A preliminary study of molten salt power reactors was made. The most promising fuel carrier salts were the fluorides and chlorides of the alkali metals, zirconium, and beryllium. The chlorides were found to have lower melting points but were less stable and more corrosive than the fluorides. A Li/sup 7/ F- - BeF/sub 2/ mixture with ThF/sub 4/ and UF/sub 4/appeared to perform best. Of the numerous alloys tested as container material, Inconel and a nickel-- molybdenum alloy INOR-8 appeared to be the most resistant to corrosion. To study the performance, safety, economics, and construction costs of a typical molten salt reactor, a reactor of specific type and size was chosen for study. The reference design reactor was a two-region homogeneous converter with a core salt of 70 mole% Li/sup 7/F and 30% BeF/sub 2. ThF/sub 4/ and enough VF/sub 4/ for criticality were added. Study indicated that a molten salt reactor would produce economical power, but the problem of developing a salt core and a container metal which would last for many years of operation needed further study. (M.C.G.)

Run SM-2 was run to determine whether a sulfated ThO2 slurry could be handled in a hydrodynamic system similar to the HRT test blanket. It was found that the ThO2 concentration circulating in the pipes was consistently 50% or less of the expected concentration based on the quantity of the oxide changed. The run lasted 1730 hours. It was terminated because of a slurry leak a few days before a shutdown had been scheduled. Severe erosion was found in the pump impeller and flow nozzle . Chloride concentration high enough to cause concern over possible stress corrosion cracking occurred on several occasions in the pressurizer.

It is concluded that an excess of O2 must be added to the HRT fuel circulating stream in amounts sufficient to recombine the D2 in dead-end lines and serve as corrosion protection.