abstract
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Type 316H stainless steel samples were exposed to flowing FLiNaK salt for 1000 h in a monometallic thermal convection loop (TCL) with a maximum temperature of 650C and a minimum of 540C. Samples in the hottest part of the TCL lost mass, with a maximum mass loss of 1.4 mg/cm2, while samples in the coldest parts of the TCL gained mass, with a maximum mass gain of 1.0 mg/cm2. Analysis of the samples that gained mass showed an Fe-rich layer on the sample surfaces, suggesting that Fe, not Cr, accounted for the majority of the mass transfer in the TCL. However, Cr loss was apparent to a depth of ~5 m in the HL. Post-exposure analysis of the salt showed major increases in the Cr, Fe, and Mn contents. The TCL was modeled using the TRANSFORM code. Modeled values matched the experimental temperature measurements showing that TRANSFORM is capable of accurately simulating the TCL conditions.