AbstractLoop studies have been made on UO2-NaK slurries at temperatures up to 1050°F. The maximum UO2concentration was 4.15 volume per cent or 35 weight per cent at room temperature. A flow rate of 5.4 ft/sec was required to suspend all of the UO2in this slurry at 1050°F. Lesser flow rates were required at lower temperatures. It was discovered that by installing a static cold trap, which was joined vertically upward from the lower horizontal leg of the loop, the slurry became more stable at the higher temperatures. The function of the cold trap is thought to be that of removing, from the circulating slurry, oxygen contamination which may have rendered previous attempts to maintain a stable suspension above 932°F unsuccessful. In the present study, the UO2could be easily resuspended after prolonged settling.