This report follows critical-assembly studies made to provide engineering and physics data to aid in developing the Gas Cooled Reactor Experiments.

Report discussing the survey work done at the Battelle Memorial Institute with the objective to successfully build a gas-cooled reactor.

This report follows ciritical-assembly studies on: the effect on reactivity caused by changes in axial reflector materials; the effect on reactivity and the power perturbation caused by fast safety control-blade guides; the effect of changes in fuel-element material composition; the effect of changes in fuel-elements spacing designed to produce uniform radial power-generation rates.

Abstract: "The effects of a number of ternary additions on the constitution, casting, and fabricating characteristics and the physical properties of aluminum-35 w/o uranium were investigated. Initial investigations were concerned with the effects of 3 w/o ternary additions on the microstructure and press-forging characteristics of the alloy. It was found that additions of this magnitude often introduced extrinsic phases in the alloy. At the 3 w/o level, additions of germanium, silicon, tin or zirconium inhibited the formation of UAl4 and thereby increased the content of the aluminum matrix in the alloy. It was also noted that these additions decreased the pressures required for extruding, and the tin addition also improved the homogeneity of cast shapes. Lead and palladium also improved the homogeneity of the cast material; however, neither of these was an effective inhibitor of UAl4 and free lead was detected in the alloy to which lead had been added at the ternary. From these studies it appears that tin and zirconium are as effective as silicon in enhancing the fabricating characteristics of aluminum-35 w/o uranium alloys, and may prove superior when evaluated on the bases of casting qualities and recycling characteristics."

From Abstract: "A literature survey was made of both welding and brazing methods that might be used to minimize the amount of exposed core material and provide the longest path for corrosion in the event of a defective weld in enextruded Zircaloy-2-clad uranium and uranium-2 w/o zirconium fuel elements."

Report discussing studies on changes within irradiated elemental boron, boron carbide, and zirconium diboride. Materials, methods, and experimental data are included.

This report follows a series of tests run to determine the shielding properties of beryllium oxide, conducted at the Battelle Lid-Tank Shielding Facility. Neutron and gamma penetrations through and behind beryllium oxide were measured.

From introduction: "The over-all objective of the present study was to determine the nature and extent of the present study was to determine the nature and extent of the corrosion of these materials under a variety of such storage conditions and to determine the ability of several potential protective coatings to retard this corrosion."

This report analyzes the stability and feasibility of a reflector-control system for a boiling heterogeneous reactor.

The following report summarizes the results of the laboratory-scale work and pilot-plant scale work of a salt-batch composition that reduces the hydrogen pickup by uranium rods during the beta heat treatment, and the study of the influence of humidity over the salt bath on hydrogen pickup.

From abstract: "A Method has been developed for the uniform coating of graphite tubes with carbides of niobium, tantalum, and zirconium by thermal composition of their respective halide vapors."

This report discusses tests on the preparation and cladding of hot-pressed and pressure-bonded titanium-boron. It explores the properties of titanium-boron as a control material in reactors.

From introduction: "On February 1, 1956, Batelle was awarded a contract by the Army Reactor Branch (ARB) to select, develop, and test core materials which could be used successfully in conducting a Gas Cooled Reactor Experiment (GCRE). The prime objective of the GCRE would be to evaluate small portable reactor systems for military application...The present report is concerned with the GCRE activities at Batelle during approximately the 7 months' period following the first report of this series, BMI-1133. It is primarily concerned with a detailed evaluation of the reference materials as well as of the impact of one material upon the other."

The following report studies an intermediate solid-fuel reactor system for aircraft propulsion.

Report discussing a study aimed at pinpointing the cause of banding segregation in arc-melted uranium-niobium alloys and suggesting possible methods for eliminating banding.

Report discussing a study to obtain a quantitative measurement of the movement and distribution of hydrogen among components such as magnesium metal chips, uranium tetrafluoride, and magnesium fluoride slag, similar to what would occur during a reaction in a thermite bomb.

