From 1995 sites in the San Juan Mountains area, 1706 water and 1982 sediment samples were collected during June-July 1976 and analyzed for uranium. The area includes the southern third of the Colorado mineral belt which has yielded rich ores of gold, silver, copper, lead, zinc, and molybdenum. The broadly domed mountains are capped by 2500 m of Tertiary volcanics, deeply eroded to expose a Precambrian crystalline core. Adjacent plateaus underlain by Mesozoic sedimentary rocks were included in the reconnaissance. Average value of uranium in water samples from mountains was less than 0.5 parts per billion, from plateaus was 1-2 parts per billion, from Mancos shale areas exceeded 2 parts per billion. Anomalous sediment samples, 40 ppm uranium, came from near Storm King Mountain and upper Vallecito Creek. Other anomalous areas, including the Lake City mining district, were well defined by 4-30 parts per million uranium in sediment and 3-30 parts per billion uranium in water. Anomalous areas not previously reported indicate favorable areas for future exploration.

From introduction: This report presents data gathered in a Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) conducted by the Los Alamos Scientific Laboratory (LASL) in southwestern Montana. The HSSR was initiated by the US Department of Energy (DOE) to outline areas favorable for uranium exploration by examining uranium concentrations in natural waters and stream sediments.

This report provides uranium and other elemental data resulting from the Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) of the La Junta quadrangle, Colorado.

Experimental techniques are described for the spectral measurement of a collimated fast neutron beam. A hydrogen filled cloud chamber, proton recording nuclear plates, and threshold fission foils were used as neutron detectors in the measurements. As an application of the above technique, the energy distribution and absolute flux of the fast neutron beam emerging from port 5W of the Los Alamos fast rector has been measured from 0.1 Mev to 18 Mev. The result show a spectral curve possessing a maximum between 9.25 and 0.30 Mev and having an exponential decrease at energies above 1.5 Mev. The mass energy of the distribution is at 0.55 Mev and the slope of the exponential section is 3.1 - 0.1 Mev per decade of intensity decrease.

The usual method of removing surface oxide from plutonium metal samples, by electrolytic cleaning in a mixture of ethylene glycol and phosphoric acid, is not satisfactory for preparing samples for oxygen determination. Samples prepared in this way give erratic oxygen values. This report describes a new method of electrolytic cleaning, using a 20 ~ aqueous potassium carbonate solution as the electrolyte. The sample is placed in a rotating tantalum cup which is made the anode. Electrolysis for two minutes at 4.5 volts is usually sufficient. Samples cleaned by the new method give lower and more consistent oxygen results than those prepared in the old way. The new method is also neater and more convenient.

A new method for the determination of O/sub 2/ in metals is described. The sample is dropped into molten Pt in a graphite crucible. The oxide in the sample reacts with C to form CO, which is swept out by a stream of argon at atmospheric pressure. The CO is oxidized to CO/sub 2/, which is condensed in a capillary trap and measured with a capillary manometer. The apparatus is sensitive to 0.3 mu g of O/sub 2/, and routine 50-mg Pu samples give a standard deviation of 7 ppm or 0.35 mu g. Pu samples with added O/sub 2/ gave a standard deviation of 1.5 mu g or 2% of the total oxygen, with no significant bias. The apparatus is simple and rugged permitting replacement of parts without glassblowing. The speed is superior to vacuum fusion methods, most samples requiring only twelve minutes for analysis.

Magnesium oxide reduction crucibles have been developed that increase the processing efficiency of uranium and plutonium production. The characteristics of the crucibles are described.

A modification of the specimen support for the Norelco diffractometer permits X-ray diffraction studies to be made of specimens prepared for metallographic examination. The unit has been successfully used to identify phases present in specimens of plutonium-uranium alloys.

High purity, homogeneous uranium-molybdenum alloys have been made successfully in the reduction bomb. The preparation of the alloys and some of their properties are described.

High purity, homogeneous alloys of uranium and columbium have been produced by adding powdered columbium metal or columbium/sub 2/O/sub 5/ to a regular reduction charge. Alloys up to 20.0 at.% columbium were produced. The preparation of the alloys, some of their properties, and casting results are described.

A high-vacuum casting furnace with an internal diameter of 15 inches has been designed, fabricated, and installed at LASL. The furnace was designed to accommodate casting crucibles up to 7 inches OD; however with a larger diameter heating element, casting crucibles up to 9 inches could be accommodated. This report describes the basic features of the furnace and presents engineering drawings of both the furnace and the furnace box.

The proposed Los Alamos Omega West Reactor is designed to be a research tool delivering a maximum neutron flux of approximately 5 x 10/sup 13/ n/sec/cm/ sup 2/ at its maximum operation power level of 5 megawatts. Solid fuel elements of the type developed for the Materials Testing Reactor will be utilized. Cooling will be accomplished with circulating demineralized water and evaporative coolers. Experimental facilities will include numerous horizontal ports, two of which will incorporate built-in rotary beam shutters, and a thermal column. If all the radioactive material contained in the fuel elements during normal reactor operation were to become spread through the residential area of Los Alamos, persons in some parts of the city would be exposed to greater than lethal doses. It does not appear that known mechanisms could operate to produce this situation. Because of geographical relationships and low ground-water flow velocities, there seems to be no likelihood of water supply contamination in the event of a reactor disaster. Care has been taken in the reactor design to insure against sudden draining of the main reactor tank containing the fuel assembly, as such a sudden loss in cooling might lead to damage of the fuel elements. Conservative …

This technical report describes a plant-scale procedure for concentrating plutonium and americium in slag and crucible (metal reduction residues) and other recovery solutions by a calcium oxalate carrier precipitation Conclusions from exploratory laboratory tests on the variables affecting the efficiency are included.

A class of critical assemblies has been considered in which the core consists of an oralloy bearing gas at more or less standard pressure and temperature and the reflector is an efficient moderator with a small thermal capture cross section. Age and diffusion theory have been applied to compute the probability that a fast neutron is thermalized by the reflector and them captured by the core. It is first assumed that fast or epithermal neutrons do not interact wit the core and it is later shown that this assumption should be a good one for many cases. The reflector may be a thick spherical shell. It is shown that oralloy masses of a few kilograms can be critical within thick reflectors of D2O, Be, C or combinations thereof. Curves are attached which enable one to estimate critical configurations.

Radiochemically determined mass-yield curves are given for the fission of U235 and U236 by 14.7-Mev neutrons.

A new method to procure RaLa sources was proposed by Group CMR-10, Los Alamos Scientific Laboratory. This method depended upon irradiation of small-diameter U235 wire in the Materials Testing Reactor, Arco, Idaho. A procedure for cladding and sealing U235 wire in stainless steel tubing, by drawing, plugging the tube ends, and welding, was developed, tested, and proved to be satisfactory.