Technical report outlining the rate of production of modified MTR type fuel elements for the Bulk Shielding Facility has proceeded. Includes compatibility test that were started as a guide in the selection of materials suitable for fuel-element fabrication. [From Summary]

Technical report detailing expansion of the Aircraft Nuclear Propulsion at the Oak Ridge National Laboratory. Major facilities completed at this time were the Shielding Rector, the ANP Critical Facility, and the 86-in. Cyclotron. Outlines further need for radiation damage studies. [From Summary]

Technical report describing the tests on types 309, 316, and 347 stainless steel. These steels were tested for a total of 779 to 828 hours in three different synthetic waste solutions. Results shoe that the best all-around corrosion resistance to the test conditions was exhibited by 316 stainless steel, but in one solution 347 stainless steel was more resistant. [From Abstract]

From introduction: "The work described in this report was carried out as part of the feasibility study (ORNL-117) of a supercritical water reactor (SCWR) for use in nuclear propulsion of aircraft. The object of this work was to study the dynamic behavior of a particular design of supercritical water reactor. Numerical results are presented in Appendix I."

Technical report outlining the effect of strain rate on the tensile properties of thorium. It has been found that the yield strength increases slightly with increasing strain rate, and that tensile strength increases but to a less extent. Studies on the fabrication of thorium by extrusion and drawing have continued, as have studies on the extrusion cladding of thorium and uranium with zirconium. [From Summary}

Quarterly technical report including reports on chemistry of source, fissionable, and structural elements, nuclear chemistry, radio-organic chemistry, chemistry of separations processes, chemical physics, radiation chemistry, and instrumentation of the Chemistry Division of the Oak Ridge National Laboratory (ORNL). [From Abstract]

Technical report covering experiments happening on the Analytical Chemistry Division's sites at the Oak Ridge National Laboratory. Includes information on ionic analyses, radio-chemical analyses, spectrochemical analyses, service analyses, inorganic preparations, analytical chemical control of homogeneous reactor solution, optical and electron microscopy, and service analyses for the period ending September 10, 1951. Studies and happenings took place on the Analytical Chemistry Division's X-10 and Y-12 sites. [From Table of Contents, Abstract]

Calculated data and graphs describing the effects of continuous thermal-neutron irradiation of thorium, the usual method of operations of homogeneous reactors, are presented.The buildup and decay of U^233, Pa^233, other heavy isotopes, and fission products are considered on the basis of best available cross-section and fission-yield data. The effects of the heavy isotopes and fission products on neutron economy are discussed.

The Spectroscopy Research Laboratory is concerned with research and development in the fields of nuclear magnetic resonance, microwaves, infrared and optical spectroscopy, spectrochemistry, and x rays. Research is directed toward fruitful methods of isotope analysis; new element and compound analytical methods having application to immediate Laboratory or long-range commission needs; and fundamental research on isotopes, elements, and compounds. The work is reported on a project basis to give a more complete picture of the purpose, activity, and status of each program. More detailed information on reported or inactive projects may be obtained from the previous semiannual report.

The flux through a given region is proportional to the total lengths of the neutron flight paths that intersect that region. The analytical Monte Carlo procedure manufactured neutron flight paths and totaled the lengths of all paths intercepted by the regions illustrated in Figure 1. The procedure was designed to utilize the various symmetries in the lattice. / Consider a portion of the lattice whose planar cross-section is shown in Figure 5. If R is the region in which the flux is to be estimated and F the fuel rod in which the neutron originated, then flight path P results in an intercepted length whose reflection in the plane is L. On the other hand flight path P' intercepts R' with length L'. R' is not the region to be studied, but a translation of the flight path P' to F' would result in the neutron intercepting R. The origin in P was arbitrary. For each neutron originating in P another could, with equal probability, have originated in P' with parallel paths. Hence consulting L' in R' towards the total flux is equivalent to starting a neutron at P'. Thus consideration of all regions symmetric to R with respect to …

The enthalpies and heat capacities of seventeen fluoride mixtures in the liquid state have been determined using Bunsen Ice Calorimeters and copper block calorimeters. The fluoride mixtures were composed of the fluorides of two or more of the following metals: lithium, sodium, potassium, beryllium, zirconium, and uranium. The enthalpies and heat capacities of most of these mixtures were studied in the solid state also. Estimates of the heat of fusion have been made. General empirical equations have been developed which represent the enthalpies and heat capacities of the fluoride mixtures in the liquid and in the solid state.

