[2N01-05] Liquid Breeders, Solid Breeders

[2N01] Corrosion resistance of JLF-1 steel and its alloying elements in molten FLiNaK salt with hydrogen fluoride solution

*Gaku Yamazaki¹, Takuya Nagasaka^1,2, Yukinori Hamaji^1,2, Teruya Tanaka², JingJie Shen^1,2 (1. SOKENDAI, 2. NIFS)

Keywords:Corrosion, RAFM steel, Molten salt, Liquid blanket, Electrochemistry

Molten fluoride salts used as blanket coolants request the good compatibility with structural materials. Hydrogen fluoride isotopes produced by neutron irradiation are well-known oxidants but cause unclarified corrosion in detail.

This study electrochemically measures the corrosion process in situ by simulating the environment in which JLF-1 steel (Fe-9Cr-2W-0.1C) immerses into molten FLiNaK (LiF-NaF-KF) salt with hydrogen fluoride solution. The corrosion of its alloying elements, of which the corrosion of JLF-1 steel consists, is also investigated.

JLF-1 steel increases its electric potential with time, suggesting the oxidation of Fe²⁺to Fe³⁺. Further, potential fluctuation and surface hollows characterize pitting corrosion. W keeps noble potential and records little weight loss without any pitting corrosion. Thus, W in steels may increase the corrosion resistance for hydrogen fluoride.