Synthesis and thermophysical property determination of NaCl-PuCl3 salts

Currently, a knowledge gap exists in the available data and understanding of thermophysical properties relating to fresh fuel salts, especially those containing plutonium. These data are necessary for designing, constructing, and licensing future commercial molten-salt reactors. Thermophysical properties, such as melting temperature, salt stability, density, and heat capacity were ascertained using NaCl-PuCl3 (36 mol% PuCl3) and a more sodium rich composition containing 25 mol% PuCl3. The NaCl-PuCl3 salt mixture was synthesized for this study and contained 63.4 mol% NaCl, 36.3 mol% PuCl3 and was 99.7% pure. Upon heating, the NaCl-PuCl3 eutectic was stable at temperatures up to 800 degrees C. The onset of melting occurred at 451 +/- 3 degrees C, and the enthalpy of fusion was determined to be 23.0 +/- 1.4 kJ/mol. Heat capacity measurements in the liquid phase ranged from 107.7 to 91.3 J/mol.K, with an average value of 104.6 +/- 11.4 J/mol.K between 500 and 650 degrees C. Three independent trials of the molten NaCl-PuCl3 salt found the density to be.(T) = 3.8589 - 9.5342 center dot 10(-4) T(.C). In addition, ab initio molecular dynamic simulations to calculate density and heat capacity values are included.

Automated summary

There is currently a lack of knowledge and data on the thermophysical properties of fresh fuel salts containing plutonium. These properties are crucial for the future development of commercial molten-salt reactors. The study investigated the melting temperature, salt stability, density, and heat capacity of NaCl-PuCl3 salt mixtures. The results provided important insights for reactor design and licensing.