Corrosion performance of ferrous and refractory metals in molten salts under reducing conditions

A lithium reduction technique to condition spent fuel for disposal has been developed at the Argonne National Laboratory. There is a need to ensure adequate vessel longevity through corrosion testing and, if necessary, materials development. Several ferrous alloys and tantalum specimens were submitted to a corrosion test at 725 degrees C for thirty days in an argon atmosphere, using a lithium-chloride salt saturated with lithium metal and containing small amounts of lithium oxide and lithium nitride. The samples did not show dimensional or weight change, nor could corrosion attack be detected metallographically. The lithium-saturated salt system did not show any behavior similar to that of liquid lithium corrosion. From testing in other gas compositions, it appears that the presence of oxygen in the system is necessary to produce severe corrosion.