Two methods were presented for the determination of tracer diffusion coefficients in molten salts. Both methods were based upon the diffusion of instantaneously applied infinitely-thin radioactive sources into semi-infinite one-dimensional media. In the first method, the melt was absorbed in sintered porous MgO-strips. In the second method, the melt was maintained as a so-called cylindrical thin layer with a thickness of 0.025 to 0.030cm. The tracer diffusion coefficients which were obtained (table 149) in pure molten NaCl, by using the cylindrical thin layer method were in excellent agreement with sintered porous strip data. The former method had the advantage of being independent of calibration, and was applicable to systems with relatively high vapor pressures.

K.Grjotheim, T.Naterstad, K.E.Troklep, H.A.Oye: Electrochimica Acta, 1978, 23[5], 451-6

Table 149

Diffusivity of Na in NaCl Melts