b'3.4 AR FUEL SAFETY TESTINGPost-Transient Characterization of the Metal FuelTHOR-C-2 ExperimentPrincipal Investigator: Jason Schulthess, Colby JensenTeam Members/Collaborators: Aaron Craft, William Chuirazzi, Allison ProbertThe THOR-C-2 testT he Transient Heatsink Over-power Response (THOR) irradiation capsule was demonstrated a newdeveloped to measure time dependent capability to testthermal behavior of advanced reactor fast reactor fuels tofuels by subjecting them to accident failure and provides anconditions in Transient Reactor Test ideal demonstrationFacility (TREAT). The THOR-C-2 test of advanced non- was the first test in this capsule to test destructive capability toa fuel pin to failure and is part of a evaluate fuel behaviorcommissioning series of tests planned. for new and valuableAdvanced non-destructive examina- Figure 1. Measured reactor power and data streams. tion was performed on the materialenergy for the THOR-C-2 experimentafter the transient using neutronthe fuel pin and time of clad rupture. computed tomography (nCT). THOR-C-2 was irradiated in TREAT THOR-C-2 Project Description:in August 2022 and contained an To address needs to continue nuclearunirradiated experimental breeder CompositionU-10Zr heated-safety research and transientreactor (EBR)-II Mk-IV fuel pin that Fuel lengthtesting of modern reactor fuels, theexperienced severe transient over (nominal)34.3 cmTREAT facility officially restartedpower conditions, establishing both a Element length74.7 cmin 2017 and planned to revive thetie-back case to historical testing and (nominal)planned M-8 experiment to be housedpower-coupling measurements for Fuel Diameter 4.3 mmin a newly designed sodium-envi- calorimetric calibration factors for CladdingHT-9 ronment module, the THOR capsule.metallic fuels.The THOR capsule was developedAccomplishments: Cladding OD5.8 mmto measure time-dependent thermalThe experiment was assembled with behavior of sodium fast reactor (SFR)an unirradiated EBR-II Mk-IV fuel pin, Cladding thickness0.45 mmand light water reactor fuel pinsassembled into the THOR capsule, and Plenum / Fuel vol1.45 subjected to accident conditionsirradiated in TREAT. The specifics of within TREAT. The THOR-commis- the fuel pin are contained in Table 1 Smear density75% sioning tests were devised to establishwith the target transient conditions Plenum gas He the performance of the test device andshown in Figure 1. After irradiation, explore fresh metallic fuel perfor- the experiment was transported to Initial Fill Gas0.1 MPa at RT mance. These tests will determinethe Neutron Radiography Reactor Pressure the capsules capacity to measure and Heat Sink Material Ti64 detect the behavior of fresh SFR fuelwhere both standard radiography during severe accident conditions,and digital nCT were completed. The Table 1. Geometry and specificationsincluding heat-sink temperature nearstandard radiography identified two for Mk-IV fuel pin used in THOR-C-2 regions of interest in the fuel pin with 174 2023|AFC ACCOMPLISHMENTS'