This technical report is intended as a brief description of the free convection problem existing in the various annuli of the SIR Mark A rotating plugs. It is by no means a complete report of the plug "hot tests", but merely records some of the more significant experimental observations and presents a few of the theories and calculations made to explain the observed free convection phenomenon. The general discussion which follows is chronological. Details of analyses are relegated to the Appendix.

Abstract: "The spectrum of plutonium has been observed over the temperature range of 2000 to 2600 C and a wavelength coverage of 3476 to 6888 A. The spectrum was excited in a modified King furnace."

Shows coastal areas of greater-than-average radioactivity.

Due to some lack of knowledge of the energy per fission, there has been some uncertainty over the absolute power of the Bulk Shielding Reactor. This report analyzes measurements to state the absolute power of the BSR within a few percent.

During a compilation of ore reserves at Bull Canyon, it was apparent from the grade of submarginal mineralization that this material might be a low-grade reserve of importance. Mr. Lewis Hazen requested a memorandum of the results of the analysis; this memorandum is a response to that request.

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.

Discussing uranium deposits drilled at the Seven Mile Canyon in grand county, Utah.

Discussing an anomaly discovered by airborne methods.

This is an extension of the results reported in UCRL-2203, where bore diameter is determined in a linear accelerator.

At the request of the Atomic Energy Commission, a 456 pound sample of Lake Athabaska ore was shipped to this laboratory by the Radioactivity Division of the Canadian Bureau of Mines. The sample was received on March 10, 1952 and given our number 43-1. Several series of flotation tests were performed on the sample.