A report of quarterly results of research and development directed towards establishing new techniques and instruments towards improving present methods for determining levels of radioactivity accurately and safely.

Summary of miscellaneous updates related to the project. This includes information on the following. Simplified equations for modeling reactor conditions. Solubility tests involving thorium, bismuth, and protactinium. various other measurements and tests involving thorium, uranium, protactinium, bismuth, aluminum, and various other salts.

Summary. At the time this project was initiated, all brazing had been confined to small retorts of ten cubic feet capacity or less. Larger assemblies were scheduled which required retorts of over 100 cubic feet capacity. Hydrogen atmospheres had given the best results, however, there was considerable reluctance to use hydrogen in these large retorts from a safety standpoint. It was thought that thru the use of PMC 2252, an argon - 2 1/2% hydrogen gas atmosphere which in non-explosive, sufficient cleaning action might be attoined without the inherent hazards encountered with hydrogen. An investigation of the argon - 2 1/2% hydrogen gas as a brazing atomosphoer

"Progress is reported on Phase II of a program for the development of a mixed fission product fueled thermoelectric generator. Materials studies are described in which bonded assemblies of bismuth telluride were life tested up to 3000 hours at 350 to 400 deg F hot junction temperature. Data were too inconsistent to define any satisfactory long-life bonding process. Further work is needed to eliminate the process variables. Insulation studies aimed at determining the thermal conductivity of various insulations with different fill gases under reduced pressures are described. Opacified aerogel powder appears to be very promising as an insulation medium for a diffuse heat source. A full- scale simulated test generator aimed at proving out the concept of a diffuse heat source for power generation is described. Progress on the construction of this electrically heated generator and its thermoelectric power converter is related.