b'their net effect on radial thermalAccomplishments: conductivity using transient nuclearThe THOR-C, aLEU-P2M, MOXTOP, heating and (2) determines theirTHOR-M and EPIC experiments are all power-to-melt threshold in transientat different stages of the design process. overpower ramps. This experiment isEven so, all of them have notable funded by the aLEU program. achievements. The first THOR-C experi-The remaining THOR-based experi- ment, THOR-C-1, has progressed thru ments are all concerning pre-irradiatedfabrication, testing and assembly and fuel. The THOR Mixed Oxide Transientwill be irradiated in TREAT. Included OverPower (MOXTOP) experimentin this stage has been establishing a campaign is a collaborative effort withsodium bonding procedure and molten the Japanese Atomic Energy Agencysodium encapsulation method that will (JAEA) to establish the fuel claddinginform all subsequent THOR-based mechanical interaction threshold forexperiments. Figure 3 shows techni-pre-irradiated oxide fuels for the JAEAcians performing the final torquing of JOYO reactor irradiation experiments,the THOR-C-1 capsule compression and for qualification of the same oxidefitting. Figure 4 shows the totally fueled fuels for future commercial SFRs. and sealed THOR-C-1 capsule.The THOR Metallic (THOR-M) isFabrication is underway for the iron essentially a continuation of theheat sink components for the aLEU-P2M THOR-C experiment campaign, withand MOXTOP experiments. These heat an emphasis on simulating transientsinks have precise machined features overpower and loss-of-flow events forthat are pushing the limits of electrical pre-irradiated U-19Pu-10Zr fuels. Itsdischarge machining (EDM) technology. primary objective is to test pre-irradi- These features enable high-resolution ated metallic U-Zr and U-Pu-Zr fueltemperature measurement, including alloys at power/thermal conditions21x Type K thermocouples and a extending to fuel failure using thedistributed temperature sensing (DTS) THOR capsule. Ultimately, these testsfiber for in-situ cladding and fuel will continue incomplete historicaltemperature measurement at different metal fuels testing and inform devel- axial and radial locations. The aLEU-P2M opment of fuel performance modelsand MOXTOP experiments have all and fuel safety criteria for industry. completed final design review, while the THOR-M and EPIC experiments have Finally, the THOR EBR-II Pre-Irradi- completed preliminary design review ated Conductivity (EPIC) experimentand are awaiting their final design aims to determine thermal conduc- review. One of the most significant areas tivity of pre-irradiated U-Pu-Zr fuelsof progress across these THOR experi-that are each irradiated to variousment campaigns has been establishing a burnup levels. This experiment isstandard method for simulating shaped funded by the Nuclear Science Usertransients in TREAT, specifically with Facility (NSUF) program. regards to the safety implications. This method will inform other TREAT experi-ments in the future2021|AFC ACCOMPLISHMENTS 153'