Through extensive testing in fission-reactor programs, molten Li2BeF4 is known to be compatible with graphite and with many useful structural metals. In service as a Controlled Thermonuclear Reactor blanket-coolant fluid, however, corrosion by this molten salt may be enhanced by (a) the effect of magnetically induced electric fields, (b) the consequences of chemical transmutations in the blanket, and (c) inadvertent mixing with other materials through leaks between fluid circuits. Fused salts flowing at high velocity across strong magnetic fields can experience intolerably large induced electromotive forces (emfs); measurements of emfs induced in aqueous solutions with electrical conductivities less than that of Li2BeF4 were found to obey Faraday’s law of electromagnetic induction even under highly turbulent flow conditions. Induced emfs, of course, are absent when the flow is parallel to the magnetic field lines and should be minimized by such flow conditions wherever possible. In regions where molten salt enters and leaves the blanket structure, induced emfs can be minimized by (a) dividing the flow among many small parallel pipes, (b) using ferromagnetic pipe sections, and (c) perhaps maintaining a frozen layer of salt on internal surfaces of pipe. Transmutations of lithium, beryllium, and fluorine in the blanket yield oxidants capable of corroding structural metals. Such corrosion can presumably be avoided by adding a reductant of suitable redox potential to the blanket. For example, low concentration of dissolved CeF3 or slurried beryllium should be capable of reacting with the oxidants and minimizing their deleterious effect. Leaks of steam or air through faulty pipes or heat exchangers would lead to markedly enhanced corrosion with most or all metals of interest, and leaks of alkali metals into Li2BeF4 would cause reduction of BeF2 to beryllium. Such inadvertent mixing would prove troublesome but of less consequence than similar leakage of steam or air into liquid alkali metals.
