; Neutron Radiography; PIE; U-Zr