During a feasibility study of auxiliary shutdown systems for the Spert II and Spert III reactor facilities, salts possessing high neutron absorption cross sections were considered for use in water soluble poison injection systems, and gadolinium nitrate appeared promising. Tests were carried out in a high pressure static autoclave to determine the stability of gadolinium nitrate solution at elevated temperature. At temperatures of 300 deg F and above, the solution decomposed with formation of a white precipitate. It was concluded that gadolinium nitrate is unsuitable for use as a soluble poison in high temperature, watermoderated reactor systems. (auth)

The uranium isotope compositions of samples from l5 ores were compared to a standard. Variations of about O.l% of the U/sup 235/ content were observed. (auth)