Property Measurements of the NaCl-PuCl3 Molten Salt System
- Argonne National Laboratory (ANL), Argonne, IL (United States)
Thermal properties of several compositions of the binary NaCl-PuCl3 salt were measured to confirm the eutectic composition and provide high quality data for use by MSR developers. The PuCl3 was generated by reducing PuO2 to plutonium metal in the presence of calcium metal and then chlorinating the metallic plutonium with NH4Cl. The resulting PuCl3 was used to make seven binary NaCl-PuCl3 compositions with between 59.9 mol % PuCl3 (Salt 1) and 20.0 mol % PuCl3 (Salt 7). The eutectic temperature was measured to be 457 ± 4 °C by onset determination in DSC analyses of the seven mixtures, which is consistent with the values in the literature. Additional transitions were observed at approximately 332 and 363 °C in analyses of the PuCl3-rich compositions (Salts 1-3) at about 376 and 439 °C in analyses the Na-rich compositions (Salts 4-7). The solid state heat capacity decreased with increasing PuCl3 content. The liquid state heat capacity was measured for Salt 3 (37.4 mol % PuCl3) and Salt 4 (38.3 mol % PuCl3). A higher heat capacity was measured for Salt 4 and measurements with both salts showed a positive correlation with temperature between 520 and 730 °C. Cells fabricated from nickel and molybdenum for use in DSC measurements at high temperatures could not be adequately sealed because these materials are not sufficiently malleable, even after high temperature annealing. It is recommended that future development focus on corrosion-resistant materials that have mechanical and thermal properties similar to the commercially available gold cells, such as Pt-Rh (80–20) and pure platinum. Those materials are chemically inert, soft, and malleable like gold, but have melting temperatures higher than 1000 °C (Rakhtsaum, 2013). Use of the Pt-Rh alloy should be evaluated first based on superior machinability for making precision parts and its current use in commercial DSC high temperature crucibles. The commercial Pt-Rh cells are not hermetically sealable, but it is expected that cells made from thinner stock can be sealed.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Nuclear Energy (NE)
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 1896499
- Report Number(s):
- ANL/CFCT-22/43; 179590; TRN: US2309385
- Country of Publication:
- United States
- Language:
- English
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