Report for General Research September 18 to December 11, 1950 (Actinium Volume)

The purpose of the research work presented in this volume is to develop a process for the separation and purification of actinium-227 produced by neutron bombardment of radium-226 and to develop methods by which uniform films of actinium metal may be deposited on metallic surfaces. The design work on the cave structure and mechanical equipment used in the actinium separation is proceeding on schedule. As the mechanical design phase is nearing completion the emphasis is being directed toward processing equipment. The process as well as the mechanical equipment has been adapted from the research work of F. T. Hagemann and the Remote Control Group at Argonne National Laboratory. Consequently, one of the first objectives is to become familiary with the chemistry of the process and the operation of the mechanical equipment. Cold runs have been made on the T.T.A. benzene extraction using lanthanum and barium in place of actinium and radium. No difficulty with the operation was observed. The formation of precipitates was one of the difficulties encountered with the process as the precipitates carry radium. It has been found that metals such as nickel cause these precipitates to form and should, therefore, be avoided in the construction of equipment. it was also found that a T.T.A. solution exposed to 0.5 curie of polonium over a period of days develops a precipitate. Some new mechanical features hav eshown promise. The use of copper-coated glassware which will hold together even though the glass is cracked has made it possible to replace custom-built heaters with standard heating mantles. A new graphite, silicone grease mixture appears to hold up in stopcocks handling benzene and, as a result, may eliminate the necessary of entering the cave for regreasing. Tests on the preparation of dense concrete have given results which meet the shielding requirements for the cave. A strippable paint and tape combination has been studied and specified to provide for decontamination of the interior of the cave. A number of different methods for the preparation of actinium metal are being tested with lanthanum compounds. It has not been found possible to reduce lanthanum from liquid ammonia with metallic sodium. Electrolytic methods are being investigated. Preliminary work has been started in an effort to determine polarographically the reduction potential of lanthanum from various fused salts. An attempt to obtain lanthanum metal from the iodide by the DeBoer proces is also under way. Lanthanum iodide vapor is thermally decomposed at a tungsten filament and the iodine vapor pumped from the system