During the heat treatment step of High Temperature Gas-Cooled Reactor (HTGR) fuel beads, the /sup 233/U-loaded fuel beads are exposed to temperatures as high as 1700/sup 0/C. Since /sup 233/U fuel beads unavoidably contain a small percentage of /sup 232/U, decay products of /sup 232/U might be released during the heat treatment step. To avoid shielding requirements, experiments were conducted using /sup 232/Th-loaded fuel beads rather than /sup 232/U-loaded fuel beads. Decay products of /sup 232/U and /sup 232/Th are the same after /sup 228/Th. Experimental data were obtained by monitoring the 583 and 2614 keV gamma emissions of /sup 208/Tl. Computer simulations of the decay process and experimental data were used to infer what relative amount of the daughter products was removed. The carbonization step (300 to 500/sup 0/C) has an effect on the loss of daughter products in the conversion step. Using uncarbonized fuel beads, approximately 50 percent of /sup 220/Rn was removed at 300/sup 0/C and approximately 20 percent of /sup 220/Rn was removed at 200/sup 0/C. At most, 5 percent of /sup 220/Rn was removed from uncarbonized beads at 25/sup 0/C. Marginal /sup 220/Rn loss was detected at 100/sup 0/C using pre-carbonized beads. At 1400/sup 0/C, …

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