Abstract: "The oxidation resistance of thin sheets of iron-28 w/o chromium-2.67 to 10.0 w/o alloys, nominally 0.004, 0.006, 0.008, 0.012, and 0.016 in. thick, was determined by exposure in static air for 100 hr at 2100 and 2300 F. A minimum of 3.67 and 9.37 w/o aluminum was necessary to prevent excessive oxidation of 0.004-in.-thick sheet material at 2100 and 2300 F, respectively. Correspondingly, specimens of lower aluminum content and greater thickness withstood the oxidation attack. Oxidation of iron-chromium-aluminum alloys appeared to be related to the diffusion of aluminum to surfaces of the sheet to form an adherent protective layer of Al2O3."

The following report presents neutron-flux measurements with the Mark I element, which include neutron-flux distribution and flux depression within the element.

Abstract: "In a study of the preparation and properties of delta-phase zirconium hydride it was found that large, sound bodies of the hydride can be prepared by direct combination of the elements if the rate of the reaction is retarded by limiting the supply of available hydrogen. Specimens up to 1-in. diameter were prepared using this technique. Because delta phase zirconium hydride does not readily form eutectics with iron-and nickel-base alloys below 1800 F these materials may be utilized for clodding the hydride. Delta-phase zirconium hydride is unaffected by exposure to liquid NaK or to nitrogen gas at temperatures below 1000 F. The hot hardness of delta-phase zirconium hydrid is about 130 kg per mm-2 at room temperature and 40 kg per mm-2 at 1500 F. The mean coefficient of thermal expansion (68 to 1337 F) is 6.5 x 10^-6 per deg F. The thermal conductivity varies from 5.7 Btu/(ft)(hr)(F) at 300 F to 5.1 Btu/(ft)(hr)(F) at 1300 F."

Abstract: A study has been made of the cladding of solid and powdered delta-phase zirconium hydride is both red and flat shapes with stainless steel. The program included investigations of metallurgical bonding, both with and without the sore of metallic barrier materials. Types 304 and 347 stainless steel were used for cladding material. The intermediate barrier-layer materials used were niobium, molybdenum, a combination of copper and molybdenum, and a combination of copper and niobium. The pressure-bonding techniques, involving the use of gas pressure at elevated temperatures, was employed in this study. Variable times and temperatures with a constant pressure of 10,000 poi were utilized by produce bonding. In this study, the best results were archived is cladding delta-phase zirconium hydride directly with Types 304 or 347 stainless steel. Good bonds were obtained by pressure bonding at 1600 F for 3 or 4 hr subsequent to pressure bonding at 1900 F for 1 to 2 hr at a pressure of 10,000 poi. Partial bonding was achieved between niobium and zirconium hydride and molybdeum and girconium hydride.

From abstract: "A preliminary investigation was made of techniques and materials for canning graphite to protect it for use at high temperatures in a nitrogen-oxygen atmosphere"

The following report presents neutron-flux measurements made with a concentric-cylinder element (Mark II) and includes axial, radial, and peripheral flux distributions.

From introduction: "This report deals with a part of the research and development studies which preceded the manufacture of fuel elements for the Gas Cooled Reactor Experiment (GCRE)." The studies evaluate the effects of varying the type and size of UO2 particles, stainless steel matrix powders, blending procedures, compacting pressures, sintering times, temperatures and atmospheres, roll-cladding temperatures and reduction rates, total cold reduction, and heat-treating times and temperatures has been made for UO2 stainless steel dispersion fuel elements."

"Centrifugal-casting techniques were investigated as a method of producing hollow cylindrical extrusion billets of aluminum-35 w/o uranium. Among the variables evaluated were melt temperature, mold and pouring-spout configurations, mold speed, and method of pouring. With the equipment employed it was found that the best castings were produced stilizing a pouring temperature of 2400 F, a heavy-walled steel cylinder rotating between 700 to 900 rpm for the mold and bottom-pouring technique employing a retractable pouring spout. Sound, nonporous billets 26 in. long and 5 in. in diameter were produced with a yield after machining of over 75 per cent of the original charge. The major losses occurred in the pouring spout-and-cup assembly. This loss is relatively unaffected by the casting length; and, therefore, coatings of greater length than 26 in. should results in even greater recoveries.