In scouting tests, a number of metals used in nuclear reactor fuel elements were dissolved by 44.5-48.5-7.0 mole % ZrF4-KF-NaF fused salt at 675°C through which HF was being passed. These included type 304 stainless steel at 4 mils/hr; type 347Nb stainless steel at 7 mils/hr; thorium at 14 mils/hr; nonirradiated uranium at 17 mils/hr; zirconium at 22-35 mils/hr; titanium at 31 mils/hr; and Zircaloy-2 at 22-46 mils/hr. Only small amounts of volatile fission products formed when irradiated uranium was dissolved. Variables that appear to affect the dissolution rate are the composition of the fused fluoride, the fused fluoride temperature, the HF flow rate, the metallurgical characteristics of the material being dissolved, and the presence of other metals. The low dissolution rate of 0.001 mil/hr observed for nickel suggests that it may be suitable as a material of construction for reaction vessels.