The countercurrent gas-liquid system BF3(g)—anisole·BF3(l) for the concentration of boron isotopes has been studied. The single-storage separation factor varies from 1.039 at 0°C to 1.029 at 30°C. Rate of exchange is rapid, and, with efficient contacting equipment, complete exchange may be obtained in less than 15 sec. A total separation of 1.525 has been realized in laboratory equipment. The critical-product reflux reaction is quite efficient. Only about 55 moles of BF3 remain in each million moles of effluent solvent under laboratory conditions. The vapor pressure of BF3 over the complex rises sharply as the temperature is increased. At 0°C the pressure is 150 mm Hg, and at 40°C the pressure has risen to 1800 mm Hg. From vapor-pressure measurements, an approximate upper limit of ΔH= -12kcal per mole of complex was calculated for the reaction [equation not transcribed]. Qualitative tests indicate good resistance of anisole to decomposition by BF3 under plant conditions. The uncatalyzed exchange of boron between BF3 and BCl3 was found to be too slow to be exploited in a countercurrent system. The single-stage, equilibrium separation factor for the Nitrox system is a function of acid concentration. At 26°C the factor ranges from 1.064 with 1 M acid …

Consideration has been given to various forms of fissionable material for use in atomic reactors, including the pure metals, their alloys and compounds. Of particular interest is the dioxide of uranium which is refractory and corrosion resistant in some environments.The oxide is useful in both granular and bulk forms. Small grains of uranium oxide can be mixed with other materials to form matrix type elements where they serve either as a convenient or necessary form of fuel or fertile material. For other applications the oxide may be fabricated in bulk form such as pellets, rods, plates, or blocks.There is a need for knowledge of the properties of the properties of this oxide, particularly as it affects fabrication in the various forms required. This knowledge is also required by reactor designers and engineers. There is in addition a challenging field for basic studies of sintering rates, oxidation behavior and other phenomena. Fabrication techniques have been developed to produce uranium oxide in various forms with consideration given to the economy of production. The continued application of basic knowledge of these materials has led to simpler. more practical means of fabrication and has thus widened the scope of their use in atomic reactors.

Observations of the effects of neutron damage to zirconium oxides led to the conclusion that the cubic form of ZrO2 is more stable to such damage than the monoclinic form. It has been reported that zirconium corrodes more rapidly in certain liquids when exposure is made under radiation (neutrons and fission products). It is well known that on heating monoclinic ZrO2 a transformation, monoclinic to tetragonal (very similar to cubic), occurs at about 1500°C. The transformation involves sufficient atomic rearrangement that pieces of ZrO2 normally crack and crumble. It is suggested that the effects of neutrons on monoclinic ZrO2 may be similar so that a protective oxide film on the metal would be destroyed soon after its formation. It might be possible, therefore, that the protective oxide film on zirconium metal which is normally monoclinic might be less resistant to corrosion under radiation damage than a similar film which was cubic.

The hydrogen evolution method for the determination of uranium trifluoride which was developed by Manning, Miller and Rowan has been used for the determination of trivalent uranium in this laboratory for the past three years. The method has been applied to many different sample types supposedly pure UF3, mixtures of UF3 and UF4 and the large variety of mixtures of fluoride salts that have been investigated as possible nuclear fuels. These mixtures contained alkali metal, beryllium and zirconium fluorides. Several modifications have been made that have substantially improved the performance and ease of operation of the method. These improvements include the use of (1) an inexpensive, long-lasting source of pure carbon dioxide, (2) vacuum to assist in purging the system of gases that are insoluble in potassium hydroxide solution, (3) deaerated acid that has an extremely low quantity of non-absorbable gases, (4) slower flow rates of purging gas, (5) a sampling technique to minimize contamination, and (6) more dilute absorber solution to reduce film error. It is the purpose of this report to show the effect of these modifications and the applicability of the method various sample types that contain uranium trifluoride.