Corrosion of 316H Stainless Steel Specimens in Two FLiBe (LiF-BeF₂) Salt Batches

Abstract

This milestone was originally envisioned for completion in FY21 and was delayed due to the COVID-19 response and difficulties in fabricating fluoride salts. To complete the milestone, commercial FLiBe was compared to a batch of FLiBe produced by the conventional hydrofluorination process. However, the batch was stopped early due to an HF leak and the salt did not undergo the final H2 sparging. Subsequent static compatibility testing of 316H specimens in 316H capsules resulted in small mass losses for the commercial FLiBe and much larger mass losses for the 2 nd batch of FLiBe.

Corrosion of 316H Stainless Steel in Flowing FLiBe (LiF-BeF₂)

“…However, after exposure in FLiBe, mass losses were observed for most 316H specimens. The mass losses were higher than in the static capsule experiments (stars in Figure 2) [12] but are still relatively low.…”

“…Purity of the salt is reliant on purification methods which typically use the hydrofluorination process [8][9][10] developed during the 1950's and 1960's. Moving beyond static, isothermal compatibility experiments [5][6][7][11][12][13], flowing salt experiments in a thermal gradient are needed to study mass transfer, which is the major concern with potentially corrosive working fluids [13][14][15]. Historically, thermal convection loops (TCLs) [13][14][15][16][17][18][19][20] have been used as an initial assessment of compatibility before investing in a forced convection loop.…”

Density Measurements of Molten LiF–BeF2 and LiF–BeF2–LaF3 Salt Mixtures by Neutron Radiography

“…FLiBe and mixtures of LaF 3 and FLiBe in the ratios listed in Table 1 were prepared in an inert glovebox in which moisture and oxygen levels were controlled (e.g., <5 ppm of O 2 , <1 ppm of H 2 O). The FLiBe salt was purified by hydrofluorination, 23 fused, and crushed into small pieces before being loaded into vanadium sample cans for neutron radiography. 24 The lithium in the FLiBe salt was of natural isotopic abundance, 7.5% Li-6 and 92.5% Li-7.…”