Solid thorium bismuthides

The only thermodynamic data for this system are those reported by Kadochnikov et al. [1974KAD/POY], who measured the emf of the cell  

These data cannot be processed further without an assumption regarding the activity of antimony in the saturated Th-Sb hquid. With the very small solubilities of Th in Sb(l), also measured by [1974KAD/POY], logio Th = -6820/r + 4.07, (giving xxh = 0.0074 at 1100 K) the activity of Sb will be very little different from the ideal value, and hence the Gibbs energy of formation of ThSb2(cr) can be calculated to be  

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X.5 Solid thorium bismuthides X.5.1 Phase diagram and structures... 

As is pointed out in Chapter 20, the easiest blanket to handle in the LMFR would be a 10 w/o thorium-bismuthide slurry in bismuth. Chemical processing of this blanket would be very similar to the core processes already described. The major problem consists in transferring the bred uranium and protactinium from the solid thorium bismuthide to the liquid bismuth phase, so that they can then be chemically processed. Two examples of proposed processes are shown in Fig. 22-11, which shows a process that can be used with the fused chloride salt FPS removal process, and in Fig. 24-19, which shows a flowsheet for a process to be used with the fluoride volatility process. 

The volatility method can be conveniently used to process a thorium bisinuthide blanket. The process must be preceded by a phase separation step which separates the thorium bismuthide solids from the liquid carrier bismuth (Fig. 24-19). The modification of the core liquid process flowsheet is as follows (1) salt effluent from the hydrofluorination step must be stored in order to achieve Pa decay to uranium, and (2) the bismuth liquid is returned to the blanket head end process without the addition of uranium. 

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