Engineering Database of Liquid Salt Thermophysical

Abstract

The purpose of this report is to provide a review of thermophysical properties and thermochemical characteristics of candidate molten salt coolants, which may be used as a primary coolant within a nuclear reactor or heat transport medium from the Very High Temperature Reactor (VHTR) to a processing plant; for example, a hydrogen-production plant. Thermodynamic properties of four types of molten salts, including LiF-BeF 2 (67 and 33 mol%, respectively; also known as FLiBe), LiF-NaF-KF (46.5, 11.5, and 52 mol%, also known as FLiNaK), and KCl-MgCl 2 (67 and 33 mol%), and sodium nitrate-sodium nitrite-potassium nitrate (NaNO 3 -NaNO 2 -KNO 3 , 7-49-44 mol%, also known as Hitec® salt) have been investigated. Limitations of existing correlations to predict density, viscosity, specific heat capacity, surface tension, and thermal conductivity were identified. The impact of thermodynamic properties on the heat transfer, especially the Nusselt number, was also discussed.Stability of the molten salts with structural alloys and their compatibility with the structural alloys was studied. Nickel and high temperature alloys with dense Ni coatings are effectively inert to corrosion in fluorides, but not so in chlorides. Of the chromium containing alloys, Hastelloy N appears to have the best corrosion resistance in fluorides, while Haynes 230 was the most resistant in chloride. In general, alloys with increasing carbon and chromium content are increasingly subject to corrosion by the fluoride salts FLiBe and FLiNaK due to attack and dissolution of the intergranular chromium carbide. Future research to obtain needed information was identified.

Mainstreaming commercial CSP systems: A technology review

“…Chromia-forming alloys, Fe-based and Ni-based, do not show corrosion resistance in molten chlorides. It has been reported that increasing Cr content in those alloys produced an increase in corrosion rates whereas changes in nickel content showed no effect [112].…”