b'Figure 2. HERA-PreH-4 rodlet inspection during experiment disassembly. The arrows point to locations for the four thermocouples that were found still attachedduring experiment disassembly.legend shows all the participants These two experiments targetedand their respective code used along 700 J/gUO 2fuel radial averagewith the peak values predicted. All enthalpy increases. The future testscodes do a good job predicting the planned in TREAT will target highersame peak radial average enthalpy enthalpy targets to fail the fuel rods.value, but the evolutions vary The first experiment at NSRRmainly due to differences in thermal targeted 625 J/gUO 2fuel radialhydraulic models between codes and average enthalpy increase and didusers. Figure 4 shows failure predic-not appear to cause failure. Detailedtions for the NSRR and TREAT cases. post-transient examinations areA value greater than unity means in progress for this specimen. Thethe code predicts that failure would second NSRR experiment was justoccur. Most codes predict that the completed with a targeted enthalpyNSRR case would fail whereas not of 725 J/gUO 2 . many codes predicted the TREAT case would fail. There was a lot of participation inAs-run simulations using as-built the modeling and simulation exer- dimensions and conditions for cise. A wide array of participantsthe experiments will be run once and fuel performance codes usedpost-transient examinations of the provides a good estimation of theexperiments are complete. This variability of possible results duringexercise will be a valuable tool for a specific experiment. The modelingcode validation.and simulation exercise included 14 cases with variations in energy depo- References:sition, cladding hydrogen content,[1.]D. Kamerman (2023) Formation and fuel-cladding gap. The nominaland characterization of hydride case for NSRR focused on a 7.5 msrim structures in Zircaloy-4 FWHM pulse targeting 650 J/gUO 2 nuclear fuel cladding Journal peak fuel radial average enthalpyof Nuclear Materials Vol 586. rise with 400 ppm hydrogen contenthttps://doi.org/10.1016/j.in the cladding. The TREAT hadjnucmat.2023.154675identical conditions but with a 90 ms FWHM pulse. Figure 3 shows the fuel radial average enthalpy result for the NSRR and TREAT cases. The 100 2023|AFC ACCOMPLISHMENTS'