Assessment of Candidate Molten Salt Coolants for the Advanced High Temperature Reactor (AHTR)

Molten Salt Heat Transport Loop: Materials Corrosion and Heat Transfer Phenomena

“…XRD diffraction pattern of Cr enriched film on graphite fixturing rod from the Incoloy 800H corrosion test. The peak corresponds to Cr 7 C 3 stoichiometry, but the slight shift in the peak position in conjunction with EDS analysis indicates the film to consist of (Cr, Fe) 7 …”

“…Based on heat transfer and other considerations stated above, as well as the recent seminal work of Williams et al at ORNL on comparison of a wide range of heat transfer salts, it was decided that high temperature corrosion experiments for this research will be performed in FLiNaK. FLiNaK salt is a eutectic mixture of three fluorides, with a composition 46.5%LiF-11.5%NaF-42%KF and it has a melting point of about 454°C [7,8]. FLiNaK is well suited for the temperature range used in this research (up to 850°C), due to its low volatility (low vapor pressure) and its relative ease of handling.…”

“…The physical properties of the FLiNaK salt for analyzing the data were different in these studies. Most notably, a large variation in the accepted thermal conductivity of FLiNaK salt can be seen from the 1950's to the accepted value today [37]. In addition, each investigator used different metal containers for their tests.…”

Electrochemical Investigation on the Stable Iron Species in Molten FLINAK

“…According to the investigations described by Oak Ridge National Laboratory (ORNL) [11], the corrosion valence state of Fe in molten fluorides is determined by the acid-base properties of the molten fluoride employed; here, a Lewis acid is defined as a fluoride ion acceptor, and a Lewis base is a fluoride ion donor. Pure FLINAK consisting of LiF, NaF, and KF [LiF:NaF:KF, 46.5:11.5:42 (mol%)] is known to be a strongly basic solvent that tends to stabilize the Fe(III) valence state [11].…”

“…Pure FLINAK consisting of LiF, NaF, and KF [LiF:NaF:KF, 46.5:11.5:42 (mol%)] is known to be a strongly basic solvent that tends to stabilize the Fe(III) valence state [11]. According to the theory of non-electric transfer described by Ozeryanaya [12], Fe may firstly dissolve in FLINAK melts as a form of Fe(II), which would further convert to Fe(III).…”